| blob | 0a5b168c3200168c04bc313eca53f56d313bf8f6 |
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 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a (negative) power of two. */
462 /* Fall through. */
477 /* In general we can't negate B in A / B, because if A is INT_MIN and
478 B is 1, we may turn this into INT_MIN / -1 which is undefined
479 and actually traps on some architectures. */
488 /* Negate -((double)float) as (double)(-float). */
490 {
494 }
498 /* Negate -f(x) as f(-x). */
504 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
506 {
510 }
515 }
517 }
519 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
520 simplification is possible.
521 If negate_expr_p would return true for T, NULL_TREE will never be
522 returned. */
524 static tree
526 {
528 tree tem;
531 {
532 /* Convert - (~A) to A + 1. */
558 {
563 }
567 {
572 {
576 }
579 }
602 {
603 /* -(A + B) -> (-B) - A. */
605 {
609 }
611 /* -(A + B) -> (-A) - B. */
613 {
617 }
618 }
622 /* - (A - B) -> B - A */
633 /* Fall through. */
637 {
646 }
658 /* In general we can't negate B in A / B, because if A is INT_MIN and
659 B is 1, we may turn this into INT_MIN / -1 which is undefined
660 and actually traps on some architectures. */
672 /* Convert -((double)float) into (double)(-float). */
674 {
678 }
682 /* Negate -f(x) as f(-x). */
685 {
691 }
695 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
697 {
700 {
707 }
708 }
713 }
716 }
718 /* A wrapper for fold_negate_expr_1. */
720 static tree
722 {
729 }
731 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
732 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
733 return NULL_TREE. */
735 static tree
737 {
739 location_t loc;
752 }
753 \f
754 /* Split a tree IN into a constant, literal and variable parts that could be
755 combined with CODE to make IN. "constant" means an expression with
756 TREE_CONSTANT but that isn't an actual constant. CODE must be a
757 commutative arithmetic operation. Store the constant part into *CONP,
758 the literal in *LITP and return the variable part. If a part isn't
759 present, set it to null. If the tree does not decompose in this way,
760 return the entire tree as the variable part and the other parts as null.
762 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
763 case, we negate an operand that was subtracted. Except if it is a
764 literal for which we use *MINUS_LITP instead.
766 If NEGATE_P is true, we are negating all of IN, again except a literal
767 for which we use *MINUS_LITP instead. If a variable part is of pointer
768 type, it is negated after converting to TYPE. This prevents us from
769 generating illegal MINUS pointer expression. LOC is the location of
770 the converted variable part.
772 If IN is itself a literal or constant, return it as appropriate.
774 Note that we do not guarantee that any of the three values will be the
775 same type as IN, but they will have the same signedness and mode. */
777 static tree
781 {
789 /* Strip any conversions that don't change the machine mode or signedness. */
798 /* We can associate addition and subtraction together (even
799 though the C standard doesn't say so) for integers because
800 the value is not affected. For reals, the value might be
801 affected, so we can't. */
807 {
813 /* First see if either of the operands is a literal, then a constant. */
826 /* If we haven't dealt with either operand, this is not a case we can
827 decompose. Otherwise, VAR is either of the ones remaining, if any. */
832 else
835 /* Now do any needed negations. */
842 }
847 {
848 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
849 when IN is constant. */
852 }
853 else
857 {
870 }
880 }
882 /* Re-associate trees split by the above function. T1 and T2 are
883 either expressions to associate or null. Return the new
884 expression, if any. LOC is the location of the new expression. If
885 we build an operation, do it in TYPE and with CODE. */
887 static tree
889 {
891 {
894 }
898 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
899 try to fold this since we will have infinite recursion. But do
900 deal with any NEGATE_EXPRs. */
904 {
906 {
919 }
921 {
924 }
928 }
932 }
933 \f
934 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
935 for use in int_const_binop, size_binop and size_diffop. */
937 static bool
939 {
946 {
955 }
960 }
963 /* Combine two integer constants ARG1 and ARG2 under operation CODE
964 to produce a new constant. Return NULL_TREE if we don't know how
965 to evaluate CODE at compile-time. */
967 static tree
970 {
971 wide_int res;
972 tree t;
980 {
996 {
1000 else
1002 }
1005 /* It's unclear from the C standard whether shifts can overflow.
1006 The following code ignores overflow; perhaps a C standard
1007 interpretation ruling is needed. */
1009 else
1016 {
1020 else
1022 }
1026 else
1105 }
1113 }
1115 tree
1117 {
1119 }
1121 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1122 constant. We assume ARG1 and ARG2 have the same data type, or at least
1123 are the same kind of constant and the same machine mode. Return zero if
1124 combining the constants is not allowed in the current operating mode. */
1126 static tree
1128 {
1129 /* Sanity check for the recursive cases. */
1137 {
1143 }
1146 {
1147 machine_mode mode;
1148 REAL_VALUE_TYPE d1;
1149 REAL_VALUE_TYPE d2;
1150 REAL_VALUE_TYPE value;
1151 REAL_VALUE_TYPE result;
1155 /* The following codes are handled by real_arithmetic. */
1157 {
1168 }
1176 /* Don't perform operation if we honor signaling NaNs and
1177 either operand is a signaling NaN. */
1183 /* Don't perform operation if it would raise a division
1184 by zero exception. */
1190 /* If either operand is a NaN, just return it. Otherwise, set up
1191 for floating-point trap; we return an overflow. */
1193 {
1194 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1195 is off. */
1199 }
1201 {
1202 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1203 is off. */
1207 }
1212 /* Don't constant fold this floating point operation if
1213 the result has overflowed and flag_trapping_math. */
1221 /* Don't constant fold this floating point operation if the
1222 result may dependent upon the run-time rounding mode and
1223 flag_rounding_math is set, or if GCC's software emulation
1224 is unable to accurately represent the result. */
1234 }
1237 {
1238 FIXED_VALUE_TYPE f1;
1239 FIXED_VALUE_TYPE f2;
1240 FIXED_VALUE_TYPE result;
1245 /* The following codes are handled by fixed_arithmetic. */
1247 {
1259 {
1266 }
1271 }
1278 /* Propagate overflow flags. */
1282 }
1285 {
1294 {
1305 mpc_mul);
1319 mpc_div);
1320 /* Fallthru. */
1326 {
1327 /* Keep this algorithm in sync with
1328 tree-complex.c:expand_complex_div_straight().
1330 Expand complex division to scalars, straightforward algorithm.
1331 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1332 t = br*br + bi*bi
1333 */
1334 tree magsquared
1338 tree t1
1342 tree t2
1349 }
1350 else
1351 {
1352 /* Keep this algorithm in sync with
1353 tree-complex.c:expand_complex_div_wide().
1355 Expand complex division to scalars, modified algorithm to minimize
1356 overflow with wide input ranges. */
1362 {
1363 /* In the TRUE branch, we compute
1364 ratio = br/bi;
1365 div = (br * ratio) + bi;
1366 tr = (ar * ratio) + ai;
1367 ti = (ai * ratio) - ar;
1368 tr = tr / div;
1369 ti = ti / div; */
1380 }
1381 else
1382 {
1383 /* In the FALSE branch, we compute
1384 ratio = d/c;
1385 divisor = (d * ratio) + c;
1386 tr = (b * ratio) + a;
1387 ti = b - (a * ratio);
1388 tr = tr / div;
1389 ti = ti / div; */
1401 }
1402 }
1407 }
1411 }
1415 {
1421 {
1427 /* It is possible that const_binop cannot handle the given
1428 code and return NULL_TREE */
1431 }
1434 }
1436 /* Shifts allow a scalar offset for a vector. */
1439 {
1445 {
1450 /* It is possible that const_binop cannot handle the given
1451 code and return NULL_TREE. */
1454 }
1457 }
1459 }
1461 /* Overload that adds a TYPE parameter to be able to dispatch
1462 to fold_relational_const. */
1464 tree
1466 {
1470 /* ??? Until we make the const_binop worker take the type of the
1471 result as argument put those cases that need it here. */
1473 {
1484 {
1500 {
1506 }
1509 }
1515 {
1540 {
1553 }
1556 }
1559 }
1564 /* Make sure type and arg0 have the same saturating flag. */
1569 }
1571 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1572 Return zero if computing the constants is not possible. */
1574 tree
1576 {
1577 /* Don't perform the operation, other than NEGATE and ABS, if
1578 flag_signaling_nans is on and the operand is a signaling NaN. */
1587 {
1588 CASE_CONVERT:
1595 /* If the source address is 0, and the source address space
1596 cannot have a valid object at 0, fold to dest type null. */
1607 {
1608 /* Can't call fold_negate_const directly here as that doesn't
1609 handle all cases and we might not be able to negate some
1610 constants. */
1615 }
1624 {
1628 }
1634 /* Perform BIT_NOT_EXPR on each element individually. */
1636 {
1638 tree elem;
1643 {
1649 }
1652 }
1674 {
1693 else
1697 {
1701 }
1704 }
1709 {
1723 {
1728 }
1731 {
1735 }
1738 }
1742 }
1745 }
1747 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1748 indicates which particular sizetype to create. */
1750 tree
1752 {
1754 }
1755 \f
1756 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1757 is a tree code. The type of the result is taken from the operands.
1758 Both must be equivalent integer types, ala int_binop_types_match_p.
1759 If the operands are constant, so is the result. */
1761 tree
1763 {
1772 /* Handle the special case of two integer constants faster. */
1774 {
1775 /* And some specific cases even faster than that. */
1777 {
1782 }
1784 {
1787 }
1789 {
1792 }
1794 /* Handle general case of two integer constants. For sizetype
1795 constant calculations we always want to know about overflow,
1796 even in the unsigned case. */
1798 }
1801 }
1803 /* Given two values, either both of sizetype or both of bitsizetype,
1804 compute the difference between the two values. Return the value
1805 in signed type corresponding to the type of the operands. */
1807 tree
1809 {
1811 tree ctype;
1816 /* If the type is already signed, just do the simple thing. */
1824 else
1827 /* If either operand is not a constant, do the conversions to the signed
1828 type and subtract. The hardware will do the right thing with any
1829 overflow in the subtraction. */
1835 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1836 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1837 overflow) and negate (which can't either). Special-case a result
1838 of zero while we're here. */
1844 else
1848 MINUS_EXPR,
1850 }
1851 \f
1852 /* A subroutine of fold_convert_const handling conversions of an
1853 INTEGER_CST to another integer type. */
1855 static tree
1857 {
1858 /* Given an integer constant, make new constant with new type,
1859 appropriately sign-extended or truncated. Use widest_int
1860 so that any extension is done according ARG1's type. */
1864 }
1866 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1867 to an integer type. */
1869 static tree
1871 {
1873 tree t;
1875 /* The following code implements the floating point to integer
1876 conversion rules required by the Java Language Specification,
1877 that IEEE NaNs are mapped to zero and values that overflow
1878 the target precision saturate, i.e. values greater than
1879 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1880 are mapped to INT_MIN. These semantics are allowed by the
1881 C and C++ standards that simply state that the behavior of
1882 FP-to-integer conversion is unspecified upon overflow. */
1884 wide_int val;
1885 REAL_VALUE_TYPE r;
1889 {
1896 }
1898 /* If R is NaN, return zero and show we have an overflow. */
1900 {
1903 }
1905 /* See if R is less than the lower bound or greater than the
1906 upper bound. */
1909 {
1913 {
1916 }
1917 }
1920 {
1923 {
1926 {
1929 }
1930 }
1931 }
1938 }
1940 /* A subroutine of fold_convert_const handling conversions of a
1941 FIXED_CST to an integer type. */
1943 static tree
1945 {
1946 tree t;
1950 /* Right shift FIXED_CST to temp by fbit. */
1954 {
1956 HOST_BITS_PER_DOUBLE_INT,
1959 /* Left shift temp to temp_trunc by fbit. */
1961 HOST_BITS_PER_DOUBLE_INT,
1963 }
1964 else
1965 {
1968 }
1970 /* If FIXED_CST is negative, we need to round the value toward 0.
1971 By checking if the fractional bits are not zero to add 1 to temp. */
1977 /* Given a fixed-point constant, make new constant with new type,
1978 appropriately sign-extended or truncated. */
1986 }
1988 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1989 to another floating point type. */
1991 static tree
1993 {
1994 REAL_VALUE_TYPE value;
1995 tree t;
1997 /* Don't perform the operation if flag_signaling_nans is on
1998 and the operand is a signaling NaN. */
2006 /* If converting an infinity or NAN to a representation that doesn't
2007 have one, set the overflow bit so that we can produce some kind of
2008 error message at the appropriate point if necessary. It's not the
2009 most user-friendly message, but it's better than nothing. */
2016 /* Regular overflow, conversion produced an infinity in a mode that
2017 can't represent them. */
2022 else
2025 }
2027 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2028 to a floating point type. */
2030 static tree
2032 {
2033 REAL_VALUE_TYPE value;
2034 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 see if ARG0 might have been made by
3369 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3371 When in doubt, return 0. */
3373 static int
3375 {
3387 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3388 and see if the inner values are the same. This removes any
3389 signedness comparison, which doesn't matter here. */
3396 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3397 actual comparison operand, ARG0.
3399 First throw away any conversions to wider types
3400 already present in the operands. */
3409 {
3412 /* Make sure shorter operand is extended the right way
3413 to match the longer operand. */
3419 }
3422 }
3423 \f
3424 /* See if ARG is an expression that is either a comparison or is performing
3425 arithmetic on comparisons. The comparisons must only be comparing
3426 two different values, which will be stored in *CVAL1 and *CVAL2; if
3427 they are nonzero it means that some operands have already been found.
3428 No variables may be used anywhere else in the expression except in the
3429 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3430 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3432 If this is true, return 1. Otherwise, return zero. */
3434 static int
3436 {
3440 /* We can handle some of the tcc_expression cases here. */
3450 {
3451 /* If we've already found a CVAL1 or CVAL2, this expression is
3452 two complex to handle. */
3458 }
3461 {
3484 /* First see if we can handle the first operand, then the second. For
3485 the second operand, we know *CVAL1 can't be zero. It must be that
3486 one side of the comparison is each of the values; test for the
3487 case where this isn't true by failing if the two operands
3488 are the same. */
3497 ;
3501 ;
3502 else
3506 ;
3510 ;
3511 else
3518 }
3519 }
3520 \f
3521 /* ARG is a tree that is known to contain just arithmetic operations and
3522 comparisons. Evaluate the operations in the tree substituting NEW0 for
3523 any occurrence of OLD0 as an operand of a comparison and likewise for
3524 NEW1 and OLD1. */
3526 static tree
3529 {
3534 /* We can handle some of the tcc_expression cases here. */
3542 {
3557 {
3576 }
3577 /* Fall through - ??? */
3580 {
3584 /* We need to check both for exact equality and tree equality. The
3585 former will be true if the operand has a side-effect. In that
3586 case, we know the operand occurred exactly once. */
3599 }
3603 }
3604 }
3605 \f
3606 /* Return a tree for the case when the result of an expression is RESULT
3607 converted to TYPE and OMITTED was previously an operand of the expression
3608 but is now not needed (e.g., we folded OMITTED * 0).
3610 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3611 the conversion of RESULT to TYPE. */
3613 tree
3615 {
3618 /* If the resulting operand is an empty statement, just return the omitted
3619 statement casted to void. */
3629 }
3631 /* Return a tree for the case when the result of an expression is RESULT
3632 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3633 of the expression but are now not needed.
3635 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3636 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3637 evaluated before OMITTED2. Otherwise, if neither has side effects,
3638 just do the conversion of RESULT to TYPE. */
3640 tree
3643 {
3652 }
3654 \f
3655 /* Return a simplified tree node for the truth-negation of ARG. This
3656 never alters ARG itself. We assume that ARG is an operation that
3657 returns a truth value (0 or 1).
