| blob | 379a30ea285acf6d78042bc1a3a5c152539b2b75 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
83 /* Nonzero if we are folding constants inside an initializer; zero
84 otherwise. */
87 /* The following constants represent a bit based encoding of GCC's
88 comparison operators. This encoding simplifies transformations
89 on relational comparison operators, such as AND and OR. */
107 };
145 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
146 Otherwise, return LOC. */
148 static location_t
150 {
153 }
155 /* Similar to protected_set_expr_location, but never modify x in place,
156 if location can and needs to be set, unshare it. */
160 {
166 {
169 }
171 }
172 \f
173 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
174 division and returns the quotient. Otherwise returns
175 NULL_TREE. */
177 tree
179 {
180 widest_int quo;
187 }
188 \f
189 /* This is nonzero if we should defer warnings about undefined
190 overflow. This facility exists because these warnings are a
191 special case. The code to estimate loop iterations does not want
192 to issue any warnings, since it works with expressions which do not
193 occur in user code. Various bits of cleanup code call fold(), but
194 only use the result if it has certain characteristics (e.g., is a
195 constant); that code only wants to issue a warning if the result is
196 used. */
200 /* If a warning about undefined overflow is deferred, this is the
201 warning. Note that this may cause us to turn two warnings into
202 one, but that is fine since it is sufficient to only give one
203 warning per expression. */
207 /* If a warning about undefined overflow is deferred, this is the
208 level at which the warning should be emitted. */
212 /* Start deferring overflow warnings. We could use a stack here to
213 permit nested calls, but at present it is not necessary. */
215 void
217 {
219 }
221 /* Stop deferring overflow warnings. If there is a pending warning,
222 and ISSUE is true, then issue the warning if appropriate. STMT is
223 the statement with which the warning should be associated (used for
224 location information); STMT may be NULL. CODE is the level of the
225 warning--a warn_strict_overflow_code value. This function will use
226 the smaller of CODE and the deferred code when deciding whether to
227 issue the warning. CODE may be zero to mean to always use the
228 deferred code. */
230 void
232 {
234 location_t locus;
239 {
245 }
256 /* Use the smallest code level when deciding to issue the
257 warning. */
266 else
269 }
271 /* Stop deferring overflow warnings, ignoring any deferred
272 warnings. */
274 void
276 {
278 }
280 /* Whether we are deferring overflow warnings. */
282 bool
284 {
286 }
288 /* This is called when we fold something based on the fact that signed
289 overflow is undefined. */
291 void
293 {
295 {
298 {
301 }
302 }
305 }
306 \f
307 /* Return true if the built-in mathematical function specified by CODE
308 is odd, i.e. -f(x) == f(-x). */
310 bool
312 {
314 {
315 CASE_CFN_ASIN:
316 CASE_CFN_ASINH:
317 CASE_CFN_ATAN:
318 CASE_CFN_ATANH:
319 CASE_CFN_CASIN:
320 CASE_CFN_CASINH:
321 CASE_CFN_CATAN:
322 CASE_CFN_CATANH:
323 CASE_CFN_CBRT:
324 CASE_CFN_CPROJ:
325 CASE_CFN_CSIN:
326 CASE_CFN_CSINH:
327 CASE_CFN_CTAN:
328 CASE_CFN_CTANH:
329 CASE_CFN_ERF:
330 CASE_CFN_LLROUND:
331 CASE_CFN_LROUND:
332 CASE_CFN_ROUND:
333 CASE_CFN_SIN:
334 CASE_CFN_SINH:
335 CASE_CFN_TAN:
336 CASE_CFN_TANH:
337 CASE_CFN_TRUNC:
340 CASE_CFN_LLRINT:
341 CASE_CFN_LRINT:
342 CASE_CFN_NEARBYINT:
343 CASE_CFN_RINT:
348 }
350 }
352 /* Check whether we may negate an integer constant T without causing
353 overflow. */
355 bool
357 {
358 tree type;
367 }
369 /* Determine whether an expression T can be cheaply negated using
370 the function negate_expr without introducing undefined overflow. */
372 static bool
374 {
375 tree type;
384 {
389 /* Check that -CST will not overflow type. */
402 /* We want to canonicalize to positive real constants. Pretend
403 that only negative ones can be easily negated. */
411 {
422 }
437 /* -(A + B) -> (-B) - A. */
440 /* -(A + B) -> (-A) - B. */
444 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
453 /* INT_MIN/n * n doesn't overflow while negating one operand it does
454 if n is a (negative) power of two. */
463 /* Fall through. */
478 /* In general we can't negate B in A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. */
489 /* Negate -((double)float) as (double)(-float). */
491 {
495 }
499 /* Negate -f(x) as f(-x). */
505 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
507 {
511 }
516 }
518 }
520 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
521 simplification is possible.
522 If negate_expr_p would return true for T, NULL_TREE will never be
523 returned. */
525 static tree
527 {
529 tree tem;
532 {
533 /* Convert - (~A) to A + 1. */
559 {
564 }
568 {
573 {
577 }
580 }
603 {
604 /* -(A + B) -> (-B) - A. */
606 {
610 }
612 /* -(A + B) -> (-A) - B. */
614 {
618 }
619 }
623 /* - (A - B) -> B - A */
634 /* Fall through. */
638 {
647 }
659 /* In general we can't negate B in A / B, because if A is INT_MIN and
660 B is 1, we may turn this into INT_MIN / -1 which is undefined
661 and actually traps on some architectures. */
673 /* Convert -((double)float) into (double)(-float). */
675 {
679 }
683 /* Negate -f(x) as f(-x). */
686 {
692 }
696 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
698 {
701 {
708 }
709 }
714 }
717 }
719 /* A wrapper for fold_negate_expr_1. */
721 static tree
723 {
730 }
732 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
733 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
734 return NULL_TREE. */
736 static tree
738 {
740 location_t loc;
753 }
754 \f
755 /* Split a tree IN into a constant, literal and variable parts that could be
756 combined with CODE to make IN. "constant" means an expression with
757 TREE_CONSTANT but that isn't an actual constant. CODE must be a
758 commutative arithmetic operation. Store the constant part into *CONP,
759 the literal in *LITP and return the variable part. If a part isn't
760 present, set it to null. If the tree does not decompose in this way,
761 return the entire tree as the variable part and the other parts as null.
763 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
764 case, we negate an operand that was subtracted. Except if it is a
765 literal for which we use *MINUS_LITP instead.
767 If NEGATE_P is true, we are negating all of IN, again except a literal
768 for which we use *MINUS_LITP instead. If a variable part is of pointer
769 type, it is negated after converting to TYPE. This prevents us from
770 generating illegal MINUS pointer expression. LOC is the location of
771 the converted variable part.
773 If IN is itself a literal or constant, return it as appropriate.
775 Note that we do not guarantee that any of the three values will be the
776 same type as IN, but they will have the same signedness and mode. */
778 static tree
781 {
788 /* Strip any conversions that don't change the machine mode or signedness. */
797 /* We can associate addition and subtraction together (even
798 though the C standard doesn't say so) for integers because
799 the value is not affected. For reals, the value might be
800 affected, so we can't. */
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. */
838 {
839 /* Convert to TYPE before negating. */
842 }
844 {
845 /* Convert to TYPE before negating. */
848 }
849 }
854 {
855 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
856 when IN is constant. Convert to TYPE before negating. */
859 }
860 else
864 {
870 {
871 /* Convert to TYPE before negating. */
874 }
876 {
877 /* Convert to TYPE before negating. */
880 }
881 }
891 }
893 /* Re-associate trees split by the above function. T1 and T2 are
894 either expressions to associate or null. Return the new
895 expression, if any. LOC is the location of the new expression. If
896 we build an operation, do it in TYPE and with CODE. */
898 static tree
900 {
906 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
907 try to fold this since we will have infinite recursion. But do
908 deal with any NEGATE_EXPRs. */
911 {
913 {
926 }
928 {
931 }
935 }
939 }
940 \f
941 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
942 for use in int_const_binop, size_binop and size_diffop. */
944 static bool
946 {
953 {
962 }
967 }
970 /* Combine two integer constants ARG1 and ARG2 under operation CODE
971 to produce a new constant. Return NULL_TREE if we don't know how
972 to evaluate CODE at compile-time. */
974 static tree
977 {
978 wide_int res;
979 tree t;
987 {
1003 {
1007 else
1009 }
1012 /* It's unclear from the C standard whether shifts can overflow.
1013 The following code ignores overflow; perhaps a C standard
1014 interpretation ruling is needed. */
1016 else
1023 {
1027 else
1029 }
1033 else
1112 }
1120 }
1122 tree
1124 {
1126 }
1128 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1129 constant. We assume ARG1 and ARG2 have the same data type, or at least
1130 are the same kind of constant and the same machine mode. Return zero if
1131 combining the constants is not allowed in the current operating mode. */
1133 static tree
1135 {
1136 /* Sanity check for the recursive cases. */
1144 {
1150 }
1153 {
1154 machine_mode mode;
1155 REAL_VALUE_TYPE d1;
1156 REAL_VALUE_TYPE d2;
1157 REAL_VALUE_TYPE value;
1158 REAL_VALUE_TYPE result;
1162 /* The following codes are handled by real_arithmetic. */
1164 {
1175 }
1183 /* Don't perform operation if we honor signaling NaNs and
1184 either operand is a signaling NaN. */
1190 /* Don't perform operation if it would raise a division
1191 by zero exception. */
1197 /* If either operand is a NaN, just return it. Otherwise, set up
1198 for floating-point trap; we return an overflow. */
1200 {
1201 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1202 is off. */
1206 }
1208 {
1209 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1210 is off. */
1214 }
1219 /* Don't constant fold this floating point operation if
1220 the result has overflowed and flag_trapping_math. */
1228 /* Don't constant fold this floating point operation if the
1229 result may dependent upon the run-time rounding mode and
1230 flag_rounding_math is set, or if GCC's software emulation
1231 is unable to accurately represent the result. */
1241 }
1244 {
1245 FIXED_VALUE_TYPE f1;
1246 FIXED_VALUE_TYPE f2;
1247 FIXED_VALUE_TYPE result;
1252 /* The following codes are handled by fixed_arithmetic. */
1254 {
1266 {
1273 }
1278 }
1285 /* Propagate overflow flags. */
1289 }
1292 {
1301 {
1312 mpc_mul);
1326 mpc_div);
1327 /* Fallthru. */
1333 {
1334 /* Keep this algorithm in sync with
1335 tree-complex.c:expand_complex_div_straight().
1337 Expand complex division to scalars, straightforward algorithm.
1338 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1339 t = br*br + bi*bi
1340 */
1341 tree magsquared
1345 tree t1
1349 tree t2
1356 }
1357 else
1358 {
1359 /* Keep this algorithm in sync with
1360 tree-complex.c:expand_complex_div_wide().
1362 Expand complex division to scalars, modified algorithm to minimize
1363 overflow with wide input ranges. */
1369 {
1370 /* In the TRUE branch, we compute
1371 ratio = br/bi;
1372 div = (br * ratio) + bi;
1373 tr = (ar * ratio) + ai;
1374 ti = (ai * ratio) - ar;
1375 tr = tr / div;
1376 ti = ti / div; */
1387 }
1388 else
1389 {
1390 /* In the FALSE branch, we compute
1391 ratio = d/c;
1392 divisor = (d * ratio) + c;
1393 tr = (b * ratio) + a;
1394 ti = b - (a * ratio);
1395 tr = tr / div;
1396 ti = ti / div; */
1408 }
1409 }
1414 }
1418 }
1422 {
1428 {
1434 /* It is possible that const_binop cannot handle the given
1435 code and return NULL_TREE */
1438 }
1441 }
1443 /* Shifts allow a scalar offset for a vector. */
1446 {
1452 {
1457 /* It is possible that const_binop cannot handle the given
1458 code and return NULL_TREE. */
1461 }
1464 }
1466 }
1468 /* Overload that adds a TYPE parameter to be able to dispatch
1469 to fold_relational_const. */
1471 tree
1473 {
1477 /* ??? Until we make the const_binop worker take the type of the
1478 result as argument put those cases that need it here. */
1480 {
1491 {
1507 {
1513 }
1516 }
1522 {
1547 {
1560 }
1563 }
1566 }
1571 /* Make sure type and arg0 have the same saturating flag. */
1576 }
1578 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1579 Return zero if computing the constants is not possible. */
1581 tree
1583 {
1584 /* Don't perform the operation, other than NEGATE and ABS, if
1585 flag_signaling_nans is on and the operand is a signaling NaN. */
1594 {
1595 CASE_CONVERT:
1602 /* If the source address is 0, and the source address space
1603 cannot have a valid object at 0, fold to dest type null. */
1614 {
1615 /* Can't call fold_negate_const directly here as that doesn't
1616 handle all cases and we might not be able to negate some
1617 constants. */
1622 }
1631 {
1635 }
1641 /* Perform BIT_NOT_EXPR on each element individually. */
1643 {
1645 tree elem;
1650 {
1656 }
1659 }
1681 {
1700 else
1704 {
1708 }
1711 }
1716 {
1730 {
1735 }
1738 {
1742 }
1745 }
1749 }
1752 }
1754 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1755 indicates which particular sizetype to create. */
1757 tree
1759 {
1761 }
1762 \f
1763 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1764 is a tree code. The type of the result is taken from the operands.
1765 Both must be equivalent integer types, ala int_binop_types_match_p.
1766 If the operands are constant, so is the result. */
1768 tree
1770 {
1779 /* Handle the special case of two integer constants faster. */
1781 {
1782 /* And some specific cases even faster than that. */
1784 {
1789 }
1791 {
1794 }
1796 {
1799 }
1801 /* Handle general case of two integer constants. For sizetype
1802 constant calculations we always want to know about overflow,
1803 even in the unsigned case. */
1805 }
1808 }
1810 /* Given two values, either both of sizetype or both of bitsizetype,
1811 compute the difference between the two values. Return the value
1812 in signed type corresponding to the type of the operands. */
1814 tree
1816 {
1818 tree ctype;
1823 /* If the type is already signed, just do the simple thing. */
1831 else
1834 /* If either operand is not a constant, do the conversions to the signed
1835 type and subtract. The hardware will do the right thing with any
1836 overflow in the subtraction. */
1842 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1843 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1844 overflow) and negate (which can't either). Special-case a result
1845 of zero while we're here. */
1851 else
1855 MINUS_EXPR,
1857 }
1858 \f
1859 /* A subroutine of fold_convert_const handling conversions of an
1860 INTEGER_CST to another integer type. */
1862 static tree
1864 {
1865 /* Given an integer constant, make new constant with new type,
1866 appropriately sign-extended or truncated. Use widest_int
1867 so that any extension is done according ARG1's type. */
1871 }
1873 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1874 to an integer type. */
1876 static tree
1878 {
1880 tree t;
1882 /* The following code implements the floating point to integer
1883 conversion rules required by the Java Language Specification,
1884 that IEEE NaNs are mapped to zero and values that overflow
1885 the target precision saturate, i.e. values greater than
1886 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1887 are mapped to INT_MIN. These semantics are allowed by the
1888 C and C++ standards that simply state that the behavior of
1889 FP-to-integer conversion is unspecified upon overflow. */
1891 wide_int val;
1892 REAL_VALUE_TYPE r;
1896 {
1903 }
1905 /* If R is NaN, return zero and show we have an overflow. */
1907 {
1910 }
1912 /* See if R is less than the lower bound or greater than the
1913 upper bound. */
1916 {
1920 {
1923 }
1924 }
1927 {
1930 {
1933 {
1936 }
1937 }
1938 }
1945 }
1947 /* A subroutine of fold_convert_const handling conversions of a
1948 FIXED_CST to an integer type. */
1950 static tree
1952 {
1953 tree t;
1957 /* Right shift FIXED_CST to temp by fbit. */
1961 {
1963 HOST_BITS_PER_DOUBLE_INT,
1966 /* Left shift temp to temp_trunc by fbit. */
1968 HOST_BITS_PER_DOUBLE_INT,
1970 }
1971 else
1972 {
1975 }
1977 /* If FIXED_CST is negative, we need to round the value toward 0.
