| blob | bece8d74b46b64afad8ee9465b4b50f80a87ccad |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2016 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
80 #ifndef LOAD_EXTEND_OP
81 #define LOAD_EXTEND_OP(M) UNKNOWN
82 #endif
84 /* Nonzero if we are folding constants inside an initializer; zero
85 otherwise. */
88 /* The following constants represent a bit based encoding of GCC's
89 comparison operators. This encoding simplifies transformations
90 on relational comparison operators, such as AND and OR. */
108 };
124 HOST_WIDE_INT *,
153 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
154 Otherwise, return LOC. */
156 static location_t
158 {
161 }
163 /* Similar to protected_set_expr_location, but never modify x in place,
164 if location can and needs to be set, unshare it. */
168 {
174 {
177 }
179 }
180 \f
181 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
182 division and returns the quotient. Otherwise returns
183 NULL_TREE. */
185 tree
187 {
188 widest_int quo;
195 }
196 \f
197 /* This is nonzero if we should defer warnings about undefined
198 overflow. This facility exists because these warnings are a
199 special case. The code to estimate loop iterations does not want
200 to issue any warnings, since it works with expressions which do not
201 occur in user code. Various bits of cleanup code call fold(), but
202 only use the result if it has certain characteristics (e.g., is a
203 constant); that code only wants to issue a warning if the result is
204 used. */
208 /* If a warning about undefined overflow is deferred, this is the
209 warning. Note that this may cause us to turn two warnings into
210 one, but that is fine since it is sufficient to only give one
211 warning per expression. */
215 /* If a warning about undefined overflow is deferred, this is the
216 level at which the warning should be emitted. */
220 /* Start deferring overflow warnings. We could use a stack here to
221 permit nested calls, but at present it is not necessary. */
223 void
225 {
227 }
229 /* Stop deferring overflow warnings. If there is a pending warning,
230 and ISSUE is true, then issue the warning if appropriate. STMT is
231 the statement with which the warning should be associated (used for
232 location information); STMT may be NULL. CODE is the level of the
233 warning--a warn_strict_overflow_code value. This function will use
234 the smaller of CODE and the deferred code when deciding whether to
235 issue the warning. CODE may be zero to mean to always use the
236 deferred code. */
238 void
240 {
242 location_t locus;
247 {
253 }
264 /* Use the smallest code level when deciding to issue the
265 warning. */
274 else
277 }
279 /* Stop deferring overflow warnings, ignoring any deferred
280 warnings. */
282 void
284 {
286 }
288 /* Whether we are deferring overflow warnings. */
290 bool
292 {
294 }
296 /* This is called when we fold something based on the fact that signed
297 overflow is undefined. */
299 static void
301 {
303 {
306 {
309 }
310 }
313 }
314 \f
315 /* Return true if the built-in mathematical function specified by CODE
316 is odd, i.e. -f(x) == f(-x). */
318 bool
320 {
322 {
323 CASE_CFN_ASIN:
324 CASE_CFN_ASINH:
325 CASE_CFN_ATAN:
326 CASE_CFN_ATANH:
327 CASE_CFN_CASIN:
328 CASE_CFN_CASINH:
329 CASE_CFN_CATAN:
330 CASE_CFN_CATANH:
331 CASE_CFN_CBRT:
332 CASE_CFN_CPROJ:
333 CASE_CFN_CSIN:
334 CASE_CFN_CSINH:
335 CASE_CFN_CTAN:
336 CASE_CFN_CTANH:
337 CASE_CFN_ERF:
338 CASE_CFN_LLROUND:
339 CASE_CFN_LROUND:
340 CASE_CFN_ROUND:
341 CASE_CFN_SIN:
342 CASE_CFN_SINH:
343 CASE_CFN_TAN:
344 CASE_CFN_TANH:
345 CASE_CFN_TRUNC:
348 CASE_CFN_LLRINT:
349 CASE_CFN_LRINT:
350 CASE_CFN_NEARBYINT:
351 CASE_CFN_RINT:
356 }
358 }
360 /* Check whether we may negate an integer constant T without causing
361 overflow. */
363 bool
365 {
366 tree type;
375 }
377 /* Determine whether an expression T can be cheaply negated using
378 the function negate_expr without introducing undefined overflow. */
380 static bool
382 {
383 tree type;
392 {
397 /* Check that -CST will not overflow type. */
410 /* We want to canonicalize to positive real constants. Pretend
411 that only negative ones can be easily negated. */
419 {
430 }
445 /* -(A + B) -> (-B) - A. */
450 /* -(A + B) -> (-A) - B. */
454 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
465 /* INT_MIN/n * n doesn't overflow while negating one operand it does
466 if n is a power of two. */
475 /* Fall through. */
490 /* In general we can't negate B in A / B, because if A is INT_MIN and
491 B is 1, we may turn this into INT_MIN / -1 which is undefined
492 and actually traps on some architectures. */
501 /* Negate -((double)float) as (double)(-float). */
503 {
507 }
511 /* Negate -f(x) as f(-x). */
517 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
519 {
523 }
528 }
530 }
532 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
533 simplification is possible.
534 If negate_expr_p would return true for T, NULL_TREE will never be
535 returned. */
537 static tree
539 {
541 tree tem;
544 {
545 /* Convert - (~A) to A + 1. */
571 {
576 }
580 {
585 {
589 }
592 }
615 {
616 /* -(A + B) -> (-B) - A. */
620 {
624 }
626 /* -(A + B) -> (-A) - B. */
628 {
632 }
633 }
637 /* - (A - B) -> B - A */
649 /* Fall through. */
653 {
662 }
674 /* In general we can't negate B in A / B, because if A is INT_MIN and
675 B is 1, we may turn this into INT_MIN / -1 which is undefined
676 and actually traps on some architectures. */
688 /* Convert -((double)float) into (double)(-float). */
690 {
694 }
698 /* Negate -f(x) as f(-x). */
701 {
707 }
711 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
713 {
716 {
723 }
724 }
729 }
732 }
734 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
735 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
736 return NULL_TREE. */
738 static tree
740 {
742 location_t loc;
755 }
756 \f
757 /* Split a tree IN into a constant, literal and variable parts that could be
758 combined with CODE to make IN. "constant" means an expression with
759 TREE_CONSTANT but that isn't an actual constant. CODE must be a
760 commutative arithmetic operation. Store the constant part into *CONP,
761 the literal in *LITP and return the variable part. If a part isn't
762 present, set it to null. If the tree does not decompose in this way,
763 return the entire tree as the variable part and the other parts as null.