3659 FIXME: one would think we would fold the result, but it causes
3660 problems with the dominator optimizer. */
3662 static tree
3664 {
3669 /* If this is a comparison, we can simply invert it, except for
3670 floating-point non-equality comparisons, in which case we just
3671 enclose a TRUTH_NOT_EXPR around what we have. */
3674 {
3677 && flag_trapping_math
3691 }
3694 {
3713 /* Here we can invert either operand. We invert the first operand
3714 unless the second operand is a TRUTH_NOT_EXPR in which case our
3715 result is the XOR of the first operand with the inside of the
3716 negation of the second operand. */
3721 else
3744 {
3751 /* A COND_EXPR may have a throw as one operand, which
3752 then has void type. Just leave void operands
3753 as they are. */
3759 }
3771 CASE_CONVERT:
3775 /* fall through */
3797 }
3798 }
3800 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3801 assume that ARG is an operation that returns a truth value (0 or 1
3802 for scalars, 0 or -1 for vectors). Return the folded expression if
3803 folding is successful. Otherwise, return NULL_TREE. */
3805 static tree
3807 {
3810 ? BIT_NOT_EXPR
3813 }
3815 /* Return a simplified tree node for the truth-negation of ARG. This
3816 never alters ARG itself. We assume that ARG is an operation that
3817 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3819 tree
3821 {
3827 ? BIT_NOT_EXPR
3830 }
3832 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3833 with code CODE. This optimization is unsafe. */
3834 static tree
3837 {
3841 /* (A / C) +- (B / C) -> (A +- B) / C. */
3851 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3856 {
3868 }
3871 }
3872 \f
3873 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3874 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3875 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3876 is the original memory reference used to preserve the alias set of
3877 the access. */
3879 static tree
3883 {
3886 /* Attempt not to lose the access path if possible. */
3888 {
3890 machine_mode nmode;
3892 tree noffset;
3902 && !reversep
3903 && !nreversep
3905 {
3908 }
3909 }
3918 {
3925 }
3940 }
3942 /* Optimize a bit-field compare.
3944 There are two cases: First is a compare against a constant and the
3945 second is a comparison of two items where the fields are at the same
3946 bit position relative to the start of a chunk (byte, halfword, word)
3947 large enough to contain it. In these cases we can avoid the shift
3948 implicit in bitfield extractions.
3950 For constants, we emit a compare of the shifted constant with the
3951 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3952 compared. For two fields at the same position, we do the ANDs with the
3953 similar mask and compare the result of the ANDs.
3955 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3956 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3957 are the left and right operands of the comparison, respectively.
3959 If the optimization described above can be done, we return the resulting
3960 tree. Otherwise we return zero. */
3962 static tree
3965 {
3968 tree unsigned_type;
3975 tree mask;
3976 tree offset;
3978 /* Get all the information about the extractions being done. If the bit size
3979 if the same as the size of the underlying object, we aren't doing an
3980 extraction at all and so can do nothing. We also don't want to
3981 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3982 then will no longer be able to replace it. */
3991 else
3992 {
3993 /* If this is not a constant, we can only do something if bit positions,
3994 sizes, signedness and storage order are the same. */
3995 rinner
4003 }
4005 /* Honor the C++ memory model and mimic what RTL expansion does. */
4009 {
4013 }
4015 /* See if we can find a mode to refer to this field. We should be able to,
4016 but fail if we can't. */
4025 /* Set signed and unsigned types of the precision of this mode for the
4026 shifts below. */
4029 /* Compute the bit position and size for the new reference and our offset
4030 within it. If the new reference is the same size as the original, we
4031 won't optimize anything, so return zero. */
4041 /* Make the mask to be used against the extracted field. */
4048 /* If not comparing with constant, just rework the comparison
4049 and return. */
4053 unsigned_type,
4056 mask),
4059 unsigned_type,
4062 mask));
4064 /* Otherwise, we are handling the constant case. See if the constant is too
4065 big for the field. Warn and return a tree for 0 (false) if so. We do
4066 this not only for its own sake, but to avoid having to test for this
4067 error case below. If we didn't, we might generate wrong code.
4069 For unsigned fields, the constant shifted right by the field length should
4070 be all zero. For signed fields, the high-order bits should agree with
4071 the sign bit. */
4074 {
4076 {
4080 }
4081 }
4082 else
4083 {
4086 {
4090 }
4091 }
4093 /* Single-bit compares should always be against zero. */
4095 {
4098 }
4100 /* Make a new bitfield reference, shift the constant over the
4101 appropriate number of bits and mask it with the computed mask
4102 (in case this was a signed field). If we changed it, make a new one. */
4110 mask);
4115 }
4116 \f
4117 /* Subroutine for fold_truth_andor_1: decode a field reference.
4119 If EXP is a comparison reference, we return the innermost reference.
4121 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4122 set to the starting bit number.
4124 If the innermost field can be completely contained in a mode-sized
4125 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4127 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4128 otherwise it is not changed.
4130 *PUNSIGNEDP is set to the signedness of the field.
4132 *PREVERSEP is set to the storage order of the field.
4134 *PMASK is set to the mask used. This is either contained in a
4135 BIT_AND_EXPR or derived from the width of the field.
4137 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4139 Return 0 if this is not a component reference or is one that we can't
4140 do anything with. */
4142 static tree
4147 {
4152 tree unsigned_type;
4155 /* All the optimizations using this function assume integer fields.
4156 There are problems with FP fields since the type_for_size call
4157 below can fail for, e.g., XFmode. */
4161 /* We are interested in the bare arrangement of bits, so strip everything
4162 that doesn't affect the machine mode. However, record the type of the
4163 outermost expression if it may matter below. */
4170 {
4176 }
4183 /* Reject out-of-bound accesses (PR79731). */
4191 /* If the number of bits in the reference is the same as the bitsize of
4192 the outer type, then the outer type gives the signedness. Otherwise
4193 (in case of a small bitfield) the signedness is unchanged. */
4197 /* Compute the mask to access the bitfield. */
4206 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4214 }
4216 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4217 bit positions and MASK is SIGNED. */
4219 static int
4221 {
4225 /* If this function returns true when the type of the mask is
4226 UNSIGNED, then there will be errors. In particular see
4227 gcc.c-torture/execute/990326-1.c. There does not appear to be
4228 any documentation paper trail as to why this is so. But the pre
4229 wide-int worked with that restriction and it has been preserved
4230 here. */
4235 }
4237 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4238 represents the sign bit of EXP's type. If EXP represents a sign
4239 or zero extension, also test VAL against the unextended type.
4240 The return value is the (sub)expression whose sign bit is VAL,
4241 or NULL_TREE otherwise. */
4243 tree
4245 {
4247 tree t;
4249 /* Tree EXP must have an integral type. */
4254 /* Tree VAL must be an integer constant. */
4263 /* Handle extension from a narrower type. */
4269 }
4271 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4272 to be evaluated unconditionally. */
4274 static int
4276 {
4277 /* Strip any conversions that don't change the machine mode. */
4286 /* Don't regard global variables as simple. They may be
4287 allocated in ways unknown to the compiler (shared memory,
4288 #pragma weak, etc). */
4291 /* Weakrefs are not safe to be read, since they can be NULL.
4292 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4293 have DECL_WEAK flag set. */
4295 /* Loading a static variable is unduly expensive, but global
4296 registers aren't expensive. */
4298 }
4300 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4301 to be evaluated unconditionally.
4302 I addition to simple_operand_p, we assume that comparisons, conversions,
4303 and logic-not operations are simple, if their operands are simple, too. */
4305 static bool
4307 {
4327 }
4329 \f
4330 /* The following functions are subroutines to fold_range_test and allow it to
4331 try to change a logical combination of comparisons into a range test.
4333 For example, both
4334 X == 2 || X == 3 || X == 4 || X == 5
4335 and
4336 X >= 2 && X <= 5
4337 are converted to
4338 (unsigned) (X - 2) <= 3
4340 We describe each set of comparisons as being either inside or outside
4341 a range, using a variable named like IN_P, and then describe the
4342 range with a lower and upper bound. If one of the bounds is omitted,
4343 it represents either the highest or lowest value of the type.
4345 In the comments below, we represent a range by two numbers in brackets
4346 preceded by a "+" to designate being inside that range, or a "-" to
4347 designate being outside that range, so the condition can be inverted by
4348 flipping the prefix. An omitted bound is represented by a "-". For
4349 example, "- [-, 10]" means being outside the range starting at the lowest
4350 possible value and ending at 10, in other words, being greater than 10.
4351 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4352 always false.
4354 We set up things so that the missing bounds are handled in a consistent
4355 manner so neither a missing bound nor "true" and "false" need to be
4356 handled using a special case. */
4358 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4359 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4360 and UPPER1_P are nonzero if the respective argument is an upper bound
4361 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4362 must be specified for a comparison. ARG1 will be converted to ARG0's
4363 type if both are specified. */
4365 static tree
4368 {
4369 tree tem;
4373 /* If neither arg represents infinity, do the normal operation.
4374 Else, if not a comparison, return infinity. Else handle the special
4375 comparison rules. Note that most of the cases below won't occur, but
4376 are handled for consistency. */
4379 {
4384 }
4389 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4390 for neither. In real maths, we cannot assume open ended ranges are
4391 the same. But, this is computer arithmetic, where numbers are finite.
4392 We can therefore make the transformation of any unbounded range with
4393 the value Z, Z being greater than any representable number. This permits
4394 us to treat unbounded ranges as equal. */
4398 {
4419 }
4422 }
4423 \f
4424 /* Helper routine for make_range. Perform one step for it, return
4425 new expression if the loop should continue or NULL_TREE if it should
4426 stop. */
4428 tree
4432 {
4438 {
4440 /* We can only do something if the range is testing for zero. */
4449 /* We can only do something if the range is testing for zero
4450 and if the second operand is an integer constant. Note that
4451 saying something is "in" the range we make is done by
4452 complementing IN_P since it will set in the initial case of
4453 being not equal to zero; "out" is leaving it alone. */
4460 {
4481 }
4483 /* If this is an unsigned comparison, we also know that EXP is
4484 greater than or equal to zero. We base the range tests we make
4485 on that fact, so we record it here so we can parse existing
4486 range tests. We test arg0_type since often the return type
4487 of, e.g. EQ_EXPR, is boolean. */
4489 {
4493 NULL_TREE))
4498 /* If the high bound is missing, but we have a nonzero low
4499 bound, reverse the range so it goes from zero to the low bound
4500 minus 1. */
4502 {
4507 }
4508 }
4516 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4517 low and high are non-NULL, then normalize will DTRT. */
4520 {
4525 }
4527 /* (-x) IN [a,b] -> x in [-b, -a] */
4539 /* ~ X -> -X - 1 */
4548 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4549 move a constant to the other side. */
4554 /* If EXP is signed, any overflow in the computation is undefined,
4555 so we don't worry about it so long as our computations on
4556 the bounds don't overflow. For unsigned, overflow is defined
4557 and this is exactly the right thing. */
4569 normalize:
4570 /* Check for an unsigned range which has wrapped around the maximum
4571 value thus making n_high < n_low, and normalize it. */
4573 {
4579 /* If the range is of the form +/- [ x+1, x ], we won't
4580 be able to normalize it. But then, it represents the
4581 whole range or the empty set, so make it
4582 +/- [ -, - ]. */
4586 else
4588 }
4589 else
4597 CASE_CONVERT:
4615 /* If we're converting arg0 from an unsigned type, to exp,
4616 a signed type, we will be doing the comparison as unsigned.
4617 The tests above have already verified that LOW and HIGH
4618 are both positive.
4620 So we have to ensure that we will handle large unsigned
4621 values the same way that the current signed bounds treat
4622 negative values. */
4625 {
4626 tree high_positive;
4627 tree equiv_type;
4628 /* For fixed-point modes, we need to pass the saturating flag
4629 as the 2nd parameter. */
4631 equiv_type
4634 else
4635 equiv_type
4638 /* A range without an upper bound is, naturally, unbounded.
4639 Since convert would have cropped a very large value, use
4640 the max value for the destination type. */
4641 high_positive
4648 high_positive),
4651 /* If the low bound is specified, "and" the range with the
4652 range for which the original unsigned value will be
4653 positive. */
4655 {
4658 integer_zero_node),
4659 high_positive))
4663 }
4664 else
4665 {
4666 /* Otherwise, "or" the range with the range of the input
4667 that will be interpreted as negative. */
4670 integer_zero_node),
4671 high_positive))
4675 }
4676 }
4685 }
4686 }
4688 /* Given EXP, a logical expression, set the range it is testing into
4689 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4690 actually being tested. *PLOW and *PHIGH will be made of the same
4691 type as the returned expression. If EXP is not a comparison, we
4692 will most likely not be returning a useful value and range. Set
4693 *STRICT_OVERFLOW_P to true if the return value is only valid
4694 because signed overflow is undefined; otherwise, do not change
4695 *STRICT_OVERFLOW_P. */
4697 tree
4700 {
4708 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4709 and see if we can refine the range. Some of the cases below may not
4710 happen, but it doesn't seem worth worrying about this. We "continue"
4711 the outer loop when we've changed something; otherwise we "break"
4712 the switch, which will "break" the while. */
4718 {
4724 {
4732 }
4741 }
4743 /* If EXP is a constant, we can evaluate whether this is true or false. */
4745 {
4752 }
4756 }
4758 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4759 a bitwise check i.e. when
4760 LOW == 0xXX...X00...0
4761 HIGH == 0xXX...X11...1
4762 Return corresponding mask in MASK and stem in VALUE. */
4764 static bool
4767 {
4790 }
4791 \f
4792 /* Helper routine for build_range_check and match.pd. Return the type to
4793 perform the check or NULL if it shouldn't be optimized. */
4795 tree
4797 {
4798 /* First make sure that arithmetics in this type is valid, then make sure
4799 that it wraps around. */
4805 {
4808 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4809 for the type in question, as we rely on this here. */
4819 else
4821 }
4823 }
4825 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4826 type, TYPE, return an expression to test if EXP is in (or out of, depending
4827 on IN_P) the range. Return 0 if the test couldn't be created. */
4829 tree
4832 {
4835 /* Disable this optimization for function pointer expressions
4836 on targets that require function pointer canonicalization. */
4843 {
4849 }
4871 value);
4874 {
4876 {
4880 }
4882 }
4884 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4886 {
4890 {
4892 {
4895 etype
4897 else
4900 }
4903 }
4904 }
4906 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4907 This requires wrap-around arithmetics for the type of the expression. */
4927 }
4928 \f
4929 /* Return the predecessor of VAL in its type, handling the infinite case. */
4931 static tree
4933 {
4939 else
4942 }
4944 /* Return the successor of VAL in its type, handling the infinite case. */
4946 static tree
4948 {
4954 else
4957 }
4959 /* Given two ranges, see if we can merge them into one. Return 1 if we
4960 can, 0 if we can't. Set the output range into the specified parameters. */
4962 bool
4965 {
4969 tree tem;
4979 /* Make range 0 be the range that starts first, or ends last if they
4980 start at the same value. Swap them if it isn't. */
4983 || (lowequal
4986 {
4990 }
4992 /* Now flag two cases, whether the ranges are disjoint or whether the
4993 second range is totally subsumed in the first. Note that the tests
4994 below are simplified by the ones above. */
5000 /* We now have four cases, depending on whether we are including or
5001 excluding the two ranges. */
5003 {
5004 /* If they don't overlap, the result is false. If the second range
5005 is a subset it is the result. Otherwise, the range is from the start
5006 of the second to the end of the first. */
5011 else
5013 }
5016 {
5017 /* If they don't overlap, the result is the first range. If they are
5018 equal, the result is false. If the second range is a subset of the
5019 first, and the ranges begin at the same place, we go from just after
5020 the end of the second range to the end of the first. If the second
5021 range is not a subset of the first, or if it is a subset and both
5022 ranges end at the same place, the range starts at the start of the
5023 first range and ends just before the second range.
