| blob | 696b4a6996fa735d9bd794549f6cf668a34a1775 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
80 #ifndef LOAD_EXTEND_OP
81 #define LOAD_EXTEND_OP(M) UNKNOWN
82 #endif
84 /* Nonzero if we are folding constants inside an initializer; zero
85 otherwise. */
88 /* The following constants represent a bit based encoding of GCC's
89 comparison operators. This encoding simplifies transformations
90 on relational comparison operators, such as AND and OR. */
108 };
125 HOST_WIDE_INT *,
154 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
155 Otherwise, return LOC. */
157 static location_t
159 {
162 }
164 /* Similar to protected_set_expr_location, but never modify x in place,
165 if location can and needs to be set, unshare it. */
169 {
175 {
178 }
180 }
181 \f
182 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
183 division and returns the quotient. Otherwise returns
184 NULL_TREE. */
186 tree
188 {
189 widest_int quo;
196 }
197 \f
198 /* This is nonzero if we should defer warnings about undefined
199 overflow. This facility exists because these warnings are a
200 special case. The code to estimate loop iterations does not want
201 to issue any warnings, since it works with expressions which do not
202 occur in user code. Various bits of cleanup code call fold(), but
203 only use the result if it has certain characteristics (e.g., is a
204 constant); that code only wants to issue a warning if the result is
205 used. */
209 /* If a warning about undefined overflow is deferred, this is the
210 warning. Note that this may cause us to turn two warnings into
211 one, but that is fine since it is sufficient to only give one
212 warning per expression. */
216 /* If a warning about undefined overflow is deferred, this is the
217 level at which the warning should be emitted. */
221 /* Start deferring overflow warnings. We could use a stack here to
222 permit nested calls, but at present it is not necessary. */
224 void
226 {
228 }
230 /* Stop deferring overflow warnings. If there is a pending warning,
231 and ISSUE is true, then issue the warning if appropriate. STMT is
232 the statement with which the warning should be associated (used for
233 location information); STMT may be NULL. CODE is the level of the
234 warning--a warn_strict_overflow_code value. This function will use
235 the smaller of CODE and the deferred code when deciding whether to
236 issue the warning. CODE may be zero to mean to always use the
237 deferred code. */
239 void
241 {
243 location_t locus;
248 {
254 }
265 /* Use the smallest code level when deciding to issue the
266 warning. */
275 else
278 }
280 /* Stop deferring overflow warnings, ignoring any deferred
281 warnings. */
283 void
285 {
287 }
289 /* Whether we are deferring overflow warnings. */
291 bool
293 {
295 }
297 /* This is called when we fold something based on the fact that signed
298 overflow is undefined. */
300 static void
302 {
304 {
307 {
310 }
311 }
314 }
315 \f
316 /* Return true if the built-in mathematical function specified by CODE
317 is odd, i.e. -f(x) == f(-x). */
319 bool
321 {
323 {
324 CASE_CFN_ASIN:
325 CASE_CFN_ASINH:
326 CASE_CFN_ATAN:
327 CASE_CFN_ATANH:
328 CASE_CFN_CASIN:
329 CASE_CFN_CASINH:
330 CASE_CFN_CATAN:
331 CASE_CFN_CATANH:
332 CASE_CFN_CBRT:
333 CASE_CFN_CPROJ:
334 CASE_CFN_CSIN:
335 CASE_CFN_CSINH:
336 CASE_CFN_CTAN:
337 CASE_CFN_CTANH:
338 CASE_CFN_ERF:
339 CASE_CFN_LLROUND:
340 CASE_CFN_LROUND:
341 CASE_CFN_ROUND:
342 CASE_CFN_SIN:
343 CASE_CFN_SINH:
344 CASE_CFN_TAN:
345 CASE_CFN_TANH:
346 CASE_CFN_TRUNC:
349 CASE_CFN_LLRINT:
350 CASE_CFN_LRINT:
351 CASE_CFN_NEARBYINT:
352 CASE_CFN_RINT:
357 }
359 }
361 /* Check whether we may negate an integer constant T without causing
362 overflow. */
364 bool
366 {
367 tree type;
376 }
378 /* Determine whether an expression T can be cheaply negated using
379 the function negate_expr without introducing undefined overflow. */
381 static bool
383 {
384 tree type;
393 {
398 /* Check that -CST will not overflow type. */
411 /* We want to canonicalize to positive real constants. Pretend
412 that only negative ones can be easily negated. */
420 {
431 }
446 /* -(A + B) -> (-B) - A. */
451 /* -(A + B) -> (-A) - B. */
455 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
466 /* INT_MIN/n * n doesn't overflow while negating one operand it does
467 if n is a power of two. */
476 /* Fall through. */
491 /* In general we can't negate B in A / B, because if A is INT_MIN and
492 B is 1, we may turn this into INT_MIN / -1 which is undefined
493 and actually traps on some architectures. */
502 /* Negate -((double)float) as (double)(-float). */
504 {
508 }
512 /* Negate -f(x) as f(-x). */
518 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
520 {
524 }
529 }
531 }
533 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
534 simplification is possible.
535 If negate_expr_p would return true for T, NULL_TREE will never be
536 returned. */
538 static tree
540 {
542 tree tem;
545 {
546 /* Convert - (~A) to A + 1. */
572 {
577 }
581 {
586 {
590 }
593 }
616 {
617 /* -(A + B) -> (-B) - A. */
621 {
625 }
627 /* -(A + B) -> (-A) - B. */
629 {
633 }
634 }
638 /* - (A - B) -> B - A */
650 /* Fall through. */
654 {
663 }
675 /* In general we can't negate B in A / B, because if A is INT_MIN and
676 B is 1, we may turn this into INT_MIN / -1 which is undefined
677 and actually traps on some architectures. */
689 /* Convert -((double)float) into (double)(-float). */
691 {
695 }
699 /* Negate -f(x) as f(-x). */
702 {
708 }
712 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
714 {
717 {
724 }
725 }
730 }
733 }
735 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
736 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
737 return NULL_TREE. */
739 static tree
741 {
743 location_t loc;
756 }
757 \f
758 /* Split a tree IN into a constant, literal and variable parts that could be
759 combined with CODE to make IN. "constant" means an expression with
760 TREE_CONSTANT but that isn't an actual constant. CODE must be a
761 commutative arithmetic operation. Store the constant part into *CONP,
762 the literal in *LITP and return the variable part. If a part isn't
763 present, set it to null. If the tree does not decompose in this way,
764 return the entire tree as the variable part and the other parts as null.
766 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
767 case, we negate an operand that was subtracted. Except if it is a
768 literal for which we use *MINUS_LITP instead.
770 If NEGATE_P is true, we are negating all of IN, again except a literal
771 for which we use *MINUS_LITP instead. If a variable part is of pointer
772 type, it is negated after converting to TYPE. This prevents us from
773 generating illegal MINUS pointer expression. LOC is the location of
774 the converted variable part.
776 If IN is itself a literal or constant, return it as appropriate.
778 Note that we do not guarantee that any of the three values will be the
779 same type as IN, but they will have the same signedness and mode. */
781 static tree
784 {
791 /* Strip any conversions that don't change the machine mode or signedness. */
800 /* We can associate addition and subtraction together (even
801 though the C standard doesn't say so) for integers because
802 the value is not affected. For reals, the value might be
803 affected, so we can't. */
806 {
812 /* First see if either of the operands is a literal, then a constant. */
825 /* If we haven't dealt with either operand, this is not a case we can
826 decompose. Otherwise, VAR is either of the ones remaining, if any. */
831 else
834 /* Now do any needed negations. */
840 {
841 /* Convert to TYPE before negating a pointer type expr. */
845 }
846 }
849 {
850 /* -X - 1 is folded to ~X, undo that here. */
853 }
856 else
860 {
866 /* Convert to TYPE before negating a pointer type expr. */
870 }
873 }
875 /* Re-associate trees split by the above function. T1 and T2 are
876 either expressions to associate or null. Return the new
877 expression, if any. LOC is the location of the new expression. If
878 we build an operation, do it in TYPE and with CODE. */
880 static tree
882 {
888 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
889 try to fold this since we will have infinite recursion. But do
890 deal with any NEGATE_EXPRs. */
893 {
895 {
908 }
910 {
913 }
917 }
921 }
922 \f
923 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
924 for use in int_const_binop, size_binop and size_diffop. */
926 static bool
928 {
935 {
944 }
949 }
952 /* Combine two integer constants ARG1 and ARG2 under operation CODE
953 to produce a new constant. Return NULL_TREE if we don't know how
954 to evaluate CODE at compile-time. */
956 static tree
959 {
960 wide_int res;
961 tree t;
970 {
986 {
990 else
992 }
995 /* It's unclear from the C standard whether shifts can overflow.
996 The following code ignores overflow; perhaps a C standard
997 interpretation ruling is needed. */
999 else
1006 {
1010 else
1012 }
1016 else
1095 }
1103 }
1105 tree
1107 {
1109 }
1111 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1112 constant. We assume ARG1 and ARG2 have the same data type, or at least
1113 are the same kind of constant and the same machine mode. Return zero if
1114 combining the constants is not allowed in the current operating mode. */
1116 static tree
1118 {
1119 /* Sanity check for the recursive cases. */
1127 {
1133 }
1136 {
1137 machine_mode mode;
1138 REAL_VALUE_TYPE d1;
1139 REAL_VALUE_TYPE d2;
1140 REAL_VALUE_TYPE value;
1141 REAL_VALUE_TYPE result;
1145 /* The following codes are handled by real_arithmetic. */
1147 {
1158 }
1166 /* Don't perform operation if we honor signaling NaNs and
1167 either operand is a signaling NaN. */
1173 /* Don't perform operation if it would raise a division
1174 by zero exception. */
1180 /* If either operand is a NaN, just return it. Otherwise, set up
1181 for floating-point trap; we return an overflow. */
1183 {
1184 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1185 is off. */
1189 }
1191 {
1192 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1193 is off. */
1197 }
1202 /* Don't constant fold this floating point operation if
1203 the result has overflowed and flag_trapping_math. */
1211 /* Don't constant fold this floating point operation if the
1212 result may dependent upon the run-time rounding mode and
1213 flag_rounding_math is set, or if GCC's software emulation
1214 is unable to accurately represent the result. */
1224 }
1227 {
1228 FIXED_VALUE_TYPE f1;
1229 FIXED_VALUE_TYPE f2;
1230 FIXED_VALUE_TYPE result;
1235 /* The following codes are handled by fixed_arithmetic. */
1237 {
1249 {
1256 }
1261 }
1268 /* Propagate overflow flags. */
1272 }
1275 {
1284 {
1295 mpc_mul);
1309 mpc_div);
1310 /* Fallthru ... */
1316 {
1317 /* Keep this algorithm in sync with
1318 tree-complex.c:expand_complex_div_straight().
1320 Expand complex division to scalars, straightforward algorithm.
1321 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1322 t = br*br + bi*bi
1323 */
1324 tree magsquared
1328 tree t1
1332 tree t2
1339 }
1340 else
1341 {
1342 /* Keep this algorithm in sync with
1343 tree-complex.c:expand_complex_div_wide().
1345 Expand complex division to scalars, modified algorithm to minimize
1346 overflow with wide input ranges. */
1352 {
1353 /* In the TRUE branch, we compute
1354 ratio = br/bi;
1355 div = (br * ratio) + bi;
1356 tr = (ar * ratio) + ai;
1357 ti = (ai * ratio) - ar;
1358 tr = tr / div;
1359 ti = ti / div; */
1370 }
1371 else
1372 {
1373 /* In the FALSE branch, we compute
1374 ratio = d/c;
1375 divisor = (d * ratio) + c;
1376 tr = (b * ratio) + a;
1377 ti = b - (a * ratio);
1378 tr = tr / div;
1379 ti = ti / div; */
1391 }
1392 }
1397 }
1401 }
1405 {
1411 {
1417 /* It is possible that const_binop cannot handle the given
1418 code and return NULL_TREE */
1421 }
1424 }
1426 /* Shifts allow a scalar offset for a vector. */
1429 {
1435 {
1440 /* It is possible that const_binop cannot handle the given
1441 code and return NULL_TREE. */
1444 }
1447 }
1449 }
1451 /* Overload that adds a TYPE parameter to be able to dispatch
1452 to fold_relational_const. */
1454 tree
1456 {
1460 /* ??? Until we make the const_binop worker take the type of the
1461 result as argument put those cases that need it here. */
1463 {
1474 {
1490 {
1496 }
1499 }
1505 {
1530 {
1543 }
1546 }
1549 }
1554 /* Make sure type and arg0 have the same saturating flag. */
1559 }
1561 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1562 Return zero if computing the constants is not possible. */
1564 tree
1566 {
1567 /* Don't perform the operation, other than NEGATE and ABS, if
1568 flag_signaling_nans is on and the operand is a signaling NaN. */
1577 {
1578 CASE_CONVERT:
1585 /* If the source address is 0, and the source address space
1586 cannot have a valid object at 0, fold to dest type null. */
1597 {
1598 /* Can't call fold_negate_const directly here as that doesn't
1599 handle all cases and we might not be able to negate some
1600 constants. */
1605 }
1614 {
1618 }
1624 /* Perform BIT_NOT_EXPR on each element individually. */
1626 {
1628 tree elem;
1633 {
1639 }
1642 }
1664 {
1683 else
1687 {
1691 }
1694 }
1699 {
1713 {
1718 }
1721 {
1725 }
1728 }
1732 }
1735 }
1737 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1738 indicates which particular sizetype to create. */
1740 tree
1742 {
1744 }
1745 \f
1746 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1747 is a tree code. The type of the result is taken from the operands.
1748 Both must be equivalent integer types, ala int_binop_types_match_p.
1749 If the operands are constant, so is the result. */
1751 tree
1753 {
1762 /* Handle the special case of two integer constants faster. */
1764 {
1765 /* And some specific cases even faster than that. */
1767 {
1772 }
1774 {
1777 }
1779 {
1782 }
1784 /* Handle general case of two integer constants. For sizetype
1785 constant calculations we always want to know about overflow,
1786 even in the unsigned case. */
1788 }
1791 }
1793 /* Given two values, either both of sizetype or both of bitsizetype,
1794 compute the difference between the two values. Return the value
1795 in signed type corresponding to the type of the operands. */
1797 tree
1799 {
1801 tree ctype;
1806 /* If the type is already signed, just do the simple thing. */
1814 else
1817 /* If either operand is not a constant, do the conversions to the signed
1818 type and subtract. The hardware will do the right thing with any
1819 overflow in the subtraction. */
1825 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1826 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1827 overflow) and negate (which can't either). Special-case a result
1828 of zero while we're here. */
1834 else
1838 MINUS_EXPR,
1840 }
1841 \f
1842 /* A subroutine of fold_convert_const handling conversions of an
1843 INTEGER_CST to another integer type. */
1845 static tree
1847 {
1848 /* Given an integer constant, make new constant with new type,
1849 appropriately sign-extended or truncated. Use widest_int
1850 so that any extension is done according ARG1's type. */
1854 }
1856 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1857 to an integer type. */
1859 static tree
1861 {
1863 tree t;
1865 /* The following code implements the floating point to integer
1866 conversion rules required by the Java Language Specification,
1867 that IEEE NaNs are mapped to zero and values that overflow
1868 the target precision saturate, i.e. values greater than
1869 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1870 are mapped to INT_MIN. These semantics are allowed by the
1871 C and C++ standards that simply state that the behavior of
1872 FP-to-integer conversion is unspecified upon overflow. */
1874 wide_int val;
1875 REAL_VALUE_TYPE r;
1879 {
1886 }
1888 /* If R is NaN, return zero and show we have an overflow. */
1890 {
1893 }
1895 /* See if R is less than the lower bound or greater than the
1896 upper bound. */
1899 {
1903 {
1906 }
1907 }
1910 {
1913 {
1916 {
1919 }
1920 }
1921 }
1928 }
1930 /* A subroutine of fold_convert_const handling conversions of a
1931 FIXED_CST to an integer type. */
1933 static tree
1935 {
1936 tree t;
1940 /* Right shift FIXED_CST to temp by fbit. */
1944 {
1946 HOST_BITS_PER_DOUBLE_INT,
1949 /* Left shift temp to temp_trunc by fbit. */
1951 HOST_BITS_PER_DOUBLE_INT,
1953 }
1954 else
1955 {
1958 }
1960 /* If FIXED_CST is negative, we need to round the value toward 0.
