| blob | e14471ed8d35c66d97223b70bfd21973cd1b29d0 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
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 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a power of two. */
462 /* Fall through. */
477 /* In general we can't negate B in A / B, because if A is INT_MIN and
478 B is 1, we may turn this into INT_MIN / -1 which is undefined
479 and actually traps on some architectures. */
488 /* Negate -((double)float) as (double)(-float). */
490 {
494 }
498 /* Negate -f(x) as f(-x). */
504 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
506 {
510 }
515 }
517 }
519 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
520 simplification is possible.
521 If negate_expr_p would return true for T, NULL_TREE will never be
522 returned. */
524 static tree
526 {
528 tree tem;
531 {
532 /* Convert - (~A) to A + 1. */
558 {
563 }
567 {
572 {
576 }
579 }
602 {
603 /* -(A + B) -> (-B) - A. */
605 {
609 }
611 /* -(A + B) -> (-A) - B. */
613 {
617 }
618 }
622 /* - (A - B) -> B - A */
633 /* Fall through. */
637 {
646 }
658 /* In general we can't negate B in A / B, because if A is INT_MIN and
659 B is 1, we may turn this into INT_MIN / -1 which is undefined
660 and actually traps on some architectures. */
672 /* Convert -((double)float) into (double)(-float). */
674 {
678 }
682 /* Negate -f(x) as f(-x). */
685 {
691 }
695 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
697 {
700 {
707 }
708 }
713 }
716 }
718 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
719 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
720 return NULL_TREE. */
722 static tree
724 {
726 location_t loc;
739 }
740 \f
741 /* Split a tree IN into a constant, literal and variable parts that could be
742 combined with CODE to make IN. "constant" means an expression with
743 TREE_CONSTANT but that isn't an actual constant. CODE must be a
744 commutative arithmetic operation. Store the constant part into *CONP,
745 the literal in *LITP and return the variable part. If a part isn't
746 present, set it to null. If the tree does not decompose in this way,
747 return the entire tree as the variable part and the other parts as null.
749 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
750 case, we negate an operand that was subtracted. Except if it is a
751 literal for which we use *MINUS_LITP instead.
753 If NEGATE_P is true, we are negating all of IN, again except a literal
754 for which we use *MINUS_LITP instead. If a variable part is of pointer
755 type, it is negated after converting to TYPE. This prevents us from
756 generating illegal MINUS pointer expression. LOC is the location of
757 the converted variable part.
759 If IN is itself a literal or constant, return it as appropriate.
761 Note that we do not guarantee that any of the three values will be the
762 same type as IN, but they will have the same signedness and mode. */
764 static tree
767 {
774 /* Strip any conversions that don't change the machine mode or signedness. */
783 /* We can associate addition and subtraction together (even
784 though the C standard doesn't say so) for integers because
785 the value is not affected. For reals, the value might be
786 affected, so we can't. */
789 {
795 /* First see if either of the operands is a literal, then a constant. */
808 /* If we haven't dealt with either operand, this is not a case we can
809 decompose. Otherwise, VAR is either of the ones remaining, if any. */
814 else
817 /* Now do any needed negations. */
823 {
824 /* Convert to TYPE before negating. */
827 }
828 }
833 {
834 /* -X - 1 is folded to ~X, undo that here. Do _not_ do this
835 when IN is constant. */
838 }
839 else
843 {
850 {
851 /* Convert to TYPE before negating. */
854 }
855 }
858 }
860 /* Re-associate trees split by the above function. T1 and T2 are
861 either expressions to associate or null. Return the new
862 expression, if any. LOC is the location of the new expression. If
863 we build an operation, do it in TYPE and with CODE. */
865 static tree
867 {
873 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
874 try to fold this since we will have infinite recursion. But do
875 deal with any NEGATE_EXPRs. */
878 {
880 {
893 }
895 {
898 }
902 }
906 }
907 \f
908 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
909 for use in int_const_binop, size_binop and size_diffop. */
911 static bool
913 {
920 {
929 }
934 }
937 /* Combine two integer constants ARG1 and ARG2 under operation CODE
938 to produce a new constant. Return NULL_TREE if we don't know how
939 to evaluate CODE at compile-time. */
941 static tree
944 {
945 wide_int res;
946 tree t;
954 {
970 {
974 else
976 }
979 /* It's unclear from the C standard whether shifts can overflow.
980 The following code ignores overflow; perhaps a C standard
981 interpretation ruling is needed. */
983 else
990 {
994 else
996 }
1000 else
1079 }
1087 }
1089 tree
1091 {
1093 }
1095 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1096 constant. We assume ARG1 and ARG2 have the same data type, or at least
1097 are the same kind of constant and the same machine mode. Return zero if
1098 combining the constants is not allowed in the current operating mode. */
1100 static tree
1102 {
1103 /* Sanity check for the recursive cases. */
1111 {
1117 }
1120 {
1121 machine_mode mode;
1122 REAL_VALUE_TYPE d1;
1123 REAL_VALUE_TYPE d2;
1124 REAL_VALUE_TYPE value;
1125 REAL_VALUE_TYPE result;
1129 /* The following codes are handled by real_arithmetic. */
1131 {
1142 }
1150 /* Don't perform operation if we honor signaling NaNs and
1151 either operand is a signaling NaN. */
1157 /* Don't perform operation if it would raise a division
1158 by zero exception. */
1164 /* If either operand is a NaN, just return it. Otherwise, set up
1165 for floating-point trap; we return an overflow. */
1167 {
1168 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1169 is off. */
1173 }
1175 {
1176 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1177 is off. */
1181 }
1186 /* Don't constant fold this floating point operation if
1187 the result has overflowed and flag_trapping_math. */
1195 /* Don't constant fold this floating point operation if the
1196 result may dependent upon the run-time rounding mode and
1197 flag_rounding_math is set, or if GCC's software emulation
1198 is unable to accurately represent the result. */
1208 }
1211 {
1212 FIXED_VALUE_TYPE f1;
1213 FIXED_VALUE_TYPE f2;
1214 FIXED_VALUE_TYPE result;
1219 /* The following codes are handled by fixed_arithmetic. */
1221 {
1233 {
1240 }
1245 }
1252 /* Propagate overflow flags. */
1256 }
1259 {
1268 {
1279 mpc_mul);
1293 mpc_div);
1294 /* Fallthru. */
1300 {
1301 /* Keep this algorithm in sync with
1302 tree-complex.c:expand_complex_div_straight().
1304 Expand complex division to scalars, straightforward algorithm.
1305 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1306 t = br*br + bi*bi
1307 */
1308 tree magsquared
1312 tree t1
1316 tree t2
1323 }
1324 else
1325 {
1326 /* Keep this algorithm in sync with
1327 tree-complex.c:expand_complex_div_wide().
1329 Expand complex division to scalars, modified algorithm to minimize
1330 overflow with wide input ranges. */
1336 {
1337 /* In the TRUE branch, we compute
1338 ratio = br/bi;
1339 div = (br * ratio) + bi;
1340 tr = (ar * ratio) + ai;
1341 ti = (ai * ratio) - ar;
1342 tr = tr / div;
1343 ti = ti / div; */
1354 }
1355 else
1356 {
1357 /* In the FALSE branch, we compute
1358 ratio = d/c;
1359 divisor = (d * ratio) + c;
1360 tr = (b * ratio) + a;
1361 ti = b - (a * ratio);
1362 tr = tr / div;
1363 ti = ti / div; */
1375 }
1376 }
1381 }
1385 }
1389 {
1395 {
1401 /* It is possible that const_binop cannot handle the given
1402 code and return NULL_TREE */
1405 }
1408 }
1410 /* Shifts allow a scalar offset for a vector. */
1413 {
1419 {
1424 /* It is possible that const_binop cannot handle the given
1425 code and return NULL_TREE. */
1428 }
1431 }
1433 }
1435 /* Overload that adds a TYPE parameter to be able to dispatch
1436 to fold_relational_const. */
1438 tree
1440 {
1444 /* ??? Until we make the const_binop worker take the type of the
1445 result as argument put those cases that need it here. */
1447 {
1458 {
1474 {
1480 }
1483 }
1489 {
1514 {
1527 }
1530 }
1533 }
1538 /* Make sure type and arg0 have the same saturating flag. */
1543 }
1545 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1546 Return zero if computing the constants is not possible. */
1548 tree
1550 {
1551 /* Don't perform the operation, other than NEGATE and ABS, if
1552 flag_signaling_nans is on and the operand is a signaling NaN. */
1561 {
1562 CASE_CONVERT:
1569 /* If the source address is 0, and the source address space
1570 cannot have a valid object at 0, fold to dest type null. */
1581 {
1582 /* Can't call fold_negate_const directly here as that doesn't
1583 handle all cases and we might not be able to negate some
1584 constants. */
1589 }
1598 {
1602 }
1608 /* Perform BIT_NOT_EXPR on each element individually. */
1610 {
1612 tree elem;
1617 {
1623 }
1626 }
1648 {
1667 else
1671 {
1675 }
1678 }
1683 {
1697 {
1702 }
1705 {
1709 }
1712 }
1716 }
1719 }
1721 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1722 indicates which particular sizetype to create. */
1724 tree
1726 {
1728 }
1729 \f
1730 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1731 is a tree code. The type of the result is taken from the operands.
1732 Both must be equivalent integer types, ala int_binop_types_match_p.
1733 If the operands are constant, so is the result. */
1735 tree
1737 {
1746 /* Handle the special case of two integer constants faster. */
1748 {
1749 /* And some specific cases even faster than that. */
1751 {
1756 }
1758 {
1761 }
1763 {
1766 }
1768 /* Handle general case of two integer constants. For sizetype
1769 constant calculations we always want to know about overflow,
1770 even in the unsigned case. */
1772 }
1775 }
1777 /* Given two values, either both of sizetype or both of bitsizetype,
1778 compute the difference between the two values. Return the value
1779 in signed type corresponding to the type of the operands. */
1781 tree
1783 {
1785 tree ctype;
1790 /* If the type is already signed, just do the simple thing. */
1798 else
1801 /* If either operand is not a constant, do the conversions to the signed
1802 type and subtract. The hardware will do the right thing with any
1803 overflow in the subtraction. */
1809 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1810 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1811 overflow) and negate (which can't either). Special-case a result
1812 of zero while we're here. */
1818 else
1822 MINUS_EXPR,
1824 }
1825 \f
1826 /* A subroutine of fold_convert_const handling conversions of an
1827 INTEGER_CST to another integer type. */
1829 static tree
1831 {
1832 /* Given an integer constant, make new constant with new type,
1833 appropriately sign-extended or truncated. Use widest_int
1834 so that any extension is done according ARG1's type. */
1838 }
1840 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1841 to an integer type. */
1843 static tree
1845 {
1847 tree t;
1849 /* The following code implements the floating point to integer
1850 conversion rules required by the Java Language Specification,
1851 that IEEE NaNs are mapped to zero and values that overflow
1852 the target precision saturate, i.e. values greater than
1853 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1854 are mapped to INT_MIN. These semantics are allowed by the
1855 C and C++ standards that simply state that the behavior of
1856 FP-to-integer conversion is unspecified upon overflow. */
1858 wide_int val;
1859 REAL_VALUE_TYPE r;
1863 {
1870 }
1872 /* If R is NaN, return zero and show we have an overflow. */
1874 {
1877 }
1879 /* See if R is less than the lower bound or greater than the
1880 upper bound. */
1883 {
1887 {
1890 }
1891 }
1894 {
1897 {
1900 {
1903 }
1904 }
1905 }
1912 }
1914 /* A subroutine of fold_convert_const handling conversions of a
1915 FIXED_CST to an integer type. */
1917 static tree
1919 {
1920 tree t;
1924 /* Right shift FIXED_CST to temp by fbit. */
1928 {
1930 HOST_BITS_PER_DOUBLE_INT,
1933 /* Left shift temp to temp_trunc by fbit. */
1935 HOST_BITS_PER_DOUBLE_INT,
1937 }
1938 else
1939 {
1942 }
1944 /* If FIXED_CST is negative, we need to round the value toward 0.
1945 By checking if the fractional bits are not zero to add 1 to temp. */
1951 /* Given a fixed-point constant, make new constant with new type,
1952 appropriately sign-extended or truncated. */
1960 }
1962 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1963 to another floating point type. */
1965 static tree
1967 {
1968 REAL_VALUE_TYPE value;
1969 tree t;
1971 /* Don't perform the operation if flag_signaling_nans is on
1972 and the operand is a signaling NaN. */
1980 /* If converting an infinity or NAN to a representation that doesn't
1981 have one, set the overflow bit so that we can produce some kind of
1982 error message at the appropriate point if necessary. It's not the
1983 most user-friendly message, but it's better than nothing. */
1990 /* Regular overflow, conversion produced an infinity in a mode that
1991 can't represent them. */
1996 else
1999 }
2001 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2002 to a floating point type. */
2004 static tree
2006 {
2007 REAL_VALUE_TYPE value;
2008 tree t;
2015 }
2017 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2018 to another fixed-point type. */
2020 static tree
2022 {
2023 FIXED_VALUE_TYPE value;
2024 tree t;
2031 /* Propagate overflow flags. */
2035 }
2037 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2038 to a fixed-point type. */
2040 static tree
2042 {
2043 FIXED_VALUE_TYPE value;
2044 tree t;
2046 double_int di;
2053 else
2061 /* Propagate overflow flags. */
2065 }
2067 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2068 to a fixed-point type. */
2070 static tree
2072 {
2073 FIXED_VALUE_TYPE value;
2074 tree t;
2082 /* Propagate overflow flags. */
2086 }
2088 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2089 type TYPE. If no simplification can be done return NULL_TREE. */
2091 static tree
2093 {
2099 {
2106 }
2108 {
2115 }
2117 {
2124 }
2126 {
2129 {
2134 {
2140 }
2142 }
2143 }
2145 }
2147 /* Construct a vector of zero elements of vector type TYPE. */
2149 static tree
2151 {
2152 tree t;
2156 }
2158 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2160 bool
2162 {
2177 {
2192 }
2193 }
2195 /* Convert expression ARG to type TYPE. Used by the middle-end for
2196 simple conversions in preference to calling the front-end's convert. */
2198 tree
2200 {
2202 tree tem;
2213 {
2216 /* Handle conversions between pointers to different address spaces. */
2221 /* fall through */
2226 {
2230 }
2244 {
2248 }
2250 {
2254 }
2256 {
2260 }
2263 {
2281 }
2286 {
2290 }
2293 {
2307 }
2311 {
2320 integer_zero_node));
2322 {
2326 {
2332 }
2340 }
2344 }
2362 }
2363 fold_convert_exit:
2366 }
2367 \f
2368 /* Return false if expr can be assumed not to be an lvalue, true
2369 otherwise. */
2371 static bool
2373 {
2374 /* We only need to wrap lvalue tree codes. */
2376 {
2407 /* Assume the worst for front-end tree codes. */
2411 }
2414 }
2416 /* Return an expr equal to X but certainly not valid as an lvalue. */
2418 tree
2420 {
2421 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2422 us. */
2429 }
2431 /* When pedantic, return an expr equal to X but certainly not valid as a
2432 pedantic lvalue. Otherwise, return X. */
2434 static tree
2436 {
2438 }
2439 \f
2440 /* Given a tree comparison code, return the code that is the logical inverse.
2441 It is generally not safe to do this for floating-point comparisons, except
2442 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2443 ERROR_MARK in this case. */
2445 enum tree_code
2447 {
2453 {
2484 }
2485 }
2487 /* Similar, but return the comparison that results if the operands are
2488 swapped. This is safe for floating-point. */
2490 enum tree_code
2492 {
2494 {
2520 }
2521 }
2524 /* Convert a comparison tree code from an enum tree_code representation
2525 into a compcode bit-based encoding. This function is the inverse of
2526 compcode_to_comparison. */
2528 static enum comparison_code
2530 {
2532 {
2563 }
2564 }
2566 /* Convert a compcode bit-based encoding of a comparison operator back
2567 to GCC's enum tree_code representation. This function is the
2568 inverse of comparison_to_compcode. */
2570 static enum tree_code
2572 {
2574 {
2605 }
2606 }
2608 /* Return a tree for the comparison which is the combination of
2609 doing the AND or OR (depending on CODE) of the two operations LCODE
2610 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2611 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2612 if this makes the transformation invalid. */
2614 tree
2619 {
2626 {
2637 }
2640 {
2641 /* Eliminate unordered comparisons, as well as LTGT and ORD
2642 which are not used unless the mode has NaNs. */
2648 }
2650 {
2651 /* Check that the original operation and the optimized ones will trap
2652 under the same condition. */
2663 /* In a short-circuited boolean expression the LHS might be
2664 such that the RHS, if evaluated, will never trap. For
2665 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2666 if neither x nor y is NaN. (This is a mixed blessing: for
2667 example, the expression above will never trap, hence
2668 optimizing it to x < y would be invalid). */
2673 /* If the comparison was short-circuited, and only the RHS
2674 trapped, we may now generate a spurious trap. */
2679 /* If we changed the conditions that cause a trap, we lose. */
2682 }
2688 else
2689 {
2694 }
2695 }
2696 \f
2697 /* Return nonzero if two operands (typically of the same tree node)
2698 are necessarily equal. FLAGS modifies behavior as follows:
2700 If OEP_ONLY_CONST is set, only return nonzero for constants.
2701 This function tests whether the operands are indistinguishable;
2702 it does not test whether they are equal using C's == operation.