5024 Otherwise, we can't describe this as a single range. */
5030 {
5035 {
5036 /* We are in the weird situation where high0 > high1 but
5037 high1 has no successor. Punt. */
5039 }
5040 }
5042 {
5047 {
5048 /* low0 < low1 but low1 has no predecessor. Punt. */
5050 }
5051 }
5052 else
5054 }
5057 {
5058 /* If they don't overlap, the result is the second range. If the second
5059 is a subset of the first, the result is false. Otherwise,
5060 the range starts just after the first range and ends at the
5061 end of the second. */
5066 else
5067 {
5072 {
5073 /* high1 > high0 but high0 has no successor. Punt. */
5075 }
5076 }
5077 }
5079 else
5080 {
5081 /* The case where we are excluding both ranges. Here the complex case
5082 is if they don't overlap. In that case, the only time we have a
5083 range is if they are adjacent. If the second is a subset of the
5084 first, the result is the first. Otherwise, the range to exclude
5085 starts at the beginning of the first range and ends at the end of the
5086 second. */
5088 {
5093 else
5094 {
5095 /* Canonicalize - [min, x] into - [-, x]. */
5098 {
5103 /* FALLTHROUGH */
5116 }
5118 /* Canonicalize - [x, max] into - [x, -]. */
5121 {
5126 /* FALLTHROUGH */
5142 }
5144 /* The ranges might be also adjacent between the maximum and
5145 minimum values of the given type. For
5146 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5147 return + [x + 1, y - 1]. */
5149 {
5156 }
5157 else
5159 }
5160 }
5163 else
5165 }
5169 }
5170 \f
5172 /* Subroutine of fold, looking inside expressions of the form
5173 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5174 of the COND_EXPR. This function is being used also to optimize
5175 A op B ? C : A, by reversing the comparison first.
5177 Return a folded expression whose code is not a COND_EXPR
5178 anymore, or NULL_TREE if no folding opportunity is found. */
5180 static tree
5183 {
5188 tree tem;
5193 /* If we have A op 0 ? A : -A, consider applying the following
5194 transformations:
5196 A == 0? A : -A same as -A
5197 A != 0? A : -A same as A
5198 A >= 0? A : -A same as abs (A)
5199 A > 0? A : -A same as abs (A)
5200 A <= 0? A : -A same as -abs (A)
5201 A < 0? A : -A same as -abs (A)
5203 None of these transformations work for modes with signed
5204 zeros. If A is +/-0, the first two transformations will
5205 change the sign of the result (from +0 to -0, or vice
5206 versa). The last four will fix the sign of the result,
5207 even though the original expressions could be positive or
5208 negative, depending on the sign of A.
5210 Note that all these transformations are correct if A is
5211 NaN, since the two alternatives (A and -A) are also NaNs. */
5218 /* In the case that A is of the form X-Y, '-A' (arg2) may
5219 have already been folded to Y-X, check for that. */
5227 {
5239 /* Fall through. */
5250 /* FALLTHRU */
5260 }
5262 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5263 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5264 both transformations are correct when A is NaN: A != 0
5265 is then true, and A == 0 is false. */
5269 {
5274 }
5276 /* Try some transformations of A op B ? A : B.
5278 A == B? A : B same as B
5279 A != B? A : B same as A
5280 A >= B? A : B same as max (A, B)
5281 A > B? A : B same as max (B, A)
5282 A <= B? A : B same as min (A, B)
5283 A < B? A : B same as min (B, A)
5285 As above, these transformations don't work in the presence
5286 of signed zeros. For example, if A and B are zeros of
5287 opposite sign, the first two transformations will change
5288 the sign of the result. In the last four, the original
5289 expressions give different results for (A=+0, B=-0) and
5290 (A=-0, B=+0), but the transformed expressions do not.
5292 The first two transformations are correct if either A or B
5293 is a NaN. In the first transformation, the condition will
5294 be false, and B will indeed be chosen. In the case of the
5295 second transformation, the condition A != B will be true,
5296 and A will be chosen.
5298 The conversions to max() and min() are not correct if B is
5299 a number and A is not. The conditions in the original
5300 expressions will be false, so all four give B. The min()
5301 and max() versions would give a NaN instead. */
5304 /* Avoid these transformations if the COND_EXPR may be used
5305 as an lvalue in the C++ front-end. PR c++/19199. */
5306 && (in_gimple_form
5312 {
5318 {
5327 /* In C++ a ?: expression can be an lvalue, so put the
5328 operand which will be used if they are equal first
5329 so that we can convert this back to the
5330 corresponding COND_EXPR. */
5332 {
5340 }
5347 {
5355 }
5368 }
5369 }
5372 }
5375 \f
5376 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5377 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5378 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5379 false) >= 2)
5380 #endif
5382 /* EXP is some logical combination of boolean tests. See if we can
5383 merge it into some range test. Return the new tree if so. */
5385 static tree
5388 {
5404 /* If this is an OR operation, invert both sides; we will invert
5405 again at the end. */
5409 /* If both expressions are the same, if we can merge the ranges, and we
5410 can build the range test, return it or it inverted. If one of the
5411 ranges is always true or always false, consider it to be the same
5412 expression as the other. */
5420 {
5424 }
5426 /* On machines where the branch cost is expensive, if this is a
5427 short-circuited branch and the underlying object on both sides
5428 is the same, make a non-short-circuit operation. */
5434 {
5435 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5436 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5437 which cases we can't do this. */
5445 {
5454 {
5457 WARN_STRICT_OVERFLOW_COMPARISON);
5461 }
5462 }
5463 }
5466 }
5467 \f
5468 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5469 bit value. Arrange things so the extra bits will be set to zero if and
5470 only if C is signed-extended to its full width. If MASK is nonzero,
5471 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5473 static tree
5475 {
5478 tree temp;
5483 /* We work by getting just the sign bit into the low-order bit, then
5484 into the high-order bit, then sign-extend. We then XOR that value
5485 with C. */
5488 /* We must use a signed type in order to get an arithmetic right shift.
5489 However, we must also avoid introducing accidental overflows, so that
5490 a subsequent call to integer_zerop will work. Hence we must
5491 do the type conversion here. At this point, the constant is either
5492 zero or one, and the conversion to a signed type can never overflow.
5493 We could get an overflow if this conversion is done anywhere else. */
5502 /* If necessary, convert the type back to match the type of C. */
5507 }
5508 \f
5509 /* For an expression that has the form
5510 (A && B) || ~B
5511 or
5512 (A || B) && ~B,
5513 we can drop one of the inner expressions and simplify to
5514 A || ~B
5515 or
5516 A && ~B
5517 LOC is the location of the resulting expression. OP is the inner
5518 logical operation; the left-hand side in the examples above, while CMPOP
5519 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5520 removing a condition that guards another, as in
5521 (A != NULL && A->...) || A == NULL
5522 which we must not transform. If RHS_ONLY is true, only eliminate the
5523 right-most operand of the inner logical operation. */
5525 static tree
5528 {
5546 {
5549 {
5552 }
5553 }
5555 {
5558 {
5561 }
5562 }
5577 }
5579 /* Find ways of folding logical expressions of LHS and RHS:
5580 Try to merge two comparisons to the same innermost item.
5581 Look for range tests like "ch >= '0' && ch <= '9'".
5582 Look for combinations of simple terms on machines with expensive branches
5583 and evaluate the RHS unconditionally.
5585 For example, if we have p->a == 2 && p->b == 4 and we can make an
5586 object large enough to span both A and B, we can do this with a comparison
5587 against the object ANDed with the a mask.
5589 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5590 operations to do this with one comparison.
5592 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5593 function and the one above.
5595 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5596 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5598 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5599 two operands.
5601 We return the simplified tree or 0 if no optimization is possible. */
5603 static tree
5606 {
5607 /* If this is the "or" of two comparisons, we can do something if
5608 the comparisons are NE_EXPR. If this is the "and", we can do something
5609 if the comparisons are EQ_EXPR. I.e.,
5610 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5612 WANTED_CODE is this operation code. For single bit fields, we can
5613 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5614 comparison for one-bit fields. */
5635 /* Start by getting the comparison codes. Fail if anything is volatile.
5636 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5637 it were surrounded with a NE_EXPR. */
5646 {
5650 }
5653 {
5657 }
5668 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5671 {
5674 {
5679 }
5682 {
5688 }
5689 }
5694 /* If the RHS can be evaluated unconditionally and its operands are
5695 simple, it wins to evaluate the RHS unconditionally on machines
5696 with expensive branches. In this case, this isn't a comparison
5697 that can be merged. */
5704 {
5705 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5716 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5726 }
5728 /* See if the comparisons can be merged. Then get all the parameters for
5729 each side. */
5754 /* It must be true that the inner operation on the lhs of each
5755 comparison must be the same if we are to be able to do anything.
5756 Then see if we have constants. If not, the same must be true for
5757 the rhs's. */
5766 {
5769 }
5774 else
5777 /* If either comparison code is not correct for our logical operation,
5778 fail. However, we can convert a one-bit comparison against zero into
5779 the opposite comparison against that bit being set in the field. */
5783 {
5785 {
5786 /* Make the left operand unsigned, since we are only interested
5787 in the value of one bit. Otherwise we are doing the wrong
5788 thing below. */
5791 }
5792 else
5794 }
5796 /* This is analogous to the code for l_const above. */
5798 {
5800 {
5803 }
5804 else
5806 }
5808 /* See if we can find a mode that contains both fields being compared on
5809 the left. If we can't, fail. Otherwise, update all constants and masks
5810 to be relative to a field of that size. */
5815 volatilep);
5825 {
5828 }
5836 {
5843 {
5847 }
5848 }
5850 {
5857 {
5861 }
5862 }
5864 /* If the right sides are not constant, do the same for it. Also,
5865 disallow this optimization if a size or signedness mismatch occurs
5866 between the left and right sides. */
5868 {
5871 /* Make sure the two fields on the right
5872 correspond to the left without being swapped. */
5880 volatilep);
5890 {
5893 }
5902 /* Make a mask that corresponds to both fields being compared.
5903 Do this for both items being compared. If the operands are the
5904 same size and the bits being compared are in the same position
5905 then we can do this by masking both and comparing the masked
5906 results. */
5910 {
5924 }
5926 /* There is still another way we can do something: If both pairs of
5927 fields being compared are adjacent, we may be able to make a wider
5928 field containing them both.
5930 Note that we still must mask the lhs/rhs expressions. Furthermore,
5931 the mask must be shifted to account for the shift done by
5932 make_bit_field_ref. */
5937 {
5938 tree type;
5954 /* Convert to the smaller type before masking out unwanted bits. */
5957 {
5959 {
5963 }
5965 {
5969 }
5970 }
5979 }
5982 }
5984 /* Handle the case of comparisons with constants. If there is something in
5985 common between the masks, those bits of the constants must be the same.
5986 If not, the condition is always false. Test for this to avoid generating
5987 incorrect code below. */
5992 {
5994 {
5997 }
5998 else
5999 {
6002 }
6003 }
6005 /* Construct the expression we will return. First get the component
6006 reference we will make. Unless the mask is all ones the width of
6007 that field, perform the mask operation. Then compare with the
6008 merged constant. */
6019 }
6020 \f
6021 /* T is an integer expression that is being multiplied, divided, or taken a
6022 modulus (CODE says which and what kind of divide or modulus) by a
6023 constant C. See if we can eliminate that operation by folding it with
6024 other operations already in T. WIDE_TYPE, if non-null, is a type that
6025 should be used for the computation if wider than our type.
6027 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6028 (X * 2) + (Y * 4). We must, however, be assured that either the original
6029 expression would not overflow or that overflow is undefined for the type
6030 in the language in question.
6032 If we return a non-null expression, it is an equivalent form of the
6033 original computation, but need not be in the original type.
6035 We set *STRICT_OVERFLOW_P to true if the return values depends on
6036 signed overflow being undefined. Otherwise we do not change
6037 *STRICT_OVERFLOW_P. */
6039 static tree
6042 {
6043 /* To avoid exponential search depth, refuse to allow recursion past
6044 three levels. Beyond that (1) it's highly unlikely that we'll find
6045 something interesting and (2) we've probably processed it before
6046 when we built the inner expression. */
6049 tree ret;
6054 depth++;
6056 depth--;
6059 }
6061 static tree
6064 {
6075 /* Don't deal with constants of zero here; they confuse the code below. */
6085 /* Note that we need not handle conditional operations here since fold
6086 already handles those cases. So just do arithmetic here. */
6088 {
6090 /* For a constant, we can always simplify if we are a multiply
6091 or (for divide and modulus) if it is a multiple of our constant. */
6094 {
6097 /* If the multiplication overflowed, we lost information on it.
6098 See PR68142 and PR69845. */
6102 }
6106 /* If op0 is an expression ... */
6112 /* ... and has wrapping overflow, and its type is smaller
6113 than ctype, then we cannot pass through as widening. */
6118 /* ... or this is a truncation (t is narrower than op0),
6119 then we cannot pass through this narrowing. */
6122 /* ... or signedness changes for division or modulus,
6123 then we cannot pass through this conversion. */
6127 /* ... or has undefined overflow while the converted to
6128 type has not, we cannot do the operation in the inner type
6129 as that would introduce undefined overflow. */
6135 /* Pass the constant down and see if we can make a simplification. If
6136 we can, replace this expression with the inner simplification for
6137 possible later conversion to our or some other type. */
6142 code == MULT_EXPR
6144 strict_overflow_p))))
6149 /* If widening the type changes it from signed to unsigned, then we
6150 must avoid building ABS_EXPR itself as unsigned. */
6152 {
6156 {
6159 }
6161 }
6162 /* If the constant is negative, we cannot simplify this. */
6165 /* FALLTHROUGH */
6167 /* For division and modulus, type can't be unsigned, as e.g.
6168 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6169 For signed types, even with wrapping overflow, this is fine. */
6178 /* If widening the type changes the signedness, then we can't perform
6179 this optimization as that changes the result. */
6183 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6189 {
6196 }
6200 /* If the second operand is constant, this is a multiplication
6201 or floor division, by a power of two, so we can treat it that
6202 way unless the multiplier or divisor overflows. Signed
6203 left-shift overflow is implementation-defined rather than
6204 undefined in C90, so do not convert signed left shift into
6205 multiplication. */
6208 /* const_binop may not detect overflow correctly,
6209 so check for it explicitly here. */
6213 size_one_node,
6214 op1)))
6218 ctype,
6220 t1),
6225 /* See if we can eliminate the operation on both sides. If we can, we
6226 can return a new PLUS or MINUS. If we can't, the only remaining
6227 cases where we can do anything are if the second operand is a
6228 constant. */
6235 /* If not multiplication, we can only do this if both operands
6236 are divisible by c. */
6239 {
6244 }
6246 /* If this was a subtraction, negate OP1 and set it to be an addition.