1961 By checking if the fractional bits are not zero to add 1 to temp. */
1967 /* Given a fixed-point constant, make new constant with new type,
1968 appropriately sign-extended or truncated. */
1976 }
1978 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1979 to another floating point type. */
1981 static tree
1983 {
1984 REAL_VALUE_TYPE value;
1985 tree t;
1987 /* Don't perform the operation if flag_signaling_nans is on
1988 and the operand is a signaling NaN. */
1996 /* If converting an infinity or NAN to a representation that doesn't
1997 have one, set the overflow bit so that we can produce some kind of
1998 error message at the appropriate point if necessary. It's not the
1999 most user-friendly message, but it's better than nothing. */
2006 /* Regular overflow, conversion produced an infinity in a mode that
2007 can't represent them. */
2012 else
2015 }
2017 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2018 to a floating point type. */
2020 static tree
2022 {
2023 REAL_VALUE_TYPE value;
2024 tree t;
2031 }
2033 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2034 to another fixed-point type. */
2036 static tree
2038 {
2039 FIXED_VALUE_TYPE value;
2040 tree t;
2047 /* Propagate overflow flags. */
2051 }
2053 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2054 to a fixed-point type. */
2056 static tree
2058 {
2059 FIXED_VALUE_TYPE value;
2060 tree t;
2062 double_int di;
2069 else
2077 /* Propagate overflow flags. */
2081 }
2083 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2084 to a fixed-point type. */
2086 static tree
2088 {
2089 FIXED_VALUE_TYPE value;
2090 tree t;
2098 /* Propagate overflow flags. */
2102 }
2104 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2105 type TYPE. If no simplification can be done return NULL_TREE. */
2107 static tree
2109 {
2115 {
2122 }
2124 {
2131 }
2133 {
2140 }
2142 {
2145 {
2150 {
2156 }
2158 }
2159 }
2161 }
2163 /* Construct a vector of zero elements of vector type TYPE. */
2165 static tree
2167 {
2168 tree t;
2172 }
2174 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2176 bool
2178 {
2193 {
2209 }
2210 }
2212 /* Convert expression ARG to type TYPE. Used by the middle-end for
2213 simple conversions in preference to calling the front-end's convert. */
2215 tree
2217 {
2219 tree tem;
2230 {
2233 /* Handle conversions between pointers to different address spaces. */
2238 /* fall through */
2243 {
2247 }
2261 {
2265 }
2267 {
2271 }
2273 {
2277 }
2280 {
2298 }
2303 {
2307 }
2310 {
2324 }
2328 {
2337 integer_zero_node));
2339 {
2343 {
2349 }
2357 }
2361 }
2379 }
2380 fold_convert_exit:
2383 }
2384 \f
2385 /* Return false if expr can be assumed not to be an lvalue, true
2386 otherwise. */
2388 static bool
2390 {
2391 /* We only need to wrap lvalue tree codes. */
2393 {
2424 /* Assume the worst for front-end tree codes. */
2428 }
2431 }
2433 /* Return an expr equal to X but certainly not valid as an lvalue. */
2435 tree
2437 {
2438 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2439 us. */
2446 }
2448 /* When pedantic, return an expr equal to X but certainly not valid as a
2449 pedantic lvalue. Otherwise, return X. */
2451 static tree
2453 {
2455 }
2456 \f
2457 /* Given a tree comparison code, return the code that is the logical inverse.
2458 It is generally not safe to do this for floating-point comparisons, except
2459 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2460 ERROR_MARK in this case. */
2462 enum tree_code
2464 {
2470 {
2501 }
2502 }
2504 /* Similar, but return the comparison that results if the operands are
2505 swapped. This is safe for floating-point. */
2507 enum tree_code
2509 {
2511 {
2537 }
2538 }
2541 /* Convert a comparison tree code from an enum tree_code representation
2542 into a compcode bit-based encoding. This function is the inverse of
2543 compcode_to_comparison. */
2545 static enum comparison_code
2547 {
2549 {
2580 }
2581 }
2583 /* Convert a compcode bit-based encoding of a comparison operator back
2584 to GCC's enum tree_code representation. This function is the
2585 inverse of comparison_to_compcode. */
2587 static enum tree_code
2589 {
2591 {
2622 }
2623 }
2625 /* Return a tree for the comparison which is the combination of
2626 doing the AND or OR (depending on CODE) of the two operations LCODE
2627 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2628 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2629 if this makes the transformation invalid. */
2631 tree
2636 {
2643 {
2654 }
2657 {
2658 /* Eliminate unordered comparisons, as well as LTGT and ORD
2659 which are not used unless the mode has NaNs. */
2665 }
2667 {
2668 /* Check that the original operation and the optimized ones will trap
2669 under the same condition. */
2680 /* In a short-circuited boolean expression the LHS might be
2681 such that the RHS, if evaluated, will never trap. For
2682 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2683 if neither x nor y is NaN. (This is a mixed blessing: for
2684 example, the expression above will never trap, hence
2685 optimizing it to x < y would be invalid). */
2690 /* If the comparison was short-circuited, and only the RHS
2691 trapped, we may now generate a spurious trap. */
2696 /* If we changed the conditions that cause a trap, we lose. */
2699 }
2705 else
2706 {
2711 }
2712 }
2713 \f
2714 /* Return nonzero if two operands (typically of the same tree node)
2715 are necessarily equal. FLAGS modifies behavior as follows:
2717 If OEP_ONLY_CONST is set, only return nonzero for constants.
2718 This function tests whether the operands are indistinguishable;
2719 it does not test whether they are equal using C's == operation.
2720 The distinction is important for IEEE floating point, because
2721 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2722 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2724 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2725 even though it may hold multiple values during a function.
2726 This is because a GCC tree node guarantees that nothing else is
2727 executed between the evaluation of its "operands" (which may often
2728 be evaluated in arbitrary order). Hence if the operands themselves
2729 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2730 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2731 unset means assuming isochronic (or instantaneous) tree equivalence.
2732 Unless comparing arbitrary expression trees, such as from different
2733 statements, this flag can usually be left unset.
2735 If OEP_PURE_SAME is set, then pure functions with identical arguments
2736 are considered the same. It is used when the caller has other ways
2737 to ensure that global memory is unchanged in between.
2739 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2740 not values of expressions.
2742 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2743 any operand with side effect. This is unnecesarily conservative in the
2744 case we know that arg0 and arg1 are in disjoint code paths (such as in
2745 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2746 addresses with TREE_CONSTANT flag set so we know that &var == &var
2747 even if var is volatile. */
2749 int
2751 {
2752 /* If either is ERROR_MARK, they aren't equal. */
2758 /* Similar, if either does not have a type (like a released SSA name),
2759 they aren't equal. */
2763 /* We cannot consider pointers to different address space equal. */
2770 /* Check equality of integer constants before bailing out due to
2771 precision differences. */
2773 {
2774 /* Address of INTEGER_CST is not defined; check that we did not forget
2775 to drop the OEP_ADDRESS_OF flags. */
2778 }
2781 {
2782 /* If both types don't have the same signedness, then we can't consider
2783 them equal. We must check this before the STRIP_NOPS calls
2784 because they may change the signedness of the arguments. As pointers
2785 strictly don't have a signedness, require either two pointers or
2786 two non-pointers as well. */
2792 /* If both types don't have the same precision, then it is not safe
2793 to strip NOPs. */
2800 }
2801 #if 0
2802 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2803 sanity check once the issue is solved. */
2804 else
2805 /* Addresses of conversions and SSA_NAMEs (and many other things)
2806 are not defined. Check that we did not forget to drop the
2807 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2810 #endif
2812 /* In case both args are comparisons but with different comparison
2813 code, try to swap the comparison operands of one arg to produce
2814 a match and compare that variant. */
2818 {
2826 }
2829 {
2830 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2832 ;
2834 {
2835 /* If we are interested in comparing addresses ignore
2836 MEM_REF wrappings of the base that can appear just for
2837 TBAA reasons. */
2851 }
2852 else
2854 }
2856 /* When not checking adddresses, this is needed for conversions and for
2857 COMPONENT_REF. Might as well play it safe and always test this. */
2864 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2865 We don't care about side effects in that case because the SAVE_EXPR
2866 takes care of that for us. In all other cases, two expressions are
2867 equal if they have no side effects. If we have two identical
2868 expressions with side effects that should be treated the same due
2869 to the only side effects being identical SAVE_EXPR's, that will
2870 be detected in the recursive calls below.
2871 If we are taking an invariant address of two identical objects
2872 they are necessarily equal as well. */
2879 /* Next handle constant cases, those for which we can return 1 even
2880 if ONLY_CONST is set. */
2883 {
2897 {
2898 /* If we do not distinguish between signed and unsigned zero,
2899 consider them equal. */
2902 }
2906 {
2913 {
2917 }
2919 }
2923 flags)
2925 flags));
2936 flags | OEP_ADDRESS_OF
2939 /* In GIMPLE empty constructors are allowed in initializers of
2940 aggregates. */
2945 }
2950 /* Define macros to test an operand from arg0 and arg1 for equality and a
2951 variant that allows null and views null as being different from any
2952 non-null value. In the latter case, if either is null, the both
2953 must be; otherwise, do the normal comparison. */
2954 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2955 TREE_OPERAND (arg1, N), flags)
2957 #define OP_SAME_WITH_NULL(N) \
2958 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2959 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2962 {
2964 /* Two conversions are equal only if signedness and modes match. */
2966 {
2967 CASE_CONVERT:
2975 }
2985 /* For commutative ops, allow the other order. */
2993 /* If either of the pointer (or reference) expressions we are
2994 dereferencing contain a side effect, these cannot be equal,
2995 but their addresses can be. */
3002 {
3012 /* Require the same offset. */
3018 /* Fallthru. */
3026 {
3027 /* Require equal access sizes */
3033 flags)))
3035 /* Verify that access happens in similar types. */
3038 /* Verify that accesses are TBAA compatible. */
3047 /* Verify that alignment is compatible. */
3051 }
3054 /* TARGET_MEM_REF require equal extra operands. */
3065 /* Compare the array index by value if it is constant first as we
3066 may have different types but same value here. */
3072 /* Compare low bound and element size as with OEP_ADDRESS_OF
3073 we have to account for the offset of the ref. */
3078 array_ref_low_bound
3082 array_ref_element_size
3084 flags))));
3087 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3088 may be NULL when we're called to compare MEM_EXPRs. */
3103 }
3107 {
3109 /* Be sure we pass right ADDRESS_OF flag. */
3127 /* The multiplcation operands are commutative. */
3128 /* FALLTHRU */
3136 /* Otherwise take into account this is a commutative operation. */
3154 }
3158 {
3162 /* If not both CALL_EXPRs are either internal or normal function
3163 functions, then they are not equal. */
3166 {
3167 /* If the CALL_EXPRs call different internal functions, then they
3168 are not equal. */
3171 }
3172 else
3173 {
3174 /* If the CALL_EXPRs call different functions, then they are not
3175 equal. */
3177 flags))
3179 }
3181 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3182 {
3186 else
3190 }
3192 /* Now see if all the arguments are the same. */
3193 {
3204 /* If we get here and both argument lists are exhausted
3205 then the CALL_EXPRs are equal. */
3207 }
3210 }
3213 /* Consider __builtin_sqrt equal to sqrt. */
3221 {
3222 /* In GIMPLE constructors are used only to build vectors from
3223 elements. Individual elements in the constructor must be
3224 indexed in increasing order and form an initial sequence.
3226 We make no effort to compare constructors in generic.
3227 (see sem_variable::equals in ipa-icf which can do so for
3228 constants). */
3233 /* Be sure that vectors constructed have the same representation.
3234 We only tested element precision and modes to match.
3235 Vectors may be BLKmode and thus also check that the number of
3236 parts match. */
3249 {
3254 /* In GIMPLE the indexes can be either NULL or matching i.
3255 Double check this so we won't get false
3256 positives for GENERIC. */
3264 }
3266 }
3271 }
3273 #undef OP_SAME
3274 #undef OP_SAME_WITH_NULL
3275 }
3276 \f
3277 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3278 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3280 When in doubt, return 0. */
3282 static int
3284 {
3296 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3297 and see if the inner values are the same. This removes any
3298 signedness comparison, which doesn't matter here. */
3305 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3306 actual comparison operand, ARG0.
3308 First throw away any conversions to wider types
3309 already present in the operands. */
3318 {
3321 /* Make sure shorter operand is extended the right way
3322 to match the longer operand. */
3328 }
3331 }
3332 \f
3333 /* See if ARG is an expression that is either a comparison or is performing
3334 arithmetic on comparisons. The comparisons must only be comparing
3335 two different values, which will be stored in *CVAL1 and *CVAL2; if
3336 they are nonzero it means that some operands have already been found.
3337 No variables may be used anywhere else in the expression except in the
3338 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3339 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3341 If this is true, return 1. Otherwise, return zero. */
3343 static int
3345 {
3349 /* We can handle some of the tcc_expression cases here. */
3359 {
3360 /* If we've already found a CVAL1 or CVAL2, this expression is
3361 two complex to handle. */
3367 }
3370 {
3393 /* First see if we can handle the first operand, then the second. For
3394 the second operand, we know *CVAL1 can't be zero. It must be that
3395 one side of the comparison is each of the values; test for the
3396 case where this isn't true by failing if the two operands
3397 are the same. */
3406 ;
3410 ;
3411 else
3415 ;
3419 ;
3420 else
3427 }
3428 }
3429 \f
3430 /* ARG is a tree that is known to contain just arithmetic operations and
3431 comparisons. Evaluate the operations in the tree substituting NEW0 for
3432 any occurrence of OLD0 as an operand of a comparison and likewise for
3433 NEW1 and OLD1. */
3435 static tree
3438 {
3443 /* We can handle some of the tcc_expression cases here. */
3451 {
3466 {
3485 }
3486 /* Fall through - ??? */
3489 {
3493 /* We need to check both for exact equality and tree equality. The
3494 former will be true if the operand has a side-effect. In that
3495 case, we know the operand occurred exactly once. */
3508 }
3512 }
3513 }
3514 \f
3515 /* Return a tree for the case when the result of an expression is RESULT
3516 converted to TYPE and OMITTED was previously an operand of the expression
3517 but is now not needed (e.g., we folded OMITTED * 0).
3519 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3520 the conversion of RESULT to TYPE. */
3522 tree
3524 {
3527 /* If the resulting operand is an empty statement, just return the omitted
3528 statement casted to void. */
3538 }
3540 /* Return a tree for the case when the result of an expression is RESULT
3541 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3542 of the expression but are now not needed.
3544 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3545 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3546 evaluated before OMITTED2. Otherwise, if neither has side effects,
3547 just do the conversion of RESULT to TYPE. */
3549 tree
3552 {
3561 }
3563 \f
3564 /* Return a simplified tree node for the truth-negation of ARG. This
3565 never alters ARG itself. We assume that ARG is an operation that
3566 returns a truth value (0 or 1).
3568 FIXME: one would think we would fold the result, but it causes
3569 problems with the dominator optimizer. */
3571 static tree
3573 {
3578 /* If this is a comparison, we can simply invert it, except for
3579 floating-point non-equality comparisons, in which case we just
3580 enclose a TRUTH_NOT_EXPR around what we have. */
3583 {
3586 && flag_trapping_math
3600 }
3603 {
3622 /* Here we can invert either operand. We invert the first operand
3623 unless the second operand is a TRUTH_NOT_EXPR in which case our
3624 result is the XOR of the first operand with the inside of the
3625 negation of the second operand. */
3630 else
3653 {
3660 /* A COND_EXPR may have a throw as one operand, which
3661 then has void type. Just leave void operands
3662 as they are. */
3668 }
3680 CASE_CONVERT:
3684 /* ... fall through ... */
3706 }
3707 }
3709 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3710 assume that ARG is an operation that returns a truth value (0 or 1
3711 for scalars, 0 or -1 for vectors). Return the folded expression if
3712 folding is successful. Otherwise, return NULL_TREE. */
3714 static tree
3716 {
3719 ? BIT_NOT_EXPR
3722 }
3724 /* Return a simplified tree node for the truth-negation of ARG. This
3725 never alters ARG itself. We assume that ARG is an operation that
3726 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3728 tree
3730 {
3736 ? BIT_NOT_EXPR
3739 }
3741 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3742 with code CODE. This optimization is unsafe. */
3743 static tree
3746 {
3750 /* (A / C) +- (B / C) -> (A +- B) / C. */
3760 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3765 {
3777 }
3780 }
3781 \f
3782 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3783 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3784 and uses reverse storage order if REVERSEP is nonzero. */
3786 static tree
3790 {
3794 {
3801 }
3816 }
3818 /* Optimize a bit-field compare.
3820 There are two cases: First is a compare against a constant and the
3821 second is a comparison of two items where the fields are at the same
3822 bit position relative to the start of a chunk (byte, halfword, word)
3823 large enough to contain it. In these cases we can avoid the shift
3824 implicit in bitfield extractions.
3826 For constants, we emit a compare of the shifted constant with the
3827 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3828 compared. For two fields at the same position, we do the ANDs with the
3829 similar mask and compare the result of the ANDs.
3831 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3832 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3833 are the left and right operands of the comparison, respectively.
3835 If the optimization described above can be done, we return the resulting
3836 tree. Otherwise we return zero. */
3838 static tree
3841 {
3844 tree unsigned_type;
3851 tree mask;
3852 tree offset;
3854 /* Get all the information about the extractions being done. If the bit size
3855 if the same as the size of the underlying object, we aren't doing an
3856 extraction at all and so can do nothing. We also don't want to
3857 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3858 then will no longer be able to replace it. */
3867 else
3868 {
3869 /* If this is not a constant, we can only do something if bit positions,
3870 sizes, signedness and storage order are the same. */
3871 rinner
3879 }
3881 /* See if we can find a mode to refer to this field. We should be able to,
3882 but fail if we can't. */
3891 /* Set signed and unsigned types of the precision of this mode for the
3892 shifts below. */
3895 /* Compute the bit position and size for the new reference and our offset
3896 within it. If the new reference is the same size as the original, we
3897 won't optimize anything, so return zero. */
3907 /* Make the mask to be used against the extracted field. */
3914 /* If not comparing with constant, just rework the comparison
3915 and return. */
3919 unsigned_type,
3922 mask),
3925 unsigned_type,
3928 mask));
3930 /* Otherwise, we are handling the constant case. See if the constant is too
3931 big for the field. Warn and return a tree for 0 (false) if so. We do
3932 this not only for its own sake, but to avoid having to test for this
3933 error case below. If we didn't, we might generate wrong code.