2703 The distinction is important for IEEE floating point, because
2704 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2705 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2707 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2708 even though it may hold multiple values during a function.
2709 This is because a GCC tree node guarantees that nothing else is
2710 executed between the evaluation of its "operands" (which may often
2711 be evaluated in arbitrary order). Hence if the operands themselves
2712 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2713 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2714 unset means assuming isochronic (or instantaneous) tree equivalence.
2715 Unless comparing arbitrary expression trees, such as from different
2716 statements, this flag can usually be left unset.
2718 If OEP_PURE_SAME is set, then pure functions with identical arguments
2719 are considered the same. It is used when the caller has other ways
2720 to ensure that global memory is unchanged in between.
2722 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2723 not values of expressions.
2725 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2726 any operand with side effect. This is unnecesarily conservative in the
2727 case we know that arg0 and arg1 are in disjoint code paths (such as in
2728 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2729 addresses with TREE_CONSTANT flag set so we know that &var == &var
2730 even if var is volatile. */
2732 int
2734 {
2735 /* When checking, verify at the outermost operand_equal_p call that
2736 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2737 hash value. */
2739 {
2741 {
2743 {
2750 }
2752 }
2753 else
2755 }
2757 /* If either is ERROR_MARK, they aren't equal. */
2763 /* Similar, if either does not have a type (like a released SSA name),
2764 they aren't equal. */
2768 /* We cannot consider pointers to different address space equal. */
2775 /* Check equality of integer constants before bailing out due to
2776 precision differences. */
2778 {
2779 /* Address of INTEGER_CST is not defined; check that we did not forget
2780 to drop the OEP_ADDRESS_OF flags. */
2783 }
2786 {
2787 /* If both types don't have the same signedness, then we can't consider
2788 them equal. We must check this before the STRIP_NOPS calls
2789 because they may change the signedness of the arguments. As pointers
2790 strictly don't have a signedness, require either two pointers or
2791 two non-pointers as well. */
2797 /* If both types don't have the same precision, then it is not safe
2798 to strip NOPs. */
2805 }
2806 #if 0
2807 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2808 sanity check once the issue is solved. */
2809 else
2810 /* Addresses of conversions and SSA_NAMEs (and many other things)
2811 are not defined. Check that we did not forget to drop the
2812 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2815 #endif
2817 /* In case both args are comparisons but with different comparison
2818 code, try to swap the comparison operands of one arg to produce
2819 a match and compare that variant. */
2823 {
2831 }
2834 {
2835 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2837 ;
2839 {
2840 /* If we are interested in comparing addresses ignore
2841 MEM_REF wrappings of the base that can appear just for
2842 TBAA reasons. */
2856 }
2857 else
2859 }
2861 /* When not checking adddresses, this is needed for conversions and for
2862 COMPONENT_REF. Might as well play it safe and always test this. */
2869 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2870 We don't care about side effects in that case because the SAVE_EXPR
2871 takes care of that for us. In all other cases, two expressions are
2872 equal if they have no side effects. If we have two identical
2873 expressions with side effects that should be treated the same due
2874 to the only side effects being identical SAVE_EXPR's, that will
2875 be detected in the recursive calls below.
2876 If we are taking an invariant address of two identical objects
2877 they are necessarily equal as well. */
2884 /* Next handle constant cases, those for which we can return 1 even
2885 if ONLY_CONST is set. */
2888 {
2902 {
2903 /* If we do not distinguish between signed and unsigned zero,
2904 consider them equal. */
2907 }
2911 {
2918 {
2922 }
2924 }
2928 flags)
2930 flags));
2941 flags | OEP_ADDRESS_OF
2944 /* In GIMPLE empty constructors are allowed in initializers of
2945 aggregates. */
2949 }
2954 /* Define macros to test an operand from arg0 and arg1 for equality and a
2955 variant that allows null and views null as being different from any
2956 non-null value. In the latter case, if either is null, the both
2957 must be; otherwise, do the normal comparison. */
2958 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2959 TREE_OPERAND (arg1, N), flags)
2961 #define OP_SAME_WITH_NULL(N) \
2962 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2963 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2966 {
2968 /* Two conversions are equal only if signedness and modes match. */
2970 {
2971 CASE_CONVERT:
2979 }
2989 /* For commutative ops, allow the other order. */
2997 /* If either of the pointer (or reference) expressions we are
2998 dereferencing contain a side effect, these cannot be equal,
2999 but their addresses can be. */
3006 {
3016 /* Require the same offset. */
3022 /* Fallthru. */
3030 {
3031 /* Require equal access sizes */
3037 flags)))
3039 /* Verify that access happens in similar types. */
3042 /* Verify that accesses are TBAA compatible. */
3051 /* Verify that alignment is compatible. */
3055 }
3058 /* TARGET_MEM_REF require equal extra operands. */
3069 /* Compare the array index by value if it is constant first as we
3070 may have different types but same value here. */
3076 /* Compare low bound and element size as with OEP_ADDRESS_OF
3077 we have to account for the offset of the ref. */
3082 array_ref_low_bound
3086 array_ref_element_size
3088 flags))));
3091 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3092 may be NULL when we're called to compare MEM_EXPRs. */
3107 }
3111 {
3113 /* Be sure we pass right ADDRESS_OF flag. */
3131 /* The multiplcation operands are commutative. */
3132 /* FALLTHRU */
3140 /* Otherwise take into account this is a commutative operation. */
3159 }
3163 {
3167 /* If not both CALL_EXPRs are either internal or normal function
3168 functions, then they are not equal. */
3171 {
3172 /* If the CALL_EXPRs call different internal functions, then they
3173 are not equal. */
3176 }
3177 else
3178 {
3179 /* If the CALL_EXPRs call different functions, then they are not
3180 equal. */
3182 flags))
3184 }
3186 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3187 {
3191 else
3195 }
3197 /* Now see if all the arguments are the same. */
3198 {
3209 /* If we get here and both argument lists are exhausted
3210 then the CALL_EXPRs are equal. */
3212 }
3215 }
3218 /* Consider __builtin_sqrt equal to sqrt. */
3226 {
3227 /* In GIMPLE constructors are used only to build vectors from
3228 elements. Individual elements in the constructor must be
3229 indexed in increasing order and form an initial sequence.
3231 We make no effort to compare constructors in generic.
3232 (see sem_variable::equals in ipa-icf which can do so for
3233 constants). */
3238 /* Be sure that vectors constructed have the same representation.
3239 We only tested element precision and modes to match.
3240 Vectors may be BLKmode and thus also check that the number of
3241 parts match. */
3254 {
3259 /* In GIMPLE the indexes can be either NULL or matching i.
3260 Double check this so we won't get false
3261 positives for GENERIC. */
3269 }
3271 }
3276 }
3278 #undef OP_SAME
3279 #undef OP_SAME_WITH_NULL
3280 }
3281 \f
3282 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3283 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3285 When in doubt, return 0. */
3287 static int
3289 {
3301 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3302 and see if the inner values are the same. This removes any
3303 signedness comparison, which doesn't matter here. */
3310 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3311 actual comparison operand, ARG0.
3313 First throw away any conversions to wider types
3314 already present in the operands. */
3323 {
3326 /* Make sure shorter operand is extended the right way
3327 to match the longer operand. */
3333 }
3336 }
3337 \f
3338 /* See if ARG is an expression that is either a comparison or is performing
3339 arithmetic on comparisons. The comparisons must only be comparing
3340 two different values, which will be stored in *CVAL1 and *CVAL2; if
3341 they are nonzero it means that some operands have already been found.
3342 No variables may be used anywhere else in the expression except in the
3343 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3344 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3346 If this is true, return 1. Otherwise, return zero. */
3348 static int
3350 {
3354 /* We can handle some of the tcc_expression cases here. */
3364 {
3365 /* If we've already found a CVAL1 or CVAL2, this expression is
3366 two complex to handle. */
3372 }
3375 {
3398 /* First see if we can handle the first operand, then the second. For
3399 the second operand, we know *CVAL1 can't be zero. It must be that
3400 one side of the comparison is each of the values; test for the
3401 case where this isn't true by failing if the two operands
3402 are the same. */
3411 ;
3415 ;
3416 else
3420 ;
3424 ;
3425 else
3432 }
3433 }
3434 \f
3435 /* ARG is a tree that is known to contain just arithmetic operations and
3436 comparisons. Evaluate the operations in the tree substituting NEW0 for
3437 any occurrence of OLD0 as an operand of a comparison and likewise for
3438 NEW1 and OLD1. */
3440 static tree
3443 {
3448 /* We can handle some of the tcc_expression cases here. */
3456 {
3471 {
3490 }
3491 /* Fall through - ??? */
3494 {
3498 /* We need to check both for exact equality and tree equality. The
3499 former will be true if the operand has a side-effect. In that
3500 case, we know the operand occurred exactly once. */
3513 }
3517 }
3518 }
3519 \f
3520 /* Return a tree for the case when the result of an expression is RESULT
3521 converted to TYPE and OMITTED was previously an operand of the expression
3522 but is now not needed (e.g., we folded OMITTED * 0).
3524 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3525 the conversion of RESULT to TYPE. */
3527 tree
3529 {
3532 /* If the resulting operand is an empty statement, just return the omitted
3533 statement casted to void. */
3543 }
3545 /* Return a tree for the case when the result of an expression is RESULT
3546 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3547 of the expression but are now not needed.
3549 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3550 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3551 evaluated before OMITTED2. Otherwise, if neither has side effects,
3552 just do the conversion of RESULT to TYPE. */
3554 tree
3557 {
3566 }
3568 \f
3569 /* Return a simplified tree node for the truth-negation of ARG. This
3570 never alters ARG itself. We assume that ARG is an operation that
3571 returns a truth value (0 or 1).
3573 FIXME: one would think we would fold the result, but it causes
3574 problems with the dominator optimizer. */
3576 static tree
3578 {
3583 /* If this is a comparison, we can simply invert it, except for
3584 floating-point non-equality comparisons, in which case we just
3585 enclose a TRUTH_NOT_EXPR around what we have. */
3588 {
3591 && flag_trapping_math
3605 }
3608 {
3627 /* Here we can invert either operand. We invert the first operand
3628 unless the second operand is a TRUTH_NOT_EXPR in which case our
3629 result is the XOR of the first operand with the inside of the
3630 negation of the second operand. */
3635 else
3658 {
3665 /* A COND_EXPR may have a throw as one operand, which
3666 then has void type. Just leave void operands
3667 as they are. */
3673 }
3685 CASE_CONVERT:
3689 /* fall through */
3711 }
3712 }
3714 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3715 assume that ARG is an operation that returns a truth value (0 or 1
3716 for scalars, 0 or -1 for vectors). Return the folded expression if
3717 folding is successful. Otherwise, return NULL_TREE. */
3719 static tree
3721 {
3724 ? BIT_NOT_EXPR
3727 }
3729 /* Return a simplified tree node for the truth-negation of ARG. This
3730 never alters ARG itself. We assume that ARG is an operation that
3731 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3733 tree
3735 {
3741 ? BIT_NOT_EXPR
3744 }
3746 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3747 with code CODE. This optimization is unsafe. */
3748 static tree
3751 {
3755 /* (A / C) +- (B / C) -> (A +- B) / C. */
3765 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3770 {
3782 }
3785 }
3786 \f
3787 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3788 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3789 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3790 is the original memory reference used to preserve the alias set of
3791 the access. */
3793 static tree
3797 {
3807 {
3814 }
3829 }
3831 /* Optimize a bit-field compare.
3833 There are two cases: First is a compare against a constant and the
3834 second is a comparison of two items where the fields are at the same
3835 bit position relative to the start of a chunk (byte, halfword, word)
3836 large enough to contain it. In these cases we can avoid the shift
3837 implicit in bitfield extractions.
3839 For constants, we emit a compare of the shifted constant with the
3840 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3841 compared. For two fields at the same position, we do the ANDs with the
3842 similar mask and compare the result of the ANDs.
3844 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3845 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3846 are the left and right operands of the comparison, respectively.
3848 If the optimization described above can be done, we return the resulting
3849 tree. Otherwise we return zero. */
3851 static tree
3854 {
3857 tree unsigned_type;
3864 tree mask;
3865 tree offset;
3867 /* Get all the information about the extractions being done. If the bit size
3868 if the same as the size of the underlying object, we aren't doing an
3869 extraction at all and so can do nothing. We also don't want to
3870 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3871 then will no longer be able to replace it. */
3880 else
3881 {
3882 /* If this is not a constant, we can only do something if bit positions,
3883 sizes, signedness and storage order are the same. */
3884 rinner
3892 }
3894 /* Honor the C++ memory model and mimic what RTL expansion does. */
3898 {
3902 }
3904 /* See if we can find a mode to refer to this field. We should be able to,
3905 but fail if we can't. */
3914 /* Set signed and unsigned types of the precision of this mode for the
3915 shifts below. */
3918 /* Compute the bit position and size for the new reference and our offset
3919 within it. If the new reference is the same size as the original, we
3920 won't optimize anything, so return zero. */
3930 /* Make the mask to be used against the extracted field. */
3937 /* If not comparing with constant, just rework the comparison
3938 and return. */
3942 unsigned_type,
3945 mask),
3948 unsigned_type,
3951 mask));
3953 /* Otherwise, we are handling the constant case. See if the constant is too
3954 big for the field. Warn and return a tree for 0 (false) if so. We do
3955 this not only for its own sake, but to avoid having to test for this
3956 error case below. If we didn't, we might generate wrong code.
3958 For unsigned fields, the constant shifted right by the field length should
3959 be all zero. For signed fields, the high-order bits should agree with
3960 the sign bit. */
3963 {
3965 {
3969 }
3970 }
3971 else
3972 {
3975 {
3979 }
3980 }
3982 /* Single-bit compares should always be against zero. */
3984 {
3987 }
3989 /* Make a new bitfield reference, shift the constant over the
3990 appropriate number of bits and mask it with the computed mask
3991 (in case this was a signed field). If we changed it, make a new one. */
3999 mask);
4004 }
4005 \f
4006 /* Subroutine for fold_truth_andor_1: decode a field reference.
4008 If EXP is a comparison reference, we return the innermost reference.
4010 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4011 set to the starting bit number.
4013 If the innermost field can be completely contained in a mode-sized
4014 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4016 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4017 otherwise it is not changed.
4019 *PUNSIGNEDP is set to the signedness of the field.
4021 *PREVERSEP is set to the storage order of the field.
4023 *PMASK is set to the mask used. This is either contained in a
4024 BIT_AND_EXPR or derived from the width of the field.
4026 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4028 Return 0 if this is not a component reference or is one that we can't
4029 do anything with. */
4031 static tree
4036 {
4041 tree unsigned_type;
4044 /* All the optimizations using this function assume integer fields.
4045 There are problems with FP fields since the type_for_size call
4046 below can fail for, e.g., XFmode. */
4050 /* We are interested in the bare arrangement of bits, so strip everything
4051 that doesn't affect the machine mode. However, record the type of the
4052 outermost expression if it may matter below. */
4059 {
4065 }
4076 /* If the number of bits in the reference is the same as the bitsize of
4077 the outer type, then the outer type gives the signedness. Otherwise
4078 (in case of a small bitfield) the signedness is unchanged. */
4082 /* Compute the mask to access the bitfield. */
4091 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4099 }
4101 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4102 bit positions and MASK is SIGNED. */
4104 static int
4106 {
4110 /* If this function returns true when the type of the mask is
4111 UNSIGNED, then there will be errors. In particular see
4112 gcc.c-torture/execute/990326-1.c. There does not appear to be
4113 any documentation paper trail as to why this is so. But the pre
4114 wide-int worked with that restriction and it has been preserved
4115 here. */
4120 }
4122 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4123 represents the sign bit of EXP's type. If EXP represents a sign
4124 or zero extension, also test VAL against the unextended type.
4125 The return value is the (sub)expression whose sign bit is VAL,
4126 or NULL_TREE otherwise. */
4128 tree
4130 {
4132 tree t;
4134 /* Tree EXP must have an integral type. */
4139 /* Tree VAL must be an integer constant. */
4148 /* Handle extension from a narrower type. */
4154 }
4156 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4157 to be evaluated unconditionally. */
4159 static int
4161 {
4162 /* Strip any conversions that don't change the machine mode. */
4171 /* Don't regard global variables as simple. They may be
4172 allocated in ways unknown to the compiler (shared memory,
4173 #pragma weak, etc). */
4176 /* Weakrefs are not safe to be read, since they can be NULL.
4177 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4178 have DECL_WEAK flag set. */
4180 /* Loading a static variable is unduly expensive, but global
4181 registers aren't expensive. */
4183 }
4185 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4186 to be evaluated unconditionally.