6247 This simplifies the logic below. */
6249 {
6251 /* If OP1 was not easily negatable, the constant may be OP0. */
6253 {
6256 }
6257 }
6262 /* If either OP1 or C are negative, this optimization is not safe for
6263 some of the division and remainder types while for others we need
6264 to change the code. */
6266 {
6274 }
6276 /* If it's a multiply or a division/modulus operation of a multiple
6277 of our constant, do the operation and verify it doesn't overflow. */
6280 {
6283 /* We allow the constant to overflow with wrapping semantics. */
6287 }
6288 else
6291 /* If we have an unsigned type, we cannot widen the operation since it
6292 will change the result if the original computation overflowed. */
6296 /* The last case is if we are a multiply. In that case, we can
6297 apply the distributive law to commute the multiply and addition
6298 if the multiplication of the constants doesn't overflow
6299 and overflow is defined. With undefined overflow
6300 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6306 op1);
6311 /* We have a special case here if we are doing something like
6312 (C * 8) % 4 since we know that's zero. */
6315 /* If the multiplication can overflow we cannot optimize this. */
6319 {
6322 }
6324 /* ... fall through ... */
6328 /* If we can extract our operation from the LHS, do so and return a
6329 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6330 do something only if the second operand is a constant. */
6346 /* If these are the same operation types, we can associate them
6347 assuming no overflow. */
6349 {
6364 }
6366 /* If these operations "cancel" each other, we have the main
6367 optimizations of this pass, which occur when either constant is a
6368 multiple of the other, in which case we replace this with either an
6369 operation or CODE or TCODE.
6371 If we have an unsigned type, we cannot do this since it will change
6372 the result if the original computation overflowed. */
6379 {
6381 {
6388 }
6390 {
6397 }
6398 }
6403 }
6406 }
6407 \f
6408 /* Return a node which has the indicated constant VALUE (either 0 or
6409 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6410 and is of the indicated TYPE. */
6412 tree
6414 {
6423 else
6425 }
6428 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6429 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6430 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6431 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6432 COND is the first argument to CODE; otherwise (as in the example
6433 given here), it is the second argument. TYPE is the type of the
6434 original expression. Return NULL_TREE if no simplification is
6435 possible. */
6437 static tree
6442 {
6452 {
6456 /* If this operand throws an expression, then it does not make
6457 sense to try to perform a logical or arithmetic operation
6458 involving it. */
6463 }
6466 {
6471 }
6472 else
6473 /* Detect the case of mixing vector and scalar types - bail out. */
6479 /* This transformation is only worthwhile if we don't have to wrap ARG
6480 in a SAVE_EXPR and the operation can be simplified without recursing
6481 on at least one of the branches once its pushed inside the COND_EXPR. */
6490 {
6494 else
6496 }
6498 {
6502 else
6504 }
6506 /* Check that we have simplified at least one of the branches. */
6511 }
6513 \f
6514 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6516 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6517 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6518 ADDEND is the same as X.
6520 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6521 and finite. The problematic cases are when X is zero, and its mode
6522 has signed zeros. In the case of rounding towards -infinity,
6523 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6524 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6526 bool
6528 {
6532 /* Don't allow the fold with -fsignaling-nans. */
6536 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6540 /* In a vector or complex, we would need to check the sign of all zeros. */
6544 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6548 /* The mode has signed zeros, and we have to honor their sign.
6549 In this situation, there is only one case we can return true for.
6550 X - 0 is the same as X unless rounding towards -infinity is
6551 supported. */
6553 }
6555 /* Subroutine of match.pd that optimizes comparisons of a division by
6556 a nonzero integer constant against an integer constant, i.e.
6557 X/C1 op C2.
6559 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6560 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6562 enum tree_code
6565 {
6570 /* We have to do this the hard way to detect unsigned overflow.
6571 prod = int_const_binop (MULT_EXPR, c1, c2); */
6577 {
6581 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6584 }
6586 {
6589 {
6608 }
6609 }
6610 else
6611 {
6612 /* A negative divisor reverses the relational operators. */
6617 {
6636 }
6637 }
6650 }
6653 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6654 equality/inequality test, then return a simplified form of the test
6655 using a sign testing. Otherwise return NULL. TYPE is the desired
6656 result type. */
6658 static tree
6661 tree result_type)
6662 {
6663 /* If this is testing a single bit, we can optimize the test. */
6667 {
6668 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6669 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6673 /* This is only a win if casting to a signed type is cheap,
6674 i.e. when arg00's type is not a partial mode. */
6677 {
6680 result_type,
6683 }
6684 }
6687 }
6689 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6690 equality/inequality test, then return a simplified form of
6691 the test using shifts and logical operations. Otherwise return
6692 NULL. TYPE is the desired result type. */
6694 tree
6697 {
6698 /* If this is testing a single bit, we can optimize the test. */
6702 {
6711 /* First, see if we can fold the single bit test into a sign-bit
6712 test. */
6714 result_type);
6718 /* Otherwise we have (A & C) != 0 where C is a single bit,
6719 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6720 Similarly for (A & C) == 0. */
6722 /* If INNER is a right shift of a constant and it plus BITNUM does
6723 not overflow, adjust BITNUM and INNER. */
6729 {
6732 }
6734 /* If we are going to be able to omit the AND below, we must do our
6735 operations as unsigned. If we must use the AND, we have a choice.
6736 Normally unsigned is faster, but for some machines signed is. */
6754 /* Put the AND last so it can combine with more things. */
6757 /* Make sure to return the proper type. */
6761 }
6763 }
6765 /* Test whether it is preferable two swap two operands, ARG0 and
6766 ARG1, for example because ARG0 is an integer constant and ARG1
6767 isn't. */
6769 bool
6771 {
6785 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6786 for commutative and comparison operators. Ensuring a canonical
6787 form allows the optimizers to find additional redundancies without
6788 having to explicitly check for both orderings. */
6794 /* Put SSA_NAMEs last. */
6800 /* Put variables last. */
6807 }
6810 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6811 means A >= Y && A != MAX, but in this case we know that
6812 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6814 static tree
6816 {
6823 else
6832 {
6835 }
6837 {
6840 }
6841 else
6848 {
6849 /* Convert the pointer types into integer before taking the difference. */
6853 }
6854 else
6861 }
6863 /* Fold a sum or difference of at least one multiplication.
6864 Returns the folded tree or NULL if no simplification could be made. */
6866 static tree
6869 {
6873 /* (A * C) +- (B * C) -> (A+-B) * C.
6874 (A * C) +- A -> A * (C+-1).
6875 We are most concerned about the case where C is a constant,
6876 but other combinations show up during loop reduction. Since
6877 it is not difficult, try all four possibilities. */
6880 {
6883 }
6885 {
6888 }
6889 else
6890 {
6891 /* We cannot generate constant 1 for fract. */
6896 }
6898 {
6901 }
6903 {
6905 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6906 the purpose of this canonicalization. */
6910 {
6913 }
6914 else
6916 }
6917 else
6918 {
6919 /* We cannot generate constant 1 for fract. */
6924 }
6927 /* Prefer factoring a common non-constant. */
6937 /* No identical multiplicands; see if we can find a common
6938 power-of-two factor in non-power-of-two multiplies. This
6939 can help in multi-dimensional array access. */
6942 {
6945 tree maybe_same;
6949 /* Move min of absolute values to int11. */
6951 {
6956 }
6957 else
6961 /* The remainder should not be a constant, otherwise we
6962 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6963 increased the number of multiplications necessary. */
6965 {
6973 }
6974 }
6981 /* We are neither factoring zero nor minus one. */
6989 /* Same may be zero and thus the operation 'code' may overflow. Likewise
6990 same may be minus one and thus the multiplication may overflow. Perform
6991 the operations in an unsigned type. */
6996 /* If the sum evaluated to a constant that is not -INF the multiplication
6997 cannot overflow. */
7006 }
7008 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7009 specified by EXPR into the buffer PTR of length LEN bytes.
7010 Return the number of bytes placed in the buffer, or zero
7011 upon failure. */
7013 static int
7015 {
7029 {
7031 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7032 number of bytes. */
7036 {
7043 else
7045 }
7046 else
7051 }
7053 }
7056 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7057 specified by EXPR into the buffer PTR of length LEN bytes.
7058 Return the number of bytes placed in the buffer, or zero
7059 upon failure. */
7061 static int
7063 {
7067 FIXED_VALUE_TYPE value;
7083 }
7086 /* Subroutine of native_encode_expr. Encode the REAL_CST
7087 specified by EXPR into the buffer PTR of length LEN bytes.
7088 Return the number of bytes placed in the buffer, or zero
7089 upon failure. */
7091 static int
7093 {
7099 /* There are always 32 bits in each long, no matter the size of
7100 the hosts long. We handle floating point representations with
7101 up to 192 bits. */
7115 {
7120 {
7127 else
7129 }
7130 else
7131 {
7134 {
7135 /* Reverse bytes within each long, or within the entire float
7136 if it's smaller than a long (for HFmode). */
7139 }
7140 }
7145 }
7147 }
7149 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7150 specified by EXPR into the buffer PTR of length LEN bytes.
7151 Return the number of bytes placed in the buffer, or zero
7152 upon failure. */
7154 static int
7156 {
7158 tree part;
7173 }
7176 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7177 specified by EXPR into the buffer PTR of length LEN bytes.
7178 Return the number of bytes placed in the buffer, or zero
7179 upon failure. */
7181 static int
7183 {
7193 {
7195 {
7198 }
7209 }
7211 }
7214 /* Subroutine of native_encode_expr. Encode the STRING_CST
7215 specified by EXPR into the buffer PTR of length LEN bytes.
7216 Return the number of bytes placed in the buffer, or zero
7217 upon failure. */
7219 static int
7221 {
7223 HOST_WIDE_INT total_bytes;
7237 {
7240 {
7243 }
7246 }
7247 else
7250 }
7253 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7254 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7255 buffer PTR of length LEN bytes. If OFF is not -1 then start
7256 the encoding at byte offset OFF and encode at most LEN bytes.
7257 Return the number of bytes placed in the buffer, or zero upon failure. */
7259 int
7261 {
7262 /* We don't support starting at negative offset and -1 is special. */
7267 {
7288 }
7289 }
7292 /* Subroutine of native_interpret_expr. Interpret the contents of
7293 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7294 If the buffer cannot be interpreted, return NULL_TREE. */
7296 static tree
7298 {
7308 }
7311 /* Subroutine of native_interpret_expr. Interpret the contents of
7312 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7313 If the buffer cannot be interpreted, return NULL_TREE. */
7315 static tree
7317 {
7319 double_int result;
7320 FIXED_VALUE_TYPE fixed_value;
7330 }
7333 /* Subroutine of native_interpret_expr. Interpret the contents of
7334 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7335 If the buffer cannot be interpreted, return NULL_TREE. */
7337 static tree
7339 {
7343 /* There are always 32 bits in each long, no matter the size of
7344 the hosts long. We handle floating point representations with
7345 up to 192 bits. */
7346 REAL_VALUE_TYPE r;
7357 {
7358 /* Both OFFSET and BYTE index within a long;
7359 bitpos indexes the whole float. */
7362 {
7369 else
7371 }
7372 else
7373 {
7376 {
7377 /* Reverse bytes within each long, or within the entire float
7378 if it's smaller than a long (for HFmode). */
7381 }
7382 }
7386 }
7390 }
7393 /* Subroutine of native_interpret_expr. Interpret the contents of
7394 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7395 If the buffer cannot be interpreted, return NULL_TREE. */
7397 static tree
7399 {
7414 }
7417 /* Subroutine of native_interpret_expr. Interpret the contents of
7418 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7419 If the buffer cannot be interpreted, return NULL_TREE. */
7421 static tree
7423 {
7436 {
7441 }
7443 }
7446 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7447 the buffer PTR of length LEN as a constant of type TYPE. For
7448 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7449 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7450 return NULL_TREE. */
7452 tree
7454 {
7456 {
7478 }
7479 }
7481 /* Returns true if we can interpret the contents of a native encoding
7482 as TYPE. */
7484 static bool
7486 {
7488 {
7501 }
7502 }
7504 /* Return true iff a constant of type TYPE is accepted by
7505 native_encode_expr. */
7507 bool
7509 {
7511 {
7521 }
7522 }
7524 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7525 TYPE at compile-time. If we're unable to perform the conversion
7526 return NULL_TREE. */
7528 static tree
7530 {
7531 /* We support up to 512-bit values (for V8DFmode). */
7535 /* Check that the host and target are sane. */
7544 }
7546 /* Build an expression for the address of T. Folds away INDIRECT_REF
7547 to avoid confusing the gimplify process. */
7549 tree
7551 {
7552 /* The size of the object is not relevant when talking about its address. */
7557 {
7562 }
7572 {
7577 }
7578 else
7582 }
7584 /* Build an expression for the address of T. */
7586 tree
7588 {
7592 }
7594 /* Fold a unary expression of code CODE and type TYPE with operand
7595 OP0. Return the folded expression if folding is successful.
7596 Otherwise, return NULL_TREE. */
7598 tree
7600 {
7601 tree tem;
7602 tree arg0;
7610 {
7613 {
7614 /* Don't use STRIP_NOPS, because signedness of argument type
7615 matters. */
7617 }
7618 else
7619 {
7620 /* Strip any conversions that don't change the mode. This
7621 is safe for every expression, except for a comparison
7622 expression because its signedness is derived from its
7623 operands.
7625 Note that this is done as an internal manipulation within
7626 the constant folder, in order to find the simplest
7627 representation of the arguments so that their form can be
7628 studied. In any cases, the appropriate type conversions
7629 should be put back in the tree that will get out of the
7630 constant folder. */
7632 }
7635 {
7638 {
7642 }
7643 }
7644 }
7651 {
7658 {
7672 /* If this was a conversion, and all we did was to move into
7673 inside the COND_EXPR, bring it back out. But leave it if
7674 it is a conversion from integer to integer and the
7675 result precision is no wider than a word since such a
7676 conversion is cheap and may be optimized away by combine,
7677 while it couldn't if it were outside the COND_EXPR. Then return
7678 so we don't get into an infinite recursion loop taking the
7679 conversion out and then back in. */
7691 && (INTEGRAL_TYPE_P
7704 }
7705 }
7708 {
7714 CASE_CONVERT:
7718 {
7719 /* If we have (type) (a CMP b) and type is an integral type, return
7720 new expression involving the new type. Canonicalize
7721 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7722 non-integral type.
7723 Do not fold the result as that would not simplify further, also
7724 folding again results in recursions. */
7734 }
7736 /* Handle (T *)&A.B.C for A being of type T and B and C
7737 living at offset zero. This occurs frequently in
7738 C++ upcasting and then accessing the base. */
7742 {
7744 tree offset;
7745 machine_mode mode;
7747 tree base
7751 /* If the reference was to a (constant) zero offset, we can use
7752 the address of the base if it has the same base type
7753 as the result type and the pointer type is unqualified. */
7760 }
7764 /* Detect assigning a bitfield. */
7766 && DECL_BIT_FIELD
7768 {
7769 /* Don't leave an assignment inside a conversion
7770 unless assigning a bitfield. */
7772 /* First do the assignment, then return converted constant. */
7777 }
7779 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7780 constants (if x has signed type, the sign bit cannot be set
7781 in c). This folds extension into the BIT_AND_EXPR.
7782 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7783 very likely don't have maximal range for their precision and this
7784 transformation effectively doesn't preserve non-maximal ranges. */
7788 {
7799 <= HOST_BITS_PER_WIDE_INT
7801 {
7805 cst &= HOST_WIDE_INT_M1U
7809 && !flag_syntax_only
7812 {
7816 }
7817 }
7819 {
7824 }
7825 }
7827 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7828 cast (T1)X will fold away. We assume that this happens when X itself
7829 is a cast. */
7833 {
7837 return fold_build_pointer_plus_loc
7839 }
7841 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7842 of the same precision, and X is an integer type not narrower than
7843 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7849 {
7855 }
7857 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7858 type of X and Y (integer types only). */
7863 {
7864 /* Be careful not to introduce new overflows. */
7865 tree mult_type;
7868 else
7872 {
7879 }
7880 }
7886 {
7893 }
7904 /* Convert fabs((double)float) into (double)fabsf(float). */
7907 {
7913 targ0));
7914 }
7918 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7937 /* Note that the operand of this must be an int
7938 and its values must be 0 or 1.