3935 For unsigned fields, the constant shifted right by the field length should
3936 be all zero. For signed fields, the high-order bits should agree with
3937 the sign bit. */
3940 {
3942 {
3946 }
3947 }
3948 else
3949 {
3952 {
3956 }
3957 }
3959 /* Single-bit compares should always be against zero. */
3961 {
3964 }
3966 /* Make a new bitfield reference, shift the constant over the
3967 appropriate number of bits and mask it with the computed mask
3968 (in case this was a signed field). If we changed it, make a new one. */
3970 lreversep);
3976 mask);
3981 }
3982 \f
3983 /* Subroutine for fold_truth_andor_1: decode a field reference.
3985 If EXP is a comparison reference, we return the innermost reference.
3987 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3988 set to the starting bit number.
3990 If the innermost field can be completely contained in a mode-sized
3991 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3993 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3994 otherwise it is not changed.
3996 *PUNSIGNEDP is set to the signedness of the field.
3998 *PREVERSEP is set to the storage order of the field.
4000 *PMASK is set to the mask used. This is either contained in a
4001 BIT_AND_EXPR or derived from the width of the field.
4003 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4005 Return 0 if this is not a component reference or is one that we can't
4006 do anything with. */
4008 static tree
4013 {
4017 tree unsigned_type;
4020 /* All the optimizations using this function assume integer fields.
4021 There are problems with FP fields since the type_for_size call
4022 below can fail for, e.g., XFmode. */
4026 /* We are interested in the bare arrangement of bits, so strip everything
4027 that doesn't affect the machine mode. However, record the type of the
4028 outermost expression if it may matter below. */
4035 {
4041 }
4050 /* If the number of bits in the reference is the same as the bitsize of
4051 the outer type, then the outer type gives the signedness. Otherwise
4052 (in case of a small bitfield) the signedness is unchanged. */
4056 /* Compute the mask to access the bitfield. */
4065 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4073 }
4075 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4076 bit positions and MASK is SIGNED. */
4078 static int
4080 {
4084 /* If this function returns true when the type of the mask is
4085 UNSIGNED, then there will be errors. In particular see
4086 gcc.c-torture/execute/990326-1.c. There does not appear to be
4087 any documentation paper trail as to why this is so. But the pre
4088 wide-int worked with that restriction and it has been preserved
4089 here. */
4094 }
4096 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4097 represents the sign bit of EXP's type. If EXP represents a sign
4098 or zero extension, also test VAL against the unextended type.
4099 The return value is the (sub)expression whose sign bit is VAL,
4100 or NULL_TREE otherwise. */
4102 tree
4104 {
4106 tree t;
4108 /* Tree EXP must have an integral type. */
4113 /* Tree VAL must be an integer constant. */
4122 /* Handle extension from a narrower type. */
4128 }
4130 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4131 to be evaluated unconditionally. */
4133 static int
4135 {
4136 /* Strip any conversions that don't change the machine mode. */
4145 /* Don't regard global variables as simple. They may be
4146 allocated in ways unknown to the compiler (shared memory,
4147 #pragma weak, etc). */
4150 /* Weakrefs are not safe to be read, since they can be NULL.
4151 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4152 have DECL_WEAK flag set. */
4154 /* Loading a static variable is unduly expensive, but global
4155 registers aren't expensive. */
4157 }
4159 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4160 to be evaluated unconditionally.
4161 I addition to simple_operand_p, we assume that comparisons, conversions,
4162 and logic-not operations are simple, if their operands are simple, too. */
4164 static bool
4166 {
4186 }
4188 \f
4189 /* The following functions are subroutines to fold_range_test and allow it to
4190 try to change a logical combination of comparisons into a range test.
4192 For example, both
4193 X == 2 || X == 3 || X == 4 || X == 5
4194 and
4195 X >= 2 && X <= 5
4196 are converted to
4197 (unsigned) (X - 2) <= 3
4199 We describe each set of comparisons as being either inside or outside
4200 a range, using a variable named like IN_P, and then describe the
4201 range with a lower and upper bound. If one of the bounds is omitted,
4202 it represents either the highest or lowest value of the type.
4204 In the comments below, we represent a range by two numbers in brackets
4205 preceded by a "+" to designate being inside that range, or a "-" to
4206 designate being outside that range, so the condition can be inverted by
4207 flipping the prefix. An omitted bound is represented by a "-". For
4208 example, "- [-, 10]" means being outside the range starting at the lowest
4209 possible value and ending at 10, in other words, being greater than 10.
4210 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4211 always false.
4213 We set up things so that the missing bounds are handled in a consistent
4214 manner so neither a missing bound nor "true" and "false" need to be
4215 handled using a special case. */
4217 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4218 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4219 and UPPER1_P are nonzero if the respective argument is an upper bound
4220 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4221 must be specified for a comparison. ARG1 will be converted to ARG0's
4222 type if both are specified. */
4224 static tree
4227 {
4228 tree tem;
4232 /* If neither arg represents infinity, do the normal operation.
4233 Else, if not a comparison, return infinity. Else handle the special
4234 comparison rules. Note that most of the cases below won't occur, but
4235 are handled for consistency. */
4238 {
4243 }
4248 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4249 for neither. In real maths, we cannot assume open ended ranges are
4250 the same. But, this is computer arithmetic, where numbers are finite.
4251 We can therefore make the transformation of any unbounded range with
4252 the value Z, Z being greater than any representable number. This permits
4253 us to treat unbounded ranges as equal. */
4257 {
4278 }
4281 }
4282 \f
4283 /* Helper routine for make_range. Perform one step for it, return
4284 new expression if the loop should continue or NULL_TREE if it should
4285 stop. */
4287 tree
4291 {
4297 {
4299 /* We can only do something if the range is testing for zero. */
4308 /* We can only do something if the range is testing for zero
4309 and if the second operand is an integer constant. Note that
4310 saying something is "in" the range we make is done by
4311 complementing IN_P since it will set in the initial case of
4312 being not equal to zero; "out" is leaving it alone. */
4319 {
4340 }
4342 /* If this is an unsigned comparison, we also know that EXP is
4343 greater than or equal to zero. We base the range tests we make
4344 on that fact, so we record it here so we can parse existing
4345 range tests. We test arg0_type since often the return type
4346 of, e.g. EQ_EXPR, is boolean. */
4348 {
4352 NULL_TREE))
4357 /* If the high bound is missing, but we have a nonzero low
4358 bound, reverse the range so it goes from zero to the low bound
4359 minus 1. */
4361 {
4366 }
4367 }
4375 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4376 low and high are non-NULL, then normalize will DTRT. */
4379 {
4384 }
4386 /* (-x) IN [a,b] -> x in [-b, -a] */
4398 /* ~ X -> -X - 1 */
4407 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4408 move a constant to the other side. */
4413 /* If EXP is signed, any overflow in the computation is undefined,
4414 so we don't worry about it so long as our computations on
4415 the bounds don't overflow. For unsigned, overflow is defined
4416 and this is exactly the right thing. */
4428 normalize:
4429 /* Check for an unsigned range which has wrapped around the maximum
4430 value thus making n_high < n_low, and normalize it. */
4432 {
4438 /* If the range is of the form +/- [ x+1, x ], we won't
4439 be able to normalize it. But then, it represents the
4440 whole range or the empty set, so make it
4441 +/- [ -, - ]. */
4445 else
4447 }
4448 else
4456 CASE_CONVERT:
4474 /* If we're converting arg0 from an unsigned type, to exp,
4475 a signed type, we will be doing the comparison as unsigned.
4476 The tests above have already verified that LOW and HIGH
4477 are both positive.
4479 So we have to ensure that we will handle large unsigned
4480 values the same way that the current signed bounds treat
4481 negative values. */
4484 {
4485 tree high_positive;
4486 tree equiv_type;
4487 /* For fixed-point modes, we need to pass the saturating flag
4488 as the 2nd parameter. */
4490 equiv_type
4493 else
4494 equiv_type
4497 /* A range without an upper bound is, naturally, unbounded.
4498 Since convert would have cropped a very large value, use
4499 the max value for the destination type. */
4500 high_positive
4507 high_positive),
4510 /* If the low bound is specified, "and" the range with the
4511 range for which the original unsigned value will be
4512 positive. */
4514 {
4517 integer_zero_node),
4518 high_positive))
4522 }
4523 else
4524 {
4525 /* Otherwise, "or" the range with the range of the input
4526 that will be interpreted as negative. */
4529 integer_zero_node),
4530 high_positive))
4534 }
4535 }
4544 }
4545 }
4547 /* Given EXP, a logical expression, set the range it is testing into
4548 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4549 actually being tested. *PLOW and *PHIGH will be made of the same
4550 type as the returned expression. If EXP is not a comparison, we
4551 will most likely not be returning a useful value and range. Set
4552 *STRICT_OVERFLOW_P to true if the return value is only valid
4553 because signed overflow is undefined; otherwise, do not change
4554 *STRICT_OVERFLOW_P. */
4556 tree
4559 {
4567 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4568 and see if we can refine the range. Some of the cases below may not
4569 happen, but it doesn't seem worth worrying about this. We "continue"
4570 the outer loop when we've changed something; otherwise we "break"
4571 the switch, which will "break" the while. */
4577 {
4583 {
4591 }
4600 }
4602 /* If EXP is a constant, we can evaluate whether this is true or false. */
4604 {
4611 }
4615 }
4616 \f
4617 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4618 type, TYPE, return an expression to test if EXP is in (or out of, depending
4619 on IN_P) the range. Return 0 if the test couldn't be created. */
4621 tree
4624 {
4627 /* Disable this optimization for function pointer expressions
4628 on targets that require function pointer canonicalization. */
4635 {
4641 }
4659 {
4661 {
4665 }
4667 }
4669 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4671 {
4675 {
4677 {
4680 etype
4682 else
4685 }
4688 }
4689 }
4691 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4692 This requires wrap-around arithmetics for the type of the expression.
4693 First make sure that arithmetics in this type is valid, then make sure
4694 that it wraps around. */
4700 {
4703 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4704 for the type in question, as we rely on this here. */
4714 else
4716 }
4726 {
4728 {
4733 }
4735 }
4743 }
4744 \f
4745 /* Return the predecessor of VAL in its type, handling the infinite case. */
4747 static tree
4749 {
4755 else
4758 }
4760 /* Return the successor of VAL in its type, handling the infinite case. */
4762 static tree
4764 {
4770 else
4773 }
4775 /* Given two ranges, see if we can merge them into one. Return 1 if we
4776 can, 0 if we can't. Set the output range into the specified parameters. */
4778 bool
4781 {
4785 tree tem;
4795 /* Make range 0 be the range that starts first, or ends last if they
4796 start at the same value. Swap them if it isn't. */
4799 || (lowequal
4802 {
4806 }
4808 /* Now flag two cases, whether the ranges are disjoint or whether the
4809 second range is totally subsumed in the first. Note that the tests
4810 below are simplified by the ones above. */
4816 /* We now have four cases, depending on whether we are including or
4817 excluding the two ranges. */
4819 {
4820 /* If they don't overlap, the result is false. If the second range
4821 is a subset it is the result. Otherwise, the range is from the start
4822 of the second to the end of the first. */
4827 else
4829 }
4832 {
4833 /* If they don't overlap, the result is the first range. If they are
4834 equal, the result is false. If the second range is a subset of the
4835 first, and the ranges begin at the same place, we go from just after
4836 the end of the second range to the end of the first. If the second
4837 range is not a subset of the first, or if it is a subset and both
4838 ranges end at the same place, the range starts at the start of the
4839 first range and ends just before the second range.
4840 Otherwise, we can't describe this as a single range. */
4846 {
4851 {
4852 /* We are in the weird situation where high0 > high1 but
4853 high1 has no successor. Punt. */
4855 }
4856 }
4858 {
4863 {
4864 /* low0 < low1 but low1 has no predecessor. Punt. */
4866 }
4867 }
4868 else
4870 }
4873 {
4874 /* If they don't overlap, the result is the second range. If the second
4875 is a subset of the first, the result is false. Otherwise,
4876 the range starts just after the first range and ends at the
4877 end of the second. */
4882 else
4883 {
4888 {
4889 /* high1 > high0 but high0 has no successor. Punt. */
4891 }
4892 }
4893 }
4895 else
4896 {
4897 /* The case where we are excluding both ranges. Here the complex case
4898 is if they don't overlap. In that case, the only time we have a
4899 range is if they are adjacent. If the second is a subset of the
4900 first, the result is the first. Otherwise, the range to exclude
4901 starts at the beginning of the first range and ends at the end of the
4902 second. */
4904 {
4909 else
4910 {
4911 /* Canonicalize - [min, x] into - [-, x]. */
4914 {
4919 /* FALLTHROUGH */
4932 }
4934 /* Canonicalize - [x, max] into - [x, -]. */
4937 {
4942 /* FALLTHROUGH */
4958 }
4960 /* The ranges might be also adjacent between the maximum and
4961 minimum values of the given type. For
4962 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4963 return + [x + 1, y - 1]. */
4965 {
4972 }
4973 else
4975 }
4976 }
4979 else
4981 }
4985 }
4986 \f
4988 /* Subroutine of fold, looking inside expressions of the form
4989 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4990 of the COND_EXPR. This function is being used also to optimize
4991 A op B ? C : A, by reversing the comparison first.
4993 Return a folded expression whose code is not a COND_EXPR
4994 anymore, or NULL_TREE if no folding opportunity is found. */
4996 static tree
4999 {
5004 tree tem;
5009 /* If we have A op 0 ? A : -A, consider applying the following
5010 transformations:
5012 A == 0? A : -A same as -A
5013 A != 0? A : -A same as A
5014 A >= 0? A : -A same as abs (A)
5015 A > 0? A : -A same as abs (A)
5016 A <= 0? A : -A same as -abs (A)
5017 A < 0? A : -A same as -abs (A)
5019 None of these transformations work for modes with signed
5020 zeros. If A is +/-0, the first two transformations will
5021 change the sign of the result (from +0 to -0, or vice
5022 versa). The last four will fix the sign of the result,
5023 even though the original expressions could be positive or
5024 negative, depending on the sign of A.
5026 Note that all these transformations are correct if A is
5027 NaN, since the two alternatives (A and -A) are also NaNs. */
5034 /* In the case that A is of the form X-Y, '-A' (arg2) may
5035 have already been folded to Y-X, check for that. */
5043 {
5057 /* Fall through. */
5077 }
5079 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5080 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5081 both transformations are correct when A is NaN: A != 0
5082 is then true, and A == 0 is false. */
5086 {
5091 }
5093 /* Try some transformations of A op B ? A : B.
5095 A == B? A : B same as B
5096 A != B? A : B same as A
5097 A >= B? A : B same as max (A, B)
5098 A > B? A : B same as max (B, A)
5099 A <= B? A : B same as min (A, B)
5100 A < B? A : B same as min (B, A)
5102 As above, these transformations don't work in the presence
5103 of signed zeros. For example, if A and B are zeros of
5104 opposite sign, the first two transformations will change
5105 the sign of the result. In the last four, the original
5106 expressions give different results for (A=+0, B=-0) and
5107 (A=-0, B=+0), but the transformed expressions do not.
5109 The first two transformations are correct if either A or B
5110 is a NaN. In the first transformation, the condition will
5111 be false, and B will indeed be chosen. In the case of the
5112 second transformation, the condition A != B will be true,
5113 and A will be chosen.
5115 The conversions to max() and min() are not correct if B is
5116 a number and A is not. The conditions in the original
5117 expressions will be false, so all four give B. The min()
5118 and max() versions would give a NaN instead. */
5121 /* Avoid these transformations if the COND_EXPR may be used
5122 as an lvalue in the C++ front-end. PR c++/19199. */
5123 && (in_gimple_form
5129 {
5134 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5136 {
5140 }
5143 {
5152 /* In C++ a ?: expression can be an lvalue, so put the
5153 operand which will be used if they are equal first
5154 so that we can convert this back to the
5155 corresponding COND_EXPR. */
5157 {
5166 }
5173 {
5182 }
5197 }
5198 }
5200 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5201 we might still be able to simplify this. For example,
5202 if C1 is one less or one more than C2, this might have started
5203 out as a MIN or MAX and been transformed by this function.
5204 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5210 {
5214 /* We can replace A with C1 in this case. */
5219 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5220 MIN_EXPR, to preserve the signedness of the comparison. */
5222 OEP_ONLY_CONST)
5226 OEP_ONLY_CONST))
5227 {
5230 arg2));
5233 }
5237 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5238 as above. */
5240 OEP_ONLY_CONST)
5244 OEP_ONLY_CONST))
5245 {
5248 arg2));
5251 }
5255 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5256 MAX_EXPR, to preserve the signedness of the comparison. */
5258 OEP_ONLY_CONST)
5262 OEP_ONLY_CONST))
5263 {
5266 arg2));
5268 }
5272 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5274 OEP_ONLY_CONST)
5278 OEP_ONLY_CONST))
5279 {
5282 arg2));
5284 }
5290 }
5293 }
5296 \f
5297 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5298 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5299 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5300 false) >= 2)
5301 #endif
5303 /* EXP is some logical combination of boolean tests. See if we can
5304 merge it into some range test. Return the new tree if so. */
5306 static tree
5309 {
5325 /* If this is an OR operation, invert both sides; we will invert
5326 again at the end. */
5330 /* If both expressions are the same, if we can merge the ranges, and we
5331 can build the range test, return it or it inverted. If one of the
5332 ranges is always true or always false, consider it to be the same
5333 expression as the other. */
5341 {
5345 }
5347 /* On machines where the branch cost is expensive, if this is a
5348 short-circuited branch and the underlying object on both sides
5349 is the same, make a non-short-circuit operation. */
5355 {
5356 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5357 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5358 which cases we can't do this. */
5366 {
5375 {
5378 WARN_STRICT_OVERFLOW_COMPARISON);
5382 }
5383 }
5384 }
5387 }
5388 \f
5389 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5390 bit value. Arrange things so the extra bits will be set to zero if and
5391 only if C is signed-extended to its full width. If MASK is nonzero,
5392 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5394 static tree
5396 {
5399 tree temp;
5404 /* We work by getting just the sign bit into the low-order bit, then
5405 into the high-order bit, then sign-extend. We then XOR that value
5406 with C. */
5409 /* We must use a signed type in order to get an arithmetic right shift.
