| blob | d48391dc05c37df1f609b2be0838372b7a678573 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /*@@ This file should be rewritten to use an arbitrary precision
23 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
24 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
25 @@ The routines that translate from the ap rep should
26 @@ warn if precision et. al. is lost.
27 @@ This would also make life easier when this technology is used
28 @@ for cross-compilers. */
30 /* The entry points in this file are fold, size_int_wide and size_binop.
32 fold takes a tree as argument and returns a simplified tree.
34 size_binop takes a tree code for an arithmetic operation
35 and two operands that are trees, and produces a tree for the
36 result, assuming the type comes from `sizetype'.
38 size_int takes an integer value, and creates a tree constant
39 with type from `sizetype'.
41 Note: Since the folders get called on non-gimple code as well as
42 gimple code, we need to handle GIMPLE tuples as well as their
43 corresponding tree equivalents. */
65 /* Nonzero if we are folding constants inside an initializer; zero
66 otherwise. */
69 /* The following constants represent a bit based encoding of GCC's
70 comparison operators. This encoding simplifies transformations
71 on relational comparison operators, such as AND and OR. */
89 };
109 HOST_WIDE_INT *,
145 /* Similar to protected_set_expr_location, but never modify x in place,
146 if location can and needs to be set, unshare it. */
150 {
156 {
159 }
161 }
164 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
165 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
166 and SUM1. Then this yields nonzero if overflow occurred during the
167 addition.
169 Overflow occurs if A and B have the same sign, but A and SUM differ in
170 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
171 sign. */
172 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
173 \f
174 /* If ARG2 divides ARG1 with zero remainder, carries out the division
175 of type CODE and returns the quotient.
176 Otherwise returns NULL_TREE. */
178 tree
180 {
184 /* The sign of the division is according to operand two, that
185 does the correct thing for POINTER_PLUS_EXPR where we want
186 a signed division. */
200 }
201 \f
202 /* This is nonzero if we should defer warnings about undefined
203 overflow. This facility exists because these warnings are a
204 special case. The code to estimate loop iterations does not want
205 to issue any warnings, since it works with expressions which do not
206 occur in user code. Various bits of cleanup code call fold(), but
207 only use the result if it has certain characteristics (e.g., is a
208 constant); that code only wants to issue a warning if the result is
209 used. */
213 /* If a warning about undefined overflow is deferred, this is the
214 warning. Note that this may cause us to turn two warnings into
215 one, but that is fine since it is sufficient to only give one
216 warning per expression. */
220 /* If a warning about undefined overflow is deferred, this is the
221 level at which the warning should be emitted. */
225 /* Start deferring overflow warnings. We could use a stack here to
226 permit nested calls, but at present it is not necessary. */
228 void
230 {
232 }
234 /* Stop deferring overflow warnings. If there is a pending warning,
235 and ISSUE is true, then issue the warning if appropriate. STMT is
236 the statement with which the warning should be associated (used for
237 location information); STMT may be NULL. CODE is the level of the
238 warning--a warn_strict_overflow_code value. This function will use
239 the smaller of CODE and the deferred code when deciding whether to
240 issue the warning. CODE may be zero to mean to always use the
241 deferred code. */
243 void
245 {
247 location_t locus;
252 {
258 }
269 /* Use the smallest code level when deciding to issue the
270 warning. */
279 else
282 }
284 /* Stop deferring overflow warnings, ignoring any deferred
285 warnings. */
287 void
289 {
291 }
293 /* Whether we are deferring overflow warnings. */
295 bool
297 {
299 }
301 /* This is called when we fold something based on the fact that signed
302 overflow is undefined. */
304 static void
306 {
308 {
311 {
314 }
315 }
318 }
319 \f
320 /* Return true if the built-in mathematical function specified by CODE
321 is odd, i.e. -f(x) == f(-x). */
323 static bool
325 {
327 {
361 }
363 }
365 /* Check whether we may negate an integer constant T without causing
366 overflow. */
368 bool
370 {
373 tree type;
383 {
388 }
389 else
394 }
396 /* Determine whether an expression T can be cheaply negated using
397 the function negate_expr without introducing undefined overflow. */
399 static bool
401 {
402 tree type;
411 {
416 /* Check that -CST will not overflow type. */
427 /* We want to canonicalize to positive real constants. Pretend
428 that only negative ones can be easily negated. */
446 /* -(A + B) -> (-B) - A. */
451 /* -(A + B) -> (-A) - B. */
455 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
465 /* Fall through. */
478 /* In general we can't negate A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. But if overflow is
481 undefined, we can negate, because - (INT_MIN / 1) is an
482 overflow. */
490 /* Negate -((double)float) as (double)(-float). */
492 {
496 }
500 /* Negate -f(x) as f(-x). */
506 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
508 {
514 }
519 }
521 }
523 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
524 simplification is possible.
525 If negate_expr_p would return true for T, NULL_TREE will never be
526 returned. */
528 static tree
530 {
532 tree tem;
535 {
536 /* Convert - (~A) to A + 1. */
552 /* Two's complement FP formats, such as c4x, may overflow. */
562 {
571 }
593 {
594 /* -(A + B) -> (-B) - A. */
598 {
602 }
604 /* -(A + B) -> (-A) - B. */
606 {
610 }
611 }
615 /* - (A - B) -> B - A */
627 /* Fall through. */
631 {
640 }
648 /* In general we can't negate A / B, because if A is INT_MIN and
649 B is 1, we may turn this into INT_MIN / -1 which is undefined
650 and actually traps on some architectures. But if overflow is
651 undefined, we can negate, because - (INT_MIN / 1) is an
652 overflow. */
654 {
659 {
666 }
669 {
676 }
677 }
681 /* Convert -((double)float) into (double)(-float). */
683 {
687 }
691 /* Negate -f(x) as f(-x). */
694 {
700 }
704 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
706 {
711 {
718 }
719 }
724 }
727 }
729 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
730 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
731 return NULL_TREE. */
733 static tree
735 {
737 location_t loc;
750 }
751 \f
752 /* Split a tree IN into a constant, literal and variable parts that could be
753 combined with CODE to make IN. "constant" means an expression with
754 TREE_CONSTANT but that isn't an actual constant. CODE must be a
755 commutative arithmetic operation. Store the constant part into *CONP,
756 the literal in *LITP and return the variable part. If a part isn't
757 present, set it to null. If the tree does not decompose in this way,
758 return the entire tree as the variable part and the other parts as null.
760 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
761 case, we negate an operand that was subtracted. Except if it is a
762 literal for which we use *MINUS_LITP instead.
764 If NEGATE_P is true, we are negating all of IN, again except a literal
765 for which we use *MINUS_LITP instead.
767 If IN is itself a literal or constant, return it as appropriate.
769 Note that we do not guarantee that any of the three values will be the
770 same type as IN, but they will have the same signedness and mode. */
772 static tree
775 {
782 /* Strip any conversions that don't change the machine mode or signedness. */
791 /* We can associate addition and subtraction together (even
792 though the C standard doesn't say so) for integers because
793 the value is not affected. For reals, the value might be
794 affected, so we can't. */
797 {
803 /* First see if either of the operands is a literal, then a constant. */
816 /* If we haven't dealt with either operand, this is not a case we can
817 decompose. Otherwise, VAR is either of the ones remaining, if any. */
822 else
825 /* Now do any needed negations. */
832 }
835 else
839 {
846 }
849 }
851 /* Re-associate trees split by the above function. T1 and T2 are
852 either expressions to associate or null. Return the new
853 expression, if any. LOC is the location of the new expression. If
854 we build an operation, do it in TYPE and with CODE. */
856 static tree
858 {
864 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
865 try to fold this since we will have infinite recursion. But do
866 deal with any NEGATE_EXPRs. */
869 {
871 {
884 }
886 {
889 }
893 }
897 }
898 \f
899 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
900 for use in int_const_binop, size_binop and size_diffop. */
902 static bool
904 {
911 {
920 }
925 }
928 /* Combine two integer constants ARG1 and ARG2 under operation CODE
929 to produce a new constant. Return NULL_TREE if we don't know how
930 to evaluate CODE at compile-time.
932 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
934 tree
936 {
938 tree t;
941 bool is_sizetype
949 {
968 /* It's unclear from the C standard whether shifts can overflow.
969 The following code ignores overflow; perhaps a C standard
970 interpretation ruling is needed. */
1005 /* This is a shortcut for a common special case. */
1010 {
1016 }
1018 /* ... fall through ... */
1024 {
1027 }
1030 {
1033 }
1042 /* This is a shortcut for a common special case. */
1047 {
1052 }
1054 /* ... fall through ... */
1075 }
1078 {
1081 /* Propagate overflow flags ourselves. */
1084 {
1087 }
1088 }
1089 else
1095 }
1097 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1098 constant. We assume ARG1 and ARG2 have the same data type, or at least
1099 are the same kind of constant and the same machine mode. Return zero if
1100 combining the constants is not allowed in the current operating mode. */
1102 static tree
1104 {
1105 /* Sanity check for the recursive cases. */
1116 {
1118 REAL_VALUE_TYPE d1;
1119 REAL_VALUE_TYPE d2;
1120 REAL_VALUE_TYPE value;
1121 REAL_VALUE_TYPE result;
1125 /* The following codes are handled by real_arithmetic. */
1127 {
1138 }
1146 /* Don't perform operation if we honor signaling NaNs and
1147 either operand is a NaN. */
1152 /* Don't perform operation if it would raise a division
1153 by zero exception. */
1159 /* If either operand is a NaN, just return it. Otherwise, set up
1160 for floating-point trap; we return an overflow. */
1169 /* Don't constant fold this floating point operation if
1170 the result has overflowed and flag_trapping_math. */
1178 /* Don't constant fold this floating point operation if the
1179 result may dependent upon the run-time rounding mode and
1180 flag_rounding_math is set, or if GCC's software emulation
1181 is unable to accurately represent the result. */
1191 }
1194 {
1195 FIXED_VALUE_TYPE f1;
1196 FIXED_VALUE_TYPE f2;
1197 FIXED_VALUE_TYPE result;
1202 /* The following codes are handled by fixed_arithmetic. */
1204 {
1221 }
1228 /* Propagate overflow flags. */
1232 }
1235 {
1244 {
1255 mpc_mul);
1269 mpc_div);
1270 /* Fallthru ... */
1276 {
1277 /* Keep this algorithm in sync with
1278 tree-complex.c:expand_complex_div_straight().
1280 Expand complex division to scalars, straightforward algorithm.
1281 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1282 t = br*br + bi*bi
1283 */
1284 tree magsquared
1288 tree t1
1292 tree t2
1299 }
1300 else
1301 {
1302 /* Keep this algorithm in sync with
1303 tree-complex.c:expand_complex_div_wide().
1305 Expand complex division to scalars, modified algorithm to minimize
1306 overflow with wide input ranges. */
1312 {
1313 /* In the TRUE branch, we compute
1314 ratio = br/bi;
1315 div = (br * ratio) + bi;
1316 tr = (ar * ratio) + ai;
1317 ti = (ai * ratio) - ar;
1318 tr = tr / div;
1319 ti = ti / div; */
1330 }
1331 else
1332 {
1333 /* In the FALSE branch, we compute
1334 ratio = d/c;
1335 divisor = (d * ratio) + c;
1336 tr = (b * ratio) + a;
1337 ti = b - (a * ratio);
1338 tr = tr / div;
1339 ti = ti / div; */
1351 }
1352 }
1357 }
1361 }
1364 {
1376 {
1379 /* The trailing elements can be empty and should be treated as 0 */
1382 else
1383 {
1386 }
1390 else
1391 {
1394 }
1398 /* It is possible that const_binop cannot handle the given
1399 code and return NULL_TREE */
1404 }
1406 }
1408 }
1410 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1411 indicates which particular sizetype to create. */
1413 tree
1415 {
1417 }
1418 \f
1419 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1420 is a tree code. The type of the result is taken from the operands.
1421 Both must be equivalent integer types, ala int_binop_types_match_p.
1422 If the operands are constant, so is the result. */
1424 tree
1426 {
1435 /* Handle the special case of two integer constants faster. */
1437 {
1438 /* And some specific cases even faster than that. */
1440 {
1445 }
1447 {
1450 }
1452 {
1455 }
1457 /* Handle general case of two integer constants. */
1459 }
1462 }
1464 /* Given two values, either both of sizetype or both of bitsizetype,
1465 compute the difference between the two values. Return the value
1466 in signed type corresponding to the type of the operands. */
1468 tree
1470 {
1472 tree ctype;
1477 /* If the type is already signed, just do the simple thing. */
1485 else
1488 /* If either operand is not a constant, do the conversions to the signed
1489 type and subtract. The hardware will do the right thing with any
1490 overflow in the subtraction. */
1496 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1497 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1498 overflow) and negate (which can't either). Special-case a result
1499 of zero while we're here. */
1505 else
1509 MINUS_EXPR,
1511 }
1512 \f
1513 /* A subroutine of fold_convert_const handling conversions of an
1514 INTEGER_CST to another integer type. */
1516 static tree
1518 {
1519 tree t;
1521 /* Given an integer constant, make new constant with new type,
1522 appropriately sign-extended or truncated. */
1531 }
1533 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1534 to an integer type. */
1536 static tree
1538 {
1540 tree t;
1542 /* The following code implements the floating point to integer
1543 conversion rules required by the Java Language Specification,
1544 that IEEE NaNs are mapped to zero and values that overflow
1545 the target precision saturate, i.e. values greater than
1546 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1547 are mapped to INT_MIN. These semantics are allowed by the
1548 C and C++ standards that simply state that the behavior of
1549 FP-to-integer conversion is unspecified upon overflow. */
1551 double_int val;
1552 REAL_VALUE_TYPE r;
1556 {
1563 }
1565 /* If R is NaN, return zero and show we have an overflow. */
1567 {
1570 }
1572 /* See if R is less than the lower bound or greater than the
1573 upper bound. */
1576 {
1580 {
1583 }
1584 }
1587 {
1590 {
1593 {
1596 }
1597 }
1598 }
1605 }
1607 /* A subroutine of fold_convert_const handling conversions of a
1608 FIXED_CST to an integer type. */
1610 static tree
1612 {
1613 tree t;
1617 /* Right shift FIXED_CST to temp by fbit. */
1621 {
1623 HOST_BITS_PER_DOUBLE_INT,
1626 /* Left shift temp to temp_trunc by fbit. */
1628 HOST_BITS_PER_DOUBLE_INT,
1630 }
1631 else
1632 {
1635 }
1637 /* If FIXED_CST is negative, we need to round the value toward 0.
1638 By checking if the fractional bits are not zero to add 1 to temp. */
1644 /* Given a fixed-point constant, make new constant with new type,
1645 appropriately sign-extended or truncated. */
1653 }
1655 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1656 to another floating point type. */
1658 static tree
1660 {
1661 REAL_VALUE_TYPE value;
1662 tree t;
1667 /* If converting an infinity or NAN to a representation that doesn't
1668 have one, set the overflow bit so that we can produce some kind of
1669 error message at the appropriate point if necessary. It's not the
1670 most user-friendly message, but it's better than nothing. */
1677 /* Regular overflow, conversion produced an infinity in a mode that
1678 can't represent them. */
1683 else
1686 }
1688 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1689 to a floating point type. */
1691 static tree
1693 {
1694 REAL_VALUE_TYPE value;
1695 tree t;
1702 }
1704 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
1705 to another fixed-point type. */
1707 static tree
1709 {
1710 FIXED_VALUE_TYPE value;
1711 tree t;
1718 /* Propagate overflow flags. */
1722 }
1724 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
1725 to a fixed-point type. */
1727 static tree
1729 {
1730 FIXED_VALUE_TYPE value;
1731 tree t;
1740 /* Propagate overflow flags. */
1744 }
1746 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1747 to a fixed-point type. */
1749 static tree
1751 {
1752 FIXED_VALUE_TYPE value;
1753 tree t;
1761 /* Propagate overflow flags. */
1765 }
1767 /* Attempt to fold type conversion operation CODE of expression ARG1 to
1768 type TYPE. If no simplification can be done return NULL_TREE. */
1770 static tree
1772 {
1778 {
1785 }
1787 {
1794 }
1796 {
1803 }
1805 }
1807 /* Construct a vector of zero elements of vector type TYPE. */
1809 static tree
1811 {
1812 tree t;
1816 }
1818 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
1820 bool
1822 {
1837 {
1856 }
1857 }
1859 /* Convert expression ARG to type TYPE. Used by the middle-end for
1860 simple conversions in preference to calling the front-end's convert. */
1862 tree
1864 {
1866 tree tem;
1880 {
1883 /* Handle conversions between pointers to different address spaces. */
1888 /* fall through */
1893 {
1897 }
1911 {
1915 }
1917 {
1921 }
1923 {
1927 }
1930 {
1948 }
1953 {
1957 }
1960 {
1974 }
1978 {
1987 integer_zero_node));
1989 {
1993 {
1999 }
2007 }
2011 }
2027 }
2028 fold_convert_exit:
2031 }
2032 \f
2033 /* Return false if expr can be assumed not to be an lvalue, true
2034 otherwise. */
2036 static bool
2038 {
2039 /* We only need to wrap lvalue tree codes. */
2041 {
2072 /* Assume the worst for front-end tree codes. */
2076 }
2079 }
2081 /* Return an expr equal to X but certainly not valid as an lvalue. */
2083 tree
2085 {
2086 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2087 us. */
2094 }
2096 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2097 Zero means allow extended lvalues. */
2101 /* When pedantic, return an expr equal to X but certainly not valid as a
2102 pedantic lvalue. Otherwise, return X. */
2104 static tree
2106 {
2111 }
2112 \f
2113 /* Given a tree comparison code, return the code that is the logical inverse
2114 of the given code. It is not safe to do this for floating-point
2115 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2116 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2118 enum tree_code
2120 {
2125 {
2156 }
2157 }
2159 /* Similar, but return the comparison that results if the operands are
2160 swapped. This is safe for floating-point. */
2162 enum tree_code
2164 {
2166 {
2192 }
2193 }
2196 /* Convert a comparison tree code from an enum tree_code representation
2197 into a compcode bit-based encoding. This function is the inverse of
2198 compcode_to_comparison. */
2200 static enum comparison_code
2202 {
2204 {
2235 }
2236 }
2238 /* Convert a compcode bit-based encoding of a comparison operator back
2239 to GCC's enum tree_code representation. This function is the
2240 inverse of comparison_to_compcode. */
2242 static enum tree_code
2244 {
2246 {
2277 }
2278 }
2280 /* Return a tree for the comparison which is the combination of
2281 doing the AND or OR (depending on CODE) of the two operations LCODE
2282 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2283 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2284 if this makes the transformation invalid. */
2286 tree
2291 {
2298 {
2309 }
2312 {
2313 /* Eliminate unordered comparisons, as well as LTGT and ORD
2314 which are not used unless the mode has NaNs. */
2320 }
2322 {
2323 /* Check that the original operation and the optimized ones will trap
2324 under the same condition. */
2335 /* In a short-circuited boolean expression the LHS might be
2336 such that the RHS, if evaluated, will never trap. For
2337 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2338 if neither x nor y is NaN. (This is a mixed blessing: for
2339 example, the expression above will never trap, hence
2340 optimizing it to x < y would be invalid). */
2345 /* If the comparison was short-circuited, and only the RHS
2346 trapped, we may now generate a spurious trap. */
2351 /* If we changed the conditions that cause a trap, we lose. */
2354 }
2360 else
2361 {
2366 }
2367 }
2368 \f
2369 /* Return nonzero if two operands (typically of the same tree node)
2370 are necessarily equal. If either argument has side-effects this
2371 function returns zero. FLAGS modifies behavior as follows:
2373 If OEP_ONLY_CONST is set, only return nonzero for constants.
2374 This function tests whether the operands are indistinguishable;
2375 it does not test whether they are equal using C's == operation.