7939 ("true" is a fixed value perhaps depending on the language,
7940 but we don't handle values other than 1 correctly yet.) */
7947 /* Fold *&X to X if X is an lvalue. */
7949 {
7956 }
7962 }
7965 /* If the operation was a conversion do _not_ mark a resulting constant
7966 with TREE_OVERFLOW if the original constant was not. These conversions
7967 have implementation defined behavior and retaining the TREE_OVERFLOW
7968 flag here would confuse later passes such as VRP. */
7969 tree
7972 {
7981 }
7983 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7984 operands OP0 and OP1. LOC is the location of the resulting expression.
7985 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7986 Return the folded expression if folding is successful. Otherwise,
7987 return NULL_TREE. */
7988 static tree
7991 {
7992 tree tem;
7994 /* We only do these simplifications if we are optimizing. */
7998 /* Check for things like (A || B) && (A || C). We can convert this
7999 to A || (B && C). Note that either operator can be any of the four
8000 truth and/or operations and the transformation will still be
8001 valid. Also note that we only care about order for the
8002 ANDIF and ORIF operators. If B contains side effects, this
8003 might change the truth-value of A. */
8010 {
8030 /* This case if tricky because we must either have commutative
8031 operators or else A10 must not have side-effects. */
8037 a01);
8038 }
8040 /* See if we can build a range comparison. */
8046 {
8050 }
8054 {
8058 }
8060 /* Check for the possibility of merging component references. If our
8061 lhs is another similar operation, try to merge its rhs with our
8062 rhs. Then try to merge our lhs and rhs. */
8076 {
8083 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8084 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8085 We don't want to pack more than two leafs to a non-IF AND/OR
8086 expression.
8087 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8088 equal to IF-CODE, then we don't want to add right-hand operand.
8089 If the inner right-hand side of left-hand operand has
8090 side-effects, or isn't simple, then we can't add to it,
8091 as otherwise we might destroy if-sequence. */
8094 /* Needed for sequence points to handle trappings, and
8095 side-effects. */
8097 {
8099 arg1);
8101 tem);
8102 }
8103 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8104 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8107 /* Needed for sequence points to handle trappings, and
8108 side-effects. */
8110 {
8115 }
8116 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8117 into (A OR B).
8118 For sequence point consistancy, we need to check for trapping,
8119 and side-effects. */
8123 }
8126 }
8128 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8129 by changing CODE to reduce the magnitude of constants involved in
8130 ARG0 of the comparison.
8131 Returns a canonicalized comparison tree if a simplification was
8132 possible, otherwise returns NULL_TREE.
8133 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8134 valid if signed overflow is undefined. */
8136 static tree
8140 {
8145 /* Match A +- CST code arg1. We can change this only if overflow
8146 is undefined. */
8149 /* In principle pointers also have undefined overflow behavior,
8150 but that causes problems elsewhere. */
8157 /* Identify the constant in arg0 and its sign. */
8161 /* Overflowed constants and zero will cause problems. */
8166 /* See if we can reduce the magnitude of the constant in
8167 arg0 by changing the comparison code. */
8168 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8172 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8176 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8180 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8184 else
8188 /* Now build the constant reduced in magnitude. But not if that
8189 would produce one outside of its types range. */
8205 }
8207 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8208 overflow further. Try to decrease the magnitude of constants involved
8209 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8210 and put sole constants at the second argument position.
8211 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8213 static tree
8216 {
8217 tree t;
8222 /* Try canonicalization by simplifying arg0. */
8227 {
8231 }
8233 /* Try canonicalization by simplifying arg1 using the swapped
8234 comparison. */
8242 }
8244 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8245 space. This is used to avoid issuing overflow warnings for
8246 expressions like &p->x which can not wrap. */
8248 static bool
8250 {
8257 wide_int wi_offset;
8263 else
8279 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8280 array. */
8282 {
8283 HOST_WIDE_INT base_size;
8288 }
8291 }
8293 /* Return a positive integer when the symbol DECL is known to have
8294 a nonzero address, zero when it's known not to (e.g., it's a weak
8295 symbol), and a negative integer when the symbol is not yet in the
8296 symbol table and so whether or not its address is zero is unknown.
8297 For function local objects always return positive integer. */
8298 static int
8300 {
8305 /* Function local objects are never NULL. */
8313 }
8315 /* Subroutine of fold_binary. This routine performs all of the
8316 transformations that are common to the equality/inequality
8317 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8318 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8319 fold_binary should call fold_binary. Fold a comparison with
8320 tree code CODE and type TYPE with operands OP0 and OP1. Return
8321 the folded comparison or NULL_TREE. */
8323 static tree
8326 {
8336 /* For comparisons of pointers we can decompose it to a compile time
8337 comparison of the base objects and the offsets into the object.
8338 This requires at least one operand being an ADDR_EXPR or a
8339 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8345 {
8348 machine_mode mode;
8352 /* Get base and offset for the access. Strip ADDR_EXPR for
8353 get_inner_reference, but put it back by stripping INDIRECT_REF
8354 off the base object if possible. indirect_baseN will be true
8355 if baseN is not an address but refers to the object itself. */
8358 {
8359 base0
8365 else
8367 }
8369 {
8373 {
8374 base0
8380 else
8382 }
8385 else
8389 {
8395 {
8398 }
8399 }
8400 }
8404 {
8405 base1
8411 else
8413 }
8415 {
8419 {
8420 base1
8426 else
8428 }
8431 else
8435 {
8441 {
8444 }
8445 }
8446 }
8448 /* If we have equivalent bases we might be able to simplify. */
8452 {
8453 /* We can fold this expression to a constant if the non-constant
8454 offset parts are equal. */
8458 {
8464 "occur when comparing P +- C1 with "
8466 WARN_STRICT_OVERFLOW_CONDITIONAL);
8469 {
8483 }
8484 }
8485 /* We can simplify the comparison to a comparison of the variable
8486 offset parts if the constant offset parts are equal.
8487 Be careful to use signed sizetype here because otherwise we
8488 mess with array offsets in the wrong way. This is possible
8489 because pointer arithmetic is restricted to retain within an
8490 object and overflow on pointer differences is undefined as of
8491 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8493 {
8494 /* By converting to signed sizetype we cover middle-end pointer
8495 arithmetic which operates on unsigned pointer types of size
8496 type size and ARRAY_REF offsets which are properly sign or
8497 zero extended from their type in case it is narrower than
8498 sizetype. */
8501 else
8505 else
8512 "occur when comparing P +- C1 with "
8514 WARN_STRICT_OVERFLOW_COMPARISON);
8517 }
8518 }
8519 /* For equal offsets we can simplify to a comparison of the
8520 base addresses. */
8522 && (indirect_base0
8524 && (indirect_base1
8529 {
8535 }
8536 /* Comparison between an ordinary (non-weak) symbol and a null
8537 pointer can be eliminated since such symbols must have a non
8538 null address. In C, relational expressions between pointers
8539 to objects and null pointers are undefined. The results
8540 below follow the C++ rules with the additional property that
8541 every object pointer compares greater than a null pointer.
8542 */
8545 /* Avoid folding references to struct members at offset 0 to
8546 prevent tests like '&ptr->firstmember == 0' from getting
8547 eliminated. When ptr is null, although the -> expression
8548 is strictly speaking invalid, GCC retains it as a matter
8549 of QoI. See PR c/44555. */
8552 && indirect_base0
8553 /* The caller guarantees that when one of the arguments is
8554 constant (i.e., null in this case) it is second. */
8556 {
8558 {
8569 }
8570 }
8571 }
8573 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8574 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8575 the resulting offset is smaller in absolute value than the
8576 original one and has the same sign. */
8585 {
8590 tree cst;
8592 "occur when combining constants around "
8595 /* Put the constant on the side where it doesn't overflow and is
8596 of lower absolute value and of same sign than before. */
8603 {
8606 variable1,
8610 }
8618 {
8624 variable2);
8625 }
8626 }
8632 /* If we are comparing an expression that just has comparisons
8633 of two integer values, arithmetic expressions of those comparisons,
8634 and constants, we can simplify it. There are only three cases
8635 to check: the two values can either be equal, the first can be
8636 greater, or the second can be greater. Fold the expression for
8637 those three values. Since each value must be 0 or 1, we have
8638 eight possibilities, each of which corresponds to the constant 0
8639 or 1 or one of the six possible comparisons.
8641 This handles common cases like (a > b) == 0 but also handles
8642 expressions like ((x > y) - (y > x)) > 0, which supposedly
8643 occur in macroized code. */
8646 {
8651 /* Don't handle degenerate cases here; they should already
8652 have been handled anyway. */
8661 {
8665 /* We can't just pass T to eval_subst in case cval1 or cval2
8666 was the same as ARG1. */
8668 tree high_result
8672 arg1);
8673 tree equal_result
8677 arg1);
8678 tree low_result
8682 arg1);
8684 /* All three of these results should be 0 or 1. Confirm they are.
8685 Then use those values to select the proper code to use. */
8690 {
8691 /* Make a 3-bit mask with the high-order bit being the
8692 value for `>', the next for '=', and the low for '<'. */
8696 {
8698 /* Always false. */
8719 /* Always true. */
8721 }
8724 {
8728 }
8730 }
8731 }
8732 }
8735 }
8738 /* Subroutine of fold_binary. Optimize complex multiplications of the
8739 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8740 argument EXPR represents the expression "z" of type TYPE. */
8742 static tree
8744 {
8749 {
8752 }
8754 {
8757 }
8758 else
8759 {
8763 }
8772 }
8775 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8776 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8778 static bool
8780 {
8784 {
8787 }
8789 {
8795 else
8797 }
8798 else
8804 }
8806 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8807 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8808 NULL_TREE otherwise. */
8810 static tree
8812 {
8829 {
8833 }
8836 {
8842 }
8843 else
8845 }
8847 /* Try to fold a pointer difference of type TYPE two address expressions of
8848 array references AREF0 and AREF1 using location LOC. Return a
8849 simplified expression for the difference or NULL_TREE. */
8851 static tree
8854 {
8859 /* If the bases are array references as well, recurse. If the bases
8860 are pointer indirections compute the difference of the pointers.
8861 If the bases are equal, we are set. */
8864 && (base_offset
8868 && (base_offset
8874 {
8880 base_offset,
8883 }
8885 }
8887 /* If the real or vector real constant CST of type TYPE has an exact
8888 inverse, return it, else return NULL. */
8890 tree
8892 {
8893 REAL_VALUE_TYPE r;
8895 machine_mode mode;
8899 {
8915 {
8920 }
8926 }
8927 }
8929 /* Mask out the tz least significant bits of X of type TYPE where
8930 tz is the number of trailing zeroes in Y. */
8931 static wide_int
8933 {
8938 }
8940 /* Return true when T is an address and is known to be nonzero.
8941 For floating point we further ensure that T is not denormal.
8942 Similar logic is present in nonzero_address in rtlanal.h.
8944 If the return value is based on the assumption that signed overflow
8945 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8946 change *STRICT_OVERFLOW_P. */
8948 static bool
8950 {
8954 /* Doing something useful for floating point would need more work. */
8960 {
8963 strict_overflow_p);
8969 strict_overflow_p);
8977 }
8980 {
8983 strict_overflow_p);
8991 strict_overflow_p);
9006 strict_overflow_p);
9010 strict_overflow_p);
9013 {
9025 }
9029 }
9031 }
9033 /* Return true when T is an address and is known to be nonzero.
9034 Handle warnings about undefined signed overflow. */
9036 bool
9038 {
9045 "determining that expression is always "
9047 WARN_STRICT_OVERFLOW_MISC);
9049 }
9051 /* Return true if T is known not to be equal to an integer W. */
9053 bool
9055 {
9057 value_range_type rtype;
9059 {
9068 {
9073 }
9078 /* If T has some known zero bits and W has any of those bits set,
9079 then T is known not to be equal to W. */
9087 }
9088 }
9090 /* Fold a binary expression of code CODE and type TYPE with operands
9091 OP0 and OP1. LOC is the location of the resulting expression.
9092 Return the folded expression if folding is successful. Otherwise,
9093 return NULL_TREE. */
9095 tree
9098 {
9113 /* Strip any conversions that don't change the mode. This is
9114 safe for every expression, except for a comparison expression
9115 because its signedness is derived from its operands. So, in
9116 the latter case, only strip conversions that don't change the
9117 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9118 preserved.
9120 Note that this is done as an internal manipulation within the
9121 constant folder, in order to find the simplest representation
9122 of the arguments so that their form can be studied. In any
9123 cases, the appropriate type conversions should be put back in
9124 the tree that will get out of the constant folder. */
9127 {
9130 }
9131 else
9132 {
9135 }
9137 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9138 constant but we can't do arithmetic on them. */
9140 {
9143 {
9147 }
9148 }
9150 /* If this is a commutative operation, and ARG0 is a constant, move it
9151 to ARG1 to reduce the number of tests below. */
9156 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9157 to ARG1 to reduce the number of tests below. */
9166 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9168 First check for cases where an arithmetic operation is applied to a
9169 compound, conditional, or comparison operation. Push the arithmetic
9170 operation inside the compound or conditional to see if any folding
9171 can then be done. Convert comparison to conditional for this purpose.
9172 The also optimizes non-constant cases that used to be done in
9173 expand_expr.
9175 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9176 one of the operands is a comparison and the other is a comparison, a
9177 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9178 code below would make the expression more complex. Change it to a
9179 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9180 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9193 {
9197 boolean_type_node,
9205 }
9209 {
9211 {
9216 tem);
9217 }
9219 {
9224 tem);
9225 }
9230 {
9236 }
9241 {
9247 }
9248 }
9251 {
9253 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9256 {
9262 }
9264 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9267 {
9268 tree base;
9269 HOST_WIDE_INT coffset;
9278 }
9283 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9289 arg1),
9291 arg0)));
9297 {
9298 /* X + (X / CST) * -CST is X % CST. */
9303 {
9312 cst0));
9313 }
9314 }
9316 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9317 one. Make sure the type is not saturating and has the signedness of
9318 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9319 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9326 {
9330 }
9333 {
9334 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9335 (plus (plus (mult) (mult)) (foo)) so that we can
9336 take advantage of the factoring cases below. */
9345 {
9351 else
9364 parg0),
9366 marg)),
9370 return
9376 parg1)));
9377 }
9378 }
9379 else
9380 {
9381 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9382 to __complex__ ( x, y ). This is not the same for SNaNs or
9383 if signed zeros are involved. */
9387 {
9394 {
9398 {
9404 }
9406 {
9412 }
9413 }
9414 }
9422 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9423 We associate floats only if the user has specified
9424 -fassociative-math. */
9428 {
9433 {
9434 tree tree0;
9437 }
9438 }
9439 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9440 We associate floats only if the user has specified
9441 -fassociative-math. */
9445 {
9450 {
9451 tree tree0;
9454 }
9455 }
9456 }
9458 bit_rotate:
9459 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9460 is a rotate of A by C1 bits. */
9461 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9462 is a rotate of A by B bits. */
9463 {
9465 tree rtype;
9474 /* Only create rotates in complete modes. Other cases are not
9475 expanded properly. */
9478 {
9492 {
9496 code0 == LSHIFT_EXPR
9500 }
9502 {
9510 element_precision
9514 return
9517 ? LROTATE_EXPR
9522 }
9524 {
9532 element_precision
9536 return fold_convert_loc
9539 ? LROTATE_EXPR
9543 }
9544 }
9545 }
9547 associate:
9548 /* In most languages, can't associate operations on floats through
9549 parentheses. Rather than remember where the parentheses were, we
9550 don't associate floats at all, unless the user has specified
9551 -fassociative-math.
