| blob | aac62f83321ea9fe1fe37e0981b3e12a1ee579f1 |
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. */
85 /* Nonzero if we are folding constants inside an initializer; zero
86 otherwise. */
89 /* The following constants represent a bit based encoding of GCC's
90 comparison operators. This encoding simplifies transformations
91 on relational comparison operators, such as AND and OR. */
109 };
142 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
143 Otherwise, return LOC. */
145 static location_t
147 {
150 }
152 /* Similar to protected_set_expr_location, but never modify x in place,
153 if location can and needs to be set, unshare it. */
157 {
163 {
166 }
168 }
169 \f
170 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
171 division and returns the quotient. Otherwise returns
172 NULL_TREE. */
174 tree
176 {
177 widest_int quo;
184 }
185 \f
186 /* This is nonzero if we should defer warnings about undefined
187 overflow. This facility exists because these warnings are a
188 special case. The code to estimate loop iterations does not want
189 to issue any warnings, since it works with expressions which do not
190 occur in user code. Various bits of cleanup code call fold(), but
191 only use the result if it has certain characteristics (e.g., is a
192 constant); that code only wants to issue a warning if the result is
193 used. */
197 /* If a warning about undefined overflow is deferred, this is the
198 warning. Note that this may cause us to turn two warnings into
199 one, but that is fine since it is sufficient to only give one
200 warning per expression. */
204 /* If a warning about undefined overflow is deferred, this is the
205 level at which the warning should be emitted. */
209 /* Start deferring overflow warnings. We could use a stack here to
210 permit nested calls, but at present it is not necessary. */
212 void
214 {
216 }
218 /* Stop deferring overflow warnings. If there is a pending warning,
219 and ISSUE is true, then issue the warning if appropriate. STMT is
220 the statement with which the warning should be associated (used for
221 location information); STMT may be NULL. CODE is the level of the
222 warning--a warn_strict_overflow_code value. This function will use
223 the smaller of CODE and the deferred code when deciding whether to
224 issue the warning. CODE may be zero to mean to always use the
225 deferred code. */
227 void
229 {
231 location_t locus;
236 {
242 }
253 /* Use the smallest code level when deciding to issue the
254 warning. */
263 else
266 }
268 /* Stop deferring overflow warnings, ignoring any deferred
269 warnings. */
271 void
273 {
275 }
277 /* Whether we are deferring overflow warnings. */
279 bool
281 {
283 }
285 /* This is called when we fold something based on the fact that signed
286 overflow is undefined. */
288 void
290 {
292 {
295 {
298 }
299 }
302 }
303 \f
304 /* Return true if the built-in mathematical function specified by CODE
305 is odd, i.e. -f(x) == f(-x). */
307 bool
309 {
311 {
312 CASE_CFN_ASIN:
313 CASE_CFN_ASINH:
314 CASE_CFN_ATAN:
315 CASE_CFN_ATANH:
316 CASE_CFN_CASIN:
317 CASE_CFN_CASINH:
318 CASE_CFN_CATAN:
319 CASE_CFN_CATANH:
320 CASE_CFN_CBRT:
321 CASE_CFN_CPROJ:
322 CASE_CFN_CSIN:
323 CASE_CFN_CSINH:
324 CASE_CFN_CTAN:
325 CASE_CFN_CTANH:
326 CASE_CFN_ERF:
327 CASE_CFN_LLROUND:
328 CASE_CFN_LROUND:
329 CASE_CFN_ROUND:
330 CASE_CFN_SIN:
331 CASE_CFN_SINH:
332 CASE_CFN_TAN:
333 CASE_CFN_TANH:
334 CASE_CFN_TRUNC:
337 CASE_CFN_LLRINT:
338 CASE_CFN_LRINT:
339 CASE_CFN_NEARBYINT:
340 CASE_CFN_RINT:
345 }
347 }
349 /* Check whether we may negate an integer constant T without causing
350 overflow. */
352 bool
354 {
355 tree type;
364 }
366 /* Determine whether an expression T can be cheaply negated using
367 the function negate_expr without introducing undefined overflow. */
369 static bool
371 {
372 tree type;
381 {
386 /* Check that -CST will not overflow type. */
399 /* We want to canonicalize to positive real constants. Pretend
400 that only negative ones can be easily negated. */
408 {
419 }
434 /* -(A + B) -> (-B) - A. */
437 /* -(A + B) -> (-A) - B. */
441 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
450 /* INT_MIN/n * n doesn't overflow while negating one operand it does
451 if n is a (negative) power of two. */
460 /* Fall through. */
475 /* In general we can't negate B in A / B, because if A is INT_MIN and
476 B is 1, we may turn this into INT_MIN / -1 which is undefined
477 and actually traps on some architectures. */
486 /* Negate -((double)float) as (double)(-float). */
488 {
492 }
496 /* Negate -f(x) as f(-x). */
502 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
504 {
508 }
513 }
515 }
517 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
518 simplification is possible.
519 If negate_expr_p would return true for T, NULL_TREE will never be
520 returned. */
522 static tree
524 {
526 tree tem;
529 {
530 /* Convert - (~A) to A + 1. */
556 {
561 }
565 {
570 {
575 }
578 }
601 {
602 /* -(A + B) -> (-B) - A. */
604 {
608 }
610 /* -(A + B) -> (-A) - B. */
612 {
616 }
617 }
621 /* - (A - B) -> B - A */
632 /* Fall through. */
636 {
645 }
657 /* In general we can't negate B in A / B, because if A is INT_MIN and
658 B is 1, we may turn this into INT_MIN / -1 which is undefined
659 and actually traps on some architectures. */
671 /* Convert -((double)float) into (double)(-float). */
673 {
677 }
681 /* Negate -f(x) as f(-x). */
684 {
690 }
694 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
696 {
699 {
706 }
707 }
712 }
715 }
717 /* A wrapper for fold_negate_expr_1. */
719 static tree
721 {
728 }
730 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
731 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
732 return NULL_TREE. */
734 static tree
736 {
738 location_t loc;
751 }
752 \f
753 /* Split a tree IN into a constant, literal and variable parts that could be
754 combined with CODE to make IN. "constant" means an expression with
755 TREE_CONSTANT but that isn't an actual constant. CODE must be a
756 commutative arithmetic operation. Store the constant part into *CONP,
757 the literal in *LITP and return the variable part. If a part isn't
758 present, set it to null. If the tree does not decompose in this way,
759 return the entire tree as the variable part and the other parts as null.
761 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
762 case, we negate an operand that was subtracted. Except if it is a
763 literal for which we use *MINUS_LITP instead.
765 If NEGATE_P is true, we are negating all of IN, again except a literal
766 for which we use *MINUS_LITP instead. If a variable part is of pointer
767 type, it is negated after converting to TYPE. This prevents us from
768 generating illegal MINUS pointer expression. LOC is the location of
769 the converted variable part.
771 If IN is itself a literal or constant, return it as appropriate.
773 Note that we do not guarantee that any of the three values will be the
774 same type as IN, but they will have the same signedness and mode. */
776 static tree
780 {
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. */
806 {
812 /* First see if either of the operands is a literal, then a constant. */
825 /* If we haven't dealt with either operand, this is not a case we can
826 decompose. Otherwise, VAR is either of the ones remaining, if any. */
831 else
834 /* Now do any needed negations. */
841 }
846 {
847 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
848 when IN is constant. */
851 }
852 else
856 {
869 }
879 }
881 /* Re-associate trees split by the above function. T1 and T2 are
882 either expressions to associate or null. Return the new
883 expression, if any. LOC is the location of the new expression. If
884 we build an operation, do it in TYPE and with CODE. */
886 static tree
888 {
890 {
893 }
897 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
898 try to fold this since we will have infinite recursion. But do
899 deal with any NEGATE_EXPRs. */
903 {
905 {
918 }
920 {
923 }
927 }
931 }
932 \f
933 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
934 for use in int_const_binop, size_binop and size_diffop. */
936 static bool
938 {
945 {
954 }
959 }
962 /* Combine two integer constants ARG1 and ARG2 under operation CODE
963 to produce a new constant. Return NULL_TREE if we don't know how
964 to evaluate CODE at compile-time. */
966 static tree
969 {
970 wide_int res;
971 tree t;
979 {
995 {
999 else
1001 }
1004 /* It's unclear from the C standard whether shifts can overflow.
1005 The following code ignores overflow; perhaps a C standard
1006 interpretation ruling is needed. */
1008 else
1015 {
1019 else
1021 }
1025 else
1104 }
1112 }
1114 tree
1116 {
1118 }
1120 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1121 constant. We assume ARG1 and ARG2 have the same data type, or at least
1122 are the same kind of constant and the same machine mode. Return zero if
1123 combining the constants is not allowed in the current operating mode. */
1125 static tree
1127 {
1128 /* Sanity check for the recursive cases. */
1136 {
1142 }
1145 {
1146 machine_mode mode;
1147 REAL_VALUE_TYPE d1;
1148 REAL_VALUE_TYPE d2;
1149 REAL_VALUE_TYPE value;
1150 REAL_VALUE_TYPE result;
1154 /* The following codes are handled by real_arithmetic. */
1156 {
1167 }
1175 /* Don't perform operation if we honor signaling NaNs and
1176 either operand is a signaling NaN. */
1182 /* Don't perform operation if it would raise a division
1183 by zero exception. */
1189 /* If either operand is a NaN, just return it. Otherwise, set up
1190 for floating-point trap; we return an overflow. */
1192 {
1193 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1194 is off. */
1198 }
1200 {
1201 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1202 is off. */
1206 }
1211 /* Don't constant fold this floating point operation if
1212 the result has overflowed and flag_trapping_math. */
1220 /* Don't constant fold this floating point operation if the
1221 result may dependent upon the run-time rounding mode and
1222 flag_rounding_math is set, or if GCC's software emulation
1223 is unable to accurately represent the result. */
1233 }
1236 {
1237 FIXED_VALUE_TYPE f1;
1238 FIXED_VALUE_TYPE f2;
1239 FIXED_VALUE_TYPE result;
1244 /* The following codes are handled by fixed_arithmetic. */
1246 {
1258 {
1265 }
1270 }
1277 /* Propagate overflow flags. */
1281 }
1284 {
1293 {
1304 mpc_mul);
1318 mpc_div);
1319 /* Fallthru. */
1325 {
1326 /* Keep this algorithm in sync with
1327 tree-complex.c:expand_complex_div_straight().
1329 Expand complex division to scalars, straightforward algorithm.
1330 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1331 t = br*br + bi*bi
1332 */
1333 tree magsquared
1337 tree t1
1341 tree t2
1348 }
1349 else
1350 {
1351 /* Keep this algorithm in sync with
1352 tree-complex.c:expand_complex_div_wide().
1354 Expand complex division to scalars, modified algorithm to minimize
1355 overflow with wide input ranges. */
1361 {
1362 /* In the TRUE branch, we compute
1363 ratio = br/bi;
1364 div = (br * ratio) + bi;
1365 tr = (ar * ratio) + ai;
1366 ti = (ai * ratio) - ar;
1367 tr = tr / div;
1368 ti = ti / div; */
1379 }
1380 else
1381 {
1382 /* In the FALSE branch, we compute
1383 ratio = d/c;
1384 divisor = (d * ratio) + c;
1385 tr = (b * ratio) + a;
1386 ti = b - (a * ratio);
1387 tr = tr / div;
1388 ti = ti / div; */
1400 }
1401 }
1406 }
1410 }
1414 {
1420 {
1426 /* It is possible that const_binop cannot handle the given
1427 code and return NULL_TREE */
1431 }
1434 }
1436 /* Shifts allow a scalar offset for a vector. */
1439 {
1445 {
1450 /* It is possible that const_binop cannot handle the given
1451 code and return NULL_TREE. */
1455 }
1458 }
1460 }
1462 /* Overload that adds a TYPE parameter to be able to dispatch
1463 to fold_relational_const. */
1465 tree
1467 {
1471 /* ??? Until we make the const_binop worker take the type of the
1472 result as argument put those cases that need it here. */
1474 {
1485 {
1499 {
1509 }
1512 }
1518 {
1540 {
1553 }
1556 }
1559 }
1564 /* Make sure type and arg0 have the same saturating flag. */
1569 }
1571 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1572 Return zero if computing the constants is not possible. */
1574 tree
1576 {
1577 /* Don't perform the operation, other than NEGATE and ABS, if
1578 flag_signaling_nans is on and the operand is a signaling NaN. */
1587 {
1588 CASE_CONVERT:
1595 /* If the source address is 0, and the source address space
1596 cannot have a valid object at 0, fold to dest type null. */
1607 {
1608 /* Can't call fold_negate_const directly here as that doesn't
1609 handle all cases and we might not be able to negate some
1610 constants. */
1615 }
1624 {
1628 }
1634 /* Perform BIT_NOT_EXPR on each element individually. */
1636 {
1637 tree elem;
1642 {
1648 }
1651 }
1673 {
1691 else
1696 {
1702 }
1705 }
1710 {
1719 {
1724 }
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;
1945 scalar_mode mode;
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;
2039 }
2041 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2042 to another fixed-point type. */
2044 static tree
2046 {
2047 FIXED_VALUE_TYPE value;
2048 tree t;
2055 /* Propagate overflow flags. */
2059 }
2061 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2062 to a fixed-point type. */
2064 static tree
2066 {
2067 FIXED_VALUE_TYPE value;
2068 tree t;
2070 double_int di;
2077 else
2085 /* Propagate overflow flags. */
2089 }
2091 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2092 to a fixed-point type. */
2094 static tree
2096 {
2097 FIXED_VALUE_TYPE value;
2098 tree t;
2106 /* Propagate overflow flags. */
2110 }
2112 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2113 type TYPE. If no simplification can be done return NULL_TREE. */
2115 static tree
2117 {
2123 {
2130 }
2132 {
2139 }
2141 {
2148 }
2150 {
2153 {
2158 {
2164 }
2166 }
2167 }
2169 }
2171 /* Construct a vector of zero elements of vector type TYPE. */
2173 static tree
2175 {
2176 tree t;
2180 }
2182 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2184 bool
2186 {
2201 {
2216 }
2217 }
2219 /* Convert expression ARG to type TYPE. Used by the middle-end for
2220 simple conversions in preference to calling the front-end's convert. */
2222 tree
2224 {
2226 tree tem;
2237 {
2240 /* Handle conversions between pointers to different address spaces. */
2245 /* fall through */
2250 {
2254 }
2268 {
2272 }
2274 {
2278 }
2280 {
2284 }
2287 {
2305 }
2310 {
2314 }
2317 {
2331 }
2335 {
2344 integer_zero_node));
2346 {
2350 {
2356 }
2364 }
2368 }
2386 }
2387 fold_convert_exit:
2390 }
2391 \f
2392 /* Return false if expr can be assumed not to be an lvalue, true
2393 otherwise. */
2395 static bool
2397 {
2398 /* We only need to wrap lvalue tree codes. */
2400 {
2431 /* Assume the worst for front-end tree codes. */
2435 }
2438 }
2440 /* Return an expr equal to X but certainly not valid as an lvalue. */
2442 tree
2444 {
2445 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2446 us. */
2453 }
2455 /* When pedantic, return an expr equal to X but certainly not valid as a
2456 pedantic lvalue. Otherwise, return X. */
2458 static tree
2460 {
2462 }
2463 \f
2464 /* Given a tree comparison code, return the code that is the logical inverse.
2465 It is generally not safe to do this for floating-point comparisons, except
2466 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2467 ERROR_MARK in this case. */
2469 enum tree_code
2471 {
2477 {
2508 }
2509 }
2511 /* Similar, but return the comparison that results if the operands are
2512 swapped. This is safe for floating-point. */
2514 enum tree_code
2516 {
2518 {
2544 }
2545 }
2548 /* Convert a comparison tree code from an enum tree_code representation
2549 into a compcode bit-based encoding. This function is the inverse of
2550 compcode_to_comparison. */
2552 static enum comparison_code
2554 {
2556 {
2587 }
2588 }
2590 /* Convert a compcode bit-based encoding of a comparison operator back
2591 to GCC's enum tree_code representation. This function is the
2592 inverse of comparison_to_compcode. */
2594 static enum tree_code
2596 {
2598 {
2629 }
2630 }
2632 /* Return a tree for the comparison which is the combination of
2633 doing the AND or OR (depending on CODE) of the two operations LCODE
2634 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2635 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2636 if this makes the transformation invalid. */
2638 tree
2643 {
2650 {
2661 }
2664 {
2665 /* Eliminate unordered comparisons, as well as LTGT and ORD
2666 which are not used unless the mode has NaNs. */
2672 }
2674 {
2675 /* Check that the original operation and the optimized ones will trap
2676 under the same condition. */
2687 /* In a short-circuited boolean expression the LHS might be
2688 such that the RHS, if evaluated, will never trap. For
2689 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2690 if neither x nor y is NaN. (This is a mixed blessing: for
2691 example, the expression above will never trap, hence
2692 optimizing it to x < y would be invalid). */
2697 /* If the comparison was short-circuited, and only the RHS
2698 trapped, we may now generate a spurious trap. */
2703 /* If we changed the conditions that cause a trap, we lose. */
2706 }
2712 else
2713 {
2718 }
2719 }
2720 \f
2721 /* Return nonzero if two operands (typically of the same tree node)
2722 are necessarily equal. FLAGS modifies behavior as follows:
2724 If OEP_ONLY_CONST is set, only return nonzero for constants.
2725 This function tests whether the operands are indistinguishable;
2726 it does not test whether they are equal using C's == operation.