4187 I addition to simple_operand_p, we assume that comparisons, conversions,
4188 and logic-not operations are simple, if their operands are simple, too. */
4190 static bool
4192 {
4212 }
4214 \f
4215 /* The following functions are subroutines to fold_range_test and allow it to
4216 try to change a logical combination of comparisons into a range test.
4218 For example, both
4219 X == 2 || X == 3 || X == 4 || X == 5
4220 and
4221 X >= 2 && X <= 5
4222 are converted to
4223 (unsigned) (X - 2) <= 3
4225 We describe each set of comparisons as being either inside or outside
4226 a range, using a variable named like IN_P, and then describe the
4227 range with a lower and upper bound. If one of the bounds is omitted,
4228 it represents either the highest or lowest value of the type.
4230 In the comments below, we represent a range by two numbers in brackets
4231 preceded by a "+" to designate being inside that range, or a "-" to
4232 designate being outside that range, so the condition can be inverted by
4233 flipping the prefix. An omitted bound is represented by a "-". For
4234 example, "- [-, 10]" means being outside the range starting at the lowest
4235 possible value and ending at 10, in other words, being greater than 10.
4236 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4237 always false.
4239 We set up things so that the missing bounds are handled in a consistent
4240 manner so neither a missing bound nor "true" and "false" need to be
4241 handled using a special case. */
4243 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4244 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4245 and UPPER1_P are nonzero if the respective argument is an upper bound
4246 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4247 must be specified for a comparison. ARG1 will be converted to ARG0's
4248 type if both are specified. */
4250 static tree
4253 {
4254 tree tem;
4258 /* If neither arg represents infinity, do the normal operation.
4259 Else, if not a comparison, return infinity. Else handle the special
4260 comparison rules. Note that most of the cases below won't occur, but
4261 are handled for consistency. */
4264 {
4269 }
4274 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4275 for neither. In real maths, we cannot assume open ended ranges are
4276 the same. But, this is computer arithmetic, where numbers are finite.
4277 We can therefore make the transformation of any unbounded range with
4278 the value Z, Z being greater than any representable number. This permits
4279 us to treat unbounded ranges as equal. */
4283 {
4304 }
4307 }
4308 \f
4309 /* Helper routine for make_range. Perform one step for it, return
4310 new expression if the loop should continue or NULL_TREE if it should
4311 stop. */
4313 tree
4317 {
4323 {
4325 /* We can only do something if the range is testing for zero. */
4334 /* We can only do something if the range is testing for zero
4335 and if the second operand is an integer constant. Note that
4336 saying something is "in" the range we make is done by
4337 complementing IN_P since it will set in the initial case of
4338 being not equal to zero; "out" is leaving it alone. */
4345 {
4366 }
4368 /* If this is an unsigned comparison, we also know that EXP is
4369 greater than or equal to zero. We base the range tests we make
4370 on that fact, so we record it here so we can parse existing
4371 range tests. We test arg0_type since often the return type
4372 of, e.g. EQ_EXPR, is boolean. */
4374 {
4378 NULL_TREE))
4383 /* If the high bound is missing, but we have a nonzero low
4384 bound, reverse the range so it goes from zero to the low bound
4385 minus 1. */
4387 {
4392 }
4393 }
4401 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4402 low and high are non-NULL, then normalize will DTRT. */
4405 {
4410 }
4412 /* (-x) IN [a,b] -> x in [-b, -a] */
4424 /* ~ X -> -X - 1 */
4433 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4434 move a constant to the other side. */
4439 /* If EXP is signed, any overflow in the computation is undefined,
4440 so we don't worry about it so long as our computations on
4441 the bounds don't overflow. For unsigned, overflow is defined
4442 and this is exactly the right thing. */
4454 normalize:
4455 /* Check for an unsigned range which has wrapped around the maximum
4456 value thus making n_high < n_low, and normalize it. */
4458 {
4464 /* If the range is of the form +/- [ x+1, x ], we won't
4465 be able to normalize it. But then, it represents the
4466 whole range or the empty set, so make it
4467 +/- [ -, - ]. */
4471 else
4473 }
4474 else
4482 CASE_CONVERT:
4500 /* If we're converting arg0 from an unsigned type, to exp,
4501 a signed type, we will be doing the comparison as unsigned.
4502 The tests above have already verified that LOW and HIGH
4503 are both positive.
4505 So we have to ensure that we will handle large unsigned
4506 values the same way that the current signed bounds treat
4507 negative values. */
4510 {
4511 tree high_positive;
4512 tree equiv_type;
4513 /* For fixed-point modes, we need to pass the saturating flag
4514 as the 2nd parameter. */
4516 equiv_type
4519 else
4520 equiv_type
4523 /* A range without an upper bound is, naturally, unbounded.
4524 Since convert would have cropped a very large value, use
4525 the max value for the destination type. */
4526 high_positive
4533 high_positive),
4536 /* If the low bound is specified, "and" the range with the
4537 range for which the original unsigned value will be
4538 positive. */
4540 {
4543 integer_zero_node),
4544 high_positive))
4548 }
4549 else
4550 {
4551 /* Otherwise, "or" the range with the range of the input
4552 that will be interpreted as negative. */
4555 integer_zero_node),
4556 high_positive))
4560 }
4561 }
4570 }
4571 }
4573 /* Given EXP, a logical expression, set the range it is testing into
4574 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4575 actually being tested. *PLOW and *PHIGH will be made of the same
4576 type as the returned expression. If EXP is not a comparison, we
4577 will most likely not be returning a useful value and range. Set
4578 *STRICT_OVERFLOW_P to true if the return value is only valid
4579 because signed overflow is undefined; otherwise, do not change
4580 *STRICT_OVERFLOW_P. */
4582 tree
4585 {
4593 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4594 and see if we can refine the range. Some of the cases below may not
4595 happen, but it doesn't seem worth worrying about this. We "continue"
4596 the outer loop when we've changed something; otherwise we "break"
4597 the switch, which will "break" the while. */
4603 {
4609 {
4617 }
4626 }
4628 /* If EXP is a constant, we can evaluate whether this is true or false. */
4630 {
4637 }
4641 }
4642 \f
4643 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4644 type, TYPE, return an expression to test if EXP is in (or out of, depending
4645 on IN_P) the range. Return 0 if the test couldn't be created. */
4647 tree
4650 {
4653 /* Disable this optimization for function pointer expressions
4654 on targets that require function pointer canonicalization. */
4661 {
4667 }
4685 {
4687 {
4691 }
4693 }
4695 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4697 {
4701 {
4703 {
4706 etype
4708 else
4711 }
4714 }
4715 }
4717 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4718 This requires wrap-around arithmetics for the type of the expression.
4719 First make sure that arithmetics in this type is valid, then make sure
4720 that it wraps around. */
4726 {
4729 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4730 for the type in question, as we rely on this here. */
4740 else
4742 }
4752 {
4754 {
4759 }
4761 }
4769 }
4770 \f
4771 /* Return the predecessor of VAL in its type, handling the infinite case. */
4773 static tree
4775 {
4781 else
4784 }
4786 /* Return the successor of VAL in its type, handling the infinite case. */
4788 static tree
4790 {
4796 else
4799 }
4801 /* Given two ranges, see if we can merge them into one. Return 1 if we
4802 can, 0 if we can't. Set the output range into the specified parameters. */
4804 bool
4807 {
4811 tree tem;
4821 /* Make range 0 be the range that starts first, or ends last if they
4822 start at the same value. Swap them if it isn't. */
4825 || (lowequal
4828 {
4832 }
4834 /* Now flag two cases, whether the ranges are disjoint or whether the
4835 second range is totally subsumed in the first. Note that the tests
4836 below are simplified by the ones above. */
4842 /* We now have four cases, depending on whether we are including or
4843 excluding the two ranges. */
4845 {
4846 /* If they don't overlap, the result is false. If the second range
4847 is a subset it is the result. Otherwise, the range is from the start
4848 of the second to the end of the first. */
4853 else
4855 }
4858 {
4859 /* If they don't overlap, the result is the first range. If they are
4860 equal, the result is false. If the second range is a subset of the
4861 first, and the ranges begin at the same place, we go from just after
4862 the end of the second range to the end of the first. If the second
4863 range is not a subset of the first, or if it is a subset and both
4864 ranges end at the same place, the range starts at the start of the
4865 first range and ends just before the second range.
4866 Otherwise, we can't describe this as a single range. */
4872 {
4877 {
4878 /* We are in the weird situation where high0 > high1 but
4879 high1 has no successor. Punt. */
4881 }
4882 }
4884 {
4889 {
4890 /* low0 < low1 but low1 has no predecessor. Punt. */
4892 }
4893 }
4894 else
4896 }
4899 {
4900 /* If they don't overlap, the result is the second range. If the second
4901 is a subset of the first, the result is false. Otherwise,
4902 the range starts just after the first range and ends at the
4903 end of the second. */
4908 else
4909 {
4914 {
4915 /* high1 > high0 but high0 has no successor. Punt. */
4917 }
4918 }
4919 }
4921 else
4922 {
4923 /* The case where we are excluding both ranges. Here the complex case
4924 is if they don't overlap. In that case, the only time we have a
4925 range is if they are adjacent. If the second is a subset of the
4926 first, the result is the first. Otherwise, the range to exclude
4927 starts at the beginning of the first range and ends at the end of the
4928 second. */
4930 {
4935 else
4936 {
4937 /* Canonicalize - [min, x] into - [-, x]. */
4940 {
4945 /* FALLTHROUGH */
4958 }
4960 /* Canonicalize - [x, max] into - [x, -]. */
4963 {
4968 /* FALLTHROUGH */
4984 }
4986 /* The ranges might be also adjacent between the maximum and
4987 minimum values of the given type. For
4988 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4989 return + [x + 1, y - 1]. */
4991 {
4998 }
4999 else
5001 }
5002 }
5005 else
5007 }
5011 }
5012 \f
5014 /* Subroutine of fold, looking inside expressions of the form
5015 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5016 of the COND_EXPR. This function is being used also to optimize
5017 A op B ? C : A, by reversing the comparison first.
5019 Return a folded expression whose code is not a COND_EXPR
5020 anymore, or NULL_TREE if no folding opportunity is found. */
5022 static tree
5025 {
5030 tree tem;
5035 /* If we have A op 0 ? A : -A, consider applying the following
5036 transformations:
5038 A == 0? A : -A same as -A
5039 A != 0? A : -A same as A
5040 A >= 0? A : -A same as abs (A)
5041 A > 0? A : -A same as abs (A)
5042 A <= 0? A : -A same as -abs (A)
5043 A < 0? A : -A same as -abs (A)
5045 None of these transformations work for modes with signed
5046 zeros. If A is +/-0, the first two transformations will
5047 change the sign of the result (from +0 to -0, or vice
5048 versa). The last four will fix the sign of the result,
5049 even though the original expressions could be positive or
5050 negative, depending on the sign of A.
5052 Note that all these transformations are correct if A is
5053 NaN, since the two alternatives (A and -A) are also NaNs. */
5060 /* In the case that A is of the form X-Y, '-A' (arg2) may
5061 have already been folded to Y-X, check for that. */
5069 {
5081 /* Fall through. */
5092 /* FALLTHRU */
5102 }
5104 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5105 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5106 both transformations are correct when A is NaN: A != 0
5107 is then true, and A == 0 is false. */
5111 {
5116 }
5118 /* Try some transformations of A op B ? A : B.
5120 A == B? A : B same as B
5121 A != B? A : B same as A
5122 A >= B? A : B same as max (A, B)
5123 A > B? A : B same as max (B, A)
5124 A <= B? A : B same as min (A, B)
5125 A < B? A : B same as min (B, A)
5127 As above, these transformations don't work in the presence
5128 of signed zeros. For example, if A and B are zeros of
5129 opposite sign, the first two transformations will change
5130 the sign of the result. In the last four, the original
5131 expressions give different results for (A=+0, B=-0) and
5132 (A=-0, B=+0), but the transformed expressions do not.
5134 The first two transformations are correct if either A or B
5135 is a NaN. In the first transformation, the condition will
5136 be false, and B will indeed be chosen. In the case of the
5137 second transformation, the condition A != B will be true,
5138 and A will be chosen.
5140 The conversions to max() and min() are not correct if B is
5141 a number and A is not. The conditions in the original
5142 expressions will be false, so all four give B. The min()
5143 and max() versions would give a NaN instead. */
5146 /* Avoid these transformations if the COND_EXPR may be used
5147 as an lvalue in the C++ front-end. PR c++/19199. */
5148 && (in_gimple_form
5154 {
5160 {
5169 /* In C++ a ?: expression can be an lvalue, so put the
5170 operand which will be used if they are equal first
5171 so that we can convert this back to the
5172 corresponding COND_EXPR. */
5174 {
5182 }
5189 {
5197 }
5210 }
5211 }
5213 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5214 we might still be able to simplify this. For example,
5215 if C1 is one less or one more than C2, this might have started
5216 out as a MIN or MAX and been transformed by this function.
5217 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5223 {
5227 /* We can replace A with C1 in this case. */
5232 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5233 MIN_EXPR, to preserve the signedness of the comparison. */
5235 OEP_ONLY_CONST)
5239 OEP_ONLY_CONST))
5240 {
5243 arg2));
5245 }
5249 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5250 as above. */
5252 OEP_ONLY_CONST)
5256 OEP_ONLY_CONST))
5257 {
5260 arg2));
5262 }
5266 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5267 MAX_EXPR, to preserve the signedness of the comparison. */
5269 OEP_ONLY_CONST)
5273 OEP_ONLY_CONST))
5274 {
5277 arg2));
5279 }
5283 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5285 OEP_ONLY_CONST)
5289 OEP_ONLY_CONST))
5290 {
5293 arg2));
5295 }
5301 }
5304 }
5307 \f
5308 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5309 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5310 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5311 false) >= 2)
5312 #endif
5314 /* EXP is some logical combination of boolean tests. See if we can
5315 merge it into some range test. Return the new tree if so. */
5317 static tree
5320 {
5336 /* If this is an OR operation, invert both sides; we will invert
5337 again at the end. */
5341 /* If both expressions are the same, if we can merge the ranges, and we
5342 can build the range test, return it or it inverted. If one of the
5343 ranges is always true or always false, consider it to be the same
5344 expression as the other. */
5352 {
5356 }
5358 /* On machines where the branch cost is expensive, if this is a
5359 short-circuited branch and the underlying object on both sides
5360 is the same, make a non-short-circuit operation. */
5366 {
5367 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5368 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5369 which cases we can't do this. */
5377 {
5386 {
5389 WARN_STRICT_OVERFLOW_COMPARISON);
5393 }
5394 }
5395 }
5398 }
5399 \f
5400 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5401 bit value. Arrange things so the extra bits will be set to zero if and
5402 only if C is signed-extended to its full width. If MASK is nonzero,
5403 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5405 static tree
5407 {
5410 tree temp;
5415 /* We work by getting just the sign bit into the low-order bit, then
5416 into the high-order bit, then sign-extend. We then XOR that value
5417 with C. */
5420 /* We must use a signed type in order to get an arithmetic right shift.
5421 However, we must also avoid introducing accidental overflows, so that
5422 a subsequent call to integer_zerop will work. Hence we must
5423 do the type conversion here. At this point, the constant is either
5424 zero or one, and the conversion to a signed type can never overflow.
5425 We could get an overflow if this conversion is done anywhere else. */
5434 /* If necessary, convert the type back to match the type of C. */
5439 }
5440 \f
5441 /* For an expression that has the form
5442 (A && B) || ~B
5443 or
5444 (A || B) && ~B,
5445 we can drop one of the inner expressions and simplify to
5446 A || ~B
5447 or
5448 A && ~B
5449 LOC is the location of the resulting expression. OP is the inner
5450 logical operation; the left-hand side in the examples above, while CMPOP
5451 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5452 removing a condition that guards another, as in
5453 (A != NULL && A->...) || A == NULL
5454 which we must not transform. If RHS_ONLY is true, only eliminate the
5455 right-most operand of the inner logical operation. */
5457 static tree
5460 {
5478 {
5481 {
5484 }
5485 }
5487 {
5490 {
5493 }
5494 }
5509 }
5511 /* Find ways of folding logical expressions of LHS and RHS:
5512 Try to merge two comparisons to the same innermost item.
5513 Look for range tests like "ch >= '0' && ch <= '9'".
5514 Look for combinations of simple terms on machines with expensive branches
5515 and evaluate the RHS unconditionally.
5517 For example, if we have p->a == 2 && p->b == 4 and we can make an
5518 object large enough to span both A and B, we can do this with a comparison
5519 against the object ANDed with the a mask.
5521 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5522 operations to do this with one comparison.
5524 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5525 function and the one above.
5527 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5528 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5530 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5531 two operands.
5533 We return the simplified tree or 0 if no optimization is possible. */
5535 static tree
5538 {
5539 /* If this is the "or" of two comparisons, we can do something if
5540 the comparisons are NE_EXPR. If this is the "and", we can do something
5541 if the comparisons are EQ_EXPR. I.e.,
5542 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5544 WANTED_CODE is this operation code. For single bit fields, we can
5545 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5546 comparison for one-bit fields. */
5567 /* Start by getting the comparison codes. Fail if anything is volatile.