765 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
766 case, we negate an operand that was subtracted. Except if it is a
767 literal for which we use *MINUS_LITP instead.
769 If NEGATE_P is true, we are negating all of IN, again except a literal
770 for which we use *MINUS_LITP instead.
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
780 {
787 /* Strip any conversions that don't change the machine mode or signedness. */
796 /* We can associate addition and subtraction together (even
797 though the C standard doesn't say so) for integers because
798 the value is not affected. For reals, the value might be
799 affected, so we can't. */
802 {
808 /* First see if either of the operands is a literal, then a constant. */
821 /* If we haven't dealt with either operand, this is not a case we can
822 decompose. Otherwise, VAR is either of the ones remaining, if any. */
827 else
830 /* Now do any needed negations. */
837 }
840 {
841 /* -X - 1 is folded to ~X, undo that here. */
844 }
847 else
851 {
858 }
861 }
863 /* Re-associate trees split by the above function. T1 and T2 are
864 either expressions to associate or null. Return the new
865 expression, if any. LOC is the location of the new expression. If
866 we build an operation, do it in TYPE and with CODE. */
868 static tree
870 {
876 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
877 try to fold this since we will have infinite recursion. But do
878 deal with any NEGATE_EXPRs. */
881 {
883 {
896 }
898 {
901 }
905 }
909 }
910 \f
911 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
912 for use in int_const_binop, size_binop and size_diffop. */
914 static bool
916 {
923 {
932 }
937 }
940 /* Combine two integer constants ARG1 and ARG2 under operation CODE
941 to produce a new constant. Return NULL_TREE if we don't know how
942 to evaluate CODE at compile-time. */
944 static tree
947 {
948 wide_int res;
949 tree t;
958 {
974 {
978 else
980 }
983 /* It's unclear from the C standard whether shifts can overflow.
984 The following code ignores overflow; perhaps a C standard
985 interpretation ruling is needed. */
987 else
994 {
998 else
1000 }
1004 else
1083 }
1091 }
1093 tree
1095 {
1097 }
1099 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1100 constant. We assume ARG1 and ARG2 have the same data type, or at least
1101 are the same kind of constant and the same machine mode. Return zero if
1102 combining the constants is not allowed in the current operating mode. */
1104 static tree
1106 {
1107 /* Sanity check for the recursive cases. */
1115 {
1121 }
1124 {
1125 machine_mode mode;
1126 REAL_VALUE_TYPE d1;
1127 REAL_VALUE_TYPE d2;
1128 REAL_VALUE_TYPE value;
1129 REAL_VALUE_TYPE result;
1133 /* The following codes are handled by real_arithmetic. */
1135 {
1146 }
1154 /* Don't perform operation if we honor signaling NaNs and
1155 either operand is a signaling NaN. */
1161 /* Don't perform operation if it would raise a division
1162 by zero exception. */
1168 /* If either operand is a NaN, just return it. Otherwise, set up
1169 for floating-point trap; we return an overflow. */
1171 {
1172 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1173 is off. */
1177 }
1179 {
1180 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1181 is off. */
1185 }
1190 /* Don't constant fold this floating point operation if
1191 the result has overflowed and flag_trapping_math. */
1199 /* Don't constant fold this floating point operation if the
1200 result may dependent upon the run-time rounding mode and
1201 flag_rounding_math is set, or if GCC's software emulation
1202 is unable to accurately represent the result. */
1212 }
1215 {
1216 FIXED_VALUE_TYPE f1;
1217 FIXED_VALUE_TYPE f2;
1218 FIXED_VALUE_TYPE result;
1223 /* The following codes are handled by fixed_arithmetic. */
1225 {
1237 {
1244 }
1249 }
1256 /* Propagate overflow flags. */
1260 }
1263 {
1272 {
1283 mpc_mul);
1297 mpc_div);
1298 /* Fallthru ... */
1304 {
1305 /* Keep this algorithm in sync with
1306 tree-complex.c:expand_complex_div_straight().
1308 Expand complex division to scalars, straightforward algorithm.
1309 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1310 t = br*br + bi*bi
1311 */
1312 tree magsquared
1316 tree t1
1320 tree t2
1327 }
1328 else
1329 {
1330 /* Keep this algorithm in sync with
1331 tree-complex.c:expand_complex_div_wide().
1333 Expand complex division to scalars, modified algorithm to minimize
1334 overflow with wide input ranges. */
1340 {
1341 /* In the TRUE branch, we compute
1342 ratio = br/bi;
1343 div = (br * ratio) + bi;
1344 tr = (ar * ratio) + ai;
1345 ti = (ai * ratio) - ar;
1346 tr = tr / div;
1347 ti = ti / div; */
1358 }
1359 else
1360 {
1361 /* In the FALSE branch, we compute
1362 ratio = d/c;
1363 divisor = (d * ratio) + c;
1364 tr = (b * ratio) + a;
1365 ti = b - (a * ratio);
1366 tr = tr / div;
1367 ti = ti / div; */
1379 }
1380 }
1385 }
1389 }
1393 {
1399 {
1405 /* It is possible that const_binop cannot handle the given
1406 code and return NULL_TREE */
1409 }
1412 }
1414 /* Shifts allow a scalar offset for a vector. */
1417 {
1423 {
1428 /* It is possible that const_binop cannot handle the given
1429 code and return NULL_TREE. */
1432 }
1435 }
1437 }
1439 /* Overload that adds a TYPE parameter to be able to dispatch
1440 to fold_relational_const. */
1442 tree
1444 {
1448 /* ??? Until we make the const_binop worker take the type of the
1449 result as argument put those cases that need it here. */
1451 {
1462 {
1478 {
1484 }
1487 }
1493 {
1518 {
1531 }
1534 }
1537 }
1542 /* Make sure type and arg0 have the same saturating flag. */
1547 }
1549 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1550 Return zero if computing the constants is not possible. */
1552 tree
1554 {
1555 /* Don't perform the operation, other than NEGATE and ABS, if
1556 flag_signaling_nans is on and the operand is a signaling NaN. */
1565 {
1566 CASE_CONVERT:
1573 /* If the source address is 0, and the source address space
1574 cannot have a valid object at 0, fold to dest type null. */
1585 {
1586 /* Can't call fold_negate_const directly here as that doesn't
1587 handle all cases and we might not be able to negate some
1588 constants. */
1593 }
1602 {
1606 }
1612 /* Perform BIT_NOT_EXPR on each element individually. */
1614 {
1616 tree elem;
1621 {
1627 }
1630 }
1652 {
1671 else
1675 {
1679 }
1682 }
1687 {
1701 {
1706 }
1709 {
1713 }
1716 }
1720 }
1723 }
1725 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1726 indicates which particular sizetype to create. */
1728 tree
1730 {
1732 }
1733 \f
1734 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1735 is a tree code. The type of the result is taken from the operands.
