| blob | 16bf45694bfe5e301caa527542d861be49c0647d |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
85 /* Nonzero if we are folding constants inside an initializer; zero
86 otherwise. */
89 /* The following constants represent a bit based encoding of GCC's
90 comparison operators. This encoding simplifies transformations
91 on relational comparison operators, such as AND and OR. */
109 };
143 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
144 Otherwise, return LOC. */
146 static location_t
148 {
151 }
153 /* Similar to protected_set_expr_location, but never modify x in place,
154 if location can and needs to be set, unshare it. */
158 {
164 {
167 }
169 }
170 \f
171 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
172 division and returns the quotient. Otherwise returns
173 NULL_TREE. */
175 tree
177 {
178 widest_int quo;
185 }
186 \f
187 /* This is nonzero if we should defer warnings about undefined
188 overflow. This facility exists because these warnings are a
189 special case. The code to estimate loop iterations does not want
190 to issue any warnings, since it works with expressions which do not
191 occur in user code. Various bits of cleanup code call fold(), but
192 only use the result if it has certain characteristics (e.g., is a
193 constant); that code only wants to issue a warning if the result is
194 used. */
198 /* If a warning about undefined overflow is deferred, this is the
199 warning. Note that this may cause us to turn two warnings into
200 one, but that is fine since it is sufficient to only give one
201 warning per expression. */
205 /* If a warning about undefined overflow is deferred, this is the
206 level at which the warning should be emitted. */
210 /* Start deferring overflow warnings. We could use a stack here to
211 permit nested calls, but at present it is not necessary. */
213 void
215 {
217 }
219 /* Stop deferring overflow warnings. If there is a pending warning,
220 and ISSUE is true, then issue the warning if appropriate. STMT is
221 the statement with which the warning should be associated (used for
222 location information); STMT may be NULL. CODE is the level of the
223 warning--a warn_strict_overflow_code value. This function will use
224 the smaller of CODE and the deferred code when deciding whether to
225 issue the warning. CODE may be zero to mean to always use the
226 deferred code. */
228 void
230 {
232 location_t locus;
237 {
243 }
254 /* Use the smallest code level when deciding to issue the
255 warning. */
264 else
267 }
269 /* Stop deferring overflow warnings, ignoring any deferred
270 warnings. */
272 void
274 {
276 }
278 /* Whether we are deferring overflow warnings. */
280 bool
282 {
284 }
286 /* This is called when we fold something based on the fact that signed
287 overflow is undefined. */
289 void
291 {
293 {
296 {
299 }
300 }
303 }
304 \f
305 /* Return true if the built-in mathematical function specified by CODE
306 is odd, i.e. -f(x) == f(-x). */
308 bool
310 {
312 {
313 CASE_CFN_ASIN:
314 CASE_CFN_ASINH:
315 CASE_CFN_ATAN:
316 CASE_CFN_ATANH:
317 CASE_CFN_CASIN:
318 CASE_CFN_CASINH:
319 CASE_CFN_CATAN:
320 CASE_CFN_CATANH:
321 CASE_CFN_CBRT:
322 CASE_CFN_CPROJ:
323 CASE_CFN_CSIN:
324 CASE_CFN_CSINH:
325 CASE_CFN_CTAN:
326 CASE_CFN_CTANH:
327 CASE_CFN_ERF:
328 CASE_CFN_LLROUND:
329 CASE_CFN_LROUND:
330 CASE_CFN_ROUND:
331 CASE_CFN_SIN:
332 CASE_CFN_SINH:
333 CASE_CFN_TAN:
334 CASE_CFN_TANH:
335 CASE_CFN_TRUNC:
338 CASE_CFN_LLRINT:
339 CASE_CFN_LRINT:
340 CASE_CFN_NEARBYINT:
341 CASE_CFN_RINT:
346 }
348 }
350 /* Check whether we may negate an integer constant T without causing
351 overflow. */
353 bool
355 {
356 tree type;
365 }
367 /* Determine whether an expression T can be cheaply negated using
368 the function negate_expr without introducing undefined overflow. */
370 static bool
372 {
373 tree type;
382 {
387 /* Check that -CST will not overflow type. */
400 /* We want to canonicalize to positive real constants. Pretend
401 that only negative ones can be easily negated. */
409 {
420 }
435 /* -(A + B) -> (-B) - A. */
438 /* -(A + B) -> (-A) - B. */
442 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
451 /* INT_MIN/n * n doesn't overflow while negating one operand it does
452 if n is a (negative) power of two. */
461 /* Fall through. */
476 /* In general we can't negate B in A / B, because if A is INT_MIN and
477 B is 1, we may turn this into INT_MIN / -1 which is undefined
478 and actually traps on some architectures. */
487 /* Negate -((double)float) as (double)(-float). */
489 {
493 }
497 /* Negate -f(x) as f(-x). */
503 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
505 {
509 }
514 }
516 }
518 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
519 simplification is possible.
520 If negate_expr_p would return true for T, NULL_TREE will never be
521 returned. */
523 static tree
525 {
527 tree tem;
530 {
531 /* Convert - (~A) to A + 1. */
557 {
562 }
566 {
571 {
575 }
578 }
601 {
602 /* -(A + B) -> (-B) - A. */
604 {
608 }
610 /* -(A + B) -> (-A) - B. */
612 {
616 }
617 }
621 /* - (A - B) -> B - A */
632 /* Fall through. */
636 {
645 }
657 /* In general we can't negate B in A / B, because if A is INT_MIN and
658 B is 1, we may turn this into INT_MIN / -1 which is undefined
659 and actually traps on some architectures. */
671 /* Convert -((double)float) into (double)(-float). */
673 {
677 }
681 /* Negate -f(x) as f(-x). */
684 {
690 }
694 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
696 {
699 {
706 }
707 }
712 }
715 }
717 /* A wrapper for fold_negate_expr_1. */
719 static tree
721 {
728 }
730 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
731 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
732 return NULL_TREE. */
734 static tree
736 {
738 location_t loc;
751 }
752 \f
753 /* Split a tree IN into a constant, literal and variable parts that could be
754 combined with CODE to make IN. "constant" means an expression with
755 TREE_CONSTANT but that isn't an actual constant. CODE must be a
756 commutative arithmetic operation. Store the constant part into *CONP,
757 the literal in *LITP and return the variable part. If a part isn't
758 present, set it to null. If the tree does not decompose in this way,
759 return the entire tree as the variable part and the other parts as null.
761 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
762 case, we negate an operand that was subtracted. Except if it is a
763 literal for which we use *MINUS_LITP instead.
765 If NEGATE_P is true, we are negating all of IN, again except a literal
766 for which we use *MINUS_LITP instead. If a variable part is of pointer
767 type, it is negated after converting to TYPE. This prevents us from
768 generating illegal MINUS pointer expression. LOC is the location of
769 the converted variable part.
771 If IN is itself a literal or constant, return it as appropriate.
773 Note that we do not guarantee that any of the three values will be the
774 same type as IN, but they will have the same signedness and mode. */
776 static tree
780 {
788 /* Strip any conversions that don't change the machine mode or signedness. */
797 /* We can associate addition and subtraction together (even
798 though the C standard doesn't say so) for integers because
799 the value is not affected. For reals, the value might be
800 affected, so we can't. */
806 {
812 /* First see if either of the operands is a literal, then a constant. */
825 /* If we haven't dealt with either operand, this is not a case we can
826 decompose. Otherwise, VAR is either of the ones remaining, if any. */
831 else
834 /* Now do any needed negations. */
841 }
846 {
847 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
848 when IN is constant. */
851 }
852 else
856 {
869 }
879 }
881 /* Re-associate trees split by the above function. T1 and T2 are
882 either expressions to associate or null. Return the new
883 expression, if any. LOC is the location of the new expression. If
884 we build an operation, do it in TYPE and with CODE. */
886 static tree
888 {
890 {
893 }
897 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
898 try to fold this since we will have infinite recursion. But do
899 deal with any NEGATE_EXPRs. */
903 {
905 {
918 }
920 {
923 }
927 }
931 }
932 \f
933 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
934 for use in int_const_binop, size_binop and size_diffop. */
936 static bool
938 {
945 {
954 }
959 }
962 /* Combine two integer constants ARG1 and ARG2 under operation CODE
963 to produce a new constant. Return NULL_TREE if we don't know how
964 to evaluate CODE at compile-time. */
966 static tree
969 {
970 wide_int res;
971 tree t;
979 {
995 {
999 else
1001 }
1004 /* It's unclear from the C standard whether shifts can overflow.
1005 The following code ignores overflow; perhaps a C standard
1006 interpretation ruling is needed. */
1008 else
1015 {
1019 else
1021 }
1025 else
1104 }
1112 }
1114 tree
1116 {
1118 }
1120 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1121 constant. We assume ARG1 and ARG2 have the same data type, or at least
1122 are the same kind of constant and the same machine mode. Return zero if
1123 combining the constants is not allowed in the current operating mode. */
1125 static tree
1127 {
1128 /* Sanity check for the recursive cases. */
1136 {
1142 }
1145 {
1146 machine_mode mode;
1147 REAL_VALUE_TYPE d1;
1148 REAL_VALUE_TYPE d2;
1149 REAL_VALUE_TYPE value;
1150 REAL_VALUE_TYPE result;
1154 /* The following codes are handled by real_arithmetic. */
1156 {
1167 }
1175 /* Don't perform operation if we honor signaling NaNs and
1176 either operand is a signaling NaN. */
1182 /* Don't perform operation if it would raise a division
1183 by zero exception. */
1189 /* If either operand is a NaN, just return it. Otherwise, set up
1190 for floating-point trap; we return an overflow. */
1192 {
1193 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1194 is off. */
1198 }
1200 {
1201 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1202 is off. */
1206 }
1211 /* Don't constant fold this floating point operation if
1212 the result has overflowed and flag_trapping_math. */
1220 /* Don't constant fold this floating point operation if the
1221 result may dependent upon the run-time rounding mode and
1222 flag_rounding_math is set, or if GCC's software emulation
1223 is unable to accurately represent the result. */
1233 }
1236 {
1237 FIXED_VALUE_TYPE f1;
1238 FIXED_VALUE_TYPE f2;
1239 FIXED_VALUE_TYPE result;
1244 /* The following codes are handled by fixed_arithmetic. */
1246 {
1258 {
1265 }
1270 }
1277 /* Propagate overflow flags. */
1281 }
1284 {
1293 {
1304 mpc_mul);
1318 mpc_div);
1319 /* Fallthru. */
1325 {
1326 /* Keep this algorithm in sync with
1327 tree-complex.c:expand_complex_div_straight().
1329 Expand complex division to scalars, straightforward algorithm.
1330 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1331 t = br*br + bi*bi
1332 */
1333 tree magsquared
1337 tree t1
1341 tree t2
1348 }
1349 else
1350 {
1351 /* Keep this algorithm in sync with
1352 tree-complex.c:expand_complex_div_wide().
1354 Expand complex division to scalars, modified algorithm to minimize
1355 overflow with wide input ranges. */
1361 {
1362 /* In the TRUE branch, we compute
1363 ratio = br/bi;
1364 div = (br * ratio) + bi;
1365 tr = (ar * ratio) + ai;
1366 ti = (ai * ratio) - ar;
1367 tr = tr / div;
1368 ti = ti / div; */
1379 }
1380 else
1381 {
1382 /* In the FALSE branch, we compute
1383 ratio = d/c;
1384 divisor = (d * ratio) + c;
1385 tr = (b * ratio) + a;
1386 ti = b - (a * ratio);
1387 tr = tr / div;
1388 ti = ti / div; */
1400 }
1401 }
1406 }
1410 }
1414 {
1420 {
1426 /* It is possible that const_binop cannot handle the given
1427 code and return NULL_TREE */
1430 }
1433 }
1435 /* Shifts allow a scalar offset for a vector. */
1438 {
1444 {
1449 /* It is possible that const_binop cannot handle the given
1450 code and return NULL_TREE. */
1453 }
1456 }
1458 }
1460 /* Overload that adds a TYPE parameter to be able to dispatch
1461 to fold_relational_const. */
1463 tree
1465 {
1469 /* ??? Until we make the const_binop worker take the type of the
1470 result as argument put those cases that need it here. */
1472 {
1483 {
1499 {
1505 }
1508 }
1514 {
1539 {
1552 }
1555 }
1558 }
1563 /* Make sure type and arg0 have the same saturating flag. */
1568 }
1570 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1571 Return zero if computing the constants is not possible. */
1573 tree
1575 {
1576 /* Don't perform the operation, other than NEGATE and ABS, if
1577 flag_signaling_nans is on and the operand is a signaling NaN. */
1586 {
1587 CASE_CONVERT:
1594 /* If the source address is 0, and the source address space
1595 cannot have a valid object at 0, fold to dest type null. */
1606 {
1607 /* Can't call fold_negate_const directly here as that doesn't
1608 handle all cases and we might not be able to negate some
1609 constants. */
1614 }
1623 {
1627 }
1633 /* Perform BIT_NOT_EXPR on each element individually. */
1635 {
1637 tree elem;
1642 {
1648 }
1651 }
1673 {
1692 else
1696 {
1700 }
1703 }
1708 {
1722 {
1727 }
1730 {
1734 }
1737 }
1741 }
1744 }
1746 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1747 indicates which particular sizetype to create. */
1749 tree
1751 {
1753 }
1754 \f
1755 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1756 is a tree code. The type of the result is taken from the operands.
1757 Both must be equivalent integer types, ala int_binop_types_match_p.
1758 If the operands are constant, so is the result. */
1760 tree
1762 {
1771 /* Handle the special case of two integer constants faster. */
1773 {
1774 /* And some specific cases even faster than that. */
1776 {
1781 }
1783 {
1786 }
1788 {
1791 }
1793 /* Handle general case of two integer constants. For sizetype
1794 constant calculations we always want to know about overflow,
1795 even in the unsigned case. */
1797 }
1800 }
1802 /* Given two values, either both of sizetype or both of bitsizetype,
1803 compute the difference between the two values. Return the value
1804 in signed type corresponding to the type of the operands. */
1806 tree
1808 {
1810 tree ctype;
1815 /* If the type is already signed, just do the simple thing. */
1823 else
1826 /* If either operand is not a constant, do the conversions to the signed
1827 type and subtract. The hardware will do the right thing with any
1828 overflow in the subtraction. */
1834 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1835 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1836 overflow) and negate (which can't either). Special-case a result
1837 of zero while we're here. */
1843 else
1847 MINUS_EXPR,
1849 }
1850 \f
1851 /* A subroutine of fold_convert_const handling conversions of an
1852 INTEGER_CST to another integer type. */
1854 static tree
1856 {
1857 /* Given an integer constant, make new constant with new type,
1858 appropriately sign-extended or truncated. Use widest_int
1859 so that any extension is done according ARG1's type. */
1863 }
1865 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1866 to an integer type. */
1868 static tree
1870 {
1872 tree t;
1874 /* The following code implements the floating point to integer
1875 conversion rules required by the Java Language Specification,
1876 that IEEE NaNs are mapped to zero and values that overflow
1877 the target precision saturate, i.e. values greater than
1878 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1879 are mapped to INT_MIN. These semantics are allowed by the
1880 C and C++ standards that simply state that the behavior of
1881 FP-to-integer conversion is unspecified upon overflow. */
1883 wide_int val;
1884 REAL_VALUE_TYPE r;
1888 {
1895 }
1897 /* If R is NaN, return zero and show we have an overflow. */
1899 {
1902 }
1904 /* See if R is less than the lower bound or greater than the
1905 upper bound. */
1908 {
1912 {
1915 }
1916 }
1919 {
1922 {
1925 {
1928 }
1929 }
1930 }
1937 }
1939 /* A subroutine of fold_convert_const handling conversions of a
1940 FIXED_CST to an integer type. */
1942 static tree
1944 {
1945 tree t;
1947 scalar_mode mode;
1949 /* Right shift FIXED_CST to temp by fbit. */
1953 {
1955 HOST_BITS_PER_DOUBLE_INT,
1958 /* Left shift temp to temp_trunc by fbit. */
1960 HOST_BITS_PER_DOUBLE_INT,
1962 }
1963 else
1964 {
1967 }
1969 /* If FIXED_CST is negative, we need to round the value toward 0.