1978 By checking if the fractional bits are not zero to add 1 to temp. */
1984 /* Given a fixed-point constant, make new constant with new type,
1985 appropriately sign-extended or truncated. */
1993 }
1995 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1996 to another floating point type. */
1998 static tree
2000 {
2001 REAL_VALUE_TYPE value;
2002 tree t;
2004 /* Don't perform the operation if flag_signaling_nans is on
2005 and the operand is a signaling NaN. */
2013 /* If converting an infinity or NAN to a representation that doesn't
2014 have one, set the overflow bit so that we can produce some kind of
2015 error message at the appropriate point if necessary. It's not the
2016 most user-friendly message, but it's better than nothing. */
2023 /* Regular overflow, conversion produced an infinity in a mode that
2024 can't represent them. */
2029 else
2032 }
2034 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2035 to a floating point type. */
2037 static tree
2039 {
2040 REAL_VALUE_TYPE value;
2041 tree t;
2048 }
2050 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2051 to another fixed-point type. */
2053 static tree
2055 {
2056 FIXED_VALUE_TYPE value;
2057 tree t;
2064 /* Propagate overflow flags. */
2068 }
2070 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2071 to a fixed-point type. */
2073 static tree
2075 {
2076 FIXED_VALUE_TYPE value;
2077 tree t;
2079 double_int di;
2086 else
2094 /* Propagate overflow flags. */
2098 }
2100 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2101 to a fixed-point type. */
2103 static tree
2105 {
2106 FIXED_VALUE_TYPE value;
2107 tree t;
2115 /* Propagate overflow flags. */
2119 }
2121 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2122 type TYPE. If no simplification can be done return NULL_TREE. */
2124 static tree
2126 {
2132 {
2139 }
2141 {
2148 }
2150 {
2157 }
2159 {
2162 {
2167 {
2173 }
2175 }
2176 }
2178 }
2180 /* Construct a vector of zero elements of vector type TYPE. */
2182 static tree
2184 {
2185 tree t;
2189 }
2191 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2193 bool
2195 {
2210 {
2225 }
2226 }
2228 /* Convert expression ARG to type TYPE. Used by the middle-end for
2229 simple conversions in preference to calling the front-end's convert. */
2231 tree
2233 {
2235 tree tem;
2246 {
2249 /* Handle conversions between pointers to different address spaces. */
2254 /* fall through */
2259 {
2263 }
2277 {
2281 }
2283 {
2287 }
2289 {
2293 }
2296 {
2314 }
2319 {
2323 }
2326 {
2340 }
2344 {
2353 integer_zero_node));
2355 {
2359 {
2365 }
2373 }
2377 }
2395 }
2396 fold_convert_exit:
2399 }
2400 \f
2401 /* Return false if expr can be assumed not to be an lvalue, true
2402 otherwise. */
2404 static bool
2406 {
2407 /* We only need to wrap lvalue tree codes. */
2409 {
2440 /* Assume the worst for front-end tree codes. */
2444 }
2447 }
2449 /* Return an expr equal to X but certainly not valid as an lvalue. */
2451 tree
2453 {
2454 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2455 us. */
2462 }
2464 /* When pedantic, return an expr equal to X but certainly not valid as a
2465 pedantic lvalue. Otherwise, return X. */
2467 static tree
2469 {
2471 }
2472 \f
2473 /* Given a tree comparison code, return the code that is the logical inverse.
2474 It is generally not safe to do this for floating-point comparisons, except
2475 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2476 ERROR_MARK in this case. */
2478 enum tree_code
2480 {
2486 {
2517 }
2518 }
2520 /* Similar, but return the comparison that results if the operands are
2521 swapped. This is safe for floating-point. */
2523 enum tree_code
2525 {
2527 {
2553 }
2554 }
2557 /* Convert a comparison tree code from an enum tree_code representation
2558 into a compcode bit-based encoding. This function is the inverse of
2559 compcode_to_comparison. */
2561 static enum comparison_code
2563 {
2565 {
2596 }
2597 }
2599 /* Convert a compcode bit-based encoding of a comparison operator back
2600 to GCC's enum tree_code representation. This function is the
2601 inverse of comparison_to_compcode. */
2603 static enum tree_code
2605 {
2607 {
2638 }
2639 }
2641 /* Return a tree for the comparison which is the combination of
2642 doing the AND or OR (depending on CODE) of the two operations LCODE
2643 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2644 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2645 if this makes the transformation invalid. */
2647 tree
2652 {
2659 {
2670 }
2673 {
2674 /* Eliminate unordered comparisons, as well as LTGT and ORD
2675 which are not used unless the mode has NaNs. */
2681 }
2683 {
2684 /* Check that the original operation and the optimized ones will trap
2685 under the same condition. */
2696 /* In a short-circuited boolean expression the LHS might be
2697 such that the RHS, if evaluated, will never trap. For
2698 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2699 if neither x nor y is NaN. (This is a mixed blessing: for
2700 example, the expression above will never trap, hence
2701 optimizing it to x < y would be invalid). */
2706 /* If the comparison was short-circuited, and only the RHS
2707 trapped, we may now generate a spurious trap. */
2712 /* If we changed the conditions that cause a trap, we lose. */
2715 }
2721 else
2722 {
2727 }
2728 }
2729 \f
2730 /* Return nonzero if two operands (typically of the same tree node)
2731 are necessarily equal. FLAGS modifies behavior as follows:
2733 If OEP_ONLY_CONST is set, only return nonzero for constants.
2734 This function tests whether the operands are indistinguishable;
2735 it does not test whether they are equal using C's == operation.
2736 The distinction is important for IEEE floating point, because
2737 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2738 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2740 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2741 even though it may hold multiple values during a function.
2742 This is because a GCC tree node guarantees that nothing else is
2743 executed between the evaluation of its "operands" (which may often
2744 be evaluated in arbitrary order). Hence if the operands themselves
2745 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2746 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2747 unset means assuming isochronic (or instantaneous) tree equivalence.
2748 Unless comparing arbitrary expression trees, such as from different
2749 statements, this flag can usually be left unset.
2751 If OEP_PURE_SAME is set, then pure functions with identical arguments
2752 are considered the same. It is used when the caller has other ways
2753 to ensure that global memory is unchanged in between.
2755 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2756 not values of expressions.
2758 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2759 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2761 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2762 any operand with side effect. This is unnecesarily conservative in the
2763 case we know that arg0 and arg1 are in disjoint code paths (such as in
2764 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2765 addresses with TREE_CONSTANT flag set so we know that &var == &var
2766 even if var is volatile. */
2768 int
2770 {
2771 /* When checking, verify at the outermost operand_equal_p call that
2772 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2773 hash value. */
2775 {
2777 {
2779 {
2786 }
2788 }
2789 else
2791 }
2793 /* If either is ERROR_MARK, they aren't equal. */
2799 /* Similar, if either does not have a type (like a released SSA name),
2800 they aren't equal. */
2804 /* We cannot consider pointers to different address space equal. */
2811 /* Check equality of integer constants before bailing out due to
2812 precision differences. */
2814 {
2815 /* Address of INTEGER_CST is not defined; check that we did not forget
2816 to drop the OEP_ADDRESS_OF flags. */
2819 }
2822 {
2823 /* If both types don't have the same signedness, then we can't consider
2824 them equal. We must check this before the STRIP_NOPS calls
2825 because they may change the signedness of the arguments. As pointers
2826 strictly don't have a signedness, require either two pointers or
2827 two non-pointers as well. */
2833 /* If both types don't have the same precision, then it is not safe
2834 to strip NOPs. */
2841 }
2842 #if 0
2843 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2844 sanity check once the issue is solved. */
2845 else
2846 /* Addresses of conversions and SSA_NAMEs (and many other things)
2847 are not defined. Check that we did not forget to drop the
2848 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2851 #endif
2853 /* In case both args are comparisons but with different comparison
2854 code, try to swap the comparison operands of one arg to produce
2855 a match and compare that variant. */
2859 {
2867 }
2870 {
2871 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2873 ;
2875 {
2876 /* If we are interested in comparing addresses ignore
2877 MEM_REF wrappings of the base that can appear just for
2878 TBAA reasons. */
2892 }
2893 else
2895 }
2897 /* When not checking adddresses, this is needed for conversions and for
2898 COMPONENT_REF. Might as well play it safe and always test this. */
2905 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2906 We don't care about side effects in that case because the SAVE_EXPR
2907 takes care of that for us. In all other cases, two expressions are
2908 equal if they have no side effects. If we have two identical
2909 expressions with side effects that should be treated the same due
2910 to the only side effects being identical SAVE_EXPR's, that will
2911 be detected in the recursive calls below.
2912 If we are taking an invariant address of two identical objects
2913 they are necessarily equal as well. */
2920 /* Next handle constant cases, those for which we can return 1 even
2921 if ONLY_CONST is set. */
2924 {
2938 {
2939 /* If we do not distinguish between signed and unsigned zero,
2940 consider them equal. */
2943 }
2947 {
2954 {
2958 }
2960 }
2964 flags)
2966 flags));
2977 flags | OEP_ADDRESS_OF
2980 /* In GIMPLE empty constructors are allowed in initializers of
2981 aggregates. */
2985 }
2990 /* Define macros to test an operand from arg0 and arg1 for equality and a
2991 variant that allows null and views null as being different from any
2992 non-null value. In the latter case, if either is null, the both
2993 must be; otherwise, do the normal comparison. */
2994 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2995 TREE_OPERAND (arg1, N), flags)
2997 #define OP_SAME_WITH_NULL(N) \
2998 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2999 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3002 {
3004 /* Two conversions are equal only if signedness and modes match. */
3006 {
3007 CASE_CONVERT:
3015 }
3025 /* For commutative ops, allow the other order. */
3033 /* If either of the pointer (or reference) expressions we are
3034 dereferencing contain a side effect, these cannot be equal,
3035 but their addresses can be. */
3042 {
3052 /* Require the same offset. */
3058 /* Fallthru. */
3066 {
3067 /* Require equal access sizes */
3073 flags)))
3075 /* Verify that access happens in similar types. */
3078 /* Verify that accesses are TBAA compatible. */
3087 /* Verify that alignment is compatible. */
3091 }
3094 /* TARGET_MEM_REF require equal extra operands. */
3105 /* Compare the array index by value if it is constant first as we
3106 may have different types but same value here. */
3112 /* Compare low bound and element size as with OEP_ADDRESS_OF
3113 we have to account for the offset of the ref. */
3118 array_ref_low_bound
3122 array_ref_element_size
3124 flags))));
3127 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3128 may be NULL when we're called to compare MEM_EXPRs. */
3143 }
3147 {
3149 /* Be sure we pass right ADDRESS_OF flag. */
3167 /* The multiplcation operands are commutative. */
3168 /* FALLTHRU */
3176 /* Otherwise take into account this is a commutative operation. */
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 see if ARG0 might have been made by
3367 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3369 When in doubt, return 0. */
3371 static int
3373 {
3385 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3386 and see if the inner values are the same. This removes any
3387 signedness comparison, which doesn't matter here. */
3394 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3395 actual comparison operand, ARG0.
3397 First throw away any conversions to wider types
3398 already present in the operands. */
3407 {
3410 /* Make sure shorter operand is extended the right way
3411 to match the longer operand. */
3417 }
3420 }
3421 \f
3422 /* See if ARG is an expression that is either a comparison or is performing
3423 arithmetic on comparisons. The comparisons must only be comparing
3424 two different values, which will be stored in *CVAL1 and *CVAL2; if
3425 they are nonzero it means that some operands have already been found.
3426 No variables may be used anywhere else in the expression except in the
3427 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3428 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3430 If this is true, return 1. Otherwise, return zero. */
3432 static int
3434 {
3438 /* We can handle some of the tcc_expression cases here. */
3448 {
3449 /* If we've already found a CVAL1 or CVAL2, this expression is
3450 two complex to handle. */
3456 }
3459 {
3482 /* First see if we can handle the first operand, then the second. For
3483 the second operand, we know *CVAL1 can't be zero. It must be that
3484 one side of the comparison is each of the values; test for the
3485 case where this isn't true by failing if the two operands
3486 are the same. */
3495 ;
3499 ;
3500 else
3504 ;
3508 ;
3509 else
3516 }
3517 }
3518 \f
3519 /* ARG is a tree that is known to contain just arithmetic operations and
3520 comparisons. Evaluate the operations in the tree substituting NEW0 for
3521 any occurrence of OLD0 as an operand of a comparison and likewise for
3522 NEW1 and OLD1. */
3524 static tree
3527 {
3532 /* We can handle some of the tcc_expression cases here. */
3540 {
3555 {
3574 }
3575 /* Fall through - ??? */
3578 {
3582 /* We need to check both for exact equality and tree equality. The
3583 former will be true if the operand has a side-effect. In that
3584 case, we know the operand occurred exactly once. */
3597 }
3601 }
3602 }
3603 \f
3604 /* Return a tree for the case when the result of an expression is RESULT
3605 converted to TYPE and OMITTED was previously an operand of the expression
3606 but is now not needed (e.g., we folded OMITTED * 0).
3608 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3609 the conversion of RESULT to TYPE. */
3611 tree
3613 {
3616 /* If the resulting operand is an empty statement, just return the omitted
3617 statement casted to void. */
3627 }
3629 /* Return a tree for the case when the result of an expression is RESULT
3630 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3631 of the expression but are now not needed.
3633 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3634 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3635 evaluated before OMITTED2. Otherwise, if neither has side effects,
3636 just do the conversion of RESULT to TYPE. */
3638 tree
3641 {
3650 }
3652 \f
3653 /* Return a simplified tree node for the truth-negation of ARG. This
3654 never alters ARG itself. We assume that ARG is an operation that
3655 returns a truth value (0 or 1).
3657 FIXME: one would think we would fold the result, but it causes
3658 problems with the dominator optimizer. */
3660 static tree
3662 {
3667 /* If this is a comparison, we can simply invert it, except for
3668 floating-point non-equality comparisons, in which case we just
3669 enclose a TRUTH_NOT_EXPR around what we have. */
3672 {
3675 && flag_trapping_math
3689 }
3692 {
3711 /* Here we can invert either operand. We invert the first operand
3712 unless the second operand is a TRUTH_NOT_EXPR in which case our
3713 result is the XOR of the first operand with the inside of the
3714 negation of the second operand. */
3719 else
3742 {
3749 /* A COND_EXPR may have a throw as one operand, which
3750 then has void type. Just leave void operands
3751 as they are. */
3757 }
3769 CASE_CONVERT:
3773 /* fall through */
3795 }
3796 }
3798 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3799 assume that ARG is an operation that returns a truth value (0 or 1
3800 for scalars, 0 or -1 for vectors). Return the folded expression if
3801 folding is successful. Otherwise, return NULL_TREE. */
3803 static tree
3805 {
3808 ? BIT_NOT_EXPR
3811 }
3813 /* Return a simplified tree node for the truth-negation of ARG. This
3814 never alters ARG itself. We assume that ARG is an operation that
3815 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3817 tree
3819 {
3825 ? BIT_NOT_EXPR
3828 }
3830 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3831 with code CODE. This optimization is unsafe. */
3832 static tree
3835 {
3839 /* (A / C) +- (B / C) -> (A +- B) / C. */
3849 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3854 {
3866 }
3869 }
3870 \f
3871 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3872 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3873 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3874 is the original memory reference used to preserve the alias set of
3875 the access. */
3877 static tree
3881 {
3884 /* Attempt not to lose the access path if possible. */
3886 {
3888 machine_mode nmode;
3890 tree noffset;
3900 && !reversep
3901 && !nreversep
3903 {
3906 }
3907 }
3916 {
3923 }
3938 }
3940 /* Optimize a bit-field compare.
3942 There are two cases: First is a compare against a constant and the
3943 second is a comparison of two items where the fields are at the same
3944 bit position relative to the start of a chunk (byte, halfword, word)
3945 large enough to contain it. In these cases we can avoid the shift
3946 implicit in bitfield extractions.
3948 For constants, we emit a compare of the shifted constant with the
3949 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3950 compared. For two fields at the same position, we do the ANDs with the
3951 similar mask and compare the result of the ANDs.
3953 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3954 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3955 are the left and right operands of the comparison, respectively.
3957 If the optimization described above can be done, we return the resulting
3958 tree. Otherwise we return zero. */
3960 static tree
3963 {
3966 tree unsigned_type;
3973 tree mask;
3974 tree offset;
3976 /* Get all the information about the extractions being done. If the bit size
3977 if the same as the size of the underlying object, we aren't doing an
3978 extraction at all and so can do nothing. We also don't want to
3979 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3980 then will no longer be able to replace it. */
3989 else
3990 {
3991 /* If this is not a constant, we can only do something if bit positions,
3992 sizes, signedness and storage order are the same. */
3993 rinner
4001 }
4003 /* Honor the C++ memory model and mimic what RTL expansion does. */
4007 {
4011 }
4013 /* See if we can find a mode to refer to this field. We should be able to,
4014 but fail if we can't. */
4023 /* Set signed and unsigned types of the precision of this mode for the
4024 shifts below. */
4027 /* Compute the bit position and size for the new reference and our offset
4028 within it. If the new reference is the same size as the original, we
4029 won't optimize anything, so return zero. */
4039 /* Make the mask to be used against the extracted field. */
4046 /* If not comparing with constant, just rework the comparison
4047 and return. */
4051 unsigned_type,
4054 mask),
4057 unsigned_type,
4060 mask));
4062 /* Otherwise, we are handling the constant case. See if the constant is too
4063 big for the field. Warn and return a tree for 0 (false) if so. We do
4064 this not only for its own sake, but to avoid having to test for this
4065 error case below. If we didn't, we might generate wrong code.
4067 For unsigned fields, the constant shifted right by the field length should
4068 be all zero. For signed fields, the high-order bits should agree with
4069 the sign bit. */
4072 {
4074 {
4078 }
4079 }
4080 else
4081 {
4084 {
4088 }
4089 }
4091 /* Single-bit compares should always be against zero. */
4093 {
4096 }
4098 /* Make a new bitfield reference, shift the constant over the
4099 appropriate number of bits and mask it with the computed mask
4100 (in case this was a signed field). If we changed it, make a new one. */
4108 mask);
4113 }
4114 \f
4115 /* Subroutine for fold_truth_andor_1: decode a field reference.
4117 If EXP is a comparison reference, we return the innermost reference.
4119 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4120 set to the starting bit number.
4122 If the innermost field can be completely contained in a mode-sized
4123 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4125 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4126 otherwise it is not changed.
4128 *PUNSIGNEDP is set to the signedness of the field.