5568 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5569 it were surrounded with a NE_EXPR. */
5578 {
5582 }
5585 {
5589 }
5600 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5603 {
5606 {
5611 }
5614 {
5620 }
5621 }
5626 /* If the RHS can be evaluated unconditionally and its operands are
5627 simple, it wins to evaluate the RHS unconditionally on machines
5628 with expensive branches. In this case, this isn't a comparison
5629 that can be merged. */
5636 {
5637 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5648 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5658 }
5660 /* See if the comparisons can be merged. Then get all the parameters for
5661 each side. */
5686 /* It must be true that the inner operation on the lhs of each
5687 comparison must be the same if we are to be able to do anything.
5688 Then see if we have constants. If not, the same must be true for
5689 the rhs's. */
5698 {
5701 }
5706 else
5709 /* If either comparison code is not correct for our logical operation,
5710 fail. However, we can convert a one-bit comparison against zero into
5711 the opposite comparison against that bit being set in the field. */
5715 {
5717 {
5718 /* Make the left operand unsigned, since we are only interested
5719 in the value of one bit. Otherwise we are doing the wrong
5720 thing below. */
5723 }
5724 else
5726 }
5728 /* This is analogous to the code for l_const above. */
5730 {
5732 {
5735 }
5736 else
5738 }
5740 /* See if we can find a mode that contains both fields being compared on
5741 the left. If we can't, fail. Otherwise, update all constants and masks
5742 to be relative to a field of that size. */
5747 volatilep);
5757 {
5760 }
5768 {
5775 {
5779 }
5780 }
5782 {
5789 {
5793 }
5794 }
5796 /* If the right sides are not constant, do the same for it. Also,
5797 disallow this optimization if a size or signedness mismatch occurs
5798 between the left and right sides. */
5800 {
5803 /* Make sure the two fields on the right
5804 correspond to the left without being swapped. */
5812 volatilep);
5822 {
5825 }
5834 /* Make a mask that corresponds to both fields being compared.
5835 Do this for both items being compared. If the operands are the
5836 same size and the bits being compared are in the same position
5837 then we can do this by masking both and comparing the masked
5838 results. */
5842 {
5856 }
5858 /* There is still another way we can do something: If both pairs of
5859 fields being compared are adjacent, we may be able to make a wider
5860 field containing them both.
5862 Note that we still must mask the lhs/rhs expressions. Furthermore,
5863 the mask must be shifted to account for the shift done by
5864 make_bit_field_ref. */
5869 {
5870 tree type;
5886 /* Convert to the smaller type before masking out unwanted bits. */
5889 {
5891 {
5895 }
5897 {
5901 }
5902 }
5911 }
5914 }
5916 /* Handle the case of comparisons with constants. If there is something in
5917 common between the masks, those bits of the constants must be the same.
5918 If not, the condition is always false. Test for this to avoid generating
5919 incorrect code below. */
5924 {
5926 {
5929 }
5930 else
5931 {
5934 }
5935 }
5937 /* Construct the expression we will return. First get the component
5938 reference we will make. Unless the mask is all ones the width of
5939 that field, perform the mask operation. Then compare with the
5940 merged constant. */
5951 }
5952 \f
5953 /* T is an integer expression that is being multiplied, divided, or taken a
5954 modulus (CODE says which and what kind of divide or modulus) by a
5955 constant C. See if we can eliminate that operation by folding it with
5956 other operations already in T. WIDE_TYPE, if non-null, is a type that
5957 should be used for the computation if wider than our type.
5959 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5960 (X * 2) + (Y * 4). We must, however, be assured that either the original
5961 expression would not overflow or that overflow is undefined for the type
5962 in the language in question.
5964 If we return a non-null expression, it is an equivalent form of the
5965 original computation, but need not be in the original type.
5967 We set *STRICT_OVERFLOW_P to true if the return values depends on
5968 signed overflow being undefined. Otherwise we do not change
5969 *STRICT_OVERFLOW_P. */
5971 static tree
5974 {
5975 /* To avoid exponential search depth, refuse to allow recursion past
5976 three levels. Beyond that (1) it's highly unlikely that we'll find
5977 something interesting and (2) we've probably processed it before
5978 when we built the inner expression. */
5981 tree ret;
5986 depth++;
5988 depth--;
5991 }
5993 static tree
5996 {
6007 /* Don't deal with constants of zero here; they confuse the code below. */
6017 /* Note that we need not handle conditional operations here since fold
6018 already handles those cases. So just do arithmetic here. */
6020 {
6022 /* For a constant, we can always simplify if we are a multiply
6023 or (for divide and modulus) if it is a multiple of our constant. */
6026 {
6029 /* If the multiplication overflowed, we lost information on it.
6030 See PR68142 and PR69845. */
6034 }
6038 /* If op0 is an expression ... */
6044 /* ... and has wrapping overflow, and its type is smaller
6045 than ctype, then we cannot pass through as widening. */
6050 /* ... or this is a truncation (t is narrower than op0),
6051 then we cannot pass through this narrowing. */
6054 /* ... or signedness changes for division or modulus,
6055 then we cannot pass through this conversion. */
6059 /* ... or has undefined overflow while the converted to
6060 type has not, we cannot do the operation in the inner type
6061 as that would introduce undefined overflow. */
6067 /* Pass the constant down and see if we can make a simplification. If
6068 we can, replace this expression with the inner simplification for
6069 possible later conversion to our or some other type. */
6074 code == MULT_EXPR
6076 strict_overflow_p))))
6081 /* If widening the type changes it from signed to unsigned, then we
6082 must avoid building ABS_EXPR itself as unsigned. */
6084 {
6088 {
6091 }
6093 }
6094 /* If the constant is negative, we cannot simplify this. */
6097 /* FALLTHROUGH */
6099 /* For division and modulus, type can't be unsigned, as e.g.
6100 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6101 For signed types, even with wrapping overflow, this is fine. */
6110 /* If widening the type changes the signedness, then we can't perform
6111 this optimization as that changes the result. */
6115 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6121 {
6128 }
6132 /* If the second operand is constant, this is a multiplication
6133 or floor division, by a power of two, so we can treat it that
6134 way unless the multiplier or divisor overflows. Signed
6135 left-shift overflow is implementation-defined rather than
6136 undefined in C90, so do not convert signed left shift into
6137 multiplication. */
6140 /* const_binop may not detect overflow correctly,
6141 so check for it explicitly here. */
6145 size_one_node,
6146 op1)))
6150 ctype,
6152 t1),
6157 /* See if we can eliminate the operation on both sides. If we can, we
6158 can return a new PLUS or MINUS. If we can't, the only remaining
6159 cases where we can do anything are if the second operand is a
6160 constant. */
6166 /* If not multiplication, we can only do this if both operands
6167 are divisible by c. */
6170 {
6175 }
6177 /* If this was a subtraction, negate OP1 and set it to be an addition.
6178 This simplifies the logic below. */
6180 {
6182 /* If OP1 was not easily negatable, the constant may be OP0. */
6184 {
6187 }
6188 }
6193 /* If either OP1 or C are negative, this optimization is not safe for
6194 some of the division and remainder types while for others we need
6195 to change the code. */
6197 {
6205 }
6207 /* If it's a multiply or a division/modulus operation of a multiple
6208 of our constant, do the operation and verify it doesn't overflow. */
6211 {
6214 /* We allow the constant to overflow with wrapping semantics. */
6218 }
6219 else
6222 /* If we have an unsigned type, we cannot widen the operation since it
6223 will change the result if the original computation overflowed. */
6227 /* If we were able to eliminate our operation from the first side,
6228 apply our operation to the second side and reform the PLUS. */
6232 /* The last case is if we are a multiply. In that case, we can
6233 apply the distributive law to commute the multiply and addition
6234 if the multiplication of the constants doesn't overflow
6235 and overflow is defined. With undefined overflow
6236 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6242 op1);
6247 /* We have a special case here if we are doing something like
6248 (C * 8) % 4 since we know that's zero. */
6251 /* If the multiplication can overflow we cannot optimize this. */
6255 {
6258 }
6260 /* ... fall through ... */
6264 /* If we can extract our operation from the LHS, do so and return a
6265 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6266 do something only if the second operand is a constant. */
6280 /* If these are the same operation types, we can associate them
6281 assuming no overflow. */
6283 {
6298 }
6300 /* If these operations "cancel" each other, we have the main
6301 optimizations of this pass, which occur when either constant is a
6302 multiple of the other, in which case we replace this with either an
6303 operation or CODE or TCODE.
6305 If we have an unsigned type, we cannot do this since it will change
6306 the result if the original computation overflowed. */
6313 {
6315 {
6322 }
6324 {
6331 }
6332 }
6337 }
6340 }
6341 \f
6342 /* Return a node which has the indicated constant VALUE (either 0 or
6343 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6344 and is of the indicated TYPE. */
6346 tree
6348 {
6357 else
6359 }
6362 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6363 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6364 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6365 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6366 COND is the first argument to CODE; otherwise (as in the example
6367 given here), it is the second argument. TYPE is the type of the
6368 original expression. Return NULL_TREE if no simplification is
6369 possible. */
6371 static tree
6376 {
6386 {
6390 /* If this operand throws an expression, then it does not make
6391 sense to try to perform a logical or arithmetic operation
6392 involving it. */
6397 }
6400 {
6405 }
6406 else
6407 /* Detect the case of mixing vector and scalar types - bail out. */
6413 /* This transformation is only worthwhile if we don't have to wrap ARG
6414 in a SAVE_EXPR and the operation can be simplified without recursing
6415 on at least one of the branches once its pushed inside the COND_EXPR. */
6424 {
6428 else
6430 }
6432 {
6436 else
6438 }
6440 /* Check that we have simplified at least one of the branches. */
6445 }
6447 \f
6448 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6450 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6451 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6452 ADDEND is the same as X.
6454 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6455 and finite. The problematic cases are when X is zero, and its mode
6456 has signed zeros. In the case of rounding towards -infinity,
6457 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6458 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6460 bool
6462 {
6466 /* Don't allow the fold with -fsignaling-nans. */
6470 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6474 /* In a vector or complex, we would need to check the sign of all zeros. */
6478 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6482 /* The mode has signed zeros, and we have to honor their sign.
6483 In this situation, there is only one case we can return true for.
6484 X - 0 is the same as X unless rounding towards -infinity is
6485 supported. */
6487 }
6489 /* Subroutine of fold() that optimizes comparisons of a division by
6490 a nonzero integer constant against an integer constant, i.e.
6491 X/C1 op C2.
6493 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6494 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6495 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6497 The function returns the constant folded tree if a simplification
6498 can be made, and NULL_TREE otherwise. */
6500 static tree
6503 {
6511 /* We have to do this the hard way to detect unsigned overflow.
6512 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6518 {
6523 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6527 }
6529 {
6533 {
6552 }
6553 }
6554 else
6555 {
6556 /* A negative divisor reverses the relational operators. */
6562 {
6581 }
6582 }
6585 {
6606 {
6609 }
6614 {
6617 }
6622 {
6625 }
6630 {
6633 }
6638 }
6641 }
6644 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6645 equality/inequality test, then return a simplified form of the test
6646 using a sign testing. Otherwise return NULL. TYPE is the desired
6647 result type. */
6649 static tree
6652 tree result_type)
6653 {
6654 /* If this is testing a single bit, we can optimize the test. */
6658 {
6659 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6660 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6664 /* This is only a win if casting to a signed type is cheap,
6665 i.e. when arg00's type is not a partial mode. */
6668 {
6671 result_type,
6674 }
6675 }
6678 }
6680 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6681 equality/inequality test, then return a simplified form of
6682 the test using shifts and logical operations. Otherwise return
6683 NULL. TYPE is the desired result type. */
6685 tree
6688 {
6689 /* If this is testing a single bit, we can optimize the test. */
6693 {
6702 /* First, see if we can fold the single bit test into a sign-bit
6703 test. */
6705 result_type);
6709 /* Otherwise we have (A & C) != 0 where C is a single bit,
6710 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6711 Similarly for (A & C) == 0. */
6713 /* If INNER is a right shift of a constant and it plus BITNUM does
6714 not overflow, adjust BITNUM and INNER. */
6720 {
6723 }
6725 /* If we are going to be able to omit the AND below, we must do our
6726 operations as unsigned. If we must use the AND, we have a choice.
6727 Normally unsigned is faster, but for some machines signed is. */
6745 /* Put the AND last so it can combine with more things. */
6748 /* Make sure to return the proper type. */
6752 }
6754 }
6756 /* Test whether it is preferable two swap two operands, ARG0 and
6757 ARG1, for example because ARG0 is an integer constant and ARG1
6758 isn't. */
6760 bool
6762 {
6776 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6777 for commutative and comparison operators. Ensuring a canonical
6778 form allows the optimizers to find additional redundancies without
6779 having to explicitly check for both orderings. */
6785 /* Put SSA_NAMEs last. */
6791 /* Put variables last. */
6798 }
6801 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6802 means A >= Y && A != MAX, but in this case we know that
6803 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6805 static tree
6807 {
6814 else
6823 {
6826 }
6828 {
6831 }
6832 else
6839 {
6840 /* Convert the pointer types into integer before taking the difference. */
6844 }
6845 else
6852 }
6854 /* Fold a sum or difference of at least one multiplication.
6855 Returns the folded tree or NULL if no simplification could be made. */
6857 static tree
6860 {
6864 /* (A * C) +- (B * C) -> (A+-B) * C.
6865 (A * C) +- A -> A * (C+-1).
6866 We are most concerned about the case where C is a constant,
6867 but other combinations show up during loop reduction. Since
6868 it is not difficult, try all four possibilities. */
6871 {
6874 }
6876 {
6879 }
6880 else
6881 {
6882 /* We cannot generate constant 1 for fract. */
6887 }
6889 {
6892 }
6894 {
6896 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6897 the purpose of this canonicalization. */
6901 {
6904 }
6905 else
6907 }
6908 else
6909 {
6910 /* We cannot generate constant 1 for fract. */
6915 }
6927 /* No identical multiplicands; see if we can find a common
6928 power-of-two factor in non-power-of-two multiplies. This
6929 can help in multi-dimensional array access. */
6932 {
6935 tree maybe_same;
6939 /* Move min of absolute values to int11. */
6941 {
6946 }
6947 else
6951 /* The remainder should not be a constant, otherwise we
6952 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6953 increased the number of multiplications necessary. */
6955 {
6963 }
6964 }
6974 }
6976 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6977 specified by EXPR into the buffer PTR of length LEN bytes.
6978 Return the number of bytes placed in the buffer, or zero
6979 upon failure. */
6981 static int
6983 {
6997 {
6999 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7000 number of bytes. */
7004 {
7011 else
7013 }
7014 else
7019 }
7021 }
7024 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7025 specified by EXPR into the buffer PTR of length LEN bytes.
7026 Return the number of bytes placed in the buffer, or zero
7027 upon failure. */
7029 static int
7031 {
7035 FIXED_VALUE_TYPE value;
7051 }
7054 /* Subroutine of native_encode_expr. Encode the REAL_CST
7055 specified by EXPR into the buffer PTR of length LEN bytes.
7056 Return the number of bytes placed in the buffer, or zero
7057 upon failure. */
7059 static int
7061 {
7067 /* There are always 32 bits in each long, no matter the size of
7068 the hosts long. We handle floating point representations with
7069 up to 192 bits. */
7083 {
7088 {
7095 else
7097 }
7098 else
7099 {
7102 {
7103 /* Reverse bytes within each long, or within the entire float
7104 if it's smaller than a long (for HFmode). */
7107 }
7108 }
7113 }
7115 }
7117 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7118 specified by EXPR into the buffer PTR of length LEN bytes.
7119 Return the number of bytes placed in the buffer, or zero
7120 upon failure. */
7122 static int
7124 {
7126 tree part;
7141 }
7144 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7145 specified by EXPR into the buffer PTR of length LEN bytes.
7146 Return the number of bytes placed in the buffer, or zero
7147 upon failure. */
7149 static int
7151 {
7161 {
7163 {
7166 }
7177 }
7179 }
7182 /* Subroutine of native_encode_expr. Encode the STRING_CST
7183 specified by EXPR into the buffer PTR of length LEN bytes.
7184 Return the number of bytes placed in the buffer, or zero
7185 upon failure. */
7187 static int
7189 {
7191 HOST_WIDE_INT total_bytes;
7205 {
7208 {
7211 }
7214 }
7215 else
7218 }
7221 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7222 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7223 buffer PTR of length LEN bytes. If OFF is not -1 then start
7224 the encoding at byte offset OFF and encode at most LEN bytes.
