| blob | 65c75f639315d620eddfef3d8362b4902d28440a |
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. */
82 #ifndef LOAD_EXTEND_OP
83 #define LOAD_EXTEND_OP(M) UNKNOWN
84 #endif
86 /* Nonzero if we are folding constants inside an initializer; zero
87 otherwise. */
90 /* The following constants represent a bit based encoding of GCC's
91 comparison operators. This encoding simplifies transformations
92 on relational comparison operators, such as AND and OR. */
110 };
148 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
149 Otherwise, return LOC. */
151 static location_t
153 {
156 }
158 /* Similar to protected_set_expr_location, but never modify x in place,
159 if location can and needs to be set, unshare it. */
163 {
169 {
172 }
174 }
175 \f
176 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
177 division and returns the quotient. Otherwise returns
178 NULL_TREE. */
180 tree
182 {
183 widest_int quo;
190 }
191 \f
192 /* This is nonzero if we should defer warnings about undefined
193 overflow. This facility exists because these warnings are a
194 special case. The code to estimate loop iterations does not want
195 to issue any warnings, since it works with expressions which do not
196 occur in user code. Various bits of cleanup code call fold(), but
197 only use the result if it has certain characteristics (e.g., is a
198 constant); that code only wants to issue a warning if the result is
199 used. */
203 /* If a warning about undefined overflow is deferred, this is the
204 warning. Note that this may cause us to turn two warnings into
205 one, but that is fine since it is sufficient to only give one
206 warning per expression. */
210 /* If a warning about undefined overflow is deferred, this is the
211 level at which the warning should be emitted. */
215 /* Start deferring overflow warnings. We could use a stack here to
216 permit nested calls, but at present it is not necessary. */
218 void
220 {
222 }
224 /* Stop deferring overflow warnings. If there is a pending warning,
225 and ISSUE is true, then issue the warning if appropriate. STMT is
226 the statement with which the warning should be associated (used for
227 location information); STMT may be NULL. CODE is the level of the
228 warning--a warn_strict_overflow_code value. This function will use
229 the smaller of CODE and the deferred code when deciding whether to
230 issue the warning. CODE may be zero to mean to always use the
231 deferred code. */
233 void
235 {
237 location_t locus;
242 {
248 }
259 /* Use the smallest code level when deciding to issue the
260 warning. */
269 else
272 }
274 /* Stop deferring overflow warnings, ignoring any deferred
275 warnings. */
277 void
279 {
281 }
283 /* Whether we are deferring overflow warnings. */
285 bool
287 {
289 }
291 /* This is called when we fold something based on the fact that signed
292 overflow is undefined. */
294 void
296 {
298 {
301 {
304 }
305 }
308 }
309 \f
310 /* Return true if the built-in mathematical function specified by CODE
311 is odd, i.e. -f(x) == f(-x). */
313 bool
315 {
317 {
318 CASE_CFN_ASIN:
319 CASE_CFN_ASINH:
320 CASE_CFN_ATAN:
321 CASE_CFN_ATANH:
322 CASE_CFN_CASIN:
323 CASE_CFN_CASINH:
324 CASE_CFN_CATAN:
325 CASE_CFN_CATANH:
326 CASE_CFN_CBRT:
327 CASE_CFN_CPROJ:
328 CASE_CFN_CSIN:
329 CASE_CFN_CSINH:
330 CASE_CFN_CTAN:
331 CASE_CFN_CTANH:
332 CASE_CFN_ERF:
333 CASE_CFN_LLROUND:
334 CASE_CFN_LROUND:
335 CASE_CFN_ROUND:
336 CASE_CFN_SIN:
337 CASE_CFN_SINH:
338 CASE_CFN_TAN:
339 CASE_CFN_TANH:
340 CASE_CFN_TRUNC:
343 CASE_CFN_LLRINT:
344 CASE_CFN_LRINT:
345 CASE_CFN_NEARBYINT:
346 CASE_CFN_RINT:
351 }
353 }
355 /* Check whether we may negate an integer constant T without causing
356 overflow. */
358 bool
360 {
361 tree type;
370 }
372 /* Determine whether an expression T can be cheaply negated using
373 the function negate_expr without introducing undefined overflow. */
375 static bool
377 {
378 tree type;
387 {
392 /* Check that -CST will not overflow type. */
405 /* We want to canonicalize to positive real constants. Pretend
406 that only negative ones can be easily negated. */
414 {
425 }
440 /* -(A + B) -> (-B) - A. */
445 /* -(A + B) -> (-A) - B. */
449 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
460 /* INT_MIN/n * n doesn't overflow while negating one operand it does
461 if n is a power of two. */
470 /* Fall through. */
485 /* In general we can't negate B in A / B, because if A is INT_MIN and
486 B is 1, we may turn this into INT_MIN / -1 which is undefined
487 and actually traps on some architectures. */
496 /* Negate -((double)float) as (double)(-float). */
498 {
502 }
506 /* Negate -f(x) as f(-x). */
512 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
514 {
518 }
523 }
525 }
527 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
528 simplification is possible.
529 If negate_expr_p would return true for T, NULL_TREE will never be
530 returned. */
532 static tree
534 {
536 tree tem;
539 {
540 /* Convert - (~A) to A + 1. */
566 {
571 }
575 {
580 {
584 }
587 }
610 {
611 /* -(A + B) -> (-B) - A. */
615 {
619 }
621 /* -(A + B) -> (-A) - B. */
623 {
627 }
628 }
632 /* - (A - B) -> B - A */
644 /* Fall through. */
648 {
657 }
669 /* In general we can't negate B in A / B, because if A is INT_MIN and
670 B is 1, we may turn this into INT_MIN / -1 which is undefined
671 and actually traps on some architectures. */
683 /* Convert -((double)float) into (double)(-float). */
685 {
689 }
693 /* Negate -f(x) as f(-x). */
696 {
702 }
706 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
708 {
711 {
718 }
719 }
724 }
727 }
729 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
730 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
731 return NULL_TREE. */
733 static tree
735 {
737 location_t loc;
750 }
751 \f
752 /* Split a tree IN into a constant, literal and variable parts that could be
753 combined with CODE to make IN. "constant" means an expression with
754 TREE_CONSTANT but that isn't an actual constant. CODE must be a
755 commutative arithmetic operation. Store the constant part into *CONP,
756 the literal in *LITP and return the variable part. If a part isn't
757 present, set it to null. If the tree does not decompose in this way,
758 return the entire tree as the variable part and the other parts as null.
760 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
761 case, we negate an operand that was subtracted. Except if it is a
762 literal for which we use *MINUS_LITP instead.
764 If NEGATE_P is true, we are negating all of IN, again except a literal
765 for which we use *MINUS_LITP instead. If a variable part is of pointer
766 type, it is negated after converting to TYPE. This prevents us from
767 generating illegal MINUS pointer expression. LOC is the location of
768 the converted variable part.
770 If IN is itself a literal or constant, return it as appropriate.
772 Note that we do not guarantee that any of the three values will be the
773 same type as IN, but they will have the same signedness and mode. */
775 static tree
778 {
785 /* Strip any conversions that don't change the machine mode or signedness. */
794 /* We can associate addition and subtraction together (even
795 though the C standard doesn't say so) for integers because
796 the value is not affected. For reals, the value might be
797 affected, so we can't. */
800 {
806 /* First see if either of the operands is a literal, then a constant. */
819 /* If we haven't dealt with either operand, this is not a case we can
820 decompose. Otherwise, VAR is either of the ones remaining, if any. */
825 else
828 /* Now do any needed negations. */
834 {
835 /* Convert to TYPE before negating. */
838 }
839 }
844 {
845 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
846 when IN is constant. */
849 }
850 else
854 {
861 {
862 /* Convert to TYPE before negating. */
865 }
866 }
869 }
871 /* Re-associate trees split by the above function. T1 and T2 are
872 either expressions to associate or null. Return the new
873 expression, if any. LOC is the location of the new expression. If
874 we build an operation, do it in TYPE and with CODE. */
876 static tree
878 {
884 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
885 try to fold this since we will have infinite recursion. But do
886 deal with any NEGATE_EXPRs. */
889 {
891 {
904 }
906 {
909 }
913 }
917 }
918 \f
919 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
920 for use in int_const_binop, size_binop and size_diffop. */
922 static bool
924 {
931 {
940 }
945 }
948 /* Combine two integer constants ARG1 and ARG2 under operation CODE
949 to produce a new constant. Return NULL_TREE if we don't know how
950 to evaluate CODE at compile-time. */
952 static tree
955 {
956 wide_int res;
957 tree t;
965 {
981 {
985 else
987 }
990 /* It's unclear from the C standard whether shifts can overflow.
991 The following code ignores overflow; perhaps a C standard
992 interpretation ruling is needed. */
994 else
1001 {
1005 else
1007 }
1011 else
1090 }
1098 }
1100 tree
1102 {
1104 }
1106 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1107 constant. We assume ARG1 and ARG2 have the same data type, or at least
1108 are the same kind of constant and the same machine mode. Return zero if
1109 combining the constants is not allowed in the current operating mode. */
1111 static tree
1113 {
1114 /* Sanity check for the recursive cases. */
1122 {
1128 }
1131 {
1132 machine_mode mode;
1133 REAL_VALUE_TYPE d1;
1134 REAL_VALUE_TYPE d2;
1135 REAL_VALUE_TYPE value;
1136 REAL_VALUE_TYPE result;
1140 /* The following codes are handled by real_arithmetic. */
1142 {
1153 }
1161 /* Don't perform operation if we honor signaling NaNs and
1162 either operand is a signaling NaN. */
1168 /* Don't perform operation if it would raise a division
1169 by zero exception. */
1175 /* If either operand is a NaN, just return it. Otherwise, set up
1176 for floating-point trap; we return an overflow. */
1178 {
1179 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1180 is off. */
1184 }
1186 {
1187 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1188 is off. */
1192 }
1197 /* Don't constant fold this floating point operation if
1198 the result has overflowed and flag_trapping_math. */
1206 /* Don't constant fold this floating point operation if the
1207 result may dependent upon the run-time rounding mode and
1208 flag_rounding_math is set, or if GCC's software emulation
1209 is unable to accurately represent the result. */
1219 }
1222 {
1223 FIXED_VALUE_TYPE f1;
1224 FIXED_VALUE_TYPE f2;
1225 FIXED_VALUE_TYPE result;
1230 /* The following codes are handled by fixed_arithmetic. */
1232 {
1244 {
1251 }
1256 }
1263 /* Propagate overflow flags. */
1267 }
1270 {
1279 {
1290 mpc_mul);
1304 mpc_div);
1305 /* Fallthru. */
1311 {
1312 /* Keep this algorithm in sync with
1313 tree-complex.c:expand_complex_div_straight().
1315 Expand complex division to scalars, straightforward algorithm.
1316 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1317 t = br*br + bi*bi
1318 */
1319 tree magsquared
1323 tree t1
1327 tree t2
1334 }
1335 else
1336 {
1337 /* Keep this algorithm in sync with
1338 tree-complex.c:expand_complex_div_wide().
1340 Expand complex division to scalars, modified algorithm to minimize
1341 overflow with wide input ranges. */
1347 {
1348 /* In the TRUE branch, we compute
1349 ratio = br/bi;
1350 div = (br * ratio) + bi;
1351 tr = (ar * ratio) + ai;
1352 ti = (ai * ratio) - ar;
1353 tr = tr / div;
1354 ti = ti / div; */
1365 }
1366 else
1367 {
1368 /* In the FALSE branch, we compute
1369 ratio = d/c;
1370 divisor = (d * ratio) + c;
1371 tr = (b * ratio) + a;
1372 ti = b - (a * ratio);
1373 tr = tr / div;
1374 ti = ti / div; */
1386 }
1387 }
1392 }
1396 }
1400 {
1406 {
1412 /* It is possible that const_binop cannot handle the given
1413 code and return NULL_TREE */
1416 }
1419 }
1421 /* Shifts allow a scalar offset for a vector. */
1424 {
1430 {
1435 /* It is possible that const_binop cannot handle the given
1436 code and return NULL_TREE. */
1439 }
1442 }
1444 }
1446 /* Overload that adds a TYPE parameter to be able to dispatch
1447 to fold_relational_const. */
1449 tree
1451 {
1455 /* ??? Until we make the const_binop worker take the type of the
1456 result as argument put those cases that need it here. */
1458 {
1469 {
1485 {
1491 }
1494 }
1500 {
1525 {
1538 }
1541 }
1544 }
1549 /* Make sure type and arg0 have the same saturating flag. */
1554 }
1556 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1557 Return zero if computing the constants is not possible. */
1559 tree
1561 {
1562 /* Don't perform the operation, other than NEGATE and ABS, if
1563 flag_signaling_nans is on and the operand is a signaling NaN. */
1572 {
1573 CASE_CONVERT:
1580 /* If the source address is 0, and the source address space
1581 cannot have a valid object at 0, fold to dest type null. */
1592 {
1593 /* Can't call fold_negate_const directly here as that doesn't
1594 handle all cases and we might not be able to negate some
1595 constants. */
1600 }
1609 {
1613 }
1619 /* Perform BIT_NOT_EXPR on each element individually. */
1621 {
1623 tree elem;
1628 {
1634 }
1637 }
1659 {
1678 else
1682 {
1686 }
1689 }
1694 {
1708 {
1713 }
1716 {
1720 }
1723 }
1727 }
1730 }
1732 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1733 indicates which particular sizetype to create. */
1735 tree
1737 {
1739 }
1740 \f
1741 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1742 is a tree code. The type of the result is taken from the operands.
1743 Both must be equivalent integer types, ala int_binop_types_match_p.
1744 If the operands are constant, so is the result. */
1746 tree
1748 {
1757 /* Handle the special case of two integer constants faster. */
1759 {
1760 /* And some specific cases even faster than that. */
1762 {
1767 }
1769 {
1772 }
1774 {
1777 }
1779 /* Handle general case of two integer constants. For sizetype
1780 constant calculations we always want to know about overflow,
1781 even in the unsigned case. */
1783 }
1786 }
1788 /* Given two values, either both of sizetype or both of bitsizetype,
1789 compute the difference between the two values. Return the value
1790 in signed type corresponding to the type of the operands. */
1792 tree
1794 {
1796 tree ctype;
1801 /* If the type is already signed, just do the simple thing. */
1809 else
1812 /* If either operand is not a constant, do the conversions to the signed
1813 type and subtract. The hardware will do the right thing with any
1814 overflow in the subtraction. */
1820 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1821 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1822 overflow) and negate (which can't either). Special-case a result
1823 of zero while we're here. */
1829 else
1833 MINUS_EXPR,
1835 }
1836 \f
1837 /* A subroutine of fold_convert_const handling conversions of an
1838 INTEGER_CST to another integer type. */
1840 static tree
1842 {
1843 /* Given an integer constant, make new constant with new type,
1844 appropriately sign-extended or truncated. Use widest_int
1845 so that any extension is done according ARG1's type. */
1849 }
1851 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1852 to an integer type. */
1854 static tree
1856 {
1858 tree t;
1860 /* The following code implements the floating point to integer
1861 conversion rules required by the Java Language Specification,
1862 that IEEE NaNs are mapped to zero and values that overflow
1863 the target precision saturate, i.e. values greater than
1864 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1865 are mapped to INT_MIN. These semantics are allowed by the
1866 C and C++ standards that simply state that the behavior of
1867 FP-to-integer conversion is unspecified upon overflow. */
1869 wide_int val;
1870 REAL_VALUE_TYPE r;
1874 {
1881 }
1883 /* If R is NaN, return zero and show we have an overflow. */
1885 {
1888 }
1890 /* See if R is less than the lower bound or greater than the
1891 upper bound. */
1894 {
1898 {
1901 }
1902 }
1905 {
1908 {
1911 {
1914 }
1915 }
1916 }
1923 }
1925 /* A subroutine of fold_convert_const handling conversions of a
1926 FIXED_CST to an integer type. */
1928 static tree
1930 {
1931 tree t;
1935 /* Right shift FIXED_CST to temp by fbit. */
1939 {
1941 HOST_BITS_PER_DOUBLE_INT,
1944 /* Left shift temp to temp_trunc by fbit. */
1946 HOST_BITS_PER_DOUBLE_INT,
1948 }
1949 else
1950 {
1953 }
1955 /* If FIXED_CST is negative, we need to round the value toward 0.