2727 The distinction is important for IEEE floating point, because
2728 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2729 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2731 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2732 even though it may hold multiple values during a function.
2733 This is because a GCC tree node guarantees that nothing else is
2734 executed between the evaluation of its "operands" (which may often
2735 be evaluated in arbitrary order). Hence if the operands themselves
2736 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2737 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2738 unset means assuming isochronic (or instantaneous) tree equivalence.
2739 Unless comparing arbitrary expression trees, such as from different
2740 statements, this flag can usually be left unset.
2742 If OEP_PURE_SAME is set, then pure functions with identical arguments
2743 are considered the same. It is used when the caller has other ways
2744 to ensure that global memory is unchanged in between.
2746 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2747 not values of expressions.
2749 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2750 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2752 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2753 any operand with side effect. This is unnecesarily conservative in the
2754 case we know that arg0 and arg1 are in disjoint code paths (such as in
2755 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2756 addresses with TREE_CONSTANT flag set so we know that &var == &var
2757 even if var is volatile. */
2759 int
2761 {
2762 /* When checking, verify at the outermost operand_equal_p call that
2763 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2764 hash value. */
2766 {
2768 {
2770 {
2777 }
2779 }
2780 else
2782 }
2784 /* If either is ERROR_MARK, they aren't equal. */
2790 /* Similar, if either does not have a type (like a released SSA name),
2791 they aren't equal. */
2795 /* We cannot consider pointers to different address space equal. */
2802 /* Check equality of integer constants before bailing out due to
2803 precision differences. */
2805 {
2806 /* Address of INTEGER_CST is not defined; check that we did not forget
2807 to drop the OEP_ADDRESS_OF flags. */
2810 }
2813 {
2814 /* If both types don't have the same signedness, then we can't consider
2815 them equal. We must check this before the STRIP_NOPS calls
2816 because they may change the signedness of the arguments. As pointers
2817 strictly don't have a signedness, require either two pointers or
2818 two non-pointers as well. */
2824 /* If both types don't have the same precision, then it is not safe
2825 to strip NOPs. */
2832 }
2833 #if 0
2834 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2835 sanity check once the issue is solved. */
2836 else
2837 /* Addresses of conversions and SSA_NAMEs (and many other things)
2838 are not defined. Check that we did not forget to drop the
2839 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2842 #endif
2844 /* In case both args are comparisons but with different comparison
2845 code, try to swap the comparison operands of one arg to produce
2846 a match and compare that variant. */
2850 {
2858 }
2861 {
2862 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2864 ;
2866 {
2867 /* If we are interested in comparing addresses ignore
2868 MEM_REF wrappings of the base that can appear just for
2869 TBAA reasons. */
2883 }
2884 else
2886 }
2888 /* When not checking adddresses, this is needed for conversions and for
2889 COMPONENT_REF. Might as well play it safe and always test this. */
2896 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2897 We don't care about side effects in that case because the SAVE_EXPR
2898 takes care of that for us. In all other cases, two expressions are
2899 equal if they have no side effects. If we have two identical
2900 expressions with side effects that should be treated the same due
2901 to the only side effects being identical SAVE_EXPR's, that will
2902 be detected in the recursive calls below.
2903 If we are taking an invariant address of two identical objects
2904 they are necessarily equal as well. */
2911 /* Next handle constant cases, those for which we can return 1 even
2912 if ONLY_CONST is set. */
2915 {
2929 {
2930 /* If we do not distinguish between signed and unsigned zero,
2931 consider them equal. */
2934 }
2938 {
2945 {
2949 }
2951 }
2955 flags)
2957 flags));
2968 flags | OEP_ADDRESS_OF
2971 /* In GIMPLE empty constructors are allowed in initializers of
2972 aggregates. */
2976 }
2981 /* Define macros to test an operand from arg0 and arg1 for equality and a
2982 variant that allows null and views null as being different from any
2983 non-null value. In the latter case, if either is null, the both
2984 must be; otherwise, do the normal comparison. */
2985 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2986 TREE_OPERAND (arg1, N), flags)
2988 #define OP_SAME_WITH_NULL(N) \
2989 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2990 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2993 {
2995 /* Two conversions are equal only if signedness and modes match. */
2997 {
2998 CASE_CONVERT:
3006 }
3016 /* For commutative ops, allow the other order. */
3024 /* If either of the pointer (or reference) expressions we are
3025 dereferencing contain a side effect, these cannot be equal,
3026 but their addresses can be. */
3033 {
3043 /* Require the same offset. */
3049 /* Fallthru. */
3057 {
3058 /* Require equal access sizes */
3064 flags)))
3066 /* Verify that access happens in similar types. */
3069 /* Verify that accesses are TBAA compatible. */
3078 /* Verify that alignment is compatible. */
3082 }
3085 /* TARGET_MEM_REF require equal extra operands. */
3096 /* Compare the array index by value if it is constant first as we
3097 may have different types but same value here. */
3103 /* Compare low bound and element size as with OEP_ADDRESS_OF
3104 we have to account for the offset of the ref. */
3109 array_ref_low_bound
3113 array_ref_element_size
3115 flags))));
3118 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3119 may be NULL when we're called to compare MEM_EXPRs. */
3134 }
3138 {
3140 /* Be sure we pass right ADDRESS_OF flag. */
3158 /* The multiplcation operands are commutative. */
3159 /* FALLTHRU */
3167 /* Otherwise take into account this is a commutative operation. */
3180 /* BIT_INSERT_EXPR has an implict operand as the type precision
3181 of op1. Need to check to make sure they are the same. */
3187 /* FALLTHRU */
3212 }
3216 {
3220 /* If not both CALL_EXPRs are either internal or normal function
3221 functions, then they are not equal. */
3224 {
3225 /* If the CALL_EXPRs call different internal functions, then they
3226 are not equal. */
3229 }
3230 else
3231 {
3232 /* If the CALL_EXPRs call different functions, then they are not
3233 equal. */
3235 flags))
3237 }
3239 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3240 {
3244 else
3248 }
3250 /* Now see if all the arguments are the same. */
3251 {
3262 /* If we get here and both argument lists are exhausted
3263 then the CALL_EXPRs are equal. */
3265 }
3268 }
3271 /* Consider __builtin_sqrt equal to sqrt. */
3279 {
3280 /* In GIMPLE constructors are used only to build vectors from
3281 elements. Individual elements in the constructor must be
3282 indexed in increasing order and form an initial sequence.
3284 We make no effort to compare constructors in generic.
3285 (see sem_variable::equals in ipa-icf which can do so for
3286 constants). */
3291 /* Be sure that vectors constructed have the same representation.
3292 We only tested element precision and modes to match.
3293 Vectors may be BLKmode and thus also check that the number of
3294 parts match. */
3307 {
3312 /* In GIMPLE the indexes can be either NULL or matching i.
3313 Double check this so we won't get false
3314 positives for GENERIC. */
3322 }
3324 }
3327 {
3328 /* Compare the STATEMENT_LISTs. */
3334 {
3335 /* The lists don't have the same number of statements. */
3341 OEP_LEXICOGRAPHIC))
3343 }
3344 }
3349 {
3356 }
3360 }
3362 #undef OP_SAME
3363 #undef OP_SAME_WITH_NULL
3364 }
3365 \f
3366 /* Similar to operand_equal_p, but strip nops first. */
3368 static bool
3370 {
3378 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3379 and see if the inner values are the same. This removes any
3380 signedness comparison, which doesn't matter here. */
3387 }
3388 \f
3389 /* See if ARG is an expression that is either a comparison or is performing
3390 arithmetic on comparisons. The comparisons must only be comparing
3391 two different values, which will be stored in *CVAL1 and *CVAL2; if
3392 they are nonzero it means that some operands have already been found.
3393 No variables may be used anywhere else in the expression except in the
3394 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3395 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3397 If this is true, return 1. Otherwise, return zero. */
3399 static int
3401 {
3405 /* We can handle some of the tcc_expression cases here. */
3415 {
3416 /* If we've already found a CVAL1 or CVAL2, this expression is
3417 two complex to handle. */
3423 }
3426 {
3449 /* First see if we can handle the first operand, then the second. For
3450 the second operand, we know *CVAL1 can't be zero. It must be that
3451 one side of the comparison is each of the values; test for the
3452 case where this isn't true by failing if the two operands
3453 are the same. */
3462 ;
3466 ;
3467 else
3471 ;
3475 ;
3476 else
3483 }
3484 }
3485 \f
3486 /* ARG is a tree that is known to contain just arithmetic operations and
3487 comparisons. Evaluate the operations in the tree substituting NEW0 for
3488 any occurrence of OLD0 as an operand of a comparison and likewise for
3489 NEW1 and OLD1. */
3491 static tree
3494 {
3499 /* We can handle some of the tcc_expression cases here. */
3507 {
3522 {
3541 }
3542 /* Fall through - ??? */
3545 {
3549 /* We need to check both for exact equality and tree equality. The
3550 former will be true if the operand has a side-effect. In that
3551 case, we know the operand occurred exactly once. */
3564 }
3568 }
3569 }
3570 \f
3571 /* Return a tree for the case when the result of an expression is RESULT
3572 converted to TYPE and OMITTED was previously an operand of the expression
3573 but is now not needed (e.g., we folded OMITTED * 0).
3575 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3576 the conversion of RESULT to TYPE. */
3578 tree
3580 {
3583 /* If the resulting operand is an empty statement, just return the omitted
3584 statement casted to void. */
3594 }
3596 /* Return a tree for the case when the result of an expression is RESULT
3597 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3598 of the expression but are now not needed.
3600 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3601 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3602 evaluated before OMITTED2. Otherwise, if neither has side effects,
3603 just do the conversion of RESULT to TYPE. */
3605 tree
3608 {
3617 }
3619 \f
3620 /* Return a simplified tree node for the truth-negation of ARG. This
3621 never alters ARG itself. We assume that ARG is an operation that
3622 returns a truth value (0 or 1).
3624 FIXME: one would think we would fold the result, but it causes
3625 problems with the dominator optimizer. */
3627 static tree
3629 {
3634 /* If this is a comparison, we can simply invert it, except for
3635 floating-point non-equality comparisons, in which case we just
3636 enclose a TRUTH_NOT_EXPR around what we have. */
3639 {
3642 && flag_trapping_math
3656 }
3659 {
3678 /* Here we can invert either operand. We invert the first operand
3679 unless the second operand is a TRUTH_NOT_EXPR in which case our
3680 result is the XOR of the first operand with the inside of the
3681 negation of the second operand. */
3686 else
3709 {
3716 /* A COND_EXPR may have a throw as one operand, which
3717 then has void type. Just leave void operands
3718 as they are. */
3724 }
3736 CASE_CONVERT:
3740 /* fall through */
3762 }
3763 }
3765 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3766 assume that ARG is an operation that returns a truth value (0 or 1
3767 for scalars, 0 or -1 for vectors). Return the folded expression if
3768 folding is successful. Otherwise, return NULL_TREE. */
3770 static tree
3772 {
3775 ? BIT_NOT_EXPR
3778 }
3780 /* Return a simplified tree node for the truth-negation of ARG. This
3781 never alters ARG itself. We assume that ARG is an operation that
3782 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3784 tree
3786 {
3792 ? BIT_NOT_EXPR
3795 }
3797 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3798 with code CODE. This optimization is unsafe. */
3799 static tree
3802 {
3806 /* (A / C) +- (B / C) -> (A +- B) / C. */
3816 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3821 {
3833 }
3836 }
3837 \f
3838 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3839 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3840 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3841 is the original memory reference used to preserve the alias set of
3842 the access. */
3844 static tree
3848 {
3851 /* Attempt not to lose the access path if possible. */
3853 {
3855 machine_mode nmode;
3857 tree noffset;
3867 && !reversep
3868 && !nreversep
3870 {
3873 }
3874 }
3883 {
3890 }
3905 }
3907 /* Optimize a bit-field compare.
3909 There are two cases: First is a compare against a constant and the
3910 second is a comparison of two items where the fields are at the same
3911 bit position relative to the start of a chunk (byte, halfword, word)
3912 large enough to contain it. In these cases we can avoid the shift
3913 implicit in bitfield extractions.
3915 For constants, we emit a compare of the shifted constant with the
3916 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3917 compared. For two fields at the same position, we do the ANDs with the
3918 similar mask and compare the result of the ANDs.
3920 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3921 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3922 are the left and right operands of the comparison, respectively.
3924 If the optimization described above can be done, we return the resulting
3925 tree. Otherwise we return zero. */
3927 static tree
3930 {
3933 tree unsigned_type;
3936 scalar_int_mode nmode;
3941 tree mask;
3942 tree offset;
3944 /* Get all the information about the extractions being done. If the bit size
3945 if the same as the size of the underlying object, we aren't doing an
3946 extraction at all and so can do nothing. We also don't want to
3947 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3948 then will no longer be able to replace it. */
3957 else
3958 {
3959 /* If this is not a constant, we can only do something if bit positions,
3960 sizes, signedness and storage order are the same. */
3961 rinner
3969 }
3971 /* Honor the C++ memory model and mimic what RTL expansion does. */
3975 {
3979 }
3981 /* See if we can find a mode to refer to this field. We should be able to,
3982 but fail if we can't. */
3990 /* Set signed and unsigned types of the precision of this mode for the
3991 shifts below. */
3994 /* Compute the bit position and size for the new reference and our offset
3995 within it. If the new reference is the same size as the original, we
3996 won't optimize anything, so return zero. */
4006 /* Make the mask to be used against the extracted field. */
4013 /* If not comparing with constant, just rework the comparison
4014 and return. */
4018 unsigned_type,
4021 mask),
4024 unsigned_type,
4027 mask));
4029 /* Otherwise, we are handling the constant case. See if the constant is too
4030 big for the field. Warn and return a tree for 0 (false) if so. We do
4031 this not only for its own sake, but to avoid having to test for this
4032 error case below. If we didn't, we might generate wrong code.
4034 For unsigned fields, the constant shifted right by the field length should
4035 be all zero. For signed fields, the high-order bits should agree with
4036 the sign bit. */
4039 {
4041 {
4045 }
4046 }
4047 else
4048 {
4051 {
4055 }
4056 }
4058 /* Single-bit compares should always be against zero. */
4060 {
4063 }
4065 /* Make a new bitfield reference, shift the constant over the
4066 appropriate number of bits and mask it with the computed mask
4067 (in case this was a signed field). If we changed it, make a new one. */
4075 mask);
4080 }
4081 \f
4082 /* Subroutine for fold_truth_andor_1: decode a field reference.
4084 If EXP is a comparison reference, we return the innermost reference.
4086 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4087 set to the starting bit number.
4089 If the innermost field can be completely contained in a mode-sized
4090 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4092 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4093 otherwise it is not changed.
4095 *PUNSIGNEDP is set to the signedness of the field.
4097 *PREVERSEP is set to the storage order of the field.
4099 *PMASK is set to the mask used. This is either contained in a
4100 BIT_AND_EXPR or derived from the width of the field.
4102 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4104 Return 0 if this is not a component reference or is one that we can't
4105 do anything with. */
4107 static tree
4112 {
4117 tree unsigned_type;
4120 /* All the optimizations using this function assume integer fields.
4121 There are problems with FP fields since the type_for_size call
4122 below can fail for, e.g., XFmode. */
4126 /* We are interested in the bare arrangement of bits, so strip everything
4127 that doesn't affect the machine mode. However, record the type of the
4128 outermost expression if it may matter below. */
4135 {
4141 }
4148 /* Reject out-of-bound accesses (PR79731). */
4156 /* If the number of bits in the reference is the same as the bitsize of
4157 the outer type, then the outer type gives the signedness. Otherwise
4158 (in case of a small bitfield) the signedness is unchanged. */
4162 /* Compute the mask to access the bitfield. */
4171 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4179 }
4181 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4182 bit positions and MASK is SIGNED. */
4184 static int
4186 {
4190 /* If this function returns true when the type of the mask is
4191 UNSIGNED, then there will be errors. In particular see
4192 gcc.c-torture/execute/990326-1.c. There does not appear to be
4193 any documentation paper trail as to why this is so. But the pre
4194 wide-int worked with that restriction and it has been preserved
4195 here. */
4200 }
4202 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4203 represents the sign bit of EXP's type. If EXP represents a sign
4204 or zero extension, also test VAL against the unextended type.
4205 The return value is the (sub)expression whose sign bit is VAL,
4206 or NULL_TREE otherwise. */
4208 tree
4210 {
4212 tree t;
4214 /* Tree EXP must have an integral type. */
4219 /* Tree VAL must be an integer constant. */
4228 /* Handle extension from a narrower type. */
4234 }
4236 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4237 to be evaluated unconditionally. */
4239 static int
4241 {
4242 /* Strip any conversions that don't change the machine mode. */
4251 /* Don't regard global variables as simple. They may be
4252 allocated in ways unknown to the compiler (shared memory,
4253 #pragma weak, etc). */
4256 /* Weakrefs are not safe to be read, since they can be NULL.