5410 However, we must also avoid introducing accidental overflows, so that
5411 a subsequent call to integer_zerop will work. Hence we must
5412 do the type conversion here. At this point, the constant is either
5413 zero or one, and the conversion to a signed type can never overflow.
5414 We could get an overflow if this conversion is done anywhere else. */
5423 /* If necessary, convert the type back to match the type of C. */
5428 }
5429 \f
5430 /* For an expression that has the form
5431 (A && B) || ~B
5432 or
5433 (A || B) && ~B,
5434 we can drop one of the inner expressions and simplify to
5435 A || ~B
5436 or
5437 A && ~B
5438 LOC is the location of the resulting expression. OP is the inner
5439 logical operation; the left-hand side in the examples above, while CMPOP
5440 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5441 removing a condition that guards another, as in
5442 (A != NULL && A->...) || A == NULL
5443 which we must not transform. If RHS_ONLY is true, only eliminate the
5444 right-most operand of the inner logical operation. */
5446 static tree
5449 {
5467 {
5470 {
5473 }
5474 }
5476 {
5479 {
5482 }
5483 }
5498 }
5500 /* Find ways of folding logical expressions of LHS and RHS:
5501 Try to merge two comparisons to the same innermost item.
5502 Look for range tests like "ch >= '0' && ch <= '9'".
5503 Look for combinations of simple terms on machines with expensive branches
5504 and evaluate the RHS unconditionally.
5506 For example, if we have p->a == 2 && p->b == 4 and we can make an
5507 object large enough to span both A and B, we can do this with a comparison
5508 against the object ANDed with the a mask.
5510 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5511 operations to do this with one comparison.
5513 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5514 function and the one above.
5516 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5517 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5519 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5520 two operands.
5522 We return the simplified tree or 0 if no optimization is possible. */
5524 static tree
5527 {
5528 /* If this is the "or" of two comparisons, we can do something if
5529 the comparisons are NE_EXPR. If this is the "and", we can do something
5530 if the comparisons are EQ_EXPR. I.e.,
5531 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5533 WANTED_CODE is this operation code. For single bit fields, we can
5534 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5535 comparison for one-bit fields. */
5556 /* Start by getting the comparison codes. Fail if anything is volatile.
5557 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5558 it were surrounded with a NE_EXPR. */
5567 {
5571 }
5574 {
5578 }
5589 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5592 {
5595 {
5600 }
5603 {
5609 }
5610 }
5615 /* If the RHS can be evaluated unconditionally and its operands are
5616 simple, it wins to evaluate the RHS unconditionally on machines
5617 with expensive branches. In this case, this isn't a comparison
5618 that can be merged. */
5625 {
5626 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5637 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5647 }
5649 /* See if the comparisons can be merged. Then get all the parameters for
5650 each side. */
5675 /* It must be true that the inner operation on the lhs of each
5676 comparison must be the same if we are to be able to do anything.
5677 Then see if we have constants. If not, the same must be true for
5678 the rhs's. */
5687 {
5690 }
5695 else
5698 /* If either comparison code is not correct for our logical operation,
5699 fail. However, we can convert a one-bit comparison against zero into
5700 the opposite comparison against that bit being set in the field. */
5704 {
5706 {
5707 /* Make the left operand unsigned, since we are only interested
5708 in the value of one bit. Otherwise we are doing the wrong
5709 thing below. */
5712 }
5713 else
5715 }
5717 /* This is analogous to the code for l_const above. */
5719 {
5721 {
5724 }
5725 else
5727 }
5729 /* See if we can find a mode that contains both fields being compared on
5730 the left. If we can't, fail. Otherwise, update all constants and masks
5731 to be relative to a field of that size. */
5736 volatilep);
5746 {
5749 }
5757 {
5764 {
5768 }
5769 }
5771 {
5778 {
5782 }
5783 }
5785 /* If the right sides are not constant, do the same for it. Also,
5786 disallow this optimization if a size or signedness mismatch occurs
5787 between the left and right sides. */
5789 {
5792 /* Make sure the two fields on the right
5793 correspond to the left without being swapped. */
5801 volatilep);
5811 {
5814 }
5823 /* Make a mask that corresponds to both fields being compared.
5824 Do this for both items being compared. If the operands are the
5825 same size and the bits being compared are in the same position
5826 then we can do this by masking both and comparing the masked
5827 results. */
5831 {
5843 }
5845 /* There is still another way we can do something: If both pairs of
5846 fields being compared are adjacent, we may be able to make a wider
5847 field containing them both.
5849 Note that we still must mask the lhs/rhs expressions. Furthermore,
5850 the mask must be shifted to account for the shift done by
5851 make_bit_field_ref. */
5856 {
5857 tree type;
5873 /* Convert to the smaller type before masking out unwanted bits. */
5876 {
5878 {
5882 }
5884 {
5888 }
5889 }
5898 }
5901 }
5903 /* Handle the case of comparisons with constants. If there is something in
5904 common between the masks, those bits of the constants must be the same.
5905 If not, the condition is always false. Test for this to avoid generating
5906 incorrect code below. */
5911 {
5913 {
5916 }
5917 else
5918 {
5921 }
5922 }
5924 /* Construct the expression we will return. First get the component
5925 reference we will make. Unless the mask is all ones the width of
5926 that field, perform the mask operation. Then compare with the
5927 merged constant. */
5937 }
5938 \f
5939 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5940 constant. */
5942 static tree
5945 {
5948 tree comp_const;
5949 tree minmax_const;
5951 tree inner;
5962 /* If something does not permit us to optimize, return the original tree. */
5970 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5971 and GT_EXPR, doing the rest with recursive calls using logical
5972 simplifications. */
5974 {
5976 {
5977 tree tem
5984 }
5987 return
5989 optimize_minmax_comparison
5991 optimize_minmax_comparison
5996 /* MAX (X, 0) == 0 -> X <= 0 */
6000 /* MAX (X, 0) == 5 -> X == 5 */
6004 /* MAX (X, 0) == -1 -> false */
6008 /* MIN (X, 0) == 0 -> X >= 0 */
6012 /* MIN (X, 0) == 5 -> false */
6015 else
6016 /* MIN (X, 0) == -1 -> X == -1 */
6021 /* MAX (X, 0) > 0 -> X > 0
6022 MAX (X, 0) > 5 -> X > 5 */
6026 /* MAX (X, 0) > -1 -> true */
6030 /* MIN (X, 0) > 0 -> false
6031 MIN (X, 0) > 5 -> false */
6034 else
6035 /* MIN (X, 0) > -1 -> X > -1 */
6040 }
6041 }
6042 \f
6043 /* T is an integer expression that is being multiplied, divided, or taken a
6044 modulus (CODE says which and what kind of divide or modulus) by a
6045 constant C. See if we can eliminate that operation by folding it with
6046 other operations already in T. WIDE_TYPE, if non-null, is a type that
6047 should be used for the computation if wider than our type.
6049 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6050 (X * 2) + (Y * 4). We must, however, be assured that either the original
6051 expression would not overflow or that overflow is undefined for the type
6052 in the language in question.
6054 If we return a non-null expression, it is an equivalent form of the
6055 original computation, but need not be in the original type.
6057 We set *STRICT_OVERFLOW_P to true if the return values depends on
6058 signed overflow being undefined. Otherwise we do not change
6059 *STRICT_OVERFLOW_P. */
6061 static tree
6064 {
6065 /* To avoid exponential search depth, refuse to allow recursion past
6066 three levels. Beyond that (1) it's highly unlikely that we'll find
6067 something interesting and (2) we've probably processed it before
6068 when we built the inner expression. */
6071 tree ret;
6076 depth++;
6078 depth--;
6081 }
6083 static tree
6086 {
6097 /* Don't deal with constants of zero here; they confuse the code below. */
6107 /* Note that we need not handle conditional operations here since fold
6108 already handles those cases. So just do arithmetic here. */
6110 {
6112 /* For a constant, we can always simplify if we are a multiply
6113 or (for divide and modulus) if it is a multiple of our constant. */
6116 {
6119 /* If the multiplication overflowed to INT_MIN then we lost sign
6120 information on it and a subsequent multiplication might
6121 spuriously overflow. See PR68142. */
6126 }
6130 /* If op0 is an expression ... */
6136 /* ... and has wrapping overflow, and its type is smaller
6137 than ctype, then we cannot pass through as widening. */
6142 /* ... or this is a truncation (t is narrower than op0),
6143 then we cannot pass through this narrowing. */
6146 /* ... or signedness changes for division or modulus,
6147 then we cannot pass through this conversion. */
6151 /* ... or has undefined overflow while the converted to
6152 type has not, we cannot do the operation in the inner type
6153 as that would introduce undefined overflow. */
6159 /* Pass the constant down and see if we can make a simplification. If
6160 we can, replace this expression with the inner simplification for
6161 possible later conversion to our or some other type. */
6166 code == MULT_EXPR
6168 strict_overflow_p))))
6173 /* If widening the type changes it from signed to unsigned, then we
6174 must avoid building ABS_EXPR itself as unsigned. */
6176 {
6180 {
6183 }
6185 }
6186 /* If the constant is negative, we cannot simplify this. */
6189 /* FALLTHROUGH */
6191 /* For division and modulus, type can't be unsigned, as e.g.
6192 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6193 For signed types, even with wrapping overflow, this is fine. */
6202 /* If widening the type changes the signedness, then we can't perform
6203 this optimization as that changes the result. */
6207 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6213 {
6220 }
6224 /* If the second operand is constant, this is a multiplication
6225 or floor division, by a power of two, so we can treat it that
6226 way unless the multiplier or divisor overflows. Signed
6227 left-shift overflow is implementation-defined rather than
6228 undefined in C90, so do not convert signed left shift into
6229 multiplication. */
6232 /* const_binop may not detect overflow correctly,
6233 so check for it explicitly here. */
6237 size_one_node,
6238 op1)))
6242 ctype,
6244 t1),
6249 /* See if we can eliminate the operation on both sides. If we can, we
6250 can return a new PLUS or MINUS. If we can't, the only remaining
6251 cases where we can do anything are if the second operand is a
6252 constant. */
6258 /* If not multiplication, we can only do this if both operands
6259 are divisible by c. */
6262 {
6267 }
6269 /* If this was a subtraction, negate OP1 and set it to be an addition.
6270 This simplifies the logic below. */
6272 {
6274 /* If OP1 was not easily negatable, the constant may be OP0. */
6276 {
6279 }
6280 }
6285 /* If either OP1 or C are negative, this optimization is not safe for
6286 some of the division and remainder types while for others we need
6287 to change the code. */
6289 {
6297 }
6299 /* If it's a multiply or a division/modulus operation of a multiple
6300 of our constant, do the operation and verify it doesn't overflow. */
6303 {
6306 /* We allow the constant to overflow with wrapping semantics. */
6310 }
6311 else
6314 /* If we have an unsigned type, we cannot widen the operation since it
6315 will change the result if the original computation overflowed. */
6319 /* If we were able to eliminate our operation from the first side,
6320 apply our operation to the second side and reform the PLUS. */
6324 /* The last case is if we are a multiply. In that case, we can
6325 apply the distributive law to commute the multiply and addition
6326 if the multiplication of the constants doesn't overflow
6327 and overflow is defined. With undefined overflow
6328 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6334 op1);
6339 /* We have a special case here if we are doing something like
6340 (C * 8) % 4 since we know that's zero. */
6343 /* If the multiplication can overflow we cannot optimize this. */
6347 {
6350 }
6352 /* ... fall through ... */
6356 /* If we can extract our operation from the LHS, do so and return a
6357 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6358 do something only if the second operand is a constant. */
6372 /* If these are the same operation types, we can associate them
6373 assuming no overflow. */
6375 {
6385 {
6390 }
6391 }
6393 /* If these operations "cancel" each other, we have the main
6394 optimizations of this pass, which occur when either constant is a
6395 multiple of the other, in which case we replace this with either an
6396 operation or CODE or TCODE.
6398 If we have an unsigned type, we cannot do this since it will change
6399 the result if the original computation overflowed. */
6406 {
6408 {
6415 }
6417 {
6424 }
6425 }
6430 }
6433 }
6434 \f
6435 /* Return a node which has the indicated constant VALUE (either 0 or
6436 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6437 and is of the indicated TYPE. */
6439 tree
6441 {
6450 else
6452 }
6455 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6456 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6457 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6458 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6459 COND is the first argument to CODE; otherwise (as in the example
6460 given here), it is the second argument. TYPE is the type of the
6461 original expression. Return NULL_TREE if no simplification is
6462 possible. */
6464 static tree
6469 {
6479 {
6483 /* If this operand throws an expression, then it does not make
6484 sense to try to perform a logical or arithmetic operation
6485 involving it. */
6490 }
6493 {
6498 }
6499 else
6500 /* Detect the case of mixing vector and scalar types - bail out. */
6506 /* This transformation is only worthwhile if we don't have to wrap ARG
6507 in a SAVE_EXPR and the operation can be simplified without recursing
6508 on at least one of the branches once its pushed inside the COND_EXPR. */
6517 {
6521 else
6523 }
6525 {
6529 else
6531 }
6533 /* Check that we have simplified at least one of the branches. */
6538 }
6540 \f
6541 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6543 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6544 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6545 ADDEND is the same as X.
6547 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6548 and finite. The problematic cases are when X is zero, and its mode
6549 has signed zeros. In the case of rounding towards -infinity,
6550 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6551 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6553 bool
6555 {
6559 /* Don't allow the fold with -fsignaling-nans. */
6563 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6567 /* In a vector or complex, we would need to check the sign of all zeros. */
6571 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6575 /* The mode has signed zeros, and we have to honor their sign.
6576 In this situation, there is only one case we can return true for.
6577 X - 0 is the same as X unless rounding towards -infinity is
6578 supported. */
6580 }
6582 /* Subroutine of fold() that optimizes comparisons of a division by
6583 a nonzero integer constant against an integer constant, i.e.
6584 X/C1 op C2.
6586 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6587 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6588 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6590 The function returns the constant folded tree if a simplification
6591 can be made, and NULL_TREE otherwise. */
6593 static tree
6596 {
6604 /* We have to do this the hard way to detect unsigned overflow.
6605 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6611 {
6616 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6620 }
6622 {
6626 {
6645 }
6646 }
6647 else
6648 {
6649 /* A negative divisor reverses the relational operators. */
6655 {
6674 }
6675 }
6678 {
6699 {
6702 }
6707 {
6710 }
6715 {
6718 }
6723 {
6726 }
6731 }
6734 }
6737 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6738 equality/inequality test, then return a simplified form of the test
6739 using a sign testing. Otherwise return NULL. TYPE is the desired
6740 result type. */
6742 static tree
6745 tree result_type)
6746 {
6747 /* If this is testing a single bit, we can optimize the test. */
6751 {
6752 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6753 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6757 /* This is only a win if casting to a signed type is cheap,
6758 i.e. when arg00's type is not a partial mode. */
6761 {
6764 result_type,
6767 }
6768 }
6771 }
6773 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6774 equality/inequality test, then return a simplified form of
6775 the test using shifts and logical operations. Otherwise return
6776 NULL. TYPE is the desired result type. */
6778 tree
6781 {
6782 /* If this is testing a single bit, we can optimize the test. */
6786 {
6795 /* First, see if we can fold the single bit test into a sign-bit
6796 test. */
6798 result_type);
6802 /* Otherwise we have (A & C) != 0 where C is a single bit,
6803 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6804 Similarly for (A & C) == 0. */
6806 /* If INNER is a right shift of a constant and it plus BITNUM does
6807 not overflow, adjust BITNUM and INNER. */
6813 {
6816 }
6818 /* If we are going to be able to omit the AND below, we must do our
6819 operations as unsigned. If we must use the AND, we have a choice.
6820 Normally unsigned is faster, but for some machines signed is. */
6838 /* Put the AND last so it can combine with more things. */
6841 /* Make sure to return the proper type. */
6845 }
6847 }
6849 /* Check whether we are allowed to reorder operands arg0 and arg1,
6850 such that the evaluation of arg1 occurs before arg0. */
6852 static bool
6854 {
6861 }
6863 /* Test whether it is preferable two swap two operands, ARG0 and
6864 ARG1, for example because ARG0 is an integer constant and ARG1
6865 isn't. If REORDER is true, only recommend swapping if we can
6866 evaluate the operands in reverse order. */
6868 bool
6870 {
6888 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6889 for commutative and comparison operators. Ensuring a canonical
6890 form allows the optimizers to find additional redundancies without
6891 having to explicitly check for both orderings. */
6897 /* Put SSA_NAMEs last. */
6903 /* Put variables last. */
6910 }
6913 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6914 means A >= Y && A != MAX, but in this case we know that
6915 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6917 static tree
6919 {
6926 else
6935 {
6938 }
6940 {
6943 }
6944 else
6951 {
6952 /* Convert the pointer types into integer before taking the difference. */
6956 }
6957 else
6964 }
6966 /* Fold a sum or difference of at least one multiplication.
6967 Returns the folded tree or NULL if no simplification could be made. */
6969 static tree
6972 {
6976 /* (A * C) +- (B * C) -> (A+-B) * C.
