| blob | b4c117c84948f6994c2ac0354b76ce8d393eb2b4 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2017 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. */
83 /* Nonzero if we are folding constants inside an initializer; zero
84 otherwise. */
87 /* The following constants represent a bit based encoding of GCC's
88 comparison operators. This encoding simplifies transformations
89 on relational comparison operators, such as AND and OR. */
107 };
145 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
146 Otherwise, return LOC. */
148 static location_t
150 {
153 }
155 /* Similar to protected_set_expr_location, but never modify x in place,
156 if location can and needs to be set, unshare it. */
160 {
166 {
169 }
171 }
172 \f
173 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
174 division and returns the quotient. Otherwise returns
175 NULL_TREE. */
177 tree
179 {
180 widest_int quo;
187 }
188 \f
189 /* This is nonzero if we should defer warnings about undefined
190 overflow. This facility exists because these warnings are a
191 special case. The code to estimate loop iterations does not want
192 to issue any warnings, since it works with expressions which do not
193 occur in user code. Various bits of cleanup code call fold(), but
194 only use the result if it has certain characteristics (e.g., is a
195 constant); that code only wants to issue a warning if the result is
196 used. */
200 /* If a warning about undefined overflow is deferred, this is the
201 warning. Note that this may cause us to turn two warnings into
202 one, but that is fine since it is sufficient to only give one
203 warning per expression. */
207 /* If a warning about undefined overflow is deferred, this is the
208 level at which the warning should be emitted. */
212 /* Start deferring overflow warnings. We could use a stack here to
213 permit nested calls, but at present it is not necessary. */
215 void
217 {
219 }
221 /* Stop deferring overflow warnings. If there is a pending warning,
222 and ISSUE is true, then issue the warning if appropriate. STMT is
223 the statement with which the warning should be associated (used for
224 location information); STMT may be NULL. CODE is the level of the
225 warning--a warn_strict_overflow_code value. This function will use
226 the smaller of CODE and the deferred code when deciding whether to
227 issue the warning. CODE may be zero to mean to always use the
228 deferred code. */
230 void
232 {
234 location_t locus;
239 {
245 }
256 /* Use the smallest code level when deciding to issue the
257 warning. */
266 else
269 }
271 /* Stop deferring overflow warnings, ignoring any deferred
272 warnings. */
274 void
276 {
278 }
280 /* Whether we are deferring overflow warnings. */
282 bool
284 {
286 }
288 /* This is called when we fold something based on the fact that signed
289 overflow is undefined. */
291 void
293 {
295 {
298 {
301 }
302 }
305 }
306 \f
307 /* Return true if the built-in mathematical function specified by CODE
308 is odd, i.e. -f(x) == f(-x). */
310 bool
312 {
314 {
315 CASE_CFN_ASIN:
316 CASE_CFN_ASINH:
317 CASE_CFN_ATAN:
318 CASE_CFN_ATANH:
319 CASE_CFN_CASIN:
320 CASE_CFN_CASINH:
321 CASE_CFN_CATAN:
322 CASE_CFN_CATANH:
323 CASE_CFN_CBRT:
324 CASE_CFN_CPROJ:
325 CASE_CFN_CSIN:
326 CASE_CFN_CSINH:
327 CASE_CFN_CTAN:
328 CASE_CFN_CTANH:
329 CASE_CFN_ERF:
330 CASE_CFN_LLROUND:
331 CASE_CFN_LROUND:
332 CASE_CFN_ROUND:
333 CASE_CFN_SIN:
334 CASE_CFN_SINH:
335 CASE_CFN_TAN:
336 CASE_CFN_TANH:
337 CASE_CFN_TRUNC:
340 CASE_CFN_LLRINT:
341 CASE_CFN_LRINT:
342 CASE_CFN_NEARBYINT:
343 CASE_CFN_RINT:
348 }
350 }
352 /* Check whether we may negate an integer constant T without causing
353 overflow. */
355 bool
357 {
358 tree type;
367 }
369 /* Determine whether an expression T can be cheaply negated using
370 the function negate_expr without introducing undefined overflow. */
372 static bool
374 {
375 tree type;
384 {
389 /* Check that -CST will not overflow type. */
402 /* We want to canonicalize to positive real constants. Pretend
403 that only negative ones can be easily negated. */
411 {
422 }
437 /* -(A + B) -> (-B) - A. */
440 /* -(A + B) -> (-A) - B. */
444 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
453 /* INT_MIN/n * n doesn't overflow while negating one operand it does
454 if n is a (negative) power of two. */
463 /* Fall through. */
478 /* In general we can't negate B in A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. */
489 /* Negate -((double)float) as (double)(-float). */
491 {
495 }
499 /* Negate -f(x) as f(-x). */
505 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
507 {
511 }
516 }
518 }
520 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
521 simplification is possible.
522 If negate_expr_p would return true for T, NULL_TREE will never be
523 returned. */
525 static tree
527 {
529 tree tem;
532 {
533 /* Convert - (~A) to A + 1. */
559 {
564 }
568 {
573 {
577 }
580 }
603 {
604 /* -(A + B) -> (-B) - A. */
606 {
610 }
612 /* -(A + B) -> (-A) - B. */
614 {
618 }
619 }
623 /* - (A - B) -> B - A */
634 /* Fall through. */
638 {
647 }
659 /* In general we can't negate B in A / B, because if A is INT_MIN and
660 B is 1, we may turn this into INT_MIN / -1 which is undefined
661 and actually traps on some architectures. */
673 /* Convert -((double)float) into (double)(-float). */
675 {
679 }
683 /* Negate -f(x) as f(-x). */
686 {
692 }
696 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
698 {
701 {
708 }
709 }
714 }
717 }
719 /* A wrapper for fold_negate_expr_1. */
721 static tree
723 {
730 }
732 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
733 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
734 return NULL_TREE. */
736 static tree
738 {
740 location_t loc;
753 }
754 \f
755 /* Split a tree IN into a constant, literal and variable parts that could be
756 combined with CODE to make IN. "constant" means an expression with
757 TREE_CONSTANT but that isn't an actual constant. CODE must be a
758 commutative arithmetic operation. Store the constant part into *CONP,
759 the literal in *LITP and return the variable part. If a part isn't
760 present, set it to null. If the tree does not decompose in this way,
761 return the entire tree as the variable part and the other parts as null.
763 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
764 case, we negate an operand that was subtracted. Except if it is a
765 literal for which we use *MINUS_LITP instead.
767 If NEGATE_P is true, we are negating all of IN, again except a literal
768 for which we use *MINUS_LITP instead. If a variable part is of pointer
769 type, it is negated after converting to TYPE. This prevents us from
770 generating illegal MINUS pointer expression. LOC is the location of
771 the converted variable part.
773 If IN is itself a literal or constant, return it as appropriate.
775 Note that we do not guarantee that any of the three values will be the
776 same type as IN, but they will have the same signedness and mode. */
778 static tree
781 {
788 /* Strip any conversions that don't change the machine mode or signedness. */
797 /* We can associate addition and subtraction together (even
798 though the C standard doesn't say so) for integers because
799 the value is not affected. For reals, the value might be
800 affected, so we can't. */
803 {
809 /* First see if either of the operands is a literal, then a constant. */
822 /* If we haven't dealt with either operand, this is not a case we can
823 decompose. Otherwise, VAR is either of the ones remaining, if any. */
828 else
831 /* Now do any needed negations. */
835 {
836 /* Convert to TYPE before negating. */
839 }
841 {
842 /* Convert to TYPE before negating. */
845 }
846 }
851 {
852 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
853 when IN is constant. */
856 }
857 else
861 {
867 {
868 /* Convert to TYPE before negating. */
871 }
873 {
874 /* Convert to TYPE before negating. */
877 }
878 }
881 }
883 /* Re-associate trees split by the above function. T1 and T2 are
884 either expressions to associate or null. Return the new
885 expression, if any. LOC is the location of the new expression. If
886 we build an operation, do it in TYPE and with CODE. */
888 static tree
890 {
896 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
897 try to fold this since we will have infinite recursion. But do
898 deal with any NEGATE_EXPRs. */
901 {
903 {
916 }
918 {
921 }
925 }
929 }
930 \f
931 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
932 for use in int_const_binop, size_binop and size_diffop. */
934 static bool
936 {
943 {
952 }
957 }
960 /* Combine two integer constants ARG1 and ARG2 under operation CODE
961 to produce a new constant. Return NULL_TREE if we don't know how
962 to evaluate CODE at compile-time. */
964 static tree
967 {
968 wide_int res;
969 tree t;
977 {
993 {
997 else
999 }
1002 /* It's unclear from the C standard whether shifts can overflow.
1003 The following code ignores overflow; perhaps a C standard
1004 interpretation ruling is needed. */
1006 else
1013 {
1017 else
1019 }
1023 else
1102 }
1110 }
1112 tree
1114 {
1116 }
1118 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1119 constant. We assume ARG1 and ARG2 have the same data type, or at least
1120 are the same kind of constant and the same machine mode. Return zero if
1121 combining the constants is not allowed in the current operating mode. */
1123 static tree
1125 {
1126 /* Sanity check for the recursive cases. */
1134 {
1140 }
1143 {
1144 machine_mode mode;
1145 REAL_VALUE_TYPE d1;
1146 REAL_VALUE_TYPE d2;
1147 REAL_VALUE_TYPE value;
1148 REAL_VALUE_TYPE result;
1152 /* The following codes are handled by real_arithmetic. */
1154 {
1165 }
1173 /* Don't perform operation if we honor signaling NaNs and
1174 either operand is a signaling NaN. */
1180 /* Don't perform operation if it would raise a division
1181 by zero exception. */
1187 /* If either operand is a NaN, just return it. Otherwise, set up
1188 for floating-point trap; we return an overflow. */
1190 {
1191 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1192 is off. */
1196 }
1198 {
1199 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1200 is off. */
1204 }
1209 /* Don't constant fold this floating point operation if
1210 the result has overflowed and flag_trapping_math. */
1218 /* Don't constant fold this floating point operation if the
1219 result may dependent upon the run-time rounding mode and
1220 flag_rounding_math is set, or if GCC's software emulation
1221 is unable to accurately represent the result. */
1231 }
1234 {
1235 FIXED_VALUE_TYPE f1;
1236 FIXED_VALUE_TYPE f2;
1237 FIXED_VALUE_TYPE result;
1242 /* The following codes are handled by fixed_arithmetic. */
1244 {
1256 {
1263 }
1268 }
1275 /* Propagate overflow flags. */
1279 }
1282 {
1291 {
1302 mpc_mul);
1316 mpc_div);
1317 /* Fallthru. */
1323 {
1324 /* Keep this algorithm in sync with
1325 tree-complex.c:expand_complex_div_straight().
1327 Expand complex division to scalars, straightforward algorithm.
1328 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1329 t = br*br + bi*bi
1330 */
1331 tree magsquared
1335 tree t1
1339 tree t2
1346 }
1347 else
1348 {
1349 /* Keep this algorithm in sync with
1350 tree-complex.c:expand_complex_div_wide().
1352 Expand complex division to scalars, modified algorithm to minimize
1353 overflow with wide input ranges. */
1359 {
1360 /* In the TRUE branch, we compute
1361 ratio = br/bi;
1362 div = (br * ratio) + bi;
1363 tr = (ar * ratio) + ai;
1364 ti = (ai * ratio) - ar;
1365 tr = tr / div;
1366 ti = ti / div; */
1377 }
1378 else
1379 {
1380 /* In the FALSE branch, we compute
1381 ratio = d/c;
1382 divisor = (d * ratio) + c;
1383 tr = (b * ratio) + a;
1384 ti = b - (a * ratio);
1385 tr = tr / div;
1386 ti = ti / div; */
1398 }
1399 }
1404 }
1408 }
1412 {
1418 {
1424 /* It is possible that const_binop cannot handle the given
1425 code and return NULL_TREE */
1428 }
1431 }
1433 /* Shifts allow a scalar offset for a vector. */
1436 {
1442 {
1447 /* It is possible that const_binop cannot handle the given
1448 code and return NULL_TREE. */
1451 }
1454 }
1456 }
1458 /* Overload that adds a TYPE parameter to be able to dispatch
1459 to fold_relational_const. */
1461 tree
1463 {
1467 /* ??? Until we make the const_binop worker take the type of the
1468 result as argument put those cases that need it here. */
1470 {
1481 {
1497 {
1503 }
1506 }
1512 {
1537 {
1550 }
1553 }
1556 }
1561 /* Make sure type and arg0 have the same saturating flag. */
1566 }
1568 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1569 Return zero if computing the constants is not possible. */
1571 tree
1573 {
1574 /* Don't perform the operation, other than NEGATE and ABS, if
1575 flag_signaling_nans is on and the operand is a signaling NaN. */
1584 {
1585 CASE_CONVERT:
1592 /* If the source address is 0, and the source address space
1593 cannot have a valid object at 0, fold to dest type null. */
1604 {
1605 /* Can't call fold_negate_const directly here as that doesn't
1606 handle all cases and we might not be able to negate some
1607 constants. */
1612 }
1621 {
1625 }
1631 /* Perform BIT_NOT_EXPR on each element individually. */
1633 {
1635 tree elem;
1640 {
1646 }
1649 }
1671 {
1690 else
1694 {
1698 }
1701 }
1706 {
1720 {
1725 }
1728 {
1732 }
1735 }
1739 }
1742 }
1744 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1745 indicates which particular sizetype to create. */
1747 tree
1749 {
1751 }
1752 \f
1753 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1754 is a tree code. The type of the result is taken from the operands.
1755 Both must be equivalent integer types, ala int_binop_types_match_p.
1756 If the operands are constant, so is the result. */
1758 tree
1760 {
1769 /* Handle the special case of two integer constants faster. */
1771 {
1772 /* And some specific cases even faster than that. */
1774 {
1779 }
1781 {
1784 }
1786 {
1789 }
1791 /* Handle general case of two integer constants. For sizetype
1792 constant calculations we always want to know about overflow,
1793 even in the unsigned case. */
1795 }
1798 }
1800 /* Given two values, either both of sizetype or both of bitsizetype,
1801 compute the difference between the two values. Return the value
1802 in signed type corresponding to the type of the operands. */
1804 tree
1806 {
1808 tree ctype;
1813 /* If the type is already signed, just do the simple thing. */
1821 else
1824 /* If either operand is not a constant, do the conversions to the signed
1825 type and subtract. The hardware will do the right thing with any
1826 overflow in the subtraction. */
1832 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1833 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1834 overflow) and negate (which can't either). Special-case a result
1835 of zero while we're here. */
1841 else
1845 MINUS_EXPR,
1847 }
1848 \f
1849 /* A subroutine of fold_convert_const handling conversions of an
1850 INTEGER_CST to another integer type. */
1852 static tree
1854 {
1855 /* Given an integer constant, make new constant with new type,
1856 appropriately sign-extended or truncated. Use widest_int
1857 so that any extension is done according ARG1's type. */
1861 }
1863 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1864 to an integer type. */
1866 static tree
1868 {
1870 tree t;
1872 /* The following code implements the floating point to integer
1873 conversion rules required by the Java Language Specification,
1874 that IEEE NaNs are mapped to zero and values that overflow
1875 the target precision saturate, i.e. values greater than
1876 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1877 are mapped to INT_MIN. These semantics are allowed by the
1878 C and C++ standards that simply state that the behavior of
1879 FP-to-integer conversion is unspecified upon overflow. */
1881 wide_int val;
1882 REAL_VALUE_TYPE r;
1886 {
1893 }
1895 /* If R is NaN, return zero and show we have an overflow. */
1897 {
1900 }
1902 /* See if R is less than the lower bound or greater than the
1903 upper bound. */
1906 {
1910 {
1913 }
1914 }
1917 {
1920 {
1923 {
1926 }
1927 }
1928 }
1935 }
1937 /* A subroutine of fold_convert_const handling conversions of a
1938 FIXED_CST to an integer type. */
1940 static tree
1942 {
1943 tree t;
1947 /* Right shift FIXED_CST to temp by fbit. */
1951 {
1953 HOST_BITS_PER_DOUBLE_INT,
1956 /* Left shift temp to temp_trunc by fbit. */
1958 HOST_BITS_PER_DOUBLE_INT,
1960 }
1961 else
1962 {
1965 }
1967 /* If FIXED_CST is negative, we need to round the value toward 0.