4257 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4258 have DECL_WEAK flag set. */
4260 /* Loading a static variable is unduly expensive, but global
4261 registers aren't expensive. */
4263 }
4265 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4266 to be evaluated unconditionally.
4267 I addition to simple_operand_p, we assume that comparisons, conversions,
4268 and logic-not operations are simple, if their operands are simple, too. */
4270 static bool
4272 {
4292 }
4294 \f
4295 /* The following functions are subroutines to fold_range_test and allow it to
4296 try to change a logical combination of comparisons into a range test.
4298 For example, both
4299 X == 2 || X == 3 || X == 4 || X == 5
4300 and
4301 X >= 2 && X <= 5
4302 are converted to
4303 (unsigned) (X - 2) <= 3
4305 We describe each set of comparisons as being either inside or outside
4306 a range, using a variable named like IN_P, and then describe the
4307 range with a lower and upper bound. If one of the bounds is omitted,
4308 it represents either the highest or lowest value of the type.
4310 In the comments below, we represent a range by two numbers in brackets
4311 preceded by a "+" to designate being inside that range, or a "-" to
4312 designate being outside that range, so the condition can be inverted by
4313 flipping the prefix. An omitted bound is represented by a "-". For
4314 example, "- [-, 10]" means being outside the range starting at the lowest
4315 possible value and ending at 10, in other words, being greater than 10.
4316 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4317 always false.
4319 We set up things so that the missing bounds are handled in a consistent
4320 manner so neither a missing bound nor "true" and "false" need to be
4321 handled using a special case. */
4323 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4324 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4325 and UPPER1_P are nonzero if the respective argument is an upper bound
4326 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4327 must be specified for a comparison. ARG1 will be converted to ARG0's
4328 type if both are specified. */
4330 static tree
4333 {
4334 tree tem;
4338 /* If neither arg represents infinity, do the normal operation.
4339 Else, if not a comparison, return infinity. Else handle the special
4340 comparison rules. Note that most of the cases below won't occur, but
4341 are handled for consistency. */
4344 {
4349 }
4354 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4355 for neither. In real maths, we cannot assume open ended ranges are
4356 the same. But, this is computer arithmetic, where numbers are finite.
4357 We can therefore make the transformation of any unbounded range with
4358 the value Z, Z being greater than any representable number. This permits
4359 us to treat unbounded ranges as equal. */
4363 {
4384 }
4387 }
4388 \f
4389 /* Helper routine for make_range. Perform one step for it, return
4390 new expression if the loop should continue or NULL_TREE if it should
4391 stop. */
4393 tree
4397 {
4403 {
4405 /* We can only do something if the range is testing for zero. */
4414 /* We can only do something if the range is testing for zero
4415 and if the second operand is an integer constant. Note that
4416 saying something is "in" the range we make is done by
4417 complementing IN_P since it will set in the initial case of
4418 being not equal to zero; "out" is leaving it alone. */
4425 {
4446 }
4448 /* If this is an unsigned comparison, we also know that EXP is
4449 greater than or equal to zero. We base the range tests we make
4450 on that fact, so we record it here so we can parse existing
4451 range tests. We test arg0_type since often the return type
4452 of, e.g. EQ_EXPR, is boolean. */
4454 {
4458 NULL_TREE))
4463 /* If the high bound is missing, but we have a nonzero low
4464 bound, reverse the range so it goes from zero to the low bound
4465 minus 1. */
4467 {
4472 }
4473 }
4481 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4482 low and high are non-NULL, then normalize will DTRT. */
4485 {
4490 }
4492 /* (-x) IN [a,b] -> x in [-b, -a] */
4504 /* ~ X -> -X - 1 */
4513 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4514 move a constant to the other side. */
4519 /* If EXP is signed, any overflow in the computation is undefined,
4520 so we don't worry about it so long as our computations on
4521 the bounds don't overflow. For unsigned, overflow is defined
4522 and this is exactly the right thing. */
4534 normalize:
4535 /* Check for an unsigned range which has wrapped around the maximum
4536 value thus making n_high < n_low, and normalize it. */
4538 {
4544 /* If the range is of the form +/- [ x+1, x ], we won't
4545 be able to normalize it. But then, it represents the
4546 whole range or the empty set, so make it
4547 +/- [ -, - ]. */
4551 else
4553 }
4554 else
4562 CASE_CONVERT:
4580 /* If we're converting arg0 from an unsigned type, to exp,
4581 a signed type, we will be doing the comparison as unsigned.
4582 The tests above have already verified that LOW and HIGH
4583 are both positive.
4585 So we have to ensure that we will handle large unsigned
4586 values the same way that the current signed bounds treat
4587 negative values. */
4590 {
4591 tree high_positive;
4592 tree equiv_type;
4593 /* For fixed-point modes, we need to pass the saturating flag
4594 as the 2nd parameter. */
4596 equiv_type
4599 else
4600 equiv_type
4603 /* A range without an upper bound is, naturally, unbounded.
4604 Since convert would have cropped a very large value, use
4605 the max value for the destination type. */
4606 high_positive
4613 high_positive),
4616 /* If the low bound is specified, "and" the range with the
4617 range for which the original unsigned value will be
4618 positive. */
4620 {
4623 integer_zero_node),
4624 high_positive))
4628 }
4629 else
4630 {
4631 /* Otherwise, "or" the range with the range of the input
4632 that will be interpreted as negative. */
4635 integer_zero_node),
4636 high_positive))
4640 }
4641 }
4650 }
4651 }
4653 /* Given EXP, a logical expression, set the range it is testing into
4654 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4655 actually being tested. *PLOW and *PHIGH will be made of the same
4656 type as the returned expression. If EXP is not a comparison, we
4657 will most likely not be returning a useful value and range. Set
4658 *STRICT_OVERFLOW_P to true if the return value is only valid
4659 because signed overflow is undefined; otherwise, do not change
4660 *STRICT_OVERFLOW_P. */
4662 tree
4665 {
4673 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4674 and see if we can refine the range. Some of the cases below may not
4675 happen, but it doesn't seem worth worrying about this. We "continue"
4676 the outer loop when we've changed something; otherwise we "break"
4677 the switch, which will "break" the while. */
4683 {
4689 {
4697 }
4706 }
4708 /* If EXP is a constant, we can evaluate whether this is true or false. */
4710 {
4717 }
4721 }
4723 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4724 a bitwise check i.e. when
4725 LOW == 0xXX...X00...0
4726 HIGH == 0xXX...X11...1
4727 Return corresponding mask in MASK and stem in VALUE. */
4729 static bool
4732 {
4755 }
4756 \f
4757 /* Helper routine for build_range_check and match.pd. Return the type to
4758 perform the check or NULL if it shouldn't be optimized. */
4760 tree
4762 {
4763 /* First make sure that arithmetics in this type is valid, then make sure
4764 that it wraps around. */
4770 {
4773 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4774 for the type in question, as we rely on this here. */
4784 else
4786 }
4788 }
4790 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4791 type, TYPE, return an expression to test if EXP is in (or out of, depending
4792 on IN_P) the range. Return 0 if the test couldn't be created. */
4794 tree
4797 {
4800 /* Disable this optimization for function pointer expressions
4801 on targets that require function pointer canonicalization. */
4808 {
4814 }
4836 value);
4839 {
4841 {
4845 }
4847 }
4849 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4851 {
4855 {
4857 {
4860 etype
4862 else
4865 }
4868 }
4869 }
4871 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4872 This requires wrap-around arithmetics for the type of the expression. */
4892 }
4893 \f
4894 /* Return the predecessor of VAL in its type, handling the infinite case. */
4896 static tree
4898 {
4904 else
4907 }
4909 /* Return the successor of VAL in its type, handling the infinite case. */
4911 static tree
4913 {
4919 else
4922 }
4924 /* Given two ranges, see if we can merge them into one. Return 1 if we
4925 can, 0 if we can't. Set the output range into the specified parameters. */
4927 bool
4930 {
4934 tree tem;
4944 /* Make range 0 be the range that starts first, or ends last if they
4945 start at the same value. Swap them if it isn't. */
4948 || (lowequal
4951 {
4955 }
4957 /* Now flag two cases, whether the ranges are disjoint or whether the
4958 second range is totally subsumed in the first. Note that the tests
4959 below are simplified by the ones above. */
4965 /* We now have four cases, depending on whether we are including or
4966 excluding the two ranges. */
4968 {
4969 /* If they don't overlap, the result is false. If the second range
4970 is a subset it is the result. Otherwise, the range is from the start
4971 of the second to the end of the first. */
4976 else
4978 }
4981 {
4982 /* If they don't overlap, the result is the first range. If they are
4983 equal, the result is false. If the second range is a subset of the
4984 first, and the ranges begin at the same place, we go from just after
4985 the end of the second range to the end of the first. If the second
4986 range is not a subset of the first, or if it is a subset and both
4987 ranges end at the same place, the range starts at the start of the
4988 first range and ends just before the second range.
4989 Otherwise, we can't describe this as a single range. */
4995 {
5000 {
5001 /* We are in the weird situation where high0 > high1 but
5002 high1 has no successor. Punt. */
5004 }
5005 }
5007 {
5012 {
5013 /* low0 < low1 but low1 has no predecessor. Punt. */
5015 }
5016 }
5017 else
5019 }
5022 {
5023 /* If they don't overlap, the result is the second range. If the second
5024 is a subset of the first, the result is false. Otherwise,
5025 the range starts just after the first range and ends at the
5026 end of the second. */
5031 else
5032 {
5037 {
5038 /* high1 > high0 but high0 has no successor. Punt. */
5040 }
5041 }
5042 }
5044 else
5045 {
5046 /* The case where we are excluding both ranges. Here the complex case
5047 is if they don't overlap. In that case, the only time we have a
5048 range is if they are adjacent. If the second is a subset of the
5049 first, the result is the first. Otherwise, the range to exclude
5050 starts at the beginning of the first range and ends at the end of the
5051 second. */
5053 {
5058 else
5059 {
5060 /* Canonicalize - [min, x] into - [-, x]. */
5063 {
5068 /* FALLTHROUGH */
5081 }
5083 /* Canonicalize - [x, max] into - [x, -]. */
5086 {
5091 /* FALLTHROUGH */
5107 }
5109 /* The ranges might be also adjacent between the maximum and
5110 minimum values of the given type. For
5111 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5112 return + [x + 1, y - 1]. */
5114 {
5121 }
5122 else
5124 }
5125 }
5128 else
5130 }
5134 }
5135 \f
5137 /* Subroutine of fold, looking inside expressions of the form
5138 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5139 of the COND_EXPR. This function is being used also to optimize
5140 A op B ? C : A, by reversing the comparison first.
5142 Return a folded expression whose code is not a COND_EXPR
5143 anymore, or NULL_TREE if no folding opportunity is found. */
5145 static tree
5148 {
5153 tree tem;
5158 /* If we have A op 0 ? A : -A, consider applying the following
5159 transformations:
5161 A == 0? A : -A same as -A
5162 A != 0? A : -A same as A
5163 A >= 0? A : -A same as abs (A)
5164 A > 0? A : -A same as abs (A)
5165 A <= 0? A : -A same as -abs (A)
5166 A < 0? A : -A same as -abs (A)
5168 None of these transformations work for modes with signed
5169 zeros. If A is +/-0, the first two transformations will
5170 change the sign of the result (from +0 to -0, or vice
5171 versa). The last four will fix the sign of the result,
5172 even though the original expressions could be positive or
5173 negative, depending on the sign of A.
5175 Note that all these transformations are correct if A is
5176 NaN, since the two alternatives (A and -A) are also NaNs. */
5183 /* In the case that A is of the form X-Y, '-A' (arg2) may
5184 have already been folded to Y-X, check for that. */
5192 {
5204 /* Fall through. */
5215 /* FALLTHRU */
5225 }
5227 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5228 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5229 both transformations are correct when A is NaN: A != 0
5230 is then true, and A == 0 is false. */
5234 {
5239 }
5241 /* Try some transformations of A op B ? A : B.
5243 A == B? A : B same as B
5244 A != B? A : B same as A
5245 A >= B? A : B same as max (A, B)
5246 A > B? A : B same as max (B, A)
5247 A <= B? A : B same as min (A, B)
5248 A < B? A : B same as min (B, A)
5250 As above, these transformations don't work in the presence
5251 of signed zeros. For example, if A and B are zeros of
5252 opposite sign, the first two transformations will change
5253 the sign of the result. In the last four, the original
5254 expressions give different results for (A=+0, B=-0) and
5255 (A=-0, B=+0), but the transformed expressions do not.
5257 The first two transformations are correct if either A or B
5258 is a NaN. In the first transformation, the condition will
5259 be false, and B will indeed be chosen. In the case of the
5260 second transformation, the condition A != B will be true,
5261 and A will be chosen.
5263 The conversions to max() and min() are not correct if B is
5264 a number and A is not. The conditions in the original
5265 expressions will be false, so all four give B. The min()
5266 and max() versions would give a NaN instead. */
5269 /* Avoid these transformations if the COND_EXPR may be used
5270 as an lvalue in the C++ front-end. PR c++/19199. */
5271 && (in_gimple_form
5277 {
5283 {
5292 /* In C++ a ?: expression can be an lvalue, so put the
5293 operand which will be used if they are equal first
5294 so that we can convert this back to the
5295 corresponding COND_EXPR. */
5297 {
5305 }
5312 {
5320 }
5333 }
5334 }
5337 }
5340 \f
5341 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5342 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5343 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5344 false) >= 2)
5345 #endif
5347 /* EXP is some logical combination of boolean tests. See if we can
5348 merge it into some range test. Return the new tree if so. */
5350 static tree
5353 {
5369 /* If this is an OR operation, invert both sides; we will invert
5370 again at the end. */
5374 /* If both expressions are the same, if we can merge the ranges, and we
5375 can build the range test, return it or it inverted. If one of the
5376 ranges is always true or always false, consider it to be the same
5377 expression as the other. */
5385 {
5389 }
5391 /* On machines where the branch cost is expensive, if this is a
5392 short-circuited branch and the underlying object on both sides
5393 is the same, make a non-short-circuit operation. */
5395 && !flag_sanitize_coverage
5400 {
5401 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5402 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5403 which cases we can't do this. */
5411 {
5420 {
5423 WARN_STRICT_OVERFLOW_COMPARISON);
5427 }
5428 }
5429 }
5432 }
5433 \f
5434 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5435 bit value. Arrange things so the extra bits will be set to zero if and
5436 only if C is signed-extended to its full width. If MASK is nonzero,
5437 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5439 static tree
5441 {
5444 tree temp;
5449 /* We work by getting just the sign bit into the low-order bit, then
5450 into the high-order bit, then sign-extend. We then XOR that value
5451 with C. */
5454 /* We must use a signed type in order to get an arithmetic right shift.
5455 However, we must also avoid introducing accidental overflows, so that
5456 a subsequent call to integer_zerop will work. Hence we must
5457 do the type conversion here. At this point, the constant is either
5458 zero or one, and the conversion to a signed type can never overflow.
5459 We could get an overflow if this conversion is done anywhere else. */
5468 /* If necessary, convert the type back to match the type of C. */
5473 }
5474 \f
5475 /* For an expression that has the form
5476 (A && B) || ~B
5477 or
5478 (A || B) && ~B,
5479 we can drop one of the inner expressions and simplify to
5480 A || ~B
5481 or
5482 A && ~B
5483 LOC is the location of the resulting expression. OP is the inner
5484 logical operation; the left-hand side in the examples above, while CMPOP
5485 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5486 removing a condition that guards another, as in
5487 (A != NULL && A->...) || A == NULL
5488 which we must not transform. If RHS_ONLY is true, only eliminate the
5489 right-most operand of the inner logical operation. */
5491 static tree
5494 {
5512 {
5515 {
5518 }
5519 }
5521 {
5524 {
5527 }
5528 }
5543 }
5545 /* Find ways of folding logical expressions of LHS and RHS:
5546 Try to merge two comparisons to the same innermost item.
5547 Look for range tests like "ch >= '0' && ch <= '9'".
5548 Look for combinations of simple terms on machines with expensive branches
5549 and evaluate the RHS unconditionally.
5551 For example, if we have p->a == 2 && p->b == 4 and we can make an
5552 object large enough to span both A and B, we can do this with a comparison
5553 against the object ANDed with the a mask.
5555 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5556 operations to do this with one comparison.
5558 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5559 function and the one above.
5561 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5562 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5564 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5565 two operands.
5567 We return the simplified tree or 0 if no optimization is possible. */
5569 static tree
5572 {
5573 /* If this is the "or" of two comparisons, we can do something if
5574 the comparisons are NE_EXPR. If this is the "and", we can do something
5575 if the comparisons are EQ_EXPR. I.e.,
5576 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5578 WANTED_CODE is this operation code. For single bit fields, we can
5579 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5580 comparison for one-bit fields. */
5601 /* Start by getting the comparison codes. Fail if anything is volatile.