6977 (A * C) +- A -> A * (C+-1).
6978 We are most concerned about the case where C is a constant,
6979 but other combinations show up during loop reduction. Since
6980 it is not difficult, try all four possibilities. */
6983 {
6986 }
6988 {
6991 }
6992 else
6993 {
6994 /* We cannot generate constant 1 for fract. */
6999 }
7001 {
7004 }
7006 {
7008 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7009 the purpose of this canonicalization. */
7013 {
7016 }
7017 else
7019 }
7020 else
7021 {
7022 /* We cannot generate constant 1 for fract. */
7027 }
7039 /* No identical multiplicands; see if we can find a common
7040 power-of-two factor in non-power-of-two multiplies. This
7041 can help in multi-dimensional array access. */
7044 {
7047 tree maybe_same;
7051 /* Move min of absolute values to int11. */
7053 {
7058 }
7059 else
7063 /* The remainder should not be a constant, otherwise we
7064 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7065 increased the number of multiplications necessary. */
7067 {
7075 }
7076 }
7086 }
7088 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7089 specified by EXPR into the buffer PTR of length LEN bytes.
7090 Return the number of bytes placed in the buffer, or zero
7091 upon failure. */
7093 static int
7095 {
7109 {
7111 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7112 number of bytes. */
7116 {
7123 else
7125 }
7126 else
7131 }
7133 }
7136 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7137 specified by EXPR into the buffer PTR of length LEN bytes.
7138 Return the number of bytes placed in the buffer, or zero
7139 upon failure. */
7141 static int
7143 {
7147 FIXED_VALUE_TYPE value;
7163 }
7166 /* Subroutine of native_encode_expr. Encode the REAL_CST
7167 specified by EXPR into the buffer PTR of length LEN bytes.
7168 Return the number of bytes placed in the buffer, or zero
7169 upon failure. */
7171 static int
7173 {
7179 /* There are always 32 bits in each long, no matter the size of
7180 the hosts long. We handle floating point representations with
7181 up to 192 bits. */
7195 {
7200 {
7207 else
7209 }
7210 else
7216 }
7218 }
7220 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7221 specified by EXPR into the buffer PTR of length LEN bytes.
7222 Return the number of bytes placed in the buffer, or zero
7223 upon failure. */
7225 static int
7227 {
7229 tree part;
7244 }
7247 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7248 specified by EXPR into the buffer PTR of length LEN bytes.
7249 Return the number of bytes placed in the buffer, or zero
7250 upon failure. */
7252 static int
7254 {
7264 {
7266 {
7269 }
7280 }
7282 }
7285 /* Subroutine of native_encode_expr. Encode the STRING_CST
7286 specified by EXPR into the buffer PTR of length LEN bytes.
7287 Return the number of bytes placed in the buffer, or zero
7288 upon failure. */
7290 static int
7292 {
7294 HOST_WIDE_INT total_bytes;
7308 {
7311 {
7314 }
7317 }
7318 else
7321 }
7324 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7325 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7326 buffer PTR of length LEN bytes. If OFF is not -1 then start
7327 the encoding at byte offset OFF and encode at most LEN bytes.
7328 Return the number of bytes placed in the buffer, or zero upon failure. */
7330 int
7332 {
7333 /* We don't support starting at negative offset and -1 is special. */
7338 {
7359 }
7360 }
7363 /* Subroutine of native_interpret_expr. Interpret the contents of
7364 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7365 If the buffer cannot be interpreted, return NULL_TREE. */
7367 static tree
7369 {
7379 }
7382 /* Subroutine of native_interpret_expr. Interpret the contents of
7383 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7384 If the buffer cannot be interpreted, return NULL_TREE. */
7386 static tree
7388 {
7390 double_int result;
7391 FIXED_VALUE_TYPE fixed_value;
7401 }
7404 /* Subroutine of native_interpret_expr. Interpret the contents of
7405 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7406 If the buffer cannot be interpreted, return NULL_TREE. */
7408 static tree
7410 {
7414 /* There are always 32 bits in each long, no matter the size of
7415 the hosts long. We handle floating point representations with
7416 up to 192 bits. */
7417 REAL_VALUE_TYPE r;
7428 {
7429 /* Both OFFSET and BYTE index within a long;
7430 bitpos indexes the whole float. */
7433 {
7440 else
7442 }
7443 else
7444 {
7447 {
7448 /* Reverse bytes within each long, or within the entire float
7449 if it's smaller than a long (for HFmode). */
7452 }
7453 }
7457 }
7461 }
7464 /* Subroutine of native_interpret_expr. Interpret the contents of
7465 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7466 If the buffer cannot be interpreted, return NULL_TREE. */
7468 static tree
7470 {
7485 }
7488 /* Subroutine of native_interpret_expr. Interpret the contents of
7489 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7490 If the buffer cannot be interpreted, return NULL_TREE. */
7492 static tree
7494 {
7507 {
7512 }
7514 }
7517 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7518 the buffer PTR of length LEN as a constant of type TYPE. For
7519 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7520 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7521 return NULL_TREE. */
7523 tree
7525 {
7527 {
7549 }
7550 }
7552 /* Returns true if we can interpret the contents of a native encoding
7553 as TYPE. */
7555 static bool
7557 {
7559 {
7572 }
7573 }
7575 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7576 TYPE at compile-time. If we're unable to perform the conversion
7577 return NULL_TREE. */
7579 static tree
7581 {
7582 /* We support up to 512-bit values (for V8DFmode). */
7586 /* Check that the host and target are sane. */
7595 }
7597 /* Build an expression for the address of T. Folds away INDIRECT_REF
7598 to avoid confusing the gimplify process. */
7600 tree
7602 {
7603 /* The size of the object is not relevant when talking about its address. */
7608 {
7613 }
7623 {
7628 }
7629 else
7633 }
7635 /* Build an expression for the address of T. */
7637 tree
7639 {
7643 }
7645 /* Fold a unary expression of code CODE and type TYPE with operand
7646 OP0. Return the folded expression if folding is successful.
7647 Otherwise, return NULL_TREE. */
7649 tree
7651 {
7652 tree tem;
7653 tree arg0;
7661 {
7664 {
7665 /* Don't use STRIP_NOPS, because signedness of argument type
7666 matters. */
7668 }
7669 else
7670 {
7671 /* Strip any conversions that don't change the mode. This
7672 is safe for every expression, except for a comparison
7673 expression because its signedness is derived from its
7674 operands.
7676 Note that this is done as an internal manipulation within
7677 the constant folder, in order to find the simplest
7678 representation of the arguments so that their form can be
7679 studied. In any cases, the appropriate type conversions
7680 should be put back in the tree that will get out of the
7681 constant folder. */
7683 }
7686 {
7689 {
7693 }
7694 }
7695 }
7702 {
7709 {
7723 /* If this was a conversion, and all we did was to move into
7724 inside the COND_EXPR, bring it back out. But leave it if
7725 it is a conversion from integer to integer and the
7726 result precision is no wider than a word since such a
7727 conversion is cheap and may be optimized away by combine,
7728 while it couldn't if it were outside the COND_EXPR. Then return
7729 so we don't get into an infinite recursion loop taking the
7730 conversion out and then back in. */
7742 && (INTEGRAL_TYPE_P
7755 }
7756 }
7759 {
7765 CASE_CONVERT:
7769 {
7770 /* If we have (type) (a CMP b) and type is an integral type, return
7771 new expression involving the new type. Canonicalize
7772 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7773 non-integral type.
7774 Do not fold the result as that would not simplify further, also
7775 folding again results in recursions. */
7785 }
7787 /* Handle (T *)&A.B.C for A being of type T and B and C
7788 living at offset zero. This occurs frequently in
7789 C++ upcasting and then accessing the base. */
7793 {
7795 tree offset;
7796 machine_mode mode;
7798 tree base
7802 /* If the reference was to a (constant) zero offset, we can use
7803 the address of the base if it has the same base type
7804 as the result type and the pointer type is unqualified. */
7811 }
7815 /* Detect assigning a bitfield. */
7817 && DECL_BIT_FIELD
7819 {
7820 /* Don't leave an assignment inside a conversion
7821 unless assigning a bitfield. */
7823 /* First do the assignment, then return converted constant. */
7828 }
7830 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7831 constants (if x has signed type, the sign bit cannot be set
7832 in c). This folds extension into the BIT_AND_EXPR.
7833 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7834 very likely don't have maximal range for their precision and this
7835 transformation effectively doesn't preserve non-maximal ranges. */
7839 {
7850 <= HOST_BITS_PER_WIDE_INT
7852 {
7856 cst &= HOST_WIDE_INT_M1U
7860 && !flag_syntax_only
7863 {
7867 }
7868 }
7870 {
7875 }
7876 }
7878 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7879 cast (T1)X will fold away. We assume that this happens when X itself
7880 is a cast. */
7884 {
7888 return fold_build_pointer_plus_loc
7890 }
7892 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7893 of the same precision, and X is an integer type not narrower than
7894 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7900 {
7906 }
7908 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7909 type of X and Y (integer types only). */
7914 {
7915 /* Be careful not to introduce new overflows. */
7916 tree mult_type;
7919 else
7923 {
7930 }
7931 }
7937 {
7942 }
7953 /* Convert fabs((double)float) into (double)fabsf(float). */
7956 {
7962 targ0));
7963 }
7967 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7986 /* Note that the operand of this must be an int
7987 and its values must be 0 or 1.
7988 ("true" is a fixed value perhaps depending on the language,
7989 but we don't handle values other than 1 correctly yet.) */
7996 /* Fold *&X to X if X is an lvalue. */
7998 {
8005 }
8011 }
8014 /* If the operation was a conversion do _not_ mark a resulting constant
8015 with TREE_OVERFLOW if the original constant was not. These conversions
8016 have implementation defined behavior and retaining the TREE_OVERFLOW
8017 flag here would confuse later passes such as VRP. */
8018 tree
8021 {
8030 }
8032 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8033 operands OP0 and OP1. LOC is the location of the resulting expression.
8034 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8035 Return the folded expression if folding is successful. Otherwise,
8036 return NULL_TREE. */
8037 static tree
8040 {
8041 tree tem;
8043 /* We only do these simplifications if we are optimizing. */
8047 /* Check for things like (A || B) && (A || C). We can convert this
8048 to A || (B && C). Note that either operator can be any of the four
8049 truth and/or operations and the transformation will still be
8050 valid. Also note that we only care about order for the
8051 ANDIF and ORIF operators. If B contains side effects, this
8052 might change the truth-value of A. */
8059 {
8079 /* This case if tricky because we must either have commutative
8080 operators or else A10 must not have side-effects. */
8086 a01);
8087 }
8089 /* See if we can build a range comparison. */
8095 {
8099 }
8103 {
8107 }
8109 /* Check for the possibility of merging component references. If our
8110 lhs is another similar operation, try to merge its rhs with our
8111 rhs. Then try to merge our lhs and rhs. */
8125 {
8132 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8133 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8134 We don't want to pack more than two leafs to a non-IF AND/OR
8135 expression.
8136 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8137 equal to IF-CODE, then we don't want to add right-hand operand.
8138 If the inner right-hand side of left-hand operand has
8139 side-effects, or isn't simple, then we can't add to it,
8140 as otherwise we might destroy if-sequence. */
8143 /* Needed for sequence points to handle trappings, and
8144 side-effects. */
8146 {
8148 arg1);
8150 tem);
8151 }
8152 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8153 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8156 /* Needed for sequence points to handle trappings, and
8157 side-effects. */
8159 {
8164 }
8165 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8166 into (A OR B).
8167 For sequence point consistancy, we need to check for trapping,
8168 and side-effects. */
8172 }
8175 }
8177 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8178 by changing CODE to reduce the magnitude of constants involved in
8179 ARG0 of the comparison.
8180 Returns a canonicalized comparison tree if a simplification was
8181 possible, otherwise returns NULL_TREE.
8182 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8183 valid if signed overflow is undefined. */
8185 static tree
8189 {
8194 /* Match A +- CST code arg1. We can change this only if overflow
8195 is undefined. */
8198 /* In principle pointers also have undefined overflow behavior,
8199 but that causes problems elsewhere. */
8206 /* Identify the constant in arg0 and its sign. */
8210 /* Overflowed constants and zero will cause problems. */
8215 /* See if we can reduce the magnitude of the constant in
8216 arg0 by changing the comparison code. */
8217 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8221 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8225 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8229 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8233 else
8237 /* Now build the constant reduced in magnitude. But not if that
8238 would produce one outside of its types range. */
8254 }
8256 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8257 overflow further. Try to decrease the magnitude of constants involved
8258 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8259 and put sole constants at the second argument position.
8260 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8262 static tree
8265 {
8266 tree t;
8271 /* Try canonicalization by simplifying arg0. */
8276 {
8280 }
8282 /* Try canonicalization by simplifying arg1 using the swapped
8283 comparison. */
8291 }
8293 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8294 space. This is used to avoid issuing overflow warnings for
8295 expressions like &p->x which can not wrap. */
8297 static bool
8299 {
8306 wide_int wi_offset;
8312 else
8328 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8329 array. */
8331 {
8332 HOST_WIDE_INT base_size;
8337 }
8340 }
8342 /* Subroutine of fold_binary. This routine performs all of the
8343 transformations that are common to the equality/inequality
8344 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8345 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8346 fold_binary should call fold_binary. Fold a comparison with
8347 tree code CODE and type TYPE with operands OP0 and OP1. Return
8348 the folded comparison or NULL_TREE. */
8350 static tree
8353 {
8363 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8365 && (equality_code
8372 {
8373 const enum tree_code
8380 /* If the constant operation overflowed this can be
8381 simplified as a comparison against INT_MAX/INT_MIN. */
8384 {
8388 /* Get the sign of the constant on the lhs if the
8389 operation were VARIABLE + CONST1. */
8393 /* The sign of the constant determines if we overflowed
8394 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8395 Canonicalize to the INT_MIN overflow by swapping the comparison
8396 if necessary. */
8400 /* We now can look at the canonicalized case
8401 VARIABLE + 1 CODE2 INT_MIN
8402 and decide on the result. */
8404 {
8408 return
8414 return
8419 }
8420 }
8421 else
8422 {
8425 "when changing X +- C1 cmp C2 to "
8427 WARN_STRICT_OVERFLOW_COMPARISON);
8429 }
8430 }
8432 /* For comparisons of pointers we can decompose it to a compile time
8433 comparison of the base objects and the offsets into the object.
8434 This requires at least one operand being an ADDR_EXPR or a
8435 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8441 {
8444 machine_mode mode;
8448 /* Get base and offset for the access. Strip ADDR_EXPR for
8449 get_inner_reference, but put it back by stripping INDIRECT_REF
8450 off the base object if possible. indirect_baseN will be true
8451 if baseN is not an address but refers to the object itself. */
8454 {
8455 base0
8461 else
8463 }
8465 {
8469 {
8470 base0
8477 else
8479 }
8482 else
8486 {
8492 {
8495 }
8496 }
8497 }
8501 {
8502 base1
8508 else
8510 }
8512 {
8516 {
8517 base1
8524 else
8526 }
8529 else
8533 {
8539 {
8542 }
8543 }
8544 }
8546 /* If we have equivalent bases we might be able to simplify. */
8550 {
8551 /* We can fold this expression to a constant if the non-constant
8552 offset parts are equal. */
8561 {
8567 "occur when comparing P +- C1 with "
8569 WARN_STRICT_OVERFLOW_CONDITIONAL);
8572 {
8586 }
8587 }
8588 /* We can simplify the comparison to a comparison of the variable
8589 offset parts if the constant offset parts are equal.
8590 Be careful to use signed sizetype here because otherwise we
8591 mess with array offsets in the wrong way. This is possible
8592 because pointer arithmetic is restricted to retain within an
8593 object and overflow on pointer differences is undefined as of
8594 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8596 && (equality_code
8599 {
8600 /* By converting to signed sizetype we cover middle-end pointer
8601 arithmetic which operates on unsigned pointer types of size
8602 type size and ARRAY_REF offsets which are properly sign or
8603 zero extended from their type in case it is narrower than
8604 sizetype. */
8607 else
8611 else
8618 "occur when comparing P +- C1 with "
8620 WARN_STRICT_OVERFLOW_COMPARISON);
8623 }
8624 }
8625 /* For equal offsets we can simplify to a comparison of the
8626 base addresses. */
8628 && (indirect_base0
8630 && (indirect_base1
8635 {
8641 }
8642 }
8644 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8645 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8646 the resulting offset is smaller in absolute value than the
8647 original one and has the same sign. */
8656 {
8661 tree cst;
8663 "occur when combining constants around "
8666 /* Put the constant on the side where it doesn't overflow and is
8667 of lower absolute value and of same sign than before. */
8674 {
8677 variable1,
8681 }
8689 {
8695 variable2);
8696 }
8697 }
8703 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8704 constant, we can simplify it. */
8709 {
8713 }
8715 /* If we are comparing an expression that just has comparisons
8716 of two integer values, arithmetic expressions of those comparisons,
8717 and constants, we can simplify it. There are only three cases
8718 to check: the two values can either be equal, the first can be
8719 greater, or the second can be greater. Fold the expression for
8720 those three values. Since each value must be 0 or 1, we have
8721 eight possibilities, each of which corresponds to the constant 0
8722 or 1 or one of the six possible comparisons.
8724 This handles common cases like (a > b) == 0 but also handles
8725 expressions like ((x > y) - (y > x)) > 0, which supposedly
8726 occur in macroized code. */
8729 {
8734 /* Don't handle degenerate cases here; they should already
8735 have been handled anyway. */
8744 {
8748 /* We can't just pass T to eval_subst in case cval1 or cval2
8749 was the same as ARG1. */
8751 tree high_result
8755 arg1);
8756 tree equal_result
8760 arg1);
8761 tree low_result
8765 arg1);
8767 /* All three of these results should be 0 or 1. Confirm they are.