7225 Return the number of bytes placed in the buffer, or zero upon failure. */
7227 int
7229 {
7230 /* We don't support starting at negative offset and -1 is special. */
7235 {
7256 }
7257 }
7260 /* Subroutine of native_interpret_expr. Interpret the contents of
7261 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7262 If the buffer cannot be interpreted, return NULL_TREE. */
7264 static tree
7266 {
7276 }
7279 /* Subroutine of native_interpret_expr. Interpret the contents of
7280 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7281 If the buffer cannot be interpreted, return NULL_TREE. */
7283 static tree
7285 {
7287 double_int result;
7288 FIXED_VALUE_TYPE fixed_value;
7298 }
7301 /* Subroutine of native_interpret_expr. Interpret the contents of
7302 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7303 If the buffer cannot be interpreted, return NULL_TREE. */
7305 static tree
7307 {
7311 /* There are always 32 bits in each long, no matter the size of
7312 the hosts long. We handle floating point representations with
7313 up to 192 bits. */
7314 REAL_VALUE_TYPE r;
7325 {
7326 /* Both OFFSET and BYTE index within a long;
7327 bitpos indexes the whole float. */
7330 {
7337 else
7339 }
7340 else
7341 {
7344 {
7345 /* Reverse bytes within each long, or within the entire float
7346 if it's smaller than a long (for HFmode). */
7349 }
7350 }
7354 }
7358 }
7361 /* Subroutine of native_interpret_expr. Interpret the contents of
7362 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7363 If the buffer cannot be interpreted, return NULL_TREE. */
7365 static tree
7367 {
7382 }
7385 /* Subroutine of native_interpret_expr. Interpret the contents of
7386 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7387 If the buffer cannot be interpreted, return NULL_TREE. */
7389 static tree
7391 {
7404 {
7409 }
7411 }
7414 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7415 the buffer PTR of length LEN as a constant of type TYPE. For
7416 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7417 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7418 return NULL_TREE. */
7420 tree
7422 {
7424 {
7446 }
7447 }
7449 /* Returns true if we can interpret the contents of a native encoding
7450 as TYPE. */
7452 static bool
7454 {
7456 {
7469 }
7470 }
7472 /* Return true iff a constant of type TYPE is accepted by
7473 native_encode_expr. */
7475 bool
7477 {
7479 {
7489 }
7490 }
7492 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7493 TYPE at compile-time. If we're unable to perform the conversion
7494 return NULL_TREE. */
7496 static tree
7498 {
7499 /* We support up to 512-bit values (for V8DFmode). */
7503 /* Check that the host and target are sane. */
7512 }
7514 /* Build an expression for the address of T. Folds away INDIRECT_REF
7515 to avoid confusing the gimplify process. */
7517 tree
7519 {
7520 /* The size of the object is not relevant when talking about its address. */
7525 {
7530 }
7540 {
7545 }
7546 else
7550 }
7552 /* Build an expression for the address of T. */
7554 tree
7556 {
7560 }
7562 /* Fold a unary expression of code CODE and type TYPE with operand
7563 OP0. Return the folded expression if folding is successful.
7564 Otherwise, return NULL_TREE. */
7566 tree
7568 {
7569 tree tem;
7570 tree arg0;
7578 {
7581 {
7582 /* Don't use STRIP_NOPS, because signedness of argument type
7583 matters. */
7585 }
7586 else
7587 {
7588 /* Strip any conversions that don't change the mode. This
7589 is safe for every expression, except for a comparison
7590 expression because its signedness is derived from its
7591 operands.
7593 Note that this is done as an internal manipulation within
7594 the constant folder, in order to find the simplest
7595 representation of the arguments so that their form can be
7596 studied. In any cases, the appropriate type conversions
7597 should be put back in the tree that will get out of the
7598 constant folder. */
7600 }
7603 {
7606 {
7610 }
7611 }
7612 }
7619 {
7626 {
7640 /* If this was a conversion, and all we did was to move into
7641 inside the COND_EXPR, bring it back out. But leave it if
7642 it is a conversion from integer to integer and the
7643 result precision is no wider than a word since such a
7644 conversion is cheap and may be optimized away by combine,
7645 while it couldn't if it were outside the COND_EXPR. Then return
7646 so we don't get into an infinite recursion loop taking the
7647 conversion out and then back in. */
7659 && (INTEGRAL_TYPE_P
7672 }
7673 }
7676 {
7682 CASE_CONVERT:
7686 {
7687 /* If we have (type) (a CMP b) and type is an integral type, return
7688 new expression involving the new type. Canonicalize
7689 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7690 non-integral type.
7691 Do not fold the result as that would not simplify further, also
7692 folding again results in recursions. */
7702 }
7704 /* Handle (T *)&A.B.C for A being of type T and B and C
7705 living at offset zero. This occurs frequently in
7706 C++ upcasting and then accessing the base. */
7710 {
7712 tree offset;
7713 machine_mode mode;
7715 tree base
7719 /* If the reference was to a (constant) zero offset, we can use
7720 the address of the base if it has the same base type
7721 as the result type and the pointer type is unqualified. */
7728 }
7732 /* Detect assigning a bitfield. */
7734 && DECL_BIT_FIELD
7736 {
7737 /* Don't leave an assignment inside a conversion
7738 unless assigning a bitfield. */
7740 /* First do the assignment, then return converted constant. */
7745 }
7747 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7748 constants (if x has signed type, the sign bit cannot be set
7749 in c). This folds extension into the BIT_AND_EXPR.
7750 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7751 very likely don't have maximal range for their precision and this
7752 transformation effectively doesn't preserve non-maximal ranges. */
7756 {
7767 <= HOST_BITS_PER_WIDE_INT
7769 {
7773 cst &= HOST_WIDE_INT_M1U
7777 && !flag_syntax_only
7780 {
7784 }
7785 }
7787 {
7792 }
7793 }
7795 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7796 cast (T1)X will fold away. We assume that this happens when X itself
7797 is a cast. */
7801 {
7805 return fold_build_pointer_plus_loc
7807 }
7809 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7810 of the same precision, and X is an integer type not narrower than
7811 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7817 {
7823 }
7825 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7826 type of X and Y (integer types only). */
7831 {
7832 /* Be careful not to introduce new overflows. */
7833 tree mult_type;
7836 else
7840 {
7847 }
7848 }
7854 {
7861 }
7872 /* Convert fabs((double)float) into (double)fabsf(float). */
7875 {
7881 targ0));
7882 }
7886 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7905 /* Note that the operand of this must be an int
7906 and its values must be 0 or 1.
7907 ("true" is a fixed value perhaps depending on the language,
7908 but we don't handle values other than 1 correctly yet.) */
7915 /* Fold *&X to X if X is an lvalue. */
7917 {
7924 }
7930 }
7933 /* If the operation was a conversion do _not_ mark a resulting constant
7934 with TREE_OVERFLOW if the original constant was not. These conversions
7935 have implementation defined behavior and retaining the TREE_OVERFLOW
7936 flag here would confuse later passes such as VRP. */
7937 tree
7940 {
7949 }
7951 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7952 operands OP0 and OP1. LOC is the location of the resulting expression.
7953 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7954 Return the folded expression if folding is successful. Otherwise,
7955 return NULL_TREE. */
7956 static tree
7959 {
7960 tree tem;
7962 /* We only do these simplifications if we are optimizing. */
7966 /* Check for things like (A || B) && (A || C). We can convert this
7967 to A || (B && C). Note that either operator can be any of the four
7968 truth and/or operations and the transformation will still be
7969 valid. Also note that we only care about order for the
7970 ANDIF and ORIF operators. If B contains side effects, this
7971 might change the truth-value of A. */
7978 {
7998 /* This case if tricky because we must either have commutative
7999 operators or else A10 must not have side-effects. */
8005 a01);
8006 }
8008 /* See if we can build a range comparison. */
8014 {
8018 }
8022 {
8026 }
8028 /* Check for the possibility of merging component references. If our
8029 lhs is another similar operation, try to merge its rhs with our
8030 rhs. Then try to merge our lhs and rhs. */
8044 {
8051 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8052 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8053 We don't want to pack more than two leafs to a non-IF AND/OR
8054 expression.
8055 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8056 equal to IF-CODE, then we don't want to add right-hand operand.
8057 If the inner right-hand side of left-hand operand has
8058 side-effects, or isn't simple, then we can't add to it,
8059 as otherwise we might destroy if-sequence. */
8062 /* Needed for sequence points to handle trappings, and
8063 side-effects. */
8065 {
8067 arg1);
8069 tem);
8070 }
8071 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8072 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8075 /* Needed for sequence points to handle trappings, and
8076 side-effects. */
8078 {
8083 }
8084 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8085 into (A OR B).
8086 For sequence point consistancy, we need to check for trapping,
8087 and side-effects. */
8091 }
8094 }
8096 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8097 by changing CODE to reduce the magnitude of constants involved in
8098 ARG0 of the comparison.
8099 Returns a canonicalized comparison tree if a simplification was
8100 possible, otherwise returns NULL_TREE.
8101 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8102 valid if signed overflow is undefined. */
8104 static tree
8108 {
8113 /* Match A +- CST code arg1. We can change this only if overflow
8114 is undefined. */
8117 /* In principle pointers also have undefined overflow behavior,
8118 but that causes problems elsewhere. */
8125 /* Identify the constant in arg0 and its sign. */
8129 /* Overflowed constants and zero will cause problems. */
8134 /* See if we can reduce the magnitude of the constant in
8135 arg0 by changing the comparison code. */
8136 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8140 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8144 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8148 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8152 else
8156 /* Now build the constant reduced in magnitude. But not if that
8157 would produce one outside of its types range. */
8173 }
8175 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8176 overflow further. Try to decrease the magnitude of constants involved
8177 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8178 and put sole constants at the second argument position.
8179 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8181 static tree
8184 {
8185 tree t;
8190 /* Try canonicalization by simplifying arg0. */
8195 {
8199 }
8201 /* Try canonicalization by simplifying arg1 using the swapped
8202 comparison. */
8210 }
8212 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8213 space. This is used to avoid issuing overflow warnings for
8214 expressions like &p->x which can not wrap. */
8216 static bool
8218 {
8225 wide_int wi_offset;
8231 else
8247 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8248 array. */
8250 {
8251 HOST_WIDE_INT base_size;
8256 }
8259 }
8261 /* Return a positive integer when the symbol DECL is known to have
8262 a nonzero address, zero when it's known not to (e.g., it's a weak
8263 symbol), and a negative integer when the symbol is not yet in the
8264 symbol table and so whether or not its address is zero is unknown. */
8265 static int
8267 {
8273 }
8275 /* Subroutine of fold_binary. This routine performs all of the
8276 transformations that are common to the equality/inequality
8277 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8278 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8279 fold_binary should call fold_binary. Fold a comparison with
8280 tree code CODE and type TYPE with operands OP0 and OP1. Return
8281 the folded comparison or NULL_TREE. */
8283 static tree
8286 {
8296 /* For comparisons of pointers we can decompose it to a compile time
8297 comparison of the base objects and the offsets into the object.
8298 This requires at least one operand being an ADDR_EXPR or a
8299 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8305 {
8308 machine_mode mode;
8312 /* Get base and offset for the access. Strip ADDR_EXPR for
8313 get_inner_reference, but put it back by stripping INDIRECT_REF
8314 off the base object if possible. indirect_baseN will be true
8315 if baseN is not an address but refers to the object itself. */
8318 {
8319 base0
8325 else
8327 }
8329 {
8333 {
8334 base0
8340 else
8342 }
8345 else
8349 {
8355 {
8358 }
8359 }
8360 }
8364 {
8365 base1
8371 else
8373 }
8375 {
8379 {
8380 base1
8386 else
8388 }
8391 else
8395 {
8401 {
8404 }
8405 }
8406 }
8408 /* If we have equivalent bases we might be able to simplify. */
8412 {
8413 /* We can fold this expression to a constant if the non-constant
8414 offset parts are equal. */
8418 && (equality_code
8419 || (indirect_base0
8423 {
8429 "occur when comparing P +- C1 with "
8431 WARN_STRICT_OVERFLOW_CONDITIONAL);
8434 {
8448 }
8449 }
8450 /* We can simplify the comparison to a comparison of the variable
8451 offset parts if the constant offset parts are equal.
8452 Be careful to use signed sizetype here because otherwise we
8453 mess with array offsets in the wrong way. This is possible
8454 because pointer arithmetic is restricted to retain within an
8455 object and overflow on pointer differences is undefined as of
8456 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8458 && (equality_code
8459 || (indirect_base0
8462 {
8463 /* By converting to signed sizetype we cover middle-end pointer
8464 arithmetic which operates on unsigned pointer types of size
8465 type size and ARRAY_REF offsets which are properly sign or
8466 zero extended from their type in case it is narrower than
8467 sizetype. */
8470 else
8474 else
8481 "occur when comparing P +- C1 with "
8483 WARN_STRICT_OVERFLOW_COMPARISON);
8486 }
8487 }
8488 /* For equal offsets we can simplify to a comparison of the
8489 base addresses. */
8491 && (indirect_base0
8493 && (indirect_base1
8498 {
8504 }
8505 /* Comparison between an ordinary (non-weak) symbol and a null
8506 pointer can be eliminated since such symbols must have a non
8507 null address. In C, relational expressions between pointers
8508 to objects and null pointers are undefined. The results
8509 below follow the C++ rules with the additional property that
8510 every object pointer compares greater than a null pointer.
8511 */
8514 /* Avoid folding references to struct members at offset 0 to
8515 prevent tests like '&ptr->firstmember == 0' from getting
8516 eliminated. When ptr is null, although the -> expression
8517 is strictly speaking invalid, GCC retains it as a matter
8518 of QoI. See PR c/44555. */
8520 /* The caller guarantees that when one of the arguments is
8521 constant (i.e., null in this case) it is second. */
8523 {
8525 {
8536 }
8537 }
8538 }
8540 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8541 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8542 the resulting offset is smaller in absolute value than the
8543 original one and has the same sign. */
8552 {
8557 tree cst;
8559 "occur when combining constants around "
8562 /* Put the constant on the side where it doesn't overflow and is
8563 of lower absolute value and of same sign than before. */
8570 {
8573 variable1,
8577 }
8585 {
8591 variable2);
8592 }
8593 }
8599 /* If we are comparing an expression that just has comparisons
8600 of two integer values, arithmetic expressions of those comparisons,
8601 and constants, we can simplify it. There are only three cases
8602 to check: the two values can either be equal, the first can be
8603 greater, or the second can be greater. Fold the expression for
8604 those three values. Since each value must be 0 or 1, we have
8605 eight possibilities, each of which corresponds to the constant 0
8606 or 1 or one of the six possible comparisons.
8608 This handles common cases like (a > b) == 0 but also handles
8609 expressions like ((x > y) - (y > x)) > 0, which supposedly
8610 occur in macroized code. */
8613 {
8618 /* Don't handle degenerate cases here; they should already
8619 have been handled anyway. */
8628 {
8632 /* We can't just pass T to eval_subst in case cval1 or cval2
8633 was the same as ARG1. */
8635 tree high_result
8639 arg1);
8640 tree equal_result
8644 arg1);
8645 tree low_result
8649 arg1);
8651 /* All three of these results should be 0 or 1. Confirm they are.
8652 Then use those values to select the proper code to use. */
8657 {
8658 /* Make a 3-bit mask with the high-order bit being the
8659 value for `>', the next for '=', and the low for '<'. */
8663 {
8665 /* Always false. */
8686 /* Always true. */
8688 }
8691 {
8695 }
8697 }
8698 }
8699 }
8701 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8702 into a single range test. */
8710 {
8714 }
8717 }
8720 /* Subroutine of fold_binary. Optimize complex multiplications of the
8721 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8722 argument EXPR represents the expression "z" of type TYPE. */
8724 static tree
8726 {
8731 {
8734 }
8736 {
8739 }
8740 else
8741 {
8745 }
8754 }
8757 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8758 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8760 static bool
8762 {
8766 {
8769 }
8771 {
8777 else
8779 }
8780 else
8786 }
8788 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8789 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8790 NULL_TREE otherwise. */
8792 static tree
8794 {
8811 {
8815 }
8818 {
8824 }
8825 else
8827 }
8829 /* Try to fold a pointer difference of type TYPE two address expressions of
8830 array references AREF0 and AREF1 using location LOC. Return a
8831 simplified expression for the difference or NULL_TREE. */
8833 static tree
8836 {
8841 /* If the bases are array references as well, recurse. If the bases
8842 are pointer indirections compute the difference of the pointers.
8843 If the bases are equal, we are set. */
8846 && (base_offset
8850 && (base_offset
8856 {
8862 base_offset,
8865 }
8867 }
8869 /* If the real or vector real constant CST of type TYPE has an exact
8870 inverse, return it, else return NULL. */
8872 tree
8874 {
8875 REAL_VALUE_TYPE r;
8877 machine_mode mode;
8881 {
8897 {
8902 }
8908 }
8909 }
8911 /* Mask out the tz least significant bits of X of type TYPE where
8912 tz is the number of trailing zeroes in Y. */
8913 static wide_int
8915 {
8920 }
8922 /* Return true when T is an address and is known to be nonzero.
8923 For floating point we further ensure that T is not denormal.
8924 Similar logic is present in nonzero_address in rtlanal.h.
8926 If the return value is based on the assumption that signed overflow
8927 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8928 change *STRICT_OVERFLOW_P. */
8930 static bool
8932 {
8936 /* Doing something useful for floating point would need more work. */
8942 {
8945 strict_overflow_p);
8951 strict_overflow_p);
8959 }
8962 {
8965 strict_overflow_p);
8973 strict_overflow_p);
8988 strict_overflow_p);
8992 strict_overflow_p);
8995 {
9007 }
9011 }
9013 }
9015 /* Return true when T is an address and is known to be nonzero.