5602 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5603 it were surrounded with a NE_EXPR. */
5612 {
5616 }
5619 {
5623 }
5634 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5637 {
5640 {
5645 }
5648 {
5654 }
5655 }
5660 /* If the RHS can be evaluated unconditionally and its operands are
5661 simple, it wins to evaluate the RHS unconditionally on machines
5662 with expensive branches. In this case, this isn't a comparison
5663 that can be merged. */
5670 {
5671 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5682 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5692 }
5694 /* See if the comparisons can be merged. Then get all the parameters for
5695 each side. */
5720 /* It must be true that the inner operation on the lhs of each
5721 comparison must be the same if we are to be able to do anything.
5722 Then see if we have constants. If not, the same must be true for
5723 the rhs's. */
5732 {
5735 }
5740 else
5743 /* If either comparison code is not correct for our logical operation,
5744 fail. However, we can convert a one-bit comparison against zero into
5745 the opposite comparison against that bit being set in the field. */
5749 {
5751 {
5752 /* Make the left operand unsigned, since we are only interested
5753 in the value of one bit. Otherwise we are doing the wrong
5754 thing below. */
5757 }
5758 else
5760 }
5762 /* This is analogous to the code for l_const above. */
5764 {
5766 {
5769 }
5770 else
5772 }
5774 /* See if we can find a mode that contains both fields being compared on
5775 the left. If we can't, fail. Otherwise, update all constants and masks
5776 to be relative to a field of that size. */
5790 {
5793 }
5801 {
5808 {
5812 }
5813 }
5815 {
5822 {
5826 }
5827 }
5829 /* If the right sides are not constant, do the same for it. Also,
5830 disallow this optimization if a size or signedness mismatch occurs
5831 between the left and right sides. */
5833 {
5836 /* Make sure the two fields on the right
5837 correspond to the left without being swapped. */
5854 {
5857 }
5866 /* Make a mask that corresponds to both fields being compared.
5867 Do this for both items being compared. If the operands are the
5868 same size and the bits being compared are in the same position
5869 then we can do this by masking both and comparing the masked
5870 results. */
5874 {
5888 }
5890 /* There is still another way we can do something: If both pairs of
5891 fields being compared are adjacent, we may be able to make a wider
5892 field containing them both.
5894 Note that we still must mask the lhs/rhs expressions. Furthermore,
5895 the mask must be shifted to account for the shift done by
5896 make_bit_field_ref. */
5901 {
5902 tree type;
5918 /* Convert to the smaller type before masking out unwanted bits. */
5921 {
5923 {
5927 }
5929 {
5933 }
5934 }
5943 }
5946 }
5948 /* Handle the case of comparisons with constants. If there is something in
5949 common between the masks, those bits of the constants must be the same.
5950 If not, the condition is always false. Test for this to avoid generating
5951 incorrect code below. */
5956 {
5958 {
5961 }
5962 else
5963 {
5966 }
5967 }
5969 /* Construct the expression we will return. First get the component
5970 reference we will make. Unless the mask is all ones the width of
5971 that field, perform the mask operation. Then compare with the
5972 merged constant. */
5983 }
5984 \f
5985 /* T is an integer expression that is being multiplied, divided, or taken a
5986 modulus (CODE says which and what kind of divide or modulus) by a
5987 constant C. See if we can eliminate that operation by folding it with
5988 other operations already in T. WIDE_TYPE, if non-null, is a type that
5989 should be used for the computation if wider than our type.
5991 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5992 (X * 2) + (Y * 4). We must, however, be assured that either the original
5993 expression would not overflow or that overflow is undefined for the type
5994 in the language in question.
5996 If we return a non-null expression, it is an equivalent form of the
5997 original computation, but need not be in the original type.
5999 We set *STRICT_OVERFLOW_P to true if the return values depends on
6000 signed overflow being undefined. Otherwise we do not change
6001 *STRICT_OVERFLOW_P. */
6003 static tree
6006 {
6007 /* To avoid exponential search depth, refuse to allow recursion past
6008 three levels. Beyond that (1) it's highly unlikely that we'll find
6009 something interesting and (2) we've probably processed it before
6010 when we built the inner expression. */
6013 tree ret;
6018 depth++;
6020 depth--;
6023 }
6025 static tree
6028 {
6040 /* Don't deal with constants of zero here; they confuse the code below. */
6050 /* Note that we need not handle conditional operations here since fold
6051 already handles those cases. So just do arithmetic here. */
6053 {
6055 /* For a constant, we can always simplify if we are a multiply
6056 or (for divide and modulus) if it is a multiple of our constant. */
6059 {
6062 /* If the multiplication overflowed, we lost information on it.
6063 See PR68142 and PR69845. */
6067 }
6071 /* If op0 is an expression ... */
6077 /* ... and has wrapping overflow, and its type is smaller
6078 than ctype, then we cannot pass through as widening. */
6083 /* ... or this is a truncation (t is narrower than op0),
6084 then we cannot pass through this narrowing. */
6087 /* ... or signedness changes for division or modulus,
6088 then we cannot pass through this conversion. */
6092 /* ... or has undefined overflow while the converted to
6093 type has not, we cannot do the operation in the inner type
6094 as that would introduce undefined overflow. */
6100 /* Pass the constant down and see if we can make a simplification. If
6101 we can, replace this expression with the inner simplification for
6102 possible later conversion to our or some other type. */
6107 code == MULT_EXPR
6109 strict_overflow_p))))
6114 /* If widening the type changes it from signed to unsigned, then we
6115 must avoid building ABS_EXPR itself as unsigned. */
6117 {
6121 {
6124 }
6126 }
6127 /* If the constant is negative, we cannot simplify this. */
6130 /* FALLTHROUGH */
6132 /* For division and modulus, type can't be unsigned, as e.g.
6133 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6134 For signed types, even with wrapping overflow, this is fine. */
6143 /* If widening the type changes the signedness, then we can't perform
6144 this optimization as that changes the result. */
6148 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6154 {
6161 }
6165 /* If the second operand is constant, this is a multiplication
6166 or floor division, by a power of two, so we can treat it that
6167 way unless the multiplier or divisor overflows. Signed
6168 left-shift overflow is implementation-defined rather than
6169 undefined in C90, so do not convert signed left shift into
6170 multiplication. */
6173 /* const_binop may not detect overflow correctly,
6174 so check for it explicitly here. */
6178 size_one_node,
6179 op1)))
6183 ctype,
6185 t1),
6190 /* See if we can eliminate the operation on both sides. If we can, we
6191 can return a new PLUS or MINUS. If we can't, the only remaining
6192 cases where we can do anything are if the second operand is a
6193 constant. */
6200 /* If not multiplication, we can only do this if both operands
6201 are divisible by c. */
6204 {
6209 }
6211 /* If this was a subtraction, negate OP1 and set it to be an addition.
6212 This simplifies the logic below. */
6214 {
6216 /* If OP1 was not easily negatable, the constant may be OP0. */
6218 {
6221 }
6222 }
6227 /* If either OP1 or C are negative, this optimization is not safe for
6228 some of the division and remainder types while for others we need
6229 to change the code. */
6231 {
6239 }
6241 /* If it's a multiply or a division/modulus operation of a multiple
6242 of our constant, do the operation and verify it doesn't overflow. */
6245 {
6248 /* We allow the constant to overflow with wrapping semantics. */
6252 }
6253 else
6256 /* If we have an unsigned type, we cannot widen the operation since it
6257 will change the result if the original computation overflowed. */
6261 /* The last case is if we are a multiply. In that case, we can
6262 apply the distributive law to commute the multiply and addition
6263 if the multiplication of the constants doesn't overflow
6264 and overflow is defined. With undefined overflow
6265 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6271 op1);
6276 /* We have a special case here if we are doing something like
6277 (C * 8) % 4 since we know that's zero. */
6280 /* If the multiplication can overflow we cannot optimize this. */
6284 {
6287 }
6289 /* ... fall through ... */
6293 /* If we can extract our operation from the LHS, do so and return a
6294 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6295 do something only if the second operand is a constant. */
6311 /* If these are the same operation types, we can associate them
6312 assuming no overflow. */
6314 {
6329 }
6331 /* If these operations "cancel" each other, we have the main
6332 optimizations of this pass, which occur when either constant is a
6333 multiple of the other, in which case we replace this with either an
6334 operation or CODE or TCODE.
6336 If we have an unsigned type, we cannot do this since it will change
6337 the result if the original computation overflowed. */
6344 {
6346 {
6353 }
6355 {
6362 }
6363 }
6368 }
6371 }
6372 \f
6373 /* Return a node which has the indicated constant VALUE (either 0 or
6374 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6375 and is of the indicated TYPE. */
6377 tree
6379 {
6388 else
6390 }
6393 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6394 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6395 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6396 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6397 COND is the first argument to CODE; otherwise (as in the example
6398 given here), it is the second argument. TYPE is the type of the
6399 original expression. Return NULL_TREE if no simplification is
6400 possible. */
6402 static tree
6407 {
6417 {
6421 /* If this operand throws an expression, then it does not make
6422 sense to try to perform a logical or arithmetic operation
6423 involving it. */
6428 }
6431 {
6436 }
6437 else
6438 /* Detect the case of mixing vector and scalar types - bail out. */
6444 /* This transformation is only worthwhile if we don't have to wrap ARG
6445 in a SAVE_EXPR and the operation can be simplified without recursing
6446 on at least one of the branches once its pushed inside the COND_EXPR. */
6455 {
6459 else
6461 }
6463 {
6467 else
6469 }
6471 /* Check that we have simplified at least one of the branches. */
6476 }
6478 \f
6479 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6481 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6482 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6483 ADDEND is the same as X.
6485 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6486 and finite. The problematic cases are when X is zero, and its mode
6487 has signed zeros. In the case of rounding towards -infinity,
6488 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6489 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6491 bool
6493 {
6497 /* Don't allow the fold with -fsignaling-nans. */
6501 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6505 /* In a vector or complex, we would need to check the sign of all zeros. */
6509 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6513 /* The mode has signed zeros, and we have to honor their sign.
6514 In this situation, there is only one case we can return true for.
6515 X - 0 is the same as X unless rounding towards -infinity is
6516 supported. */
6518 }
6520 /* Subroutine of match.pd that optimizes comparisons of a division by
6521 a nonzero integer constant against an integer constant, i.e.
6522 X/C1 op C2.
6524 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6525 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6527 enum tree_code
6530 {
6535 /* We have to do this the hard way to detect unsigned overflow.
6536 prod = int_const_binop (MULT_EXPR, c1, c2); */
6542 {
6546 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6549 }
6551 {
6554 {
6573 }
6574 }
6575 else
6576 {
6577 /* A negative divisor reverses the relational operators. */
6582 {
6601 }
6602 }
6615 }
6618 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6619 equality/inequality test, then return a simplified form of the test
6620 using a sign testing. Otherwise return NULL. TYPE is the desired
6621 result type. */
6623 static tree
6626 tree result_type)
6627 {
6628 /* If this is testing a single bit, we can optimize the test. */
6632 {
6633 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6634 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6638 /* This is only a win if casting to a signed type is cheap,
6639 i.e. when arg00's type is not a partial mode. */
6641 {
6644 result_type,
6647 }
6648 }
6651 }
6653 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6654 equality/inequality test, then return a simplified form of
6655 the test using shifts and logical operations. Otherwise return
6656 NULL. TYPE is the desired result type. */
6658 tree
6661 {
6662 /* If this is testing a single bit, we can optimize the test. */
6666 {
6675 /* First, see if we can fold the single bit test into a sign-bit
6676 test. */
6678 result_type);
6682 /* Otherwise we have (A & C) != 0 where C is a single bit,
6683 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6684 Similarly for (A & C) == 0. */
6686 /* If INNER is a right shift of a constant and it plus BITNUM does
6687 not overflow, adjust BITNUM and INNER. */
6693 {
6696 }
6698 /* If we are going to be able to omit the AND below, we must do our
6699 operations as unsigned. If we must use the AND, we have a choice.
6700 Normally unsigned is faster, but for some machines signed is. */
6718 /* Put the AND last so it can combine with more things. */
6721 /* Make sure to return the proper type. */
6725 }
6727 }
6729 /* Test whether it is preferable two swap two operands, ARG0 and
6730 ARG1, for example because ARG0 is an integer constant and ARG1
6731 isn't. */
6733 bool
6735 {
6749 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6750 for commutative and comparison operators. Ensuring a canonical
6751 form allows the optimizers to find additional redundancies without
6752 having to explicitly check for both orderings. */
6758 /* Put SSA_NAMEs last. */
6764 /* Put variables last. */
6771 }
6774 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6775 means A >= Y && A != MAX, but in this case we know that
6776 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6778 static tree
6780 {
6787 else
6796 {
6799 }
6801 {
6804 }
6805 else
6812 {
6813 /* Convert the pointer types into integer before taking the difference. */
6817 }
6818 else
6825 }
6827 /* Fold a sum or difference of at least one multiplication.
6828 Returns the folded tree or NULL if no simplification could be made. */
6830 static tree
6833 {
6837 /* (A * C) +- (B * C) -> (A+-B) * C.
6838 (A * C) +- A -> A * (C+-1).
6839 We are most concerned about the case where C is a constant,
6840 but other combinations show up during loop reduction. Since
6841 it is not difficult, try all four possibilities. */
6844 {
6847 }
6849 {
6852 }
6853 else
6854 {
6855 /* We cannot generate constant 1 for fract. */
6860 }
6862 {
6865 }
6867 {
6869 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6870 the purpose of this canonicalization. */
6874 {
6877 }
6878 else
6880 }
6881 else
6882 {
6883 /* We cannot generate constant 1 for fract. */
6888 }
6891 /* Prefer factoring a common non-constant. */
6901 /* No identical multiplicands; see if we can find a common
6902 power-of-two factor in non-power-of-two multiplies. This
6903 can help in multi-dimensional array access. */
6906 {
6909 tree maybe_same;
6913 /* Move min of absolute values to int11. */
6915 {
6920 }
6921 else
6925 /* The remainder should not be a constant, otherwise we
6926 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6927 increased the number of multiplications necessary. */
6929 {
6937 }
6938 }
6945 /* We are neither factoring zero nor minus one. */
6953 /* Same may be zero and thus the operation 'code' may overflow. Likewise
6954 same may be minus one and thus the multiplication may overflow. Perform
6955 the operations in an unsigned type. */
6960 /* If the sum evaluated to a constant that is not -INF the multiplication
6961 cannot overflow. */
6970 }
6972 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6973 specified by EXPR into the buffer PTR of length LEN bytes.
6974 Return the number of bytes placed in the buffer, or zero
6975 upon failure. */
6977 static int
6979 {
6991 /* Dry run. */
6997 {
6999 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7000 number of bytes. */
7004 {
7011 else
7013 }
7014 else
7018 }
7020 }
7023 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7024 specified by EXPR into the buffer PTR of length LEN bytes.
7025 Return the number of bytes placed in the buffer, or zero
7026 upon failure. */
7028 static int
7030 {
7034 FIXED_VALUE_TYPE value;
7049 }
7052 /* Subroutine of native_encode_expr. Encode the REAL_CST
7053 specified by EXPR into the buffer PTR of length LEN bytes.
7054 Return the number of bytes placed in the buffer, or zero
7055 upon failure. */
7057 static int
7059 {
7065 /* There are always 32 bits in each long, no matter the size of
7066 the hosts long. We handle floating point representations with
7067 up to 192 bits. */
7076 /* Dry run. */
7085 {
7090 {
7097 else
7099 }
7100 else
7101 {
7104 {
7105 /* Reverse bytes within each long, or within the entire float
7106 if it's smaller than a long (for HFmode). */
7109 }
7110 }
7115 }
7117 }
7119 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7120 specified by EXPR into the buffer PTR of length LEN bytes.
7121 Return the number of bytes placed in the buffer, or zero
7122 upon failure. */
7124 static int
7126 {
7128 tree part;
7142 }
7145 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7146 specified by EXPR into the buffer PTR of length LEN bytes.
7147 Return the number of bytes placed in the buffer, or zero
7148 upon failure. */
7150 static int
7152 {
7162 {
7164 {
7167 }
7178 }
7180 }
7183 /* Subroutine of native_encode_expr. Encode the STRING_CST
7184 specified by EXPR into the buffer PTR of length LEN bytes.
7185 Return the number of bytes placed in the buffer, or zero
7186 upon failure. */
7188 static int
7190 {
7193 /* Wide-char strings are encoded in target byte-order so native
7194 encoding them is trivial. */
7209 {
7212 {
7215 }
7218 }
7219 else
7222 }
7225 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7226 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7227 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7228 anything, just do a dry run. If OFF is not -1 then start
7229 the encoding at byte offset OFF and encode at most LEN bytes.