1956 By checking if the fractional bits are not zero to add 1 to temp. */
1962 /* Given a fixed-point constant, make new constant with new type,
1963 appropriately sign-extended or truncated. */
1971 }
1973 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1974 to another floating point type. */
1976 static tree
1978 {
1979 REAL_VALUE_TYPE value;
1980 tree t;
1982 /* Don't perform the operation if flag_signaling_nans is on
1983 and the operand is a signaling NaN. */
1991 /* If converting an infinity or NAN to a representation that doesn't
1992 have one, set the overflow bit so that we can produce some kind of
1993 error message at the appropriate point if necessary. It's not the
1994 most user-friendly message, but it's better than nothing. */
2001 /* Regular overflow, conversion produced an infinity in a mode that
2002 can't represent them. */
2007 else
2010 }
2012 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2013 to a floating point type. */
2015 static tree
2017 {
2018 REAL_VALUE_TYPE value;
2019 tree t;
2026 }
2028 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2029 to another fixed-point type. */
2031 static tree
2033 {
2034 FIXED_VALUE_TYPE value;
2035 tree t;
2042 /* Propagate overflow flags. */
2046 }
2048 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2049 to a fixed-point type. */
2051 static tree
2053 {
2054 FIXED_VALUE_TYPE value;
2055 tree t;
2057 double_int di;
2064 else
2072 /* Propagate overflow flags. */
2076 }
2078 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2079 to a fixed-point type. */
2081 static tree
2083 {
2084 FIXED_VALUE_TYPE value;
2085 tree t;
2093 /* Propagate overflow flags. */
2097 }
2099 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2100 type TYPE. If no simplification can be done return NULL_TREE. */
2102 static tree
2104 {
2110 {
2117 }
2119 {
2126 }
2128 {
2135 }
2137 {
2140 {
2145 {
2151 }
2153 }
2154 }
2156 }
2158 /* Construct a vector of zero elements of vector type TYPE. */
2160 static tree
2162 {
2163 tree t;
2167 }
2169 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2171 bool
2173 {
2188 {
2203 }
2204 }
2206 /* Convert expression ARG to type TYPE. Used by the middle-end for
2207 simple conversions in preference to calling the front-end's convert. */
2209 tree
2211 {
2213 tree tem;
2224 {
2227 /* Handle conversions between pointers to different address spaces. */
2232 /* fall through */
2237 {
2241 }
2255 {
2259 }
2261 {
2265 }
2267 {
2271 }
2274 {
2292 }
2297 {
2301 }
2304 {
2318 }
2322 {
2331 integer_zero_node));
2333 {
2337 {
2343 }
2351 }
2355 }
2373 }
2374 fold_convert_exit:
2377 }
2378 \f
2379 /* Return false if expr can be assumed not to be an lvalue, true
2380 otherwise. */
2382 static bool
2384 {
2385 /* We only need to wrap lvalue tree codes. */
2387 {
2418 /* Assume the worst for front-end tree codes. */
2422 }
2425 }
2427 /* Return an expr equal to X but certainly not valid as an lvalue. */
2429 tree
2431 {
2432 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2433 us. */
2440 }
2442 /* When pedantic, return an expr equal to X but certainly not valid as a
2443 pedantic lvalue. Otherwise, return X. */
2445 static tree
2447 {
2449 }
2450 \f
2451 /* Given a tree comparison code, return the code that is the logical inverse.
2452 It is generally not safe to do this for floating-point comparisons, except
2453 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2454 ERROR_MARK in this case. */
2456 enum tree_code
2458 {
2464 {
2495 }
2496 }
2498 /* Similar, but return the comparison that results if the operands are
2499 swapped. This is safe for floating-point. */
2501 enum tree_code
2503 {
2505 {
2531 }
2532 }
2535 /* Convert a comparison tree code from an enum tree_code representation
2536 into a compcode bit-based encoding. This function is the inverse of
2537 compcode_to_comparison. */
2539 static enum comparison_code
2541 {
2543 {
2574 }
2575 }
2577 /* Convert a compcode bit-based encoding of a comparison operator back
2578 to GCC's enum tree_code representation. This function is the
2579 inverse of comparison_to_compcode. */
2581 static enum tree_code
2583 {
2585 {
2616 }
2617 }
2619 /* Return a tree for the comparison which is the combination of
2620 doing the AND or OR (depending on CODE) of the two operations LCODE
2621 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2622 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2623 if this makes the transformation invalid. */
2625 tree
2630 {
2637 {
2648 }
2651 {
2652 /* Eliminate unordered comparisons, as well as LTGT and ORD
2653 which are not used unless the mode has NaNs. */
2659 }
2661 {
2662 /* Check that the original operation and the optimized ones will trap
2663 under the same condition. */
2674 /* In a short-circuited boolean expression the LHS might be
2675 such that the RHS, if evaluated, will never trap. For
2676 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2677 if neither x nor y is NaN. (This is a mixed blessing: for
2678 example, the expression above will never trap, hence
2679 optimizing it to x < y would be invalid). */
2684 /* If the comparison was short-circuited, and only the RHS
2685 trapped, we may now generate a spurious trap. */
2690 /* If we changed the conditions that cause a trap, we lose. */
2693 }
2699 else
2700 {
2705 }
2706 }
2707 \f
2708 /* Return nonzero if two operands (typically of the same tree node)
2709 are necessarily equal. FLAGS modifies behavior as follows:
2711 If OEP_ONLY_CONST is set, only return nonzero for constants.
2712 This function tests whether the operands are indistinguishable;
2713 it does not test whether they are equal using C's == operation.
2714 The distinction is important for IEEE floating point, because
2715 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2716 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2718 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2719 even though it may hold multiple values during a function.
2720 This is because a GCC tree node guarantees that nothing else is
2721 executed between the evaluation of its "operands" (which may often
2722 be evaluated in arbitrary order). Hence if the operands themselves
2723 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2724 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2725 unset means assuming isochronic (or instantaneous) tree equivalence.
2726 Unless comparing arbitrary expression trees, such as from different
2727 statements, this flag can usually be left unset.
2729 If OEP_PURE_SAME is set, then pure functions with identical arguments
2730 are considered the same. It is used when the caller has other ways
2731 to ensure that global memory is unchanged in between.
2733 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2734 not values of expressions.
2736 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2737 any operand with side effect. This is unnecesarily conservative in the
2738 case we know that arg0 and arg1 are in disjoint code paths (such as in
2739 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2740 addresses with TREE_CONSTANT flag set so we know that &var == &var
2741 even if var is volatile. */
2743 int
2745 {
2746 /* When checking, verify at the outermost operand_equal_p call that
2747 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2748 hash value. */
2750 {
2752 {
2754 {
2761 }
2763 }
2764 else
2766 }
2768 /* If either is ERROR_MARK, they aren't equal. */
2774 /* Similar, if either does not have a type (like a released SSA name),
2775 they aren't equal. */
2779 /* We cannot consider pointers to different address space equal. */
2786 /* Check equality of integer constants before bailing out due to
2787 precision differences. */
2789 {
2790 /* Address of INTEGER_CST is not defined; check that we did not forget
2791 to drop the OEP_ADDRESS_OF flags. */
2794 }
2797 {
2798 /* If both types don't have the same signedness, then we can't consider
2799 them equal. We must check this before the STRIP_NOPS calls
2800 because they may change the signedness of the arguments. As pointers
2801 strictly don't have a signedness, require either two pointers or
2802 two non-pointers as well. */
2808 /* If both types don't have the same precision, then it is not safe
2809 to strip NOPs. */
2816 }
2817 #if 0
2818 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2819 sanity check once the issue is solved. */
2820 else
2821 /* Addresses of conversions and SSA_NAMEs (and many other things)
2822 are not defined. Check that we did not forget to drop the
2823 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2826 #endif
2828 /* In case both args are comparisons but with different comparison
2829 code, try to swap the comparison operands of one arg to produce
2830 a match and compare that variant. */
2834 {
2842 }
2845 {
2846 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2848 ;
2850 {
2851 /* If we are interested in comparing addresses ignore
2852 MEM_REF wrappings of the base that can appear just for
2853 TBAA reasons. */
2867 }
2868 else
2870 }
2872 /* When not checking adddresses, this is needed for conversions and for
2873 COMPONENT_REF. Might as well play it safe and always test this. */
2880 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2881 We don't care about side effects in that case because the SAVE_EXPR
2882 takes care of that for us. In all other cases, two expressions are
2883 equal if they have no side effects. If we have two identical
2884 expressions with side effects that should be treated the same due
2885 to the only side effects being identical SAVE_EXPR's, that will
2886 be detected in the recursive calls below.
2887 If we are taking an invariant address of two identical objects
2888 they are necessarily equal as well. */
2895 /* Next handle constant cases, those for which we can return 1 even
2896 if ONLY_CONST is set. */
2899 {
2913 {
2914 /* If we do not distinguish between signed and unsigned zero,
2915 consider them equal. */
2918 }
2922 {
2929 {
2933 }
2935 }
2939 flags)
2941 flags));
2952 flags | OEP_ADDRESS_OF
2955 /* In GIMPLE empty constructors are allowed in initializers of
2956 aggregates. */
2960 }
2965 /* Define macros to test an operand from arg0 and arg1 for equality and a
2966 variant that allows null and views null as being different from any
2967 non-null value. In the latter case, if either is null, the both
2968 must be; otherwise, do the normal comparison. */
2969 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2970 TREE_OPERAND (arg1, N), flags)
2972 #define OP_SAME_WITH_NULL(N) \
2973 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2974 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2977 {
2979 /* Two conversions are equal only if signedness and modes match. */
2981 {
2982 CASE_CONVERT:
2990 }
3000 /* For commutative ops, allow the other order. */
3008 /* If either of the pointer (or reference) expressions we are
3009 dereferencing contain a side effect, these cannot be equal,
3010 but their addresses can be. */
3017 {
3027 /* Require the same offset. */
3033 /* Fallthru. */
3041 {
3042 /* Require equal access sizes */
3048 flags)))
3050 /* Verify that access happens in similar types. */
3053 /* Verify that accesses are TBAA compatible. */
3062 /* Verify that alignment is compatible. */
3066 }
3069 /* TARGET_MEM_REF require equal extra operands. */
3080 /* Compare the array index by value if it is constant first as we
3081 may have different types but same value here. */
3087 /* Compare low bound and element size as with OEP_ADDRESS_OF
3088 we have to account for the offset of the ref. */
3093 array_ref_low_bound
3097 array_ref_element_size
3099 flags))));
3102 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3103 may be NULL when we're called to compare MEM_EXPRs. */
3118 }
3122 {
3124 /* Be sure we pass right ADDRESS_OF flag. */
3142 /* The multiplcation operands are commutative. */
3143 /* FALLTHRU */
3151 /* Otherwise take into account this is a commutative operation. */
3170 }
3174 {
3178 /* If not both CALL_EXPRs are either internal or normal function
3179 functions, then they are not equal. */
3182 {
3183 /* If the CALL_EXPRs call different internal functions, then they
3184 are not equal. */
3187 }
3188 else
3189 {
3190 /* If the CALL_EXPRs call different functions, then they are not
3191 equal. */
3193 flags))
3195 }
3197 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3198 {
3202 else
3206 }
3208 /* Now see if all the arguments are the same. */
3209 {
3220 /* If we get here and both argument lists are exhausted
3221 then the CALL_EXPRs are equal. */
3223 }
3226 }
3229 /* Consider __builtin_sqrt equal to sqrt. */
3237 {
3238 /* In GIMPLE constructors are used only to build vectors from
3239 elements. Individual elements in the constructor must be
3240 indexed in increasing order and form an initial sequence.
3242 We make no effort to compare constructors in generic.
3243 (see sem_variable::equals in ipa-icf which can do so for
3244 constants). */
3249 /* Be sure that vectors constructed have the same representation.
3250 We only tested element precision and modes to match.
3251 Vectors may be BLKmode and thus also check that the number of
3252 parts match. */
3265 {
3270 /* In GIMPLE the indexes can be either NULL or matching i.
3271 Double check this so we won't get false
3272 positives for GENERIC. */
3280 }
3282 }
3287 }
3289 #undef OP_SAME
3290 #undef OP_SAME_WITH_NULL
3291 }
3292 \f
3293 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3294 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3296 When in doubt, return 0. */
3298 static int
3300 {
3312 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3313 and see if the inner values are the same. This removes any
3314 signedness comparison, which doesn't matter here. */
3321 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3322 actual comparison operand, ARG0.
3324 First throw away any conversions to wider types
3325 already present in the operands. */
3334 {
3337 /* Make sure shorter operand is extended the right way
3338 to match the longer operand. */
3344 }
3347 }
3348 \f
3349 /* See if ARG is an expression that is either a comparison or is performing
3350 arithmetic on comparisons. The comparisons must only be comparing
3351 two different values, which will be stored in *CVAL1 and *CVAL2; if
3352 they are nonzero it means that some operands have already been found.
3353 No variables may be used anywhere else in the expression except in the
3354 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3355 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3357 If this is true, return 1. Otherwise, return zero. */
3359 static int
3361 {
3365 /* We can handle some of the tcc_expression cases here. */
3375 {
3376 /* If we've already found a CVAL1 or CVAL2, this expression is
3377 two complex to handle. */
3383 }
3386 {
3409 /* First see if we can handle the first operand, then the second. For
3410 the second operand, we know *CVAL1 can't be zero. It must be that
3411 one side of the comparison is each of the values; test for the
3412 case where this isn't true by failing if the two operands
3413 are the same. */
3422 ;
3426 ;
3427 else
3431 ;
3435 ;
3436 else
3443 }
3444 }
3445 \f
3446 /* ARG is a tree that is known to contain just arithmetic operations and
3447 comparisons. Evaluate the operations in the tree substituting NEW0 for
3448 any occurrence of OLD0 as an operand of a comparison and likewise for
3449 NEW1 and OLD1. */
3451 static tree
3454 {
3459 /* We can handle some of the tcc_expression cases here. */
3467 {
3482 {
3501 }
3502 /* Fall through - ??? */
3505 {
3509 /* We need to check both for exact equality and tree equality. The
3510 former will be true if the operand has a side-effect. In that
3511 case, we know the operand occurred exactly once. */
3524 }
3528 }
3529 }
3530 \f
3531 /* Return a tree for the case when the result of an expression is RESULT
3532 converted to TYPE and OMITTED was previously an operand of the expression
3533 but is now not needed (e.g., we folded OMITTED * 0).
3535 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3536 the conversion of RESULT to TYPE. */
3538 tree
3540 {
3543 /* If the resulting operand is an empty statement, just return the omitted
3544 statement casted to void. */
3554 }
3556 /* Return a tree for the case when the result of an expression is RESULT
3557 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3558 of the expression but are now not needed.
3560 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3561 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3562 evaluated before OMITTED2. Otherwise, if neither has side effects,
3563 just do the conversion of RESULT to TYPE. */
3565 tree
3568 {
3577 }
3579 \f
3580 /* Return a simplified tree node for the truth-negation of ARG. This
3581 never alters ARG itself. We assume that ARG is an operation that
3582 returns a truth value (0 or 1).
3584 FIXME: one would think we would fold the result, but it causes
3585 problems with the dominator optimizer. */
3587 static tree
3589 {
3594 /* If this is a comparison, we can simply invert it, except for
3595 floating-point non-equality comparisons, in which case we just
3596 enclose a TRUTH_NOT_EXPR around what we have. */
3599 {
3602 && flag_trapping_math
3616 }
3619 {
3638 /* Here we can invert either operand. We invert the first operand
3639 unless the second operand is a TRUTH_NOT_EXPR in which case our
3640 result is the XOR of the first operand with the inside of the
3641 negation of the second operand. */
3646 else
3669 {
3676 /* A COND_EXPR may have a throw as one operand, which
3677 then has void type. Just leave void operands
3678 as they are. */
3684 }
3696 CASE_CONVERT:
3700 /* fall through */
3722 }
3723 }
3725 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3726 assume that ARG is an operation that returns a truth value (0 or 1
3727 for scalars, 0 or -1 for vectors). Return the folded expression if
3728 folding is successful. Otherwise, return NULL_TREE. */
3730 static tree
3732 {
3735 ? BIT_NOT_EXPR
3738 }
3740 /* Return a simplified tree node for the truth-negation of ARG. This
3741 never alters ARG itself. We assume that ARG is an operation that
3742 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3744 tree
3746 {
3752 ? BIT_NOT_EXPR
3755 }
3757 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3758 with code CODE. This optimization is unsafe. */
3759 static tree
3762 {
3766 /* (A / C) +- (B / C) -> (A +- B) / C. */
3776 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3781 {
3793 }
3796 }
3797 \f
3798 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3799 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3800 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3801 is the original memory reference used to preserve the alias set of
3802 the access. */
3804 static tree
3808 {
3814 build_int_cst
3818 {
3825 }
3840 }
3842 /* Optimize a bit-field compare.
3844 There are two cases: First is a compare against a constant and the
3845 second is a comparison of two items where the fields are at the same
3846 bit position relative to the start of a chunk (byte, halfword, word)
3847 large enough to contain it. In these cases we can avoid the shift
3848 implicit in bitfield extractions.
3850 For constants, we emit a compare of the shifted constant with the
3851 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3852 compared. For two fields at the same position, we do the ANDs with the
3853 similar mask and compare the result of the ANDs.
3855 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3856 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3857 are the left and right operands of the comparison, respectively.
3859 If the optimization described above can be done, we return the resulting
3860 tree. Otherwise we return zero. */
3862 static tree
3865 {
3868 tree unsigned_type;
3875 tree mask;
3876 tree offset;
3878 /* Get all the information about the extractions being done. If the bit size
3879 if the same as the size of the underlying object, we aren't doing an
3880 extraction at all and so can do nothing. We also don't want to
3881 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3882 then will no longer be able to replace it. */
3891 else
3892 {
3893 /* If this is not a constant, we can only do something if bit positions,
3894 sizes, signedness and storage order are the same. */
3895 rinner
3903 }
3905 /* Honor the C++ memory model and mimic what RTL expansion does. */
3909 {
3913 }
3915 /* See if we can find a mode to refer to this field. We should be able to,
3916 but fail if we can't. */
3925 /* Set signed and unsigned types of the precision of this mode for the
3926 shifts below. */
3929 /* Compute the bit position and size for the new reference and our offset
3930 within it. If the new reference is the same size as the original, we
3931 won't optimize anything, so return zero. */
3941 /* Make the mask to be used against the extracted field. */
3948 /* If not comparing with constant, just rework the comparison
3949 and return. */
3953 unsigned_type,
3956 mask),
3959 unsigned_type,
3962 mask));
3964 /* Otherwise, we are handling the constant case. See if the constant is too
3965 big for the field. Warn and return a tree for 0 (false) if so. We do
3966 this not only for its own sake, but to avoid having to test for this
3967 error case below. If we didn't, we might generate wrong code.