1970 By checking if the fractional bits are not zero to add 1 to temp. */
1976 /* Given a fixed-point constant, make new constant with new type,
1977 appropriately sign-extended or truncated. */
1985 }
1987 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1988 to another floating point type. */
1990 static tree
1992 {
1993 REAL_VALUE_TYPE value;
1994 tree t;
1996 /* Don't perform the operation if flag_signaling_nans is on
1997 and the operand is a signaling NaN. */
2005 /* If converting an infinity or NAN to a representation that doesn't
2006 have one, set the overflow bit so that we can produce some kind of
2007 error message at the appropriate point if necessary. It's not the
2008 most user-friendly message, but it's better than nothing. */
2015 /* Regular overflow, conversion produced an infinity in a mode that
2016 can't represent them. */
2021 else
2024 }
2026 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2027 to a floating point type. */
2029 static tree
2031 {
2032 REAL_VALUE_TYPE value;
2033 tree t;
2041 }
2043 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2044 to another fixed-point type. */
2046 static tree
2048 {
2049 FIXED_VALUE_TYPE value;
2050 tree t;
2057 /* Propagate overflow flags. */
2061 }
2063 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2064 to a fixed-point type. */
2066 static tree
2068 {
2069 FIXED_VALUE_TYPE value;
2070 tree t;
2072 double_int di;
2079 else
2087 /* Propagate overflow flags. */
2091 }
2093 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2094 to a fixed-point type. */
2096 static tree
2098 {
2099 FIXED_VALUE_TYPE value;
2100 tree t;
2108 /* Propagate overflow flags. */
2112 }
2114 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2115 type TYPE. If no simplification can be done return NULL_TREE. */
2117 static tree
2119 {
2125 {
2132 }
2134 {
2141 }
2143 {
2150 }
2152 {
2155 {
2160 {
2166 }
2168 }
2169 }
2171 }
2173 /* Construct a vector of zero elements of vector type TYPE. */
2175 static tree
2177 {
2178 tree t;
2182 }
2184 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2186 bool
2188 {
2203 {
2218 }
2219 }
2221 /* Convert expression ARG to type TYPE. Used by the middle-end for
2222 simple conversions in preference to calling the front-end's convert. */
2224 tree
2226 {
2228 tree tem;
2239 {
2242 /* Handle conversions between pointers to different address spaces. */
2247 /* fall through */
2252 {
2256 }
2270 {
2274 }
2276 {
2280 }
2282 {
2286 }
2289 {
2307 }
2312 {
2316 }
2319 {
2333 }
2337 {
2346 integer_zero_node));
2348 {
2352 {
2358 }
2366 }
2370 }
2388 }
2389 fold_convert_exit:
2392 }
2393 \f
2394 /* Return false if expr can be assumed not to be an lvalue, true
2395 otherwise. */
2397 static bool
2399 {
2400 /* We only need to wrap lvalue tree codes. */
2402 {
2433 /* Assume the worst for front-end tree codes. */
2437 }
2440 }
2442 /* Return an expr equal to X but certainly not valid as an lvalue. */
2444 tree
2446 {
2447 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2448 us. */
2455 }
2457 /* When pedantic, return an expr equal to X but certainly not valid as a
2458 pedantic lvalue. Otherwise, return X. */
2460 static tree
2462 {
2464 }
2465 \f
2466 /* Given a tree comparison code, return the code that is the logical inverse.
2467 It is generally not safe to do this for floating-point comparisons, except
2468 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2469 ERROR_MARK in this case. */
2471 enum tree_code
2473 {
2479 {
2510 }
2511 }
2513 /* Similar, but return the comparison that results if the operands are
2514 swapped. This is safe for floating-point. */
2516 enum tree_code
2518 {
2520 {
2546 }
2547 }
2550 /* Convert a comparison tree code from an enum tree_code representation
2551 into a compcode bit-based encoding. This function is the inverse of
2552 compcode_to_comparison. */
2554 static enum comparison_code
2556 {
2558 {
2589 }
2590 }
2592 /* Convert a compcode bit-based encoding of a comparison operator back
2593 to GCC's enum tree_code representation. This function is the
2594 inverse of comparison_to_compcode. */
2596 static enum tree_code
2598 {
2600 {
2631 }
2632 }
2634 /* Return a tree for the comparison which is the combination of
2635 doing the AND or OR (depending on CODE) of the two operations LCODE
2636 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2637 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2638 if this makes the transformation invalid. */
2640 tree
2645 {
2652 {
2663 }
2666 {
2667 /* Eliminate unordered comparisons, as well as LTGT and ORD
2668 which are not used unless the mode has NaNs. */
2674 }
2676 {
2677 /* Check that the original operation and the optimized ones will trap
2678 under the same condition. */
2689 /* In a short-circuited boolean expression the LHS might be
2690 such that the RHS, if evaluated, will never trap. For
2691 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2692 if neither x nor y is NaN. (This is a mixed blessing: for
2693 example, the expression above will never trap, hence
2694 optimizing it to x < y would be invalid). */
2699 /* If the comparison was short-circuited, and only the RHS
2700 trapped, we may now generate a spurious trap. */
2705 /* If we changed the conditions that cause a trap, we lose. */
2708 }
2714 else
2715 {
2720 }
2721 }
2722 \f
2723 /* Return nonzero if two operands (typically of the same tree node)
2724 are necessarily equal. FLAGS modifies behavior as follows:
2726 If OEP_ONLY_CONST is set, only return nonzero for constants.
2727 This function tests whether the operands are indistinguishable;
2728 it does not test whether they are equal using C's == operation.
2729 The distinction is important for IEEE floating point, because
2730 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2731 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2733 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2734 even though it may hold multiple values during a function.
2735 This is because a GCC tree node guarantees that nothing else is
2736 executed between the evaluation of its "operands" (which may often
2737 be evaluated in arbitrary order). Hence if the operands themselves
2738 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2739 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2740 unset means assuming isochronic (or instantaneous) tree equivalence.
2741 Unless comparing arbitrary expression trees, such as from different
2742 statements, this flag can usually be left unset.
2744 If OEP_PURE_SAME is set, then pure functions with identical arguments
2745 are considered the same. It is used when the caller has other ways
2746 to ensure that global memory is unchanged in between.
2748 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2749 not values of expressions.
2751 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2752 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2754 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2755 any operand with side effect. This is unnecesarily conservative in the
2756 case we know that arg0 and arg1 are in disjoint code paths (such as in
2757 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2758 addresses with TREE_CONSTANT flag set so we know that &var == &var
2759 even if var is volatile. */
2761 int
2763 {
2764 /* When checking, verify at the outermost operand_equal_p call that
2765 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2766 hash value. */
2768 {
2770 {
2772 {
2779 }
2781 }
2782 else
2784 }
2786 /* If either is ERROR_MARK, they aren't equal. */
2792 /* Similar, if either does not have a type (like a released SSA name),
2793 they aren't equal. */
2797 /* We cannot consider pointers to different address space equal. */
2804 /* Check equality of integer constants before bailing out due to
2805 precision differences. */
2807 {
2808 /* Address of INTEGER_CST is not defined; check that we did not forget
2809 to drop the OEP_ADDRESS_OF flags. */
2812 }
2815 {
2816 /* If both types don't have the same signedness, then we can't consider
2817 them equal. We must check this before the STRIP_NOPS calls
2818 because they may change the signedness of the arguments. As pointers
2819 strictly don't have a signedness, require either two pointers or
2820 two non-pointers as well. */
2826 /* If both types don't have the same precision, then it is not safe
2827 to strip NOPs. */
2834 }
2835 #if 0
2836 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2837 sanity check once the issue is solved. */
2838 else
2839 /* Addresses of conversions and SSA_NAMEs (and many other things)
2840 are not defined. Check that we did not forget to drop the
2841 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2844 #endif
2846 /* In case both args are comparisons but with different comparison
2847 code, try to swap the comparison operands of one arg to produce
2848 a match and compare that variant. */
2852 {
2860 }
2863 {
2864 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2866 ;
2868 {
2869 /* If we are interested in comparing addresses ignore
2870 MEM_REF wrappings of the base that can appear just for
2871 TBAA reasons. */
2885 }
2886 else
2888 }
2890 /* When not checking adddresses, this is needed for conversions and for
2891 COMPONENT_REF. Might as well play it safe and always test this. */
2898 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2899 We don't care about side effects in that case because the SAVE_EXPR
2900 takes care of that for us. In all other cases, two expressions are
2901 equal if they have no side effects. If we have two identical
2902 expressions with side effects that should be treated the same due
2903 to the only side effects being identical SAVE_EXPR's, that will
2904 be detected in the recursive calls below.
2905 If we are taking an invariant address of two identical objects
2906 they are necessarily equal as well. */
2913 /* Next handle constant cases, those for which we can return 1 even
2914 if ONLY_CONST is set. */
2917 {
2931 {
2932 /* If we do not distinguish between signed and unsigned zero,
2933 consider them equal. */
2936 }
2940 {
2947 {
2951 }
2953 }
2957 flags)
2959 flags));
2970 flags | OEP_ADDRESS_OF
2973 /* In GIMPLE empty constructors are allowed in initializers of
2974 aggregates. */
2978 }
2983 /* Define macros to test an operand from arg0 and arg1 for equality and a
2984 variant that allows null and views null as being different from any
2985 non-null value. In the latter case, if either is null, the both
2986 must be; otherwise, do the normal comparison. */
2987 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2988 TREE_OPERAND (arg1, N), flags)
2990 #define OP_SAME_WITH_NULL(N) \
2991 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2992 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2995 {
2997 /* Two conversions are equal only if signedness and modes match. */
2999 {
3000 CASE_CONVERT:
3008 }
3018 /* For commutative ops, allow the other order. */
3026 /* If either of the pointer (or reference) expressions we are
3027 dereferencing contain a side effect, these cannot be equal,
3028 but their addresses can be. */
3035 {
3045 /* Require the same offset. */
3051 /* Fallthru. */
3059 {
3060 /* Require equal access sizes */
3066 flags)))
3068 /* Verify that access happens in similar types. */
3071 /* Verify that accesses are TBAA compatible. */
3080 /* Verify that alignment is compatible. */
3084 }
3087 /* TARGET_MEM_REF require equal extra operands. */
3098 /* Compare the array index by value if it is constant first as we
3099 may have different types but same value here. */
3105 /* Compare low bound and element size as with OEP_ADDRESS_OF
3106 we have to account for the offset of the ref. */
3111 array_ref_low_bound
3115 array_ref_element_size
3117 flags))));
3120 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3121 may be NULL when we're called to compare MEM_EXPRs. */
3136 }
3140 {
3142 /* Be sure we pass right ADDRESS_OF flag. */
3160 /* The multiplcation operands are commutative. */
3161 /* FALLTHRU */
3169 /* Otherwise take into account this is a commutative operation. */
3182 /* BIT_INSERT_EXPR has an implict operand as the type precision
3183 of op1. Need to check to make sure they are the same. */
3189 /* FALLTHRU */
3214 }
3218 {
3222 /* If not both CALL_EXPRs are either internal or normal function
3223 functions, then they are not equal. */
3226 {
3227 /* If the CALL_EXPRs call different internal functions, then they
3228 are not equal. */
3231 }
3232 else
3233 {
3234 /* If the CALL_EXPRs call different functions, then they are not
3235 equal. */
3237 flags))
3239 }
3241 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3242 {
3246 else
3250 }
3252 /* Now see if all the arguments are the same. */
3253 {
3264 /* If we get here and both argument lists are exhausted
3265 then the CALL_EXPRs are equal. */
3267 }
3270 }
3273 /* Consider __builtin_sqrt equal to sqrt. */
3281 {
3282 /* In GIMPLE constructors are used only to build vectors from
3283 elements. Individual elements in the constructor must be
3284 indexed in increasing order and form an initial sequence.
3286 We make no effort to compare constructors in generic.
3287 (see sem_variable::equals in ipa-icf which can do so for
3288 constants). */
3293 /* Be sure that vectors constructed have the same representation.
3294 We only tested element precision and modes to match.
3295 Vectors may be BLKmode and thus also check that the number of
3296 parts match. */
3309 {
3314 /* In GIMPLE the indexes can be either NULL or matching i.
3315 Double check this so we won't get false
3316 positives for GENERIC. */
3324 }
3326 }
3329 {
3330 /* Compare the STATEMENT_LISTs. */
3336 {
3337 /* The lists don't have the same number of statements. */
3343 OEP_LEXICOGRAPHIC))
3345 }
3346 }
3351 {
3358 }
3362 }
3364 #undef OP_SAME
3365 #undef OP_SAME_WITH_NULL
3366 }
3367 \f
3368 /* Similar to operand_equal_p, but strip nops first. */
3370 static bool
3372 {
3380 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3381 and see if the inner values are the same. This removes any
3382 signedness comparison, which doesn't matter here. */
3389 }
3390 \f
3391 /* See if ARG is an expression that is either a comparison or is performing
3392 arithmetic on comparisons. The comparisons must only be comparing
3393 two different values, which will be stored in *CVAL1 and *CVAL2; if
3394 they are nonzero it means that some operands have already been found.
3395 No variables may be used anywhere else in the expression except in the
3396 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3397 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3399 If this is true, return 1. Otherwise, return zero. */
3401 static int
3403 {
3407 /* We can handle some of the tcc_expression cases here. */
3417 {
3418 /* If we've already found a CVAL1 or CVAL2, this expression is
3419 two complex to handle. */
3425 }
3428 {
3451 /* First see if we can handle the first operand, then the second. For
3452 the second operand, we know *CVAL1 can't be zero. It must be that
3453 one side of the comparison is each of the values; test for the
3454 case where this isn't true by failing if the two operands
3455 are the same. */
3464 ;
3468 ;
3469 else
3473 ;
3477 ;
3478 else
3485 }
3486 }
3487 \f
3488 /* ARG is a tree that is known to contain just arithmetic operations and
3489 comparisons. Evaluate the operations in the tree substituting NEW0 for
3490 any occurrence of OLD0 as an operand of a comparison and likewise for
3491 NEW1 and OLD1. */
3493 static tree
3496 {
3501 /* We can handle some of the tcc_expression cases here. */
3509 {
3524 {
3543 }
3544 /* Fall through - ??? */
3547 {
3551 /* We need to check both for exact equality and tree equality. The
3552 former will be true if the operand has a side-effect. In that
3553 case, we know the operand occurred exactly once. */
3566 }
3570 }
3571 }
3572 \f
3573 /* Return a tree for the case when the result of an expression is RESULT
3574 converted to TYPE and OMITTED was previously an operand of the expression
3575 but is now not needed (e.g., we folded OMITTED * 0).
3577 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3578 the conversion of RESULT to TYPE. */
3580 tree
3582 {
3585 /* If the resulting operand is an empty statement, just return the omitted
3586 statement casted to void. */
3596 }
3598 /* Return a tree for the case when the result of an expression is RESULT
3599 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3600 of the expression but are now not needed.
3602 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3603 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3604 evaluated before OMITTED2. Otherwise, if neither has side effects,
3605 just do the conversion of RESULT to TYPE. */
3607 tree
3610 {
3619 }
3621 \f
3622 /* Return a simplified tree node for the truth-negation of ARG. This
3623 never alters ARG itself. We assume that ARG is an operation that
3624 returns a truth value (0 or 1).
3626 FIXME: one would think we would fold the result, but it causes
3627 problems with the dominator optimizer. */
3629 static tree
3631 {
3636 /* If this is a comparison, we can simply invert it, except for
3637 floating-point non-equality comparisons, in which case we just
3638 enclose a TRUTH_NOT_EXPR around what we have. */
3641 {
3644 && flag_trapping_math
3658 }
3661 {
3680 /* Here we can invert either operand. We invert the first operand
3681 unless the second operand is a TRUTH_NOT_EXPR in which case our
3682 result is the XOR of the first operand with the inside of the
3683 negation of the second operand. */
3688 else
3711 {
3718 /* A COND_EXPR may have a throw as one operand, which
3719 then has void type. Just leave void operands
3720 as they are. */
3726 }
3738 CASE_CONVERT:
3742 /* fall through */
3764 }
3765 }
3767 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3768 assume that ARG is an operation that returns a truth value (0 or 1
3769 for scalars, 0 or -1 for vectors). Return the folded expression if
3770 folding is successful. Otherwise, return NULL_TREE. */
3772 static tree
3774 {
3777 ? BIT_NOT_EXPR
3780 }
3782 /* Return a simplified tree node for the truth-negation of ARG. This
3783 never alters ARG itself. We assume that ARG is an operation that
3784 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3786 tree
3788 {
3794 ? BIT_NOT_EXPR
3797 }
3799 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3800 with code CODE. This optimization is unsafe. */
3801 static tree
3804 {
3808 /* (A / C) +- (B / C) -> (A +- B) / C. */
3818 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3823 {
3835 }
3838 }
3839 \f
3840 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3841 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3842 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3843 is the original memory reference used to preserve the alias set of
3844 the access. */
3846 static tree
3850 {
3853 /* Attempt not to lose the access path if possible. */
3855 {
3857 machine_mode nmode;
3859 tree noffset;
3869 && !reversep
3870 && !nreversep
3872 {
3875 }
3876 }
3885 {
3892 }
3907 }
3909 /* Optimize a bit-field compare.
3911 There are two cases: First is a compare against a constant and the
3912 second is a comparison of two items where the fields are at the same
3913 bit position relative to the start of a chunk (byte, halfword, word)
3914 large enough to contain it. In these cases we can avoid the shift
3915 implicit in bitfield extractions.
3917 For constants, we emit a compare of the shifted constant with the
3918 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3919 compared. For two fields at the same position, we do the ANDs with the
3920 similar mask and compare the result of the ANDs.
3922 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3923 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3924 are the left and right operands of the comparison, respectively.
3926 If the optimization described above can be done, we return the resulting
3927 tree. Otherwise we return zero. */
3929 static tree
3932 {
3935 tree unsigned_type;
3938 scalar_int_mode nmode;
3943 tree mask;
3944 tree offset;
3946 /* Get all the information about the extractions being done. If the bit size
3947 if the same as the size of the underlying object, we aren't doing an
3948 extraction at all and so can do nothing. We also don't want to
3949 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3950 then will no longer be able to replace it. */
3959 else
3960 {
3961 /* If this is not a constant, we can only do something if bit positions,
3962 sizes, signedness and storage order are the same. */
3963 rinner
3971 }
3973 /* Honor the C++ memory model and mimic what RTL expansion does. */
3977 {
3981 }
3983 /* See if we can find a mode to refer to this field. We should be able to,
3984 but fail if we can't. */
3992 /* Set signed and unsigned types of the precision of this mode for the
3993 shifts below. */
3996 /* Compute the bit position and size for the new reference and our offset
3997 within it. If the new reference is the same size as the original, we
3998 won't optimize anything, so return zero. */
4008 /* Make the mask to be used against the extracted field. */
4015 /* If not comparing with constant, just rework the comparison
4016 and return. */
4020 unsigned_type,
4023 mask),
4026 unsigned_type,
4029 mask));
4031 /* Otherwise, we are handling the constant case. See if the constant is too
4032 big for the field. Warn and return a tree for 0 (false) if so. We do
4033 this not only for its own sake, but to avoid having to test for this
4034 error case below. If we didn't, we might generate wrong code.
