| blob | f97b8bf6978d3cf69c21991d0b95619fa4108a82 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
81 #ifndef LOAD_EXTEND_OP
82 #define LOAD_EXTEND_OP(M) UNKNOWN
83 #endif
85 /* Nonzero if we are folding constants inside an initializer; zero
86 otherwise. */
89 /* The following constants represent a bit based encoding of GCC's
90 comparison operators. This encoding simplifies transformations
91 on relational comparison operators, such as AND and OR. */
109 };
147 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
148 Otherwise, return LOC. */
150 static location_t
152 {
155 }
157 /* Similar to protected_set_expr_location, but never modify x in place,
158 if location can and needs to be set, unshare it. */
162 {
168 {
171 }
173 }
174 \f
175 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
176 division and returns the quotient. Otherwise returns
177 NULL_TREE. */
179 tree
181 {
182 widest_int quo;
189 }
190 \f
191 /* This is nonzero if we should defer warnings about undefined
192 overflow. This facility exists because these warnings are a
193 special case. The code to estimate loop iterations does not want
194 to issue any warnings, since it works with expressions which do not
195 occur in user code. Various bits of cleanup code call fold(), but
196 only use the result if it has certain characteristics (e.g., is a
197 constant); that code only wants to issue a warning if the result is
198 used. */
202 /* If a warning about undefined overflow is deferred, this is the
203 warning. Note that this may cause us to turn two warnings into
204 one, but that is fine since it is sufficient to only give one
205 warning per expression. */
209 /* If a warning about undefined overflow is deferred, this is the
210 level at which the warning should be emitted. */
214 /* Start deferring overflow warnings. We could use a stack here to
215 permit nested calls, but at present it is not necessary. */
217 void
219 {
221 }
223 /* Stop deferring overflow warnings. If there is a pending warning,
224 and ISSUE is true, then issue the warning if appropriate. STMT is
225 the statement with which the warning should be associated (used for
226 location information); STMT may be NULL. CODE is the level of the
227 warning--a warn_strict_overflow_code value. This function will use
228 the smaller of CODE and the deferred code when deciding whether to
229 issue the warning. CODE may be zero to mean to always use the
230 deferred code. */
232 void
234 {
236 location_t locus;
241 {
247 }
258 /* Use the smallest code level when deciding to issue the
259 warning. */
268 else
271 }
273 /* Stop deferring overflow warnings, ignoring any deferred
274 warnings. */
276 void
278 {
280 }
282 /* Whether we are deferring overflow warnings. */
284 bool
286 {
288 }
290 /* This is called when we fold something based on the fact that signed
291 overflow is undefined. */
293 void
295 {
297 {
300 {
303 }
304 }
307 }
308 \f
309 /* Return true if the built-in mathematical function specified by CODE
310 is odd, i.e. -f(x) == f(-x). */
312 bool
314 {
316 {
317 CASE_CFN_ASIN:
318 CASE_CFN_ASINH:
319 CASE_CFN_ATAN:
320 CASE_CFN_ATANH:
321 CASE_CFN_CASIN:
322 CASE_CFN_CASINH:
323 CASE_CFN_CATAN:
324 CASE_CFN_CATANH:
325 CASE_CFN_CBRT:
326 CASE_CFN_CPROJ:
327 CASE_CFN_CSIN:
328 CASE_CFN_CSINH:
329 CASE_CFN_CTAN:
330 CASE_CFN_CTANH:
331 CASE_CFN_ERF:
332 CASE_CFN_LLROUND:
333 CASE_CFN_LROUND:
334 CASE_CFN_ROUND:
335 CASE_CFN_SIN:
336 CASE_CFN_SINH:
337 CASE_CFN_TAN:
338 CASE_CFN_TANH:
339 CASE_CFN_TRUNC:
342 CASE_CFN_LLRINT:
343 CASE_CFN_LRINT:
344 CASE_CFN_NEARBYINT:
345 CASE_CFN_RINT:
350 }
352 }
354 /* Check whether we may negate an integer constant T without causing
355 overflow. */
357 bool
359 {
360 tree type;
369 }
371 /* Determine whether an expression T can be cheaply negated using
372 the function negate_expr without introducing undefined overflow. */
374 static bool
376 {
377 tree type;
386 {
391 /* Check that -CST will not overflow type. */
404 /* We want to canonicalize to positive real constants. Pretend
405 that only negative ones can be easily negated. */
413 {
424 }
439 /* -(A + B) -> (-B) - A. */
444 /* -(A + B) -> (-A) - B. */
448 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
459 /* INT_MIN/n * n doesn't overflow while negating one operand it does
460 if n is a power of two. */
469 /* Fall through. */
484 /* In general we can't negate B in A / B, because if A is INT_MIN and
485 B is 1, we may turn this into INT_MIN / -1 which is undefined
486 and actually traps on some architectures. */
495 /* Negate -((double)float) as (double)(-float). */
497 {
501 }
505 /* Negate -f(x) as f(-x). */
511 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
513 {
517 }
522 }
524 }
526 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
527 simplification is possible.
528 If negate_expr_p would return true for T, NULL_TREE will never be
529 returned. */
531 static tree
533 {
535 tree tem;
538 {
539 /* Convert - (~A) to A + 1. */
565 {
570 }
574 {
579 {
583 }
586 }
609 {
610 /* -(A + B) -> (-B) - A. */
614 {
618 }
620 /* -(A + B) -> (-A) - B. */
622 {
626 }
627 }
631 /* - (A - B) -> B - A */
643 /* Fall through. */
647 {
656 }
668 /* In general we can't negate B in A / B, because if A is INT_MIN and
669 B is 1, we may turn this into INT_MIN / -1 which is undefined
670 and actually traps on some architectures. */
682 /* Convert -((double)float) into (double)(-float). */
684 {
688 }
692 /* Negate -f(x) as f(-x). */
695 {
701 }
705 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
707 {
710 {
717 }
718 }
723 }
726 }
728 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
729 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
730 return NULL_TREE. */
732 static tree
734 {
736 location_t loc;
749 }
750 \f
751 /* Split a tree IN into a constant, literal and variable parts that could be
752 combined with CODE to make IN. "constant" means an expression with
753 TREE_CONSTANT but that isn't an actual constant. CODE must be a
754 commutative arithmetic operation. Store the constant part into *CONP,
755 the literal in *LITP and return the variable part. If a part isn't
756 present, set it to null. If the tree does not decompose in this way,
757 return the entire tree as the variable part and the other parts as null.
759 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
760 case, we negate an operand that was subtracted. Except if it is a
761 literal for which we use *MINUS_LITP instead.
763 If NEGATE_P is true, we are negating all of IN, again except a literal
764 for which we use *MINUS_LITP instead. If a variable part is of pointer
765 type, it is negated after converting to TYPE. This prevents us from
766 generating illegal MINUS pointer expression. LOC is the location of
767 the converted variable part.
769 If IN is itself a literal or constant, return it as appropriate.
771 Note that we do not guarantee that any of the three values will be the
772 same type as IN, but they will have the same signedness and mode. */
774 static tree
777 {
784 /* Strip any conversions that don't change the machine mode or signedness. */
793 /* We can associate addition and subtraction together (even
794 though the C standard doesn't say so) for integers because
795 the value is not affected. For reals, the value might be
796 affected, so we can't. */
799 {
805 /* First see if either of the operands is a literal, then a constant. */
818 /* If we haven't dealt with either operand, this is not a case we can
819 decompose. Otherwise, VAR is either of the ones remaining, if any. */
824 else
827 /* Now do any needed negations. */
833 {
834 /* Convert to TYPE before negating. */
837 }
838 }
841 {
842 /* -X - 1 is folded to ~X, undo that here. */
845 }
848 else
852 {
859 {
860 /* Convert to TYPE before negating. */
863 }
864 }
867 }
869 /* Re-associate trees split by the above function. T1 and T2 are
870 either expressions to associate or null. Return the new
871 expression, if any. LOC is the location of the new expression. If
872 we build an operation, do it in TYPE and with CODE. */
874 static tree
876 {
882 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
883 try to fold this since we will have infinite recursion. But do
884 deal with any NEGATE_EXPRs. */
887 {
889 {
902 }
904 {
907 }
911 }
915 }
916 \f
917 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
918 for use in int_const_binop, size_binop and size_diffop. */
920 static bool
922 {
929 {
938 }
943 }
946 /* Combine two integer constants ARG1 and ARG2 under operation CODE
947 to produce a new constant. Return NULL_TREE if we don't know how
948 to evaluate CODE at compile-time. */
950 static tree
953 {
954 wide_int res;
955 tree t;
963 {
979 {
983 else
985 }
988 /* It's unclear from the C standard whether shifts can overflow.
989 The following code ignores overflow; perhaps a C standard
990 interpretation ruling is needed. */
992 else
999 {
1003 else
1005 }
1009 else
1088 }
1096 }
1098 tree
1100 {
1102 }
1104 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1105 constant. We assume ARG1 and ARG2 have the same data type, or at least
1106 are the same kind of constant and the same machine mode. Return zero if
1107 combining the constants is not allowed in the current operating mode. */
1109 static tree
1111 {
1112 /* Sanity check for the recursive cases. */
1120 {
1126 }
1129 {
1130 machine_mode mode;
1131 REAL_VALUE_TYPE d1;
1132 REAL_VALUE_TYPE d2;
1133 REAL_VALUE_TYPE value;
1134 REAL_VALUE_TYPE result;
1138 /* The following codes are handled by real_arithmetic. */
1140 {
1151 }
1159 /* Don't perform operation if we honor signaling NaNs and
1160 either operand is a signaling NaN. */
1166 /* Don't perform operation if it would raise a division
1167 by zero exception. */
1173 /* If either operand is a NaN, just return it. Otherwise, set up
1174 for floating-point trap; we return an overflow. */
1176 {
1177 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1178 is off. */
1182 }
1184 {
1185 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1186 is off. */
1190 }
1195 /* Don't constant fold this floating point operation if
1196 the result has overflowed and flag_trapping_math. */
1204 /* Don't constant fold this floating point operation if the
1205 result may dependent upon the run-time rounding mode and
1206 flag_rounding_math is set, or if GCC's software emulation
1207 is unable to accurately represent the result. */
1217 }
1220 {
1221 FIXED_VALUE_TYPE f1;
1222 FIXED_VALUE_TYPE f2;
1223 FIXED_VALUE_TYPE result;
1228 /* The following codes are handled by fixed_arithmetic. */
1230 {
1242 {
1249 }
1254 }
1261 /* Propagate overflow flags. */
1265 }
1268 {
1277 {
1288 mpc_mul);
1302 mpc_div);
1303 /* Fallthru ... */
1309 {
1310 /* Keep this algorithm in sync with
1311 tree-complex.c:expand_complex_div_straight().
1313 Expand complex division to scalars, straightforward algorithm.
1314 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1315 t = br*br + bi*bi
1316 */
1317 tree magsquared
1321 tree t1
1325 tree t2
1332 }
1333 else
1334 {
1335 /* Keep this algorithm in sync with
1336 tree-complex.c:expand_complex_div_wide().
1338 Expand complex division to scalars, modified algorithm to minimize
1339 overflow with wide input ranges. */
1345 {
1346 /* In the TRUE branch, we compute
1347 ratio = br/bi;
1348 div = (br * ratio) + bi;
1349 tr = (ar * ratio) + ai;
1350 ti = (ai * ratio) - ar;
1351 tr = tr / div;
1352 ti = ti / div; */
1363 }
1364 else
1365 {
1366 /* In the FALSE branch, we compute
1367 ratio = d/c;
1368 divisor = (d * ratio) + c;
1369 tr = (b * ratio) + a;
1370 ti = b - (a * ratio);
1371 tr = tr / div;
1372 ti = ti / div; */
1384 }
1385 }
1390 }
1394 }
1398 {
1404 {
1410 /* It is possible that const_binop cannot handle the given
1411 code and return NULL_TREE */
1414 }
1417 }
1419 /* Shifts allow a scalar offset for a vector. */
1422 {
1428 {
1433 /* It is possible that const_binop cannot handle the given
1434 code and return NULL_TREE. */
1437 }
1440 }
1442 }
1444 /* Overload that adds a TYPE parameter to be able to dispatch
1445 to fold_relational_const. */
1447 tree
1449 {
1453 /* ??? Until we make the const_binop worker take the type of the
1454 result as argument put those cases that need it here. */
1456 {
1467 {
1483 {
1489 }
1492 }
1498 {
1523 {
1536 }
1539 }
1542 }
1547 /* Make sure type and arg0 have the same saturating flag. */
1552 }
1554 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1555 Return zero if computing the constants is not possible. */
1557 tree
1559 {
1560 /* Don't perform the operation, other than NEGATE and ABS, if
1561 flag_signaling_nans is on and the operand is a signaling NaN. */
1570 {
1571 CASE_CONVERT:
1578 /* If the source address is 0, and the source address space
1579 cannot have a valid object at 0, fold to dest type null. */
1590 {
1591 /* Can't call fold_negate_const directly here as that doesn't
1592 handle all cases and we might not be able to negate some
1593 constants. */
1598 }
1607 {
1611 }
1617 /* Perform BIT_NOT_EXPR on each element individually. */
1619 {
1621 tree elem;
1626 {
1632 }
1635 }
1657 {
1676 else
1680 {
1684 }
1687 }
1692 {
1706 {
1711 }
1714 {
1718 }
1721 }
1725 }
1728 }
1730 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1731 indicates which particular sizetype to create. */
1733 tree
1735 {
1737 }
1738 \f
1739 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1740 is a tree code. The type of the result is taken from the operands.
1741 Both must be equivalent integer types, ala int_binop_types_match_p.
1742 If the operands are constant, so is the result. */
1744 tree
1746 {
1755 /* Handle the special case of two integer constants faster. */
1757 {
1758 /* And some specific cases even faster than that. */
1760 {
1765 }
1767 {
1770 }
1772 {
1775 }
1777 /* Handle general case of two integer constants. For sizetype
1778 constant calculations we always want to know about overflow,
1779 even in the unsigned case. */
1781 }
1784 }
1786 /* Given two values, either both of sizetype or both of bitsizetype,
1787 compute the difference between the two values. Return the value
1788 in signed type corresponding to the type of the operands. */
1790 tree
1792 {
1794 tree ctype;
1799 /* If the type is already signed, just do the simple thing. */
1807 else
1810 /* If either operand is not a constant, do the conversions to the signed
1811 type and subtract. The hardware will do the right thing with any
1812 overflow in the subtraction. */
1818 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1819 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1820 overflow) and negate (which can't either). Special-case a result
1821 of zero while we're here. */
1827 else
1831 MINUS_EXPR,
1833 }
1834 \f
1835 /* A subroutine of fold_convert_const handling conversions of an
1836 INTEGER_CST to another integer type. */
1838 static tree
1840 {
1841 /* Given an integer constant, make new constant with new type,
1842 appropriately sign-extended or truncated. Use widest_int
1843 so that any extension is done according ARG1's type. */
1847 }
1849 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1850 to an integer type. */
1852 static tree
1854 {
1856 tree t;
1858 /* The following code implements the floating point to integer
1859 conversion rules required by the Java Language Specification,
1860 that IEEE NaNs are mapped to zero and values that overflow
1861 the target precision saturate, i.e. values greater than
1862 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1863 are mapped to INT_MIN. These semantics are allowed by the
1864 C and C++ standards that simply state that the behavior of
1865 FP-to-integer conversion is unspecified upon overflow. */
1867 wide_int val;
1868 REAL_VALUE_TYPE r;
1872 {
1879 }
1881 /* If R is NaN, return zero and show we have an overflow. */
1883 {
1886 }
1888 /* See if R is less than the lower bound or greater than the
1889 upper bound. */
1892 {
1896 {
1899 }
1900 }
1903 {
1906 {
1909 {
1912 }
1913 }
1914 }
1921 }
1923 /* A subroutine of fold_convert_const handling conversions of a
1924 FIXED_CST to an integer type. */
1926 static tree
1928 {
1929 tree t;
1933 /* Right shift FIXED_CST to temp by fbit. */
1937 {
1939 HOST_BITS_PER_DOUBLE_INT,
1942 /* Left shift temp to temp_trunc by fbit. */
1944 HOST_BITS_PER_DOUBLE_INT,
1946 }
1947 else
1948 {
1951 }
1953 /* If FIXED_CST is negative, we need to round the value toward 0.