3969 For unsigned fields, the constant shifted right by the field length should
3970 be all zero. For signed fields, the high-order bits should agree with
3971 the sign bit. */
3974 {
3976 {
3980 }
3981 }
3982 else
3983 {
3986 {
3990 }
3991 }
3993 /* Single-bit compares should always be against zero. */
3995 {
3998 }
4000 /* Make a new bitfield reference, shift the constant over the
4001 appropriate number of bits and mask it with the computed mask
4002 (in case this was a signed field). If we changed it, make a new one. */
4010 mask);
4015 }
4016 \f
4017 /* Subroutine for fold_truth_andor_1: decode a field reference.
4019 If EXP is a comparison reference, we return the innermost reference.
4021 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4022 set to the starting bit number.
4024 If the innermost field can be completely contained in a mode-sized
4025 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4027 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4028 otherwise it is not changed.
4030 *PUNSIGNEDP is set to the signedness of the field.
4032 *PREVERSEP is set to the storage order of the field.
4034 *PMASK is set to the mask used. This is either contained in a
4035 BIT_AND_EXPR or derived from the width of the field.
4037 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4039 Return 0 if this is not a component reference or is one that we can't
4040 do anything with. */
4042 static tree
4047 {
4052 tree unsigned_type;
4055 /* All the optimizations using this function assume integer fields.
4056 There are problems with FP fields since the type_for_size call
4057 below can fail for, e.g., XFmode. */
4061 /* We are interested in the bare arrangement of bits, so strip everything
4062 that doesn't affect the machine mode. However, record the type of the
4063 outermost expression if it may matter below. */
4070 {
4076 }
4087 /* If the number of bits in the reference is the same as the bitsize of
4088 the outer type, then the outer type gives the signedness. Otherwise
4089 (in case of a small bitfield) the signedness is unchanged. */
4093 /* Compute the mask to access the bitfield. */
4102 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4110 }
4112 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4113 bit positions and MASK is SIGNED. */
4115 static int
4117 {
4121 /* If this function returns true when the type of the mask is
4122 UNSIGNED, then there will be errors. In particular see
4123 gcc.c-torture/execute/990326-1.c. There does not appear to be
4124 any documentation paper trail as to why this is so. But the pre
4125 wide-int worked with that restriction and it has been preserved
4126 here. */
4131 }
4133 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4134 represents the sign bit of EXP's type. If EXP represents a sign
4135 or zero extension, also test VAL against the unextended type.
4136 The return value is the (sub)expression whose sign bit is VAL,
4137 or NULL_TREE otherwise. */
4139 tree
4141 {
4143 tree t;
4145 /* Tree EXP must have an integral type. */
4150 /* Tree VAL must be an integer constant. */
4159 /* Handle extension from a narrower type. */
4165 }
4167 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4168 to be evaluated unconditionally. */
4170 static int
4172 {
4173 /* Strip any conversions that don't change the machine mode. */
4182 /* Don't regard global variables as simple. They may be
4183 allocated in ways unknown to the compiler (shared memory,
4184 #pragma weak, etc). */
4187 /* Weakrefs are not safe to be read, since they can be NULL.
4188 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4189 have DECL_WEAK flag set. */
4191 /* Loading a static variable is unduly expensive, but global
4192 registers aren't expensive. */
4194 }
4196 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4197 to be evaluated unconditionally.
4198 I addition to simple_operand_p, we assume that comparisons, conversions,
4199 and logic-not operations are simple, if their operands are simple, too. */
4201 static bool
4203 {
4223 }
4225 \f
4226 /* The following functions are subroutines to fold_range_test and allow it to
4227 try to change a logical combination of comparisons into a range test.
4229 For example, both
4230 X == 2 || X == 3 || X == 4 || X == 5
4231 and
4232 X >= 2 && X <= 5
4233 are converted to
4234 (unsigned) (X - 2) <= 3
4236 We describe each set of comparisons as being either inside or outside
4237 a range, using a variable named like IN_P, and then describe the
4238 range with a lower and upper bound. If one of the bounds is omitted,
4239 it represents either the highest or lowest value of the type.
4241 In the comments below, we represent a range by two numbers in brackets
4242 preceded by a "+" to designate being inside that range, or a "-" to
4243 designate being outside that range, so the condition can be inverted by
4244 flipping the prefix. An omitted bound is represented by a "-". For
4245 example, "- [-, 10]" means being outside the range starting at the lowest
4246 possible value and ending at 10, in other words, being greater than 10.
4247 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4248 always false.
4250 We set up things so that the missing bounds are handled in a consistent
4251 manner so neither a missing bound nor "true" and "false" need to be
4252 handled using a special case. */
4254 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4255 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4256 and UPPER1_P are nonzero if the respective argument is an upper bound
4257 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4258 must be specified for a comparison. ARG1 will be converted to ARG0's
4259 type if both are specified. */
4261 static tree
4264 {
4265 tree tem;
4269 /* If neither arg represents infinity, do the normal operation.
4270 Else, if not a comparison, return infinity. Else handle the special
4271 comparison rules. Note that most of the cases below won't occur, but
4272 are handled for consistency. */
4275 {
4280 }
4285 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4286 for neither. In real maths, we cannot assume open ended ranges are
4287 the same. But, this is computer arithmetic, where numbers are finite.
4288 We can therefore make the transformation of any unbounded range with
4289 the value Z, Z being greater than any representable number. This permits
4290 us to treat unbounded ranges as equal. */
4294 {
4315 }
4318 }
4319 \f
4320 /* Helper routine for make_range. Perform one step for it, return
4321 new expression if the loop should continue or NULL_TREE if it should
4322 stop. */
4324 tree
4328 {
4334 {
4336 /* We can only do something if the range is testing for zero. */
4345 /* We can only do something if the range is testing for zero
4346 and if the second operand is an integer constant. Note that
4347 saying something is "in" the range we make is done by
4348 complementing IN_P since it will set in the initial case of
4349 being not equal to zero; "out" is leaving it alone. */
4356 {
4377 }
4379 /* If this is an unsigned comparison, we also know that EXP is
4380 greater than or equal to zero. We base the range tests we make
4381 on that fact, so we record it here so we can parse existing
4382 range tests. We test arg0_type since often the return type
4383 of, e.g. EQ_EXPR, is boolean. */
4385 {
4389 NULL_TREE))
4394 /* If the high bound is missing, but we have a nonzero low
4395 bound, reverse the range so it goes from zero to the low bound
4396 minus 1. */
4398 {
4403 }
4404 }
4412 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4413 low and high are non-NULL, then normalize will DTRT. */
4416 {
4421 }
4423 /* (-x) IN [a,b] -> x in [-b, -a] */
4435 /* ~ X -> -X - 1 */
4444 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4445 move a constant to the other side. */
4450 /* If EXP is signed, any overflow in the computation is undefined,
4451 so we don't worry about it so long as our computations on
4452 the bounds don't overflow. For unsigned, overflow is defined
4453 and this is exactly the right thing. */
4465 normalize:
4466 /* Check for an unsigned range which has wrapped around the maximum
4467 value thus making n_high < n_low, and normalize it. */
4469 {
4475 /* If the range is of the form +/- [ x+1, x ], we won't
4476 be able to normalize it. But then, it represents the
4477 whole range or the empty set, so make it
4478 +/- [ -, - ]. */
4482 else
4484 }
4485 else
4493 CASE_CONVERT:
4511 /* If we're converting arg0 from an unsigned type, to exp,
4512 a signed type, we will be doing the comparison as unsigned.
4513 The tests above have already verified that LOW and HIGH
4514 are both positive.
4516 So we have to ensure that we will handle large unsigned
4517 values the same way that the current signed bounds treat
4518 negative values. */
4521 {
4522 tree high_positive;
4523 tree equiv_type;
4524 /* For fixed-point modes, we need to pass the saturating flag
4525 as the 2nd parameter. */
4527 equiv_type
4530 else
4531 equiv_type
4534 /* A range without an upper bound is, naturally, unbounded.
4535 Since convert would have cropped a very large value, use
4536 the max value for the destination type. */
4537 high_positive
4544 high_positive),
4547 /* If the low bound is specified, "and" the range with the
4548 range for which the original unsigned value will be
4549 positive. */
4551 {
4554 integer_zero_node),
4555 high_positive))
4559 }
4560 else
4561 {
4562 /* Otherwise, "or" the range with the range of the input
4563 that will be interpreted as negative. */
4566 integer_zero_node),
4567 high_positive))
4571 }
4572 }
4581 }
4582 }
4584 /* Given EXP, a logical expression, set the range it is testing into
4585 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4586 actually being tested. *PLOW and *PHIGH will be made of the same
4587 type as the returned expression. If EXP is not a comparison, we
4588 will most likely not be returning a useful value and range. Set
4589 *STRICT_OVERFLOW_P to true if the return value is only valid
4590 because signed overflow is undefined; otherwise, do not change
4591 *STRICT_OVERFLOW_P. */
4593 tree
4596 {
4604 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4605 and see if we can refine the range. Some of the cases below may not
4606 happen, but it doesn't seem worth worrying about this. We "continue"
4607 the outer loop when we've changed something; otherwise we "break"
4608 the switch, which will "break" the while. */
4614 {
4620 {
4628 }
4637 }
4639 /* If EXP is a constant, we can evaluate whether this is true or false. */
4641 {
4648 }
4652 }
4653 \f
4654 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4655 type, TYPE, return an expression to test if EXP is in (or out of, depending
4656 on IN_P) the range. Return 0 if the test couldn't be created. */
4658 tree
4661 {
4664 /* Disable this optimization for function pointer expressions
4665 on targets that require function pointer canonicalization. */
4672 {
4678 }
4696 {
4698 {
4702 }
4704 }
4706 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4708 {
4712 {
4714 {
4717 etype
4719 else
4722 }
4725 }
4726 }
4728 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4729 This requires wrap-around arithmetics for the type of the expression.
4730 First make sure that arithmetics in this type is valid, then make sure
4731 that it wraps around. */
4737 {
4740 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4741 for the type in question, as we rely on this here. */
4751 else
4753 }
4763 {
4765 {
4770 }
4772 }
4780 }
4781 \f
4782 /* Return the predecessor of VAL in its type, handling the infinite case. */
4784 static tree
4786 {
4792 else
4795 }
4797 /* Return the successor of VAL in its type, handling the infinite case. */
4799 static tree
4801 {
4807 else
4810 }
4812 /* Given two ranges, see if we can merge them into one. Return 1 if we
4813 can, 0 if we can't. Set the output range into the specified parameters. */
4815 bool
4818 {
4822 tree tem;
4832 /* Make range 0 be the range that starts first, or ends last if they
4833 start at the same value. Swap them if it isn't. */
4836 || (lowequal
4839 {
4843 }
4845 /* Now flag two cases, whether the ranges are disjoint or whether the
4846 second range is totally subsumed in the first. Note that the tests
4847 below are simplified by the ones above. */
4853 /* We now have four cases, depending on whether we are including or
4854 excluding the two ranges. */
4856 {
4857 /* If they don't overlap, the result is false. If the second range
4858 is a subset it is the result. Otherwise, the range is from the start
4859 of the second to the end of the first. */
4864 else
4866 }
4869 {
4870 /* If they don't overlap, the result is the first range. If they are
4871 equal, the result is false. If the second range is a subset of the
4872 first, and the ranges begin at the same place, we go from just after
4873 the end of the second range to the end of the first. If the second
4874 range is not a subset of the first, or if it is a subset and both
4875 ranges end at the same place, the range starts at the start of the
4876 first range and ends just before the second range.
4877 Otherwise, we can't describe this as a single range. */
4883 {
4888 {
4889 /* We are in the weird situation where high0 > high1 but
4890 high1 has no successor. Punt. */
4892 }
4893 }
4895 {
4900 {
4901 /* low0 < low1 but low1 has no predecessor. Punt. */
4903 }
4904 }
4905 else
4907 }
4910 {
4911 /* If they don't overlap, the result is the second range. If the second
4912 is a subset of the first, the result is false. Otherwise,
4913 the range starts just after the first range and ends at the
4914 end of the second. */
4919 else
4920 {
4925 {
4926 /* high1 > high0 but high0 has no successor. Punt. */
4928 }
4929 }
4930 }
4932 else
4933 {
4934 /* The case where we are excluding both ranges. Here the complex case
4935 is if they don't overlap. In that case, the only time we have a
4936 range is if they are adjacent. If the second is a subset of the
4937 first, the result is the first. Otherwise, the range to exclude
4938 starts at the beginning of the first range and ends at the end of the
4939 second. */
4941 {
4946 else
4947 {
4948 /* Canonicalize - [min, x] into - [-, x]. */
4951 {
4956 /* FALLTHROUGH */
4969 }
4971 /* Canonicalize - [x, max] into - [x, -]. */
4974 {
4979 /* FALLTHROUGH */
4995 }
4997 /* The ranges might be also adjacent between the maximum and
4998 minimum values of the given type. For
4999 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5000 return + [x + 1, y - 1]. */
5002 {
5009 }
5010 else
5012 }
5013 }
5016 else
5018 }
5022 }
5023 \f
5025 /* Subroutine of fold, looking inside expressions of the form
5026 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5027 of the COND_EXPR. This function is being used also to optimize
5028 A op B ? C : A, by reversing the comparison first.
5030 Return a folded expression whose code is not a COND_EXPR
5031 anymore, or NULL_TREE if no folding opportunity is found. */
5033 static tree
5036 {
5041 tree tem;
5046 /* If we have A op 0 ? A : -A, consider applying the following
5047 transformations:
5049 A == 0? A : -A same as -A
5050 A != 0? A : -A same as A
5051 A >= 0? A : -A same as abs (A)
5052 A > 0? A : -A same as abs (A)
5053 A <= 0? A : -A same as -abs (A)
5054 A < 0? A : -A same as -abs (A)
5056 None of these transformations work for modes with signed
5057 zeros. If A is +/-0, the first two transformations will
5058 change the sign of the result (from +0 to -0, or vice
5059 versa). The last four will fix the sign of the result,
5060 even though the original expressions could be positive or
5061 negative, depending on the sign of A.
5063 Note that all these transformations are correct if A is
5064 NaN, since the two alternatives (A and -A) are also NaNs. */
5071 /* In the case that A is of the form X-Y, '-A' (arg2) may
5072 have already been folded to Y-X, check for that. */
5080 {
5094 /* Fall through. */
5105 /* FALLTHRU */
5115 }
5117 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5118 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5119 both transformations are correct when A is NaN: A != 0
5120 is then true, and A == 0 is false. */
5124 {
5129 }
5131 /* Try some transformations of A op B ? A : B.
5133 A == B? A : B same as B
5134 A != B? A : B same as A
5135 A >= B? A : B same as max (A, B)
5136 A > B? A : B same as max (B, A)
5137 A <= B? A : B same as min (A, B)
5138 A < B? A : B same as min (B, A)
5140 As above, these transformations don't work in the presence
5141 of signed zeros. For example, if A and B are zeros of
5142 opposite sign, the first two transformations will change
5143 the sign of the result. In the last four, the original
5144 expressions give different results for (A=+0, B=-0) and
5145 (A=-0, B=+0), but the transformed expressions do not.
5147 The first two transformations are correct if either A or B
5148 is a NaN. In the first transformation, the condition will
5149 be false, and B will indeed be chosen. In the case of the
5150 second transformation, the condition A != B will be true,
5151 and A will be chosen.
5153 The conversions to max() and min() are not correct if B is
5154 a number and A is not. The conditions in the original
5155 expressions will be false, so all four give B. The min()
5156 and max() versions would give a NaN instead. */
5159 /* Avoid these transformations if the COND_EXPR may be used
5160 as an lvalue in the C++ front-end. PR c++/19199. */
5161 && (in_gimple_form
5167 {
5172 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5174 {
5178 }
5181 {
5190 /* In C++ a ?: expression can be an lvalue, so put the
5191 operand which will be used if they are equal first
5192 so that we can convert this back to the
5193 corresponding COND_EXPR. */
5195 {
5204 }
5211 {
5220 }
5235 }
5236 }
5238 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5239 we might still be able to simplify this. For example,
5240 if C1 is one less or one more than C2, this might have started
5241 out as a MIN or MAX and been transformed by this function.
5242 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5248 {
5252 /* We can replace A with C1 in this case. */
5257 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5258 MIN_EXPR, to preserve the signedness of the comparison. */
5260 OEP_ONLY_CONST)
5264 OEP_ONLY_CONST))
5265 {
5268 arg2));
5271 }
5275 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5276 as above. */
5278 OEP_ONLY_CONST)
5282 OEP_ONLY_CONST))
5283 {
5286 arg2));
5289 }
5293 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5294 MAX_EXPR, to preserve the signedness of the comparison. */
5296 OEP_ONLY_CONST)
5300 OEP_ONLY_CONST))
5301 {
5304 arg2));
5306 }
5310 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5312 OEP_ONLY_CONST)
5316 OEP_ONLY_CONST))
5317 {
5320 arg2));
5322 }
5328 }
5331 }
5334 \f
5335 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5336 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5337 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5338 false) >= 2)
5339 #endif
5341 /* EXP is some logical combination of boolean tests. See if we can
5342 merge it into some range test. Return the new tree if so. */
5344 static tree
5347 {
5363 /* If this is an OR operation, invert both sides; we will invert
5364 again at the end. */
5368 /* If both expressions are the same, if we can merge the ranges, and we
5369 can build the range test, return it or it inverted. If one of the
5370 ranges is always true or always false, consider it to be the same
5371 expression as the other. */
5379 {
5383 }
5385 /* On machines where the branch cost is expensive, if this is a
5386 short-circuited branch and the underlying object on both sides
5387 is the same, make a non-short-circuit operation. */
5393 {
5394 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5395 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5396 which cases we can't do this. */
5404 {
5413 {
5416 WARN_STRICT_OVERFLOW_COMPARISON);
5420 }
5421 }
5422 }
5425 }
5426 \f
5427 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5428 bit value. Arrange things so the extra bits will be set to zero if and
5429 only if C is signed-extended to its full width. If MASK is nonzero,
5430 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5432 static tree
5434 {
5437 tree temp;
5442 /* We work by getting just the sign bit into the low-order bit, then
5443 into the high-order bit, then sign-extend. We then XOR that value
5444 with C. */
5447 /* We must use a signed type in order to get an arithmetic right shift.