4036 For unsigned fields, the constant shifted right by the field length should
4037 be all zero. For signed fields, the high-order bits should agree with
4038 the sign bit. */
4041 {
4043 {
4047 }
4048 }
4049 else
4050 {
4053 {
4057 }
4058 }
4060 /* Single-bit compares should always be against zero. */
4062 {
4065 }
4067 /* Make a new bitfield reference, shift the constant over the
4068 appropriate number of bits and mask it with the computed mask
4069 (in case this was a signed field). If we changed it, make a new one. */
4077 mask);
4082 }
4083 \f
4084 /* Subroutine for fold_truth_andor_1: decode a field reference.
4086 If EXP is a comparison reference, we return the innermost reference.
4088 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4089 set to the starting bit number.
4091 If the innermost field can be completely contained in a mode-sized
4092 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4094 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4095 otherwise it is not changed.
4097 *PUNSIGNEDP is set to the signedness of the field.
4099 *PREVERSEP is set to the storage order of the field.
4101 *PMASK is set to the mask used. This is either contained in a
4102 BIT_AND_EXPR or derived from the width of the field.
4104 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4106 Return 0 if this is not a component reference or is one that we can't
4107 do anything with. */
4109 static tree
4114 {
4119 tree unsigned_type;
4122 /* All the optimizations using this function assume integer fields.
4123 There are problems with FP fields since the type_for_size call
4124 below can fail for, e.g., XFmode. */
4128 /* We are interested in the bare arrangement of bits, so strip everything
4129 that doesn't affect the machine mode. However, record the type of the
4130 outermost expression if it may matter below. */
4137 {
4143 }
4150 /* Reject out-of-bound accesses (PR79731). */
4158 /* If the number of bits in the reference is the same as the bitsize of
4159 the outer type, then the outer type gives the signedness. Otherwise
4160 (in case of a small bitfield) the signedness is unchanged. */
4164 /* Compute the mask to access the bitfield. */
4173 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4181 }
4183 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4184 bit positions and MASK is SIGNED. */
4186 static int
4188 {
4192 /* If this function returns true when the type of the mask is
4193 UNSIGNED, then there will be errors. In particular see
4194 gcc.c-torture/execute/990326-1.c. There does not appear to be
4195 any documentation paper trail as to why this is so. But the pre
4196 wide-int worked with that restriction and it has been preserved
4197 here. */
4202 }
4204 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4205 represents the sign bit of EXP's type. If EXP represents a sign
4206 or zero extension, also test VAL against the unextended type.
4207 The return value is the (sub)expression whose sign bit is VAL,
4208 or NULL_TREE otherwise. */
4210 tree
4212 {
4214 tree t;
4216 /* Tree EXP must have an integral type. */
4221 /* Tree VAL must be an integer constant. */
4230 /* Handle extension from a narrower type. */
4236 }
4238 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4239 to be evaluated unconditionally. */
4241 static int
4243 {
4244 /* Strip any conversions that don't change the machine mode. */
4253 /* Don't regard global variables as simple. They may be
4254 allocated in ways unknown to the compiler (shared memory,
4255 #pragma weak, etc). */
4258 /* Weakrefs are not safe to be read, since they can be NULL.
4259 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4260 have DECL_WEAK flag set. */
4262 /* Loading a static variable is unduly expensive, but global
4263 registers aren't expensive. */
4265 }
4267 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4268 to be evaluated unconditionally.
4269 I addition to simple_operand_p, we assume that comparisons, conversions,
4270 and logic-not operations are simple, if their operands are simple, too. */
4272 static bool
4274 {
4294 }
4296 \f
4297 /* The following functions are subroutines to fold_range_test and allow it to
4298 try to change a logical combination of comparisons into a range test.
4300 For example, both
4301 X == 2 || X == 3 || X == 4 || X == 5
4302 and
4303 X >= 2 && X <= 5
4304 are converted to
4305 (unsigned) (X - 2) <= 3
4307 We describe each set of comparisons as being either inside or outside
4308 a range, using a variable named like IN_P, and then describe the
4309 range with a lower and upper bound. If one of the bounds is omitted,
4310 it represents either the highest or lowest value of the type.
4312 In the comments below, we represent a range by two numbers in brackets
4313 preceded by a "+" to designate being inside that range, or a "-" to
4314 designate being outside that range, so the condition can be inverted by
4315 flipping the prefix. An omitted bound is represented by a "-". For
4316 example, "- [-, 10]" means being outside the range starting at the lowest
4317 possible value and ending at 10, in other words, being greater than 10.
4318 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4319 always false.
4321 We set up things so that the missing bounds are handled in a consistent
4322 manner so neither a missing bound nor "true" and "false" need to be
4323 handled using a special case. */
4325 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4326 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4327 and UPPER1_P are nonzero if the respective argument is an upper bound
4328 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4329 must be specified for a comparison. ARG1 will be converted to ARG0's
4330 type if both are specified. */
4332 static tree
4335 {
4336 tree tem;
4340 /* If neither arg represents infinity, do the normal operation.
4341 Else, if not a comparison, return infinity. Else handle the special
4342 comparison rules. Note that most of the cases below won't occur, but
4343 are handled for consistency. */
4346 {
4351 }
4356 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4357 for neither. In real maths, we cannot assume open ended ranges are
4358 the same. But, this is computer arithmetic, where numbers are finite.
4359 We can therefore make the transformation of any unbounded range with
4360 the value Z, Z being greater than any representable number. This permits
4361 us to treat unbounded ranges as equal. */
4365 {
4386 }
4389 }
4390 \f
4391 /* Helper routine for make_range. Perform one step for it, return
4392 new expression if the loop should continue or NULL_TREE if it should
4393 stop. */
4395 tree
4399 {
4405 {
4407 /* We can only do something if the range is testing for zero. */
4416 /* We can only do something if the range is testing for zero
4417 and if the second operand is an integer constant. Note that
4418 saying something is "in" the range we make is done by
4419 complementing IN_P since it will set in the initial case of
4420 being not equal to zero; "out" is leaving it alone. */
4427 {
4448 }
4450 /* If this is an unsigned comparison, we also know that EXP is
4451 greater than or equal to zero. We base the range tests we make
4452 on that fact, so we record it here so we can parse existing
4453 range tests. We test arg0_type since often the return type
4454 of, e.g. EQ_EXPR, is boolean. */
4456 {
4460 NULL_TREE))
4465 /* If the high bound is missing, but we have a nonzero low
4466 bound, reverse the range so it goes from zero to the low bound
4467 minus 1. */
4469 {
4474 }
4475 }
4483 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4484 low and high are non-NULL, then normalize will DTRT. */
4487 {
4492 }
4494 /* (-x) IN [a,b] -> x in [-b, -a] */
4506 /* ~ X -> -X - 1 */
4515 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4516 move a constant to the other side. */
4521 /* If EXP is signed, any overflow in the computation is undefined,
4522 so we don't worry about it so long as our computations on
4523 the bounds don't overflow. For unsigned, overflow is defined
4524 and this is exactly the right thing. */
4536 normalize:
4537 /* Check for an unsigned range which has wrapped around the maximum
4538 value thus making n_high < n_low, and normalize it. */
4540 {
4546 /* If the range is of the form +/- [ x+1, x ], we won't
4547 be able to normalize it. But then, it represents the
4548 whole range or the empty set, so make it
4549 +/- [ -, - ]. */
4553 else
4555 }
4556 else
4564 CASE_CONVERT:
4582 /* If we're converting arg0 from an unsigned type, to exp,
4583 a signed type, we will be doing the comparison as unsigned.
4584 The tests above have already verified that LOW and HIGH
4585 are both positive.
4587 So we have to ensure that we will handle large unsigned
4588 values the same way that the current signed bounds treat
4589 negative values. */
4592 {
4593 tree high_positive;
4594 tree equiv_type;
4595 /* For fixed-point modes, we need to pass the saturating flag
4596 as the 2nd parameter. */
4598 equiv_type
4601 else
4602 equiv_type
4605 /* A range without an upper bound is, naturally, unbounded.
4606 Since convert would have cropped a very large value, use
4607 the max value for the destination type. */
4608 high_positive
4615 high_positive),
4618 /* If the low bound is specified, "and" the range with the
4619 range for which the original unsigned value will be
4620 positive. */
4622 {
4625 integer_zero_node),
4626 high_positive))
4630 }
4631 else
4632 {
4633 /* Otherwise, "or" the range with the range of the input
4634 that will be interpreted as negative. */
4637 integer_zero_node),
4638 high_positive))
4642 }
4643 }
4652 }
4653 }
4655 /* Given EXP, a logical expression, set the range it is testing into
4656 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4657 actually being tested. *PLOW and *PHIGH will be made of the same
4658 type as the returned expression. If EXP is not a comparison, we
4659 will most likely not be returning a useful value and range. Set
4660 *STRICT_OVERFLOW_P to true if the return value is only valid
4661 because signed overflow is undefined; otherwise, do not change
4662 *STRICT_OVERFLOW_P. */
4664 tree
4667 {
4675 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4676 and see if we can refine the range. Some of the cases below may not
4677 happen, but it doesn't seem worth worrying about this. We "continue"
4678 the outer loop when we've changed something; otherwise we "break"
4679 the switch, which will "break" the while. */
4685 {
4691 {
4699 }
4708 }
4710 /* If EXP is a constant, we can evaluate whether this is true or false. */
4712 {
4719 }
4723 }
4725 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4726 a bitwise check i.e. when
4727 LOW == 0xXX...X00...0
4728 HIGH == 0xXX...X11...1
4729 Return corresponding mask in MASK and stem in VALUE. */
4731 static bool
4734 {
4757 }
4758 \f
4759 /* Helper routine for build_range_check and match.pd. Return the type to
4760 perform the check or NULL if it shouldn't be optimized. */
4762 tree
4764 {
4765 /* First make sure that arithmetics in this type is valid, then make sure
4766 that it wraps around. */
4772 {
4775 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4776 for the type in question, as we rely on this here. */
4786 else
4788 }
4790 }
4792 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4793 type, TYPE, return an expression to test if EXP is in (or out of, depending
4794 on IN_P) the range. Return 0 if the test couldn't be created. */
4796 tree
4799 {
4802 /* Disable this optimization for function pointer expressions
4803 on targets that require function pointer canonicalization. */
4810 {
4816 }
4838 value);
4841 {
4843 {
4847 }
4849 }
4851 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4853 {
4857 {
4859 {
4862 etype
4864 else
4867 }
4870 }
4871 }
4873 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4874 This requires wrap-around arithmetics for the type of the expression. */
4894 }
4895 \f
4896 /* Return the predecessor of VAL in its type, handling the infinite case. */
4898 static tree
4900 {
4906 else
4909 }
4911 /* Return the successor of VAL in its type, handling the infinite case. */
4913 static tree
4915 {
4921 else
4924 }
4926 /* Given two ranges, see if we can merge them into one. Return 1 if we
4927 can, 0 if we can't. Set the output range into the specified parameters. */
4929 bool
4932 {
4936 tree tem;
4946 /* Make range 0 be the range that starts first, or ends last if they
4947 start at the same value. Swap them if it isn't. */
4950 || (lowequal
4953 {
4957 }
4959 /* Now flag two cases, whether the ranges are disjoint or whether the
4960 second range is totally subsumed in the first. Note that the tests
4961 below are simplified by the ones above. */
4967 /* We now have four cases, depending on whether we are including or
4968 excluding the two ranges. */
4970 {
4971 /* If they don't overlap, the result is false. If the second range
4972 is a subset it is the result. Otherwise, the range is from the start
4973 of the second to the end of the first. */
4978 else
4980 }
4983 {
4984 /* If they don't overlap, the result is the first range. If they are
4985 equal, the result is false. If the second range is a subset of the
4986 first, and the ranges begin at the same place, we go from just after
4987 the end of the second range to the end of the first. If the second
4988 range is not a subset of the first, or if it is a subset and both
4989 ranges end at the same place, the range starts at the start of the
4990 first range and ends just before the second range.
4991 Otherwise, we can't describe this as a single range. */
4997 {
5002 {
5003 /* We are in the weird situation where high0 > high1 but
5004 high1 has no successor. Punt. */
5006 }
5007 }
5009 {
5014 {
5015 /* low0 < low1 but low1 has no predecessor. Punt. */
5017 }
5018 }
5019 else
5021 }
5024 {
5025 /* If they don't overlap, the result is the second range. If the second
5026 is a subset of the first, the result is false. Otherwise,
5027 the range starts just after the first range and ends at the
5028 end of the second. */
5033 else
5034 {
5039 {
5040 /* high1 > high0 but high0 has no successor. Punt. */
5042 }
5043 }
5044 }
5046 else
5047 {
5048 /* The case where we are excluding both ranges. Here the complex case
5049 is if they don't overlap. In that case, the only time we have a
5050 range is if they are adjacent. If the second is a subset of the
5051 first, the result is the first. Otherwise, the range to exclude
5052 starts at the beginning of the first range and ends at the end of the
5053 second. */
5055 {
5060 else
5061 {
5062 /* Canonicalize - [min, x] into - [-, x]. */
5065 {
5070 /* FALLTHROUGH */
5083 }
5085 /* Canonicalize - [x, max] into - [x, -]. */
5088 {
5093 /* FALLTHROUGH */
5109 }
5111 /* The ranges might be also adjacent between the maximum and
5112 minimum values of the given type. For
5113 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5114 return + [x + 1, y - 1]. */
5116 {
5123 }
5124 else
5126 }
5127 }
5130 else
5132 }
5136 }
5137 \f
5139 /* Subroutine of fold, looking inside expressions of the form
5140 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5141 of the COND_EXPR. This function is being used also to optimize
5142 A op B ? C : A, by reversing the comparison first.
5144 Return a folded expression whose code is not a COND_EXPR
5145 anymore, or NULL_TREE if no folding opportunity is found. */
5147 static tree
5150 {
5155 tree tem;
5160 /* If we have A op 0 ? A : -A, consider applying the following
5161 transformations:
5163 A == 0? A : -A same as -A
5164 A != 0? A : -A same as A
5165 A >= 0? A : -A same as abs (A)
5166 A > 0? A : -A same as abs (A)
5167 A <= 0? A : -A same as -abs (A)
5168 A < 0? A : -A same as -abs (A)
5170 None of these transformations work for modes with signed
5171 zeros. If A is +/-0, the first two transformations will
5172 change the sign of the result (from +0 to -0, or vice
5173 versa). The last four will fix the sign of the result,
5174 even though the original expressions could be positive or
5175 negative, depending on the sign of A.
5177 Note that all these transformations are correct if A is
5178 NaN, since the two alternatives (A and -A) are also NaNs. */
5185 /* In the case that A is of the form X-Y, '-A' (arg2) may
5186 have already been folded to Y-X, check for that. */
5194 {
5206 /* Fall through. */
5217 /* FALLTHRU */
5227 }
5229 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5230 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5231 both transformations are correct when A is NaN: A != 0
5232 is then true, and A == 0 is false. */
5236 {
5241 }
5243 /* Try some transformations of A op B ? A : B.
5245 A == B? A : B same as B
5246 A != B? A : B same as A
5247 A >= B? A : B same as max (A, B)
5248 A > B? A : B same as max (B, A)
5249 A <= B? A : B same as min (A, B)
5250 A < B? A : B same as min (B, A)
5252 As above, these transformations don't work in the presence
5253 of signed zeros. For example, if A and B are zeros of
5254 opposite sign, the first two transformations will change
5255 the sign of the result. In the last four, the original
5256 expressions give different results for (A=+0, B=-0) and
5257 (A=-0, B=+0), but the transformed expressions do not.
5259 The first two transformations are correct if either A or B
5260 is a NaN. In the first transformation, the condition will
5261 be false, and B will indeed be chosen. In the case of the
5262 second transformation, the condition A != B will be true,
5263 and A will be chosen.
5265 The conversions to max() and min() are not correct if B is
5266 a number and A is not. The conditions in the original
5267 expressions will be false, so all four give B. The min()
5268 and max() versions would give a NaN instead. */
5271 /* Avoid these transformations if the COND_EXPR may be used
5272 as an lvalue in the C++ front-end. PR c++/19199. */
5273 && (in_gimple_form
5279 {
5285 {
5294 /* In C++ a ?: expression can be an lvalue, so put the
5295 operand which will be used if they are equal first
5296 so that we can convert this back to the
5297 corresponding COND_EXPR. */
5299 {
5307 }
5314 {
5322 }
5335 }
5336 }
5339 }
5342 \f
5343 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5344 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5345 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5346 false) >= 2)
5347 #endif
5349 /* EXP is some logical combination of boolean tests. See if we can
5350 merge it into some range test. Return the new tree if so. */
5352 static tree
5355 {
5371 /* If this is an OR operation, invert both sides; we will invert
5372 again at the end. */
5376 /* If both expressions are the same, if we can merge the ranges, and we
5377 can build the range test, return it or it inverted. If one of the
5378 ranges is always true or always false, consider it to be the same
5379 expression as the other. */
5387 {
5391 }
5393 /* On machines where the branch cost is expensive, if this is a
5394 short-circuited branch and the underlying object on both sides
5395 is the same, make a non-short-circuit operation. */
5397 && !flag_sanitize_coverage
5402 {
5403 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5404 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5405 which cases we can't do this. */
5413 {
5422 {
5425 WARN_STRICT_OVERFLOW_COMPARISON);
5429 }
5430 }
5431 }
5434 }
5435 \f
5436 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5437 bit value. Arrange things so the extra bits will be set to zero if and
5438 only if C is signed-extended to its full width. If MASK is nonzero,
5439 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5441 static tree
5443 {
5446 tree temp;
5451 /* We work by getting just the sign bit into the low-order bit, then
5452 into the high-order bit, then sign-extend. We then XOR that value
5453 with C. */
5456 /* We must use a signed type in order to get an arithmetic right shift.