9016 Handle warnings about undefined signed overflow. */
9018 static bool
9020 {
9027 "determining that expression is always "
9029 WARN_STRICT_OVERFLOW_MISC);
9031 }
9033 /* Return true if T is known not to be equal to an integer W. */
9035 bool
9037 {
9039 value_range_type rtype;
9041 {
9050 {
9055 }
9060 /* If T has some known zero bits and W has any of those bits set,
9061 then T is known not to be equal to W. */
9069 }
9070 }
9072 /* Fold a binary expression of code CODE and type TYPE with operands
9073 OP0 and OP1. LOC is the location of the resulting expression.
9074 Return the folded expression if folding is successful. Otherwise,
9075 return NULL_TREE. */
9077 tree
9080 {
9095 /* Strip any conversions that don't change the mode. This is
9096 safe for every expression, except for a comparison expression
9097 because its signedness is derived from its operands. So, in
9098 the latter case, only strip conversions that don't change the
9099 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9100 preserved.
9102 Note that this is done as an internal manipulation within the
9103 constant folder, in order to find the simplest representation
9104 of the arguments so that their form can be studied. In any
9105 cases, the appropriate type conversions should be put back in
9106 the tree that will get out of the constant folder. */
9109 {
9112 }
9113 else
9114 {
9117 }
9119 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9120 constant but we can't do arithmetic on them. */
9122 {
9125 {
9129 }
9130 }
9132 /* If this is a commutative operation, and ARG0 is a constant, move it
9133 to ARG1 to reduce the number of tests below. */
9138 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9139 to ARG1 to reduce the number of tests below. */
9148 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9150 First check for cases where an arithmetic operation is applied to a
9151 compound, conditional, or comparison operation. Push the arithmetic
9152 operation inside the compound or conditional to see if any folding
9153 can then be done. Convert comparison to conditional for this purpose.
9154 The also optimizes non-constant cases that used to be done in
9155 expand_expr.
9157 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9158 one of the operands is a comparison and the other is a comparison, a
9159 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9160 code below would make the expression more complex. Change it to a
9161 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9162 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9175 {
9179 boolean_type_node,
9187 }
9191 {
9193 {
9198 tem);
9199 }
9201 {
9206 tem);
9207 }
9212 {
9218 }
9223 {
9229 }
9230 }
9233 {
9235 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9238 {
9244 }
9246 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9249 {
9250 tree base;
9251 HOST_WIDE_INT coffset;
9260 }
9265 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9271 arg1),
9273 arg0)));
9279 {
9280 /* X + (X / CST) * -CST is X % CST. */
9285 {
9294 cst0));
9295 }
9296 }
9298 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9299 one. Make sure the type is not saturating and has the signedness of
9300 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9301 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9308 {
9312 }
9315 {
9316 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9317 (plus (plus (mult) (mult)) (foo)) so that we can
9318 take advantage of the factoring cases below. */
9327 {
9333 else
9346 parg0),
9348 marg)),
9352 return
9358 parg1)));
9359 }
9360 }
9361 else
9362 {
9363 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9364 to __complex__ ( x, y ). This is not the same for SNaNs or
9365 if signed zeros are involved. */
9369 {
9376 {
9380 {
9386 }
9388 {
9394 }
9395 }
9396 }
9404 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9405 We associate floats only if the user has specified
9406 -fassociative-math. */
9410 {
9415 {
9416 tree tree0;
9419 }
9420 }
9421 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9422 We associate floats only if the user has specified
9423 -fassociative-math. */
9427 {
9432 {
9433 tree tree0;
9436 }
9437 }
9438 }
9440 bit_rotate:
9441 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9442 is a rotate of A by C1 bits. */
9443 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9444 is a rotate of A by B bits. */
9445 {
9447 tree rtype;
9456 /* Only create rotates in complete modes. Other cases are not
9457 expanded properly. */
9460 {
9474 {
9478 code0 == LSHIFT_EXPR
9482 }
9484 {
9492 element_precision
9496 return
9499 ? LROTATE_EXPR
9504 }
9506 {
9514 element_precision
9518 return fold_convert_loc
9521 ? LROTATE_EXPR
9525 }
9526 }
9527 }
9529 associate:
9530 /* In most languages, can't associate operations on floats through
9531 parentheses. Rather than remember where the parentheses were, we
9532 don't associate floats at all, unless the user has specified
9533 -fassociative-math.
9534 And, we need to make sure type is not saturating. */
9538 {
9544 /* Split both trees into variables, constants, and literals. Then
9545 associate each group together, the constants with literals,
9546 then the result with variables. This increases the chances of
9547 literals being recombined later and of generating relocatable
9548 expressions for the sum of a constant and literal. */
9554 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9558 /* With undefined overflow prefer doing association in a type
9559 which wraps on overflow, if that is one of the operand types. */
9562 {
9570 }
9572 /* With undefined overflow we can only associate constants with one
9573 variable, and constants whose association doesn't overflow. */
9576 {
9578 {
9584 {
9587 }
9594 {
9597 }
9603 /* The only case we can still associate with two variables
9604 is if they cancel out. */
9608 }
9609 }
9611 /* Only do something if we found more than two objects. Otherwise,
9612 nothing has changed and we risk infinite recursion. */
9618 {
9630 /* Preserve the MINUS_EXPR if the negative part of the literal is
9631 greater than the positive part. Otherwise, the multiplicative
9632 folding code (i.e extract_muldiv) may be fooled in case
9633 unsigned constants are subtracted, like in the following
9634 example: ((X*2 + 4) - 8U)/2. */
9636 {
9640 {
9644 }
9645 else
9646 {
9650 }
9651 }
9653 /* Don't introduce overflows through reassociation. */
9660 {
9662 return
9666 else
9667 {
9670 return
9674 }
9675 }
9678 return
9681 }
9682 }
9687 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9695 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9696 __complex__ ( x, -y ). This is not the same for SNaNs or if
9697 signed zeros are involved. */
9701 {
9708 {
9712 {
9714 arg1r ? arg1r
9719 }
9721 {
9725 arg1i ? arg1i
9728 }
9729 }
9730 }
9732 /* A - B -> A + (-B) if B is easily negatable. */
9736 /* Avoid this transformation if B is a positive REAL_CST. */
9744 /* Fold &a[i] - &a[j] to i-j. */
9749 {
9755 }
9758 && flag_unsafe_math_optimizations
9764 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9765 one. Make sure the type is not saturating and has the signedness of
9766 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9767 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9774 {
9778 }
9784 {
9785 /* Transform x * -C into -x * C if x is easily negatable. */
9799 {
9802 "occur when simplifying "
9804 WARN_STRICT_OVERFLOW_MISC);
9806 }
9808 /* Optimize z * conj(z) for integer complex numbers. */
9815 }
9816 else
9817 {
9818 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9819 This is not the same for NaNs or if signed zeros are
9820 involved. */
9826 {
9829 return
9835 return
9840 }
9842 /* Optimize z * conj(z) for floating point complex numbers.
9843 Guarded by flag_unsafe_math_optimizations as non-finite
9844 imaginary components don't produce scalar results. */
9853 }
9857 /* Canonicalize (X & C1) | C2. */
9861 {
9866 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9874 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9879 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9880 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9881 mode which allows further optimizations. */
9886 {
9890 {
9893 }
9894 }
9901 c3)),
9902 arg1);
9903 }
9905 /* See if this can be simplified into a rotate first. If that
9906 is unsuccessful continue in the association code. */
9910 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9918 /* See if this can be simplified into a rotate first. If that
9919 is unsuccessful continue in the association code. */
9923 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9928 {
9929 tree tem2;
9936 }
9937 /* Fold ~X & 1 as (X & 1) == 0. */
9941 {
9942 tree tem2;
9949 }
9950 /* Fold !X & 1 as X == 0. */
9953 {
9957 }
9959 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9960 multiple of 1 << CST. */
9962 {
9969 }
9971 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
9972 bits from CST2. */
9976 {
9984 {
9985 /* Avoid the transform if arg1 is a mask of some
9986 mode which allows further optimizations. */
9993 }
9994 }
9996 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
9997 ((A & N) + B) & M -> (A + B) & M
9998 Similarly if (N & M) == 0,
9999 ((A | N) + B) & M -> (A + B) & M
10000 and for - instead of + (or unary - instead of +)
10001 and/or ^ instead of |.
10002 If B is constant and (B & M) == 0, fold into A & M. */
10004 {
10013 {
10016 wide_int cst0;
10018 /* Now we know that arg0 is (C + D) or (C - D) or
10019 -C and arg1 (M) is == (1LL << cst) - 1.
10020 Store C into PMOP[0] and D into PMOP[1]. */
10024 {
10027 }
10034 {
10044 {
10047 }
10050 /* If C or D is of the form (A & N) where
10051 (N & M) == M, or of the form (A | N) or
10052 (A ^ N) where (N & M) == 0, replace it with A. */
10056 /* If C or D is a N where (N & M) == 0, it can be
10057 omitted (assumed 0). */
10065 }
10067 /* Only build anything new if we optimized one or both arguments
10068 above. */
10072 {
10075 {
10076 /* Perform the operations in a type that has defined
10077 overflow behavior. */
10083 }
10088 {
10096 else
10098 }
10101 else
10104 /* TEM is now the new binary +, - or unary - replacement. */
10108 }
10109 }
10110 }
10112 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10115 {
10120 return
10122 }
10127 /* Don't touch a floating-point divide by zero unless the mode
10128 of the constant can represent infinity. */
10134 /* (-A) / (-B) -> A / B */
10146 /* Fall through */
10149 /* Simplify A / (B << N) where A and B are positive and B is
10150 a power of 2, to A >> (N + log2(B)). */
10155 {
10158 {
10166 WARN_STRICT_OVERFLOW_MISC);
10172 }
10173 }
10175 /* Fall through */
10183 /* Convert -A / -B to A / B when the type is signed and overflow is
10184 undefined. */
10188 {
10191 "when distributing negation across "
10193 WARN_STRICT_OVERFLOW_MISC);
10198 }
10202 {
10205 "when distributing negation across "
10207 WARN_STRICT_OVERFLOW_MISC);
10212 }
10214 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10215 operation, EXACT_DIV_EXPR.
10217 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10218 At one time others generated faster code, it's not clear if they do
10219 after the last round to changes to the DIV code in expmed.c. */
10230 {
10234 WARN_STRICT_OVERFLOW_MISC);
10236 }
10248 {
10252 WARN_STRICT_OVERFLOW_MISC);
10254 }
10262 /* Since negative shift count is not well-defined,
10263 don't try to compute it in the compiler. */
10269 /* If we have a rotate of a bit operation with the rotate count and
10270 the second operand of the bit operation both constant,
10271 permute the two operations. */
10277 {
10285 }
10287 /* Two consecutive rotates adding up to the some integer
10288 multiple of the precision of the type can be ignored. */
10303 /* Note that the operands of this must be ints
10304 and their values must be 0 or 1.
10305 ("true" is a fixed value perhaps depending on the language.) */
10306 /* If first arg is constant zero, return it. */
10309 /* FALLTHRU */
10311 /* If either arg is constant true, drop it. */
10315 /* Preserve sequence points. */
10318 /* If second arg is constant zero, result is zero, but first arg
10319 must be evaluated. */
10322 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10323 case will be handled here. */
10327 /* !X && X is always false. */
10331 /* X && !X is always false. */
10336 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10337 means A >= Y && A != MAX, but in this case we know that
10338 A < X <= MAX. */
10342 {
10350 }
10359 /* Note that the operands of this must be ints
10360 and their values must be 0 or true.
10361 ("true" is a fixed value perhaps depending on the language.) */
10362 /* If first arg is constant true, return it. */
10365 /* FALLTHRU */
10367 /* If either arg is constant zero, drop it. */
10371 /* Preserve sequence points. */
10374 /* If second arg is constant true, result is true, but we must
10375 evaluate first arg. */
10378 /* Likewise for first arg, but note this only occurs here for
10379 TRUTH_OR_EXPR. */
10383 /* !X || X is always true. */
10387 /* X || !X is always true. */
10392 /* (X && !Y) || (!X && Y) is X ^ Y */
10395 {
10412 }
10421 /* If the second arg is constant zero, drop it. */
10424 /* If the second arg is constant true, this is a logical inversion. */
10426 {
10429 }
10430 /* Identical arguments cancel to zero. */
10434 /* !X ^ X is always true. */
10439 /* X ^ !X is always true. */
10455 /* bool_var != 1 becomes !bool_var. */
10462 /* bool_var == 0 becomes !bool_var. */
10469 /* !exp != 0 becomes !exp */
10474 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10483 {
10489 }
10491 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10500 {
10506 }
10508 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10516 code == NE_EXPR
10520 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10528 code == NE_EXPR
10532 /* If this is an EQ or NE comparison with zero and ARG0 is
10533 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10534 two operations, but the latter can be done in one less insn
10535 on machines that have only two-operand insns or on which a
10536 constant cannot be the first operand. */
10539 {
10544 {
10551 arg1);
10552 }
10555 {
10562 arg1);
10563 }
10564 }
10566 /* If this is an NE or EQ comparison of zero against the result of a
10567 signed MOD operation whose second operand is a power of 2, make
10568 the MOD operation unsigned since it is simpler and equivalent. */
10576 {
10586 }
10588 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10589 C1 is a valid shift constant, and C2 is a power of two, i.e.
10590 a single bit. */
10594 == INTEGER_CST
10597 {
10602 /* Check for a valid shift count. */
10604 {
10608 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10609 can be rewritten as (X & (C2 << C1)) != 0. */
10611 {
10616 }
10617 /* Otherwise, for signed (arithmetic) shifts,
10618 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10619 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10623 /* Otherwise, of unsigned (logical) shifts,
10624 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10625 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10626 else
10630 arg000);
10631 }
10632 }
10634 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10635 Similarly for NE_EXPR. */
10639 {
10643 tree dandnotc
10646 notc);
10650 }
10652 /* If this is a comparison of a field, we may be able to simplify it. */
10655 /* Handle the constant case even without -O
10656 to make sure the warnings are given. */
10658 {
10662 }
10664 /* Optimize comparisons of strlen vs zero to a compare of the
10665 first character of the string vs zero. To wit,
10666 strlen(ptr) == 0 => *ptr == 0
10667 strlen(ptr) != 0 => *ptr != 0
10668 Other cases should reduce to one of these two (or a constant)
10669 due to the return value of strlen being unsigned. */
10672 {
10680 {
10685 }
10686 }
10688 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10689 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10693 {
10698 {
10700 {
10703 }
10706 }
10707 }
10709 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10710 (X & C) == 0 when C is a single bit. */
10715 {
10722 arg1));
10723 }
10725 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10726 constant C is a power of two, i.e. a single bit. */
10733 {
10737 }
10739 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10740 when is C is a power of two, i.e. a single bit. */
10747 {
10753 }
10757 {
10760 }
10762 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10765 {
10778 arg01),
10787 arg01),
10796 arg00),
10805 arg00),
10807 }
10811 {
10818 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10819 operand_equal_p guarantees no side-effects so we don't need
10820 to use omit_one_operand on Z. */
10824 arg10));
10828 arg11));
10832 arg10));
10836 arg11));
10838 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10841 {
10847 }
10848 }
10850 /* Attempt to simplify equality/inequality comparisons of complex
10851 values. Only lower the comparison if the result is known or
10852 can be simplified to a single scalar comparison. */
10857 {
10862 {
10865 }
10866 else
10867 {
10870 }
10873 {
10876 }
10877 else
10878 {
10881 }
10885 {
10887 {
10892 }
10893 else
10894 {
10899 }
10900 }
10904 {
10906 {
10911 }
10912 else
10913 {
10918 }
10919 }
10920 }
10932 /* Transform comparisons of the form X +- C CMP X. */
10939 {
10946 else
10949 /* (X - c) > X becomes false. */
10953 {
10957 "occur when assuming that (X - c) > X "
10959 WARN_STRICT_OVERFLOW_ALL);
10961 }
10963 /* Likewise (X + c) < X becomes false. */
10967 {
10971 "occur when assuming that "
10973 WARN_STRICT_OVERFLOW_ALL);
10975 }
10977 /* Convert (X - c) <= X to true. */
10982 {
10986 "occur when assuming that "
10988 WARN_STRICT_OVERFLOW_ALL);
10990 }
10992 /* Convert (X + c) >= X to true. */
10997 {
11001 "occur when assuming that "
11003 WARN_STRICT_OVERFLOW_ALL);
11005 }
11008 {
11009 /* Convert X + c > X and X - c < X to true for integers. */
11013 {
11016 "not occur when assuming that "
11018 WARN_STRICT_OVERFLOW_ALL);
11020 }
11025 {
11028 "not occur when assuming that "
11030 WARN_STRICT_OVERFLOW_ALL);
11032 }
11034 /* Convert X + c <= X and X - c >= X to false for integers. */
11038 {
11041 "not occur when assuming that "
11043 WARN_STRICT_OVERFLOW_ALL);
11045 }
11050 {
11053 "not occur when assuming that "
11055 WARN_STRICT_OVERFLOW_ALL);
11057 }
11058 }
11059 }
11061 /* If we are comparing an ABS_EXPR with a constant, we can
11062 convert all the cases into explicit comparisons, but they may
11063 well not be faster than doing the ABS and one comparison.
