| blob | 0efa9d5b0b1dd338a324c5a75ddc5b7a8545a013 |
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. */
81 #ifndef LOAD_EXTEND_OP
82 #define LOAD_EXTEND_OP(M) UNKNOWN
83 #endif
85 /* Nonzero if we are folding constants inside an initializer; zero
86 otherwise. */
89 /* The following constants represent a bit based encoding of GCC's
90 comparison operators. This encoding simplifies transformations
91 on relational comparison operators, such as AND and OR. */
109 };
149 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
150 Otherwise, return LOC. */
152 static location_t
154 {
157 }
159 /* Similar to protected_set_expr_location, but never modify x in place,
160 if location can and needs to be set, unshare it. */
164 {
170 {
173 }
175 }
176 \f
177 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
178 division and returns the quotient. Otherwise returns
179 NULL_TREE. */
181 tree
183 {
184 widest_int quo;
191 }
192 \f
193 /* This is nonzero if we should defer warnings about undefined
194 overflow. This facility exists because these warnings are a
195 special case. The code to estimate loop iterations does not want
196 to issue any warnings, since it works with expressions which do not
197 occur in user code. Various bits of cleanup code call fold(), but
198 only use the result if it has certain characteristics (e.g., is a
199 constant); that code only wants to issue a warning if the result is
200 used. */
204 /* If a warning about undefined overflow is deferred, this is the
205 warning. Note that this may cause us to turn two warnings into
206 one, but that is fine since it is sufficient to only give one
207 warning per expression. */
211 /* If a warning about undefined overflow is deferred, this is the
212 level at which the warning should be emitted. */
216 /* Start deferring overflow warnings. We could use a stack here to
217 permit nested calls, but at present it is not necessary. */
219 void
221 {
223 }
225 /* Stop deferring overflow warnings. If there is a pending warning,
226 and ISSUE is true, then issue the warning if appropriate. STMT is
227 the statement with which the warning should be associated (used for
228 location information); STMT may be NULL. CODE is the level of the
229 warning--a warn_strict_overflow_code value. This function will use
230 the smaller of CODE and the deferred code when deciding whether to
231 issue the warning. CODE may be zero to mean to always use the
232 deferred code. */
234 void
236 {
238 location_t locus;
243 {
249 }
260 /* Use the smallest code level when deciding to issue the
261 warning. */
270 else
273 }
275 /* Stop deferring overflow warnings, ignoring any deferred
276 warnings. */
278 void
280 {
282 }
284 /* Whether we are deferring overflow warnings. */
286 bool
288 {
290 }
292 /* This is called when we fold something based on the fact that signed
293 overflow is undefined. */
295 void
297 {
299 {
302 {
305 }
306 }
309 }
310 \f
311 /* Return true if the built-in mathematical function specified by CODE
312 is odd, i.e. -f(x) == f(-x). */
314 bool
316 {
318 {
319 CASE_CFN_ASIN:
320 CASE_CFN_ASINH:
321 CASE_CFN_ATAN:
322 CASE_CFN_ATANH:
323 CASE_CFN_CASIN:
324 CASE_CFN_CASINH:
325 CASE_CFN_CATAN:
326 CASE_CFN_CATANH:
327 CASE_CFN_CBRT:
328 CASE_CFN_CPROJ:
329 CASE_CFN_CSIN:
330 CASE_CFN_CSINH:
331 CASE_CFN_CTAN:
332 CASE_CFN_CTANH:
333 CASE_CFN_ERF:
334 CASE_CFN_LLROUND:
335 CASE_CFN_LROUND:
336 CASE_CFN_ROUND:
337 CASE_CFN_SIN:
338 CASE_CFN_SINH:
339 CASE_CFN_TAN:
340 CASE_CFN_TANH:
341 CASE_CFN_TRUNC:
344 CASE_CFN_LLRINT:
345 CASE_CFN_LRINT:
346 CASE_CFN_NEARBYINT:
347 CASE_CFN_RINT:
352 }
354 }
356 /* Check whether we may negate an integer constant T without causing
357 overflow. */
359 bool
361 {
362 tree type;
371 }
373 /* Determine whether an expression T can be cheaply negated using
374 the function negate_expr without introducing undefined overflow. */
376 static bool
378 {
379 tree type;
388 {
393 /* Check that -CST will not overflow type. */
406 /* We want to canonicalize to positive real constants. Pretend
407 that only negative ones can be easily negated. */
415 {
426 }
441 /* -(A + B) -> (-B) - A. */
446 /* -(A + B) -> (-A) - B. */
450 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
461 /* INT_MIN/n * n doesn't overflow while negating one operand it does
462 if n is a power of two. */
471 /* Fall through. */
486 /* In general we can't negate B in A / B, because if A is INT_MIN and
487 B is 1, we may turn this into INT_MIN / -1 which is undefined
488 and actually traps on some architectures. */
497 /* Negate -((double)float) as (double)(-float). */
499 {
503 }
507 /* Negate -f(x) as f(-x). */
513 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
515 {
519 }
524 }
526 }
528 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
529 simplification is possible.
530 If negate_expr_p would return true for T, NULL_TREE will never be
531 returned. */
533 static tree
535 {
537 tree tem;
540 {
541 /* Convert - (~A) to A + 1. */
567 {
572 }
576 {
581 {
585 }
588 }
611 {
612 /* -(A + B) -> (-B) - A. */
616 {
620 }
622 /* -(A + B) -> (-A) - B. */
624 {
628 }
629 }
633 /* - (A - B) -> B - A */
645 /* Fall through. */
649 {
658 }
670 /* In general we can't negate B in A / B, because if A is INT_MIN and
671 B is 1, we may turn this into INT_MIN / -1 which is undefined
672 and actually traps on some architectures. */
684 /* Convert -((double)float) into (double)(-float). */
686 {
690 }
694 /* Negate -f(x) as f(-x). */
697 {
703 }
707 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
709 {
712 {
719 }
720 }
725 }
728 }
730 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
731 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
732 return NULL_TREE. */
734 static tree
736 {
738 location_t loc;
751 }
752 \f
753 /* Split a tree IN into a constant, literal and variable parts that could be
754 combined with CODE to make IN. "constant" means an expression with
755 TREE_CONSTANT but that isn't an actual constant. CODE must be a
756 commutative arithmetic operation. Store the constant part into *CONP,
757 the literal in *LITP and return the variable part. If a part isn't
758 present, set it to null. If the tree does not decompose in this way,
759 return the entire tree as the variable part and the other parts as null.
761 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
762 case, we negate an operand that was subtracted. Except if it is a
763 literal for which we use *MINUS_LITP instead.
765 If NEGATE_P is true, we are negating all of IN, again except a literal
766 for which we use *MINUS_LITP instead. If a variable part is of pointer
767 type, it is negated after converting to TYPE. This prevents us from
768 generating illegal MINUS pointer expression. LOC is the location of
769 the converted variable part.
771 If IN is itself a literal or constant, return it as appropriate.
773 Note that we do not guarantee that any of the three values will be the
774 same type as IN, but they will have the same signedness and mode. */
776 static tree
779 {
786 /* Strip any conversions that don't change the machine mode or signedness. */
795 /* We can associate addition and subtraction together (even
796 though the C standard doesn't say so) for integers because
797 the value is not affected. For reals, the value might be
798 affected, so we can't. */
801 {
807 /* First see if either of the operands is a literal, then a constant. */
820 /* If we haven't dealt with either operand, this is not a case we can
821 decompose. Otherwise, VAR is either of the ones remaining, if any. */
826 else
829 /* Now do any needed negations. */
835 {
836 /* Convert to TYPE before negating. */
839 }
840 }
843 {
844 /* -X - 1 is folded to ~X, undo that here. */
847 }
850 else
854 {
861 {
862 /* Convert to TYPE before negating. */
865 }
866 }
869 }
871 /* Re-associate trees split by the above function. T1 and T2 are
872 either expressions to associate or null. Return the new
873 expression, if any. LOC is the location of the new expression. If
874 we build an operation, do it in TYPE and with CODE. */
876 static tree
878 {
884 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
885 try to fold this since we will have infinite recursion. But do
886 deal with any NEGATE_EXPRs. */
889 {
891 {
904 }
906 {
909 }
913 }
917 }
918 \f
919 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
920 for use in int_const_binop, size_binop and size_diffop. */
922 static bool
924 {
931 {
940 }
945 }
948 /* Combine two integer constants ARG1 and ARG2 under operation CODE
949 to produce a new constant. Return NULL_TREE if we don't know how
950 to evaluate CODE at compile-time. */
952 static tree
955 {
956 wide_int res;
957 tree t;
965 {
981 {
985 else
987 }
990 /* It's unclear from the C standard whether shifts can overflow.
991 The following code ignores overflow; perhaps a C standard
992 interpretation ruling is needed. */
994 else
1001 {
1005 else
1007 }
1011 else
1090 }
1098 }
1100 tree
1102 {
1104 }
1106 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1107 constant. We assume ARG1 and ARG2 have the same data type, or at least
1108 are the same kind of constant and the same machine mode. Return zero if
1109 combining the constants is not allowed in the current operating mode. */
1111 static tree
1113 {
1114 /* Sanity check for the recursive cases. */
1122 {
1128 }
1131 {
1132 machine_mode mode;
1133 REAL_VALUE_TYPE d1;
1134 REAL_VALUE_TYPE d2;
1135 REAL_VALUE_TYPE value;
1136 REAL_VALUE_TYPE result;
1140 /* The following codes are handled by real_arithmetic. */
1142 {
1153 }
1161 /* Don't perform operation if we honor signaling NaNs and
1162 either operand is a signaling NaN. */
1168 /* Don't perform operation if it would raise a division
1169 by zero exception. */
1175 /* If either operand is a NaN, just return it. Otherwise, set up
1176 for floating-point trap; we return an overflow. */
1178 {
1179 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1180 is off. */
1184 }
1186 {
1187 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1188 is off. */
1192 }
1197 /* Don't constant fold this floating point operation if
1198 the result has overflowed and flag_trapping_math. */
1206 /* Don't constant fold this floating point operation if the
1207 result may dependent upon the run-time rounding mode and
1208 flag_rounding_math is set, or if GCC's software emulation
1209 is unable to accurately represent the result. */
1219 }
1222 {
1223 FIXED_VALUE_TYPE f1;
1224 FIXED_VALUE_TYPE f2;
1225 FIXED_VALUE_TYPE result;
1230 /* The following codes are handled by fixed_arithmetic. */
1232 {
1244 {
1251 }
1256 }
1263 /* Propagate overflow flags. */
1267 }
1270 {
1279 {
1290 mpc_mul);
1304 mpc_div);
1305 /* Fallthru ... */
1311 {
1312 /* Keep this algorithm in sync with
1313 tree-complex.c:expand_complex_div_straight().
1315 Expand complex division to scalars, straightforward algorithm.
1316 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1317 t = br*br + bi*bi
1318 */
1319 tree magsquared
1323 tree t1
1327 tree t2
1334 }
1335 else
1336 {
1337 /* Keep this algorithm in sync with
1338 tree-complex.c:expand_complex_div_wide().
1340 Expand complex division to scalars, modified algorithm to minimize
1341 overflow with wide input ranges. */
1347 {
1348 /* In the TRUE branch, we compute
1349 ratio = br/bi;
1350 div = (br * ratio) + bi;
1351 tr = (ar * ratio) + ai;
1352 ti = (ai * ratio) - ar;
1353 tr = tr / div;
1354 ti = ti / div; */
1365 }
1366 else
1367 {
1368 /* In the FALSE branch, we compute
1369 ratio = d/c;
1370 divisor = (d * ratio) + c;
1371 tr = (b * ratio) + a;
1372 ti = b - (a * ratio);
1373 tr = tr / div;
1374 ti = ti / div; */
1386 }
1387 }
1392 }
1396 }
1400 {
1406 {
1412 /* It is possible that const_binop cannot handle the given
1413 code and return NULL_TREE */
1416 }
1419 }
1421 /* Shifts allow a scalar offset for a vector. */
1424 {
1430 {
1435 /* It is possible that const_binop cannot handle the given
1436 code and return NULL_TREE. */
1439 }
1442 }
1444 }
1446 /* Overload that adds a TYPE parameter to be able to dispatch
1447 to fold_relational_const. */
1449 tree
1451 {
1455 /* ??? Until we make the const_binop worker take the type of the
1456 result as argument put those cases that need it here. */
1458 {
1469 {
1485 {
1491 }
1494 }
1500 {
1525 {
1538 }
1541 }
1544 }
1549 /* Make sure type and arg0 have the same saturating flag. */
1554 }
1556 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1557 Return zero if computing the constants is not possible. */
1559 tree
1561 {
1562 /* Don't perform the operation, other than NEGATE and ABS, if
1563 flag_signaling_nans is on and the operand is a signaling NaN. */
1572 {
1573 CASE_CONVERT:
1580 /* If the source address is 0, and the source address space
1581 cannot have a valid object at 0, fold to dest type null. */
1592 {
1593 /* Can't call fold_negate_const directly here as that doesn't
1594 handle all cases and we might not be able to negate some
1595 constants. */
1600 }
1609 {
1613 }
1619 /* Perform BIT_NOT_EXPR on each element individually. */
1621 {
1623 tree elem;
1628 {
1634 }
1637 }
1659 {
1678 else
1682 {
1686 }
1689 }
1694 {
1708 {
1713 }
1716 {
1720 }
1723 }
1727 }
1730 }
1732 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1733 indicates which particular sizetype to create. */
1735 tree
1737 {
1739 }
1740 \f
1741 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1742 is a tree code. The type of the result is taken from the operands.
1743 Both must be equivalent integer types, ala int_binop_types_match_p.
1744 If the operands are constant, so is the result. */
1746 tree
1748 {
1757 /* Handle the special case of two integer constants faster. */
1759 {
1760 /* And some specific cases even faster than that. */
1762 {
1767 }
1769 {
1772 }
1774 {
1777 }
1779 /* Handle general case of two integer constants. For sizetype
1780 constant calculations we always want to know about overflow,
1781 even in the unsigned case. */
1783 }
1786 }
1788 /* Given two values, either both of sizetype or both of bitsizetype,
1789 compute the difference between the two values. Return the value
1790 in signed type corresponding to the type of the operands. */
1792 tree
1794 {
1796 tree ctype;
1801 /* If the type is already signed, just do the simple thing. */
1809 else
1812 /* If either operand is not a constant, do the conversions to the signed
1813 type and subtract. The hardware will do the right thing with any
1814 overflow in the subtraction. */
1820 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1821 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1822 overflow) and negate (which can't either). Special-case a result
1823 of zero while we're here. */
1829 else
1833 MINUS_EXPR,
1835 }
1836 \f
1837 /* A subroutine of fold_convert_const handling conversions of an
1838 INTEGER_CST to another integer type. */
1840 static tree
1842 {
1843 /* Given an integer constant, make new constant with new type,
1844 appropriately sign-extended or truncated. Use widest_int
1845 so that any extension is done according ARG1's type. */
1849 }
1851 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1852 to an integer type. */
1854 static tree
1856 {
1858 tree t;
1860 /* The following code implements the floating point to integer
1861 conversion rules required by the Java Language Specification,
1862 that IEEE NaNs are mapped to zero and values that overflow
1863 the target precision saturate, i.e. values greater than
1864 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1865 are mapped to INT_MIN. These semantics are allowed by the
1866 C and C++ standards that simply state that the behavior of
1867 FP-to-integer conversion is unspecified upon overflow. */
1869 wide_int val;
1870 REAL_VALUE_TYPE r;
1874 {
1881 }
1883 /* If R is NaN, return zero and show we have an overflow. */
1885 {
1888 }
1890 /* See if R is less than the lower bound or greater than the
1891 upper bound. */
1894 {
1898 {
1901 }
1902 }
1905 {
1908 {
1911 {
1914 }
1915 }
1916 }
1923 }
1925 /* A subroutine of fold_convert_const handling conversions of a
1926 FIXED_CST to an integer type. */
1928 static tree
1930 {
1931 tree t;
1935 /* Right shift FIXED_CST to temp by fbit. */
1939 {
1941 HOST_BITS_PER_DOUBLE_INT,
1944 /* Left shift temp to temp_trunc by fbit. */
1946 HOST_BITS_PER_DOUBLE_INT,
1948 }
1949 else
1950 {
1953 }
1955 /* If FIXED_CST is negative, we need to round the value toward 0.