7230 Return the number of bytes placed in the buffer, or zero upon failure. */
7232 int
7234 {
7235 /* We don't support starting at negative offset and -1 is special. */
7240 {
7261 }
7262 }
7265 /* Subroutine of native_interpret_expr. Interpret the contents of
7266 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7267 If the buffer cannot be interpreted, return NULL_TREE. */
7269 static tree
7271 {
7281 }
7284 /* Subroutine of native_interpret_expr. Interpret the contents of
7285 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7286 If the buffer cannot be interpreted, return NULL_TREE. */
7288 static tree
7290 {
7293 double_int result;
7294 FIXED_VALUE_TYPE fixed_value;
7304 }
7307 /* Subroutine of native_interpret_expr. Interpret the contents of
7308 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7309 If the buffer cannot be interpreted, return NULL_TREE. */
7311 static tree
7313 {
7317 /* There are always 32 bits in each long, no matter the size of
7318 the hosts long. We handle floating point representations with
7319 up to 192 bits. */
7320 REAL_VALUE_TYPE r;
7330 {
7331 /* Both OFFSET and BYTE index within a long;
7332 bitpos indexes the whole float. */
7335 {
7342 else
7344 }
7345 else
7346 {
7349 {
7350 /* Reverse bytes within each long, or within the entire float
7351 if it's smaller than a long (for HFmode). */
7354 }
7355 }
7359 }
7363 }
7366 /* Subroutine of native_interpret_expr. Interpret the contents of
7367 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7368 If the buffer cannot be interpreted, return NULL_TREE. */
7370 static tree
7372 {
7387 }
7390 /* Subroutine of native_interpret_expr. Interpret the contents of
7391 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7392 If the buffer cannot be interpreted, return NULL_TREE. */
7394 static tree
7396 {
7408 {
7413 }
7415 }
7418 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7419 the buffer PTR of length LEN as a constant of type TYPE. For
7420 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7421 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7422 return NULL_TREE. */
7424 tree
7426 {
7428 {
7450 }
7451 }
7453 /* Returns true if we can interpret the contents of a native encoding
7454 as TYPE. */
7456 static bool
7458 {
7460 {
7473 }
7474 }
7477 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7478 TYPE at compile-time. If we're unable to perform the conversion
7479 return NULL_TREE. */
7481 static tree
7483 {
7484 /* We support up to 512-bit values (for V8DFmode). */
7488 /* Check that the host and target are sane. */
7497 }
7499 /* Build an expression for the address of T. Folds away INDIRECT_REF
7500 to avoid confusing the gimplify process. */
7502 tree
7504 {
7505 /* The size of the object is not relevant when talking about its address. */
7510 {
7515 }
7525 {
7530 }
7531 else
7535 }
7537 /* Build an expression for the address of T. */
7539 tree
7541 {
7545 }
7547 /* Fold a unary expression of code CODE and type TYPE with operand
7548 OP0. Return the folded expression if folding is successful.
7549 Otherwise, return NULL_TREE. */
7551 tree
7553 {
7554 tree tem;
7555 tree arg0;
7563 {
7566 {
7567 /* Don't use STRIP_NOPS, because signedness of argument type
7568 matters. */
7570 }
7571 else
7572 {
7573 /* Strip any conversions that don't change the mode. This
7574 is safe for every expression, except for a comparison
7575 expression because its signedness is derived from its
7576 operands.
7578 Note that this is done as an internal manipulation within
7579 the constant folder, in order to find the simplest
7580 representation of the arguments so that their form can be
7581 studied. In any cases, the appropriate type conversions
7582 should be put back in the tree that will get out of the
7583 constant folder. */
7585 }
7588 {
7591 {
7595 }
7596 }
7597 }
7604 {
7611 {
7625 /* If this was a conversion, and all we did was to move into
7626 inside the COND_EXPR, bring it back out. But leave it if
7627 it is a conversion from integer to integer and the
7628 result precision is no wider than a word since such a
7629 conversion is cheap and may be optimized away by combine,
7630 while it couldn't if it were outside the COND_EXPR. Then return
7631 so we don't get into an infinite recursion loop taking the
7632 conversion out and then back in. */
7644 && (INTEGRAL_TYPE_P
7657 }
7658 }
7661 {
7667 CASE_CONVERT:
7671 {
7672 /* If we have (type) (a CMP b) and type is an integral type, return
7673 new expression involving the new type. Canonicalize
7674 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7675 non-integral type.
7676 Do not fold the result as that would not simplify further, also
7677 folding again results in recursions. */
7687 }
7689 /* Handle (T *)&A.B.C for A being of type T and B and C
7690 living at offset zero. This occurs frequently in
7691 C++ upcasting and then accessing the base. */
7695 {
7697 tree offset;
7698 machine_mode mode;
7700 tree base
7704 /* If the reference was to a (constant) zero offset, we can use
7705 the address of the base if it has the same base type
7706 as the result type and the pointer type is unqualified. */
7713 }
7717 /* Detect assigning a bitfield. */
7719 && DECL_BIT_FIELD
7721 {
7722 /* Don't leave an assignment inside a conversion
7723 unless assigning a bitfield. */
7725 /* First do the assignment, then return converted constant. */
7730 }
7732 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7733 constants (if x has signed type, the sign bit cannot be set
7734 in c). This folds extension into the BIT_AND_EXPR.
7735 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7736 very likely don't have maximal range for their precision and this
7737 transformation effectively doesn't preserve non-maximal ranges. */
7741 {
7752 <= HOST_BITS_PER_WIDE_INT
7754 {
7758 cst &= HOST_WIDE_INT_M1U
7762 && !flag_syntax_only
7765 {
7769 }
7770 }
7772 {
7777 }
7778 }
7780 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7781 cast (T1)X will fold away. We assume that this happens when X itself
7782 is a cast. */
7786 {
7790 return fold_build_pointer_plus_loc
7792 }
7794 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7795 of the same precision, and X is an integer type not narrower than
7796 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7802 {
7808 }
7810 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7811 type of X and Y (integer types only). */
7816 {
7817 /* Be careful not to introduce new overflows. */
7818 tree mult_type;
7821 else
7825 {
7832 }
7833 }
7839 {
7846 }
7857 /* Convert fabs((double)float) into (double)fabsf(float). */
7860 {
7866 targ0));
7867 }
7871 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7890 /* Note that the operand of this must be an int
7891 and its values must be 0 or 1.
7892 ("true" is a fixed value perhaps depending on the language,
7893 but we don't handle values other than 1 correctly yet.) */
7900 /* Fold *&X to X if X is an lvalue. */
7902 {
7909 }
7915 }
7918 /* If the operation was a conversion do _not_ mark a resulting constant
7919 with TREE_OVERFLOW if the original constant was not. These conversions
7920 have implementation defined behavior and retaining the TREE_OVERFLOW
7921 flag here would confuse later passes such as VRP. */
7922 tree
7925 {
7934 }
7936 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7937 operands OP0 and OP1. LOC is the location of the resulting expression.
7938 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7939 Return the folded expression if folding is successful. Otherwise,
7940 return NULL_TREE. */
7941 static tree
7944 {
7945 tree tem;
7947 /* We only do these simplifications if we are optimizing. */
7951 /* Check for things like (A || B) && (A || C). We can convert this
7952 to A || (B && C). Note that either operator can be any of the four
7953 truth and/or operations and the transformation will still be
7954 valid. Also note that we only care about order for the
7955 ANDIF and ORIF operators. If B contains side effects, this
7956 might change the truth-value of A. */
7963 {
7983 /* This case if tricky because we must either have commutative
7984 operators or else A10 must not have side-effects. */
7990 a01);
7991 }
7993 /* See if we can build a range comparison. */
7999 {
8003 }
8007 {
8011 }
8013 /* Check for the possibility of merging component references. If our
8014 lhs is another similar operation, try to merge its rhs with our
8015 rhs. Then try to merge our lhs and rhs. */
8025 && !flag_sanitize_coverage
8030 {
8037 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8038 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8039 We don't want to pack more than two leafs to a non-IF AND/OR
8040 expression.
8041 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8042 equal to IF-CODE, then we don't want to add right-hand operand.
8043 If the inner right-hand side of left-hand operand has
8044 side-effects, or isn't simple, then we can't add to it,
8045 as otherwise we might destroy if-sequence. */
8048 /* Needed for sequence points to handle trappings, and
8049 side-effects. */
8051 {
8053 arg1);
8055 tem);
8056 }
8057 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8058 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8061 /* Needed for sequence points to handle trappings, and
8062 side-effects. */
8064 {
8069 }
8070 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8071 into (A OR B).
8072 For sequence point consistancy, we need to check for trapping,
8073 and side-effects. */
8077 }
8080 }
8082 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8083 by changing CODE to reduce the magnitude of constants involved in
8084 ARG0 of the comparison.
8085 Returns a canonicalized comparison tree if a simplification was
8086 possible, otherwise returns NULL_TREE.
8087 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8088 valid if signed overflow is undefined. */
8090 static tree
8094 {
8099 /* Match A +- CST code arg1. We can change this only if overflow
8100 is undefined. */
8103 /* In principle pointers also have undefined overflow behavior,
8104 but that causes problems elsewhere. */
8111 /* Identify the constant in arg0 and its sign. */
8115 /* Overflowed constants and zero will cause problems. */
8120 /* See if we can reduce the magnitude of the constant in
8121 arg0 by changing the comparison code. */
8122 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8126 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8130 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8134 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8138 else
8142 /* Now build the constant reduced in magnitude. But not if that
8143 would produce one outside of its types range. */
8159 }
8161 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8162 overflow further. Try to decrease the magnitude of constants involved
8163 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8164 and put sole constants at the second argument position.
8165 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8167 static tree
8170 {
8171 tree t;
8176 /* Try canonicalization by simplifying arg0. */
8181 {
8185 }
8187 /* Try canonicalization by simplifying arg1 using the swapped
8188 comparison. */
8196 }
8198 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8199 space. This is used to avoid issuing overflow warnings for
8200 expressions like &p->x which can not wrap. */
8202 static bool
8204 {
8211 wide_int wi_offset;
8217 else
8233 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8234 array. */
8236 {
8237 HOST_WIDE_INT base_size;
8242 }
8245 }
8247 /* Return a positive integer when the symbol DECL is known to have
8248 a nonzero address, zero when it's known not to (e.g., it's a weak
8249 symbol), and a negative integer when the symbol is not yet in the
8250 symbol table and so whether or not its address is zero is unknown.
8251 For function local objects always return positive integer. */
8252 static int
8254 {
8259 /* Function local objects are never NULL. */
8267 }
8269 /* Subroutine of fold_binary. This routine performs all of the
8270 transformations that are common to the equality/inequality
8271 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8272 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8273 fold_binary should call fold_binary. Fold a comparison with
8274 tree code CODE and type TYPE with operands OP0 and OP1. Return
8275 the folded comparison or NULL_TREE. */
8277 static tree
8280 {
8290 /* For comparisons of pointers we can decompose it to a compile time
8291 comparison of the base objects and the offsets into the object.
8292 This requires at least one operand being an ADDR_EXPR or a
8293 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8299 {
8302 machine_mode mode;
8306 /* Get base and offset for the access. Strip ADDR_EXPR for
8307 get_inner_reference, but put it back by stripping INDIRECT_REF
8308 off the base object if possible. indirect_baseN will be true
8309 if baseN is not an address but refers to the object itself. */
8312 {
8313 base0
8319 else
8321 }
8323 {
8327 {
8328 base0
8334 else
8336 }
8339 else
8343 {
8349 {
8352 }
8353 }
8354 }
8358 {
8359 base1
8365 else
8367 }
8369 {
8373 {
8374 base1
8380 else
8382 }
8385 else
8389 {
8395 {
8398 }
8399 }
8400 }
8402 /* If we have equivalent bases we might be able to simplify. */
8406 {
8407 /* We can fold this expression to a constant if the non-constant
8408 offset parts are equal. */
8412 {
8418 "occur when comparing P +- C1 with "
8420 WARN_STRICT_OVERFLOW_CONDITIONAL);
8423 {
8437 }
8438 }
8439 /* We can simplify the comparison to a comparison of the variable
8440 offset parts if the constant offset parts are equal.
8441 Be careful to use signed sizetype here because otherwise we
8442 mess with array offsets in the wrong way. This is possible
8443 because pointer arithmetic is restricted to retain within an
8444 object and overflow on pointer differences is undefined as of
8445 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8447 {
8448 /* By converting to signed sizetype we cover middle-end pointer
8449 arithmetic which operates on unsigned pointer types of size
8450 type size and ARRAY_REF offsets which are properly sign or
8451 zero extended from their type in case it is narrower than
8452 sizetype. */
8455 else
8459 else
8466 "occur when comparing P +- C1 with "
8468 WARN_STRICT_OVERFLOW_COMPARISON);
8471 }
8472 }
8473 /* For equal offsets we can simplify to a comparison of the
8474 base addresses. */
8476 && (indirect_base0
8478 && (indirect_base1
8483 {
8489 }
8490 /* Comparison between an ordinary (non-weak) symbol and a null
8491 pointer can be eliminated since such symbols must have a non
8492 null address. In C, relational expressions between pointers
8493 to objects and null pointers are undefined. The results
8494 below follow the C++ rules with the additional property that
8495 every object pointer compares greater than a null pointer.
8496 */
8499 /* Avoid folding references to struct members at offset 0 to
8500 prevent tests like '&ptr->firstmember == 0' from getting
8501 eliminated. When ptr is null, although the -> expression
8502 is strictly speaking invalid, GCC retains it as a matter
8503 of QoI. See PR c/44555. */
8506 && indirect_base0
8507 /* The caller guarantees that when one of the arguments is
8508 constant (i.e., null in this case) it is second. */
8510 {
8512 {
8523 }
8524 }
8525 }
8527 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8528 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8529 the resulting offset is smaller in absolute value than the
8530 original one and has the same sign. */
8539 {
8544 tree cst;
8546 "occur when combining constants around "
8549 /* Put the constant on the side where it doesn't overflow and is
8550 of lower absolute value and of same sign than before. */
8557 {
8560 variable1,
8564 }
8572 {
8578 variable2);
8579 }
8580 }
8586 /* If we are comparing an expression that just has comparisons
8587 of two integer values, arithmetic expressions of those comparisons,
8588 and constants, we can simplify it. There are only three cases
8589 to check: the two values can either be equal, the first can be
8590 greater, or the second can be greater. Fold the expression for
8591 those three values. Since each value must be 0 or 1, we have
8592 eight possibilities, each of which corresponds to the constant 0
8593 or 1 or one of the six possible comparisons.
8595 This handles common cases like (a > b) == 0 but also handles
8596 expressions like ((x > y) - (y > x)) > 0, which supposedly
8597 occur in macroized code. */
8600 {
8605 /* Don't handle degenerate cases here; they should already
8606 have been handled anyway. */
8615 {
8619 /* We can't just pass T to eval_subst in case cval1 or cval2
8620 was the same as ARG1. */
8622 tree high_result
8626 arg1);
8627 tree equal_result
8631 arg1);
8632 tree low_result
8636 arg1);
8638 /* All three of these results should be 0 or 1. Confirm they are.
8639 Then use those values to select the proper code to use. */
8644 {
8645 /* Make a 3-bit mask with the high-order bit being the
8646 value for `>', the next for '=', and the low for '<'. */
8650 {
8652 /* Always false. */
8673 /* Always true. */
8675 }
8678 {
8682 }
8684 }
8685 }
8686 }
8689 }
8692 /* Subroutine of fold_binary. Optimize complex multiplications of the
8693 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8694 argument EXPR represents the expression "z" of type TYPE. */
8696 static tree
8698 {
8703 {
8706 }
8708 {
8711 }
8712 else
8713 {
8717 }
8726 }
8729 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8730 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8731 true if successful. */
8733 static bool
8735 {
8739 {
8742 }
8744 {
8750 else
8752 }
8753 else
8759 }
8761 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8762 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8763 NULL_TREE otherwise. */
8765 static tree
8767 {
8786 {
8790 }
8793 {
8799 }
8800 else
8802 }
8804 /* Try to fold a pointer difference of type TYPE two address expressions of
8805 array references AREF0 and AREF1 using location LOC. Return a
8806 simplified expression for the difference or NULL_TREE. */
8808 static tree
8811 {
8816 /* If the bases are array references as well, recurse. If the bases
8817 are pointer indirections compute the difference of the pointers.
8818 If the bases are equal, we are set. */
8821 && (base_offset
8825 && (base_offset
8831 {
8837 base_offset,
8840 }
8842 }
8844 /* If the real or vector real constant CST of type TYPE has an exact
8845 inverse, return it, else return NULL. */
8847 tree
8849 {
8850 REAL_VALUE_TYPE r;
8851 tree unit_type;
8852 machine_mode mode;
8856 {
8866 {
8873 {
8878 }
8881 }
8885 }
8886 }
8888 /* Mask out the tz least significant bits of X of type TYPE where
8889 tz is the number of trailing zeroes in Y. */
8890 static wide_int
8892 {
8897 }
8899 /* Return true when T is an address and is known to be nonzero.
8900 For floating point we further ensure that T is not denormal.
8901 Similar logic is present in nonzero_address in rtlanal.h.
8903 If the return value is based on the assumption that signed overflow
8904 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8905 change *STRICT_OVERFLOW_P. */
8907 static bool
8909 {
8913 /* Doing something useful for floating point would need more work. */
8919 {
8922 strict_overflow_p);
8928 strict_overflow_p);
8936 }
8939 {
8942 strict_overflow_p);
8950 strict_overflow_p);
8965 strict_overflow_p);
8969 strict_overflow_p);
8972 {
8984 }
8988 }
8990 }
8992 /* Return true when T is an address and is known to be nonzero.