5457 However, we must also avoid introducing accidental overflows, so that
5458 a subsequent call to integer_zerop will work. Hence we must
5459 do the type conversion here. At this point, the constant is either
5460 zero or one, and the conversion to a signed type can never overflow.
5461 We could get an overflow if this conversion is done anywhere else. */
5470 /* If necessary, convert the type back to match the type of C. */
5475 }
5476 \f
5477 /* For an expression that has the form
5478 (A && B) || ~B
5479 or
5480 (A || B) && ~B,
5481 we can drop one of the inner expressions and simplify to
5482 A || ~B
5483 or
5484 A && ~B
5485 LOC is the location of the resulting expression. OP is the inner
5486 logical operation; the left-hand side in the examples above, while CMPOP
5487 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5488 removing a condition that guards another, as in
5489 (A != NULL && A->...) || A == NULL
5490 which we must not transform. If RHS_ONLY is true, only eliminate the
5491 right-most operand of the inner logical operation. */
5493 static tree
5496 {
5514 {
5517 {
5520 }
5521 }
5523 {
5526 {
5529 }
5530 }
5545 }
5547 /* Find ways of folding logical expressions of LHS and RHS:
5548 Try to merge two comparisons to the same innermost item.
5549 Look for range tests like "ch >= '0' && ch <= '9'".
5550 Look for combinations of simple terms on machines with expensive branches
5551 and evaluate the RHS unconditionally.
5553 For example, if we have p->a == 2 && p->b == 4 and we can make an
5554 object large enough to span both A and B, we can do this with a comparison
5555 against the object ANDed with the a mask.
5557 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5558 operations to do this with one comparison.
5560 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5561 function and the one above.
5563 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5564 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5566 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5567 two operands.
5569 We return the simplified tree or 0 if no optimization is possible. */
5571 static tree
5574 {
5575 /* If this is the "or" of two comparisons, we can do something if
5576 the comparisons are NE_EXPR. If this is the "and", we can do something
5577 if the comparisons are EQ_EXPR. I.e.,
5578 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5580 WANTED_CODE is this operation code. For single bit fields, we can
5581 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5582 comparison for one-bit fields. */
5603 /* Start by getting the comparison codes. Fail if anything is volatile.
5604 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5605 it were surrounded with a NE_EXPR. */
5614 {
5618 }
5621 {
5625 }
5636 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5639 {
5642 {
5647 }
5650 {
5656 }
5657 }
5662 /* If the RHS can be evaluated unconditionally and its operands are
5663 simple, it wins to evaluate the RHS unconditionally on machines
5664 with expensive branches. In this case, this isn't a comparison
5665 that can be merged. */
5672 {
5673 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5684 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5694 }
5696 /* See if the comparisons can be merged. Then get all the parameters for
5697 each side. */
5722 /* It must be true that the inner operation on the lhs of each
5723 comparison must be the same if we are to be able to do anything.
5724 Then see if we have constants. If not, the same must be true for
5725 the rhs's. */
5734 {
5737 }
5742 else
5745 /* If either comparison code is not correct for our logical operation,
5746 fail. However, we can convert a one-bit comparison against zero into
5747 the opposite comparison against that bit being set in the field. */
5751 {
5753 {
5754 /* Make the left operand unsigned, since we are only interested
5755 in the value of one bit. Otherwise we are doing the wrong
5756 thing below. */
5759 }
5760 else
5762 }
5764 /* This is analogous to the code for l_const above. */
5766 {
5768 {
5771 }
5772 else
5774 }
5776 /* See if we can find a mode that contains both fields being compared on
5777 the left. If we can't, fail. Otherwise, update all constants and masks
5778 to be relative to a field of that size. */
5792 {
5795 }
5803 {
5810 {
5814 }
5815 }
5817 {
5824 {
5828 }
5829 }
5831 /* If the right sides are not constant, do the same for it. Also,
5832 disallow this optimization if a size or signedness mismatch occurs
5833 between the left and right sides. */
5835 {
5838 /* Make sure the two fields on the right
5839 correspond to the left without being swapped. */
5856 {
5859 }
5868 /* Make a mask that corresponds to both fields being compared.
5869 Do this for both items being compared. If the operands are the
5870 same size and the bits being compared are in the same position
5871 then we can do this by masking both and comparing the masked
5872 results. */
5876 {
5890 }
5892 /* There is still another way we can do something: If both pairs of
5893 fields being compared are adjacent, we may be able to make a wider
5894 field containing them both.
5896 Note that we still must mask the lhs/rhs expressions. Furthermore,
5897 the mask must be shifted to account for the shift done by
5898 make_bit_field_ref. */
5903 {
5904 tree type;
5920 /* Convert to the smaller type before masking out unwanted bits. */
5923 {
5925 {
5929 }
5931 {
5935 }
5936 }
5945 }
5948 }
5950 /* Handle the case of comparisons with constants. If there is something in
5951 common between the masks, those bits of the constants must be the same.
5952 If not, the condition is always false. Test for this to avoid generating
5953 incorrect code below. */
5958 {
5960 {
5963 }
5964 else
5965 {
5968 }
5969 }
5971 /* Construct the expression we will return. First get the component
5972 reference we will make. Unless the mask is all ones the width of
5973 that field, perform the mask operation. Then compare with the
5974 merged constant. */
5985 }
5986 \f
5987 /* T is an integer expression that is being multiplied, divided, or taken a
5988 modulus (CODE says which and what kind of divide or modulus) by a
5989 constant C. See if we can eliminate that operation by folding it with
5990 other operations already in T. WIDE_TYPE, if non-null, is a type that
5991 should be used for the computation if wider than our type.
5993 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5994 (X * 2) + (Y * 4). We must, however, be assured that either the original
5995 expression would not overflow or that overflow is undefined for the type
5996 in the language in question.
5998 If we return a non-null expression, it is an equivalent form of the
5999 original computation, but need not be in the original type.
6001 We set *STRICT_OVERFLOW_P to true if the return values depends on
6002 signed overflow being undefined. Otherwise we do not change
6003 *STRICT_OVERFLOW_P. */
6005 static tree
6008 {
6009 /* To avoid exponential search depth, refuse to allow recursion past
6010 three levels. Beyond that (1) it's highly unlikely that we'll find
6011 something interesting and (2) we've probably processed it before
6012 when we built the inner expression. */
6015 tree ret;
6020 depth++;
6022 depth--;
6025 }
6027 static tree
6030 {
6042 /* Don't deal with constants of zero here; they confuse the code below. */
6052 /* Note that we need not handle conditional operations here since fold
6053 already handles those cases. So just do arithmetic here. */
6055 {
6057 /* For a constant, we can always simplify if we are a multiply
6058 or (for divide and modulus) if it is a multiple of our constant. */
6061 {
6064 /* If the multiplication overflowed, we lost information on it.
6065 See PR68142 and PR69845. */
6069 }
6073 /* If op0 is an expression ... */
6079 /* ... and has wrapping overflow, and its type is smaller
6080 than ctype, then we cannot pass through as widening. */
6085 /* ... or this is a truncation (t is narrower than op0),
6086 then we cannot pass through this narrowing. */
6089 /* ... or signedness changes for division or modulus,
6090 then we cannot pass through this conversion. */
6094 /* ... or has undefined overflow while the converted to
6095 type has not, we cannot do the operation in the inner type
6096 as that would introduce undefined overflow. */
6102 /* Pass the constant down and see if we can make a simplification. If
6103 we can, replace this expression with the inner simplification for
6104 possible later conversion to our or some other type. */
6109 code == MULT_EXPR
6111 strict_overflow_p))))
6116 /* If widening the type changes it from signed to unsigned, then we
6117 must avoid building ABS_EXPR itself as unsigned. */
6119 {
6123 {
6126 }
6128 }
6129 /* If the constant is negative, we cannot simplify this. */
6132 /* FALLTHROUGH */
6134 /* For division and modulus, type can't be unsigned, as e.g.
6135 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6136 For signed types, even with wrapping overflow, this is fine. */
6145 /* If widening the type changes the signedness, then we can't perform
6146 this optimization as that changes the result. */
6150 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6156 {
6163 }
6167 /* If the second operand is constant, this is a multiplication
6168 or floor division, by a power of two, so we can treat it that
6169 way unless the multiplier or divisor overflows. Signed
6170 left-shift overflow is implementation-defined rather than
6171 undefined in C90, so do not convert signed left shift into
6172 multiplication. */
6175 /* const_binop may not detect overflow correctly,
6176 so check for it explicitly here. */
6180 size_one_node,
6181 op1)))
6185 ctype,
6187 t1),
6192 /* See if we can eliminate the operation on both sides. If we can, we
6193 can return a new PLUS or MINUS. If we can't, the only remaining
6194 cases where we can do anything are if the second operand is a
6195 constant. */
6202 /* If not multiplication, we can only do this if both operands
6203 are divisible by c. */
6206 {
6211 }
6213 /* If this was a subtraction, negate OP1 and set it to be an addition.
6214 This simplifies the logic below. */
6216 {
6218 /* If OP1 was not easily negatable, the constant may be OP0. */
6220 {
6223 }
6224 }
6229 /* If either OP1 or C are negative, this optimization is not safe for
6230 some of the division and remainder types while for others we need
6231 to change the code. */
6233 {
6241 }
6243 /* If it's a multiply or a division/modulus operation of a multiple
6244 of our constant, do the operation and verify it doesn't overflow. */
6247 {
6250 /* We allow the constant to overflow with wrapping semantics. */
6254 }
6255 else
6258 /* If we have an unsigned type, we cannot widen the operation since it
6259 will change the result if the original computation overflowed. */
6263 /* The last case is if we are a multiply. In that case, we can
6264 apply the distributive law to commute the multiply and addition
6265 if the multiplication of the constants doesn't overflow
6266 and overflow is defined. With undefined overflow
6267 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6273 op1);
6278 /* We have a special case here if we are doing something like
6279 (C * 8) % 4 since we know that's zero. */
6282 /* If the multiplication can overflow we cannot optimize this. */
6286 {
6289 }
6291 /* ... fall through ... */
6295 /* If we can extract our operation from the LHS, do so and return a
6296 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6297 do something only if the second operand is a constant. */
6313 /* If these are the same operation types, we can associate them
6314 assuming no overflow. */
6316 {
6331 }
6333 /* If these operations "cancel" each other, we have the main
6334 optimizations of this pass, which occur when either constant is a
6335 multiple of the other, in which case we replace this with either an
6336 operation or CODE or TCODE.
6338 If we have an unsigned type, we cannot do this since it will change
6339 the result if the original computation overflowed. */
6346 {
6348 {
6355 }
6357 {
6364 }
6365 }
6370 }
6373 }
6374 \f
6375 /* Return a node which has the indicated constant VALUE (either 0 or
6376 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6377 and is of the indicated TYPE. */
6379 tree
6381 {
6390 else
6392 }
6395 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6396 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6397 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6398 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6399 COND is the first argument to CODE; otherwise (as in the example
6400 given here), it is the second argument. TYPE is the type of the
6401 original expression. Return NULL_TREE if no simplification is
6402 possible. */
6404 static tree
6409 {
6419 {
6423 /* If this operand throws an expression, then it does not make
6424 sense to try to perform a logical or arithmetic operation
6425 involving it. */
6430 }
6433 {
6438 }
6439 else
6440 /* Detect the case of mixing vector and scalar types - bail out. */
6446 /* This transformation is only worthwhile if we don't have to wrap ARG
6447 in a SAVE_EXPR and the operation can be simplified without recursing
6448 on at least one of the branches once its pushed inside the COND_EXPR. */
6457 {
6461 else
6463 }
6465 {
6469 else
6471 }
6473 /* Check that we have simplified at least one of the branches. */
6478 }
6480 \f
6481 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6483 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6484 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6485 ADDEND is the same as X.
6487 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6488 and finite. The problematic cases are when X is zero, and its mode
6489 has signed zeros. In the case of rounding towards -infinity,
6490 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6491 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6493 bool
6495 {
6499 /* Don't allow the fold with -fsignaling-nans. */
6503 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6507 /* In a vector or complex, we would need to check the sign of all zeros. */
6511 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6515 /* The mode has signed zeros, and we have to honor their sign.
6516 In this situation, there is only one case we can return true for.
6517 X - 0 is the same as X unless rounding towards -infinity is
6518 supported. */
6520 }
6522 /* Subroutine of match.pd that optimizes comparisons of a division by
6523 a nonzero integer constant against an integer constant, i.e.
6524 X/C1 op C2.
6526 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6527 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6529 enum tree_code
6532 {
6537 /* We have to do this the hard way to detect unsigned overflow.
6538 prod = int_const_binop (MULT_EXPR, c1, c2); */
6544 {
6548 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6551 }
6553 {
6556 {
6575 }
6576 }
6577 else
6578 {
6579 /* A negative divisor reverses the relational operators. */
6584 {
6603 }
6604 }
6617 }
6620 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6621 equality/inequality test, then return a simplified form of the test
6622 using a sign testing. Otherwise return NULL. TYPE is the desired
6623 result type. */
6625 static tree
6628 tree result_type)
6629 {
6630 /* If this is testing a single bit, we can optimize the test. */
6634 {
6635 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6636 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6640 /* This is only a win if casting to a signed type is cheap,
6641 i.e. when arg00's type is not a partial mode. */
6643 {
6646 result_type,
6649 }
6650 }
6653 }
6655 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6656 equality/inequality test, then return a simplified form of
6657 the test using shifts and logical operations. Otherwise return
6658 NULL. TYPE is the desired result type. */
6660 tree
6663 {
6664 /* If this is testing a single bit, we can optimize the test. */
6668 {
6677 /* First, see if we can fold the single bit test into a sign-bit
6678 test. */
6680 result_type);
6684 /* Otherwise we have (A & C) != 0 where C is a single bit,
6685 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6686 Similarly for (A & C) == 0. */
6688 /* If INNER is a right shift of a constant and it plus BITNUM does
6689 not overflow, adjust BITNUM and INNER. */
6695 {
6698 }
6700 /* If we are going to be able to omit the AND below, we must do our
6701 operations as unsigned. If we must use the AND, we have a choice.
6702 Normally unsigned is faster, but for some machines signed is. */
6720 /* Put the AND last so it can combine with more things. */
6723 /* Make sure to return the proper type. */
6727 }
6729 }
6731 /* Test whether it is preferable two swap two operands, ARG0 and
6732 ARG1, for example because ARG0 is an integer constant and ARG1
6733 isn't. */
6735 bool
6737 {
6751 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6752 for commutative and comparison operators. Ensuring a canonical
6753 form allows the optimizers to find additional redundancies without
6754 having to explicitly check for both orderings. */
6760 /* Put SSA_NAMEs last. */
6766 /* Put variables last. */
6773 }
6776 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6777 means A >= Y && A != MAX, but in this case we know that
6778 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6780 static tree
6782 {
6789 else
6798 {
6801 }
6803 {
6806 }
6807 else
6814 {
6815 /* Convert the pointer types into integer before taking the difference. */
6819 }
6820 else
6827 }
6829 /* Fold a sum or difference of at least one multiplication.
6830 Returns the folded tree or NULL if no simplification could be made. */
6832 static tree
6835 {
6839 /* (A * C) +- (B * C) -> (A+-B) * C.
6840 (A * C) +- A -> A * (C+-1).
6841 We are most concerned about the case where C is a constant,
6842 but other combinations show up during loop reduction. Since
6843 it is not difficult, try all four possibilities. */
6846 {
6849 }
6851 {
6854 }
6855 else
6856 {
6857 /* We cannot generate constant 1 for fract. */
6862 }
6864 {
6867 }
6869 {
6871 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6872 the purpose of this canonicalization. */
6876 {
6879 }
6880 else
6882 }
6883 else
6884 {
6885 /* We cannot generate constant 1 for fract. */
6890 }
6893 /* Prefer factoring a common non-constant. */
6903 /* No identical multiplicands; see if we can find a common
6904 power-of-two factor in non-power-of-two multiplies. This
6905 can help in multi-dimensional array access. */
6908 {
6911 tree maybe_same;
6915 /* Move min of absolute values to int11. */
6917 {
6922 }
6923 else
6927 /* The remainder should not be a constant, otherwise we
6928 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6929 increased the number of multiplications necessary. */
6931 {
6939 }
6940 }
6947 /* We are neither factoring zero nor minus one. */
6955 /* Same may be zero and thus the operation 'code' may overflow. Likewise
6956 same may be minus one and thus the multiplication may overflow. Perform
6957 the operations in an unsigned type. */
6962 /* If the sum evaluated to a constant that is not -INF the multiplication
6963 cannot overflow. */
6972 }
6974 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6975 specified by EXPR into the buffer PTR of length LEN bytes.
6976 Return the number of bytes placed in the buffer, or zero
6977 upon failure. */
6979 static int
6981 {
6995 {
6997 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
6998 number of bytes. */
7002 {
7009 else
7011 }
7012 else
7017 }
7019 }
7022 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7023 specified by EXPR into the buffer PTR of length LEN bytes.
7024 Return the number of bytes placed in the buffer, or zero
7025 upon failure. */
7027 static int
7029 {
7033 FIXED_VALUE_TYPE value;
7049 }
7052 /* Subroutine of native_encode_expr. Encode the REAL_CST
7053 specified by EXPR into the buffer PTR of length LEN bytes.