2376 The distinction is important for IEEE floating point, because
2377 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2378 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2380 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2381 even though it may hold multiple values during a function.
2382 This is because a GCC tree node guarantees that nothing else is
2383 executed between the evaluation of its "operands" (which may often
2384 be evaluated in arbitrary order). Hence if the operands themselves
2385 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2386 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2387 unset means assuming isochronic (or instantaneous) tree equivalence.
2388 Unless comparing arbitrary expression trees, such as from different
2389 statements, this flag can usually be left unset.
2391 If OEP_PURE_SAME is set, then pure functions with identical arguments
2392 are considered the same. It is used when the caller has other ways
2393 to ensure that global memory is unchanged in between.
2395 If OEP_ALLOW_NULL is set, this routine will not crash on NULL operands,
2396 and two NULL operands are considered equal. This flag is usually set
2397 in the context of frontend when ARG0 and/or ARG1 may be NULL mostly due
2398 to recursion on partially built expressions (e.g. a CAST_EXPR on a NULL
2399 tree.) In this case, we certainly don't want the compiler to crash and
2400 it's OK to consider two NULL operands equal. On the other hand, when
2401 called in the context of code generation and optimization, if NULL
2402 operands are not expected, silently ignoring them could be dangerous
2403 and might cause problems downstream that are hard to find/debug. In that
2404 case, the flag should probably not be set. */
2406 int
2408 {
2409 /* If either is NULL, they must be both NULL to be equal. We only do this
2410 check when OEP_ALLOW_NULL is set. */
2414 /* If either is ERROR_MARK, they aren't equal. */
2420 /* Similar, if either does not have a type (like a released SSA name),
2421 they aren't equal. */
2423 {
2424 /* If the caller chooses to allow the comparison of operands without
2425 types, we will continue the comparison only when both of them don't
2426 have a type. */
2429 }
2431 /* Check equality of integer constants before bailing out due to
2432 precision differences. */
2436 /* If both types don't have the same signedness, then we can't consider
2437 them equal. We must check this before the STRIP_NOPS calls
2438 because they may change the signedness of the arguments. As pointers
2439 strictly don't have a signedness, require either two pointers or
2440 two non-pointers as well. */
2447 /* We cannot consider pointers to different address space equal. */
2454 /* If both types don't have the same precision, then it is not safe
2455 to strip NOPs. */
2464 /* In case both args are comparisons but with different comparison
2465 code, try to swap the comparison operands of one arg to produce
2466 a match and compare that variant. */
2470 {
2478 }
2481 /* This is needed for conversions and for COMPONENT_REF.
2482 Might as well play it safe and always test this. */
2489 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2490 We don't care about side effects in that case because the SAVE_EXPR
2491 takes care of that for us. In all other cases, two expressions are
2492 equal if they have no side effects. If we have two identical
2493 expressions with side effects that should be treated the same due
2494 to the only side effects being identical SAVE_EXPR's, that will
2495 be detected in the recursive calls below. */
2501 /* Next handle constant cases, those for which we can return 1 even
2502 if ONLY_CONST is set. */
2505 {
2521 {
2522 /* If we do not distinguish between signed and unsigned zero,
2523 consider them equal. */
2526 }
2530 {
2536 {
2538 flags))
2542 }
2545 }
2549 flags)
2551 flags));
2564 }
2569 /* Define macros to test an operand from arg0 and arg1 for equality and a
2570 variant that allows null and views null as being different from any
2571 non-null value. In the latter case, if either is null, the both
2572 must be; otherwise, do the normal comparison. */
2573 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2574 TREE_OPERAND (arg1, N), flags)
2576 #define OP_SAME_WITH_NULL(N) \
2577 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2578 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2581 {
2583 /* Two conversions are equal only if signedness and modes match. */
2585 {
2586 CASE_CONVERT:
2595 }
2605 /* For commutative ops, allow the other order. */
2613 /* If either of the pointer (or reference) expressions we are
2614 dereferencing contain a side effect, these cannot be equal. */
2620 {
2627 /* Require equal access sizes, and similar pointer types.
2628 We can have incomplete types for array references of
2629 variable-sized arrays from the Fortran frontent
2630 though. */
2638 flags)))
2645 /* Operands 2 and 3 may be null.
2646 Compare the array index by value if it is constant first as we
2647 may have different types but same value here. */
2656 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2657 may be NULL when we're called to compare MEM_EXPRs. */
2667 }
2671 {
2685 /* The multiplcation operands are commutative. */
2686 /* FALLTHRU */
2694 /* Otherwise take into account this is a commutative operation. */
2707 }
2711 {
2713 /* If the CALL_EXPRs call different functions, then they
2714 clearly can not be equal. */
2716 flags))
2719 {
2723 else
2727 }
2729 /* Now see if all the arguments are the same. */
2730 {
2741 /* If we get here and both argument lists are exhausted
2742 then the CALL_EXPRs are equal. */
2744 }
2747 }
2750 /* Consider __builtin_sqrt equal to sqrt. */
2758 }
2760 #undef OP_SAME
2761 #undef OP_SAME_WITH_NULL
2762 }
2763 \f
2764 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2765 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2767 When in doubt, return 0. */
2769 static int
2771 {
2783 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2784 and see if the inner values are the same. This removes any
2785 signedness comparison, which doesn't matter here. */
2792 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2793 actual comparison operand, ARG0.
2795 First throw away any conversions to wider types
2796 already present in the operands. */
2805 {
2808 /* Make sure shorter operand is extended the right way
2809 to match the longer operand. */
2815 }
2818 }
2819 \f
2820 /* See if ARG is an expression that is either a comparison or is performing
2821 arithmetic on comparisons. The comparisons must only be comparing
2822 two different values, which will be stored in *CVAL1 and *CVAL2; if
2823 they are nonzero it means that some operands have already been found.
2824 No variables may be used anywhere else in the expression except in the
2825 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2826 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2828 If this is true, return 1. Otherwise, return zero. */
2830 static int
2832 {
2836 /* We can handle some of the tcc_expression cases here. */
2846 {
2847 /* If we've already found a CVAL1 or CVAL2, this expression is
2848 two complex to handle. */
2854 }
2857 {
2880 /* First see if we can handle the first operand, then the second. For
2881 the second operand, we know *CVAL1 can't be zero. It must be that
2882 one side of the comparison is each of the values; test for the
2883 case where this isn't true by failing if the two operands
2884 are the same. */
2893 ;
2897 ;
2898 else
2902 ;
2906 ;
2907 else
2914 }
2915 }
2916 \f
2917 /* ARG is a tree that is known to contain just arithmetic operations and
2918 comparisons. Evaluate the operations in the tree substituting NEW0 for
2919 any occurrence of OLD0 as an operand of a comparison and likewise for
2920 NEW1 and OLD1. */
2922 static tree
2925 {
2930 /* We can handle some of the tcc_expression cases here. */
2938 {
2953 {
2972 }
2973 /* Fall through - ??? */
2976 {
2980 /* We need to check both for exact equality and tree equality. The
2981 former will be true if the operand has a side-effect. In that
2982 case, we know the operand occurred exactly once. */
2995 }
2999 }
3000 }
3001 \f
3002 /* Return a tree for the case when the result of an expression is RESULT
3003 converted to TYPE and OMITTED was previously an operand of the expression
3004 but is now not needed (e.g., we folded OMITTED * 0).
3006 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3007 the conversion of RESULT to TYPE. */
3009 tree
3011 {
3014 /* If the resulting operand is an empty statement, just return the omitted
3015 statement casted to void. */
3025 }
3027 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3029 static tree
3031 tree omitted)
3032 {
3035 /* If the resulting operand is an empty statement, just return the omitted
3036 statement casted to void. */
3046 }
3048 /* Return a tree for the case when the result of an expression is RESULT
3049 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3050 of the expression but are now not needed.
3052 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3053 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3054 evaluated before OMITTED2. Otherwise, if neither has side effects,
3055 just do the conversion of RESULT to TYPE. */
3057 tree
3060 {
3069 }
3071 \f
3072 /* Return a simplified tree node for the truth-negation of ARG. This
3073 never alters ARG itself. We assume that ARG is an operation that
3074 returns a truth value (0 or 1).
3076 FIXME: one would think we would fold the result, but it causes
3077 problems with the dominator optimizer. */
3079 tree
3081 {
3086 /* If this is a comparison, we can simply invert it, except for
3087 floating-point non-equality comparisons, in which case we just
3088 enclose a TRUTH_NOT_EXPR around what we have. */
3091 {
3094 && flag_trapping_math
3105 }
3108 {
3135 /* Here we can invert either operand. We invert the first operand
3136 unless the second operand is a TRUTH_NOT_EXPR in which case our
3137 result is the XOR of the first operand with the inside of the
3138 negation of the second operand. */
3143 else
3174 {
3185 /* A COND_EXPR may have a throw as one operand, which
3186 then has void type. Just leave void operands
3187 as they are. */
3193 }
3209 CASE_CONVERT:
3213 /* ... fall through ... */
3239 }
3240 }
3242 /* Return a simplified tree node for the truth-negation of ARG. This
3243 never alters ARG itself. We assume that ARG is an operation that
3244 returns a truth value (0 or 1).
3246 FIXME: one would think we would fold the result, but it causes
3247 problems with the dominator optimizer. */
3249 tree
3251 {
3252 tree tem;
3262 }
3264 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3265 operands are another bit-wise operation with a common input. If so,
3266 distribute the bit operations to save an operation and possibly two if
3267 constants are involved. For example, convert
3268 (A | B) & (A | C) into A | (B & C)
3269 Further simplification will occur if B and C are constants.
3271 If this optimization cannot be done, 0 will be returned. */
3273 static tree
3276 {
3277 tree common;
3287 {
3291 }
3293 {
3297 }
3299 {
3303 }
3305 {
3309 }
3310 else
3318 }
3320 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3321 with code CODE. This optimization is unsafe. */
3322 static tree
3325 {
3329 /* (A / C) +- (B / C) -> (A +- B) / C. */
3339 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3344 {
3356 }
3359 }
3360 \f
3361 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3362 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3364 static tree
3367 {
3371 {
3378 }
3392 }
3394 /* Optimize a bit-field compare.
3396 There are two cases: First is a compare against a constant and the
3397 second is a comparison of two items where the fields are at the same
3398 bit position relative to the start of a chunk (byte, halfword, word)
3399 large enough to contain it. In these cases we can avoid the shift
3400 implicit in bitfield extractions.
3402 For constants, we emit a compare of the shifted constant with the
3403 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3404 compared. For two fields at the same position, we do the ANDs with the
3405 similar mask and compare the result of the ANDs.
3407 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3408 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3409 are the left and right operands of the comparison, respectively.
3411 If the optimization described above can be done, we return the resulting
3412 tree. Otherwise we return zero. */
3414 static tree
3417 {
3426 tree mask;
3427 tree offset;
3429 /* Get all the information about the extractions being done. If the bit size
3430 if the same as the size of the underlying object, we aren't doing an
3431 extraction at all and so can do nothing. We also don't want to
3432 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3433 then will no longer be able to replace it. */
3441 {
3442 /* If this is not a constant, we can only do something if bit positions,
3443 sizes, and signedness are the same. */
3451 }
3453 /* See if we can find a mode to refer to this field. We should be able to,
3454 but fail if we can't. */
3459 else
3468 /* Set signed and unsigned types of the precision of this mode for the
3469 shifts below. */
3473 /* Compute the bit position and size for the new reference and our offset
3474 within it. If the new reference is the same size as the original, we
3475 won't optimize anything, so return zero. */
3485 /* Make the mask to be used against the extracted field. */
3492 /* If not comparing with constant, just rework the comparison
3493 and return. */
3497 unsigned_type,
3500 mask),
3503 unsigned_type,
3506 mask));
3508 /* Otherwise, we are handling the constant case. See if the constant is too
3509 big for the field. Warn and return a tree of for 0 (false) if so. We do
3510 this not only for its own sake, but to avoid having to test for this
3511 error case below. If we didn't, we might generate wrong code.
3513 For unsigned fields, the constant shifted right by the field length should
3514 be all zero. For signed fields, the high-order bits should agree with
3515 the sign bit. */
3518 {
3523 {
3527 }
3528 }
3529 else
3530 {
3535 {
3539 }
3540 }
3542 /* Single-bit compares should always be against zero. */
3544 {
3547 }
3549 /* Make a new bitfield reference, shift the constant over the
3550 appropriate number of bits and mask it with the computed mask
3551 (in case this was a signed field). If we changed it, make a new one. */
3554 {
3557 }
3563 mask);
3568 }
3569 \f
3570 /* Subroutine for fold_truthop: decode a field reference.
3572 If EXP is a comparison reference, we return the innermost reference.
3574 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3575 set to the starting bit number.
3577 If the innermost field can be completely contained in a mode-sized
3578 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3580 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3581 otherwise it is not changed.
3583 *PUNSIGNEDP is set to the signedness of the field.
3585 *PMASK is set to the mask used. This is either contained in a
3586 BIT_AND_EXPR or derived from the width of the field.
3588 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3590 Return 0 if this is not a component reference or is one that we can't
3591 do anything with. */
3593 static tree
3598 {
3602 tree unsigned_type;
3605 /* All the optimizations using this function assume integer fields.
3606 There are problems with FP fields since the type_for_size call
3607 below can fail for, e.g., XFmode. */
3611 /* We are interested in the bare arrangement of bits, so strip everything
3612 that doesn't affect the machine mode. However, record the type of the
3613 outermost expression if it may matter below. */
3620 {
3626 }
3635 /* If the number of bits in the reference is the same as the bitsize of
3636 the outer type, then the outer type gives the signedness. Otherwise
3637 (in case of a small bitfield) the signedness is unchanged. */
3641 /* Compute the mask to access the bitfield. */
3650 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3658 }
3660 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3661 bit positions. */
3663 static int
3665 {
3668 tree tmask;
3672 return
3678 }
3680 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3681 represents the sign bit of EXP's type. If EXP represents a sign
3682 or zero extension, also test VAL against the unextended type.
3683 The return value is the (sub)expression whose sign bit is VAL,
3684 or NULL_TREE otherwise. */
3686 static tree
3688 {
3692 tree t;
3694 /* Tree EXP must have an integral type. */
3699 /* Tree VAL must be an integer constant. */
3706 {
3713 }
3714 else
3715 {
3722 }
3724 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3725 treat VAL as if it were unsigned. */
3730 /* Handle extension from a narrower type. */
3736 }
3738 /* Subroutine for fold_truthop: determine if an operand is simple enough
3739 to be evaluated unconditionally. */
3741 static int
3743 {
3744 /* Strip any conversions that don't change the machine mode. */
3753 /* Don't regard global variables as simple. They may be
3754 allocated in ways unknown to the compiler (shared memory,
3755 #pragma weak, etc). */
3758 /* Loading a static variable is unduly expensive, but global
3759 registers aren't expensive. */
3761 }
3762 \f
3763 /* The following functions are subroutines to fold_range_test and allow it to
3764 try to change a logical combination of comparisons into a range test.
3766 For example, both
3767 X == 2 || X == 3 || X == 4 || X == 5
3768 and
3769 X >= 2 && X <= 5
3770 are converted to
3771 (unsigned) (X - 2) <= 3
3773 We describe each set of comparisons as being either inside or outside
3774 a range, using a variable named like IN_P, and then describe the
3775 range with a lower and upper bound. If one of the bounds is omitted,
3776 it represents either the highest or lowest value of the type.
3778 In the comments below, we represent a range by two numbers in brackets
3779 preceded by a "+" to designate being inside that range, or a "-" to
3780 designate being outside that range, so the condition can be inverted by
3781 flipping the prefix. An omitted bound is represented by a "-". For
3782 example, "- [-, 10]" means being outside the range starting at the lowest
3783 possible value and ending at 10, in other words, being greater than 10.
3784 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3785 always false.
3787 We set up things so that the missing bounds are handled in a consistent
3788 manner so neither a missing bound nor "true" and "false" need to be
3789 handled using a special case. */
3791 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3792 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3793 and UPPER1_P are nonzero if the respective argument is an upper bound
3794 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3795 must be specified for a comparison. ARG1 will be converted to ARG0's
3796 type if both are specified. */
3798 static tree
3801 {
3802 tree tem;
3806 /* If neither arg represents infinity, do the normal operation.
3807 Else, if not a comparison, return infinity. Else handle the special
3808 comparison rules. Note that most of the cases below won't occur, but
3809 are handled for consistency. */
3812 {
3817 }
3822 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3823 for neither. In real maths, we cannot assume open ended ranges are
3824 the same. But, this is computer arithmetic, where numbers are finite.
3825 We can therefore make the transformation of any unbounded range with
3826 the value Z, Z being greater than any representable number. This permits
3827 us to treat unbounded ranges as equal. */
3831 {
3852 }
3855 }
3856 \f
3857 /* Given EXP, a logical expression, set the range it is testing into
3858 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
3859 actually being tested. *PLOW and *PHIGH will be made of the same
3860 type as the returned expression. If EXP is not a comparison, we
3861 will most likely not be returning a useful value and range. Set
3862 *STRICT_OVERFLOW_P to true if the return value is only valid
3863 because signed overflow is undefined; otherwise, do not change
3864 *STRICT_OVERFLOW_P. */
3866 tree
3869 {
3877 /* Start with simply saying "EXP != 0" and then look at the code of EXP
3878 and see if we can refine the range. Some of the cases below may not
3879 happen, but it doesn't seem worth worrying about this. We "continue"
3880 the outer loop when we've changed something; otherwise we "break"
3881 the switch, which will "break" the while. */
3887 {
3892 {
3904 }
3907 {
3914 /* We can only do something if the range is testing for zero
3915 and if the second operand is an integer constant. Note that
3916 saying something is "in" the range we make is done by
3917 complementing IN_P since it will set in the initial case of
3918 being not equal to zero; "out" is leaving it alone. */
3925 {
3946 }
3948 /* If this is an unsigned comparison, we also know that EXP is
3949 greater than or equal to zero. We base the range tests we make
3950 on that fact, so we record it here so we can parse existing
3951 range tests. We test arg0_type since often the return type
3952 of, e.g. EQ_EXPR, is boolean. */
3954 {
3958 NULL_TREE))
3963 /* If the high bound is missing, but we have a nonzero low
3964 bound, reverse the range so it goes from zero to the low bound
3965 minus 1. */
3967 {
3972 }
3973 }
3979 /* (-x) IN [a,b] -> x in [-b, -a] */
3991 /* ~ X -> -X - 1 */
4000 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4001 move a constant to the other side. */
4006 /* If EXP is signed, any overflow in the computation is undefined,
4007 so we don't worry about it so long as our computations on
4008 the bounds don't overflow. For unsigned, overflow is defined
4009 and this is exactly the right thing. */
4021 normalize:
4022 /* Check for an unsigned range which has wrapped around the maximum
4023 value thus making n_high < n_low, and normalize it. */
4025 {
4031 /* If the range is of the form +/- [ x+1, x ], we won't
4032 be able to normalize it. But then, it represents the
4033 whole range or the empty set, so make it
4034 +/- [ -, - ]. */
4038 else
4040 }
4041 else
4065 /* If we're converting arg0 from an unsigned type, to exp,
4066 a signed type, we will be doing the comparison as unsigned.