1968 By checking if the fractional bits are not zero to add 1 to temp. */
1974 /* Given a fixed-point constant, make new constant with new type,
1975 appropriately sign-extended or truncated. */
1983 }
1985 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1986 to another floating point type. */
1988 static tree
1990 {
1991 REAL_VALUE_TYPE value;
1992 tree t;
1994 /* Don't perform the operation if flag_signaling_nans is on
1995 and the operand is a signaling NaN. */
2003 /* If converting an infinity or NAN to a representation that doesn't
2004 have one, set the overflow bit so that we can produce some kind of
2005 error message at the appropriate point if necessary. It's not the
2006 most user-friendly message, but it's better than nothing. */
2013 /* Regular overflow, conversion produced an infinity in a mode that
2014 can't represent them. */
2019 else
2022 }
2024 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2025 to a floating point type. */
2027 static tree
2029 {
2030 REAL_VALUE_TYPE value;
2031 tree t;
2038 }
2040 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2041 to another fixed-point type. */
2043 static tree
2045 {
2046 FIXED_VALUE_TYPE value;
2047 tree t;
2054 /* Propagate overflow flags. */
2058 }
2060 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2061 to a fixed-point type. */
2063 static tree
2065 {
2066 FIXED_VALUE_TYPE value;
2067 tree t;
2069 double_int di;
2076 else
2084 /* Propagate overflow flags. */
2088 }
2090 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2091 to a fixed-point type. */
2093 static tree
2095 {
2096 FIXED_VALUE_TYPE value;
2097 tree t;
2105 /* Propagate overflow flags. */
2109 }
2111 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2112 type TYPE. If no simplification can be done return NULL_TREE. */
2114 static tree
2116 {
2122 {
2129 }
2131 {
2138 }
2140 {
2147 }
2149 {
2152 {
2157 {
2163 }
2165 }
2166 }
2168 }
2170 /* Construct a vector of zero elements of vector type TYPE. */
2172 static tree
2174 {
2175 tree t;
2179 }
2181 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2183 bool
2185 {
2200 {
2215 }
2216 }
2218 /* Convert expression ARG to type TYPE. Used by the middle-end for
2219 simple conversions in preference to calling the front-end's convert. */
2221 tree
2223 {
2225 tree tem;
2236 {
2239 /* Handle conversions between pointers to different address spaces. */
2244 /* fall through */
2249 {
2253 }
2267 {
2271 }
2273 {
2277 }
2279 {
2283 }
2286 {
2304 }
2309 {
2313 }
2316 {
2330 }
2334 {
2343 integer_zero_node));
2345 {
2349 {
2355 }
2363 }
2367 }
2385 }
2386 fold_convert_exit:
2389 }
2390 \f
2391 /* Return false if expr can be assumed not to be an lvalue, true
2392 otherwise. */
2394 static bool
2396 {
2397 /* We only need to wrap lvalue tree codes. */
2399 {
2430 /* Assume the worst for front-end tree codes. */
2434 }
2437 }
2439 /* Return an expr equal to X but certainly not valid as an lvalue. */
2441 tree
2443 {
2444 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2445 us. */
2452 }
2454 /* When pedantic, return an expr equal to X but certainly not valid as a
2455 pedantic lvalue. Otherwise, return X. */
2457 static tree
2459 {
2461 }
2462 \f
2463 /* Given a tree comparison code, return the code that is the logical inverse.
2464 It is generally not safe to do this for floating-point comparisons, except
2465 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2466 ERROR_MARK in this case. */
2468 enum tree_code
2470 {
2476 {
2507 }
2508 }
2510 /* Similar, but return the comparison that results if the operands are
2511 swapped. This is safe for floating-point. */
2513 enum tree_code
2515 {
2517 {
2543 }
2544 }
2547 /* Convert a comparison tree code from an enum tree_code representation
2548 into a compcode bit-based encoding. This function is the inverse of
2549 compcode_to_comparison. */
2551 static enum comparison_code
2553 {
2555 {
2586 }
2587 }
2589 /* Convert a compcode bit-based encoding of a comparison operator back
2590 to GCC's enum tree_code representation. This function is the
2591 inverse of comparison_to_compcode. */
2593 static enum tree_code
2595 {
2597 {
2628 }
2629 }
2631 /* Return a tree for the comparison which is the combination of
2632 doing the AND or OR (depending on CODE) of the two operations LCODE
2633 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2634 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2635 if this makes the transformation invalid. */
2637 tree
2642 {
2649 {
2660 }
2663 {
2664 /* Eliminate unordered comparisons, as well as LTGT and ORD
2665 which are not used unless the mode has NaNs. */
2671 }
2673 {
2674 /* Check that the original operation and the optimized ones will trap
2675 under the same condition. */
2686 /* In a short-circuited boolean expression the LHS might be
2687 such that the RHS, if evaluated, will never trap. For
2688 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2689 if neither x nor y is NaN. (This is a mixed blessing: for
2690 example, the expression above will never trap, hence
2691 optimizing it to x < y would be invalid). */
2696 /* If the comparison was short-circuited, and only the RHS
2697 trapped, we may now generate a spurious trap. */
2702 /* If we changed the conditions that cause a trap, we lose. */
2705 }
2711 else
2712 {
2717 }
2718 }
2719 \f
2720 /* Return nonzero if two operands (typically of the same tree node)
2721 are necessarily equal. FLAGS modifies behavior as follows:
2723 If OEP_ONLY_CONST is set, only return nonzero for constants.
2724 This function tests whether the operands are indistinguishable;
2725 it does not test whether they are equal using C's == operation.
2726 The distinction is important for IEEE floating point, because
2727 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2728 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2730 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2731 even though it may hold multiple values during a function.
2732 This is because a GCC tree node guarantees that nothing else is
2733 executed between the evaluation of its "operands" (which may often
2734 be evaluated in arbitrary order). Hence if the operands themselves
2735 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2736 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2737 unset means assuming isochronic (or instantaneous) tree equivalence.
2738 Unless comparing arbitrary expression trees, such as from different
2739 statements, this flag can usually be left unset.
2741 If OEP_PURE_SAME is set, then pure functions with identical arguments
2742 are considered the same. It is used when the caller has other ways
2743 to ensure that global memory is unchanged in between.
2745 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2746 not values of expressions.
2748 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2749 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2751 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2752 any operand with side effect. This is unnecesarily conservative in the
2753 case we know that arg0 and arg1 are in disjoint code paths (such as in
2754 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2755 addresses with TREE_CONSTANT flag set so we know that &var == &var
2756 even if var is volatile. */
2758 int
2760 {
2761 /* When checking, verify at the outermost operand_equal_p call that
2762 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2763 hash value. */
2765 {
2767 {
2769 {
2776 }
2778 }
2779 else
2781 }
2783 /* If either is ERROR_MARK, they aren't equal. */
2789 /* Similar, if either does not have a type (like a released SSA name),
2790 they aren't equal. */
2794 /* We cannot consider pointers to different address space equal. */
2801 /* Check equality of integer constants before bailing out due to
2802 precision differences. */
2804 {
2805 /* Address of INTEGER_CST is not defined; check that we did not forget
2806 to drop the OEP_ADDRESS_OF flags. */
2809 }
2812 {
2813 /* If both types don't have the same signedness, then we can't consider
2814 them equal. We must check this before the STRIP_NOPS calls
2815 because they may change the signedness of the arguments. As pointers
2816 strictly don't have a signedness, require either two pointers or
2817 two non-pointers as well. */
2823 /* If both types don't have the same precision, then it is not safe
2824 to strip NOPs. */
2831 }
2832 #if 0
2833 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2834 sanity check once the issue is solved. */
2835 else
2836 /* Addresses of conversions and SSA_NAMEs (and many other things)
2837 are not defined. Check that we did not forget to drop the
2838 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2841 #endif
2843 /* In case both args are comparisons but with different comparison
2844 code, try to swap the comparison operands of one arg to produce
2845 a match and compare that variant. */
2849 {
2857 }
2860 {
2861 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2863 ;
2865 {
2866 /* If we are interested in comparing addresses ignore
2867 MEM_REF wrappings of the base that can appear just for
2868 TBAA reasons. */
2882 }
2883 else
2885 }
2887 /* When not checking adddresses, this is needed for conversions and for
2888 COMPONENT_REF. Might as well play it safe and always test this. */
2895 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2896 We don't care about side effects in that case because the SAVE_EXPR
2897 takes care of that for us. In all other cases, two expressions are
2898 equal if they have no side effects. If we have two identical
2899 expressions with side effects that should be treated the same due
2900 to the only side effects being identical SAVE_EXPR's, that will
2901 be detected in the recursive calls below.
2902 If we are taking an invariant address of two identical objects
2903 they are necessarily equal as well. */
2910 /* Next handle constant cases, those for which we can return 1 even
2911 if ONLY_CONST is set. */
2914 {
2928 {
2929 /* If we do not distinguish between signed and unsigned zero,
2930 consider them equal. */
2933 }
2937 {
2944 {
2948 }
2950 }
2954 flags)
2956 flags));
2967 flags | OEP_ADDRESS_OF
2970 /* In GIMPLE empty constructors are allowed in initializers of
2971 aggregates. */
2975 }
2980 /* Define macros to test an operand from arg0 and arg1 for equality and a
2981 variant that allows null and views null as being different from any
2982 non-null value. In the latter case, if either is null, the both
2983 must be; otherwise, do the normal comparison. */
2984 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2985 TREE_OPERAND (arg1, N), flags)
2987 #define OP_SAME_WITH_NULL(N) \
2988 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2989 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2992 {
2994 /* Two conversions are equal only if signedness and modes match. */
2996 {
2997 CASE_CONVERT:
3005 }
3015 /* For commutative ops, allow the other order. */
3023 /* If either of the pointer (or reference) expressions we are
3024 dereferencing contain a side effect, these cannot be equal,
3025 but their addresses can be. */
3032 {
3042 /* Require the same offset. */
3048 /* Fallthru. */
3056 {
3057 /* Require equal access sizes */
3063 flags)))
3065 /* Verify that access happens in similar types. */
3068 /* Verify that accesses are TBAA compatible. */
3077 /* Verify that alignment is compatible. */
3081 }
3084 /* TARGET_MEM_REF require equal extra operands. */
3095 /* Compare the array index by value if it is constant first as we
3096 may have different types but same value here. */
3102 /* Compare low bound and element size as with OEP_ADDRESS_OF
3103 we have to account for the offset of the ref. */
3108 array_ref_low_bound
3112 array_ref_element_size
3114 flags))));
3117 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3118 may be NULL when we're called to compare MEM_EXPRs. */
3133 }
3137 {
3139 /* Be sure we pass right ADDRESS_OF flag. */
3157 /* The multiplcation operands are commutative. */
3158 /* FALLTHRU */
3166 /* Otherwise take into account this is a commutative operation. */
3202 }
3206 {
3210 /* If not both CALL_EXPRs are either internal or normal function
3211 functions, then they are not equal. */
3214 {
3215 /* If the CALL_EXPRs call different internal functions, then they
3216 are not equal. */
3219 }
3220 else
3221 {
3222 /* If the CALL_EXPRs call different functions, then they are not
3223 equal. */
3225 flags))
3227 }
3229 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3230 {
3234 else
3238 }
3240 /* Now see if all the arguments are the same. */
3241 {
3252 /* If we get here and both argument lists are exhausted
3253 then the CALL_EXPRs are equal. */
3255 }
3258 }
3261 /* Consider __builtin_sqrt equal to sqrt. */
3269 {
3270 /* In GIMPLE constructors are used only to build vectors from
3271 elements. Individual elements in the constructor must be
3272 indexed in increasing order and form an initial sequence.
3274 We make no effort to compare constructors in generic.
3275 (see sem_variable::equals in ipa-icf which can do so for
3276 constants). */
3281 /* Be sure that vectors constructed have the same representation.
3282 We only tested element precision and modes to match.
3283 Vectors may be BLKmode and thus also check that the number of
3284 parts match. */
3297 {
3302 /* In GIMPLE the indexes can be either NULL or matching i.
3303 Double check this so we won't get false
3304 positives for GENERIC. */
3312 }
3314 }
3317 {
3318 /* Compare the STATEMENT_LISTs. */
3324 {
3325 /* The lists don't have the same number of statements. */
3331 OEP_LEXICOGRAPHIC))
3333 }
3334 }
3339 {
3346 }
3350 }
3352 #undef OP_SAME
3353 #undef OP_SAME_WITH_NULL
3354 }
3355 \f
3356 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3357 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3359 When in doubt, return 0. */
3361 static int
3363 {
3375 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3376 and see if the inner values are the same. This removes any
3377 signedness comparison, which doesn't matter here. */
3384 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3385 actual comparison operand, ARG0.
3387 First throw away any conversions to wider types
3388 already present in the operands. */
3397 {
3400 /* Make sure shorter operand is extended the right way
3401 to match the longer operand. */
3407 }
3410 }
3411 \f
3412 /* See if ARG is an expression that is either a comparison or is performing
3413 arithmetic on comparisons. The comparisons must only be comparing
3414 two different values, which will be stored in *CVAL1 and *CVAL2; if
3415 they are nonzero it means that some operands have already been found.
3416 No variables may be used anywhere else in the expression except in the
3417 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3418 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3420 If this is true, return 1. Otherwise, return zero. */
3422 static int
3424 {
3428 /* We can handle some of the tcc_expression cases here. */
3438 {
3439 /* If we've already found a CVAL1 or CVAL2, this expression is
3440 two complex to handle. */
3446 }
3449 {
3472 /* First see if we can handle the first operand, then the second. For
3473 the second operand, we know *CVAL1 can't be zero. It must be that
3474 one side of the comparison is each of the values; test for the
3475 case where this isn't true by failing if the two operands
3476 are the same. */
3485 ;
3489 ;
3490 else
3494 ;
3498 ;
3499 else
3506 }
3507 }
3508 \f
3509 /* ARG is a tree that is known to contain just arithmetic operations and
3510 comparisons. Evaluate the operations in the tree substituting NEW0 for
3511 any occurrence of OLD0 as an operand of a comparison and likewise for
3512 NEW1 and OLD1. */
3514 static tree
3517 {
3522 /* We can handle some of the tcc_expression cases here. */
3530 {
3545 {
3564 }
3565 /* Fall through - ??? */
3568 {
3572 /* We need to check both for exact equality and tree equality. The
3573 former will be true if the operand has a side-effect. In that
3574 case, we know the operand occurred exactly once. */
3587 }
3591 }
3592 }
3593 \f
3594 /* Return a tree for the case when the result of an expression is RESULT
3595 converted to TYPE and OMITTED was previously an operand of the expression
3596 but is now not needed (e.g., we folded OMITTED * 0).
3598 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3599 the conversion of RESULT to TYPE. */
3601 tree
3603 {
3606 /* If the resulting operand is an empty statement, just return the omitted
3607 statement casted to void. */
3617 }
3619 /* Return a tree for the case when the result of an expression is RESULT
3620 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3621 of the expression but are now not needed.
3623 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3624 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3625 evaluated before OMITTED2. Otherwise, if neither has side effects,
3626 just do the conversion of RESULT to TYPE. */
3628 tree
3631 {
3640 }
3642 \f
3643 /* Return a simplified tree node for the truth-negation of ARG. This
3644 never alters ARG itself. We assume that ARG is an operation that
3645 returns a truth value (0 or 1).
3647 FIXME: one would think we would fold the result, but it causes
3648 problems with the dominator optimizer. */
3650 static tree
3652 {
3657 /* If this is a comparison, we can simply invert it, except for
3658 floating-point non-equality comparisons, in which case we just
3659 enclose a TRUTH_NOT_EXPR around what we have. */
3662 {
3665 && flag_trapping_math
3679 }
3682 {
3701 /* Here we can invert either operand. We invert the first operand
3702 unless the second operand is a TRUTH_NOT_EXPR in which case our
3703 result is the XOR of the first operand with the inside of the
3704 negation of the second operand. */
3709 else
3732 {
3739 /* A COND_EXPR may have a throw as one operand, which
3740 then has void type. Just leave void operands
3741 as they are. */
3747 }
3759 CASE_CONVERT:
3763 /* fall through */
3785 }
3786 }
3788 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3789 assume that ARG is an operation that returns a truth value (0 or 1
3790 for scalars, 0 or -1 for vectors). Return the folded expression if
3791 folding is successful. Otherwise, return NULL_TREE. */
3793 static tree
3795 {
3798 ? BIT_NOT_EXPR
3801 }
3803 /* Return a simplified tree node for the truth-negation of ARG. This
3804 never alters ARG itself. We assume that ARG is an operation that
3805 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3807 tree
3809 {
3815 ? BIT_NOT_EXPR
3818 }
3820 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3821 with code CODE. This optimization is unsafe. */
3822 static tree
3825 {
3829 /* (A / C) +- (B / C) -> (A +- B) / C. */
3839 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3844 {
3856 }
3859 }
3860 \f
3861 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3862 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3863 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3864 is the original memory reference used to preserve the alias set of
3865 the access. */
3867 static tree
3871 {
3874 /* Attempt not to lose the access path if possible. */
3876 {
3878 machine_mode nmode;
3880 tree noffset;
3890 && !reversep
3891 && !nreversep
3893 {
3896 }
3897 }
3906 {
3913 }
3928 }
3930 /* Optimize a bit-field compare.
3932 There are two cases: First is a compare against a constant and the
3933 second is a comparison of two items where the fields are at the same
3934 bit position relative to the start of a chunk (byte, halfword, word)
3935 large enough to contain it. In these cases we can avoid the shift
3936 implicit in bitfield extractions.
3938 For constants, we emit a compare of the shifted constant with the
3939 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3940 compared. For two fields at the same position, we do the ANDs with the
3941 similar mask and compare the result of the ANDs.
3943 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3944 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3945 are the left and right operands of the comparison, respectively.
3947 If the optimization described above can be done, we return the resulting
3948 tree. Otherwise we return zero. */
3950 static tree
3953 {
3956 tree unsigned_type;
3963 tree mask;
3964 tree offset;
3966 /* Get all the information about the extractions being done. If the bit size
3967 if the same as the size of the underlying object, we aren't doing an
3968 extraction at all and so can do nothing. We also don't want to
3969 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3970 then will no longer be able to replace it. */
3979 else
3980 {
3981 /* If this is not a constant, we can only do something if bit positions,
3982 sizes, signedness and storage order are the same. */
3983 rinner
3991 }
3993 /* Honor the C++ memory model and mimic what RTL expansion does. */
3997 {
4001 }
4003 /* See if we can find a mode to refer to this field. We should be able to,
4004 but fail if we can't. */
4013 /* Set signed and unsigned types of the precision of this mode for the
4014 shifts below. */
4017 /* Compute the bit position and size for the new reference and our offset
4018 within it. If the new reference is the same size as the original, we
4019 won't optimize anything, so return zero. */
4029 /* Make the mask to be used against the extracted field. */
4036 /* If not comparing with constant, just rework the comparison
4037 and return. */
4041 unsigned_type,
4044 mask),
4047 unsigned_type,
4050 mask));
4052 /* Otherwise, we are handling the constant case. See if the constant is too
4053 big for the field. Warn and return a tree for 0 (false) if so. We do
4054 this not only for its own sake, but to avoid having to test for this
4055 error case below. If we didn't, we might generate wrong code.