11064 But ABS (X) <= C is a range comparison, which becomes a subtraction
11065 and a comparison, and is probably faster. */
11079 /* Convert ABS_EXPR<x> >= 0 to true. */
11086 {
11089 "when simplifying comparison of "
11091 WARN_STRICT_OVERFLOW_CONDITIONAL);
11094 arg0);
11095 }
11097 /* Convert ABS_EXPR<x> < 0 to false. */
11102 {
11105 "when simplifying comparison of "
11107 WARN_STRICT_OVERFLOW_CONDITIONAL);
11110 arg0);
11111 }
11113 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11114 and similarly for >= into !=. */
11124 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11125 otherwise Y might be >= # of bits in X's type and thus e.g.
11126 (unsigned char) (1 << Y) for Y 15 might be 0.
11127 If the cast is widening, then 1 << Y should have unsigned type,
11128 otherwise if Y is number of bits in the signed shift type minus 1,
11129 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11130 31 might be 0xffffffff80000000. */
11141 {
11147 }
11159 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11160 {
11172 }
11177 /* When pedantic, a compound expression can be neither an lvalue
11178 nor an integer constant expression. */
11181 /* Don't let (0, 0) be null pointer constant. */
11187 /* An ASSERT_EXPR should never be passed to fold_binary. */
11193 }
11195 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11196 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11197 of GOTO_EXPR. */
11199 static tree
11201 {
11203 {
11210 /* fall through */
11214 }
11215 }
11217 /* Return whether the sub-tree ST contains a label which is accessible from
11218 outside the sub-tree. */
11220 static bool
11222 {
11223 return
11225 }
11227 /* Fold a ternary expression of code CODE and type TYPE with operands
11228 OP0, OP1, and OP2. Return the folded expression if folding is
11229 successful. Otherwise, return NULL_TREE. */
11231 tree
11234 {
11235 tree tem;
11242 /* If this is a commutative operation, and OP0 is a constant, move it
11243 to OP1 to reduce the number of tests below. */
11252 /* Strip any conversions that don't change the mode. This is safe
11253 for every expression, except for a comparison expression because
11254 its signedness is derived from its operands. So, in the latter
11255 case, only strip conversions that don't change the signedness.
11257 Note that this is done as an internal manipulation within the
11258 constant folder, in order to find the simplest representation of
11259 the arguments so that their form can be studied. In any cases,
11260 the appropriate type conversions should be put back in the tree
11261 that will get out of the constant folder. */
11263 {
11266 }
11269 {
11272 }
11275 {
11278 }
11281 {
11285 {
11291 }
11296 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11297 so all simple results must be passed through pedantic_non_lvalue. */
11299 {
11302 /* Only optimize constant conditions when the selected branch
11303 has the same type as the COND_EXPR. This avoids optimizing
11304 away "c ? x : throw", where the throw has a void type.
11305 Avoid throwing away that operand which contains label. */
11312 }
11314 {
11319 {
11324 {
11332 }
11336 }
11337 }
11339 /* If we have A op B ? A : C, we may be able to convert this to a
11340 simpler expression, depending on the operation and the values
11341 of B and C. Signed zeros prevent all of these transformations,
11342 for reasons given above each one.
11344 Also try swapping the arguments and inverting the conditional. */
11349 {
11353 }
11357 op2,
11360 {
11364 {
11368 }
11369 }
11371 /* If the second operand is simpler than the third, swap them
11372 since that produces better jump optimization results. */
11375 {
11377 /* See if this can be inverted. If it can't, possibly because
11378 it was a floating-point inequality comparison, don't do
11379 anything. */
11383 }
11385 /* Convert A ? 1 : 0 to simply A. */
11390 /* If we try to convert OP0 to our type, the
11391 call to fold will try to move the conversion inside
11392 a COND, which will recurse. In that case, the COND_EXPR
11393 is probably the best choice, so leave it alone. */
11397 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11398 over COND_EXPR in cases such as floating point comparisons. */
11407 arg0)));
11409 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11414 {
11415 /* sign_bit_p looks through both zero and sign extensions,
11416 but for this optimization only sign extensions are
11417 usable. */
11420 {
11423 {
11426 }
11428 }
11429 /* sign_bit_p only checks ARG1 bits within A's precision.
11430 If <sign bit of A> has wider type than A, bits outside
11431 of A's precision in <sign bit of A> need to be checked.
11432 If they are all 0, this optimization needs to be done
11433 in unsigned A's type, if they are all 1 in signed A's type,
11434 otherwise this can't be done. */
11440 {
11442 tree tem_type;
11455 {
11458 }
11460 {
11463 }
11464 else
11466 }
11469 return
11475 arg1)));
11476 }
11478 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11479 already handled above. */
11484 {
11493 }
11495 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11496 is probably obsolete because the first operand should be a
11497 truth value (that's why we have the two cases above), but let's
11498 leave it in until we can confirm this for all front-ends. */
11510 /* Disable the transformations below for vectors, since
11511 fold_binary_op_with_conditional_arg may undo them immediately,
11512 yielding an infinite loop. */
11516 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11525 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11530 {
11532 /* Only perform transformation if ARG0 is easily inverted. */
11536 ? BIT_IOR_EXPR
11539 arg1);
11540 }
11542 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11547 {
11549 /* Only perform transformation if ARG0 is easily inverted. */
11555 op2);
11556 }
11558 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11570 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11571 of fold_ternary on them. */
11579 {
11589 {
11594 {
11602 }
11603 }
11604 }
11606 /* On constants we can use native encode/interpret to constant
11607 fold (nearly) all BIT_FIELD_REFs. */
11611 {
11614 /* Limit us to a reasonable amount of work. To relax the
11615 other limitations we need bit-shifting of the buffer
11616 and rounding up the size. */
11620 {
11622 unsigned HOST_WIDE_INT len
11627 {
11632 }
11633 }
11634 }
11639 /* For integers we can decompose the FMA if possible. */
11651 {
11667 {
11672 /* Make sure that the perm value is in an acceptable
11673 range. */
11682 else
11687 }
11690 {
11695 }
11700 {
11705 }
11711 {
11715 }
11720 /* Some targets are deficient and fail to expand a single
11721 argument permutation while still allowing an equivalent
11722 2-argument version. */
11726 {
11729 }
11732 {
11739 }
11743 }
11747 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11750 {
11756 wide_int tem2
11760 }
11765 {
11767 unsigned HOST_WIDE_INT elsize
11770 {
11774 else
11775 {
11781 }
11782 }
11783 }
11789 }
11791 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11792 of an array (or vector). */
11794 tree
11796 {
11801 {
11804 {
11805 /* Static constructors for variably sized objects makes no sense. */
11809 }
11810 }
11821 offset_int max_index;
11826 {
11827 /* Array constructor might explicitly set index, or specify a range,
11828 or leave index NULL meaning that it is next index after previous
11829 one. */
11831 {
11834 else
11835 {
11839 }
11840 }
11841 else
11842 {
11848 }
11850 /* Do we have match? */
11854 }
11856 }
11858 /* Perform constant folding and related simplification of EXPR.
11859 The related simplifications include x*1 => x, x*0 => 0, etc.,
11860 and application of the associative law.
11861 NOP_EXPR conversions may be removed freely (as long as we
11862 are careful not to change the type of the overall expression).
11863 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11864 but we can constant-fold them if they have constant operands. */
11866 #ifdef ENABLE_FOLD_CHECKING
11867 # define fold(x) fold_1 (x)
11869 static
11870 #endif
11871 tree
11873 {
11877 tree tem;
11880 /* Return right away if a constant. */
11884 /* CALL_EXPR-like objects with variable numbers of operands are
11885 treated specially. */
11887 {
11889 {
11892 }
11894 }
11897 {
11902 {
11920 }
11921 }
11924 {
11926 {
11933 {
11938 }
11941 }
11943 /* Return a VECTOR_CST if possible. */
11945 {
11951 tree val;
11957 }
11965 }
11967 #ifdef ENABLE_FOLD_CHECKING
11968 #undef fold
11975 /* When --enable-checking=fold, compute a digest of expr before
11976 and after actual fold call to see if fold did not accidentally
11977 change original expr. */
11979 tree
11981 {
11982 tree ret;
12002 }
12004 void
12006 {
12017 }
12019 static void
12021 {
12023 }
12025 static void
12028 {
12034 recursive_label:
12044 {
12045 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12050 }
12058 {
12059 /* Allow these fields to be modified. */
12060 tree tmp;
12069 {
12072 }
12073 }
12084 {
12087 {
12102 }
12106 {
12119 }
12136 {
12142 }
12145 {
12147 {
12150 }
12152 }
12163 {
12166 }
12176 }
12177 }
12179 /* Helper function for outputting the checksum of a tree T. When
12180 debugging with gdb, you can "define mynext" to be "next" followed
12181 by "call debug_fold_checksum (op0)", then just trace down till the
12182 outputs differ. */
12184 DEBUG_FUNCTION void
12186 {
12201 }
12203 #endif
12205 /* Fold a unary tree expression with code CODE of type TYPE with an
12206 operand OP0. LOC is the location of the resulting expression.
12207 Return a folded expression if successful. Otherwise, return a tree
12208 expression with code CODE of type TYPE with an operand OP0. */
12210 tree
12213 {
12214 tree tem;
12215 #ifdef ENABLE_FOLD_CHECKING
12224 #endif
12230 #ifdef ENABLE_FOLD_CHECKING
12237 #endif
12239 }
12241 /* Fold a binary tree expression with code CODE of type TYPE with
12242 operands OP0 and OP1. LOC is the location of the resulting
12243 expression. Return a folded expression if successful. Otherwise,
12244 return a tree expression with code CODE of type TYPE with operands
12245 OP0 and OP1. */
12247 tree
12250 MEM_STAT_DECL)
12251 {
12252 tree tem;
12253 #ifdef ENABLE_FOLD_CHECKING
12270 #endif
12276 #ifdef ENABLE_FOLD_CHECKING
12291 #endif
12293 }
12295 /* Fold a ternary tree expression with code CODE of type TYPE with
12296 operands OP0, OP1, and OP2. Return a folded expression if
12297 successful. Otherwise, return a tree expression with code CODE of
12298 type TYPE with operands OP0, OP1, and OP2. */
12300 tree
12303 {
12304 tree tem;
12305 #ifdef ENABLE_FOLD_CHECKING
12329 #endif
12336 #ifdef ENABLE_FOLD_CHECKING
12359 #endif
12361 }
12363 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12364 arguments in ARGARRAY, and a null static chain.
12365 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12366 of type TYPE from the given operands as constructed by build_call_array. */
12368 tree
12371 {
12372 tree tem;
12373 #ifdef ENABLE_FOLD_CHECKING
12392 #endif
12398 #ifdef ENABLE_FOLD_CHECKING
12414 #endif
12416 }
12418 /* Perform constant folding and related simplification of initializer
12419 expression EXPR. These behave identically to "fold_buildN" but ignore
12420 potential run-time traps and exceptions that fold must preserve. */
12422 #define START_FOLD_INIT \
12423 int saved_signaling_nans = flag_signaling_nans;\
12424 int saved_trapping_math = flag_trapping_math;\
12425 int saved_rounding_math = flag_rounding_math;\
12426 int saved_trapv = flag_trapv;\
12427 int saved_folding_initializer = folding_initializer;\
12428 flag_signaling_nans = 0;\
12429 flag_trapping_math = 0;\
12430 flag_rounding_math = 0;\
12431 flag_trapv = 0;\
12432 folding_initializer = 1;
12434 #define END_FOLD_INIT \
12435 flag_signaling_nans = saved_signaling_nans;\
12436 flag_trapping_math = saved_trapping_math;\
12437 flag_rounding_math = saved_rounding_math;\
12438 flag_trapv = saved_trapv;\
12439 folding_initializer = saved_folding_initializer;
12441 tree
12444 {
12445 tree result;
12446 START_FOLD_INIT;
12450 END_FOLD_INIT;
12452 }
12454 tree
12457 {
12458 tree result;
12459 START_FOLD_INIT;
12463 END_FOLD_INIT;
12465 }
12467 tree
12470 {
12471 tree result;
12472 START_FOLD_INIT;
12476 END_FOLD_INIT;
12478 }
12480 #undef START_FOLD_INIT
12481 #undef END_FOLD_INIT
12483 /* Determine if first argument is a multiple of second argument. Return 0 if
12484 it is not, or we cannot easily determined it to be.
12486 An example of the sort of thing we care about (at this point; this routine
12487 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12488 fold cases do now) is discovering that
12490 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12492 is a multiple of
12494 SAVE_EXPR (J * 8)
12496 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12498 This code also handles discovering that
12500 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12502 is a multiple of 8 so we don't have to worry about dealing with a
12503 possible remainder.
12505 Note that we *look* inside a SAVE_EXPR only to determine how it was
12506 calculated; it is not safe for fold to do much of anything else with the
12507 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12508 at run time. For example, the latter example above *cannot* be implemented
12509 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12510 evaluation time of the original SAVE_EXPR is not necessarily the same at
12511 the time the new expression is evaluated. The only optimization of this
12512 sort that would be valid is changing
12514 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12516 divided by 8 to
12518 SAVE_EXPR (I) * SAVE_EXPR (J)
12520 (where the same SAVE_EXPR (J) is used in the original and the
12521 transformed version). */
12523 int
12525 {
12536 {
12538 /* Bitwise and provides a power of two multiple. If the mask is
12539 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12542 /* FALLTHRU */
12549 /* It is impossible to prove if op0 - op1 is multiple of bottom
12550 precisely, so be conservative here checking if both op0 and op1
12551 are multiple of bottom. Note we check the second operand first
12552 since it's usually simpler. */
12557 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12558 as op0 - 3 if the expression has unsigned type. For example,
12559 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12569 {
12571 /* const_binop may not detect overflow correctly,
12572 so check for it explicitly here. */
12576 size_one_node,
12577 op1)))
12580 }
12584 /* Can't handle conversions from non-integral or wider integral type. */
12590 /* fall through */
12607 SIGNED);
12613 {
12616 /* Check for special cases to see if top is defined as multiple
12617 of bottom:
12619 top = (X & ~(bottom - 1) ; bottom is power of 2
12621 or
12623 Y = X % bottom
12624 top = X - Y. */
12643 }
12645 /* fall through */
12649 }
12650 }
12652 #define tree_expr_nonnegative_warnv_p(X, Y) \
12655 #define RECURSE(X) \
12656 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12658 /* Return true if CODE or TYPE is known to be non-negative. */
12660 static bool
12662 {
12665 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12666 have a signed:1 type (where the value is -1 and 0). */
12669 }
12671 /* Return true if (CODE OP0) is known to be non-negative. If the return
12672 value is based on the assumption that signed overflow is undefined,
12673 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12674 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12676 bool
12679 {
12684 {
12686 /* We can't return 1 if flag_wrapv is set because
12687 ABS_EXPR<INT_MIN> = INT_MIN. */
12691 {
12694 }
12702 CASE_CONVERT:
12703 {
12708 {
12712 {
12716 }
12717 }
12719 {
12725 }
12726 }
12731 }
12733 /* We don't know sign of `t', so be conservative and return false. */
12735 }
12737 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12738 value is based on the assumption that signed overflow is undefined,
12739 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12740 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12742 bool
12746 {
12751 {
12757 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12758 both unsigned and at least 2 bits shorter than the result. */
12762 {
12767 {
12771 }
12772 }
12777 {
12778 /* x * x is always non-negative for floating point x
12779 or without overflow. */
12782 {
12787 }
12788 }
12790 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12791 both unsigned and their total bits is shorter than the result. */
12795 {
12814 {
12824 }
12825 }
12852 }
12854 /* We don't know sign of `t', so be conservative and return false. */
12856 }
12858 /* Return true if T is known to be non-negative. If the return
12859 value is based on the assumption that signed overflow is undefined,
12860 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12861 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12863 bool
12865 {
12870 {
12884 /* Limit the depth of recursion to avoid quadratic behavior.