4067 The tests above have already verified that LOW and HIGH
4068 are both positive.
4070 So we have to ensure that we will handle large unsigned
4071 values the same way that the current signed bounds treat
4072 negative values. */
4075 {
4076 tree high_positive;
4077 tree equiv_type;
4078 /* For fixed-point modes, we need to pass the saturating flag
4079 as the 2nd parameter. */
4084 else
4088 /* A range without an upper bound is, naturally, unbounded.
4089 Since convert would have cropped a very large value, use
4090 the max value for the destination type. */
4091 high_positive
4098 high_positive),
4101 /* If the low bound is specified, "and" the range with the
4102 range for which the original unsigned value will be
4103 positive. */
4105 {
4109 integer_zero_node),
4110 high_positive))
4114 }
4115 else
4116 {
4117 /* Otherwise, "or" the range with the range of the input
4118 that will be interpreted as negative. */
4122 integer_zero_node),
4123 high_positive))
4127 }
4128 }
4136 }
4139 }
4141 /* If EXP is a constant, we can evaluate whether this is true or false. */
4143 {
4150 }
4154 }
4155 \f
4156 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4157 type, TYPE, return an expression to test if EXP is in (or out of, depending
4158 on IN_P) the range. Return 0 if the test couldn't be created. */
4160 tree
4163 {
4166 #ifdef HAVE_canonicalize_funcptr_for_compare
4167 /* Disable this optimization for function pointer expressions
4168 on targets that require function pointer canonicalization. */
4173 #endif
4176 {
4182 }
4200 {
4202 {
4206 }
4208 }
4210 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4212 {
4214 HOST_WIDE_INT hi;
4219 {
4222 }
4223 else
4224 {
4227 }
4230 {
4232 {
4235 etype
4237 else
4240 }
4243 }
4244 }
4246 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4247 This requires wrap-around arithmetics for the type of the expression.
4248 First make sure that arithmetics in this type is valid, then make sure
4249 that it wraps around. */
4255 {
4258 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4259 for the type in question, as we rely on this here. */
4269 else
4271 }
4281 {
4283 {
4290 }
4292 }
4300 }
4301 \f
4302 /* Return the predecessor of VAL in its type, handling the infinite case. */
4304 static tree
4306 {
4312 else
4314 }
4316 /* Return the successor of VAL in its type, handling the infinite case. */
4318 static tree
4320 {
4326 else
4328 }
4330 /* Given two ranges, see if we can merge them into one. Return 1 if we
4331 can, 0 if we can't. Set the output range into the specified parameters. */
4333 bool
4336 {
4340 tree tem;
4350 /* Make range 0 be the range that starts first, or ends last if they
4351 start at the same value. Swap them if it isn't. */
4354 || (lowequal
4357 {
4361 }
4363 /* Now flag two cases, whether the ranges are disjoint or whether the
4364 second range is totally subsumed in the first. Note that the tests
4365 below are simplified by the ones above. */
4371 /* We now have four cases, depending on whether we are including or
4372 excluding the two ranges. */
4374 {
4375 /* If they don't overlap, the result is false. If the second range
4376 is a subset it is the result. Otherwise, the range is from the start
4377 of the second to the end of the first. */
4382 else
4384 }
4387 {
4388 /* If they don't overlap, the result is the first range. If they are
4389 equal, the result is false. If the second range is a subset of the
4390 first, and the ranges begin at the same place, we go from just after
4391 the end of the second range to the end of the first. If the second
4392 range is not a subset of the first, or if it is a subset and both
4393 ranges end at the same place, the range starts at the start of the
4394 first range and ends just before the second range.
4395 Otherwise, we can't describe this as a single range. */
4401 {
4406 {
4407 /* We are in the weird situation where high0 > high1 but
4408 high1 has no successor. Punt. */
4410 }
4411 }
4413 {
4418 {
4419 /* low0 < low1 but low1 has no predecessor. Punt. */
4421 }
4422 }
4423 else
4425 }
4428 {
4429 /* If they don't overlap, the result is the second range. If the second
4430 is a subset of the first, the result is false. Otherwise,
4431 the range starts just after the first range and ends at the
4432 end of the second. */
4437 else
4438 {
4443 {
4444 /* high1 > high0 but high0 has no successor. Punt. */
4446 }
4447 }
4448 }
4450 else
4451 {
4452 /* The case where we are excluding both ranges. Here the complex case
4453 is if they don't overlap. In that case, the only time we have a
4454 range is if they are adjacent. If the second is a subset of the
4455 first, the result is the first. Otherwise, the range to exclude
4456 starts at the beginning of the first range and ends at the end of the
4457 second. */
4459 {
4464 else
4465 {
4466 /* Canonicalize - [min, x] into - [-, x]. */
4469 {
4474 /* FALLTHROUGH */
4487 }
4489 /* Canonicalize - [x, max] into - [x, -]. */
4492 {
4497 /* FALLTHROUGH */
4512 }
4514 /* The ranges might be also adjacent between the maximum and
4515 minimum values of the given type. For
4516 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4517 return + [x + 1, y - 1]. */
4519 {
4526 }
4527 else
4529 }
4530 }
4533 else
4535 }
4539 }
4540 \f
4542 /* Subroutine of fold, looking inside expressions of the form
4543 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4544 of the COND_EXPR. This function is being used also to optimize
4545 A op B ? C : A, by reversing the comparison first.
4547 Return a folded expression whose code is not a COND_EXPR
4548 anymore, or NULL_TREE if no folding opportunity is found. */
4550 static tree
4553 {
4558 tree tem;
4563 /* If we have A op 0 ? A : -A, consider applying the following
4564 transformations:
4566 A == 0? A : -A same as -A
4567 A != 0? A : -A same as A
4568 A >= 0? A : -A same as abs (A)
4569 A > 0? A : -A same as abs (A)
4570 A <= 0? A : -A same as -abs (A)
4571 A < 0? A : -A same as -abs (A)
4573 None of these transformations work for modes with signed
4574 zeros. If A is +/-0, the first two transformations will
4575 change the sign of the result (from +0 to -0, or vice
4576 versa). The last four will fix the sign of the result,
4577 even though the original expressions could be positive or
4578 negative, depending on the sign of A.
4580 Note that all these transformations are correct if A is
4581 NaN, since the two alternatives (A and -A) are also NaNs. */
4588 /* In the case that A is of the form X-Y, '-A' (arg2) may
4589 have already been folded to Y-X, check for that. */
4597 {
4611 /* Fall through. */
4633 }
4635 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4636 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4637 both transformations are correct when A is NaN: A != 0
4638 is then true, and A == 0 is false. */
4642 {
4647 }
4649 /* Try some transformations of A op B ? A : B.
4651 A == B? A : B same as B
4652 A != B? A : B same as A
4653 A >= B? A : B same as max (A, B)
4654 A > B? A : B same as max (B, A)
4655 A <= B? A : B same as min (A, B)
4656 A < B? A : B same as min (B, A)
4658 As above, these transformations don't work in the presence
4659 of signed zeros. For example, if A and B are zeros of
4660 opposite sign, the first two transformations will change
4661 the sign of the result. In the last four, the original
4662 expressions give different results for (A=+0, B=-0) and
4663 (A=-0, B=+0), but the transformed expressions do not.
4665 The first two transformations are correct if either A or B
4666 is a NaN. In the first transformation, the condition will
4667 be false, and B will indeed be chosen. In the case of the
4668 second transformation, the condition A != B will be true,
4669 and A will be chosen.
4671 The conversions to max() and min() are not correct if B is
4672 a number and A is not. The conditions in the original
4673 expressions will be false, so all four give B. The min()
4674 and max() versions would give a NaN instead. */
4677 /* Avoid these transformations if the COND_EXPR may be used
4678 as an lvalue in the C++ front-end. PR c++/19199. */
4679 && (in_gimple_form
4684 {
4689 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4691 {
4695 }
4698 {
4707 /* In C++ a ?: expression can be an lvalue, so put the
4708 operand which will be used if they are equal first
4709 so that we can convert this back to the
4710 corresponding COND_EXPR. */
4712 {
4721 }
4728 {
4737 }
4752 }
4753 }
4755 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4756 we might still be able to simplify this. For example,
4757 if C1 is one less or one more than C2, this might have started
4758 out as a MIN or MAX and been transformed by this function.
4759 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4765 {
4769 /* We can replace A with C1 in this case. */
4774 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
4775 MIN_EXPR, to preserve the signedness of the comparison. */
4777 OEP_ONLY_CONST)
4781 OEP_ONLY_CONST))
4782 {
4785 arg2));
4788 }
4792 /* If C1 is C2 - 1, this is min(A, C2), with the same care
4793 as above. */
4795 OEP_ONLY_CONST)
4799 OEP_ONLY_CONST))
4800 {
4803 arg2));
4806 }
4810 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
4811 MAX_EXPR, to preserve the signedness of the comparison. */
4813 OEP_ONLY_CONST)
4817 OEP_ONLY_CONST))
4818 {
4821 arg2));
4823 }
4827 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
4829 OEP_ONLY_CONST)
4833 OEP_ONLY_CONST))
4834 {
4837 arg2));
4839 }
4845 }
4848 }
4851 \f
4852 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4853 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
4854 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
4855 false) >= 2)
4856 #endif
4858 /* EXP is some logical combination of boolean tests. See if we can
4859 merge it into some range test. Return the new tree if so. */
4861 static tree
4864 {
4872 tree tem;
4876 /* If this is an OR operation, invert both sides; we will invert
4877 again at the end. */
4881 /* If both expressions are the same, if we can merge the ranges, and we
4882 can build the range test, return it or it inverted. If one of the
4883 ranges is always true or always false, consider it to be the same
4884 expression as the other. */
4892 {
4896 }
4898 /* On machines where the branch cost is expensive, if this is a
4899 short-circuited branch and the underlying object on both sides
4900 is the same, make a non-short-circuit operation. */
4906 {
4907 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4908 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4909 which cases we can't do this. */
4917 {
4926 {
4929 WARN_STRICT_OVERFLOW_COMPARISON);
4933 }
4934 }
4935 }
4938 }
4939 \f
4940 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
4941 bit value. Arrange things so the extra bits will be set to zero if and
4942 only if C is signed-extended to its full width. If MASK is nonzero,
4943 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4945 static tree
4947 {
4950 tree temp;
4955 /* We work by getting just the sign bit into the low-order bit, then
4956 into the high-order bit, then sign-extend. We then XOR that value
4957 with C. */
4961 /* We must use a signed type in order to get an arithmetic right shift.
4962 However, we must also avoid introducing accidental overflows, so that
4963 a subsequent call to integer_zerop will work. Hence we must
4964 do the type conversion here. At this point, the constant is either
4965 zero or one, and the conversion to a signed type can never overflow.
4966 We could get an overflow if this conversion is done anywhere else. */
4975 /* If necessary, convert the type back to match the type of C. */
4980 }
4981 \f
4982 /* For an expression that has the form
4983 (A && B) || ~B
4984 or
4985 (A || B) && ~B,
4986 we can drop one of the inner expressions and simplify to
4987 A || ~B
4988 or
4989 A && ~B
4990 LOC is the location of the resulting expression. OP is the inner
4991 logical operation; the left-hand side in the examples above, while CMPOP
4992 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
4993 removing a condition that guards another, as in
4994 (A != NULL && A->...) || A == NULL
4995 which we must not transform. If RHS_ONLY is true, only eliminate the
4996 right-most operand of the inner logical operation. */
4998 static tree
5001 {
5019 {
5022 {
5025 }
5026 }
5028 {
5031 {
5034 }
5035 }
5050 }
5052 /* Find ways of folding logical expressions of LHS and RHS:
5053 Try to merge two comparisons to the same innermost item.
5054 Look for range tests like "ch >= '0' && ch <= '9'".
5055 Look for combinations of simple terms on machines with expensive branches
5056 and evaluate the RHS unconditionally.
5058 For example, if we have p->a == 2 && p->b == 4 and we can make an
5059 object large enough to span both A and B, we can do this with a comparison
5060 against the object ANDed with the a mask.
5062 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5063 operations to do this with one comparison.
5065 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5066 function and the one above.
5068 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5069 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5071 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5072 two operands.
5074 We return the simplified tree or 0 if no optimization is possible. */
5076 static tree
5079 {
5080 /* If this is the "or" of two comparisons, we can do something if
5081 the comparisons are NE_EXPR. If this is the "and", we can do something
5082 if the comparisons are EQ_EXPR. I.e.,
5083 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5085 WANTED_CODE is this operation code. For single bit fields, we can
5086 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5087 comparison for one-bit fields. */
5109 /* Start by getting the comparison codes. Fail if anything is volatile.
5110 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5111 it were surrounded with a NE_EXPR. */
5120 {
5124 }
5127 {
5131 }
5142 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5145 {
5148 {
5153 }
5156 {
5162 }
5163 }
5168 /* If the RHS can be evaluated unconditionally and its operands are
5169 simple, it wins to evaluate the RHS unconditionally on machines
5170 with expensive branches. In this case, this isn't a comparison
5171 that can be merged. Avoid doing this if the RHS is a floating-point
5172 comparison since those can trap. */
5179 {
5180 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5191 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5203 {
5207 }
5208 }
5210 /* See if the comparisons can be merged. Then get all the parameters for
5211 each side. */
5235 /* It must be true that the inner operation on the lhs of each
5236 comparison must be the same if we are to be able to do anything.
5237 Then see if we have constants. If not, the same must be true for
5238 the rhs's. */
5249 else
5252 /* If either comparison code is not correct for our logical operation,
5253 fail. However, we can convert a one-bit comparison against zero into
5254 the opposite comparison against that bit being set in the field. */
5258 {
5260 {
5261 /* Make the left operand unsigned, since we are only interested
5262 in the value of one bit. Otherwise we are doing the wrong
5263 thing below. */
5266 }
5267 else
5269 }
5271 /* This is analogous to the code for l_const above. */
5273 {
5275 {
5278 }
5279 else
5281 }
5283 /* See if we can find a mode that contains both fields being compared on
5284 the left. If we can't, fail. Otherwise, update all constants and masks
5285 to be relative to a field of that size. */
5290 volatilep);
5300 {
5303 }
5311 {
5318 {
5322 }
5323 }
5325 {
5332 {
5336 }
5337 }
5339 /* If the right sides are not constant, do the same for it. Also,
5340 disallow this optimization if a size or signedness mismatch occurs
5341 between the left and right sides. */
5343 {
5346 /* Make sure the two fields on the right
5347 correspond to the left without being swapped. */
5355 volatilep);
5365 {
5368 }
5377 /* Make a mask that corresponds to both fields being compared.
5378 Do this for both items being compared. If the operands are the
5379 same size and the bits being compared are in the same position
5380 then we can do this by masking both and comparing the masked
5381 results. */
5385 {
5397 }
5399 /* There is still another way we can do something: If both pairs of
5400 fields being compared are adjacent, we may be able to make a wider
5401 field containing them both.
5403 Note that we still must mask the lhs/rhs expressions. Furthermore,
5404 the mask must be shifted to account for the shift done by
5405 make_bit_field_ref. */
5410 {
5411 tree type;
5425 /* Convert to the smaller type before masking out unwanted bits. */
5428 {
5430 {
5434 }
5436 {
5440 }
5441 }
5450 }
5453 }
5455 /* Handle the case of comparisons with constants. If there is something in
5456 common between the masks, those bits of the constants must be the same.
5457 If not, the condition is always false. Test for this to avoid generating
5458 incorrect code below. */
5463 {
5465 {
5468 }
5469 else
5470 {
5473 }
5474 }
5476 /* Construct the expression we will return. First get the component
5477 reference we will make. Unless the mask is all ones the width of
5478 that field, perform the mask operation. Then compare with the
5479 merged constant. */
5489 }
5490 \f
5491 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5492 constant. */
5494 static tree
5497 {
5500 tree comp_const;
5501 tree minmax_const;
5503 tree inner;
5514 /* If something does not permit us to optimize, return the original tree. */
5522 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5523 and GT_EXPR, doing the rest with recursive calls using logical
5524 simplifications. */
5526 {
5528 {
5529 tree tem
5536 }
5539 return
5541 optimize_minmax_comparison
5543 optimize_minmax_comparison
5548 /* MAX (X, 0) == 0 -> X <= 0 */
5552 /* MAX (X, 0) == 5 -> X == 5 */
5556 /* MAX (X, 0) == -1 -> false */
5560 /* MIN (X, 0) == 0 -> X >= 0 */
5564 /* MIN (X, 0) == 5 -> false */
5567 else
5568 /* MIN (X, 0) == -1 -> X == -1 */
5573 /* MAX (X, 0) > 0 -> X > 0
5574 MAX (X, 0) > 5 -> X > 5 */
5578 /* MAX (X, 0) > -1 -> true */
5582 /* MIN (X, 0) > 0 -> false
5583 MIN (X, 0) > 5 -> false */
5586 else
5587 /* MIN (X, 0) > -1 -> X > -1 */
5592 }
5593 }
5594 \f
5595 /* T is an integer expression that is being multiplied, divided, or taken a
5596 modulus (CODE says which and what kind of divide or modulus) by a
5597 constant C. See if we can eliminate that operation by folding it with
5598 other operations already in T. WIDE_TYPE, if non-null, is a type that
5599 should be used for the computation if wider than our type.
5601 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5602 (X * 2) + (Y * 4). We must, however, be assured that either the original
5603 expression would not overflow or that overflow is undefined for the type
5604 in the language in question.
5606 If we return a non-null expression, it is an equivalent form of the
5607 original computation, but need not be in the original type.
5609 We set *STRICT_OVERFLOW_P to true if the return values depends on
5610 signed overflow being undefined. Otherwise we do not change
5611 *STRICT_OVERFLOW_P. */
5613 static tree
5616 {
5617 /* To avoid exponential search depth, refuse to allow recursion past
5618 three levels. Beyond that (1) it's highly unlikely that we'll find
5619 something interesting and (2) we've probably processed it before
5620 when we built the inner expression. */
5623 tree ret;
5628 depth++;
5630 depth--;
5633 }
5635 static tree
5638 {
5649 /* Don't deal with constants of zero here; they confuse the code below. */
5659 /* Note that we need not handle conditional operations here since fold
5660 already handles those cases. So just do arithmetic here. */
5662 {
5664 /* For a constant, we can always simplify if we are a multiply
5665 or (for divide and modulus) if it is a multiple of our constant. */
5673 /* If op0 is an expression ... */
5679 /* ... and has wrapping overflow, and its type is smaller
5680 than ctype, then we cannot pass through as widening. */
5686 /* ... or this is a truncation (t is narrower than op0),
5687 then we cannot pass through this narrowing. */
5690 /* ... or signedness changes for division or modulus,
5691 then we cannot pass through this conversion. */
5695 /* ... or has undefined overflow while the converted to
5696 type has not, we cannot do the operation in the inner type
5697 as that would introduce undefined overflow. */
5702 /* Pass the constant down and see if we can make a simplification. If
5703 we can, replace this expression with the inner simplification for
5704 possible later conversion to our or some other type. */
5709 code == MULT_EXPR
5711 strict_overflow_p))))
5716 /* If widening the type changes it from signed to unsigned, then we
5717 must avoid building ABS_EXPR itself as unsigned. */
5719 {
5723 {
5726 }
5728 }
5729 /* If the constant is negative, we cannot simplify this. */
5732 /* FALLTHROUGH */
5740 /* If widening the type changes the signedness, then we can't perform
5741 this optimization as that changes the result. */
5745 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5751 {
5758 }
5762 /* If the second operand is constant, this is a multiplication
5763 or floor division, by a power of two, so we can treat it that
5764 way unless the multiplier or divisor overflows. Signed
5765 left-shift overflow is implementation-defined rather than
5766 undefined in C90, so do not convert signed left shift into
5767 multiplication. */
5770 /* const_binop may not detect overflow correctly,
5771 so check for it explicitly here. */
5776 size_one_node,
5777 op1)))
5781 ctype,
5783 t1),
5788 /* See if we can eliminate the operation on both sides. If we can, we
5789 can return a new PLUS or MINUS. If we can't, the only remaining
5790 cases where we can do anything are if the second operand is a
5791 constant. */
5797 /* If not multiplication, we can only do this if both operands
5798 are divisible by c. */
5801 {
5806 }
5808 /* If this was a subtraction, negate OP1 and set it to be an addition.