1736 Both must be equivalent integer types, ala int_binop_types_match_p.
1737 If the operands are constant, so is the result. */
1739 tree
1741 {
1750 /* Handle the special case of two integer constants faster. */
1752 {
1753 /* And some specific cases even faster than that. */
1755 {
1760 }
1762 {
1765 }
1767 {
1770 }
1772 /* Handle general case of two integer constants. For sizetype
1773 constant calculations we always want to know about overflow,
1774 even in the unsigned case. */
1776 }
1779 }
1781 /* Given two values, either both of sizetype or both of bitsizetype,
1782 compute the difference between the two values. Return the value
1783 in signed type corresponding to the type of the operands. */
1785 tree
1787 {
1789 tree ctype;
1794 /* If the type is already signed, just do the simple thing. */
1802 else
1805 /* If either operand is not a constant, do the conversions to the signed
1806 type and subtract. The hardware will do the right thing with any
1807 overflow in the subtraction. */
1813 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1814 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1815 overflow) and negate (which can't either). Special-case a result
1816 of zero while we're here. */
1822 else
1826 MINUS_EXPR,
1828 }
1829 \f
1830 /* A subroutine of fold_convert_const handling conversions of an
1831 INTEGER_CST to another integer type. */
1833 static tree
1835 {
1836 /* Given an integer constant, make new constant with new type,
1837 appropriately sign-extended or truncated. Use widest_int
1838 so that any extension is done according ARG1's type. */
1842 }
1844 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1845 to an integer type. */
1847 static tree
1849 {
1851 tree t;
1853 /* The following code implements the floating point to integer
1854 conversion rules required by the Java Language Specification,
1855 that IEEE NaNs are mapped to zero and values that overflow
1856 the target precision saturate, i.e. values greater than
1857 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1858 are mapped to INT_MIN. These semantics are allowed by the
1859 C and C++ standards that simply state that the behavior of
1860 FP-to-integer conversion is unspecified upon overflow. */
1862 wide_int val;
1863 REAL_VALUE_TYPE r;
1867 {
1874 }
1876 /* If R is NaN, return zero and show we have an overflow. */
1878 {
1881 }
1883 /* See if R is less than the lower bound or greater than the
1884 upper bound. */
1887 {
1891 {
1894 }
1895 }
1898 {
1901 {
1904 {
1907 }
1908 }
1909 }
1916 }
1918 /* A subroutine of fold_convert_const handling conversions of a
1919 FIXED_CST to an integer type. */
1921 static tree
1923 {
1924 tree t;
1928 /* Right shift FIXED_CST to temp by fbit. */
1932 {
1934 HOST_BITS_PER_DOUBLE_INT,
1937 /* Left shift temp to temp_trunc by fbit. */
1939 HOST_BITS_PER_DOUBLE_INT,
1941 }
1942 else
1943 {
1946 }
1948 /* If FIXED_CST is negative, we need to round the value toward 0.
1949 By checking if the fractional bits are not zero to add 1 to temp. */
1955 /* Given a fixed-point constant, make new constant with new type,
1956 appropriately sign-extended or truncated. */
1964 }
1966 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1967 to another floating point type. */
1969 static tree
1971 {
1972 REAL_VALUE_TYPE value;
1973 tree t;
1975 /* Don't perform the operation if flag_signaling_nans is on
1976 and the operand is a signaling NaN. */
1984 /* If converting an infinity or NAN to a representation that doesn't
1985 have one, set the overflow bit so that we can produce some kind of
1986 error message at the appropriate point if necessary. It's not the
1987 most user-friendly message, but it's better than nothing. */
1994 /* Regular overflow, conversion produced an infinity in a mode that
1995 can't represent them. */
2000 else
2003 }
2005 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2006 to a floating point type. */
2008 static tree
2010 {
2011 REAL_VALUE_TYPE value;
2012 tree t;
2019 }
2021 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2022 to another fixed-point type. */
2024 static tree
2026 {
2027 FIXED_VALUE_TYPE value;
2028 tree t;
2035 /* Propagate overflow flags. */
2039 }
2041 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2042 to a fixed-point type. */
2044 static tree
2046 {
2047 FIXED_VALUE_TYPE value;
2048 tree t;
2050 double_int di;
2057 else
2065 /* Propagate overflow flags. */
2069 }
2071 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2072 to a fixed-point type. */
2074 static tree
2076 {
2077 FIXED_VALUE_TYPE value;
2078 tree t;
2086 /* Propagate overflow flags. */
2090 }
2092 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2093 type TYPE. If no simplification can be done return NULL_TREE. */
2095 static tree
2097 {
2103 {
2110 }
2112 {
2119 }
2121 {
2128 }
2130 {
2133 {
2138 {
2144 }
2146 }
2147 }
2149 }
2151 /* Construct a vector of zero elements of vector type TYPE. */
2153 static tree
2155 {
2156 tree t;
2160 }
2162 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2164 bool
2166 {
2181 {
2197 }
2198 }
2200 /* Convert expression ARG to type TYPE. Used by the middle-end for
2201 simple conversions in preference to calling the front-end's convert. */
2203 tree
2205 {
2207 tree tem;
2218 {
2221 /* Handle conversions between pointers to different address spaces. */
2226 /* fall through */
2231 {
2235 }
2249 {
2253 }
2255 {
2259 }
2261 {
2265 }
2268 {
2286 }
2291 {
2295 }
2298 {
2312 }
2316 {
2325 integer_zero_node));
2327 {
2331 {
2337 }
2345 }
2349 }
2367 }
2368 fold_convert_exit:
2371 }
2372 \f
2373 /* Return false if expr can be assumed not to be an lvalue, true
2374 otherwise. */
2376 static bool
2378 {
2379 /* We only need to wrap lvalue tree codes. */
2381 {
2412 /* Assume the worst for front-end tree codes. */
2416 }
2419 }
2421 /* Return an expr equal to X but certainly not valid as an lvalue. */
2423 tree
2425 {
2426 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2427 us. */
2434 }
2436 /* When pedantic, return an expr equal to X but certainly not valid as a
2437 pedantic lvalue. Otherwise, return X. */
2439 static tree
2441 {
2443 }
2444 \f
2445 /* Given a tree comparison code, return the code that is the logical inverse.