4057 For unsigned fields, the constant shifted right by the field length should
4058 be all zero. For signed fields, the high-order bits should agree with
4059 the sign bit. */
4062 {
4064 {
4068 }
4069 }
4070 else
4071 {
4074 {
4078 }
4079 }
4081 /* Single-bit compares should always be against zero. */
4083 {
4086 }
4088 /* Make a new bitfield reference, shift the constant over the
4089 appropriate number of bits and mask it with the computed mask
4090 (in case this was a signed field). If we changed it, make a new one. */
4098 mask);
4103 }
4104 \f
4105 /* Subroutine for fold_truth_andor_1: decode a field reference.
4107 If EXP is a comparison reference, we return the innermost reference.
4109 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4110 set to the starting bit number.
4112 If the innermost field can be completely contained in a mode-sized
4113 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4115 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4116 otherwise it is not changed.
4118 *PUNSIGNEDP is set to the signedness of the field.
4120 *PREVERSEP is set to the storage order of the field.
4122 *PMASK is set to the mask used. This is either contained in a
4123 BIT_AND_EXPR or derived from the width of the field.
4125 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4127 Return 0 if this is not a component reference or is one that we can't
4128 do anything with. */
4130 static tree
4135 {
4140 tree unsigned_type;
4143 /* All the optimizations using this function assume integer fields.
4144 There are problems with FP fields since the type_for_size call
4145 below can fail for, e.g., XFmode. */
4149 /* We are interested in the bare arrangement of bits, so strip everything
4150 that doesn't affect the machine mode. However, record the type of the
4151 outermost expression if it may matter below. */
4158 {
4164 }
4171 /* Reject out-of-bound accesses (PR79731). */
4179 /* If the number of bits in the reference is the same as the bitsize of
4180 the outer type, then the outer type gives the signedness. Otherwise
4181 (in case of a small bitfield) the signedness is unchanged. */
4185 /* Compute the mask to access the bitfield. */
4194 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4202 }
4204 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4205 bit positions and MASK is SIGNED. */
4207 static int
4209 {
4213 /* If this function returns true when the type of the mask is
4214 UNSIGNED, then there will be errors. In particular see
4215 gcc.c-torture/execute/990326-1.c. There does not appear to be
4216 any documentation paper trail as to why this is so. But the pre
4217 wide-int worked with that restriction and it has been preserved
4218 here. */
4223 }
4225 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4226 represents the sign bit of EXP's type. If EXP represents a sign
4227 or zero extension, also test VAL against the unextended type.
4228 The return value is the (sub)expression whose sign bit is VAL,
4229 or NULL_TREE otherwise. */
4231 tree
4233 {
4235 tree t;
4237 /* Tree EXP must have an integral type. */
4242 /* Tree VAL must be an integer constant. */
4251 /* Handle extension from a narrower type. */
4257 }
4259 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4260 to be evaluated unconditionally. */
4262 static int
4264 {
4265 /* Strip any conversions that don't change the machine mode. */
4274 /* Don't regard global variables as simple. They may be
4275 allocated in ways unknown to the compiler (shared memory,
4276 #pragma weak, etc). */
4279 /* Weakrefs are not safe to be read, since they can be NULL.
4280 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4281 have DECL_WEAK flag set. */
4283 /* Loading a static variable is unduly expensive, but global
4284 registers aren't expensive. */
4286 }
4288 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4289 to be evaluated unconditionally.
4290 I addition to simple_operand_p, we assume that comparisons, conversions,
4291 and logic-not operations are simple, if their operands are simple, too. */
4293 static bool
4295 {
4315 }
4317 \f
4318 /* The following functions are subroutines to fold_range_test and allow it to
4319 try to change a logical combination of comparisons into a range test.
4321 For example, both
4322 X == 2 || X == 3 || X == 4 || X == 5
4323 and
4324 X >= 2 && X <= 5
4325 are converted to
4326 (unsigned) (X - 2) <= 3
4328 We describe each set of comparisons as being either inside or outside
4329 a range, using a variable named like IN_P, and then describe the
4330 range with a lower and upper bound. If one of the bounds is omitted,
4331 it represents either the highest or lowest value of the type.
4333 In the comments below, we represent a range by two numbers in brackets
4334 preceded by a "+" to designate being inside that range, or a "-" to
4335 designate being outside that range, so the condition can be inverted by
4336 flipping the prefix. An omitted bound is represented by a "-". For
4337 example, "- [-, 10]" means being outside the range starting at the lowest
4338 possible value and ending at 10, in other words, being greater than 10.
4339 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4340 always false.
4342 We set up things so that the missing bounds are handled in a consistent
4343 manner so neither a missing bound nor "true" and "false" need to be
4344 handled using a special case. */
4346 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4347 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4348 and UPPER1_P are nonzero if the respective argument is an upper bound
4349 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4350 must be specified for a comparison. ARG1 will be converted to ARG0's
4351 type if both are specified. */
4353 static tree
4356 {
4357 tree tem;
4361 /* If neither arg represents infinity, do the normal operation.
4362 Else, if not a comparison, return infinity. Else handle the special
4363 comparison rules. Note that most of the cases below won't occur, but
4364 are handled for consistency. */
4367 {
4372 }
4377 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4378 for neither. In real maths, we cannot assume open ended ranges are
4379 the same. But, this is computer arithmetic, where numbers are finite.
4380 We can therefore make the transformation of any unbounded range with
4381 the value Z, Z being greater than any representable number. This permits
4382 us to treat unbounded ranges as equal. */
4386 {
4407 }
4410 }
4411 \f
4412 /* Helper routine for make_range. Perform one step for it, return
4413 new expression if the loop should continue or NULL_TREE if it should
4414 stop. */
4416 tree
4420 {
4426 {
4428 /* We can only do something if the range is testing for zero. */
4437 /* We can only do something if the range is testing for zero
4438 and if the second operand is an integer constant. Note that
4439 saying something is "in" the range we make is done by
4440 complementing IN_P since it will set in the initial case of
4441 being not equal to zero; "out" is leaving it alone. */
4448 {
4469 }
4471 /* If this is an unsigned comparison, we also know that EXP is
4472 greater than or equal to zero. We base the range tests we make
4473 on that fact, so we record it here so we can parse existing
4474 range tests. We test arg0_type since often the return type
4475 of, e.g. EQ_EXPR, is boolean. */
4477 {
4481 NULL_TREE))
4486 /* If the high bound is missing, but we have a nonzero low
4487 bound, reverse the range so it goes from zero to the low bound
4488 minus 1. */
4490 {
4495 }
4496 }
4504 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4505 low and high are non-NULL, then normalize will DTRT. */
4508 {
4513 }
4515 /* (-x) IN [a,b] -> x in [-b, -a] */
4527 /* ~ X -> -X - 1 */
4536 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4537 move a constant to the other side. */
4542 /* If EXP is signed, any overflow in the computation is undefined,
4543 so we don't worry about it so long as our computations on
4544 the bounds don't overflow. For unsigned, overflow is defined
4545 and this is exactly the right thing. */
4557 normalize:
4558 /* Check for an unsigned range which has wrapped around the maximum
4559 value thus making n_high < n_low, and normalize it. */
4561 {
4567 /* If the range is of the form +/- [ x+1, x ], we won't
4568 be able to normalize it. But then, it represents the
4569 whole range or the empty set, so make it
4570 +/- [ -, - ]. */
4574 else
4576 }
4577 else
4585 CASE_CONVERT:
4603 /* If we're converting arg0 from an unsigned type, to exp,
4604 a signed type, we will be doing the comparison as unsigned.
4605 The tests above have already verified that LOW and HIGH
4606 are both positive.
4608 So we have to ensure that we will handle large unsigned
4609 values the same way that the current signed bounds treat
4610 negative values. */
4613 {
4614 tree high_positive;
4615 tree equiv_type;
4616 /* For fixed-point modes, we need to pass the saturating flag
4617 as the 2nd parameter. */
4619 equiv_type
4622 else
4623 equiv_type
4626 /* A range without an upper bound is, naturally, unbounded.
4627 Since convert would have cropped a very large value, use
4628 the max value for the destination type. */
4629 high_positive
4636 high_positive),
4639 /* If the low bound is specified, "and" the range with the
4640 range for which the original unsigned value will be
4641 positive. */
4643 {
4646 integer_zero_node),
4647 high_positive))
4651 }
4652 else
4653 {
4654 /* Otherwise, "or" the range with the range of the input
4655 that will be interpreted as negative. */
4658 integer_zero_node),
4659 high_positive))
4663 }
4664 }
4673 }
4674 }
4676 /* Given EXP, a logical expression, set the range it is testing into
4677 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4678 actually being tested. *PLOW and *PHIGH will be made of the same
4679 type as the returned expression. If EXP is not a comparison, we
4680 will most likely not be returning a useful value and range. Set
4681 *STRICT_OVERFLOW_P to true if the return value is only valid
4682 because signed overflow is undefined; otherwise, do not change
4683 *STRICT_OVERFLOW_P. */
4685 tree
4688 {
4696 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4697 and see if we can refine the range. Some of the cases below may not
4698 happen, but it doesn't seem worth worrying about this. We "continue"
4699 the outer loop when we've changed something; otherwise we "break"
4700 the switch, which will "break" the while. */
4706 {
4712 {
4720 }
4729 }
4731 /* If EXP is a constant, we can evaluate whether this is true or false. */
4733 {
4740 }
4744 }
4745 \f
4746 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4747 type, TYPE, return an expression to test if EXP is in (or out of, depending
4748 on IN_P) the range. Return 0 if the test couldn't be created. */
4750 tree
4753 {
4756 /* Disable this optimization for function pointer expressions
4757 on targets that require function pointer canonicalization. */
4764 {
4770 }
4788 {
4790 {
4794 }
4796 }
4798 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4800 {
4804 {
4806 {
4809 etype
4811 else
4814 }
4817 }
4818 }
4820 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4821 This requires wrap-around arithmetics for the type of the expression.
4822 First make sure that arithmetics in this type is valid, then make sure
4823 that it wraps around. */
4829 {
4832 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4833 for the type in question, as we rely on this here. */
4843 else
4845 }
4855 {
4857 {
4862 }
4864 }
4872 }
4873 \f
4874 /* Return the predecessor of VAL in its type, handling the infinite case. */
4876 static tree
4878 {
4884 else
4887 }
4889 /* Return the successor of VAL in its type, handling the infinite case. */
4891 static tree
4893 {
4899 else
4902 }
4904 /* Given two ranges, see if we can merge them into one. Return 1 if we
4905 can, 0 if we can't. Set the output range into the specified parameters. */
4907 bool
4910 {
4914 tree tem;
4924 /* Make range 0 be the range that starts first, or ends last if they
4925 start at the same value. Swap them if it isn't. */
4928 || (lowequal
4931 {
4935 }
4937 /* Now flag two cases, whether the ranges are disjoint or whether the
4938 second range is totally subsumed in the first. Note that the tests
4939 below are simplified by the ones above. */
4945 /* We now have four cases, depending on whether we are including or
4946 excluding the two ranges. */
4948 {
4949 /* If they don't overlap, the result is false. If the second range
4950 is a subset it is the result. Otherwise, the range is from the start
4951 of the second to the end of the first. */
4956 else
4958 }
4961 {
4962 /* If they don't overlap, the result is the first range. If they are
4963 equal, the result is false. If the second range is a subset of the
4964 first, and the ranges begin at the same place, we go from just after
4965 the end of the second range to the end of the first. If the second
4966 range is not a subset of the first, or if it is a subset and both
4967 ranges end at the same place, the range starts at the start of the
4968 first range and ends just before the second range.
4969 Otherwise, we can't describe this as a single range. */
4975 {
4980 {
4981 /* We are in the weird situation where high0 > high1 but
4982 high1 has no successor. Punt. */
4984 }
4985 }
4987 {
4992 {
4993 /* low0 < low1 but low1 has no predecessor. Punt. */
4995 }
4996 }
4997 else
4999 }
5002 {
5003 /* If they don't overlap, the result is the second range. If the second
5004 is a subset of the first, the result is false. Otherwise,
5005 the range starts just after the first range and ends at the
5006 end of the second. */
5011 else
5012 {
5017 {
5018 /* high1 > high0 but high0 has no successor. Punt. */
5020 }
5021 }
5022 }
5024 else
5025 {
5026 /* The case where we are excluding both ranges. Here the complex case
5027 is if they don't overlap. In that case, the only time we have a
5028 range is if they are adjacent. If the second is a subset of the
5029 first, the result is the first. Otherwise, the range to exclude
5030 starts at the beginning of the first range and ends at the end of the
5031 second. */
5033 {
5038 else
5039 {
5040 /* Canonicalize - [min, x] into - [-, x]. */
5043 {
5048 /* FALLTHROUGH */
5061 }
5063 /* Canonicalize - [x, max] into - [x, -]. */
5066 {
5071 /* FALLTHROUGH */
5087 }
5089 /* The ranges might be also adjacent between the maximum and
5090 minimum values of the given type. For
5091 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5092 return + [x + 1, y - 1]. */
5094 {
5101 }
5102 else
5104 }
5105 }
5108 else
5110 }
5114 }
5115 \f
5117 /* Subroutine of fold, looking inside expressions of the form
5118 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5119 of the COND_EXPR. This function is being used also to optimize
5120 A op B ? C : A, by reversing the comparison first.
5122 Return a folded expression whose code is not a COND_EXPR
5123 anymore, or NULL_TREE if no folding opportunity is found. */
5125 static tree
5128 {
5133 tree tem;
5138 /* If we have A op 0 ? A : -A, consider applying the following
5139 transformations:
5141 A == 0? A : -A same as -A
5142 A != 0? A : -A same as A
5143 A >= 0? A : -A same as abs (A)
5144 A > 0? A : -A same as abs (A)
5145 A <= 0? A : -A same as -abs (A)
5146 A < 0? A : -A same as -abs (A)
5148 None of these transformations work for modes with signed
5149 zeros. If A is +/-0, the first two transformations will
5150 change the sign of the result (from +0 to -0, or vice
5151 versa). The last four will fix the sign of the result,
5152 even though the original expressions could be positive or
5153 negative, depending on the sign of A.
5155 Note that all these transformations are correct if A is
5156 NaN, since the two alternatives (A and -A) are also NaNs. */
5163 /* In the case that A is of the form X-Y, '-A' (arg2) may
5164 have already been folded to Y-X, check for that. */
5172 {
5184 /* Fall through. */
5195 /* FALLTHRU */
5205 }
5207 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5208 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5209 both transformations are correct when A is NaN: A != 0
5210 is then true, and A == 0 is false. */
5214 {
5219 }
5221 /* Try some transformations of A op B ? A : B.
5223 A == B? A : B same as B
5224 A != B? A : B same as A
5225 A >= B? A : B same as max (A, B)
5226 A > B? A : B same as max (B, A)
5227 A <= B? A : B same as min (A, B)
5228 A < B? A : B same as min (B, A)
5230 As above, these transformations don't work in the presence
5231 of signed zeros. For example, if A and B are zeros of
5232 opposite sign, the first two transformations will change
5233 the sign of the result. In the last four, the original
5234 expressions give different results for (A=+0, B=-0) and
5235 (A=-0, B=+0), but the transformed expressions do not.
5237 The first two transformations are correct if either A or B
5238 is a NaN. In the first transformation, the condition will
5239 be false, and B will indeed be chosen. In the case of the
5240 second transformation, the condition A != B will be true,
5241 and A will be chosen.
5243 The conversions to max() and min() are not correct if B is
5244 a number and A is not. The conditions in the original
5245 expressions will be false, so all four give B. The min()
5246 and max() versions would give a NaN instead. */
5249 /* Avoid these transformations if the COND_EXPR may be used
5250 as an lvalue in the C++ front-end. PR c++/19199. */
5251 && (in_gimple_form
5257 {
5263 {
5272 /* In C++ a ?: expression can be an lvalue, so put the
5273 operand which will be used if they are equal first
5274 so that we can convert this back to the
5275 corresponding COND_EXPR. */
5277 {
5285 }
5292 {
5300 }
5313 }
5314 }
5317 }
5320 \f
5321 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5322 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5323 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5324 false) >= 2)
5325 #endif
5327 /* EXP is some logical combination of boolean tests. See if we can
5328 merge it into some range test. Return the new tree if so. */
5330 static tree
5333 {
5349 /* If this is an OR operation, invert both sides; we will invert
5350 again at the end. */
5354 /* If both expressions are the same, if we can merge the ranges, and we
5355 can build the range test, return it or it inverted. If one of the
5356 ranges is always true or always false, consider it to be the same
5357 expression as the other. */
5365 {
5369 }
5371 /* On machines where the branch cost is expensive, if this is a
5372 short-circuited branch and the underlying object on both sides
5373 is the same, make a non-short-circuit operation. */
5379 {
5380 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5381 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5382 which cases we can't do this. */
5390 {
5399 {
5402 WARN_STRICT_OVERFLOW_COMPARISON);
5406 }
5407 }
5408 }
5411 }
5412 \f
5413 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5414 bit value. Arrange things so the extra bits will be set to zero if and
5415 only if C is signed-extended to its full width. If MASK is nonzero,
5416 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5418 static tree
5420 {
5423 tree temp;
5428 /* We work by getting just the sign bit into the low-order bit, then
5429 into the high-order bit, then sign-extend. We then XOR that value
5430 with C. */
5433 /* We must use a signed type in order to get an arithmetic right shift.