8768 Then use those values to select the proper code to use. */
8773 {
8774 /* Make a 3-bit mask with the high-order bit being the
8775 value for `>', the next for '=', and the low for '<'. */
8779 {
8781 /* Always false. */
8802 /* Always true. */
8804 }
8807 {
8811 }
8813 }
8814 }
8815 }
8817 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8818 into a single range test. */
8826 {
8830 }
8833 }
8836 /* Subroutine of fold_binary. Optimize complex multiplications of the
8837 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8838 argument EXPR represents the expression "z" of type TYPE. */
8840 static tree
8842 {
8847 {
8850 }
8852 {
8855 }
8856 else
8857 {
8861 }
8870 }
8873 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8874 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8876 static bool
8878 {
8882 {
8885 }
8887 {
8893 else
8895 }
8896 else
8902 }
8904 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8905 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8906 NULL_TREE otherwise. */
8908 static tree
8910 {
8927 {
8931 }
8934 {
8940 }
8941 else
8943 }
8945 /* Try to fold a pointer difference of type TYPE two address expressions of
8946 array references AREF0 and AREF1 using location LOC. Return a
8947 simplified expression for the difference or NULL_TREE. */
8949 static tree
8952 {
8957 /* If the bases are array references as well, recurse. If the bases
8958 are pointer indirections compute the difference of the pointers.
8959 If the bases are equal, we are set. */
8962 && (base_offset
8966 && (base_offset
8972 {
8978 base_offset,
8981 }
8983 }
8985 /* If the real or vector real constant CST of type TYPE has an exact
8986 inverse, return it, else return NULL. */
8988 tree
8990 {
8991 REAL_VALUE_TYPE r;
8993 machine_mode mode;
8997 {
9013 {
9018 }
9024 }
9025 }
9027 /* Mask out the tz least significant bits of X of type TYPE where
9028 tz is the number of trailing zeroes in Y. */
9029 static wide_int
9031 {
9036 }
9038 /* Return true when T is an address and is known to be nonzero.
9039 For floating point we further ensure that T is not denormal.
9040 Similar logic is present in nonzero_address in rtlanal.h.
9042 If the return value is based on the assumption that signed overflow
9043 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9044 change *STRICT_OVERFLOW_P. */
9046 static bool
9048 {
9052 /* Doing something useful for floating point would need more work. */
9058 {
9061 strict_overflow_p);
9067 strict_overflow_p);
9075 }
9078 {
9081 strict_overflow_p);
9089 strict_overflow_p);
9104 strict_overflow_p);
9108 strict_overflow_p);
9111 {
9123 }
9127 }
9129 }
9131 /* Return true when T is an address and is known to be nonzero.
9132 Handle warnings about undefined signed overflow. */
9134 static bool
9136 {
9143 "determining that expression is always "
9145 WARN_STRICT_OVERFLOW_MISC);
9147 }
9149 /* Return true if T is known not to be equal to an integer W. */
9151 bool
9153 {
9155 value_range_type rtype;
9157 {
9166 {
9171 }
9176 /* If T has some known zero bits and W has any of those bits set,
9177 then T is known not to be equal to W. */
9185 }
9186 }
9188 /* Fold a binary expression of code CODE and type TYPE with operands
9189 OP0 and OP1. LOC is the location of the resulting expression.
9190 Return the folded expression if folding is successful. Otherwise,
9191 return NULL_TREE. */
9193 tree
9196 {
9211 /* Strip any conversions that don't change the mode. This is
9212 safe for every expression, except for a comparison expression
9213 because its signedness is derived from its operands. So, in
9214 the latter case, only strip conversions that don't change the
9215 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9216 preserved.
9218 Note that this is done as an internal manipulation within the
9219 constant folder, in order to find the simplest representation
9220 of the arguments so that their form can be studied. In any
9221 cases, the appropriate type conversions should be put back in
9222 the tree that will get out of the constant folder. */
9225 {
9228 }
9229 else
9230 {
9233 }
9235 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9236 constant but we can't do arithmetic on them. */
9238 {
9241 {
9245 }
9246 }
9248 /* If this is a commutative operation, and ARG0 is a constant, move it
9249 to ARG1 to reduce the number of tests below. */
9254 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9255 to ARG1 to reduce the number of tests below. */
9264 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9266 First check for cases where an arithmetic operation is applied to a
9267 compound, conditional, or comparison operation. Push the arithmetic
9268 operation inside the compound or conditional to see if any folding
9269 can then be done. Convert comparison to conditional for this purpose.
9270 The also optimizes non-constant cases that used to be done in
9271 expand_expr.
9273 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9274 one of the operands is a comparison and the other is a comparison, a
9275 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9276 code below would make the expression more complex. Change it to a
9277 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9278 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9291 {
9295 boolean_type_node,
9303 }
9307 {
9309 {
9314 tem);
9315 }
9318 {
9323 tem);
9324 }
9329 {
9335 }
9340 {
9346 }
9347 }
9350 {
9352 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9355 {
9361 }
9363 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9366 {
9367 tree base;
9368 HOST_WIDE_INT coffset;
9377 }
9382 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9388 arg1),
9390 arg0)));
9396 {
9397 /* X + (X / CST) * -CST is X % CST. */
9402 {
9411 cst0));
9412 }
9413 }
9415 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9416 one. Make sure the type is not saturating and has the signedness of
9417 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9418 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9425 {
9429 }
9432 {
9433 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9434 (plus (plus (mult) (mult)) (foo)) so that we can
9435 take advantage of the factoring cases below. */
9444 {
9450 else
9463 parg0),
9465 marg)),
9469 return
9475 parg1)));
9476 }
9477 }
9478 else
9479 {
9480 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9481 to __complex__ ( x, y ). This is not the same for SNaNs or
9482 if signed zeros are involved. */
9486 {
9493 {
9497 {
9503 }
9505 {
9511 }
9512 }
9513 }
9521 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9522 We associate floats only if the user has specified
9523 -fassociative-math. */
9527 {
9532 {
9533 tree tree0;
9536 }
9537 }
9538 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9539 We associate floats only if the user has specified
9540 -fassociative-math. */
9544 {
9549 {
9550 tree tree0;
9553 }
9554 }
9555 }
9557 bit_rotate:
9558 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9559 is a rotate of A by C1 bits. */
9560 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9561 is a rotate of A by B bits. */
9562 {
9564 tree rtype;
9573 /* Only create rotates in complete modes. Other cases are not
9574 expanded properly. */
9577 {
9591 {
9595 code0 == LSHIFT_EXPR
9599 }
9601 {
9609 element_precision
9613 return
9616 ? LROTATE_EXPR
9621 }
9623 {
9631 element_precision
9635 return fold_convert_loc
9638 ? LROTATE_EXPR
9642 }
9643 }
9644 }
9646 associate:
9647 /* In most languages, can't associate operations on floats through
9648 parentheses. Rather than remember where the parentheses were, we
9649 don't associate floats at all, unless the user has specified
9650 -fassociative-math.
9651 And, we need to make sure type is not saturating. */
9655 {
9661 /* Split both trees into variables, constants, and literals. Then
9662 associate each group together, the constants with literals,
9663 then the result with variables. This increases the chances of
9664 literals being recombined later and of generating relocatable
9665 expressions for the sum of a constant and literal. */
9671 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9675 /* With undefined overflow prefer doing association in a type
9676 which wraps on overflow, if that is one of the operand types. */
9679 {
9687 }
9689 /* With undefined overflow we can only associate constants with one
9690 variable, and constants whose association doesn't overflow. */
9693 {
9695 {
9701 {
9704 }
9711 {
9714 }
9720 /* The only case we can still associate with two variables
9721 is if they cancel out. */
9725 }
9726 }
9728 /* Only do something if we found more than two objects. Otherwise,
9729 nothing has changed and we risk infinite recursion. */
9735 {
9747 /* Preserve the MINUS_EXPR if the negative part of the literal is
9748 greater than the positive part. Otherwise, the multiplicative
9749 folding code (i.e extract_muldiv) may be fooled in case
9750 unsigned constants are subtracted, like in the following
9751 example: ((X*2 + 4) - 8U)/2. */
9753 {
9757 {
9761 }
9762 else
9763 {
9767 }
9768 }
9770 /* Don't introduce overflows through reassociation. */
9777 {
9779 return
9783 else
9784 {
9787 return
9791 }
9792 }
9795 return
9798 }
9799 }
9804 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9813 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9814 __complex__ ( x, -y ). This is not the same for SNaNs or if
9815 signed zeros are involved. */
9819 {
9826 {
9830 {
9832 arg1r ? arg1r
9837 }
9839 {
9843 arg1i ? arg1i
9846 }
9847 }
9848 }
9850 /* A - B -> A + (-B) if B is easily negatable. */
9854 /* Avoid this transformation if B is a positive REAL_CST. */
9862 /* Fold &a[i] - &a[j] to i-j. */
9867 {
9873 }
9876 && flag_unsafe_math_optimizations
9882 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9883 one. Make sure the type is not saturating and has the signedness of
9884 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9885 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9892 {
9896 }
9902 {
9903 /* Transform x * -C into -x * C if x is easily negatable. */
9913 /* (A + A) * C -> A * 2 * C */
9925 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9926 sign-changing only. */
9936 {
9939 "occur when simplifying "
9941 WARN_STRICT_OVERFLOW_MISC);
9943 }
9945 /* Optimize z * conj(z) for integer complex numbers. */
9952 }
9953 else
9954 {
9955 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9956 This is not the same for NaNs or if signed zeros are
9957 involved. */
9963 {
9966 return
9972 return
9977 }
9979 /* Optimize z * conj(z) for floating point complex numbers.
9980 Guarded by flag_unsafe_math_optimizations as non-finite
9981 imaginary components don't produce scalar results. */
9992 {
9994 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
9996 && optimize
9998 {
10002 {
10005 }
10006 }
10007 }
10008 }
10012 /* Canonicalize (X & C1) | C2. */
10016 {
10021 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10029 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10034 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10035 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10036 mode which allows further optimizations. */
10041 {
10045 {
10048 }
10049 }
10056 c3)),
10057 arg1);
10058 }
10060 /* See if this can be simplified into a rotate first. If that
10061 is unsuccessful continue in the association code. */
10065 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10073 /* See if this can be simplified into a rotate first. If that
10074 is unsuccessful continue in the association code. */
10078 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10083 {
10084 tree tem2;
10091 }
10092 /* Fold ~X & 1 as (X & 1) == 0. */
10096 {
10097 tree tem2;
10104 }
10105 /* Fold !X & 1 as X == 0. */
10108 {
10112 }
10114 /* Fold (X ^ Y) & Y as ~X & Y. */
10117 {
10122 }
10123 /* Fold (X ^ Y) & X as ~Y & X. */
10127 {
10132 }
10133 /* Fold X & (X ^ Y) as X & ~Y. */
10136 {
10141 }
10142 /* Fold X & (Y ^ X) as ~Y & X. */
10146 {
10151 }
10153 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10154 multiple of 1 << CST. */
10156 {
10163 }
10165 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10166 bits from CST2. */
10170 {
10178 {
10179 /* Avoid the transform if arg1 is a mask of some
10180 mode which allows further optimizations. */
10187 }
10188 }
10190 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10191 ((A & N) + B) & M -> (A + B) & M
10192 Similarly if (N & M) == 0,
10193 ((A | N) + B) & M -> (A + B) & M
10194 and for - instead of + (or unary - instead of +)
10195 and/or ^ instead of |.
10196 If B is constant and (B & M) == 0, fold into A & M. */
10198 {
10207 {
10210 wide_int cst0;
10212 /* Now we know that arg0 is (C + D) or (C - D) or
10213 -C and arg1 (M) is == (1LL << cst) - 1.
10214 Store C into PMOP[0] and D into PMOP[1]. */
10218 {
10221 }
10228 {
10238 {
10241 }
10244 /* If C or D is of the form (A & N) where
10245 (N & M) == M, or of the form (A | N) or
10246 (A ^ N) where (N & M) == 0, replace it with A. */
10250 /* If C or D is a N where (N & M) == 0, it can be
10251 omitted (assumed 0). */
10259 }
10261 /* Only build anything new if we optimized one or both arguments
10262 above. */
10266 {
10269 {
10270 /* Perform the operations in a type that has defined
10271 overflow behavior. */
10277 }
10282 {
10290 else
10292 }
10295 else
10298 /* TEM is now the new binary +, - or unary - replacement. */
10302 }
10303 }
10304 }
10306 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10309 {
10314 return
10316 }
10321 /* Don't touch a floating-point divide by zero unless the mode
10322 of the constant can represent infinity. */
10328 /* (-A) / (-B) -> A / B */
10340 /* Fall through */
10343 /* Simplify A / (B << N) where A and B are positive and B is
10344 a power of 2, to A >> (N + log2(B)). */
10349 {
10352 {
10360 WARN_STRICT_OVERFLOW_MISC);
10366 }
10367 }
10369 /* Fall through */
10377 /* Convert -A / -B to A / B when the type is signed and overflow is
10378 undefined. */
10382 {
10385 "when distributing negation across "
10387 WARN_STRICT_OVERFLOW_MISC);
10392 }
10396 {
10399 "when distributing negation across "
10401 WARN_STRICT_OVERFLOW_MISC);
10406 }
10408 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10409 operation, EXACT_DIV_EXPR.
10411 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10412 At one time others generated faster code, it's not clear if they do
10413 after the last round to changes to the DIV code in expmed.c. */
10424 {
10428 WARN_STRICT_OVERFLOW_MISC);
10430 }
10442 {
10446 WARN_STRICT_OVERFLOW_MISC);
10448 }
10456 /* Since negative shift count is not well-defined,
10457 don't try to compute it in the compiler. */
10463 /* If we have a rotate of a bit operation with the rotate count and
10464 the second operand of the bit operation both constant,
10465 permute the two operations. */
10477 /* Two consecutive rotates adding up to the some integer
10478 multiple of the precision of the type can be ignored. */
10493 /* Note that the operands of this must be ints
10494 and their values must be 0 or 1.
10495 ("true" is a fixed value perhaps depending on the language.) */
10496 /* If first arg is constant zero, return it. */
10500 /* If either arg is constant true, drop it. */
10504 /* Preserve sequence points. */
10507 /* If second arg is constant zero, result is zero, but first arg
10508 must be evaluated. */
10511 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10512 case will be handled here. */
10516 /* !X && X is always false. */
10520 /* X && !X is always false. */
10525 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10526 means A >= Y && A != MAX, but in this case we know that
10527 A < X <= MAX. */
10531 {
10539 }
10548 /* Note that the operands of this must be ints
10549 and their values must be 0 or true.
10550 ("true" is a fixed value perhaps depending on the language.) */
10551 /* If first arg is constant true, return it. */
10555 /* If either arg is constant zero, drop it. */
10559 /* Preserve sequence points. */
10562 /* If second arg is constant true, result is true, but we must
10563 evaluate first arg. */
10566 /* Likewise for first arg, but note this only occurs here for
10567 TRUTH_OR_EXPR. */
10571 /* !X || X is always true. */
10575 /* X || !X is always true. */
10580 /* (X && !Y) || (!X && Y) is X ^ Y */
10583 {
10600 }
10609 /* If the second arg is constant zero, drop it. */
10612 /* If the second arg is constant true, this is a logical inversion. */
10614 {
10617 }
10618 /* Identical arguments cancel to zero. */
10622 /* !X ^ X is always true. */
10627 /* X ^ !X is always true. */
10643 /* bool_var != 1 becomes !bool_var. */
10650 /* bool_var == 0 becomes !bool_var. */
10657 /* !exp != 0 becomes !exp */
10662 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10671 {
10677 }
10679 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10688 {
10694 }
10696 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10704 code == NE_EXPR
10708 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10716 code == NE_EXPR
10720 /* If this is an EQ or NE comparison with zero and ARG0 is
10721 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10722 two operations, but the latter can be done in one less insn
10723 on machines that have only two-operand insns or on which a
10724 constant cannot be the first operand. */
10727 {
10732 {
10739 arg1);
10740 }
10743 {
10750 arg1);
10751 }
10752 }
10754 /* If this is an NE or EQ comparison of zero against the result of a
10755 signed MOD operation whose second operand is a power of 2, make
10756 the MOD operation unsigned since it is simpler and equivalent. */
10764 {
10774 }
10776 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10777 C1 is a valid shift constant, and C2 is a power of two, i.e.