2446 It is generally not safe to do this for floating-point comparisons, except
2447 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2448 ERROR_MARK in this case. */
2450 enum tree_code
2452 {
2458 {
2489 }
2490 }
2492 /* Similar, but return the comparison that results if the operands are
2493 swapped. This is safe for floating-point. */
2495 enum tree_code
2497 {
2499 {
2525 }
2526 }
2529 /* Convert a comparison tree code from an enum tree_code representation
2530 into a compcode bit-based encoding. This function is the inverse of
2531 compcode_to_comparison. */
2533 static enum comparison_code
2535 {
2537 {
2568 }
2569 }
2571 /* Convert a compcode bit-based encoding of a comparison operator back
2572 to GCC's enum tree_code representation. This function is the
2573 inverse of comparison_to_compcode. */
2575 static enum tree_code
2577 {
2579 {
2610 }
2611 }
2613 /* Return a tree for the comparison which is the combination of
2614 doing the AND or OR (depending on CODE) of the two operations LCODE
2615 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2616 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2617 if this makes the transformation invalid. */
2619 tree
2624 {
2631 {
2642 }
2645 {
2646 /* Eliminate unordered comparisons, as well as LTGT and ORD
2647 which are not used unless the mode has NaNs. */
2653 }
2655 {
2656 /* Check that the original operation and the optimized ones will trap
2657 under the same condition. */
2668 /* In a short-circuited boolean expression the LHS might be
2669 such that the RHS, if evaluated, will never trap. For
2670 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2671 if neither x nor y is NaN. (This is a mixed blessing: for
2672 example, the expression above will never trap, hence
2673 optimizing it to x < y would be invalid). */
2678 /* If the comparison was short-circuited, and only the RHS
2679 trapped, we may now generate a spurious trap. */
2684 /* If we changed the conditions that cause a trap, we lose. */
2687 }
2693 else
2694 {
2699 }
2700 }
2701 \f
2702 /* Return nonzero if two operands (typically of the same tree node)
2703 are necessarily equal. FLAGS modifies behavior as follows:
2705 If OEP_ONLY_CONST is set, only return nonzero for constants.
2706 This function tests whether the operands are indistinguishable;
2707 it does not test whether they are equal using C's == operation.
2708 The distinction is important for IEEE floating point, because
2709 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2710 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2712 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2713 even though it may hold multiple values during a function.
2714 This is because a GCC tree node guarantees that nothing else is
2715 executed between the evaluation of its "operands" (which may often
2716 be evaluated in arbitrary order). Hence if the operands themselves
2717 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2718 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2719 unset means assuming isochronic (or instantaneous) tree equivalence.
2720 Unless comparing arbitrary expression trees, such as from different
2721 statements, this flag can usually be left unset.
2723 If OEP_PURE_SAME is set, then pure functions with identical arguments
2724 are considered the same. It is used when the caller has other ways
2725 to ensure that global memory is unchanged in between.
2727 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2728 not values of expressions.
2730 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2731 any operand with side effect. This is unnecesarily conservative in the
2732 case we know that arg0 and arg1 are in disjoint code paths (such as in
2733 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2734 addresses with TREE_CONSTANT flag set so we know that &var == &var
2735 even if var is volatile. */
2737 int
2739 {
2740 /* If either is ERROR_MARK, they aren't equal. */
2746 /* Similar, if either does not have a type (like a released SSA name),
2747 they aren't equal. */
2751 /* We cannot consider pointers to different address space equal. */
2758 /* Check equality of integer constants before bailing out due to
2759 precision differences. */
2761 {
2762 /* Address of INTEGER_CST is not defined; check that we did not forget
2763 to drop the OEP_ADDRESS_OF flags. */
2766 }
2769 {
2770 /* If both types don't have the same signedness, then we can't consider
2771 them equal. We must check this before the STRIP_NOPS calls
2772 because they may change the signedness of the arguments. As pointers
2773 strictly don't have a signedness, require either two pointers or
2774 two non-pointers as well. */
2780 /* If both types don't have the same precision, then it is not safe
2781 to strip NOPs. */
2788 }
2789 #if 0
2790 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2791 sanity check once the issue is solved. */
2792 else
2793 /* Addresses of conversions and SSA_NAMEs (and many other things)
2794 are not defined. Check that we did not forget to drop the
2795 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2798 #endif
2800 /* In case both args are comparisons but with different comparison
2801 code, try to swap the comparison operands of one arg to produce
2802 a match and compare that variant. */
2806 {
2814 }
2817 {
2818 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2820 ;
2822 {
2823 /* If we are interested in comparing addresses ignore
2824 MEM_REF wrappings of the base that can appear just for
2825 TBAA reasons. */
2839 }
2840 else
2842 }
2844 /* When not checking adddresses, this is needed for conversions and for
2845 COMPONENT_REF. Might as well play it safe and always test this. */
2852 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2853 We don't care about side effects in that case because the SAVE_EXPR
2854 takes care of that for us. In all other cases, two expressions are
2855 equal if they have no side effects. If we have two identical
2856 expressions with side effects that should be treated the same due
2857 to the only side effects being identical SAVE_EXPR's, that will
2858 be detected in the recursive calls below.