9552 And, we need to make sure type is not saturating. */
9556 {
9562 /* Split both trees into variables, constants, and literals. Then
9563 associate each group together, the constants with literals,
9564 then the result with variables. This increases the chances of
9565 literals being recombined later and of generating relocatable
9566 expressions for the sum of a constant and literal. */
9574 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9578 /* With undefined overflow prefer doing association in a type
9579 which wraps on overflow, if that is one of the operand types. */
9582 {
9590 }
9592 /* With undefined overflow we can only associate constants with one
9593 variable, and constants whose association doesn't overflow. */
9596 {
9598 {
9599 /* ??? If split_tree would handle NEGATE_EXPR we could
9600 simply reject these cases and the allowed cases would
9601 be the var0/minus_var1 ones. */
9607 {
9610 }
9617 {
9620 }
9626 /* The only case we can still associate with two variables
9627 is if they cancel out. */
9631 }
9637 }
9639 /* Only do something if we found more than two objects. Otherwise,
9640 nothing has changed and we risk infinite recursion. */
9648 {
9660 {
9664 }
9666 {
9670 }
9672 /* Preserve the MINUS_EXPR if the negative part of the literal is
9673 greater than the positive part. Otherwise, the multiplicative
9674 folding code (i.e extract_muldiv) may be fooled in case
9675 unsigned constants are subtracted, like in the following
9676 example: ((X*2 + 4) - 8U)/2. */
9678 {
9682 /* But avoid ending up with only negated parts. */
9684 {
9688 }
9689 else
9690 {
9694 }
9695 }
9697 /* Don't introduce overflows through reassociation. */
9702 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9709 /* Eliminate minus_con0. */
9711 {
9718 else
9721 }
9723 /* Eliminate minus_var0. */
9725 {
9729 else
9732 }
9734 return
9737 }
9738 }
9743 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9751 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9752 __complex__ ( x, -y ). This is not the same for SNaNs or if
9753 signed zeros are involved. */
9757 {
9764 {
9768 {
9770 arg1r ? arg1r
9775 }
9777 {
9781 arg1i ? arg1i
9784 }
9785 }
9786 }
9788 /* A - B -> A + (-B) if B is easily negatable. */
9792 /* Avoid this transformation if B is a positive REAL_CST. */
9800 /* Fold &a[i] - &a[j] to i-j. */
9805 {
9811 }
9814 && flag_unsafe_math_optimizations
9820 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9821 one. Make sure the type is not saturating and has the signedness of
9822 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9823 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9830 {
9834 }
9840 {
9841 /* Transform x * -C into -x * C if x is easily negatable. */
9856 {
9859 "occur when simplifying "
9861 WARN_STRICT_OVERFLOW_MISC);
9863 }
9865 /* Optimize z * conj(z) for integer complex numbers. */
9872 }
9873 else
9874 {
9875 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9876 This is not the same for NaNs or if signed zeros are
9877 involved. */
9883 {
9886 return
9892 return
9897 }
9899 /* Optimize z * conj(z) for floating point complex numbers.
9900 Guarded by flag_unsafe_math_optimizations as non-finite
9901 imaginary components don't produce scalar results. */
9910 }
9914 /* Canonicalize (X & C1) | C2. */
9918 {
9923 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9931 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9933 {
9936 }
9938 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9939 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9940 mode which allows further optimizations. */
9945 {
9949 {
9952 }
9953 }
9956 {
9961 }
9962 }
9964 /* See if this can be simplified into a rotate first. If that
9965 is unsuccessful continue in the association code. */
9969 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9977 /* See if this can be simplified into a rotate first. If that
9978 is unsuccessful continue in the association code. */
9982 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9987 {
9988 tree tem2;
9995 }
9996 /* Fold ~X & 1 as (X & 1) == 0. */
10000 {
10001 tree tem2;
10008 }
10009 /* Fold !X & 1 as X == 0. */
10012 {
10016 }
10018 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10019 multiple of 1 << CST. */
10021 {
10028 }
10030 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10031 bits from CST2. */
10035 {
10043 {
10044 /* Avoid the transform if arg1 is a mask of some
10045 mode which allows further optimizations. */
10052 }
10053 }
10055 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10056 ((A & N) + B) & M -> (A + B) & M
10057 Similarly if (N & M) == 0,
10058 ((A | N) + B) & M -> (A + B) & M
10059 and for - instead of + (or unary - instead of +)
10060 and/or ^ instead of |.
10061 If B is constant and (B & M) == 0, fold into A & M. */
10063 {
10072 {
10075 wide_int cst0;
10077 /* Now we know that arg0 is (C + D) or (C - D) or
10078 -C and arg1 (M) is == (1LL << cst) - 1.
10079 Store C into PMOP[0] and D into PMOP[1]. */
10083 {
10086 }
10093 {
10103 {
10106 }
10109 /* If C or D is of the form (A & N) where
10110 (N & M) == M, or of the form (A | N) or
10111 (A ^ N) where (N & M) == 0, replace it with A. */
10115 /* If C or D is a N where (N & M) == 0, it can be
10116 omitted (assumed 0). */
10124 }
10126 /* Only build anything new if we optimized one or both arguments
10127 above. */
10131 {
10134 {
10135 /* Perform the operations in a type that has defined
10136 overflow behavior. */
10142 }
10147 {
10155 else
10157 }
10160 else
10163 /* TEM is now the new binary +, - or unary - replacement. */
10167 }
10168 }
10169 }
10171 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10174 {
10179 return
10181 }
10186 /* Don't touch a floating-point divide by zero unless the mode
10187 of the constant can represent infinity. */
10193 /* (-A) / (-B) -> A / B */
10205 /* Fall through */
10208 /* Simplify A / (B << N) where A and B are positive and B is
10209 a power of 2, to A >> (N + log2(B)). */
10214 {
10217 {
10225 WARN_STRICT_OVERFLOW_MISC);
10231 }
10232 }
10234 /* Fall through */
10242 /* Convert -A / -B to A / B when the type is signed and overflow is
10243 undefined. */
10247 {
10250 "when distributing negation across "
10252 WARN_STRICT_OVERFLOW_MISC);
10257 }
10261 {
10264 "when distributing negation across "
10266 WARN_STRICT_OVERFLOW_MISC);
10271 }
10273 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10274 operation, EXACT_DIV_EXPR.
10276 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10277 At one time others generated faster code, it's not clear if they do
10278 after the last round to changes to the DIV code in expmed.c. */
10289 {
10293 WARN_STRICT_OVERFLOW_MISC);
10295 }
10307 {
10311 WARN_STRICT_OVERFLOW_MISC);
10313 }
10321 /* Since negative shift count is not well-defined,
10322 don't try to compute it in the compiler. */
10328 /* If we have a rotate of a bit operation with the rotate count and
10329 the second operand of the bit operation both constant,
10330 permute the two operations. */
10336 {
10344 }
10346 /* Two consecutive rotates adding up to the some integer
10347 multiple of the precision of the type can be ignored. */
10362 /* Note that the operands of this must be ints
10363 and their values must be 0 or 1.
10364 ("true" is a fixed value perhaps depending on the language.) */
10365 /* If first arg is constant zero, return it. */
10368 /* FALLTHRU */
10370 /* If either arg is constant true, drop it. */
10374 /* Preserve sequence points. */
10377 /* If second arg is constant zero, result is zero, but first arg
10378 must be evaluated. */
10381 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10382 case will be handled here. */
10386 /* !X && X is always false. */
10390 /* X && !X is always false. */
10395 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10396 means A >= Y && A != MAX, but in this case we know that
10397 A < X <= MAX. */
10401 {
10409 }
10418 /* Note that the operands of this must be ints
10419 and their values must be 0 or true.
10420 ("true" is a fixed value perhaps depending on the language.) */
10421 /* If first arg is constant true, return it. */
10424 /* FALLTHRU */
10426 /* If either arg is constant zero, drop it. */
10430 /* Preserve sequence points. */
10433 /* If second arg is constant true, result is true, but we must
10434 evaluate first arg. */
10437 /* Likewise for first arg, but note this only occurs here for
10438 TRUTH_OR_EXPR. */
10442 /* !X || X is always true. */
10446 /* X || !X is always true. */
10451 /* (X && !Y) || (!X && Y) is X ^ Y */
10454 {
10471 }
10480 /* If the second arg is constant zero, drop it. */
10483 /* If the second arg is constant true, this is a logical inversion. */
10485 {
10488 }
10489 /* Identical arguments cancel to zero. */
10493 /* !X ^ X is always true. */
10498 /* X ^ !X is always true. */
10514 /* bool_var != 1 becomes !bool_var. */
10521 /* bool_var == 0 becomes !bool_var. */
10528 /* !exp != 0 becomes !exp */
10533 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10542 {
10548 }
10550 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10559 {
10565 }
10567 /* If this is an EQ or NE comparison with zero and ARG0 is
10568 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10569 two operations, but the latter can be done in one less insn
10570 on machines that have only two-operand insns or on which a
10571 constant cannot be the first operand. */
10574 {
10579 {
10586 arg1);
10587 }
10590 {
10597 arg1);
10598 }
10599 }
10601 /* If this is an NE or EQ comparison of zero against the result of a
10602 signed MOD operation whose second operand is a power of 2, make
10603 the MOD operation unsigned since it is simpler and equivalent. */
10611 {
10621 }
10623 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10624 C1 is a valid shift constant, and C2 is a power of two, i.e.
10625 a single bit. */
10629 == INTEGER_CST
10632 {
10637 /* Check for a valid shift count. */
10639 {
10643 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10644 can be rewritten as (X & (C2 << C1)) != 0. */
10646 {
10651 }
10652 /* Otherwise, for signed (arithmetic) shifts,
10653 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10654 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10658 /* Otherwise, of unsigned (logical) shifts,
10659 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10660 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10661 else
10665 arg000);
10666 }
10667 }
10669 /* If this is a comparison of a field, we may be able to simplify it. */
10672 /* Handle the constant case even without -O
10673 to make sure the warnings are given. */
10675 {
10679 }
10681 /* Optimize comparisons of strlen vs zero to a compare of the
10682 first character of the string vs zero. To wit,
10683 strlen(ptr) == 0 => *ptr == 0
10684 strlen(ptr) != 0 => *ptr != 0
10685 Other cases should reduce to one of these two (or a constant)
10686 due to the return value of strlen being unsigned. */
10689 {
10697 {
10702 }
10703 }
10705 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10706 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10710 {
10715 {
10717 {
10720 }
10723 }
10724 }
10726 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10727 (X & C) == 0 when C is a single bit. */
10732 {
10739 arg1));
10740 }
10742 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10743 constant C is a power of two, i.e. a single bit. */
10750 {
10754 }
10756 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10757 when is C is a power of two, i.e. a single bit. */
10764 {
10770 }
10774 {
10777 }
10779 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10782 {
10790 {
10796 }
10798 {
10804 }
10806 {
10812 }
10814 {
10820 }
10821 }
10825 {
10832 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10833 operand_equal_p guarantees no side-effects so we don't need
10834 to use omit_one_operand on Z. */
10838 arg10));
10842 arg11));
10846 arg10));
10850 arg11));
10852 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10855 {
10861 }
10862 }
10864 /* Attempt to simplify equality/inequality comparisons of complex
10865 values. Only lower the comparison if the result is known or
10866 can be simplified to a single scalar comparison. */
10871 {
10876 {
10879 }
10880 else
10881 {
10884 }
10887 {
10890 }
10891 else
10892 {
10895 }
10899 {
10901 {
10906 }
10907 else
10908 {
10913 }
10914 }
10918 {
10920 {
10925 }
10926 else
10927 {
10932 }
10933 }
10934 }
10946 /* Transform comparisons of the form X +- C CMP X. */
10953 {
10960 else
10963 /* (X - c) > X becomes false. */
10967 {
10971 "occur when assuming that (X - c) > X "
10973 WARN_STRICT_OVERFLOW_ALL);
10975 }
10977 /* Likewise (X + c) < X becomes false. */
10981 {
10985 "occur when assuming that "
10987 WARN_STRICT_OVERFLOW_ALL);
10989 }
10991 /* Convert (X - c) <= X to true. */
10996 {
11000 "occur when assuming that "
11002 WARN_STRICT_OVERFLOW_ALL);
11004 }
11006 /* Convert (X + c) >= X to true. */
11011 {
11015 "occur when assuming that "
11017 WARN_STRICT_OVERFLOW_ALL);
11019 }
11022 {
11023 /* Convert X + c > X and X - c < X to true for integers. */
11027 {
11030 "not occur when assuming that "
11032 WARN_STRICT_OVERFLOW_ALL);
11034 }
11039 {
11042 "not occur when assuming that "
11044 WARN_STRICT_OVERFLOW_ALL);
11046 }
11048 /* Convert X + c <= X and X - c >= X to false for integers. */
11052 {
11055 "not occur when assuming that "
11057 WARN_STRICT_OVERFLOW_ALL);
11059 }
11064 {
11067 "not occur when assuming that "
11069 WARN_STRICT_OVERFLOW_ALL);
11071 }
11072 }
11073 }
11075 /* If we are comparing an ABS_EXPR with a constant, we can
11076 convert all the cases into explicit comparisons, but they may
11077 well not be faster than doing the ABS and one comparison.
11078 But ABS (X) <= C is a range comparison, which becomes a subtraction
11079 and a comparison, and is probably faster. */
11093 /* Convert ABS_EXPR<x> >= 0 to true. */
11100 {
11103 "when simplifying comparison of "
11105 WARN_STRICT_OVERFLOW_CONDITIONAL);
11108 arg0);
11109 }
11111 /* Convert ABS_EXPR<x> < 0 to false. */
11116 {
11119 "when simplifying comparison of "
11121 WARN_STRICT_OVERFLOW_CONDITIONAL);
11124 arg0);
11125 }
11127 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11128 and similarly for >= into !=. */
11138 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11139 otherwise Y might be >= # of bits in X's type and thus e.g.
11140 (unsigned char) (1 << Y) for Y 15 might be 0.
11141 If the cast is widening, then 1 << Y should have unsigned type,
11142 otherwise if Y is number of bits in the signed shift type minus 1,
11143 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11144 31 might be 0xffffffff80000000. */
11155 {
11161 }
11173 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11174 {
11186 }
11191 /* When pedantic, a compound expression can be neither an lvalue
11192 nor an integer constant expression. */
11195 /* Don't let (0, 0) be null pointer constant. */
11201 /* An ASSERT_EXPR should never be passed to fold_binary. */
11207 }
11209 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11210 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11211 of GOTO_EXPR. */
11213 static tree
11215 {
11217 {
11224 /* fall through */
11228 }
11229 }
11231 /* Return whether the sub-tree ST contains a label which is accessible from
11232 outside the sub-tree. */
11234 static bool
11236 {
11237 return
11239 }
11241 /* Fold a ternary expression of code CODE and type TYPE with operands
11242 OP0, OP1, and OP2. Return the folded expression if folding is
11243 successful. Otherwise, return NULL_TREE. */
11245 tree
11248 {
11249 tree tem;
11256 /* If this is a commutative operation, and OP0 is a constant, move it
11257 to OP1 to reduce the number of tests below. */
11266 /* Strip any conversions that don't change the mode. This is safe
11267 for every expression, except for a comparison expression because
11268 its signedness is derived from its operands. So, in the latter
11269 case, only strip conversions that don't change the signedness.
11271 Note that this is done as an internal manipulation within the
11272 constant folder, in order to find the simplest representation of
11273 the arguments so that their form can be studied. In any cases,
11274 the appropriate type conversions should be put back in the tree
11275 that will get out of the constant folder. */
11277 {
11280 }
11283 {
11286 }
11289 {
11292 }
11295 {
11299 {
11305 }
11310 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11311 so all simple results must be passed through pedantic_non_lvalue. */
11313 {
11316 /* Only optimize constant conditions when the selected branch
11317 has the same type as the COND_EXPR. This avoids optimizing
11318 away "c ? x : throw", where the throw has a void type.