7054 Return the number of bytes placed in the buffer, or zero
7055 upon failure. */
7057 static int
7059 {
7065 /* There are always 32 bits in each long, no matter the size of
7066 the hosts long. We handle floating point representations with
7067 up to 192 bits. */
7081 {
7086 {
7093 else
7095 }
7096 else
7097 {
7100 {
7101 /* Reverse bytes within each long, or within the entire float
7102 if it's smaller than a long (for HFmode). */
7105 }
7106 }
7111 }
7113 }
7115 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7116 specified by EXPR into the buffer PTR of length LEN bytes.
7117 Return the number of bytes placed in the buffer, or zero
7118 upon failure. */
7120 static int
7122 {
7124 tree part;
7139 }
7142 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7143 specified by EXPR into the buffer PTR of length LEN bytes.
7144 Return the number of bytes placed in the buffer, or zero
7145 upon failure. */
7147 static int
7149 {
7159 {
7161 {
7164 }
7175 }
7177 }
7180 /* Subroutine of native_encode_expr. Encode the STRING_CST
7181 specified by EXPR into the buffer PTR of length LEN bytes.
7182 Return the number of bytes placed in the buffer, or zero
7183 upon failure. */
7185 static int
7187 {
7198 {
7201 {
7204 }
7207 }
7208 else
7211 }
7214 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7215 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7216 buffer PTR of length LEN bytes. If OFF is not -1 then start
7217 the encoding at byte offset OFF and encode at most LEN bytes.
7218 Return the number of bytes placed in the buffer, or zero upon failure. */
7220 int
7222 {
7223 /* We don't support starting at negative offset and -1 is special. */
7228 {
7249 }
7250 }
7253 /* Subroutine of native_interpret_expr. Interpret the contents of
7254 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7255 If the buffer cannot be interpreted, return NULL_TREE. */
7257 static tree
7259 {
7269 }
7272 /* Subroutine of native_interpret_expr. Interpret the contents of
7273 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7274 If the buffer cannot be interpreted, return NULL_TREE. */
7276 static tree
7278 {
7281 double_int result;
7282 FIXED_VALUE_TYPE fixed_value;
7292 }
7295 /* Subroutine of native_interpret_expr. Interpret the contents of
7296 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7297 If the buffer cannot be interpreted, return NULL_TREE. */
7299 static tree
7301 {
7305 /* There are always 32 bits in each long, no matter the size of
7306 the hosts long. We handle floating point representations with
7307 up to 192 bits. */
7308 REAL_VALUE_TYPE r;
7318 {
7319 /* Both OFFSET and BYTE index within a long;
7320 bitpos indexes the whole float. */
7323 {
7330 else
7332 }
7333 else
7334 {
7337 {
7338 /* Reverse bytes within each long, or within the entire float
7339 if it's smaller than a long (for HFmode). */
7342 }
7343 }
7347 }
7351 }
7354 /* Subroutine of native_interpret_expr. Interpret the contents of
7355 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7356 If the buffer cannot be interpreted, return NULL_TREE. */
7358 static tree
7360 {
7375 }
7378 /* Subroutine of native_interpret_expr. Interpret the contents of
7379 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7380 If the buffer cannot be interpreted, return NULL_TREE. */
7382 static tree
7384 {
7397 {
7402 }
7404 }
7407 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7408 the buffer PTR of length LEN as a constant of type TYPE. For
7409 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7410 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7411 return NULL_TREE. */
7413 tree
7415 {
7417 {
7439 }
7440 }
7442 /* Returns true if we can interpret the contents of a native encoding
7443 as TYPE. */
7445 static bool
7447 {
7449 {
7462 }
7463 }
7465 /* Return true iff a constant of type TYPE is accepted by
7466 native_encode_expr. */
7468 bool
7470 {
7472 {
7482 }
7483 }
7485 /* Return true iff a STRING_CST S is accepted by
7486 native_encode_expr. */
7488 bool
7490 {
7493 /* Wide-char strings are encoded in target byte-order so native
7494 encoding them is trivial. */
7501 }
7503 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7504 TYPE at compile-time. If we're unable to perform the conversion
7505 return NULL_TREE. */
7507 static tree
7509 {
7510 /* We support up to 512-bit values (for V8DFmode). */
7514 /* Check that the host and target are sane. */
7523 }
7525 /* Build an expression for the address of T. Folds away INDIRECT_REF
7526 to avoid confusing the gimplify process. */
7528 tree
7530 {
7531 /* The size of the object is not relevant when talking about its address. */
7536 {
7541 }
7551 {
7556 }
7557 else
7561 }
7563 /* Build an expression for the address of T. */
7565 tree
7567 {
7571 }
7573 /* Fold a unary expression of code CODE and type TYPE with operand
7574 OP0. Return the folded expression if folding is successful.
7575 Otherwise, return NULL_TREE. */
7577 tree
7579 {
7580 tree tem;
7581 tree arg0;
7589 {
7592 {
7593 /* Don't use STRIP_NOPS, because signedness of argument type
7594 matters. */
7596 }
7597 else
7598 {
7599 /* Strip any conversions that don't change the mode. This
7600 is safe for every expression, except for a comparison
7601 expression because its signedness is derived from its
7602 operands.
7604 Note that this is done as an internal manipulation within
7605 the constant folder, in order to find the simplest
7606 representation of the arguments so that their form can be
7607 studied. In any cases, the appropriate type conversions
7608 should be put back in the tree that will get out of the
7609 constant folder. */
7611 }
7614 {
7617 {
7621 }
7622 }
7623 }
7630 {
7637 {
7651 /* If this was a conversion, and all we did was to move into
7652 inside the COND_EXPR, bring it back out. But leave it if
7653 it is a conversion from integer to integer and the
7654 result precision is no wider than a word since such a
7655 conversion is cheap and may be optimized away by combine,
7656 while it couldn't if it were outside the COND_EXPR. Then return
7657 so we don't get into an infinite recursion loop taking the
7658 conversion out and then back in. */
7670 && (INTEGRAL_TYPE_P
7683 }
7684 }
7687 {
7693 CASE_CONVERT:
7697 {
7698 /* If we have (type) (a CMP b) and type is an integral type, return
7699 new expression involving the new type. Canonicalize
7700 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7701 non-integral type.
7702 Do not fold the result as that would not simplify further, also
7703 folding again results in recursions. */
7713 }
7715 /* Handle (T *)&A.B.C for A being of type T and B and C
7716 living at offset zero. This occurs frequently in
7717 C++ upcasting and then accessing the base. */
7721 {
7723 tree offset;
7724 machine_mode mode;
7726 tree base
7730 /* If the reference was to a (constant) zero offset, we can use
7731 the address of the base if it has the same base type
7732 as the result type and the pointer type is unqualified. */
7739 }
7743 /* Detect assigning a bitfield. */
7745 && DECL_BIT_FIELD
7747 {
7748 /* Don't leave an assignment inside a conversion
7749 unless assigning a bitfield. */
7751 /* First do the assignment, then return converted constant. */
7756 }
7758 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7759 constants (if x has signed type, the sign bit cannot be set
7760 in c). This folds extension into the BIT_AND_EXPR.
7761 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7762 very likely don't have maximal range for their precision and this
7763 transformation effectively doesn't preserve non-maximal ranges. */
7767 {
7778 <= HOST_BITS_PER_WIDE_INT
7780 {
7784 cst &= HOST_WIDE_INT_M1U
7788 && !flag_syntax_only
7791 {
7795 }
7796 }
7798 {
7803 }
7804 }
7806 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7807 cast (T1)X will fold away. We assume that this happens when X itself
7808 is a cast. */
7812 {
7816 return fold_build_pointer_plus_loc
7818 }
7820 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7821 of the same precision, and X is an integer type not narrower than
7822 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7828 {
7834 }
7836 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7837 type of X and Y (integer types only). */
7842 {
7843 /* Be careful not to introduce new overflows. */
7844 tree mult_type;
7847 else
7851 {
7858 }
7859 }
7865 {
7872 }
7883 /* Convert fabs((double)float) into (double)fabsf(float). */
7886 {
7892 targ0));
7893 }
7897 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7916 /* Note that the operand of this must be an int
7917 and its values must be 0 or 1.
7918 ("true" is a fixed value perhaps depending on the language,
7919 but we don't handle values other than 1 correctly yet.) */
7926 /* Fold *&X to X if X is an lvalue. */
7928 {
7935 }
7941 }
7944 /* If the operation was a conversion do _not_ mark a resulting constant
7945 with TREE_OVERFLOW if the original constant was not. These conversions
7946 have implementation defined behavior and retaining the TREE_OVERFLOW
7947 flag here would confuse later passes such as VRP. */
7948 tree
7951 {
7960 }
7962 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7963 operands OP0 and OP1. LOC is the location of the resulting expression.
7964 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7965 Return the folded expression if folding is successful. Otherwise,
7966 return NULL_TREE. */
7967 static tree
7970 {
7971 tree tem;
7973 /* We only do these simplifications if we are optimizing. */
7977 /* Check for things like (A || B) && (A || C). We can convert this
7978 to A || (B && C). Note that either operator can be any of the four
7979 truth and/or operations and the transformation will still be
7980 valid. Also note that we only care about order for the
7981 ANDIF and ORIF operators. If B contains side effects, this
7982 might change the truth-value of A. */
7989 {
8009 /* This case if tricky because we must either have commutative
8010 operators or else A10 must not have side-effects. */
8016 a01);
8017 }
8019 /* See if we can build a range comparison. */
8025 {
8029 }
8033 {
8037 }
8039 /* Check for the possibility of merging component references. If our
8040 lhs is another similar operation, try to merge its rhs with our
8041 rhs. Then try to merge our lhs and rhs. */
8051 && !flag_sanitize_coverage
8056 {
8063 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8064 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8065 We don't want to pack more than two leafs to a non-IF AND/OR
8066 expression.
8067 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8068 equal to IF-CODE, then we don't want to add right-hand operand.
8069 If the inner right-hand side of left-hand operand has
8070 side-effects, or isn't simple, then we can't add to it,
8071 as otherwise we might destroy if-sequence. */
8074 /* Needed for sequence points to handle trappings, and
8075 side-effects. */
8077 {
8079 arg1);
8081 tem);
8082 }
8083 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8084 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8087 /* Needed for sequence points to handle trappings, and
8088 side-effects. */
8090 {
8095 }
8096 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8097 into (A OR B).
8098 For sequence point consistancy, we need to check for trapping,
8099 and side-effects. */
8103 }
8106 }
8108 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8109 by changing CODE to reduce the magnitude of constants involved in
8110 ARG0 of the comparison.
8111 Returns a canonicalized comparison tree if a simplification was
8112 possible, otherwise returns NULL_TREE.
8113 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8114 valid if signed overflow is undefined. */
8116 static tree
8120 {
8125 /* Match A +- CST code arg1. We can change this only if overflow
8126 is undefined. */
8129 /* In principle pointers also have undefined overflow behavior,
8130 but that causes problems elsewhere. */
8137 /* Identify the constant in arg0 and its sign. */
8141 /* Overflowed constants and zero will cause problems. */
8146 /* See if we can reduce the magnitude of the constant in
8147 arg0 by changing the comparison code. */
8148 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8152 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8156 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8160 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8164 else
8168 /* Now build the constant reduced in magnitude. But not if that
8169 would produce one outside of its types range. */
8185 }
8187 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8188 overflow further. Try to decrease the magnitude of constants involved
8189 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8190 and put sole constants at the second argument position.
8191 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8193 static tree
8196 {
8197 tree t;
8202 /* Try canonicalization by simplifying arg0. */
8207 {
8211 }
8213 /* Try canonicalization by simplifying arg1 using the swapped
8214 comparison. */
8222 }
8224 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8225 space. This is used to avoid issuing overflow warnings for
8226 expressions like &p->x which can not wrap. */
8228 static bool
8230 {
8237 wide_int wi_offset;
8243 else
8259 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8260 array. */
8262 {
8263 HOST_WIDE_INT base_size;
8268 }
8271 }
8273 /* Return a positive integer when the symbol DECL is known to have
8274 a nonzero address, zero when it's known not to (e.g., it's a weak
8275 symbol), and a negative integer when the symbol is not yet in the
8276 symbol table and so whether or not its address is zero is unknown.
8277 For function local objects always return positive integer. */
8278 static int
8280 {
8285 /* Function local objects are never NULL. */
8293 }
8295 /* Subroutine of fold_binary. This routine performs all of the
8296 transformations that are common to the equality/inequality
8297 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8298 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8299 fold_binary should call fold_binary. Fold a comparison with
8300 tree code CODE and type TYPE with operands OP0 and OP1. Return
8301 the folded comparison or NULL_TREE. */
8303 static tree
8306 {
8316 /* For comparisons of pointers we can decompose it to a compile time
8317 comparison of the base objects and the offsets into the object.
8318 This requires at least one operand being an ADDR_EXPR or a
8319 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8325 {
8328 machine_mode mode;
8332 /* Get base and offset for the access. Strip ADDR_EXPR for
8333 get_inner_reference, but put it back by stripping INDIRECT_REF
8334 off the base object if possible. indirect_baseN will be true
8335 if baseN is not an address but refers to the object itself. */
8338 {
8339 base0
8345 else
8347 }
8349 {
8353 {
8354 base0
8360 else
8362 }
8365 else
8369 {
8375 {
8378 }
8379 }
8380 }
8384 {
8385 base1
8391 else
8393 }
8395 {
8399 {
8400 base1
8406 else
8408 }
8411 else
8415 {
8421 {
8424 }
8425 }
8426 }
8428 /* If we have equivalent bases we might be able to simplify. */
8432 {
8433 /* We can fold this expression to a constant if the non-constant
8434 offset parts are equal. */
8438 {
8444 "occur when comparing P +- C1 with "
8446 WARN_STRICT_OVERFLOW_CONDITIONAL);
8449 {
8463 }
8464 }
8465 /* We can simplify the comparison to a comparison of the variable
8466 offset parts if the constant offset parts are equal.
8467 Be careful to use signed sizetype here because otherwise we
8468 mess with array offsets in the wrong way. This is possible
8469 because pointer arithmetic is restricted to retain within an
8470 object and overflow on pointer differences is undefined as of
8471 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8473 {
8474 /* By converting to signed sizetype we cover middle-end pointer
8475 arithmetic which operates on unsigned pointer types of size
8476 type size and ARRAY_REF offsets which are properly sign or
8477 zero extended from their type in case it is narrower than
8478 sizetype. */
8481 else
8485 else
8492 "occur when comparing P +- C1 with "
8494 WARN_STRICT_OVERFLOW_COMPARISON);
8497 }
8498 }
8499 /* For equal offsets we can simplify to a comparison of the
8500 base addresses. */
8502 && (indirect_base0
8504 && (indirect_base1
8509 {
8515 }
8516 /* Comparison between an ordinary (non-weak) symbol and a null
8517 pointer can be eliminated since such symbols must have a non
8518 null address. In C, relational expressions between pointers
8519 to objects and null pointers are undefined. The results
8520 below follow the C++ rules with the additional property that
8521 every object pointer compares greater than a null pointer.
8522 */
8525 /* Avoid folding references to struct members at offset 0 to
8526 prevent tests like '&ptr->firstmember == 0' from getting
8527 eliminated. When ptr is null, although the -> expression
8528 is strictly speaking invalid, GCC retains it as a matter
8529 of QoI. See PR c/44555. */
8532 && indirect_base0
8533 /* The caller guarantees that when one of the arguments is
8534 constant (i.e., null in this case) it is second. */
8536 {
8538 {
8549 }
8550 }
8551 }
8553 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8554 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8555 the resulting offset is smaller in absolute value than the
8556 original one and has the same sign. */
8565 {
8570 tree cst;
8572 "occur when combining constants around "
8575 /* Put the constant on the side where it doesn't overflow and is
8576 of lower absolute value and of same sign than before. */
8583 {
8586 variable1,
8590 }
8598 {
8604 variable2);
8605 }
8606 }
8612 /* If we are comparing an expression that just has comparisons
8613 of two integer values, arithmetic expressions of those comparisons,
8614 and constants, we can simplify it. There are only three cases
8615 to check: the two values can either be equal, the first can be
8616 greater, or the second can be greater. Fold the expression for
8617 those three values. Since each value must be 0 or 1, we have
8618 eight possibilities, each of which corresponds to the constant 0
8619 or 1 or one of the six possible comparisons.
8621 This handles common cases like (a > b) == 0 but also handles
8622 expressions like ((x > y) - (y > x)) > 0, which supposedly
8623 occur in macroized code. */
8626 {
8631 /* Don't handle degenerate cases here; they should already
8632 have been handled anyway. */
8641 {
8645 /* We can't just pass T to eval_subst in case cval1 or cval2
8646 was the same as ARG1. */
8648 tree high_result
8652 arg1);
8653 tree equal_result
8657 arg1);
8658 tree low_result
8662 arg1);
8664 /* All three of these results should be 0 or 1. Confirm they are.
8665 Then use those values to select the proper code to use. */
8670 {
8671 /* Make a 3-bit mask with the high-order bit being the
8672 value for `>', the next for '=', and the low for '<'. */
8676 {
8678 /* Always false. */
8699 /* Always true. */
8701 }
8704 {
8708 }
8710 }
8711 }
8712 }
8715 }
8718 /* Subroutine of fold_binary. Optimize complex multiplications of the
8719 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8720 argument EXPR represents the expression "z" of type TYPE. */
8722 static tree
8724 {
8729 {
8732 }
8734 {
8737 }
8738 else
8739 {
8743 }
8752 }
8755 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8756 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8758 static bool
8760 {
8764 {
8767 }
8769 {
8775 else
8777 }
8778 else
8784 }
8786 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8787 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8788 NULL_TREE otherwise. */
8790 static tree
8792 {
8809 {
8813 }
8816 {
8822 }
8823 else
8825 }
8827 /* Try to fold a pointer difference of type TYPE two address expressions of
8828 array references AREF0 and AREF1 using location LOC. Return a
8829 simplified expression for the difference or NULL_TREE. */
8831 static tree
8834 {
8839 /* If the bases are array references as well, recurse. If the bases
8840 are pointer indirections compute the difference of the pointers.