4130 *PREVERSEP is set to the storage order of the field.
4132 *PMASK is set to the mask used. This is either contained in a
4133 BIT_AND_EXPR or derived from the width of the field.
4135 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4137 Return 0 if this is not a component reference or is one that we can't
4138 do anything with. */
4140 static tree
4145 {
4150 tree unsigned_type;
4153 /* All the optimizations using this function assume integer fields.
4154 There are problems with FP fields since the type_for_size call
4155 below can fail for, e.g., XFmode. */
4159 /* We are interested in the bare arrangement of bits, so strip everything
4160 that doesn't affect the machine mode. However, record the type of the
4161 outermost expression if it may matter below. */
4168 {
4174 }
4181 /* Reject out-of-bound accesses (PR79731). */
4189 /* If the number of bits in the reference is the same as the bitsize of
4190 the outer type, then the outer type gives the signedness. Otherwise
4191 (in case of a small bitfield) the signedness is unchanged. */
4195 /* Compute the mask to access the bitfield. */
4204 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4212 }
4214 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4215 bit positions and MASK is SIGNED. */
4217 static int
4219 {
4223 /* If this function returns true when the type of the mask is
4224 UNSIGNED, then there will be errors. In particular see
4225 gcc.c-torture/execute/990326-1.c. There does not appear to be
4226 any documentation paper trail as to why this is so. But the pre
4227 wide-int worked with that restriction and it has been preserved
4228 here. */
4233 }
4235 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4236 represents the sign bit of EXP's type. If EXP represents a sign
4237 or zero extension, also test VAL against the unextended type.
4238 The return value is the (sub)expression whose sign bit is VAL,
4239 or NULL_TREE otherwise. */
4241 tree
4243 {
4245 tree t;
4247 /* Tree EXP must have an integral type. */
4252 /* Tree VAL must be an integer constant. */
4261 /* Handle extension from a narrower type. */
4267 }
4269 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4270 to be evaluated unconditionally. */
4272 static int
4274 {
4275 /* Strip any conversions that don't change the machine mode. */
4284 /* Don't regard global variables as simple. They may be
4285 allocated in ways unknown to the compiler (shared memory,
4286 #pragma weak, etc). */
4289 /* Weakrefs are not safe to be read, since they can be NULL.
4290 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4291 have DECL_WEAK flag set. */
4293 /* Loading a static variable is unduly expensive, but global
4294 registers aren't expensive. */
4296 }
4298 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4299 to be evaluated unconditionally.
4300 I addition to simple_operand_p, we assume that comparisons, conversions,
4301 and logic-not operations are simple, if their operands are simple, too. */
4303 static bool
4305 {
4325 }
4327 \f
4328 /* The following functions are subroutines to fold_range_test and allow it to
4329 try to change a logical combination of comparisons into a range test.
4331 For example, both
4332 X == 2 || X == 3 || X == 4 || X == 5
4333 and
4334 X >= 2 && X <= 5
4335 are converted to
4336 (unsigned) (X - 2) <= 3
4338 We describe each set of comparisons as being either inside or outside
4339 a range, using a variable named like IN_P, and then describe the
4340 range with a lower and upper bound. If one of the bounds is omitted,
4341 it represents either the highest or lowest value of the type.
4343 In the comments below, we represent a range by two numbers in brackets
4344 preceded by a "+" to designate being inside that range, or a "-" to
4345 designate being outside that range, so the condition can be inverted by
4346 flipping the prefix. An omitted bound is represented by a "-". For
4347 example, "- [-, 10]" means being outside the range starting at the lowest
4348 possible value and ending at 10, in other words, being greater than 10.
4349 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4350 always false.
4352 We set up things so that the missing bounds are handled in a consistent
4353 manner so neither a missing bound nor "true" and "false" need to be
4354 handled using a special case. */
4356 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4357 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4358 and UPPER1_P are nonzero if the respective argument is an upper bound
4359 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4360 must be specified for a comparison. ARG1 will be converted to ARG0's
4361 type if both are specified. */
4363 static tree
4366 {
4367 tree tem;
4371 /* If neither arg represents infinity, do the normal operation.
4372 Else, if not a comparison, return infinity. Else handle the special
4373 comparison rules. Note that most of the cases below won't occur, but
4374 are handled for consistency. */
4377 {
4382 }
4387 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4388 for neither. In real maths, we cannot assume open ended ranges are
4389 the same. But, this is computer arithmetic, where numbers are finite.
4390 We can therefore make the transformation of any unbounded range with
4391 the value Z, Z being greater than any representable number. This permits
4392 us to treat unbounded ranges as equal. */
4396 {
4417 }
4420 }
4421 \f
4422 /* Helper routine for make_range. Perform one step for it, return
4423 new expression if the loop should continue or NULL_TREE if it should
4424 stop. */
4426 tree
4430 {
4436 {
4438 /* We can only do something if the range is testing for zero. */
4447 /* We can only do something if the range is testing for zero
4448 and if the second operand is an integer constant. Note that
4449 saying something is "in" the range we make is done by
4450 complementing IN_P since it will set in the initial case of
4451 being not equal to zero; "out" is leaving it alone. */
4458 {
4479 }
4481 /* If this is an unsigned comparison, we also know that EXP is
4482 greater than or equal to zero. We base the range tests we make
4483 on that fact, so we record it here so we can parse existing
4484 range tests. We test arg0_type since often the return type
4485 of, e.g. EQ_EXPR, is boolean. */
4487 {
4491 NULL_TREE))
4496 /* If the high bound is missing, but we have a nonzero low
4497 bound, reverse the range so it goes from zero to the low bound
4498 minus 1. */
4500 {
4505 }
4506 }
4514 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4515 low and high are non-NULL, then normalize will DTRT. */
4518 {
4523 }
4525 /* (-x) IN [a,b] -> x in [-b, -a] */
4537 /* ~ X -> -X - 1 */
4546 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4547 move a constant to the other side. */
4552 /* If EXP is signed, any overflow in the computation is undefined,
4553 so we don't worry about it so long as our computations on
4554 the bounds don't overflow. For unsigned, overflow is defined
4555 and this is exactly the right thing. */
4567 normalize:
4568 /* Check for an unsigned range which has wrapped around the maximum
4569 value thus making n_high < n_low, and normalize it. */
4571 {
4577 /* If the range is of the form +/- [ x+1, x ], we won't
4578 be able to normalize it. But then, it represents the
4579 whole range or the empty set, so make it
4580 +/- [ -, - ]. */
4584 else
4586 }
4587 else
4595 CASE_CONVERT:
4613 /* If we're converting arg0 from an unsigned type, to exp,
4614 a signed type, we will be doing the comparison as unsigned.
4615 The tests above have already verified that LOW and HIGH
4616 are both positive.
4618 So we have to ensure that we will handle large unsigned
4619 values the same way that the current signed bounds treat
4620 negative values. */
4623 {
4624 tree high_positive;
4625 tree equiv_type;
4626 /* For fixed-point modes, we need to pass the saturating flag
4627 as the 2nd parameter. */
4629 equiv_type
4632 else
4633 equiv_type
4636 /* A range without an upper bound is, naturally, unbounded.
4637 Since convert would have cropped a very large value, use
4638 the max value for the destination type. */
4639 high_positive
4646 high_positive),
4649 /* If the low bound is specified, "and" the range with the
4650 range for which the original unsigned value will be
4651 positive. */
4653 {
4656 integer_zero_node),
4657 high_positive))
4661 }
4662 else
4663 {
4664 /* Otherwise, "or" the range with the range of the input
4665 that will be interpreted as negative. */
4668 integer_zero_node),
4669 high_positive))
4673 }
4674 }
4683 }
4684 }
4686 /* Given EXP, a logical expression, set the range it is testing into
4687 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4688 actually being tested. *PLOW and *PHIGH will be made of the same
4689 type as the returned expression. If EXP is not a comparison, we
4690 will most likely not be returning a useful value and range. Set
4691 *STRICT_OVERFLOW_P to true if the return value is only valid
4692 because signed overflow is undefined; otherwise, do not change
4693 *STRICT_OVERFLOW_P. */
4695 tree
4698 {
4706 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4707 and see if we can refine the range. Some of the cases below may not
4708 happen, but it doesn't seem worth worrying about this. We "continue"
4709 the outer loop when we've changed something; otherwise we "break"
4710 the switch, which will "break" the while. */
4716 {
4722 {
4730 }
4739 }
4741 /* If EXP is a constant, we can evaluate whether this is true or false. */
4743 {
4750 }
4754 }
4756 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4757 a bitwise check i.e. when
4758 LOW == 0xXX...X00...0
4759 HIGH == 0xXX...X11...1
4760 Return corresponding mask in MASK and stem in VALUE. */
4762 static bool
4765 {
4788 }
4789 \f
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.
4873 First make sure that arithmetics in this type is valid, then make sure
4874 that it wraps around. */
4880 {
4883 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4884 for the type in question, as we rely on this here. */
4894 else
4896 }
4906 {
4908 {
4913 }
4915 }
4923 }
4924 \f
4925 /* Return the predecessor of VAL in its type, handling the infinite case. */
4927 static tree
4929 {
4935 else
4938 }
4940 /* Return the successor of VAL in its type, handling the infinite case. */
4942 static tree
4944 {
4950 else
4953 }
4955 /* Given two ranges, see if we can merge them into one. Return 1 if we
4956 can, 0 if we can't. Set the output range into the specified parameters. */
4958 bool
4961 {
4965 tree tem;
4975 /* Make range 0 be the range that starts first, or ends last if they
4976 start at the same value. Swap them if it isn't. */
4979 || (lowequal
4982 {
4986 }
4988 /* Now flag two cases, whether the ranges are disjoint or whether the
4989 second range is totally subsumed in the first. Note that the tests
4990 below are simplified by the ones above. */
4996 /* We now have four cases, depending on whether we are including or
4997 excluding the two ranges. */
4999 {
5000 /* If they don't overlap, the result is false. If the second range
5001 is a subset it is the result. Otherwise, the range is from the start
5002 of the second to the end of the first. */
5007 else
5009 }
5012 {
5013 /* If they don't overlap, the result is the first range. If they are
5014 equal, the result is false. If the second range is a subset of the
5015 first, and the ranges begin at the same place, we go from just after
5016 the end of the second range to the end of the first. If the second
5017 range is not a subset of the first, or if it is a subset and both
5018 ranges end at the same place, the range starts at the start of the
5019 first range and ends just before the second range.
5020 Otherwise, we can't describe this as a single range. */
5026 {
5031 {
5032 /* We are in the weird situation where high0 > high1 but
5033 high1 has no successor. Punt. */
5035 }
5036 }
5038 {
5043 {
5044 /* low0 < low1 but low1 has no predecessor. Punt. */
5046 }
5047 }
5048 else
5050 }
5053 {
5054 /* If they don't overlap, the result is the second range. If the second
5055 is a subset of the first, the result is false. Otherwise,
5056 the range starts just after the first range and ends at the
5057 end of the second. */
5062 else
5063 {
5068 {
5069 /* high1 > high0 but high0 has no successor. Punt. */
5071 }
5072 }
5073 }
5075 else
5076 {
5077 /* The case where we are excluding both ranges. Here the complex case
5078 is if they don't overlap. In that case, the only time we have a
5079 range is if they are adjacent. If the second is a subset of the
5080 first, the result is the first. Otherwise, the range to exclude
5081 starts at the beginning of the first range and ends at the end of the
5082 second. */
5084 {
5089 else
5090 {
5091 /* Canonicalize - [min, x] into - [-, x]. */
5094 {
5099 /* FALLTHROUGH */
5112 }
5114 /* Canonicalize - [x, max] into - [x, -]. */
5117 {
5122 /* FALLTHROUGH */
5138 }
5140 /* The ranges might be also adjacent between the maximum and
5141 minimum values of the given type. For
5142 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5143 return + [x + 1, y - 1]. */
5145 {
5152 }
5153 else
5155 }
5156 }
5159 else
5161 }
5165 }
5166 \f
5168 /* Subroutine of fold, looking inside expressions of the form
5169 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5170 of the COND_EXPR. This function is being used also to optimize
5171 A op B ? C : A, by reversing the comparison first.
5173 Return a folded expression whose code is not a COND_EXPR
5174 anymore, or NULL_TREE if no folding opportunity is found. */
5176 static tree
5179 {
5184 tree tem;
5189 /* If we have A op 0 ? A : -A, consider applying the following
5190 transformations:
5192 A == 0? A : -A same as -A
5193 A != 0? A : -A same as A
5194 A >= 0? A : -A same as abs (A)
5195 A > 0? A : -A same as abs (A)
5196 A <= 0? A : -A same as -abs (A)
5197 A < 0? A : -A same as -abs (A)
5199 None of these transformations work for modes with signed
5200 zeros. If A is +/-0, the first two transformations will
5201 change the sign of the result (from +0 to -0, or vice
5202 versa). The last four will fix the sign of the result,
5203 even though the original expressions could be positive or
5204 negative, depending on the sign of A.
5206 Note that all these transformations are correct if A is
5207 NaN, since the two alternatives (A and -A) are also NaNs. */
5214 /* In the case that A is of the form X-Y, '-A' (arg2) may
5215 have already been folded to Y-X, check for that. */
5223 {
5235 /* Fall through. */
5246 /* FALLTHRU */
5256 }
5258 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5259 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5260 both transformations are correct when A is NaN: A != 0
5261 is then true, and A == 0 is false. */
5265 {
5270 }
5272 /* Try some transformations of A op B ? A : B.
5274 A == B? A : B same as B
5275 A != B? A : B same as A
5276 A >= B? A : B same as max (A, B)
5277 A > B? A : B same as max (B, A)
5278 A <= B? A : B same as min (A, B)
5279 A < B? A : B same as min (B, A)
5281 As above, these transformations don't work in the presence
5282 of signed zeros. For example, if A and B are zeros of
5283 opposite sign, the first two transformations will change
5284 the sign of the result. In the last four, the original
5285 expressions give different results for (A=+0, B=-0) and
5286 (A=-0, B=+0), but the transformed expressions do not.
5288 The first two transformations are correct if either A or B
5289 is a NaN. In the first transformation, the condition will
5290 be false, and B will indeed be chosen. In the case of the
5291 second transformation, the condition A != B will be true,
5292 and A will be chosen.
5294 The conversions to max() and min() are not correct if B is
5295 a number and A is not. The conditions in the original
5296 expressions will be false, so all four give B. The min()
5297 and max() versions would give a NaN instead. */
5300 /* Avoid these transformations if the COND_EXPR may be used
5301 as an lvalue in the C++ front-end. PR c++/19199. */
5302 && (in_gimple_form
5308 {
5314 {
5323 /* In C++ a ?: expression can be an lvalue, so put the
5324 operand which will be used if they are equal first
5325 so that we can convert this back to the
5326 corresponding COND_EXPR. */
5328 {
5336 }
5343 {
5351 }
5364 }
5365 }
5368 }
5371 \f
5372 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5373 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5374 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5375 false) >= 2)
5376 #endif
5378 /* EXP is some logical combination of boolean tests. See if we can
5379 merge it into some range test. Return the new tree if so. */
5381 static tree
5384 {
5400 /* If this is an OR operation, invert both sides; we will invert
5401 again at the end. */
5405 /* If both expressions are the same, if we can merge the ranges, and we
5406 can build the range test, return it or it inverted. If one of the
5407 ranges is always true or always false, consider it to be the same
5408 expression as the other. */
5416 {
5420 }
5422 /* On machines where the branch cost is expensive, if this is a
5423 short-circuited branch and the underlying object on both sides
5424 is the same, make a non-short-circuit operation. */
5430 {
5431 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5432 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5433 which cases we can't do this. */
5441 {
5450 {
5453 WARN_STRICT_OVERFLOW_COMPARISON);
5457 }
5458 }
5459 }
5462 }
5463 \f
5464 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5465 bit value. Arrange things so the extra bits will be set to zero if and
5466 only if C is signed-extended to its full width. If MASK is nonzero,
5467 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5469 static tree
5471 {
5474 tree temp;
5479 /* We work by getting just the sign bit into the low-order bit, then
5480 into the high-order bit, then sign-extend. We then XOR that value
5481 with C. */
5484 /* We must use a signed type in order to get an arithmetic right shift.
5485 However, we must also avoid introducing accidental overflows, so that
5486 a subsequent call to integer_zerop will work. Hence we must
5487 do the type conversion here. At this point, the constant is either
5488 zero or one, and the conversion to a signed type can never overflow.
5489 We could get an overflow if this conversion is done anywhere else. */
5498 /* If necessary, convert the type back to match the type of C. */
5503 }
5504 \f
5505 /* For an expression that has the form
5506 (A && B) || ~B
5507 or
5508 (A || B) && ~B,
5509 we can drop one of the inner expressions and simplify to
5510 A || ~B
5511 or
5512 A && ~B
5513 LOC is the location of the resulting expression. OP is the inner
5514 logical operation; the left-hand side in the examples above, while CMPOP
5515 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5516 removing a condition that guards another, as in
5517 (A != NULL && A->...) || A == NULL
5518 which we must not transform. If RHS_ONLY is true, only eliminate the
5519 right-most operand of the inner logical operation. */
5521 static tree
5524 {
5542 {
5545 {
5548 }
5549 }
5551 {
5554 {
5557 }
5558 }
5573 }
5575 /* Find ways of folding logical expressions of LHS and RHS:
5576 Try to merge two comparisons to the same innermost item.
5577 Look for range tests like "ch >= '0' && ch <= '9'".
5578 Look for combinations of simple terms on machines with expensive branches
5579 and evaluate the RHS unconditionally.