5434 However, we must also avoid introducing accidental overflows, so that
5435 a subsequent call to integer_zerop will work. Hence we must
5436 do the type conversion here. At this point, the constant is either
5437 zero or one, and the conversion to a signed type can never overflow.
5438 We could get an overflow if this conversion is done anywhere else. */
5447 /* If necessary, convert the type back to match the type of C. */
5452 }
5453 \f
5454 /* For an expression that has the form
5455 (A && B) || ~B
5456 or
5457 (A || B) && ~B,
5458 we can drop one of the inner expressions and simplify to
5459 A || ~B
5460 or
5461 A && ~B
5462 LOC is the location of the resulting expression. OP is the inner
5463 logical operation; the left-hand side in the examples above, while CMPOP
5464 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5465 removing a condition that guards another, as in
5466 (A != NULL && A->...) || A == NULL
5467 which we must not transform. If RHS_ONLY is true, only eliminate the
5468 right-most operand of the inner logical operation. */
5470 static tree
5473 {
5491 {
5494 {
5497 }
5498 }
5500 {
5503 {
5506 }
5507 }
5522 }
5524 /* Find ways of folding logical expressions of LHS and RHS:
5525 Try to merge two comparisons to the same innermost item.
5526 Look for range tests like "ch >= '0' && ch <= '9'".
5527 Look for combinations of simple terms on machines with expensive branches
5528 and evaluate the RHS unconditionally.
5530 For example, if we have p->a == 2 && p->b == 4 and we can make an
5531 object large enough to span both A and B, we can do this with a comparison
5532 against the object ANDed with the a mask.
5534 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5535 operations to do this with one comparison.
5537 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5538 function and the one above.
5540 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5541 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5543 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5544 two operands.
5546 We return the simplified tree or 0 if no optimization is possible. */
5548 static tree
5551 {
5552 /* If this is the "or" of two comparisons, we can do something if
5553 the comparisons are NE_EXPR. If this is the "and", we can do something
5554 if the comparisons are EQ_EXPR. I.e.,
5555 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5557 WANTED_CODE is this operation code. For single bit fields, we can
5558 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5559 comparison for one-bit fields. */
5580 /* Start by getting the comparison codes. Fail if anything is volatile.
5581 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5582 it were surrounded with a NE_EXPR. */
5591 {
5595 }
5598 {
5602 }
5613 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5616 {
5619 {
5624 }
5627 {
5633 }
5634 }
5639 /* If the RHS can be evaluated unconditionally and its operands are
5640 simple, it wins to evaluate the RHS unconditionally on machines
5641 with expensive branches. In this case, this isn't a comparison
5642 that can be merged. */
5649 {
5650 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5661 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5671 }
5673 /* See if the comparisons can be merged. Then get all the parameters for
5674 each side. */
5699 /* It must be true that the inner operation on the lhs of each
5700 comparison must be the same if we are to be able to do anything.
5701 Then see if we have constants. If not, the same must be true for
5702 the rhs's. */
5711 {
5714 }
5719 else
5722 /* If either comparison code is not correct for our logical operation,
5723 fail. However, we can convert a one-bit comparison against zero into
5724 the opposite comparison against that bit being set in the field. */
5728 {
5730 {
5731 /* Make the left operand unsigned, since we are only interested
5732 in the value of one bit. Otherwise we are doing the wrong
5733 thing below. */
5736 }
5737 else
5739 }
5741 /* This is analogous to the code for l_const above. */
5743 {
5745 {
5748 }
5749 else
5751 }
5753 /* See if we can find a mode that contains both fields being compared on
5754 the left. If we can't, fail. Otherwise, update all constants and masks
5755 to be relative to a field of that size. */
5760 volatilep);
5770 {
5773 }
5781 {
5788 {
5792 }
5793 }
5795 {
5802 {
5806 }
5807 }
5809 /* If the right sides are not constant, do the same for it. Also,
5810 disallow this optimization if a size or signedness mismatch occurs
5811 between the left and right sides. */
5813 {
5816 /* Make sure the two fields on the right
5817 correspond to the left without being swapped. */
5825 volatilep);
5835 {
5838 }
5847 /* Make a mask that corresponds to both fields being compared.
5848 Do this for both items being compared. If the operands are the
5849 same size and the bits being compared are in the same position
5850 then we can do this by masking both and comparing the masked
5851 results. */
5855 {
5869 }
5871 /* There is still another way we can do something: If both pairs of
5872 fields being compared are adjacent, we may be able to make a wider
5873 field containing them both.
5875 Note that we still must mask the lhs/rhs expressions. Furthermore,
5876 the mask must be shifted to account for the shift done by
5877 make_bit_field_ref. */
5882 {
5883 tree type;
5899 /* Convert to the smaller type before masking out unwanted bits. */
5902 {
5904 {
5908 }
5910 {
5914 }
5915 }
5924 }
5927 }
5929 /* Handle the case of comparisons with constants. If there is something in
5930 common between the masks, those bits of the constants must be the same.
5931 If not, the condition is always false. Test for this to avoid generating
5932 incorrect code below. */
5937 {
5939 {
5942 }
5943 else
5944 {
5947 }
5948 }
5950 /* Construct the expression we will return. First get the component
5951 reference we will make. Unless the mask is all ones the width of
5952 that field, perform the mask operation. Then compare with the
5953 merged constant. */
5964 }
5965 \f
5966 /* T is an integer expression that is being multiplied, divided, or taken a
5967 modulus (CODE says which and what kind of divide or modulus) by a
5968 constant C. See if we can eliminate that operation by folding it with
5969 other operations already in T. WIDE_TYPE, if non-null, is a type that
5970 should be used for the computation if wider than our type.
5972 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5973 (X * 2) + (Y * 4). We must, however, be assured that either the original
5974 expression would not overflow or that overflow is undefined for the type
5975 in the language in question.
5977 If we return a non-null expression, it is an equivalent form of the
5978 original computation, but need not be in the original type.
5980 We set *STRICT_OVERFLOW_P to true if the return values depends on
5981 signed overflow being undefined. Otherwise we do not change
5982 *STRICT_OVERFLOW_P. */
5984 static tree
5987 {
5988 /* To avoid exponential search depth, refuse to allow recursion past
5989 three levels. Beyond that (1) it's highly unlikely that we'll find
5990 something interesting and (2) we've probably processed it before
5991 when we built the inner expression. */
5994 tree ret;
5999 depth++;
6001 depth--;
6004 }
6006 static tree
6009 {
6020 /* Don't deal with constants of zero here; they confuse the code below. */
6030 /* Note that we need not handle conditional operations here since fold
6031 already handles those cases. So just do arithmetic here. */
6033 {
6035 /* For a constant, we can always simplify if we are a multiply
6036 or (for divide and modulus) if it is a multiple of our constant. */
6039 {
6042 /* If the multiplication overflowed, we lost information on it.
6043 See PR68142 and PR69845. */
6047 }
6051 /* If op0 is an expression ... */
6057 /* ... and has wrapping overflow, and its type is smaller
6058 than ctype, then we cannot pass through as widening. */
6063 /* ... or this is a truncation (t is narrower than op0),
6064 then we cannot pass through this narrowing. */
6067 /* ... or signedness changes for division or modulus,
6068 then we cannot pass through this conversion. */
6072 /* ... or has undefined overflow while the converted to
6073 type has not, we cannot do the operation in the inner type
6074 as that would introduce undefined overflow. */
6080 /* Pass the constant down and see if we can make a simplification. If
6081 we can, replace this expression with the inner simplification for
6082 possible later conversion to our or some other type. */
6087 code == MULT_EXPR
6089 strict_overflow_p))))
6094 /* If widening the type changes it from signed to unsigned, then we
6095 must avoid building ABS_EXPR itself as unsigned. */
6097 {
6101 {
6104 }
6106 }
6107 /* If the constant is negative, we cannot simplify this. */
6110 /* FALLTHROUGH */
6112 /* For division and modulus, type can't be unsigned, as e.g.
6113 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6114 For signed types, even with wrapping overflow, this is fine. */
6123 /* If widening the type changes the signedness, then we can't perform
6124 this optimization as that changes the result. */
6128 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6134 {
6141 }
6145 /* If the second operand is constant, this is a multiplication
6146 or floor division, by a power of two, so we can treat it that
6147 way unless the multiplier or divisor overflows. Signed
6148 left-shift overflow is implementation-defined rather than
6149 undefined in C90, so do not convert signed left shift into
6150 multiplication. */
6153 /* const_binop may not detect overflow correctly,
6154 so check for it explicitly here. */
6158 size_one_node,
6159 op1)))
6163 ctype,
6165 t1),
6170 /* See if we can eliminate the operation on both sides. If we can, we
6171 can return a new PLUS or MINUS. If we can't, the only remaining
6172 cases where we can do anything are if the second operand is a
6173 constant. */
6179 /* If not multiplication, we can only do this if both operands
6180 are divisible by c. */
6183 {
6188 }
6190 /* If this was a subtraction, negate OP1 and set it to be an addition.
6191 This simplifies the logic below. */
6193 {
6195 /* If OP1 was not easily negatable, the constant may be OP0. */
6197 {
6200 }
6201 }
6206 /* If either OP1 or C are negative, this optimization is not safe for
6207 some of the division and remainder types while for others we need
6208 to change the code. */
6210 {
6218 }
6220 /* If it's a multiply or a division/modulus operation of a multiple
6221 of our constant, do the operation and verify it doesn't overflow. */
6224 {
6227 /* We allow the constant to overflow with wrapping semantics. */
6231 }
6232 else
6235 /* If we have an unsigned type, we cannot widen the operation since it
6236 will change the result if the original computation overflowed. */
6240 /* If we were able to eliminate our operation from the first side,
6241 apply our operation to the second side and reform the PLUS. */
6245 /* The last case is if we are a multiply. In that case, we can
6246 apply the distributive law to commute the multiply and addition
6247 if the multiplication of the constants doesn't overflow
6248 and overflow is defined. With undefined overflow
6249 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6255 op1);
6260 /* We have a special case here if we are doing something like
6261 (C * 8) % 4 since we know that's zero. */
6264 /* If the multiplication can overflow we cannot optimize this. */
6268 {
6271 }
6273 /* ... fall through ... */
6277 /* If we can extract our operation from the LHS, do so and return a
6278 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6279 do something only if the second operand is a constant. */
6293 /* If these are the same operation types, we can associate them
6294 assuming no overflow. */
6296 {
6311 }
6313 /* If these operations "cancel" each other, we have the main
6314 optimizations of this pass, which occur when either constant is a
6315 multiple of the other, in which case we replace this with either an
6316 operation or CODE or TCODE.
6318 If we have an unsigned type, we cannot do this since it will change
6319 the result if the original computation overflowed. */
6326 {
6328 {
6335 }
6337 {
6344 }
6345 }
6350 }
6353 }
6354 \f
6355 /* Return a node which has the indicated constant VALUE (either 0 or
6356 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6357 and is of the indicated TYPE. */
6359 tree
6361 {
6370 else
6372 }
6375 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6376 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6377 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6378 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6379 COND is the first argument to CODE; otherwise (as in the example
6380 given here), it is the second argument. TYPE is the type of the
6381 original expression. Return NULL_TREE if no simplification is
6382 possible. */
6384 static tree
6389 {
6399 {
6403 /* If this operand throws an expression, then it does not make
6404 sense to try to perform a logical or arithmetic operation
6405 involving it. */
6410 }
6413 {
6418 }
6419 else
6420 /* Detect the case of mixing vector and scalar types - bail out. */
6426 /* This transformation is only worthwhile if we don't have to wrap ARG
6427 in a SAVE_EXPR and the operation can be simplified without recursing
6428 on at least one of the branches once its pushed inside the COND_EXPR. */
6437 {
6441 else
6443 }
6445 {
6449 else
6451 }
6453 /* Check that we have simplified at least one of the branches. */
6458 }
6460 \f
6461 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6463 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6464 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6465 ADDEND is the same as X.
6467 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6468 and finite. The problematic cases are when X is zero, and its mode
6469 has signed zeros. In the case of rounding towards -infinity,
6470 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6471 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6473 bool
6475 {
6479 /* Don't allow the fold with -fsignaling-nans. */
6483 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6487 /* In a vector or complex, we would need to check the sign of all zeros. */
6491 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6495 /* The mode has signed zeros, and we have to honor their sign.
6496 In this situation, there is only one case we can return true for.
6497 X - 0 is the same as X unless rounding towards -infinity is
6498 supported. */
6500 }
6502 /* Subroutine of fold() that optimizes comparisons of a division by
6503 a nonzero integer constant against an integer constant, i.e.
6504 X/C1 op C2.
6506 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6507 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6508 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6510 The function returns the constant folded tree if a simplification
6511 can be made, and NULL_TREE otherwise. */
6513 static tree
6516 {
6524 /* We have to do this the hard way to detect unsigned overflow.
6525 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6531 {
6536 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6540 }
6542 {
6546 {
6565 }
6566 }
6567 else
6568 {
6569 /* A negative divisor reverses the relational operators. */
6575 {
6594 }
6595 }
6598 {
6619 {
6622 }
6627 {
6630 }
6635 {
6638 }
6643 {
6646 }
6651 }
6654 }
6657 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6658 equality/inequality test, then return a simplified form of the test
6659 using a sign testing. Otherwise return NULL. TYPE is the desired
6660 result type. */
6662 static tree
6665 tree result_type)
6666 {
6667 /* If this is testing a single bit, we can optimize the test. */
6671 {
6672 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6673 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6677 /* This is only a win if casting to a signed type is cheap,
6678 i.e. when arg00's type is not a partial mode. */
6681 {
6684 result_type,
6687 }
6688 }
6691 }
6693 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6694 equality/inequality test, then return a simplified form of
6695 the test using shifts and logical operations. Otherwise return
6696 NULL. TYPE is the desired result type. */
6698 tree
6701 {
6702 /* If this is testing a single bit, we can optimize the test. */
6706 {
6715 /* First, see if we can fold the single bit test into a sign-bit
6716 test. */
6718 result_type);
6722 /* Otherwise we have (A & C) != 0 where C is a single bit,
6723 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6724 Similarly for (A & C) == 0. */
6726 /* If INNER is a right shift of a constant and it plus BITNUM does
6727 not overflow, adjust BITNUM and INNER. */
6733 {
6736 }
6738 /* If we are going to be able to omit the AND below, we must do our
6739 operations as unsigned. If we must use the AND, we have a choice.
6740 Normally unsigned is faster, but for some machines signed is. */
6758 /* Put the AND last so it can combine with more things. */
6761 /* Make sure to return the proper type. */
6765 }
6767 }
6769 /* Test whether it is preferable two swap two operands, ARG0 and
6770 ARG1, for example because ARG0 is an integer constant and ARG1
6771 isn't. */
6773 bool
6775 {
6789 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6790 for commutative and comparison operators. Ensuring a canonical
6791 form allows the optimizers to find additional redundancies without
6792 having to explicitly check for both orderings. */
6798 /* Put SSA_NAMEs last. */
6804 /* Put variables last. */
6811 }
6814 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6815 means A >= Y && A != MAX, but in this case we know that
6816 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6818 static tree
6820 {
6827 else
6836 {
6839 }
6841 {
6844 }
6845 else
6852 {
6853 /* Convert the pointer types into integer before taking the difference. */
6857 }
6858 else
6865 }
6867 /* Fold a sum or difference of at least one multiplication.
6868 Returns the folded tree or NULL if no simplification could be made. */
6870 static tree
6873 {
6877 /* (A * C) +- (B * C) -> (A+-B) * C.
6878 (A * C) +- A -> A * (C+-1).
6879 We are most concerned about the case where C is a constant,
6880 but other combinations show up during loop reduction. Since
6881 it is not difficult, try all four possibilities. */
6884 {
6887 }
6889 {
6892 }
6893 else
6894 {
6895 /* We cannot generate constant 1 for fract. */
6900 }
6902 {
6905 }
6907 {
6909 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6910 the purpose of this canonicalization. */
6914 {
6917 }
6918 else
6920 }
6921 else
6922 {
6923 /* We cannot generate constant 1 for fract. */
6928 }
6940 /* No identical multiplicands; see if we can find a common
6941 power-of-two factor in non-power-of-two multiplies. This
6942 can help in multi-dimensional array access. */
6945 {
6948 tree maybe_same;
6952 /* Move min of absolute values to int11. */
6954 {
6959 }
6960 else
6964 /* The remainder should not be a constant, otherwise we
6965 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6966 increased the number of multiplications necessary. */
6968 {
6976 }
6977 }
6987 }
6989 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6990 specified by EXPR into the buffer PTR of length LEN bytes.
6991 Return the number of bytes placed in the buffer, or zero
6992 upon failure. */
6994 static int
6996 {
7010 {
7012 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7013 number of bytes. */
7017 {
7024 else
7026 }
7027 else
7032 }
7034 }
7037 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7038 specified by EXPR into the buffer PTR of length LEN bytes.
7039 Return the number of bytes placed in the buffer, or zero
7040 upon failure. */
7042 static int
7044 {
7048 FIXED_VALUE_TYPE value;
7064 }
7067 /* Subroutine of native_encode_expr. Encode the REAL_CST
7068 specified by EXPR into the buffer PTR of length LEN bytes.