8841 If the bases are equal, we are set. */
8844 && (base_offset
8848 && (base_offset
8854 {
8860 base_offset,
8863 }
8865 }
8867 /* If the real or vector real constant CST of type TYPE has an exact
8868 inverse, return it, else return NULL. */
8870 tree
8872 {
8873 REAL_VALUE_TYPE r;
8875 machine_mode mode;
8879 {
8895 {
8900 }
8906 }
8907 }
8909 /* Mask out the tz least significant bits of X of type TYPE where
8910 tz is the number of trailing zeroes in Y. */
8911 static wide_int
8913 {
8918 }
8920 /* Return true when T is an address and is known to be nonzero.
8921 For floating point we further ensure that T is not denormal.
8922 Similar logic is present in nonzero_address in rtlanal.h.
8924 If the return value is based on the assumption that signed overflow
8925 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8926 change *STRICT_OVERFLOW_P. */
8928 static bool
8930 {
8934 /* Doing something useful for floating point would need more work. */
8940 {
8943 strict_overflow_p);
8949 strict_overflow_p);
8957 }
8960 {
8963 strict_overflow_p);
8971 strict_overflow_p);
8986 strict_overflow_p);
8990 strict_overflow_p);
8993 {
9005 }
9009 }
9011 }
9013 /* Return true when T is an address and is known to be nonzero.
9014 Handle warnings about undefined signed overflow. */
9016 bool
9018 {
9025 "determining that expression is always "
9027 WARN_STRICT_OVERFLOW_MISC);
9029 }
9031 /* Return true if T is known not to be equal to an integer W. */
9033 bool
9035 {
9037 value_range_type rtype;
9039 {
9048 {
9053 }
9058 /* If T has some known zero bits and W has any of those bits set,
9059 then T is known not to be equal to W. */
9067 }
9068 }
9070 /* Fold a binary expression of code CODE and type TYPE with operands
9071 OP0 and OP1. LOC is the location of the resulting expression.
9072 Return the folded expression if folding is successful. Otherwise,
9073 return NULL_TREE. */
9075 tree
9078 {
9093 /* Strip any conversions that don't change the mode. This is
9094 safe for every expression, except for a comparison expression
9095 because its signedness is derived from its operands. So, in
9096 the latter case, only strip conversions that don't change the
9097 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9098 preserved.
9100 Note that this is done as an internal manipulation within the
9101 constant folder, in order to find the simplest representation
9102 of the arguments so that their form can be studied. In any
9103 cases, the appropriate type conversions should be put back in
9104 the tree that will get out of the constant folder. */
9107 {
9110 }
9111 else
9112 {
9115 }
9117 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9118 constant but we can't do arithmetic on them. */
9120 {
9123 {
9127 }
9128 }
9130 /* If this is a commutative operation, and ARG0 is a constant, move it
9131 to ARG1 to reduce the number of tests below. */
9136 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9137 to ARG1 to reduce the number of tests below. */
9146 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9148 First check for cases where an arithmetic operation is applied to a
9149 compound, conditional, or comparison operation. Push the arithmetic
9150 operation inside the compound or conditional to see if any folding
9151 can then be done. Convert comparison to conditional for this purpose.
9152 The also optimizes non-constant cases that used to be done in
9153 expand_expr.
9155 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9156 one of the operands is a comparison and the other is a comparison, a
9157 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9158 code below would make the expression more complex. Change it to a
9159 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9160 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9173 {
9177 boolean_type_node,
9185 }
9189 {
9191 {
9196 tem);
9197 }
9199 {
9204 tem);
9205 }
9210 {
9216 }
9221 {
9227 }
9228 }
9231 {
9233 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9236 {
9242 }
9244 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9247 {
9248 tree base;
9249 HOST_WIDE_INT coffset;
9258 }
9263 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9269 arg1),
9271 arg0)));
9277 {
9278 /* X + (X / CST) * -CST is X % CST. */
9283 {
9292 cst0));
9293 }
9294 }
9296 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9297 one. Make sure the type is not saturating and has the signedness of
9298 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9299 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9306 {
9310 }
9313 {
9314 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9315 (plus (plus (mult) (mult)) (foo)) so that we can
9316 take advantage of the factoring cases below. */
9325 {
9331 else
9344 parg0),
9346 marg)),
9350 return
9356 parg1)));
9357 }
9358 }
9359 else
9360 {
9361 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9362 to __complex__ ( x, y ). This is not the same for SNaNs or
9363 if signed zeros are involved. */
9367 {
9374 {
9378 {
9384 }
9386 {
9392 }
9393 }
9394 }
9402 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9403 We associate floats only if the user has specified
9404 -fassociative-math. */
9408 {
9413 {
9414 tree tree0;
9417 }
9418 }
9419 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9420 We associate floats only if the user has specified
9421 -fassociative-math. */
9425 {
9430 {
9431 tree tree0;
9434 }
9435 }
9436 }
9438 bit_rotate:
9439 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9440 is a rotate of A by C1 bits. */
9441 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9442 is a rotate of A by B bits. */
9443 {
9445 tree rtype;
9454 /* Only create rotates in complete modes. Other cases are not
9455 expanded properly. */
9458 {
9472 {
9476 code0 == LSHIFT_EXPR
9480 }
9482 {
9490 element_precision
9494 return
9497 ? LROTATE_EXPR
9502 }
9504 {
9512 element_precision
9516 return fold_convert_loc
9519 ? LROTATE_EXPR
9523 }
9524 }
9525 }
9527 associate:
9528 /* In most languages, can't associate operations on floats through
9529 parentheses. Rather than remember where the parentheses were, we
9530 don't associate floats at all, unless the user has specified
9531 -fassociative-math.
9532 And, we need to make sure type is not saturating. */
9536 {
9542 /* Split both trees into variables, constants, and literals. Then
9543 associate each group together, the constants with literals,
9544 then the result with variables. This increases the chances of
9545 literals being recombined later and of generating relocatable
9546 expressions for the sum of a constant and literal. */
9554 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9558 /* With undefined overflow prefer doing association in a type
9559 which wraps on overflow, if that is one of the operand types. */
9562 {
9570 }
9572 /* With undefined overflow we can only associate constants with one
9573 variable, and constants whose association doesn't overflow. */
9576 {
9578 {
9579 /* ??? If split_tree would handle NEGATE_EXPR we could
9580 simply reject these cases and the allowed cases would
9581 be the var0/minus_var1 ones. */
9587 {
9590 }
9597 {
9600 }
9606 /* The only case we can still associate with two variables
9607 is if they cancel out. */
9611 }
9617 }
9619 /* Only do something if we found more than two objects. Otherwise,
9620 nothing has changed and we risk infinite recursion. */
9628 {
9640 {
9644 }
9646 {
9650 }
9652 /* Preserve the MINUS_EXPR if the negative part of the literal is
9653 greater than the positive part. Otherwise, the multiplicative
9654 folding code (i.e extract_muldiv) may be fooled in case
9655 unsigned constants are subtracted, like in the following
9656 example: ((X*2 + 4) - 8U)/2. */
9658 {
9662 /* But avoid ending up with only negated parts. */
9664 {
9668 }
9669 else
9670 {
9674 }
9675 }
9677 /* Don't introduce overflows through reassociation. */
9682 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9689 /* Eliminate minus_con0. */
9691 {
9698 else
9701 }
9703 /* Eliminate minus_var0. */
9705 {
9709 else
9712 }
9714 return
9717 }
9718 }
9723 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9731 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9732 __complex__ ( x, -y ). This is not the same for SNaNs or if
9733 signed zeros are involved. */
9737 {
9744 {
9748 {
9750 arg1r ? arg1r
9755 }
9757 {
9761 arg1i ? arg1i
9764 }
9765 }
9766 }
9768 /* A - B -> A + (-B) if B is easily negatable. */
9772 /* Avoid this transformation if B is a positive REAL_CST. */
9780 /* Fold &a[i] - &a[j] to i-j. */
9785 {
9791 }
9794 && flag_unsafe_math_optimizations
9800 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9801 one. Make sure the type is not saturating and has the signedness of
9802 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9803 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9810 {
9814 }
9820 {
9821 /* Transform x * -C into -x * C if x is easily negatable. */
9836 {
9839 "occur when simplifying "
9841 WARN_STRICT_OVERFLOW_MISC);
9843 }
9845 /* Optimize z * conj(z) for integer complex numbers. */
9852 }
9853 else
9854 {
9855 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9856 This is not the same for NaNs or if signed zeros are
9857 involved. */
9863 {
9866 return
9872 return
9877 }
9879 /* Optimize z * conj(z) for floating point complex numbers.
9880 Guarded by flag_unsafe_math_optimizations as non-finite
9881 imaginary components don't produce scalar results. */
9890 }
9894 /* Canonicalize (X & C1) | C2. */
9898 {
9903 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9911 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9913 {
9916 }
9918 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9919 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9920 mode which allows further optimizations. */
9925 {
9929 {
9932 }
9933 }
9936 {
9941 }
9942 }
9944 /* See if this can be simplified into a rotate first. If that
9945 is unsuccessful continue in the association code. */
9949 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9957 /* See if this can be simplified into a rotate first. If that
9958 is unsuccessful continue in the association code. */
9962 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9967 {
9968 tree tem2;
9975 }
9976 /* Fold ~X & 1 as (X & 1) == 0. */
9980 {
9981 tree tem2;
9988 }
9989 /* Fold !X & 1 as X == 0. */
9992 {
9996 }
9998 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9999 multiple of 1 << CST. */
10001 {
10008 }
10010 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10011 bits from CST2. */
10015 {
10023 {
10024 /* Avoid the transform if arg1 is a mask of some
10025 mode which allows further optimizations. */
10032 }
10033 }
10035 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10036 ((A & N) + B) & M -> (A + B) & M
10037 Similarly if (N & M) == 0,
10038 ((A | N) + B) & M -> (A + B) & M
10039 and for - instead of + (or unary - instead of +)
10040 and/or ^ instead of |.
10041 If B is constant and (B & M) == 0, fold into A & M. */
10043 {
10052 {
10055 wide_int cst0;
10057 /* Now we know that arg0 is (C + D) or (C - D) or
10058 -C and arg1 (M) is == (1LL << cst) - 1.
10059 Store C into PMOP[0] and D into PMOP[1]. */
10063 {
10066 }
10073 {
10083 {
10086 }
10089 /* If C or D is of the form (A & N) where
10090 (N & M) == M, or of the form (A | N) or
10091 (A ^ N) where (N & M) == 0, replace it with A. */
10095 /* If C or D is a N where (N & M) == 0, it can be
10096 omitted (assumed 0). */
10104 }
10106 /* Only build anything new if we optimized one or both arguments
10107 above. */
10111 {
10114 {
10115 /* Perform the operations in a type that has defined
10116 overflow behavior. */
10122 }
10127 {
10135 else
10137 }
10140 else
10143 /* TEM is now the new binary +, - or unary - replacement. */
10147 }
10148 }
10149 }
10151 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10154 {
10159 return
10161 }
10166 /* Don't touch a floating-point divide by zero unless the mode
10167 of the constant can represent infinity. */
10173 /* (-A) / (-B) -> A / B */
10185 /* Fall through */
10188 /* Simplify A / (B << N) where A and B are positive and B is
10189 a power of 2, to A >> (N + log2(B)). */
10194 {
10197 {
10205 WARN_STRICT_OVERFLOW_MISC);
10211 }
10212 }
10214 /* Fall through */
10222 /* Convert -A / -B to A / B when the type is signed and overflow is
10223 undefined. */
10227 {
10230 "when distributing negation across "
10232 WARN_STRICT_OVERFLOW_MISC);
10237 }
10241 {
10244 "when distributing negation across "
10246 WARN_STRICT_OVERFLOW_MISC);
10251 }
10253 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10254 operation, EXACT_DIV_EXPR.
10256 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10257 At one time others generated faster code, it's not clear if they do
10258 after the last round to changes to the DIV code in expmed.c. */
10269 {
10273 WARN_STRICT_OVERFLOW_MISC);
10275 }
10287 {
10291 WARN_STRICT_OVERFLOW_MISC);
10293 }
10301 /* Since negative shift count is not well-defined,
10302 don't try to compute it in the compiler. */
10308 /* If we have a rotate of a bit operation with the rotate count and
10309 the second operand of the bit operation both constant,
10310 permute the two operations. */
10316 {
10324 }
10326 /* Two consecutive rotates adding up to the some integer
10327 multiple of the precision of the type can be ignored. */
10342 /* Note that the operands of this must be ints
10343 and their values must be 0 or 1.
10344 ("true" is a fixed value perhaps depending on the language.) */
10345 /* If first arg is constant zero, return it. */
10348 /* FALLTHRU */
10350 /* If either arg is constant true, drop it. */
10354 /* Preserve sequence points. */
10357 /* If second arg is constant zero, result is zero, but first arg
10358 must be evaluated. */
10361 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10362 case will be handled here. */
10366 /* !X && X is always false. */
10370 /* X && !X is always false. */
10375 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10376 means A >= Y && A != MAX, but in this case we know that
10377 A < X <= MAX. */
10381 {
10389 }
10398 /* Note that the operands of this must be ints
10399 and their values must be 0 or true.
10400 ("true" is a fixed value perhaps depending on the language.) */
10401 /* If first arg is constant true, return it. */
10404 /* FALLTHRU */
10406 /* If either arg is constant zero, drop it. */
10410 /* Preserve sequence points. */
10413 /* If second arg is constant true, result is true, but we must
10414 evaluate first arg. */
10417 /* Likewise for first arg, but note this only occurs here for
10418 TRUTH_OR_EXPR. */
10422 /* !X || X is always true. */
10426 /* X || !X is always true. */
10431 /* (X && !Y) || (!X && Y) is X ^ Y */
10434 {
10451 }
10460 /* If the second arg is constant zero, drop it. */
10463 /* If the second arg is constant true, this is a logical inversion. */
10465 {
10468 }
10469 /* Identical arguments cancel to zero. */
10473 /* !X ^ X is always true. */
10478 /* X ^ !X is always true. */
10494 /* bool_var != 1 becomes !bool_var. */
10501 /* bool_var == 0 becomes !bool_var. */
10508 /* !exp != 0 becomes !exp */
10513 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10522 {
10528 }
10530 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10539 {
10545 }
10547 /* If this is an EQ or NE comparison with zero and ARG0 is
10548 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10549 two operations, but the latter can be done in one less insn
10550 on machines that have only two-operand insns or on which a
10551 constant cannot be the first operand. */
10554 {
10559 {
10566 arg1);
10567 }
10570 {
10577 arg1);
10578 }
10579 }
10581 /* If this is an NE or EQ comparison of zero against the result of a
10582 signed MOD operation whose second operand is a power of 2, make
10583 the MOD operation unsigned since it is simpler and equivalent. */
10591 {
10601 }
10603 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10604 C1 is a valid shift constant, and C2 is a power of two, i.e.
10605 a single bit. */
10609 == INTEGER_CST
10612 {
10617 /* Check for a valid shift count. */
10619 {
10623 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10624 can be rewritten as (X & (C2 << C1)) != 0. */
10626 {
10631 }
10632 /* Otherwise, for signed (arithmetic) shifts,
10633 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10634 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10638 /* Otherwise, of unsigned (logical) shifts,
10639 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10640 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10641 else
10645 arg000);
10646 }
10647 }
10649 /* If this is a comparison of a field, we may be able to simplify it. */
10652 /* Handle the constant case even without -O
10653 to make sure the warnings are given. */
10655 {
10659 }
10661 /* Optimize comparisons of strlen vs zero to a compare of the
10662 first character of the string vs zero. To wit,
10663 strlen(ptr) == 0 => *ptr == 0
10664 strlen(ptr) != 0 => *ptr != 0
10665 Other cases should reduce to one of these two (or a constant)
10666 due to the return value of strlen being unsigned. */
10669 {
10677 {
10682 }
10683 }
10685 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10686 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10690 {
10695 {
10697 {
10700 }
10703 }
10704 }
10706 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10707 (X & C) == 0 when C is a single bit. */
10712 {
10719 arg1));
10720 }
10722 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10723 constant C is a power of two, i.e. a single bit. */
10730 {
10734 }
10736 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10737 when is C is a power of two, i.e. a single bit. */
10744 {
10750 }
10754 {
10757 }
10759 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10762 {
10770 {
10776 }
10778 {
10784 }
10786 {
10792 }
10794 {
10800 }
10801 }
10805 {
10812 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10813 operand_equal_p guarantees no side-effects so we don't need
10814 to use omit_one_operand on Z. */
10818 arg10));
10822 arg11));
10826 arg10));
10830 arg11));
10832 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10835 {
10841 }
10842 }
10844 /* Attempt to simplify equality/inequality comparisons of complex
10845 values. Only lower the comparison if the result is known or
10846 can be simplified to a single scalar comparison. */
10851 {
10856 {
10859 }
10860 else
10861 {
10864 }
10867 {
10870 }
10871 else
10872 {
10875 }
10879 {
10881 {
10886 }
10887 else
10888 {
10893 }
10894 }
10898 {
10900 {
10905 }
10906 else
10907 {
10912 }
10913 }
10914 }
10926 /* Transform comparisons of the form X +- C CMP X. */
10933 {
10940 else
10943 /* (X - c) > X becomes false. */
10947 {
10951 "occur when assuming that (X - c) > X "
10953 WARN_STRICT_OVERFLOW_ALL);
10955 }
10957 /* Likewise (X + c) < X becomes false. */
10961 {
10965 "occur when assuming that "
10967 WARN_STRICT_OVERFLOW_ALL);
10969 }
10971 /* Convert (X - c) <= X to true. */
10976 {
10980 "occur when assuming that "
10982 WARN_STRICT_OVERFLOW_ALL);
10984 }
10986 /* Convert (X + c) >= X to true. */
10991 {
10995 "occur when assuming that "
10997 WARN_STRICT_OVERFLOW_ALL);
10999 }
11002 {
11003 /* Convert X + c > X and X - c < X to true for integers. */
11007 {
11010 "not occur when assuming that "
11012 WARN_STRICT_OVERFLOW_ALL);
11014 }
11019 {
11022 "not occur when assuming that "
11024 WARN_STRICT_OVERFLOW_ALL);
11026 }
11028 /* Convert X + c <= X and X - c >= X to false for integers. */
11032 {
11035 "not occur when assuming that "
11037 WARN_STRICT_OVERFLOW_ALL);
11039 }
11044 {
11047 "not occur when assuming that "
11049 WARN_STRICT_OVERFLOW_ALL);
11051 }
11052 }
11053 }
11055 /* If we are comparing an ABS_EXPR with a constant, we can
11056 convert all the cases into explicit comparisons, but they may
11057 well not be faster than doing the ABS and one comparison.