5809 This simplifies the logic below. */
5811 {
5813 /* If OP1 was not easily negatable, the constant may be OP0. */
5815 {
5822 }
5823 }
5828 /* If either OP1 or C are negative, this optimization is not safe for
5829 some of the division and remainder types while for others we need
5830 to change the code. */
5832 {
5840 }
5842 /* If it's a multiply or a division/modulus operation of a multiple
5843 of our constant, do the operation and verify it doesn't overflow. */
5846 {
5849 /* We allow the constant to overflow with wrapping semantics. */
5853 }
5854 else
5857 /* If we have an unsigned type is not a sizetype, we cannot widen
5858 the operation since it will change the result if the original
5859 computation overflowed. */
5865 /* If we were able to eliminate our operation from the first side,
5866 apply our operation to the second side and reform the PLUS. */
5870 /* The last case is if we are a multiply. In that case, we can
5871 apply the distributive law to commute the multiply and addition
5872 if the multiplication of the constants doesn't overflow. */
5878 op1);
5883 /* We have a special case here if we are doing something like
5884 (C * 8) % 4 since we know that's zero. */
5887 /* If the multiplication can overflow we cannot optimize this.
5888 ??? Until we can properly mark individual operations as
5889 not overflowing we need to treat sizetype special here as
5890 stor-layout relies on this opimization to make
5891 DECL_FIELD_BIT_OFFSET always a constant. */
5897 {
5900 }
5902 /* ... fall through ... */
5906 /* If we can extract our operation from the LHS, do so and return a
5907 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5908 do something only if the second operand is a constant. */
5922 /* If these are the same operation types, we can associate them
5923 assuming no overflow. */
5935 /* If these operations "cancel" each other, we have the main
5936 optimizations of this pass, which occur when either constant is a
5937 multiple of the other, in which case we replace this with either an
5938 operation or CODE or TCODE.
5940 If we have an unsigned type that is not a sizetype, we cannot do
5941 this since it will change the result if the original computation
5942 overflowed. */
5950 {
5952 {
5959 }
5961 {
5968 }
5969 }
5974 }
5977 }
5978 \f
5979 /* Return a node which has the indicated constant VALUE (either 0 or
5980 1), and is of the indicated TYPE. */
5982 tree
5984 {
5991 else
5993 }
5996 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
5997 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
5998 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
5999 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6000 COND is the first argument to CODE; otherwise (as in the example
6001 given here), it is the second argument. TYPE is the type of the
6002 original expression. Return NULL_TREE if no simplification is
6003 possible. */
6005 static tree
6010 {
6018 {
6022 /* If this operand throws an expression, then it does not make
6023 sense to try to perform a logical or arithmetic operation
6024 involving it. */
6029 }
6030 else
6031 {
6036 }
6038 /* This transformation is only worthwhile if we don't have to wrap ARG
6039 in a SAVE_EXPR and the operation can be simplified on at least one
6040 of the branches once its pushed inside the COND_EXPR. */
6048 {
6052 else
6054 }
6056 {
6060 else
6062 }
6064 /* Check that we have simplified at least one of the branches. */
6069 }
6071 \f
6072 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6074 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6075 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6076 ADDEND is the same as X.
6078 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6079 and finite. The problematic cases are when X is zero, and its mode
6080 has signed zeros. In the case of rounding towards -infinity,
6081 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6082 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6084 bool
6086 {
6090 /* Don't allow the fold with -fsignaling-nans. */
6094 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6098 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6103 /* The mode has signed zeros, and we have to honor their sign.
6104 In this situation, there is only one case we can return true for.
6105 X - 0 is the same as X unless rounding towards -infinity is
6106 supported. */
6108 }
6110 /* Subroutine of fold() that checks comparisons of built-in math
6111 functions against real constants.
6113 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6114 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6115 is the type of the result and ARG0 and ARG1 are the operands of the
6116 comparison. ARG1 must be a TREE_REAL_CST.
6118 The function returns the constant folded tree if a simplification
6119 can be made, and NULL_TREE otherwise. */
6121 static tree
6125 {
6126 REAL_VALUE_TYPE c;
6129 {
6135 {
6136 /* sqrt(x) < y is always false, if y is negative. */
6140 /* sqrt(x) > y is always true, if y is negative and we
6141 don't care about NaNs, i.e. negative values of x. */
6145 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6148 }
6150 {
6151 REAL_VALUE_TYPE c2;
6157 {
6158 /* sqrt(x) > y is x == +Inf, when y is very large. */
6163 /* sqrt(x) > y is always false, when y is very large
6164 and we don't care about infinities. */
6166 }
6168 /* sqrt(x) > c is the same as x > c*c. */
6171 }
6173 {
6174 REAL_VALUE_TYPE c2;
6180 {
6181 /* sqrt(x) < y is always true, when y is a very large
6182 value and we don't care about NaNs or Infinities. */
6186 /* sqrt(x) < y is x != +Inf when y is very large and we
6187 don't care about NaNs. */
6192 /* sqrt(x) < y is x >= 0 when y is very large and we
6193 don't care about Infinities. */
6198 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6207 dconst0)),
6210 c2)));
6211 }
6213 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6218 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6221 {
6226 dconst0)),
6229 c2)));
6230 }
6231 }
6232 }
6235 }
6237 /* Subroutine of fold() that optimizes comparisons against Infinities,
6238 either +Inf or -Inf.
6240 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6241 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6242 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6244 The function returns the constant folded tree if a simplification
6245 can be made, and NULL_TREE otherwise. */
6247 static tree
6250 {
6252 REAL_VALUE_TYPE max;
6253 tree temp;
6258 /* For negative infinity swap the sense of the comparison. */
6264 {
6266 /* x > +Inf is always false, if with ignore sNANs. */
6272 /* x <= +Inf is always true, if we don't case about NaNs. */
6276 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6279 {
6282 }
6287 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6293 /* x < +Inf is always equal to x <= DBL_MAX. */
6299 /* x != +Inf is always equal to !(x > DBL_MAX). */
6311 }
6314 }
6316 /* Subroutine of fold() that optimizes comparisons of a division by
6317 a nonzero integer constant against an integer constant, i.e.
6318 X/C1 op C2.
6320 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6321 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6322 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6324 The function returns the constant folded tree if a simplification
6325 can be made, and NULL_TREE otherwise. */
6327 static tree
6330 {
6334 double_int val;
6339 /* We have to do this the hard way to detect unsigned overflow.
6340 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6350 {
6355 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6363 }
6365 {
6369 {
6388 }
6389 }
6390 else
6391 {
6392 /* A negative divisor reverses the relational operators. */
6398 {
6417 }
6418 }
6421 {
6442 {
6445 }
6450 {
6453 }
6458 {
6461 }
6466 {
6469 }
6474 }
6477 }
6480 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6481 equality/inequality test, then return a simplified form of the test
6482 using a sign testing. Otherwise return NULL. TYPE is the desired
6483 result type. */
6485 static tree
6488 tree result_type)
6489 {
6490 /* If this is testing a single bit, we can optimize the test. */
6494 {
6495 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6496 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6500 /* This is only a win if casting to a signed type is cheap,
6501 i.e. when arg00's type is not a partial mode. */
6504 {
6507 result_type,
6510 }
6511 }
6514 }
6516 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6517 equality/inequality test, then return a simplified form of
6518 the test using shifts and logical operations. Otherwise return
6519 NULL. TYPE is the desired result type. */
6521 tree
6524 {
6525 /* If this is testing a single bit, we can optimize the test. */
6529 {
6538 /* First, see if we can fold the single bit test into a sign-bit
6539 test. */
6541 result_type);
6545 /* Otherwise we have (A & C) != 0 where C is a single bit,
6546 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6547 Similarly for (A & C) == 0. */
6549 /* If INNER is a right shift of a constant and it plus BITNUM does
6550 not overflow, adjust BITNUM and INNER. */
6557 {
6560 }
6562 /* If we are going to be able to omit the AND below, we must do our
6563 operations as unsigned. If we must use the AND, we have a choice.
6564 Normally unsigned is faster, but for some machines signed is. */
6565 #ifdef LOAD_EXTEND_OP
6568 #else
6570 #endif
6586 /* Put the AND last so it can combine with more things. */
6589 /* Make sure to return the proper type. */
6593 }
6595 }
6597 /* Check whether we are allowed to reorder operands arg0 and arg1,
6598 such that the evaluation of arg1 occurs before arg0. */
6600 static bool
6602 {
6609 }
6611 /* Test whether it is preferable two swap two operands, ARG0 and
6612 ARG1, for example because ARG0 is an integer constant and ARG1
6613 isn't. If REORDER is true, only recommend swapping if we can
6614 evaluate the operands in reverse order. */
6616 bool
6618 {
6654 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6655 for commutative and comparison operators. Ensuring a canonical
6656 form allows the optimizers to find additional redundancies without
6657 having to explicitly check for both orderings. */
6663 /* Put SSA_NAMEs last. */
6669 /* Put variables last. */
6676 }
6678 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6679 ARG0 is extended to a wider type. */
6681 static tree
6684 {
6686 tree arg1_unw;
6695 #ifdef HAVE_canonicalize_funcptr_for_compare
6696 /* Disable this optimization if we're casting a function pointer
6697 type on targets that require function pointer canonicalization. */
6702 #endif
6709 /* If possible, express the comparison in the shorter mode. */
6729 /* If we are comparing with the integer that does not fit into the range
6730 of the shorter type, the result is known. */
6741 {
6768 }
6771 }
6773 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6774 ARG0 just the signedness is changed. */
6776 static tree
6779 {
6780 tree arg0_inner;
6790 #ifdef HAVE_canonicalize_funcptr_for_compare
6791 /* Disable this optimization if we're casting a function pointer
6792 type on targets that require function pointer canonicalization. */
6797 #endif
6816 else
6820 }
6822 /* Tries to replace &a[idx] p+ s * delta with &a[idx + delta], if s is
6823 step of the array. Reconstructs s and delta in the case of s *
6824 delta being an integer constant (and thus already folded). ADDR is
6825 the address. MULT is the multiplicative expression. If the
6826 function succeeds, the new address expression is returned.
6827 Otherwise NULL_TREE is returned. LOC is the location of the
6828 resulting expression. */
6830 static tree
6832 {
6836 tree itype;
6839 /* Strip the nops that might be added when converting op1 to sizetype. */
6842 /* Canonicalize op1 into a possibly non-constant delta
6843 and an INTEGER_CST s. */
6845 {
6852 {
6855 }
6857 {
6860 }
6861 else
6863 }
6865 {
6868 }
6869 else
6870 {
6871 /* Simulate we are delta * 1. */
6874 }
6877 {
6879 {
6880 tree domain;
6882 /* Remember if this was a multi-dimensional array. */
6896 {
6899 }
6900 else
6901 {
6902 /* Try if delta is a multiple of step. */
6907 }
6909 /* Only fold here if we can verify we do not overflow one
6910 dimension of a multi-dimensional array. */
6912 {
6913 tree tmp;
6928 }
6931 }
6932 else
6937 }
6939 /* We found the suitable array reference. So copy everything up to it,
6940 and replace the index. */
6948 {
6952 }
6960 }
6963 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6964 means A >= Y && A != MAX, but in this case we know that
6965 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6967 static tree
6969 {
6976 else
6985 {
6988 }
6990 {
6993 }
6994 else
7001 {
7002 /* Convert the pointer types into integer before taking the difference. */
7006 }
7007 else
7014 }
7016 /* Fold a sum or difference of at least one multiplication.
7017 Returns the folded tree or NULL if no simplification could be made. */
7019 static tree
7022 {
7026 /* (A * C) +- (B * C) -> (A+-B) * C.
7027 (A * C) +- A -> A * (C+-1).
7028 We are most concerned about the case where C is a constant,
7029 but other combinations show up during loop reduction. Since
7030 it is not difficult, try all four possibilities. */
7033 {
7036 }
7038 {
7041 }
7042 else
7043 {
7044 /* We cannot generate constant 1 for fract. */
7049 }
7051 {
7054 }
7056 {
7058 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7059 the purpose of this canonicalization. */
7063 {
7066 }
7067 else
7069 }
7070 else
7071 {
7072 /* We cannot generate constant 1 for fract. */
7077 }
7089 /* No identical multiplicands; see if we can find a common
7090 power-of-two factor in non-power-of-two multiplies. This
7091 can help in multi-dimensional array access. */
7094 {
7097 tree maybe_same;
7101 /* Move min of absolute values to int11. */
7104 {
7109 }
7110 else
7114 /* The remainder should not be a constant, otherwise we
7115 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7116 increased the number of multiplications necessary. */
7118 {
7126 }
7127 }
7137 }
7139 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7140 specified by EXPR into the buffer PTR of length LEN bytes.
7141 Return the number of bytes placed in the buffer, or zero
7142 upon failure. */
7144 static int
7146 {
7157 {
7161 else
7166 {
7173 else
7175 }
7176 else
7179 }
7181 }
7184 /* Subroutine of native_encode_expr. Encode the REAL_CST
7185 specified by EXPR into the buffer PTR of length LEN bytes.
7186 Return the number of bytes placed in the buffer, or zero
7187 upon failure. */
7189 static int
7191 {
7197 /* There are always 32 bits in each long, no matter the size of
7198 the hosts long. We handle floating point representations with
7199 up to 192 bits. */
7210 {
7215 {
7222 else
7224 }
7225 else
7228 }
7230 }
7232 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7233 specified by EXPR into the buffer PTR of length LEN bytes.
7234 Return the number of bytes placed in the buffer, or zero
7235 upon failure. */
7237 static int
7239 {
7241 tree part;
7252 }
7255 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7256 specified by EXPR into the buffer PTR of length LEN bytes.
7257 Return the number of bytes placed in the buffer, or zero
7258 upon failure. */
7260 static int
7262 {
7272 {
7274 {
7277 }
7278 else
7282 {
7285 }
7286 else
7287 {
7291 }
7293 }
7295 }
7298 /* Subroutine of native_encode_expr. Encode the STRING_CST
7299 specified by EXPR into the buffer PTR of length LEN bytes.
7300 Return the number of bytes placed in the buffer, or zero
7301 upon failure. */
7303 static int
7305 {
7307 HOST_WIDE_INT total_bytes;
7318 {
7322 }
7323 else
7326 }
7329 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7330 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7331 buffer PTR of length LEN bytes. Return the number of bytes
7332 placed in the buffer, or zero upon failure. */
7334 int
7336 {
7338 {
7356 }
7357 }
7360 /* Subroutine of native_interpret_expr. Interpret the contents of
7361 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7362 If the buffer cannot be interpreted, return NULL_TREE. */
7364 static tree
7366 {
7370 double_int result;
7381 {
7384 {
7391 else
7393 }
7394 else
7400 else
7403 }
7406 }
7409 /* Subroutine of native_interpret_expr. Interpret the contents of
7410 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7411 If the buffer cannot be interpreted, return NULL_TREE. */
7413 static tree
7415 {
7420 /* There are always 32 bits in each long, no matter the size of
7421 the hosts long. We handle floating point representations with
7422 up to 192 bits. */
7423 REAL_VALUE_TYPE r;
7434 {
7437 {
7444 else
7446 }
7447 else
7452 }
7456 }
7459 /* Subroutine of native_interpret_expr. Interpret the contents of
7460 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7461 If the buffer cannot be interpreted, return NULL_TREE. */
7463 static tree
7465 {
7480 }
7483 /* Subroutine of native_interpret_expr. Interpret the contents of
7484 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7485 If the buffer cannot be interpreted, return NULL_TREE. */
7487 static tree
7489 {
7501 {
7506 }
7508 }
7511 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7512 the buffer PTR of length LEN as a constant of type TYPE. For
7513 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7514 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7515 return NULL_TREE. */
7517 tree
7519 {
7521 {
7538 }
7539 }
7542 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7543 TYPE at compile-time. If we're unable to perform the conversion
7544 return NULL_TREE. */
7546 static tree
7548 {
7549 /* We support up to 512-bit values (for V8DFmode). */
7553 /* Check that the host and target are sane. */
7562 }
7564 /* Build an expression for the address of T. Folds away INDIRECT_REF
7565 to avoid confusing the gimplify process. */
7567 tree
7569 {
7570 /* The size of the object is not relevant when talking about its address. */
7575 {
7580 }
7585 {
7590 }
7591 else
7595 }
7597 /* Build an expression for the address of T. */
7599 tree
7601 {
7605 }
7607 /* Fold a unary expression of code CODE and type TYPE with operand
7608 OP0. Return the folded expression if folding is successful.
7609 Otherwise, return NULL_TREE. */
7611 static tree
7613 {
7614 tree tem;
7615 tree arg0;
7623 {
7626 {
7627 /* Don't use STRIP_NOPS, because signedness of argument type
7628 matters. */
7630 }
7631 else
7632 {
7633 /* Strip any conversions that don't change the mode. This
7634 is safe for every expression, except for a comparison
7635 expression because its signedness is derived from its
7636 operands.
7638 Note that this is done as an internal manipulation within
7639 the constant folder, in order to find the simplest
7640 representation of the arguments so that their form can be
7641 studied. In any cases, the appropriate type conversions
7642 should be put back in the tree that will get out of the
7643 constant folder. */
7645 }
7646 }
7649 {
7656 {
7670 /* If this was a conversion, and all we did was to move into
7671 inside the COND_EXPR, bring it back out. But leave it if
7672 it is a conversion from integer to integer and the
7673 result precision is no wider than a word since such a
7674 conversion is cheap and may be optimized away by combine,
7675 while it couldn't if it were outside the COND_EXPR. Then return
7676 so we don't get into an infinite recursion loop taking the
7677 conversion out and then back in. */
7689 && (INTEGRAL_TYPE_P
7702 }
7704 {
7706 {
7710 }
7714 integer_one_node),
7716 integer_zero_node));
7717 }
7718 }
7721 {
7723 /* Re-association barriers around constants and other re-association
7724 barriers can be removed. */
7730 CASE_CONVERT:
7736 /* If we have (type) (a CMP b) and type is an integral type, return
7737 new expression involving the new type. */
7742 /* Handle cases of two conversions in a row. */
7744 {
7766 /* In addition to the cases of two conversions in a row
7767 handled below, if we are converting something to its own
7768 type via an object of identical or wider precision, neither
7769 conversion is needed. */
7776 /* Likewise, if the intermediate and initial types are either both
7777 float or both integer, we don't need the middle conversion if the
7778 former is wider than the latter and doesn't change the signedness
7779 (for integers). Avoid this if the final type is a pointer since
7780 then we sometimes need the middle conversion. Likewise if the
7781 final type has a precision not equal to the size of its mode. */
7790 && ! final_ptr
7794 /* If we have a sign-extension of a zero-extended value, we can
7795 replace that by a single zero-extension. */
7801 /* Two conversions in a row are not needed unless:
7802 - some conversion is floating-point (overstrict for now), or
7803 - some conversion is a vector (overstrict for now), or
7804 - the intermediate type is narrower than both initial and
7805 final, or
7806 - the intermediate type and innermost type differ in signedness,
7807 and the outermost type is wider than the intermediate, or
7808 - the initial type is a pointer type and the precisions of the
7809 intermediate and final types differ, or
7810 - the final type is a pointer type and the precisions of the
7811 initial and intermediate types differ. */
7825 }
7827 /* Handle (T *)&A.B.C for A being of type T and B and C
7828 living at offset zero. This occurs frequently in
7829 C++ upcasting and then accessing the base. */
7833 {
7835 tree offset;
7841 /* If the reference was to a (constant) zero offset, we can use
7842 the address of the base if it has the same base type
7843 as the result type and the pointer type is unqualified. */
7850 }
7854 /* Detect assigning a bitfield. */
7856 && DECL_BIT_FIELD
7858 {
7859 /* Don't leave an assignment inside a conversion
7860 unless assigning a bitfield. */
7862 /* First do the assignment, then return converted constant. */
7867 }
7869 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7870 constants (if x has signed type, the sign bit cannot be set
7871 in c). This folds extension into the BIT_AND_EXPR.