5581 For example, if we have p->a == 2 && p->b == 4 and we can make an
5582 object large enough to span both A and B, we can do this with a comparison
5583 against the object ANDed with the a mask.
5585 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5586 operations to do this with one comparison.
5588 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5589 function and the one above.
5591 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5592 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5594 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5595 two operands.
5597 We return the simplified tree or 0 if no optimization is possible. */
5599 static tree
5602 {
5603 /* If this is the "or" of two comparisons, we can do something if
5604 the comparisons are NE_EXPR. If this is the "and", we can do something
5605 if the comparisons are EQ_EXPR. I.e.,
5606 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5608 WANTED_CODE is this operation code. For single bit fields, we can
5609 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5610 comparison for one-bit fields. */
5631 /* Start by getting the comparison codes. Fail if anything is volatile.
5632 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5633 it were surrounded with a NE_EXPR. */
5642 {
5646 }
5649 {
5653 }
5664 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5667 {
5670 {
5675 }
5678 {
5684 }
5685 }
5690 /* If the RHS can be evaluated unconditionally and its operands are
5691 simple, it wins to evaluate the RHS unconditionally on machines
5692 with expensive branches. In this case, this isn't a comparison
5693 that can be merged. */
5700 {
5701 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5712 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5722 }
5724 /* See if the comparisons can be merged. Then get all the parameters for
5725 each side. */
5750 /* It must be true that the inner operation on the lhs of each
5751 comparison must be the same if we are to be able to do anything.
5752 Then see if we have constants. If not, the same must be true for
5753 the rhs's. */
5762 {
5765 }
5770 else
5773 /* If either comparison code is not correct for our logical operation,
5774 fail. However, we can convert a one-bit comparison against zero into
5775 the opposite comparison against that bit being set in the field. */
5779 {
5781 {
5782 /* Make the left operand unsigned, since we are only interested
5783 in the value of one bit. Otherwise we are doing the wrong
5784 thing below. */
5787 }
5788 else
5790 }
5792 /* This is analogous to the code for l_const above. */
5794 {
5796 {
5799 }
5800 else
5802 }
5804 /* See if we can find a mode that contains both fields being compared on
5805 the left. If we can't, fail. Otherwise, update all constants and masks
5806 to be relative to a field of that size. */
5811 volatilep);
5821 {
5824 }
5832 {
5839 {
5843 }
5844 }
5846 {
5853 {
5857 }
5858 }
5860 /* If the right sides are not constant, do the same for it. Also,
5861 disallow this optimization if a size or signedness mismatch occurs
5862 between the left and right sides. */
5864 {
5867 /* Make sure the two fields on the right
5868 correspond to the left without being swapped. */
5876 volatilep);
5886 {
5889 }
5898 /* Make a mask that corresponds to both fields being compared.
5899 Do this for both items being compared. If the operands are the
5900 same size and the bits being compared are in the same position
5901 then we can do this by masking both and comparing the masked
5902 results. */
5906 {
5920 }
5922 /* There is still another way we can do something: If both pairs of
5923 fields being compared are adjacent, we may be able to make a wider
5924 field containing them both.
5926 Note that we still must mask the lhs/rhs expressions. Furthermore,
5927 the mask must be shifted to account for the shift done by
5928 make_bit_field_ref. */
5933 {
5934 tree type;
5950 /* Convert to the smaller type before masking out unwanted bits. */
5953 {
5955 {
5959 }
5961 {
5965 }
5966 }
5975 }
5978 }
5980 /* Handle the case of comparisons with constants. If there is something in
5981 common between the masks, those bits of the constants must be the same.
5982 If not, the condition is always false. Test for this to avoid generating
5983 incorrect code below. */
5988 {
5990 {
5993 }
5994 else
5995 {
5998 }
5999 }
6001 /* Construct the expression we will return. First get the component
6002 reference we will make. Unless the mask is all ones the width of
6003 that field, perform the mask operation. Then compare with the
6004 merged constant. */
6015 }
6016 \f
6017 /* T is an integer expression that is being multiplied, divided, or taken a
6018 modulus (CODE says which and what kind of divide or modulus) by a
6019 constant C. See if we can eliminate that operation by folding it with
6020 other operations already in T. WIDE_TYPE, if non-null, is a type that
6021 should be used for the computation if wider than our type.
6023 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6024 (X * 2) + (Y * 4). We must, however, be assured that either the original
6025 expression would not overflow or that overflow is undefined for the type
6026 in the language in question.
6028 If we return a non-null expression, it is an equivalent form of the
6029 original computation, but need not be in the original type.
6031 We set *STRICT_OVERFLOW_P to true if the return values depends on
6032 signed overflow being undefined. Otherwise we do not change
6033 *STRICT_OVERFLOW_P. */
6035 static tree
6038 {
6039 /* To avoid exponential search depth, refuse to allow recursion past
6040 three levels. Beyond that (1) it's highly unlikely that we'll find
6041 something interesting and (2) we've probably processed it before
6042 when we built the inner expression. */
6045 tree ret;
6050 depth++;
6052 depth--;
6055 }
6057 static tree
6060 {
6071 /* Don't deal with constants of zero here; they confuse the code below. */
6081 /* Note that we need not handle conditional operations here since fold
6082 already handles those cases. So just do arithmetic here. */
6084 {
6086 /* For a constant, we can always simplify if we are a multiply
6087 or (for divide and modulus) if it is a multiple of our constant. */
6090 {
6093 /* If the multiplication overflowed, we lost information on it.
6094 See PR68142 and PR69845. */
6098 }
6102 /* If op0 is an expression ... */
6108 /* ... and has wrapping overflow, and its type is smaller
6109 than ctype, then we cannot pass through as widening. */
6114 /* ... or this is a truncation (t is narrower than op0),
6115 then we cannot pass through this narrowing. */
6118 /* ... or signedness changes for division or modulus,
6119 then we cannot pass through this conversion. */
6123 /* ... or has undefined overflow while the converted to
6124 type has not, we cannot do the operation in the inner type
6125 as that would introduce undefined overflow. */
6131 /* Pass the constant down and see if we can make a simplification. If
6132 we can, replace this expression with the inner simplification for
6133 possible later conversion to our or some other type. */
6138 code == MULT_EXPR
6140 strict_overflow_p))))
6145 /* If widening the type changes it from signed to unsigned, then we
6146 must avoid building ABS_EXPR itself as unsigned. */
6148 {
6152 {
6155 }
6157 }
6158 /* If the constant is negative, we cannot simplify this. */
6161 /* FALLTHROUGH */
6163 /* For division and modulus, type can't be unsigned, as e.g.
6164 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6165 For signed types, even with wrapping overflow, this is fine. */
6174 /* If widening the type changes the signedness, then we can't perform
6175 this optimization as that changes the result. */
6179 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6185 {
6192 }
6196 /* If the second operand is constant, this is a multiplication
6197 or floor division, by a power of two, so we can treat it that
6198 way unless the multiplier or divisor overflows. Signed
6199 left-shift overflow is implementation-defined rather than
6200 undefined in C90, so do not convert signed left shift into
6201 multiplication. */
6204 /* const_binop may not detect overflow correctly,
6205 so check for it explicitly here. */
6209 size_one_node,
6210 op1)))
6214 ctype,
6216 t1),
6221 /* See if we can eliminate the operation on both sides. If we can, we
6222 can return a new PLUS or MINUS. If we can't, the only remaining
6223 cases where we can do anything are if the second operand is a
6224 constant. */
6231 /* If not multiplication, we can only do this if both operands
6232 are divisible by c. */
6235 {
6240 }
6242 /* If this was a subtraction, negate OP1 and set it to be an addition.
6243 This simplifies the logic below. */
6245 {
6247 /* If OP1 was not easily negatable, the constant may be OP0. */
6249 {
6252 }
6253 }
6258 /* If either OP1 or C are negative, this optimization is not safe for
6259 some of the division and remainder types while for others we need
6260 to change the code. */
6262 {
6270 }
6272 /* If it's a multiply or a division/modulus operation of a multiple
6273 of our constant, do the operation and verify it doesn't overflow. */
6276 {
6279 /* We allow the constant to overflow with wrapping semantics. */
6283 }
6284 else
6287 /* If we have an unsigned type, we cannot widen the operation since it
6288 will change the result if the original computation overflowed. */
6292 /* The last case is if we are a multiply. In that case, we can
6293 apply the distributive law to commute the multiply and addition
6294 if the multiplication of the constants doesn't overflow
6295 and overflow is defined. With undefined overflow
6296 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6302 op1);
6307 /* We have a special case here if we are doing something like
6308 (C * 8) % 4 since we know that's zero. */
6311 /* If the multiplication can overflow we cannot optimize this. */
6315 {
6318 }
6320 /* ... fall through ... */
6324 /* If we can extract our operation from the LHS, do so and return a
6325 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6326 do something only if the second operand is a constant. */
6342 /* If these are the same operation types, we can associate them
6343 assuming no overflow. */
6345 {
6360 }
6362 /* If these operations "cancel" each other, we have the main
6363 optimizations of this pass, which occur when either constant is a
6364 multiple of the other, in which case we replace this with either an
6365 operation or CODE or TCODE.
6367 If we have an unsigned type, we cannot do this since it will change
6368 the result if the original computation overflowed. */
6375 {
6377 {
6384 }
6386 {
6393 }
6394 }
6399 }
6402 }
6403 \f
6404 /* Return a node which has the indicated constant VALUE (either 0 or
6405 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6406 and is of the indicated TYPE. */
6408 tree
6410 {
6419 else
6421 }
6424 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6425 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6426 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6427 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6428 COND is the first argument to CODE; otherwise (as in the example
6429 given here), it is the second argument. TYPE is the type of the
6430 original expression. Return NULL_TREE if no simplification is
6431 possible. */
6433 static tree
6438 {
6448 {
6452 /* If this operand throws an expression, then it does not make
6453 sense to try to perform a logical or arithmetic operation
6454 involving it. */
6459 }
6462 {
6467 }
6468 else
6469 /* Detect the case of mixing vector and scalar types - bail out. */
6475 /* This transformation is only worthwhile if we don't have to wrap ARG
6476 in a SAVE_EXPR and the operation can be simplified without recursing
6477 on at least one of the branches once its pushed inside the COND_EXPR. */
6486 {
6490 else
6492 }
6494 {
6498 else
6500 }
6502 /* Check that we have simplified at least one of the branches. */
6507 }
6509 \f
6510 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6512 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6513 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6514 ADDEND is the same as X.
6516 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6517 and finite. The problematic cases are when X is zero, and its mode
6518 has signed zeros. In the case of rounding towards -infinity,
6519 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6520 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6522 bool
6524 {
6528 /* Don't allow the fold with -fsignaling-nans. */
6532 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6536 /* In a vector or complex, we would need to check the sign of all zeros. */
6540 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6544 /* The mode has signed zeros, and we have to honor their sign.
6545 In this situation, there is only one case we can return true for.
6546 X - 0 is the same as X unless rounding towards -infinity is
6547 supported. */
6549 }
6551 /* Subroutine of fold() that optimizes comparisons of a division by
6552 a nonzero integer constant against an integer constant, i.e.
6553 X/C1 op C2.
6555 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6556 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6557 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6559 The function returns the constant folded tree if a simplification
6560 can be made, and NULL_TREE otherwise. */
6562 static tree
6565 {
6573 /* We have to do this the hard way to detect unsigned overflow.
6574 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6580 {
6585 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6589 }
6591 {
6595 {
6614 }
6615 }
6616 else
6617 {
6618 /* A negative divisor reverses the relational operators. */
6624 {
6643 }
6644 }
6647 {
6668 {
6671 }
6676 {
6679 }
6684 {
6687 }
6692 {
6695 }
6700 }
6703 }
6706 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6707 equality/inequality test, then return a simplified form of the test
6708 using a sign testing. Otherwise return NULL. TYPE is the desired
6709 result type. */
6711 static tree
6714 tree result_type)
6715 {
6716 /* If this is testing a single bit, we can optimize the test. */
6720 {
6721 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6722 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6726 /* This is only a win if casting to a signed type is cheap,
6727 i.e. when arg00's type is not a partial mode. */
6730 {
6733 result_type,
6736 }
6737 }
6740 }
6742 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6743 equality/inequality test, then return a simplified form of
6744 the test using shifts and logical operations. Otherwise return
6745 NULL. TYPE is the desired result type. */
6747 tree
6750 {
6751 /* If this is testing a single bit, we can optimize the test. */
6755 {
6764 /* First, see if we can fold the single bit test into a sign-bit
6765 test. */
6767 result_type);
6771 /* Otherwise we have (A & C) != 0 where C is a single bit,
6772 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6773 Similarly for (A & C) == 0. */
6775 /* If INNER is a right shift of a constant and it plus BITNUM does
6776 not overflow, adjust BITNUM and INNER. */
6782 {
6785 }
6787 /* If we are going to be able to omit the AND below, we must do our
6788 operations as unsigned. If we must use the AND, we have a choice.
6789 Normally unsigned is faster, but for some machines signed is. */
6807 /* Put the AND last so it can combine with more things. */
6810 /* Make sure to return the proper type. */
6814 }
6816 }
6818 /* Test whether it is preferable two swap two operands, ARG0 and
6819 ARG1, for example because ARG0 is an integer constant and ARG1
6820 isn't. */
6822 bool
6824 {
6838 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6839 for commutative and comparison operators. Ensuring a canonical
6840 form allows the optimizers to find additional redundancies without
6841 having to explicitly check for both orderings. */
6847 /* Put SSA_NAMEs last. */
6853 /* Put variables last. */
6860 }
6863 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6864 means A >= Y && A != MAX, but in this case we know that
6865 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6867 static tree
6869 {
6876 else
6885 {
6888 }
6890 {
6893 }
6894 else
6901 {
6902 /* Convert the pointer types into integer before taking the difference. */
6906 }
6907 else
6914 }
6916 /* Fold a sum or difference of at least one multiplication.
6917 Returns the folded tree or NULL if no simplification could be made. */
6919 static tree
6922 {
6926 /* (A * C) +- (B * C) -> (A+-B) * C.
6927 (A * C) +- A -> A * (C+-1).
6928 We are most concerned about the case where C is a constant,
6929 but other combinations show up during loop reduction. Since
6930 it is not difficult, try all four possibilities. */
6933 {
6936 }
6938 {
6941 }
6942 else
6943 {
6944 /* We cannot generate constant 1 for fract. */
6949 }
6951 {
6954 }
6956 {
6958 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6959 the purpose of this canonicalization. */
6963 {
6966 }
6967 else
6969 }
6970 else
6971 {
6972 /* We cannot generate constant 1 for fract. */
6977 }
6980 /* Prefer factoring a common non-constant. */
6990 /* No identical multiplicands; see if we can find a common
6991 power-of-two factor in non-power-of-two multiplies. This
6992 can help in multi-dimensional array access. */
6995 {
6998 tree maybe_same;
7002 /* Move min of absolute values to int11. */
7004 {
7009 }
7010 else
7014 /* The remainder should not be a constant, otherwise we
7015 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7016 increased the number of multiplications necessary. */
7018 {
7026 }
7027 }
7034 /* We are neither factoring zero nor minus one. */
7042 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7043 same may be minus one and thus the multiplication may overflow. Perform
7044 the operations in an unsigned type. */
7049 /* If the sum evaluated to a constant that is not -INF the multiplication
7050 cannot overflow. */
7059 }
7061 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7062 specified by EXPR into the buffer PTR of length LEN bytes.
7063 Return the number of bytes placed in the buffer, or zero
7064 upon failure. */
7066 static int
7068 {
7082 {
7084 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7085 number of bytes. */
7089 {
7096 else
7098 }
7099 else
7104 }
7106 }
7109 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7110 specified by EXPR into the buffer PTR of length LEN bytes.
7111 Return the number of bytes placed in the buffer, or zero
7112 upon failure. */
7114 static int
7116 {
7120 FIXED_VALUE_TYPE value;
7136 }
7139 /* Subroutine of native_encode_expr. Encode the REAL_CST
7140 specified by EXPR into the buffer PTR of length LEN bytes.
7141 Return the number of bytes placed in the buffer, or zero
7142 upon failure. */
7144 static int
7146 {
7152 /* There are always 32 bits in each long, no matter the size of
7153 the hosts long. We handle floating point representations with
7154 up to 192 bits. */
7168 {
7173 {
7180 else
7182 }
7183 else
7184 {
7187 {
7188 /* Reverse bytes within each long, or within the entire float
7189 if it's smaller than a long (for HFmode). */
7192 }
7193 }
7198 }
7200 }
7202 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7203 specified by EXPR into the buffer PTR of length LEN bytes.
7204 Return the number of bytes placed in the buffer, or zero
7205 upon failure. */
7207 static int
7209 {
7211 tree part;
7226 }
7229 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7230 specified by EXPR into the buffer PTR of length LEN bytes.
7231 Return the number of bytes placed in the buffer, or zero
7232 upon failure. */
7234 static int
7236 {
7246 {
7248 {
7251 }
7262 }
7264 }
7267 /* Subroutine of native_encode_expr. Encode the STRING_CST
7268 specified by EXPR into the buffer PTR of length LEN bytes.