7069 Return the number of bytes placed in the buffer, or zero
7070 upon failure. */
7072 static int
7074 {
7080 /* There are always 32 bits in each long, no matter the size of
7081 the hosts long. We handle floating point representations with
7082 up to 192 bits. */
7096 {
7101 {
7108 else
7110 }
7111 else
7112 {
7115 {
7116 /* Reverse bytes within each long, or within the entire float
7117 if it's smaller than a long (for HFmode). */
7120 }
7121 }
7126 }
7128 }
7130 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7131 specified by EXPR into the buffer PTR of length LEN bytes.
7132 Return the number of bytes placed in the buffer, or zero
7133 upon failure. */
7135 static int
7137 {
7139 tree part;
7154 }
7157 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7158 specified by EXPR into the buffer PTR of length LEN bytes.
7159 Return the number of bytes placed in the buffer, or zero
7160 upon failure. */
7162 static int
7164 {
7174 {
7176 {
7179 }
7190 }
7192 }
7195 /* Subroutine of native_encode_expr. Encode the STRING_CST
7196 specified by EXPR into the buffer PTR of length LEN bytes.
7197 Return the number of bytes placed in the buffer, or zero
7198 upon failure. */
7200 static int
7202 {
7204 HOST_WIDE_INT total_bytes;
7218 {
7221 {
7224 }
7227 }
7228 else
7231 }
7234 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7235 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7236 buffer PTR of length LEN bytes. If OFF is not -1 then start
7237 the encoding at byte offset OFF and encode at most LEN bytes.
7238 Return the number of bytes placed in the buffer, or zero upon failure. */
7240 int
7242 {
7243 /* We don't support starting at negative offset and -1 is special. */
7248 {
7269 }
7270 }
7273 /* Subroutine of native_interpret_expr. Interpret the contents of
7274 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7275 If the buffer cannot be interpreted, return NULL_TREE. */
7277 static tree
7279 {
7289 }
7292 /* Subroutine of native_interpret_expr. Interpret the contents of
7293 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7294 If the buffer cannot be interpreted, return NULL_TREE. */
7296 static tree
7298 {
7300 double_int result;
7301 FIXED_VALUE_TYPE fixed_value;
7311 }
7314 /* Subroutine of native_interpret_expr. Interpret the contents of
7315 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7316 If the buffer cannot be interpreted, return NULL_TREE. */
7318 static tree
7320 {
7324 /* There are always 32 bits in each long, no matter the size of
7325 the hosts long. We handle floating point representations with
7326 up to 192 bits. */
7327 REAL_VALUE_TYPE r;
7338 {
7339 /* Both OFFSET and BYTE index within a long;
7340 bitpos indexes the whole float. */
7343 {
7350 else
7352 }
7353 else
7354 {
7357 {
7358 /* Reverse bytes within each long, or within the entire float
7359 if it's smaller than a long (for HFmode). */
7362 }
7363 }
7367 }
7371 }
7374 /* Subroutine of native_interpret_expr. Interpret the contents of
7375 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7376 If the buffer cannot be interpreted, return NULL_TREE. */
7378 static tree
7380 {
7395 }
7398 /* Subroutine of native_interpret_expr. Interpret the contents of
7399 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7400 If the buffer cannot be interpreted, return NULL_TREE. */
7402 static tree
7404 {
7417 {
7422 }
7424 }
7427 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7428 the buffer PTR of length LEN as a constant of type TYPE. For
7429 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7430 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7431 return NULL_TREE. */
7433 tree
7435 {
7437 {
7459 }
7460 }
7462 /* Returns true if we can interpret the contents of a native encoding
7463 as TYPE. */
7465 static bool
7467 {
7469 {
7482 }
7483 }
7485 /* Return true iff a constant of type TYPE is accepted by
7486 native_encode_expr. */
7488 bool
7490 {
7492 {
7502 }
7503 }
7505 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7506 TYPE at compile-time. If we're unable to perform the conversion
7507 return NULL_TREE. */
7509 static tree
7511 {
7512 /* We support up to 512-bit values (for V8DFmode). */
7516 /* Check that the host and target are sane. */
7525 }
7527 /* Build an expression for the address of T. Folds away INDIRECT_REF
7528 to avoid confusing the gimplify process. */
7530 tree
7532 {
7533 /* The size of the object is not relevant when talking about its address. */
7538 {
7543 }
7553 {
7558 }
7559 else
7563 }
7565 /* Build an expression for the address of T. */
7567 tree
7569 {
7573 }
7575 /* Fold a unary expression of code CODE and type TYPE with operand
7576 OP0. Return the folded expression if folding is successful.
7577 Otherwise, return NULL_TREE. */
7579 tree
7581 {
7582 tree tem;
7583 tree arg0;
7591 {
7594 {
7595 /* Don't use STRIP_NOPS, because signedness of argument type
7596 matters. */
7598 }
7599 else
7600 {
7601 /* Strip any conversions that don't change the mode. This
7602 is safe for every expression, except for a comparison
7603 expression because its signedness is derived from its
7604 operands.
7606 Note that this is done as an internal manipulation within
7607 the constant folder, in order to find the simplest
7608 representation of the arguments so that their form can be
7609 studied. In any cases, the appropriate type conversions
7610 should be put back in the tree that will get out of the
7611 constant folder. */
7613 }
7616 {
7619 {
7623 }
7624 }
7625 }
7632 {
7639 {
7653 /* If this was a conversion, and all we did was to move into
7654 inside the COND_EXPR, bring it back out. But leave it if
7655 it is a conversion from integer to integer and the
7656 result precision is no wider than a word since such a
7657 conversion is cheap and may be optimized away by combine,
7658 while it couldn't if it were outside the COND_EXPR. Then return
7659 so we don't get into an infinite recursion loop taking the
7660 conversion out and then back in. */
7672 && (INTEGRAL_TYPE_P
7685 }
7686 }
7689 {
7695 CASE_CONVERT:
7699 {
7700 /* If we have (type) (a CMP b) and type is an integral type, return
7701 new expression involving the new type. Canonicalize
7702 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7703 non-integral type.
7704 Do not fold the result as that would not simplify further, also
7705 folding again results in recursions. */
7715 }
7717 /* Handle (T *)&A.B.C for A being of type T and B and C
7718 living at offset zero. This occurs frequently in
7719 C++ upcasting and then accessing the base. */
7723 {
7725 tree offset;
7726 machine_mode mode;
7728 tree base
7732 /* If the reference was to a (constant) zero offset, we can use
7733 the address of the base if it has the same base type
7734 as the result type and the pointer type is unqualified. */
7741 }
7745 /* Detect assigning a bitfield. */
7747 && DECL_BIT_FIELD
7749 {
7750 /* Don't leave an assignment inside a conversion
7751 unless assigning a bitfield. */
7753 /* First do the assignment, then return converted constant. */
7758 }
7760 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7761 constants (if x has signed type, the sign bit cannot be set
7762 in c). This folds extension into the BIT_AND_EXPR.
7763 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7764 very likely don't have maximal range for their precision and this
7765 transformation effectively doesn't preserve non-maximal ranges. */
7769 {
7780 <= HOST_BITS_PER_WIDE_INT
7782 {
7786 cst &= HOST_WIDE_INT_M1U
7790 && !flag_syntax_only
7793 {
7797 }
7798 }
7800 {
7805 }
7806 }
7808 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7809 cast (T1)X will fold away. We assume that this happens when X itself
7810 is a cast. */
7814 {
7818 return fold_build_pointer_plus_loc
7820 }
7822 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7823 of the same precision, and X is an integer type not narrower than
7824 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7830 {
7836 }
7838 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7839 type of X and Y (integer types only). */
7844 {
7845 /* Be careful not to introduce new overflows. */
7846 tree mult_type;
7849 else
7853 {
7860 }
7861 }
7867 {
7874 }
7885 /* Convert fabs((double)float) into (double)fabsf(float). */
7888 {
7894 targ0));
7895 }
7899 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7918 /* Note that the operand of this must be an int
7919 and its values must be 0 or 1.
7920 ("true" is a fixed value perhaps depending on the language,
7921 but we don't handle values other than 1 correctly yet.) */
7928 /* Fold *&X to X if X is an lvalue. */
7930 {
7937 }
7943 }
7946 /* If the operation was a conversion do _not_ mark a resulting constant
7947 with TREE_OVERFLOW if the original constant was not. These conversions
7948 have implementation defined behavior and retaining the TREE_OVERFLOW
7949 flag here would confuse later passes such as VRP. */
7950 tree
7953 {
7962 }
7964 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7965 operands OP0 and OP1. LOC is the location of the resulting expression.
7966 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7967 Return the folded expression if folding is successful. Otherwise,
7968 return NULL_TREE. */
7969 static tree
7972 {
7973 tree tem;
7975 /* We only do these simplifications if we are optimizing. */
7979 /* Check for things like (A || B) && (A || C). We can convert this
7980 to A || (B && C). Note that either operator can be any of the four
7981 truth and/or operations and the transformation will still be
7982 valid. Also note that we only care about order for the
7983 ANDIF and ORIF operators. If B contains side effects, this
7984 might change the truth-value of A. */
7991 {
8011 /* This case if tricky because we must either have commutative
8012 operators or else A10 must not have side-effects. */
8018 a01);
8019 }
8021 /* See if we can build a range comparison. */
8027 {
8031 }
8035 {
8039 }
8041 /* Check for the possibility of merging component references. If our
8042 lhs is another similar operation, try to merge its rhs with our
8043 rhs. Then try to merge our lhs and rhs. */
8057 {
8064 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8065 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8066 We don't want to pack more than two leafs to a non-IF AND/OR
8067 expression.
8068 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8069 equal to IF-CODE, then we don't want to add right-hand operand.
8070 If the inner right-hand side of left-hand operand has
8071 side-effects, or isn't simple, then we can't add to it,
8072 as otherwise we might destroy if-sequence. */
8075 /* Needed for sequence points to handle trappings, and
8076 side-effects. */
8078 {
8080 arg1);
8082 tem);
8083 }
8084 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8085 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8088 /* Needed for sequence points to handle trappings, and
8089 side-effects. */
8091 {
8096 }
8097 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8098 into (A OR B).
8099 For sequence point consistancy, we need to check for trapping,
8100 and side-effects. */
8104 }
8107 }
8109 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8110 by changing CODE to reduce the magnitude of constants involved in
8111 ARG0 of the comparison.
8112 Returns a canonicalized comparison tree if a simplification was
8113 possible, otherwise returns NULL_TREE.
8114 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8115 valid if signed overflow is undefined. */
8117 static tree
8121 {
8126 /* Match A +- CST code arg1. We can change this only if overflow
8127 is undefined. */
8130 /* In principle pointers also have undefined overflow behavior,
8131 but that causes problems elsewhere. */
8138 /* Identify the constant in arg0 and its sign. */
8142 /* Overflowed constants and zero will cause problems. */
8147 /* See if we can reduce the magnitude of the constant in
8148 arg0 by changing the comparison code. */
8149 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8153 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8157 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8161 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8165 else
8169 /* Now build the constant reduced in magnitude. But not if that
8170 would produce one outside of its types range. */
8186 }
8188 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8189 overflow further. Try to decrease the magnitude of constants involved
8190 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8191 and put sole constants at the second argument position.
8192 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8194 static tree
8197 {
8198 tree t;
8203 /* Try canonicalization by simplifying arg0. */
8208 {
8212 }
8214 /* Try canonicalization by simplifying arg1 using the swapped
8215 comparison. */
8223 }
8225 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8226 space. This is used to avoid issuing overflow warnings for
8227 expressions like &p->x which can not wrap. */
8229 static bool
8231 {
8238 wide_int wi_offset;
8244 else
8260 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8261 array. */
8263 {
8264 HOST_WIDE_INT base_size;
8269 }
8272 }
8274 /* Return a positive integer when the symbol DECL is known to have
8275 a nonzero address, zero when it's known not to (e.g., it's a weak
8276 symbol), and a negative integer when the symbol is not yet in the
8277 symbol table and so whether or not its address is zero is unknown.
8278 For function local objects always return positive integer. */
8279 static int
8281 {
8286 /* Function local objects are never NULL. */
8294 }
8296 /* Subroutine of fold_binary. This routine performs all of the
8297 transformations that are common to the equality/inequality
8298 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8299 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8300 fold_binary should call fold_binary. Fold a comparison with
8301 tree code CODE and type TYPE with operands OP0 and OP1. Return
8302 the folded comparison or NULL_TREE. */
8304 static tree
8307 {
8317 /* For comparisons of pointers we can decompose it to a compile time
8318 comparison of the base objects and the offsets into the object.
8319 This requires at least one operand being an ADDR_EXPR or a
8320 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8326 {
8329 machine_mode mode;
8333 /* Get base and offset for the access. Strip ADDR_EXPR for
8334 get_inner_reference, but put it back by stripping INDIRECT_REF
8335 off the base object if possible. indirect_baseN will be true
8336 if baseN is not an address but refers to the object itself. */
8339 {
8340 base0
8346 else
8348 }
8350 {
8354 {
8355 base0
8361 else
8363 }
8366 else
8370 {
8376 {
8379 }
8380 }
8381 }
8385 {
8386 base1
8392 else
8394 }
8396 {
8400 {
8401 base1
8407 else
8409 }
8412 else
8416 {
8422 {
8425 }
8426 }
8427 }
8429 /* If we have equivalent bases we might be able to simplify. */
8433 {
8434 /* We can fold this expression to a constant if the non-constant
8435 offset parts are equal. */
8439 && (equality_code
8440 || (indirect_base0
8444 {
8450 "occur when comparing P +- C1 with "
8452 WARN_STRICT_OVERFLOW_CONDITIONAL);
8455 {
8469 }
8470 }
8471 /* We can simplify the comparison to a comparison of the variable
8472 offset parts if the constant offset parts are equal.
8473 Be careful to use signed sizetype here because otherwise we
8474 mess with array offsets in the wrong way. This is possible
8475 because pointer arithmetic is restricted to retain within an
8476 object and overflow on pointer differences is undefined as of
8477 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8479 && (equality_code
8480 || (indirect_base0
8483 {
8484 /* By converting to signed sizetype we cover middle-end pointer
8485 arithmetic which operates on unsigned pointer types of size
8486 type size and ARRAY_REF offsets which are properly sign or
8487 zero extended from their type in case it is narrower than
8488 sizetype. */
8491 else
8495 else
8502 "occur when comparing P +- C1 with "
8504 WARN_STRICT_OVERFLOW_COMPARISON);
8507 }
8508 }
8509 /* For equal offsets we can simplify to a comparison of the
8510 base addresses. */
8512 && (indirect_base0
8514 && (indirect_base1
8519 {
8525 }
8526 /* Comparison between an ordinary (non-weak) symbol and a null
8527 pointer can be eliminated since such symbols must have a non
8528 null address. In C, relational expressions between pointers
8529 to objects and null pointers are undefined. The results
8530 below follow the C++ rules with the additional property that
8531 every object pointer compares greater than a null pointer.
8532 */
8535 /* Avoid folding references to struct members at offset 0 to
8536 prevent tests like '&ptr->firstmember == 0' from getting
8537 eliminated. When ptr is null, although the -> expression
8538 is strictly speaking invalid, GCC retains it as a matter
8539 of QoI. See PR c/44555. */
8542 && indirect_base0
8543 /* The caller guarantees that when one of the arguments is
8544 constant (i.e., null in this case) it is second. */
8546 {
8548 {
8559 }
8560 }
8561 }
8563 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8564 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8565 the resulting offset is smaller in absolute value than the
8566 original one and has the same sign. */
8575 {
8580 tree cst;
8582 "occur when combining constants around "
8585 /* Put the constant on the side where it doesn't overflow and is
8586 of lower absolute value and of same sign than before. */
8593 {
8596 variable1,
8600 }
8608 {
8614 variable2);
8615 }
8616 }
8622 /* If we are comparing an expression that just has comparisons
8623 of two integer values, arithmetic expressions of those comparisons,
8624 and constants, we can simplify it. There are only three cases
8625 to check: the two values can either be equal, the first can be
8626 greater, or the second can be greater. Fold the expression for
8627 those three values. Since each value must be 0 or 1, we have
8628 eight possibilities, each of which corresponds to the constant 0
8629 or 1 or one of the six possible comparisons.
8631 This handles common cases like (a > b) == 0 but also handles
8632 expressions like ((x > y) - (y > x)) > 0, which supposedly
8633 occur in macroized code. */
8636 {
8641 /* Don't handle degenerate cases here; they should already
8642 have been handled anyway. */
8651 {
8655 /* We can't just pass T to eval_subst in case cval1 or cval2
8656 was the same as ARG1. */
8658 tree high_result
8662 arg1);
8663 tree equal_result
8667 arg1);
8668 tree low_result
8672 arg1);
8674 /* All three of these results should be 0 or 1. Confirm they are.
8675 Then use those values to select the proper code to use. */
8680 {
8681 /* Make a 3-bit mask with the high-order bit being the
8682 value for `>', the next for '=', and the low for '<'. */
8686 {
8688 /* Always false. */
8709 /* Always true. */
8711 }
8714 {
8718 }
8720 }
8721 }
8722 }
8724 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8725 into a single range test. */
8732 {
8736 }
8739 }
8742 /* Subroutine of fold_binary. Optimize complex multiplications of the
8743 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8744 argument EXPR represents the expression "z" of type TYPE. */
8746 static tree
8748 {
8753 {
8756 }
8758 {
8761 }
8762 else
8763 {
8767 }
8776 }
8779 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8780 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8782 static bool
8784 {
8788 {
8791 }
8793 {
8799 else
8801 }
8802 else
8808 }
8810 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8811 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8812 NULL_TREE otherwise. */
8814 static tree
8816 {
8833 {
8837 }
8840 {
8846 }
8847 else
8849 }
8851 /* Try to fold a pointer difference of type TYPE two address expressions of
8852 array references AREF0 and AREF1 using location LOC. Return a
8853 simplified expression for the difference or NULL_TREE. */
8855 static tree
8858 {
8863 /* If the bases are array references as well, recurse. If the bases
8864 are pointer indirections compute the difference of the pointers.