5448 However, we must also avoid introducing accidental overflows, so that
5449 a subsequent call to integer_zerop will work. Hence we must
5450 do the type conversion here. At this point, the constant is either
5451 zero or one, and the conversion to a signed type can never overflow.
5452 We could get an overflow if this conversion is done anywhere else. */
5461 /* If necessary, convert the type back to match the type of C. */
5466 }
5467 \f
5468 /* For an expression that has the form
5469 (A && B) || ~B
5470 or
5471 (A || B) && ~B,
5472 we can drop one of the inner expressions and simplify to
5473 A || ~B
5474 or
5475 A && ~B
5476 LOC is the location of the resulting expression. OP is the inner
5477 logical operation; the left-hand side in the examples above, while CMPOP
5478 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5479 removing a condition that guards another, as in
5480 (A != NULL && A->...) || A == NULL
5481 which we must not transform. If RHS_ONLY is true, only eliminate the
5482 right-most operand of the inner logical operation. */
5484 static tree
5487 {
5505 {
5508 {
5511 }
5512 }
5514 {
5517 {
5520 }
5521 }
5536 }
5538 /* Find ways of folding logical expressions of LHS and RHS:
5539 Try to merge two comparisons to the same innermost item.
5540 Look for range tests like "ch >= '0' && ch <= '9'".
5541 Look for combinations of simple terms on machines with expensive branches
5542 and evaluate the RHS unconditionally.
5544 For example, if we have p->a == 2 && p->b == 4 and we can make an
5545 object large enough to span both A and B, we can do this with a comparison
5546 against the object ANDed with the a mask.
5548 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5549 operations to do this with one comparison.
5551 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5552 function and the one above.
5554 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5555 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5557 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5558 two operands.
5560 We return the simplified tree or 0 if no optimization is possible. */
5562 static tree
5565 {
5566 /* If this is the "or" of two comparisons, we can do something if
5567 the comparisons are NE_EXPR. If this is the "and", we can do something
5568 if the comparisons are EQ_EXPR. I.e.,
5569 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5571 WANTED_CODE is this operation code. For single bit fields, we can
5572 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5573 comparison for one-bit fields. */
5594 /* Start by getting the comparison codes. Fail if anything is volatile.
5595 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5596 it were surrounded with a NE_EXPR. */
5605 {
5609 }
5612 {
5616 }
5627 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5630 {
5633 {
5638 }
5641 {
5647 }
5648 }
5653 /* If the RHS can be evaluated unconditionally and its operands are
5654 simple, it wins to evaluate the RHS unconditionally on machines
5655 with expensive branches. In this case, this isn't a comparison
5656 that can be merged. */
5663 {
5664 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5675 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5685 }
5687 /* See if the comparisons can be merged. Then get all the parameters for
5688 each side. */
5713 /* It must be true that the inner operation on the lhs of each
5714 comparison must be the same if we are to be able to do anything.
5715 Then see if we have constants. If not, the same must be true for
5716 the rhs's. */
5725 {
5728 }
5733 else
5736 /* If either comparison code is not correct for our logical operation,
5737 fail. However, we can convert a one-bit comparison against zero into
5738 the opposite comparison against that bit being set in the field. */
5742 {
5744 {
5745 /* Make the left operand unsigned, since we are only interested
5746 in the value of one bit. Otherwise we are doing the wrong
5747 thing below. */
5750 }
5751 else
5753 }
5755 /* This is analogous to the code for l_const above. */
5757 {
5759 {
5762 }
5763 else
5765 }
5767 /* See if we can find a mode that contains both fields being compared on
5768 the left. If we can't, fail. Otherwise, update all constants and masks
5769 to be relative to a field of that size. */
5774 volatilep);
5784 {
5787 }
5795 {
5802 {
5806 }
5807 }
5809 {
5816 {
5820 }
5821 }
5823 /* If the right sides are not constant, do the same for it. Also,
5824 disallow this optimization if a size or signedness mismatch occurs
5825 between the left and right sides. */
5827 {
5830 /* Make sure the two fields on the right
5831 correspond to the left without being swapped. */
5839 volatilep);
5849 {
5852 }
5861 /* Make a mask that corresponds to both fields being compared.
5862 Do this for both items being compared. If the operands are the
5863 same size and the bits being compared are in the same position
5864 then we can do this by masking both and comparing the masked
5865 results. */
5869 {
5883 }
5885 /* There is still another way we can do something: If both pairs of
5886 fields being compared are adjacent, we may be able to make a wider
5887 field containing them both.
5889 Note that we still must mask the lhs/rhs expressions. Furthermore,
5890 the mask must be shifted to account for the shift done by
5891 make_bit_field_ref. */
5896 {
5897 tree type;
5913 /* Convert to the smaller type before masking out unwanted bits. */
5916 {
5918 {
5922 }
5924 {
5928 }
5929 }
5938 }
5941 }
5943 /* Handle the case of comparisons with constants. If there is something in
5944 common between the masks, those bits of the constants must be the same.
5945 If not, the condition is always false. Test for this to avoid generating
5946 incorrect code below. */
5951 {
5953 {
5956 }
5957 else
5958 {
5961 }
5962 }
5964 /* Construct the expression we will return. First get the component
5965 reference we will make. Unless the mask is all ones the width of
5966 that field, perform the mask operation. Then compare with the
5967 merged constant. */
5978 }
5979 \f
5980 /* T is an integer expression that is being multiplied, divided, or taken a
5981 modulus (CODE says which and what kind of divide or modulus) by a
5982 constant C. See if we can eliminate that operation by folding it with
5983 other operations already in T. WIDE_TYPE, if non-null, is a type that
5984 should be used for the computation if wider than our type.
5986 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5987 (X * 2) + (Y * 4). We must, however, be assured that either the original
5988 expression would not overflow or that overflow is undefined for the type
5989 in the language in question.
5991 If we return a non-null expression, it is an equivalent form of the
5992 original computation, but need not be in the original type.
5994 We set *STRICT_OVERFLOW_P to true if the return values depends on
5995 signed overflow being undefined. Otherwise we do not change
5996 *STRICT_OVERFLOW_P. */
5998 static tree
6001 {
6002 /* To avoid exponential search depth, refuse to allow recursion past
6003 three levels. Beyond that (1) it's highly unlikely that we'll find
6004 something interesting and (2) we've probably processed it before
6005 when we built the inner expression. */
6008 tree ret;
6013 depth++;
6015 depth--;
6018 }
6020 static tree
6023 {
6034 /* Don't deal with constants of zero here; they confuse the code below. */
6044 /* Note that we need not handle conditional operations here since fold
6045 already handles those cases. So just do arithmetic here. */
6047 {
6049 /* For a constant, we can always simplify if we are a multiply
6050 or (for divide and modulus) if it is a multiple of our constant. */
6053 {
6056 /* If the multiplication overflowed, we lost information on it.
6057 See PR68142 and PR69845. */
6061 }
6065 /* If op0 is an expression ... */
6071 /* ... and has wrapping overflow, and its type is smaller
6072 than ctype, then we cannot pass through as widening. */
6077 /* ... or this is a truncation (t is narrower than op0),
6078 then we cannot pass through this narrowing. */
6081 /* ... or signedness changes for division or modulus,
6082 then we cannot pass through this conversion. */
6086 /* ... or has undefined overflow while the converted to
6087 type has not, we cannot do the operation in the inner type
6088 as that would introduce undefined overflow. */
6094 /* Pass the constant down and see if we can make a simplification. If
6095 we can, replace this expression with the inner simplification for
6096 possible later conversion to our or some other type. */
6101 code == MULT_EXPR
6103 strict_overflow_p))))
6108 /* If widening the type changes it from signed to unsigned, then we
6109 must avoid building ABS_EXPR itself as unsigned. */
6111 {
6115 {
6118 }
6120 }
6121 /* If the constant is negative, we cannot simplify this. */
6124 /* FALLTHROUGH */
6126 /* For division and modulus, type can't be unsigned, as e.g.
6127 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6128 For signed types, even with wrapping overflow, this is fine. */
6137 /* If widening the type changes the signedness, then we can't perform
6138 this optimization as that changes the result. */
6142 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6148 {
6155 }
6159 /* If the second operand is constant, this is a multiplication
6160 or floor division, by a power of two, so we can treat it that
6161 way unless the multiplier or divisor overflows. Signed
6162 left-shift overflow is implementation-defined rather than
6163 undefined in C90, so do not convert signed left shift into
6164 multiplication. */
6167 /* const_binop may not detect overflow correctly,
6168 so check for it explicitly here. */
6172 size_one_node,
6173 op1)))
6177 ctype,
6179 t1),
6184 /* See if we can eliminate the operation on both sides. If we can, we
6185 can return a new PLUS or MINUS. If we can't, the only remaining
6186 cases where we can do anything are if the second operand is a
6187 constant. */
6193 /* If not multiplication, we can only do this if both operands
6194 are divisible by c. */
6197 {
6202 }
6204 /* If this was a subtraction, negate OP1 and set it to be an addition.
6205 This simplifies the logic below. */
6207 {
6209 /* If OP1 was not easily negatable, the constant may be OP0. */
6211 {
6214 }
6215 }
6220 /* If either OP1 or C are negative, this optimization is not safe for
6221 some of the division and remainder types while for others we need
6222 to change the code. */
6224 {
6232 }
6234 /* If it's a multiply or a division/modulus operation of a multiple
6235 of our constant, do the operation and verify it doesn't overflow. */
6238 {
6241 /* We allow the constant to overflow with wrapping semantics. */
6245 }
6246 else
6249 /* If we have an unsigned type, we cannot widen the operation since it
6250 will change the result if the original computation overflowed. */
6254 /* If we were able to eliminate our operation from the first side,
6255 apply our operation to the second side and reform the PLUS. */
6259 /* The last case is if we are a multiply. In that case, we can
6260 apply the distributive law to commute the multiply and addition
6261 if the multiplication of the constants doesn't overflow
6262 and overflow is defined. With undefined overflow
6263 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6269 op1);
6274 /* We have a special case here if we are doing something like
6275 (C * 8) % 4 since we know that's zero. */
6278 /* If the multiplication can overflow we cannot optimize this. */
6282 {
6285 }
6287 /* ... fall through ... */
6291 /* If we can extract our operation from the LHS, do so and return a
6292 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6293 do something only if the second operand is a constant. */
6307 /* If these are the same operation types, we can associate them
6308 assuming no overflow. */
6310 {
6325 }
6327 /* If these operations "cancel" each other, we have the main
6328 optimizations of this pass, which occur when either constant is a
6329 multiple of the other, in which case we replace this with either an
6330 operation or CODE or TCODE.
6332 If we have an unsigned type, we cannot do this since it will change
6333 the result if the original computation overflowed. */
6340 {
6342 {
6349 }
6351 {
6358 }
6359 }
6364 }
6367 }
6368 \f
6369 /* Return a node which has the indicated constant VALUE (either 0 or
6370 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6371 and is of the indicated TYPE. */
6373 tree
6375 {
6384 else
6386 }
6389 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6390 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6391 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6392 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6393 COND is the first argument to CODE; otherwise (as in the example
6394 given here), it is the second argument. TYPE is the type of the
6395 original expression. Return NULL_TREE if no simplification is
6396 possible. */
6398 static tree
6403 {
6413 {
6417 /* If this operand throws an expression, then it does not make
6418 sense to try to perform a logical or arithmetic operation
6419 involving it. */
6424 }
6427 {
6432 }
6433 else
6434 /* Detect the case of mixing vector and scalar types - bail out. */
6440 /* This transformation is only worthwhile if we don't have to wrap ARG
6441 in a SAVE_EXPR and the operation can be simplified without recursing
6442 on at least one of the branches once its pushed inside the COND_EXPR. */
6451 {
6455 else
6457 }
6459 {
6463 else
6465 }
6467 /* Check that we have simplified at least one of the branches. */
6472 }
6474 \f
6475 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6477 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6478 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6479 ADDEND is the same as X.
6481 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6482 and finite. The problematic cases are when X is zero, and its mode
6483 has signed zeros. In the case of rounding towards -infinity,
6484 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6485 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6487 bool
6489 {
6493 /* Don't allow the fold with -fsignaling-nans. */
6497 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6501 /* In a vector or complex, we would need to check the sign of all zeros. */
6505 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6509 /* The mode has signed zeros, and we have to honor their sign.
6510 In this situation, there is only one case we can return true for.
6511 X - 0 is the same as X unless rounding towards -infinity is
6512 supported. */
6514 }
6516 /* Subroutine of fold() that optimizes comparisons of a division by
6517 a nonzero integer constant against an integer constant, i.e.
6518 X/C1 op C2.
6520 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6521 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6522 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6524 The function returns the constant folded tree if a simplification
6525 can be made, and NULL_TREE otherwise. */
6527 static tree
6530 {
6538 /* We have to do this the hard way to detect unsigned overflow.
6539 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6545 {
6550 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6554 }
6556 {
6560 {
6579 }
6580 }
6581 else
6582 {
6583 /* A negative divisor reverses the relational operators. */
6589 {
6608 }
6609 }
6612 {
6633 {
6636 }
6641 {
6644 }
6649 {
6652 }
6657 {
6660 }
6665 }
6668 }
6671 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6672 equality/inequality test, then return a simplified form of the test
6673 using a sign testing. Otherwise return NULL. TYPE is the desired
6674 result type. */
6676 static tree
6679 tree result_type)
6680 {
6681 /* If this is testing a single bit, we can optimize the test. */
6685 {
6686 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6687 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6691 /* This is only a win if casting to a signed type is cheap,
6692 i.e. when arg00's type is not a partial mode. */
6695 {
6698 result_type,
6701 }
6702 }
6705 }
6707 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6708 equality/inequality test, then return a simplified form of
6709 the test using shifts and logical operations. Otherwise return
6710 NULL. TYPE is the desired result type. */
6712 tree
6715 {
6716 /* If this is testing a single bit, we can optimize the test. */
6720 {
6729 /* First, see if we can fold the single bit test into a sign-bit
6730 test. */
6732 result_type);
6736 /* Otherwise we have (A & C) != 0 where C is a single bit,
6737 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6738 Similarly for (A & C) == 0. */
6740 /* If INNER is a right shift of a constant and it plus BITNUM does
6741 not overflow, adjust BITNUM and INNER. */
6747 {
6750 }
6752 /* If we are going to be able to omit the AND below, we must do our
6753 operations as unsigned. If we must use the AND, we have a choice.
6754 Normally unsigned is faster, but for some machines signed is. */
6772 /* Put the AND last so it can combine with more things. */
6775 /* Make sure to return the proper type. */
6779 }
6781 }
6783 /* Check whether we are allowed to reorder operands arg0 and arg1,
6784 such that the evaluation of arg1 occurs before arg0. */
6786 static bool
6788 {
6795 }
6797 /* Test whether it is preferable two swap two operands, ARG0 and
6798 ARG1, for example because ARG0 is an integer constant and ARG1
6799 isn't. If REORDER is true, only recommend swapping if we can
6800 evaluate the operands in reverse order. */
6802 bool
6804 {
6822 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6823 for commutative and comparison operators. Ensuring a canonical
6824 form allows the optimizers to find additional redundancies without
6825 having to explicitly check for both orderings. */
6831 /* Put SSA_NAMEs last. */
6837 /* Put variables last. */
6844 }
6847 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6848 means A >= Y && A != MAX, but in this case we know that
6849 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6851 static tree
6853 {
6860 else
6869 {
6872 }
6874 {
6877 }
6878 else
6885 {
6886 /* Convert the pointer types into integer before taking the difference. */
6890 }
6891 else
6898 }
6900 /* Fold a sum or difference of at least one multiplication.
6901 Returns the folded tree or NULL if no simplification could be made. */
6903 static tree
6906 {
6910 /* (A * C) +- (B * C) -> (A+-B) * C.
6911 (A * C) +- A -> A * (C+-1).
6912 We are most concerned about the case where C is a constant,
6913 but other combinations show up during loop reduction. Since
6914 it is not difficult, try all four possibilities. */
6917 {
6920 }
6922 {
6925 }
6926 else
6927 {
6928 /* We cannot generate constant 1 for fract. */
6933 }
6935 {
6938 }
6940 {
6942 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6943 the purpose of this canonicalization. */
6947 {
6950 }
6951 else
6953 }
6954 else
6955 {
6956 /* We cannot generate constant 1 for fract. */
6961 }
6973 /* No identical multiplicands; see if we can find a common
6974 power-of-two factor in non-power-of-two multiplies. This
6975 can help in multi-dimensional array access. */
6978 {
6981 tree maybe_same;
6985 /* Move min of absolute values to int11. */
6987 {
6992 }
6993 else
6997 /* The remainder should not be a constant, otherwise we
6998 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6999 increased the number of multiplications necessary. */
7001 {
7009 }
7010 }
7020 }
7022 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7023 specified by EXPR into the buffer PTR of length LEN bytes.