7872 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7873 very likely don't have maximal range for their precision and this
7874 transformation effectively doesn't preserve non-maximal ranges. */
7878 {
7889 <= HOST_BITS_PER_WIDE_INT
7891 {
7898 #ifdef LOAD_EXTEND_OP
7900 && !flag_syntax_only
7903 {
7907 }
7908 #endif
7909 }
7911 {
7916 }
7917 }
7919 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type,
7920 when one of the new casts will fold away. Conservatively we assume
7921 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7927 {
7935 }
7937 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7938 of the same precision, and X is an integer type not narrower than
7939 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7945 {
7951 }
7953 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7954 type of X and Y (integer types only). */
7959 {
7960 /* Be careful not to introduce new overflows. */
7961 tree mult_type;
7964 else
7968 {
7975 }
7976 }
8000 /* For integral conversions with the same precision or pointer
8001 conversions use a NOP_EXPR instead. */
8009 /* Strip inner integral conversions that do not change the precision. */
8033 /* Convert fabs((double)float) into (double)fabsf(float). */
8036 {
8042 targ0));
8043 }
8044 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
8050 /* Strip sign ops from argument. */
8052 {
8057 }
8064 {
8070 }
8072 {
8077 }
8087 /* Convert ~ (-A) to A - 1. */
8092 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
8101 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8116 /* Perform BIT_NOT_EXPR on each element individually. */
8118 {
8123 {
8125 {
8131 }
8132 else
8135 }
8138 }
8143 /* The argument to invert_truthvalue must have Boolean type. */
8147 /* Note that the operand of this must be an int
8148 and its values must be 0 or 1.
8149 ("true" is a fixed value perhaps depending on the language,
8150 but we don't handle values other than 1 correctly yet.) */
8165 {
8173 }
8175 {
8180 }
8182 {
8186 {
8195 }
8196 }
8208 {
8216 }
8218 {
8222 }
8224 {
8228 {
8237 }
8238 }
8242 /* Fold *&X to X if X is an lvalue. */
8244 {
8251 }
8257 }
8259 /* Given an expression tree EXP, set the EXPR_FOLDED flag, and if it is
8260 a nop, recursively set the EXPR_FOLDED flag of its operand. */
8262 static void
8264 {
8267 /* If EXP is a nop (i.e. NON_LVALUE_EXPRs and NOP_EXPRs), we need to
8268 recursively set the EXPR_FOLDED flag of its operand because the
8269 expression will be stripped later. */
8273 {
8276 }
8277 }
8279 /* Fold a unary expression of code CODE and type TYPE with operand
8280 OP0. Return the folded expression if folding is successful.
8281 Otherwise, return NULL_TREE.
8282 This is a wrapper around fold_unary_1 function (which does the
8283 actual folding). Set the EXPR_FOLDED flag of the folded expression
8284 if folding is successful. */
8286 tree
8288 {
8293 }
8295 /* If the operation was a conversion do _not_ mark a resulting constant
8296 with TREE_OVERFLOW if the original constant was not. These conversions
8297 have implementation defined behavior and retaining the TREE_OVERFLOW
8298 flag here would confuse later passes such as VRP. */
8299 tree
8302 {
8311 }
8313 /* Fold a binary expression of code CODE and type TYPE with operands
8314 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8315 Return the folded expression if folding is successful. Otherwise,
8316 return NULL_TREE. */
8318 static tree
8320 {
8327 else
8330 /* MIN (MAX (a, b), b) == b. */
8335 /* MIN (MAX (b, a), b) == b. */
8341 /* MIN (a, MAX (a, b)) == a. */
8347 /* MIN (a, MAX (b, a)) == a. */
8354 }
8356 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8357 by changing CODE to reduce the magnitude of constants involved in
8358 ARG0 of the comparison.
8359 Returns a canonicalized comparison tree if a simplification was
8360 possible, otherwise returns NULL_TREE.
8361 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8362 valid if signed overflow is undefined. */
8364 static tree
8368 {
8374 /* Match A +- CST code arg1 and CST code arg1. We can change the
8375 first form only if overflow is undefined. */
8377 /* In principle pointers also have undefined overflow behavior,
8378 but that causes problems elsewhere. */
8386 /* Identify the constant in arg0 and its sign. */
8389 else
8393 /* Overflowed constants and zero will cause problems. */
8398 /* See if we can reduce the magnitude of the constant in
8399 arg0 by changing the comparison code. */
8401 {
8402 /* CST <= arg1 -> CST-1 < arg1. */
8405 /* -CST < arg1 -> -CST-1 <= arg1. */
8408 /* CST > arg1 -> CST-1 >= arg1. */
8411 /* -CST >= arg1 -> -CST-1 > arg1. */
8414 else
8416 /* arg1 code' CST' might be more canonical. */
8418 }
8419 else
8420 {
8421 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8425 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8429 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8433 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8437 else
8440 }
8442 /* Now build the constant reduced in magnitude. But not if that
8443 would produce one outside of its types range. */
8451 /* We cannot swap the comparison here as that would cause us to
8452 endlessly recurse. */
8460 /* If swapping might yield to a more canonical form, do so. */
8463 else
8465 }
8467 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8468 overflow further. Try to decrease the magnitude of constants involved
8469 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8470 and put sole constants at the second argument position.
8471 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8473 static tree
8476 {
8477 tree t;
8482 /* Try canonicalization by simplifying arg0. */
8487 {
8491 }
8493 /* Try canonicalization by simplifying arg1 using the swapped
8494 comparison. */
8502 }
8504 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8505 space. This is used to avoid issuing overflow warnings for
8506 expressions like &p->x which can not wrap. */
8508 static bool
8510 {
8521 {
8524 }
8527 else
8528 {
8531 }
8546 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8547 array. */
8549 {
8550 HOST_WIDE_INT base_size;
8555 }
8558 }
8560 /* Subroutine of fold_binary. This routine performs all of the
8561 transformations that are common to the equality/inequality
8562 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8563 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8564 fold_binary should call fold_binary. Fold a comparison with
8565 tree code CODE and type TYPE with operands OP0 and OP1. Return
8566 the folded comparison or NULL_TREE. */
8568 static tree
8571 {
8584 /* If one arg is a real or integer constant, put it last. */
8588 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8595 {
8599 tree lhs;
8606 /* If the constant operation overflowed this can be
8607 simplified as a comparison against INT_MAX/INT_MIN. */
8610 {
8614 /* Get the sign of the constant on the lhs if the
8615 operation were VARIABLE + CONST1. */
8619 /* The sign of the constant determines if we overflowed
8620 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8621 Canonicalize to the INT_MIN overflow by swapping the comparison
8622 if necessary. */
8626 /* We now can look at the canonicalized case
8627 VARIABLE + 1 CODE2 INT_MIN
8628 and decide on the result. */
8637 }
8642 {
8645 "when changing X +- C1 cmp C2 to "
8647 WARN_STRICT_OVERFLOW_COMPARISON);
8649 }
8650 }
8652 /* For comparisons of pointers we can decompose it to a compile time
8653 comparison of the base objects and the offsets into the object.
8654 This requires at least one operand being an ADDR_EXPR or a
8655 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8661 {
8668 /* Get base and offset for the access. Strip ADDR_EXPR for
8669 get_inner_reference, but put it back by stripping INDIRECT_REF
8670 off the base object if possible. indirect_baseN will be true
8671 if baseN is not an address but refers to the object itself. */
8674 {
8680 else
8682 }
8684 {
8688 {
8691 }
8693 }
8697 {
8703 else
8705 }
8707 {
8711 {
8714 }
8716 }
8718 /* A local variable can never be pointed to by
8719 the default SSA name of an incoming parameter. */
8721 && indirect_base0
8724 && !indirect_base1
8729 && indirect_base1
8732 && !indirect_base0
8736 {
8741 }
8742 /* If we have equivalent bases we might be able to simplify. */
8745 {
8746 /* We can fold this expression to a constant if the non-constant
8747 offset parts are equal. */
8755 {
8762 "occur when comparing P +- C1 with "
8764 WARN_STRICT_OVERFLOW_CONDITIONAL);
8767 {
8781 }
8782 }
8783 /* We can simplify the comparison to a comparison of the variable
8784 offset parts if the constant offset parts are equal.
8785 Be careful to use signed size type here because otherwise we
8786 mess with array offsets in the wrong way. This is possible
8787 because pointer arithmetic is restricted to retain within an
8788 object and overflow on pointer differences is undefined as of
8789 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8793 {
8794 /* By converting to signed size type we cover middle-end pointer
8795 arithmetic which operates on unsigned pointer types of size
8796 type size and ARRAY_REF offsets which are properly sign or
8797 zero extended from their type in case it is narrower than
8798 size type. */
8801 else
8805 else
8813 "occur when comparing P +- C1 with "
8815 WARN_STRICT_OVERFLOW_COMPARISON);
8818 }
8819 }
8820 /* For non-equal bases we can simplify if they are addresses
8821 of local binding decls or constants. */
8823 /* We know that !operand_equal_p (base0, base1, 0)
8824 because the if condition was false. But make
8825 sure two decls are not the same. */
8839 {
8846 }
8847 /* For equal offsets we can simplify to a comparison of the
8848 base addresses. */
8850 && (indirect_base0
8852 && (indirect_base1
8857 {
8863 }
8864 }
8866 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8867 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8868 the resulting offset is smaller in absolute value than the
8869 original one. */
8877 {
8882 tree cst;
8884 "occur when combining constants around "
8887 /* Put the constant on the side where it doesn't overflow and is
8888 of lower absolute value than before. */
8894 {
8897 variable1,
8901 }
8908 {
8913 variable2);
8914 }
8915 }
8917 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8918 signed arithmetic case. That form is created by the compiler
8919 often enough for folding it to be of value. One example is in
8920 computing loop trip counts after Operator Strength Reduction. */
8926 {
8932 /* Handle unfolded multiplication by zero. */
8937 "eliminating multiplication in comparison "
8939 WARN_STRICT_OVERFLOW_COMPARISON);
8941 /* If const1 is negative we swap the sense of the comparison. */
8946 }
8953 {
8961 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8967 /* (-a) CMP (-b) -> b CMP a */
8974 {
8975 REAL_VALUE_TYPE cst;
8978 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8985 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8986 /* a CMP (-0) -> a CMP 0 */
8991 /* x != NaN is always true, other ops are always false. */
8994 {
8997 }
8999 /* Fold comparisons against infinity. */
9002 {
9006 }
9007 }
9009 /* If this is a comparison of a real constant with a PLUS_EXPR
9010 or a MINUS_EXPR of a real constant, we can convert it into a
9011 comparison with a revised real constant as long as no overflow
9012 occurs when unsafe_math_optimizations are enabled. */
9024 /* Likewise, we can simplify a comparison of a real constant with
9025 a MINUS_EXPR whose first operand is also a real constant, i.e.
9026 (c1 - x) < c2 becomes x > c1-c2. Reordering is allowed on
9027 floating-point types only if -fassociative-math is set. */
9033 arg1))
9038 /* Fold comparisons against built-in math functions. */
9040 && flag_unsafe_math_optimizations
9042 {
9046 {
9050 }
9051 }
9052 }
9056 {
9057 /* If we are widening one operand of an integer comparison,
9058 see if the other operand is similarly being widened. Perhaps we
9059 can do the comparison in the narrower type. */
9064 /* Or if we are changing signedness. */
9068 }
9070 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
9071 constant, we can simplify it. */
9076 {
9080 }
9082 /* Simplify comparison of something with itself. (For IEEE
9083 floating-point, we can only do some of these simplifications.) */
9085 {
9087 {
9102 /* For NE, we can only do this simplification if integer
9103 or we don't honor IEEE floating point NaNs. */
9107 /* ... fall through ... */
9113 }
9114 }
9116 /* If we are comparing an expression that just has comparisons
9117 of two integer values, arithmetic expressions of those comparisons,
9118 and constants, we can simplify it. There are only three cases
9119 to check: the two values can either be equal, the first can be
9120 greater, or the second can be greater. Fold the expression for
9121 those three values. Since each value must be 0 or 1, we have
9122 eight possibilities, each of which corresponds to the constant 0
9123 or 1 or one of the six possible comparisons.
9125 This handles common cases like (a > b) == 0 but also handles
9126 expressions like ((x > y) - (y > x)) > 0, which supposedly
9127 occur in macroized code. */
9130 {
9135 /* Don't handle degenerate cases here; they should already
9136 have been handled anyway. */
9145 {
9149 /* We can't just pass T to eval_subst in case cval1 or cval2
9150 was the same as ARG1. */
9152 tree high_result
9156 arg1);
9157 tree equal_result
9161 arg1);
9162 tree low_result
9166 arg1);
9168 /* All three of these results should be 0 or 1. Confirm they are.
9169 Then use those values to select the proper code to use. */
9174 {
9175 /* Make a 3-bit mask with the high-order bit being the
9176 value for `>', the next for '=', and the low for '<'. */
9180 {
9182 /* Always false. */
9203 /* Always true. */
9205 }
9208 {
9212 }
9214 }
9215 }
9216 }
9218 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
9219 into a single range test. */
9227 {
9231 }
9233 /* Fold ~X op ~Y as Y op X. */
9236 {
9242 }
9244 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
9247 {
9253 }
9256 }
9259 /* Subroutine of fold_binary. Optimize complex multiplications of the
9260 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
9261 argument EXPR represents the expression "z" of type TYPE. */
9263 static tree
9265 {
9270 {
9273 }
9275 {
9278 }
9279 else
9280 {
9284 }
9293 }
9296 /* Subroutine of fold_binary. If P is the value of EXPR, computes
9297 power-of-two M and (arbitrary) N such that M divides (P-N). This condition
9298 guarantees that P and N have the same least significant log2(M) bits.
9299 N is not otherwise constrained. In particular, N is not normalized to
9300 0 <= N < M as is common. In general, the precise value of P is unknown.
9301 M is chosen as large as possible such that constant N can be determined.
9303 Returns M and sets *RESIDUE to N.
9305 If ALLOW_FUNC_ALIGN is true, do take functions' DECL_ALIGN_UNIT into
9306 account. This is not always possible due to PR 35705.
9307 */
9309 static unsigned HOST_WIDE_INT
9312 {
9319 {
9322 {
9324 tree offset;
9332 {
9335 else
9336 /* We don't handle more complicated offset expressions. */
9338 }
9339 }
9344 }
9346 {
9354 allow_func_align);
9360 {
9363 }
9365 {
9368 {
9371 /* Compute the greatest power-of-2 divisor of op1. */
9375 /* If align is non-zero and less than *modulus, replace
9376 *modulus with align., If align is 0, then either op1 is 0
9377 or the greatest power-of-2 divisor of op1 doesn't fit in an
9378 unsigned HOST_WIDE_INT. In either case, no additional
9379 constraint is imposed. */
9384 }
9385 }
9386 }
9388 /* If we get here, we were unable to determine anything useful about the
9389 expression. */
9391 }
9394 /* Fold a binary expression of code CODE and type TYPE with operands
9395 OP0 and OP1. LOC is the location of the resulting expression.
9396 Return the folded expression if folding is successful. Otherwise,
9397 return NULL_TREE. */
9399 static tree
9402 {
9416 /* Strip any conversions that don't change the mode. This is
9417 safe for every expression, except for a comparison expression
9418 because its signedness is derived from its operands. So, in
9419 the latter case, only strip conversions that don't change the
9420 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9421 preserved.
9423 Note that this is done as an internal manipulation within the
9424 constant folder, in order to find the simplest representation
9425 of the arguments so that their form can be studied. In any
9426 cases, the appropriate type conversions should be put back in
9427 the tree that will get out of the constant folder. */
9430 {
9433 }
9434 else
9435 {
9438 }
9440 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9441 constant but we can't do arithmetic on them. */
9448 {
9450 {
9451 /* Make sure type and arg0 have the same saturating flag. */
9455 }
9458 else
9462 {
9466 }
9467 }
9469 /* If this is a commutative operation, and ARG0 is a constant, move it
9470 to ARG1 to reduce the number of tests below. */
9475 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9477 First check for cases where an arithmetic operation is applied to a
9478 compound, conditional, or comparison operation. Push the arithmetic
9479 operation inside the compound or conditional to see if any folding
9480 can then be done. Convert comparison to conditional for this purpose.
9481 The also optimizes non-constant cases that used to be done in
9482 expand_expr.
9484 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9485 one of the operands is a comparison and the other is a comparison, a
9486 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9487 code below would make the expression more complex. Change it to a
9488 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9489 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9501 {
9505 boolean_type_node,
9513 }
9517 {
9519 {
9524 tem);
9525 }
9528 {
9533 tem);
9534 }
9537 {
9543 }
9546 {
9552 }
9553 }
9556 {
9558 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9561 {
9567 }
9569 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9572 {
9573 tree base;
9574 HOST_WIDE_INT coffset;
9583 }
9588 /* 0 +p index -> (type)index */
9592 /* PTR +p 0 -> PTR */
9596 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9602 arg1),
9604 arg0)));
9606 /* index +p PTR -> PTR +p index */
9613 /* (PTR +p B) +p A -> PTR +p (B + A) */
9615 {
9616 tree inner;
9625 }
9627 /* PTR_CST +p CST -> CST1 */
9632 /* Try replacing &a[i1] +p c * i2 with &a[i1 + i2], if c is step
9633 of the array. Loop optimizer sometimes produce this type of
9634 expressions. */
9636 {
9641 }
9646 /* A + (-B) -> A - B */
9652 /* (-A) + B -> B - A */
9661 {
9662 /* Convert ~A + 1 to -A. */
9669 /* ~X + X is -1. */
9672 {
9677 {
9680 }
9681 }
9683 /* X + ~X is -1. */
9686 {
9691 {
9694 }
9695 }
9697 /* X + (X / CST) * -CST is X % CST. */
9702 {
9711 cst0));
9712 }
9713 }
9715 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9716 same or one. Make sure type is not saturating.