11319 Avoid throwing away that operand which contains label. */
11326 }
11328 {
11333 {
11338 {
11346 }
11350 }
11351 }
11353 /* If we have A op B ? A : C, we may be able to convert this to a
11354 simpler expression, depending on the operation and the values
11355 of B and C. Signed zeros prevent all of these transformations,
11356 for reasons given above each one.
11358 Also try swapping the arguments and inverting the conditional. */
11363 {
11367 }
11371 op2,
11374 {
11378 {
11382 }
11383 }
11385 /* If the second operand is simpler than the third, swap them
11386 since that produces better jump optimization results. */
11389 {
11391 /* See if this can be inverted. If it can't, possibly because
11392 it was a floating-point inequality comparison, don't do
11393 anything. */
11397 }
11399 /* Convert A ? 1 : 0 to simply A. */
11404 /* If we try to convert OP0 to our type, the
11405 call to fold will try to move the conversion inside
11406 a COND, which will recurse. In that case, the COND_EXPR
11407 is probably the best choice, so leave it alone. */
11411 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11412 over COND_EXPR in cases such as floating point comparisons. */
11421 arg0)));
11423 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11428 {
11429 /* sign_bit_p looks through both zero and sign extensions,
11430 but for this optimization only sign extensions are
11431 usable. */
11434 {
11437 {
11440 }
11442 }
11443 /* sign_bit_p only checks ARG1 bits within A's precision.
11444 If <sign bit of A> has wider type than A, bits outside
11445 of A's precision in <sign bit of A> need to be checked.
11446 If they are all 0, this optimization needs to be done
11447 in unsigned A's type, if they are all 1 in signed A's type,
11448 otherwise this can't be done. */
11454 {
11456 tree tem_type;
11469 {
11472 }
11474 {
11477 }
11478 else
11480 }
11483 return
11489 arg1)));
11490 }
11492 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11493 already handled above. */
11498 {
11508 op1);
11509 }
11511 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11512 is probably obsolete because the first operand should be a
11513 truth value (that's why we have the two cases above), but let's
11514 leave it in until we can confirm this for all front-ends. */
11526 /* Disable the transformations below for vectors, since
11527 fold_binary_op_with_conditional_arg may undo them immediately,
11528 yielding an infinite loop. */
11532 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11541 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11546 {
11548 /* Only perform transformation if ARG0 is easily inverted. */
11552 ? BIT_IOR_EXPR
11555 op1);
11556 }
11558 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11563 {
11565 /* Only perform transformation if ARG0 is easily inverted. */
11571 op2);
11572 }
11574 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11586 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11587 of fold_ternary on them. */
11595 {
11605 {
11610 {
11618 }
11619 }
11620 }
11622 /* On constants we can use native encode/interpret to constant
11623 fold (nearly) all BIT_FIELD_REFs. */
11627 {
11630 /* Limit us to a reasonable amount of work. To relax the
11631 other limitations we need bit-shifting of the buffer
11632 and rounding up the size. */
11636 {
11638 unsigned HOST_WIDE_INT len
11643 {
11648 }
11649 }
11650 }
11655 /* For integers we can decompose the FMA if possible. */
11667 {
11683 {
11688 /* Make sure that the perm value is in an acceptable
11689 range. */
11698 else
11703 }
11706 {
11711 }
11716 {
11721 }
11727 {
11731 }
11736 /* Some targets are deficient and fail to expand a single
11737 argument permutation while still allowing an equivalent
11738 2-argument version. */
11742 {
11745 }
11748 {
11755 }
11759 }
11763 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11766 {
11772 wide_int tem2
11776 }
11781 {
11783 unsigned HOST_WIDE_INT elsize
11786 {
11790 else
11791 {
11797 }
11798 }
11799 }
11805 }
11807 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11808 of an array (or vector). */
11810 tree
11812 {
11817 {
11820 {
11821 /* Static constructors for variably sized objects makes no sense. */
11825 }
11826 }
11837 offset_int max_index;
11842 {
11843 /* Array constructor might explicitly set index, or specify a range,
11844 or leave index NULL meaning that it is next index after previous
11845 one. */
11847 {
11850 else
11851 {
11855 }
11856 }
11857 else
11858 {
11864 }
11866 /* Do we have match? */
11870 }
11872 }
11874 /* Perform constant folding and related simplification of EXPR.
11875 The related simplifications include x*1 => x, x*0 => 0, etc.,
11876 and application of the associative law.
11877 NOP_EXPR conversions may be removed freely (as long as we
11878 are careful not to change the type of the overall expression).
11879 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11880 but we can constant-fold them if they have constant operands. */
11882 #ifdef ENABLE_FOLD_CHECKING
11883 # define fold(x) fold_1 (x)
11885 static
11886 #endif
11887 tree
11889 {
11893 tree tem;
11896 /* Return right away if a constant. */
11900 /* CALL_EXPR-like objects with variable numbers of operands are
11901 treated specially. */
11903 {
11905 {
11908 }
11910 }
11913 {
11918 {
11936 }
11937 }
11940 {
11942 {
11949 {
11954 }
11957 }
11959 /* Return a VECTOR_CST if possible. */
11961 {
11967 tree val;
11973 }
11981 }
11983 #ifdef ENABLE_FOLD_CHECKING
11984 #undef fold
11991 /* When --enable-checking=fold, compute a digest of expr before
11992 and after actual fold call to see if fold did not accidentally
11993 change original expr. */
11995 tree
11997 {
11998 tree ret;
12018 }
12020 void
12022 {
12033 }
12035 static void
12037 {
12039 }
12041 static void
12044 {
12050 recursive_label:
12060 {
12061 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12066 }
12074 {
12075 /* Allow these fields to be modified. */
12076 tree tmp;
12085 {
12088 }
12089 }
12100 {
12103 {
12118 }
12122 {
12135 }
12152 {
12158 }
12161 {
12163 {
12166 }
12168 }
12179 {
12182 }
12192 }
12193 }
12195 /* Helper function for outputting the checksum of a tree T. When
12196 debugging with gdb, you can "define mynext" to be "next" followed
12197 by "call debug_fold_checksum (op0)", then just trace down till the
12198 outputs differ. */
12200 DEBUG_FUNCTION void
12202 {
12217 }
12219 #endif
12221 /* Fold a unary tree expression with code CODE of type TYPE with an
12222 operand OP0. LOC is the location of the resulting expression.
12223 Return a folded expression if successful. Otherwise, return a tree
12224 expression with code CODE of type TYPE with an operand OP0. */
12226 tree
12229 {
12230 tree tem;
12231 #ifdef ENABLE_FOLD_CHECKING
12240 #endif
12246 #ifdef ENABLE_FOLD_CHECKING
12253 #endif
12255 }
12257 /* Fold a binary tree expression with code CODE of type TYPE with
12258 operands OP0 and OP1. LOC is the location of the resulting
12259 expression. Return a folded expression if successful. Otherwise,
12260 return a tree expression with code CODE of type TYPE with operands
12261 OP0 and OP1. */
12263 tree
12266 MEM_STAT_DECL)
12267 {
12268 tree tem;
12269 #ifdef ENABLE_FOLD_CHECKING
12286 #endif
12292 #ifdef ENABLE_FOLD_CHECKING
12307 #endif
12309 }
12311 /* Fold a ternary tree expression with code CODE of type TYPE with
12312 operands OP0, OP1, and OP2. Return a folded expression if
12313 successful. Otherwise, return a tree expression with code CODE of
12314 type TYPE with operands OP0, OP1, and OP2. */
12316 tree
12319 {
12320 tree tem;
12321 #ifdef ENABLE_FOLD_CHECKING
12345 #endif
12352 #ifdef ENABLE_FOLD_CHECKING
12375 #endif
12377 }
12379 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12380 arguments in ARGARRAY, and a null static chain.
12381 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12382 of type TYPE from the given operands as constructed by build_call_array. */
12384 tree
12387 {
12388 tree tem;
12389 #ifdef ENABLE_FOLD_CHECKING
12408 #endif
12414 #ifdef ENABLE_FOLD_CHECKING
12430 #endif
12432 }
12434 /* Perform constant folding and related simplification of initializer
12435 expression EXPR. These behave identically to "fold_buildN" but ignore
12436 potential run-time traps and exceptions that fold must preserve. */
12438 #define START_FOLD_INIT \
12439 int saved_signaling_nans = flag_signaling_nans;\
12440 int saved_trapping_math = flag_trapping_math;\
12441 int saved_rounding_math = flag_rounding_math;\
12442 int saved_trapv = flag_trapv;\
12443 int saved_folding_initializer = folding_initializer;\
12444 flag_signaling_nans = 0;\
12445 flag_trapping_math = 0;\
12446 flag_rounding_math = 0;\
12447 flag_trapv = 0;\
12448 folding_initializer = 1;
12450 #define END_FOLD_INIT \
12451 flag_signaling_nans = saved_signaling_nans;\
12452 flag_trapping_math = saved_trapping_math;\
12453 flag_rounding_math = saved_rounding_math;\
12454 flag_trapv = saved_trapv;\
12455 folding_initializer = saved_folding_initializer;
12457 tree
12460 {
12461 tree result;
12462 START_FOLD_INIT;
12466 END_FOLD_INIT;
12468 }
12470 tree
12473 {
12474 tree result;
12475 START_FOLD_INIT;
12479 END_FOLD_INIT;
12481 }
12483 tree
12486 {
12487 tree result;
12488 START_FOLD_INIT;
12492 END_FOLD_INIT;
12494 }
12496 #undef START_FOLD_INIT
12497 #undef END_FOLD_INIT
12499 /* Determine if first argument is a multiple of second argument. Return 0 if
12500 it is not, or we cannot easily determined it to be.
12502 An example of the sort of thing we care about (at this point; this routine
12503 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12504 fold cases do now) is discovering that
12506 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12508 is a multiple of
12510 SAVE_EXPR (J * 8)
12512 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12514 This code also handles discovering that
12516 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12518 is a multiple of 8 so we don't have to worry about dealing with a
12519 possible remainder.
12521 Note that we *look* inside a SAVE_EXPR only to determine how it was
12522 calculated; it is not safe for fold to do much of anything else with the
12523 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12524 at run time. For example, the latter example above *cannot* be implemented
12525 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12526 evaluation time of the original SAVE_EXPR is not necessarily the same at
12527 the time the new expression is evaluated. The only optimization of this
12528 sort that would be valid is changing
12530 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12532 divided by 8 to
12534 SAVE_EXPR (I) * SAVE_EXPR (J)
12536 (where the same SAVE_EXPR (J) is used in the original and the
12537 transformed version). */
12539 int
12541 {
12552 {
12554 /* Bitwise and provides a power of two multiple. If the mask is
12555 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12558 /* FALLTHRU */
12565 /* It is impossible to prove if op0 - op1 is multiple of bottom
12566 precisely, so be conservative here checking if both op0 and op1
12567 are multiple of bottom. Note we check the second operand first
12568 since it's usually simpler. */
12573 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12574 as op0 - 3 if the expression has unsigned type. For example,
12575 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12585 {
12587 /* const_binop may not detect overflow correctly,
12588 so check for it explicitly here. */
12592 size_one_node,
12593 op1)))
12596 }
12600 /* Can't handle conversions from non-integral or wider integral type. */
12606 /* fall through */
12623 SIGNED);
12629 {
12632 /* Check for special cases to see if top is defined as multiple
12633 of bottom:
12635 top = (X & ~(bottom - 1) ; bottom is power of 2
12637 or
12639 Y = X % bottom
12640 top = X - Y. */
12659 }
12661 /* fall through */
12665 }
12666 }
12668 #define tree_expr_nonnegative_warnv_p(X, Y) \
12671 #define RECURSE(X) \
12672 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12674 /* Return true if CODE or TYPE is known to be non-negative. */
12676 static bool
12678 {
12681 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12682 have a signed:1 type (where the value is -1 and 0). */
12685 }
12687 /* Return true if (CODE OP0) is known to be non-negative. If the return
12688 value is based on the assumption that signed overflow is undefined,
12689 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12690 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12692 bool
12695 {
12700 {
12702 /* We can't return 1 if flag_wrapv is set because
12703 ABS_EXPR<INT_MIN> = INT_MIN. */
12707 {
12710 }
12718 CASE_CONVERT:
12719 {
12724 {
12728 {
12732 }
12733 }
12735 {
12741 }
12742 }
12747 }
12749 /* We don't know sign of `t', so be conservative and return false. */
12751 }
12753 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12754 value is based on the assumption that signed overflow is undefined,
12755 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12756 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12758 bool
12762 {
12767 {
12773 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12774 both unsigned and at least 2 bits shorter than the result. */
12778 {
12783 {
12787 }
12788 }
12793 {
12794 /* x * x is always non-negative for floating point x
12795 or without overflow. */
12798 {
12803 }
12804 }
12806 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12807 both unsigned and their total bits is shorter than the result. */
12811 {
12830 {
12840 }
12841 }
12868 }
12870 /* We don't know sign of `t', so be conservative and return false. */
12872 }
12874 /* Return true if T is known to be non-negative. If the return
12875 value is based on the assumption that signed overflow is undefined,
12876 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12877 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12879 bool
12881 {
12886 {
12900 /* Limit the depth of recursion to avoid quadratic behavior.