7024 Return the number of bytes placed in the buffer, or zero
7025 upon failure. */
7027 static int
7029 {
7043 {
7045 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7046 number of bytes. */
7050 {
7057 else
7059 }
7060 else
7065 }
7067 }
7070 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7071 specified by EXPR into the buffer PTR of length LEN bytes.
7072 Return the number of bytes placed in the buffer, or zero
7073 upon failure. */
7075 static int
7077 {
7081 FIXED_VALUE_TYPE value;
7097 }
7100 /* Subroutine of native_encode_expr. Encode the REAL_CST
7101 specified by EXPR into the buffer PTR of length LEN bytes.
7102 Return the number of bytes placed in the buffer, or zero
7103 upon failure. */
7105 static int
7107 {
7113 /* There are always 32 bits in each long, no matter the size of
7114 the hosts long. We handle floating point representations with
7115 up to 192 bits. */
7129 {
7134 {
7141 else
7143 }
7144 else
7145 {
7148 {
7149 /* Reverse bytes within each long, or within the entire float
7150 if it's smaller than a long (for HFmode). */
7153 }
7154 }
7159 }
7161 }
7163 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7164 specified by EXPR into the buffer PTR of length LEN bytes.
7165 Return the number of bytes placed in the buffer, or zero
7166 upon failure. */
7168 static int
7170 {
7172 tree part;
7187 }
7190 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7191 specified by EXPR into the buffer PTR of length LEN bytes.
7192 Return the number of bytes placed in the buffer, or zero
7193 upon failure. */
7195 static int
7197 {
7207 {
7209 {
7212 }
7223 }
7225 }
7228 /* Subroutine of native_encode_expr. Encode the STRING_CST
7229 specified by EXPR into the buffer PTR of length LEN bytes.
7230 Return the number of bytes placed in the buffer, or zero
7231 upon failure. */
7233 static int
7235 {
7237 HOST_WIDE_INT total_bytes;
7251 {
7254 {
7257 }
7260 }
7261 else
7264 }
7267 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7268 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7269 buffer PTR of length LEN bytes. If OFF is not -1 then start
7270 the encoding at byte offset OFF and encode at most LEN bytes.
7271 Return the number of bytes placed in the buffer, or zero upon failure. */
7273 int
7275 {
7276 /* We don't support starting at negative offset and -1 is special. */
7281 {
7302 }
7303 }
7306 /* Subroutine of native_interpret_expr. Interpret the contents of
7307 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7308 If the buffer cannot be interpreted, return NULL_TREE. */
7310 static tree
7312 {
7322 }
7325 /* Subroutine of native_interpret_expr. Interpret the contents of
7326 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7327 If the buffer cannot be interpreted, return NULL_TREE. */
7329 static tree
7331 {
7333 double_int result;
7334 FIXED_VALUE_TYPE fixed_value;
7344 }
7347 /* Subroutine of native_interpret_expr. Interpret the contents of
7348 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7349 If the buffer cannot be interpreted, return NULL_TREE. */
7351 static tree
7353 {
7357 /* There are always 32 bits in each long, no matter the size of
7358 the hosts long. We handle floating point representations with
7359 up to 192 bits. */
7360 REAL_VALUE_TYPE r;
7371 {
7372 /* Both OFFSET and BYTE index within a long;
7373 bitpos indexes the whole float. */
7376 {
7383 else
7385 }
7386 else
7387 {
7390 {
7391 /* Reverse bytes within each long, or within the entire float
7392 if it's smaller than a long (for HFmode). */
7395 }
7396 }
7400 }
7404 }
7407 /* Subroutine of native_interpret_expr. Interpret the contents of
7408 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7409 If the buffer cannot be interpreted, return NULL_TREE. */
7411 static tree
7413 {
7428 }
7431 /* Subroutine of native_interpret_expr. Interpret the contents of
7432 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7433 If the buffer cannot be interpreted, return NULL_TREE. */
7435 static tree
7437 {
7450 {
7455 }
7457 }
7460 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7461 the buffer PTR of length LEN as a constant of type TYPE. For
7462 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7463 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7464 return NULL_TREE. */
7466 tree
7468 {
7470 {
7492 }
7493 }
7495 /* Returns true if we can interpret the contents of a native encoding
7496 as TYPE. */
7498 static bool
7500 {
7502 {
7515 }
7516 }
7518 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7519 TYPE at compile-time. If we're unable to perform the conversion
7520 return NULL_TREE. */
7522 static tree
7524 {
7525 /* We support up to 512-bit values (for V8DFmode). */
7529 /* Check that the host and target are sane. */
7538 }
7540 /* Build an expression for the address of T. Folds away INDIRECT_REF
7541 to avoid confusing the gimplify process. */
7543 tree
7545 {
7546 /* The size of the object is not relevant when talking about its address. */
7551 {
7556 }
7566 {
7571 }
7572 else
7576 }
7578 /* Build an expression for the address of T. */
7580 tree
7582 {
7586 }
7588 /* Fold a unary expression of code CODE and type TYPE with operand
7589 OP0. Return the folded expression if folding is successful.
7590 Otherwise, return NULL_TREE. */
7592 tree
7594 {
7595 tree tem;
7596 tree arg0;
7604 {
7607 {
7608 /* Don't use STRIP_NOPS, because signedness of argument type
7609 matters. */
7611 }
7612 else
7613 {
7614 /* Strip any conversions that don't change the mode. This
7615 is safe for every expression, except for a comparison
7616 expression because its signedness is derived from its
7617 operands.
7619 Note that this is done as an internal manipulation within
7620 the constant folder, in order to find the simplest
7621 representation of the arguments so that their form can be
7622 studied. In any cases, the appropriate type conversions
7623 should be put back in the tree that will get out of the
7624 constant folder. */
7626 }
7629 {
7632 {
7636 }
7637 }
7638 }
7645 {
7652 {
7666 /* If this was a conversion, and all we did was to move into
7667 inside the COND_EXPR, bring it back out. But leave it if
7668 it is a conversion from integer to integer and the
7669 result precision is no wider than a word since such a
7670 conversion is cheap and may be optimized away by combine,
7671 while it couldn't if it were outside the COND_EXPR. Then return
7672 so we don't get into an infinite recursion loop taking the
7673 conversion out and then back in. */
7685 && (INTEGRAL_TYPE_P
7698 }
7699 }
7702 {
7708 CASE_CONVERT:
7712 {
7713 /* If we have (type) (a CMP b) and type is an integral type, return
7714 new expression involving the new type. Canonicalize
7715 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7716 non-integral type.
7717 Do not fold the result as that would not simplify further, also
7718 folding again results in recursions. */
7728 }
7730 /* Handle (T *)&A.B.C for A being of type T and B and C
7731 living at offset zero. This occurs frequently in
7732 C++ upcasting and then accessing the base. */
7736 {
7738 tree offset;
7739 machine_mode mode;
7741 tree base
7745 /* If the reference was to a (constant) zero offset, we can use
7746 the address of the base if it has the same base type
7747 as the result type and the pointer type is unqualified. */
7754 }
7758 /* Detect assigning a bitfield. */
7760 && DECL_BIT_FIELD
7762 {
7763 /* Don't leave an assignment inside a conversion
7764 unless assigning a bitfield. */
7766 /* First do the assignment, then return converted constant. */
7771 }
7773 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7774 constants (if x has signed type, the sign bit cannot be set
7775 in c). This folds extension into the BIT_AND_EXPR.
7776 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7777 very likely don't have maximal range for their precision and this
7778 transformation effectively doesn't preserve non-maximal ranges. */
7782 {
7793 <= HOST_BITS_PER_WIDE_INT
7795 {
7799 cst &= HOST_WIDE_INT_M1U
7803 && !flag_syntax_only
7806 {
7810 }
7811 }
7813 {
7818 }
7819 }
7821 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7822 cast (T1)X will fold away. We assume that this happens when X itself
7823 is a cast. */
7827 {
7831 return fold_build_pointer_plus_loc
7833 }
7835 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7836 of the same precision, and X is an integer type not narrower than
7837 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7843 {
7849 }
7851 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7852 type of X and Y (integer types only). */
7857 {
7858 /* Be careful not to introduce new overflows. */
7859 tree mult_type;
7862 else
7866 {
7873 }
7874 }
7880 {
7887 }
7898 /* Convert fabs((double)float) into (double)fabsf(float). */
7901 {
7907 targ0));
7908 }
7912 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7931 /* Note that the operand of this must be an int
7932 and its values must be 0 or 1.
7933 ("true" is a fixed value perhaps depending on the language,
7934 but we don't handle values other than 1 correctly yet.) */
7941 /* Fold *&X to X if X is an lvalue. */
7943 {
7950 }
7956 }
7959 /* If the operation was a conversion do _not_ mark a resulting constant
7960 with TREE_OVERFLOW if the original constant was not. These conversions
7961 have implementation defined behavior and retaining the TREE_OVERFLOW
7962 flag here would confuse later passes such as VRP. */
7963 tree
7966 {
7975 }
7977 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7978 operands OP0 and OP1. LOC is the location of the resulting expression.
7979 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7980 Return the folded expression if folding is successful. Otherwise,
7981 return NULL_TREE. */
7982 static tree
7985 {
7986 tree tem;
7988 /* We only do these simplifications if we are optimizing. */
7992 /* Check for things like (A || B) && (A || C). We can convert this
7993 to A || (B && C). Note that either operator can be any of the four
7994 truth and/or operations and the transformation will still be
7995 valid. Also note that we only care about order for the
7996 ANDIF and ORIF operators. If B contains side effects, this
7997 might change the truth-value of A. */
8004 {
8024 /* This case if tricky because we must either have commutative
8025 operators or else A10 must not have side-effects. */
8031 a01);
8032 }
8034 /* See if we can build a range comparison. */
8040 {
8044 }
8048 {
8052 }
8054 /* Check for the possibility of merging component references. If our
8055 lhs is another similar operation, try to merge its rhs with our
8056 rhs. Then try to merge our lhs and rhs. */
8070 {
8077 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8078 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8079 We don't want to pack more than two leafs to a non-IF AND/OR
8080 expression.
8081 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8082 equal to IF-CODE, then we don't want to add right-hand operand.
8083 If the inner right-hand side of left-hand operand has
8084 side-effects, or isn't simple, then we can't add to it,
8085 as otherwise we might destroy if-sequence. */
8088 /* Needed for sequence points to handle trappings, and
8089 side-effects. */
8091 {
8093 arg1);
8095 tem);
8096 }
8097 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8098 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8101 /* Needed for sequence points to handle trappings, and
8102 side-effects. */
8104 {
8109 }
8110 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8111 into (A OR B).
8112 For sequence point consistancy, we need to check for trapping,
8113 and side-effects. */
8117 }
8120 }
8122 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8123 by changing CODE to reduce the magnitude of constants involved in
8124 ARG0 of the comparison.
8125 Returns a canonicalized comparison tree if a simplification was
8126 possible, otherwise returns NULL_TREE.
8127 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8128 valid if signed overflow is undefined. */
8130 static tree
8134 {
8139 /* Match A +- CST code arg1. We can change this only if overflow
8140 is undefined. */
8143 /* In principle pointers also have undefined overflow behavior,
8144 but that causes problems elsewhere. */
8151 /* Identify the constant in arg0 and its sign. */
8155 /* Overflowed constants and zero will cause problems. */
8160 /* See if we can reduce the magnitude of the constant in
8161 arg0 by changing the comparison code. */
8162 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8166 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8170 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8174 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8178 else
8182 /* Now build the constant reduced in magnitude. But not if that
8183 would produce one outside of its types range. */
8199 }
8201 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8202 overflow further. Try to decrease the magnitude of constants involved
8203 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8204 and put sole constants at the second argument position.
8205 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8207 static tree
8210 {
8211 tree t;
8216 /* Try canonicalization by simplifying arg0. */
8221 {
8225 }
8227 /* Try canonicalization by simplifying arg1 using the swapped
8228 comparison. */
8236 }
8238 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8239 space. This is used to avoid issuing overflow warnings for
8240 expressions like &p->x which can not wrap. */
8242 static bool
8244 {
8251 wide_int wi_offset;
8257 else
8273 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8274 array. */
8276 {
8277 HOST_WIDE_INT base_size;
8282 }
8285 }
8287 /* Return a positive integer when the symbol DECL is known to have
8288 a nonzero address, zero when it's known not to (e.g., it's a weak
8289 symbol), and a negative integer when the symbol is not yet in the
8290 symbol table and so whether or not its address is zero is unknown. */
8291 static int
8293 {
8299 }
8301 /* Subroutine of fold_binary. This routine performs all of the
8302 transformations that are common to the equality/inequality
8303 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8304 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8305 fold_binary should call fold_binary. Fold a comparison with
8306 tree code CODE and type TYPE with operands OP0 and OP1. Return
8307 the folded comparison or NULL_TREE. */
8309 static tree
8312 {
8322 /* For comparisons of pointers we can decompose it to a compile time
8323 comparison of the base objects and the offsets into the object.
8324 This requires at least one operand being an ADDR_EXPR or a
8325 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8331 {
8334 machine_mode mode;
8338 /* Get base and offset for the access. Strip ADDR_EXPR for
8339 get_inner_reference, but put it back by stripping INDIRECT_REF
8340 off the base object if possible. indirect_baseN will be true
8341 if baseN is not an address but refers to the object itself. */
8344 {
8345 base0
8351 else
8353 }
8355 {
8359 {
8360 base0
8366 else
8368 }
8371 else
8375 {
8381 {
8384 }
8385 }
8386 }
8390 {
8391 base1
8397 else
8399 }
8401 {
8405 {
8406 base1
8412 else
8414 }
8417 else
8421 {
8427 {
8430 }
8431 }
8432 }
8434 /* If we have equivalent bases we might be able to simplify. */
8438 {
8439 /* We can fold this expression to a constant if the non-constant
8440 offset parts are equal. */
8444 && (equality_code
8445 || (indirect_base0
8449 {
8455 "occur when comparing P +- C1 with "
8457 WARN_STRICT_OVERFLOW_CONDITIONAL);
8460 {
8474 }
8475 }
8476 /* We can simplify the comparison to a comparison of the variable
8477 offset parts if the constant offset parts are equal.
8478 Be careful to use signed sizetype here because otherwise we
8479 mess with array offsets in the wrong way. This is possible
8480 because pointer arithmetic is restricted to retain within an
8481 object and overflow on pointer differences is undefined as of
8482 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8484 && (equality_code
8485 || (indirect_base0
8488 {
8489 /* By converting to signed sizetype we cover middle-end pointer
8490 arithmetic which operates on unsigned pointer types of size
8491 type size and ARRAY_REF offsets which are properly sign or
8492 zero extended from their type in case it is narrower than
8493 sizetype. */
8496 else
8500 else
8507 "occur when comparing P +- C1 with "
8509 WARN_STRICT_OVERFLOW_COMPARISON);
8512 }
8513 }
8514 /* For equal offsets we can simplify to a comparison of the
8515 base addresses. */
8517 && (indirect_base0
8519 && (indirect_base1
8524 {
8530 }
8531 /* Comparison between an ordinary (non-weak) symbol and a null
8532 pointer can be eliminated since such symbols must have a non
8533 null address. In C, relational expressions between pointers
8534 to objects and null pointers are undefined. The results
8535 below follow the C++ rules with the additional property that
8536 every object pointer compares greater than a null pointer.
8537 */
8540 /* Avoid folding references to struct members at offset 0 to
8541 prevent tests like '&ptr->firstmember == 0' from getting
8542 eliminated. When ptr is null, although the -> expression
8543 is strictly speaking invalid, GCC retains it as a matter
8544 of QoI. See PR c/44555. */
8546 /* The caller guarantees that when one of the arguments is
8547 constant (i.e., null in this case) it is second. */
8549 {
8551 {
8562 }
8563 }
8564 }
8566 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8567 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8568 the resulting offset is smaller in absolute value than the
8569 original one and has the same sign. */
8578 {
8583 tree cst;
8585 "occur when combining constants around "
8588 /* Put the constant on the side where it doesn't overflow and is
8589 of lower absolute value and of same sign than before. */
8596 {
8599 variable1,
8603 }
8611 {
8617 variable2);
8618 }
8619 }
8625 /* If we are comparing an expression that just has comparisons
8626 of two integer values, arithmetic expressions of those comparisons,
8627 and constants, we can simplify it. There are only three cases
8628 to check: the two values can either be equal, the first can be
8629 greater, or the second can be greater. Fold the expression for
8630 those three values. Since each value must be 0 or 1, we have
8631 eight possibilities, each of which corresponds to the constant 0
8632 or 1 or one of the six possible comparisons.
8634 This handles common cases like (a > b) == 0 but also handles
8635 expressions like ((x > y) - (y > x)) > 0, which supposedly
8636 occur in macroized code. */
8639 {
8644 /* Don't handle degenerate cases here; they should already
8645 have been handled anyway. */
8654 {
8658 /* We can't just pass T to eval_subst in case cval1 or cval2
8659 was the same as ARG1. */
8661 tree high_result
8665 arg1);
8666 tree equal_result
8670 arg1);
8671 tree low_result
8675 arg1);
8677 /* All three of these results should be 0 or 1. Confirm they are.