9717 fold_plusminus_mult_expr will re-associate. */
9722 {
9726 }
9729 {
9733 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9734 with a constant, and the two constants have no bits in common,
9735 we should treat this as a BIT_IOR_EXPR since this may produce more
9736 simplifications. */
9744 {
9747 }
9749 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9750 (plus (plus (mult) (mult)) (foo)) so that we can
9751 take advantage of the factoring cases below. */
9758 {
9764 else
9777 parg0),
9779 marg)),
9783 return
9789 parg1)));
9790 }
9791 }
9792 else
9793 {
9794 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9798 /* Likewise if the operands are reversed. */
9802 /* Convert X + -C into X - C. */
9805 {
9811 }
9813 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9814 to __complex__ ( x, y ). This is not the same for SNaNs or
9815 if signed zeros are involved. */
9819 {
9826 {
9830 {
9836 }
9838 {
9844 }
9845 }
9846 }
9854 /* Convert x+x into x*2.0. */
9860 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9861 We associate floats only if the user has specified
9862 -fassociative-math. */
9866 {
9871 {
9872 tree tree0;
9875 }
9876 }
9877 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9878 We associate floats only if the user has specified
9879 -fassociative-math. */
9883 {
9888 {
9889 tree tree0;
9892 }
9893 }
9894 }
9896 bit_rotate:
9897 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9898 is a rotate of A by C1 bits. */
9899 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9900 is a rotate of A by B bits. */
9901 {
9903 tree rtype;
9912 /* Only create rotates in complete modes. Other cases are not
9913 expanded properly. */
9915 {
9931 {
9937 }
9939 {
9947 TYPE_PRECISION
9951 return
9954 ? LROTATE_EXPR
9958 }
9960 {
9968 TYPE_PRECISION
9972 return fold_convert_loc
9975 ? LROTATE_EXPR
9979 }
9980 }
9981 }
9983 associate:
9984 /* In most languages, can't associate operations on floats through
9985 parentheses. Rather than remember where the parentheses were, we
9986 don't associate floats at all, unless the user has specified
9987 -fassociative-math.
9988 And, we need to make sure type is not saturating. */
9992 {
9997 /* Split both trees into variables, constants, and literals. Then
9998 associate each group together, the constants with literals,
9999 then the result with variables. This increases the chances of
10000 literals being recombined later and of generating relocatable
10001 expressions for the sum of a constant and literal. */
10006 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
10010 /* With undefined overflow we can only associate constants with one
10011 variable, and constants whose association doesn't overflow. */
10014 {
10016 {
10024 /* The only case we can still associate with two variables
10025 is if they are the same, modulo negation. */
10028 }
10031 {
10038 }
10039 }
10041 /* Only do something if we found more than two objects. Otherwise,
10042 nothing has changed and we risk infinite recursion. */
10048 {
10054 /* Preserve the MINUS_EXPR if the negative part of the literal is
10055 greater than the positive part. Otherwise, the multiplicative
10056 folding code (i.e extract_muldiv) may be fooled in case
10057 unsigned constants are subtracted, like in the following
10058 example: ((X*2 + 4) - 8U)/2. */
10060 {
10064 {
10068 }
10069 else
10070 {
10074 }
10075 }
10077 {
10079 return
10083 else
10084 {
10087 return
10091 }
10092 }
10095 return
10098 }
10099 }
10104 /* Pointer simplifications for subtraction, simple reassociations. */
10106 {
10107 /* (PTR0 p+ A) - (PTR1 p+ B) -> (PTR0 - PTR1) + (A - B) */
10110 {
10120 }
10121 /* (PTR0 p+ A) - PTR1 -> (PTR0 - PTR1) + A, assuming PTR0 - PTR1 simplifies. */
10123 {
10130 }
10131 }
10132 /* A - (-B) -> A + B */
10137 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10148 /* Convert -A - 1 to ~A. */
10157 /* Convert -1 - A to ~A. */
10163 /* X - (X / CST) * CST is X % CST. */
10171 return
10177 {
10183 /* Fold A - (A & B) into ~B & A. */
10186 {
10188 {
10195 }
10197 {
10204 }
10205 }
10207 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
10208 any power of 2 minus 1. */
10213 {
10219 {
10223 }
10224 }
10225 }
10227 /* See if ARG1 is zero and X - ARG1 reduces to X. */
10231 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
10232 ARG0 is zero and X + ARG0 reduces to X, since that would mean
10233 (-ARG1 + ARG0) reduces to -ARG1. */
10237 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10238 __complex__ ( x, -y ). This is not the same for SNaNs or if
10239 signed zeros are involved. */
10243 {
10250 {
10254 {
10256 arg1r ? arg1r
10261 }
10263 {
10267 arg1i ? arg1i
10270 }
10271 }
10272 }
10274 /* Fold &x - &x. This can happen from &x.foo - &x.
10275 This is unsafe for certain floats even in non-IEEE formats.
10276 In IEEE, it is unsafe because it does wrong for NaNs.
10277 Also note that operand_equal_p is always false if an operand
10278 is volatile. */
10284 /* A - B -> A + (-B) if B is easily negatable. */
10287 /* Avoid this transformation if B is a positive REAL_CST. */
10296 /* Try folding difference of addresses. */
10297 {
10298 HOST_WIDE_INT diff;
10304 }
10306 /* Fold &a[i] - &a[j] to i-j. */
10311 {
10316 {
10324 }
10325 }
10328 && flag_unsafe_math_optimizations
10334 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
10335 same or one. Make sure type is not saturating.
10336 fold_plusminus_mult_expr will re-associate. */
10341 {
10345 }
10350 /* (-A) * (-B) -> A * B */
10365 {
10370 /* Transform x * -1 into -x. Make sure to do the negation
10371 on the original operand with conversions not stripped
10372 because we can only strip non-sign-changing conversions. */
10375 /* Transform x * -C into -x * C if x is easily negatable. */
10384 tem);
10386 /* (a * (1 << b)) is (a << b) */
10396 /* (A + A) * C -> A * 2 * C */
10412 {
10415 "occur when simplifying "
10417 WARN_STRICT_OVERFLOW_MISC);
10419 }
10421 /* Optimize z * conj(z) for integer complex numbers. */
10428 }
10429 else
10430 {
10431 /* Maybe fold x * 0 to 0. The expressions aren't the same
10432 when x is NaN, since x * 0 is also NaN. Nor are they the
10433 same in modes with signed zeros, since multiplying a
10434 negative value by 0 gives -0, not +0. */
10439 /* In IEEE floating point, x*1 is not equivalent to x for snans.
10440 Likewise for complex arithmetic with signed zeros. */
10447 /* Transform x * -1.0 into -x. */
10454 /* Convert (C1/X)*C2 into (C1*C2)/X. This transformation may change
10455 the result for floating point types due to rounding so it is applied
10456 only if -fassociative-math was specify. */
10461 {
10463 arg1);
10467 }
10469 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
10471 {
10474 {
10477 }
10478 }
10480 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10481 This is not the same for NaNs or if signed zeros are
10482 involved. */
10488 {
10491 return
10497 return
10502 }
10504 /* Optimize z * conj(z) for floating point complex numbers.
10505 Guarded by flag_unsafe_math_optimizations as non-finite
10506 imaginary components don't produce scalar results. */
10517 {
10521 /* Optimizations of root(...)*root(...). */
10523 {
10528 /* Optimize sqrt(x)*sqrt(x) as x. */
10534 /* Optimize root(x)*root(y) as root(x*y). */
10538 }
10540 /* Optimize expN(x)*expN(y) as expN(x+y). */
10542 {
10548 }
10550 /* Optimizations of pow(...)*pow(...). */
10554 {
10560 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
10562 {
10567 }
10569 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
10571 {
10576 }
10577 }
10579 /* Optimize tan(x)*cos(x) as sin(x). */
10588 {
10594 }
10596 /* Optimize x*pow(x,c) as pow(x,c+1). */
10600 {
10606 {
10608 REAL_VALUE_TYPE c;
10609 tree arg;
10615 }
10616 }
10618 /* Optimize pow(x,c)*x as pow(x,c+1). */
10622 {
10628 {
10630 REAL_VALUE_TYPE c;
10631 tree arg;
10637 }
10638 }
10640 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
10643 {
10647 {
10650 }
10651 }
10652 }
10653 }
10657 bit_ior:
10665 /* ~X | X is -1. */
10668 {
10672 }
10674 /* X | ~X is -1. */
10677 {
10681 }
10683 /* Canonicalize (X & C1) | C2. */
10687 {
10693 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10700 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10706 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10707 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10708 mode which allows further optimizations. */
10715 {
10716 unsigned HOST_WIDE_INT mask
10720 {
10723 }
10724 }
10730 c3)),
10731 arg1);
10732 }
10734 /* (X & Y) | Y is (X, Y). */
10738 /* (X & Y) | X is (Y, X). */
10743 /* X | (X & Y) is (Y, X). */
10748 /* X | (Y & X) is (Y, X). */
10758 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10760 This results in more efficient code for machines without a NAND
10761 instruction. Combine will canonicalize to the first form
10762 which will allow use of NAND instructions provided by the
10763 backend if they exist. */
10766 {
10767 return
10774 }
10776 /* See if this can be simplified into a rotate first. If that
10777 is unsuccessful continue in the association code. */
10788 /* ~X ^ X is -1. */
10791 {
10795 }
10797 /* X ^ ~X is -1. */
10800 {
10804 }
10806 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10807 with a constant, and the two constants have no bits in common,
10808 we should treat this as a BIT_IOR_EXPR since this may produce more
10809 simplifications. */
10817 {
10820 }
10822 /* (X | Y) ^ X -> Y & ~ X*/
10825 {
10828 arg1);
10833 }
10835 /* (Y | X) ^ X -> Y & ~ X*/
10838 {
10841 arg1);
10846 }
10848 /* X ^ (X | Y) -> Y & ~ X*/
10851 {
10854 arg0);
10859 }
10861 /* X ^ (Y | X) -> Y & ~ X*/
10864 {
10867 arg0);
10872 }
10874 /* Convert ~X ^ ~Y to X ^ Y. */
10883 /* Convert ~X ^ C to X ^ ~C. */
10891 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10898 /* Fold (X & Y) ^ Y as ~X & Y. */
10901 {
10906 }
10907 /* Fold (X & Y) ^ X as ~Y & X. */
10911 {
10916 }
10917 /* Fold X ^ (X & Y) as X & ~Y. */
10920 {
10925 }
10926 /* Fold X ^ (Y & X) as ~Y & X. */
10930 {
10935 }
10937 /* See if this can be simplified into a rotate first. If that
10938 is unsuccessful continue in the association code. */
10949 /* ~X & X is always zero. */
10954 /* X & ~X is always zero. */
10959 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10963 {
10969 return
10973 }
10975 /* (X | Y) & Y is (X, Y). */
10979 /* (X | Y) & X is (Y, X). */
10984 /* X & (X | Y) is (Y, X). */
10989 /* X & (Y | X) is (Y, X). */
10995 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10999 {
11005 }
11006 /* Fold ~X & 1 as (X & 1) == 0. */
11009 {
11015 }
11017 /* Fold (X ^ Y) & Y as ~X & Y. */
11020 {
11025 }
11026 /* Fold (X ^ Y) & X as ~Y & X. */
11030 {
11035 }
11036 /* Fold X & (X ^ Y) as X & ~Y. */
11039 {
11044 }
11045 /* Fold X & (Y ^ X) as ~Y & X. */
11049 {
11054 }
11056 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11057 ((A & N) + B) & M -> (A + B) & M
11058 Similarly if (N & M) == 0,
11059 ((A | N) + B) & M -> (A + B) & M
11060 and for - instead of + (or unary - instead of +)
11061 and/or ^ instead of |.
11062 If B is constant and (B & M) == 0, fold into A & M. */
11064 {
11073 {
11078 /* Now we know that arg0 is (C + D) or (C - D) or
11079 -C and arg1 (M) is == (1LL << cst) - 1.
11080 Store C into PMOP[0] and D into PMOP[1]. */
11084 {
11087 }
11096 {
11103 /* tree_low_cst not used, because we don't care about
11104 the upper bits. */
11108 {
11111 }
11114 /* If C or D is of the form (A & N) where
11115 (N & M) == M, or of the form (A | N) or
11116 (A ^ N) where (N & M) == 0, replace it with A. */
11120 /* If C or D is a N where (N & M) == 0, it can be
11121 omitted (assumed 0). */
11129 }
11131 /* Only build anything new if we optimized one or both arguments
11132 above. */
11136 {
11139 {
11140 /* Perform the operations in a type that has defined
11141 overflow behavior. */
11147 }
11152 {
11160 else
11162 }
11165 else
11168 /* TEM is now the new binary +, - or unary - replacement. */
11172 }
11173 }
11174 }
11179 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
11182 {
11183 unsigned int prec
11189 return
11191 }
11193 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
11195 This results in more efficient code for machines without a NOR
11196 instruction. Combine will canonicalize to the first form
11197 which will allow use of NOR instructions provided by the
11198 backend if they exist. */
11201 {
11208 }
11210 /* If arg0 is derived from the address of an object or function, we may
11211 be able to fold this expression using the object or function's
11212 alignment. */
11214 {
11221 /* This works because modulus is a power of 2. If this weren't the
11222 case, we'd have to replace it by its greatest power-of-2
11223 divisor: modulus & -modulus. */
11226 }
11228 /* Fold (X << C1) & C2 into (X << C1) & (C2 | ((1 << C1) - 1))
11229 (X >> C1) & C2 into (X >> C1) & (C2 | ~((type) -1 >> C1))
11230 if the new mask might be further optimized. */
11239 {
11241 unsigned HOST_WIDE_INT mask
11251 {
11254 /* See if more bits can be proven as zero because of
11255 zero extension. */
11258 {
11263 {
11265 /* See if we can shorten the right shift. */
11268 }
11269 }
11273 /* For arithmetic shift if sign bit could be set, zerobits
11274 can contain actually sign bits, so no transformation is
11275 possible, unless MASK masks them all away. In that
11276 case the shift needs to be converted into logical shift. */
11279 {
11282 else
11284 }
11285 }
11287 /* ((X << 16) & 0xff00) is (X, 0). */
11294 {
11297 /* Only do the transformation if NEWMASK is some integer
11298 mode's mask. */
11305 {
11306 tree newmaskt;
11309 {
11315 }
11316 else
11321 }
11322 }
11323 }
11328 /* Don't touch a floating-point divide by zero unless the mode
11329 of the constant can represent infinity. */
11335 /* Optimize A / A to 1.0 if we don't care about
11336 NaNs or Infinities. Skip the transformation
11337 for non-real operands. */
11342 {
11346 }
11348 /* The complex version of the above A / A optimization. */
11351 {
11355 {
11357 /* omit_two_operands will call fold_convert for us. */
11359 }
11360 }
11362 /* (-A) / (-B) -> A / B */
11372 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
11377 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
11383 /* If ARG1 is a constant, we can convert this to a multiply by the
11384 reciprocal. This does not have the same rounding properties,
11385 so only do this if -freciprocal-math. We can actually
11386 always safely do it if ARG1 is a power of two, but it's hard to
11387 tell if it is or not in a portable manner. */
11389 {
11392 arg1)))
11394 /* Find the reciprocal if optimizing and the result is exact. */
11396 {
11397 REAL_VALUE_TYPE r;
11400 {
11404 }
11405 }
11406 }
11407 /* Convert A/B/C to A/(B*C). */
11414 /* Convert A/(B/C) to (A/B)*C. */
11422 /* Convert C1/(X*C2) into (C1/C2)/X. */
11427 {
11433 }
11436 {
11440 /* Optimize sin(x)/cos(x) as tan(x). */
11446 {
11451 }
11453 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
11459 {
11463 {
11468 }
11469 }
11471 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
11472 NaNs or Infinities. */
11476 {
11483 {
11488 }
11489 }
11491 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
11492 NaNs or Infinities. */
11496 {
11503 {
11507 {
11511 tmp);
11512 }
11513 }
11514 }
11516 /* Optimize pow(x,c)/x as pow(x,c-1). */
11520 {
11526 {
11528 REAL_VALUE_TYPE c;
11529 tree arg;
11535 }
11536 }
11538 /* Optimize a/root(b/c) into a*root(c/b). */
11540 {
11544 {
11553 }
11554 }
11556 /* Optimize x/expN(y) into x*expN(-y). */
11558 {
11565 }
11567 /* Optimize x/pow(y,z) into x*pow(y,-z). */
11571 {
11579 }
11580 }
11584 /* Optimize (X & (-A)) / A where A is a power of 2,
11585 to X >> log2(A) */
11589 {
11597 else
11604 }
11605 }
11607 /* Fall thru */
11610 /* Simplify A / (B << N) where A and B are positive and B is
11611 a power of 2, to A >> (N + log2(B)). */
11616 {
11619 {
11625 else
11632 WARN_STRICT_OVERFLOW_MISC);
11638 }
11639 }
11641 /* For unsigned integral types, FLOOR_DIV_EXPR is the same as
11642 TRUNC_DIV_EXPR. Rewrite into the latter in this case. */
11648 /* Fall thru */
11657 /* X / -1 is -X. */
11664 /* Convert -A / -B to A / B when the type is signed and overflow is
11665 undefined. */
11669 {
11672 "when distributing negation across "
11674 WARN_STRICT_OVERFLOW_MISC);
11680 }
11684 {
11687 "when distributing negation across "
11689 WARN_STRICT_OVERFLOW_MISC);
11695 }
11697 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
11698 operation, EXACT_DIV_EXPR.
11700 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
11701 At one time others generated faster code, it's not clear if they do
11702 after the last round to changes to the DIV code in expmed.c. */
11711 {
11715 WARN_STRICT_OVERFLOW_MISC);
11717 }
11725 /* X % 1 is always zero, but be sure to preserve any side
11726 effects in X. */
11730 /* X % 0, return X % 0 unchanged so that we can get the
11731 proper warnings and errors. */
11735 /* 0 % X is always zero, but be sure to preserve any side
11736 effects in X. Place this after checking for X == 0. */
11740 /* X % -1 is zero. */
11747 /* X % -C is the same as X % C. */
11754 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
11761 /* X % -Y is the same as X % Y. */
11774 {
11778 WARN_STRICT_OVERFLOW_MISC);
11780 }
11782 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
11783 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
11787 {
11789 /* Also optimize A % (C << N) where C is a power of 2,
11790 to A & ((C << N) - 1). */
11795 {
11796 tree mask
11801 "occur when simplifying "
11803 WARN_STRICT_OVERFLOW_MISC);
11807 }
11808 }
11819 /* Optimize -1 >> x for arithmetic right shifts. */
11823 /* ... fall through ... */
11826 shift:
11832 /* Since negative shift count is not well-defined,
11833 don't try to compute it in the compiler. */
11837 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
11842 {
11846 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
11847 being well defined. */
11849 {
11855 else
11857 }
11861 }
11863 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
11864 into x & ((unsigned)-1 >> c) for unsigned types. */
11872 {
11875 tree lshift;
11876 tree arg00;
11879 {
11886 }
11887 }
11889 /* Rewrite an LROTATE_EXPR by a constant into an
11890 RROTATE_EXPR by a new constant. */
11892 {
11897 }
11899 /* If we have a rotate of a bit operation with the rotate count and
11900 the second operand of the bit operation both constant,
11901 permute the two operations. */
11913 /* Two consecutive rotates adding up to the precision of the
11914 type can be ignored. */
11925 /* Fold (X & C2) << C1 into (X << C1) & (C2 << C1)
11926 (X & C2) >> C1 into (X >> C1) & (C2 >> C1)
11927 if the latter can be further optimized. */
11932 {
11936 arg1);
11940 arg1);
11944 }
11972 /* Note that the operands of this must be ints
11973 and their values must be 0 or 1.