1956 By checking if the fractional bits are not zero to add 1 to temp. */
1962 /* Given a fixed-point constant, make new constant with new type,
1963 appropriately sign-extended or truncated. */
1971 }
1973 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1974 to another floating point type. */
1976 static tree
1978 {
1979 REAL_VALUE_TYPE value;
1980 tree t;
1982 /* Don't perform the operation if flag_signaling_nans is on
1983 and the operand is a signaling NaN. */
1991 /* If converting an infinity or NAN to a representation that doesn't
1992 have one, set the overflow bit so that we can produce some kind of
1993 error message at the appropriate point if necessary. It's not the
1994 most user-friendly message, but it's better than nothing. */
2001 /* Regular overflow, conversion produced an infinity in a mode that
2002 can't represent them. */
2007 else
2010 }
2012 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2013 to a floating point type. */
2015 static tree
2017 {
2018 REAL_VALUE_TYPE value;
2019 tree t;
2026 }
2028 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2029 to another fixed-point type. */
2031 static tree
2033 {
2034 FIXED_VALUE_TYPE value;
2035 tree t;
2042 /* Propagate overflow flags. */
2046 }
2048 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2049 to a fixed-point type. */
2051 static tree
2053 {
2054 FIXED_VALUE_TYPE value;
2055 tree t;
2057 double_int di;
2064 else
2072 /* Propagate overflow flags. */
2076 }
2078 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2079 to a fixed-point type. */
2081 static tree
2083 {
2084 FIXED_VALUE_TYPE value;
2085 tree t;
2093 /* Propagate overflow flags. */
2097 }
2099 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2100 type TYPE. If no simplification can be done return NULL_TREE. */
2102 static tree
2104 {
2110 {
2117 }
2119 {
2126 }
2128 {
2135 }
2137 {
2140 {
2145 {
2151 }
2153 }
2154 }
2156 }
2158 /* Construct a vector of zero elements of vector type TYPE. */
2160 static tree
2162 {
2163 tree t;
2167 }
2169 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2171 bool
2173 {
2188 {
2204 }
2205 }
2207 /* Convert expression ARG to type TYPE. Used by the middle-end for
2208 simple conversions in preference to calling the front-end's convert. */
2210 tree
2212 {
2214 tree tem;
2225 {
2228 /* Handle conversions between pointers to different address spaces. */
2233 /* fall through */
2238 {
2242 }
2256 {
2260 }
2262 {
2266 }
2268 {
2272 }
2275 {
2293 }
2298 {
2302 }
2305 {
2319 }
2323 {
2332 integer_zero_node));
2334 {
2338 {
2344 }
2352 }
2356 }
2374 }
2375 fold_convert_exit:
2378 }
2379 \f
2380 /* Return false if expr can be assumed not to be an lvalue, true
2381 otherwise. */
2383 static bool
2385 {
2386 /* We only need to wrap lvalue tree codes. */
2388 {
2419 /* Assume the worst for front-end tree codes. */
2423 }
2426 }
2428 /* Return an expr equal to X but certainly not valid as an lvalue. */
2430 tree
2432 {
2433 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2434 us. */
2441 }
2443 /* When pedantic, return an expr equal to X but certainly not valid as a
2444 pedantic lvalue. Otherwise, return X. */
2446 static tree
2448 {
2450 }
2451 \f
2452 /* Given a tree comparison code, return the code that is the logical inverse.
2453 It is generally not safe to do this for floating-point comparisons, except
2454 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2455 ERROR_MARK in this case. */
2457 enum tree_code
2459 {
2465 {
2496 }
2497 }
2499 /* Similar, but return the comparison that results if the operands are
2500 swapped. This is safe for floating-point. */
2502 enum tree_code
2504 {
2506 {
2532 }
2533 }
2536 /* Convert a comparison tree code from an enum tree_code representation
2537 into a compcode bit-based encoding. This function is the inverse of
2538 compcode_to_comparison. */
2540 static enum comparison_code
2542 {
2544 {
2575 }
2576 }
2578 /* Convert a compcode bit-based encoding of a comparison operator back
2579 to GCC's enum tree_code representation. This function is the
2580 inverse of comparison_to_compcode. */
2582 static enum tree_code
2584 {
2586 {
2617 }
2618 }
2620 /* Return a tree for the comparison which is the combination of
2621 doing the AND or OR (depending on CODE) of the two operations LCODE
2622 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2623 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2624 if this makes the transformation invalid. */
2626 tree
2631 {
2638 {
2649 }
2652 {
2653 /* Eliminate unordered comparisons, as well as LTGT and ORD
2654 which are not used unless the mode has NaNs. */
2660 }
2662 {
2663 /* Check that the original operation and the optimized ones will trap
2664 under the same condition. */
2675 /* In a short-circuited boolean expression the LHS might be
2676 such that the RHS, if evaluated, will never trap. For
2677 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2678 if neither x nor y is NaN. (This is a mixed blessing: for
2679 example, the expression above will never trap, hence
2680 optimizing it to x < y would be invalid). */
2685 /* If the comparison was short-circuited, and only the RHS
2686 trapped, we may now generate a spurious trap. */
2691 /* If we changed the conditions that cause a trap, we lose. */
2694 }
2700 else
2701 {
2706 }
2707 }
2708 \f
2709 /* Return nonzero if two operands (typically of the same tree node)
2710 are necessarily equal. FLAGS modifies behavior as follows:
2712 If OEP_ONLY_CONST is set, only return nonzero for constants.
2713 This function tests whether the operands are indistinguishable;
2714 it does not test whether they are equal using C's == operation.
2715 The distinction is important for IEEE floating point, because
2716 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2717 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2719 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2720 even though it may hold multiple values during a function.
2721 This is because a GCC tree node guarantees that nothing else is
2722 executed between the evaluation of its "operands" (which may often
2723 be evaluated in arbitrary order). Hence if the operands themselves
2724 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2725 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2726 unset means assuming isochronic (or instantaneous) tree equivalence.
2727 Unless comparing arbitrary expression trees, such as from different
2728 statements, this flag can usually be left unset.
2730 If OEP_PURE_SAME is set, then pure functions with identical arguments
2731 are considered the same. It is used when the caller has other ways
2732 to ensure that global memory is unchanged in between.
2734 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2735 not values of expressions.
2737 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2738 any operand with side effect. This is unnecesarily conservative in the
2739 case we know that arg0 and arg1 are in disjoint code paths (such as in
2740 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2741 addresses with TREE_CONSTANT flag set so we know that &var == &var
2742 even if var is volatile. */
2744 int
2746 {
2747 /* When checking, verify at the outermost operand_equal_p call that
2748 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2749 hash value. */
2751 {
2753 {
2755 {
2762 }
2764 }
2765 else
2767 }
2769 /* If either is ERROR_MARK, they aren't equal. */
2775 /* Similar, if either does not have a type (like a released SSA name),
2776 they aren't equal. */
2780 /* We cannot consider pointers to different address space equal. */
2787 /* Check equality of integer constants before bailing out due to
2788 precision differences. */
2790 {
2791 /* Address of INTEGER_CST is not defined; check that we did not forget
2792 to drop the OEP_ADDRESS_OF flags. */
2795 }
2798 {
2799 /* If both types don't have the same signedness, then we can't consider
2800 them equal. We must check this before the STRIP_NOPS calls
2801 because they may change the signedness of the arguments. As pointers
2802 strictly don't have a signedness, require either two pointers or
2803 two non-pointers as well. */
2809 /* If both types don't have the same precision, then it is not safe
2810 to strip NOPs. */
2817 }
2818 #if 0
2819 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2820 sanity check once the issue is solved. */
2821 else
2822 /* Addresses of conversions and SSA_NAMEs (and many other things)
2823 are not defined. Check that we did not forget to drop the
2824 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2827 #endif
2829 /* In case both args are comparisons but with different comparison
2830 code, try to swap the comparison operands of one arg to produce
2831 a match and compare that variant. */
2835 {
2843 }
2846 {
2847 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2849 ;
2851 {
2852 /* If we are interested in comparing addresses ignore
2853 MEM_REF wrappings of the base that can appear just for
2854 TBAA reasons. */
2868 }
2869 else
2871 }
2873 /* When not checking adddresses, this is needed for conversions and for
2874 COMPONENT_REF. Might as well play it safe and always test this. */
2881 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2882 We don't care about side effects in that case because the SAVE_EXPR
2883 takes care of that for us. In all other cases, two expressions are
2884 equal if they have no side effects. If we have two identical
2885 expressions with side effects that should be treated the same due
2886 to the only side effects being identical SAVE_EXPR's, that will
2887 be detected in the recursive calls below.
2888 If we are taking an invariant address of two identical objects
2889 they are necessarily equal as well. */
2896 /* Next handle constant cases, those for which we can return 1 even
2897 if ONLY_CONST is set. */
2900 {
2914 {
2915 /* If we do not distinguish between signed and unsigned zero,
2916 consider them equal. */
2919 }
2923 {
2930 {
2934 }
2936 }
2940 flags)
2942 flags));
2953 flags | OEP_ADDRESS_OF
2956 /* In GIMPLE empty constructors are allowed in initializers of
2957 aggregates. */
2962 }
2967 /* Define macros to test an operand from arg0 and arg1 for equality and a
2968 variant that allows null and views null as being different from any
2969 non-null value. In the latter case, if either is null, the both
2970 must be; otherwise, do the normal comparison. */
2971 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2972 TREE_OPERAND (arg1, N), flags)
2974 #define OP_SAME_WITH_NULL(N) \
2975 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2976 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2979 {
2981 /* Two conversions are equal only if signedness and modes match. */
2983 {
2984 CASE_CONVERT:
2992 }
3002 /* For commutative ops, allow the other order. */
3010 /* If either of the pointer (or reference) expressions we are
3011 dereferencing contain a side effect, these cannot be equal,
3012 but their addresses can be. */
3019 {
3029 /* Require the same offset. */
3035 /* Fallthru. */
3043 {
3044 /* Require equal access sizes */
3050 flags)))
3052 /* Verify that access happens in similar types. */
3055 /* Verify that accesses are TBAA compatible. */
3064 /* Verify that alignment is compatible. */
3068 }
3071 /* TARGET_MEM_REF require equal extra operands. */
3082 /* Compare the array index by value if it is constant first as we
3083 may have different types but same value here. */
3089 /* Compare low bound and element size as with OEP_ADDRESS_OF
3090 we have to account for the offset of the ref. */
3095 array_ref_low_bound
3099 array_ref_element_size
3101 flags))));
3104 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3105 may be NULL when we're called to compare MEM_EXPRs. */
3120 }
3124 {
3126 /* Be sure we pass right ADDRESS_OF flag. */
3144 /* The multiplcation operands are commutative. */
3145 /* FALLTHRU */
3153 /* Otherwise take into account this is a commutative operation. */
3172 }
3176 {
3180 /* If not both CALL_EXPRs are either internal or normal function
3181 functions, then they are not equal. */
3184 {
3185 /* If the CALL_EXPRs call different internal functions, then they
3186 are not equal. */
3189 }
3190 else
3191 {
3192 /* If the CALL_EXPRs call different functions, then they are not
3193 equal. */
3195 flags))
3197 }
3199 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3200 {
3204 else
3208 }
3210 /* Now see if all the arguments are the same. */
3211 {
3222 /* If we get here and both argument lists are exhausted
3223 then the CALL_EXPRs are equal. */
3225 }
3228 }
3231 /* Consider __builtin_sqrt equal to sqrt. */
3239 {
3240 /* In GIMPLE constructors are used only to build vectors from
3241 elements. Individual elements in the constructor must be
3242 indexed in increasing order and form an initial sequence.
3244 We make no effort to compare constructors in generic.
3245 (see sem_variable::equals in ipa-icf which can do so for
3246 constants). */
3251 /* Be sure that vectors constructed have the same representation.
3252 We only tested element precision and modes to match.
3253 Vectors may be BLKmode and thus also check that the number of
3254 parts match. */
3267 {
3272 /* In GIMPLE the indexes can be either NULL or matching i.
3273 Double check this so we won't get false
3274 positives for GENERIC. */
3282 }
3284 }
3289 }
3291 #undef OP_SAME
3292 #undef OP_SAME_WITH_NULL
3293 }
3294 \f
3295 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3296 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3298 When in doubt, return 0. */
3300 static int
3302 {
3314 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3315 and see if the inner values are the same. This removes any
3316 signedness comparison, which doesn't matter here. */
3323 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3324 actual comparison operand, ARG0.
3326 First throw away any conversions to wider types
3327 already present in the operands. */
3336 {
3339 /* Make sure shorter operand is extended the right way
3340 to match the longer operand. */
3346 }
3349 }
3350 \f
3351 /* See if ARG is an expression that is either a comparison or is performing
3352 arithmetic on comparisons. The comparisons must only be comparing
3353 two different values, which will be stored in *CVAL1 and *CVAL2; if
3354 they are nonzero it means that some operands have already been found.
3355 No variables may be used anywhere else in the expression except in the
3356 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3357 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3359 If this is true, return 1. Otherwise, return zero. */
3361 static int
3363 {
3367 /* We can handle some of the tcc_expression cases here. */
3377 {
3378 /* If we've already found a CVAL1 or CVAL2, this expression is
3379 two complex to handle. */
3385 }
3388 {
3411 /* First see if we can handle the first operand, then the second. For
3412 the second operand, we know *CVAL1 can't be zero. It must be that
3413 one side of the comparison is each of the values; test for the
3414 case where this isn't true by failing if the two operands
3415 are the same. */
3424 ;
3428 ;
3429 else
3433 ;
3437 ;
3438 else
3445 }
3446 }
3447 \f
3448 /* ARG is a tree that is known to contain just arithmetic operations and
3449 comparisons. Evaluate the operations in the tree substituting NEW0 for
3450 any occurrence of OLD0 as an operand of a comparison and likewise for
3451 NEW1 and OLD1. */
3453 static tree
3456 {
3461 /* We can handle some of the tcc_expression cases here. */
3469 {
3484 {
3503 }
3504 /* Fall through - ??? */
3507 {
3511 /* We need to check both for exact equality and tree equality. The
3512 former will be true if the operand has a side-effect. In that
3513 case, we know the operand occurred exactly once. */
3526 }
3530 }
3531 }
3532 \f
3533 /* Return a tree for the case when the result of an expression is RESULT
3534 converted to TYPE and OMITTED was previously an operand of the expression
3535 but is now not needed (e.g., we folded OMITTED * 0).
3537 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3538 the conversion of RESULT to TYPE. */
3540 tree
3542 {
3545 /* If the resulting operand is an empty statement, just return the omitted
3546 statement casted to void. */
3556 }
3558 /* Return a tree for the case when the result of an expression is RESULT
3559 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3560 of the expression but are now not needed.
3562 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3563 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3564 evaluated before OMITTED2. Otherwise, if neither has side effects,
3565 just do the conversion of RESULT to TYPE. */
3567 tree
3570 {
3579 }
3581 \f
3582 /* Return a simplified tree node for the truth-negation of ARG. This
3583 never alters ARG itself. We assume that ARG is an operation that
3584 returns a truth value (0 or 1).
3586 FIXME: one would think we would fold the result, but it causes
3587 problems with the dominator optimizer. */
3589 static tree
3591 {
3596 /* If this is a comparison, we can simply invert it, except for
3597 floating-point non-equality comparisons, in which case we just
3598 enclose a TRUTH_NOT_EXPR around what we have. */
3601 {
3604 && flag_trapping_math
3618 }
3621 {
3640 /* Here we can invert either operand. We invert the first operand
3641 unless the second operand is a TRUTH_NOT_EXPR in which case our
3642 result is the XOR of the first operand with the inside of the
3643 negation of the second operand. */
3648 else
3671 {
3678 /* A COND_EXPR may have a throw as one operand, which
3679 then has void type. Just leave void operands
3680 as they are. */
3686 }
3698 CASE_CONVERT:
3702 /* ... fall through ... */
3724 }
3725 }
3727 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3728 assume that ARG is an operation that returns a truth value (0 or 1
3729 for scalars, 0 or -1 for vectors). Return the folded expression if
3730 folding is successful. Otherwise, return NULL_TREE. */
3732 static tree
3734 {
3737 ? BIT_NOT_EXPR
3740 }
3742 /* Return a simplified tree node for the truth-negation of ARG. This
3743 never alters ARG itself. We assume that ARG is an operation that
3744 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3746 tree
3748 {
3754 ? BIT_NOT_EXPR
3757 }
3759 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3760 with code CODE. This optimization is unsafe. */
3761 static tree
3764 {
3768 /* (A / C) +- (B / C) -> (A +- B) / C. */
3778 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3783 {
3795 }
3798 }
3799 \f
3800 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3801 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3802 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3803 is the original memory reference used to preserve the alias set of
3804 the access. */
3806 static tree
3810 {
3816 build_int_cst
3820 {
3827 }
3842 }
3844 /* Optimize a bit-field compare.
3846 There are two cases: First is a compare against a constant and the
3847 second is a comparison of two items where the fields are at the same
3848 bit position relative to the start of a chunk (byte, halfword, word)
3849 large enough to contain it. In these cases we can avoid the shift
3850 implicit in bitfield extractions.
3852 For constants, we emit a compare of the shifted constant with the
3853 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3854 compared. For two fields at the same position, we do the ANDs with the
3855 similar mask and compare the result of the ANDs.
3857 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3858 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3859 are the left and right operands of the comparison, respectively.
3861 If the optimization described above can be done, we return the resulting
3862 tree. Otherwise we return zero. */
3864 static tree
3867 {
3870 tree unsigned_type;
3877 tree mask;
3878 tree offset;
3880 /* Get all the information about the extractions being done. If the bit size
3881 if the same as the size of the underlying object, we aren't doing an
3882 extraction at all and so can do nothing. We also don't want to
3883 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3884 then will no longer be able to replace it. */
3893 else
3894 {
3895 /* If this is not a constant, we can only do something if bit positions,
3896 sizes, signedness and storage order are the same. */
3897 rinner
3905 }
3907 /* See if we can find a mode to refer to this field. We should be able to,
3908 but fail if we can't. */
3917 /* Set signed and unsigned types of the precision of this mode for the
3918 shifts below. */
3921 /* Compute the bit position and size for the new reference and our offset
3922 within it. If the new reference is the same size as the original, we
3923 won't optimize anything, so return zero. */
3933 /* Make the mask to be used against the extracted field. */
3940 /* If not comparing with constant, just rework the comparison
3941 and return. */
3945 unsigned_type,
3948 mask),
3951 unsigned_type,
3954 mask));
3956 /* Otherwise, we are handling the constant case. See if the constant is too
3957 big for the field. Warn and return a tree for 0 (false) if so. We do
3958 this not only for its own sake, but to avoid having to test for this
3959 error case below. If we didn't, we might generate wrong code.