11058 But ABS (X) <= C is a range comparison, which becomes a subtraction
11059 and a comparison, and is probably faster. */
11073 /* Convert ABS_EXPR<x> >= 0 to true. */
11080 {
11083 "when simplifying comparison of "
11085 WARN_STRICT_OVERFLOW_CONDITIONAL);
11088 arg0);
11089 }
11091 /* Convert ABS_EXPR<x> < 0 to false. */
11096 {
11099 "when simplifying comparison of "
11101 WARN_STRICT_OVERFLOW_CONDITIONAL);
11104 arg0);
11105 }
11107 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11108 and similarly for >= into !=. */
11118 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11119 otherwise Y might be >= # of bits in X's type and thus e.g.
11120 (unsigned char) (1 << Y) for Y 15 might be 0.
11121 If the cast is widening, then 1 << Y should have unsigned type,
11122 otherwise if Y is number of bits in the signed shift type minus 1,
11123 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11124 31 might be 0xffffffff80000000. */
11135 {
11141 }
11153 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11154 {
11166 }
11171 /* When pedantic, a compound expression can be neither an lvalue
11172 nor an integer constant expression. */
11175 /* Don't let (0, 0) be null pointer constant. */
11181 /* An ASSERT_EXPR should never be passed to fold_binary. */
11187 }
11189 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11190 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11191 of GOTO_EXPR. */
11193 static tree
11195 {
11197 {
11204 /* fall through */
11208 }
11209 }
11211 /* Return whether the sub-tree ST contains a label which is accessible from
11212 outside the sub-tree. */
11214 static bool
11216 {
11217 return
11219 }
11221 /* Fold a ternary expression of code CODE and type TYPE with operands
11222 OP0, OP1, and OP2. Return the folded expression if folding is
11223 successful. Otherwise, return NULL_TREE. */
11225 tree
11228 {
11229 tree tem;
11236 /* If this is a commutative operation, and OP0 is a constant, move it
11237 to OP1 to reduce the number of tests below. */
11246 /* Strip any conversions that don't change the mode. This is safe
11247 for every expression, except for a comparison expression because
11248 its signedness is derived from its operands. So, in the latter
11249 case, only strip conversions that don't change the signedness.
11251 Note that this is done as an internal manipulation within the
11252 constant folder, in order to find the simplest representation of
11253 the arguments so that their form can be studied. In any cases,
11254 the appropriate type conversions should be put back in the tree
11255 that will get out of the constant folder. */
11257 {
11260 }
11263 {
11266 }
11269 {
11272 }
11275 {
11279 {
11285 }
11290 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11291 so all simple results must be passed through pedantic_non_lvalue. */
11293 {
11296 /* Only optimize constant conditions when the selected branch
11297 has the same type as the COND_EXPR. This avoids optimizing
11298 away "c ? x : throw", where the throw has a void type.
11299 Avoid throwing away that operand which contains label. */
11306 }
11308 {
11313 {
11318 {
11326 }
11330 }
11331 }
11333 /* If we have A op B ? A : C, we may be able to convert this to a
11334 simpler expression, depending on the operation and the values
11335 of B and C. Signed zeros prevent all of these transformations,
11336 for reasons given above each one.
11338 Also try swapping the arguments and inverting the conditional. */
11342 {
11346 }
11351 {
11355 {
11359 }
11360 }
11362 /* If the second operand is simpler than the third, swap them
11363 since that produces better jump optimization results. */
11366 {
11368 /* See if this can be inverted. If it can't, possibly because
11369 it was a floating-point inequality comparison, don't do
11370 anything. */
11374 }
11376 /* Convert A ? 1 : 0 to simply A. */
11381 /* If we try to convert OP0 to our type, the
11382 call to fold will try to move the conversion inside
11383 a COND, which will recurse. In that case, the COND_EXPR
11384 is probably the best choice, so leave it alone. */
11388 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11389 over COND_EXPR in cases such as floating point comparisons. */
11398 arg0)));
11400 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11405 {
11406 /* sign_bit_p looks through both zero and sign extensions,
11407 but for this optimization only sign extensions are
11408 usable. */
11411 {
11414 {
11417 }
11419 }
11420 /* sign_bit_p only checks ARG1 bits within A's precision.
11421 If <sign bit of A> has wider type than A, bits outside
11422 of A's precision in <sign bit of A> need to be checked.
11423 If they are all 0, this optimization needs to be done
11424 in unsigned A's type, if they are all 1 in signed A's type,
11425 otherwise this can't be done. */
11431 {
11433 tree tem_type;
11446 {
11449 }
11451 {
11454 }
11455 else
11457 }
11460 return
11466 arg1)));
11467 }
11469 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11470 already handled above. */
11475 {
11485 op1);
11486 }
11488 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11489 is probably obsolete because the first operand should be a
11490 truth value (that's why we have the two cases above), but let's
11491 leave it in until we can confirm this for all front-ends. */
11503 /* Disable the transformations below for vectors, since
11504 fold_binary_op_with_conditional_arg may undo them immediately,
11505 yielding an infinite loop. */
11509 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11518 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11523 {
11525 /* Only perform transformation if ARG0 is easily inverted. */
11529 ? BIT_IOR_EXPR
11532 op1);
11533 }
11535 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11540 {
11542 /* Only perform transformation if ARG0 is easily inverted. */
11548 op2);
11549 }
11551 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11563 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11564 of fold_ternary on them. */
11572 {
11582 {
11587 {
11595 }
11596 }
11597 }
11599 /* On constants we can use native encode/interpret to constant
11600 fold (nearly) all BIT_FIELD_REFs. */
11604 {
11607 /* Limit us to a reasonable amount of work. To relax the
11608 other limitations we need bit-shifting of the buffer
11609 and rounding up the size. */
11613 {
11615 unsigned HOST_WIDE_INT len
11620 {
11625 }
11626 }
11627 }
11632 /* For integers we can decompose the FMA if possible. */
11644 {
11660 {
11665 /* Make sure that the perm value is in an acceptable
11666 range. */
11675 else
11680 }
11683 {
11688 }
11693 {
11698 }
11704 {
11708 }
11713 /* Some targets are deficient and fail to expand a single
11714 argument permutation while still allowing an equivalent
11715 2-argument version. */
11719 {
11722 }
11725 {
11732 }
11736 }
11740 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11743 {
11749 wide_int tem2
11753 }
11758 {
11760 unsigned HOST_WIDE_INT elsize
11763 {
11767 else
11768 {
11774 }
11775 }
11776 }
11782 }
11784 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11785 of an array (or vector). */
11787 tree
11789 {
11794 {
11797 {
11798 /* Static constructors for variably sized objects makes no sense. */
11802 }
11803 }
11814 offset_int max_index;
11819 {
11820 /* Array constructor might explicitly set index, or specify a range,
11821 or leave index NULL meaning that it is next index after previous
11822 one. */
11824 {
11827 else
11828 {
11832 }
11833 }
11834 else
11835 {
11841 }
11843 /* Do we have match? */
11847 }
11849 }
11851 /* Perform constant folding and related simplification of EXPR.
11852 The related simplifications include x*1 => x, x*0 => 0, etc.,
11853 and application of the associative law.
11854 NOP_EXPR conversions may be removed freely (as long as we
11855 are careful not to change the type of the overall expression).
11856 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11857 but we can constant-fold them if they have constant operands. */
11859 #ifdef ENABLE_FOLD_CHECKING
11860 # define fold(x) fold_1 (x)
11862 static
11863 #endif
11864 tree
11866 {
11870 tree tem;
11873 /* Return right away if a constant. */
11877 /* CALL_EXPR-like objects with variable numbers of operands are
11878 treated specially. */
11880 {
11882 {
11885 }
11887 }
11890 {
11895 {
11913 }
11914 }
11917 {
11919 {
11926 {
11931 }
11934 }
11936 /* Return a VECTOR_CST if possible. */
11938 {
11944 tree val;
11950 }
11958 }
11960 #ifdef ENABLE_FOLD_CHECKING
11961 #undef fold
11968 /* When --enable-checking=fold, compute a digest of expr before
11969 and after actual fold call to see if fold did not accidentally
11970 change original expr. */
11972 tree
11974 {
11975 tree ret;
11995 }
11997 void
11999 {
12010 }
12012 static void
12014 {
12016 }
12018 static void
12021 {
12027 recursive_label:
12037 {
12038 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12043 }
12051 {
12052 /* Allow these fields to be modified. */
12053 tree tmp;
12062 {
12065 }
12066 }
12077 {
12080 {
12095 }
12099 {
12112 }
12129 {
12135 }
12138 {
12140 {
12143 }
12145 }
12156 {
12159 }
12169 }
12170 }
12172 /* Helper function for outputting the checksum of a tree T. When
12173 debugging with gdb, you can "define mynext" to be "next" followed
12174 by "call debug_fold_checksum (op0)", then just trace down till the
12175 outputs differ. */
12177 DEBUG_FUNCTION void
12179 {
12194 }
12196 #endif
12198 /* Fold a unary tree expression with code CODE of type TYPE with an
12199 operand OP0. LOC is the location of the resulting expression.
12200 Return a folded expression if successful. Otherwise, return a tree
12201 expression with code CODE of type TYPE with an operand OP0. */
12203 tree
12206 {
12207 tree tem;
12208 #ifdef ENABLE_FOLD_CHECKING
12217 #endif
12223 #ifdef ENABLE_FOLD_CHECKING
12230 #endif
12232 }
12234 /* Fold a binary tree expression with code CODE of type TYPE with
12235 operands OP0 and OP1. LOC is the location of the resulting
12236 expression. Return a folded expression if successful. Otherwise,
12237 return a tree expression with code CODE of type TYPE with operands
12238 OP0 and OP1. */
12240 tree
12243 MEM_STAT_DECL)
12244 {
12245 tree tem;
12246 #ifdef ENABLE_FOLD_CHECKING
12263 #endif
12269 #ifdef ENABLE_FOLD_CHECKING
12284 #endif
12286 }
12288 /* Fold a ternary tree expression with code CODE of type TYPE with
12289 operands OP0, OP1, and OP2. Return a folded expression if
12290 successful. Otherwise, return a tree expression with code CODE of
12291 type TYPE with operands OP0, OP1, and OP2. */
12293 tree
12296 {
12297 tree tem;
12298 #ifdef ENABLE_FOLD_CHECKING
12322 #endif
12329 #ifdef ENABLE_FOLD_CHECKING
12352 #endif
12354 }
12356 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12357 arguments in ARGARRAY, and a null static chain.
12358 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12359 of type TYPE from the given operands as constructed by build_call_array. */
12361 tree
12364 {
12365 tree tem;
12366 #ifdef ENABLE_FOLD_CHECKING
12385 #endif
12391 #ifdef ENABLE_FOLD_CHECKING
12407 #endif
12409 }
12411 /* Perform constant folding and related simplification of initializer
12412 expression EXPR. These behave identically to "fold_buildN" but ignore
12413 potential run-time traps and exceptions that fold must preserve. */
12415 #define START_FOLD_INIT \
12416 int saved_signaling_nans = flag_signaling_nans;\
12417 int saved_trapping_math = flag_trapping_math;\
12418 int saved_rounding_math = flag_rounding_math;\
12419 int saved_trapv = flag_trapv;\
12420 int saved_folding_initializer = folding_initializer;\
12421 flag_signaling_nans = 0;\
12422 flag_trapping_math = 0;\
12423 flag_rounding_math = 0;\
12424 flag_trapv = 0;\
12425 folding_initializer = 1;
12427 #define END_FOLD_INIT \
12428 flag_signaling_nans = saved_signaling_nans;\
12429 flag_trapping_math = saved_trapping_math;\
12430 flag_rounding_math = saved_rounding_math;\
12431 flag_trapv = saved_trapv;\
12432 folding_initializer = saved_folding_initializer;
12434 tree
12437 {
12438 tree result;
12439 START_FOLD_INIT;
12443 END_FOLD_INIT;
12445 }
12447 tree
12450 {
12451 tree result;
12452 START_FOLD_INIT;
12456 END_FOLD_INIT;
12458 }
12460 tree
12463 {
12464 tree result;
12465 START_FOLD_INIT;
12469 END_FOLD_INIT;
12471 }
12473 #undef START_FOLD_INIT
12474 #undef END_FOLD_INIT
12476 /* Determine if first argument is a multiple of second argument. Return 0 if
12477 it is not, or we cannot easily determined it to be.
12479 An example of the sort of thing we care about (at this point; this routine
12480 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12481 fold cases do now) is discovering that
12483 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12485 is a multiple of
12487 SAVE_EXPR (J * 8)
12489 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12491 This code also handles discovering that
12493 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12495 is a multiple of 8 so we don't have to worry about dealing with a
12496 possible remainder.
12498 Note that we *look* inside a SAVE_EXPR only to determine how it was
12499 calculated; it is not safe for fold to do much of anything else with the
12500 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12501 at run time. For example, the latter example above *cannot* be implemented
12502 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12503 evaluation time of the original SAVE_EXPR is not necessarily the same at
12504 the time the new expression is evaluated. The only optimization of this
12505 sort that would be valid is changing
12507 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12509 divided by 8 to
12511 SAVE_EXPR (I) * SAVE_EXPR (J)
12513 (where the same SAVE_EXPR (J) is used in the original and the
12514 transformed version). */
12516 int
12518 {
12529 {
12531 /* Bitwise and provides a power of two multiple. If the mask is
12532 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12535 /* FALLTHRU */
12542 /* It is impossible to prove if op0 - op1 is multiple of bottom
12543 precisely, so be conservative here checking if both op0 and op1
12544 are multiple of bottom. Note we check the second operand first
12545 since it's usually simpler. */
12550 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12551 as op0 - 3 if the expression has unsigned type. For example,
12552 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12562 {
12564 /* const_binop may not detect overflow correctly,
12565 so check for it explicitly here. */
12569 size_one_node,
12570 op1)))
12573 }
12577 /* Can't handle conversions from non-integral or wider integral type. */
12583 /* fall through */
12600 SIGNED);
12606 {
12609 /* Check for special cases to see if top is defined as multiple
12610 of bottom:
12612 top = (X & ~(bottom - 1) ; bottom is power of 2
12614 or
12616 Y = X % bottom
12617 top = X - Y. */
12636 }
12638 /* fall through */
12642 }
12643 }
12645 #define tree_expr_nonnegative_warnv_p(X, Y) \
12648 #define RECURSE(X) \
12649 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12651 /* Return true if CODE or TYPE is known to be non-negative. */
12653 static bool
12655 {
12658 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12659 have a signed:1 type (where the value is -1 and 0). */
12662 }
12664 /* Return true if (CODE OP0) is known to be non-negative. If the return
12665 value is based on the assumption that signed overflow is undefined,
12666 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12667 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12669 bool
12672 {
12677 {
12679 /* We can't return 1 if flag_wrapv is set because
12680 ABS_EXPR<INT_MIN> = INT_MIN. */
12684 {
12687 }
12695 CASE_CONVERT:
12696 {
12701 {
12705 {
12709 }
12710 }
12712 {
12718 }
12719 }
12724 }
12726 /* We don't know sign of `t', so be conservative and return false. */
12728 }
12730 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12731 value is based on the assumption that signed overflow is undefined,
12732 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12733 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12735 bool
12739 {
12744 {
12750 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12751 both unsigned and at least 2 bits shorter than the result. */
12755 {
12760 {
12764 }
12765 }
12770 {
12771 /* x * x is always non-negative for floating point x
12772 or without overflow. */
12775 {
12780 }
12781 }
12783 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12784 both unsigned and their total bits is shorter than the result. */
12788 {
12807 {
12817 }
12818 }
12845 }
12847 /* We don't know sign of `t', so be conservative and return false. */
12849 }
12851 /* Return true if T is known to be non-negative. If the return
12852 value is based on the assumption that signed overflow is undefined,
12853 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12854 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12856 bool
12858 {
12863 {
12877 /* Limit the depth of recursion to avoid quadratic behavior.