11974 ("true" is a fixed value perhaps depending on the language.) */
11975 /* If first arg is constant zero, return it. */
11979 /* If either arg is constant true, drop it. */
11983 /* Preserve sequence points. */
11986 /* If second arg is constant zero, result is zero, but first arg
11987 must be evaluated. */
11990 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
11991 case will be handled here. */
11995 /* !X && X is always false. */
11999 /* X && !X is always false. */
12004 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
12005 means A >= Y && A != MAX, but in this case we know that
12006 A < X <= MAX. */
12010 {
12018 }
12020 truth_andor:
12021 /* We only do these simplifications if we are optimizing. */
12025 /* Check for things like (A || B) && (A || C). We can convert this
12026 to A || (B && C). Note that either operator can be any of the four
12027 truth and/or operations and the transformation will still be
12028 valid. Also note that we only care about order for the
12029 ANDIF and ORIF operators. If B contains side effects, this
12030 might change the truth-value of A. */
12037 {
12057 /* This case if tricky because we must either have commutative
12058 operators or else A10 must not have side-effects. */
12064 a01);
12065 }
12067 /* See if we can build a range comparison. */
12073 {
12077 }
12081 {
12085 }
12087 /* Check for the possibility of merging component references. If our
12088 lhs is another similar operation, try to merge its rhs with our
12089 rhs. Then try to merge our lhs and rhs. */
12101 /* Note that the operands of this must be ints
12102 and their values must be 0 or true.
12103 ("true" is a fixed value perhaps depending on the language.) */
12104 /* If first arg is constant true, return it. */
12108 /* If either arg is constant zero, drop it. */
12112 /* Preserve sequence points. */
12115 /* If second arg is constant true, result is true, but we must
12116 evaluate first arg. */
12119 /* Likewise for first arg, but note this only occurs here for
12120 TRUTH_OR_EXPR. */
12124 /* !X || X is always true. */
12128 /* X || !X is always true. */
12136 /* If the second arg is constant zero, drop it. */
12139 /* If the second arg is constant true, this is a logical inversion. */
12141 {
12142 /* Only call invert_truthvalue if operand is a truth value. */
12145 else
12148 }
12149 /* Identical arguments cancel to zero. */
12153 /* !X ^ X is always true. */
12158 /* X ^ !X is always true. */
12171 /* bool_var != 0 becomes bool_var. */
12176 /* bool_var == 1 becomes bool_var. */
12181 /* bool_var != 1 becomes !bool_var. */
12187 /* bool_var == 0 becomes !bool_var. */
12193 /* !exp != 0 becomes !exp */
12198 /* If this is an equality comparison of the address of two non-weak,
12199 unaliased symbols neither of which are extern (since we do not
12200 have access to attributes for externs), then we know the result. */
12213 {
12214 /* We know that we're looking at the address of two
12215 non-weak, unaliased, static _DECL nodes.
12217 It is both wasteful and incorrect to call operand_equal_p
12218 to compare the two ADDR_EXPR nodes. It is wasteful in that
12219 all we need to do is test pointer equality for the arguments
12220 to the two ADDR_EXPR nodes. It is incorrect to use
12221 operand_equal_p as that function is NOT equivalent to a
12222 C equality test. It can in fact return false for two
12223 objects which would test as equal using the C equality
12224 operator. */
12228 type);
12229 }
12231 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
12232 a MINUS_EXPR of a constant, we can convert it into a comparison with
12233 a revised constant as long as no overflow occurs. */
12241 arg1),
12246 /* Similarly for a NEGATE_EXPR. */
12254 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
12262 arg1),
12265 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
12272 {
12276 val,
12280 }
12282 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
12287 {
12289 code == NE_EXPR
12292 }
12294 /* If we have X - Y == 0, we can convert that to X == Y and similarly
12295 for !=. Don't do this for ordered comparisons due to overflow. */
12301 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
12306 /* If this is an EQ or NE comparison with zero and ARG0 is
12307 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
12308 two operations, but the latter can be done in one less insn
12309 on machines that have only two-operand insns or on which a
12310 constant cannot be the first operand. */
12313 {
12318 {
12325 arg1);
12326 }
12329 {
12336 arg1);
12337 }
12338 }
12340 /* If this is an NE or EQ comparison of zero against the result of a
12341 signed MOD operation whose second operand is a power of 2, make
12342 the MOD operation unsigned since it is simpler and equivalent. */
12350 {
12360 }
12362 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
12363 C1 is a valid shift constant, and C2 is a power of two, i.e.
12364 a single bit. */
12368 == INTEGER_CST
12371 {
12376 /* Check for a valid shift count. */
12379 {
12383 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
12384 can be rewritten as (X & (C2 << C1)) != 0. */
12386 {
12390 }
12391 /* Otherwise, for signed (arithmetic) shifts,
12392 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
12393 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
12397 /* Otherwise, of unsigned (logical) shifts,
12398 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
12399 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
12400 else
12404 arg000);
12405 }
12406 }
12408 /* If this is an NE comparison of zero with an AND of one, remove the
12409 comparison since the AND will give the correct value. */
12416 /* If we have (A & C) == C where C is a power of 2, convert this into
12417 (A & C) != 0. Similarly for NE_EXPR. */
12423 integer_zero_node));
12425 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
12426 bit, then fold the expression into A < 0 or A >= 0. */
12431 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
12432 Similarly for NE_EXPR. */
12436 {
12445 }
12447 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
12448 Similarly for NE_EXPR. */
12452 {
12459 }
12461 /* If this is a comparison of a field, we may be able to simplify it. */
12464 /* Handle the constant case even without -O
12465 to make sure the warnings are given. */
12467 {
12471 }
12473 /* Optimize comparisons of strlen vs zero to a compare of the
12474 first character of the string vs zero. To wit,
12475 strlen(ptr) == 0 => *ptr == 0
12476 strlen(ptr) != 0 => *ptr != 0
12477 Other cases should reduce to one of these two (or a constant)
12478 due to the return value of strlen being unsigned. */
12481 {
12489 {
12494 }
12495 }
12497 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
12498 of X. Similarly fold (X >> C) == 0 into X >= 0. */
12502 {
12509 {
12511 {
12514 }
12517 }
12518 }
12520 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
12526 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
12531 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
12538 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
12546 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
12547 (X & C) == 0 when C is a single bit. */
12552 {
12558 }
12560 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
12561 constant C is a power of two, i.e. a single bit. */
12568 {
12572 }
12574 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
12575 when is C is a power of two, i.e. a single bit. */
12582 {
12588 }
12592 {
12595 }
12597 /* Fold -X op -Y as X op Y, where op is eq/ne. */
12604 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
12607 {
12620 arg01),
12629 arg01),
12638 arg00),
12647 arg00),
12649 }
12653 {
12660 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
12661 operand_equal_p guarantees no side-effects so we don't need
12662 to use omit_one_operand on Z. */
12672 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
12680 arg10);
12681 }
12683 /* Attempt to simplify equality/inequality comparisons of complex
12684 values. Only lower the comparison if the result is known or
12685 can be simplified to a single scalar comparison. */
12690 {
12695 {
12698 }
12699 else
12700 {
12703 }
12706 {
12709 }
12710 else
12711 {
12714 }
12718 {
12720 {
12725 }
12726 else
12727 {
12732 }
12733 }
12737 {
12739 {
12744 }
12745 else
12746 {
12751 }
12752 }
12753 }
12765 /* Transform comparisons of the form X +- C CMP X. */
12772 {
12779 else
12782 /* (X - c) > X becomes false. */
12786 {
12790 "occur when assuming that (X - c) > X "
12792 WARN_STRICT_OVERFLOW_ALL);
12794 }
12796 /* Likewise (X + c) < X becomes false. */
12800 {
12804 "occur when assuming that "
12806 WARN_STRICT_OVERFLOW_ALL);
12808 }
12810 /* Convert (X - c) <= X to true. */
12815 {
12819 "occur when assuming that "
12821 WARN_STRICT_OVERFLOW_ALL);
12823 }
12825 /* Convert (X + c) >= X to true. */
12830 {
12834 "occur when assuming that "
12836 WARN_STRICT_OVERFLOW_ALL);
12838 }
12841 {
12842 /* Convert X + c > X and X - c < X to true for integers. */
12846 {
12849 "not occur when assuming that "
12851 WARN_STRICT_OVERFLOW_ALL);
12853 }
12858 {
12861 "not occur when assuming that "
12863 WARN_STRICT_OVERFLOW_ALL);
12865 }
12867 /* Convert X + c <= X and X - c >= X to false for integers. */
12871 {
12874 "not occur when assuming that "
12876 WARN_STRICT_OVERFLOW_ALL);
12878 }
12883 {
12886 "not occur when assuming that "
12888 WARN_STRICT_OVERFLOW_ALL);
12890 }
12891 }
12892 }
12894 /* Comparisons with the highest or lowest possible integer of
12895 the specified precision will have known values. */
12896 {
12903 {
12904 HOST_WIDE_INT signed_max_hi;
12909 {
12916 {
12920 }
12921 else
12922 {
12926 }
12927 }
12928 else
12929 {
12938 {
12941 }
12942 else
12943 {
12946 }
12947 }
12952 {
12965 /* The GE_EXPR and LT_EXPR cases above are not normally
12966 reached because of previous transformations. */
12970 }
12972 == max_hi
12975 {
12982 arg1);
12988 arg0),
12989 arg1);
12992 }
12994 == min_hi
12997 {
13012 }
13014 == min_hi
13017 {
13023 arg1);
13028 arg0),
13029 arg1);
13032 }
13037 /* We will flip the signedness of the comparison operator
13038 associated with the mode of arg1, so the sign bit is
13039 specified by this mode. Check that arg1 is the signed
13040 max associated with this sign bit. */
13042 /* signed_type does not work on pointer types. */
13044 {
13045 /* The following case also applies to X < signed_max+1
13046 and X >= signed_max+1 because previous transformations. */
13048 {
13049 tree st;
13055 }
13056 }
13057 }
13058 }
13060 /* If we are comparing an ABS_EXPR with a constant, we can
13061 convert all the cases into explicit comparisons, but they may
13062 well not be faster than doing the ABS and one comparison.
13063 But ABS (X) <= C is a range comparison, which becomes a subtraction
13064 and a comparison, and is probably faster. */
13078 /* Convert ABS_EXPR<x> >= 0 to true. */
13085 {
13088 "when simplifying comparison of "
13090 WARN_STRICT_OVERFLOW_CONDITIONAL);
13092 }
13094 /* Convert ABS_EXPR<x> < 0 to false. */
13099 {
13102 "when simplifying comparison of "
13104 WARN_STRICT_OVERFLOW_CONDITIONAL);
13106 }
13108 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
13109 and similarly for >= into !=. */
13124 {
13130 }
13143 {
13147 }
13149 /* If the first operand is NaN, the result is constant. */
13153 {
13155 ? integer_zero_node
13158 }
13160 /* If the second operand is NaN, the result is constant. */
13164 {
13166 ? integer_zero_node
13169 }
13171 /* Simplify unordered comparison of something with itself. */
13177 && !flag_trapping_math
13181 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
13182 {
13194 }
13199 /* When pedantic, a compound expression can be neither an lvalue
13200 nor an integer constant expression. */
13203 /* Don't let (0, 0) be null pointer constant. */
13217 /* An ASSERT_EXPR should never be passed to fold_binary. */
13223 }
13225 /* Fold a binary expression of code CODE and type TYPE with operands
13226 OP0 and OP1. Return the folded expression if folding is
13227 successful. Otherwise, return NULL_TREE.
13228 This is a wrapper around fold_binary_1 function (which does the
13229 actual folding). Set the EXPR_FOLDED flag of the folded expression
13230 if folding is successful. */
13231 tree
13234 {
13239 }
13241 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
13242 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
13243 of GOTO_EXPR. */
13245 static tree
13247 {
13249 {
13256 /* ... fall through ... */
13260 }
13261 }
13263 /* Return whether the sub-tree ST contains a label which is accessible from
13264 outside the sub-tree. */
13266 static bool
13268 {
13269 return
13271 }
13273 /* Fold a ternary expression of code CODE and type TYPE with operands
13274 OP0, OP1, and OP2. Return the folded expression if folding is
13275 successful. Otherwise, return NULL_TREE. */
13277 static tree
13280 {
13281 tree tem;
13288 /* Strip any conversions that don't change the mode. This is safe
13289 for every expression, except for a comparison expression because
13290 its signedness is derived from its operands. So, in the latter
13291 case, only strip conversions that don't change the signedness.
13293 Note that this is done as an internal manipulation within the
13294 constant folder, in order to find the simplest representation of
13295 the arguments so that their form can be studied. In any cases,
13296 the appropriate type conversions should be put back in the tree
13297 that will get out of the constant folder. */
13299 {
13302 }
13305 {
13308 }
13311 {
13314 }
13317 {
13321 {
13327 }
13331 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
13332 so all simple results must be passed through pedantic_non_lvalue. */
13334 {
13337 /* Only optimize constant conditions when the selected branch
13338 has the same type as the COND_EXPR. This avoids optimizing
13339 away "c ? x : throw", where the throw has a void type.
13340 Avoid throwing away that operand which contains label. */
13347 }
13351 /* If we have A op B ? A : C, we may be able to convert this to a
13352 simpler expression, depending on the operation and the values
13353 of B and C. Signed zeros prevent all of these transformations,
13354 for reasons given above each one.
13356 Also try swapping the arguments and inverting the conditional. */
13361 {
13365 }
13369 op2,
13372 {
13375 {
13379 }
13380 }
13382 /* If the second operand is simpler than the third, swap them
13383 since that produces better jump optimization results. */
13386 {
13387 /* See if this can be inverted. If it can't, possibly because
13388 it was a floating-point inequality comparison, don't do
13389 anything. */
13393 }
13395 /* Convert A ? 1 : 0 to simply A. */
13398 /* If we try to convert OP0 to our type, the
13399 call to fold will try to move the conversion inside
13400 a COND, which will recurse. In that case, the COND_EXPR
13401 is probably the best choice, so leave it alone. */
13405 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
13406 over COND_EXPR in cases such as floating point comparisons. */
13413 arg0)));
13415 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
13420 {
13421 /* sign_bit_p only checks ARG1 bits within A's precision.
13422 If <sign bit of A> has wider type than A, bits outside
13423 of A's precision in <sign bit of A> need to be checked.
13424 If they are all 0, this optimization needs to be done
13425 in unsigned A's type, if they are all 1 in signed A's type,
13426 otherwise this can't be done. */
13431 {
13433 HOST_WIDE_INT mask_hi;
13435 tree tem_type;
13443 {
13447 }
13448 else
13449 {
13453 }
13455 {
13459 }
13460 else
13466 {
13469 }
13472 {
13475 }
13476 else
13478 }
13481 return
13487 arg1)));
13488 }
13490 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
13491 already handled above. */
13496 {
13505 }
13507 /* A & N ? N : 0 is simply A & N if N is a power of two. This
13508 is probably obsolete because the first operand should be a
13509 truth value (that's why we have the two cases above), but let's
13510 leave it in until we can confirm this for all front-ends. */
13522 /* Convert A ? B : 0 into A && B if A and B are truth values. */
13528 arg1);
13530 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
13534 {
13535 /* Only perform transformation if ARG0 is easily inverted. */
13540 arg1);
13541 }
13543 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
13547 {
13548 /* Only perform transformation if ARG0 is easily inverted. */
13553 op2);
13554 }
13556 /* Convert A ? 1 : B into A || B if A and B are truth values. */
13562 op2);
13567 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
13568 of fold_ternary on them. */
13575 {
13584 {
13589 else
13590 {
13592 tree value;
13596 }
13601 else
13603 }
13604 }
13606 /* A bit-field-ref that referenced the full argument can be stripped. */
13615 /* For integers we can decompose the FMA if possible. */
13628 }
13630 /* Fold a ternary expression of code CODE and type TYPE with operands
13631 OP0, OP1, and OP2. Return the folded expression if folding is
13632 successful. Otherwise, return NULL_TREE.
13633 This is a wrapper around fold_ternary_1 function (which does the
13634 actual folding). Set the EXPR_FOLDED flag of the folded expression
13635 if folding is successful. */
13637 tree
13640 {
13645 }
13647 /* Perform constant folding and related simplification of EXPR.
13648 The related simplifications include x*1 => x, x*0 => 0, etc.,
13649 and application of the associative law.
13650 NOP_EXPR conversions may be removed freely (as long as we
13651 are careful not to change the type of the overall expression).
13652 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
13653 but we can constant-fold them if they have constant operands. */
13655 #ifdef ENABLE_FOLD_CHECKING
13656 # define fold(x) fold_1 (x)
13658 static
13659 #endif
13660 tree
13662 {
13666 tree tem;
13669 /* Return right away if a constant. */
13673 /* CALL_EXPR-like objects with variable numbers of operands are
13674 treated specially. */
13676 {
13678 {
13681 }
13683 }
13686 {
13691 {
13709 }
13710 }
13713 {
13715 {
13722 {
13727 /* Find a matching index by means of a binary search. */
13729 {
13745 else
13747 }
13748 }
13751 }
13759 }
13761 #ifdef ENABLE_FOLD_CHECKING
13762 #undef fold
13768 /* When --enable-checking=fold, compute a digest of expr before
13769 and after actual fold call to see if fold did not accidentally
13770 change original expr. */
13772 tree
13774 {
13775 tree ret;
13778 htab_t ht;
13797 }
13799 void
13801 {
13804 htab_t ht;
13814 }
13816 static void
13818 {
13820 }
13822 static void
13824 {
13830 recursive_label:
13844 {
13845 /* Allow DECL_ASSEMBLER_NAME to be modified. */
13849 }
13856 {
13857 /* Allow these fields to be modified. */
13858 tree tmp;
13866 {
13869 }
13870 }
13879 {
13882 {
13896 }
13900 {
13913 }
13930 {
13936 }
13941 {
13945 }
13956 {
13959 }
13969 }
13970 }
13972 /* Helper function for outputting the checksum of a tree T. When
13973 debugging with gdb, you can "define mynext" to be "next" followed
13974 by "call debug_fold_checksum (op0)", then just trace down till the
13975 outputs differ. */
13977 DEBUG_FUNCTION void
13979 {
13994 }
13996 #endif
13998 /* Fold a unary tree expression with code CODE of type TYPE with an
13999 operand OP0. LOC is the location of the resulting expression.
14000 Return a folded expression if successful. Otherwise, return a tree
14001 expression with code CODE of type TYPE with an operand OP0. */
14003 tree
14006 {
14007 tree tem;
14008 #ifdef ENABLE_FOLD_CHECKING
14011 htab_t ht;
14018 #endif
14024 #ifdef ENABLE_FOLD_CHECKING
14032 #endif
14034 }
14036 /* Fold a binary tree expression with code CODE of type TYPE with
14037 operands OP0 and OP1. LOC is the location of the resulting
14038 expression. Return a folded expression if successful. Otherwise,
14039 return a tree expression with code CODE of type TYPE with operands
14040 OP0 and OP1. */
14042 tree
14045 MEM_STAT_DECL)
14046 {
14047 tree tem;
14048 #ifdef ENABLE_FOLD_CHECKING
14054 htab_t ht;
14066 #endif
14072 #ifdef ENABLE_FOLD_CHECKING
14088 #endif
14090 }
14092 /* Fold a ternary tree expression with code CODE of type TYPE with
14093 operands OP0, OP1, and OP2. Return a folded expression if
14094 successful. Otherwise, return a tree expression with code CODE of
14095 type TYPE with operands OP0, OP1, and OP2. */
14097 tree
14100 {
14101 tree tem;
14102 #ifdef ENABLE_FOLD_CHECKING
14110 htab_t ht;
14127 #endif
14134 #ifdef ENABLE_FOLD_CHECKING
14158 #endif
14160 }
14162 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
14163 arguments in ARGARRAY, and a null static chain.