1954 By checking if the fractional bits are not zero to add 1 to temp. */
1960 /* Given a fixed-point constant, make new constant with new type,
1961 appropriately sign-extended or truncated. */
1969 }
1971 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1972 to another floating point type. */
1974 static tree
1976 {
1977 REAL_VALUE_TYPE value;
1978 tree t;
1980 /* Don't perform the operation if flag_signaling_nans is on
1981 and the operand is a signaling NaN. */
1989 /* If converting an infinity or NAN to a representation that doesn't
1990 have one, set the overflow bit so that we can produce some kind of
1991 error message at the appropriate point if necessary. It's not the
1992 most user-friendly message, but it's better than nothing. */
1999 /* Regular overflow, conversion produced an infinity in a mode that
2000 can't represent them. */
2005 else
2008 }
2010 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2011 to a floating point type. */
2013 static tree
2015 {
2016 REAL_VALUE_TYPE value;
2017 tree t;
2024 }
2026 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2027 to another fixed-point type. */
2029 static tree
2031 {
2032 FIXED_VALUE_TYPE value;
2033 tree t;
2040 /* Propagate overflow flags. */
2044 }
2046 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2047 to a fixed-point type. */
2049 static tree
2051 {
2052 FIXED_VALUE_TYPE value;
2053 tree t;
2055 double_int di;
2062 else
2070 /* Propagate overflow flags. */
2074 }
2076 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2077 to a fixed-point type. */
2079 static tree
2081 {
2082 FIXED_VALUE_TYPE value;
2083 tree t;
2091 /* Propagate overflow flags. */
2095 }
2097 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2098 type TYPE. If no simplification can be done return NULL_TREE. */
2100 static tree
2102 {
2108 {
2115 }
2117 {
2124 }
2126 {
2133 }
2135 {
2138 {
2143 {
2149 }
2151 }
2152 }
2154 }
2156 /* Construct a vector of zero elements of vector type TYPE. */
2158 static tree
2160 {
2161 tree t;
2165 }
2167 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2169 bool
2171 {
2186 {
2202 }
2203 }
2205 /* Convert expression ARG to type TYPE. Used by the middle-end for
2206 simple conversions in preference to calling the front-end's convert. */
2208 tree
2210 {
2212 tree tem;
2223 {
2226 /* Handle conversions between pointers to different address spaces. */
2231 /* fall through */
2236 {
2240 }
2254 {
2258 }
2260 {
2264 }
2266 {
2270 }
2273 {
2291 }
2296 {
2300 }
2303 {
2317 }
2321 {
2330 integer_zero_node));
2332 {
2336 {
2342 }
2350 }
2354 }
2372 }
2373 fold_convert_exit:
2376 }
2377 \f
2378 /* Return false if expr can be assumed not to be an lvalue, true
2379 otherwise. */
2381 static bool
2383 {
2384 /* We only need to wrap lvalue tree codes. */
2386 {
2417 /* Assume the worst for front-end tree codes. */
2421 }
2424 }
2426 /* Return an expr equal to X but certainly not valid as an lvalue. */
2428 tree
2430 {
2431 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2432 us. */
2439 }
2441 /* When pedantic, return an expr equal to X but certainly not valid as a
2442 pedantic lvalue. Otherwise, return X. */
2444 static tree
2446 {
2448 }
2449 \f
2450 /* Given a tree comparison code, return the code that is the logical inverse.
2451 It is generally not safe to do this for floating-point comparisons, except
2452 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2453 ERROR_MARK in this case. */
2455 enum tree_code
2457 {
2463 {
2494 }
2495 }
2497 /* Similar, but return the comparison that results if the operands are
2498 swapped. This is safe for floating-point. */
2500 enum tree_code
2502 {
2504 {
2530 }
2531 }
2534 /* Convert a comparison tree code from an enum tree_code representation
2535 into a compcode bit-based encoding. This function is the inverse of
2536 compcode_to_comparison. */
2538 static enum comparison_code
2540 {
2542 {
2573 }
2574 }
2576 /* Convert a compcode bit-based encoding of a comparison operator back
2577 to GCC's enum tree_code representation. This function is the
2578 inverse of comparison_to_compcode. */
2580 static enum tree_code
2582 {
2584 {
2615 }
2616 }
2618 /* Return a tree for the comparison which is the combination of
2619 doing the AND or OR (depending on CODE) of the two operations LCODE
2620 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2621 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2622 if this makes the transformation invalid. */
2624 tree
2629 {
2636 {
2647 }
2650 {
2651 /* Eliminate unordered comparisons, as well as LTGT and ORD
2652 which are not used unless the mode has NaNs. */
2658 }
2660 {
2661 /* Check that the original operation and the optimized ones will trap
2662 under the same condition. */
2673 /* In a short-circuited boolean expression the LHS might be
2674 such that the RHS, if evaluated, will never trap. For
2675 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2676 if neither x nor y is NaN. (This is a mixed blessing: for
2677 example, the expression above will never trap, hence
2678 optimizing it to x < y would be invalid). */
2683 /* If the comparison was short-circuited, and only the RHS
2684 trapped, we may now generate a spurious trap. */
2689 /* If we changed the conditions that cause a trap, we lose. */
2692 }
2698 else
2699 {
2704 }
2705 }
2706 \f
2707 /* Return nonzero if two operands (typically of the same tree node)
2708 are necessarily equal. FLAGS modifies behavior as follows:
2710 If OEP_ONLY_CONST is set, only return nonzero for constants.
2711 This function tests whether the operands are indistinguishable;
2712 it does not test whether they are equal using C's == operation.
2713 The distinction is important for IEEE floating point, because
2714 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2715 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2717 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2718 even though it may hold multiple values during a function.
2719 This is because a GCC tree node guarantees that nothing else is
2720 executed between the evaluation of its "operands" (which may often
2721 be evaluated in arbitrary order). Hence if the operands themselves
2722 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2723 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2724 unset means assuming isochronic (or instantaneous) tree equivalence.
2725 Unless comparing arbitrary expression trees, such as from different
2726 statements, this flag can usually be left unset.
2728 If OEP_PURE_SAME is set, then pure functions with identical arguments
2729 are considered the same. It is used when the caller has other ways
2730 to ensure that global memory is unchanged in between.
2732 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2733 not values of expressions.
2735 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2736 any operand with side effect. This is unnecesarily conservative in the
2737 case we know that arg0 and arg1 are in disjoint code paths (such as in
2738 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2739 addresses with TREE_CONSTANT flag set so we know that &var == &var
2740 even if var is volatile. */
2742 int
2744 {
2745 /* When checking, verify at the outermost operand_equal_p call that
2746 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2747 hash value. */
2749 {
2751 {
2753 {
2760 }
2762 }
2763 else
2765 }
2767 /* If either is ERROR_MARK, they aren't equal. */
2773 /* Similar, if either does not have a type (like a released SSA name),
2774 they aren't equal. */
2778 /* We cannot consider pointers to different address space equal. */
2785 /* Check equality of integer constants before bailing out due to
2786 precision differences. */
2788 {
2789 /* Address of INTEGER_CST is not defined; check that we did not forget
2790 to drop the OEP_ADDRESS_OF flags. */
2793 }
2796 {
2797 /* If both types don't have the same signedness, then we can't consider
2798 them equal. We must check this before the STRIP_NOPS calls
2799 because they may change the signedness of the arguments. As pointers
2800 strictly don't have a signedness, require either two pointers or
2801 two non-pointers as well. */
2807 /* If both types don't have the same precision, then it is not safe
2808 to strip NOPs. */
2815 }
2816 #if 0
2817 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2818 sanity check once the issue is solved. */
2819 else
2820 /* Addresses of conversions and SSA_NAMEs (and many other things)
2821 are not defined. Check that we did not forget to drop the
2822 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2825 #endif
2827 /* In case both args are comparisons but with different comparison
2828 code, try to swap the comparison operands of one arg to produce
2829 a match and compare that variant. */
2833 {
2841 }
2844 {
2845 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2847 ;
2849 {
2850 /* If we are interested in comparing addresses ignore
2851 MEM_REF wrappings of the base that can appear just for
2852 TBAA reasons. */
2866 }
2867 else
2869 }
2871 /* When not checking adddresses, this is needed for conversions and for
2872 COMPONENT_REF. Might as well play it safe and always test this. */
2879 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2880 We don't care about side effects in that case because the SAVE_EXPR
2881 takes care of that for us. In all other cases, two expressions are
2882 equal if they have no side effects. If we have two identical
2883 expressions with side effects that should be treated the same due
2884 to the only side effects being identical SAVE_EXPR's, that will
2885 be detected in the recursive calls below.
2886 If we are taking an invariant address of two identical objects
2887 they are necessarily equal as well. */
2894 /* Next handle constant cases, those for which we can return 1 even
2895 if ONLY_CONST is set. */
2898 {
2912 {
2913 /* If we do not distinguish between signed and unsigned zero,
2914 consider them equal. */
2917 }
2921 {
2928 {
2932 }
2934 }
2938 flags)
2940 flags));
2951 flags | OEP_ADDRESS_OF
2954 /* In GIMPLE empty constructors are allowed in initializers of
2955 aggregates. */
2960 }
2965 /* Define macros to test an operand from arg0 and arg1 for equality and a
2966 variant that allows null and views null as being different from any
2967 non-null value. In the latter case, if either is null, the both
2968 must be; otherwise, do the normal comparison. */
2969 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2970 TREE_OPERAND (arg1, N), flags)
2972 #define OP_SAME_WITH_NULL(N) \
2973 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2974 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2977 {
2979 /* Two conversions are equal only if signedness and modes match. */
2981 {
2982 CASE_CONVERT:
2990 }
3000 /* For commutative ops, allow the other order. */
3008 /* If either of the pointer (or reference) expressions we are
3009 dereferencing contain a side effect, these cannot be equal,
3010 but their addresses can be. */
3017 {
3027 /* Require the same offset. */
3033 /* Fallthru. */
3041 {
3042 /* Require equal access sizes */
3048 flags)))
3050 /* Verify that access happens in similar types. */
3053 /* Verify that accesses are TBAA compatible. */
3062 /* Verify that alignment is compatible. */
3066 }
3069 /* TARGET_MEM_REF require equal extra operands. */
3080 /* Compare the array index by value if it is constant first as we
3081 may have different types but same value here. */
3087 /* Compare low bound and element size as with OEP_ADDRESS_OF
3088 we have to account for the offset of the ref. */
3093 array_ref_low_bound
3097 array_ref_element_size
3099 flags))));
3102 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3103 may be NULL when we're called to compare MEM_EXPRs. */
3118 }
3122 {
3124 /* Be sure we pass right ADDRESS_OF flag. */
3142 /* The multiplcation operands are commutative. */
3143 /* FALLTHRU */
3151 /* Otherwise take into account this is a commutative operation. */
3170 }
3174 {
3178 /* If not both CALL_EXPRs are either internal or normal function
3179 functions, then they are not equal. */
3182 {
3183 /* If the CALL_EXPRs call different internal functions, then they
3184 are not equal. */
3187 }
3188 else
3189 {
3190 /* If the CALL_EXPRs call different functions, then they are not
3191 equal. */
3193 flags))
3195 }
3197 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3198 {
3202 else
3206 }
3208 /* Now see if all the arguments are the same. */
3209 {
3220 /* If we get here and both argument lists are exhausted
3221 then the CALL_EXPRs are equal. */
3223 }
3226 }
3229 /* Consider __builtin_sqrt equal to sqrt. */
3237 {
3238 /* In GIMPLE constructors are used only to build vectors from
3239 elements. Individual elements in the constructor must be
3240 indexed in increasing order and form an initial sequence.
3242 We make no effort to compare constructors in generic.
3243 (see sem_variable::equals in ipa-icf which can do so for
3244 constants). */
3249 /* Be sure that vectors constructed have the same representation.
3250 We only tested element precision and modes to match.
3251 Vectors may be BLKmode and thus also check that the number of
3252 parts match. */
3265 {
3270 /* In GIMPLE the indexes can be either NULL or matching i.
3271 Double check this so we won't get false
3272 positives for GENERIC. */
3280 }
3282 }
3287 }
3289 #undef OP_SAME
3290 #undef OP_SAME_WITH_NULL
3291 }
3292 \f
3293 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3294 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3296 When in doubt, return 0. */
3298 static int
3300 {
3312 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3313 and see if the inner values are the same. This removes any
3314 signedness comparison, which doesn't matter here. */
3321 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3322 actual comparison operand, ARG0.
3324 First throw away any conversions to wider types
3325 already present in the operands. */
3334 {
3337 /* Make sure shorter operand is extended the right way
3338 to match the longer operand. */
3344 }
3347 }
3348 \f
3349 /* See if ARG is an expression that is either a comparison or is performing
3350 arithmetic on comparisons. The comparisons must only be comparing
3351 two different values, which will be stored in *CVAL1 and *CVAL2; if
3352 they are nonzero it means that some operands have already been found.
3353 No variables may be used anywhere else in the expression except in the
3354 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3355 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3357 If this is true, return 1. Otherwise, return zero. */
3359 static int
3361 {
3365 /* We can handle some of the tcc_expression cases here. */
3375 {
3376 /* If we've already found a CVAL1 or CVAL2, this expression is
3377 two complex to handle. */
3383 }
3386 {
3409 /* First see if we can handle the first operand, then the second. For
3410 the second operand, we know *CVAL1 can't be zero. It must be that
3411 one side of the comparison is each of the values; test for the
3412 case where this isn't true by failing if the two operands
3413 are the same. */
3422 ;
3426 ;
3427 else
3431 ;
3435 ;
3436 else
3443 }
3444 }
3445 \f
3446 /* ARG is a tree that is known to contain just arithmetic operations and
3447 comparisons. Evaluate the operations in the tree substituting NEW0 for
3448 any occurrence of OLD0 as an operand of a comparison and likewise for
3449 NEW1 and OLD1. */
3451 static tree
3454 {
3459 /* We can handle some of the tcc_expression cases here. */
3467 {
3482 {
3501 }
3502 /* Fall through - ??? */
3505 {
3509 /* We need to check both for exact equality and tree equality. The
3510 former will be true if the operand has a side-effect. In that
3511 case, we know the operand occurred exactly once. */
3524 }
3528 }
3529 }
3530 \f
3531 /* Return a tree for the case when the result of an expression is RESULT
3532 converted to TYPE and OMITTED was previously an operand of the expression
3533 but is now not needed (e.g., we folded OMITTED * 0).
3535 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3536 the conversion of RESULT to TYPE. */
3538 tree
3540 {
3543 /* If the resulting operand is an empty statement, just return the omitted
3544 statement casted to void. */
3554 }
3556 /* Return a tree for the case when the result of an expression is RESULT
3557 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3558 of the expression but are now not needed.
3560 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3561 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3562 evaluated before OMITTED2. Otherwise, if neither has side effects,
3563 just do the conversion of RESULT to TYPE. */
3565 tree
3568 {
3577 }
3579 \f
3580 /* Return a simplified tree node for the truth-negation of ARG. This
3581 never alters ARG itself. We assume that ARG is an operation that
3582 returns a truth value (0 or 1).
3584 FIXME: one would think we would fold the result, but it causes
3585 problems with the dominator optimizer. */
3587 static tree
3589 {
3594 /* If this is a comparison, we can simply invert it, except for
3595 floating-point non-equality comparisons, in which case we just
3596 enclose a TRUTH_NOT_EXPR around what we have. */
3599 {
3602 && flag_trapping_math
3616 }
3619 {
3638 /* Here we can invert either operand. We invert the first operand
3639 unless the second operand is a TRUTH_NOT_EXPR in which case our
3640 result is the XOR of the first operand with the inside of the
3641 negation of the second operand. */
3646 else
3669 {
3676 /* A COND_EXPR may have a throw as one operand, which
3677 then has void type. Just leave void operands
3678 as they are. */
3684 }
3696 CASE_CONVERT:
3700 /* ... fall through ... */
3722 }
3723 }
3725 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3726 assume that ARG is an operation that returns a truth value (0 or 1
3727 for scalars, 0 or -1 for vectors). Return the folded expression if
3728 folding is successful. Otherwise, return NULL_TREE. */
3730 static tree
3732 {
3735 ? BIT_NOT_EXPR
3738 }
3740 /* Return a simplified tree node for the truth-negation of ARG. This
3741 never alters ARG itself. We assume that ARG is an operation that
3742 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3744 tree
3746 {
3752 ? BIT_NOT_EXPR
3755 }
3757 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3758 with code CODE. This optimization is unsafe. */
3759 static tree
3762 {
3766 /* (A / C) +- (B / C) -> (A +- B) / C. */
3776 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3781 {
3793 }
3796 }
3797 \f
3798 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3799 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3800 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3801 is the original memory reference used to preserve the alias set of
3802 the access. */
3804 static tree
3808 {
3814 build_int_cst
3818 {
3825 }
3840 }
3842 /* Optimize a bit-field compare.
3844 There are two cases: First is a compare against a constant and the
3845 second is a comparison of two items where the fields are at the same
3846 bit position relative to the start of a chunk (byte, halfword, word)
3847 large enough to contain it. In these cases we can avoid the shift
3848 implicit in bitfield extractions.
3850 For constants, we emit a compare of the shifted constant with the
3851 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3852 compared. For two fields at the same position, we do the ANDs with the
3853 similar mask and compare the result of the ANDs.
3855 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3856 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3857 are the left and right operands of the comparison, respectively.
3859 If the optimization described above can be done, we return the resulting
3860 tree. Otherwise we return zero. */
3862 static tree
3865 {
3868 tree unsigned_type;
3875 tree mask;
3876 tree offset;
3878 /* Get all the information about the extractions being done. If the bit size
3879 if the same as the size of the underlying object, we aren't doing an
3880 extraction at all and so can do nothing. We also don't want to
3881 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3882 then will no longer be able to replace it. */
3891 else
3892 {
3893 /* If this is not a constant, we can only do something if bit positions,
3894 sizes, signedness and storage order are the same. */
3895 rinner
3903 }
3905 /* Honor the C++ memory model and mimic what RTL expansion does. */
3909 {
3913 }
3915 /* See if we can find a mode to refer to this field. We should be able to,
3916 but fail if we can't. */
3925 /* Set signed and unsigned types of the precision of this mode for the
3926 shifts below. */
3929 /* Compute the bit position and size for the new reference and our offset
3930 within it. If the new reference is the same size as the original, we
3931 won't optimize anything, so return zero. */
3941 /* Make the mask to be used against the extracted field. */
3948 /* If not comparing with constant, just rework the comparison
3949 and return. */
3953 unsigned_type,
3956 mask),
3959 unsigned_type,
3962 mask));
3964 /* Otherwise, we are handling the constant case. See if the constant is too
3965 big for the field. Warn and return a tree for 0 (false) if so. We do
3966 this not only for its own sake, but to avoid having to test for this
3967 error case below. If we didn't, we might generate wrong code.