7269 Return the number of bytes placed in the buffer, or zero
7270 upon failure. */
7272 static int
7274 {
7276 HOST_WIDE_INT total_bytes;
7290 {
7293 {
7296 }
7299 }
7300 else
7303 }
7306 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7307 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7308 buffer PTR of length LEN bytes. If OFF is not -1 then start
7309 the encoding at byte offset OFF and encode at most LEN bytes.
7310 Return the number of bytes placed in the buffer, or zero upon failure. */
7312 int
7314 {
7315 /* We don't support starting at negative offset and -1 is special. */
7320 {
7341 }
7342 }
7345 /* Subroutine of native_interpret_expr. Interpret the contents of
7346 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7347 If the buffer cannot be interpreted, return NULL_TREE. */
7349 static tree
7351 {
7361 }
7364 /* Subroutine of native_interpret_expr. Interpret the contents of
7365 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7366 If the buffer cannot be interpreted, return NULL_TREE. */
7368 static tree
7370 {
7372 double_int result;
7373 FIXED_VALUE_TYPE fixed_value;
7383 }
7386 /* Subroutine of native_interpret_expr. Interpret the contents of
7387 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7388 If the buffer cannot be interpreted, return NULL_TREE. */
7390 static tree
7392 {
7396 /* There are always 32 bits in each long, no matter the size of
7397 the hosts long. We handle floating point representations with
7398 up to 192 bits. */
7399 REAL_VALUE_TYPE r;
7410 {
7411 /* Both OFFSET and BYTE index within a long;
7412 bitpos indexes the whole float. */
7415 {
7422 else
7424 }
7425 else
7426 {
7429 {
7430 /* Reverse bytes within each long, or within the entire float
7431 if it's smaller than a long (for HFmode). */
7434 }
7435 }
7439 }
7443 }
7446 /* Subroutine of native_interpret_expr. Interpret the contents of
7447 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7448 If the buffer cannot be interpreted, return NULL_TREE. */
7450 static tree
7452 {
7467 }
7470 /* Subroutine of native_interpret_expr. Interpret the contents of
7471 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7472 If the buffer cannot be interpreted, return NULL_TREE. */
7474 static tree
7476 {
7489 {
7494 }
7496 }
7499 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7500 the buffer PTR of length LEN as a constant of type TYPE. For
7501 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7502 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7503 return NULL_TREE. */
7505 tree
7507 {
7509 {
7531 }
7532 }
7534 /* Returns true if we can interpret the contents of a native encoding
7535 as TYPE. */
7537 static bool
7539 {
7541 {
7554 }
7555 }
7557 /* Return true iff a constant of type TYPE is accepted by
7558 native_encode_expr. */
7560 bool
7562 {
7564 {
7574 }
7575 }
7577 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7578 TYPE at compile-time. If we're unable to perform the conversion
7579 return NULL_TREE. */
7581 static tree
7583 {
7584 /* We support up to 512-bit values (for V8DFmode). */
7588 /* Check that the host and target are sane. */
7597 }
7599 /* Build an expression for the address of T. Folds away INDIRECT_REF
7600 to avoid confusing the gimplify process. */
7602 tree
7604 {
7605 /* The size of the object is not relevant when talking about its address. */
7610 {
7615 }
7625 {
7630 }
7631 else
7635 }
7637 /* Build an expression for the address of T. */
7639 tree
7641 {
7645 }
7647 /* Fold a unary expression of code CODE and type TYPE with operand
7648 OP0. Return the folded expression if folding is successful.
7649 Otherwise, return NULL_TREE. */
7651 tree
7653 {
7654 tree tem;
7655 tree arg0;
7663 {
7666 {
7667 /* Don't use STRIP_NOPS, because signedness of argument type
7668 matters. */
7670 }
7671 else
7672 {
7673 /* Strip any conversions that don't change the mode. This
7674 is safe for every expression, except for a comparison
7675 expression because its signedness is derived from its
7676 operands.
7678 Note that this is done as an internal manipulation within
7679 the constant folder, in order to find the simplest
7680 representation of the arguments so that their form can be
7681 studied. In any cases, the appropriate type conversions
7682 should be put back in the tree that will get out of the
7683 constant folder. */
7685 }
7688 {
7691 {
7695 }
7696 }
7697 }
7704 {
7711 {
7725 /* If this was a conversion, and all we did was to move into
7726 inside the COND_EXPR, bring it back out. But leave it if
7727 it is a conversion from integer to integer and the
7728 result precision is no wider than a word since such a
7729 conversion is cheap and may be optimized away by combine,
7730 while it couldn't if it were outside the COND_EXPR. Then return
7731 so we don't get into an infinite recursion loop taking the
7732 conversion out and then back in. */
7744 && (INTEGRAL_TYPE_P
7757 }
7758 }
7761 {
7767 CASE_CONVERT:
7771 {
7772 /* If we have (type) (a CMP b) and type is an integral type, return
7773 new expression involving the new type. Canonicalize
7774 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7775 non-integral type.
7776 Do not fold the result as that would not simplify further, also
7777 folding again results in recursions. */
7787 }
7789 /* Handle (T *)&A.B.C for A being of type T and B and C
7790 living at offset zero. This occurs frequently in
7791 C++ upcasting and then accessing the base. */
7795 {
7797 tree offset;
7798 machine_mode mode;
7800 tree base
7804 /* If the reference was to a (constant) zero offset, we can use
7805 the address of the base if it has the same base type
7806 as the result type and the pointer type is unqualified. */
7813 }
7817 /* Detect assigning a bitfield. */
7819 && DECL_BIT_FIELD
7821 {
7822 /* Don't leave an assignment inside a conversion
7823 unless assigning a bitfield. */
7825 /* First do the assignment, then return converted constant. */
7830 }
7832 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7833 constants (if x has signed type, the sign bit cannot be set
7834 in c). This folds extension into the BIT_AND_EXPR.
7835 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7836 very likely don't have maximal range for their precision and this
7837 transformation effectively doesn't preserve non-maximal ranges. */
7841 {
7852 <= HOST_BITS_PER_WIDE_INT
7854 {
7858 cst &= HOST_WIDE_INT_M1U
7862 && !flag_syntax_only
7865 {
7869 }
7870 }
7872 {
7877 }
7878 }
7880 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7881 cast (T1)X will fold away. We assume that this happens when X itself
7882 is a cast. */
7886 {
7890 return fold_build_pointer_plus_loc
7892 }
7894 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7895 of the same precision, and X is an integer type not narrower than
7896 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7902 {
7908 }
7910 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7911 type of X and Y (integer types only). */
7916 {
7917 /* Be careful not to introduce new overflows. */
7918 tree mult_type;
7921 else
7925 {
7932 }
7933 }
7939 {
7946 }
7957 /* Convert fabs((double)float) into (double)fabsf(float). */
7960 {
7966 targ0));
7967 }
7971 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7990 /* Note that the operand of this must be an int
7991 and its values must be 0 or 1.
7992 ("true" is a fixed value perhaps depending on the language,
7993 but we don't handle values other than 1 correctly yet.) */
8000 /* Fold *&X to X if X is an lvalue. */
8002 {
8009 }
8015 }
8018 /* If the operation was a conversion do _not_ mark a resulting constant
8019 with TREE_OVERFLOW if the original constant was not. These conversions
8020 have implementation defined behavior and retaining the TREE_OVERFLOW
8021 flag here would confuse later passes such as VRP. */
8022 tree
8025 {
8034 }
8036 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8037 operands OP0 and OP1. LOC is the location of the resulting expression.
8038 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8039 Return the folded expression if folding is successful. Otherwise,
8040 return NULL_TREE. */
8041 static tree
8044 {
8045 tree tem;
8047 /* We only do these simplifications if we are optimizing. */
8051 /* Check for things like (A || B) && (A || C). We can convert this
8052 to A || (B && C). Note that either operator can be any of the four
8053 truth and/or operations and the transformation will still be
8054 valid. Also note that we only care about order for the
8055 ANDIF and ORIF operators. If B contains side effects, this
8056 might change the truth-value of A. */
8063 {
8083 /* This case if tricky because we must either have commutative
8084 operators or else A10 must not have side-effects. */
8090 a01);
8091 }
8093 /* See if we can build a range comparison. */
8099 {
8103 }
8107 {
8111 }
8113 /* Check for the possibility of merging component references. If our
8114 lhs is another similar operation, try to merge its rhs with our
8115 rhs. Then try to merge our lhs and rhs. */
8129 {
8136 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8137 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8138 We don't want to pack more than two leafs to a non-IF AND/OR
8139 expression.
8140 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8141 equal to IF-CODE, then we don't want to add right-hand operand.
8142 If the inner right-hand side of left-hand operand has
8143 side-effects, or isn't simple, then we can't add to it,
8144 as otherwise we might destroy if-sequence. */
8147 /* Needed for sequence points to handle trappings, and
8148 side-effects. */
8150 {
8152 arg1);
8154 tem);
8155 }
8156 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8157 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8160 /* Needed for sequence points to handle trappings, and
8161 side-effects. */
8163 {
8168 }
8169 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8170 into (A OR B).
8171 For sequence point consistancy, we need to check for trapping,
8172 and side-effects. */
8176 }
8179 }
8181 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8182 by changing CODE to reduce the magnitude of constants involved in
8183 ARG0 of the comparison.
8184 Returns a canonicalized comparison tree if a simplification was
8185 possible, otherwise returns NULL_TREE.
8186 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8187 valid if signed overflow is undefined. */
8189 static tree
8193 {
8198 /* Match A +- CST code arg1. We can change this only if overflow
8199 is undefined. */
8202 /* In principle pointers also have undefined overflow behavior,
8203 but that causes problems elsewhere. */
8210 /* Identify the constant in arg0 and its sign. */
8214 /* Overflowed constants and zero will cause problems. */
8219 /* See if we can reduce the magnitude of the constant in
8220 arg0 by changing the comparison code. */
8221 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8225 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8229 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8233 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8237 else
8241 /* Now build the constant reduced in magnitude. But not if that
8242 would produce one outside of its types range. */
8258 }
8260 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8261 overflow further. Try to decrease the magnitude of constants involved
8262 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8263 and put sole constants at the second argument position.
8264 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8266 static tree
8269 {
8270 tree t;
8275 /* Try canonicalization by simplifying arg0. */
8280 {
8284 }
8286 /* Try canonicalization by simplifying arg1 using the swapped
8287 comparison. */
8295 }
8297 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8298 space. This is used to avoid issuing overflow warnings for
8299 expressions like &p->x which can not wrap. */
8301 static bool
8303 {
8310 wide_int wi_offset;
8316 else
8332 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8333 array. */
8335 {
8336 HOST_WIDE_INT base_size;
8341 }
8344 }
8346 /* Return a positive integer when the symbol DECL is known to have
8347 a nonzero address, zero when it's known not to (e.g., it's a weak
8348 symbol), and a negative integer when the symbol is not yet in the
8349 symbol table and so whether or not its address is zero is unknown.
8350 For function local objects always return positive integer. */
8351 static int
8353 {
8358 /* Function local objects are never NULL. */
8366 }
8368 /* Subroutine of fold_binary. This routine performs all of the
8369 transformations that are common to the equality/inequality
8370 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8371 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8372 fold_binary should call fold_binary. Fold a comparison with
8373 tree code CODE and type TYPE with operands OP0 and OP1. Return
8374 the folded comparison or NULL_TREE. */
8376 static tree
8379 {
8389 /* For comparisons of pointers we can decompose it to a compile time
8390 comparison of the base objects and the offsets into the object.
8391 This requires at least one operand being an ADDR_EXPR or a
8392 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8398 {
8401 machine_mode mode;
8405 /* Get base and offset for the access. Strip ADDR_EXPR for
8406 get_inner_reference, but put it back by stripping INDIRECT_REF
8407 off the base object if possible. indirect_baseN will be true
8408 if baseN is not an address but refers to the object itself. */
8411 {
8412 base0
8418 else
8420 }
8422 {
8426 {
8427 base0
8433 else
8435 }
8438 else
8442 {
8448 {
8451 }
8452 }
8453 }
8457 {
8458 base1
8464 else
8466 }
8468 {
8472 {
8473 base1
8479 else
8481 }
8484 else
8488 {
8494 {
8497 }
8498 }
8499 }
8501 /* If we have equivalent bases we might be able to simplify. */
8505 {
8506 /* We can fold this expression to a constant if the non-constant
8507 offset parts are equal. */
8511 && (equality_code
8512 || (indirect_base0
8516 {
8522 "occur when comparing P +- C1 with "
8524 WARN_STRICT_OVERFLOW_CONDITIONAL);
8527 {
8541 }
8542 }
8543 /* We can simplify the comparison to a comparison of the variable
8544 offset parts if the constant offset parts are equal.
8545 Be careful to use signed sizetype here because otherwise we
8546 mess with array offsets in the wrong way. This is possible
8547 because pointer arithmetic is restricted to retain within an
8548 object and overflow on pointer differences is undefined as of
8549 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8551 && (equality_code
8552 || (indirect_base0
8555 {
8556 /* By converting to signed sizetype we cover middle-end pointer
8557 arithmetic which operates on unsigned pointer types of size
8558 type size and ARRAY_REF offsets which are properly sign or
8559 zero extended from their type in case it is narrower than
8560 sizetype. */
8563 else
8567 else
8574 "occur when comparing P +- C1 with "
8576 WARN_STRICT_OVERFLOW_COMPARISON);
8579 }
8580 }
8581 /* For equal offsets we can simplify to a comparison of the
8582 base addresses. */
8584 && (indirect_base0
8586 && (indirect_base1
8591 {
8597 }
8598 /* Comparison between an ordinary (non-weak) symbol and a null
8599 pointer can be eliminated since such symbols must have a non
8600 null address. In C, relational expressions between pointers
8601 to objects and null pointers are undefined. The results
8602 below follow the C++ rules with the additional property that
8603 every object pointer compares greater than a null pointer.
8604 */
8607 /* Avoid folding references to struct members at offset 0 to
8608 prevent tests like '&ptr->firstmember == 0' from getting
8609 eliminated. When ptr is null, although the -> expression
8610 is strictly speaking invalid, GCC retains it as a matter
8611 of QoI. See PR c/44555. */
8614 && indirect_base0
8615 /* The caller guarantees that when one of the arguments is
8616 constant (i.e., null in this case) it is second. */
8618 {
8620 {
8631 }
8632 }
8633 }
8635 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8636 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8637 the resulting offset is smaller in absolute value than the
8638 original one and has the same sign. */
8647 {
8652 tree cst;
8654 "occur when combining constants around "
8657 /* Put the constant on the side where it doesn't overflow and is
8658 of lower absolute value and of same sign than before. */
8665 {
8668 variable1,
8672 }
8680 {
8686 variable2);
8687 }
8688 }
8694 /* If we are comparing an expression that just has comparisons
8695 of two integer values, arithmetic expressions of those comparisons,
8696 and constants, we can simplify it. There are only three cases
8697 to check: the two values can either be equal, the first can be
8698 greater, or the second can be greater. Fold the expression for
8699 those three values. Since each value must be 0 or 1, we have
8700 eight possibilities, each of which corresponds to the constant 0
8701 or 1 or one of the six possible comparisons.
8703 This handles common cases like (a > b) == 0 but also handles
8704 expressions like ((x > y) - (y > x)) > 0, which supposedly
8705 occur in macroized code. */
8708 {
8713 /* Don't handle degenerate cases here; they should already
8714 have been handled anyway. */
8723 {
8727 /* We can't just pass T to eval_subst in case cval1 or cval2
8728 was the same as ARG1. */
8730 tree high_result
8734 arg1);
8735 tree equal_result
8739 arg1);
8740 tree low_result
8744 arg1);
8746 /* All three of these results should be 0 or 1. Confirm they are.
8747 Then use those values to select the proper code to use. */
8752 {
8753 /* Make a 3-bit mask with the high-order bit being the
8754 value for `>', the next for '=', and the low for '<'. */
8758 {
8760 /* Always false. */
8781 /* Always true. */
8783 }
8786 {
8790 }
8792 }
8793 }
8794 }
8796 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8797 into a single range test. */
8804 {
8808 }
8811 }
8814 /* Subroutine of fold_binary. Optimize complex multiplications of the
8815 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8816 argument EXPR represents the expression "z" of type TYPE. */
8818 static tree
8820 {
8825 {
8828 }
8830 {
8833 }
8834 else
8835 {
8839 }
8848 }
8851 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8852 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8854 static bool
8856 {
8860 {
8863 }
8865 {
8871 else
8873 }
8874 else
8880 }
8882 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8883 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8884 NULL_TREE otherwise. */
8886 static tree
8888 {
8905 {
8909 }
8912 {
8918 }
8919 else
8921 }
8923 /* Try to fold a pointer difference of type TYPE two address expressions of
8924 array references AREF0 and AREF1 using location LOC. Return a
8925 simplified expression for the difference or NULL_TREE. */
8927 static tree
8930 {
8935 /* If the bases are array references as well, recurse. If the bases
8936 are pointer indirections compute the difference of the pointers.