10778 a single bit. */
10782 == INTEGER_CST
10785 {
10790 /* Check for a valid shift count. */
10792 {
10796 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10797 can be rewritten as (X & (C2 << C1)) != 0. */
10799 {
10804 }
10805 /* Otherwise, for signed (arithmetic) shifts,
10806 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10807 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10811 /* Otherwise, of unsigned (logical) shifts,
10812 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10813 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10814 else
10818 arg000);
10819 }
10820 }
10822 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10823 Similarly for NE_EXPR. */
10827 {
10831 tree dandnotc
10834 notc);
10838 }
10840 /* If this is a comparison of a field, we may be able to simplify it. */
10843 /* Handle the constant case even without -O
10844 to make sure the warnings are given. */
10846 {
10850 }
10852 /* Optimize comparisons of strlen vs zero to a compare of the
10853 first character of the string vs zero. To wit,
10854 strlen(ptr) == 0 => *ptr == 0
10855 strlen(ptr) != 0 => *ptr != 0
10856 Other cases should reduce to one of these two (or a constant)
10857 due to the return value of strlen being unsigned. */
10860 {
10868 {
10873 }
10874 }
10876 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10877 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10881 {
10886 {
10888 {
10891 }
10894 }
10895 }
10897 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10898 (X & C) == 0 when C is a single bit. */
10903 {
10910 arg1));
10911 }
10913 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10914 constant C is a power of two, i.e. a single bit. */
10921 {
10925 }
10927 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10928 when is C is a power of two, i.e. a single bit. */
10935 {
10941 }
10945 {
10948 }
10950 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10953 {
10966 arg01),
10975 arg01),
10984 arg00),
10993 arg00),
10995 }
10999 {
11006 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11007 operand_equal_p guarantees no side-effects so we don't need
11008 to use omit_one_operand on Z. */
11012 arg10));
11016 arg11));
11020 arg10));
11024 arg11));
11026 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11029 {
11035 }
11036 }
11038 /* Attempt to simplify equality/inequality comparisons of complex
11039 values. Only lower the comparison if the result is known or
11040 can be simplified to a single scalar comparison. */
11045 {
11050 {
11053 }
11054 else
11055 {
11058 }
11061 {
11064 }
11065 else
11066 {
11069 }
11073 {
11075 {
11080 }
11081 else
11082 {
11087 }
11088 }
11092 {
11094 {
11099 }
11100 else
11101 {
11106 }
11107 }
11108 }
11120 /* Transform comparisons of the form X +- C CMP X. */
11127 {
11134 else
11137 /* (X - c) > X becomes false. */
11141 {
11145 "occur when assuming that (X - c) > X "
11147 WARN_STRICT_OVERFLOW_ALL);
11149 }
11151 /* Likewise (X + c) < X becomes false. */
11155 {
11159 "occur when assuming that "
11161 WARN_STRICT_OVERFLOW_ALL);
11163 }
11165 /* Convert (X - c) <= X to true. */
11170 {
11174 "occur when assuming that "
11176 WARN_STRICT_OVERFLOW_ALL);
11178 }
11180 /* Convert (X + c) >= X to true. */
11185 {
11189 "occur when assuming that "
11191 WARN_STRICT_OVERFLOW_ALL);
11193 }
11196 {
11197 /* Convert X + c > X and X - c < X to true for integers. */
11201 {
11204 "not occur when assuming that "
11206 WARN_STRICT_OVERFLOW_ALL);
11208 }
11213 {
11216 "not occur when assuming that "
11218 WARN_STRICT_OVERFLOW_ALL);
11220 }
11222 /* Convert X + c <= X and X - c >= X to false for integers. */
11226 {
11229 "not occur when assuming that "
11231 WARN_STRICT_OVERFLOW_ALL);
11233 }
11238 {
11241 "not occur when assuming that "
11243 WARN_STRICT_OVERFLOW_ALL);
11245 }
11246 }
11247 }
11249 /* If we are comparing an ABS_EXPR with a constant, we can
11250 convert all the cases into explicit comparisons, but they may
11251 well not be faster than doing the ABS and one comparison.
11252 But ABS (X) <= C is a range comparison, which becomes a subtraction
11253 and a comparison, and is probably faster. */
11267 /* Convert ABS_EXPR<x> >= 0 to true. */
11274 {
11277 "when simplifying comparison of "
11279 WARN_STRICT_OVERFLOW_CONDITIONAL);
11282 arg0);
11283 }
11285 /* Convert ABS_EXPR<x> < 0 to false. */
11290 {
11293 "when simplifying comparison of "
11295 WARN_STRICT_OVERFLOW_CONDITIONAL);
11298 arg0);
11299 }
11301 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11302 and similarly for >= into !=. */
11312 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11313 otherwise Y might be >= # of bits in X's type and thus e.g.
11314 (unsigned char) (1 << Y) for Y 15 might be 0.
11315 If the cast is widening, then 1 << Y should have unsigned type,
11316 otherwise if Y is number of bits in the signed shift type minus 1,
11317 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11318 31 might be 0xffffffff80000000. */
11329 {
11335 }
11347 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11348 {
11360 }
11365 /* When pedantic, a compound expression can be neither an lvalue
11366 nor an integer constant expression. */
11369 /* Don't let (0, 0) be null pointer constant. */
11375 /* An ASSERT_EXPR should never be passed to fold_binary. */
11381 }
11383 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11384 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11385 of GOTO_EXPR. */
11387 static tree
11389 {
11391 {
11398 /* ... fall through ... */
11402 }
11403 }
11405 /* Return whether the sub-tree ST contains a label which is accessible from
11406 outside the sub-tree. */
11408 static bool
11410 {
11411 return
11413 }
11415 /* Fold a ternary expression of code CODE and type TYPE with operands
11416 OP0, OP1, and OP2. Return the folded expression if folding is
11417 successful. Otherwise, return NULL_TREE. */
11419 tree
11422 {
11423 tree tem;
11430 /* If this is a commutative operation, and OP0 is a constant, move it
11431 to OP1 to reduce the number of tests below. */
11440 /* Strip any conversions that don't change the mode. This is safe
11441 for every expression, except for a comparison expression because
11442 its signedness is derived from its operands. So, in the latter
11443 case, only strip conversions that don't change the signedness.
11445 Note that this is done as an internal manipulation within the
11446 constant folder, in order to find the simplest representation of
11447 the arguments so that their form can be studied. In any cases,
11448 the appropriate type conversions should be put back in the tree
11449 that will get out of the constant folder. */
11451 {
11454 }
11457 {
11460 }
11463 {
11466 }
11469 {
11473 {
11479 }
11484 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11485 so all simple results must be passed through pedantic_non_lvalue. */
11487 {
11490 /* Only optimize constant conditions when the selected branch
11491 has the same type as the COND_EXPR. This avoids optimizing
11492 away "c ? x : throw", where the throw has a void type.
11493 Avoid throwing away that operand which contains label. */
11500 }
11502 {
11507 {
11512 {
11520 }
11524 }
11525 }
11527 /* If we have A op B ? A : C, we may be able to convert this to a
11528 simpler expression, depending on the operation and the values
11529 of B and C. Signed zeros prevent all of these transformations,
11530 for reasons given above each one.
11532 Also try swapping the arguments and inverting the conditional. */
11537 {
11541 }
11545 op2,
11548 {
11552 {
11556 }
11557 }
11559 /* If the second operand is simpler than the third, swap them
11560 since that produces better jump optimization results. */
11563 {
11565 /* See if this can be inverted. If it can't, possibly because
11566 it was a floating-point inequality comparison, don't do
11567 anything. */
11571 }
11573 /* Convert A ? 1 : 0 to simply A. */
11578 /* If we try to convert OP0 to our type, the
11579 call to fold will try to move the conversion inside
11580 a COND, which will recurse. In that case, the COND_EXPR
11581 is probably the best choice, so leave it alone. */
11585 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11586 over COND_EXPR in cases such as floating point comparisons. */
11595 arg0)));
11597 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11602 {
11603 /* sign_bit_p looks through both zero and sign extensions,
11604 but for this optimization only sign extensions are
11605 usable. */
11608 {
11611 {
11614 }
11616 }
11617 /* sign_bit_p only checks ARG1 bits within A's precision.
11618 If <sign bit of A> has wider type than A, bits outside
11619 of A's precision in <sign bit of A> need to be checked.
11620 If they are all 0, this optimization needs to be done
11621 in unsigned A's type, if they are all 1 in signed A's type,
11622 otherwise this can't be done. */
11628 {
11630 tree tem_type;
11643 {
11646 }
11648 {
11651 }
11652 else
11654 }
11657 return
11663 arg1)));
11664 }
11666 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11667 already handled above. */
11672 {
11681 }
11683 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11684 is probably obsolete because the first operand should be a
11685 truth value (that's why we have the two cases above), but let's
11686 leave it in until we can confirm this for all front-ends. */
11698 /* Disable the transformations below for vectors, since
11699 fold_binary_op_with_conditional_arg may undo them immediately,
11700 yielding an infinite loop. */
11704 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11713 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11718 {
11720 /* Only perform transformation if ARG0 is easily inverted. */
11724 ? BIT_IOR_EXPR
11727 arg1);
11728 }
11730 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11735 {
11737 /* Only perform transformation if ARG0 is easily inverted. */
11743 op2);
11744 }
11746 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11758 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11759 of fold_ternary on them. */
11769 {
11779 {
11784 {
11792 }
11794 /* Constructor elements can be subvectors. */
11797 {
11801 }
11803 /* We keep an exact subset of the constructor elements. */
11805 {
11811 {
11815 }
11823 CONSTRUCTOR_ELT
11826 }
11827 /* The bitfield references a single constructor element. */
11829 {
11834 else
11838 }
11839 }
11840 }
11842 /* A bit-field-ref that referenced the full argument can be stripped. */
11848 /* On constants we can use native encode/interpret to constant
11849 fold (nearly) all BIT_FIELD_REFs. */
11853 /* This limitation should not be necessary, we just need to
11854 round this up to mode size. */
11856 /* Need bit-shifting of the buffer to relax the following. */
11858 {
11863 /* ??? We cannot tell native_encode_expr to start at
11864 some random byte only. So limit us to a reasonable amount
11865 of work. */
11867 {
11872 {
11878 }
11879 }
11880 }
11885 /* For integers we can decompose the FMA if possible. */
11897 {
11913 {
11918 /* Make sure that the perm value is in an acceptable
11919 range. */
11928 else
11933 }
11936 {
11941 }
11946 {
11951 }
11957 {
11961 }
11966 /* Some targets are deficient and fail to expand a single
11967 argument permutation while still allowing an equivalent
11968 2-argument version. */
11972 {
11975 }
11978 {
11985 }
11989 }
11995 }
11997 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11998 of an array (or vector). */
12000 tree
12002 {
12007 {
12010 {
12011 /* Static constructors for variably sized objects makes no sense. */
12015 }
12016 }
12027 offset_int max_index;
12032 {
12033 /* Array constructor might explicitly set index, or specify a range,
12034 or leave index NULL meaning that it is next index after previous
12035 one. */
12037 {
12040 else
12041 {
12045 }
12046 }
12047 else
12048 {
12054 }
12056 /* Do we have match? */
12060 }
12062 }
12064 /* Perform constant folding and related simplification of EXPR.
12065 The related simplifications include x*1 => x, x*0 => 0, etc.,
12066 and application of the associative law.
12067 NOP_EXPR conversions may be removed freely (as long as we
12068 are careful not to change the type of the overall expression).
12069 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12070 but we can constant-fold them if they have constant operands. */
12072 #ifdef ENABLE_FOLD_CHECKING
12073 # define fold(x) fold_1 (x)
12075 static
12076 #endif
12077 tree
12079 {
12083 tree tem;
12086 /* Return right away if a constant. */
12090 /* CALL_EXPR-like objects with variable numbers of operands are
12091 treated specially. */
12093 {
12095 {
12098 }
12100 }
12103 {
12108 {
12126 }
12127 }
12130 {
12132 {
12139 {
12144 }
12147 }
12149 /* Return a VECTOR_CST if possible. */
12151 {
12157 tree val;
12163 }
12171 }
12173 #ifdef ENABLE_FOLD_CHECKING
12174 #undef fold
12181 /* When --enable-checking=fold, compute a digest of expr before
12182 and after actual fold call to see if fold did not accidentally
12183 change original expr. */
12185 tree
12187 {
12188 tree ret;
12208 }
12210 void
12212 {
12223 }
12225 static void
12227 {
12229 }
12231 static void
12234 {
12240 recursive_label:
12250 {
12251 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12256 }
12263 {
12264 /* Allow these fields to be modified. */
12265 tree tmp;
12273 {
12276 }
12277 }
12288 {
12291 {
12306 }
12310 {
12323 }
12340 {
12346 }
12349 {
12351 {
12354 }
12356 }
12367 {
12370 }
12380 }
12381 }
12383 /* Helper function for outputting the checksum of a tree T. When
12384 debugging with gdb, you can "define mynext" to be "next" followed
12385 by "call debug_fold_checksum (op0)", then just trace down till the
12386 outputs differ. */
12388 DEBUG_FUNCTION void
12390 {
12405 }
12407 #endif
12409 /* Fold a unary tree expression with code CODE of type TYPE with an
12410 operand OP0. LOC is the location of the resulting expression.
12411 Return a folded expression if successful. Otherwise, return a tree
12412 expression with code CODE of type TYPE with an operand OP0. */
12414 tree
12417 {
12418 tree tem;
12419 #ifdef ENABLE_FOLD_CHECKING
12428 #endif
12434 #ifdef ENABLE_FOLD_CHECKING
12441 #endif
12443 }
12445 /* Fold a binary tree expression with code CODE of type TYPE with
12446 operands OP0 and OP1. LOC is the location of the resulting
12447 expression. Return a folded expression if successful. Otherwise,
12448 return a tree expression with code CODE of type TYPE with operands
12449 OP0 and OP1. */
12451 tree
12454 MEM_STAT_DECL)
12455 {
12456 tree tem;
12457 #ifdef ENABLE_FOLD_CHECKING
12474 #endif
12480 #ifdef ENABLE_FOLD_CHECKING
12495 #endif
12497 }
12499 /* Fold a ternary tree expression with code CODE of type TYPE with
12500 operands OP0, OP1, and OP2. Return a folded expression if
12501 successful. Otherwise, return a tree expression with code CODE of
12502 type TYPE with operands OP0, OP1, and OP2. */
12504 tree
12507 {
12508 tree tem;
12509 #ifdef ENABLE_FOLD_CHECKING
12533 #endif
12540 #ifdef ENABLE_FOLD_CHECKING
12563 #endif
12565 }
12567 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12568 arguments in ARGARRAY, and a null static chain.
12569 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12570 of type TYPE from the given operands as constructed by build_call_array. */
12572 tree
12575 {
12576 tree tem;
12577 #ifdef ENABLE_FOLD_CHECKING
12596 #endif
12602 #ifdef ENABLE_FOLD_CHECKING
12618 #endif
12620 }
12622 /* Perform constant folding and related simplification of initializer
12623 expression EXPR. These behave identically to "fold_buildN" but ignore
12624 potential run-time traps and exceptions that fold must preserve. */
12626 #define START_FOLD_INIT \
12627 int saved_signaling_nans = flag_signaling_nans;\
12628 int saved_trapping_math = flag_trapping_math;\
12629 int saved_rounding_math = flag_rounding_math;\
12630 int saved_trapv = flag_trapv;\
12631 int saved_folding_initializer = folding_initializer;\
12632 flag_signaling_nans = 0;\
12633 flag_trapping_math = 0;\
12634 flag_rounding_math = 0;\
12635 flag_trapv = 0;\
12636 folding_initializer = 1;
12638 #define END_FOLD_INIT \
12639 flag_signaling_nans = saved_signaling_nans;\
12640 flag_trapping_math = saved_trapping_math;\
12641 flag_rounding_math = saved_rounding_math;\
12642 flag_trapv = saved_trapv;\
12643 folding_initializer = saved_folding_initializer;
12645 tree
12648 {
12649 tree result;
12650 START_FOLD_INIT;
12654 END_FOLD_INIT;
12656 }
12658 tree
12661 {
12662 tree result;
12663 START_FOLD_INIT;
12667 END_FOLD_INIT;
12669 }
12671 tree
12674 {
12675 tree result;
12676 START_FOLD_INIT;
12680 END_FOLD_INIT;
12682 }
12684 #undef START_FOLD_INIT
12685 #undef END_FOLD_INIT
12687 /* Determine if first argument is a multiple of second argument. Return 0 if
12688 it is not, or we cannot easily determined it to be.
12690 An example of the sort of thing we care about (at this point; this routine
12691 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12692 fold cases do now) is discovering that
12694 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12696 is a multiple of
12698 SAVE_EXPR (J * 8)
12700 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12702 This code also handles discovering that
12704 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12706 is a multiple of 8 so we don't have to worry about dealing with a
12707 possible remainder.
12709 Note that we *look* inside a SAVE_EXPR only to determine how it was
12710 calculated; it is not safe for fold to do much of anything else with the
12711 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12712 at run time. For example, the latter example above *cannot* be implemented
12713 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12714 evaluation time of the original SAVE_EXPR is not necessarily the same at
12715 the time the new expression is evaluated. The only optimization of this
12716 sort that would be valid is changing
12718 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12720 divided by 8 to
12722 SAVE_EXPR (I) * SAVE_EXPR (J)
12724 (where the same SAVE_EXPR (J) is used in the original and the
12725 transformed version). */
12727 int
12729 {
12737 {
12739 /* Bitwise and provides a power of two multiple. If the mask is
12740 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12743 /* FALLTHRU */
12756 {
12760 /* const_binop may not detect overflow correctly,
12761 so check for it explicitly here. */
12765 size_one_node,
12766 op1)))
12769 }
12773 /* Can't handle conversions from non-integral or wider integral type. */
12779 /* .. fall through ... */
12796 SIGNED);
12800 }
12801 }
12803 #define tree_expr_nonnegative_warnv_p(X, Y) \
12806 #define RECURSE(X) \
12807 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12809 /* Return true if CODE or TYPE is known to be non-negative. */
12811 static bool
12813 {
12816 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12817 have a signed:1 type (where the value is -1 and 0). */
12820 }
12822 /* Return true if (CODE OP0) is known to be non-negative. If the return
12823 value is based on the assumption that signed overflow is undefined,
12824 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12825 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12827 bool
12830 {
12835 {
12837 /* We can't return 1 if flag_wrapv is set because
12838 ABS_EXPR<INT_MIN> = INT_MIN. */
12842 {
12845 }
12853 CASE_CONVERT:
12854 {
12859 {
12863 {
12867 }
12868 }
12870 {
12876 }
12877 }
12882 }
12884 /* We don't know sign of `t', so be conservative and return false. */
12886 }
12888 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12889 value is based on the assumption that signed overflow is undefined,
12890 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12891 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12893 bool
12897 {
12902 {
12908 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12909 both unsigned and at least 2 bits shorter than the result. */
12913 {
12918 {
12922 }
12923 }
12928 {
12929 /* x * x is always non-negative for floating point x
12930 or without overflow. */
12933 {
12938 }
12939 }
12941 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12942 both unsigned and their total bits is shorter than the result. */
12946 {
12965 {
12975 }
12976 }
13003 }
13005 /* We don't know sign of `t', so be conservative and return false. */
13007 }
13009 /* Return true if T is known to be non-negative. If the return
13010 value is based on the assumption that signed overflow is undefined,
13011 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13012 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13014 bool
13016 {
13021 {
13035 /* Limit the depth of recursion to avoid quadratic behavior.