12901 This is expected to catch almost all occurrences in practice.
12902 If this code misses important cases that unbounded recursion
12903 would not, passes that need this information could be revised
12904 to provide it through dataflow propagation. */
12912 }
12913 }
12915 /* Return true if T is known to be non-negative. If the return
12916 value is based on the assumption that signed overflow is undefined,
12917 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12918 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12920 bool
12923 {
12925 {
12926 CASE_CFN_ACOS:
12927 CASE_CFN_ACOSH:
12928 CASE_CFN_CABS:
12929 CASE_CFN_COSH:
12930 CASE_CFN_ERFC:
12931 CASE_CFN_EXP:
12932 CASE_CFN_EXP10:
12933 CASE_CFN_EXP2:
12934 CASE_CFN_FABS:
12935 CASE_CFN_FDIM:
12936 CASE_CFN_HYPOT:
12937 CASE_CFN_POW10:
12938 CASE_CFN_FFS:
12939 CASE_CFN_PARITY:
12940 CASE_CFN_POPCOUNT:
12941 CASE_CFN_CLZ:
12942 CASE_CFN_CLRSB:
12945 /* Always true. */
12948 CASE_CFN_SQRT:
12949 /* sqrt(-0.0) is -0.0. */
12954 CASE_CFN_ASINH:
12955 CASE_CFN_ATAN:
12956 CASE_CFN_ATANH:
12957 CASE_CFN_CBRT:
12958 CASE_CFN_CEIL:
12959 CASE_CFN_ERF:
12960 CASE_CFN_EXPM1:
12961 CASE_CFN_FLOOR:
12962 CASE_CFN_FMOD:
12963 CASE_CFN_FREXP:
12964 CASE_CFN_ICEIL:
12965 CASE_CFN_IFLOOR:
12966 CASE_CFN_IRINT:
12967 CASE_CFN_IROUND:
12968 CASE_CFN_LCEIL:
12969 CASE_CFN_LDEXP:
12970 CASE_CFN_LFLOOR:
12971 CASE_CFN_LLCEIL:
12972 CASE_CFN_LLFLOOR:
12973 CASE_CFN_LLRINT:
12974 CASE_CFN_LLROUND:
12975 CASE_CFN_LRINT:
12976 CASE_CFN_LROUND:
12977 CASE_CFN_MODF:
12978 CASE_CFN_NEARBYINT:
12979 CASE_CFN_RINT:
12980 CASE_CFN_ROUND:
12981 CASE_CFN_SCALB:
12982 CASE_CFN_SCALBLN:
12983 CASE_CFN_SCALBN:
12984 CASE_CFN_SIGNBIT:
12985 CASE_CFN_SIGNIFICAND:
12986 CASE_CFN_SINH:
12987 CASE_CFN_TANH:
12988 CASE_CFN_TRUNC:
12989 /* True if the 1st argument is nonnegative. */
12992 CASE_CFN_FMAX:
12993 /* True if the 1st OR 2nd arguments are nonnegative. */
12996 CASE_CFN_FMIN:
12997 /* True if the 1st AND 2nd arguments are nonnegative. */
13000 CASE_CFN_COPYSIGN:
13001 /* True if the 2nd argument is nonnegative. */
13004 CASE_CFN_POWI:
13005 /* True if the 1st argument is nonnegative or the second
13006 argument is an even integer. */
13012 CASE_CFN_POW:
13013 /* True if the 1st argument is nonnegative or the second
13014 argument is an even integer valued real. */
13016 {
13017 REAL_VALUE_TYPE c;
13018 HOST_WIDE_INT n;
13023 {
13024 REAL_VALUE_TYPE cint;
13028 }
13029 }
13034 }
13036 }
13038 /* Return true if T is known to be non-negative. If the return
13039 value is based on the assumption that signed overflow is undefined,
13040 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13041 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13043 static bool
13045 {
13051 {
13053 {
13057 /* If the initializer is non-void, then it's a normal expression
13058 that will be assigned to the slot. */
13062 /* Otherwise, the initializer sets the slot in some way. One common
13063 way is an assignment statement at the end of the initializer. */
13065 {
13073 else
13075 }
13081 }
13084 {
13090 arg0,
13091 arg1,
13093 }
13106 }
13107 }
13109 #undef RECURSE
13110 #undef tree_expr_nonnegative_warnv_p
13112 /* Return true if T is known to be non-negative. If the return
13113 value is based on the assumption that signed overflow is undefined,
13114 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13115 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13117 bool
13119 {
13126 {
13148 }
13151 {
13177 }
13178 }
13180 /* Return true if `t' is known to be non-negative. Handle warnings
13181 about undefined signed overflow. */
13183 bool
13185 {
13192 "determining that expression is always "
13194 WARN_STRICT_OVERFLOW_MISC);
13196 }
13199 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13200 For floating point we further ensure that T is not denormal.
13201 Similar logic is present in nonzero_address in rtlanal.h.
13203 If the return value is based on the assumption that signed overflow
13204 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13205 change *STRICT_OVERFLOW_P. */
13207 bool
13210 {
13212 {
13215 strict_overflow_p);
13218 {
13224 strict_overflow_p));
13225 }
13230 strict_overflow_p);
13234 }
13237 }
13239 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13240 For floating point we further ensure that T is not denormal.
13241 Similar logic is present in nonzero_address in rtlanal.h.
13243 If the return value is based on the assumption that signed overflow
13244 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13245 change *STRICT_OVERFLOW_P. */
13247 bool
13249 tree type,
13250 tree op0,
13252 {
13255 {
13259 {
13260 /* With the presence of negative values it is hard
13261 to say something. */
13268 /* One of operands must be positive and the other non-negative. */
13269 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13270 overflows, on a twos-complement machine the sum of two
13271 nonnegative numbers can never be zero. */
13273 strict_overflow_p)
13275 strict_overflow_p));
13276 }
13281 {
13283 strict_overflow_p)
13285 strict_overflow_p))
13286 {
13289 }
13290 }
13299 {
13302 }
13309 {
13313 /* When both operands are nonzero, then MAX must be too. */
13315 strict_overflow_p))
13318 /* MAX where operand 0 is positive is positive. */
13320 strict_overflow_p);
13321 }
13322 /* MAX where operand 1 is positive is positive. */
13327 {
13331 }
13336 strict_overflow_p)
13338 strict_overflow_p));
13342 }
13345 }
13347 /* Return true when T is an address and is known to be nonzero.
13348 For floating point we further ensure that T is not denormal.
13349 Similar logic is present in nonzero_address in rtlanal.h.
13351 If the return value is based on the assumption that signed overflow
13352 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13353 change *STRICT_OVERFLOW_P. */
13355 bool
13357 {
13360 {
13365 {
13377 /* For objects in symbol table check if we know they are non-zero.
13378 Don't do anything for variables and functions before symtab is built;
13379 it is quite possible that they will be declared weak later. */
13384 /* Constants are never weak. */
13389 }
13397 {
13401 }
13411 }
13413 }
13415 #define integer_valued_real_p(X) \
13418 #define RECURSE(X) \
13419 ((integer_valued_real_p) (X, depth + 1))
13421 /* Return true if the floating point result of (CODE OP0) has an
13422 integer value. We also allow +Inf, -Inf and NaN to be considered
13423 integer values. Return false for signaling NaN.
13425 DEPTH is the current nesting depth of the query. */
13427 bool
13429 {
13431 {
13438 CASE_CONVERT:
13439 {
13446 }
13450 }
13452 }
13454 /* Return true if the floating point result of (CODE OP0 OP1) has an
13455 integer value. We also allow +Inf, -Inf and NaN to be considered
13456 integer values. Return false for signaling NaN.
13458 DEPTH is the current nesting depth of the query. */
13460 bool
13462 {
13464 {
13474 }
13476 }
13478 /* Return true if the floating point result of calling FNDECL with arguments
13479 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13480 considered integer values. Return false for signaling NaN. If FNDECL
13481 takes fewer than 2 arguments, the remaining ARGn are null.
13483 DEPTH is the current nesting depth of the query. */
13485 bool
13487 {
13489 {
13490 CASE_CFN_CEIL:
13491 CASE_CFN_FLOOR:
13492 CASE_CFN_NEARBYINT:
13493 CASE_CFN_RINT:
13494 CASE_CFN_ROUND:
13495 CASE_CFN_TRUNC:
13498 CASE_CFN_FMIN:
13499 CASE_CFN_FMAX:
13504 }
13506 }
13508 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13509 has an integer value. We also allow +Inf, -Inf and NaN to be
13510 considered integer values. Return false for signaling NaN.
13512 DEPTH is the current nesting depth of the query. */
13514 bool
13516 {
13518 {
13526 /* Limit the depth of recursion to avoid quadratic behavior.
13527 This is expected to catch almost all occurrences in practice.
13528 If this code misses important cases that unbounded recursion
13529 would not, passes that need this information could be revised
13530 to provide it through dataflow propagation. */
13534 depth));
13538 }
13540 }
13542 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13543 has an integer value. We also allow +Inf, -Inf and NaN to be
13544 considered integer values. Return false for signaling NaN.
13546 DEPTH is the current nesting depth of the query. */
13548 static bool
13550 {
13552 {
13563 }
13565 }
13567 #undef RECURSE
13568 #undef integer_valued_real_p
13570 /* Return true if the floating point expression T has an integer value.
13571 We also allow +Inf, -Inf and NaN to be considered integer values.
13572 Return false for signaling NaN.
13574 DEPTH is the current nesting depth of the query. */
13576 bool
13578 {
13584 {
13600 }
13603 {
13609 {
13618 }
13622 }
13623 }
13625 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13626 attempt to fold the expression to a constant without modifying TYPE,
13627 OP0 or OP1.
13629 If the expression could be simplified to a constant, then return
13630 the constant. If the expression would not be simplified to a
13631 constant, then return NULL_TREE. */
13633 tree
13635 {
13638 }
13640 /* Given the components of a unary expression CODE, TYPE and OP0,
13641 attempt to fold the expression to a constant without modifying
13642 TYPE or OP0.
13644 If the expression could be simplified to a constant, then return
13645 the constant. If the expression would not be simplified to a
13646 constant, then return NULL_TREE. */
13648 tree
13650 {
13653 }
13655 /* If EXP represents referencing an element in a constant string
13656 (either via pointer arithmetic or array indexing), return the
13657 tree representing the value accessed, otherwise return NULL. */
13659 tree
13661 {
13665 {
13667 tree index;
13668 tree string;
13673 else
13674 {
13678 /* Optimize the special-case of a zero lower bound.
13680 We convert the low_bound to sizetype to avoid some problems
13681 with constant folding. (E.g. suppose the lower bound is 1,
13682 and its mode is QI. Without the conversion,l (ARRAY
13683 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13684 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13690 }
13703 }
13705 }
13707 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13708 an integer constant, real, or fixed-point constant.
13710 TYPE is the type of the result. */
13712 static tree
13714 {
13718 {
13720 {
13727 }
13734 {
13735 FIXED_VALUE_TYPE f;
13740 /* Propagate overflow flags. */
13744 }
13748 }
13751 }
13753 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13754 an integer constant or real constant.
13756 TYPE is the type of the result. */
13758 tree
13760 {
13764 {
13766 {
13767 /* If the value is unsigned or non-negative, then the absolute value
13768 is the same as the ordinary value. */
13772 /* If the value is negative, then the absolute value is
13773 its negation. */
13774 else
13775 {
13780 }
13781 }
13787 else
13793 }
13796 }
13798 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13799 constant. TYPE is the type of the result. */
13801 static tree
13803 {
13807 }
13809 /* Given CODE, a relational operator, the target type, TYPE and two
13810 constant operands OP0 and OP1, return the result of the
13811 relational operation. If the result is not a compile time
13812 constant, then return NULL_TREE. */
13814 static tree
13816 {
13819 /* From here on, the only cases we handle are when the result is
13820 known to be a constant. */
13823 {
13827 /* Handle the cases where either operand is a NaN. */
13829 {
13831 {
13859 }
13862 }
13865 }
13868 {
13872 }
13874 /* Handle equality/inequality of complex constants. */
13876 {
13887 else
13889 }
13892 {
13894 {
13895 /* Have vector comparison with scalar boolean result. */
13899 {
13907 }
13909 }
13916 {
13928 }
13931 }
13933 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13935 To compute GT, swap the arguments and do LT.
13936 To compute GE, do LT and invert the result.
13937 To compute LE, swap the arguments, do LT and invert the result.
13938 To compute NE, do EQ and invert the result.
13940 Therefore, the code below must handle only EQ and LT. */
13943 {
13946 }
13948 /* Note that it is safe to invert for real values here because we
13949 have already handled the one case that it matters. */
13953 {
13956 }
13958 /* Compute a result for LT or EQ if args permit;
13959 Otherwise return T. */
13961 {
13964 else
13966 }
13967 else
13973 }
13975 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13976 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13977 itself. */
13979 tree
13981 {
13982 /* If the expression does not have side effects then we don't have to wrap
13983 it with a cleanup point expression. */
13987 /* If the expression is a return, check to see if the expression inside the
13988 return has no side effects or the right hand side of the modify expression
13989 inside the return. If either don't have side effects set we don't need to
13990 wrap the expression in a cleanup point expression. Note we don't check the
13991 left hand side of the modify because it should always be a return decl. */
13993 {
14000 }
14003 }
14005 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14006 of an indirection through OP0, or NULL_TREE if no simplification is
14007 possible. */
14009 tree
14011 {
14013 tree subtype;
14022 {
14025 /* *&CONST_DECL -> to the value of the const decl. */
14028 /* *&p => p; make sure to handle *&"str"[cst] here. */
14030 {
14034 else
14036 }
14037 /* *(foo *)&fooarray => fooarray[0] */
14040 && (!in_gimple_form
14042 {
14052 }
14053 /* *(foo *)&complexfoo => __real__ complexfoo */
14057 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14060 {
14064 }
14065 }
14069 {
14075 {
14076 tree op00type;
14080 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14083 {
14085 unsigned HOST_WIDE_INT max_offset
14090 {
14097 }
14098 }
14099 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14102 {
14106 }
14107 /* ((foo *)&fooarray)[1] => fooarray[1] */
14110 {
14117 offset_int remainder;
14120 {
14125 }
14126 }
14127 }
14128 }
14130 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14133 && (!in_gimple_form
14135 {
14136 tree type_domain;
14146 NULL_TREE);
14147 }
14150 }
14152 /* Builds an expression for an indirection through T, simplifying some
14153 cases. */
14155 tree
14157 {
14165 }
14167 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14169 tree
14171 {
14176 else
14178 }
14180 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14181 whose result is ignored. The type of the returned tree need not be
14182 the same as the original expression. */
14184 tree
14186 {
14192 {
14203 else
14209 {
14225 }
14230 }
14231 }
14233 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14235 tree
14237 {
14243 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14244 have to do anything. Only do this when we are not given a const,
14245 because in that case, this check is more expensive than just
14246 doing it. */
14248 {
14253 }
14255 /* If divisor is a power of two, simplify this to bit manipulation. */
14257 {
14259 {
14273 }
14274 else
14275 {
14276 tree t;
14282 }
14283 }
14284 else
14285 {
14290 }
14293 }
14295 /* Likewise, but round down. */
14297 tree
14299 {
14306 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14307 have to do anything. Only do this when we are not given a const,
14308 because in that case, this check is more expensive than just
14309 doing it. */
14311 {
14316 }
14318 /* If divisor is a power of two, simplify this to bit manipulation. */
14320 {
14321 tree t;
14325 }
14326 else
14327 {
14332 }
14335 }
14337 /* Returns the pointer to the base of the object addressed by EXP and
14338 extracts the information about the offset of the access, storing it
14339 to PBITPOS and POFFSET. */
14341 static tree
14344 {
14345 tree core;
14346 machine_mode mode;
14348 HOST_WIDE_INT bitsize;
14352 {
14357 }
14359 {
14365 {
14370 {
14373 }
14374 }
14375 }
14376 else
14377 {
14381 }
14384 }
14386 /* Returns true if addresses of E1 and E2 differ by a constant, false
14387 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14389 bool
14391 {
14405 {
14415 }
14417 {
14418 /* If only one of the offsets is non-constant, the difference cannot
14419 be a constant. */
14421 }
14422 else
14427 }
14429 /* Return OFF converted to a pointer offset type suitable as offset for
14430 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14431 tree
14433 {
14435 }
14437 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14438 tree
14440 {
14443 }
14445 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14446 tree
14448 {
14451 }
14453 /* Return a char pointer for a C string if it is a string constant
14454 or sum of string constant and integer constant. We only support
14455 string constants properly terminated with '\0' character.
14456 If STRLEN is a valid pointer, length (including terminating character)
14457 of returned string is stored to the argument. */
14461 {
14462 tree offset_node;
14473 {
14476 else
14478 }
14483 /* Support only properly null-terminated strings. */
14492 }
14494 #if CHECKING_P
14498 /* Helper functions for writing tests of folding trees. */
14500 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14502 static void
14504 tree constant)
14505 {
14507 }
14509 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14510 wrapping WRAPPED_EXPR. */
14512 static void
14514 tree wrapped_expr)
14515 {
14520 }
14522 /* Verify that various arithmetic binary operations are folded
14523 correctly. */
14525 static void
14527 {
14533 /* Addition. */
14534 /* 1 <-- (0 + 1) */
14536 one);
14538 one);
14540 /* (nonlvalue)x <-- (x + 0) */
14542 x);
14544 /* Subtraction. */
14545 /* 0 <-- (x - x) */
14547 zero);
14549 x);
14551 /* Multiplication. */
14552 /* 0 <-- (x * 0) */
14554 zero);
14556 /* (nonlvalue)x <-- (x * 1) */
14558 x);
14559 }
14561 /* Verify that various binary operations on vectors are folded
14562 correctly. */
14564 static void
14566 {
14572 /* Verify equality tests that return a scalar boolean result. */
14578 }
14580 /* Run all of the selftests within this file. */
14582 void
14584 {
14587 }