8937 If the bases are equal, we are set. */
8940 && (base_offset
8944 && (base_offset
8950 {
8956 base_offset,
8959 }
8961 }
8963 /* If the real or vector real constant CST of type TYPE has an exact
8964 inverse, return it, else return NULL. */
8966 tree
8968 {
8969 REAL_VALUE_TYPE r;
8971 machine_mode mode;
8975 {
8991 {
8996 }
9002 }
9003 }
9005 /* Mask out the tz least significant bits of X of type TYPE where
9006 tz is the number of trailing zeroes in Y. */
9007 static wide_int
9009 {
9014 }
9016 /* Return true when T is an address and is known to be nonzero.
9017 For floating point we further ensure that T is not denormal.
9018 Similar logic is present in nonzero_address in rtlanal.h.
9020 If the return value is based on the assumption that signed overflow
9021 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9022 change *STRICT_OVERFLOW_P. */
9024 static bool
9026 {
9030 /* Doing something useful for floating point would need more work. */
9036 {
9039 strict_overflow_p);
9045 strict_overflow_p);
9053 }
9056 {
9059 strict_overflow_p);
9067 strict_overflow_p);
9082 strict_overflow_p);
9086 strict_overflow_p);
9089 {
9101 }
9105 }
9107 }
9109 /* Return true when T is an address and is known to be nonzero.
9110 Handle warnings about undefined signed overflow. */
9112 bool
9114 {
9121 "determining that expression is always "
9123 WARN_STRICT_OVERFLOW_MISC);
9125 }
9127 /* Return true if T is known not to be equal to an integer W. */
9129 bool
9131 {
9133 value_range_type rtype;
9135 {
9144 {
9149 }
9154 /* If T has some known zero bits and W has any of those bits set,
9155 then T is known not to be equal to W. */
9163 }
9164 }
9166 /* Fold a binary expression of code CODE and type TYPE with operands
9167 OP0 and OP1. LOC is the location of the resulting expression.
9168 Return the folded expression if folding is successful. Otherwise,
9169 return NULL_TREE. */
9171 tree
9174 {
9189 /* Strip any conversions that don't change the mode. This is
9190 safe for every expression, except for a comparison expression
9191 because its signedness is derived from its operands. So, in
9192 the latter case, only strip conversions that don't change the
9193 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9194 preserved.
9196 Note that this is done as an internal manipulation within the
9197 constant folder, in order to find the simplest representation
9198 of the arguments so that their form can be studied. In any
9199 cases, the appropriate type conversions should be put back in
9200 the tree that will get out of the constant folder. */
9203 {
9206 }
9207 else
9208 {
9211 }
9213 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9214 constant but we can't do arithmetic on them. */
9216 {
9219 {
9223 }
9224 }
9226 /* If this is a commutative operation, and ARG0 is a constant, move it
9227 to ARG1 to reduce the number of tests below. */
9232 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9233 to ARG1 to reduce the number of tests below. */
9242 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9244 First check for cases where an arithmetic operation is applied to a
9245 compound, conditional, or comparison operation. Push the arithmetic
9246 operation inside the compound or conditional to see if any folding
9247 can then be done. Convert comparison to conditional for this purpose.
9248 The also optimizes non-constant cases that used to be done in
9249 expand_expr.
9251 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9252 one of the operands is a comparison and the other is a comparison, a
9253 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9254 code below would make the expression more complex. Change it to a
9255 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9256 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9269 {
9273 boolean_type_node,
9281 }
9285 {
9287 {
9292 tem);
9293 }
9295 {
9300 tem);
9301 }
9306 {
9312 }
9317 {
9323 }
9324 }
9327 {
9329 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9332 {
9338 }
9340 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9343 {
9344 tree base;
9345 HOST_WIDE_INT coffset;
9354 }
9359 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9365 arg1),
9367 arg0)));
9373 {
9374 /* X + (X / CST) * -CST is X % CST. */
9379 {
9388 cst0));
9389 }
9390 }
9392 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9393 one. Make sure the type is not saturating and has the signedness of
9394 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9395 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9402 {
9406 }
9409 {
9410 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9411 (plus (plus (mult) (mult)) (foo)) so that we can
9412 take advantage of the factoring cases below. */
9421 {
9427 else
9440 parg0),
9442 marg)),
9446 return
9452 parg1)));
9453 }
9454 }
9455 else
9456 {
9457 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9458 to __complex__ ( x, y ). This is not the same for SNaNs or
9459 if signed zeros are involved. */
9463 {
9470 {
9474 {
9480 }
9482 {
9488 }
9489 }
9490 }
9498 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9499 We associate floats only if the user has specified
9500 -fassociative-math. */
9504 {
9509 {
9510 tree tree0;
9513 }
9514 }
9515 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9516 We associate floats only if the user has specified
9517 -fassociative-math. */
9521 {
9526 {
9527 tree tree0;
9530 }
9531 }
9532 }
9534 bit_rotate:
9535 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9536 is a rotate of A by C1 bits. */
9537 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9538 is a rotate of A by B bits. */
9539 {
9541 tree rtype;
9550 /* Only create rotates in complete modes. Other cases are not
9551 expanded properly. */
9554 {
9568 {
9572 code0 == LSHIFT_EXPR
9576 }
9578 {
9586 element_precision
9590 return
9593 ? LROTATE_EXPR
9598 }
9600 {
9608 element_precision
9612 return fold_convert_loc
9615 ? LROTATE_EXPR
9619 }
9620 }
9621 }
9623 associate:
9624 /* In most languages, can't associate operations on floats through
9625 parentheses. Rather than remember where the parentheses were, we
9626 don't associate floats at all, unless the user has specified
9627 -fassociative-math.
9628 And, we need to make sure type is not saturating. */
9632 {
9638 /* Split both trees into variables, constants, and literals. Then
9639 associate each group together, the constants with literals,
9640 then the result with variables. This increases the chances of
9641 literals being recombined later and of generating relocatable
9642 expressions for the sum of a constant and literal. */
9648 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9652 /* With undefined overflow prefer doing association in a type
9653 which wraps on overflow, if that is one of the operand types. */
9656 {
9664 }
9666 /* With undefined overflow we can only associate constants with one
9667 variable, and constants whose association doesn't overflow. */
9670 {
9672 {
9678 {
9681 }
9688 {
9691 }
9697 /* The only case we can still associate with two variables
9698 is if they cancel out. */
9702 }
9703 }
9705 /* Only do something if we found more than two objects. Otherwise,
9706 nothing has changed and we risk infinite recursion. */
9712 {
9719 /* Preserve the MINUS_EXPR if the negative part of the literal is
9720 greater than the positive part. Otherwise, the multiplicative
9721 folding code (i.e extract_muldiv) may be fooled in case
9722 unsigned constants are subtracted, like in the following
9723 example: ((X*2 + 4) - 8U)/2. */
9725 {
9729 {
9733 }
9734 else
9735 {
9739 }
9740 }
9742 /* Don't introduce overflows through reassociation. */
9748 {
9750 return
9754 else
9755 {
9758 return
9762 }
9763 }
9766 return
9769 }
9770 }
9775 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9783 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9784 __complex__ ( x, -y ). This is not the same for SNaNs or if
9785 signed zeros are involved. */
9789 {
9796 {
9800 {
9802 arg1r ? arg1r
9807 }
9809 {
9813 arg1i ? arg1i
9816 }
9817 }
9818 }
9820 /* A - B -> A + (-B) if B is easily negatable. */
9824 /* Avoid this transformation if B is a positive REAL_CST. */
9832 /* Fold &a[i] - &a[j] to i-j. */
9837 {
9843 }
9846 && flag_unsafe_math_optimizations
9852 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9853 one. Make sure the type is not saturating and has the signedness of
9854 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9855 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9862 {
9866 }
9872 {
9873 /* Transform x * -C into -x * C if x is easily negatable. */
9888 {
9891 "occur when simplifying "
9893 WARN_STRICT_OVERFLOW_MISC);
9895 }
9897 /* Optimize z * conj(z) for integer complex numbers. */
9904 }
9905 else
9906 {
9907 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9908 This is not the same for NaNs or if signed zeros are
9909 involved. */
9915 {
9918 return
9924 return
9929 }
9931 /* Optimize z * conj(z) for floating point complex numbers.
9932 Guarded by flag_unsafe_math_optimizations as non-finite
9933 imaginary components don't produce scalar results. */
9942 }
9946 /* Canonicalize (X & C1) | C2. */
9950 {
9955 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9963 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9965 {
9968 }
9970 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9971 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9972 mode which allows further optimizations. */
9977 {
9981 {
9984 }
9985 }
9988 {
9993 }
9994 }
9996 /* See if this can be simplified into a rotate first. If that
9997 is unsuccessful continue in the association code. */
10001 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10009 /* See if this can be simplified into a rotate first. If that
10010 is unsuccessful continue in the association code. */
10014 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10019 {
10020 tree tem2;
10027 }
10028 /* Fold ~X & 1 as (X & 1) == 0. */
10032 {
10033 tree tem2;
10040 }
10041 /* Fold !X & 1 as X == 0. */
10044 {
10048 }
10050 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10051 multiple of 1 << CST. */
10053 {
10060 }
10062 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10063 bits from CST2. */
10067 {
10075 {
10076 /* Avoid the transform if arg1 is a mask of some
10077 mode which allows further optimizations. */
10084 }
10085 }
10087 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10088 ((A & N) + B) & M -> (A + B) & M
10089 Similarly if (N & M) == 0,
10090 ((A | N) + B) & M -> (A + B) & M
10091 and for - instead of + (or unary - instead of +)
10092 and/or ^ instead of |.
10093 If B is constant and (B & M) == 0, fold into A & M. */
10095 {
10104 {
10107 wide_int cst0;
10109 /* Now we know that arg0 is (C + D) or (C - D) or
10110 -C and arg1 (M) is == (1LL << cst) - 1.
10111 Store C into PMOP[0] and D into PMOP[1]. */
10115 {
10118 }
10125 {
10135 {
10138 }
10141 /* If C or D is of the form (A & N) where
10142 (N & M) == M, or of the form (A | N) or
10143 (A ^ N) where (N & M) == 0, replace it with A. */
10147 /* If C or D is a N where (N & M) == 0, it can be
10148 omitted (assumed 0). */
10156 }
10158 /* Only build anything new if we optimized one or both arguments
10159 above. */
10163 {
10166 {
10167 /* Perform the operations in a type that has defined
10168 overflow behavior. */
10174 }
10179 {
10187 else
10189 }
10192 else
10195 /* TEM is now the new binary +, - or unary - replacement. */
10199 }
10200 }
10201 }
10203 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10206 {
10211 return
10213 }
10218 /* Don't touch a floating-point divide by zero unless the mode
10219 of the constant can represent infinity. */
10225 /* (-A) / (-B) -> A / B */
10237 /* Fall through */
10240 /* Simplify A / (B << N) where A and B are positive and B is
10241 a power of 2, to A >> (N + log2(B)). */
10246 {
10249 {
10257 WARN_STRICT_OVERFLOW_MISC);
10263 }
10264 }
10266 /* Fall through */
10274 /* Convert -A / -B to A / B when the type is signed and overflow is
10275 undefined. */
10279 {
10282 "when distributing negation across "
10284 WARN_STRICT_OVERFLOW_MISC);
10289 }
10293 {
10296 "when distributing negation across "
10298 WARN_STRICT_OVERFLOW_MISC);
10303 }
10305 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10306 operation, EXACT_DIV_EXPR.
10308 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10309 At one time others generated faster code, it's not clear if they do
10310 after the last round to changes to the DIV code in expmed.c. */
10321 {
10325 WARN_STRICT_OVERFLOW_MISC);
10327 }
10339 {
10343 WARN_STRICT_OVERFLOW_MISC);
10345 }
10353 /* Since negative shift count is not well-defined,
10354 don't try to compute it in the compiler. */
10360 /* If we have a rotate of a bit operation with the rotate count and
10361 the second operand of the bit operation both constant,
10362 permute the two operations. */
10368 {
10376 }
10378 /* Two consecutive rotates adding up to the some integer
10379 multiple of the precision of the type can be ignored. */
10394 /* Note that the operands of this must be ints
10395 and their values must be 0 or 1.
10396 ("true" is a fixed value perhaps depending on the language.) */
10397 /* If first arg is constant zero, return it. */
10400 /* FALLTHRU */
10402 /* If either arg is constant true, drop it. */
10406 /* Preserve sequence points. */
10409 /* If second arg is constant zero, result is zero, but first arg
10410 must be evaluated. */
10413 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10414 case will be handled here. */
10418 /* !X && X is always false. */
10422 /* X && !X is always false. */
10427 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10428 means A >= Y && A != MAX, but in this case we know that
10429 A < X <= MAX. */
10433 {
10441 }
10450 /* Note that the operands of this must be ints
10451 and their values must be 0 or true.
10452 ("true" is a fixed value perhaps depending on the language.) */
10453 /* If first arg is constant true, return it. */
10456 /* FALLTHRU */
10458 /* If either arg is constant zero, drop it. */
10462 /* Preserve sequence points. */
10465 /* If second arg is constant true, result is true, but we must
10466 evaluate first arg. */
10469 /* Likewise for first arg, but note this only occurs here for
10470 TRUTH_OR_EXPR. */
10474 /* !X || X is always true. */
10478 /* X || !X is always true. */
10483 /* (X && !Y) || (!X && Y) is X ^ Y */
10486 {
10503 }
10512 /* If the second arg is constant zero, drop it. */
10515 /* If the second arg is constant true, this is a logical inversion. */
10517 {
10520 }
10521 /* Identical arguments cancel to zero. */
10525 /* !X ^ X is always true. */
10530 /* X ^ !X is always true. */
10546 /* bool_var != 1 becomes !bool_var. */
10553 /* bool_var == 0 becomes !bool_var. */
10560 /* !exp != 0 becomes !exp */
10565 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10574 {
10580 }
10582 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10591 {
10597 }
10599 /* If this is an EQ or NE comparison with zero and ARG0 is
10600 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10601 two operations, but the latter can be done in one less insn
10602 on machines that have only two-operand insns or on which a
10603 constant cannot be the first operand. */
10606 {
10611 {
10618 arg1);
10619 }
10622 {
10629 arg1);
10630 }
10631 }
10633 /* If this is an NE or EQ comparison of zero against the result of a
10634 signed MOD operation whose second operand is a power of 2, make
10635 the MOD operation unsigned since it is simpler and equivalent. */
10643 {
10653 }
10655 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10656 C1 is a valid shift constant, and C2 is a power of two, i.e.
10657 a single bit. */
10661 == INTEGER_CST
10664 {
10669 /* Check for a valid shift count. */
10671 {
10675 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10676 can be rewritten as (X & (C2 << C1)) != 0. */
10678 {
10683 }
10684 /* Otherwise, for signed (arithmetic) shifts,
10685 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10686 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10690 /* Otherwise, of unsigned (logical) shifts,
10691 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10692 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10693 else
10697 arg000);
10698 }
10699 }
10701 /* If this is a comparison of a field, we may be able to simplify it. */
10704 /* Handle the constant case even without -O
10705 to make sure the warnings are given. */
10707 {
10711 }
10713 /* Optimize comparisons of strlen vs zero to a compare of the
10714 first character of the string vs zero. To wit,
10715 strlen(ptr) == 0 => *ptr == 0
10716 strlen(ptr) != 0 => *ptr != 0
10717 Other cases should reduce to one of these two (or a constant)
10718 due to the return value of strlen being unsigned. */
10721 {
10729 {
10734 }
10735 }
10737 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10738 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10742 {
10747 {
10749 {
10752 }
10755 }
10756 }
10758 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10759 (X & C) == 0 when C is a single bit. */
10764 {
10771 arg1));
10772 }
10774 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10775 constant C is a power of two, i.e. a single bit. */
10782 {
10786 }
10788 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10789 when is C is a power of two, i.e. a single bit. */
10796 {
10802 }
10806 {
10809 }
10811 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10814 {
10822 {
10828 }
10830 {
10836 }
10838 {
10844 }
10846 {
10852 }
10853 }
10857 {
10864 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10865 operand_equal_p guarantees no side-effects so we don't need
10866 to use omit_one_operand on Z. */
10870 arg10));
10874 arg11));
10878 arg10));
10882 arg11));
10884 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10887 {
10893 }
10894 }
10896 /* Attempt to simplify equality/inequality comparisons of complex
10897 values. Only lower the comparison if the result is known or
10898 can be simplified to a single scalar comparison. */
10903 {
10908 {
10911 }
10912 else
10913 {
10916 }
10919 {
10922 }
10923 else
10924 {
10927 }
10931 {
10933 {
10938 }
10939 else
10940 {
10945 }
10946 }
10950 {
10952 {
10957 }
10958 else
10959 {
10964 }
10965 }
10966 }
10978 /* Transform comparisons of the form X +- C CMP X. */
10985 {
10992 else
10995 /* (X - c) > X becomes false. */
10999 {
11003 "occur when assuming that (X - c) > X "
11005 WARN_STRICT_OVERFLOW_ALL);
11007 }
11009 /* Likewise (X + c) < X becomes false. */
11013 {
11017 "occur when assuming that "
11019 WARN_STRICT_OVERFLOW_ALL);
11021 }
11023 /* Convert (X - c) <= X to true. */
11028 {
11032 "occur when assuming that "
11034 WARN_STRICT_OVERFLOW_ALL);
11036 }
11038 /* Convert (X + c) >= X to true. */
11043 {
11047 "occur when assuming that "
11049 WARN_STRICT_OVERFLOW_ALL);
11051 }
11054 {
11055 /* Convert X + c > X and X - c < X to true for integers. */
11059 {
11062 "not occur when assuming that "
11064 WARN_STRICT_OVERFLOW_ALL);
11066 }
11071 {
11074 "not occur when assuming that "
11076 WARN_STRICT_OVERFLOW_ALL);
11078 }
11080 /* Convert X + c <= X and X - c >= X to false for integers. */
11084 {
11087 "not occur when assuming that "
11089 WARN_STRICT_OVERFLOW_ALL);
11091 }
11096 {
11099 "not occur when assuming that "
11101 WARN_STRICT_OVERFLOW_ALL);
11103 }
11104 }
11105 }
11107 /* If we are comparing an ABS_EXPR with a constant, we can
11108 convert all the cases into explicit comparisons, but they may
11109 well not be faster than doing the ABS and one comparison.