13036 This is expected to catch almost all occurrences in practice.
13037 If this code misses important cases that unbounded recursion
13038 would not, passes that need this information could be revised
13039 to provide it through dataflow propagation. */
13047 }
13048 }
13050 /* Return true if T is known to be non-negative. If the return
13051 value is based on the assumption that signed overflow is undefined,
13052 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13053 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13055 bool
13058 {
13060 {
13061 CASE_CFN_ACOS:
13062 CASE_CFN_ACOSH:
13063 CASE_CFN_CABS:
13064 CASE_CFN_COSH:
13065 CASE_CFN_ERFC:
13066 CASE_CFN_EXP:
13067 CASE_CFN_EXP10:
13068 CASE_CFN_EXP2:
13069 CASE_CFN_FABS:
13070 CASE_CFN_FDIM:
13071 CASE_CFN_HYPOT:
13072 CASE_CFN_POW10:
13073 CASE_CFN_FFS:
13074 CASE_CFN_PARITY:
13075 CASE_CFN_POPCOUNT:
13076 CASE_CFN_CLZ:
13077 CASE_CFN_CLRSB:
13080 /* Always true. */
13083 CASE_CFN_SQRT:
13084 /* sqrt(-0.0) is -0.0. */
13089 CASE_CFN_ASINH:
13090 CASE_CFN_ATAN:
13091 CASE_CFN_ATANH:
13092 CASE_CFN_CBRT:
13093 CASE_CFN_CEIL:
13094 CASE_CFN_ERF:
13095 CASE_CFN_EXPM1:
13096 CASE_CFN_FLOOR:
13097 CASE_CFN_FMOD:
13098 CASE_CFN_FREXP:
13099 CASE_CFN_ICEIL:
13100 CASE_CFN_IFLOOR:
13101 CASE_CFN_IRINT:
13102 CASE_CFN_IROUND:
13103 CASE_CFN_LCEIL:
13104 CASE_CFN_LDEXP:
13105 CASE_CFN_LFLOOR:
13106 CASE_CFN_LLCEIL:
13107 CASE_CFN_LLFLOOR:
13108 CASE_CFN_LLRINT:
13109 CASE_CFN_LLROUND:
13110 CASE_CFN_LRINT:
13111 CASE_CFN_LROUND:
13112 CASE_CFN_MODF:
13113 CASE_CFN_NEARBYINT:
13114 CASE_CFN_RINT:
13115 CASE_CFN_ROUND:
13116 CASE_CFN_SCALB:
13117 CASE_CFN_SCALBLN:
13118 CASE_CFN_SCALBN:
13119 CASE_CFN_SIGNBIT:
13120 CASE_CFN_SIGNIFICAND:
13121 CASE_CFN_SINH:
13122 CASE_CFN_TANH:
13123 CASE_CFN_TRUNC:
13124 /* True if the 1st argument is nonnegative. */
13127 CASE_CFN_FMAX:
13128 /* True if the 1st OR 2nd arguments are nonnegative. */
13131 CASE_CFN_FMIN:
13132 /* True if the 1st AND 2nd arguments are nonnegative. */
13135 CASE_CFN_COPYSIGN:
13136 /* True if the 2nd argument is nonnegative. */
13139 CASE_CFN_POWI:
13140 /* True if the 1st argument is nonnegative or the second
13141 argument is an even integer. */
13147 CASE_CFN_POW:
13148 /* True if the 1st argument is nonnegative or the second
13149 argument is an even integer valued real. */
13151 {
13152 REAL_VALUE_TYPE c;
13153 HOST_WIDE_INT n;
13158 {
13159 REAL_VALUE_TYPE cint;
13163 }
13164 }
13169 }
13171 }
13173 /* Return true if T is known to be non-negative. If the return
13174 value is based on the assumption that signed overflow is undefined,
13175 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13176 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13178 static bool
13180 {
13186 {
13188 {
13192 /* If the initializer is non-void, then it's a normal expression
13193 that will be assigned to the slot. */
13197 /* Otherwise, the initializer sets the slot in some way. One common
13198 way is an assignment statement at the end of the initializer. */
13200 {
13208 else
13210 }
13216 }
13219 {
13225 arg0,
13226 arg1,
13228 }
13241 }
13242 }
13244 #undef RECURSE
13245 #undef tree_expr_nonnegative_warnv_p
13247 /* Return true if T is known to be non-negative. If the return
13248 value is based on the assumption that signed overflow is undefined,
13249 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13250 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13252 bool
13254 {
13261 {
13283 }
13286 {
13312 }
13313 }
13315 /* Return true if `t' is known to be non-negative. Handle warnings
13316 about undefined signed overflow. */
13318 bool
13320 {
13327 "determining that expression is always "
13329 WARN_STRICT_OVERFLOW_MISC);
13331 }
13334 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13335 For floating point we further ensure that T is not denormal.
13336 Similar logic is present in nonzero_address in rtlanal.h.
13338 If the return value is based on the assumption that signed overflow
13339 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13340 change *STRICT_OVERFLOW_P. */
13342 bool
13345 {
13347 {
13350 strict_overflow_p);
13353 {
13359 strict_overflow_p));
13360 }
13365 strict_overflow_p);
13369 }
13372 }
13374 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13375 For floating point we further ensure that T is not denormal.
13376 Similar logic is present in nonzero_address in rtlanal.h.
13378 If the return value is based on the assumption that signed overflow
13379 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13380 change *STRICT_OVERFLOW_P. */
13382 bool
13384 tree type,
13385 tree op0,
13387 {
13390 {
13394 {
13395 /* With the presence of negative values it is hard
13396 to say something. */
13403 /* One of operands must be positive and the other non-negative. */
13404 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13405 overflows, on a twos-complement machine the sum of two
13406 nonnegative numbers can never be zero. */
13408 strict_overflow_p)
13410 strict_overflow_p));
13411 }
13416 {
13418 strict_overflow_p)
13420 strict_overflow_p))
13421 {
13424 }
13425 }
13434 {
13437 }
13444 {
13448 /* When both operands are nonzero, then MAX must be too. */
13450 strict_overflow_p))
13453 /* MAX where operand 0 is positive is positive. */
13455 strict_overflow_p);
13456 }
13457 /* MAX where operand 1 is positive is positive. */
13462 {
13466 }
13471 strict_overflow_p)
13473 strict_overflow_p));
13477 }
13480 }
13482 /* Return true when T is an address and is known to be nonzero.
13483 For floating point we further ensure that T is not denormal.
13484 Similar logic is present in nonzero_address in rtlanal.h.
13486 If the return value is based on the assumption that signed overflow
13487 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13488 change *STRICT_OVERFLOW_P. */
13490 bool
13492 {
13495 {
13500 {
13509 /* For objects in symbol table check if we know they are non-zero.
13510 Don't do anything for variables and functions before symtab is built;
13511 it is quite possible that they will be declared weak later. */
13513 {
13519 else
13521 }
13523 /* Function local objects are never NULL. */
13530 /* Constants are never weak. */
13535 }
13543 {
13547 }
13552 }
13554 }
13556 #define integer_valued_real_p(X) \
13559 #define RECURSE(X) \
13560 ((integer_valued_real_p) (X, depth + 1))
13562 /* Return true if the floating point result of (CODE OP0) has an
13563 integer value. We also allow +Inf, -Inf and NaN to be considered
13564 integer values. Return false for signaling NaN.
13566 DEPTH is the current nesting depth of the query. */
13568 bool
13570 {
13572 {
13579 CASE_CONVERT:
13580 {
13587 }
13591 }
13593 }
13595 /* Return true if the floating point result of (CODE OP0 OP1) has an
13596 integer value. We also allow +Inf, -Inf and NaN to be considered
13597 integer values. Return false for signaling NaN.
13599 DEPTH is the current nesting depth of the query. */
13601 bool
13603 {
13605 {
13615 }
13617 }
13619 /* Return true if the floating point result of calling FNDECL with arguments
13620 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13621 considered integer values. Return false for signaling NaN. If FNDECL
13622 takes fewer than 2 arguments, the remaining ARGn are null.
13624 DEPTH is the current nesting depth of the query. */
13626 bool
13628 {
13630 {
13631 CASE_CFN_CEIL:
13632 CASE_CFN_FLOOR:
13633 CASE_CFN_NEARBYINT:
13634 CASE_CFN_RINT:
13635 CASE_CFN_ROUND:
13636 CASE_CFN_TRUNC:
13639 CASE_CFN_FMIN:
13640 CASE_CFN_FMAX:
13645 }
13647 }
13649 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13650 has an integer value. We also allow +Inf, -Inf and NaN to be
13651 considered integer values. Return false for signaling NaN.
13653 DEPTH is the current nesting depth of the query. */
13655 bool
13657 {
13659 {
13667 /* Limit the depth of recursion to avoid quadratic behavior.
13668 This is expected to catch almost all occurrences in practice.
13669 If this code misses important cases that unbounded recursion
13670 would not, passes that need this information could be revised
13671 to provide it through dataflow propagation. */
13675 depth));
13679 }
13681 }
13683 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13684 has an integer value. We also allow +Inf, -Inf and NaN to be
13685 considered integer values. Return false for signaling NaN.
13687 DEPTH is the current nesting depth of the query. */
13689 static bool
13691 {
13693 {
13704 }
13706 }
13708 #undef RECURSE
13709 #undef integer_valued_real_p
13711 /* Return true if the floating point expression T has an integer value.
13712 We also allow +Inf, -Inf and NaN to be considered integer values.
13713 Return false for signaling NaN.
13715 DEPTH is the current nesting depth of the query. */
13717 bool
13719 {
13725 {
13741 }
13744 {
13750 {
13759 }
13763 }
13764 }
13766 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13767 attempt to fold the expression to a constant without modifying TYPE,
13768 OP0 or OP1.
13770 If the expression could be simplified to a constant, then return
13771 the constant. If the expression would not be simplified to a
13772 constant, then return NULL_TREE. */
13774 tree
13776 {
13779 }
13781 /* Given the components of a unary expression CODE, TYPE and OP0,
13782 attempt to fold the expression to a constant without modifying
13783 TYPE or OP0.
13785 If the expression could be simplified to a constant, then return
13786 the constant. If the expression would not be simplified to a
13787 constant, then return NULL_TREE. */
13789 tree
13791 {
13794 }
13796 /* If EXP represents referencing an element in a constant string
13797 (either via pointer arithmetic or array indexing), return the
13798 tree representing the value accessed, otherwise return NULL. */
13800 tree
13802 {
13806 {
13808 tree index;
13809 tree string;
13814 else
13815 {
13819 /* Optimize the special-case of a zero lower bound.
13821 We convert the low_bound to sizetype to avoid some problems
13822 with constant folding. (E.g. suppose the lower bound is 1,
13823 and its mode is QI. Without the conversion,l (ARRAY
13824 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13825 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13831 }
13844 }
13846 }
13848 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13849 an integer constant, real, or fixed-point constant.
13851 TYPE is the type of the result. */
13853 static tree
13855 {
13859 {
13861 {
13868 }
13875 {
13876 FIXED_VALUE_TYPE f;
13881 /* Propagate overflow flags. */
13885 }
13889 }
13892 }
13894 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13895 an integer constant or real constant.
13897 TYPE is the type of the result. */
13899 tree
13901 {
13905 {
13907 {
13908 /* If the value is unsigned or non-negative, then the absolute value
13909 is the same as the ordinary value. */
13913 /* If the value is negative, then the absolute value is
13914 its negation. */
13915 else
13916 {
13921 }
13922 }
13928 else
13934 }
13937 }
13939 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13940 constant. TYPE is the type of the result. */
13942 static tree
13944 {
13948 }
13950 /* Given CODE, a relational operator, the target type, TYPE and two
13951 constant operands OP0 and OP1, return the result of the
13952 relational operation. If the result is not a compile time
13953 constant, then return NULL_TREE. */
13955 static tree
13957 {
13960 /* From here on, the only cases we handle are when the result is
13961 known to be a constant. */
13964 {
13968 /* Handle the cases where either operand is a NaN. */
13970 {
13972 {
14000 }
14003 }
14006 }
14009 {
14013 }
14015 /* Handle equality/inequality of complex constants. */
14017 {
14028 else
14030 }
14033 {
14035 {
14036 /* Have vector comparison with scalar boolean result. */
14041 {
14046 }
14050 }
14057 {
14069 }
14072 }
14074 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14076 To compute GT, swap the arguments and do LT.
14077 To compute GE, do LT and invert the result.
14078 To compute LE, swap the arguments, do LT and invert the result.
14079 To compute NE, do EQ and invert the result.
14081 Therefore, the code below must handle only EQ and LT. */
14084 {
14087 }
14089 /* Note that it is safe to invert for real values here because we
14090 have already handled the one case that it matters. */
14094 {
14097 }
14099 /* Compute a result for LT or EQ if args permit;
14100 Otherwise return T. */
14102 {
14105 else
14107 }
14108 else
14114 }
14116 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14117 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14118 itself. */
14120 tree
14122 {
14123 /* If the expression does not have side effects then we don't have to wrap
14124 it with a cleanup point expression. */
14128 /* If the expression is a return, check to see if the expression inside the
14129 return has no side effects or the right hand side of the modify expression
14130 inside the return. If either don't have side effects set we don't need to
14131 wrap the expression in a cleanup point expression. Note we don't check the
14132 left hand side of the modify because it should always be a return decl. */
14134 {
14141 }
14144 }
14146 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14147 of an indirection through OP0, or NULL_TREE if no simplification is
14148 possible. */
14150 tree
14152 {
14154 tree subtype;
14162 {
14165 /* *&CONST_DECL -> to the value of the const decl. */
14168 /* *&p => p; make sure to handle *&"str"[cst] here. */
14170 {
14174 else
14176 }
14177 /* *(foo *)&fooarray => fooarray[0] */
14180 && (!in_gimple_form
14182 {
14192 }
14193 /* *(foo *)&complexfoo => __real__ complexfoo */
14197 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14200 {
14204 }
14205 }
14209 {
14215 {
14216 tree op00type;
14220 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14223 {
14225 unsigned HOST_WIDE_INT max_offset
14230 {
14237 }
14238 }
14239 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14242 {
14246 }
14247 /* ((foo *)&fooarray)[1] => fooarray[1] */
14250 {
14260 }
14261 }
14262 }
14264 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14267 && (!in_gimple_form
14269 {
14270 tree type_domain;
14280 NULL_TREE);
14281 }
14284 }
14286 /* Builds an expression for an indirection through T, simplifying some
14287 cases. */
14289 tree
14291 {
14299 }
14301 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14303 tree
14305 {
14310 else
14312 }
14314 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14315 whose result is ignored. The type of the returned tree need not be
14316 the same as the original expression. */
14318 tree
14320 {
14326 {
14337 else
14343 {
14359 }
14364 }
14365 }
14367 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14369 tree
14371 {
14377 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14378 have to do anything. Only do this when we are not given a const,
14379 because in that case, this check is more expensive than just
14380 doing it. */
14382 {
14387 }
14389 /* If divisor is a power of two, simplify this to bit manipulation. */
14391 {
14393 {
14407 }
14408 else
14409 {
14410 tree t;
14416 }
14417 }
14418 else
14419 {
14424 }
14427 }
14429 /* Likewise, but round down. */
14431 tree
14433 {
14440 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14441 have to do anything. Only do this when we are not given a const,
14442 because in that case, this check is more expensive than just
14443 doing it. */
14445 {
14450 }
14452 /* If divisor is a power of two, simplify this to bit manipulation. */
14454 {
14455 tree t;
14459 }
14460 else
14461 {
14466 }
14469 }
14471 /* Returns the pointer to the base of the object addressed by EXP and
14472 extracts the information about the offset of the access, storing it
14473 to PBITPOS and POFFSET. */
14475 static tree
14478 {
14479 tree core;
14480 machine_mode mode;
14482 HOST_WIDE_INT bitsize;
14486 {
14491 }
14492 else
14493 {
14497 }
14500 }
14502 /* Returns true if addresses of E1 and E2 differ by a constant, false
14503 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14505 bool
14507 {
14521 {
14531 }
14533 {
14534 /* If only one of the offsets is non-constant, the difference cannot
14535 be a constant. */
14537 }
14538 else
14543 }
14545 /* Return OFF converted to a pointer offset type suitable as offset for
14546 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14547 tree
14549 {
14551 }
14553 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14554 tree
14556 {
14559 }
14561 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14562 tree
14564 {
14567 }
14569 /* Return a char pointer for a C string if it is a string constant
14570 or sum of string constant and integer constant. */
14574 {
14575 tree offset_node;
14588 }