8865 If the bases are equal, we are set. */
8868 && (base_offset
8872 && (base_offset
8878 {
8884 base_offset,
8887 }
8889 }
8891 /* If the real or vector real constant CST of type TYPE has an exact
8892 inverse, return it, else return NULL. */
8894 tree
8896 {
8897 REAL_VALUE_TYPE r;
8899 machine_mode mode;
8903 {
8919 {
8924 }
8930 }
8931 }
8933 /* Mask out the tz least significant bits of X of type TYPE where
8934 tz is the number of trailing zeroes in Y. */
8935 static wide_int
8937 {
8942 }
8944 /* Return true when T is an address and is known to be nonzero.
8945 For floating point we further ensure that T is not denormal.
8946 Similar logic is present in nonzero_address in rtlanal.h.
8948 If the return value is based on the assumption that signed overflow
8949 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8950 change *STRICT_OVERFLOW_P. */
8952 static bool
8954 {
8958 /* Doing something useful for floating point would need more work. */
8964 {
8967 strict_overflow_p);
8973 strict_overflow_p);
8981 }
8984 {
8987 strict_overflow_p);
8995 strict_overflow_p);
9010 strict_overflow_p);
9014 strict_overflow_p);
9017 {
9029 }
9033 }
9035 }
9037 /* Return true when T is an address and is known to be nonzero.
9038 Handle warnings about undefined signed overflow. */
9040 bool
9042 {
9049 "determining that expression is always "
9051 WARN_STRICT_OVERFLOW_MISC);
9053 }
9055 /* Return true if T is known not to be equal to an integer W. */
9057 bool
9059 {
9061 value_range_type rtype;
9063 {
9072 {
9077 }
9082 /* If T has some known zero bits and W has any of those bits set,
9083 then T is known not to be equal to W. */
9091 }
9092 }
9094 /* Fold a binary expression of code CODE and type TYPE with operands
9095 OP0 and OP1. LOC is the location of the resulting expression.
9096 Return the folded expression if folding is successful. Otherwise,
9097 return NULL_TREE. */
9099 tree
9102 {
9117 /* Strip any conversions that don't change the mode. This is
9118 safe for every expression, except for a comparison expression
9119 because its signedness is derived from its operands. So, in
9120 the latter case, only strip conversions that don't change the
9121 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9122 preserved.
9124 Note that this is done as an internal manipulation within the
9125 constant folder, in order to find the simplest representation
9126 of the arguments so that their form can be studied. In any
9127 cases, the appropriate type conversions should be put back in
9128 the tree that will get out of the constant folder. */
9131 {
9134 }
9135 else
9136 {
9139 }
9141 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9142 constant but we can't do arithmetic on them. */
9144 {
9147 {
9151 }
9152 }
9154 /* If this is a commutative operation, and ARG0 is a constant, move it
9155 to ARG1 to reduce the number of tests below. */
9160 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9161 to ARG1 to reduce the number of tests below. */
9170 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9172 First check for cases where an arithmetic operation is applied to a
9173 compound, conditional, or comparison operation. Push the arithmetic
9174 operation inside the compound or conditional to see if any folding
9175 can then be done. Convert comparison to conditional for this purpose.
9176 The also optimizes non-constant cases that used to be done in
9177 expand_expr.
9179 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9180 one of the operands is a comparison and the other is a comparison, a
9181 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9182 code below would make the expression more complex. Change it to a
9183 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9184 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9197 {
9201 boolean_type_node,
9209 }
9213 {
9215 {
9220 tem);
9221 }
9223 {
9228 tem);
9229 }
9234 {
9240 }
9245 {
9251 }
9252 }
9255 {
9257 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9260 {
9266 }
9268 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9271 {
9272 tree base;
9273 HOST_WIDE_INT coffset;
9282 }
9287 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9293 arg1),
9295 arg0)));
9301 {
9302 /* X + (X / CST) * -CST is X % CST. */
9307 {
9316 cst0));
9317 }
9318 }
9320 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9321 one. Make sure the type is not saturating and has the signedness of
9322 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9323 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9330 {
9334 }
9337 {
9338 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9339 (plus (plus (mult) (mult)) (foo)) so that we can
9340 take advantage of the factoring cases below. */
9349 {
9355 else
9368 parg0),
9370 marg)),
9374 return
9380 parg1)));
9381 }
9382 }
9383 else
9384 {
9385 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9386 to __complex__ ( x, y ). This is not the same for SNaNs or
9387 if signed zeros are involved. */
9391 {
9398 {
9402 {
9408 }
9410 {
9416 }
9417 }
9418 }
9426 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9427 We associate floats only if the user has specified
9428 -fassociative-math. */
9432 {
9437 {
9438 tree tree0;
9441 }
9442 }
9443 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9444 We associate floats only if the user has specified
9445 -fassociative-math. */
9449 {
9454 {
9455 tree tree0;
9458 }
9459 }
9460 }
9462 bit_rotate:
9463 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9464 is a rotate of A by C1 bits. */
9465 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9466 is a rotate of A by B bits. */
9467 {
9469 tree rtype;
9478 /* Only create rotates in complete modes. Other cases are not
9479 expanded properly. */
9482 {
9496 {
9500 code0 == LSHIFT_EXPR
9504 }
9506 {
9514 element_precision
9518 return
9521 ? LROTATE_EXPR
9526 }
9528 {
9536 element_precision
9540 return fold_convert_loc
9543 ? LROTATE_EXPR
9547 }
9548 }
9549 }
9551 associate:
9552 /* In most languages, can't associate operations on floats through
9553 parentheses. Rather than remember where the parentheses were, we
9554 don't associate floats at all, unless the user has specified
9555 -fassociative-math.
9556 And, we need to make sure type is not saturating. */
9560 {
9566 /* Split both trees into variables, constants, and literals. Then
9567 associate each group together, the constants with literals,
9568 then the result with variables. This increases the chances of
9569 literals being recombined later and of generating relocatable
9570 expressions for the sum of a constant and literal. */
9576 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9580 /* With undefined overflow prefer doing association in a type
9581 which wraps on overflow, if that is one of the operand types. */
9584 {
9592 }
9594 /* With undefined overflow we can only associate constants with one
9595 variable, and constants whose association doesn't overflow. */
9598 {
9600 {
9606 {
9609 }
9616 {
9619 }
9625 /* The only case we can still associate with two variables
9626 is if they cancel out. */
9630 }
9631 }
9633 /* Only do something if we found more than two objects. Otherwise,
9634 nothing has changed and we risk infinite recursion. */
9640 {
9652 /* Preserve the MINUS_EXPR if the negative part of the literal is
9653 greater than the positive part. Otherwise, the multiplicative
9654 folding code (i.e extract_muldiv) may be fooled in case
9655 unsigned constants are subtracted, like in the following
9656 example: ((X*2 + 4) - 8U)/2. */
9658 {
9662 {
9666 }
9667 else
9668 {
9672 }
9673 }
9675 /* Don't introduce overflows through reassociation. */
9682 {
9684 return
9688 else
9689 {
9692 return
9696 }
9697 }
9700 return
9703 }
9704 }
9709 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9717 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9718 __complex__ ( x, -y ). This is not the same for SNaNs or if
9719 signed zeros are involved. */
9723 {
9730 {
9734 {
9736 arg1r ? arg1r
9741 }
9743 {
9747 arg1i ? arg1i
9750 }
9751 }
9752 }
9754 /* A - B -> A + (-B) if B is easily negatable. */
9758 /* Avoid this transformation if B is a positive REAL_CST. */
9766 /* Fold &a[i] - &a[j] to i-j. */
9771 {
9777 }
9780 && flag_unsafe_math_optimizations
9786 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9787 one. Make sure the type is not saturating and has the signedness of
9788 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9789 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9796 {
9800 }
9806 {
9807 /* Transform x * -C into -x * C if x is easily negatable. */
9821 {
9824 "occur when simplifying "
9826 WARN_STRICT_OVERFLOW_MISC);
9828 }
9830 /* Optimize z * conj(z) for integer complex numbers. */
9837 }
9838 else
9839 {
9840 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9841 This is not the same for NaNs or if signed zeros are
9842 involved. */
9848 {
9851 return
9857 return
9862 }
9864 /* Optimize z * conj(z) for floating point complex numbers.
9865 Guarded by flag_unsafe_math_optimizations as non-finite
9866 imaginary components don't produce scalar results. */
9875 }
9879 /* Canonicalize (X & C1) | C2. */
9883 {
9888 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9896 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9901 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9902 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9903 mode which allows further optimizations. */
9908 {
9912 {
9915 }
9916 }
9923 c3)),
9924 arg1);
9925 }
9927 /* See if this can be simplified into a rotate first. If that
9928 is unsuccessful continue in the association code. */
9932 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9940 /* See if this can be simplified into a rotate first. If that
9941 is unsuccessful continue in the association code. */
9945 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9950 {
9951 tree tem2;
9958 }
9959 /* Fold ~X & 1 as (X & 1) == 0. */
9963 {
9964 tree tem2;
9971 }
9972 /* Fold !X & 1 as X == 0. */
9975 {
9979 }
9981 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9982 multiple of 1 << CST. */
9984 {
9991 }
9993 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
9994 bits from CST2. */
9998 {
10006 {
10007 /* Avoid the transform if arg1 is a mask of some
10008 mode which allows further optimizations. */
10015 }
10016 }
10018 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10019 ((A & N) + B) & M -> (A + B) & M
10020 Similarly if (N & M) == 0,
10021 ((A | N) + B) & M -> (A + B) & M
10022 and for - instead of + (or unary - instead of +)
10023 and/or ^ instead of |.
10024 If B is constant and (B & M) == 0, fold into A & M. */
10026 {
10035 {
10038 wide_int cst0;
10040 /* Now we know that arg0 is (C + D) or (C - D) or
10041 -C and arg1 (M) is == (1LL << cst) - 1.
10042 Store C into PMOP[0] and D into PMOP[1]. */
10046 {
10049 }
10056 {
10066 {
10069 }
10072 /* If C or D is of the form (A & N) where
10073 (N & M) == M, or of the form (A | N) or
10074 (A ^ N) where (N & M) == 0, replace it with A. */
10078 /* If C or D is a N where (N & M) == 0, it can be
10079 omitted (assumed 0). */
10087 }
10089 /* Only build anything new if we optimized one or both arguments
10090 above. */
10094 {
10097 {
10098 /* Perform the operations in a type that has defined
10099 overflow behavior. */
10105 }
10110 {
10118 else
10120 }
10123 else
10126 /* TEM is now the new binary +, - or unary - replacement. */
10130 }
10131 }
10132 }
10134 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10137 {
10142 return
10144 }
10149 /* Don't touch a floating-point divide by zero unless the mode
10150 of the constant can represent infinity. */
10156 /* (-A) / (-B) -> A / B */
10168 /* Fall through */
10171 /* Simplify A / (B << N) where A and B are positive and B is
10172 a power of 2, to A >> (N + log2(B)). */
10177 {
10180 {
10188 WARN_STRICT_OVERFLOW_MISC);
10194 }
10195 }
10197 /* Fall through */
10205 /* Convert -A / -B to A / B when the type is signed and overflow is
10206 undefined. */
10210 {
10213 "when distributing negation across "
10215 WARN_STRICT_OVERFLOW_MISC);
10220 }
10224 {
10227 "when distributing negation across "
10229 WARN_STRICT_OVERFLOW_MISC);
10234 }
10236 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10237 operation, EXACT_DIV_EXPR.
10239 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10240 At one time others generated faster code, it's not clear if they do
10241 after the last round to changes to the DIV code in expmed.c. */
10252 {
10256 WARN_STRICT_OVERFLOW_MISC);
10258 }
10270 {
10274 WARN_STRICT_OVERFLOW_MISC);
10276 }
10284 /* Since negative shift count is not well-defined,
10285 don't try to compute it in the compiler. */
10291 /* If we have a rotate of a bit operation with the rotate count and
10292 the second operand of the bit operation both constant,
10293 permute the two operations. */
10299 {
10307 }
10309 /* Two consecutive rotates adding up to the some integer
10310 multiple of the precision of the type can be ignored. */
10325 /* Note that the operands of this must be ints
10326 and their values must be 0 or 1.
10327 ("true" is a fixed value perhaps depending on the language.) */
10328 /* If first arg is constant zero, return it. */
10331 /* FALLTHRU */
10333 /* If either arg is constant true, drop it. */
10337 /* Preserve sequence points. */
10340 /* If second arg is constant zero, result is zero, but first arg
10341 must be evaluated. */
10344 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10345 case will be handled here. */
10349 /* !X && X is always false. */
10353 /* X && !X is always false. */
10358 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10359 means A >= Y && A != MAX, but in this case we know that
10360 A < X <= MAX. */
10364 {
10372 }
10381 /* Note that the operands of this must be ints
10382 and their values must be 0 or true.
10383 ("true" is a fixed value perhaps depending on the language.) */
10384 /* If first arg is constant true, return it. */
10387 /* FALLTHRU */
10389 /* If either arg is constant zero, drop it. */
10393 /* Preserve sequence points. */
10396 /* If second arg is constant true, result is true, but we must
10397 evaluate first arg. */
10400 /* Likewise for first arg, but note this only occurs here for
10401 TRUTH_OR_EXPR. */
10405 /* !X || X is always true. */
10409 /* X || !X is always true. */
10414 /* (X && !Y) || (!X && Y) is X ^ Y */
10417 {
10434 }
10443 /* If the second arg is constant zero, drop it. */
10446 /* If the second arg is constant true, this is a logical inversion. */
10448 {
10451 }
10452 /* Identical arguments cancel to zero. */
10456 /* !X ^ X is always true. */
10461 /* X ^ !X is always true. */
10477 /* bool_var != 1 becomes !bool_var. */
10484 /* bool_var == 0 becomes !bool_var. */
10491 /* !exp != 0 becomes !exp */
10496 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10505 {
10511 }
10513 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10522 {
10528 }
10530 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10538 code == NE_EXPR
10542 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10550 code == NE_EXPR
10554 /* If this is an EQ or NE comparison with zero and ARG0 is
10555 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10556 two operations, but the latter can be done in one less insn
10557 on machines that have only two-operand insns or on which a
10558 constant cannot be the first operand. */
10561 {
10566 {
10573 arg1);
10574 }
10577 {
10584 arg1);
10585 }
10586 }
10588 /* If this is an NE or EQ comparison of zero against the result of a
10589 signed MOD operation whose second operand is a power of 2, make
10590 the MOD operation unsigned since it is simpler and equivalent. */
10598 {
10608 }
10610 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10611 C1 is a valid shift constant, and C2 is a power of two, i.e.
10612 a single bit. */
10616 == INTEGER_CST
10619 {
10624 /* Check for a valid shift count. */
10626 {
10630 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10631 can be rewritten as (X & (C2 << C1)) != 0. */
10633 {
10638 }
10639 /* Otherwise, for signed (arithmetic) shifts,
10640 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10641 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10645 /* Otherwise, of unsigned (logical) shifts,
10646 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10647 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10648 else
10652 arg000);
10653 }
10654 }
10656 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10657 Similarly for NE_EXPR. */
10661 {
10665 tree dandnotc
10668 notc);
10672 }
10674 /* If this is a comparison of a field, we may be able to simplify it. */
10677 /* Handle the constant case even without -O
10678 to make sure the warnings are given. */
10680 {
10684 }
10686 /* Optimize comparisons of strlen vs zero to a compare of the
10687 first character of the string vs zero. To wit,
10688 strlen(ptr) == 0 => *ptr == 0
10689 strlen(ptr) != 0 => *ptr != 0
10690 Other cases should reduce to one of these two (or a constant)
10691 due to the return value of strlen being unsigned. */
10694 {
10702 {
10707 }
10708 }
10710 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10711 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10715 {
10720 {
10722 {
10725 }
10728 }
10729 }
10731 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10732 (X & C) == 0 when C is a single bit. */
10737 {
10744 arg1));
10745 }
10747 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10748 constant C is a power of two, i.e. a single bit. */
10755 {
10759 }
10761 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10762 when is C is a power of two, i.e. a single bit. */
10769 {
10775 }
10779 {
10782 }
10784 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10787 {
10800 arg01),
10809 arg01),
10818 arg00),
10827 arg00),
10829 }
10833 {
10840 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10841 operand_equal_p guarantees no side-effects so we don't need
10842 to use omit_one_operand on Z. */
10846 arg10));
10850 arg11));
10854 arg10));
10858 arg11));
10860 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10863 {
10869 }
10870 }
10872 /* Attempt to simplify equality/inequality comparisons of complex
10873 values. Only lower the comparison if the result is known or
10874 can be simplified to a single scalar comparison. */
10879 {
10884 {
10887 }
10888 else
10889 {
10892 }
10895 {
10898 }
10899 else
10900 {
10903 }
10907 {
10909 {
10914 }
10915 else
10916 {
10921 }
10922 }
10926 {
10928 {
10933 }
10934 else
10935 {
10940 }
10941 }
10942 }
10954 /* Transform comparisons of the form X +- C CMP X. */
10961 {
10968 else
10971 /* (X - c) > X becomes false. */
10975 {
10979 "occur when assuming that (X - c) > X "
10981 WARN_STRICT_OVERFLOW_ALL);
10983 }
10985 /* Likewise (X + c) < X becomes false. */
10989 {
10993 "occur when assuming that "
10995 WARN_STRICT_OVERFLOW_ALL);
10997 }
10999 /* Convert (X - c) <= X to true. */
11004 {
11008 "occur when assuming that "
11010 WARN_STRICT_OVERFLOW_ALL);
11012 }
11014 /* Convert (X + c) >= X to true. */
11019 {
11023 "occur when assuming that "
11025 WARN_STRICT_OVERFLOW_ALL);
11027 }
11030 {
11031 /* Convert X + c > X and X - c < X to true for integers. */
11035 {
11038 "not occur when assuming that "
11040 WARN_STRICT_OVERFLOW_ALL);
11042 }
11047 {
11050 "not occur when assuming that "
11052 WARN_STRICT_OVERFLOW_ALL);
11054 }
11056 /* Convert X + c <= X and X - c >= X to false for integers. */
11060 {
11063 "not occur when assuming that "
11065 WARN_STRICT_OVERFLOW_ALL);
11067 }
11072 {
11075 "not occur when assuming that "
11077 WARN_STRICT_OVERFLOW_ALL);
11079 }
11080 }
11081 }
11083 /* If we are comparing an ABS_EXPR with a constant, we can
11084 convert all the cases into explicit comparisons, but they may
11085 well not be faster than doing the ABS and one comparison.