3961 For unsigned fields, the constant shifted right by the field length should
3962 be all zero. For signed fields, the high-order bits should agree with
3963 the sign bit. */
3966 {
3968 {
3972 }
3973 }
3974 else
3975 {
3978 {
3982 }
3983 }
3985 /* Single-bit compares should always be against zero. */
3987 {
3990 }
3992 /* Make a new bitfield reference, shift the constant over the
3993 appropriate number of bits and mask it with the computed mask
3994 (in case this was a signed field). If we changed it, make a new one. */
4002 mask);
4007 }
4008 \f
4009 /* Subroutine for fold_truth_andor_1: decode a field reference.
4011 If EXP is a comparison reference, we return the innermost reference.
4013 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4014 set to the starting bit number.
4016 If the innermost field can be completely contained in a mode-sized
4017 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4019 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4020 otherwise it is not changed.
4022 *PUNSIGNEDP is set to the signedness of the field.
4024 *PREVERSEP is set to the storage order of the field.
4026 *PMASK is set to the mask used. This is either contained in a
4027 BIT_AND_EXPR or derived from the width of the field.
4029 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4031 Return 0 if this is not a component reference or is one that we can't
4032 do anything with. */
4034 static tree
4039 {
4044 tree unsigned_type;
4047 /* All the optimizations using this function assume integer fields.
4048 There are problems with FP fields since the type_for_size call
4049 below can fail for, e.g., XFmode. */
4053 /* We are interested in the bare arrangement of bits, so strip everything
4054 that doesn't affect the machine mode. However, record the type of the
4055 outermost expression if it may matter below. */
4062 {
4068 }
4079 /* If the number of bits in the reference is the same as the bitsize of
4080 the outer type, then the outer type gives the signedness. Otherwise
4081 (in case of a small bitfield) the signedness is unchanged. */
4085 /* Compute the mask to access the bitfield. */
4094 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4102 }
4104 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4105 bit positions and MASK is SIGNED. */
4107 static int
4109 {
4113 /* If this function returns true when the type of the mask is
4114 UNSIGNED, then there will be errors. In particular see
4115 gcc.c-torture/execute/990326-1.c. There does not appear to be
4116 any documentation paper trail as to why this is so. But the pre
4117 wide-int worked with that restriction and it has been preserved
4118 here. */
4123 }
4125 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4126 represents the sign bit of EXP's type. If EXP represents a sign
4127 or zero extension, also test VAL against the unextended type.
4128 The return value is the (sub)expression whose sign bit is VAL,
4129 or NULL_TREE otherwise. */
4131 tree
4133 {
4135 tree t;
4137 /* Tree EXP must have an integral type. */
4142 /* Tree VAL must be an integer constant. */
4151 /* Handle extension from a narrower type. */
4157 }
4159 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4160 to be evaluated unconditionally. */
4162 static int
4164 {
4165 /* Strip any conversions that don't change the machine mode. */
4174 /* Don't regard global variables as simple. They may be
4175 allocated in ways unknown to the compiler (shared memory,
4176 #pragma weak, etc). */
4179 /* Weakrefs are not safe to be read, since they can be NULL.
4180 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4181 have DECL_WEAK flag set. */
4183 /* Loading a static variable is unduly expensive, but global
4184 registers aren't expensive. */
4186 }
4188 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4189 to be evaluated unconditionally.
4190 I addition to simple_operand_p, we assume that comparisons, conversions,
4191 and logic-not operations are simple, if their operands are simple, too. */
4193 static bool
4195 {
4215 }
4217 \f
4218 /* The following functions are subroutines to fold_range_test and allow it to
4219 try to change a logical combination of comparisons into a range test.
4221 For example, both
4222 X == 2 || X == 3 || X == 4 || X == 5
4223 and
4224 X >= 2 && X <= 5
4225 are converted to
4226 (unsigned) (X - 2) <= 3
4228 We describe each set of comparisons as being either inside or outside
4229 a range, using a variable named like IN_P, and then describe the
4230 range with a lower and upper bound. If one of the bounds is omitted,
4231 it represents either the highest or lowest value of the type.
4233 In the comments below, we represent a range by two numbers in brackets
4234 preceded by a "+" to designate being inside that range, or a "-" to
4235 designate being outside that range, so the condition can be inverted by
4236 flipping the prefix. An omitted bound is represented by a "-". For
4237 example, "- [-, 10]" means being outside the range starting at the lowest
4238 possible value and ending at 10, in other words, being greater than 10.
4239 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4240 always false.
4242 We set up things so that the missing bounds are handled in a consistent
4243 manner so neither a missing bound nor "true" and "false" need to be
4244 handled using a special case. */
4246 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4247 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4248 and UPPER1_P are nonzero if the respective argument is an upper bound
4249 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4250 must be specified for a comparison. ARG1 will be converted to ARG0's
4251 type if both are specified. */
4253 static tree
4256 {
4257 tree tem;
4261 /* If neither arg represents infinity, do the normal operation.
4262 Else, if not a comparison, return infinity. Else handle the special
4263 comparison rules. Note that most of the cases below won't occur, but
4264 are handled for consistency. */
4267 {
4272 }
4277 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4278 for neither. In real maths, we cannot assume open ended ranges are
4279 the same. But, this is computer arithmetic, where numbers are finite.
4280 We can therefore make the transformation of any unbounded range with
4281 the value Z, Z being greater than any representable number. This permits
4282 us to treat unbounded ranges as equal. */
4286 {
4307 }
4310 }
4311 \f
4312 /* Helper routine for make_range. Perform one step for it, return
4313 new expression if the loop should continue or NULL_TREE if it should
4314 stop. */
4316 tree
4320 {
4326 {
4328 /* We can only do something if the range is testing for zero. */
4337 /* We can only do something if the range is testing for zero
4338 and if the second operand is an integer constant. Note that
4339 saying something is "in" the range we make is done by
4340 complementing IN_P since it will set in the initial case of
4341 being not equal to zero; "out" is leaving it alone. */
4348 {
4369 }
4371 /* If this is an unsigned comparison, we also know that EXP is
4372 greater than or equal to zero. We base the range tests we make
4373 on that fact, so we record it here so we can parse existing
4374 range tests. We test arg0_type since often the return type
4375 of, e.g. EQ_EXPR, is boolean. */
4377 {
4381 NULL_TREE))
4386 /* If the high bound is missing, but we have a nonzero low
4387 bound, reverse the range so it goes from zero to the low bound
4388 minus 1. */
4390 {
4395 }
4396 }
4404 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4405 low and high are non-NULL, then normalize will DTRT. */
4408 {
4413 }
4415 /* (-x) IN [a,b] -> x in [-b, -a] */
4427 /* ~ X -> -X - 1 */
4436 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4437 move a constant to the other side. */
4442 /* If EXP is signed, any overflow in the computation is undefined,
4443 so we don't worry about it so long as our computations on
4444 the bounds don't overflow. For unsigned, overflow is defined
4445 and this is exactly the right thing. */
4457 normalize:
4458 /* Check for an unsigned range which has wrapped around the maximum
4459 value thus making n_high < n_low, and normalize it. */
4461 {
4467 /* If the range is of the form +/- [ x+1, x ], we won't
4468 be able to normalize it. But then, it represents the
4469 whole range or the empty set, so make it
4470 +/- [ -, - ]. */
4474 else
4476 }
4477 else
4485 CASE_CONVERT:
4503 /* If we're converting arg0 from an unsigned type, to exp,
4504 a signed type, we will be doing the comparison as unsigned.
4505 The tests above have already verified that LOW and HIGH
4506 are both positive.
4508 So we have to ensure that we will handle large unsigned
4509 values the same way that the current signed bounds treat
4510 negative values. */
4513 {
4514 tree high_positive;
4515 tree equiv_type;
4516 /* For fixed-point modes, we need to pass the saturating flag
4517 as the 2nd parameter. */
4519 equiv_type
4522 else
4523 equiv_type
4526 /* A range without an upper bound is, naturally, unbounded.
4527 Since convert would have cropped a very large value, use
4528 the max value for the destination type. */
4529 high_positive
4536 high_positive),
4539 /* If the low bound is specified, "and" the range with the
4540 range for which the original unsigned value will be
4541 positive. */
4543 {
4546 integer_zero_node),
4547 high_positive))
4551 }
4552 else
4553 {
4554 /* Otherwise, "or" the range with the range of the input
4555 that will be interpreted as negative. */
4558 integer_zero_node),
4559 high_positive))
4563 }
4564 }
4573 }
4574 }
4576 /* Given EXP, a logical expression, set the range it is testing into
4577 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4578 actually being tested. *PLOW and *PHIGH will be made of the same
4579 type as the returned expression. If EXP is not a comparison, we
4580 will most likely not be returning a useful value and range. Set
4581 *STRICT_OVERFLOW_P to true if the return value is only valid
4582 because signed overflow is undefined; otherwise, do not change
4583 *STRICT_OVERFLOW_P. */
4585 tree
4588 {
4596 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4597 and see if we can refine the range. Some of the cases below may not
4598 happen, but it doesn't seem worth worrying about this. We "continue"
4599 the outer loop when we've changed something; otherwise we "break"
4600 the switch, which will "break" the while. */
4606 {
4612 {
4620 }
4629 }
4631 /* If EXP is a constant, we can evaluate whether this is true or false. */
4633 {
4640 }
4644 }
4645 \f
4646 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4647 type, TYPE, return an expression to test if EXP is in (or out of, depending
4648 on IN_P) the range. Return 0 if the test couldn't be created. */
4650 tree
4653 {
4656 /* Disable this optimization for function pointer expressions
4657 on targets that require function pointer canonicalization. */
4664 {
4670 }
4688 {
4690 {
4694 }
4696 }
4698 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4700 {
4704 {
4706 {
4709 etype
4711 else
4714 }
4717 }
4718 }
4720 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4721 This requires wrap-around arithmetics for the type of the expression.
4722 First make sure that arithmetics in this type is valid, then make sure
4723 that it wraps around. */
4729 {
4732 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4733 for the type in question, as we rely on this here. */
4743 else
4745 }
4755 {
4757 {
4762 }
4764 }
4772 }
4773 \f
4774 /* Return the predecessor of VAL in its type, handling the infinite case. */
4776 static tree
4778 {
4784 else
4787 }
4789 /* Return the successor of VAL in its type, handling the infinite case. */
4791 static tree
4793 {
4799 else
4802 }
4804 /* Given two ranges, see if we can merge them into one. Return 1 if we
4805 can, 0 if we can't. Set the output range into the specified parameters. */
4807 bool
4810 {
4814 tree tem;
4824 /* Make range 0 be the range that starts first, or ends last if they
4825 start at the same value. Swap them if it isn't. */
4828 || (lowequal
4831 {
4835 }
4837 /* Now flag two cases, whether the ranges are disjoint or whether the
4838 second range is totally subsumed in the first. Note that the tests
4839 below are simplified by the ones above. */
4845 /* We now have four cases, depending on whether we are including or
4846 excluding the two ranges. */
4848 {
4849 /* If they don't overlap, the result is false. If the second range
4850 is a subset it is the result. Otherwise, the range is from the start
4851 of the second to the end of the first. */
4856 else
4858 }
4861 {
4862 /* If they don't overlap, the result is the first range. If they are
4863 equal, the result is false. If the second range is a subset of the
4864 first, and the ranges begin at the same place, we go from just after
4865 the end of the second range to the end of the first. If the second
4866 range is not a subset of the first, or if it is a subset and both
4867 ranges end at the same place, the range starts at the start of the
4868 first range and ends just before the second range.
4869 Otherwise, we can't describe this as a single range. */
4875 {
4880 {
4881 /* We are in the weird situation where high0 > high1 but
4882 high1 has no successor. Punt. */
4884 }
4885 }
4887 {
4892 {
4893 /* low0 < low1 but low1 has no predecessor. Punt. */
4895 }
4896 }
4897 else
4899 }
4902 {
4903 /* If they don't overlap, the result is the second range. If the second
4904 is a subset of the first, the result is false. Otherwise,
4905 the range starts just after the first range and ends at the
4906 end of the second. */
4911 else
4912 {
4917 {
4918 /* high1 > high0 but high0 has no successor. Punt. */
4920 }
4921 }
4922 }
4924 else
4925 {
4926 /* The case where we are excluding both ranges. Here the complex case
4927 is if they don't overlap. In that case, the only time we have a
4928 range is if they are adjacent. If the second is a subset of the
4929 first, the result is the first. Otherwise, the range to exclude
4930 starts at the beginning of the first range and ends at the end of the
4931 second. */
4933 {
4938 else
4939 {
4940 /* Canonicalize - [min, x] into - [-, x]. */
4943 {
4948 /* FALLTHROUGH */
4961 }
4963 /* Canonicalize - [x, max] into - [x, -]. */
4966 {
4971 /* FALLTHROUGH */
4987 }
4989 /* The ranges might be also adjacent between the maximum and
4990 minimum values of the given type. For
4991 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4992 return + [x + 1, y - 1]. */
4994 {
5001 }
5002 else
5004 }
5005 }
5008 else
5010 }
5014 }
5015 \f
5017 /* Subroutine of fold, looking inside expressions of the form
5018 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5019 of the COND_EXPR. This function is being used also to optimize
5020 A op B ? C : A, by reversing the comparison first.
5022 Return a folded expression whose code is not a COND_EXPR
5023 anymore, or NULL_TREE if no folding opportunity is found. */
5025 static tree
5028 {
5033 tree tem;
5038 /* If we have A op 0 ? A : -A, consider applying the following
5039 transformations:
5041 A == 0? A : -A same as -A
5042 A != 0? A : -A same as A
5043 A >= 0? A : -A same as abs (A)
5044 A > 0? A : -A same as abs (A)
5045 A <= 0? A : -A same as -abs (A)
5046 A < 0? A : -A same as -abs (A)
5048 None of these transformations work for modes with signed
5049 zeros. If A is +/-0, the first two transformations will
5050 change the sign of the result (from +0 to -0, or vice
5051 versa). The last four will fix the sign of the result,
5052 even though the original expressions could be positive or
5053 negative, depending on the sign of A.
5055 Note that all these transformations are correct if A is
5056 NaN, since the two alternatives (A and -A) are also NaNs. */
5063 /* In the case that A is of the form X-Y, '-A' (arg2) may
5064 have already been folded to Y-X, check for that. */
5072 {
5086 /* Fall through. */
5106 }
5108 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5109 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5110 both transformations are correct when A is NaN: A != 0
5111 is then true, and A == 0 is false. */
5115 {
5120 }
5122 /* Try some transformations of A op B ? A : B.
5124 A == B? A : B same as B
5125 A != B? A : B same as A
5126 A >= B? A : B same as max (A, B)
5127 A > B? A : B same as max (B, A)
5128 A <= B? A : B same as min (A, B)
5129 A < B? A : B same as min (B, A)
5131 As above, these transformations don't work in the presence
5132 of signed zeros. For example, if A and B are zeros of
5133 opposite sign, the first two transformations will change
5134 the sign of the result. In the last four, the original
5135 expressions give different results for (A=+0, B=-0) and
5136 (A=-0, B=+0), but the transformed expressions do not.
5138 The first two transformations are correct if either A or B
5139 is a NaN. In the first transformation, the condition will
5140 be false, and B will indeed be chosen. In the case of the
5141 second transformation, the condition A != B will be true,
5142 and A will be chosen.
5144 The conversions to max() and min() are not correct if B is
5145 a number and A is not. The conditions in the original
5146 expressions will be false, so all four give B. The min()
5147 and max() versions would give a NaN instead. */
5150 /* Avoid these transformations if the COND_EXPR may be used
5151 as an lvalue in the C++ front-end. PR c++/19199. */
5152 && (in_gimple_form
5158 {
5163 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5165 {
5169 }
5172 {
5181 /* In C++ a ?: expression can be an lvalue, so put the
5182 operand which will be used if they are equal first
5183 so that we can convert this back to the
5184 corresponding COND_EXPR. */
5186 {
5195 }
5202 {
5211 }
5226 }
5227 }
5229 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5230 we might still be able to simplify this. For example,
5231 if C1 is one less or one more than C2, this might have started
5232 out as a MIN or MAX and been transformed by this function.
5233 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5239 {
5243 /* We can replace A with C1 in this case. */
5248 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5249 MIN_EXPR, to preserve the signedness of the comparison. */
5251 OEP_ONLY_CONST)
5255 OEP_ONLY_CONST))
5256 {
5259 arg2));
5262 }
5266 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5267 as above. */
5269 OEP_ONLY_CONST)
5273 OEP_ONLY_CONST))
5274 {
5277 arg2));
5280 }
5284 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5285 MAX_EXPR, to preserve the signedness of the comparison. */
5287 OEP_ONLY_CONST)
5291 OEP_ONLY_CONST))
5292 {
5295 arg2));
5297 }
5301 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5303 OEP_ONLY_CONST)
5307 OEP_ONLY_CONST))
5308 {
5311 arg2));
5313 }
5319 }
5322 }
5325 \f
5326 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5327 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5328 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5329 false) >= 2)
5330 #endif
5332 /* EXP is some logical combination of boolean tests. See if we can
5333 merge it into some range test. Return the new tree if so. */
5335 static tree
5338 {
5354 /* If this is an OR operation, invert both sides; we will invert
5355 again at the end. */
5359 /* If both expressions are the same, if we can merge the ranges, and we
5360 can build the range test, return it or it inverted. If one of the
5361 ranges is always true or always false, consider it to be the same
5362 expression as the other. */
5370 {
5374 }
5376 /* On machines where the branch cost is expensive, if this is a
5377 short-circuited branch and the underlying object on both sides
5378 is the same, make a non-short-circuit operation. */
5384 {
5385 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5386 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5387 which cases we can't do this. */
5395 {
5404 {
5407 WARN_STRICT_OVERFLOW_COMPARISON);
5411 }
5412 }
5413 }
5416 }
5417 \f
5418 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5419 bit value. Arrange things so the extra bits will be set to zero if and
5420 only if C is signed-extended to its full width. If MASK is nonzero,
5421 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5423 static tree
5425 {
5428 tree temp;
5433 /* We work by getting just the sign bit into the low-order bit, then
5434 into the high-order bit, then sign-extend. We then XOR that value
5435 with C. */
5438 /* We must use a signed type in order to get an arithmetic right shift.