8678 Then use those values to select the proper code to use. */
8683 {
8684 /* Make a 3-bit mask with the high-order bit being the
8685 value for `>', the next for '=', and the low for '<'. */
8689 {
8691 /* Always false. */
8712 /* Always true. */
8714 }
8717 {
8721 }
8723 }
8724 }
8725 }
8727 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8728 into a single range test. */
8736 {
8740 }
8743 }
8746 /* Subroutine of fold_binary. Optimize complex multiplications of the
8747 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8748 argument EXPR represents the expression "z" of type TYPE. */
8750 static tree
8752 {
8757 {
8760 }
8762 {
8765 }
8766 else
8767 {
8771 }
8780 }
8783 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8784 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8786 static bool
8788 {
8792 {
8795 }
8797 {
8803 else
8805 }
8806 else
8812 }
8814 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8815 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8816 NULL_TREE otherwise. */
8818 static tree
8820 {
8837 {
8841 }
8844 {
8850 }
8851 else
8853 }
8855 /* Try to fold a pointer difference of type TYPE two address expressions of
8856 array references AREF0 and AREF1 using location LOC. Return a
8857 simplified expression for the difference or NULL_TREE. */
8859 static tree
8862 {
8867 /* If the bases are array references as well, recurse. If the bases
8868 are pointer indirections compute the difference of the pointers.
8869 If the bases are equal, we are set. */
8872 && (base_offset
8876 && (base_offset
8882 {
8888 base_offset,
8891 }
8893 }
8895 /* If the real or vector real constant CST of type TYPE has an exact
8896 inverse, return it, else return NULL. */
8898 tree
8900 {
8901 REAL_VALUE_TYPE r;
8903 machine_mode mode;
8907 {
8923 {
8928 }
8934 }
8935 }
8937 /* Mask out the tz least significant bits of X of type TYPE where
8938 tz is the number of trailing zeroes in Y. */
8939 static wide_int
8941 {
8946 }
8948 /* Return true when T is an address and is known to be nonzero.
8949 For floating point we further ensure that T is not denormal.
8950 Similar logic is present in nonzero_address in rtlanal.h.
8952 If the return value is based on the assumption that signed overflow
8953 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8954 change *STRICT_OVERFLOW_P. */
8956 static bool
8958 {
8962 /* Doing something useful for floating point would need more work. */
8968 {
8971 strict_overflow_p);
8977 strict_overflow_p);
8985 }
8988 {
8991 strict_overflow_p);
8999 strict_overflow_p);
9014 strict_overflow_p);
9018 strict_overflow_p);
9021 {
9033 }
9037 }
9039 }
9041 /* Return true when T is an address and is known to be nonzero.
9042 Handle warnings about undefined signed overflow. */
9044 static bool
9046 {
9053 "determining that expression is always "
9055 WARN_STRICT_OVERFLOW_MISC);
9057 }
9059 /* Return true if T is known not to be equal to an integer W. */
9061 bool
9063 {
9065 value_range_type rtype;
9067 {
9076 {
9081 }
9086 /* If T has some known zero bits and W has any of those bits set,
9087 then T is known not to be equal to W. */
9095 }
9096 }
9098 /* Fold a binary expression of code CODE and type TYPE with operands
9099 OP0 and OP1. LOC is the location of the resulting expression.
9100 Return the folded expression if folding is successful. Otherwise,
9101 return NULL_TREE. */
9103 tree
9106 {
9121 /* Strip any conversions that don't change the mode. This is
9122 safe for every expression, except for a comparison expression
9123 because its signedness is derived from its operands. So, in
9124 the latter case, only strip conversions that don't change the
9125 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9126 preserved.
9128 Note that this is done as an internal manipulation within the
9129 constant folder, in order to find the simplest representation
9130 of the arguments so that their form can be studied. In any
9131 cases, the appropriate type conversions should be put back in
9132 the tree that will get out of the constant folder. */
9135 {
9138 }
9139 else
9140 {
9143 }
9145 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9146 constant but we can't do arithmetic on them. */
9148 {
9151 {
9155 }
9156 }
9158 /* If this is a commutative operation, and ARG0 is a constant, move it
9159 to ARG1 to reduce the number of tests below. */
9164 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9165 to ARG1 to reduce the number of tests below. */
9174 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9176 First check for cases where an arithmetic operation is applied to a
9177 compound, conditional, or comparison operation. Push the arithmetic
9178 operation inside the compound or conditional to see if any folding
9179 can then be done. Convert comparison to conditional for this purpose.
9180 The also optimizes non-constant cases that used to be done in
9181 expand_expr.
9183 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9184 one of the operands is a comparison and the other is a comparison, a
9185 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9186 code below would make the expression more complex. Change it to a
9187 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9188 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9201 {
9205 boolean_type_node,
9213 }
9217 {
9219 {
9224 tem);
9225 }
9228 {
9233 tem);
9234 }
9239 {
9245 }
9250 {
9256 }
9257 }
9260 {
9262 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9265 {
9271 }
9273 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9276 {
9277 tree base;
9278 HOST_WIDE_INT coffset;
9287 }
9292 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9298 arg1),
9300 arg0)));
9306 {
9307 /* X + (X / CST) * -CST is X % CST. */
9312 {
9321 cst0));
9322 }
9323 }
9325 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9326 one. Make sure the type is not saturating and has the signedness of
9327 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9328 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9335 {
9339 }
9342 {
9343 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9344 (plus (plus (mult) (mult)) (foo)) so that we can
9345 take advantage of the factoring cases below. */
9354 {
9360 else
9373 parg0),
9375 marg)),
9379 return
9385 parg1)));
9386 }
9387 }
9388 else
9389 {
9390 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9391 to __complex__ ( x, y ). This is not the same for SNaNs or
9392 if signed zeros are involved. */
9396 {
9403 {
9407 {
9413 }
9415 {
9421 }
9422 }
9423 }
9431 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9432 We associate floats only if the user has specified
9433 -fassociative-math. */
9437 {
9442 {
9443 tree tree0;
9446 }
9447 }
9448 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9449 We associate floats only if the user has specified
9450 -fassociative-math. */
9454 {
9459 {
9460 tree tree0;
9463 }
9464 }
9465 }
9467 bit_rotate:
9468 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9469 is a rotate of A by C1 bits. */
9470 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9471 is a rotate of A by B bits. */
9472 {
9474 tree rtype;
9483 /* Only create rotates in complete modes. Other cases are not
9484 expanded properly. */
9487 {
9501 {
9505 code0 == LSHIFT_EXPR
9509 }
9511 {
9519 element_precision
9523 return
9526 ? LROTATE_EXPR
9531 }
9533 {
9541 element_precision
9545 return fold_convert_loc
9548 ? LROTATE_EXPR
9552 }
9553 }
9554 }
9556 associate:
9557 /* In most languages, can't associate operations on floats through
9558 parentheses. Rather than remember where the parentheses were, we
9559 don't associate floats at all, unless the user has specified
9560 -fassociative-math.
9561 And, we need to make sure type is not saturating. */
9565 {
9571 /* Split both trees into variables, constants, and literals. Then
9572 associate each group together, the constants with literals,
9573 then the result with variables. This increases the chances of
9574 literals being recombined later and of generating relocatable
9575 expressions for the sum of a constant and literal. */
9581 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9585 /* With undefined overflow prefer doing association in a type
9586 which wraps on overflow, if that is one of the operand types. */
9589 {
9597 }
9599 /* With undefined overflow we can only associate constants with one
9600 variable, and constants whose association doesn't overflow. */
9603 {
9605 {
9611 {
9614 }
9621 {
9624 }
9630 /* The only case we can still associate with two variables
9631 is if they cancel out. */
9635 }
9636 }
9638 /* Only do something if we found more than two objects. Otherwise,
9639 nothing has changed and we risk infinite recursion. */
9645 {
9657 /* Preserve the MINUS_EXPR if the negative part of the literal is
9658 greater than the positive part. Otherwise, the multiplicative
9659 folding code (i.e extract_muldiv) may be fooled in case
9660 unsigned constants are subtracted, like in the following
9661 example: ((X*2 + 4) - 8U)/2. */
9663 {
9667 {
9671 }
9672 else
9673 {
9677 }
9678 }
9680 /* Don't introduce overflows through reassociation. */
9687 {
9689 return
9693 else
9694 {
9697 return
9701 }
9702 }
9705 return
9708 }
9709 }
9714 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9723 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9724 __complex__ ( x, -y ). This is not the same for SNaNs or if
9725 signed zeros are involved. */
9729 {
9736 {
9740 {
9742 arg1r ? arg1r
9747 }
9749 {
9753 arg1i ? arg1i
9756 }
9757 }
9758 }
9760 /* A - B -> A + (-B) if B is easily negatable. */
9764 /* Avoid this transformation if B is a positive REAL_CST. */
9772 /* Fold &a[i] - &a[j] to i-j. */
9777 {
9783 }
9786 && flag_unsafe_math_optimizations
9792 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9793 one. Make sure the type is not saturating and has the signedness of
9794 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9795 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9802 {
9806 }
9812 {
9813 /* Transform x * -C into -x * C if x is easily negatable. */
9827 {
9830 "occur when simplifying "
9832 WARN_STRICT_OVERFLOW_MISC);
9834 }
9836 /* Optimize z * conj(z) for integer complex numbers. */
9843 }
9844 else
9845 {
9846 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9847 This is not the same for NaNs or if signed zeros are
9848 involved. */
9854 {
9857 return
9863 return
9868 }
9870 /* Optimize z * conj(z) for floating point complex numbers.
9871 Guarded by flag_unsafe_math_optimizations as non-finite
9872 imaginary components don't produce scalar results. */
9881 }
9885 /* Canonicalize (X & C1) | C2. */
9889 {
9894 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9902 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9907 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9908 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9909 mode which allows further optimizations. */
9914 {
9918 {
9921 }
9922 }
9929 c3)),
9930 arg1);
9931 }
9933 /* See if this can be simplified into a rotate first. If that
9934 is unsuccessful continue in the association code. */
9938 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9946 /* See if this can be simplified into a rotate first. If that
9947 is unsuccessful continue in the association code. */
9951 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9956 {
9957 tree tem2;
9964 }
9965 /* Fold ~X & 1 as (X & 1) == 0. */
9969 {
9970 tree tem2;
9977 }
9978 /* Fold !X & 1 as X == 0. */
9981 {
9985 }
9987 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9988 multiple of 1 << CST. */
9990 {
9997 }
9999 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10000 bits from CST2. */
10004 {
10012 {
10013 /* Avoid the transform if arg1 is a mask of some
10014 mode which allows further optimizations. */
10021 }
10022 }
10024 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10025 ((A & N) + B) & M -> (A + B) & M
10026 Similarly if (N & M) == 0,
10027 ((A | N) + B) & M -> (A + B) & M
10028 and for - instead of + (or unary - instead of +)
10029 and/or ^ instead of |.
10030 If B is constant and (B & M) == 0, fold into A & M. */
10032 {
10041 {
10044 wide_int cst0;
10046 /* Now we know that arg0 is (C + D) or (C - D) or
10047 -C and arg1 (M) is == (1LL << cst) - 1.
10048 Store C into PMOP[0] and D into PMOP[1]. */
10052 {
10055 }
10062 {
10072 {
10075 }
10078 /* If C or D is of the form (A & N) where
10079 (N & M) == M, or of the form (A | N) or
10080 (A ^ N) where (N & M) == 0, replace it with A. */
10084 /* If C or D is a N where (N & M) == 0, it can be
10085 omitted (assumed 0). */
10093 }
10095 /* Only build anything new if we optimized one or both arguments
10096 above. */
10100 {
10103 {
10104 /* Perform the operations in a type that has defined
10105 overflow behavior. */
10111 }
10116 {
10124 else
10126 }
10129 else
10132 /* TEM is now the new binary +, - or unary - replacement. */
10136 }
10137 }
10138 }
10140 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10143 {
10148 return
10150 }
10155 /* Don't touch a floating-point divide by zero unless the mode
10156 of the constant can represent infinity. */
10162 /* (-A) / (-B) -> A / B */
10174 /* Fall through */
10177 /* Simplify A / (B << N) where A and B are positive and B is
10178 a power of 2, to A >> (N + log2(B)). */
10183 {
10186 {
10194 WARN_STRICT_OVERFLOW_MISC);
10200 }
10201 }
10203 /* Fall through */
10211 /* Convert -A / -B to A / B when the type is signed and overflow is
10212 undefined. */
10216 {
10219 "when distributing negation across "
10221 WARN_STRICT_OVERFLOW_MISC);
10226 }
10230 {
10233 "when distributing negation across "
10235 WARN_STRICT_OVERFLOW_MISC);
10240 }
10242 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10243 operation, EXACT_DIV_EXPR.
10245 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10246 At one time others generated faster code, it's not clear if they do
10247 after the last round to changes to the DIV code in expmed.c. */
10258 {
10262 WARN_STRICT_OVERFLOW_MISC);
10264 }
10276 {
10280 WARN_STRICT_OVERFLOW_MISC);
10282 }
10290 /* Since negative shift count is not well-defined,
10291 don't try to compute it in the compiler. */
10297 /* If we have a rotate of a bit operation with the rotate count and
10298 the second operand of the bit operation both constant,
10299 permute the two operations. */
10305 {
10313 }
10315 /* Two consecutive rotates adding up to the some integer
10316 multiple of the precision of the type can be ignored. */
10331 /* Note that the operands of this must be ints
10332 and their values must be 0 or 1.
10333 ("true" is a fixed value perhaps depending on the language.) */
10334 /* If first arg is constant zero, return it. */
10337 /* FALLTHRU */
10339 /* If either arg is constant true, drop it. */
10343 /* Preserve sequence points. */
10346 /* If second arg is constant zero, result is zero, but first arg
10347 must be evaluated. */
10350 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10351 case will be handled here. */
10355 /* !X && X is always false. */
10359 /* X && !X is always false. */
10364 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10365 means A >= Y && A != MAX, but in this case we know that
10366 A < X <= MAX. */
10370 {
10378 }
10387 /* Note that the operands of this must be ints
10388 and their values must be 0 or true.
10389 ("true" is a fixed value perhaps depending on the language.) */
10390 /* If first arg is constant true, return it. */
10393 /* FALLTHRU */
10395 /* If either arg is constant zero, drop it. */
10399 /* Preserve sequence points. */
10402 /* If second arg is constant true, result is true, but we must
10403 evaluate first arg. */
10406 /* Likewise for first arg, but note this only occurs here for
10407 TRUTH_OR_EXPR. */
10411 /* !X || X is always true. */
10415 /* X || !X is always true. */
10420 /* (X && !Y) || (!X && Y) is X ^ Y */
10423 {
10440 }
10449 /* If the second arg is constant zero, drop it. */
10452 /* If the second arg is constant true, this is a logical inversion. */
10454 {
10457 }
10458 /* Identical arguments cancel to zero. */
10462 /* !X ^ X is always true. */
10467 /* X ^ !X is always true. */
10483 /* bool_var != 1 becomes !bool_var. */
10490 /* bool_var == 0 becomes !bool_var. */
10497 /* !exp != 0 becomes !exp */
10502 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10511 {
10517 }
10519 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10528 {
10534 }
10536 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10544 code == NE_EXPR
10548 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10556 code == NE_EXPR
10560 /* If this is an EQ or NE comparison with zero and ARG0 is
10561 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10562 two operations, but the latter can be done in one less insn
10563 on machines that have only two-operand insns or on which a
10564 constant cannot be the first operand. */
10567 {
10572 {
10579 arg1);
10580 }
10583 {
10590 arg1);
10591 }
10592 }
10594 /* If this is an NE or EQ comparison of zero against the result of a
10595 signed MOD operation whose second operand is a power of 2, make
10596 the MOD operation unsigned since it is simpler and equivalent. */
10604 {
10614 }
10616 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10617 C1 is a valid shift constant, and C2 is a power of two, i.e.
10618 a single bit. */
10622 == INTEGER_CST
10625 {
10630 /* Check for a valid shift count. */
10632 {
10636 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10637 can be rewritten as (X & (C2 << C1)) != 0. */
10639 {
10644 }
10645 /* Otherwise, for signed (arithmetic) shifts,
10646 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10647 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10651 /* Otherwise, of unsigned (logical) shifts,
10652 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10653 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10654 else
10658 arg000);
10659 }
10660 }
10662 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10663 Similarly for NE_EXPR. */
10667 {
10671 tree dandnotc
10674 notc);
10678 }
10680 /* If this is a comparison of a field, we may be able to simplify it. */
10683 /* Handle the constant case even without -O
10684 to make sure the warnings are given. */
10686 {
10690 }
10692 /* Optimize comparisons of strlen vs zero to a compare of the
10693 first character of the string vs zero. To wit,
10694 strlen(ptr) == 0 => *ptr == 0
10695 strlen(ptr) != 0 => *ptr != 0
10696 Other cases should reduce to one of these two (or a constant)
10697 due to the return value of strlen being unsigned. */
10700 {
10708 {
10713 }
10714 }
10716 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10717 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10721 {
10726 {
10728 {
10731 }
10734 }
10735 }
10737 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10738 (X & C) == 0 when C is a single bit. */
10743 {
10750 arg1));
10751 }
10753 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10754 constant C is a power of two, i.e. a single bit. */
10761 {
10765 }
10767 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10768 when is C is a power of two, i.e. a single bit. */
10775 {
10781 }
10785 {
10788 }
10790 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10793 {
10806 arg01),
10815 arg01),
10824 arg00),
10833 arg00),
10835 }
10839 {
10846 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10847 operand_equal_p guarantees no side-effects so we don't need
10848 to use omit_one_operand on Z. */
10852 arg10));
10856 arg11));
10860 arg10));
10864 arg11));
10866 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10869 {
10875 }
10876 }
10878 /* Attempt to simplify equality/inequality comparisons of complex
10879 values. Only lower the comparison if the result is known or
10880 can be simplified to a single scalar comparison. */
10885 {
10890 {
10893 }
10894 else
10895 {
10898 }
10901 {
10904 }
10905 else
10906 {
10909 }
10913 {
10915 {
10920 }
10921 else
10922 {
10927 }
10928 }
10932 {
10934 {
10939 }
10940 else
10941 {
10946 }
10947 }
10948 }
10960 /* Transform comparisons of the form X +- C CMP X. */
10967 {
10974 else
10977 /* (X - c) > X becomes false. */
10981 {
10985 "occur when assuming that (X - c) > X "
10987 WARN_STRICT_OVERFLOW_ALL);
10989 }
10991 /* Likewise (X + c) < X becomes false. */
10995 {
10999 "occur when assuming that "
11001 WARN_STRICT_OVERFLOW_ALL);
11003 }
11005 /* Convert (X - c) <= X to true. */
11010 {
11014 "occur when assuming that "
11016 WARN_STRICT_OVERFLOW_ALL);
11018 }
11020 /* Convert (X + c) >= X to true. */
11025 {
11029 "occur when assuming that "
11031 WARN_STRICT_OVERFLOW_ALL);
11033 }
11036 {
11037 /* Convert X + c > X and X - c < X to true for integers. */
11041 {
11044 "not occur when assuming that "
11046 WARN_STRICT_OVERFLOW_ALL);
11048 }
11053 {
11056 "not occur when assuming that "
11058 WARN_STRICT_OVERFLOW_ALL);
11060 }
11062 /* Convert X + c <= X and X - c >= X to false for integers. */
11066 {
11069 "not occur when assuming that "
11071 WARN_STRICT_OVERFLOW_ALL);
11073 }
11078 {
11081 "not occur when assuming that "
11083 WARN_STRICT_OVERFLOW_ALL);
11085 }
11086 }
11087 }
11089 /* If we are comparing an ABS_EXPR with a constant, we can
11090 convert all the cases into explicit comparisons, but they may
11091 well not be faster than doing the ABS and one comparison.