11086 But ABS (X) <= C is a range comparison, which becomes a subtraction
11087 and a comparison, and is probably faster. */
11101 /* Convert ABS_EXPR<x> >= 0 to true. */
11108 {
11111 "when simplifying comparison of "
11113 WARN_STRICT_OVERFLOW_CONDITIONAL);
11116 arg0);
11117 }
11119 /* Convert ABS_EXPR<x> < 0 to false. */
11124 {
11127 "when simplifying comparison of "
11129 WARN_STRICT_OVERFLOW_CONDITIONAL);
11132 arg0);
11133 }
11135 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11136 and similarly for >= into !=. */
11146 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11147 otherwise Y might be >= # of bits in X's type and thus e.g.
11148 (unsigned char) (1 << Y) for Y 15 might be 0.
11149 If the cast is widening, then 1 << Y should have unsigned type,
11150 otherwise if Y is number of bits in the signed shift type minus 1,
11151 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11152 31 might be 0xffffffff80000000. */
11163 {
11169 }
11181 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11182 {
11194 }
11199 /* When pedantic, a compound expression can be neither an lvalue
11200 nor an integer constant expression. */
11203 /* Don't let (0, 0) be null pointer constant. */
11209 /* An ASSERT_EXPR should never be passed to fold_binary. */
11215 }
11217 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11218 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11219 of GOTO_EXPR. */
11221 static tree
11223 {
11225 {
11232 /* fall through */
11236 }
11237 }
11239 /* Return whether the sub-tree ST contains a label which is accessible from
11240 outside the sub-tree. */
11242 static bool
11244 {
11245 return
11247 }
11249 /* Fold a ternary expression of code CODE and type TYPE with operands
11250 OP0, OP1, and OP2. Return the folded expression if folding is
11251 successful. Otherwise, return NULL_TREE. */
11253 tree
11256 {
11257 tree tem;
11264 /* If this is a commutative operation, and OP0 is a constant, move it
11265 to OP1 to reduce the number of tests below. */
11274 /* Strip any conversions that don't change the mode. This is safe
11275 for every expression, except for a comparison expression because
11276 its signedness is derived from its operands. So, in the latter
11277 case, only strip conversions that don't change the signedness.
11279 Note that this is done as an internal manipulation within the
11280 constant folder, in order to find the simplest representation of
11281 the arguments so that their form can be studied. In any cases,
11282 the appropriate type conversions should be put back in the tree
11283 that will get out of the constant folder. */
11285 {
11288 }
11291 {
11294 }
11297 {
11300 }
11303 {
11307 {
11313 }
11318 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11319 so all simple results must be passed through pedantic_non_lvalue. */
11321 {
11324 /* Only optimize constant conditions when the selected branch
11325 has the same type as the COND_EXPR. This avoids optimizing
11326 away "c ? x : throw", where the throw has a void type.
11327 Avoid throwing away that operand which contains label. */
11334 }
11336 {
11341 {
11346 {
11354 }
11358 }
11359 }
11361 /* If we have A op B ? A : C, we may be able to convert this to a
11362 simpler expression, depending on the operation and the values
11363 of B and C. Signed zeros prevent all of these transformations,
11364 for reasons given above each one.
11366 Also try swapping the arguments and inverting the conditional. */
11371 {
11375 }
11379 op2,
11382 {
11386 {
11390 }
11391 }
11393 /* If the second operand is simpler than the third, swap them
11394 since that produces better jump optimization results. */
11397 {
11399 /* See if this can be inverted. If it can't, possibly because
11400 it was a floating-point inequality comparison, don't do
11401 anything. */
11405 }
11407 /* Convert A ? 1 : 0 to simply A. */
11412 /* If we try to convert OP0 to our type, the
11413 call to fold will try to move the conversion inside
11414 a COND, which will recurse. In that case, the COND_EXPR
11415 is probably the best choice, so leave it alone. */
11419 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11420 over COND_EXPR in cases such as floating point comparisons. */
11429 arg0)));
11431 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11436 {
11437 /* sign_bit_p looks through both zero and sign extensions,
11438 but for this optimization only sign extensions are
11439 usable. */
11442 {
11445 {
11448 }
11450 }
11451 /* sign_bit_p only checks ARG1 bits within A's precision.
11452 If <sign bit of A> has wider type than A, bits outside
11453 of A's precision in <sign bit of A> need to be checked.
11454 If they are all 0, this optimization needs to be done
11455 in unsigned A's type, if they are all 1 in signed A's type,
11456 otherwise this can't be done. */
11462 {
11464 tree tem_type;
11477 {
11480 }
11482 {
11485 }
11486 else
11488 }
11491 return
11497 arg1)));
11498 }
11500 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11501 already handled above. */
11506 {
11515 }
11517 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11518 is probably obsolete because the first operand should be a
11519 truth value (that's why we have the two cases above), but let's
11520 leave it in until we can confirm this for all front-ends. */
11532 /* Disable the transformations below for vectors, since
11533 fold_binary_op_with_conditional_arg may undo them immediately,
11534 yielding an infinite loop. */
11538 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11547 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11552 {
11554 /* Only perform transformation if ARG0 is easily inverted. */
11558 ? BIT_IOR_EXPR
11561 arg1);
11562 }
11564 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11569 {
11571 /* Only perform transformation if ARG0 is easily inverted. */
11577 op2);
11578 }
11580 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11592 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11593 of fold_ternary on them. */
11601 {
11611 {
11616 {
11624 }
11625 }
11626 }
11628 /* On constants we can use native encode/interpret to constant
11629 fold (nearly) all BIT_FIELD_REFs. */
11633 {
11636 /* Limit us to a reasonable amount of work. To relax the
11637 other limitations we need bit-shifting of the buffer
11638 and rounding up the size. */
11642 {
11644 unsigned HOST_WIDE_INT len
11649 {
11654 }
11655 }
11656 }
11661 /* For integers we can decompose the FMA if possible. */
11673 {
11689 {
11694 /* Make sure that the perm value is in an acceptable
11695 range. */
11704 else
11709 }
11712 {
11717 }
11722 {
11727 }
11733 {
11737 }
11742 /* Some targets are deficient and fail to expand a single
11743 argument permutation while still allowing an equivalent
11744 2-argument version. */
11748 {
11751 }
11754 {
11761 }
11765 }
11769 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11772 {
11778 wide_int tem2
11782 }
11787 {
11789 unsigned HOST_WIDE_INT elsize
11792 {
11796 else
11797 {
11803 }
11804 }
11805 }
11811 }
11813 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11814 of an array (or vector). */
11816 tree
11818 {
11823 {
11826 {
11827 /* Static constructors for variably sized objects makes no sense. */
11831 }
11832 }
11843 offset_int max_index;
11848 {
11849 /* Array constructor might explicitly set index, or specify a range,
11850 or leave index NULL meaning that it is next index after previous
11851 one. */
11853 {
11856 else
11857 {
11861 }
11862 }
11863 else
11864 {
11870 }
11872 /* Do we have match? */
11876 }
11878 }
11880 /* Perform constant folding and related simplification of EXPR.
11881 The related simplifications include x*1 => x, x*0 => 0, etc.,
11882 and application of the associative law.
11883 NOP_EXPR conversions may be removed freely (as long as we
11884 are careful not to change the type of the overall expression).
11885 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11886 but we can constant-fold them if they have constant operands. */
11888 #ifdef ENABLE_FOLD_CHECKING
11889 # define fold(x) fold_1 (x)
11891 static
11892 #endif
11893 tree
11895 {
11899 tree tem;
11902 /* Return right away if a constant. */
11906 /* CALL_EXPR-like objects with variable numbers of operands are
11907 treated specially. */
11909 {
11911 {
11914 }
11916 }
11919 {
11924 {
11942 }
11943 }
11946 {
11948 {
11955 {
11960 }
11963 }
11965 /* Return a VECTOR_CST if possible. */
11967 {
11973 tree val;
11979 }
11987 }
11989 #ifdef ENABLE_FOLD_CHECKING
11990 #undef fold
11997 /* When --enable-checking=fold, compute a digest of expr before
11998 and after actual fold call to see if fold did not accidentally
11999 change original expr. */
12001 tree
12003 {
12004 tree ret;
12024 }
12026 void
12028 {
12039 }
12041 static void
12043 {
12045 }
12047 static void
12050 {
12056 recursive_label:
12066 {
12067 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12072 }
12080 {
12081 /* Allow these fields to be modified. */
12082 tree tmp;
12091 {
12094 }
12095 }
12106 {
12109 {
12124 }
12128 {
12141 }
12158 {
12164 }
12167 {
12169 {
12172 }
12174 }
12185 {
12188 }
12198 }
12199 }
12201 /* Helper function for outputting the checksum of a tree T. When
12202 debugging with gdb, you can "define mynext" to be "next" followed
12203 by "call debug_fold_checksum (op0)", then just trace down till the
12204 outputs differ. */
12206 DEBUG_FUNCTION void
12208 {
12223 }
12225 #endif
12227 /* Fold a unary tree expression with code CODE of type TYPE with an
12228 operand OP0. LOC is the location of the resulting expression.
12229 Return a folded expression if successful. Otherwise, return a tree
12230 expression with code CODE of type TYPE with an operand OP0. */
12232 tree
12235 {
12236 tree tem;
12237 #ifdef ENABLE_FOLD_CHECKING
12246 #endif
12252 #ifdef ENABLE_FOLD_CHECKING
12259 #endif
12261 }
12263 /* Fold a binary tree expression with code CODE of type TYPE with
12264 operands OP0 and OP1. LOC is the location of the resulting
12265 expression. Return a folded expression if successful. Otherwise,
12266 return a tree expression with code CODE of type TYPE with operands
12267 OP0 and OP1. */
12269 tree
12272 MEM_STAT_DECL)
12273 {
12274 tree tem;
12275 #ifdef ENABLE_FOLD_CHECKING
12292 #endif
12298 #ifdef ENABLE_FOLD_CHECKING
12313 #endif
12315 }
12317 /* Fold a ternary tree expression with code CODE of type TYPE with
12318 operands OP0, OP1, and OP2. Return a folded expression if
12319 successful. Otherwise, return a tree expression with code CODE of
12320 type TYPE with operands OP0, OP1, and OP2. */
12322 tree
12325 {
12326 tree tem;
12327 #ifdef ENABLE_FOLD_CHECKING
12351 #endif
12358 #ifdef ENABLE_FOLD_CHECKING
12381 #endif
12383 }
12385 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12386 arguments in ARGARRAY, and a null static chain.
12387 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12388 of type TYPE from the given operands as constructed by build_call_array. */
12390 tree
12393 {
12394 tree tem;
12395 #ifdef ENABLE_FOLD_CHECKING
12414 #endif
12420 #ifdef ENABLE_FOLD_CHECKING
12436 #endif
12438 }
12440 /* Perform constant folding and related simplification of initializer
12441 expression EXPR. These behave identically to "fold_buildN" but ignore
12442 potential run-time traps and exceptions that fold must preserve. */
12444 #define START_FOLD_INIT \
12445 int saved_signaling_nans = flag_signaling_nans;\
12446 int saved_trapping_math = flag_trapping_math;\
12447 int saved_rounding_math = flag_rounding_math;\
12448 int saved_trapv = flag_trapv;\
12449 int saved_folding_initializer = folding_initializer;\
12450 flag_signaling_nans = 0;\
12451 flag_trapping_math = 0;\
12452 flag_rounding_math = 0;\
12453 flag_trapv = 0;\
12454 folding_initializer = 1;
12456 #define END_FOLD_INIT \
12457 flag_signaling_nans = saved_signaling_nans;\
12458 flag_trapping_math = saved_trapping_math;\
12459 flag_rounding_math = saved_rounding_math;\
12460 flag_trapv = saved_trapv;\
12461 folding_initializer = saved_folding_initializer;
12463 tree
12466 {
12467 tree result;
12468 START_FOLD_INIT;
12472 END_FOLD_INIT;
12474 }
12476 tree
12479 {
12480 tree result;
12481 START_FOLD_INIT;
12485 END_FOLD_INIT;
12487 }
12489 tree
12492 {
12493 tree result;
12494 START_FOLD_INIT;
12498 END_FOLD_INIT;
12500 }
12502 #undef START_FOLD_INIT
12503 #undef END_FOLD_INIT
12505 /* Determine if first argument is a multiple of second argument. Return 0 if
12506 it is not, or we cannot easily determined it to be.
12508 An example of the sort of thing we care about (at this point; this routine
12509 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12510 fold cases do now) is discovering that
12512 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12514 is a multiple of
12516 SAVE_EXPR (J * 8)
12518 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12520 This code also handles discovering that
12522 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12524 is a multiple of 8 so we don't have to worry about dealing with a
12525 possible remainder.
12527 Note that we *look* inside a SAVE_EXPR only to determine how it was
12528 calculated; it is not safe for fold to do much of anything else with the
12529 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12530 at run time. For example, the latter example above *cannot* be implemented
12531 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12532 evaluation time of the original SAVE_EXPR is not necessarily the same at
12533 the time the new expression is evaluated. The only optimization of this
12534 sort that would be valid is changing
12536 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12538 divided by 8 to
12540 SAVE_EXPR (I) * SAVE_EXPR (J)
12542 (where the same SAVE_EXPR (J) is used in the original and the
12543 transformed version). */
12545 int
12547 {
12558 {
12560 /* Bitwise and provides a power of two multiple. If the mask is
12561 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12564 /* FALLTHRU */
12571 /* It is impossible to prove if op0 - op1 is multiple of bottom
12572 precisely, so be conservative here checking if both op0 and op1
12573 are multiple of bottom. Note we check the second operand first
12574 since it's usually simpler. */
12579 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12580 as op0 - 3 if the expression has unsigned type. For example,
12581 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12591 {
12593 /* const_binop may not detect overflow correctly,
12594 so check for it explicitly here. */
12598 size_one_node,
12599 op1)))
12602 }
12606 /* Can't handle conversions from non-integral or wider integral type. */
12612 /* fall through */
12629 SIGNED);
12635 {
12638 /* Check for special cases to see if top is defined as multiple
12639 of bottom:
12641 top = (X & ~(bottom - 1) ; bottom is power of 2
12643 or
12645 Y = X % bottom
12646 top = X - Y. */
12665 }
12667 /* fall through */
12671 }
12672 }
12674 #define tree_expr_nonnegative_warnv_p(X, Y) \
12677 #define RECURSE(X) \
12678 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12680 /* Return true if CODE or TYPE is known to be non-negative. */
12682 static bool
12684 {
12687 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12688 have a signed:1 type (where the value is -1 and 0). */
12691 }
12693 /* Return true if (CODE OP0) is known to be non-negative. If the return
12694 value is based on the assumption that signed overflow is undefined,
12695 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12696 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12698 bool
12701 {
12706 {
12708 /* We can't return 1 if flag_wrapv is set because
12709 ABS_EXPR<INT_MIN> = INT_MIN. */
12713 {
12716 }
12724 CASE_CONVERT:
12725 {
12730 {
12734 {
12738 }
12739 }
12741 {
12747 }
12748 }
12753 }
12755 /* We don't know sign of `t', so be conservative and return false. */
12757 }
12759 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12760 value is based on the assumption that signed overflow is undefined,
12761 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12762 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12764 bool
12768 {
12773 {
12779 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12780 both unsigned and at least 2 bits shorter than the result. */
12784 {
12789 {
12793 }
12794 }
12799 {
12800 /* x * x is always non-negative for floating point x
12801 or without overflow. */
12804 {
12809 }
12810 }
12812 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12813 both unsigned and their total bits is shorter than the result. */
12817 {
12836 {
12846 }
12847 }
12874 }
12876 /* We don't know sign of `t', so be conservative and return false. */
12878 }
12880 /* Return true if T is known to be non-negative. If the return
12881 value is based on the assumption that signed overflow is undefined,
12882 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12883 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12885 bool
12887 {
12892 {
12906 /* Limit the depth of recursion to avoid quadratic behavior.