5439 However, we must also avoid introducing accidental overflows, so that
5440 a subsequent call to integer_zerop will work. Hence we must
5441 do the type conversion here. At this point, the constant is either
5442 zero or one, and the conversion to a signed type can never overflow.
5443 We could get an overflow if this conversion is done anywhere else. */
5452 /* If necessary, convert the type back to match the type of C. */
5457 }
5458 \f
5459 /* For an expression that has the form
5460 (A && B) || ~B
5461 or
5462 (A || B) && ~B,
5463 we can drop one of the inner expressions and simplify to
5464 A || ~B
5465 or
5466 A && ~B
5467 LOC is the location of the resulting expression. OP is the inner
5468 logical operation; the left-hand side in the examples above, while CMPOP
5469 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5470 removing a condition that guards another, as in
5471 (A != NULL && A->...) || A == NULL
5472 which we must not transform. If RHS_ONLY is true, only eliminate the
5473 right-most operand of the inner logical operation. */
5475 static tree
5478 {
5496 {
5499 {
5502 }
5503 }
5505 {
5508 {
5511 }
5512 }
5527 }
5529 /* Find ways of folding logical expressions of LHS and RHS:
5530 Try to merge two comparisons to the same innermost item.
5531 Look for range tests like "ch >= '0' && ch <= '9'".
5532 Look for combinations of simple terms on machines with expensive branches
5533 and evaluate the RHS unconditionally.
5535 For example, if we have p->a == 2 && p->b == 4 and we can make an
5536 object large enough to span both A and B, we can do this with a comparison
5537 against the object ANDed with the a mask.
5539 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5540 operations to do this with one comparison.
5542 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5543 function and the one above.
5545 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5546 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5548 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5549 two operands.
5551 We return the simplified tree or 0 if no optimization is possible. */
5553 static tree
5556 {
5557 /* If this is the "or" of two comparisons, we can do something if
5558 the comparisons are NE_EXPR. If this is the "and", we can do something
5559 if the comparisons are EQ_EXPR. I.e.,
5560 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5562 WANTED_CODE is this operation code. For single bit fields, we can
5563 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5564 comparison for one-bit fields. */
5585 /* Start by getting the comparison codes. Fail if anything is volatile.
5586 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5587 it were surrounded with a NE_EXPR. */
5596 {
5600 }
5603 {
5607 }
5618 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5621 {
5624 {
5629 }
5632 {
5638 }
5639 }
5644 /* If the RHS can be evaluated unconditionally and its operands are
5645 simple, it wins to evaluate the RHS unconditionally on machines
5646 with expensive branches. In this case, this isn't a comparison
5647 that can be merged. */
5654 {
5655 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5666 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5676 }
5678 /* See if the comparisons can be merged. Then get all the parameters for
5679 each side. */
5704 /* It must be true that the inner operation on the lhs of each
5705 comparison must be the same if we are to be able to do anything.
5706 Then see if we have constants. If not, the same must be true for
5707 the rhs's. */
5716 {
5719 }
5724 else
5727 /* If either comparison code is not correct for our logical operation,
5728 fail. However, we can convert a one-bit comparison against zero into
5729 the opposite comparison against that bit being set in the field. */
5733 {
5735 {
5736 /* Make the left operand unsigned, since we are only interested
5737 in the value of one bit. Otherwise we are doing the wrong
5738 thing below. */
5741 }
5742 else
5744 }
5746 /* This is analogous to the code for l_const above. */
5748 {
5750 {
5753 }
5754 else
5756 }
5758 /* See if we can find a mode that contains both fields being compared on
5759 the left. If we can't, fail. Otherwise, update all constants and masks
5760 to be relative to a field of that size. */
5765 volatilep);
5775 {
5778 }
5786 {
5793 {
5797 }
5798 }
5800 {
5807 {
5811 }
5812 }
5814 /* If the right sides are not constant, do the same for it. Also,
5815 disallow this optimization if a size or signedness mismatch occurs
5816 between the left and right sides. */
5818 {
5821 /* Make sure the two fields on the right
5822 correspond to the left without being swapped. */
5830 volatilep);
5840 {
5843 }
5852 /* Make a mask that corresponds to both fields being compared.
5853 Do this for both items being compared. If the operands are the
5854 same size and the bits being compared are in the same position
5855 then we can do this by masking both and comparing the masked
5856 results. */
5860 {
5874 }
5876 /* There is still another way we can do something: If both pairs of
5877 fields being compared are adjacent, we may be able to make a wider
5878 field containing them both.
5880 Note that we still must mask the lhs/rhs expressions. Furthermore,
5881 the mask must be shifted to account for the shift done by
5882 make_bit_field_ref. */
5887 {
5888 tree type;
5904 /* Convert to the smaller type before masking out unwanted bits. */
5907 {
5909 {
5913 }
5915 {
5919 }
5920 }
5929 }
5932 }
5934 /* Handle the case of comparisons with constants. If there is something in
5935 common between the masks, those bits of the constants must be the same.
5936 If not, the condition is always false. Test for this to avoid generating
5937 incorrect code below. */
5942 {
5944 {
5947 }
5948 else
5949 {
5952 }
5953 }
5955 /* Construct the expression we will return. First get the component
5956 reference we will make. Unless the mask is all ones the width of
5957 that field, perform the mask operation. Then compare with the
5958 merged constant. */
5969 }
5970 \f
5971 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5972 constant. */
5974 static tree
5977 {
5980 tree comp_const;
5981 tree minmax_const;
5983 tree inner;
5994 /* If something does not permit us to optimize, return the original tree. */
6002 /* Now handle all the various comparison codes. We only handle EQ_EXPR
6003 and GT_EXPR, doing the rest with recursive calls using logical
6004 simplifications. */
6006 {
6008 {
6009 tree tem
6016 }
6019 return
6021 optimize_minmax_comparison
6023 optimize_minmax_comparison
6028 /* MAX (X, 0) == 0 -> X <= 0 */
6032 /* MAX (X, 0) == 5 -> X == 5 */
6036 /* MAX (X, 0) == -1 -> false */
6040 /* MIN (X, 0) == 0 -> X >= 0 */
6044 /* MIN (X, 0) == 5 -> false */
6047 else
6048 /* MIN (X, 0) == -1 -> X == -1 */
6053 /* MAX (X, 0) > 0 -> X > 0
6054 MAX (X, 0) > 5 -> X > 5 */
6058 /* MAX (X, 0) > -1 -> true */
6062 /* MIN (X, 0) > 0 -> false
6063 MIN (X, 0) > 5 -> false */
6066 else
6067 /* MIN (X, 0) > -1 -> X > -1 */
6072 }
6073 }
6074 \f
6075 /* T is an integer expression that is being multiplied, divided, or taken a
6076 modulus (CODE says which and what kind of divide or modulus) by a
6077 constant C. See if we can eliminate that operation by folding it with
6078 other operations already in T. WIDE_TYPE, if non-null, is a type that
6079 should be used for the computation if wider than our type.
6081 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6082 (X * 2) + (Y * 4). We must, however, be assured that either the original
6083 expression would not overflow or that overflow is undefined for the type
6084 in the language in question.
6086 If we return a non-null expression, it is an equivalent form of the
6087 original computation, but need not be in the original type.
6089 We set *STRICT_OVERFLOW_P to true if the return values depends on
6090 signed overflow being undefined. Otherwise we do not change
6091 *STRICT_OVERFLOW_P. */
6093 static tree
6096 {
6097 /* To avoid exponential search depth, refuse to allow recursion past
6098 three levels. Beyond that (1) it's highly unlikely that we'll find
6099 something interesting and (2) we've probably processed it before
6100 when we built the inner expression. */
6103 tree ret;
6108 depth++;
6110 depth--;
6113 }
6115 static tree
6118 {
6129 /* Don't deal with constants of zero here; they confuse the code below. */
6139 /* Note that we need not handle conditional operations here since fold
6140 already handles those cases. So just do arithmetic here. */
6142 {
6144 /* For a constant, we can always simplify if we are a multiply
6145 or (for divide and modulus) if it is a multiple of our constant. */
6148 {
6151 /* If the multiplication overflowed, we lost information on it.
6152 See PR68142 and PR69845. */
6156 }
6160 /* If op0 is an expression ... */
6166 /* ... and has wrapping overflow, and its type is smaller
6167 than ctype, then we cannot pass through as widening. */
6172 /* ... or this is a truncation (t is narrower than op0),
6173 then we cannot pass through this narrowing. */
6176 /* ... or signedness changes for division or modulus,
6177 then we cannot pass through this conversion. */
6181 /* ... or has undefined overflow while the converted to
6182 type has not, we cannot do the operation in the inner type
6183 as that would introduce undefined overflow. */
6189 /* Pass the constant down and see if we can make a simplification. If
6190 we can, replace this expression with the inner simplification for
6191 possible later conversion to our or some other type. */
6196 code == MULT_EXPR
6198 strict_overflow_p))))
6203 /* If widening the type changes it from signed to unsigned, then we
6204 must avoid building ABS_EXPR itself as unsigned. */
6206 {
6210 {
6213 }
6215 }
6216 /* If the constant is negative, we cannot simplify this. */
6219 /* FALLTHROUGH */
6221 /* For division and modulus, type can't be unsigned, as e.g.
6222 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6223 For signed types, even with wrapping overflow, this is fine. */
6232 /* If widening the type changes the signedness, then we can't perform
6233 this optimization as that changes the result. */
6237 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6243 {
6250 }
6254 /* If the second operand is constant, this is a multiplication
6255 or floor division, by a power of two, so we can treat it that
6256 way unless the multiplier or divisor overflows. Signed
6257 left-shift overflow is implementation-defined rather than
6258 undefined in C90, so do not convert signed left shift into
6259 multiplication. */
6262 /* const_binop may not detect overflow correctly,
6263 so check for it explicitly here. */
6267 size_one_node,
6268 op1)))
6272 ctype,
6274 t1),
6279 /* See if we can eliminate the operation on both sides. If we can, we
6280 can return a new PLUS or MINUS. If we can't, the only remaining
6281 cases where we can do anything are if the second operand is a
6282 constant. */
6288 /* If not multiplication, we can only do this if both operands
6289 are divisible by c. */
6292 {
6297 }
6299 /* If this was a subtraction, negate OP1 and set it to be an addition.
6300 This simplifies the logic below. */
6302 {
6304 /* If OP1 was not easily negatable, the constant may be OP0. */
6306 {
6309 }
6310 }
6315 /* If either OP1 or C are negative, this optimization is not safe for
6316 some of the division and remainder types while for others we need
6317 to change the code. */
6319 {
6327 }
6329 /* If it's a multiply or a division/modulus operation of a multiple
6330 of our constant, do the operation and verify it doesn't overflow. */
6333 {
6336 /* We allow the constant to overflow with wrapping semantics. */
6340 }
6341 else
6344 /* If we have an unsigned type, we cannot widen the operation since it
6345 will change the result if the original computation overflowed. */
6349 /* If we were able to eliminate our operation from the first side,
6350 apply our operation to the second side and reform the PLUS. */
6354 /* The last case is if we are a multiply. In that case, we can
6355 apply the distributive law to commute the multiply and addition
6356 if the multiplication of the constants doesn't overflow
6357 and overflow is defined. With undefined overflow
6358 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6364 op1);
6369 /* We have a special case here if we are doing something like
6370 (C * 8) % 4 since we know that's zero. */
6373 /* If the multiplication can overflow we cannot optimize this. */
6377 {
6380 }
6382 /* ... fall through ... */
6386 /* If we can extract our operation from the LHS, do so and return a
6387 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6388 do something only if the second operand is a constant. */
6402 /* If these are the same operation types, we can associate them
6403 assuming no overflow. */
6405 {
6420 }
6422 /* If these operations "cancel" each other, we have the main
6423 optimizations of this pass, which occur when either constant is a
6424 multiple of the other, in which case we replace this with either an
6425 operation or CODE or TCODE.
6427 If we have an unsigned type, we cannot do this since it will change
6428 the result if the original computation overflowed. */
6435 {
6437 {
6444 }
6446 {
6453 }
6454 }
6459 }
6462 }
6463 \f
6464 /* Return a node which has the indicated constant VALUE (either 0 or
6465 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6466 and is of the indicated TYPE. */
6468 tree
6470 {
6479 else
6481 }
6484 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6485 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6486 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6487 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6488 COND is the first argument to CODE; otherwise (as in the example
6489 given here), it is the second argument. TYPE is the type of the
6490 original expression. Return NULL_TREE if no simplification is
6491 possible. */
6493 static tree
6498 {
6508 {
6512 /* If this operand throws an expression, then it does not make
6513 sense to try to perform a logical or arithmetic operation
6514 involving it. */
6519 }
6522 {
6527 }
6528 else
6529 /* Detect the case of mixing vector and scalar types - bail out. */
6535 /* This transformation is only worthwhile if we don't have to wrap ARG
6536 in a SAVE_EXPR and the operation can be simplified without recursing
6537 on at least one of the branches once its pushed inside the COND_EXPR. */
6546 {
6550 else
6552 }
6554 {
6558 else
6560 }
6562 /* Check that we have simplified at least one of the branches. */
6567 }
6569 \f
6570 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6572 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6573 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6574 ADDEND is the same as X.
6576 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6577 and finite. The problematic cases are when X is zero, and its mode
6578 has signed zeros. In the case of rounding towards -infinity,
6579 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6580 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6582 bool
6584 {
6588 /* Don't allow the fold with -fsignaling-nans. */
6592 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6596 /* In a vector or complex, we would need to check the sign of all zeros. */
6600 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6604 /* The mode has signed zeros, and we have to honor their sign.
6605 In this situation, there is only one case we can return true for.
6606 X - 0 is the same as X unless rounding towards -infinity is
6607 supported. */
6609 }
6611 /* Subroutine of fold() that optimizes comparisons of a division by
6612 a nonzero integer constant against an integer constant, i.e.
6613 X/C1 op C2.
6615 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6616 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6617 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6619 The function returns the constant folded tree if a simplification
6620 can be made, and NULL_TREE otherwise. */
6622 static tree
6625 {
6633 /* We have to do this the hard way to detect unsigned overflow.
6634 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6640 {
6645 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6649 }
6651 {
6655 {
6674 }
6675 }
6676 else
6677 {
6678 /* A negative divisor reverses the relational operators. */
6684 {
6703 }
6704 }
6707 {
6728 {
6731 }
6736 {
6739 }
6744 {
6747 }
6752 {
6755 }
6760 }
6763 }
6766 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6767 equality/inequality test, then return a simplified form of the test
6768 using a sign testing. Otherwise return NULL. TYPE is the desired
6769 result type. */
6771 static tree
6774 tree result_type)
6775 {
6776 /* If this is testing a single bit, we can optimize the test. */
6780 {
6781 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6782 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6786 /* This is only a win if casting to a signed type is cheap,
6787 i.e. when arg00's type is not a partial mode. */
6790 {
6793 result_type,
6796 }
6797 }
6800 }
6802 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6803 equality/inequality test, then return a simplified form of
6804 the test using shifts and logical operations. Otherwise return
6805 NULL. TYPE is the desired result type. */
6807 tree
6810 {
6811 /* If this is testing a single bit, we can optimize the test. */
6815 {
6824 /* First, see if we can fold the single bit test into a sign-bit
6825 test. */
6827 result_type);
6831 /* Otherwise we have (A & C) != 0 where C is a single bit,
6832 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6833 Similarly for (A & C) == 0. */
6835 /* If INNER is a right shift of a constant and it plus BITNUM does
6836 not overflow, adjust BITNUM and INNER. */
6842 {
6845 }
6847 /* If we are going to be able to omit the AND below, we must do our
6848 operations as unsigned. If we must use the AND, we have a choice.
6849 Normally unsigned is faster, but for some machines signed is. */
6867 /* Put the AND last so it can combine with more things. */
6870 /* Make sure to return the proper type. */
6874 }
6876 }
6878 /* Check whether we are allowed to reorder operands arg0 and arg1,
6879 such that the evaluation of arg1 occurs before arg0. */
6881 static bool
6883 {
6890 }
6892 /* Test whether it is preferable two swap two operands, ARG0 and
6893 ARG1, for example because ARG0 is an integer constant and ARG1
6894 isn't. If REORDER is true, only recommend swapping if we can
6895 evaluate the operands in reverse order. */
6897 bool
6899 {
6917 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6918 for commutative and comparison operators. Ensuring a canonical
6919 form allows the optimizers to find additional redundancies without
6920 having to explicitly check for both orderings. */
6926 /* Put SSA_NAMEs last. */
6932 /* Put variables last. */
6939 }
6942 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6943 means A >= Y && A != MAX, but in this case we know that
6944 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6946 static tree
6948 {
6955 else
6964 {
6967 }
6969 {
6972 }
6973 else
6980 {
6981 /* Convert the pointer types into integer before taking the difference. */
6985 }
6986 else
6993 }
6995 /* Fold a sum or difference of at least one multiplication.
6996 Returns the folded tree or NULL if no simplification could be made. */
6998 static tree
7001 {
7005 /* (A * C) +- (B * C) -> (A+-B) * C.