2859 If we are taking an invariant address of two identical objects
2860 they are necessarily equal as well. */
2867 /* Next handle constant cases, those for which we can return 1 even
2868 if ONLY_CONST is set. */
2871 {
2885 {
2886 /* If we do not distinguish between signed and unsigned zero,
2887 consider them equal. */
2890 }
2894 {
2901 {
2905 }
2907 }
2911 flags)
2913 flags));
2924 flags | OEP_ADDRESS_OF
2927 /* In GIMPLE empty constructors are allowed in initializers of
2928 aggregates. */
2933 }
2938 /* Define macros to test an operand from arg0 and arg1 for equality and a
2939 variant that allows null and views null as being different from any
2940 non-null value. In the latter case, if either is null, the both
2941 must be; otherwise, do the normal comparison. */
2942 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2943 TREE_OPERAND (arg1, N), flags)
2945 #define OP_SAME_WITH_NULL(N) \
2946 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2947 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2950 {
2952 /* Two conversions are equal only if signedness and modes match. */
2954 {
2955 CASE_CONVERT:
2963 }
2973 /* For commutative ops, allow the other order. */
2981 /* If either of the pointer (or reference) expressions we are
2982 dereferencing contain a side effect, these cannot be equal,
2983 but their addresses can be. */
2990 {
3007 {
3008 /* Require equal access sizes */
3014 flags)))
3016 /* Verify that accesses are TBAA compatible. */
3025 /* Verify that alignment is compatible. */
3029 }
3032 /* TARGET_MEM_REF require equal extra operands. */
3040 /* Operands 2 and 3 may be null.
3041 Compare the array index by value if it is constant first as we
3042 may have different types but same value here. */
3053 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3054 may be NULL when we're called to compare MEM_EXPRs. */
3069 }
3073 {
3075 /* Be sure we pass right ADDRESS_OF flag. */
3093 /* The multiplcation operands are commutative. */
3094 /* FALLTHRU */
3102 /* Otherwise take into account this is a commutative operation. */
3115 }
3119 {
3123 /* If not both CALL_EXPRs are either internal or normal function
3124 functions, then they are not equal. */
3127 {
3128 /* If the CALL_EXPRs call different internal functions, then they
3129 are not equal. */
3132 }
3133 else
3134 {
3135 /* If the CALL_EXPRs call different functions, then they are not
3136 equal. */
3138 flags))
3140 }
3142 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3143 {
3147 else
3151 }
3153 /* Now see if all the arguments are the same. */
3154 {
3165 /* If we get here and both argument lists are exhausted
3166 then the CALL_EXPRs are equal. */
3168 }
3171 }
3174 /* Consider __builtin_sqrt equal to sqrt. */
3182 {
3183 /* In GIMPLE constructors are used only to build vectors from
3184 elements. Individual elements in the constructor must be
3185 indexed in increasing order and form an initial sequence.
3187 We make no effort to compare constructors in generic.
3188 (see sem_variable::equals in ipa-icf which can do so for
3189 constants). */
3194 /* Be sure that vectors constructed have the same representation.
3195 We only tested element precision and modes to match.
3196 Vectors may be BLKmode and thus also check that the number of
3197 parts match. */
3210 {
3215 /* In GIMPLE the indexes can be either NULL or matching i.
3216 Double check this so we won't get false
3217 positives for GENERIC. */
3225 }
3227 }
3232 }
3234 #undef OP_SAME
3235 #undef OP_SAME_WITH_NULL
3236 }
3237 \f
3238 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3239 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3241 When in doubt, return 0. */
3243 static int
3245 {
3257 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3258 and see if the inner values are the same. This removes any
3259 signedness comparison, which doesn't matter here. */
3266 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3267 actual comparison operand, ARG0.
3269 First throw away any conversions to wider types
3270 already present in the operands. */
3279 {
3282 /* Make sure shorter operand is extended the right way
3283 to match the longer operand. */
3289 }
3292 }
3293 \f
3294 /* See if ARG is an expression that is either a comparison or is performing
3295 arithmetic on comparisons. The comparisons must only be comparing
3296 two different values, which will be stored in *CVAL1 and *CVAL2; if
3297 they are nonzero it means that some operands have already been found.
3298 No variables may be used anywhere else in the expression except in the
3299 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3300 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3302 If this is true, return 1. Otherwise, return zero. */
3304 static int
3306 {
3310 /* We can handle some of the tcc_expression cases here. */
3320 {
3321 /* If we've already found a CVAL1 or CVAL2, this expression is
3322 two complex to handle. */
3328 }
3331 {
3354 /* First see if we can handle the first operand, then the second. For
3355 the second operand, we know *CVAL1 can't be zero. It must be that
3356 one side of the comparison is each of the values; test for the
3357 case where this isn't true by failing if the two operands
3358 are the same. */
3367 ;
3371 ;
3372 else
3376 ;
3380 ;
3381 else
3388 }
3389 }
3390 \f
3391 /* ARG is a tree that is known to contain just arithmetic operations and
3392 comparisons. Evaluate the operations in the tree substituting NEW0 for
3393 any occurrence of OLD0 as an operand of a comparison and likewise for
3394 NEW1 and OLD1. */
3396 static tree
3399 {
3404 /* We can handle some of the tcc_expression cases here. */
3412 {
3427 {
3446 }
3447 /* Fall through - ??? */
3450 {
3454 /* We need to check both for exact equality and tree equality. The
3455 former will be true if the operand has a side-effect. In that
3456 case, we know the operand occurred exactly once. */
3469 }
3473 }
3474 }
3475 \f
3476 /* Return a tree for the case when the result of an expression is RESULT
3477 converted to TYPE and OMITTED was previously an operand of the expression
3478 but is now not needed (e.g., we folded OMITTED * 0).
3480 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3481 the conversion of RESULT to TYPE. */
3483 tree
3485 {
3488 /* If the resulting operand is an empty statement, just return the omitted
3489 statement casted to void. */
3499 }
3501 /* Return a tree for the case when the result of an expression is RESULT
3502 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3503 of the expression but are now not needed.
3505 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3506 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3507 evaluated before OMITTED2. Otherwise, if neither has side effects,
3508 just do the conversion of RESULT to TYPE. */
3510 tree
3513 {
3522 }
3524 \f
3525 /* Return a simplified tree node for the truth-negation of ARG. This
3526 never alters ARG itself. We assume that ARG is an operation that
3527 returns a truth value (0 or 1).