8993 Handle warnings about undefined signed overflow. */
8995 bool
8997 {
9004 "determining that expression is always "
9006 WARN_STRICT_OVERFLOW_MISC);
9008 }
9010 /* Return true if T is known not to be equal to an integer W. */
9012 bool
9014 {
9016 value_range_type rtype;
9018 {
9027 {
9032 }
9037 /* If T has some known zero bits and W has any of those bits set,
9038 then T is known not to be equal to W. */
9046 }
9047 }
9049 /* Fold a binary expression of code CODE and type TYPE with operands
9050 OP0 and OP1. LOC is the location of the resulting expression.
9051 Return the folded expression if folding is successful. Otherwise,
9052 return NULL_TREE. */
9054 tree
9057 {
9072 /* Strip any conversions that don't change the mode. This is
9073 safe for every expression, except for a comparison expression
9074 because its signedness is derived from its operands. So, in
9075 the latter case, only strip conversions that don't change the
9076 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9077 preserved.
9079 Note that this is done as an internal manipulation within the
9080 constant folder, in order to find the simplest representation
9081 of the arguments so that their form can be studied. In any
9082 cases, the appropriate type conversions should be put back in
9083 the tree that will get out of the constant folder. */
9086 {
9089 }
9090 else
9091 {
9094 }
9096 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9097 constant but we can't do arithmetic on them. */
9099 {
9102 {
9106 }
9107 }
9109 /* If this is a commutative operation, and ARG0 is a constant, move it
9110 to ARG1 to reduce the number of tests below. */
9115 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9116 to ARG1 to reduce the number of tests below. */
9125 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9127 First check for cases where an arithmetic operation is applied to a
9128 compound, conditional, or comparison operation. Push the arithmetic
9129 operation inside the compound or conditional to see if any folding
9130 can then be done. Convert comparison to conditional for this purpose.
9131 The also optimizes non-constant cases that used to be done in
9132 expand_expr.
9134 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9135 one of the operands is a comparison and the other is a comparison, a
9136 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9137 code below would make the expression more complex. Change it to a
9138 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9139 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9152 {
9156 boolean_type_node,
9164 }
9168 {
9170 {
9175 tem);
9176 }
9178 {
9183 tem);
9184 }
9189 {
9195 }
9200 {
9206 }
9207 }
9210 {
9212 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9215 {
9221 }
9223 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9226 {
9227 tree base;
9228 HOST_WIDE_INT coffset;
9237 }
9242 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9248 arg1),
9250 arg0)));
9256 {
9257 /* X + (X / CST) * -CST is X % CST. */
9262 {
9271 cst0));
9272 }
9273 }
9275 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9276 one. Make sure the type is not saturating and has the signedness of
9277 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9278 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9285 {
9289 }
9292 {
9293 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9294 (plus (plus (mult) (mult)) (foo)) so that we can
9295 take advantage of the factoring cases below. */
9304 {
9310 else
9323 parg0),
9325 marg)),
9329 return
9335 parg1)));
9336 }
9337 }
9338 else
9339 {
9340 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9341 to __complex__ ( x, y ). This is not the same for SNaNs or
9342 if signed zeros are involved. */
9346 {
9353 {
9357 {
9363 }
9365 {
9371 }
9372 }
9373 }
9381 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9382 We associate floats only if the user has specified
9383 -fassociative-math. */
9387 {
9392 {
9393 tree tree0;
9396 }
9397 }
9398 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9399 We associate floats only if the user has specified
9400 -fassociative-math. */
9404 {
9409 {
9410 tree tree0;
9413 }
9414 }
9415 }
9417 bit_rotate:
9418 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9419 is a rotate of A by C1 bits. */
9420 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9421 is a rotate of A by B bits. */
9422 {
9424 tree rtype;
9433 /* Only create rotates in complete modes. Other cases are not
9434 expanded properly. */
9437 {
9451 {
9455 code0 == LSHIFT_EXPR
9459 }
9461 {
9469 element_precision
9473 return
9476 ? LROTATE_EXPR
9481 }
9483 {
9491 element_precision
9495 return fold_convert_loc
9498 ? LROTATE_EXPR
9502 }
9503 }
9504 }
9506 associate:
9507 /* In most languages, can't associate operations on floats through
9508 parentheses. Rather than remember where the parentheses were, we
9509 don't associate floats at all, unless the user has specified
9510 -fassociative-math.
9511 And, we need to make sure type is not saturating. */
9515 {
9521 /* Split both trees into variables, constants, and literals. Then
9522 associate each group together, the constants with literals,
9523 then the result with variables. This increases the chances of
9524 literals being recombined later and of generating relocatable
9525 expressions for the sum of a constant and literal. */
9533 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9537 /* With undefined overflow prefer doing association in a type
9538 which wraps on overflow, if that is one of the operand types. */
9541 {
9549 }
9551 /* With undefined overflow we can only associate constants with one
9552 variable, and constants whose association doesn't overflow. */
9555 {
9557 {
9558 /* ??? If split_tree would handle NEGATE_EXPR we could
9559 simply reject these cases and the allowed cases would
9560 be the var0/minus_var1 ones. */
9566 {
9569 }
9576 {
9579 }
9585 /* The only case we can still associate with two variables
9586 is if they cancel out. */
9590 }
9596 }
9598 /* Only do something if we found more than two objects. Otherwise,
9599 nothing has changed and we risk infinite recursion. */
9607 {
9619 {
9623 }
9625 {
9629 }
9631 /* Preserve the MINUS_EXPR if the negative part of the literal is
9632 greater than the positive part. Otherwise, the multiplicative
9633 folding code (i.e extract_muldiv) may be fooled in case
9634 unsigned constants are subtracted, like in the following
9635 example: ((X*2 + 4) - 8U)/2. */
9637 {
9641 /* But avoid ending up with only negated parts. */
9643 {
9647 }
9648 else
9649 {
9653 }
9654 }
9656 /* Don't introduce overflows through reassociation. */
9661 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9668 /* Eliminate minus_con0. */
9670 {
9677 else
9680 }
9682 /* Eliminate minus_var0. */
9684 {
9688 else
9691 }
9693 return
9696 }
9697 }
9702 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9710 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9711 __complex__ ( x, -y ). This is not the same for SNaNs or if
9712 signed zeros are involved. */
9716 {
9723 {
9727 {
9729 arg1r ? arg1r
9734 }
9736 {
9740 arg1i ? arg1i
9743 }
9744 }
9745 }
9747 /* A - B -> A + (-B) if B is easily negatable. */
9751 /* Avoid this transformation if B is a positive REAL_CST. */
9759 /* Fold &a[i] - &a[j] to i-j. */
9764 {
9770 }
9773 && flag_unsafe_math_optimizations
9779 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9780 one. Make sure the type is not saturating and has the signedness of
9781 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9782 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9789 {
9793 }
9799 {
9800 /* Transform x * -C into -x * C if x is easily negatable. */
9815 {
9818 "occur when simplifying "
9820 WARN_STRICT_OVERFLOW_MISC);
9822 }
9824 /* Optimize z * conj(z) for integer complex numbers. */
9831 }
9832 else
9833 {
9834 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9835 This is not the same for NaNs or if signed zeros are
9836 involved. */
9842 {
9845 return
9851 return
9856 }
9858 /* Optimize z * conj(z) for floating point complex numbers.
9859 Guarded by flag_unsafe_math_optimizations as non-finite
9860 imaginary components don't produce scalar results. */
9869 }
9873 /* Canonicalize (X & C1) | C2. */
9877 {
9882 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9890 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9892 {
9895 }
9897 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9898 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9899 mode which allows further optimizations. */
9904 {
9909 {
9912 }
9913 }
9916 {
9921 }
9922 }
9924 /* See if this can be simplified into a rotate first. If that
9925 is unsuccessful continue in the association code. */
9929 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9937 /* See if this can be simplified into a rotate first. If that
9938 is unsuccessful continue in the association code. */
9942 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9947 {
9948 tree tem2;
9955 }
9956 /* Fold ~X & 1 as (X & 1) == 0. */
9960 {
9961 tree tem2;
9968 }
9969 /* Fold !X & 1 as X == 0. */
9972 {
9976 }
9978 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9979 multiple of 1 << CST. */
9981 {
9988 }
9990 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
9991 bits from CST2. */
9995 {
10003 {
10004 /* Avoid the transform if arg1 is a mask of some
10005 mode which allows further optimizations. */
10012 }
10013 }
10015 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10016 ((A & N) + B) & M -> (A + B) & M
10017 Similarly if (N & M) == 0,
10018 ((A | N) + B) & M -> (A + B) & M
10019 and for - instead of + (or unary - instead of +)
10020 and/or ^ instead of |.
10021 If B is constant and (B & M) == 0, fold into A & M. */
10023 {
10032 {
10035 wide_int cst0;
10037 /* Now we know that arg0 is (C + D) or (C - D) or
10038 -C and arg1 (M) is == (1LL << cst) - 1.
10039 Store C into PMOP[0] and D into PMOP[1]. */
10043 {
10046 }
10053 {
10063 {
10066 }
10069 /* If C or D is of the form (A & N) where
10070 (N & M) == M, or of the form (A | N) or
10071 (A ^ N) where (N & M) == 0, replace it with A. */
10075 /* If C or D is a N where (N & M) == 0, it can be
10076 omitted (assumed 0). */
10084 }
10086 /* Only build anything new if we optimized one or both arguments
10087 above. */
10091 {
10094 {
10095 /* Perform the operations in a type that has defined
10096 overflow behavior. */
10102 }
10107 {
10115 else
10117 }
10120 else
10123 /* TEM is now the new binary +, - or unary - replacement. */
10127 }
10128 }
10129 }
10131 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10134 {
10139 return
10141 }
10146 /* Don't touch a floating-point divide by zero unless the mode
10147 of the constant can represent infinity. */
10153 /* (-A) / (-B) -> A / B */
10165 /* Fall through */
10168 /* Simplify A / (B << N) where A and B are positive and B is
10169 a power of 2, to A >> (N + log2(B)). */
10174 {
10177 {
10185 WARN_STRICT_OVERFLOW_MISC);
10191 }
10192 }
10194 /* Fall through */
10202 /* Convert -A / -B to A / B when the type is signed and overflow is
10203 undefined. */
10207 {
10210 "when distributing negation across "
10212 WARN_STRICT_OVERFLOW_MISC);
10217 }
10221 {
10224 "when distributing negation across "
10226 WARN_STRICT_OVERFLOW_MISC);
10231 }
10233 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10234 operation, EXACT_DIV_EXPR.
10236 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10237 At one time others generated faster code, it's not clear if they do
10238 after the last round to changes to the DIV code in expmed.c. */
10249 {
10253 WARN_STRICT_OVERFLOW_MISC);
10255 }
10267 {
10271 WARN_STRICT_OVERFLOW_MISC);
10273 }
10281 /* Since negative shift count is not well-defined,
10282 don't try to compute it in the compiler. */
10288 /* If we have a rotate of a bit operation with the rotate count and
10289 the second operand of the bit operation both constant,
10290 permute the two operations. */
10296 {
10304 }
10306 /* Two consecutive rotates adding up to the some integer
10307 multiple of the precision of the type can be ignored. */
10322 /* Note that the operands of this must be ints
10323 and their values must be 0 or 1.
10324 ("true" is a fixed value perhaps depending on the language.) */
10325 /* If first arg is constant zero, return it. */
10328 /* FALLTHRU */
10330 /* If either arg is constant true, drop it. */
10334 /* Preserve sequence points. */
10337 /* If second arg is constant zero, result is zero, but first arg
10338 must be evaluated. */
10341 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10342 case will be handled here. */
10346 /* !X && X is always false. */
10350 /* X && !X is always false. */
10355 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10356 means A >= Y && A != MAX, but in this case we know that
10357 A < X <= MAX. */
10361 {
10369 }
10378 /* Note that the operands of this must be ints
10379 and their values must be 0 or true.
10380 ("true" is a fixed value perhaps depending on the language.) */
10381 /* If first arg is constant true, return it. */
10384 /* FALLTHRU */
10386 /* If either arg is constant zero, drop it. */
10390 /* Preserve sequence points. */
10393 /* If second arg is constant true, result is true, but we must
10394 evaluate first arg. */
10397 /* Likewise for first arg, but note this only occurs here for
10398 TRUTH_OR_EXPR. */
10402 /* !X || X is always true. */
10406 /* X || !X is always true. */
10411 /* (X && !Y) || (!X && Y) is X ^ Y */
10414 {
10431 }
10440 /* If the second arg is constant zero, drop it. */
10443 /* If the second arg is constant true, this is a logical inversion. */
10445 {
10448 }
10449 /* Identical arguments cancel to zero. */
10453 /* !X ^ X is always true. */
10458 /* X ^ !X is always true. */
10474 /* bool_var != 1 becomes !bool_var. */
10481 /* bool_var == 0 becomes !bool_var. */
10488 /* !exp != 0 becomes !exp */
10493 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10502 {
10508 }
10510 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10519 {
10525 }
10527 /* If this is an EQ or NE comparison with zero and ARG0 is
10528 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10529 two operations, but the latter can be done in one less insn
10530 on machines that have only two-operand insns or on which a
10531 constant cannot be the first operand. */
10534 {
10539 {
10546 arg1);
10547 }
10550 {
10557 arg1);
10558 }
10559 }
10561 /* If this is an NE or EQ comparison of zero against the result of a
10562 signed MOD operation whose second operand is a power of 2, make
10563 the MOD operation unsigned since it is simpler and equivalent. */
10571 {
10581 }
10583 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10584 C1 is a valid shift constant, and C2 is a power of two, i.e.
10585 a single bit. */
10589 == INTEGER_CST
10592 {
10597 /* Check for a valid shift count. */
10599 {
10603 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10604 can be rewritten as (X & (C2 << C1)) != 0. */
10606 {
10611 }
10612 /* Otherwise, for signed (arithmetic) shifts,
10613 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10614 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10618 /* Otherwise, of unsigned (logical) shifts,
10619 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10620 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10621 else
10625 arg000);
10626 }
10627 }
10629 /* If this is a comparison of a field, we may be able to simplify it. */
10632 /* Handle the constant case even without -O
10633 to make sure the warnings are given. */
10635 {
10639 }
10641 /* Optimize comparisons of strlen vs zero to a compare of the
10642 first character of the string vs zero. To wit,
10643 strlen(ptr) == 0 => *ptr == 0
10644 strlen(ptr) != 0 => *ptr != 0
10645 Other cases should reduce to one of these two (or a constant)
10646 due to the return value of strlen being unsigned. */
10649 {
10657 {
10662 }
10663 }
10665 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10666 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10670 {
10675 {
10677 {
10680 }
10683 }
10684 }
10686 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10687 (X & C) == 0 when C is a single bit. */
10692 {
10699 arg1));
10700 }
10702 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10703 constant C is a power of two, i.e. a single bit. */
10710 {
10714 }
10716 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10717 when is C is a power of two, i.e. a single bit. */
10724 {
10730 }
10734 {
10737 }
10739 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10742 {
10750 {
10756 }
10758 {
10764 }
10766 {
10772 }
10774 {
10780 }
10781 }
10785 {
10792 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10793 operand_equal_p guarantees no side-effects so we don't need
10794 to use omit_one_operand on Z. */
10798 arg10));
10802 arg11));
10806 arg10));
10810 arg11));
10812 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10815 {
10821 }
10822 }
10824 /* Attempt to simplify equality/inequality comparisons of complex
10825 values. Only lower the comparison if the result is known or
10826 can be simplified to a single scalar comparison. */
10831 {
10836 {
10839 }
10840 else
10841 {
10844 }
10847 {
10850 }
10851 else
10852 {
10855 }
10859 {
10861 {
10866 }
10867 else
10868 {
10873 }
10874 }
10878 {
10880 {
10885 }
10886 else
10887 {
10892 }
10893 }
10894 }
10906 /* Transform comparisons of the form X +- C CMP X. */
10913 {
10920 else
10923 /* (X - c) > X becomes false. */
10927 {
10931 "occur when assuming that (X - c) > X "
10933 WARN_STRICT_OVERFLOW_ALL);
10935 }
10937 /* Likewise (X + c) < X becomes false. */
10941 {
10945 "occur when assuming that "
10947 WARN_STRICT_OVERFLOW_ALL);
10949 }
10951 /* Convert (X - c) <= X to true. */
10956 {
10960 "occur when assuming that "
10962 WARN_STRICT_OVERFLOW_ALL);
10964 }
10966 /* Convert (X + c) >= X to true. */
10971 {
10975 "occur when assuming that "
10977 WARN_STRICT_OVERFLOW_ALL);
10979 }
10982 {
10983 /* Convert X + c > X and X - c < X to true for integers. */
10987 {
10990 "not occur when assuming that "
10992 WARN_STRICT_OVERFLOW_ALL);
10994 }
10999 {
11002 "not occur when assuming that "
11004 WARN_STRICT_OVERFLOW_ALL);
11006 }
11008 /* Convert X + c <= X and X - c >= X to false for integers. */
11012 {
11015 "not occur when assuming that "
11017 WARN_STRICT_OVERFLOW_ALL);
11019 }
11024 {
11027 "not occur when assuming that "
11029 WARN_STRICT_OVERFLOW_ALL);
11031 }
11032 }
11033 }
11035 /* If we are comparing an ABS_EXPR with a constant, we can
11036 convert all the cases into explicit comparisons, but they may
11037 well not be faster than doing the ABS and one comparison.