7006 (A * C) +- A -> A * (C+-1).
7007 We are most concerned about the case where C is a constant,
7008 but other combinations show up during loop reduction. Since
7009 it is not difficult, try all four possibilities. */
7012 {
7015 }
7017 {
7020 }
7021 else
7022 {
7023 /* We cannot generate constant 1 for fract. */
7028 }
7030 {
7033 }
7035 {
7037 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7038 the purpose of this canonicalization. */
7042 {
7045 }
7046 else
7048 }
7049 else
7050 {
7051 /* We cannot generate constant 1 for fract. */
7056 }
7068 /* No identical multiplicands; see if we can find a common
7069 power-of-two factor in non-power-of-two multiplies. This
7070 can help in multi-dimensional array access. */
7073 {
7076 tree maybe_same;
7080 /* Move min of absolute values to int11. */
7082 {
7087 }
7088 else
7092 /* The remainder should not be a constant, otherwise we
7093 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7094 increased the number of multiplications necessary. */
7096 {
7104 }
7105 }
7115 }
7117 /* Subroutine of native_encode_expr. Encode the INTEGER_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 {
7138 {
7140 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7141 number of bytes. */
7145 {
7152 else
7154 }
7155 else
7160 }
7162 }
7165 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7166 specified by EXPR into the buffer PTR of length LEN bytes.
7167 Return the number of bytes placed in the buffer, or zero
7168 upon failure. */
7170 static int
7172 {
7176 FIXED_VALUE_TYPE value;
7192 }
7195 /* Subroutine of native_encode_expr. Encode the REAL_CST
7196 specified by EXPR into the buffer PTR of length LEN bytes.
7197 Return the number of bytes placed in the buffer, or zero
7198 upon failure. */
7200 static int
7202 {
7208 /* There are always 32 bits in each long, no matter the size of
7209 the hosts long. We handle floating point representations with
7210 up to 192 bits. */
7224 {
7229 {
7236 else
7238 }
7239 else
7245 }
7247 }
7249 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7250 specified by EXPR into the buffer PTR of length LEN bytes.
7251 Return the number of bytes placed in the buffer, or zero
7252 upon failure. */
7254 static int
7256 {
7258 tree part;
7273 }
7276 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7277 specified by EXPR into the buffer PTR of length LEN bytes.
7278 Return the number of bytes placed in the buffer, or zero
7279 upon failure. */
7281 static int
7283 {
7293 {
7295 {
7298 }
7309 }
7311 }
7314 /* Subroutine of native_encode_expr. Encode the STRING_CST
7315 specified by EXPR into the buffer PTR of length LEN bytes.
7316 Return the number of bytes placed in the buffer, or zero
7317 upon failure. */
7319 static int
7321 {
7323 HOST_WIDE_INT total_bytes;
7337 {
7340 {
7343 }
7346 }
7347 else
7350 }
7353 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7354 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7355 buffer PTR of length LEN bytes. If OFF is not -1 then start
7356 the encoding at byte offset OFF and encode at most LEN bytes.
7357 Return the number of bytes placed in the buffer, or zero upon failure. */
7359 int
7361 {
7362 /* We don't support starting at negative offset and -1 is special. */
7367 {
7388 }
7389 }
7392 /* Subroutine of native_interpret_expr. Interpret the contents of
7393 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7394 If the buffer cannot be interpreted, return NULL_TREE. */
7396 static tree
7398 {
7408 }
7411 /* Subroutine of native_interpret_expr. Interpret the contents of
7412 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7413 If the buffer cannot be interpreted, return NULL_TREE. */
7415 static tree
7417 {
7419 double_int result;
7420 FIXED_VALUE_TYPE fixed_value;
7430 }
7433 /* Subroutine of native_interpret_expr. Interpret the contents of
7434 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7435 If the buffer cannot be interpreted, return NULL_TREE. */
7437 static tree
7439 {
7443 /* There are always 32 bits in each long, no matter the size of
7444 the hosts long. We handle floating point representations with
7445 up to 192 bits. */
7446 REAL_VALUE_TYPE r;
7457 {
7458 /* Both OFFSET and BYTE index within a long;
7459 bitpos indexes the whole float. */
7462 {
7469 else
7471 }
7472 else
7473 {
7476 {
7477 /* Reverse bytes within each long, or within the entire float
7478 if it's smaller than a long (for HFmode). */
7481 }
7482 }
7486 }
7490 }
7493 /* Subroutine of native_interpret_expr. Interpret the contents of
7494 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7495 If the buffer cannot be interpreted, return NULL_TREE. */
7497 static tree
7499 {
7514 }
7517 /* Subroutine of native_interpret_expr. Interpret the contents of
7518 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7519 If the buffer cannot be interpreted, return NULL_TREE. */
7521 static tree
7523 {
7536 {
7541 }
7543 }
7546 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7547 the buffer PTR of length LEN as a constant of type TYPE. For
7548 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7549 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7550 return NULL_TREE. */
7552 tree
7554 {
7556 {
7578 }
7579 }
7581 /* Returns true if we can interpret the contents of a native encoding
7582 as TYPE. */
7584 static bool
7586 {
7588 {
7601 }
7602 }
7604 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7605 TYPE at compile-time. If we're unable to perform the conversion
7606 return NULL_TREE. */
7608 static tree
7610 {
7611 /* We support up to 512-bit values (for V8DFmode). */
7615 /* Check that the host and target are sane. */
7624 }
7626 /* Build an expression for the address of T. Folds away INDIRECT_REF
7627 to avoid confusing the gimplify process. */
7629 tree
7631 {
7632 /* The size of the object is not relevant when talking about its address. */
7637 {
7642 }
7652 {
7657 }
7658 else
7662 }
7664 /* Build an expression for the address of T. */
7666 tree
7668 {
7672 }
7674 /* Fold a unary expression of code CODE and type TYPE with operand
7675 OP0. Return the folded expression if folding is successful.
7676 Otherwise, return NULL_TREE. */
7678 tree
7680 {
7681 tree tem;
7682 tree arg0;
7690 {
7693 {
7694 /* Don't use STRIP_NOPS, because signedness of argument type
7695 matters. */
7697 }
7698 else
7699 {
7700 /* Strip any conversions that don't change the mode. This
7701 is safe for every expression, except for a comparison
7702 expression because its signedness is derived from its
7703 operands.
7705 Note that this is done as an internal manipulation within
7706 the constant folder, in order to find the simplest
7707 representation of the arguments so that their form can be
7708 studied. In any cases, the appropriate type conversions
7709 should be put back in the tree that will get out of the
7710 constant folder. */
7712 }
7715 {
7718 {
7722 }
7723 }
7724 }
7731 {
7738 {
7752 /* If this was a conversion, and all we did was to move into
7753 inside the COND_EXPR, bring it back out. But leave it if
7754 it is a conversion from integer to integer and the
7755 result precision is no wider than a word since such a
7756 conversion is cheap and may be optimized away by combine,
7757 while it couldn't if it were outside the COND_EXPR. Then return
7758 so we don't get into an infinite recursion loop taking the
7759 conversion out and then back in. */
7771 && (INTEGRAL_TYPE_P
7784 }
7785 }
7788 {
7794 CASE_CONVERT:
7798 {
7799 /* If we have (type) (a CMP b) and type is an integral type, return
7800 new expression involving the new type. Canonicalize
7801 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7802 non-integral type.
7803 Do not fold the result as that would not simplify further, also
7804 folding again results in recursions. */
7814 }
7816 /* Handle (T *)&A.B.C for A being of type T and B and C
7817 living at offset zero. This occurs frequently in
7818 C++ upcasting and then accessing the base. */
7822 {
7824 tree offset;
7825 machine_mode mode;
7827 tree base
7831 /* If the reference was to a (constant) zero offset, we can use
7832 the address of the base if it has the same base type
7833 as the result type and the pointer type is unqualified. */
7840 }
7844 /* Detect assigning a bitfield. */
7846 && DECL_BIT_FIELD
7848 {
7849 /* Don't leave an assignment inside a conversion
7850 unless assigning a bitfield. */
7852 /* First do the assignment, then return converted constant. */
7857 }
7859 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7860 constants (if x has signed type, the sign bit cannot be set
7861 in c). This folds extension into the BIT_AND_EXPR.
7862 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7863 very likely don't have maximal range for their precision and this
7864 transformation effectively doesn't preserve non-maximal ranges. */
7868 {
7879 <= HOST_BITS_PER_WIDE_INT
7881 {
7885 cst &= HOST_WIDE_INT_M1U
7889 && !flag_syntax_only
7892 {
7896 }
7897 }
7899 {
7904 }
7905 }
7907 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7908 cast (T1)X will fold away. We assume that this happens when X itself
7909 is a cast. */
7913 {
7917 return fold_build_pointer_plus_loc
7919 }
7921 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7922 of the same precision, and X is an integer type not narrower than
7923 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7929 {
7935 }
7937 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7938 type of X and Y (integer types only). */
7943 {
7944 /* Be careful not to introduce new overflows. */
7945 tree mult_type;
7948 else
7952 {
7959 }
7960 }
7966 {
7971 }
7982 /* Convert fabs((double)float) into (double)fabsf(float). */
7985 {
7991 targ0));
7992 }
7996 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8015 /* Note that the operand of this must be an int
8016 and its values must be 0 or 1.
8017 ("true" is a fixed value perhaps depending on the language,
8018 but we don't handle values other than 1 correctly yet.) */
8025 /* Fold *&X to X if X is an lvalue. */
8027 {
8034 }
8040 }
8043 /* If the operation was a conversion do _not_ mark a resulting constant
8044 with TREE_OVERFLOW if the original constant was not. These conversions
8045 have implementation defined behavior and retaining the TREE_OVERFLOW
8046 flag here would confuse later passes such as VRP. */
8047 tree
8050 {
8059 }
8061 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8062 operands OP0 and OP1. LOC is the location of the resulting expression.
8063 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8064 Return the folded expression if folding is successful. Otherwise,
8065 return NULL_TREE. */
8066 static tree
8069 {
8070 tree tem;
8072 /* We only do these simplifications if we are optimizing. */
8076 /* Check for things like (A || B) && (A || C). We can convert this
8077 to A || (B && C). Note that either operator can be any of the four
8078 truth and/or operations and the transformation will still be
8079 valid. Also note that we only care about order for the
8080 ANDIF and ORIF operators. If B contains side effects, this
8081 might change the truth-value of A. */
8088 {
8108 /* This case if tricky because we must either have commutative
8109 operators or else A10 must not have side-effects. */
8115 a01);
8116 }
8118 /* See if we can build a range comparison. */
8124 {
8128 }
8132 {
8136 }
8138 /* Check for the possibility of merging component references. If our
8139 lhs is another similar operation, try to merge its rhs with our
8140 rhs. Then try to merge our lhs and rhs. */
8154 {
8161 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8162 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8163 We don't want to pack more than two leafs to a non-IF AND/OR
8164 expression.
8165 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8166 equal to IF-CODE, then we don't want to add right-hand operand.
8167 If the inner right-hand side of left-hand operand has
8168 side-effects, or isn't simple, then we can't add to it,
8169 as otherwise we might destroy if-sequence. */
8172 /* Needed for sequence points to handle trappings, and
8173 side-effects. */
8175 {
8177 arg1);
8179 tem);
8180 }
8181 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8182 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8185 /* Needed for sequence points to handle trappings, and
8186 side-effects. */
8188 {
8193 }
8194 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8195 into (A OR B).
8196 For sequence point consistancy, we need to check for trapping,
8197 and side-effects. */
8201 }
8204 }
8206 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8207 by changing CODE to reduce the magnitude of constants involved in
8208 ARG0 of the comparison.
8209 Returns a canonicalized comparison tree if a simplification was
8210 possible, otherwise returns NULL_TREE.
8211 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8212 valid if signed overflow is undefined. */
8214 static tree
8218 {
8223 /* Match A +- CST code arg1. We can change this only if overflow
8224 is undefined. */
8227 /* In principle pointers also have undefined overflow behavior,
8228 but that causes problems elsewhere. */
8235 /* Identify the constant in arg0 and its sign. */
8239 /* Overflowed constants and zero will cause problems. */
8244 /* See if we can reduce the magnitude of the constant in
8245 arg0 by changing the comparison code. */
8246 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8250 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8254 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8258 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8262 else
8266 /* Now build the constant reduced in magnitude. But not if that
8267 would produce one outside of its types range. */
8283 }
8285 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8286 overflow further. Try to decrease the magnitude of constants involved
8287 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8288 and put sole constants at the second argument position.
8289 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8291 static tree
8294 {
8295 tree t;
8300 /* Try canonicalization by simplifying arg0. */
8305 {
8309 }
8311 /* Try canonicalization by simplifying arg1 using the swapped
8312 comparison. */
8320 }
8322 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8323 space. This is used to avoid issuing overflow warnings for
8324 expressions like &p->x which can not wrap. */
8326 static bool
8328 {
8335 wide_int wi_offset;
8341 else
8357 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8358 array. */
8360 {
8361 HOST_WIDE_INT base_size;
8366 }
8369 }
8371 /* Return a positive integer when the symbol DECL is known to have
8372 a nonzero address, zero when it's known not to (e.g., it's a weak
8373 symbol), and a negative integer when the symbol is not yet in the
8374 symbol table and so whether or not its address is zero is unknown. */
8375 static int
8377 {
8383 }
8385 /* Subroutine of fold_binary. This routine performs all of the
8386 transformations that are common to the equality/inequality
8387 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8388 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8389 fold_binary should call fold_binary. Fold a comparison with
8390 tree code CODE and type TYPE with operands OP0 and OP1. Return
8391 the folded comparison or NULL_TREE. */
8393 static tree
8396 {
8406 /* For comparisons of pointers we can decompose it to a compile time
8407 comparison of the base objects and the offsets into the object.
8408 This requires at least one operand being an ADDR_EXPR or a
8409 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8415 {
8418 machine_mode mode;
8422 /* Get base and offset for the access. Strip ADDR_EXPR for
8423 get_inner_reference, but put it back by stripping INDIRECT_REF
8424 off the base object if possible. indirect_baseN will be true
8425 if baseN is not an address but refers to the object itself. */
8428 {
8429 base0
8435 else
8437 }
8439 {
8443 {
8444 base0
8451 else
8453 }
8456 else
8460 {
8466 {
8469 }
8470 }
8471 }
8475 {
8476 base1
8482 else
8484 }
8486 {
8490 {
8491 base1
8498 else
8500 }
8503 else
8507 {
8513 {
8516 }
8517 }
8518 }
8520 /* If we have equivalent bases we might be able to simplify. */
8524 {
8525 /* We can fold this expression to a constant if the non-constant
8526 offset parts are equal. */
8535 {
8541 "occur when comparing P +- C1 with "
8543 WARN_STRICT_OVERFLOW_CONDITIONAL);
8546 {
8560 }
8561 }
8562 /* We can simplify the comparison to a comparison of the variable
8563 offset parts if the constant offset parts are equal.
8564 Be careful to use signed sizetype here because otherwise we
8565 mess with array offsets in the wrong way. This is possible
8566 because pointer arithmetic is restricted to retain within an
8567 object and overflow on pointer differences is undefined as of
8568 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8570 && (equality_code
8573 {
8574 /* By converting to signed sizetype we cover middle-end pointer
8575 arithmetic which operates on unsigned pointer types of size
8576 type size and ARRAY_REF offsets which are properly sign or
8577 zero extended from their type in case it is narrower than
8578 sizetype. */
8581 else
8585 else
8592 "occur when comparing P +- C1 with "
8594 WARN_STRICT_OVERFLOW_COMPARISON);
8597 }
8598 }
8599 /* For equal offsets we can simplify to a comparison of the
8600 base addresses. */
8602 && (indirect_base0
8604 && (indirect_base1
8609 {
8615 }
8616 /* Comparison between an ordinary (non-weak) symbol and a null
8617 pointer can be eliminated since such symbols must have a non
8618 null address. In C, relational expressions between pointers
8619 to objects and null pointers are undefined. The results
8620 below follow the C++ rules with the additional property that
8621 every object pointer compares greater than a null pointer.
8622 */
8625 /* Avoid folding references to struct members at offset 0 to
8626 prevent tests like '&ptr->firstmember == 0' from getting
8627 eliminated. When ptr is null, although the -> expression
8628 is strictly speaking invalid, GCC retains it as a matter
8629 of QoI. See PR c/44555. */
8631 /* The caller guarantees that when one of the arguments is
8632 constant (i.e., null in this case) it is second. */
8634 {
8636 {
8647 }
8648 }
8649 }
8651 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8652 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8653 the resulting offset is smaller in absolute value than the
8654 original one and has the same sign. */
8663 {
8668 tree cst;
8670 "occur when combining constants around "
8673 /* Put the constant on the side where it doesn't overflow and is
8674 of lower absolute value and of same sign than before. */
8681 {
8684 variable1,
8688 }
8696 {
8702 variable2);
8703 }
8704 }
8710 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8711 constant, we can simplify it. */
8716 {
8720 }
8722 /* If we are comparing an expression that just has comparisons
8723 of two integer values, arithmetic expressions of those comparisons,
8724 and constants, we can simplify it. There are only three cases
8725 to check: the two values can either be equal, the first can be
8726 greater, or the second can be greater. Fold the expression for
8727 those three values. Since each value must be 0 or 1, we have
8728 eight possibilities, each of which corresponds to the constant 0
8729 or 1 or one of the six possible comparisons.