14164 Return a folded expression if successful. Otherwise, return a CALL_EXPR
14165 of type TYPE from the given operands as constructed by build_call_array. */
14167 tree
14170 {
14171 tree tem;
14172 #ifdef ENABLE_FOLD_CHECKING
14178 htab_t ht;
14192 #endif
14196 #ifdef ENABLE_FOLD_CHECKING
14213 #endif
14215 }
14217 /* Perform constant folding and related simplification of initializer
14218 expression EXPR. These behave identically to "fold_buildN" but ignore
14219 potential run-time traps and exceptions that fold must preserve. */
14221 #define START_FOLD_INIT \
14222 int saved_signaling_nans = flag_signaling_nans;\
14223 int saved_trapping_math = flag_trapping_math;\
14224 int saved_rounding_math = flag_rounding_math;\
14225 int saved_trapv = flag_trapv;\
14226 int saved_folding_initializer = folding_initializer;\
14227 flag_signaling_nans = 0;\
14228 flag_trapping_math = 0;\
14229 flag_rounding_math = 0;\
14230 flag_trapv = 0;\
14231 folding_initializer = 1;
14233 #define END_FOLD_INIT \
14234 flag_signaling_nans = saved_signaling_nans;\
14235 flag_trapping_math = saved_trapping_math;\
14236 flag_rounding_math = saved_rounding_math;\
14237 flag_trapv = saved_trapv;\
14238 folding_initializer = saved_folding_initializer;
14240 tree
14243 {
14244 tree result;
14245 START_FOLD_INIT;
14249 END_FOLD_INIT;
14251 }
14253 tree
14256 {
14257 tree result;
14258 START_FOLD_INIT;
14262 END_FOLD_INIT;
14264 }
14266 tree
14269 {
14270 tree result;
14271 START_FOLD_INIT;
14275 END_FOLD_INIT;
14277 }
14279 tree
14282 {
14283 tree result;
14284 START_FOLD_INIT;
14288 END_FOLD_INIT;
14290 }
14292 #undef START_FOLD_INIT
14293 #undef END_FOLD_INIT
14295 /* Determine if first argument is a multiple of second argument. Return 0 if
14296 it is not, or we cannot easily determined it to be.
14298 An example of the sort of thing we care about (at this point; this routine
14299 could surely be made more general, and expanded to do what the *_DIV_EXPR's
14300 fold cases do now) is discovering that
14302 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14304 is a multiple of
14306 SAVE_EXPR (J * 8)
14308 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
14310 This code also handles discovering that
14312 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
14314 is a multiple of 8 so we don't have to worry about dealing with a
14315 possible remainder.
14317 Note that we *look* inside a SAVE_EXPR only to determine how it was
14318 calculated; it is not safe for fold to do much of anything else with the
14319 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
14320 at run time. For example, the latter example above *cannot* be implemented
14321 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
14322 evaluation time of the original SAVE_EXPR is not necessarily the same at
14323 the time the new expression is evaluated. The only optimization of this
14324 sort that would be valid is changing
14326 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
14328 divided by 8 to
14330 SAVE_EXPR (I) * SAVE_EXPR (J)
14332 (where the same SAVE_EXPR (J) is used in the original and the
14333 transformed version). */
14335 int
14337 {
14345 {
14347 /* Bitwise and provides a power of two multiple. If the mask is
14348 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
14351 /* FALLTHRU */
14364 {
14368 /* const_binop may not detect overflow correctly,
14369 so check for it explicitly here. */
14375 size_one_node,
14376 op1)))
14379 }
14383 /* Can't handle conversions from non-integral or wider integral type. */
14389 /* .. fall through ... */
14410 }
14411 }
14413 /* Return true if CODE or TYPE is known to be non-negative. */
14415 static bool
14417 {
14420 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
14421 have a signed:1 type (where the value is -1 and 0). */
14424 }
14426 /* Return true if (CODE OP0) is known to be non-negative. If the return
14427 value is based on the assumption that signed overflow is undefined,
14428 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14429 *STRICT_OVERFLOW_P. */
14431 bool
14434 {
14439 {
14441 /* We can't return 1 if flag_wrapv is set because
14442 ABS_EXPR<INT_MIN> = INT_MIN. */
14446 {
14449 }
14456 strict_overflow_p);
14459 {
14464 {
14467 strict_overflow_p);
14469 {
14473 strict_overflow_p);
14474 }
14475 }
14477 {
14480 strict_overflow_p);
14484 }
14485 }
14490 }
14492 /* We don't know sign of `t', so be conservative and return false. */
14494 }
14496 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
14497 value is based on the assumption that signed overflow is undefined,
14498 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14499 *STRICT_OVERFLOW_P. */
14501 bool
14504 {
14509 {
14514 strict_overflow_p)
14516 strict_overflow_p));
14518 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
14519 both unsigned and at least 2 bits shorter than the result. */
14523 {
14528 {
14532 }
14533 }
14538 {
14539 /* x * x for floating point x is always non-negative. */
14543 strict_overflow_p)
14545 strict_overflow_p));
14546 }
14548 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
14549 both unsigned and their total bits is shorter than the result. */
14553 {
14572 {
14582 }
14583 }
14589 strict_overflow_p)
14591 strict_overflow_p));
14602 strict_overflow_p)
14604 strict_overflow_p));
14611 strict_overflow_p);
14614 }
14616 /* We don't know sign of `t', so be conservative and return false. */
14618 }
14620 /* Return true if T is known to be non-negative. If the return
14621 value is based on the assumption that signed overflow is undefined,
14622 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14623 *STRICT_OVERFLOW_P. */
14625 bool
14627 {
14632 {
14644 strict_overflow_p)
14646 strict_overflow_p));
14650 }
14651 /* We don't know sign of `t', so be conservative and return false. */
14653 }
14655 /* Return true if T is known to be non-negative. If the return
14656 value is based on the assumption that signed overflow is undefined,
14657 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14658 *STRICT_OVERFLOW_P. */
14660 bool
14663 {
14666 {
14684 /* Always true. */
14688 /* sqrt(-0.0) is -0.0. */
14692 strict_overflow_p);
14725 /* True if the 1st argument is nonnegative. */
14727 strict_overflow_p);
14730 /* True if the 1st OR 2nd arguments are nonnegative. */
14732 strict_overflow_p)
14734 strict_overflow_p)));
14737 /* True if the 1st AND 2nd arguments are nonnegative. */
14739 strict_overflow_p)
14741 strict_overflow_p)));
14744 /* True if the 2nd argument is nonnegative. */
14746 strict_overflow_p);
14749 /* True if the 1st argument is nonnegative or the second
14750 argument is an even integer. */
14755 strict_overflow_p);
14758 /* True if the 1st argument is nonnegative or the second
14759 argument is an even integer valued real. */
14761 {
14762 REAL_VALUE_TYPE c;
14763 HOST_WIDE_INT n;
14768 {
14769 REAL_VALUE_TYPE cint;
14774 }
14775 }
14777 strict_overflow_p);
14781 }
14783 type);
14784 }
14786 /* Return true if T is known to be non-negative. If the return
14787 value is based on the assumption that signed overflow is undefined,
14788 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14789 *STRICT_OVERFLOW_P. */
14791 bool
14793 {
14799 {
14801 {
14805 /* If the initializer is non-void, then it's a normal expression
14806 that will be assigned to the slot. */
14810 /* Otherwise, the initializer sets the slot in some way. One common
14811 way is an assignment statement at the end of the initializer. */
14813 {
14821 else
14823 }
14827 strict_overflow_p);
14830 }
14833 {
14839 arg0,
14840 arg1,
14841 strict_overflow_p);
14842 }
14846 strict_overflow_p);
14849 strict_overflow_p);
14852 strict_overflow_p);
14857 }
14859 /* We don't know sign of `t', so be conservative and return false. */
14861 }
14863 /* Return true if T is known to be non-negative. If the return
14864 value is based on the assumption that signed overflow is undefined,
14865 set *STRICT_OVERFLOW_P to true; otherwise, don't change
14866 *STRICT_OVERFLOW_P. */
14868 bool
14870 {
14877 {
14884 strict_overflow_p);
14890 strict_overflow_p);
14899 }
14902 {
14910 strict_overflow_p);
14915 strict_overflow_p);
14928 }
14929 }
14931 /* Return true if `t' is known to be non-negative. Handle warnings
14932 about undefined signed overflow. */
14934 bool
14936 {
14943 "determining that expression is always "
14945 WARN_STRICT_OVERFLOW_MISC);
14947 }
14950 /* Return true when (CODE OP0) is an address and is known to be nonzero.
14951 For floating point we further ensure that T is not denormal.
14952 Similar logic is present in nonzero_address in rtlanal.h.
14954 If the return value is based on the assumption that signed overflow
14955 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14956 change *STRICT_OVERFLOW_P. */
14958 bool
14961 {
14963 {
14966 strict_overflow_p);
14969 {
14975 strict_overflow_p));
14976 }
14981 strict_overflow_p);
14985 }
14988 }
14990 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
14991 For floating point we further ensure that T is not denormal.
14992 Similar logic is present in nonzero_address in rtlanal.h.
14994 If the return value is based on the assumption that signed overflow
14995 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
14996 change *STRICT_OVERFLOW_P. */
14998 bool
15000 tree type,
15001 tree op0,
15003 {
15006 {
15010 {
15011 /* With the presence of negative values it is hard
15012 to say something. */
15019 /* One of operands must be positive and the other non-negative. */
15020 /* We don't set *STRICT_OVERFLOW_P here: even if this value
15021 overflows, on a twos-complement machine the sum of two
15022 nonnegative numbers can never be zero. */
15024 strict_overflow_p)
15026 strict_overflow_p));
15027 }
15032 {
15034 strict_overflow_p)
15036 strict_overflow_p))
15037 {
15040 }
15041 }
15050 {
15053 }
15060 {
15064 /* When both operands are nonzero, then MAX must be too. */
15066 strict_overflow_p))
15069 /* MAX where operand 0 is positive is positive. */
15071 strict_overflow_p);
15072 }
15073 /* MAX where operand 1 is positive is positive. */
15078 {
15082 }
15087 strict_overflow_p)
15089 strict_overflow_p));
15093 }
15096 }
15098 /* Return true when T is an address and is known to be nonzero.
15099 For floating point we further ensure that T is not denormal.
15100 Similar logic is present in nonzero_address in rtlanal.h.
15102 If the return value is based on the assumption that signed overflow
15103 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15104 change *STRICT_OVERFLOW_P. */
15106 bool
15108 {
15111 {
15116 {
15124 /* Weak declarations may link to NULL. Other things may also be NULL
15125 so protect with -fdelete-null-pointer-checks; but not variables
15126 allocated on the stack. */
15128 && (flag_delete_null_pointer_checks
15134 /* Constants are never weak. */
15139 }
15147 {
15151 }
15156 }
15158 }
15160 /* Return true when T is an address and is known to be nonzero.
15161 For floating point we further ensure that T is not denormal.
15162 Similar logic is present in nonzero_address in rtlanal.h.
15164 If the return value is based on the assumption that signed overflow
15165 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
15166 change *STRICT_OVERFLOW_P. */
15168 bool
15170 {
15174 /* Doing something useful for floating point would need more work. */
15180 {
15183 strict_overflow_p);
15189 strict_overflow_p);
15197 }
15200 {
15203 strict_overflow_p);
15211 strict_overflow_p);
15226 strict_overflow_p);
15230 strict_overflow_p);
15237 }
15239 }
15241 /* Return true when T is an address and is known to be nonzero.
15242 Handle warnings about undefined signed overflow. */
15244 bool
15246 {
15253 "determining that expression is always "
15255 WARN_STRICT_OVERFLOW_MISC);
15257 }
15259 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
15260 attempt to fold the expression to a constant without modifying TYPE,
15261 OP0 or OP1.
15263 If the expression could be simplified to a constant, then return
15264 the constant. If the expression would not be simplified to a
15265 constant, then return NULL_TREE. */
15267 tree
15269 {
15272 }
15274 /* Given the components of a unary expression CODE, TYPE and OP0,
15275 attempt to fold the expression to a constant without modifying
15276 TYPE or OP0.
15278 If the expression could be simplified to a constant, then return
15279 the constant. If the expression would not be simplified to a
15280 constant, then return NULL_TREE. */
15282 tree
15284 {
15287 }
15289 /* If EXP represents referencing an element in a constant string
15290 (either via pointer arithmetic or array indexing), return the
15291 tree representing the value accessed, otherwise return NULL. */
15293 tree
15295 {
15299 {
15301 tree index;
15302 tree string;
15307 else
15308 {
15312 /* Optimize the special-case of a zero lower bound.
15314 We convert the low_bound to sizetype to avoid some problems
15315 with constant folding. (E.g. suppose the lower bound is 1,
15316 and its mode is QI. Without the conversion,l (ARRAY
15317 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
15318 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
15324 }
15337 }
15339 }
15341 /* Return the tree for neg (ARG0) when ARG0 is known to be either
15342 an integer constant, real, or fixed-point constant.
15344 TYPE is the type of the result. */
15346 static tree
15348 {
15352 {
15354 {
15362 }
15369 {
15370 FIXED_VALUE_TYPE f;
15375 /* Propagate overflow flags. */
15379 }
15383 }
15386 }
15388 /* Return the tree for abs (ARG0) when ARG0 is known to be either
15389 an integer constant or real constant.
15391 TYPE is the type of the result. */
15393 tree
15395 {
15399 {
15401 {
15404 /* If the value is unsigned or non-negative, then the absolute value
15405 is the same as the ordinary value. */
15410 /* If the value is negative, then the absolute value is
15411 its negation. */
15412 else
15413 {
15419 }
15420 }
15426 else
15432 }
15435 }
15437 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
15438 constant. TYPE is the type of the result. */
15440 static tree
15442 {
15443 double_int val;
15449 }
15451 /* Given CODE, a relational operator, the target type, TYPE and two
15452 constant operands OP0 and OP1, return the result of the
15453 relational operation. If the result is not a compile time
15454 constant, then return NULL_TREE. */
15456 static tree
15458 {
15461 /* From here on, the only cases we handle are when the result is
15462 known to be a constant. */
15465 {
15469 /* Handle the cases where either operand is a NaN. */
15471 {
15473 {
15501 }
15504 }
15507 }
15510 {
15514 }
15516 /* Handle equality/inequality of complex constants. */
15518 {
15529 else
15531 }
15533 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
15535 To compute GT, swap the arguments and do LT.
15536 To compute GE, do LT and invert the result.
15537 To compute LE, swap the arguments, do LT and invert the result.
15538 To compute NE, do EQ and invert the result.
15540 Therefore, the code below must handle only EQ and LT. */
15543 {
15548 }
15550 /* Note that it is safe to invert for real values here because we
15551 have already handled the one case that it matters. */
15555 {
15558 }
15560 /* Compute a result for LT or EQ if args permit;
15561 Otherwise return T. */
15563 {
15568 else
15570 }
15571 else
15577 }
15579 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
15580 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
15581 itself. */
15583 tree
15585 {
15586 /* If the expression does not have side effects then we don't have to wrap
15587 it with a cleanup point expression. */
15591 /* If the expression is a return, check to see if the expression inside the
15592 return has no side effects or the right hand side of the modify expression
15593 inside the return. If either don't have side effects set we don't need to
15594 wrap the expression in a cleanup point expression. Note we don't check the
15595 left hand side of the modify because it should always be a return decl. */
15597 {
15604 }
15607 }
15609 /* Given a pointer value OP0 and a type TYPE, return a simplified version
15610 of an indirection through OP0, or NULL_TREE if no simplification is
15611 possible. */
15613 tree
15615 {
15617 tree subtype;
15625 {
15628 /* *&CONST_DECL -> to the value of the const decl. */
15631 /* *&p => p; make sure to handle *&"str"[cst] here. */
15633 {
15637 else
15639 }
15640 /* *(foo *)&fooarray => fooarray[0] */
15643 && (!in_gimple_form
15645 {
15655 }
15656 /* *(foo *)&complexfoo => __real__ complexfoo */
15660 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
15663 {
15667 }
15668 }
15672 {
15678 {
15679 tree op00type;
15683 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
15686 {
15698 }
15699 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
15702 {
15706 }
15707 /* ((foo *)&fooarray)[1] => fooarray[1] */
15710 {
15720 }
15721 }
15722 }
15724 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
15727 && (!in_gimple_form
15729 {
15730 tree type_domain;
15740 NULL_TREE);
15741 }
15744 }
15746 /* Builds an expression for an indirection through T, simplifying some
15747 cases. */
15749 tree
15751 {
15759 }
15761 /* Given an INDIRECT_REF T, return either T or a simplified version. */
15763 tree
15765 {
15770 else
15772 }
15774 /* Strip non-trapping, non-side-effecting tree nodes from an expression
15775 whose result is ignored. The type of the returned tree need not be
15776 the same as the original expression. */
15778 tree
15780 {
15786 {
15797 else
15803 {
15819 }
15824 }
15825 }
15827 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
15828 This can only be applied to objects of a sizetype. */
15830 tree
15832 {
15839 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15840 have to do anything. Only do this when we are not given a const,
15841 because in that case, this check is more expensive than just
15842 doing it. */
15844 {
15849 }
15851 /* If divisor is a power of two, simplify this to bit manipulation. */
15853 {
15855 {
15866 {
15870 }
15874 }
15875 else
15876 {
15877 tree t;
15883 }
15884 }
15885 else
15886 {
15891 }
15894 }
15896 /* Likewise, but round down. */
15898 tree
15900 {
15907 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
15908 have to do anything. Only do this when we are not given a const,
15909 because in that case, this check is more expensive than just
15910 doing it. */
15912 {
15917 }
15919 /* If divisor is a power of two, simplify this to bit manipulation. */
15921 {
15922 tree t;
15926 }
15927 else
15928 {
15933 }
15936 }
15938 /* Returns the pointer to the base of the object addressed by EXP and
15939 extracts the information about the offset of the access, storing it
15940 to PBITPOS and POFFSET. */
15942 static tree
15945 {
15946 tree core;
15949 HOST_WIDE_INT bitsize;
15953 {
15958 }
15959 else
15960 {
15964 }
15967 }
15969 /* Returns true if addresses of E1 and E2 differ by a constant, false
15970 otherwise. If they do, E1 - E2 is stored in *DIFF. */
15972 bool
15974 {
15988 {
15998 }
16000 {
16001 /* If only one of the offsets is non-constant, the difference cannot
16002 be a constant. */
16004 }
16005 else
16010 }
16012 /* Simplify the floating point expression EXP when the sign of the
16013 result is not significant. Return NULL_TREE if no simplification
16014 is possible. */
16016 tree
16018 {
16023 {
16059 {
16062 {
16064 /* Strip copysign function call, return the 1st argument. */
16070 /* Strip sign ops from the argument of "odd" math functions. */
16072 {
16076 }
16078 }
16079 }
16084 }
16086 }