3529 FIXME: one would think we would fold the result, but it causes
3530 problems with the dominator optimizer. */
3532 static tree
3534 {
3539 /* If this is a comparison, we can simply invert it, except for
3540 floating-point non-equality comparisons, in which case we just
3541 enclose a TRUTH_NOT_EXPR around what we have. */
3544 {
3547 && flag_trapping_math
3558 }
3561 {
3580 /* Here we can invert either operand. We invert the first operand
3581 unless the second operand is a TRUTH_NOT_EXPR in which case our
3582 result is the XOR of the first operand with the inside of the
3583 negation of the second operand. */
3588 else
3611 {
3618 /* A COND_EXPR may have a throw as one operand, which
3619 then has void type. Just leave void operands
3620 as they are. */
3626 }
3638 CASE_CONVERT:
3642 /* ... fall through ... */
3664 }
3665 }
3667 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3668 assume that ARG is an operation that returns a truth value (0 or 1
3669 for scalars, 0 or -1 for vectors). Return the folded expression if
3670 folding is successful. Otherwise, return NULL_TREE. */
3672 static tree
3674 {
3677 ? BIT_NOT_EXPR
3680 }
3682 /* Return a simplified tree node for the truth-negation of ARG. This
3683 never alters ARG itself. We assume that ARG is an operation that
3684 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3686 tree
3688 {
3694 ? BIT_NOT_EXPR
3697 }
3699 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3700 with code CODE. This optimization is unsafe. */
3701 static tree
3704 {
3708 /* (A / C) +- (B / C) -> (A +- B) / C. */
3718 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3723 {
3735 }
3738 }
3739 \f
3740 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3741 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3742 and uses reverse storage order if REVERSEP is nonzero. */
3744 static tree
3748 {
3752 {
3759 }
3774 }
3776 /* Optimize a bit-field compare.
3778 There are two cases: First is a compare against a constant and the
3779 second is a comparison of two items where the fields are at the same
3780 bit position relative to the start of a chunk (byte, halfword, word)
3781 large enough to contain it. In these cases we can avoid the shift
3782 implicit in bitfield extractions.
3784 For constants, we emit a compare of the shifted constant with the
3785 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3786 compared. For two fields at the same position, we do the ANDs with the
3787 similar mask and compare the result of the ANDs.
3789 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3790 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3791 are the left and right operands of the comparison, respectively.
3793 If the optimization described above can be done, we return the resulting
3794 tree. Otherwise we return zero. */
3796 static tree
3799 {
3802 tree unsigned_type;
3809 tree mask;
3810 tree offset;
3812 /* Get all the information about the extractions being done. If the bit size
3813 if the same as the size of the underlying object, we aren't doing an
3814 extraction at all and so can do nothing. We also don't want to
3815 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3816 then will no longer be able to replace it. */
3825 else
3826 {
3827 /* If this is not a constant, we can only do something if bit positions,
3828 sizes, signedness and storage order are the same. */
3829 rinner
3837 }
3839 /* See if we can find a mode to refer to this field. We should be able to,
3840 but fail if we can't. */
3849 /* Set signed and unsigned types of the precision of this mode for the
3850 shifts below. */
3853 /* Compute the bit position and size for the new reference and our offset
3854 within it. If the new reference is the same size as the original, we
3855 won't optimize anything, so return zero. */
3865 /* Make the mask to be used against the extracted field. */
3872 /* If not comparing with constant, just rework the comparison
3873 and return. */
3877 unsigned_type,
3880 mask),
3883 unsigned_type,
3886 mask));
3888 /* Otherwise, we are handling the constant case. See if the constant is too
3889 big for the field. Warn and return a tree for 0 (false) if so. We do
3890 this not only for its own sake, but to avoid having to test for this
3891 error case below. If we didn't, we might generate wrong code.
3893 For unsigned fields, the constant shifted right by the field length should
3894 be all zero. For signed fields, the high-order bits should agree with
3895 the sign bit. */
3898 {
3900 {
3904 }
3905 }
3906 else
3907 {
3910 {
3914 }
3915 }
3917 /* Single-bit compares should always be against zero. */
3919 {
3922 }
3924 /* Make a new bitfield reference, shift the constant over the
3925 appropriate number of bits and mask it with the computed mask
3926 (in case this was a signed field). If we changed it, make a new one. */
3928 lreversep);
3934 mask);
3939 }
3940 \f
3941 /* Subroutine for fold_truth_andor_1: decode a field reference.
3943 If EXP is a comparison reference, we return the innermost reference.
3945 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3946 set to the starting bit number.
3948 If the innermost field can be completely contained in a mode-sized
3949 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3951 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3952 otherwise it is not changed.
3954 *PUNSIGNEDP is set to the signedness of the field.
3956 *PREVERSEP is set to the storage order of the field.
3958 *PMASK is set to the mask used. This is either contained in a
3959 BIT_AND_EXPR or derived from the width of the field.
3961 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3963 Return 0 if this is not a component reference or is one that we can't
3964 do anything with. */
3966 static tree
3971 {
3975 tree unsigned_type;
3978 /* All the optimizations using this function assume integer fields.
3979 There are problems with FP fields since the type_for_size call
3980 below can fail for, e.g., XFmode. */
3984 /* We are interested in the bare arrangement of bits, so strip everything
3985 that doesn't affect the machine mode. However, record the type of the
3986 outermost expression if it may matter below. */
3993 {
3999 }
4008 /* If the number of bits in the reference is the same as the bitsize of
4009 the outer type, then the outer type gives the signedness. Otherwise
4010 (in case of a small bitfield) the signedness is unchanged. */
4014 /* Compute the mask to access the bitfield. */
4023 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4031 }
4033 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4034 bit positions and MASK is SIGNED. */
4036 static int
4038 {
4042 /* If this function returns true when the type of the mask is
4043 UNSIGNED, then there will be errors. In particular see
4044 gcc.c-torture/execute/990326-1.c. There does not appear to be
4045 any documentation paper trail as to why this is so. But the pre
4046 wide-int worked with that restriction and it has been preserved
4047 here. */
4052 }
4054 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4055 represents the sign bit of EXP's type. If EXP represents a sign
4056 or zero extension, also test VAL against the unextended type.