8731 This handles common cases like (a > b) == 0 but also handles
8732 expressions like ((x > y) - (y > x)) > 0, which supposedly
8733 occur in macroized code. */
8736 {
8741 /* Don't handle degenerate cases here; they should already
8742 have been handled anyway. */
8751 {
8755 /* We can't just pass T to eval_subst in case cval1 or cval2
8756 was the same as ARG1. */
8758 tree high_result
8762 arg1);
8763 tree equal_result
8767 arg1);
8768 tree low_result
8772 arg1);
8774 /* All three of these results should be 0 or 1. Confirm they are.
8775 Then use those values to select the proper code to use. */
8780 {
8781 /* Make a 3-bit mask with the high-order bit being the
8782 value for `>', the next for '=', and the low for '<'. */
8786 {
8788 /* Always false. */
8809 /* Always true. */
8811 }
8814 {
8818 }
8820 }
8821 }
8822 }
8824 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8825 into a single range test. */
8833 {
8837 }
8840 }
8843 /* Subroutine of fold_binary. Optimize complex multiplications of the
8844 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8845 argument EXPR represents the expression "z" of type TYPE. */
8847 static tree
8849 {
8854 {
8857 }
8859 {
8862 }
8863 else
8864 {
8868 }
8877 }
8880 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8881 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8883 static bool
8885 {
8889 {
8892 }
8894 {
8900 else
8902 }
8903 else
8909 }
8911 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8912 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8913 NULL_TREE otherwise. */
8915 static tree
8917 {
8934 {
8938 }
8941 {
8947 }
8948 else
8950 }
8952 /* Try to fold a pointer difference of type TYPE two address expressions of
8953 array references AREF0 and AREF1 using location LOC. Return a
8954 simplified expression for the difference or NULL_TREE. */
8956 static tree
8959 {
8964 /* If the bases are array references as well, recurse. If the bases
8965 are pointer indirections compute the difference of the pointers.
8966 If the bases are equal, we are set. */
8969 && (base_offset
8973 && (base_offset
8979 {
8985 base_offset,
8988 }
8990 }
8992 /* If the real or vector real constant CST of type TYPE has an exact
8993 inverse, return it, else return NULL. */
8995 tree
8997 {
8998 REAL_VALUE_TYPE r;
9000 machine_mode mode;
9004 {
9020 {
9025 }
9031 }
9032 }
9034 /* Mask out the tz least significant bits of X of type TYPE where
9035 tz is the number of trailing zeroes in Y. */
9036 static wide_int
9038 {
9043 }
9045 /* Return true when T is an address and is known to be nonzero.
9046 For floating point we further ensure that T is not denormal.
9047 Similar logic is present in nonzero_address in rtlanal.h.
9049 If the return value is based on the assumption that signed overflow
9050 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9051 change *STRICT_OVERFLOW_P. */
9053 static bool
9055 {
9059 /* Doing something useful for floating point would need more work. */
9065 {
9068 strict_overflow_p);
9074 strict_overflow_p);
9082 }
9085 {
9088 strict_overflow_p);
9096 strict_overflow_p);
9111 strict_overflow_p);
9115 strict_overflow_p);
9118 {
9130 }
9134 }
9136 }
9138 /* Return true when T is an address and is known to be nonzero.
9139 Handle warnings about undefined signed overflow. */
9141 static bool
9143 {
9150 "determining that expression is always "
9152 WARN_STRICT_OVERFLOW_MISC);
9154 }
9156 /* Return true if T is known not to be equal to an integer W. */
9158 bool
9160 {
9162 value_range_type rtype;
9164 {
9173 {
9178 }
9183 /* If T has some known zero bits and W has any of those bits set,
9184 then T is known not to be equal to W. */
9192 }
9193 }
9195 /* Fold a binary expression of code CODE and type TYPE with operands
9196 OP0 and OP1. LOC is the location of the resulting expression.
9197 Return the folded expression if folding is successful. Otherwise,
9198 return NULL_TREE. */
9200 tree
9203 {
9218 /* Strip any conversions that don't change the mode. This is
9219 safe for every expression, except for a comparison expression
9220 because its signedness is derived from its operands. So, in
9221 the latter case, only strip conversions that don't change the
9222 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9223 preserved.
9225 Note that this is done as an internal manipulation within the
9226 constant folder, in order to find the simplest representation
9227 of the arguments so that their form can be studied. In any
9228 cases, the appropriate type conversions should be put back in
9229 the tree that will get out of the constant folder. */
9232 {
9235 }
9236 else
9237 {
9240 }
9242 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9243 constant but we can't do arithmetic on them. */
9245 {
9248 {
9252 }
9253 }
9255 /* If this is a commutative operation, and ARG0 is a constant, move it
9256 to ARG1 to reduce the number of tests below. */
9261 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9262 to ARG1 to reduce the number of tests below. */
9271 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9273 First check for cases where an arithmetic operation is applied to a
9274 compound, conditional, or comparison operation. Push the arithmetic
9275 operation inside the compound or conditional to see if any folding
9276 can then be done. Convert comparison to conditional for this purpose.
9277 The also optimizes non-constant cases that used to be done in
9278 expand_expr.
9280 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9281 one of the operands is a comparison and the other is a comparison, a
9282 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9283 code below would make the expression more complex. Change it to a
9284 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9285 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9298 {
9302 boolean_type_node,
9310 }
9314 {
9316 {
9321 tem);
9322 }
9325 {
9330 tem);
9331 }
9336 {
9342 }
9347 {
9353 }
9354 }
9357 {
9359 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9362 {
9368 }
9370 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9373 {
9374 tree base;
9375 HOST_WIDE_INT coffset;
9384 }
9389 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9395 arg1),
9397 arg0)));
9403 {
9404 /* X + (X / CST) * -CST is X % CST. */
9409 {
9418 cst0));
9419 }
9420 }
9422 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9423 one. Make sure the type is not saturating and has the signedness of
9424 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9425 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9432 {
9436 }
9439 {
9440 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9441 (plus (plus (mult) (mult)) (foo)) so that we can
9442 take advantage of the factoring cases below. */
9451 {
9457 else
9470 parg0),
9472 marg)),
9476 return
9482 parg1)));
9483 }
9484 }
9485 else
9486 {
9487 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9488 to __complex__ ( x, y ). This is not the same for SNaNs or
9489 if signed zeros are involved. */
9493 {
9500 {
9504 {
9510 }
9512 {
9518 }
9519 }
9520 }
9528 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9529 We associate floats only if the user has specified
9530 -fassociative-math. */
9534 {
9539 {
9540 tree tree0;
9543 }
9544 }
9545 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9546 We associate floats only if the user has specified
9547 -fassociative-math. */
9551 {
9556 {
9557 tree tree0;
9560 }
9561 }
9562 }
9564 bit_rotate:
9565 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9566 is a rotate of A by C1 bits. */
9567 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9568 is a rotate of A by B bits. */
9569 {
9571 tree rtype;
9580 /* Only create rotates in complete modes. Other cases are not
9581 expanded properly. */
9584 {
9598 {
9602 code0 == LSHIFT_EXPR
9606 }
9608 {
9616 element_precision
9620 return
9623 ? LROTATE_EXPR
9628 }
9630 {
9638 element_precision
9642 return fold_convert_loc
9645 ? LROTATE_EXPR
9649 }
9650 }
9651 }
9653 associate:
9654 /* In most languages, can't associate operations on floats through
9655 parentheses. Rather than remember where the parentheses were, we
9656 don't associate floats at all, unless the user has specified
9657 -fassociative-math.
9658 And, we need to make sure type is not saturating. */
9662 {
9668 /* Split both trees into variables, constants, and literals. Then
9669 associate each group together, the constants with literals,
9670 then the result with variables. This increases the chances of
9671 literals being recombined later and of generating relocatable
9672 expressions for the sum of a constant and literal. */
9678 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9682 /* With undefined overflow prefer doing association in a type
9683 which wraps on overflow, if that is one of the operand types. */
9686 {
9694 }
9696 /* With undefined overflow we can only associate constants with one
9697 variable, and constants whose association doesn't overflow. */
9700 {
9702 {
9708 {
9711 }
9718 {
9721 }
9727 /* The only case we can still associate with two variables
9728 is if they cancel out. */
9732 }
9733 }
9735 /* Only do something if we found more than two objects. Otherwise,
9736 nothing has changed and we risk infinite recursion. */
9742 {
9754 /* Preserve the MINUS_EXPR if the negative part of the literal is
9755 greater than the positive part. Otherwise, the multiplicative
9756 folding code (i.e extract_muldiv) may be fooled in case
9757 unsigned constants are subtracted, like in the following
9758 example: ((X*2 + 4) - 8U)/2. */
9760 {
9764 {
9768 }
9769 else
9770 {
9774 }
9775 }
9777 /* Don't introduce overflows through reassociation. */
9784 {
9786 return
9790 else
9791 {
9794 return
9798 }
9799 }
9802 return
9805 }
9806 }
9811 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9820 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9821 __complex__ ( x, -y ). This is not the same for SNaNs or if
9822 signed zeros are involved. */
9826 {
9833 {
9837 {
9839 arg1r ? arg1r
9844 }
9846 {
9850 arg1i ? arg1i
9853 }
9854 }
9855 }
9857 /* A - B -> A + (-B) if B is easily negatable. */
9861 /* Avoid this transformation if B is a positive REAL_CST. */
9869 /* Fold &a[i] - &a[j] to i-j. */
9874 {
9880 }
9883 && flag_unsafe_math_optimizations
9889 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9890 one. Make sure the type is not saturating and has the signedness of
9891 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9892 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9899 {
9903 }
9909 {
9910 /* Transform x * -C into -x * C if x is easily negatable. */
9924 {
9927 "occur when simplifying "
9929 WARN_STRICT_OVERFLOW_MISC);
9931 }
9933 /* Optimize z * conj(z) for integer complex numbers. */
9940 }
9941 else
9942 {
9943 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9944 This is not the same for NaNs or if signed zeros are
9945 involved. */
9951 {
9954 return
9960 return
9965 }
9967 /* Optimize z * conj(z) for floating point complex numbers.
9968 Guarded by flag_unsafe_math_optimizations as non-finite
9969 imaginary components don't produce scalar results. */
9978 }
9982 /* Canonicalize (X & C1) | C2. */
9986 {
9991 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9999 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10004 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10005 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10006 mode which allows further optimizations. */
10011 {
10015 {
10018 }
10019 }
10026 c3)),
10027 arg1);
10028 }
10030 /* See if this can be simplified into a rotate first. If that
10031 is unsuccessful continue in the association code. */
10035 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10043 /* See if this can be simplified into a rotate first. If that
10044 is unsuccessful continue in the association code. */
10048 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10053 {
10054 tree tem2;
10061 }
10062 /* Fold ~X & 1 as (X & 1) == 0. */
10066 {
10067 tree tem2;
10074 }
10075 /* Fold !X & 1 as X == 0. */
10078 {
10082 }
10084 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10085 multiple of 1 << CST. */
10087 {
10094 }
10096 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10097 bits from CST2. */
10101 {
10109 {
10110 /* Avoid the transform if arg1 is a mask of some
10111 mode which allows further optimizations. */
10118 }
10119 }
10121 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10122 ((A & N) + B) & M -> (A + B) & M
10123 Similarly if (N & M) == 0,
10124 ((A | N) + B) & M -> (A + B) & M
10125 and for - instead of + (or unary - instead of +)
10126 and/or ^ instead of |.
10127 If B is constant and (B & M) == 0, fold into A & M. */
10129 {
10138 {
10141 wide_int cst0;
10143 /* Now we know that arg0 is (C + D) or (C - D) or
10144 -C and arg1 (M) is == (1LL << cst) - 1.
10145 Store C into PMOP[0] and D into PMOP[1]. */
10149 {
10152 }
10159 {
10169 {
10172 }
10175 /* If C or D is of the form (A & N) where
10176 (N & M) == M, or of the form (A | N) or
10177 (A ^ N) where (N & M) == 0, replace it with A. */
10181 /* If C or D is a N where (N & M) == 0, it can be
10182 omitted (assumed 0). */
10190 }
10192 /* Only build anything new if we optimized one or both arguments
10193 above. */
10197 {
10200 {
10201 /* Perform the operations in a type that has defined
10202 overflow behavior. */
10208 }
10213 {
10221 else
10223 }
10226 else
10229 /* TEM is now the new binary +, - or unary - replacement. */
10233 }
10234 }
10235 }
10237 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10240 {
10245 return
10247 }
10252 /* Don't touch a floating-point divide by zero unless the mode
10253 of the constant can represent infinity. */
10259 /* (-A) / (-B) -> A / B */
10271 /* Fall through */
10274 /* Simplify A / (B << N) where A and B are positive and B is
10275 a power of 2, to A >> (N + log2(B)). */
10280 {
10283 {
10291 WARN_STRICT_OVERFLOW_MISC);
10297 }
10298 }
10300 /* Fall through */
10308 /* Convert -A / -B to A / B when the type is signed and overflow is
10309 undefined. */
10313 {
10316 "when distributing negation across "
10318 WARN_STRICT_OVERFLOW_MISC);
10323 }
10327 {
10330 "when distributing negation across "
10332 WARN_STRICT_OVERFLOW_MISC);
10337 }
10339 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10340 operation, EXACT_DIV_EXPR.
10342 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10343 At one time others generated faster code, it's not clear if they do
10344 after the last round to changes to the DIV code in expmed.c. */
10355 {
10359 WARN_STRICT_OVERFLOW_MISC);
10361 }
10373 {
10377 WARN_STRICT_OVERFLOW_MISC);
10379 }
10387 /* Since negative shift count is not well-defined,
10388 don't try to compute it in the compiler. */
10394 /* If we have a rotate of a bit operation with the rotate count and
10395 the second operand of the bit operation both constant,
10396 permute the two operations. */
10408 /* Two consecutive rotates adding up to the some integer
10409 multiple of the precision of the type can be ignored. */
10424 /* Note that the operands of this must be ints
10425 and their values must be 0 or 1.
10426 ("true" is a fixed value perhaps depending on the language.) */
10427 /* If first arg is constant zero, return it. */
10431 /* If either arg is constant true, drop it. */
10435 /* Preserve sequence points. */
10438 /* If second arg is constant zero, result is zero, but first arg
10439 must be evaluated. */
10442 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10443 case will be handled here. */
10447 /* !X && X is always false. */
10451 /* X && !X is always false. */
10456 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10457 means A >= Y && A != MAX, but in this case we know that
10458 A < X <= MAX. */
10462 {
10470 }
10479 /* Note that the operands of this must be ints
10480 and their values must be 0 or true.
10481 ("true" is a fixed value perhaps depending on the language.) */
10482 /* If first arg is constant true, return it. */
10486 /* If either arg is constant zero, drop it. */
10490 /* Preserve sequence points. */
10493 /* If second arg is constant true, result is true, but we must
10494 evaluate first arg. */
10497 /* Likewise for first arg, but note this only occurs here for
10498 TRUTH_OR_EXPR. */
10502 /* !X || X is always true. */
10506 /* X || !X is always true. */
10511 /* (X && !Y) || (!X && Y) is X ^ Y */
10514 {
10531 }
10540 /* If the second arg is constant zero, drop it. */
10543 /* If the second arg is constant true, this is a logical inversion. */
10545 {
10548 }
10549 /* Identical arguments cancel to zero. */
10553 /* !X ^ X is always true. */
10558 /* X ^ !X is always true. */
10574 /* bool_var != 1 becomes !bool_var. */
10581 /* bool_var == 0 becomes !bool_var. */
10588 /* !exp != 0 becomes !exp */
10593 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10602 {
10608 }
10610 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10619 {
10625 }
10627 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10635 code == NE_EXPR
10639 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10647 code == NE_EXPR
10651 /* If this is an EQ or NE comparison with zero and ARG0 is
10652 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10653 two operations, but the latter can be done in one less insn
10654 on machines that have only two-operand insns or on which a
10655 constant cannot be the first operand. */
10658 {
10663 {
10670 arg1);
10671 }
10674 {
10681 arg1);
10682 }
10683 }
10685 /* If this is an NE or EQ comparison of zero against the result of a
10686 signed MOD operation whose second operand is a power of 2, make
10687 the MOD operation unsigned since it is simpler and equivalent. */
10695 {
10705 }
10707 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10708 C1 is a valid shift constant, and C2 is a power of two, i.e.