11092 But ABS (X) <= C is a range comparison, which becomes a subtraction
11093 and a comparison, and is probably faster. */
11107 /* Convert ABS_EXPR<x> >= 0 to true. */
11114 {
11117 "when simplifying comparison of "
11119 WARN_STRICT_OVERFLOW_CONDITIONAL);
11122 arg0);
11123 }
11125 /* Convert ABS_EXPR<x> < 0 to false. */
11130 {
11133 "when simplifying comparison of "
11135 WARN_STRICT_OVERFLOW_CONDITIONAL);
11138 arg0);
11139 }
11141 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11142 and similarly for >= into !=. */
11152 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11153 otherwise Y might be >= # of bits in X's type and thus e.g.
11154 (unsigned char) (1 << Y) for Y 15 might be 0.
11155 If the cast is widening, then 1 << Y should have unsigned type,
11156 otherwise if Y is number of bits in the signed shift type minus 1,
11157 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11158 31 might be 0xffffffff80000000. */
11169 {
11175 }
11187 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11188 {
11200 }
11205 /* When pedantic, a compound expression can be neither an lvalue
11206 nor an integer constant expression. */
11209 /* Don't let (0, 0) be null pointer constant. */
11215 /* An ASSERT_EXPR should never be passed to fold_binary. */
11221 }
11223 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11224 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11225 of GOTO_EXPR. */
11227 static tree
11229 {
11231 {
11238 /* fall through */
11242 }
11243 }
11245 /* Return whether the sub-tree ST contains a label which is accessible from
11246 outside the sub-tree. */
11248 static bool
11250 {
11251 return
11253 }
11255 /* Fold a ternary expression of code CODE and type TYPE with operands
11256 OP0, OP1, and OP2. Return the folded expression if folding is
11257 successful. Otherwise, return NULL_TREE. */
11259 tree
11262 {
11263 tree tem;
11270 /* If this is a commutative operation, and OP0 is a constant, move it
11271 to OP1 to reduce the number of tests below. */
11280 /* Strip any conversions that don't change the mode. This is safe
11281 for every expression, except for a comparison expression because
11282 its signedness is derived from its operands. So, in the latter
11283 case, only strip conversions that don't change the signedness.
11285 Note that this is done as an internal manipulation within the
11286 constant folder, in order to find the simplest representation of
11287 the arguments so that their form can be studied. In any cases,
11288 the appropriate type conversions should be put back in the tree
11289 that will get out of the constant folder. */
11291 {
11294 }
11297 {
11300 }
11303 {
11306 }
11309 {
11313 {
11319 }
11324 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11325 so all simple results must be passed through pedantic_non_lvalue. */
11327 {
11330 /* Only optimize constant conditions when the selected branch
11331 has the same type as the COND_EXPR. This avoids optimizing
11332 away "c ? x : throw", where the throw has a void type.
11333 Avoid throwing away that operand which contains label. */
11340 }
11342 {
11347 {
11352 {
11360 }
11364 }
11365 }
11367 /* If we have A op B ? A : C, we may be able to convert this to a
11368 simpler expression, depending on the operation and the values
11369 of B and C. Signed zeros prevent all of these transformations,
11370 for reasons given above each one.
11372 Also try swapping the arguments and inverting the conditional. */
11377 {
11381 }
11385 op2,
11388 {
11392 {
11396 }
11397 }
11399 /* If the second operand is simpler than the third, swap them
11400 since that produces better jump optimization results. */
11403 {
11405 /* See if this can be inverted. If it can't, possibly because
11406 it was a floating-point inequality comparison, don't do
11407 anything. */
11411 }
11413 /* Convert A ? 1 : 0 to simply A. */
11418 /* If we try to convert OP0 to our type, the
11419 call to fold will try to move the conversion inside
11420 a COND, which will recurse. In that case, the COND_EXPR
11421 is probably the best choice, so leave it alone. */
11425 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11426 over COND_EXPR in cases such as floating point comparisons. */
11435 arg0)));
11437 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11442 {
11443 /* sign_bit_p looks through both zero and sign extensions,
11444 but for this optimization only sign extensions are
11445 usable. */
11448 {
11451 {
11454 }
11456 }
11457 /* sign_bit_p only checks ARG1 bits within A's precision.
11458 If <sign bit of A> has wider type than A, bits outside
11459 of A's precision in <sign bit of A> need to be checked.
11460 If they are all 0, this optimization needs to be done
11461 in unsigned A's type, if they are all 1 in signed A's type,
11462 otherwise this can't be done. */
11468 {
11470 tree tem_type;
11483 {
11486 }
11488 {
11491 }
11492 else
11494 }
11497 return
11503 arg1)));
11504 }
11506 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11507 already handled above. */
11512 {
11521 }
11523 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11524 is probably obsolete because the first operand should be a
11525 truth value (that's why we have the two cases above), but let's
11526 leave it in until we can confirm this for all front-ends. */
11538 /* Disable the transformations below for vectors, since
11539 fold_binary_op_with_conditional_arg may undo them immediately,
11540 yielding an infinite loop. */
11544 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11553 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11558 {
11560 /* Only perform transformation if ARG0 is easily inverted. */
11564 ? BIT_IOR_EXPR
11567 arg1);
11568 }
11570 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11575 {
11577 /* Only perform transformation if ARG0 is easily inverted. */
11583 op2);
11584 }
11586 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11598 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11599 of fold_ternary on them. */
11607 {
11617 {
11622 {
11630 }
11631 }
11632 }
11634 /* On constants we can use native encode/interpret to constant
11635 fold (nearly) all BIT_FIELD_REFs. */
11639 {
11642 /* Limit us to a reasonable amount of work. To relax the
11643 other limitations we need bit-shifting of the buffer
11644 and rounding up the size. */
11648 {
11650 unsigned HOST_WIDE_INT len
11655 {
11660 }
11661 }
11662 }
11667 /* For integers we can decompose the FMA if possible. */
11679 {
11695 {
11700 /* Make sure that the perm value is in an acceptable
11701 range. */
11710 else
11715 }
11718 {
11723 }
11728 {
11733 }
11739 {
11743 }
11748 /* Some targets are deficient and fail to expand a single
11749 argument permutation while still allowing an equivalent
11750 2-argument version. */
11754 {
11757 }
11760 {
11767 }
11771 }
11775 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11778 {
11784 wide_int tem2
11788 }
11793 {
11795 unsigned HOST_WIDE_INT elsize
11798 {
11802 else
11803 {
11809 }
11810 }
11811 }
11817 }
11819 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11820 of an array (or vector). */
11822 tree
11824 {
11829 {
11832 {
11833 /* Static constructors for variably sized objects makes no sense. */
11837 }
11838 }
11849 offset_int max_index;
11854 {
11855 /* Array constructor might explicitly set index, or specify a range,
11856 or leave index NULL meaning that it is next index after previous
11857 one. */
11859 {
11862 else
11863 {
11867 }
11868 }
11869 else
11870 {
11876 }
11878 /* Do we have match? */
11882 }
11884 }
11886 /* Perform constant folding and related simplification of EXPR.
11887 The related simplifications include x*1 => x, x*0 => 0, etc.,
11888 and application of the associative law.
11889 NOP_EXPR conversions may be removed freely (as long as we
11890 are careful not to change the type of the overall expression).
11891 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11892 but we can constant-fold them if they have constant operands. */
11894 #ifdef ENABLE_FOLD_CHECKING
11895 # define fold(x) fold_1 (x)
11897 static
11898 #endif
11899 tree
11901 {
11905 tree tem;
11908 /* Return right away if a constant. */
11912 /* CALL_EXPR-like objects with variable numbers of operands are
11913 treated specially. */
11915 {
11917 {
11920 }
11922 }
11925 {
11930 {
11948 }
11949 }
11952 {
11954 {
11961 {
11966 }
11969 }
11971 /* Return a VECTOR_CST if possible. */
11973 {
11979 tree val;
11985 }
11993 }
11995 #ifdef ENABLE_FOLD_CHECKING
11996 #undef fold
12003 /* When --enable-checking=fold, compute a digest of expr before
12004 and after actual fold call to see if fold did not accidentally
12005 change original expr. */
12007 tree
12009 {
12010 tree ret;
12030 }
12032 void
12034 {
12045 }
12047 static void
12049 {
12051 }
12053 static void
12056 {
12062 recursive_label:
12072 {
12073 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12078 }
12086 {
12087 /* Allow these fields to be modified. */
12088 tree tmp;
12097 {
12100 }
12101 }
12112 {
12115 {
12130 }
12134 {
12147 }
12164 {
12170 }
12173 {
12175 {
12178 }
12180 }
12191 {
12194 }
12204 }
12205 }
12207 /* Helper function for outputting the checksum of a tree T. When
12208 debugging with gdb, you can "define mynext" to be "next" followed
12209 by "call debug_fold_checksum (op0)", then just trace down till the
12210 outputs differ. */
12212 DEBUG_FUNCTION void
12214 {
12229 }
12231 #endif
12233 /* Fold a unary tree expression with code CODE of type TYPE with an
12234 operand OP0. LOC is the location of the resulting expression.
12235 Return a folded expression if successful. Otherwise, return a tree
12236 expression with code CODE of type TYPE with an operand OP0. */
12238 tree
12241 {
12242 tree tem;
12243 #ifdef ENABLE_FOLD_CHECKING
12252 #endif
12258 #ifdef ENABLE_FOLD_CHECKING
12265 #endif
12267 }
12269 /* Fold a binary tree expression with code CODE of type TYPE with
12270 operands OP0 and OP1. LOC is the location of the resulting
12271 expression. Return a folded expression if successful. Otherwise,
12272 return a tree expression with code CODE of type TYPE with operands
12273 OP0 and OP1. */
12275 tree
12278 MEM_STAT_DECL)
12279 {
12280 tree tem;
12281 #ifdef ENABLE_FOLD_CHECKING
12298 #endif
12304 #ifdef ENABLE_FOLD_CHECKING
12319 #endif
12321 }
12323 /* Fold a ternary tree expression with code CODE of type TYPE with
12324 operands OP0, OP1, and OP2. Return a folded expression if
12325 successful. Otherwise, return a tree expression with code CODE of
12326 type TYPE with operands OP0, OP1, and OP2. */
12328 tree
12331 {
12332 tree tem;
12333 #ifdef ENABLE_FOLD_CHECKING
12357 #endif
12364 #ifdef ENABLE_FOLD_CHECKING
12387 #endif
12389 }
12391 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12392 arguments in ARGARRAY, and a null static chain.
12393 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12394 of type TYPE from the given operands as constructed by build_call_array. */
12396 tree
12399 {
12400 tree tem;
12401 #ifdef ENABLE_FOLD_CHECKING
12420 #endif
12426 #ifdef ENABLE_FOLD_CHECKING
12442 #endif
12444 }
12446 /* Perform constant folding and related simplification of initializer
12447 expression EXPR. These behave identically to "fold_buildN" but ignore
12448 potential run-time traps and exceptions that fold must preserve. */
12450 #define START_FOLD_INIT \
12451 int saved_signaling_nans = flag_signaling_nans;\
12452 int saved_trapping_math = flag_trapping_math;\
12453 int saved_rounding_math = flag_rounding_math;\
12454 int saved_trapv = flag_trapv;\
12455 int saved_folding_initializer = folding_initializer;\
12456 flag_signaling_nans = 0;\
12457 flag_trapping_math = 0;\
12458 flag_rounding_math = 0;\
12459 flag_trapv = 0;\
12460 folding_initializer = 1;
12462 #define END_FOLD_INIT \
12463 flag_signaling_nans = saved_signaling_nans;\
12464 flag_trapping_math = saved_trapping_math;\
12465 flag_rounding_math = saved_rounding_math;\
12466 flag_trapv = saved_trapv;\
12467 folding_initializer = saved_folding_initializer;
12469 tree
12472 {
12473 tree result;
12474 START_FOLD_INIT;
12478 END_FOLD_INIT;
12480 }
12482 tree
12485 {
12486 tree result;
12487 START_FOLD_INIT;
12491 END_FOLD_INIT;
12493 }
12495 tree
12498 {
12499 tree result;
12500 START_FOLD_INIT;
12504 END_FOLD_INIT;
12506 }
12508 #undef START_FOLD_INIT
12509 #undef END_FOLD_INIT
12511 /* Determine if first argument is a multiple of second argument. Return 0 if
12512 it is not, or we cannot easily determined it to be.
12514 An example of the sort of thing we care about (at this point; this routine
12515 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12516 fold cases do now) is discovering that
12518 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12520 is a multiple of
12522 SAVE_EXPR (J * 8)
12524 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12526 This code also handles discovering that
12528 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12530 is a multiple of 8 so we don't have to worry about dealing with a
12531 possible remainder.
12533 Note that we *look* inside a SAVE_EXPR only to determine how it was
12534 calculated; it is not safe for fold to do much of anything else with the
12535 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12536 at run time. For example, the latter example above *cannot* be implemented
12537 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12538 evaluation time of the original SAVE_EXPR is not necessarily the same at
12539 the time the new expression is evaluated. The only optimization of this
12540 sort that would be valid is changing
12542 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12544 divided by 8 to
12546 SAVE_EXPR (I) * SAVE_EXPR (J)
12548 (where the same SAVE_EXPR (J) is used in the original and the
12549 transformed version). */
12551 int
12553 {
12564 {
12566 /* Bitwise and provides a power of two multiple. If the mask is
12567 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12570 /* FALLTHRU */
12577 /* It is impossible to prove if op0 - op1 is multiple of bottom
12578 precisely, so be conservative here checking if both op0 and op1
12579 are multiple of bottom. Note we check the second operand first
12580 since it's usually simpler. */
12585 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12586 as op0 - 3 if the expression has unsigned type. For example,
12587 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12597 {
12599 /* const_binop may not detect overflow correctly,
12600 so check for it explicitly here. */
12604 size_one_node,
12605 op1)))
12608 }
12612 /* Can't handle conversions from non-integral or wider integral type. */
12618 /* fall through */
12635 SIGNED);
12641 {
12644 /* Check for special cases to see if top is defined as multiple
12645 of bottom:
12647 top = (X & ~(bottom - 1) ; bottom is power of 2
12649 or
12651 Y = X % bottom
12652 top = X - Y. */
12671 }
12673 /* fall through */
12677 }
12678 }
12680 #define tree_expr_nonnegative_warnv_p(X, Y) \
12683 #define RECURSE(X) \
12684 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12686 /* Return true if CODE or TYPE is known to be non-negative. */
12688 static bool
12690 {
12693 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12694 have a signed:1 type (where the value is -1 and 0). */
12697 }
12699 /* Return true if (CODE OP0) is known to be non-negative. If the return
12700 value is based on the assumption that signed overflow is undefined,
12701 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12702 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12704 bool
12707 {
12712 {
12714 /* We can't return 1 if flag_wrapv is set because
12715 ABS_EXPR<INT_MIN> = INT_MIN. */
12719 {
12722 }
12730 CASE_CONVERT:
12731 {
12736 {
12740 {
12744 }
12745 }
12747 {
12753 }
12754 }
12759 }
12761 /* We don't know sign of `t', so be conservative and return false. */
12763 }
12765 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12766 value is based on the assumption that signed overflow is undefined,
12767 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12768 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12770 bool
12774 {
12779 {
12785 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12786 both unsigned and at least 2 bits shorter than the result. */
12790 {
12795 {
12799 }
12800 }
12805 {
12806 /* x * x is always non-negative for floating point x
12807 or without overflow. */
12810 {
12815 }
12816 }
12818 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12819 both unsigned and their total bits is shorter than the result. */
12823 {
12842 {
12852 }
12853 }
12880 }
12882 /* We don't know sign of `t', so be conservative and return false. */
12884 }
12886 /* Return true if T is known to be non-negative. If the return
12887 value is based on the assumption that signed overflow is undefined,
12888 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12889 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12891 bool
12893 {
12898 {
12912 /* Limit the depth of recursion to avoid quadratic behavior.