12907 This is expected to catch almost all occurrences in practice.
12908 If this code misses important cases that unbounded recursion
12909 would not, passes that need this information could be revised
12910 to provide it through dataflow propagation. */
12918 }
12919 }
12921 /* Return true if T is known to be non-negative. If the return
12922 value is based on the assumption that signed overflow is undefined,
12923 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12924 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12926 bool
12929 {
12931 {
12932 CASE_CFN_ACOS:
12933 CASE_CFN_ACOSH:
12934 CASE_CFN_CABS:
12935 CASE_CFN_COSH:
12936 CASE_CFN_ERFC:
12937 CASE_CFN_EXP:
12938 CASE_CFN_EXP10:
12939 CASE_CFN_EXP2:
12940 CASE_CFN_FABS:
12941 CASE_CFN_FDIM:
12942 CASE_CFN_HYPOT:
12943 CASE_CFN_POW10:
12944 CASE_CFN_FFS:
12945 CASE_CFN_PARITY:
12946 CASE_CFN_POPCOUNT:
12947 CASE_CFN_CLZ:
12948 CASE_CFN_CLRSB:
12951 /* Always true. */
12954 CASE_CFN_SQRT:
12955 /* sqrt(-0.0) is -0.0. */
12960 CASE_CFN_ASINH:
12961 CASE_CFN_ATAN:
12962 CASE_CFN_ATANH:
12963 CASE_CFN_CBRT:
12964 CASE_CFN_CEIL:
12965 CASE_CFN_ERF:
12966 CASE_CFN_EXPM1:
12967 CASE_CFN_FLOOR:
12968 CASE_CFN_FMOD:
12969 CASE_CFN_FREXP:
12970 CASE_CFN_ICEIL:
12971 CASE_CFN_IFLOOR:
12972 CASE_CFN_IRINT:
12973 CASE_CFN_IROUND:
12974 CASE_CFN_LCEIL:
12975 CASE_CFN_LDEXP:
12976 CASE_CFN_LFLOOR:
12977 CASE_CFN_LLCEIL:
12978 CASE_CFN_LLFLOOR:
12979 CASE_CFN_LLRINT:
12980 CASE_CFN_LLROUND:
12981 CASE_CFN_LRINT:
12982 CASE_CFN_LROUND:
12983 CASE_CFN_MODF:
12984 CASE_CFN_NEARBYINT:
12985 CASE_CFN_RINT:
12986 CASE_CFN_ROUND:
12987 CASE_CFN_SCALB:
12988 CASE_CFN_SCALBLN:
12989 CASE_CFN_SCALBN:
12990 CASE_CFN_SIGNBIT:
12991 CASE_CFN_SIGNIFICAND:
12992 CASE_CFN_SINH:
12993 CASE_CFN_TANH:
12994 CASE_CFN_TRUNC:
12995 /* True if the 1st argument is nonnegative. */
12998 CASE_CFN_FMAX:
12999 /* True if the 1st OR 2nd arguments are nonnegative. */
13002 CASE_CFN_FMIN:
13003 /* True if the 1st AND 2nd arguments are nonnegative. */
13006 CASE_CFN_COPYSIGN:
13007 /* True if the 2nd argument is nonnegative. */
13010 CASE_CFN_POWI:
13011 /* True if the 1st argument is nonnegative or the second
13012 argument is an even integer. */
13018 CASE_CFN_POW:
13019 /* True if the 1st argument is nonnegative or the second
13020 argument is an even integer valued real. */
13022 {
13023 REAL_VALUE_TYPE c;
13024 HOST_WIDE_INT n;
13029 {
13030 REAL_VALUE_TYPE cint;
13034 }
13035 }
13040 }
13042 }
13044 /* Return true if T is known to be non-negative. If the return
13045 value is based on the assumption that signed overflow is undefined,
13046 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13047 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13049 static bool
13051 {
13057 {
13059 {
13063 /* If the initializer is non-void, then it's a normal expression
13064 that will be assigned to the slot. */
13068 /* Otherwise, the initializer sets the slot in some way. One common
13069 way is an assignment statement at the end of the initializer. */
13071 {
13079 else
13081 }
13087 }
13090 {
13096 arg0,
13097 arg1,
13099 }
13112 }
13113 }
13115 #undef RECURSE
13116 #undef tree_expr_nonnegative_warnv_p
13118 /* Return true if T is known to be non-negative. If the return
13119 value is based on the assumption that signed overflow is undefined,
13120 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13121 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13123 bool
13125 {
13132 {
13154 }
13157 {
13183 }
13184 }
13186 /* Return true if `t' is known to be non-negative. Handle warnings
13187 about undefined signed overflow. */
13189 bool
13191 {
13198 "determining that expression is always "
13200 WARN_STRICT_OVERFLOW_MISC);
13202 }
13205 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13206 For floating point we further ensure that T is not denormal.
13207 Similar logic is present in nonzero_address in rtlanal.h.
13209 If the return value is based on the assumption that signed overflow
13210 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13211 change *STRICT_OVERFLOW_P. */
13213 bool
13216 {
13218 {
13221 strict_overflow_p);
13224 {
13230 strict_overflow_p));
13231 }
13236 strict_overflow_p);
13240 }
13243 }
13245 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13246 For floating point we further ensure that T is not denormal.
13247 Similar logic is present in nonzero_address in rtlanal.h.
13249 If the return value is based on the assumption that signed overflow
13250 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13251 change *STRICT_OVERFLOW_P. */
13253 bool
13255 tree type,
13256 tree op0,
13258 {
13261 {
13265 {
13266 /* With the presence of negative values it is hard
13267 to say something. */
13274 /* One of operands must be positive and the other non-negative. */
13275 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13276 overflows, on a twos-complement machine the sum of two
13277 nonnegative numbers can never be zero. */
13279 strict_overflow_p)
13281 strict_overflow_p));
13282 }
13287 {
13289 strict_overflow_p)
13291 strict_overflow_p))
13292 {
13295 }
13296 }
13305 {
13308 }
13315 {
13319 /* When both operands are nonzero, then MAX must be too. */
13321 strict_overflow_p))
13324 /* MAX where operand 0 is positive is positive. */
13326 strict_overflow_p);
13327 }
13328 /* MAX where operand 1 is positive is positive. */
13333 {
13337 }
13342 strict_overflow_p)
13344 strict_overflow_p));
13348 }
13351 }
13353 /* Return true when T is an address and is known to be nonzero.
13354 For floating point we further ensure that T is not denormal.
13355 Similar logic is present in nonzero_address in rtlanal.h.
13357 If the return value is based on the assumption that signed overflow
13358 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13359 change *STRICT_OVERFLOW_P. */
13361 bool
13363 {
13366 {
13371 {
13383 /* For objects in symbol table check if we know they are non-zero.
13384 Don't do anything for variables and functions before symtab is built;
13385 it is quite possible that they will be declared weak later. */
13390 /* Constants are never weak. */
13395 }
13403 {
13407 }
13412 }
13414 }
13416 #define integer_valued_real_p(X) \
13419 #define RECURSE(X) \
13420 ((integer_valued_real_p) (X, depth + 1))
13422 /* Return true if the floating point result of (CODE OP0) has an
13423 integer value. We also allow +Inf, -Inf and NaN to be considered
13424 integer values. Return false for signaling NaN.
13426 DEPTH is the current nesting depth of the query. */
13428 bool
13430 {
13432 {
13439 CASE_CONVERT:
13440 {
13447 }
13451 }
13453 }
13455 /* Return true if the floating point result of (CODE OP0 OP1) has an
13456 integer value. We also allow +Inf, -Inf and NaN to be considered
13457 integer values. Return false for signaling NaN.
13459 DEPTH is the current nesting depth of the query. */
13461 bool
13463 {
13465 {
13475 }
13477 }
13479 /* Return true if the floating point result of calling FNDECL with arguments
13480 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13481 considered integer values. Return false for signaling NaN. If FNDECL
13482 takes fewer than 2 arguments, the remaining ARGn are null.
13484 DEPTH is the current nesting depth of the query. */
13486 bool
13488 {
13490 {
13491 CASE_CFN_CEIL:
13492 CASE_CFN_FLOOR:
13493 CASE_CFN_NEARBYINT:
13494 CASE_CFN_RINT:
13495 CASE_CFN_ROUND:
13496 CASE_CFN_TRUNC:
13499 CASE_CFN_FMIN:
13500 CASE_CFN_FMAX:
13505 }
13507 }
13509 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13510 has an integer value. We also allow +Inf, -Inf and NaN to be
13511 considered integer values. Return false for signaling NaN.
13513 DEPTH is the current nesting depth of the query. */
13515 bool
13517 {
13519 {
13527 /* Limit the depth of recursion to avoid quadratic behavior.
13528 This is expected to catch almost all occurrences in practice.
13529 If this code misses important cases that unbounded recursion
13530 would not, passes that need this information could be revised
13531 to provide it through dataflow propagation. */
13535 depth));
13539 }
13541 }
13543 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13544 has an integer value. We also allow +Inf, -Inf and NaN to be
13545 considered integer values. Return false for signaling NaN.
13547 DEPTH is the current nesting depth of the query. */
13549 static bool
13551 {
13553 {
13564 }
13566 }
13568 #undef RECURSE
13569 #undef integer_valued_real_p
13571 /* Return true if the floating point expression T has an integer value.
13572 We also allow +Inf, -Inf and NaN to be considered integer values.
13573 Return false for signaling NaN.
13575 DEPTH is the current nesting depth of the query. */
13577 bool
13579 {
13585 {
13601 }
13604 {
13610 {
13619 }
13623 }
13624 }
13626 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13627 attempt to fold the expression to a constant without modifying TYPE,
13628 OP0 or OP1.
13630 If the expression could be simplified to a constant, then return
13631 the constant. If the expression would not be simplified to a
13632 constant, then return NULL_TREE. */
13634 tree
13636 {
13639 }
13641 /* Given the components of a unary expression CODE, TYPE and OP0,
13642 attempt to fold the expression to a constant without modifying
13643 TYPE or OP0.
13645 If the expression could be simplified to a constant, then return
13646 the constant. If the expression would not be simplified to a
13647 constant, then return NULL_TREE. */
13649 tree
13651 {
13654 }
13656 /* If EXP represents referencing an element in a constant string
13657 (either via pointer arithmetic or array indexing), return the
13658 tree representing the value accessed, otherwise return NULL. */
13660 tree
13662 {
13666 {
13668 tree index;
13669 tree string;
13674 else
13675 {
13679 /* Optimize the special-case of a zero lower bound.
13681 We convert the low_bound to sizetype to avoid some problems
13682 with constant folding. (E.g. suppose the lower bound is 1,
13683 and its mode is QI. Without the conversion,l (ARRAY
13684 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13685 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13691 }
13704 }
13706 }
13708 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13709 an integer constant, real, or fixed-point constant.
13711 TYPE is the type of the result. */
13713 static tree
13715 {
13719 {
13721 {
13728 }
13735 {
13736 FIXED_VALUE_TYPE f;
13741 /* Propagate overflow flags. */
13745 }
13749 }
13752 }
13754 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13755 an integer constant or real constant.
13757 TYPE is the type of the result. */
13759 tree
13761 {
13765 {
13767 {
13768 /* If the value is unsigned or non-negative, then the absolute value
13769 is the same as the ordinary value. */
13773 /* If the value is negative, then the absolute value is
13774 its negation. */
13775 else
13776 {
13781 }
13782 }
13788 else
13794 }
13797 }
13799 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13800 constant. TYPE is the type of the result. */
13802 static tree
13804 {
13808 }
13810 /* Given CODE, a relational operator, the target type, TYPE and two
13811 constant operands OP0 and OP1, return the result of the
13812 relational operation. If the result is not a compile time
13813 constant, then return NULL_TREE. */
13815 static tree
13817 {
13820 /* From here on, the only cases we handle are when the result is
13821 known to be a constant. */
13824 {
13828 /* Handle the cases where either operand is a NaN. */
13830 {
13832 {
13860 }
13863 }
13866 }
13869 {
13873 }
13875 /* Handle equality/inequality of complex constants. */
13877 {
13888 else
13890 }
13893 {
13895 {
13896 /* Have vector comparison with scalar boolean result. */
13900 {
13908 }
13910 }
13917 {
13929 }
13932 }
13934 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13936 To compute GT, swap the arguments and do LT.
13937 To compute GE, do LT and invert the result.
13938 To compute LE, swap the arguments, do LT and invert the result.
13939 To compute NE, do EQ and invert the result.
13941 Therefore, the code below must handle only EQ and LT. */
13944 {
13947 }
13949 /* Note that it is safe to invert for real values here because we
13950 have already handled the one case that it matters. */
13954 {
13957 }
13959 /* Compute a result for LT or EQ if args permit;
13960 Otherwise return T. */
13962 {
13965 else
13967 }
13968 else
13974 }
13976 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13977 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13978 itself. */
13980 tree
13982 {
13983 /* If the expression does not have side effects then we don't have to wrap
13984 it with a cleanup point expression. */
13988 /* If the expression is a return, check to see if the expression inside the
13989 return has no side effects or the right hand side of the modify expression
13990 inside the return. If either don't have side effects set we don't need to
13991 wrap the expression in a cleanup point expression. Note we don't check the
13992 left hand side of the modify because it should always be a return decl. */
13994 {
14001 }
14004 }
14006 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14007 of an indirection through OP0, or NULL_TREE if no simplification is
14008 possible. */
14010 tree
14012 {
14014 tree subtype;
14023 {
14026 /* *&CONST_DECL -> to the value of the const decl. */
14029 /* *&p => p; make sure to handle *&"str"[cst] here. */
14031 {
14035 else
14037 }
14038 /* *(foo *)&fooarray => fooarray[0] */
14041 && (!in_gimple_form
14043 {
14053 }
14054 /* *(foo *)&complexfoo => __real__ complexfoo */
14058 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14061 {
14065 }
14066 }
14070 {
14076 {
14077 tree op00type;
14081 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14084 {
14086 unsigned HOST_WIDE_INT max_offset
14091 {
14098 }
14099 }
14100 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14103 {
14107 }
14108 /* ((foo *)&fooarray)[1] => fooarray[1] */
14111 {
14121 }
14122 }
14123 }
14125 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14128 && (!in_gimple_form
14130 {
14131 tree type_domain;
14141 NULL_TREE);
14142 }
14145 }
14147 /* Builds an expression for an indirection through T, simplifying some
14148 cases. */
14150 tree
14152 {
14160 }
14162 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14164 tree
14166 {
14171 else
14173 }
14175 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14176 whose result is ignored. The type of the returned tree need not be
14177 the same as the original expression. */
14179 tree
14181 {
14187 {
14198 else
14204 {
14220 }
14225 }
14226 }
14228 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14230 tree
14232 {
14238 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14239 have to do anything. Only do this when we are not given a const,
14240 because in that case, this check is more expensive than just
14241 doing it. */
14243 {
14248 }
14250 /* If divisor is a power of two, simplify this to bit manipulation. */
14252 {
14254 {
14268 }
14269 else
14270 {
14271 tree t;
14277 }
14278 }
14279 else
14280 {
14285 }
14288 }
14290 /* Likewise, but round down. */
14292 tree
14294 {
14301 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14302 have to do anything. Only do this when we are not given a const,
14303 because in that case, this check is more expensive than just
14304 doing it. */
14306 {
14311 }
14313 /* If divisor is a power of two, simplify this to bit manipulation. */
14315 {
14316 tree t;
14320 }
14321 else
14322 {
14327 }
14330 }
14332 /* Returns the pointer to the base of the object addressed by EXP and
14333 extracts the information about the offset of the access, storing it
14334 to PBITPOS and POFFSET. */
14336 static tree
14339 {
14340 tree core;
14341 machine_mode mode;
14343 HOST_WIDE_INT bitsize;
14347 {
14352 }
14354 {
14360 {
14365 {
14368 }
14369 }
14370 }
14371 else
14372 {
14376 }
14379 }
14381 /* Returns true if addresses of E1 and E2 differ by a constant, false
14382 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14384 bool
14386 {
14400 {
14410 }
14412 {
14413 /* If only one of the offsets is non-constant, the difference cannot
14414 be a constant. */
14416 }
14417 else
14422 }
14424 /* Return OFF converted to a pointer offset type suitable as offset for
14425 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14426 tree
14428 {
14430 }
14432 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14433 tree
14435 {
14438 }
14440 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14441 tree
14443 {
14446 }
14448 /* Return a char pointer for a C string if it is a string constant
14449 or sum of string constant and integer constant. We only support
14450 string constants properly terminated with '\0' character.
14451 If STRLEN is a valid pointer, length (including terminating character)
14452 of returned string is stored to the argument. */
14456 {
14457 tree offset_node;
14468 {
14471 else
14473 }
14478 /* Support only properly null-terminated strings. */
14487 }
14489 #if CHECKING_P
14493 /* Helper functions for writing tests of folding trees. */
14495 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14497 static void
14499 tree constant)
14500 {
14502 }
14504 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14505 wrapping WRAPPED_EXPR. */
14507 static void
14509 tree wrapped_expr)
14510 {
14515 }
14517 /* Verify that various arithmetic binary operations are folded
14518 correctly. */
14520 static void
14522 {
14528 /* Addition. */
14529 /* 1 <-- (0 + 1) */
14531 one);
14533 one);
14535 /* (nonlvalue)x <-- (x + 0) */
14537 x);
14539 /* Subtraction. */
14540 /* 0 <-- (x - x) */
14542 zero);
14544 x);
14546 /* Multiplication. */
14547 /* 0 <-- (x * 0) */
14549 zero);
14551 /* (nonlvalue)x <-- (x * 1) */
14553 x);
14554 }
14556 /* Verify that various binary operations on vectors are folded
14557 correctly. */
14559 static void
14561 {
14567 /* Verify equality tests that return a scalar boolean result. */
14573 }
14575 /* Run all of the selftests within this file. */
14577 void
14579 {
14582 }