4057 The return value is the (sub)expression whose sign bit is VAL,
4058 or NULL_TREE otherwise. */
4060 tree
4062 {
4064 tree t;
4066 /* Tree EXP must have an integral type. */
4071 /* Tree VAL must be an integer constant. */
4080 /* Handle extension from a narrower type. */
4086 }
4088 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4089 to be evaluated unconditionally. */
4091 static int
4093 {
4094 /* Strip any conversions that don't change the machine mode. */
4103 /* Don't regard global variables as simple. They may be
4104 allocated in ways unknown to the compiler (shared memory,
4105 #pragma weak, etc). */
4108 /* Weakrefs are not safe to be read, since they can be NULL.
4109 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4110 have DECL_WEAK flag set. */
4112 /* Loading a static variable is unduly expensive, but global
4113 registers aren't expensive. */
4115 }
4117 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4118 to be evaluated unconditionally.
4119 I addition to simple_operand_p, we assume that comparisons, conversions,
4120 and logic-not operations are simple, if their operands are simple, too. */
4122 static bool
4124 {
4144 }
4146 \f
4147 /* The following functions are subroutines to fold_range_test and allow it to
4148 try to change a logical combination of comparisons into a range test.
4150 For example, both
4151 X == 2 || X == 3 || X == 4 || X == 5
4152 and
4153 X >= 2 && X <= 5
4154 are converted to
4155 (unsigned) (X - 2) <= 3
4157 We describe each set of comparisons as being either inside or outside
4158 a range, using a variable named like IN_P, and then describe the
4159 range with a lower and upper bound. If one of the bounds is omitted,
4160 it represents either the highest or lowest value of the type.
4162 In the comments below, we represent a range by two numbers in brackets
4163 preceded by a "+" to designate being inside that range, or a "-" to
4164 designate being outside that range, so the condition can be inverted by
4165 flipping the prefix. An omitted bound is represented by a "-". For
4166 example, "- [-, 10]" means being outside the range starting at the lowest
4167 possible value and ending at 10, in other words, being greater than 10.
4168 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4169 always false.
4171 We set up things so that the missing bounds are handled in a consistent
4172 manner so neither a missing bound nor "true" and "false" need to be
4173 handled using a special case. */
4175 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4176 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4177 and UPPER1_P are nonzero if the respective argument is an upper bound
4178 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4179 must be specified for a comparison. ARG1 will be converted to ARG0's
4180 type if both are specified. */
4182 static tree
4185 {
4186 tree tem;
4190 /* If neither arg represents infinity, do the normal operation.
4191 Else, if not a comparison, return infinity. Else handle the special
4192 comparison rules. Note that most of the cases below won't occur, but
4193 are handled for consistency. */
4196 {
4201 }
4206 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4207 for neither. In real maths, we cannot assume open ended ranges are
4208 the same. But, this is computer arithmetic, where numbers are finite.
4209 We can therefore make the transformation of any unbounded range with
4210 the value Z, Z being greater than any representable number. This permits
4211 us to treat unbounded ranges as equal. */
4215 {
4236 }
4239 }
4240 \f
4241 /* Helper routine for make_range. Perform one step for it, return
4242 new expression if the loop should continue or NULL_TREE if it should
4243 stop. */
4245 tree
4249 {
4255 {
4257 /* We can only do something if the range is testing for zero. */
4266 /* We can only do something if the range is testing for zero
4267 and if the second operand is an integer constant. Note that
4268 saying something is "in" the range we make is done by
4269 complementing IN_P since it will set in the initial case of
4270 being not equal to zero; "out" is leaving it alone. */
4277 {
4298 }
4300 /* If this is an unsigned comparison, we also know that EXP is
4301 greater than or equal to zero. We base the range tests we make
4302 on that fact, so we record it here so we can parse existing
4303 range tests. We test arg0_type since often the return type
4304 of, e.g. EQ_EXPR, is boolean. */
4306 {
4310 NULL_TREE))
4315 /* If the high bound is missing, but we have a nonzero low
4316 bound, reverse the range so it goes from zero to the low bound
4317 minus 1. */
4319 {
4324 }
4325 }
4333 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4334 low and high are non-NULL, then normalize will DTRT. */
4337 {
4342 }
4344 /* (-x) IN [a,b] -> x in [-b, -a] */
4356 /* ~ X -> -X - 1 */
4365 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4366 move a constant to the other side. */
4371 /* If EXP is signed, any overflow in the computation is undefined,
4372 so we don't worry about it so long as our computations on
4373 the bounds don't overflow. For unsigned, overflow is defined
4374 and this is exactly the right thing. */
4386 normalize:
4387 /* Check for an unsigned range which has wrapped around the maximum
4388 value thus making n_high < n_low, and normalize it. */
4390 {
4396 /* If the range is of the form +/- [ x+1, x ], we won't
4397 be able to normalize it. But then, it represents the
4398 whole range or the empty set, so make it
4399 +/- [ -, - ]. */
4403 else
4405 }
4406 else
4414 CASE_CONVERT:
4432 /* If we're converting arg0 from an unsigned type, to exp,
4433 a signed type, we will be doing the comparison as unsigned.
4434 The tests above have already verified that LOW and HIGH
4435 are both positive.
4437 So we have to ensure that we will handle large unsigned
4438 values the same way that the current signed bounds treat
4439 negative values. */
4442 {
4443 tree high_positive;
4444 tree equiv_type;
4445 /* For fixed-point modes, we need to pass the saturating flag
4446 as the 2nd parameter. */
4448 equiv_type
4451 else
4452 equiv_type
4455 /* A range without an upper bound is, naturally, unbounded.