11110 But ABS (X) <= C is a range comparison, which becomes a subtraction
11111 and a comparison, and is probably faster. */
11125 /* Convert ABS_EXPR<x> >= 0 to true. */
11132 {
11135 "when simplifying comparison of "
11137 WARN_STRICT_OVERFLOW_CONDITIONAL);
11140 arg0);
11141 }
11143 /* Convert ABS_EXPR<x> < 0 to false. */
11148 {
11151 "when simplifying comparison of "
11153 WARN_STRICT_OVERFLOW_CONDITIONAL);
11156 arg0);
11157 }
11159 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11160 and similarly for >= into !=. */
11170 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11171 otherwise Y might be >= # of bits in X's type and thus e.g.
11172 (unsigned char) (1 << Y) for Y 15 might be 0.
11173 If the cast is widening, then 1 << Y should have unsigned type,
11174 otherwise if Y is number of bits in the signed shift type minus 1,
11175 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11176 31 might be 0xffffffff80000000. */
11187 {
11193 }
11205 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11206 {
11218 }
11223 /* When pedantic, a compound expression can be neither an lvalue
11224 nor an integer constant expression. */
11227 /* Don't let (0, 0) be null pointer constant. */
11233 /* An ASSERT_EXPR should never be passed to fold_binary. */
11239 }
11241 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11242 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11243 of GOTO_EXPR. */
11245 static tree
11247 {
11249 {
11256 /* fall through */
11260 }
11261 }
11263 /* Return whether the sub-tree ST contains a label which is accessible from
11264 outside the sub-tree. */
11266 static bool
11268 {
11269 return
11271 }
11273 /* Fold a ternary expression of code CODE and type TYPE with operands
11274 OP0, OP1, and OP2. Return the folded expression if folding is
11275 successful. Otherwise, return NULL_TREE. */
11277 tree
11280 {
11281 tree tem;
11288 /* If this is a commutative operation, and OP0 is a constant, move it
11289 to OP1 to reduce the number of tests below. */
11298 /* Strip any conversions that don't change the mode. This is safe
11299 for every expression, except for a comparison expression because
11300 its signedness is derived from its operands. So, in the latter
11301 case, only strip conversions that don't change the signedness.
11303 Note that this is done as an internal manipulation within the
11304 constant folder, in order to find the simplest representation of
11305 the arguments so that their form can be studied. In any cases,
11306 the appropriate type conversions should be put back in the tree
11307 that will get out of the constant folder. */
11309 {
11312 }
11315 {
11318 }
11321 {
11324 }
11327 {
11331 {
11337 }
11342 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11343 so all simple results must be passed through pedantic_non_lvalue. */
11345 {
11348 /* Only optimize constant conditions when the selected branch
11349 has the same type as the COND_EXPR. This avoids optimizing
11350 away "c ? x : throw", where the throw has a void type.
11351 Avoid throwing away that operand which contains label. */
11358 }
11360 {
11365 {
11370 {
11378 }
11382 }
11383 }
11385 /* If we have A op B ? A : C, we may be able to convert this to a
11386 simpler expression, depending on the operation and the values
11387 of B and C. Signed zeros prevent all of these transformations,
11388 for reasons given above each one.
11390 Also try swapping the arguments and inverting the conditional. */
11395 {
11399 }
11403 op2,
11406 {
11410 {
11414 }
11415 }
11417 /* If the second operand is simpler than the third, swap them
11418 since that produces better jump optimization results. */
11421 {
11423 /* See if this can be inverted. If it can't, possibly because
11424 it was a floating-point inequality comparison, don't do
11425 anything. */
11429 }
11431 /* Convert A ? 1 : 0 to simply A. */
11436 /* If we try to convert OP0 to our type, the
11437 call to fold will try to move the conversion inside
11438 a COND, which will recurse. In that case, the COND_EXPR
11439 is probably the best choice, so leave it alone. */
11443 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11444 over COND_EXPR in cases such as floating point comparisons. */
11453 arg0)));
11455 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11460 {
11461 /* sign_bit_p looks through both zero and sign extensions,
11462 but for this optimization only sign extensions are
11463 usable. */
11466 {
11469 {
11472 }
11474 }
11475 /* sign_bit_p only checks ARG1 bits within A's precision.
11476 If <sign bit of A> has wider type than A, bits outside
11477 of A's precision in <sign bit of A> need to be checked.
11478 If they are all 0, this optimization needs to be done
11479 in unsigned A's type, if they are all 1 in signed A's type,
11480 otherwise this can't be done. */
11486 {
11488 tree tem_type;
11501 {
11504 }
11506 {
11509 }
11510 else
11512 }
11515 return
11521 arg1)));
11522 }
11524 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11525 already handled above. */
11530 {
11540 op1);
11541 }
11543 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11544 is probably obsolete because the first operand should be a
11545 truth value (that's why we have the two cases above), but let's
11546 leave it in until we can confirm this for all front-ends. */
11558 /* Disable the transformations below for vectors, since
11559 fold_binary_op_with_conditional_arg may undo them immediately,
11560 yielding an infinite loop. */
11564 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11573 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11578 {
11580 /* Only perform transformation if ARG0 is easily inverted. */
11584 ? BIT_IOR_EXPR
11587 op1);
11588 }
11590 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11595 {
11597 /* Only perform transformation if ARG0 is easily inverted. */
11603 op2);
11604 }
11606 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11618 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11619 of fold_ternary on them. */
11627 {
11637 {
11642 {
11650 }
11651 }
11652 }
11654 /* On constants we can use native encode/interpret to constant
11655 fold (nearly) all BIT_FIELD_REFs. */
11659 {
11662 /* Limit us to a reasonable amount of work. To relax the
11663 other limitations we need bit-shifting of the buffer
11664 and rounding up the size. */
11668 {
11670 unsigned HOST_WIDE_INT len
11675 {
11680 }
11681 }
11682 }
11687 /* For integers we can decompose the FMA if possible. */
11699 {
11715 {
11720 /* Make sure that the perm value is in an acceptable
11721 range. */
11730 else
11735 }
11738 {
11743 }
11748 {
11753 }
11759 {
11763 }
11768 /* Some targets are deficient and fail to expand a single
11769 argument permutation while still allowing an equivalent
11770 2-argument version. */
11774 {
11777 }
11780 {
11787 }
11791 }
11795 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11798 {
11804 wide_int tem2
11808 }
11813 {
11815 unsigned HOST_WIDE_INT elsize
11818 {
11822 else
11823 {
11829 }
11830 }
11831 }
11837 }
11839 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11840 of an array (or vector). */
11842 tree
11844 {
11849 {
11852 {
11853 /* Static constructors for variably sized objects makes no sense. */
11857 }
11858 }
11869 offset_int max_index;
11874 {
11875 /* Array constructor might explicitly set index, or specify a range,
11876 or leave index NULL meaning that it is next index after previous
11877 one. */
11879 {
11882 else
11883 {
11887 }
11888 }
11889 else
11890 {
11896 }
11898 /* Do we have match? */
11902 }
11904 }
11906 /* Perform constant folding and related simplification of EXPR.
11907 The related simplifications include x*1 => x, x*0 => 0, etc.,
11908 and application of the associative law.
11909 NOP_EXPR conversions may be removed freely (as long as we
11910 are careful not to change the type of the overall expression).
11911 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11912 but we can constant-fold them if they have constant operands. */
11914 #ifdef ENABLE_FOLD_CHECKING
11915 # define fold(x) fold_1 (x)
11917 static
11918 #endif
11919 tree
11921 {
11925 tree tem;
11928 /* Return right away if a constant. */
11932 /* CALL_EXPR-like objects with variable numbers of operands are
11933 treated specially. */
11935 {
11937 {
11940 }
11942 }
11945 {
11950 {
11968 }
11969 }
11972 {
11974 {
11981 {
11986 }
11989 }
11991 /* Return a VECTOR_CST if possible. */
11993 {
11999 tree val;
12005 }
12013 }
12015 #ifdef ENABLE_FOLD_CHECKING
12016 #undef fold
12023 /* When --enable-checking=fold, compute a digest of expr before
12024 and after actual fold call to see if fold did not accidentally
12025 change original expr. */
12027 tree
12029 {
12030 tree ret;
12050 }
12052 void
12054 {
12065 }
12067 static void
12069 {
12071 }
12073 static void
12076 {
12082 recursive_label:
12092 {
12093 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12098 }
12106 {
12107 /* Allow these fields to be modified. */
12108 tree tmp;
12117 {
12120 }
12121 }
12132 {
12135 {
12150 }
12154 {
12167 }
12184 {
12190 }
12193 {
12195 {
12198 }
12200 }
12211 {
12214 }
12224 }
12225 }
12227 /* Helper function for outputting the checksum of a tree T. When
12228 debugging with gdb, you can "define mynext" to be "next" followed
12229 by "call debug_fold_checksum (op0)", then just trace down till the
12230 outputs differ. */
12232 DEBUG_FUNCTION void
12234 {
12249 }
12251 #endif
12253 /* Fold a unary tree expression with code CODE of type TYPE with an
12254 operand OP0. LOC is the location of the resulting expression.
12255 Return a folded expression if successful. Otherwise, return a tree
12256 expression with code CODE of type TYPE with an operand OP0. */
12258 tree
12261 {
12262 tree tem;
12263 #ifdef ENABLE_FOLD_CHECKING
12272 #endif
12278 #ifdef ENABLE_FOLD_CHECKING
12285 #endif
12287 }
12289 /* Fold a binary tree expression with code CODE of type TYPE with
12290 operands OP0 and OP1. LOC is the location of the resulting
12291 expression. Return a folded expression if successful. Otherwise,
12292 return a tree expression with code CODE of type TYPE with operands
12293 OP0 and OP1. */
12295 tree
12298 MEM_STAT_DECL)
12299 {
12300 tree tem;
12301 #ifdef ENABLE_FOLD_CHECKING
12318 #endif
12324 #ifdef ENABLE_FOLD_CHECKING
12339 #endif
12341 }
12343 /* Fold a ternary tree expression with code CODE of type TYPE with
12344 operands OP0, OP1, and OP2. Return a folded expression if
12345 successful. Otherwise, return a tree expression with code CODE of
12346 type TYPE with operands OP0, OP1, and OP2. */
12348 tree
12351 {
12352 tree tem;
12353 #ifdef ENABLE_FOLD_CHECKING
12377 #endif
12384 #ifdef ENABLE_FOLD_CHECKING
12407 #endif
12409 }
12411 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12412 arguments in ARGARRAY, and a null static chain.
12413 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12414 of type TYPE from the given operands as constructed by build_call_array. */
12416 tree
12419 {
12420 tree tem;
12421 #ifdef ENABLE_FOLD_CHECKING
12440 #endif
12446 #ifdef ENABLE_FOLD_CHECKING
12462 #endif
12464 }
12466 /* Perform constant folding and related simplification of initializer
12467 expression EXPR. These behave identically to "fold_buildN" but ignore
12468 potential run-time traps and exceptions that fold must preserve. */
12470 #define START_FOLD_INIT \
12471 int saved_signaling_nans = flag_signaling_nans;\
12472 int saved_trapping_math = flag_trapping_math;\
12473 int saved_rounding_math = flag_rounding_math;\
12474 int saved_trapv = flag_trapv;\
12475 int saved_folding_initializer = folding_initializer;\
12476 flag_signaling_nans = 0;\
12477 flag_trapping_math = 0;\
12478 flag_rounding_math = 0;\
12479 flag_trapv = 0;\
12480 folding_initializer = 1;
12482 #define END_FOLD_INIT \
12483 flag_signaling_nans = saved_signaling_nans;\
12484 flag_trapping_math = saved_trapping_math;\
12485 flag_rounding_math = saved_rounding_math;\
12486 flag_trapv = saved_trapv;\
12487 folding_initializer = saved_folding_initializer;
12489 tree
12492 {
12493 tree result;
12494 START_FOLD_INIT;
12498 END_FOLD_INIT;
12500 }
12502 tree
12505 {
12506 tree result;
12507 START_FOLD_INIT;
12511 END_FOLD_INIT;
12513 }
12515 tree
12518 {
12519 tree result;
12520 START_FOLD_INIT;
12524 END_FOLD_INIT;
12526 }
12528 #undef START_FOLD_INIT
12529 #undef END_FOLD_INIT
12531 /* Determine if first argument is a multiple of second argument. Return 0 if
12532 it is not, or we cannot easily determined it to be.
12534 An example of the sort of thing we care about (at this point; this routine
12535 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12536 fold cases do now) is discovering that
12538 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12540 is a multiple of
12542 SAVE_EXPR (J * 8)
12544 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12546 This code also handles discovering that
12548 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12550 is a multiple of 8 so we don't have to worry about dealing with a
12551 possible remainder.
12553 Note that we *look* inside a SAVE_EXPR only to determine how it was
12554 calculated; it is not safe for fold to do much of anything else with the
12555 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12556 at run time. For example, the latter example above *cannot* be implemented
12557 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12558 evaluation time of the original SAVE_EXPR is not necessarily the same at
12559 the time the new expression is evaluated. The only optimization of this
12560 sort that would be valid is changing
12562 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12564 divided by 8 to
12566 SAVE_EXPR (I) * SAVE_EXPR (J)
12568 (where the same SAVE_EXPR (J) is used in the original and the
12569 transformed version). */
12571 int
12573 {
12584 {
12586 /* Bitwise and provides a power of two multiple. If the mask is
12587 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12590 /* FALLTHRU */
12597 /* It is impossible to prove if op0 - op1 is multiple of bottom
12598 precisely, so be conservative here checking if both op0 and op1
12599 are multiple of bottom. Note we check the second operand first
12600 since it's usually simpler. */
12605 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12606 as op0 - 3 if the expression has unsigned type. For example,
12607 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12617 {
12619 /* const_binop may not detect overflow correctly,
12620 so check for it explicitly here. */
12624 size_one_node,
12625 op1)))
12628 }
12632 /* Can't handle conversions from non-integral or wider integral type. */
12638 /* fall through */
12655 SIGNED);
12661 {
12664 /* Check for special cases to see if top is defined as multiple
12665 of bottom:
12667 top = (X & ~(bottom - 1) ; bottom is power of 2
12669 or
12671 Y = X % bottom
12672 top = X - Y. */
12691 }
12693 /* fall through */
12697 }
12698 }
12700 #define tree_expr_nonnegative_warnv_p(X, Y) \
12703 #define RECURSE(X) \
12704 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12706 /* Return true if CODE or TYPE is known to be non-negative. */
12708 static bool
12710 {
12713 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12714 have a signed:1 type (where the value is -1 and 0). */
12717 }
12719 /* Return true if (CODE OP0) is known to be non-negative. If the return
12720 value is based on the assumption that signed overflow is undefined,
12721 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12722 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12724 bool
12727 {
12732 {
12734 /* We can't return 1 if flag_wrapv is set because
12735 ABS_EXPR<INT_MIN> = INT_MIN. */
12739 {
12742 }
12750 CASE_CONVERT:
12751 {
12756 {
12760 {
12764 }
12765 }
12767 {
12773 }
12774 }
12779 }
12781 /* We don't know sign of `t', so be conservative and return false. */
12783 }
12785 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12786 value is based on the assumption that signed overflow is undefined,
12787 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12788 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12790 bool
12794 {
12799 {
12805 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12806 both unsigned and at least 2 bits shorter than the result. */
12810 {
12815 {
12819 }
12820 }
12825 {
12826 /* x * x is always non-negative for floating point x
12827 or without overflow. */
12830 {
12835 }
12836 }
12838 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12839 both unsigned and their total bits is shorter than the result. */
12843 {
12862 {
12872 }
12873 }
12900 }
12902 /* We don't know sign of `t', so be conservative and return false. */
12904 }
12906 /* Return true if T is known to be non-negative. If the return
12907 value is based on the assumption that signed overflow is undefined,
12908 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12909 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12911 bool
12913 {
12918 {
12932 /* Limit the depth of recursion to avoid quadratic behavior.