3969 For unsigned fields, the constant shifted right by the field length should
3970 be all zero. For signed fields, the high-order bits should agree with
3971 the sign bit. */
3974 {
3976 {
3980 }
3981 }
3982 else
3983 {
3986 {
3990 }
3991 }
3993 /* Single-bit compares should always be against zero. */
3995 {
3998 }
4000 /* Make a new bitfield reference, shift the constant over the
4001 appropriate number of bits and mask it with the computed mask
4002 (in case this was a signed field). If we changed it, make a new one. */
4010 mask);
4015 }
4016 \f
4017 /* Subroutine for fold_truth_andor_1: decode a field reference.
4019 If EXP is a comparison reference, we return the innermost reference.
4021 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4022 set to the starting bit number.
4024 If the innermost field can be completely contained in a mode-sized
4025 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4027 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4028 otherwise it is not changed.
4030 *PUNSIGNEDP is set to the signedness of the field.
4032 *PREVERSEP is set to the storage order of the field.
4034 *PMASK is set to the mask used. This is either contained in a
4035 BIT_AND_EXPR or derived from the width of the field.
4037 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4039 Return 0 if this is not a component reference or is one that we can't
4040 do anything with. */
4042 static tree
4047 {
4052 tree unsigned_type;
4055 /* All the optimizations using this function assume integer fields.
4056 There are problems with FP fields since the type_for_size call
4057 below can fail for, e.g., XFmode. */
4061 /* We are interested in the bare arrangement of bits, so strip everything
4062 that doesn't affect the machine mode. However, record the type of the
4063 outermost expression if it may matter below. */
4070 {
4076 }
4087 /* If the number of bits in the reference is the same as the bitsize of
4088 the outer type, then the outer type gives the signedness. Otherwise
4089 (in case of a small bitfield) the signedness is unchanged. */
4093 /* Compute the mask to access the bitfield. */
4102 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4110 }
4112 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4113 bit positions and MASK is SIGNED. */
4115 static int
4117 {
4121 /* If this function returns true when the type of the mask is
4122 UNSIGNED, then there will be errors. In particular see
4123 gcc.c-torture/execute/990326-1.c. There does not appear to be
4124 any documentation paper trail as to why this is so. But the pre
4125 wide-int worked with that restriction and it has been preserved
4126 here. */
4131 }
4133 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4134 represents the sign bit of EXP's type. If EXP represents a sign
4135 or zero extension, also test VAL against the unextended type.
4136 The return value is the (sub)expression whose sign bit is VAL,
4137 or NULL_TREE otherwise. */
4139 tree
4141 {
4143 tree t;
4145 /* Tree EXP must have an integral type. */
4150 /* Tree VAL must be an integer constant. */
4159 /* Handle extension from a narrower type. */
4165 }
4167 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4168 to be evaluated unconditionally. */
4170 static int
4172 {
4173 /* Strip any conversions that don't change the machine mode. */
4182 /* Don't regard global variables as simple. They may be
4183 allocated in ways unknown to the compiler (shared memory,
4184 #pragma weak, etc). */
4187 /* Weakrefs are not safe to be read, since they can be NULL.
4188 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4189 have DECL_WEAK flag set. */
4191 /* Loading a static variable is unduly expensive, but global
4192 registers aren't expensive. */
4194 }
4196 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4197 to be evaluated unconditionally.
4198 I addition to simple_operand_p, we assume that comparisons, conversions,
4199 and logic-not operations are simple, if their operands are simple, too. */
4201 static bool
4203 {
4223 }
4225 \f
4226 /* The following functions are subroutines to fold_range_test and allow it to
4227 try to change a logical combination of comparisons into a range test.
4229 For example, both
4230 X == 2 || X == 3 || X == 4 || X == 5
4231 and
4232 X >= 2 && X <= 5
4233 are converted to
4234 (unsigned) (X - 2) <= 3
4236 We describe each set of comparisons as being either inside or outside
4237 a range, using a variable named like IN_P, and then describe the
4238 range with a lower and upper bound. If one of the bounds is omitted,
4239 it represents either the highest or lowest value of the type.
4241 In the comments below, we represent a range by two numbers in brackets
4242 preceded by a "+" to designate being inside that range, or a "-" to
4243 designate being outside that range, so the condition can be inverted by
4244 flipping the prefix. An omitted bound is represented by a "-". For
4245 example, "- [-, 10]" means being outside the range starting at the lowest
4246 possible value and ending at 10, in other words, being greater than 10.
4247 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4248 always false.
4250 We set up things so that the missing bounds are handled in a consistent
4251 manner so neither a missing bound nor "true" and "false" need to be
4252 handled using a special case. */
4254 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4255 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4256 and UPPER1_P are nonzero if the respective argument is an upper bound
4257 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4258 must be specified for a comparison. ARG1 will be converted to ARG0's
4259 type if both are specified. */
4261 static tree
4264 {
4265 tree tem;
4269 /* If neither arg represents infinity, do the normal operation.
4270 Else, if not a comparison, return infinity. Else handle the special
4271 comparison rules. Note that most of the cases below won't occur, but
4272 are handled for consistency. */
4275 {
4280 }
4285 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4286 for neither. In real maths, we cannot assume open ended ranges are
4287 the same. But, this is computer arithmetic, where numbers are finite.
4288 We can therefore make the transformation of any unbounded range with
4289 the value Z, Z being greater than any representable number. This permits
4290 us to treat unbounded ranges as equal. */
4294 {
4315 }
4318 }
4319 \f
4320 /* Helper routine for make_range. Perform one step for it, return
4321 new expression if the loop should continue or NULL_TREE if it should
4322 stop. */
4324 tree
4328 {
4334 {
4336 /* We can only do something if the range is testing for zero. */
4345 /* We can only do something if the range is testing for zero
4346 and if the second operand is an integer constant. Note that
4347 saying something is "in" the range we make is done by
4348 complementing IN_P since it will set in the initial case of
4349 being not equal to zero; "out" is leaving it alone. */
4356 {
4377 }
4379 /* If this is an unsigned comparison, we also know that EXP is
4380 greater than or equal to zero. We base the range tests we make
4381 on that fact, so we record it here so we can parse existing
4382 range tests. We test arg0_type since often the return type
4383 of, e.g. EQ_EXPR, is boolean. */
4385 {
4389 NULL_TREE))
4394 /* If the high bound is missing, but we have a nonzero low
4395 bound, reverse the range so it goes from zero to the low bound
4396 minus 1. */
4398 {
4403 }
4404 }
4412 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4413 low and high are non-NULL, then normalize will DTRT. */
4416 {
4421 }
4423 /* (-x) IN [a,b] -> x in [-b, -a] */
4435 /* ~ X -> -X - 1 */
4444 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4445 move a constant to the other side. */
4450 /* If EXP is signed, any overflow in the computation is undefined,
4451 so we don't worry about it so long as our computations on
4452 the bounds don't overflow. For unsigned, overflow is defined
4453 and this is exactly the right thing. */
4465 normalize:
4466 /* Check for an unsigned range which has wrapped around the maximum
4467 value thus making n_high < n_low, and normalize it. */
4469 {
4475 /* If the range is of the form +/- [ x+1, x ], we won't
4476 be able to normalize it. But then, it represents the
4477 whole range or the empty set, so make it
4478 +/- [ -, - ]. */
4482 else
4484 }
4485 else
4493 CASE_CONVERT:
4511 /* If we're converting arg0 from an unsigned type, to exp,
4512 a signed type, we will be doing the comparison as unsigned.
4513 The tests above have already verified that LOW and HIGH
4514 are both positive.
4516 So we have to ensure that we will handle large unsigned
4517 values the same way that the current signed bounds treat
4518 negative values. */
4521 {
4522 tree high_positive;
4523 tree equiv_type;
4524 /* For fixed-point modes, we need to pass the saturating flag
4525 as the 2nd parameter. */
4527 equiv_type
4530 else
4531 equiv_type
4534 /* A range without an upper bound is, naturally, unbounded.
4535 Since convert would have cropped a very large value, use
4536 the max value for the destination type. */
4537 high_positive
4544 high_positive),
4547 /* If the low bound is specified, "and" the range with the
4548 range for which the original unsigned value will be
4549 positive. */
4551 {
4554 integer_zero_node),
4555 high_positive))
4559 }
4560 else
4561 {
4562 /* Otherwise, "or" the range with the range of the input
4563 that will be interpreted as negative. */
4566 integer_zero_node),
4567 high_positive))
4571 }
4572 }
4581 }
4582 }
4584 /* Given EXP, a logical expression, set the range it is testing into
4585 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4586 actually being tested. *PLOW and *PHIGH will be made of the same
4587 type as the returned expression. If EXP is not a comparison, we
4588 will most likely not be returning a useful value and range. Set
4589 *STRICT_OVERFLOW_P to true if the return value is only valid
4590 because signed overflow is undefined; otherwise, do not change
4591 *STRICT_OVERFLOW_P. */
4593 tree
4596 {
4604 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4605 and see if we can refine the range. Some of the cases below may not
4606 happen, but it doesn't seem worth worrying about this. We "continue"
4607 the outer loop when we've changed something; otherwise we "break"
4608 the switch, which will "break" the while. */
4614 {
4620 {
4628 }
4637 }
4639 /* If EXP is a constant, we can evaluate whether this is true or false. */
4641 {
4648 }
4652 }
4653 \f
4654 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4655 type, TYPE, return an expression to test if EXP is in (or out of, depending
4656 on IN_P) the range. Return 0 if the test couldn't be created. */
4658 tree
4661 {
4664 /* Disable this optimization for function pointer expressions
4665 on targets that require function pointer canonicalization. */
4672 {
4678 }
4696 {
4698 {
4702 }
4704 }
4706 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4708 {
4712 {
4714 {
4717 etype
4719 else
4722 }
4725 }
4726 }
4728 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4729 This requires wrap-around arithmetics for the type of the expression.
4730 First make sure that arithmetics in this type is valid, then make sure
4731 that it wraps around. */
4737 {
4740 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4741 for the type in question, as we rely on this here. */
4751 else
4753 }
4763 {
4765 {
4770 }
4772 }
4780 }
4781 \f
4782 /* Return the predecessor of VAL in its type, handling the infinite case. */
4784 static tree
4786 {
4792 else
4795 }
4797 /* Return the successor of VAL in its type, handling the infinite case. */
4799 static tree
4801 {
4807 else
4810 }
4812 /* Given two ranges, see if we can merge them into one. Return 1 if we
4813 can, 0 if we can't. Set the output range into the specified parameters. */
4815 bool
4818 {
4822 tree tem;
4832 /* Make range 0 be the range that starts first, or ends last if they
4833 start at the same value. Swap them if it isn't. */
4836 || (lowequal
4839 {
4843 }
4845 /* Now flag two cases, whether the ranges are disjoint or whether the
4846 second range is totally subsumed in the first. Note that the tests
4847 below are simplified by the ones above. */
4853 /* We now have four cases, depending on whether we are including or
4854 excluding the two ranges. */
4856 {
4857 /* If they don't overlap, the result is false. If the second range
4858 is a subset it is the result. Otherwise, the range is from the start
4859 of the second to the end of the first. */
4864 else
4866 }
4869 {
4870 /* If they don't overlap, the result is the first range. If they are
4871 equal, the result is false. If the second range is a subset of the
4872 first, and the ranges begin at the same place, we go from just after
4873 the end of the second range to the end of the first. If the second
4874 range is not a subset of the first, or if it is a subset and both
4875 ranges end at the same place, the range starts at the start of the
4876 first range and ends just before the second range.
4877 Otherwise, we can't describe this as a single range. */
4883 {
4888 {
4889 /* We are in the weird situation where high0 > high1 but
4890 high1 has no successor. Punt. */
4892 }
4893 }
4895 {
4900 {
4901 /* low0 < low1 but low1 has no predecessor. Punt. */
4903 }
4904 }
4905 else
4907 }
4910 {
4911 /* If they don't overlap, the result is the second range. If the second
4912 is a subset of the first, the result is false. Otherwise,
4913 the range starts just after the first range and ends at the
4914 end of the second. */
4919 else
4920 {
4925 {
4926 /* high1 > high0 but high0 has no successor. Punt. */
4928 }
4929 }
4930 }
4932 else
4933 {
4934 /* The case where we are excluding both ranges. Here the complex case
4935 is if they don't overlap. In that case, the only time we have a
4936 range is if they are adjacent. If the second is a subset of the
4937 first, the result is the first. Otherwise, the range to exclude
4938 starts at the beginning of the first range and ends at the end of the
4939 second. */
4941 {
4946 else
4947 {
4948 /* Canonicalize - [min, x] into - [-, x]. */
4951 {
4956 /* FALLTHROUGH */
4969 }
4971 /* Canonicalize - [x, max] into - [x, -]. */
4974 {
4979 /* FALLTHROUGH */
4995 }
4997 /* The ranges might be also adjacent between the maximum and
4998 minimum values of the given type. For
4999 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5000 return + [x + 1, y - 1]. */
5002 {
5009 }
5010 else
5012 }
5013 }
5016 else
5018 }
5022 }
5023 \f
5025 /* Subroutine of fold, looking inside expressions of the form
5026 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5027 of the COND_EXPR. This function is being used also to optimize
5028 A op B ? C : A, by reversing the comparison first.
5030 Return a folded expression whose code is not a COND_EXPR
5031 anymore, or NULL_TREE if no folding opportunity is found. */
5033 static tree
5036 {
5041 tree tem;
5046 /* If we have A op 0 ? A : -A, consider applying the following
5047 transformations:
5049 A == 0? A : -A same as -A
5050 A != 0? A : -A same as A
5051 A >= 0? A : -A same as abs (A)
5052 A > 0? A : -A same as abs (A)
5053 A <= 0? A : -A same as -abs (A)
5054 A < 0? A : -A same as -abs (A)
5056 None of these transformations work for modes with signed
5057 zeros. If A is +/-0, the first two transformations will
5058 change the sign of the result (from +0 to -0, or vice
5059 versa). The last four will fix the sign of the result,
5060 even though the original expressions could be positive or
5061 negative, depending on the sign of A.
5063 Note that all these transformations are correct if A is
5064 NaN, since the two alternatives (A and -A) are also NaNs. */
5071 /* In the case that A is of the form X-Y, '-A' (arg2) may
5072 have already been folded to Y-X, check for that. */
5080 {
5094 /* Fall through. */
5114 }
5116 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5117 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5118 both transformations are correct when A is NaN: A != 0
5119 is then true, and A == 0 is false. */
5123 {
5128 }
5130 /* Try some transformations of A op B ? A : B.
5132 A == B? A : B same as B
5133 A != B? A : B same as A
5134 A >= B? A : B same as max (A, B)
5135 A > B? A : B same as max (B, A)
5136 A <= B? A : B same as min (A, B)
5137 A < B? A : B same as min (B, A)
5139 As above, these transformations don't work in the presence
5140 of signed zeros. For example, if A and B are zeros of
5141 opposite sign, the first two transformations will change
5142 the sign of the result. In the last four, the original
5143 expressions give different results for (A=+0, B=-0) and
5144 (A=-0, B=+0), but the transformed expressions do not.
5146 The first two transformations are correct if either A or B
5147 is a NaN. In the first transformation, the condition will
5148 be false, and B will indeed be chosen. In the case of the
5149 second transformation, the condition A != B will be true,
5150 and A will be chosen.
5152 The conversions to max() and min() are not correct if B is
5153 a number and A is not. The conditions in the original
5154 expressions will be false, so all four give B. The min()
5155 and max() versions would give a NaN instead. */
5158 /* Avoid these transformations if the COND_EXPR may be used
5159 as an lvalue in the C++ front-end. PR c++/19199. */
5160 && (in_gimple_form
5166 {
5171 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5173 {
5177 }
5180 {
5189 /* In C++ a ?: expression can be an lvalue, so put the
5190 operand which will be used if they are equal first
5191 so that we can convert this back to the
5192 corresponding COND_EXPR. */
5194 {
5203 }
5210 {
5219 }
5234 }
5235 }
5237 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5238 we might still be able to simplify this. For example,
5239 if C1 is one less or one more than C2, this might have started
5240 out as a MIN or MAX and been transformed by this function.
5241 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5247 {
5251 /* We can replace A with C1 in this case. */
5256 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5257 MIN_EXPR, to preserve the signedness of the comparison. */
5259 OEP_ONLY_CONST)
5263 OEP_ONLY_CONST))
5264 {
5267 arg2));
5270 }
5274 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5275 as above. */
5277 OEP_ONLY_CONST)
5281 OEP_ONLY_CONST))
5282 {
5285 arg2));
5288 }
5292 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5293 MAX_EXPR, to preserve the signedness of the comparison. */
5295 OEP_ONLY_CONST)
5299 OEP_ONLY_CONST))
5300 {
5303 arg2));
5305 }
5309 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5311 OEP_ONLY_CONST)
5315 OEP_ONLY_CONST))
5316 {
5319 arg2));
5321 }
5327 }
5330 }
5333 \f
5334 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5335 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5336 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5337 false) >= 2)
5338 #endif
5340 /* EXP is some logical combination of boolean tests. See if we can
5341 merge it into some range test. Return the new tree if so. */
5343 static tree
5346 {
5362 /* If this is an OR operation, invert both sides; we will invert
5363 again at the end. */
5367 /* If both expressions are the same, if we can merge the ranges, and we
5368 can build the range test, return it or it inverted. If one of the
5369 ranges is always true or always false, consider it to be the same
5370 expression as the other. */
5378 {
5382 }
5384 /* On machines where the branch cost is expensive, if this is a
5385 short-circuited branch and the underlying object on both sides
5386 is the same, make a non-short-circuit operation. */
5392 {
5393 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5394 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5395 which cases we can't do this. */
5403 {
5412 {
5415 WARN_STRICT_OVERFLOW_COMPARISON);
5419 }
5420 }
5421 }
5424 }
5425 \f
5426 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5427 bit value. Arrange things so the extra bits will be set to zero if and
5428 only if C is signed-extended to its full width. If MASK is nonzero,
5429 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5431 static tree
5433 {
5436 tree temp;
5441 /* We work by getting just the sign bit into the low-order bit, then
5442 into the high-order bit, then sign-extend. We then XOR that value
5443 with C. */
5446 /* We must use a signed type in order to get an arithmetic right shift.