10709 a single bit. */
10713 == INTEGER_CST
10716 {
10721 /* Check for a valid shift count. */
10723 {
10727 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10728 can be rewritten as (X & (C2 << C1)) != 0. */
10730 {
10735 }
10736 /* Otherwise, for signed (arithmetic) shifts,
10737 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10738 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10742 /* Otherwise, of unsigned (logical) shifts,
10743 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10744 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10745 else
10749 arg000);
10750 }
10751 }
10753 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10754 Similarly for NE_EXPR. */
10758 {
10762 tree dandnotc
10765 notc);
10769 }
10771 /* If this is a comparison of a field, we may be able to simplify it. */
10774 /* Handle the constant case even without -O
10775 to make sure the warnings are given. */
10777 {
10781 }
10783 /* Optimize comparisons of strlen vs zero to a compare of the
10784 first character of the string vs zero. To wit,
10785 strlen(ptr) == 0 => *ptr == 0
10786 strlen(ptr) != 0 => *ptr != 0
10787 Other cases should reduce to one of these two (or a constant)
10788 due to the return value of strlen being unsigned. */
10791 {
10799 {
10804 }
10805 }
10807 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10808 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10812 {
10817 {
10819 {
10822 }
10825 }
10826 }
10828 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10829 (X & C) == 0 when C is a single bit. */
10834 {
10841 arg1));
10842 }
10844 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10845 constant C is a power of two, i.e. a single bit. */
10852 {
10856 }
10858 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10859 when is C is a power of two, i.e. a single bit. */
10866 {
10872 }
10876 {
10879 }
10881 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10884 {
10897 arg01),
10906 arg01),
10915 arg00),
10924 arg00),
10926 }
10930 {
10937 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10938 operand_equal_p guarantees no side-effects so we don't need
10939 to use omit_one_operand on Z. */
10943 arg10));
10947 arg11));
10951 arg10));
10955 arg11));
10957 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10960 {
10966 }
10967 }
10969 /* Attempt to simplify equality/inequality comparisons of complex
10970 values. Only lower the comparison if the result is known or
10971 can be simplified to a single scalar comparison. */
10976 {
10981 {
10984 }
10985 else
10986 {
10989 }
10992 {
10995 }
10996 else
10997 {
11000 }
11004 {
11006 {
11011 }
11012 else
11013 {
11018 }
11019 }
11023 {
11025 {
11030 }
11031 else
11032 {
11037 }
11038 }
11039 }
11051 /* Transform comparisons of the form X +- C CMP X. */
11058 {
11065 else
11068 /* (X - c) > X becomes false. */
11072 {
11076 "occur when assuming that (X - c) > X "
11078 WARN_STRICT_OVERFLOW_ALL);
11080 }
11082 /* Likewise (X + c) < X becomes false. */
11086 {
11090 "occur when assuming that "
11092 WARN_STRICT_OVERFLOW_ALL);
11094 }
11096 /* Convert (X - c) <= X to true. */
11101 {
11105 "occur when assuming that "
11107 WARN_STRICT_OVERFLOW_ALL);
11109 }
11111 /* Convert (X + c) >= X to true. */
11116 {
11120 "occur when assuming that "
11122 WARN_STRICT_OVERFLOW_ALL);
11124 }
11127 {
11128 /* Convert X + c > X and X - c < X to true for integers. */
11132 {
11135 "not occur when assuming that "
11137 WARN_STRICT_OVERFLOW_ALL);
11139 }
11144 {
11147 "not occur when assuming that "
11149 WARN_STRICT_OVERFLOW_ALL);
11151 }
11153 /* Convert X + c <= X and X - c >= X to false for integers. */
11157 {
11160 "not occur when assuming that "
11162 WARN_STRICT_OVERFLOW_ALL);
11164 }
11169 {
11172 "not occur when assuming that "
11174 WARN_STRICT_OVERFLOW_ALL);
11176 }
11177 }
11178 }
11180 /* If we are comparing an ABS_EXPR with a constant, we can
11181 convert all the cases into explicit comparisons, but they may
11182 well not be faster than doing the ABS and one comparison.
11183 But ABS (X) <= C is a range comparison, which becomes a subtraction
11184 and a comparison, and is probably faster. */
11198 /* Convert ABS_EXPR<x> >= 0 to true. */
11205 {
11208 "when simplifying comparison of "
11210 WARN_STRICT_OVERFLOW_CONDITIONAL);
11213 arg0);
11214 }
11216 /* Convert ABS_EXPR<x> < 0 to false. */
11221 {
11224 "when simplifying comparison of "
11226 WARN_STRICT_OVERFLOW_CONDITIONAL);
11229 arg0);
11230 }
11232 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11233 and similarly for >= into !=. */
11243 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11244 otherwise Y might be >= # of bits in X's type and thus e.g.
11245 (unsigned char) (1 << Y) for Y 15 might be 0.
11246 If the cast is widening, then 1 << Y should have unsigned type,
11247 otherwise if Y is number of bits in the signed shift type minus 1,
11248 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11249 31 might be 0xffffffff80000000. */
11260 {
11266 }
11278 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11279 {
11291 }
11296 /* When pedantic, a compound expression can be neither an lvalue
11297 nor an integer constant expression. */
11300 /* Don't let (0, 0) be null pointer constant. */
11306 /* An ASSERT_EXPR should never be passed to fold_binary. */
11312 }
11314 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11315 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11316 of GOTO_EXPR. */
11318 static tree
11320 {
11322 {
11329 /* ... fall through ... */
11333 }
11334 }
11336 /* Return whether the sub-tree ST contains a label which is accessible from
11337 outside the sub-tree. */
11339 static bool
11341 {
11342 return
11344 }
11346 /* Fold a ternary expression of code CODE and type TYPE with operands
11347 OP0, OP1, and OP2. Return the folded expression if folding is
11348 successful. Otherwise, return NULL_TREE. */
11350 tree
11353 {
11354 tree tem;
11361 /* If this is a commutative operation, and OP0 is a constant, move it
11362 to OP1 to reduce the number of tests below. */
11371 /* Strip any conversions that don't change the mode. This is safe
11372 for every expression, except for a comparison expression because
11373 its signedness is derived from its operands. So, in the latter
11374 case, only strip conversions that don't change the signedness.
11376 Note that this is done as an internal manipulation within the
11377 constant folder, in order to find the simplest representation of
11378 the arguments so that their form can be studied. In any cases,
11379 the appropriate type conversions should be put back in the tree
11380 that will get out of the constant folder. */
11382 {
11385 }
11388 {
11391 }
11394 {
11397 }
11400 {
11404 {
11410 }
11415 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11416 so all simple results must be passed through pedantic_non_lvalue. */
11418 {
11421 /* Only optimize constant conditions when the selected branch
11422 has the same type as the COND_EXPR. This avoids optimizing
11423 away "c ? x : throw", where the throw has a void type.
11424 Avoid throwing away that operand which contains label. */
11431 }
11433 {
11438 {
11443 {
11451 }
11455 }
11456 }
11458 /* If we have A op B ? A : C, we may be able to convert this to a
11459 simpler expression, depending on the operation and the values
11460 of B and C. Signed zeros prevent all of these transformations,
11461 for reasons given above each one.
11463 Also try swapping the arguments and inverting the conditional. */
11468 {
11472 }
11476 op2,
11479 {
11483 {
11487 }
11488 }
11490 /* If the second operand is simpler than the third, swap them
11491 since that produces better jump optimization results. */
11494 {
11496 /* See if this can be inverted. If it can't, possibly because
11497 it was a floating-point inequality comparison, don't do
11498 anything. */
11502 }
11504 /* Convert A ? 1 : 0 to simply A. */
11509 /* If we try to convert OP0 to our type, the
11510 call to fold will try to move the conversion inside
11511 a COND, which will recurse. In that case, the COND_EXPR
11512 is probably the best choice, so leave it alone. */
11516 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11517 over COND_EXPR in cases such as floating point comparisons. */
11526 arg0)));
11528 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11533 {
11534 /* sign_bit_p looks through both zero and sign extensions,
11535 but for this optimization only sign extensions are
11536 usable. */
11539 {
11542 {
11545 }
11547 }
11548 /* sign_bit_p only checks ARG1 bits within A's precision.
11549 If <sign bit of A> has wider type than A, bits outside
11550 of A's precision in <sign bit of A> need to be checked.
11551 If they are all 0, this optimization needs to be done
11552 in unsigned A's type, if they are all 1 in signed A's type,
11553 otherwise this can't be done. */
11559 {
11561 tree tem_type;
11574 {
11577 }
11579 {
11582 }
11583 else
11585 }
11588 return
11594 arg1)));
11595 }
11597 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11598 already handled above. */
11603 {
11612 }
11614 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11615 is probably obsolete because the first operand should be a
11616 truth value (that's why we have the two cases above), but let's
11617 leave it in until we can confirm this for all front-ends. */
11629 /* Disable the transformations below for vectors, since
11630 fold_binary_op_with_conditional_arg may undo them immediately,
11631 yielding an infinite loop. */
11635 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11644 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11649 {
11651 /* Only perform transformation if ARG0 is easily inverted. */
11655 ? BIT_IOR_EXPR
11658 arg1);
11659 }
11661 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11666 {
11668 /* Only perform transformation if ARG0 is easily inverted. */
11674 op2);
11675 }
11677 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11689 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11690 of fold_ternary on them. */
11698 {
11708 {
11713 {
11721 }
11722 }
11723 }
11725 /* On constants we can use native encode/interpret to constant
11726 fold (nearly) all BIT_FIELD_REFs. */
11730 {
11733 /* Limit us to a reasonable amount of work. To relax the
11734 other limitations we need bit-shifting of the buffer
11735 and rounding up the size. */
11739 {
11741 unsigned HOST_WIDE_INT len
11746 {
11751 }
11752 }
11753 }
11758 /* For integers we can decompose the FMA if possible. */
11770 {
11786 {
11791 /* Make sure that the perm value is in an acceptable
11792 range. */
11801 else
11806 }
11809 {
11814 }
11819 {
11824 }
11830 {
11834 }
11839 /* Some targets are deficient and fail to expand a single
11840 argument permutation while still allowing an equivalent
11841 2-argument version. */
11845 {
11848 }
11851 {
11858 }
11862 }
11866 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11869 {
11875 wide_int tem2
11879 }
11884 {
11886 unsigned HOST_WIDE_INT elsize
11889 {
11893 else
11894 {
11900 }
11901 }
11902 }
11908 }
11910 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11911 of an array (or vector). */
11913 tree
11915 {
11920 {
11923 {
11924 /* Static constructors for variably sized objects makes no sense. */
11928 }
11929 }
11940 offset_int max_index;
11945 {
11946 /* Array constructor might explicitly set index, or specify a range,
11947 or leave index NULL meaning that it is next index after previous
11948 one. */
11950 {
11953 else
11954 {
11958 }
11959 }
11960 else
11961 {
11967 }
11969 /* Do we have match? */
11973 }
11975 }
11977 /* Perform constant folding and related simplification of EXPR.
11978 The related simplifications include x*1 => x, x*0 => 0, etc.,
11979 and application of the associative law.
11980 NOP_EXPR conversions may be removed freely (as long as we
11981 are careful not to change the type of the overall expression).
11982 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11983 but we can constant-fold them if they have constant operands. */
11985 #ifdef ENABLE_FOLD_CHECKING
11986 # define fold(x) fold_1 (x)
11988 static
11989 #endif
11990 tree
11992 {
11996 tree tem;
11999 /* Return right away if a constant. */
12003 /* CALL_EXPR-like objects with variable numbers of operands are
12004 treated specially. */
12006 {
12008 {
12011 }
12013 }
12016 {
12021 {
12039 }
12040 }
12043 {
12045 {
12052 {
12057 }
12060 }
12062 /* Return a VECTOR_CST if possible. */
12064 {
12070 tree val;
12076 }
12084 }
12086 #ifdef ENABLE_FOLD_CHECKING
12087 #undef fold
12094 /* When --enable-checking=fold, compute a digest of expr before
12095 and after actual fold call to see if fold did not accidentally
12096 change original expr. */
12098 tree
12100 {
12101 tree ret;
12121 }
12123 void
12125 {
12136 }
12138 static void
12140 {
12142 }
12144 static void
12147 {
12153 recursive_label:
12163 {
12164 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12169 }
12177 {
12178 /* Allow these fields to be modified. */
12179 tree tmp;
12188 {
12191 }
12192 }
12203 {
12206 {
12221 }
12225 {
12238 }
12255 {
12261 }
12264 {
12266 {
12269 }
12271 }
12282 {
12285 }
12295 }
12296 }
12298 /* Helper function for outputting the checksum of a tree T. When
12299 debugging with gdb, you can "define mynext" to be "next" followed
12300 by "call debug_fold_checksum (op0)", then just trace down till the
12301 outputs differ. */
12303 DEBUG_FUNCTION void
12305 {
12320 }
12322 #endif
12324 /* Fold a unary tree expression with code CODE of type TYPE with an
12325 operand OP0. LOC is the location of the resulting expression.
12326 Return a folded expression if successful. Otherwise, return a tree
12327 expression with code CODE of type TYPE with an operand OP0. */
12329 tree
12332 {
12333 tree tem;
12334 #ifdef ENABLE_FOLD_CHECKING
12343 #endif
12349 #ifdef ENABLE_FOLD_CHECKING
12356 #endif
12358 }
12360 /* Fold a binary tree expression with code CODE of type TYPE with
12361 operands OP0 and OP1. LOC is the location of the resulting
12362 expression. Return a folded expression if successful. Otherwise,
12363 return a tree expression with code CODE of type TYPE with operands
12364 OP0 and OP1. */
12366 tree
12369 MEM_STAT_DECL)
12370 {
12371 tree tem;
12372 #ifdef ENABLE_FOLD_CHECKING
12389 #endif
12395 #ifdef ENABLE_FOLD_CHECKING
12410 #endif
12412 }
12414 /* Fold a ternary tree expression with code CODE of type TYPE with
12415 operands OP0, OP1, and OP2. Return a folded expression if
12416 successful. Otherwise, return a tree expression with code CODE of
12417 type TYPE with operands OP0, OP1, and OP2. */
12419 tree
12422 {
12423 tree tem;
12424 #ifdef ENABLE_FOLD_CHECKING
12448 #endif
12455 #ifdef ENABLE_FOLD_CHECKING
12478 #endif
12480 }
12482 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12483 arguments in ARGARRAY, and a null static chain.
12484 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12485 of type TYPE from the given operands as constructed by build_call_array. */
12487 tree
12490 {
12491 tree tem;
12492 #ifdef ENABLE_FOLD_CHECKING
12511 #endif
12517 #ifdef ENABLE_FOLD_CHECKING
12533 #endif
12535 }
12537 /* Perform constant folding and related simplification of initializer
12538 expression EXPR. These behave identically to "fold_buildN" but ignore
12539 potential run-time traps and exceptions that fold must preserve. */
12541 #define START_FOLD_INIT \
12542 int saved_signaling_nans = flag_signaling_nans;\
12543 int saved_trapping_math = flag_trapping_math;\
12544 int saved_rounding_math = flag_rounding_math;\
12545 int saved_trapv = flag_trapv;\
12546 int saved_folding_initializer = folding_initializer;\
12547 flag_signaling_nans = 0;\
12548 flag_trapping_math = 0;\
12549 flag_rounding_math = 0;\
12550 flag_trapv = 0;\
12551 folding_initializer = 1;
12553 #define END_FOLD_INIT \
12554 flag_signaling_nans = saved_signaling_nans;\
12555 flag_trapping_math = saved_trapping_math;\
12556 flag_rounding_math = saved_rounding_math;\
12557 flag_trapv = saved_trapv;\
12558 folding_initializer = saved_folding_initializer;
12560 tree
12563 {
12564 tree result;
12565 START_FOLD_INIT;
12569 END_FOLD_INIT;
12571 }
12573 tree
12576 {
12577 tree result;
12578 START_FOLD_INIT;
12582 END_FOLD_INIT;
12584 }
12586 tree
12589 {
12590 tree result;
12591 START_FOLD_INIT;
12595 END_FOLD_INIT;
12597 }
12599 #undef START_FOLD_INIT
12600 #undef END_FOLD_INIT
12602 /* Determine if first argument is a multiple of second argument. Return 0 if
12603 it is not, or we cannot easily determined it to be.
12605 An example of the sort of thing we care about (at this point; this routine
12606 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12607 fold cases do now) is discovering that
12609 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12611 is a multiple of
12613 SAVE_EXPR (J * 8)
12615 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12617 This code also handles discovering that
12619 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12621 is a multiple of 8 so we don't have to worry about dealing with a
12622 possible remainder.
12624 Note that we *look* inside a SAVE_EXPR only to determine how it was
12625 calculated; it is not safe for fold to do much of anything else with the
12626 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12627 at run time. For example, the latter example above *cannot* be implemented
12628 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12629 evaluation time of the original SAVE_EXPR is not necessarily the same at
12630 the time the new expression is evaluated. The only optimization of this
12631 sort that would be valid is changing
12633 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12635 divided by 8 to
12637 SAVE_EXPR (I) * SAVE_EXPR (J)
12639 (where the same SAVE_EXPR (J) is used in the original and the
12640 transformed version). */
12642 int
12644 {
12652 {
12654 /* Bitwise and provides a power of two multiple. If the mask is
12655 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12658 /* FALLTHRU */
12671 {
12675 /* const_binop may not detect overflow correctly,
12676 so check for it explicitly here. */
12680 size_one_node,
12681 op1)))
12684 }
12688 /* Can't handle conversions from non-integral or wider integral type. */
12694 /* .. fall through ... */
12711 SIGNED);
12715 }
12716 }
12718 #define tree_expr_nonnegative_warnv_p(X, Y) \
12721 #define RECURSE(X) \
12722 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12724 /* Return true if CODE or TYPE is known to be non-negative. */
12726 static bool
12728 {
12731 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12732 have a signed:1 type (where the value is -1 and 0). */
12735 }
12737 /* Return true if (CODE OP0) 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
12745 {
12750 {
12752 /* We can't return 1 if flag_wrapv is set because
12753 ABS_EXPR<INT_MIN> = INT_MIN. */
12757 {
12760 }
12768 CASE_CONVERT:
12769 {
12774 {
12778 {
12782 }
12783 }
12785 {
12791 }
12792 }
12797 }
12799 /* We don't know sign of `t', so be conservative and return false. */
12801 }
12803 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12804 value is based on the assumption that signed overflow is undefined,
12805 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12806 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12808 bool
12812 {
12817 {
12823 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12824 both unsigned and at least 2 bits shorter than the result. */
12828 {
12833 {
12837 }
12838 }
12843 {
12844 /* x * x is always non-negative for floating point x
12845 or without overflow. */
12848 {
12853 }
12854 }
12856 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12857 both unsigned and their total bits is shorter than the result. */
12861 {
12880 {
12890 }
12891 }
12918 }
12920 /* We don't know sign of `t', so be conservative and return false. */
12922 }
12924 /* Return true if T is known to be non-negative. If the return
12925 value is based on the assumption that signed overflow is undefined,
12926 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12927 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12929 bool
12931 {
12936 {
12950 /* Limit the depth of recursion to avoid quadratic behavior.