12878 This is expected to catch almost all occurrences in practice.
12879 If this code misses important cases that unbounded recursion
12880 would not, passes that need this information could be revised
12881 to provide it through dataflow propagation. */
12889 }
12890 }
12892 /* Return true if T is known to be non-negative. If the return
12893 value is based on the assumption that signed overflow is undefined,
12894 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12895 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12897 bool
12900 {
12902 {
12903 CASE_CFN_ACOS:
12904 CASE_CFN_ACOSH:
12905 CASE_CFN_CABS:
12906 CASE_CFN_COSH:
12907 CASE_CFN_ERFC:
12908 CASE_CFN_EXP:
12909 CASE_CFN_EXP10:
12910 CASE_CFN_EXP2:
12911 CASE_CFN_FABS:
12912 CASE_CFN_FDIM:
12913 CASE_CFN_HYPOT:
12914 CASE_CFN_POW10:
12915 CASE_CFN_FFS:
12916 CASE_CFN_PARITY:
12917 CASE_CFN_POPCOUNT:
12918 CASE_CFN_CLZ:
12919 CASE_CFN_CLRSB:
12922 /* Always true. */
12925 CASE_CFN_SQRT:
12926 /* sqrt(-0.0) is -0.0. */
12931 CASE_CFN_ASINH:
12932 CASE_CFN_ATAN:
12933 CASE_CFN_ATANH:
12934 CASE_CFN_CBRT:
12935 CASE_CFN_CEIL:
12936 CASE_CFN_ERF:
12937 CASE_CFN_EXPM1:
12938 CASE_CFN_FLOOR:
12939 CASE_CFN_FMOD:
12940 CASE_CFN_FREXP:
12941 CASE_CFN_ICEIL:
12942 CASE_CFN_IFLOOR:
12943 CASE_CFN_IRINT:
12944 CASE_CFN_IROUND:
12945 CASE_CFN_LCEIL:
12946 CASE_CFN_LDEXP:
12947 CASE_CFN_LFLOOR:
12948 CASE_CFN_LLCEIL:
12949 CASE_CFN_LLFLOOR:
12950 CASE_CFN_LLRINT:
12951 CASE_CFN_LLROUND:
12952 CASE_CFN_LRINT:
12953 CASE_CFN_LROUND:
12954 CASE_CFN_MODF:
12955 CASE_CFN_NEARBYINT:
12956 CASE_CFN_RINT:
12957 CASE_CFN_ROUND:
12958 CASE_CFN_SCALB:
12959 CASE_CFN_SCALBLN:
12960 CASE_CFN_SCALBN:
12961 CASE_CFN_SIGNBIT:
12962 CASE_CFN_SIGNIFICAND:
12963 CASE_CFN_SINH:
12964 CASE_CFN_TANH:
12965 CASE_CFN_TRUNC:
12966 /* True if the 1st argument is nonnegative. */
12969 CASE_CFN_FMAX:
12970 /* True if the 1st OR 2nd arguments are nonnegative. */
12973 CASE_CFN_FMIN:
12974 /* True if the 1st AND 2nd arguments are nonnegative. */
12977 CASE_CFN_COPYSIGN:
12978 /* True if the 2nd argument is nonnegative. */
12981 CASE_CFN_POWI:
12982 /* True if the 1st argument is nonnegative or the second
12983 argument is an even integer. */
12989 CASE_CFN_POW:
12990 /* True if the 1st argument is nonnegative or the second
12991 argument is an even integer valued real. */
12993 {
12994 REAL_VALUE_TYPE c;
12995 HOST_WIDE_INT n;
13000 {
13001 REAL_VALUE_TYPE cint;
13005 }
13006 }
13011 }
13013 }
13015 /* Return true if T is known to be non-negative. If the return
13016 value is based on the assumption that signed overflow is undefined,
13017 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13018 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13020 static bool
13022 {
13028 {
13030 {
13034 /* If the initializer is non-void, then it's a normal expression
13035 that will be assigned to the slot. */
13039 /* Otherwise, the initializer sets the slot in some way. One common
13040 way is an assignment statement at the end of the initializer. */
13042 {
13050 else
13052 }
13058 }
13061 {
13067 arg0,
13068 arg1,
13070 }
13083 }
13084 }
13086 #undef RECURSE
13087 #undef tree_expr_nonnegative_warnv_p
13089 /* Return true if T is known to be non-negative. If the return
13090 value is based on the assumption that signed overflow is undefined,
13091 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13092 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13094 bool
13096 {
13103 {
13125 }
13128 {
13154 }
13155 }
13157 /* Return true if `t' is known to be non-negative. Handle warnings
13158 about undefined signed overflow. */
13160 bool
13162 {
13169 "determining that expression is always "
13171 WARN_STRICT_OVERFLOW_MISC);
13173 }
13176 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13177 For floating point we further ensure that T is not denormal.
13178 Similar logic is present in nonzero_address in rtlanal.h.
13180 If the return value is based on the assumption that signed overflow
13181 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13182 change *STRICT_OVERFLOW_P. */
13184 bool
13187 {
13189 {
13192 strict_overflow_p);
13195 {
13201 strict_overflow_p));
13202 }
13207 strict_overflow_p);
13211 }
13214 }
13216 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13217 For floating point we further ensure that T is not denormal.
13218 Similar logic is present in nonzero_address in rtlanal.h.
13220 If the return value is based on the assumption that signed overflow
13221 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13222 change *STRICT_OVERFLOW_P. */
13224 bool
13226 tree type,
13227 tree op0,
13229 {
13232 {
13236 {
13237 /* With the presence of negative values it is hard
13238 to say something. */
13245 /* One of operands must be positive and the other non-negative. */
13246 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13247 overflows, on a twos-complement machine the sum of two
13248 nonnegative numbers can never be zero. */
13250 strict_overflow_p)
13252 strict_overflow_p));
13253 }
13258 {
13260 strict_overflow_p)
13262 strict_overflow_p))
13263 {
13266 }
13267 }
13276 {
13279 }
13286 {
13290 /* When both operands are nonzero, then MAX must be too. */
13292 strict_overflow_p))
13295 /* MAX where operand 0 is positive is positive. */
13297 strict_overflow_p);
13298 }
13299 /* MAX where operand 1 is positive is positive. */
13304 {
13308 }
13313 strict_overflow_p)
13315 strict_overflow_p));
13319 }
13322 }
13324 /* Return true when T is an address and is known to be nonzero.
13325 For floating point we further ensure that T is not denormal.
13326 Similar logic is present in nonzero_address in rtlanal.h.
13328 If the return value is based on the assumption that signed overflow
13329 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13330 change *STRICT_OVERFLOW_P. */
13332 bool
13334 {
13337 {
13342 {
13354 /* For objects in symbol table check if we know they are non-zero.
13355 Don't do anything for variables and functions before symtab is built;
13356 it is quite possible that they will be declared weak later. */
13361 /* Constants are never weak. */
13366 }
13374 {
13378 }
13388 }
13390 }
13392 #define integer_valued_real_p(X) \
13395 #define RECURSE(X) \
13396 ((integer_valued_real_p) (X, depth + 1))
13398 /* Return true if the floating point result of (CODE OP0) has an
13399 integer value. We also allow +Inf, -Inf and NaN to be considered
13400 integer values. Return false for signaling NaN.
13402 DEPTH is the current nesting depth of the query. */
13404 bool
13406 {
13408 {
13415 CASE_CONVERT:
13416 {
13423 }
13427 }
13429 }
13431 /* Return true if the floating point result of (CODE OP0 OP1) has an
13432 integer value. We also allow +Inf, -Inf and NaN to be considered
13433 integer values. Return false for signaling NaN.
13435 DEPTH is the current nesting depth of the query. */
13437 bool
13439 {
13441 {
13451 }
13453 }
13455 /* Return true if the floating point result of calling FNDECL with arguments
13456 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13457 considered integer values. Return false for signaling NaN. If FNDECL
13458 takes fewer than 2 arguments, the remaining ARGn are null.
13460 DEPTH is the current nesting depth of the query. */
13462 bool
13464 {
13466 {
13467 CASE_CFN_CEIL:
13468 CASE_CFN_FLOOR:
13469 CASE_CFN_NEARBYINT:
13470 CASE_CFN_RINT:
13471 CASE_CFN_ROUND:
13472 CASE_CFN_TRUNC:
13475 CASE_CFN_FMIN:
13476 CASE_CFN_FMAX:
13481 }
13483 }
13485 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13486 has an integer value. We also allow +Inf, -Inf and NaN to be
13487 considered integer values. Return false for signaling NaN.
13489 DEPTH is the current nesting depth of the query. */
13491 bool
13493 {
13495 {
13503 /* Limit the depth of recursion to avoid quadratic behavior.
13504 This is expected to catch almost all occurrences in practice.
13505 If this code misses important cases that unbounded recursion
13506 would not, passes that need this information could be revised
13507 to provide it through dataflow propagation. */
13511 depth));
13515 }
13517 }
13519 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13520 has an integer value. We also allow +Inf, -Inf and NaN to be
13521 considered integer values. Return false for signaling NaN.
13523 DEPTH is the current nesting depth of the query. */
13525 static bool
13527 {
13529 {
13540 }
13542 }
13544 #undef RECURSE
13545 #undef integer_valued_real_p
13547 /* Return true if the floating point expression T has an integer value.
13548 We also allow +Inf, -Inf and NaN to be considered integer values.
13549 Return false for signaling NaN.
13551 DEPTH is the current nesting depth of the query. */
13553 bool
13555 {
13561 {
13577 }
13580 {
13586 {
13595 }
13599 }
13600 }
13602 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13603 attempt to fold the expression to a constant without modifying TYPE,
13604 OP0 or OP1.
13606 If the expression could be simplified to a constant, then return
13607 the constant. If the expression would not be simplified to a
13608 constant, then return NULL_TREE. */
13610 tree
13612 {
13615 }
13617 /* Given the components of a unary expression CODE, TYPE and OP0,
13618 attempt to fold the expression to a constant without modifying
13619 TYPE or OP0.
13621 If the expression could be simplified to a constant, then return
13622 the constant. If the expression would not be simplified to a
13623 constant, then return NULL_TREE. */
13625 tree
13627 {
13630 }
13632 /* If EXP represents referencing an element in a constant string
13633 (either via pointer arithmetic or array indexing), return the
13634 tree representing the value accessed, otherwise return NULL. */
13636 tree
13638 {
13642 {
13644 tree index;
13645 tree string;
13650 else
13651 {
13655 /* Optimize the special-case of a zero lower bound.
13657 We convert the low_bound to sizetype to avoid some problems
13658 with constant folding. (E.g. suppose the lower bound is 1,
13659 and its mode is QI. Without the conversion,l (ARRAY
13660 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13661 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13667 }
13669 scalar_int_mode char_mode;
13681 }
13683 }
13685 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13686 an integer constant, real, or fixed-point constant.
13688 TYPE is the type of the result. */
13690 static tree
13692 {
13696 {
13698 {
13705 }
13712 {
13713 FIXED_VALUE_TYPE f;
13718 /* Propagate overflow flags. */
13722 }
13726 }
13729 }
13731 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13732 an integer constant or real constant.
13734 TYPE is the type of the result. */
13736 tree
13738 {
13742 {
13744 {
13745 /* If the value is unsigned or non-negative, then the absolute value
13746 is the same as the ordinary value. */
13750 /* If the value is negative, then the absolute value is
13751 its negation. */
13752 else
13753 {
13758 }
13759 }
13765 else
13771 }
13774 }
13776 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13777 constant. TYPE is the type of the result. */
13779 static tree
13781 {
13785 }
13787 /* Given CODE, a relational operator, the target type, TYPE and two
13788 constant operands OP0 and OP1, return the result of the
13789 relational operation. If the result is not a compile time
13790 constant, then return NULL_TREE. */
13792 static tree
13794 {
13797 /* From here on, the only cases we handle are when the result is
13798 known to be a constant. */
13801 {
13805 /* Handle the cases where either operand is a NaN. */
13807 {
13809 {
13837 }
13840 }
13843 }
13846 {
13850 }
13852 /* Handle equality/inequality of complex constants. */
13854 {
13865 else
13867 }
13870 {
13872 {
13873 /* Have vector comparison with scalar boolean result. */
13877 {
13885 }
13887 }
13894 {
13906 }
13909 }
13911 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13913 To compute GT, swap the arguments and do LT.
13914 To compute GE, do LT and invert the result.
13915 To compute LE, swap the arguments, do LT and invert the result.
13916 To compute NE, do EQ and invert the result.
13918 Therefore, the code below must handle only EQ and LT. */
13921 {
13924 }
13926 /* Note that it is safe to invert for real values here because we
13927 have already handled the one case that it matters. */
13931 {
13934 }
13936 /* Compute a result for LT or EQ if args permit;
13937 Otherwise return T. */
13939 {
13942 else
13944 }
13945 else
13951 }
13953 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13954 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13955 itself. */
13957 tree
13959 {
13960 /* If the expression does not have side effects then we don't have to wrap
13961 it with a cleanup point expression. */
13965 /* If the expression is a return, check to see if the expression inside the
13966 return has no side effects or the right hand side of the modify expression
13967 inside the return. If either don't have side effects set we don't need to
13968 wrap the expression in a cleanup point expression. Note we don't check the
13969 left hand side of the modify because it should always be a return decl. */
13971 {
13978 }
13981 }
13983 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13984 of an indirection through OP0, or NULL_TREE if no simplification is
13985 possible. */
13987 tree
13989 {
13991 tree subtype;
14000 {
14003 /* *&CONST_DECL -> to the value of the const decl. */
14006 /* *&p => p; make sure to handle *&"str"[cst] here. */
14008 {
14012 else
14014 }
14015 /* *(foo *)&fooarray => fooarray[0] */
14018 && (!in_gimple_form
14020 {
14030 }
14031 /* *(foo *)&complexfoo => __real__ complexfoo */
14035 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14038 {
14042 }
14043 }
14047 {
14053 {
14054 tree op00type;
14058 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14061 {
14063 unsigned HOST_WIDE_INT max_offset
14068 {
14075 }
14076 }
14077 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14080 {
14084 }
14085 /* ((foo *)&fooarray)[1] => fooarray[1] */
14088 {
14095 offset_int remainder;
14098 {
14103 }
14104 }
14105 }
14106 }
14108 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14111 && (!in_gimple_form
14113 {
14114 tree type_domain;
14124 NULL_TREE);
14125 }
14128 }
14130 /* Builds an expression for an indirection through T, simplifying some
14131 cases. */
14133 tree
14135 {
14143 }
14145 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14147 tree
14149 {
14154 else
14156 }
14158 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14159 whose result is ignored. The type of the returned tree need not be
14160 the same as the original expression. */
14162 tree
14164 {
14170 {
14181 else
14187 {
14203 }
14208 }
14209 }
14211 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14213 tree
14215 {
14221 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14222 have to do anything. Only do this when we are not given a const,
14223 because in that case, this check is more expensive than just
14224 doing it. */
14226 {
14231 }
14233 /* If divisor is a power of two, simplify this to bit manipulation. */
14235 {
14237 {
14251 }
14252 else
14253 {
14254 tree t;
14260 }
14261 }
14262 else
14263 {
14268 }
14271 }
14273 /* Likewise, but round down. */
14275 tree
14277 {
14284 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14285 have to do anything. Only do this when we are not given a const,
14286 because in that case, this check is more expensive than just
14287 doing it. */
14289 {
14294 }
14296 /* If divisor is a power of two, simplify this to bit manipulation. */
14298 {
14299 tree t;
14303 }
14304 else
14305 {
14310 }
14313 }
14315 /* Returns the pointer to the base of the object addressed by EXP and
14316 extracts the information about the offset of the access, storing it
14317 to PBITPOS and POFFSET. */
14319 static tree
14322 {
14323 tree core;
14324 machine_mode mode;
14326 HOST_WIDE_INT bitsize;
14330 {
14335 }
14337 {
14343 {
14348 {
14351 }
14352 }
14353 }
14354 else
14355 {
14359 }
14362 }
14364 /* Returns true if addresses of E1 and E2 differ by a constant, false
14365 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14367 bool
14369 {
14383 {
14393 }
14395 {
14396 /* If only one of the offsets is non-constant, the difference cannot
14397 be a constant. */
14399 }
14400 else
14405 }
14407 /* Return OFF converted to a pointer offset type suitable as offset for
14408 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14409 tree
14411 {
14413 }
14415 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14416 tree
14418 {
14421 }
14423 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14424 tree
14426 {
14429 }
14431 /* Return a char pointer for a C string if it is a string constant
14432 or sum of string constant and integer constant. We only support
14433 string constants properly terminated with '\0' character.
14434 If STRLEN is a valid pointer, length (including terminating character)
14435 of returned string is stored to the argument. */
14439 {
14440 tree offset_node;
14451 {
14454 else
14456 }
14461 /* Support only properly null-terminated strings. */
14470 }
14472 #if CHECKING_P
14476 /* Helper functions for writing tests of folding trees. */
14478 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14480 static void
14482 tree constant)
14483 {
14485 }
14487 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14488 wrapping WRAPPED_EXPR. */
14490 static void
14492 tree wrapped_expr)
14493 {
14498 }
14500 /* Verify that various arithmetic binary operations are folded
14501 correctly. */
14503 static void
14505 {
14511 /* Addition. */
14512 /* 1 <-- (0 + 1) */
14514 one);
14516 one);
14518 /* (nonlvalue)x <-- (x + 0) */
14520 x);
14522 /* Subtraction. */
14523 /* 0 <-- (x - x) */
14525 zero);
14527 x);
14529 /* Multiplication. */
14530 /* 0 <-- (x * 0) */
14532 zero);
14534 /* (nonlvalue)x <-- (x * 1) */
14536 x);
14537 }
14539 /* Verify that various binary operations on vectors are folded
14540 correctly. */
14542 static void
14544 {
14550 /* Verify equality tests that return a scalar boolean result. */
14556 }
14558 /* Run all of the selftests within this file. */
14560 void
14562 {
14565 }