5447 However, we must also avoid introducing accidental overflows, so that
5448 a subsequent call to integer_zerop will work. Hence we must
5449 do the type conversion here. At this point, the constant is either
5450 zero or one, and the conversion to a signed type can never overflow.
5451 We could get an overflow if this conversion is done anywhere else. */
5460 /* If necessary, convert the type back to match the type of C. */
5465 }
5466 \f
5467 /* For an expression that has the form
5468 (A && B) || ~B
5469 or
5470 (A || B) && ~B,
5471 we can drop one of the inner expressions and simplify to
5472 A || ~B
5473 or
5474 A && ~B
5475 LOC is the location of the resulting expression. OP is the inner
5476 logical operation; the left-hand side in the examples above, while CMPOP
5477 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5478 removing a condition that guards another, as in
5479 (A != NULL && A->...) || A == NULL
5480 which we must not transform. If RHS_ONLY is true, only eliminate the
5481 right-most operand of the inner logical operation. */
5483 static tree
5486 {
5504 {
5507 {
5510 }
5511 }
5513 {
5516 {
5519 }
5520 }
5535 }
5537 /* Find ways of folding logical expressions of LHS and RHS:
5538 Try to merge two comparisons to the same innermost item.
5539 Look for range tests like "ch >= '0' && ch <= '9'".
5540 Look for combinations of simple terms on machines with expensive branches
5541 and evaluate the RHS unconditionally.
5543 For example, if we have p->a == 2 && p->b == 4 and we can make an
5544 object large enough to span both A and B, we can do this with a comparison
5545 against the object ANDed with the a mask.
5547 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5548 operations to do this with one comparison.
5550 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5551 function and the one above.
5553 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5554 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5556 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5557 two operands.
5559 We return the simplified tree or 0 if no optimization is possible. */
5561 static tree
5564 {
5565 /* If this is the "or" of two comparisons, we can do something if
5566 the comparisons are NE_EXPR. If this is the "and", we can do something
5567 if the comparisons are EQ_EXPR. I.e.,
5568 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5570 WANTED_CODE is this operation code. For single bit fields, we can
5571 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5572 comparison for one-bit fields. */
5593 /* Start by getting the comparison codes. Fail if anything is volatile.
5594 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5595 it were surrounded with a NE_EXPR. */
5604 {
5608 }
5611 {
5615 }
5626 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5629 {
5632 {
5637 }
5640 {
5646 }
5647 }
5652 /* If the RHS can be evaluated unconditionally and its operands are
5653 simple, it wins to evaluate the RHS unconditionally on machines
5654 with expensive branches. In this case, this isn't a comparison
5655 that can be merged. */
5662 {
5663 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5674 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5684 }
5686 /* See if the comparisons can be merged. Then get all the parameters for
5687 each side. */
5712 /* It must be true that the inner operation on the lhs of each
5713 comparison must be the same if we are to be able to do anything.
5714 Then see if we have constants. If not, the same must be true for
5715 the rhs's. */
5724 {
5727 }
5732 else
5735 /* If either comparison code is not correct for our logical operation,
5736 fail. However, we can convert a one-bit comparison against zero into
5737 the opposite comparison against that bit being set in the field. */
5741 {
5743 {
5744 /* Make the left operand unsigned, since we are only interested
5745 in the value of one bit. Otherwise we are doing the wrong
5746 thing below. */
5749 }
5750 else
5752 }
5754 /* This is analogous to the code for l_const above. */
5756 {
5758 {
5761 }
5762 else
5764 }
5766 /* See if we can find a mode that contains both fields being compared on
5767 the left. If we can't, fail. Otherwise, update all constants and masks
5768 to be relative to a field of that size. */
5773 volatilep);
5783 {
5786 }
5794 {
5801 {
5805 }
5806 }
5808 {
5815 {
5819 }
5820 }
5822 /* If the right sides are not constant, do the same for it. Also,
5823 disallow this optimization if a size or signedness mismatch occurs
5824 between the left and right sides. */
5826 {
5829 /* Make sure the two fields on the right
5830 correspond to the left without being swapped. */
5838 volatilep);
5848 {
5851 }
5860 /* Make a mask that corresponds to both fields being compared.
5861 Do this for both items being compared. If the operands are the
5862 same size and the bits being compared are in the same position
5863 then we can do this by masking both and comparing the masked
5864 results. */
5868 {
5882 }
5884 /* There is still another way we can do something: If both pairs of
5885 fields being compared are adjacent, we may be able to make a wider
5886 field containing them both.
5888 Note that we still must mask the lhs/rhs expressions. Furthermore,
5889 the mask must be shifted to account for the shift done by
5890 make_bit_field_ref. */
5895 {
5896 tree type;
5912 /* Convert to the smaller type before masking out unwanted bits. */
5915 {
5917 {
5921 }
5923 {
5927 }
5928 }
5937 }
5940 }
5942 /* Handle the case of comparisons with constants. If there is something in
5943 common between the masks, those bits of the constants must be the same.
5944 If not, the condition is always false. Test for this to avoid generating
5945 incorrect code below. */
5950 {
5952 {
5955 }
5956 else
5957 {
5960 }
5961 }
5963 /* Construct the expression we will return. First get the component
5964 reference we will make. Unless the mask is all ones the width of
5965 that field, perform the mask operation. Then compare with the
5966 merged constant. */
5977 }
5978 \f
5979 /* T is an integer expression that is being multiplied, divided, or taken a
5980 modulus (CODE says which and what kind of divide or modulus) by a
5981 constant C. See if we can eliminate that operation by folding it with
5982 other operations already in T. WIDE_TYPE, if non-null, is a type that
5983 should be used for the computation if wider than our type.
5985 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5986 (X * 2) + (Y * 4). We must, however, be assured that either the original
5987 expression would not overflow or that overflow is undefined for the type
5988 in the language in question.
5990 If we return a non-null expression, it is an equivalent form of the
5991 original computation, but need not be in the original type.
5993 We set *STRICT_OVERFLOW_P to true if the return values depends on
5994 signed overflow being undefined. Otherwise we do not change
5995 *STRICT_OVERFLOW_P. */
5997 static tree
6000 {
6001 /* To avoid exponential search depth, refuse to allow recursion past
6002 three levels. Beyond that (1) it's highly unlikely that we'll find
6003 something interesting and (2) we've probably processed it before
6004 when we built the inner expression. */
6007 tree ret;
6012 depth++;
6014 depth--;
6017 }
6019 static tree
6022 {
6033 /* Don't deal with constants of zero here; they confuse the code below. */
6043 /* Note that we need not handle conditional operations here since fold
6044 already handles those cases. So just do arithmetic here. */
6046 {
6048 /* For a constant, we can always simplify if we are a multiply
6049 or (for divide and modulus) if it is a multiple of our constant. */
6052 {
6055 /* If the multiplication overflowed, we lost information on it.
6056 See PR68142 and PR69845. */
6060 }
6064 /* If op0 is an expression ... */
6070 /* ... and has wrapping overflow, and its type is smaller
6071 than ctype, then we cannot pass through as widening. */
6076 /* ... or this is a truncation (t is narrower than op0),
6077 then we cannot pass through this narrowing. */
6080 /* ... or signedness changes for division or modulus,
6081 then we cannot pass through this conversion. */
6085 /* ... or has undefined overflow while the converted to
6086 type has not, we cannot do the operation in the inner type
6087 as that would introduce undefined overflow. */
6093 /* Pass the constant down and see if we can make a simplification. If
6094 we can, replace this expression with the inner simplification for
6095 possible later conversion to our or some other type. */
6100 code == MULT_EXPR
6102 strict_overflow_p))))
6107 /* If widening the type changes it from signed to unsigned, then we
6108 must avoid building ABS_EXPR itself as unsigned. */
6110 {
6114 {
6117 }
6119 }
6120 /* If the constant is negative, we cannot simplify this. */
6123 /* FALLTHROUGH */
6125 /* For division and modulus, type can't be unsigned, as e.g.
6126 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6127 For signed types, even with wrapping overflow, this is fine. */
6136 /* If widening the type changes the signedness, then we can't perform
6137 this optimization as that changes the result. */
6141 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6147 {
6154 }
6158 /* If the second operand is constant, this is a multiplication
6159 or floor division, by a power of two, so we can treat it that
6160 way unless the multiplier or divisor overflows. Signed
6161 left-shift overflow is implementation-defined rather than
6162 undefined in C90, so do not convert signed left shift into
6163 multiplication. */
6166 /* const_binop may not detect overflow correctly,
6167 so check for it explicitly here. */
6171 size_one_node,
6172 op1)))
6176 ctype,
6178 t1),
6183 /* See if we can eliminate the operation on both sides. If we can, we
6184 can return a new PLUS or MINUS. If we can't, the only remaining
6185 cases where we can do anything are if the second operand is a
6186 constant. */
6192 /* If not multiplication, we can only do this if both operands
6193 are divisible by c. */
6196 {
6201 }
6203 /* If this was a subtraction, negate OP1 and set it to be an addition.
6204 This simplifies the logic below. */
6206 {
6208 /* If OP1 was not easily negatable, the constant may be OP0. */
6210 {
6213 }
6214 }
6219 /* If either OP1 or C are negative, this optimization is not safe for
6220 some of the division and remainder types while for others we need
6221 to change the code. */
6223 {
6231 }
6233 /* If it's a multiply or a division/modulus operation of a multiple
6234 of our constant, do the operation and verify it doesn't overflow. */
6237 {
6240 /* We allow the constant to overflow with wrapping semantics. */
6244 }
6245 else
6248 /* If we have an unsigned type, we cannot widen the operation since it
6249 will change the result if the original computation overflowed. */
6253 /* If we were able to eliminate our operation from the first side,
6254 apply our operation to the second side and reform the PLUS. */
6258 /* The last case is if we are a multiply. In that case, we can
6259 apply the distributive law to commute the multiply and addition
6260 if the multiplication of the constants doesn't overflow
6261 and overflow is defined. With undefined overflow
6262 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6268 op1);
6273 /* We have a special case here if we are doing something like
6274 (C * 8) % 4 since we know that's zero. */
6277 /* If the multiplication can overflow we cannot optimize this. */
6281 {
6284 }
6286 /* ... fall through ... */
6290 /* If we can extract our operation from the LHS, do so and return a
6291 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6292 do something only if the second operand is a constant. */
6306 /* If these are the same operation types, we can associate them
6307 assuming no overflow. */
6309 {
6324 }
6326 /* If these operations "cancel" each other, we have the main
6327 optimizations of this pass, which occur when either constant is a
6328 multiple of the other, in which case we replace this with either an
6329 operation or CODE or TCODE.
6331 If we have an unsigned type, we cannot do this since it will change
6332 the result if the original computation overflowed. */
6339 {
6341 {
6348 }
6350 {
6357 }
6358 }
6363 }
6366 }
6367 \f
6368 /* Return a node which has the indicated constant VALUE (either 0 or
6369 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6370 and is of the indicated TYPE. */
6372 tree
6374 {
6383 else
6385 }
6388 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6389 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6390 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6391 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6392 COND is the first argument to CODE; otherwise (as in the example
6393 given here), it is the second argument. TYPE is the type of the
6394 original expression. Return NULL_TREE if no simplification is
6395 possible. */
6397 static tree
6402 {
6412 {
6416 /* If this operand throws an expression, then it does not make
6417 sense to try to perform a logical or arithmetic operation
6418 involving it. */
6423 }
6426 {
6431 }
6432 else
6433 /* Detect the case of mixing vector and scalar types - bail out. */
6439 /* This transformation is only worthwhile if we don't have to wrap ARG
6440 in a SAVE_EXPR and the operation can be simplified without recursing
6441 on at least one of the branches once its pushed inside the COND_EXPR. */
6450 {
6454 else
6456 }
6458 {
6462 else
6464 }
6466 /* Check that we have simplified at least one of the branches. */
6471 }
6473 \f
6474 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6476 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6477 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6478 ADDEND is the same as X.
6480 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6481 and finite. The problematic cases are when X is zero, and its mode
6482 has signed zeros. In the case of rounding towards -infinity,
6483 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6484 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6486 bool
6488 {
6492 /* Don't allow the fold with -fsignaling-nans. */
6496 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6500 /* In a vector or complex, we would need to check the sign of all zeros. */
6504 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6508 /* The mode has signed zeros, and we have to honor their sign.
6509 In this situation, there is only one case we can return true for.
6510 X - 0 is the same as X unless rounding towards -infinity is
6511 supported. */
6513 }
6515 /* Subroutine of fold() that optimizes comparisons of a division by
6516 a nonzero integer constant against an integer constant, i.e.
6517 X/C1 op C2.
6519 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6520 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6521 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6523 The function returns the constant folded tree if a simplification
6524 can be made, and NULL_TREE otherwise. */
6526 static tree
6529 {
6537 /* We have to do this the hard way to detect unsigned overflow.
6538 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6544 {
6549 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6553 }
6555 {
6559 {
6578 }
6579 }
6580 else
6581 {
6582 /* A negative divisor reverses the relational operators. */
6588 {
6607 }
6608 }
6611 {
6632 {
6635 }
6640 {
6643 }
6648 {
6651 }
6656 {
6659 }
6664 }
6667 }
6670 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6671 equality/inequality test, then return a simplified form of the test
6672 using a sign testing. Otherwise return NULL. TYPE is the desired
6673 result type. */
6675 static tree
6678 tree result_type)
6679 {
6680 /* If this is testing a single bit, we can optimize the test. */
6684 {
6685 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6686 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6690 /* This is only a win if casting to a signed type is cheap,
6691 i.e. when arg00's type is not a partial mode. */
6694 {
6697 result_type,
6700 }
6701 }
6704 }
6706 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6707 equality/inequality test, then return a simplified form of
6708 the test using shifts and logical operations. Otherwise return
6709 NULL. TYPE is the desired result type. */
6711 tree
6714 {
6715 /* If this is testing a single bit, we can optimize the test. */
6719 {
6728 /* First, see if we can fold the single bit test into a sign-bit
6729 test. */
6731 result_type);
6735 /* Otherwise we have (A & C) != 0 where C is a single bit,
6736 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6737 Similarly for (A & C) == 0. */
6739 /* If INNER is a right shift of a constant and it plus BITNUM does
6740 not overflow, adjust BITNUM and INNER. */
6746 {
6749 }
6751 /* If we are going to be able to omit the AND below, we must do our
6752 operations as unsigned. If we must use the AND, we have a choice.
6753 Normally unsigned is faster, but for some machines signed is. */
6771 /* Put the AND last so it can combine with more things. */
6774 /* Make sure to return the proper type. */
6778 }
6780 }
6782 /* Check whether we are allowed to reorder operands arg0 and arg1,
6783 such that the evaluation of arg1 occurs before arg0. */
6785 static bool
6787 {
6794 }
6796 /* Test whether it is preferable two swap two operands, ARG0 and
6797 ARG1, for example because ARG0 is an integer constant and ARG1
6798 isn't. If REORDER is true, only recommend swapping if we can
6799 evaluate the operands in reverse order. */
6801 bool
6803 {
6821 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6822 for commutative and comparison operators. Ensuring a canonical
6823 form allows the optimizers to find additional redundancies without
6824 having to explicitly check for both orderings. */
6830 /* Put SSA_NAMEs last. */
6836 /* Put variables last. */
6843 }
6846 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6847 means A >= Y && A != MAX, but in this case we know that
6848 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6850 static tree
6852 {
6859 else
6868 {
6871 }
6873 {
6876 }
6877 else
6884 {
6885 /* Convert the pointer types into integer before taking the difference. */
6889 }
6890 else
6897 }
6899 /* Fold a sum or difference of at least one multiplication.
6900 Returns the folded tree or NULL if no simplification could be made. */
6902 static tree
6905 {
6909 /* (A * C) +- (B * C) -> (A+-B) * C.
6910 (A * C) +- A -> A * (C+-1).
6911 We are most concerned about the case where C is a constant,
6912 but other combinations show up during loop reduction. Since
6913 it is not difficult, try all four possibilities. */
6916 {
6919 }
6921 {
6924 }
6925 else
6926 {
6927 /* We cannot generate constant 1 for fract. */
6932 }
6934 {
6937 }
6939 {
6941 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6942 the purpose of this canonicalization. */
6946 {
6949 }
6950 else
6952 }
6953 else
6954 {
6955 /* We cannot generate constant 1 for fract. */
6960 }
6972 /* No identical multiplicands; see if we can find a common
6973 power-of-two factor in non-power-of-two multiplies. This
6974 can help in multi-dimensional array access. */
6977 {
6980 tree maybe_same;
6984 /* Move min of absolute values to int11. */
6986 {
6991 }
6992 else
6996 /* The remainder should not be a constant, otherwise we
6997 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6998 increased the number of multiplications necessary. */
7000 {
7008 }
7009 }
7019 }
7021 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7022 specified by EXPR into the buffer PTR of length LEN bytes.