12933 This is expected to catch almost all occurrences in practice.
12934 If this code misses important cases that unbounded recursion
12935 would not, passes that need this information could be revised
12936 to provide it through dataflow propagation. */
12944 }
12945 }
12947 /* Return true if T is known to be non-negative. If the return
12948 value is based on the assumption that signed overflow is undefined,
12949 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12950 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12952 bool
12955 {
12957 {
12958 CASE_CFN_ACOS:
12959 CASE_CFN_ACOSH:
12960 CASE_CFN_CABS:
12961 CASE_CFN_COSH:
12962 CASE_CFN_ERFC:
12963 CASE_CFN_EXP:
12964 CASE_CFN_EXP10:
12965 CASE_CFN_EXP2:
12966 CASE_CFN_FABS:
12967 CASE_CFN_FDIM:
12968 CASE_CFN_HYPOT:
12969 CASE_CFN_POW10:
12970 CASE_CFN_FFS:
12971 CASE_CFN_PARITY:
12972 CASE_CFN_POPCOUNT:
12973 CASE_CFN_CLZ:
12974 CASE_CFN_CLRSB:
12977 /* Always true. */
12980 CASE_CFN_SQRT:
12981 /* sqrt(-0.0) is -0.0. */
12986 CASE_CFN_ASINH:
12987 CASE_CFN_ATAN:
12988 CASE_CFN_ATANH:
12989 CASE_CFN_CBRT:
12990 CASE_CFN_CEIL:
12991 CASE_CFN_ERF:
12992 CASE_CFN_EXPM1:
12993 CASE_CFN_FLOOR:
12994 CASE_CFN_FMOD:
12995 CASE_CFN_FREXP:
12996 CASE_CFN_ICEIL:
12997 CASE_CFN_IFLOOR:
12998 CASE_CFN_IRINT:
12999 CASE_CFN_IROUND:
13000 CASE_CFN_LCEIL:
13001 CASE_CFN_LDEXP:
13002 CASE_CFN_LFLOOR:
13003 CASE_CFN_LLCEIL:
13004 CASE_CFN_LLFLOOR:
13005 CASE_CFN_LLRINT:
13006 CASE_CFN_LLROUND:
13007 CASE_CFN_LRINT:
13008 CASE_CFN_LROUND:
13009 CASE_CFN_MODF:
13010 CASE_CFN_NEARBYINT:
13011 CASE_CFN_RINT:
13012 CASE_CFN_ROUND:
13013 CASE_CFN_SCALB:
13014 CASE_CFN_SCALBLN:
13015 CASE_CFN_SCALBN:
13016 CASE_CFN_SIGNBIT:
13017 CASE_CFN_SIGNIFICAND:
13018 CASE_CFN_SINH:
13019 CASE_CFN_TANH:
13020 CASE_CFN_TRUNC:
13021 /* True if the 1st argument is nonnegative. */
13024 CASE_CFN_FMAX:
13025 /* True if the 1st OR 2nd arguments are nonnegative. */
13028 CASE_CFN_FMIN:
13029 /* True if the 1st AND 2nd arguments are nonnegative. */
13032 CASE_CFN_COPYSIGN:
13033 /* True if the 2nd argument is nonnegative. */
13036 CASE_CFN_POWI:
13037 /* True if the 1st argument is nonnegative or the second
13038 argument is an even integer. */
13044 CASE_CFN_POW:
13045 /* True if the 1st argument is nonnegative or the second
13046 argument is an even integer valued real. */
13048 {
13049 REAL_VALUE_TYPE c;
13050 HOST_WIDE_INT n;
13055 {
13056 REAL_VALUE_TYPE cint;
13060 }
13061 }
13066 }
13068 }
13070 /* Return true if T is known to be non-negative. If the return
13071 value is based on the assumption that signed overflow is undefined,
13072 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13073 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13075 static bool
13077 {
13083 {
13085 {
13089 /* If the initializer is non-void, then it's a normal expression
13090 that will be assigned to the slot. */
13094 /* Otherwise, the initializer sets the slot in some way. One common
13095 way is an assignment statement at the end of the initializer. */
13097 {
13105 else
13107 }
13113 }
13116 {
13122 arg0,
13123 arg1,
13125 }
13138 }
13139 }
13141 #undef RECURSE
13142 #undef tree_expr_nonnegative_warnv_p
13144 /* Return true if T is known to be non-negative. If the return
13145 value is based on the assumption that signed overflow is undefined,
13146 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13147 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13149 bool
13151 {
13158 {
13180 }
13183 {
13209 }
13210 }
13212 /* Return true if `t' is known to be non-negative. Handle warnings
13213 about undefined signed overflow. */
13215 bool
13217 {
13224 "determining that expression is always "
13226 WARN_STRICT_OVERFLOW_MISC);
13228 }
13231 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13232 For floating point we further ensure that T is not denormal.
13233 Similar logic is present in nonzero_address in rtlanal.h.
13235 If the return value is based on the assumption that signed overflow
13236 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13237 change *STRICT_OVERFLOW_P. */
13239 bool
13242 {
13244 {
13247 strict_overflow_p);
13250 {
13256 strict_overflow_p));
13257 }
13262 strict_overflow_p);
13266 }
13269 }
13271 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13272 For floating point we further ensure that T is not denormal.
13273 Similar logic is present in nonzero_address in rtlanal.h.
13275 If the return value is based on the assumption that signed overflow
13276 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13277 change *STRICT_OVERFLOW_P. */
13279 bool
13281 tree type,
13282 tree op0,
13284 {
13287 {
13291 {
13292 /* With the presence of negative values it is hard
13293 to say something. */
13300 /* One of operands must be positive and the other non-negative. */
13301 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13302 overflows, on a twos-complement machine the sum of two
13303 nonnegative numbers can never be zero. */
13305 strict_overflow_p)
13307 strict_overflow_p));
13308 }
13313 {
13315 strict_overflow_p)
13317 strict_overflow_p))
13318 {
13321 }
13322 }
13331 {
13334 }
13341 {
13345 /* When both operands are nonzero, then MAX must be too. */
13347 strict_overflow_p))
13350 /* MAX where operand 0 is positive is positive. */
13352 strict_overflow_p);
13353 }
13354 /* MAX where operand 1 is positive is positive. */
13359 {
13363 }
13368 strict_overflow_p)
13370 strict_overflow_p));
13374 }
13377 }
13379 /* Return true when T is an address and is known to be nonzero.
13380 For floating point we further ensure that T is not denormal.
13381 Similar logic is present in nonzero_address in rtlanal.h.
13383 If the return value is based on the assumption that signed overflow
13384 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13385 change *STRICT_OVERFLOW_P. */
13387 bool
13389 {
13392 {
13397 {
13409 /* For objects in symbol table check if we know they are non-zero.
13410 Don't do anything for variables and functions before symtab is built;
13411 it is quite possible that they will be declared weak later. */
13416 /* Constants are never weak. */
13421 }
13429 {
13433 }
13443 }
13445 }
13447 #define integer_valued_real_p(X) \
13450 #define RECURSE(X) \
13451 ((integer_valued_real_p) (X, depth + 1))
13453 /* Return true if the floating point result of (CODE OP0) has an
13454 integer value. We also allow +Inf, -Inf and NaN to be considered
13455 integer values. Return false for signaling NaN.
13457 DEPTH is the current nesting depth of the query. */
13459 bool
13461 {
13463 {
13470 CASE_CONVERT:
13471 {
13478 }
13482 }
13484 }
13486 /* Return true if the floating point result of (CODE OP0 OP1) has an
13487 integer value. We also allow +Inf, -Inf and NaN to be considered
13488 integer values. Return false for signaling NaN.
13490 DEPTH is the current nesting depth of the query. */
13492 bool
13494 {
13496 {
13506 }
13508 }
13510 /* Return true if the floating point result of calling FNDECL with arguments
13511 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13512 considered integer values. Return false for signaling NaN. If FNDECL
13513 takes fewer than 2 arguments, the remaining ARGn are null.
13515 DEPTH is the current nesting depth of the query. */
13517 bool
13519 {
13521 {
13522 CASE_CFN_CEIL:
13523 CASE_CFN_FLOOR:
13524 CASE_CFN_NEARBYINT:
13525 CASE_CFN_RINT:
13526 CASE_CFN_ROUND:
13527 CASE_CFN_TRUNC:
13530 CASE_CFN_FMIN:
13531 CASE_CFN_FMAX:
13536 }
13538 }
13540 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13541 has an integer value. We also allow +Inf, -Inf and NaN to be
13542 considered integer values. Return false for signaling NaN.
13544 DEPTH is the current nesting depth of the query. */
13546 bool
13548 {
13550 {
13558 /* Limit the depth of recursion to avoid quadratic behavior.
13559 This is expected to catch almost all occurrences in practice.
13560 If this code misses important cases that unbounded recursion
13561 would not, passes that need this information could be revised
13562 to provide it through dataflow propagation. */
13566 depth));
13570 }
13572 }
13574 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13575 has an integer value. We also allow +Inf, -Inf and NaN to be
13576 considered integer values. Return false for signaling NaN.
13578 DEPTH is the current nesting depth of the query. */
13580 static bool
13582 {
13584 {
13595 }
13597 }
13599 #undef RECURSE
13600 #undef integer_valued_real_p
13602 /* Return true if the floating point expression T has an integer value.
13603 We also allow +Inf, -Inf and NaN to be considered integer values.
13604 Return false for signaling NaN.
13606 DEPTH is the current nesting depth of the query. */
13608 bool
13610 {
13616 {
13632 }
13635 {
13641 {
13650 }
13654 }
13655 }
13657 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13658 attempt to fold the expression to a constant without modifying TYPE,
13659 OP0 or OP1.
13661 If the expression could be simplified to a constant, then return
13662 the constant. If the expression would not be simplified to a
13663 constant, then return NULL_TREE. */
13665 tree
13667 {
13670 }
13672 /* Given the components of a unary expression CODE, TYPE and OP0,
13673 attempt to fold the expression to a constant without modifying
13674 TYPE or OP0.
13676 If the expression could be simplified to a constant, then return
13677 the constant. If the expression would not be simplified to a
13678 constant, then return NULL_TREE. */
13680 tree
13682 {
13685 }
13687 /* If EXP represents referencing an element in a constant string
13688 (either via pointer arithmetic or array indexing), return the
13689 tree representing the value accessed, otherwise return NULL. */
13691 tree
13693 {
13697 {
13699 tree index;
13700 tree string;
13705 else
13706 {
13710 /* Optimize the special-case of a zero lower bound.
13712 We convert the low_bound to sizetype to avoid some problems
13713 with constant folding. (E.g. suppose the lower bound is 1,
13714 and its mode is QI. Without the conversion,l (ARRAY
13715 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13716 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13722 }
13735 }
13737 }
13739 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13740 an integer constant, real, or fixed-point constant.
13742 TYPE is the type of the result. */
13744 static tree
13746 {
13750 {
13752 {
13759 }
13766 {
13767 FIXED_VALUE_TYPE f;
13772 /* Propagate overflow flags. */
13776 }
13780 }
13783 }
13785 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13786 an integer constant or real constant.
13788 TYPE is the type of the result. */
13790 tree
13792 {
13796 {
13798 {
13799 /* If the value is unsigned or non-negative, then the absolute value
13800 is the same as the ordinary value. */
13804 /* If the value is negative, then the absolute value is
13805 its negation. */
13806 else
13807 {
13812 }
13813 }
13819 else
13825 }
13828 }
13830 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13831 constant. TYPE is the type of the result. */
13833 static tree
13835 {
13839 }
13841 /* Given CODE, a relational operator, the target type, TYPE and two
13842 constant operands OP0 and OP1, return the result of the
13843 relational operation. If the result is not a compile time
13844 constant, then return NULL_TREE. */
13846 static tree
13848 {
13851 /* From here on, the only cases we handle are when the result is
13852 known to be a constant. */
13855 {
13859 /* Handle the cases where either operand is a NaN. */
13861 {
13863 {
13891 }
13894 }
13897 }
13900 {
13904 }
13906 /* Handle equality/inequality of complex constants. */
13908 {
13919 else
13921 }
13924 {
13926 {
13927 /* Have vector comparison with scalar boolean result. */
13931 {
13939 }
13941 }
13948 {
13960 }
13963 }
13965 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13967 To compute GT, swap the arguments and do LT.
13968 To compute GE, do LT and invert the result.
13969 To compute LE, swap the arguments, do LT and invert the result.
13970 To compute NE, do EQ and invert the result.
13972 Therefore, the code below must handle only EQ and LT. */
13975 {
13978 }
13980 /* Note that it is safe to invert for real values here because we
13981 have already handled the one case that it matters. */
13985 {
13988 }
13990 /* Compute a result for LT or EQ if args permit;
13991 Otherwise return T. */
13993 {
13996 else
13998 }
13999 else
14005 }
14007 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14008 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14009 itself. */
14011 tree
14013 {
14014 /* If the expression does not have side effects then we don't have to wrap
14015 it with a cleanup point expression. */
14019 /* If the expression is a return, check to see if the expression inside the
14020 return has no side effects or the right hand side of the modify expression
14021 inside the return. If either don't have side effects set we don't need to
14022 wrap the expression in a cleanup point expression. Note we don't check the
14023 left hand side of the modify because it should always be a return decl. */
14025 {
14032 }
14035 }
14037 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14038 of an indirection through OP0, or NULL_TREE if no simplification is
14039 possible. */
14041 tree
14043 {
14045 tree subtype;
14054 {
14057 /* *&CONST_DECL -> to the value of the const decl. */
14060 /* *&p => p; make sure to handle *&"str"[cst] here. */
14062 {
14066 else
14068 }
14069 /* *(foo *)&fooarray => fooarray[0] */
14072 && (!in_gimple_form
14074 {
14084 }
14085 /* *(foo *)&complexfoo => __real__ complexfoo */
14089 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14092 {
14096 }
14097 }
14101 {
14107 {
14108 tree op00type;
14112 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14115 {
14117 unsigned HOST_WIDE_INT max_offset
14122 {
14129 }
14130 }
14131 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14134 {
14138 }
14139 /* ((foo *)&fooarray)[1] => fooarray[1] */
14142 {
14152 }
14153 }
14154 }
14156 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14159 && (!in_gimple_form
14161 {
14162 tree type_domain;
14172 NULL_TREE);
14173 }
14176 }
14178 /* Builds an expression for an indirection through T, simplifying some
14179 cases. */
14181 tree
14183 {
14191 }
14193 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14195 tree
14197 {
14202 else
14204 }
14206 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14207 whose result is ignored. The type of the returned tree need not be
14208 the same as the original expression. */
14210 tree
14212 {
14218 {
14229 else
14235 {
14251 }
14256 }
14257 }
14259 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14261 tree
14263 {
14269 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14270 have to do anything. Only do this when we are not given a const,
14271 because in that case, this check is more expensive than just
14272 doing it. */
14274 {
14279 }
14281 /* If divisor is a power of two, simplify this to bit manipulation. */
14283 {
14285 {
14299 }
14300 else
14301 {
14302 tree t;
14308 }
14309 }
14310 else
14311 {
14316 }
14319 }
14321 /* Likewise, but round down. */
14323 tree
14325 {
14332 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14333 have to do anything. Only do this when we are not given a const,
14334 because in that case, this check is more expensive than just
14335 doing it. */
14337 {
14342 }
14344 /* If divisor is a power of two, simplify this to bit manipulation. */
14346 {
14347 tree t;
14351 }
14352 else
14353 {
14358 }
14361 }
14363 /* Returns the pointer to the base of the object addressed by EXP and
14364 extracts the information about the offset of the access, storing it
14365 to PBITPOS and POFFSET. */
14367 static tree
14370 {
14371 tree core;
14372 machine_mode mode;
14374 HOST_WIDE_INT bitsize;
14378 {
14383 }
14385 {
14391 {
14396 {
14399 }
14400 }
14401 }
14402 else
14403 {
14407 }
14410 }
14412 /* Returns true if addresses of E1 and E2 differ by a constant, false
14413 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14415 bool
14417 {
14431 {
14441 }
14443 {
14444 /* If only one of the offsets is non-constant, the difference cannot
14445 be a constant. */
14447 }
14448 else
14453 }
14455 /* Return OFF converted to a pointer offset type suitable as offset for
14456 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14457 tree
14459 {
14461 }
14463 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14464 tree
14466 {
14469 }
14471 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14472 tree
14474 {
14477 }
14479 /* Return a char pointer for a C string if it is a string constant
14480 or sum of string constant and integer constant. We only support
14481 string constants properly terminated with '\0' character.
14482 If STRLEN is a valid pointer, length (including terminating character)
14483 of returned string is stored to the argument. */
14487 {
14488 tree offset_node;
14499 {
14502 else
14504 }
14509 /* Support only properly null-terminated strings. */
14518 }
14520 #if CHECKING_P
14524 /* Helper functions for writing tests of folding trees. */
14526 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14528 static void
14530 tree constant)
14531 {
14533 }
14535 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14536 wrapping WRAPPED_EXPR. */
14538 static void
14540 tree wrapped_expr)
14541 {
14546 }
14548 /* Verify that various arithmetic binary operations are folded
14549 correctly. */
14551 static void
14553 {
14559 /* Addition. */
14560 /* 1 <-- (0 + 1) */
14562 one);
14564 one);
14566 /* (nonlvalue)x <-- (x + 0) */
14568 x);
14570 /* Subtraction. */
14571 /* 0 <-- (x - x) */
14573 zero);
14575 x);
14577 /* Multiplication. */
14578 /* 0 <-- (x * 0) */
14580 zero);
14582 /* (nonlvalue)x <-- (x * 1) */
14584 x);
14585 }
14587 /* Verify that various binary operations on vectors are folded
14588 correctly. */
14590 static void
14592 {
14598 /* Verify equality tests that return a scalar boolean result. */
14604 }
14606 /* Run all of the selftests within this file. */
14608 void
14610 {
14613 }