12885 This is expected to catch almost all occurrences in practice.
12886 If this code misses important cases that unbounded recursion
12887 would not, passes that need this information could be revised
12888 to provide it through dataflow propagation. */
12896 }
12897 }
12899 /* Return true if T is known to be non-negative. If the return
12900 value is based on the assumption that signed overflow is undefined,
12901 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12902 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12904 bool
12907 {
12909 {
12910 CASE_CFN_ACOS:
12911 CASE_CFN_ACOSH:
12912 CASE_CFN_CABS:
12913 CASE_CFN_COSH:
12914 CASE_CFN_ERFC:
12915 CASE_CFN_EXP:
12916 CASE_CFN_EXP10:
12917 CASE_CFN_EXP2:
12918 CASE_CFN_FABS:
12919 CASE_CFN_FDIM:
12920 CASE_CFN_HYPOT:
12921 CASE_CFN_POW10:
12922 CASE_CFN_FFS:
12923 CASE_CFN_PARITY:
12924 CASE_CFN_POPCOUNT:
12925 CASE_CFN_CLZ:
12926 CASE_CFN_CLRSB:
12929 /* Always true. */
12932 CASE_CFN_SQRT:
12933 /* sqrt(-0.0) is -0.0. */
12938 CASE_CFN_ASINH:
12939 CASE_CFN_ATAN:
12940 CASE_CFN_ATANH:
12941 CASE_CFN_CBRT:
12942 CASE_CFN_CEIL:
12943 CASE_CFN_ERF:
12944 CASE_CFN_EXPM1:
12945 CASE_CFN_FLOOR:
12946 CASE_CFN_FMOD:
12947 CASE_CFN_FREXP:
12948 CASE_CFN_ICEIL:
12949 CASE_CFN_IFLOOR:
12950 CASE_CFN_IRINT:
12951 CASE_CFN_IROUND:
12952 CASE_CFN_LCEIL:
12953 CASE_CFN_LDEXP:
12954 CASE_CFN_LFLOOR:
12955 CASE_CFN_LLCEIL:
12956 CASE_CFN_LLFLOOR:
12957 CASE_CFN_LLRINT:
12958 CASE_CFN_LLROUND:
12959 CASE_CFN_LRINT:
12960 CASE_CFN_LROUND:
12961 CASE_CFN_MODF:
12962 CASE_CFN_NEARBYINT:
12963 CASE_CFN_RINT:
12964 CASE_CFN_ROUND:
12965 CASE_CFN_SCALB:
12966 CASE_CFN_SCALBLN:
12967 CASE_CFN_SCALBN:
12968 CASE_CFN_SIGNBIT:
12969 CASE_CFN_SIGNIFICAND:
12970 CASE_CFN_SINH:
12971 CASE_CFN_TANH:
12972 CASE_CFN_TRUNC:
12973 /* True if the 1st argument is nonnegative. */
12976 CASE_CFN_FMAX:
12977 /* True if the 1st OR 2nd arguments are nonnegative. */
12980 CASE_CFN_FMIN:
12981 /* True if the 1st AND 2nd arguments are nonnegative. */
12984 CASE_CFN_COPYSIGN:
12985 /* True if the 2nd argument is nonnegative. */
12988 CASE_CFN_POWI:
12989 /* True if the 1st argument is nonnegative or the second
12990 argument is an even integer. */
12996 CASE_CFN_POW:
12997 /* True if the 1st argument is nonnegative or the second
12998 argument is an even integer valued real. */
13000 {
13001 REAL_VALUE_TYPE c;
13002 HOST_WIDE_INT n;
13007 {
13008 REAL_VALUE_TYPE cint;
13012 }
13013 }
13018 }
13020 }
13022 /* Return true if T is known to be non-negative. If the return
13023 value is based on the assumption that signed overflow is undefined,
13024 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13025 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13027 static bool
13029 {
13035 {
13037 {
13041 /* If the initializer is non-void, then it's a normal expression
13042 that will be assigned to the slot. */
13046 /* Otherwise, the initializer sets the slot in some way. One common
13047 way is an assignment statement at the end of the initializer. */
13049 {
13057 else
13059 }
13065 }
13068 {
13074 arg0,
13075 arg1,
13077 }
13090 }
13091 }
13093 #undef RECURSE
13094 #undef tree_expr_nonnegative_warnv_p
13096 /* Return true if T is known to be non-negative. If the return
13097 value is based on the assumption that signed overflow is undefined,
13098 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13099 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13101 bool
13103 {
13110 {
13132 }
13135 {
13161 }
13162 }
13164 /* Return true if `t' is known to be non-negative. Handle warnings
13165 about undefined signed overflow. */
13167 bool
13169 {
13176 "determining that expression is always "
13178 WARN_STRICT_OVERFLOW_MISC);
13180 }
13183 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13184 For floating point we further ensure that T is not denormal.
13185 Similar logic is present in nonzero_address in rtlanal.h.
13187 If the return value is based on the assumption that signed overflow
13188 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13189 change *STRICT_OVERFLOW_P. */
13191 bool
13194 {
13196 {
13199 strict_overflow_p);
13202 {
13208 strict_overflow_p));
13209 }
13214 strict_overflow_p);
13218 }
13221 }
13223 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13224 For floating point we further ensure that T is not denormal.
13225 Similar logic is present in nonzero_address in rtlanal.h.
13227 If the return value is based on the assumption that signed overflow
13228 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13229 change *STRICT_OVERFLOW_P. */
13231 bool
13233 tree type,
13234 tree op0,
13236 {
13239 {
13243 {
13244 /* With the presence of negative values it is hard
13245 to say something. */
13252 /* One of operands must be positive and the other non-negative. */
13253 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13254 overflows, on a twos-complement machine the sum of two
13255 nonnegative numbers can never be zero. */
13257 strict_overflow_p)
13259 strict_overflow_p));
13260 }
13265 {
13267 strict_overflow_p)
13269 strict_overflow_p))
13270 {
13273 }
13274 }
13283 {
13286 }
13293 {
13297 /* When both operands are nonzero, then MAX must be too. */
13299 strict_overflow_p))
13302 /* MAX where operand 0 is positive is positive. */
13304 strict_overflow_p);
13305 }
13306 /* MAX where operand 1 is positive is positive. */
13311 {
13315 }
13320 strict_overflow_p)
13322 strict_overflow_p));
13326 }
13329 }
13331 /* Return true when T is an address and is known to be nonzero.
13332 For floating point we further ensure that T is not denormal.
13333 Similar logic is present in nonzero_address in rtlanal.h.
13335 If the return value is based on the assumption that signed overflow
13336 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13337 change *STRICT_OVERFLOW_P. */
13339 bool
13341 {
13344 {
13349 {
13361 /* For objects in symbol table check if we know they are non-zero.
13362 Don't do anything for variables and functions before symtab is built;
13363 it is quite possible that they will be declared weak later. */
13368 /* Function local objects are never NULL. */
13375 /* Constants are never weak. */
13380 }
13388 {
13392 }
13397 }
13399 }
13401 #define integer_valued_real_p(X) \
13404 #define RECURSE(X) \
13405 ((integer_valued_real_p) (X, depth + 1))
13407 /* Return true if the floating point result of (CODE OP0) has an
13408 integer value. We also allow +Inf, -Inf and NaN to be considered
13409 integer values. Return false for signaling NaN.
13411 DEPTH is the current nesting depth of the query. */
13413 bool
13415 {
13417 {
13424 CASE_CONVERT:
13425 {
13432 }
13436 }
13438 }
13440 /* Return true if the floating point result of (CODE OP0 OP1) has an
13441 integer value. We also allow +Inf, -Inf and NaN to be considered
13442 integer values. Return false for signaling NaN.
13444 DEPTH is the current nesting depth of the query. */
13446 bool
13448 {
13450 {
13460 }
13462 }
13464 /* Return true if the floating point result of calling FNDECL with arguments
13465 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13466 considered integer values. Return false for signaling NaN. If FNDECL
13467 takes fewer than 2 arguments, the remaining ARGn are null.
13469 DEPTH is the current nesting depth of the query. */
13471 bool
13473 {
13475 {
13476 CASE_CFN_CEIL:
13477 CASE_CFN_FLOOR:
13478 CASE_CFN_NEARBYINT:
13479 CASE_CFN_RINT:
13480 CASE_CFN_ROUND:
13481 CASE_CFN_TRUNC:
13484 CASE_CFN_FMIN:
13485 CASE_CFN_FMAX:
13490 }
13492 }
13494 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13495 has an integer value. We also allow +Inf, -Inf and NaN to be
13496 considered integer values. Return false for signaling NaN.
13498 DEPTH is the current nesting depth of the query. */
13500 bool
13502 {
13504 {
13512 /* Limit the depth of recursion to avoid quadratic behavior.
13513 This is expected to catch almost all occurrences in practice.
13514 If this code misses important cases that unbounded recursion
13515 would not, passes that need this information could be revised
13516 to provide it through dataflow propagation. */
13520 depth));
13524 }
13526 }
13528 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13529 has an integer value. We also allow +Inf, -Inf and NaN to be
13530 considered integer values. Return false for signaling NaN.
13532 DEPTH is the current nesting depth of the query. */
13534 static bool
13536 {
13538 {
13549 }
13551 }
13553 #undef RECURSE
13554 #undef integer_valued_real_p
13556 /* Return true if the floating point expression T has an integer value.
13557 We also allow +Inf, -Inf and NaN to be considered integer values.
13558 Return false for signaling NaN.
13560 DEPTH is the current nesting depth of the query. */
13562 bool
13564 {
13570 {
13586 }
13589 {
13595 {
13604 }
13608 }
13609 }
13611 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13612 attempt to fold the expression to a constant without modifying TYPE,
13613 OP0 or OP1.
13615 If the expression could be simplified to a constant, then return
13616 the constant. If the expression would not be simplified to a
13617 constant, then return NULL_TREE. */
13619 tree
13621 {
13624 }
13626 /* Given the components of a unary expression CODE, TYPE and OP0,
13627 attempt to fold the expression to a constant without modifying
13628 TYPE or OP0.
13630 If the expression could be simplified to a constant, then return
13631 the constant. If the expression would not be simplified to a
13632 constant, then return NULL_TREE. */
13634 tree
13636 {
13639 }
13641 /* If EXP represents referencing an element in a constant string
13642 (either via pointer arithmetic or array indexing), return the
13643 tree representing the value accessed, otherwise return NULL. */
13645 tree
13647 {
13651 {
13653 tree index;
13654 tree string;
13659 else
13660 {
13664 /* Optimize the special-case of a zero lower bound.
13666 We convert the low_bound to sizetype to avoid some problems
13667 with constant folding. (E.g. suppose the lower bound is 1,
13668 and its mode is QI. Without the conversion,l (ARRAY
13669 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13670 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13676 }
13689 }
13691 }
13693 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13694 an integer constant, real, or fixed-point constant.
13696 TYPE is the type of the result. */
13698 static tree
13700 {
13704 {
13706 {
13713 }
13720 {
13721 FIXED_VALUE_TYPE f;
13726 /* Propagate overflow flags. */
13730 }
13734 }
13737 }
13739 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13740 an integer constant or real constant.
13742 TYPE is the type of the result. */
13744 tree
13746 {
13750 {
13752 {
13753 /* If the value is unsigned or non-negative, then the absolute value
13754 is the same as the ordinary value. */
13758 /* If the value is negative, then the absolute value is
13759 its negation. */
13760 else
13761 {
13766 }
13767 }
13773 else
13779 }
13782 }
13784 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13785 constant. TYPE is the type of the result. */
13787 static tree
13789 {
13793 }
13795 /* Given CODE, a relational operator, the target type, TYPE and two
13796 constant operands OP0 and OP1, return the result of the
13797 relational operation. If the result is not a compile time
13798 constant, then return NULL_TREE. */
13800 static tree
13802 {
13805 /* From here on, the only cases we handle are when the result is
13806 known to be a constant. */
13809 {
13813 /* Handle the cases where either operand is a NaN. */
13815 {
13817 {
13845 }
13848 }
13851 }
13854 {
13858 }
13860 /* Handle equality/inequality of complex constants. */
13862 {
13873 else
13875 }
13878 {
13880 {
13881 /* Have vector comparison with scalar boolean result. */
13885 {
13893 }
13895 }
13902 {
13914 }
13917 }
13919 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13921 To compute GT, swap the arguments and do LT.
13922 To compute GE, do LT and invert the result.
13923 To compute LE, swap the arguments, do LT and invert the result.
13924 To compute NE, do EQ and invert the result.
13926 Therefore, the code below must handle only EQ and LT. */
13929 {
13932 }
13934 /* Note that it is safe to invert for real values here because we
13935 have already handled the one case that it matters. */
13939 {
13942 }
13944 /* Compute a result for LT or EQ if args permit;
13945 Otherwise return T. */
13947 {
13950 else
13952 }
13953 else
13959 }
13961 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13962 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13963 itself. */
13965 tree
13967 {
13968 /* If the expression does not have side effects then we don't have to wrap
13969 it with a cleanup point expression. */
13973 /* If the expression is a return, check to see if the expression inside the
13974 return has no side effects or the right hand side of the modify expression
13975 inside the return. If either don't have side effects set we don't need to
13976 wrap the expression in a cleanup point expression. Note we don't check the
13977 left hand side of the modify because it should always be a return decl. */
13979 {
13986 }
13989 }
13991 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13992 of an indirection through OP0, or NULL_TREE if no simplification is
13993 possible. */
13995 tree
13997 {
13999 tree subtype;
14007 {
14010 /* *&CONST_DECL -> to the value of the const decl. */
14013 /* *&p => p; make sure to handle *&"str"[cst] here. */
14015 {
14019 else
14021 }
14022 /* *(foo *)&fooarray => fooarray[0] */
14025 && (!in_gimple_form
14027 {
14037 }
14038 /* *(foo *)&complexfoo => __real__ complexfoo */
14042 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14045 {
14049 }
14050 }
14054 {
14060 {
14061 tree op00type;
14065 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14068 {
14070 unsigned HOST_WIDE_INT max_offset
14075 {
14082 }
14083 }
14084 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14087 {
14091 }
14092 /* ((foo *)&fooarray)[1] => fooarray[1] */
14095 {
14105 }
14106 }
14107 }
14109 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14112 && (!in_gimple_form
14114 {
14115 tree type_domain;
14125 NULL_TREE);
14126 }
14129 }
14131 /* Builds an expression for an indirection through T, simplifying some
14132 cases. */
14134 tree
14136 {
14144 }
14146 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14148 tree
14150 {
14155 else
14157 }
14159 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14160 whose result is ignored. The type of the returned tree need not be
14161 the same as the original expression. */
14163 tree
14165 {
14171 {
14182 else
14188 {
14204 }
14209 }
14210 }
14212 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14214 tree
14216 {
14222 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14223 have to do anything. Only do this when we are not given a const,
14224 because in that case, this check is more expensive than just
14225 doing it. */
14227 {
14232 }
14234 /* If divisor is a power of two, simplify this to bit manipulation. */
14236 {
14238 {
14252 }
14253 else
14254 {
14255 tree t;
14261 }
14262 }
14263 else
14264 {
14269 }
14272 }
14274 /* Likewise, but round down. */
14276 tree
14278 {
14285 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14286 have to do anything. Only do this when we are not given a const,
14287 because in that case, this check is more expensive than just
14288 doing it. */
14290 {
14295 }
14297 /* If divisor is a power of two, simplify this to bit manipulation. */
14299 {
14300 tree t;
14304 }
14305 else
14306 {
14311 }
14314 }
14316 /* Returns the pointer to the base of the object addressed by EXP and
14317 extracts the information about the offset of the access, storing it
14318 to PBITPOS and POFFSET. */
14320 static tree
14323 {
14324 tree core;
14325 machine_mode mode;
14327 HOST_WIDE_INT bitsize;
14331 {
14336 }
14337 else
14338 {
14342 }
14345 }
14347 /* Returns true if addresses of E1 and E2 differ by a constant, false
14348 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14350 bool
14352 {
14366 {
14376 }
14378 {
14379 /* If only one of the offsets is non-constant, the difference cannot
14380 be a constant. */
14382 }
14383 else
14388 }
14390 /* Return OFF converted to a pointer offset type suitable as offset for
14391 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14392 tree
14394 {
14396 }
14398 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14399 tree
14401 {
14404 }
14406 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14407 tree
14409 {
14412 }
14414 /* Return a char pointer for a C string if it is a string constant
14415 or sum of string constant and integer constant. We only support
14416 string constants properly terminated with '\0' character.
14417 If STRLEN is a valid pointer, length (including terminating character)
14418 of returned string is stored to the argument. */
14422 {
14423 tree offset_node;
14434 {
14437 else
14439 }
14444 /* Support only properly null-terminated strings. */
14453 }
14455 #if CHECKING_P
14459 /* Helper functions for writing tests of folding trees. */
14461 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14463 static void
14465 tree constant)
14466 {
14468 }
14470 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14471 wrapping WRAPPED_EXPR. */
14473 static void
14475 tree wrapped_expr)
14476 {
14481 }
14483 /* Verify that various arithmetic binary operations are folded
14484 correctly. */
14486 static void
14488 {
14494 /* Addition. */
14495 /* 1 <-- (0 + 1) */
14497 one);
14499 one);
14501 /* (nonlvalue)x <-- (x + 0) */
14503 x);
14505 /* Subtraction. */
14506 /* 0 <-- (x - x) */
14508 zero);
14510 x);
14512 /* Multiplication. */
14513 /* 0 <-- (x * 0) */
14515 zero);
14517 /* (nonlvalue)x <-- (x * 1) */
14519 x);
14520 }
14522 /* Verify that various binary operations on vectors are folded
14523 correctly. */
14525 static void
14527 {
14533 /* Verify equality tests that return a scalar boolean result. */
14539 }
14541 /* Run all of the selftests within this file. */
14543 void
14545 {
14548 }