7023 Return the number of bytes placed in the buffer, or zero
7024 upon failure. */
7026 static int
7028 {
7042 {
7044 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7045 number of bytes. */
7049 {
7056 else
7058 }
7059 else
7064 }
7066 }
7069 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7070 specified by EXPR into the buffer PTR of length LEN bytes.
7071 Return the number of bytes placed in the buffer, or zero
7072 upon failure. */
7074 static int
7076 {
7080 FIXED_VALUE_TYPE value;
7096 }
7099 /* Subroutine of native_encode_expr. Encode the REAL_CST
7100 specified by EXPR into the buffer PTR of length LEN bytes.
7101 Return the number of bytes placed in the buffer, or zero
7102 upon failure. */
7104 static int
7106 {
7112 /* There are always 32 bits in each long, no matter the size of
7113 the hosts long. We handle floating point representations with
7114 up to 192 bits. */
7128 {
7133 {
7140 else
7142 }
7143 else
7149 }
7151 }
7153 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7154 specified by EXPR into the buffer PTR of length LEN bytes.
7155 Return the number of bytes placed in the buffer, or zero
7156 upon failure. */
7158 static int
7160 {
7162 tree part;
7177 }
7180 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7181 specified by EXPR into the buffer PTR of length LEN bytes.
7182 Return the number of bytes placed in the buffer, or zero
7183 upon failure. */
7185 static int
7187 {
7197 {
7199 {
7202 }
7213 }
7215 }
7218 /* Subroutine of native_encode_expr. Encode the STRING_CST
7219 specified by EXPR into the buffer PTR of length LEN bytes.
7220 Return the number of bytes placed in the buffer, or zero
7221 upon failure. */
7223 static int
7225 {
7227 HOST_WIDE_INT total_bytes;
7241 {
7244 {
7247 }
7250 }
7251 else
7254 }
7257 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7258 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7259 buffer PTR of length LEN bytes. If OFF is not -1 then start
7260 the encoding at byte offset OFF and encode at most LEN bytes.
7261 Return the number of bytes placed in the buffer, or zero upon failure. */
7263 int
7265 {
7266 /* We don't support starting at negative offset and -1 is special. */
7271 {
7292 }
7293 }
7296 /* Subroutine of native_interpret_expr. Interpret the contents of
7297 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7298 If the buffer cannot be interpreted, return NULL_TREE. */
7300 static tree
7302 {
7312 }
7315 /* Subroutine of native_interpret_expr. Interpret the contents of
7316 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7317 If the buffer cannot be interpreted, return NULL_TREE. */
7319 static tree
7321 {
7323 double_int result;
7324 FIXED_VALUE_TYPE fixed_value;
7334 }
7337 /* Subroutine of native_interpret_expr. Interpret the contents of
7338 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7339 If the buffer cannot be interpreted, return NULL_TREE. */
7341 static tree
7343 {
7347 /* There are always 32 bits in each long, no matter the size of
7348 the hosts long. We handle floating point representations with
7349 up to 192 bits. */
7350 REAL_VALUE_TYPE r;
7361 {
7362 /* Both OFFSET and BYTE index within a long;
7363 bitpos indexes the whole float. */
7366 {
7373 else
7375 }
7376 else
7377 {
7380 {
7381 /* Reverse bytes within each long, or within the entire float
7382 if it's smaller than a long (for HFmode). */
7385 }
7386 }
7390 }
7394 }
7397 /* Subroutine of native_interpret_expr. Interpret the contents of
7398 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7399 If the buffer cannot be interpreted, return NULL_TREE. */
7401 static tree
7403 {
7418 }
7421 /* Subroutine of native_interpret_expr. Interpret the contents of
7422 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7423 If the buffer cannot be interpreted, return NULL_TREE. */
7425 static tree
7427 {
7440 {
7445 }
7447 }
7450 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7451 the buffer PTR of length LEN as a constant of type TYPE. For
7452 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7453 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7454 return NULL_TREE. */
7456 tree
7458 {
7460 {
7482 }
7483 }
7485 /* Returns true if we can interpret the contents of a native encoding
7486 as TYPE. */
7488 static bool
7490 {
7492 {
7505 }
7506 }
7508 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7509 TYPE at compile-time. If we're unable to perform the conversion
7510 return NULL_TREE. */
7512 static tree
7514 {
7515 /* We support up to 512-bit values (for V8DFmode). */
7519 /* Check that the host and target are sane. */
7528 }
7530 /* Build an expression for the address of T. Folds away INDIRECT_REF
7531 to avoid confusing the gimplify process. */
7533 tree
7535 {
7536 /* The size of the object is not relevant when talking about its address. */
7541 {
7546 }
7556 {
7561 }
7562 else
7566 }
7568 /* Build an expression for the address of T. */
7570 tree
7572 {
7576 }
7578 /* Fold a unary expression of code CODE and type TYPE with operand
7579 OP0. Return the folded expression if folding is successful.
7580 Otherwise, return NULL_TREE. */
7582 tree
7584 {
7585 tree tem;
7586 tree arg0;
7594 {
7597 {
7598 /* Don't use STRIP_NOPS, because signedness of argument type
7599 matters. */
7601 }
7602 else
7603 {
7604 /* Strip any conversions that don't change the mode. This
7605 is safe for every expression, except for a comparison
7606 expression because its signedness is derived from its
7607 operands.
7609 Note that this is done as an internal manipulation within
7610 the constant folder, in order to find the simplest
7611 representation of the arguments so that their form can be
7612 studied. In any cases, the appropriate type conversions
7613 should be put back in the tree that will get out of the
7614 constant folder. */
7616 }
7619 {
7622 {
7626 }
7627 }
7628 }
7635 {
7642 {
7656 /* If this was a conversion, and all we did was to move into
7657 inside the COND_EXPR, bring it back out. But leave it if
7658 it is a conversion from integer to integer and the
7659 result precision is no wider than a word since such a
7660 conversion is cheap and may be optimized away by combine,
7661 while it couldn't if it were outside the COND_EXPR. Then return
7662 so we don't get into an infinite recursion loop taking the
7663 conversion out and then back in. */
7675 && (INTEGRAL_TYPE_P
7688 }
7689 }
7692 {
7698 CASE_CONVERT:
7702 {
7703 /* If we have (type) (a CMP b) and type is an integral type, return
7704 new expression involving the new type. Canonicalize
7705 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7706 non-integral type.
7707 Do not fold the result as that would not simplify further, also
7708 folding again results in recursions. */
7718 }
7720 /* Handle (T *)&A.B.C for A being of type T and B and C
7721 living at offset zero. This occurs frequently in
7722 C++ upcasting and then accessing the base. */
7726 {
7728 tree offset;
7729 machine_mode mode;
7731 tree base
7735 /* If the reference was to a (constant) zero offset, we can use
7736 the address of the base if it has the same base type
7737 as the result type and the pointer type is unqualified. */
7744 }
7748 /* Detect assigning a bitfield. */
7750 && DECL_BIT_FIELD
7752 {
7753 /* Don't leave an assignment inside a conversion
7754 unless assigning a bitfield. */
7756 /* First do the assignment, then return converted constant. */
7761 }
7763 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7764 constants (if x has signed type, the sign bit cannot be set
7765 in c). This folds extension into the BIT_AND_EXPR.
7766 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7767 very likely don't have maximal range for their precision and this
7768 transformation effectively doesn't preserve non-maximal ranges. */
7772 {
7783 <= HOST_BITS_PER_WIDE_INT
7785 {
7789 cst &= HOST_WIDE_INT_M1U
7793 && !flag_syntax_only
7796 {
7800 }
7801 }
7803 {
7808 }
7809 }
7811 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7812 cast (T1)X will fold away. We assume that this happens when X itself
7813 is a cast. */
7817 {
7821 return fold_build_pointer_plus_loc
7823 }
7825 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7826 of the same precision, and X is an integer type not narrower than
7827 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7833 {
7839 }
7841 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7842 type of X and Y (integer types only). */
7847 {
7848 /* Be careful not to introduce new overflows. */
7849 tree mult_type;
7852 else
7856 {
7863 }
7864 }
7870 {
7877 }
7888 /* Convert fabs((double)float) into (double)fabsf(float). */
7891 {
7897 targ0));
7898 }
7902 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7921 /* Note that the operand of this must be an int
7922 and its values must be 0 or 1.
7923 ("true" is a fixed value perhaps depending on the language,
7924 but we don't handle values other than 1 correctly yet.) */
7931 /* Fold *&X to X if X is an lvalue. */
7933 {
7940 }
7946 }
7949 /* If the operation was a conversion do _not_ mark a resulting constant
7950 with TREE_OVERFLOW if the original constant was not. These conversions
7951 have implementation defined behavior and retaining the TREE_OVERFLOW
7952 flag here would confuse later passes such as VRP. */
7953 tree
7956 {
7965 }
7967 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7968 operands OP0 and OP1. LOC is the location of the resulting expression.
7969 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7970 Return the folded expression if folding is successful. Otherwise,
7971 return NULL_TREE. */
7972 static tree
7975 {
7976 tree tem;
7978 /* We only do these simplifications if we are optimizing. */
7982 /* Check for things like (A || B) && (A || C). We can convert this
7983 to A || (B && C). Note that either operator can be any of the four
7984 truth and/or operations and the transformation will still be
7985 valid. Also note that we only care about order for the
7986 ANDIF and ORIF operators. If B contains side effects, this
7987 might change the truth-value of A. */
7994 {
8014 /* This case if tricky because we must either have commutative
8015 operators or else A10 must not have side-effects. */
8021 a01);
8022 }
8024 /* See if we can build a range comparison. */
8030 {
8034 }
8038 {
8042 }
8044 /* Check for the possibility of merging component references. If our
8045 lhs is another similar operation, try to merge its rhs with our
8046 rhs. Then try to merge our lhs and rhs. */
8060 {
8067 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8068 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8069 We don't want to pack more than two leafs to a non-IF AND/OR
8070 expression.
8071 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8072 equal to IF-CODE, then we don't want to add right-hand operand.
8073 If the inner right-hand side of left-hand operand has
8074 side-effects, or isn't simple, then we can't add to it,
8075 as otherwise we might destroy if-sequence. */
8078 /* Needed for sequence points to handle trappings, and
8079 side-effects. */
8081 {
8083 arg1);
8085 tem);
8086 }
8087 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8088 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8091 /* Needed for sequence points to handle trappings, and
8092 side-effects. */
8094 {
8099 }
8100 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8101 into (A OR B).
8102 For sequence point consistancy, we need to check for trapping,
8103 and side-effects. */
8107 }
8110 }
8112 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8113 by changing CODE to reduce the magnitude of constants involved in
8114 ARG0 of the comparison.
8115 Returns a canonicalized comparison tree if a simplification was
8116 possible, otherwise returns NULL_TREE.
8117 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8118 valid if signed overflow is undefined. */
8120 static tree
8124 {
8129 /* Match A +- CST code arg1. We can change this only if overflow
8130 is undefined. */
8133 /* In principle pointers also have undefined overflow behavior,
8134 but that causes problems elsewhere. */
8141 /* Identify the constant in arg0 and its sign. */
8145 /* Overflowed constants and zero will cause problems. */
8150 /* See if we can reduce the magnitude of the constant in
8151 arg0 by changing the comparison code. */
8152 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8156 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8160 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8164 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8168 else
8172 /* Now build the constant reduced in magnitude. But not if that
8173 would produce one outside of its types range. */
8189 }
8191 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8192 overflow further. Try to decrease the magnitude of constants involved
8193 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8194 and put sole constants at the second argument position.
8195 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8197 static tree
8200 {
8201 tree t;
8206 /* Try canonicalization by simplifying arg0. */
8211 {
8215 }
8217 /* Try canonicalization by simplifying arg1 using the swapped
8218 comparison. */
8226 }
8228 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8229 space. This is used to avoid issuing overflow warnings for
8230 expressions like &p->x which can not wrap. */
8232 static bool
8234 {
8241 wide_int wi_offset;
8247 else
8263 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8264 array. */
8266 {
8267 HOST_WIDE_INT base_size;
8272 }
8275 }
8277 /* Return a positive integer when the symbol DECL is known to have
8278 a nonzero address, zero when it's known not to (e.g., it's a weak
8279 symbol), and a negative integer when the symbol is not yet in the
8280 symbol table and so whether or not its address is zero is unknown. */
8281 static int
8283 {
8289 }
8291 /* Subroutine of fold_binary. This routine performs all of the
8292 transformations that are common to the equality/inequality
8293 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8294 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8295 fold_binary should call fold_binary. Fold a comparison with
8296 tree code CODE and type TYPE with operands OP0 and OP1. Return
8297 the folded comparison or NULL_TREE. */
8299 static tree
8302 {
8312 /* For comparisons of pointers we can decompose it to a compile time
8313 comparison of the base objects and the offsets into the object.
8314 This requires at least one operand being an ADDR_EXPR or a
8315 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8321 {
8324 machine_mode mode;
8328 /* Get base and offset for the access. Strip ADDR_EXPR for
8329 get_inner_reference, but put it back by stripping INDIRECT_REF
8330 off the base object if possible. indirect_baseN will be true
8331 if baseN is not an address but refers to the object itself. */
8334 {
8335 base0
8341 else
8343 }
8345 {
8349 {
8350 base0
8357 else
8359 }
8362 else
8366 {
8372 {
8375 }
8376 }
8377 }
8381 {
8382 base1
8388 else
8390 }
8392 {
8396 {
8397 base1
8404 else
8406 }
8409 else
8413 {
8419 {
8422 }
8423 }
8424 }
8426 /* If we have equivalent bases we might be able to simplify. */
8430 {
8431 /* We can fold this expression to a constant if the non-constant
8432 offset parts are equal. */
8436 && (equality_code
8437 || (indirect_base0
8441 {
8447 "occur when comparing P +- C1 with "
8449 WARN_STRICT_OVERFLOW_CONDITIONAL);
8452 {
8466 }
8467 }
8468 /* We can simplify the comparison to a comparison of the variable
8469 offset parts if the constant offset parts are equal.
8470 Be careful to use signed sizetype here because otherwise we
8471 mess with array offsets in the wrong way. This is possible
8472 because pointer arithmetic is restricted to retain within an
8473 object and overflow on pointer differences is undefined as of
8474 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8476 && (equality_code
8477 || (indirect_base0
8480 {
8481 /* By converting to signed sizetype we cover middle-end pointer
8482 arithmetic which operates on unsigned pointer types of size
8483 type size and ARRAY_REF offsets which are properly sign or
8484 zero extended from their type in case it is narrower than
8485 sizetype. */
8488 else
8492 else
8499 "occur when comparing P +- C1 with "
8501 WARN_STRICT_OVERFLOW_COMPARISON);
8504 }
8505 }
8506 /* For equal offsets we can simplify to a comparison of the
8507 base addresses. */
8509 && (indirect_base0
8511 && (indirect_base1
8516 {
8522 }
8523 /* Comparison between an ordinary (non-weak) symbol and a null
8524 pointer can be eliminated since such symbols must have a non
8525 null address. In C, relational expressions between pointers
8526 to objects and null pointers are undefined. The results
8527 below follow the C++ rules with the additional property that
8528 every object pointer compares greater than a null pointer.
8529 */
8532 /* Avoid folding references to struct members at offset 0 to
8533 prevent tests like '&ptr->firstmember == 0' from getting
8534 eliminated. When ptr is null, although the -> expression
8535 is strictly speaking invalid, GCC retains it as a matter
8536 of QoI. See PR c/44555. */
8538 /* The caller guarantees that when one of the arguments is
8539 constant (i.e., null in this case) it is second. */
8541 {
8543 {
8554 }
8555 }
8556 }
8558 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8559 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8560 the resulting offset is smaller in absolute value than the
8561 original one and has the same sign. */
8570 {
8575 tree cst;
8577 "occur when combining constants around "
8580 /* Put the constant on the side where it doesn't overflow and is
8581 of lower absolute value and of same sign than before. */
8588 {
8591 variable1,
8595 }
8603 {
8609 variable2);
8610 }
8611 }
8617 /* If we are comparing an expression that just has comparisons
8618 of two integer values, arithmetic expressions of those comparisons,
8619 and constants, we can simplify it. There are only three cases
8620 to check: the two values can either be equal, the first can be
8621 greater, or the second can be greater. Fold the expression for
8622 those three values. Since each value must be 0 or 1, we have
8623 eight possibilities, each of which corresponds to the constant 0
8624 or 1 or one of the six possible comparisons.
8626 This handles common cases like (a > b) == 0 but also handles
8627 expressions like ((x > y) - (y > x)) > 0, which supposedly
8628 occur in macroized code. */
8631 {
8636 /* Don't handle degenerate cases here; they should already
8637 have been handled anyway. */
8646 {
8650 /* We can't just pass T to eval_subst in case cval1 or cval2
8651 was the same as ARG1. */
8653 tree high_result
8657 arg1);
8658 tree equal_result
8662 arg1);
8663 tree low_result
8667 arg1);
8669 /* All three of these results should be 0 or 1. Confirm they are.