11038 But ABS (X) <= C is a range comparison, which becomes a subtraction
11039 and a comparison, and is probably faster. */
11053 /* Convert ABS_EXPR<x> >= 0 to true. */
11060 {
11063 "when simplifying comparison of "
11065 WARN_STRICT_OVERFLOW_CONDITIONAL);
11068 arg0);
11069 }
11071 /* Convert ABS_EXPR<x> < 0 to false. */
11076 {
11079 "when simplifying comparison of "
11081 WARN_STRICT_OVERFLOW_CONDITIONAL);
11084 arg0);
11085 }
11087 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11088 and similarly for >= into !=. */
11098 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11099 otherwise Y might be >= # of bits in X's type and thus e.g.
11100 (unsigned char) (1 << Y) for Y 15 might be 0.
11101 If the cast is widening, then 1 << Y should have unsigned type,
11102 otherwise if Y is number of bits in the signed shift type minus 1,
11103 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11104 31 might be 0xffffffff80000000. */
11115 {
11121 }
11133 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11134 {
11146 }
11151 /* When pedantic, a compound expression can be neither an lvalue
11152 nor an integer constant expression. */
11155 /* Don't let (0, 0) be null pointer constant. */
11161 /* An ASSERT_EXPR should never be passed to fold_binary. */
11167 }
11169 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11170 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11171 of GOTO_EXPR. */
11173 static tree
11175 {
11177 {
11184 /* fall through */
11188 }
11189 }
11191 /* Return whether the sub-tree ST contains a label which is accessible from
11192 outside the sub-tree. */
11194 static bool
11196 {
11197 return
11199 }
11201 /* Fold a ternary expression of code CODE and type TYPE with operands
11202 OP0, OP1, and OP2. Return the folded expression if folding is
11203 successful. Otherwise, return NULL_TREE. */
11205 tree
11208 {
11209 tree tem;
11216 /* If this is a commutative operation, and OP0 is a constant, move it
11217 to OP1 to reduce the number of tests below. */
11226 /* Strip any conversions that don't change the mode. This is safe
11227 for every expression, except for a comparison expression because
11228 its signedness is derived from its operands. So, in the latter
11229 case, only strip conversions that don't change the signedness.
11231 Note that this is done as an internal manipulation within the
11232 constant folder, in order to find the simplest representation of
11233 the arguments so that their form can be studied. In any cases,
11234 the appropriate type conversions should be put back in the tree
11235 that will get out of the constant folder. */
11237 {
11240 }
11243 {
11246 }
11249 {
11252 }
11255 {
11259 {
11265 }
11270 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11271 so all simple results must be passed through pedantic_non_lvalue. */
11273 {
11276 /* Only optimize constant conditions when the selected branch
11277 has the same type as the COND_EXPR. This avoids optimizing
11278 away "c ? x : throw", where the throw has a void type.
11279 Avoid throwing away that operand which contains label. */
11286 }
11288 {
11293 {
11298 {
11306 }
11310 }
11311 }
11313 /* If we have A op B ? A : C, we may be able to convert this to a
11314 simpler expression, depending on the operation and the values
11315 of B and C. Signed zeros prevent all of these transformations,
11316 for reasons given above each one.
11318 Also try swapping the arguments and inverting the conditional. */
11322 {
11326 }
11331 {
11335 {
11339 }
11340 }
11342 /* If the second operand is simpler than the third, swap them
11343 since that produces better jump optimization results. */
11346 {
11348 /* See if this can be inverted. If it can't, possibly because
11349 it was a floating-point inequality comparison, don't do
11350 anything. */
11354 }
11356 /* Convert A ? 1 : 0 to simply A. */
11361 /* If we try to convert OP0 to our type, the
11362 call to fold will try to move the conversion inside
11363 a COND, which will recurse. In that case, the COND_EXPR
11364 is probably the best choice, so leave it alone. */
11368 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11369 over COND_EXPR in cases such as floating point comparisons. */
11378 arg0)));
11380 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11385 {
11386 /* sign_bit_p looks through both zero and sign extensions,
11387 but for this optimization only sign extensions are
11388 usable. */
11391 {
11394 {
11397 }
11399 }
11400 /* sign_bit_p only checks ARG1 bits within A's precision.
11401 If <sign bit of A> has wider type than A, bits outside
11402 of A's precision in <sign bit of A> need to be checked.
11403 If they are all 0, this optimization needs to be done
11404 in unsigned A's type, if they are all 1 in signed A's type,
11405 otherwise this can't be done. */
11411 {
11413 tree tem_type;
11426 {
11429 }
11431 {
11434 }
11435 else
11437 }
11440 return
11446 arg1)));
11447 }
11449 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11450 already handled above. */
11455 {
11465 op1);
11466 }
11468 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11469 is probably obsolete because the first operand should be a
11470 truth value (that's why we have the two cases above), but let's
11471 leave it in until we can confirm this for all front-ends. */
11483 /* Disable the transformations below for vectors, since
11484 fold_binary_op_with_conditional_arg may undo them immediately,
11485 yielding an infinite loop. */
11489 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11498 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11503 {
11505 /* Only perform transformation if ARG0 is easily inverted. */
11509 ? BIT_IOR_EXPR
11512 op1);
11513 }
11515 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11520 {
11522 /* Only perform transformation if ARG0 is easily inverted. */
11528 op2);
11529 }
11531 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11543 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11544 of fold_ternary on them. */
11552 {
11562 {
11567 {
11575 }
11576 }
11577 }
11579 /* On constants we can use native encode/interpret to constant
11580 fold (nearly) all BIT_FIELD_REFs. */
11584 {
11587 /* Limit us to a reasonable amount of work. To relax the
11588 other limitations we need bit-shifting of the buffer
11589 and rounding up the size. */
11593 {
11595 unsigned HOST_WIDE_INT len
11600 {
11605 }
11606 }
11607 }
11612 /* For integers we can decompose the FMA if possible. */
11624 {
11640 {
11645 /* Make sure that the perm value is in an acceptable
11646 range. */
11655 else
11663 }
11666 {
11671 }
11676 {
11681 }
11687 {
11691 }
11696 /* Some targets are deficient and fail to expand a single
11697 argument permutation while still allowing an equivalent
11698 2-argument version. */
11702 {
11705 }
11708 {
11715 }
11719 }
11723 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11726 {
11732 wide_int tem2
11736 }
11741 {
11743 unsigned HOST_WIDE_INT elsize
11746 {
11750 else
11751 {
11759 }
11760 }
11761 }
11767 }
11769 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11770 of an array (or vector). */
11772 tree
11774 {
11779 {
11782 {
11783 /* Static constructors for variably sized objects makes no sense. */
11787 }
11788 }
11799 offset_int max_index;
11804 {
11805 /* Array constructor might explicitly set index, or specify a range,
11806 or leave index NULL meaning that it is next index after previous
11807 one. */
11809 {
11812 else
11813 {
11817 }
11818 }
11819 else
11820 {
11826 }
11828 /* Do we have match? */
11832 }
11834 }
11836 /* Perform constant folding and related simplification of EXPR.
11837 The related simplifications include x*1 => x, x*0 => 0, etc.,
11838 and application of the associative law.
11839 NOP_EXPR conversions may be removed freely (as long as we
11840 are careful not to change the type of the overall expression).
11841 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11842 but we can constant-fold them if they have constant operands. */
11844 #ifdef ENABLE_FOLD_CHECKING
11845 # define fold(x) fold_1 (x)
11847 static
11848 #endif
11849 tree
11851 {
11855 tree tem;
11858 /* Return right away if a constant. */
11862 /* CALL_EXPR-like objects with variable numbers of operands are
11863 treated specially. */
11865 {
11867 {
11870 }
11872 }
11875 {
11880 {
11898 }
11899 }
11902 {
11904 {
11911 {
11916 }
11919 }
11921 /* Return a VECTOR_CST if possible. */
11923 {
11929 tree val;
11935 }
11943 }
11945 #ifdef ENABLE_FOLD_CHECKING
11946 #undef fold
11953 /* When --enable-checking=fold, compute a digest of expr before
11954 and after actual fold call to see if fold did not accidentally
11955 change original expr. */
11957 tree
11959 {
11960 tree ret;
11980 }
11982 void
11984 {
11995 }
11997 static void
11999 {
12001 }
12003 static void
12006 {
12012 recursive_label:
12022 {
12023 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12028 }
12036 {
12037 /* Allow these fields to be modified. */
12038 tree tmp;
12047 {
12050 }
12051 }
12062 {
12065 {
12080 }
12084 {
12097 }
12114 {
12120 }
12123 {
12125 {
12128 }
12130 }
12141 {
12144 }
12154 }
12155 }
12157 /* Helper function for outputting the checksum of a tree T. When
12158 debugging with gdb, you can "define mynext" to be "next" followed
12159 by "call debug_fold_checksum (op0)", then just trace down till the
12160 outputs differ. */
12162 DEBUG_FUNCTION void
12164 {
12179 }
12181 #endif
12183 /* Fold a unary tree expression with code CODE of type TYPE with an
12184 operand OP0. LOC is the location of the resulting expression.
12185 Return a folded expression if successful. Otherwise, return a tree
12186 expression with code CODE of type TYPE with an operand OP0. */
12188 tree
12191 {
12192 tree tem;
12193 #ifdef ENABLE_FOLD_CHECKING
12202 #endif
12208 #ifdef ENABLE_FOLD_CHECKING
12215 #endif
12217 }
12219 /* Fold a binary tree expression with code CODE of type TYPE with
12220 operands OP0 and OP1. LOC is the location of the resulting
12221 expression. Return a folded expression if successful. Otherwise,
12222 return a tree expression with code CODE of type TYPE with operands
12223 OP0 and OP1. */
12225 tree
12228 MEM_STAT_DECL)
12229 {
12230 tree tem;
12231 #ifdef ENABLE_FOLD_CHECKING
12248 #endif
12254 #ifdef ENABLE_FOLD_CHECKING
12269 #endif
12271 }
12273 /* Fold a ternary tree expression with code CODE of type TYPE with
12274 operands OP0, OP1, and OP2. Return a folded expression if
12275 successful. Otherwise, return a tree expression with code CODE of
12276 type TYPE with operands OP0, OP1, and OP2. */
12278 tree
12281 {
12282 tree tem;
12283 #ifdef ENABLE_FOLD_CHECKING
12307 #endif
12314 #ifdef ENABLE_FOLD_CHECKING
12337 #endif
12339 }
12341 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12342 arguments in ARGARRAY, and a null static chain.
12343 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12344 of type TYPE from the given operands as constructed by build_call_array. */
12346 tree
12349 {
12350 tree tem;
12351 #ifdef ENABLE_FOLD_CHECKING
12370 #endif
12376 #ifdef ENABLE_FOLD_CHECKING
12392 #endif
12394 }
12396 /* Perform constant folding and related simplification of initializer
12397 expression EXPR. These behave identically to "fold_buildN" but ignore
12398 potential run-time traps and exceptions that fold must preserve. */
12400 #define START_FOLD_INIT \
12401 int saved_signaling_nans = flag_signaling_nans;\
12402 int saved_trapping_math = flag_trapping_math;\
12403 int saved_rounding_math = flag_rounding_math;\
12404 int saved_trapv = flag_trapv;\
12405 int saved_folding_initializer = folding_initializer;\
12406 flag_signaling_nans = 0;\
12407 flag_trapping_math = 0;\
12408 flag_rounding_math = 0;\
12409 flag_trapv = 0;\
12410 folding_initializer = 1;
12412 #define END_FOLD_INIT \
12413 flag_signaling_nans = saved_signaling_nans;\
12414 flag_trapping_math = saved_trapping_math;\
12415 flag_rounding_math = saved_rounding_math;\
12416 flag_trapv = saved_trapv;\
12417 folding_initializer = saved_folding_initializer;
12419 tree
12422 {
12423 tree result;
12424 START_FOLD_INIT;
12428 END_FOLD_INIT;
12430 }
12432 tree
12435 {
12436 tree result;
12437 START_FOLD_INIT;
12441 END_FOLD_INIT;
12443 }
12445 tree
12448 {
12449 tree result;
12450 START_FOLD_INIT;
12454 END_FOLD_INIT;
12456 }
12458 #undef START_FOLD_INIT
12459 #undef END_FOLD_INIT
12461 /* Determine if first argument is a multiple of second argument. Return 0 if
12462 it is not, or we cannot easily determined it to be.
12464 An example of the sort of thing we care about (at this point; this routine
12465 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12466 fold cases do now) is discovering that
12468 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12470 is a multiple of
12472 SAVE_EXPR (J * 8)
12474 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12476 This code also handles discovering that
12478 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12480 is a multiple of 8 so we don't have to worry about dealing with a
12481 possible remainder.
12483 Note that we *look* inside a SAVE_EXPR only to determine how it was
12484 calculated; it is not safe for fold to do much of anything else with the
12485 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12486 at run time. For example, the latter example above *cannot* be implemented
12487 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12488 evaluation time of the original SAVE_EXPR is not necessarily the same at
12489 the time the new expression is evaluated. The only optimization of this
12490 sort that would be valid is changing
12492 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12494 divided by 8 to
12496 SAVE_EXPR (I) * SAVE_EXPR (J)
12498 (where the same SAVE_EXPR (J) is used in the original and the
12499 transformed version). */
12501 int
12503 {
12514 {
12516 /* Bitwise and provides a power of two multiple. If the mask is
12517 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12520 /* FALLTHRU */
12527 /* It is impossible to prove if op0 - op1 is multiple of bottom
12528 precisely, so be conservative here checking if both op0 and op1
12529 are multiple of bottom. Note we check the second operand first
12530 since it's usually simpler. */
12535 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12536 as op0 - 3 if the expression has unsigned type. For example,
12537 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12547 {
12549 /* const_binop may not detect overflow correctly,
12550 so check for it explicitly here. */
12554 size_one_node,
12555 op1)))
12558 }
12562 /* Can't handle conversions from non-integral or wider integral type. */
12568 /* fall through */
12585 SIGNED);
12591 {
12594 /* Check for special cases to see if top is defined as multiple
12595 of bottom:
12597 top = (X & ~(bottom - 1) ; bottom is power of 2
12599 or
12601 Y = X % bottom
12602 top = X - Y. */
12621 }
12623 /* fall through */
12627 }
12628 }
12630 #define tree_expr_nonnegative_warnv_p(X, Y) \
12633 #define RECURSE(X) \
12634 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12636 /* Return true if CODE or TYPE is known to be non-negative. */
12638 static bool
12640 {
12643 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12644 have a signed:1 type (where the value is -1 and 0). */
12647 }
12649 /* Return true if (CODE OP0) is known to be non-negative. If the return
12650 value is based on the assumption that signed overflow is undefined,
12651 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12652 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12654 bool
12657 {
12662 {
12664 /* We can't return 1 if flag_wrapv is set because
12665 ABS_EXPR<INT_MIN> = INT_MIN. */
12669 {
12672 }
12680 CASE_CONVERT:
12681 {
12686 {
12690 {
12694 }
12695 }
12697 {
12703 }
12704 }
12709 }
12711 /* We don't know sign of `t', so be conservative and return false. */
12713 }
12715 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12716 value is based on the assumption that signed overflow is undefined,
12717 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12718 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12720 bool
12724 {
12729 {
12735 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12736 both unsigned and at least 2 bits shorter than the result. */
12740 {
12745 {
12749 }
12750 }
12755 {
12756 /* x * x is always non-negative for floating point x
12757 or without overflow. */
12760 {
12765 }
12766 }
12768 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12769 both unsigned and their total bits is shorter than the result. */
12773 {
12792 {
12802 }
12803 }
12830 }
12832 /* We don't know sign of `t', so be conservative and return false. */
12834 }
12836 /* Return true if T is known to be non-negative. If the return
12837 value is based on the assumption that signed overflow is undefined,
12838 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12839 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12841 bool
12843 {
12848 {
12862 /* Limit the depth of recursion to avoid quadratic behavior.