12951 This is expected to catch almost all occurrences in practice.
12952 If this code misses important cases that unbounded recursion
12953 would not, passes that need this information could be revised
12954 to provide it through dataflow propagation. */
12962 }
12963 }
12965 /* Return true if T is known to be non-negative. If the return
12966 value is based on the assumption that signed overflow is undefined,
12967 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12968 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12970 bool
12973 {
12975 {
12976 CASE_CFN_ACOS:
12977 CASE_CFN_ACOSH:
12978 CASE_CFN_CABS:
12979 CASE_CFN_COSH:
12980 CASE_CFN_ERFC:
12981 CASE_CFN_EXP:
12982 CASE_CFN_EXP10:
12983 CASE_CFN_EXP2:
12984 CASE_CFN_FABS:
12985 CASE_CFN_FDIM:
12986 CASE_CFN_HYPOT:
12987 CASE_CFN_POW10:
12988 CASE_CFN_FFS:
12989 CASE_CFN_PARITY:
12990 CASE_CFN_POPCOUNT:
12991 CASE_CFN_CLZ:
12992 CASE_CFN_CLRSB:
12995 /* Always true. */
12998 CASE_CFN_SQRT:
12999 /* sqrt(-0.0) is -0.0. */
13004 CASE_CFN_ASINH:
13005 CASE_CFN_ATAN:
13006 CASE_CFN_ATANH:
13007 CASE_CFN_CBRT:
13008 CASE_CFN_CEIL:
13009 CASE_CFN_ERF:
13010 CASE_CFN_EXPM1:
13011 CASE_CFN_FLOOR:
13012 CASE_CFN_FMOD:
13013 CASE_CFN_FREXP:
13014 CASE_CFN_ICEIL:
13015 CASE_CFN_IFLOOR:
13016 CASE_CFN_IRINT:
13017 CASE_CFN_IROUND:
13018 CASE_CFN_LCEIL:
13019 CASE_CFN_LDEXP:
13020 CASE_CFN_LFLOOR:
13021 CASE_CFN_LLCEIL:
13022 CASE_CFN_LLFLOOR:
13023 CASE_CFN_LLRINT:
13024 CASE_CFN_LLROUND:
13025 CASE_CFN_LRINT:
13026 CASE_CFN_LROUND:
13027 CASE_CFN_MODF:
13028 CASE_CFN_NEARBYINT:
13029 CASE_CFN_RINT:
13030 CASE_CFN_ROUND:
13031 CASE_CFN_SCALB:
13032 CASE_CFN_SCALBLN:
13033 CASE_CFN_SCALBN:
13034 CASE_CFN_SIGNBIT:
13035 CASE_CFN_SIGNIFICAND:
13036 CASE_CFN_SINH:
13037 CASE_CFN_TANH:
13038 CASE_CFN_TRUNC:
13039 /* True if the 1st argument is nonnegative. */
13042 CASE_CFN_FMAX:
13043 /* True if the 1st OR 2nd arguments are nonnegative. */
13046 CASE_CFN_FMIN:
13047 /* True if the 1st AND 2nd arguments are nonnegative. */
13050 CASE_CFN_COPYSIGN:
13051 /* True if the 2nd argument is nonnegative. */
13054 CASE_CFN_POWI:
13055 /* True if the 1st argument is nonnegative or the second
13056 argument is an even integer. */
13062 CASE_CFN_POW:
13063 /* True if the 1st argument is nonnegative or the second
13064 argument is an even integer valued real. */
13066 {
13067 REAL_VALUE_TYPE c;
13068 HOST_WIDE_INT n;
13073 {
13074 REAL_VALUE_TYPE cint;
13078 }
13079 }
13084 }
13086 }
13088 /* Return true if T is known to be non-negative. If the return
13089 value is based on the assumption that signed overflow is undefined,
13090 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13091 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13093 static bool
13095 {
13101 {
13103 {
13107 /* If the initializer is non-void, then it's a normal expression
13108 that will be assigned to the slot. */
13112 /* Otherwise, the initializer sets the slot in some way. One common
13113 way is an assignment statement at the end of the initializer. */
13115 {
13123 else
13125 }
13131 }
13134 {
13140 arg0,
13141 arg1,
13143 }
13156 }
13157 }
13159 #undef RECURSE
13160 #undef tree_expr_nonnegative_warnv_p
13162 /* Return true if T is known to be non-negative. If the return
13163 value is based on the assumption that signed overflow is undefined,
13164 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13165 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13167 bool
13169 {
13176 {
13198 }
13201 {
13227 }
13228 }
13230 /* Return true if `t' is known to be non-negative. Handle warnings
13231 about undefined signed overflow. */
13233 bool
13235 {
13242 "determining that expression is always "
13244 WARN_STRICT_OVERFLOW_MISC);
13246 }
13249 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13250 For floating point we further ensure that T is not denormal.
13251 Similar logic is present in nonzero_address in rtlanal.h.
13253 If the return value is based on the assumption that signed overflow
13254 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13255 change *STRICT_OVERFLOW_P. */
13257 bool
13260 {
13262 {
13265 strict_overflow_p);
13268 {
13274 strict_overflow_p));
13275 }
13280 strict_overflow_p);
13284 }
13287 }
13289 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13290 For floating point we further ensure that T is not denormal.
13291 Similar logic is present in nonzero_address in rtlanal.h.
13293 If the return value is based on the assumption that signed overflow
13294 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13295 change *STRICT_OVERFLOW_P. */
13297 bool
13299 tree type,
13300 tree op0,
13302 {
13305 {
13309 {
13310 /* With the presence of negative values it is hard
13311 to say something. */
13318 /* One of operands must be positive and the other non-negative. */
13319 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13320 overflows, on a twos-complement machine the sum of two
13321 nonnegative numbers can never be zero. */
13323 strict_overflow_p)
13325 strict_overflow_p));
13326 }
13331 {
13333 strict_overflow_p)
13335 strict_overflow_p))
13336 {
13339 }
13340 }
13349 {
13352 }
13359 {
13363 /* When both operands are nonzero, then MAX must be too. */
13365 strict_overflow_p))
13368 /* MAX where operand 0 is positive is positive. */
13370 strict_overflow_p);
13371 }
13372 /* MAX where operand 1 is positive is positive. */
13377 {
13381 }
13386 strict_overflow_p)
13388 strict_overflow_p));
13392 }
13395 }
13397 /* Return true when T is an address and is known to be nonzero.
13398 For floating point we further ensure that T is not denormal.
13399 Similar logic is present in nonzero_address in rtlanal.h.
13401 If the return value is based on the assumption that signed overflow
13402 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13403 change *STRICT_OVERFLOW_P. */
13405 bool
13407 {
13410 {
13415 {
13427 /* For objects in symbol table check if we know they are non-zero.
13428 Don't do anything for variables and functions before symtab is built;
13429 it is quite possible that they will be declared weak later. */
13434 /* Function local objects are never NULL. */
13441 /* Constants are never weak. */
13446 }
13454 {
13458 }
13463 }
13465 }
13467 #define integer_valued_real_p(X) \
13470 #define RECURSE(X) \
13471 ((integer_valued_real_p) (X, depth + 1))
13473 /* Return true if the floating point result of (CODE OP0) has an
13474 integer value. We also allow +Inf, -Inf and NaN to be considered
13475 integer values. Return false for signaling NaN.
13477 DEPTH is the current nesting depth of the query. */
13479 bool
13481 {
13483 {
13490 CASE_CONVERT:
13491 {
13498 }
13502 }
13504 }
13506 /* Return true if the floating point result of (CODE OP0 OP1) has an
13507 integer value. We also allow +Inf, -Inf and NaN to be considered
13508 integer values. Return false for signaling NaN.
13510 DEPTH is the current nesting depth of the query. */
13512 bool
13514 {
13516 {
13526 }
13528 }
13530 /* Return true if the floating point result of calling FNDECL with arguments
13531 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13532 considered integer values. Return false for signaling NaN. If FNDECL
13533 takes fewer than 2 arguments, the remaining ARGn are null.
13535 DEPTH is the current nesting depth of the query. */
13537 bool
13539 {
13541 {
13542 CASE_CFN_CEIL:
13543 CASE_CFN_FLOOR:
13544 CASE_CFN_NEARBYINT:
13545 CASE_CFN_RINT:
13546 CASE_CFN_ROUND:
13547 CASE_CFN_TRUNC:
13550 CASE_CFN_FMIN:
13551 CASE_CFN_FMAX:
13556 }
13558 }
13560 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13561 has an integer value. We also allow +Inf, -Inf and NaN to be
13562 considered integer values. Return false for signaling NaN.
13564 DEPTH is the current nesting depth of the query. */
13566 bool
13568 {
13570 {
13578 /* Limit the depth of recursion to avoid quadratic behavior.
13579 This is expected to catch almost all occurrences in practice.
13580 If this code misses important cases that unbounded recursion
13581 would not, passes that need this information could be revised
13582 to provide it through dataflow propagation. */
13586 depth));
13590 }
13592 }
13594 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13595 has an integer value. We also allow +Inf, -Inf and NaN to be
13596 considered integer values. Return false for signaling NaN.
13598 DEPTH is the current nesting depth of the query. */
13600 static bool
13602 {
13604 {
13615 }
13617 }
13619 #undef RECURSE
13620 #undef integer_valued_real_p
13622 /* Return true if the floating point expression T has an integer value.
13623 We also allow +Inf, -Inf and NaN to be considered integer values.
13624 Return false for signaling NaN.
13626 DEPTH is the current nesting depth of the query. */
13628 bool
13630 {
13636 {
13652 }
13655 {
13661 {
13670 }
13674 }
13675 }
13677 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13678 attempt to fold the expression to a constant without modifying TYPE,
13679 OP0 or OP1.
13681 If the expression could be simplified to a constant, then return
13682 the constant. If the expression would not be simplified to a
13683 constant, then return NULL_TREE. */
13685 tree
13687 {
13690 }
13692 /* Given the components of a unary expression CODE, TYPE and OP0,
13693 attempt to fold the expression to a constant without modifying
13694 TYPE or OP0.
13696 If the expression could be simplified to a constant, then return
13697 the constant. If the expression would not be simplified to a
13698 constant, then return NULL_TREE. */
13700 tree
13702 {
13705 }
13707 /* If EXP represents referencing an element in a constant string
13708 (either via pointer arithmetic or array indexing), return the
13709 tree representing the value accessed, otherwise return NULL. */
13711 tree
13713 {
13717 {
13719 tree index;
13720 tree string;
13725 else
13726 {
13730 /* Optimize the special-case of a zero lower bound.
13732 We convert the low_bound to sizetype to avoid some problems
13733 with constant folding. (E.g. suppose the lower bound is 1,
13734 and its mode is QI. Without the conversion,l (ARRAY
13735 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13736 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13742 }
13755 }
13757 }
13759 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13760 an integer constant, real, or fixed-point constant.
13762 TYPE is the type of the result. */
13764 static tree
13766 {
13770 {
13772 {
13779 }
13786 {
13787 FIXED_VALUE_TYPE f;
13792 /* Propagate overflow flags. */
13796 }
13800 }
13803 }
13805 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13806 an integer constant or real constant.
13808 TYPE is the type of the result. */
13810 tree
13812 {
13816 {
13818 {
13819 /* If the value is unsigned or non-negative, then the absolute value
13820 is the same as the ordinary value. */
13824 /* If the value is negative, then the absolute value is
13825 its negation. */
13826 else
13827 {
13832 }
13833 }
13839 else
13845 }
13848 }
13850 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13851 constant. TYPE is the type of the result. */
13853 static tree
13855 {
13859 }
13861 /* Given CODE, a relational operator, the target type, TYPE and two
13862 constant operands OP0 and OP1, return the result of the
13863 relational operation. If the result is not a compile time
13864 constant, then return NULL_TREE. */
13866 static tree
13868 {
13871 /* From here on, the only cases we handle are when the result is
13872 known to be a constant. */
13875 {
13879 /* Handle the cases where either operand is a NaN. */
13881 {
13883 {
13911 }
13914 }
13917 }
13920 {
13924 }
13926 /* Handle equality/inequality of complex constants. */
13928 {
13939 else
13941 }
13944 {
13946 {
13947 /* Have vector comparison with scalar boolean result. */
13952 {
13957 }
13961 }
13968 {
13980 }
13983 }
13985 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13987 To compute GT, swap the arguments and do LT.
13988 To compute GE, do LT and invert the result.
13989 To compute LE, swap the arguments, do LT and invert the result.
13990 To compute NE, do EQ and invert the result.
13992 Therefore, the code below must handle only EQ and LT. */
13995 {
13998 }
14000 /* Note that it is safe to invert for real values here because we
14001 have already handled the one case that it matters. */
14005 {
14008 }
14010 /* Compute a result for LT or EQ if args permit;
14011 Otherwise return T. */
14013 {
14016 else
14018 }
14019 else
14025 }
14027 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14028 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14029 itself. */
14031 tree
14033 {
14034 /* If the expression does not have side effects then we don't have to wrap
14035 it with a cleanup point expression. */
14039 /* If the expression is a return, check to see if the expression inside the
14040 return has no side effects or the right hand side of the modify expression
14041 inside the return. If either don't have side effects set we don't need to
14042 wrap the expression in a cleanup point expression. Note we don't check the
14043 left hand side of the modify because it should always be a return decl. */
14045 {
14052 }
14055 }
14057 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14058 of an indirection through OP0, or NULL_TREE if no simplification is
14059 possible. */
14061 tree
14063 {
14065 tree subtype;
14073 {
14076 /* *&CONST_DECL -> to the value of the const decl. */
14079 /* *&p => p; make sure to handle *&"str"[cst] here. */
14081 {
14085 else
14087 }
14088 /* *(foo *)&fooarray => fooarray[0] */
14091 && (!in_gimple_form
14093 {
14103 }
14104 /* *(foo *)&complexfoo => __real__ complexfoo */
14108 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14111 {
14115 }
14116 }
14120 {
14126 {
14127 tree op00type;
14131 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14134 {
14136 unsigned HOST_WIDE_INT max_offset
14141 {
14148 }
14149 }
14150 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14153 {
14157 }
14158 /* ((foo *)&fooarray)[1] => fooarray[1] */
14161 {
14171 }
14172 }
14173 }
14175 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14178 && (!in_gimple_form
14180 {
14181 tree type_domain;
14191 NULL_TREE);
14192 }
14195 }
14197 /* Builds an expression for an indirection through T, simplifying some
14198 cases. */
14200 tree
14202 {
14210 }
14212 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14214 tree
14216 {
14221 else
14223 }
14225 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14226 whose result is ignored. The type of the returned tree need not be
14227 the same as the original expression. */
14229 tree
14231 {
14237 {
14248 else
14254 {
14270 }
14275 }
14276 }
14278 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14280 tree
14282 {
14288 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14289 have to do anything. Only do this when we are not given a const,
14290 because in that case, this check is more expensive than just
14291 doing it. */
14293 {
14298 }
14300 /* If divisor is a power of two, simplify this to bit manipulation. */
14302 {
14304 {
14318 }
14319 else
14320 {
14321 tree t;
14327 }
14328 }
14329 else
14330 {
14335 }
14338 }
14340 /* Likewise, but round down. */
14342 tree
14344 {
14351 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14352 have to do anything. Only do this when we are not given a const,
14353 because in that case, this check is more expensive than just
14354 doing it. */
14356 {
14361 }
14363 /* If divisor is a power of two, simplify this to bit manipulation. */
14365 {
14366 tree t;
14370 }
14371 else
14372 {
14377 }
14380 }
14382 /* Returns the pointer to the base of the object addressed by EXP and
14383 extracts the information about the offset of the access, storing it
14384 to PBITPOS and POFFSET. */
14386 static tree
14389 {
14390 tree core;
14391 machine_mode mode;
14393 HOST_WIDE_INT bitsize;
14397 {
14402 }
14403 else
14404 {
14408 }
14411 }
14413 /* Returns true if addresses of E1 and E2 differ by a constant, false
14414 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14416 bool
14418 {
14432 {
14442 }
14444 {
14445 /* If only one of the offsets is non-constant, the difference cannot
14446 be a constant. */
14448 }
14449 else
14454 }
14456 /* Return OFF converted to a pointer offset type suitable as offset for
14457 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14458 tree
14460 {
14462 }
14464 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14465 tree
14467 {
14470 }
14472 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14473 tree
14475 {
14478 }
14480 /* Return a char pointer for a C string if it is a string constant
14481 or sum of string constant and integer constant. */
14485 {
14486 tree offset_node;
14499 }
14501 #if CHECKING_P
14505 /* Helper functions for writing tests of folding trees. */
14507 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14509 static void
14511 tree constant)
14512 {
14514 }
14516 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14517 wrapping WRAPPED_EXPR. */
14519 static void
14521 tree wrapped_expr)
14522 {
14527 }
14529 /* Verify that various arithmetic binary operations are folded
14530 correctly. */
14532 static void
14534 {
14540 /* Addition. */
14541 /* 1 <-- (0 + 1) */
14543 one);
14545 one);
14547 /* (nonlvalue)x <-- (x + 0) */
14549 x);
14551 /* Subtraction. */
14552 /* 0 <-- (x - x) */
14554 zero);
14556 x);
14558 /* Multiplication. */
14559 /* 0 <-- (x * 0) */
14561 zero);
14563 /* (nonlvalue)x <-- (x * 1) */
14565 x);
14566 }
14568 /* Run all of the selftests within this file. */
14570 void
14572 {
14574 }