8670 Then use those values to select the proper code to use. */
8675 {
8676 /* Make a 3-bit mask with the high-order bit being the
8677 value for `>', the next for '=', and the low for '<'. */
8681 {
8683 /* Always false. */
8704 /* Always true. */
8706 }
8709 {
8713 }
8715 }
8716 }
8717 }
8719 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8720 into a single range test. */
8728 {
8732 }
8735 }
8738 /* Subroutine of fold_binary. Optimize complex multiplications of the
8739 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8740 argument EXPR represents the expression "z" of type TYPE. */
8742 static tree
8744 {
8749 {
8752 }
8754 {
8757 }
8758 else
8759 {
8763 }
8772 }
8775 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8776 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8778 static bool
8780 {
8784 {
8787 }
8789 {
8795 else
8797 }
8798 else
8804 }
8806 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8807 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8808 NULL_TREE otherwise. */
8810 static tree
8812 {
8829 {
8833 }
8836 {
8842 }
8843 else
8845 }
8847 /* Try to fold a pointer difference of type TYPE two address expressions of
8848 array references AREF0 and AREF1 using location LOC. Return a
8849 simplified expression for the difference or NULL_TREE. */
8851 static tree
8854 {
8859 /* If the bases are array references as well, recurse. If the bases
8860 are pointer indirections compute the difference of the pointers.
8861 If the bases are equal, we are set. */
8864 && (base_offset
8868 && (base_offset
8874 {
8880 base_offset,
8883 }
8885 }
8887 /* If the real or vector real constant CST of type TYPE has an exact
8888 inverse, return it, else return NULL. */
8890 tree
8892 {
8893 REAL_VALUE_TYPE r;
8895 machine_mode mode;
8899 {
8915 {
8920 }
8926 }
8927 }
8929 /* Mask out the tz least significant bits of X of type TYPE where
8930 tz is the number of trailing zeroes in Y. */
8931 static wide_int
8933 {
8938 }
8940 /* Return true when T is an address and is known to be nonzero.
8941 For floating point we further ensure that T is not denormal.
8942 Similar logic is present in nonzero_address in rtlanal.h.
8944 If the return value is based on the assumption that signed overflow
8945 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8946 change *STRICT_OVERFLOW_P. */
8948 static bool
8950 {
8954 /* Doing something useful for floating point would need more work. */
8960 {
8963 strict_overflow_p);
8969 strict_overflow_p);
8977 }
8980 {
8983 strict_overflow_p);
8991 strict_overflow_p);
9006 strict_overflow_p);
9010 strict_overflow_p);
9013 {
9025 }
9029 }
9031 }
9033 /* Return true when T is an address and is known to be nonzero.
9034 Handle warnings about undefined signed overflow. */
9036 static bool
9038 {
9045 "determining that expression is always "
9047 WARN_STRICT_OVERFLOW_MISC);
9049 }
9051 /* Return true if T is known not to be equal to an integer W. */
9053 bool
9055 {
9057 value_range_type rtype;
9059 {
9068 {
9073 }
9078 /* If T has some known zero bits and W has any of those bits set,
9079 then T is known not to be equal to W. */
9087 }
9088 }
9090 /* Fold a binary expression of code CODE and type TYPE with operands
9091 OP0 and OP1. LOC is the location of the resulting expression.
9092 Return the folded expression if folding is successful. Otherwise,
9093 return NULL_TREE. */
9095 tree
9098 {
9113 /* Strip any conversions that don't change the mode. This is
9114 safe for every expression, except for a comparison expression
9115 because its signedness is derived from its operands. So, in
9116 the latter case, only strip conversions that don't change the
9117 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9118 preserved.
9120 Note that this is done as an internal manipulation within the
9121 constant folder, in order to find the simplest representation
9122 of the arguments so that their form can be studied. In any
9123 cases, the appropriate type conversions should be put back in
9124 the tree that will get out of the constant folder. */
9127 {
9130 }
9131 else
9132 {
9135 }
9137 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9138 constant but we can't do arithmetic on them. */
9140 {
9143 {
9147 }
9148 }
9150 /* If this is a commutative operation, and ARG0 is a constant, move it
9151 to ARG1 to reduce the number of tests below. */
9156 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9157 to ARG1 to reduce the number of tests below. */
9166 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9168 First check for cases where an arithmetic operation is applied to a
9169 compound, conditional, or comparison operation. Push the arithmetic
9170 operation inside the compound or conditional to see if any folding
9171 can then be done. Convert comparison to conditional for this purpose.
9172 The also optimizes non-constant cases that used to be done in
9173 expand_expr.
9175 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9176 one of the operands is a comparison and the other is a comparison, a
9177 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9178 code below would make the expression more complex. Change it to a
9179 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9180 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9193 {
9197 boolean_type_node,
9205 }
9209 {
9211 {
9216 tem);
9217 }
9220 {
9225 tem);
9226 }
9231 {
9237 }
9242 {
9248 }
9249 }
9252 {
9254 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9257 {
9263 }
9265 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9268 {
9269 tree base;
9270 HOST_WIDE_INT coffset;
9279 }
9284 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9290 arg1),
9292 arg0)));
9298 {
9299 /* X + (X / CST) * -CST is X % CST. */
9304 {
9313 cst0));
9314 }
9315 }
9317 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9318 one. Make sure the type is not saturating and has the signedness of
9319 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9320 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9327 {
9331 }
9334 {
9335 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9336 (plus (plus (mult) (mult)) (foo)) so that we can
9337 take advantage of the factoring cases below. */
9346 {
9352 else
9365 parg0),
9367 marg)),
9371 return
9377 parg1)));
9378 }
9379 }
9380 else
9381 {
9382 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9383 to __complex__ ( x, y ). This is not the same for SNaNs or
9384 if signed zeros are involved. */
9388 {
9395 {
9399 {
9405 }
9407 {
9413 }
9414 }
9415 }
9423 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9424 We associate floats only if the user has specified
9425 -fassociative-math. */
9429 {
9434 {
9435 tree tree0;
9438 }
9439 }
9440 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9441 We associate floats only if the user has specified
9442 -fassociative-math. */
9446 {
9451 {
9452 tree tree0;
9455 }
9456 }
9457 }
9459 bit_rotate:
9460 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9461 is a rotate of A by C1 bits. */
9462 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9463 is a rotate of A by B bits. */
9464 {
9466 tree rtype;
9475 /* Only create rotates in complete modes. Other cases are not
9476 expanded properly. */
9479 {
9493 {
9497 code0 == LSHIFT_EXPR
9501 }
9503 {
9511 element_precision
9515 return
9518 ? LROTATE_EXPR
9523 }
9525 {
9533 element_precision
9537 return fold_convert_loc
9540 ? LROTATE_EXPR
9544 }
9545 }
9546 }
9548 associate:
9549 /* In most languages, can't associate operations on floats through
9550 parentheses. Rather than remember where the parentheses were, we
9551 don't associate floats at all, unless the user has specified
9552 -fassociative-math.
9553 And, we need to make sure type is not saturating. */
9557 {
9563 /* Split both trees into variables, constants, and literals. Then
9564 associate each group together, the constants with literals,
9565 then the result with variables. This increases the chances of
9566 literals being recombined later and of generating relocatable
9567 expressions for the sum of a constant and literal. */
9573 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9577 /* With undefined overflow prefer doing association in a type
9578 which wraps on overflow, if that is one of the operand types. */
9581 {
9589 }
9591 /* With undefined overflow we can only associate constants with one
9592 variable, and constants whose association doesn't overflow. */
9595 {
9597 {
9603 {
9606 }
9613 {
9616 }
9622 /* The only case we can still associate with two variables
9623 is if they cancel out. */
9627 }
9628 }
9630 /* Only do something if we found more than two objects. Otherwise,
9631 nothing has changed and we risk infinite recursion. */
9637 {
9649 /* Preserve the MINUS_EXPR if the negative part of the literal is
9650 greater than the positive part. Otherwise, the multiplicative
9651 folding code (i.e extract_muldiv) may be fooled in case
9652 unsigned constants are subtracted, like in the following
9653 example: ((X*2 + 4) - 8U)/2. */
9655 {
9659 {
9663 }
9664 else
9665 {
9669 }
9670 }
9672 /* Don't introduce overflows through reassociation. */
9679 {
9681 return
9685 else
9686 {
9689 return
9693 }
9694 }
9697 return
9700 }
9701 }
9706 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9715 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9716 __complex__ ( x, -y ). This is not the same for SNaNs or if
9717 signed zeros are involved. */
9721 {
9728 {
9732 {
9734 arg1r ? arg1r
9739 }
9741 {
9745 arg1i ? arg1i
9748 }
9749 }
9750 }
9752 /* A - B -> A + (-B) if B is easily negatable. */
9756 /* Avoid this transformation if B is a positive REAL_CST. */
9764 /* Fold &a[i] - &a[j] to i-j. */
9769 {
9775 }
9778 && flag_unsafe_math_optimizations
9784 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9785 one. Make sure the type is not saturating and has the signedness of
9786 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9787 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9794 {
9798 }
9804 {
9805 /* Transform x * -C into -x * C if x is easily negatable. */
9819 {
9822 "occur when simplifying "
9824 WARN_STRICT_OVERFLOW_MISC);
9826 }
9828 /* Optimize z * conj(z) for integer complex numbers. */
9835 }
9836 else
9837 {
9838 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9839 This is not the same for NaNs or if signed zeros are
9840 involved. */
9846 {
9849 return
9855 return
9860 }
9862 /* Optimize z * conj(z) for floating point complex numbers.
9863 Guarded by flag_unsafe_math_optimizations as non-finite
9864 imaginary components don't produce scalar results. */
9873 }
9877 /* Canonicalize (X & C1) | C2. */
9881 {
9886 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9894 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9899 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9900 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9901 mode which allows further optimizations. */
9906 {
9910 {
9913 }
9914 }
9921 c3)),
9922 arg1);
9923 }
9925 /* See if this can be simplified into a rotate first. If that
9926 is unsuccessful continue in the association code. */
9930 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9938 /* See if this can be simplified into a rotate first. If that
9939 is unsuccessful continue in the association code. */
9943 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9948 {
9949 tree tem2;
9956 }
9957 /* Fold ~X & 1 as (X & 1) == 0. */
9961 {
9962 tree tem2;
9969 }
9970 /* Fold !X & 1 as X == 0. */
9973 {
9977 }
9979 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9980 multiple of 1 << CST. */
9982 {
9989 }
9991 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
9992 bits from CST2. */
9996 {
10004 {
10005 /* Avoid the transform if arg1 is a mask of some
10006 mode which allows further optimizations. */
10013 }
10014 }
10016 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10017 ((A & N) + B) & M -> (A + B) & M
10018 Similarly if (N & M) == 0,
10019 ((A | N) + B) & M -> (A + B) & M
10020 and for - instead of + (or unary - instead of +)
10021 and/or ^ instead of |.
10022 If B is constant and (B & M) == 0, fold into A & M. */
10024 {
10033 {
10036 wide_int cst0;
10038 /* Now we know that arg0 is (C + D) or (C - D) or
10039 -C and arg1 (M) is == (1LL << cst) - 1.
10040 Store C into PMOP[0] and D into PMOP[1]. */
10044 {
10047 }
10054 {
10064 {
10067 }
10070 /* If C or D is of the form (A & N) where
10071 (N & M) == M, or of the form (A | N) or
10072 (A ^ N) where (N & M) == 0, replace it with A. */
10076 /* If C or D is a N where (N & M) == 0, it can be
10077 omitted (assumed 0). */
10085 }
10087 /* Only build anything new if we optimized one or both arguments
10088 above. */
10092 {
10095 {
10096 /* Perform the operations in a type that has defined
10097 overflow behavior. */
10103 }
10108 {
10116 else
10118 }
10121 else
10124 /* TEM is now the new binary +, - or unary - replacement. */
10128 }
10129 }
10130 }
10132 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10135 {
10140 return
10142 }
10147 /* Don't touch a floating-point divide by zero unless the mode
10148 of the constant can represent infinity. */
10154 /* (-A) / (-B) -> A / B */
10166 /* Fall through */
10169 /* Simplify A / (B << N) where A and B are positive and B is
10170 a power of 2, to A >> (N + log2(B)). */
10175 {
10178 {
10186 WARN_STRICT_OVERFLOW_MISC);
10192 }
10193 }
10195 /* Fall through */
10203 /* Convert -A / -B to A / B when the type is signed and overflow is
10204 undefined. */
10208 {
10211 "when distributing negation across "
10213 WARN_STRICT_OVERFLOW_MISC);
10218 }
10222 {
10225 "when distributing negation across "
10227 WARN_STRICT_OVERFLOW_MISC);
10232 }
10234 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10235 operation, EXACT_DIV_EXPR.
10237 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10238 At one time others generated faster code, it's not clear if they do
10239 after the last round to changes to the DIV code in expmed.c. */
10250 {
10254 WARN_STRICT_OVERFLOW_MISC);
10256 }
10268 {
10272 WARN_STRICT_OVERFLOW_MISC);
10274 }
10282 /* Since negative shift count is not well-defined,
10283 don't try to compute it in the compiler. */
10289 /* If we have a rotate of a bit operation with the rotate count and
10290 the second operand of the bit operation both constant,
10291 permute the two operations. */
10297 {
10305 }
10307 /* Two consecutive rotates adding up to the some integer
10308 multiple of the precision of the type can be ignored. */
10323 /* Note that the operands of this must be ints
10324 and their values must be 0 or 1.
10325 ("true" is a fixed value perhaps depending on the language.) */
10326 /* If first arg is constant zero, return it. */
10330 /* If either arg is constant true, drop it. */
10334 /* Preserve sequence points. */
10337 /* If second arg is constant zero, result is zero, but first arg
10338 must be evaluated. */
10341 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10342 case will be handled here. */
10346 /* !X && X is always false. */
10350 /* X && !X is always false. */
10355 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10356 means A >= Y && A != MAX, but in this case we know that
10357 A < X <= MAX. */
10361 {
10369 }
10378 /* Note that the operands of this must be ints
10379 and their values must be 0 or true.
10380 ("true" is a fixed value perhaps depending on the language.) */
10381 /* If first arg is constant true, return it. */
10385 /* If either arg is constant zero, drop it. */
10389 /* Preserve sequence points. */
10392 /* If second arg is constant true, result is true, but we must
10393 evaluate first arg. */
10396 /* Likewise for first arg, but note this only occurs here for
10397 TRUTH_OR_EXPR. */
10401 /* !X || X is always true. */
10405 /* X || !X is always true. */
10410 /* (X && !Y) || (!X && Y) is X ^ Y */
10413 {
10430 }
10439 /* If the second arg is constant zero, drop it. */
10442 /* If the second arg is constant true, this is a logical inversion. */
10444 {
10447 }
10448 /* Identical arguments cancel to zero. */
10452 /* !X ^ X is always true. */
10457 /* X ^ !X is always true. */
10473 /* bool_var != 1 becomes !bool_var. */
10480 /* bool_var == 0 becomes !bool_var. */
10487 /* !exp != 0 becomes !exp */
10492 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10501 {
10507 }
10509 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10518 {
10524 }
10526 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10534 code == NE_EXPR
10538 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10546 code == NE_EXPR
10550 /* If this is an EQ or NE comparison with zero and ARG0 is
10551 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10552 two operations, but the latter can be done in one less insn
10553 on machines that have only two-operand insns or on which a
10554 constant cannot be the first operand. */
10557 {
10562 {
10569 arg1);
10570 }
10573 {
10580 arg1);
10581 }
10582 }
10584 /* If this is an NE or EQ comparison of zero against the result of a
10585 signed MOD operation whose second operand is a power of 2, make
10586 the MOD operation unsigned since it is simpler and equivalent. */
10594 {
10604 }
10606 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10607 C1 is a valid shift constant, and C2 is a power of two, i.e.