12863 This is expected to catch almost all occurrences in practice.
12864 If this code misses important cases that unbounded recursion
12865 would not, passes that need this information could be revised
12866 to provide it through dataflow propagation. */
12874 }
12875 }
12877 /* Return true if T is known to be non-negative. If the return
12878 value is based on the assumption that signed overflow is undefined,
12879 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12880 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12882 bool
12885 {
12887 {
12888 CASE_CFN_ACOS:
12889 CASE_CFN_ACOSH:
12890 CASE_CFN_CABS:
12891 CASE_CFN_COSH:
12892 CASE_CFN_ERFC:
12893 CASE_CFN_EXP:
12894 CASE_CFN_EXP10:
12895 CASE_CFN_EXP2:
12896 CASE_CFN_FABS:
12897 CASE_CFN_FDIM:
12898 CASE_CFN_HYPOT:
12899 CASE_CFN_POW10:
12900 CASE_CFN_FFS:
12901 CASE_CFN_PARITY:
12902 CASE_CFN_POPCOUNT:
12903 CASE_CFN_CLZ:
12904 CASE_CFN_CLRSB:
12907 /* Always true. */
12910 CASE_CFN_SQRT:
12911 /* sqrt(-0.0) is -0.0. */
12916 CASE_CFN_ASINH:
12917 CASE_CFN_ATAN:
12918 CASE_CFN_ATANH:
12919 CASE_CFN_CBRT:
12920 CASE_CFN_CEIL:
12921 CASE_CFN_ERF:
12922 CASE_CFN_EXPM1:
12923 CASE_CFN_FLOOR:
12924 CASE_CFN_FMOD:
12925 CASE_CFN_FREXP:
12926 CASE_CFN_ICEIL:
12927 CASE_CFN_IFLOOR:
12928 CASE_CFN_IRINT:
12929 CASE_CFN_IROUND:
12930 CASE_CFN_LCEIL:
12931 CASE_CFN_LDEXP:
12932 CASE_CFN_LFLOOR:
12933 CASE_CFN_LLCEIL:
12934 CASE_CFN_LLFLOOR:
12935 CASE_CFN_LLRINT:
12936 CASE_CFN_LLROUND:
12937 CASE_CFN_LRINT:
12938 CASE_CFN_LROUND:
12939 CASE_CFN_MODF:
12940 CASE_CFN_NEARBYINT:
12941 CASE_CFN_RINT:
12942 CASE_CFN_ROUND:
12943 CASE_CFN_SCALB:
12944 CASE_CFN_SCALBLN:
12945 CASE_CFN_SCALBN:
12946 CASE_CFN_SIGNBIT:
12947 CASE_CFN_SIGNIFICAND:
12948 CASE_CFN_SINH:
12949 CASE_CFN_TANH:
12950 CASE_CFN_TRUNC:
12951 /* True if the 1st argument is nonnegative. */
12954 CASE_CFN_FMAX:
12955 /* True if the 1st OR 2nd arguments are nonnegative. */
12958 CASE_CFN_FMIN:
12959 /* True if the 1st AND 2nd arguments are nonnegative. */
12962 CASE_CFN_COPYSIGN:
12963 /* True if the 2nd argument is nonnegative. */
12966 CASE_CFN_POWI:
12967 /* True if the 1st argument is nonnegative or the second
12968 argument is an even integer. */
12974 CASE_CFN_POW:
12975 /* True if the 1st argument is nonnegative or the second
12976 argument is an even integer valued real. */
12978 {
12979 REAL_VALUE_TYPE c;
12980 HOST_WIDE_INT n;
12985 {
12986 REAL_VALUE_TYPE cint;
12990 }
12991 }
12996 }
12998 }
13000 /* Return true if T is known to be non-negative. If the return
13001 value is based on the assumption that signed overflow is undefined,
13002 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13003 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13005 static bool
13007 {
13013 {
13015 {
13019 /* If the initializer is non-void, then it's a normal expression
13020 that will be assigned to the slot. */
13024 /* Otherwise, the initializer sets the slot in some way. One common
13025 way is an assignment statement at the end of the initializer. */
13027 {
13035 else
13037 }
13043 }
13046 {
13052 arg0,
13053 arg1,
13055 }
13068 }
13069 }
13071 #undef RECURSE
13072 #undef tree_expr_nonnegative_warnv_p
13074 /* Return true if T is known to be non-negative. If the return
13075 value is based on the assumption that signed overflow is undefined,
13076 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13077 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13079 bool
13081 {
13088 {
13110 }
13113 {
13139 }
13140 }
13142 /* Return true if `t' is known to be non-negative. Handle warnings
13143 about undefined signed overflow. */
13145 bool
13147 {
13154 "determining that expression is always "
13156 WARN_STRICT_OVERFLOW_MISC);
13158 }
13161 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13162 For floating point we further ensure that T is not denormal.
13163 Similar logic is present in nonzero_address in rtlanal.h.
13165 If the return value is based on the assumption that signed overflow
13166 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13167 change *STRICT_OVERFLOW_P. */
13169 bool
13172 {
13174 {
13177 strict_overflow_p);
13180 {
13186 strict_overflow_p));
13187 }
13192 strict_overflow_p);
13196 }
13199 }
13201 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13202 For floating point we further ensure that T is not denormal.
13203 Similar logic is present in nonzero_address in rtlanal.h.
13205 If the return value is based on the assumption that signed overflow
13206 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13207 change *STRICT_OVERFLOW_P. */
13209 bool
13211 tree type,
13212 tree op0,
13214 {
13217 {
13221 {
13222 /* With the presence of negative values it is hard
13223 to say something. */
13230 /* One of operands must be positive and the other non-negative. */
13231 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13232 overflows, on a twos-complement machine the sum of two
13233 nonnegative numbers can never be zero. */
13235 strict_overflow_p)
13237 strict_overflow_p));
13238 }
13243 {
13245 strict_overflow_p)
13247 strict_overflow_p))
13248 {
13251 }
13252 }
13261 {
13264 }
13271 {
13275 /* When both operands are nonzero, then MAX must be too. */
13277 strict_overflow_p))
13280 /* MAX where operand 0 is positive is positive. */
13282 strict_overflow_p);
13283 }
13284 /* MAX where operand 1 is positive is positive. */
13289 {
13293 }
13298 strict_overflow_p)
13300 strict_overflow_p));
13304 }
13307 }
13309 /* Return true when T is an address and is known to be nonzero.
13310 For floating point we further ensure that T is not denormal.
13311 Similar logic is present in nonzero_address in rtlanal.h.
13313 If the return value is based on the assumption that signed overflow
13314 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13315 change *STRICT_OVERFLOW_P. */
13317 bool
13319 {
13322 {
13327 {
13339 /* For objects in symbol table check if we know they are non-zero.
13340 Don't do anything for variables and functions before symtab is built;
13341 it is quite possible that they will be declared weak later. */
13346 /* Constants are never weak. */
13351 }
13359 {
13363 }
13373 }
13375 }
13377 #define integer_valued_real_p(X) \
13380 #define RECURSE(X) \
13381 ((integer_valued_real_p) (X, depth + 1))
13383 /* Return true if the floating point result of (CODE OP0) has an
13384 integer value. We also allow +Inf, -Inf and NaN to be considered
13385 integer values. Return false for signaling NaN.
13387 DEPTH is the current nesting depth of the query. */
13389 bool
13391 {
13393 {
13400 CASE_CONVERT:
13401 {
13408 }
13412 }
13414 }
13416 /* Return true if the floating point result of (CODE OP0 OP1) has an
13417 integer value. We also allow +Inf, -Inf and NaN to be considered
13418 integer values. Return false for signaling NaN.
13420 DEPTH is the current nesting depth of the query. */
13422 bool
13424 {
13426 {
13436 }
13438 }
13440 /* Return true if the floating point result of calling FNDECL with arguments
13441 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13442 considered integer values. Return false for signaling NaN. If FNDECL
13443 takes fewer than 2 arguments, the remaining ARGn are null.
13445 DEPTH is the current nesting depth of the query. */
13447 bool
13449 {
13451 {
13452 CASE_CFN_CEIL:
13453 CASE_CFN_FLOOR:
13454 CASE_CFN_NEARBYINT:
13455 CASE_CFN_RINT:
13456 CASE_CFN_ROUND:
13457 CASE_CFN_TRUNC:
13460 CASE_CFN_FMIN:
13461 CASE_CFN_FMAX:
13466 }
13468 }
13470 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13471 has an integer value. We also allow +Inf, -Inf and NaN to be
13472 considered integer values. Return false for signaling NaN.
13474 DEPTH is the current nesting depth of the query. */
13476 bool
13478 {
13480 {
13488 /* Limit the depth of recursion to avoid quadratic behavior.
13489 This is expected to catch almost all occurrences in practice.
13490 If this code misses important cases that unbounded recursion
13491 would not, passes that need this information could be revised
13492 to provide it through dataflow propagation. */
13496 depth));
13500 }
13502 }
13504 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13505 has an integer value. We also allow +Inf, -Inf and NaN to be
13506 considered integer values. Return false for signaling NaN.
13508 DEPTH is the current nesting depth of the query. */
13510 static bool
13512 {
13514 {
13525 }
13527 }
13529 #undef RECURSE
13530 #undef integer_valued_real_p
13532 /* Return true if the floating point expression T has an integer value.
13533 We also allow +Inf, -Inf and NaN to be considered integer values.
13534 Return false for signaling NaN.
13536 DEPTH is the current nesting depth of the query. */
13538 bool
13540 {
13546 {
13562 }
13565 {
13571 {
13580 }
13584 }
13585 }
13587 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13588 attempt to fold the expression to a constant without modifying TYPE,
13589 OP0 or OP1.
13591 If the expression could be simplified to a constant, then return
13592 the constant. If the expression would not be simplified to a
13593 constant, then return NULL_TREE. */
13595 tree
13597 {
13600 }
13602 /* Given the components of a unary expression CODE, TYPE and OP0,
13603 attempt to fold the expression to a constant without modifying
13604 TYPE or OP0.
13606 If the expression could be simplified to a constant, then return
13607 the constant. If the expression would not be simplified to a
13608 constant, then return NULL_TREE. */
13610 tree
13612 {
13615 }
13617 /* If EXP represents referencing an element in a constant string
13618 (either via pointer arithmetic or array indexing), return the
13619 tree representing the value accessed, otherwise return NULL. */
13621 tree
13623 {
13627 {
13629 tree index;
13630 tree string;
13635 else
13636 {
13640 /* Optimize the special-case of a zero lower bound.
13642 We convert the low_bound to sizetype to avoid some problems
13643 with constant folding. (E.g. suppose the lower bound is 1,
13644 and its mode is QI. Without the conversion,l (ARRAY
13645 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13646 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13652 }
13654 scalar_int_mode char_mode;
13666 }
13668 }
13670 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13671 an integer constant, real, or fixed-point constant.
13673 TYPE is the type of the result. */
13675 static tree
13677 {
13681 {
13683 {
13690 }
13697 {
13698 FIXED_VALUE_TYPE f;
13703 /* Propagate overflow flags. */
13707 }
13711 }
13714 }
13716 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13717 an integer constant or real constant.
13719 TYPE is the type of the result. */
13721 tree
13723 {
13727 {
13729 {
13730 /* If the value is unsigned or non-negative, then the absolute value
13731 is the same as the ordinary value. */
13735 /* If the value is negative, then the absolute value is
13736 its negation. */
13737 else
13738 {
13743 }
13744 }
13750 else
13756 }
13759 }
13761 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13762 constant. TYPE is the type of the result. */
13764 static tree
13766 {
13770 }
13772 /* Given CODE, a relational operator, the target type, TYPE and two
13773 constant operands OP0 and OP1, return the result of the
13774 relational operation. If the result is not a compile time
13775 constant, then return NULL_TREE. */
13777 static tree
13779 {
13782 /* From here on, the only cases we handle are when the result is
13783 known to be a constant. */
13786 {
13790 /* Handle the cases where either operand is a NaN. */
13792 {
13794 {
13822 }
13825 }
13828 }
13831 {
13835 }
13837 /* Handle equality/inequality of complex constants. */
13839 {
13850 else
13852 }
13855 {
13857 {
13858 /* Have vector comparison with scalar boolean result. */
13862 {
13870 }
13872 }
13879 {
13892 }
13895 }
13897 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13899 To compute GT, swap the arguments and do LT.
13900 To compute GE, do LT and invert the result.
13901 To compute LE, swap the arguments, do LT and invert the result.
13902 To compute NE, do EQ and invert the result.
13904 Therefore, the code below must handle only EQ and LT. */
13907 {
13910 }
13912 /* Note that it is safe to invert for real values here because we
13913 have already handled the one case that it matters. */
13917 {
13920 }
13922 /* Compute a result for LT or EQ if args permit;
13923 Otherwise return T. */
13925 {
13928 else
13930 }
13931 else
13937 }
13939 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13940 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13941 itself. */
13943 tree
13945 {
13946 /* If the expression does not have side effects then we don't have to wrap
13947 it with a cleanup point expression. */
13951 /* If the expression is a return, check to see if the expression inside the
13952 return has no side effects or the right hand side of the modify expression
13953 inside the return. If either don't have side effects set we don't need to
13954 wrap the expression in a cleanup point expression. Note we don't check the
13955 left hand side of the modify because it should always be a return decl. */
13957 {
13964 }
13967 }
13969 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13970 of an indirection through OP0, or NULL_TREE if no simplification is
13971 possible. */
13973 tree
13975 {
13977 tree subtype;
13986 {
13989 /* *&CONST_DECL -> to the value of the const decl. */
13992 /* *&p => p; make sure to handle *&"str"[cst] here. */
13994 {
13998 else
14000 }
14001 /* *(foo *)&fooarray => fooarray[0] */
14004 && (!in_gimple_form
14006 {
14016 }
14017 /* *(foo *)&complexfoo => __real__ complexfoo */
14021 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14024 {
14028 }
14029 }
14033 {
14039 {
14040 tree op00type;
14044 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14047 {
14049 unsigned HOST_WIDE_INT max_offset
14054 {
14061 }
14062 }
14063 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14066 {
14070 }
14071 /* ((foo *)&fooarray)[1] => fooarray[1] */
14074 {
14081 offset_int remainder;
14084 {
14089 }
14090 }
14091 }
14092 }
14094 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14097 && (!in_gimple_form
14099 {
14100 tree type_domain;
14110 NULL_TREE);
14111 }
14114 }
14116 /* Builds an expression for an indirection through T, simplifying some
14117 cases. */
14119 tree
14121 {
14129 }
14131 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14133 tree
14135 {
14140 else
14142 }
14144 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14145 whose result is ignored. The type of the returned tree need not be
14146 the same as the original expression. */
14148 tree
14150 {
14156 {
14167 else
14173 {
14189 }
14194 }
14195 }
14197 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14199 tree
14201 {
14207 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14208 have to do anything. Only do this when we are not given a const,
14209 because in that case, this check is more expensive than just
14210 doing it. */
14212 {
14217 }
14219 /* If divisor is a power of two, simplify this to bit manipulation. */
14221 {
14223 {
14237 }
14238 else
14239 {
14240 tree t;
14246 }
14247 }
14248 else
14249 {
14254 }
14257 }
14259 /* Likewise, but round down. */
14261 tree
14263 {
14270 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14271 have to do anything. Only do this when we are not given a const,
14272 because in that case, this check is more expensive than just
14273 doing it. */
14275 {
14280 }
14282 /* If divisor is a power of two, simplify this to bit manipulation. */
14284 {
14285 tree t;
14289 }
14290 else
14291 {
14296 }
14299 }
14301 /* Returns the pointer to the base of the object addressed by EXP and
14302 extracts the information about the offset of the access, storing it
14303 to PBITPOS and POFFSET. */
14305 static tree
14308 {
14309 tree core;
14310 machine_mode mode;
14312 HOST_WIDE_INT bitsize;
14316 {
14321 }
14323 {
14329 {
14334 {
14337 }
14338 }
14339 }
14340 else
14341 {
14345 }
14348 }
14350 /* Returns true if addresses of E1 and E2 differ by a constant, false
14351 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14353 bool
14355 {
14369 {
14379 }
14381 {
14382 /* If only one of the offsets is non-constant, the difference cannot
14383 be a constant. */
14385 }
14386 else
14391 }
14393 /* Return OFF converted to a pointer offset type suitable as offset for
14394 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14395 tree
14397 {
14399 }
14401 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14402 tree
14404 {
14407 }
14409 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14410 tree
14412 {
14415 }
14417 /* Return a char pointer for a C string if it is a string constant
14418 or sum of string constant and integer constant. We only support
14419 string constants properly terminated with '\0' character.
14420 If STRLEN is a valid pointer, length (including terminating character)
14421 of returned string is stored to the argument. */
14425 {
14426 tree offset_node;
14437 {
14440 else
14442 }
14447 /* Support only properly null-terminated strings. */
14456 }
14458 #if CHECKING_P
14462 /* Helper functions for writing tests of folding trees. */
14464 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14466 static void
14468 tree constant)
14469 {
14471 }
14473 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14474 wrapping WRAPPED_EXPR. */
14476 static void
14478 tree wrapped_expr)
14479 {
14484 }
14486 /* Verify that various arithmetic binary operations are folded
14487 correctly. */
14489 static void
14491 {
14497 /* Addition. */
14498 /* 1 <-- (0 + 1) */
14500 one);
14502 one);
14504 /* (nonlvalue)x <-- (x + 0) */
14506 x);
14508 /* Subtraction. */
14509 /* 0 <-- (x - x) */
14511 zero);
14513 x);
14515 /* Multiplication. */
14516 /* 0 <-- (x * 0) */
14518 zero);
14520 /* (nonlvalue)x <-- (x * 1) */
14522 x);
14523 }
14525 /* Verify that various binary operations on vectors are folded
14526 correctly. */
14528 static void
14530 {
14536 /* Verify equality tests that return a scalar boolean result. */
14542 }
14544 /* Run all of the selftests within this file. */
14546 void
14548 {
14551 }