12913 This is expected to catch almost all occurrences in practice.
12914 If this code misses important cases that unbounded recursion
12915 would not, passes that need this information could be revised
12916 to provide it through dataflow propagation. */
12924 }
12925 }
12927 /* Return true if T is known to be non-negative. If the return
12928 value is based on the assumption that signed overflow is undefined,
12929 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12930 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12932 bool
12935 {
12937 {
12938 CASE_CFN_ACOS:
12939 CASE_CFN_ACOSH:
12940 CASE_CFN_CABS:
12941 CASE_CFN_COSH:
12942 CASE_CFN_ERFC:
12943 CASE_CFN_EXP:
12944 CASE_CFN_EXP10:
12945 CASE_CFN_EXP2:
12946 CASE_CFN_FABS:
12947 CASE_CFN_FDIM:
12948 CASE_CFN_HYPOT:
12949 CASE_CFN_POW10:
12950 CASE_CFN_FFS:
12951 CASE_CFN_PARITY:
12952 CASE_CFN_POPCOUNT:
12953 CASE_CFN_CLZ:
12954 CASE_CFN_CLRSB:
12957 /* Always true. */
12960 CASE_CFN_SQRT:
12961 /* sqrt(-0.0) is -0.0. */
12966 CASE_CFN_ASINH:
12967 CASE_CFN_ATAN:
12968 CASE_CFN_ATANH:
12969 CASE_CFN_CBRT:
12970 CASE_CFN_CEIL:
12971 CASE_CFN_ERF:
12972 CASE_CFN_EXPM1:
12973 CASE_CFN_FLOOR:
12974 CASE_CFN_FMOD:
12975 CASE_CFN_FREXP:
12976 CASE_CFN_ICEIL:
12977 CASE_CFN_IFLOOR:
12978 CASE_CFN_IRINT:
12979 CASE_CFN_IROUND:
12980 CASE_CFN_LCEIL:
12981 CASE_CFN_LDEXP:
12982 CASE_CFN_LFLOOR:
12983 CASE_CFN_LLCEIL:
12984 CASE_CFN_LLFLOOR:
12985 CASE_CFN_LLRINT:
12986 CASE_CFN_LLROUND:
12987 CASE_CFN_LRINT:
12988 CASE_CFN_LROUND:
12989 CASE_CFN_MODF:
12990 CASE_CFN_NEARBYINT:
12991 CASE_CFN_RINT:
12992 CASE_CFN_ROUND:
12993 CASE_CFN_SCALB:
12994 CASE_CFN_SCALBLN:
12995 CASE_CFN_SCALBN:
12996 CASE_CFN_SIGNBIT:
12997 CASE_CFN_SIGNIFICAND:
12998 CASE_CFN_SINH:
12999 CASE_CFN_TANH:
13000 CASE_CFN_TRUNC:
13001 /* True if the 1st argument is nonnegative. */
13004 CASE_CFN_FMAX:
13005 /* True if the 1st OR 2nd arguments are nonnegative. */
13008 CASE_CFN_FMIN:
13009 /* True if the 1st AND 2nd arguments are nonnegative. */
13012 CASE_CFN_COPYSIGN:
13013 /* True if the 2nd argument is nonnegative. */
13016 CASE_CFN_POWI:
13017 /* True if the 1st argument is nonnegative or the second
13018 argument is an even integer. */
13024 CASE_CFN_POW:
13025 /* True if the 1st argument is nonnegative or the second
13026 argument is an even integer valued real. */
13028 {
13029 REAL_VALUE_TYPE c;
13030 HOST_WIDE_INT n;
13035 {
13036 REAL_VALUE_TYPE cint;
13040 }
13041 }
13046 }
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 static bool
13057 {
13063 {
13065 {
13069 /* If the initializer is non-void, then it's a normal expression
13070 that will be assigned to the slot. */
13074 /* Otherwise, the initializer sets the slot in some way. One common
13075 way is an assignment statement at the end of the initializer. */
13077 {
13085 else
13087 }
13093 }
13096 {
13102 arg0,
13103 arg1,
13105 }
13118 }
13119 }
13121 #undef RECURSE
13122 #undef tree_expr_nonnegative_warnv_p
13124 /* Return true if T is known to be non-negative. If the return
13125 value is based on the assumption that signed overflow is undefined,
13126 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13127 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13129 bool
13131 {
13138 {
13160 }
13163 {
13189 }
13190 }
13192 /* Return true if `t' is known to be non-negative. Handle warnings
13193 about undefined signed overflow. */
13195 bool
13197 {
13204 "determining that expression is always "
13206 WARN_STRICT_OVERFLOW_MISC);
13208 }
13211 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13212 For floating point we further ensure that T is not denormal.
13213 Similar logic is present in nonzero_address in rtlanal.h.
13215 If the return value is based on the assumption that signed overflow
13216 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13217 change *STRICT_OVERFLOW_P. */
13219 bool
13222 {
13224 {
13227 strict_overflow_p);
13230 {
13236 strict_overflow_p));
13237 }
13242 strict_overflow_p);
13246 }
13249 }
13251 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13252 For floating point we further ensure that T is not denormal.
13253 Similar logic is present in nonzero_address in rtlanal.h.
13255 If the return value is based on the assumption that signed overflow
13256 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13257 change *STRICT_OVERFLOW_P. */
13259 bool
13261 tree type,
13262 tree op0,
13264 {
13267 {
13271 {
13272 /* With the presence of negative values it is hard
13273 to say something. */
13280 /* One of operands must be positive and the other non-negative. */
13281 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13282 overflows, on a twos-complement machine the sum of two
13283 nonnegative numbers can never be zero. */
13285 strict_overflow_p)
13287 strict_overflow_p));
13288 }
13293 {
13295 strict_overflow_p)
13297 strict_overflow_p))
13298 {
13301 }
13302 }
13311 {
13314 }
13321 {
13325 /* When both operands are nonzero, then MAX must be too. */
13327 strict_overflow_p))
13330 /* MAX where operand 0 is positive is positive. */
13332 strict_overflow_p);
13333 }
13334 /* MAX where operand 1 is positive is positive. */
13339 {
13343 }
13348 strict_overflow_p)
13350 strict_overflow_p));
13354 }
13357 }
13359 /* Return true when T is an address and is known to be nonzero.
13360 For floating point we further ensure that T is not denormal.
13361 Similar logic is present in nonzero_address in rtlanal.h.
13363 If the return value is based on the assumption that signed overflow
13364 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13365 change *STRICT_OVERFLOW_P. */
13367 bool
13369 {
13372 {
13377 {
13389 /* For objects in symbol table check if we know they are non-zero.
13390 Don't do anything for variables and functions before symtab is built;
13391 it is quite possible that they will be declared weak later. */
13396 /* Function local objects are never NULL. */
13403 /* Constants are never weak. */
13408 }
13416 {
13420 }
13425 }
13427 }
13429 #define integer_valued_real_p(X) \
13432 #define RECURSE(X) \
13433 ((integer_valued_real_p) (X, depth + 1))
13435 /* Return true if the floating point result of (CODE OP0) has an
13436 integer value. We also allow +Inf, -Inf and NaN to be considered
13437 integer values. Return false for signaling NaN.
13439 DEPTH is the current nesting depth of the query. */
13441 bool
13443 {
13445 {
13452 CASE_CONVERT:
13453 {
13460 }
13464 }
13466 }
13468 /* Return true if the floating point result of (CODE OP0 OP1) has an
13469 integer value. We also allow +Inf, -Inf and NaN to be considered
13470 integer values. Return false for signaling NaN.
13472 DEPTH is the current nesting depth of the query. */
13474 bool
13476 {
13478 {
13488 }
13490 }
13492 /* Return true if the floating point result of calling FNDECL with arguments
13493 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13494 considered integer values. Return false for signaling NaN. If FNDECL
13495 takes fewer than 2 arguments, the remaining ARGn are null.
13497 DEPTH is the current nesting depth of the query. */
13499 bool
13501 {
13503 {
13504 CASE_CFN_CEIL:
13505 CASE_CFN_FLOOR:
13506 CASE_CFN_NEARBYINT:
13507 CASE_CFN_RINT:
13508 CASE_CFN_ROUND:
13509 CASE_CFN_TRUNC:
13512 CASE_CFN_FMIN:
13513 CASE_CFN_FMAX:
13518 }
13520 }
13522 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13523 has an integer value. We also allow +Inf, -Inf and NaN to be
13524 considered integer values. Return false for signaling NaN.
13526 DEPTH is the current nesting depth of the query. */
13528 bool
13530 {
13532 {
13540 /* Limit the depth of recursion to avoid quadratic behavior.
13541 This is expected to catch almost all occurrences in practice.
13542 If this code misses important cases that unbounded recursion
13543 would not, passes that need this information could be revised
13544 to provide it through dataflow propagation. */
13548 depth));
13552 }
13554 }
13556 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13557 has an integer value. We also allow +Inf, -Inf and NaN to be
13558 considered integer values. Return false for signaling NaN.
13560 DEPTH is the current nesting depth of the query. */
13562 static bool
13564 {
13566 {
13577 }
13579 }
13581 #undef RECURSE
13582 #undef integer_valued_real_p
13584 /* Return true if the floating point expression T has an integer value.
13585 We also allow +Inf, -Inf and NaN to be considered integer values.
13586 Return false for signaling NaN.
13588 DEPTH is the current nesting depth of the query. */
13590 bool
13592 {
13598 {
13614 }
13617 {
13623 {
13632 }
13636 }
13637 }
13639 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13640 attempt to fold the expression to a constant without modifying TYPE,
13641 OP0 or OP1.
13643 If the expression could be simplified to a constant, then return
13644 the constant. If the expression would not be simplified to a
13645 constant, then return NULL_TREE. */
13647 tree
13649 {
13652 }
13654 /* Given the components of a unary expression CODE, TYPE and OP0,
13655 attempt to fold the expression to a constant without modifying
13656 TYPE or OP0.
13658 If the expression could be simplified to a constant, then return
13659 the constant. If the expression would not be simplified to a
13660 constant, then return NULL_TREE. */
13662 tree
13664 {
13667 }
13669 /* If EXP represents referencing an element in a constant string
13670 (either via pointer arithmetic or array indexing), return the
13671 tree representing the value accessed, otherwise return NULL. */
13673 tree
13675 {
13679 {
13681 tree index;
13682 tree string;
13687 else
13688 {
13692 /* Optimize the special-case of a zero lower bound.
13694 We convert the low_bound to sizetype to avoid some problems
13695 with constant folding. (E.g. suppose the lower bound is 1,
13696 and its mode is QI. Without the conversion,l (ARRAY
13697 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13698 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13704 }
13717 }
13719 }
13721 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13722 an integer constant, real, or fixed-point constant.
13724 TYPE is the type of the result. */
13726 static tree
13728 {
13732 {
13734 {
13741 }
13748 {
13749 FIXED_VALUE_TYPE f;
13754 /* Propagate overflow flags. */
13758 }
13762 }
13765 }
13767 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13768 an integer constant or real constant.
13770 TYPE is the type of the result. */
13772 tree
13774 {
13778 {
13780 {
13781 /* If the value is unsigned or non-negative, then the absolute value
13782 is the same as the ordinary value. */
13786 /* If the value is negative, then the absolute value is
13787 its negation. */
13788 else
13789 {
13794 }
13795 }
13801 else
13807 }
13810 }
13812 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13813 constant. TYPE is the type of the result. */
13815 static tree
13817 {
13821 }
13823 /* Given CODE, a relational operator, the target type, TYPE and two
13824 constant operands OP0 and OP1, return the result of the
13825 relational operation. If the result is not a compile time
13826 constant, then return NULL_TREE. */
13828 static tree
13830 {
13833 /* From here on, the only cases we handle are when the result is
13834 known to be a constant. */
13837 {
13841 /* Handle the cases where either operand is a NaN. */
13843 {
13845 {
13873 }
13876 }
13879 }
13882 {
13886 }
13888 /* Handle equality/inequality of complex constants. */
13890 {
13901 else
13903 }
13906 {
13908 {
13909 /* Have vector comparison with scalar boolean result. */
13913 {
13921 }
13923 }
13930 {
13942 }
13945 }
13947 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13949 To compute GT, swap the arguments and do LT.
13950 To compute GE, do LT and invert the result.
13951 To compute LE, swap the arguments, do LT and invert the result.
13952 To compute NE, do EQ and invert the result.
13954 Therefore, the code below must handle only EQ and LT. */
13957 {
13960 }
13962 /* Note that it is safe to invert for real values here because we
13963 have already handled the one case that it matters. */
13967 {
13970 }
13972 /* Compute a result for LT or EQ if args permit;
13973 Otherwise return T. */
13975 {
13978 else
13980 }
13981 else
13987 }
13989 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13990 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13991 itself. */
13993 tree
13995 {
13996 /* If the expression does not have side effects then we don't have to wrap
13997 it with a cleanup point expression. */
14001 /* If the expression is a return, check to see if the expression inside the
14002 return has no side effects or the right hand side of the modify expression
14003 inside the return. If either don't have side effects set we don't need to
14004 wrap the expression in a cleanup point expression. Note we don't check the
14005 left hand side of the modify because it should always be a return decl. */
14007 {
14014 }
14017 }
14019 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14020 of an indirection through OP0, or NULL_TREE if no simplification is
14021 possible. */
14023 tree
14025 {
14027 tree subtype;
14035 {
14038 /* *&CONST_DECL -> to the value of the const decl. */
14041 /* *&p => p; make sure to handle *&"str"[cst] here. */
14043 {
14047 else
14049 }
14050 /* *(foo *)&fooarray => fooarray[0] */
14053 && (!in_gimple_form
14055 {
14065 }
14066 /* *(foo *)&complexfoo => __real__ complexfoo */
14070 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14073 {
14077 }
14078 }
14082 {
14088 {
14089 tree op00type;
14093 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14096 {
14098 unsigned HOST_WIDE_INT max_offset
14103 {
14110 }
14111 }
14112 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14115 {
14119 }
14120 /* ((foo *)&fooarray)[1] => fooarray[1] */
14123 {
14133 }
14134 }
14135 }
14137 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14140 && (!in_gimple_form
14142 {
14143 tree type_domain;
14153 NULL_TREE);
14154 }
14157 }
14159 /* Builds an expression for an indirection through T, simplifying some
14160 cases. */
14162 tree
14164 {
14172 }
14174 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14176 tree
14178 {
14183 else
14185 }
14187 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14188 whose result is ignored. The type of the returned tree need not be
14189 the same as the original expression. */
14191 tree
14193 {
14199 {
14210 else
14216 {
14232 }
14237 }
14238 }
14240 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14242 tree
14244 {
14250 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14251 have to do anything. Only do this when we are not given a const,
14252 because in that case, this check is more expensive than just
14253 doing it. */
14255 {
14260 }
14262 /* If divisor is a power of two, simplify this to bit manipulation. */
14264 {
14266 {
14280 }
14281 else
14282 {
14283 tree t;
14289 }
14290 }
14291 else
14292 {
14297 }
14300 }
14302 /* Likewise, but round down. */
14304 tree
14306 {
14313 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14314 have to do anything. Only do this when we are not given a const,
14315 because in that case, this check is more expensive than just
14316 doing it. */
14318 {
14323 }
14325 /* If divisor is a power of two, simplify this to bit manipulation. */
14327 {
14328 tree t;
14332 }
14333 else
14334 {
14339 }
14342 }
14344 /* Returns the pointer to the base of the object addressed by EXP and
14345 extracts the information about the offset of the access, storing it
14346 to PBITPOS and POFFSET. */
14348 static tree
14351 {
14352 tree core;
14353 machine_mode mode;
14355 HOST_WIDE_INT bitsize;
14359 {
14364 }
14365 else
14366 {
14370 }
14373 }
14375 /* Returns true if addresses of E1 and E2 differ by a constant, false
14376 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14378 bool
14380 {
14394 {
14404 }
14406 {
14407 /* If only one of the offsets is non-constant, the difference cannot
14408 be a constant. */
14410 }
14411 else
14416 }
14418 /* Return OFF converted to a pointer offset type suitable as offset for
14419 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14420 tree
14422 {
14424 }
14426 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14427 tree
14429 {
14432 }
14434 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14435 tree
14437 {
14440 }
14442 /* Return a char pointer for a C string if it is a string constant
14443 or sum of string constant and integer constant. */
14447 {
14448 tree offset_node;
14461 }
14463 #if CHECKING_P
14467 /* Helper functions for writing tests of folding trees. */
14469 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14471 static void
14473 tree constant)
14474 {
14476 }
14478 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14479 wrapping WRAPPED_EXPR. */
14481 static void
14483 tree wrapped_expr)
14484 {
14489 }
14491 /* Verify that various arithmetic binary operations are folded
14492 correctly. */
14494 static void
14496 {
14502 /* Addition. */
14503 /* 1 <-- (0 + 1) */
14505 one);
14507 one);
14509 /* (nonlvalue)x <-- (x + 0) */
14511 x);
14513 /* Subtraction. */
14514 /* 0 <-- (x - x) */
14516 zero);
14518 x);
14520 /* Multiplication. */
14521 /* 0 <-- (x * 0) */
14523 zero);
14525 /* (nonlvalue)x <-- (x * 1) */
14527 x);
14528 }
14530 /* Verify that various binary operations on vectors are folded
14531 correctly. */
14533 static void
14535 {
14541 /* Verify equality tests that return a scalar boolean result. */
14547 }
14549 /* Run all of the selftests within this file. */
14551 void
14553 {
14556 }