10608 a single bit. */
10612 == INTEGER_CST
10615 {
10620 /* Check for a valid shift count. */
10622 {
10626 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10627 can be rewritten as (X & (C2 << C1)) != 0. */
10629 {
10634 }
10635 /* Otherwise, for signed (arithmetic) shifts,
10636 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10637 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10641 /* Otherwise, of unsigned (logical) shifts,
10642 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10643 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10644 else
10648 arg000);
10649 }
10650 }
10652 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10653 Similarly for NE_EXPR. */
10657 {
10661 tree dandnotc
10664 notc);
10668 }
10670 /* If this is a comparison of a field, we may be able to simplify it. */
10673 /* Handle the constant case even without -O
10674 to make sure the warnings are given. */
10676 {
10680 }
10682 /* Optimize comparisons of strlen vs zero to a compare of the
10683 first character of the string vs zero. To wit,
10684 strlen(ptr) == 0 => *ptr == 0
10685 strlen(ptr) != 0 => *ptr != 0
10686 Other cases should reduce to one of these two (or a constant)
10687 due to the return value of strlen being unsigned. */
10690 {
10698 {
10703 }
10704 }
10706 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10707 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10711 {
10716 {
10718 {
10721 }
10724 }
10725 }
10727 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10728 (X & C) == 0 when C is a single bit. */
10733 {
10740 arg1));
10741 }
10743 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10744 constant C is a power of two, i.e. a single bit. */
10751 {
10755 }
10757 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10758 when is C is a power of two, i.e. a single bit. */
10765 {
10771 }
10775 {
10778 }
10780 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10783 {
10796 arg01),
10805 arg01),
10814 arg00),
10823 arg00),
10825 }
10829 {
10836 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10837 operand_equal_p guarantees no side-effects so we don't need
10838 to use omit_one_operand on Z. */
10842 arg10));
10846 arg11));
10850 arg10));
10854 arg11));
10856 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10859 {
10865 }
10866 }
10868 /* Attempt to simplify equality/inequality comparisons of complex
10869 values. Only lower the comparison if the result is known or
10870 can be simplified to a single scalar comparison. */
10875 {
10880 {
10883 }
10884 else
10885 {
10888 }
10891 {
10894 }
10895 else
10896 {
10899 }
10903 {
10905 {
10910 }
10911 else
10912 {
10917 }
10918 }
10922 {
10924 {
10929 }
10930 else
10931 {
10936 }
10937 }
10938 }
10950 /* Transform comparisons of the form X +- C CMP X. */
10957 {
10964 else
10967 /* (X - c) > X becomes false. */
10971 {
10975 "occur when assuming that (X - c) > X "
10977 WARN_STRICT_OVERFLOW_ALL);
10979 }
10981 /* Likewise (X + c) < X becomes false. */
10985 {
10989 "occur when assuming that "
10991 WARN_STRICT_OVERFLOW_ALL);
10993 }
10995 /* Convert (X - c) <= X to true. */
11000 {
11004 "occur when assuming that "
11006 WARN_STRICT_OVERFLOW_ALL);
11008 }
11010 /* Convert (X + c) >= X to true. */
11015 {
11019 "occur when assuming that "
11021 WARN_STRICT_OVERFLOW_ALL);
11023 }
11026 {
11027 /* Convert X + c > X and X - c < X to true for integers. */
11031 {
11034 "not occur when assuming that "
11036 WARN_STRICT_OVERFLOW_ALL);
11038 }
11043 {
11046 "not occur when assuming that "
11048 WARN_STRICT_OVERFLOW_ALL);
11050 }
11052 /* Convert X + c <= X and X - c >= X to false for integers. */
11056 {
11059 "not occur when assuming that "
11061 WARN_STRICT_OVERFLOW_ALL);
11063 }
11068 {
11071 "not occur when assuming that "
11073 WARN_STRICT_OVERFLOW_ALL);
11075 }
11076 }
11077 }
11079 /* If we are comparing an ABS_EXPR with a constant, we can
11080 convert all the cases into explicit comparisons, but they may
11081 well not be faster than doing the ABS and one comparison.
11082 But ABS (X) <= C is a range comparison, which becomes a subtraction
11083 and a comparison, and is probably faster. */
11097 /* Convert ABS_EXPR<x> >= 0 to true. */
11104 {
11107 "when simplifying comparison of "
11109 WARN_STRICT_OVERFLOW_CONDITIONAL);
11112 arg0);
11113 }
11115 /* Convert ABS_EXPR<x> < 0 to false. */
11120 {
11123 "when simplifying comparison of "
11125 WARN_STRICT_OVERFLOW_CONDITIONAL);
11128 arg0);
11129 }
11131 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11132 and similarly for >= into !=. */
11142 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11143 otherwise Y might be >= # of bits in X's type and thus e.g.
11144 (unsigned char) (1 << Y) for Y 15 might be 0.
11145 If the cast is widening, then 1 << Y should have unsigned type,
11146 otherwise if Y is number of bits in the signed shift type minus 1,
11147 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11148 31 might be 0xffffffff80000000. */
11159 {
11165 }
11177 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11178 {
11190 }
11195 /* When pedantic, a compound expression can be neither an lvalue
11196 nor an integer constant expression. */
11199 /* Don't let (0, 0) be null pointer constant. */
11205 /* An ASSERT_EXPR should never be passed to fold_binary. */
11211 }
11213 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11214 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11215 of GOTO_EXPR. */
11217 static tree
11219 {
11221 {
11228 /* ... fall through ... */
11232 }
11233 }
11235 /* Return whether the sub-tree ST contains a label which is accessible from
11236 outside the sub-tree. */
11238 static bool
11240 {
11241 return
11243 }
11245 /* Fold a ternary expression of code CODE and type TYPE with operands
11246 OP0, OP1, and OP2. Return the folded expression if folding is
11247 successful. Otherwise, return NULL_TREE. */
11249 tree
11252 {
11253 tree tem;
11260 /* If this is a commutative operation, and OP0 is a constant, move it
11261 to OP1 to reduce the number of tests below. */
11270 /* Strip any conversions that don't change the mode. This is safe
11271 for every expression, except for a comparison expression because
11272 its signedness is derived from its operands. So, in the latter
11273 case, only strip conversions that don't change the signedness.
11275 Note that this is done as an internal manipulation within the
11276 constant folder, in order to find the simplest representation of
11277 the arguments so that their form can be studied. In any cases,
11278 the appropriate type conversions should be put back in the tree
11279 that will get out of the constant folder. */
11281 {
11284 }
11287 {
11290 }
11293 {
11296 }
11299 {
11303 {
11309 }
11314 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11315 so all simple results must be passed through pedantic_non_lvalue. */
11317 {
11320 /* Only optimize constant conditions when the selected branch
11321 has the same type as the COND_EXPR. This avoids optimizing
11322 away "c ? x : throw", where the throw has a void type.
11323 Avoid throwing away that operand which contains label. */
11330 }
11332 {
11337 {
11342 {
11350 }
11354 }
11355 }
11357 /* If we have A op B ? A : C, we may be able to convert this to a
11358 simpler expression, depending on the operation and the values
11359 of B and C. Signed zeros prevent all of these transformations,
11360 for reasons given above each one.
11362 Also try swapping the arguments and inverting the conditional. */
11367 {
11371 }
11375 op2,
11378 {
11382 {
11386 }
11387 }
11389 /* If the second operand is simpler than the third, swap them
11390 since that produces better jump optimization results. */
11393 {
11395 /* See if this can be inverted. If it can't, possibly because
11396 it was a floating-point inequality comparison, don't do
11397 anything. */
11401 }
11403 /* Convert A ? 1 : 0 to simply A. */
11408 /* If we try to convert OP0 to our type, the
11409 call to fold will try to move the conversion inside
11410 a COND, which will recurse. In that case, the COND_EXPR
11411 is probably the best choice, so leave it alone. */
11415 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11416 over COND_EXPR in cases such as floating point comparisons. */
11425 arg0)));
11427 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11432 {
11433 /* sign_bit_p looks through both zero and sign extensions,
11434 but for this optimization only sign extensions are
11435 usable. */
11438 {
11441 {
11444 }
11446 }
11447 /* sign_bit_p only checks ARG1 bits within A's precision.
11448 If <sign bit of A> has wider type than A, bits outside
11449 of A's precision in <sign bit of A> need to be checked.
11450 If they are all 0, this optimization needs to be done
11451 in unsigned A's type, if they are all 1 in signed A's type,
11452 otherwise this can't be done. */
11458 {
11460 tree tem_type;
11473 {
11476 }
11478 {
11481 }
11482 else
11484 }
11487 return
11493 arg1)));
11494 }
11496 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11497 already handled above. */
11502 {
11511 }
11513 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11514 is probably obsolete because the first operand should be a
11515 truth value (that's why we have the two cases above), but let's
11516 leave it in until we can confirm this for all front-ends. */
11528 /* Disable the transformations below for vectors, since
11529 fold_binary_op_with_conditional_arg may undo them immediately,
11530 yielding an infinite loop. */
11534 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11543 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11548 {
11550 /* Only perform transformation if ARG0 is easily inverted. */
11554 ? BIT_IOR_EXPR
11557 arg1);
11558 }
11560 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11565 {
11567 /* Only perform transformation if ARG0 is easily inverted. */
11573 op2);
11574 }
11576 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11588 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11589 of fold_ternary on them. */
11597 {
11607 {
11612 {
11620 }
11621 }
11622 }
11624 /* On constants we can use native encode/interpret to constant
11625 fold (nearly) all BIT_FIELD_REFs. */
11629 {
11632 /* Limit us to a reasonable amount of work. To relax the
11633 other limitations we need bit-shifting of the buffer
11634 and rounding up the size. */
11638 {
11640 unsigned HOST_WIDE_INT len
11645 {
11650 }
11651 }
11652 }
11657 /* For integers we can decompose the FMA if possible. */
11669 {
11685 {
11690 /* Make sure that the perm value is in an acceptable
11691 range. */
11700 else
11705 }
11708 {
11713 }
11718 {
11723 }
11729 {
11733 }
11738 /* Some targets are deficient and fail to expand a single
11739 argument permutation while still allowing an equivalent
11740 2-argument version. */
11744 {
11747 }
11750 {
11757 }
11761 }
11765 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11768 {
11774 wide_int tem2
11778 }
11783 {
11785 unsigned HOST_WIDE_INT elsize
11788 {
11792 else
11793 {
11799 }
11800 }
11801 }
11807 }
11809 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11810 of an array (or vector). */
11812 tree
11814 {
11819 {
11822 {
11823 /* Static constructors for variably sized objects makes no sense. */
11827 }
11828 }
11839 offset_int max_index;
11844 {
11845 /* Array constructor might explicitly set index, or specify a range,
11846 or leave index NULL meaning that it is next index after previous
11847 one. */
11849 {
11852 else
11853 {
11857 }
11858 }
11859 else
11860 {
11866 }
11868 /* Do we have match? */
11872 }
11874 }
11876 /* Perform constant folding and related simplification of EXPR.
11877 The related simplifications include x*1 => x, x*0 => 0, etc.,
11878 and application of the associative law.
11879 NOP_EXPR conversions may be removed freely (as long as we
11880 are careful not to change the type of the overall expression).
11881 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11882 but we can constant-fold them if they have constant operands. */
11884 #ifdef ENABLE_FOLD_CHECKING
11885 # define fold(x) fold_1 (x)
11887 static
11888 #endif
11889 tree
11891 {
11895 tree tem;
11898 /* Return right away if a constant. */
11902 /* CALL_EXPR-like objects with variable numbers of operands are
11903 treated specially. */
11905 {
11907 {
11910 }
11912 }
11915 {
11920 {
11938 }
11939 }
11942 {
11944 {
11951 {
11956 }
11959 }
11961 /* Return a VECTOR_CST if possible. */
11963 {
11969 tree val;
11975 }
11983 }
11985 #ifdef ENABLE_FOLD_CHECKING
11986 #undef fold
11993 /* When --enable-checking=fold, compute a digest of expr before
11994 and after actual fold call to see if fold did not accidentally
11995 change original expr. */
11997 tree
11999 {
12000 tree ret;
12020 }
12022 void
12024 {
12035 }
12037 static void
12039 {
12041 }
12043 static void
12046 {
12052 recursive_label:
12062 {
12063 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12068 }
12076 {
12077 /* Allow these fields to be modified. */
12078 tree tmp;
12087 {
12090 }
12091 }
12102 {
12105 {
12120 }
12124 {
12137 }
12154 {
12160 }
12163 {
12165 {
12168 }
12170 }
12181 {
12184 }
12194 }
12195 }
12197 /* Helper function for outputting the checksum of a tree T. When
12198 debugging with gdb, you can "define mynext" to be "next" followed
12199 by "call debug_fold_checksum (op0)", then just trace down till the
12200 outputs differ. */
12202 DEBUG_FUNCTION void
12204 {
12219 }
12221 #endif
12223 /* Fold a unary tree expression with code CODE of type TYPE with an
12224 operand OP0. LOC is the location of the resulting expression.
12225 Return a folded expression if successful. Otherwise, return a tree
12226 expression with code CODE of type TYPE with an operand OP0. */
12228 tree
12231 {
12232 tree tem;
12233 #ifdef ENABLE_FOLD_CHECKING
12242 #endif
12248 #ifdef ENABLE_FOLD_CHECKING
12255 #endif
12257 }
12259 /* Fold a binary tree expression with code CODE of type TYPE with
12260 operands OP0 and OP1. LOC is the location of the resulting
12261 expression. Return a folded expression if successful. Otherwise,
12262 return a tree expression with code CODE of type TYPE with operands
12263 OP0 and OP1. */
12265 tree
12268 MEM_STAT_DECL)
12269 {
12270 tree tem;
12271 #ifdef ENABLE_FOLD_CHECKING
12288 #endif
12294 #ifdef ENABLE_FOLD_CHECKING
12309 #endif
12311 }
12313 /* Fold a ternary tree expression with code CODE of type TYPE with
12314 operands OP0, OP1, and OP2. Return a folded expression if
12315 successful. Otherwise, return a tree expression with code CODE of
12316 type TYPE with operands OP0, OP1, and OP2. */
12318 tree
12321 {
12322 tree tem;
12323 #ifdef ENABLE_FOLD_CHECKING
12347 #endif
12354 #ifdef ENABLE_FOLD_CHECKING
12377 #endif
12379 }
12381 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12382 arguments in ARGARRAY, and a null static chain.
12383 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12384 of type TYPE from the given operands as constructed by build_call_array. */
12386 tree
12389 {
12390 tree tem;
12391 #ifdef ENABLE_FOLD_CHECKING
12410 #endif
12416 #ifdef ENABLE_FOLD_CHECKING
12432 #endif
12434 }
12436 /* Perform constant folding and related simplification of initializer
12437 expression EXPR. These behave identically to "fold_buildN" but ignore
12438 potential run-time traps and exceptions that fold must preserve. */
12440 #define START_FOLD_INIT \
12441 int saved_signaling_nans = flag_signaling_nans;\
12442 int saved_trapping_math = flag_trapping_math;\
12443 int saved_rounding_math = flag_rounding_math;\
12444 int saved_trapv = flag_trapv;\
12445 int saved_folding_initializer = folding_initializer;\
12446 flag_signaling_nans = 0;\
12447 flag_trapping_math = 0;\
12448 flag_rounding_math = 0;\
12449 flag_trapv = 0;\
12450 folding_initializer = 1;
12452 #define END_FOLD_INIT \
12453 flag_signaling_nans = saved_signaling_nans;\
12454 flag_trapping_math = saved_trapping_math;\
12455 flag_rounding_math = saved_rounding_math;\
12456 flag_trapv = saved_trapv;\
12457 folding_initializer = saved_folding_initializer;
12459 tree
12462 {
12463 tree result;
12464 START_FOLD_INIT;
12468 END_FOLD_INIT;
12470 }
12472 tree
12475 {
12476 tree result;
12477 START_FOLD_INIT;
12481 END_FOLD_INIT;
12483 }
12485 tree
12488 {
12489 tree result;
12490 START_FOLD_INIT;
12494 END_FOLD_INIT;
12496 }
12498 #undef START_FOLD_INIT
12499 #undef END_FOLD_INIT
12501 /* Determine if first argument is a multiple of second argument. Return 0 if
12502 it is not, or we cannot easily determined it to be.
12504 An example of the sort of thing we care about (at this point; this routine
12505 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12506 fold cases do now) is discovering that
12508 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12510 is a multiple of
12512 SAVE_EXPR (J * 8)
12514 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12516 This code also handles discovering that
12518 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12520 is a multiple of 8 so we don't have to worry about dealing with a
12521 possible remainder.
12523 Note that we *look* inside a SAVE_EXPR only to determine how it was
12524 calculated; it is not safe for fold to do much of anything else with the
12525 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12526 at run time. For example, the latter example above *cannot* be implemented
12527 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12528 evaluation time of the original SAVE_EXPR is not necessarily the same at
12529 the time the new expression is evaluated. The only optimization of this
12530 sort that would be valid is changing
12532 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12534 divided by 8 to
12536 SAVE_EXPR (I) * SAVE_EXPR (J)
12538 (where the same SAVE_EXPR (J) is used in the original and the
12539 transformed version). */
12541 int
12543 {
12551 {
12553 /* Bitwise and provides a power of two multiple. If the mask is
12554 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12557 /* FALLTHRU */
12570 {
12574 /* const_binop may not detect overflow correctly,
12575 so check for it explicitly here. */
12579 size_one_node,
12580 op1)))
12583 }
12587 /* Can't handle conversions from non-integral or wider integral type. */
12593 /* .. fall through ... */
12610 SIGNED);
12614 }
12615 }
12617 #define tree_expr_nonnegative_warnv_p(X, Y) \
12620 #define RECURSE(X) \
12621 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12623 /* Return true if CODE or TYPE is known to be non-negative. */
12625 static bool
12627 {
12630 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12631 have a signed:1 type (where the value is -1 and 0). */
12634 }
12636 /* Return true if (CODE OP0) is known to be non-negative. If the return
12637 value is based on the assumption that signed overflow is undefined,
12638 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12639 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12641 bool
12644 {
12649 {
12651 /* We can't return 1 if flag_wrapv is set because
12652 ABS_EXPR<INT_MIN> = INT_MIN. */
12656 {
12659 }
12667 CASE_CONVERT:
12668 {
12673 {
12677 {
12681 }
12682 }
12684 {
12690 }
12691 }
12696 }
12698 /* We don't know sign of `t', so be conservative and return false. */
12700 }
12702 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12703 value is based on the assumption that signed overflow is undefined,
12704 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12705 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12707 bool
12711 {
12716 {
12722 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12723 both unsigned and at least 2 bits shorter than the result. */
12727 {
12732 {
12736 }
12737 }
12742 {
12743 /* x * x is always non-negative for floating point x
12744 or without overflow. */
12747 {
12752 }
12753 }
12755 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12756 both unsigned and their total bits is shorter than the result. */
12760 {
12779 {
12789 }
12790 }
12817 }
12819 /* We don't know sign of `t', so be conservative and return false. */
12821 }
12823 /* Return true if T is known to be non-negative. If the return
12824 value is based on the assumption that signed overflow is undefined,
12825 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12826 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12828 bool
12830 {
12835 {
12849 /* Limit the depth of recursion to avoid quadratic behavior.
12850 This is expected to catch almost all occurrences in practice.
12851 If this code misses important cases that unbounded recursion
12852 would not, passes that need this information could be revised
12853 to provide it through dataflow propagation. */
12861 }
12862 }
12864 /* Return true if T is known to be non-negative. If the return
12865 value is based on the assumption that signed overflow is undefined,
12866 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12867 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12869 bool
12872 {
12874 {
12875 CASE_CFN_ACOS:
12876 CASE_CFN_ACOSH:
12877 CASE_CFN_CABS:
12878 CASE_CFN_COSH:
12879 CASE_CFN_ERFC:
12880 CASE_CFN_EXP:
12881 CASE_CFN_EXP10:
12882 CASE_CFN_EXP2:
12883 CASE_CFN_FABS:
12884 CASE_CFN_FDIM:
12885 CASE_CFN_HYPOT:
12886 CASE_CFN_POW10:
12887 CASE_CFN_FFS:
12888 CASE_CFN_PARITY:
12889 CASE_CFN_POPCOUNT:
12890 CASE_CFN_CLZ:
12891 CASE_CFN_CLRSB:
12894 /* Always true. */
12897 CASE_CFN_SQRT:
12898 /* sqrt(-0.0) is -0.0. */
12903 CASE_CFN_ASINH:
12904 CASE_CFN_ATAN:
12905 CASE_CFN_ATANH:
12906 CASE_CFN_CBRT:
12907 CASE_CFN_CEIL:
12908 CASE_CFN_ERF:
12909 CASE_CFN_EXPM1:
12910 CASE_CFN_FLOOR:
12911 CASE_CFN_FMOD:
12912 CASE_CFN_FREXP:
12913 CASE_CFN_ICEIL:
12914 CASE_CFN_IFLOOR:
12915 CASE_CFN_IRINT:
12916 CASE_CFN_IROUND:
12917 CASE_CFN_LCEIL:
12918 CASE_CFN_LDEXP:
12919 CASE_CFN_LFLOOR:
12920 CASE_CFN_LLCEIL:
12921 CASE_CFN_LLFLOOR:
12922 CASE_CFN_LLRINT:
12923 CASE_CFN_LLROUND:
12924 CASE_CFN_LRINT:
12925 CASE_CFN_LROUND:
12926 CASE_CFN_MODF:
12927 CASE_CFN_NEARBYINT:
12928 CASE_CFN_RINT:
12929 CASE_CFN_ROUND:
12930 CASE_CFN_SCALB:
12931 CASE_CFN_SCALBLN:
12932 CASE_CFN_SCALBN:
12933 CASE_CFN_SIGNBIT:
12934 CASE_CFN_SIGNIFICAND:
12935 CASE_CFN_SINH:
12936 CASE_CFN_TANH:
12937 CASE_CFN_TRUNC:
12938 /* True if the 1st argument is nonnegative. */
12941 CASE_CFN_FMAX:
12942 /* True if the 1st OR 2nd arguments are nonnegative. */
12945 CASE_CFN_FMIN:
12946 /* True if the 1st AND 2nd arguments are nonnegative. */
12949 CASE_CFN_COPYSIGN:
12950 /* True if the 2nd argument is nonnegative. */
12953 CASE_CFN_POWI:
12954 /* True if the 1st argument is nonnegative or the second
12955 argument is an even integer. */
12961 CASE_CFN_POW:
12962 /* True if the 1st argument is nonnegative or the second
12963 argument is an even integer valued real. */
12965 {
12966 REAL_VALUE_TYPE c;
12967 HOST_WIDE_INT n;
12972 {
12973 REAL_VALUE_TYPE cint;
12977 }
12978 }
12983 }
12985 }
12987 /* Return true if T is known to be non-negative. If the return
12988 value is based on the assumption that signed overflow is undefined,
12989 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12990 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12992 static bool
12994 {
13000 {
13002 {
13006 /* If the initializer is non-void, then it's a normal expression
13007 that will be assigned to the slot. */
13011 /* Otherwise, the initializer sets the slot in some way. One common
13012 way is an assignment statement at the end of the initializer. */
13014 {
13022 else
13024 }
13030 }
13033 {
13039 arg0,
13040 arg1,
13042 }
13055 }
13056 }
13058 #undef RECURSE
13059 #undef tree_expr_nonnegative_warnv_p
13061 /* Return true if T is known to be non-negative. If the return
13062 value is based on the assumption that signed overflow is undefined,
13063 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13064 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13066 bool
13068 {
13075 {
13097 }
13100 {
13126 }
13127 }
13129 /* Return true if `t' is known to be non-negative. Handle warnings
13130 about undefined signed overflow. */
13132 bool
13134 {
13141 "determining that expression is always "
13143 WARN_STRICT_OVERFLOW_MISC);
13145 }
13148 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13149 For floating point we further ensure that T is not denormal.
13150 Similar logic is present in nonzero_address in rtlanal.h.
13152 If the return value is based on the assumption that signed overflow
13153 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13154 change *STRICT_OVERFLOW_P. */
13156 bool
13159 {
13161 {
13164 strict_overflow_p);
13167 {
13173 strict_overflow_p));
13174 }
13179 strict_overflow_p);
13183 }
13186 }
13188 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13189 For floating point we further ensure that T is not denormal.
13190 Similar logic is present in nonzero_address in rtlanal.h.
13192 If the return value is based on the assumption that signed overflow
13193 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13194 change *STRICT_OVERFLOW_P. */
13196 bool
13198 tree type,
13199 tree op0,
13201 {
13204 {
13208 {
13209 /* With the presence of negative values it is hard
13210 to say something. */
13217 /* One of operands must be positive and the other non-negative. */
13218 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13219 overflows, on a twos-complement machine the sum of two
13220 nonnegative numbers can never be zero. */
13222 strict_overflow_p)
13224 strict_overflow_p));
13225 }
13230 {
13232 strict_overflow_p)
13234 strict_overflow_p))
13235 {
13238 }
13239 }
13248 {
13251 }
13258 {
13262 /* When both operands are nonzero, then MAX must be too. */
13264 strict_overflow_p))
13267 /* MAX where operand 0 is positive is positive. */
13269 strict_overflow_p);
13270 }
13271 /* MAX where operand 1 is positive is positive. */
13276 {
13280 }
13285 strict_overflow_p)
13287 strict_overflow_p));
13291 }
13294 }
13296 /* Return true when T is an address and is known to be nonzero.
13297 For floating point we further ensure that T is not denormal.
13298 Similar logic is present in nonzero_address in rtlanal.h.
13300 If the return value is based on the assumption that signed overflow
13301 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13302 change *STRICT_OVERFLOW_P. */
13304 bool
13306 {
13309 {
13314 {
13326 /* For objects in symbol table check if we know they are non-zero.
13327 Don't do anything for variables and functions before symtab is built;
13328 it is quite possible that they will be declared weak later. */
13333 /* Function local objects are never NULL. */
13340 /* Constants are never weak. */
13345 }
13353 {
13357 }
13362 }
13364 }
13366 #define integer_valued_real_p(X) \
13369 #define RECURSE(X) \
13370 ((integer_valued_real_p) (X, depth + 1))
13372 /* Return true if the floating point result of (CODE OP0) has an
13373 integer value. We also allow +Inf, -Inf and NaN to be considered
13374 integer values. Return false for signaling NaN.
13376 DEPTH is the current nesting depth of the query. */
13378 bool
13380 {
13382 {
13389 CASE_CONVERT:
13390 {
13397 }
13401 }
13403 }
13405 /* Return true if the floating point result of (CODE OP0 OP1) has an
13406 integer value. We also allow +Inf, -Inf and NaN to be considered
13407 integer values. Return false for signaling NaN.
13409 DEPTH is the current nesting depth of the query. */
13411 bool
13413 {
13415 {
13425 }
13427 }
13429 /* Return true if the floating point result of calling FNDECL with arguments
13430 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13431 considered integer values. Return false for signaling NaN. If FNDECL
13432 takes fewer than 2 arguments, the remaining ARGn are null.
13434 DEPTH is the current nesting depth of the query. */
13436 bool
13438 {
13440 {
13441 CASE_CFN_CEIL:
13442 CASE_CFN_FLOOR:
13443 CASE_CFN_NEARBYINT:
13444 CASE_CFN_RINT:
13445 CASE_CFN_ROUND:
13446 CASE_CFN_TRUNC:
13449 CASE_CFN_FMIN:
13450 CASE_CFN_FMAX:
13455 }
13457 }
13459 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13460 has an integer value. We also allow +Inf, -Inf and NaN to be
13461 considered integer values. Return false for signaling NaN.
13463 DEPTH is the current nesting depth of the query. */
13465 bool
13467 {
13469 {
13477 /* Limit the depth of recursion to avoid quadratic behavior.
13478 This is expected to catch almost all occurrences in practice.
13479 If this code misses important cases that unbounded recursion
13480 would not, passes that need this information could be revised
13481 to provide it through dataflow propagation. */
13485 depth));
13489 }
13491 }
13493 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13494 has an integer value. We also allow +Inf, -Inf and NaN to be
13495 considered integer values. Return false for signaling NaN.
13497 DEPTH is the current nesting depth of the query. */
13499 static bool
13501 {
13503 {
13514 }
13516 }
13518 #undef RECURSE
13519 #undef integer_valued_real_p
13521 /* Return true if the floating point expression T has an integer value.
13522 We also allow +Inf, -Inf and NaN to be considered integer values.
13523 Return false for signaling NaN.
13525 DEPTH is the current nesting depth of the query. */
13527 bool
13529 {
13535 {
13551 }
13554 {
13560 {
13569 }
13573 }
13574 }
13576 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13577 attempt to fold the expression to a constant without modifying TYPE,
13578 OP0 or OP1.
13580 If the expression could be simplified to a constant, then return
13581 the constant. If the expression would not be simplified to a
13582 constant, then return NULL_TREE. */
13584 tree
13586 {
13589 }
13591 /* Given the components of a unary expression CODE, TYPE and OP0,
13592 attempt to fold the expression to a constant without modifying
13593 TYPE or OP0.
13595 If the expression could be simplified to a constant, then return
13596 the constant. If the expression would not be simplified to a
13597 constant, then return NULL_TREE. */
13599 tree
13601 {
13604 }
13606 /* If EXP represents referencing an element in a constant string
13607 (either via pointer arithmetic or array indexing), return the
13608 tree representing the value accessed, otherwise return NULL. */
13610 tree
13612 {
13616 {
13618 tree index;
13619 tree string;
13624 else
13625 {
13629 /* Optimize the special-case of a zero lower bound.
13631 We convert the low_bound to sizetype to avoid some problems
13632 with constant folding. (E.g. suppose the lower bound is 1,
13633 and its mode is QI. Without the conversion,l (ARRAY
13634 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13635 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13641 }
13654 }
13656 }
13658 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13659 an integer constant, real, or fixed-point constant.
13661 TYPE is the type of the result. */
13663 static tree
13665 {
13669 {
13671 {
13678 }
13685 {
13686 FIXED_VALUE_TYPE f;
13691 /* Propagate overflow flags. */
13695 }
13699 }
13702 }
13704 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13705 an integer constant or real constant.
13707 TYPE is the type of the result. */
13709 tree
13711 {
13715 {
13717 {
13718 /* If the value is unsigned or non-negative, then the absolute value
13719 is the same as the ordinary value. */
13723 /* If the value is negative, then the absolute value is
13724 its negation. */
13725 else
13726 {
13731 }
13732 }
13738 else
13744 }
13747 }
13749 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13750 constant. TYPE is the type of the result. */
13752 static tree
13754 {
13758 }
13760 /* Given CODE, a relational operator, the target type, TYPE and two
13761 constant operands OP0 and OP1, return the result of the
13762 relational operation. If the result is not a compile time
13763 constant, then return NULL_TREE. */
13765 static tree
13767 {
13770 /* From here on, the only cases we handle are when the result is
13771 known to be a constant. */
13774 {
13778 /* Handle the cases where either operand is a NaN. */
13780 {
13782 {
13810 }
13813 }
13816 }
13819 {
13823 }
13825 /* Handle equality/inequality of complex constants. */
13827 {
13838 else
13840 }
13843 {
13845 {
13846 /* Have vector comparison with scalar boolean result. */
13851 {
13856 }
13860 }
13867 {
13879 }
13882 }
13884 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13886 To compute GT, swap the arguments and do LT.
13887 To compute GE, do LT and invert the result.
13888 To compute LE, swap the arguments, do LT and invert the result.
13889 To compute NE, do EQ and invert the result.
13891 Therefore, the code below must handle only EQ and LT. */
13894 {
13897 }
13899 /* Note that it is safe to invert for real values here because we
13900 have already handled the one case that it matters. */
13904 {
13907 }
13909 /* Compute a result for LT or EQ if args permit;
13910 Otherwise return T. */
13912 {
13915 else
13917 }
13918 else
13924 }
13926 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13927 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13928 itself. */
13930 tree
13932 {
13933 /* If the expression does not have side effects then we don't have to wrap
13934 it with a cleanup point expression. */
13938 /* If the expression is a return, check to see if the expression inside the
13939 return has no side effects or the right hand side of the modify expression
13940 inside the return. If either don't have side effects set we don't need to
13941 wrap the expression in a cleanup point expression. Note we don't check the
13942 left hand side of the modify because it should always be a return decl. */
13944 {
13951 }
13954 }
13956 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13957 of an indirection through OP0, or NULL_TREE if no simplification is
13958 possible. */
13960 tree
13962 {
13964 tree subtype;
13972 {
13975 /* *&CONST_DECL -> to the value of the const decl. */
13978 /* *&p => p; make sure to handle *&"str"[cst] here. */
13980 {
13984 else
13986 }
13987 /* *(foo *)&fooarray => fooarray[0] */
13990 && (!in_gimple_form
13992 {
14002 }
14003 /* *(foo *)&complexfoo => __real__ complexfoo */
14007 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14010 {
14014 }
14015 }
14019 {
14025 {
14026 tree op00type;
14030 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14033 {
14035 unsigned HOST_WIDE_INT max_offset
14040 {
14047 }
14048 }
14049 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14052 {
14056 }
14057 /* ((foo *)&fooarray)[1] => fooarray[1] */
14060 {
14070 }
14071 }
14072 }
14074 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14077 && (!in_gimple_form
14079 {
14080 tree type_domain;
14090 NULL_TREE);
14091 }
14094 }
14096 /* Builds an expression for an indirection through T, simplifying some
14097 cases. */
14099 tree
14101 {
14109 }
14111 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14113 tree
14115 {
14120 else
14122 }
14124 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14125 whose result is ignored. The type of the returned tree need not be
14126 the same as the original expression. */
14128 tree
14130 {
14136 {
14147 else
14153 {
14169 }
14174 }
14175 }
14177 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14179 tree
14181 {
14187 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14188 have to do anything. Only do this when we are not given a const,
14189 because in that case, this check is more expensive than just
14190 doing it. */
14192 {
14197 }
14199 /* If divisor is a power of two, simplify this to bit manipulation. */
14201 {
14203 {
14217 }
14218 else
14219 {
14220 tree t;
14226 }
14227 }
14228 else
14229 {
14234 }
14237 }
14239 /* Likewise, but round down. */
14241 tree
14243 {
14250 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14251 have to do anything. Only do this when we are not given a const,
14252 because in that case, this check is more expensive than just
14253 doing it. */
14255 {
14260 }
14262 /* If divisor is a power of two, simplify this to bit manipulation. */
14264 {
14265 tree t;
14269 }
14270 else
14271 {
14276 }
14279 }
14281 /* Returns the pointer to the base of the object addressed by EXP and
14282 extracts the information about the offset of the access, storing it
14283 to PBITPOS and POFFSET. */
14285 static tree
14288 {
14289 tree core;
14290 machine_mode mode;
14292 HOST_WIDE_INT bitsize;
14296 {
14301 }
14302 else
14303 {
14307 }
14310 }
14312 /* Returns true if addresses of E1 and E2 differ by a constant, false
14313 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14315 bool
14317 {
14331 {
14341 }
14343 {
14344 /* If only one of the offsets is non-constant, the difference cannot
14345 be a constant. */
14347 }
14348 else
14353 }
14355 /* Return OFF converted to a pointer offset type suitable as offset for
14356 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14357 tree
14359 {
14361 }
14363 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14364 tree
14366 {
14369 }
14371 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14372 tree
14374 {
14377 }
14379 /* Return a char pointer for a C string if it is a string constant
14380 or sum of string constant and integer constant. */
14384 {
14385 tree offset_node;
14398 }
14400 #if CHECKING_P
14404 /* Helper functions for writing tests of folding trees. */
14406 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14408 static void
14410 tree constant)
14411 {
14413 }
14415 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14416 wrapping WRAPPED_EXPR. */
14418 static void
14420 tree wrapped_expr)
14421 {
14426 }
14428 /* Verify that various arithmetic binary operations are folded
14429 correctly. */
14431 static void
14433 {
14439 /* Addition. */
14440 /* 1 <-- (0 + 1) */
14442 one);
14444 one);
14446 /* (nonlvalue)x <-- (x + 0) */
14448 x);
14450 /* Subtraction. */
14451 /* 0 <-- (x - x) */
14453 zero);
14455 x);
14457 /* Multiplication. */
14458 /* 0 <-- (x * 0) */
14460 zero);
14462 /* (nonlvalue)x <-- (x * 1) */
14464 x);
14465 }
14467 /* Run all of the selftests within this file. */
14469 void
14471 {
14473 }