4456 Since convert would have cropped a very large value, use
4457 the max value for the destination type. */
4458 high_positive
4465 high_positive),
4468 /* If the low bound is specified, "and" the range with the
4469 range for which the original unsigned value will be
4470 positive. */
4472 {
4475 integer_zero_node),
4476 high_positive))
4480 }
4481 else
4482 {
4483 /* Otherwise, "or" the range with the range of the input
4484 that will be interpreted as negative. */
4487 integer_zero_node),
4488 high_positive))
4492 }
4493 }
4502 }
4503 }
4505 /* Given EXP, a logical expression, set the range it is testing into
4506 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4507 actually being tested. *PLOW and *PHIGH will be made of the same
4508 type as the returned expression. If EXP is not a comparison, we
4509 will most likely not be returning a useful value and range. Set
4510 *STRICT_OVERFLOW_P to true if the return value is only valid
4511 because signed overflow is undefined; otherwise, do not change
4512 *STRICT_OVERFLOW_P. */
4514 tree
4517 {
4525 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4526 and see if we can refine the range. Some of the cases below may not
4527 happen, but it doesn't seem worth worrying about this. We "continue"
4528 the outer loop when we've changed something; otherwise we "break"
4529 the switch, which will "break" the while. */
4535 {
4541 {
4549 }
4558 }
4560 /* If EXP is a constant, we can evaluate whether this is true or false. */
4562 {
4569 }
4573 }
4574 \f
4575 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4576 type, TYPE, return an expression to test if EXP is in (or out of, depending
4577 on IN_P) the range. Return 0 if the test couldn't be created. */
4579 tree
4582 {
4585 /* Disable this optimization for function pointer expressions
4586 on targets that require function pointer canonicalization. */
4593 {
4599 }
4617 {
4619 {
4623 }
4625 }
4627 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4629 {
4633 {
4635 {
4638 etype
4640 else
4643 }
4646 }
4647 }
4649 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4650 This requires wrap-around arithmetics for the type of the expression.
4651 First make sure that arithmetics in this type is valid, then make sure
4652 that it wraps around. */
4658 {
4661 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4662 for the type in question, as we rely on this here. */
4672 else
4674 }
4684 {
4686 {
4691 }
4693 }
4701 }
4702 \f
4703 /* Return the predecessor of VAL in its type, handling the infinite case. */
4705 static tree
4707 {
4713 else
4716 }
4718 /* Return the successor of VAL in its type, handling the infinite case. */
4720 static tree
4722 {
4728 else
4731 }
4733 /* Given two ranges, see if we can merge them into one. Return 1 if we
4734 can, 0 if we can't. Set the output range into the specified parameters. */
4736 bool
4739 {
4743 tree tem;
4753 /* Make range 0 be the range that starts first, or ends last if they
4754 start at the same value. Swap them if it isn't. */
4757 || (lowequal
4760 {
4764 }
4766 /* Now flag two cases, whether the ranges are disjoint or whether the
4767 second range is totally subsumed in the first. Note that the tests
4768 below are simplified by the ones above. */
4774 /* We now have four cases, depending on whether we are including or
4775 excluding the two ranges. */
4777 {
4778 /* If they don't overlap, the result is false. If the second range
4779 is a subset it is the result. Otherwise, the range is from the start
4780 of the second to the end of the first. */
4785 else
4787 }
4790 {
4791 /* If they don't overlap, the result is the first range. If they are
4792 equal, the result is false. If the second range is a subset of the
4793 first, and the ranges begin at the same place, we go from just after
4794 the end of the second range to the end of the first. If the second
4795 range is not a subset of the first, or if it is a subset and both
4796 ranges end at the same place, the range starts at the start of the
4797 first range and ends just before the second range.
4798 Otherwise, we can't describe this as a single range. */
4804 {
4809 {
4810 /* We are in the weird situation where high0 > high1 but
4811 high1 has no successor. Punt. */
4813 }
4814 }
4816 {
4821 {
4822 /* low0 < low1 but low1 has no predecessor. Punt. */
4824 }
4825 }
4826 else
4828 }
4831 {
4832 /* If they don't overlap, the result is the second range. If the second
4833 is a subset of the first, the result is false. Otherwise,
4834 the range starts just after the first range and ends at the
4835 end of the second. */
4840 else
4841 {
4846 {
4847 /* high1 > high0 but high0 has no successor. Punt. */
4849 }
4850 }
4851 }
4853 else
4854 {
4855 /* The case where we are excluding both ranges. Here the complex case
4856 is if they don't overlap. In that case, the only time we have a
4857 range is if they are adjacent. If the second is a subset of the
4858 first, the result is the first. Otherwise, the range to exclude
4859 starts at the beginning of the first range and ends at the end of the
4860 second. */
4862 {
4867 else
4868 {
4869 /* Canonicalize - [min, x] into - [-, x]. */
4872 {
4877 /* FALLTHROUGH */
4890 }
4892 /* Canonicalize - [x, max] into - [x, -]. */
4895 {
4900 /* FALLTHROUGH */
4916 }
4918 /* The ranges might be also adjacent between the maximum and
4919 minimum values of the given type. For
4920 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4921 return + [x + 1, y - 1]. */
4923 {
4930 }
4931 else
4933 }
4934 }
4937 else
4939 }
4943 }
4944 \f
4946 /* Subroutine of fold, looking inside expressions of the form
4947 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4948 of the COND_EXPR. This function is being used also to optimize
4949 A op B ? C : A, by reversing the comparison first.
4951 Return a folded expression whose code is not a COND_EXPR
4952 anymore, or NULL_TREE if no folding opportunity is found. */
4954 static tree
4957 {
4962 tree tem;
4967 /* If we have A op 0 ? A : -A, consider applying the following
4968 transformations:
4970 A == 0? A : -A same as -A
4971 A != 0? A : -A same as A
4972 A >= 0? A : -A same as abs (A)
4973 A > 0? A : -A same as abs (A)
4974 A <= 0? A : -A same as -abs (A)
4975 A < 0? A : -A same as -abs (A)
4977 None of these transformations work for modes with signed
4978 zeros. If A is +/-0, the first two transformations will
4979 change the sign of the result (from +0 to -0, or vice
4980 versa). The last four will fix the sign of the result,
4981 even though the original expressions could be positive or
4982 negative, depending on the sign of A.
4984 Note that all these transformations are correct if A is
4985 NaN, since the two alternatives (A and -A) are also NaNs. */
4992 /* In the case that A is of the form X-Y, '-A' (arg2) may
4993 have already been folded to Y-X, check for that. */
5001 {
5015 /* Fall through. */
5035 }
5037 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5038 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5039 both transformations are correct when A is NaN: A != 0
5040 is then true, and A == 0 is false. */
5044 {
5049 }
5051 /* Try some transformations of A op B ? A : B.
5053 A == B? A : B same as B
5054 A != B? A : B same as A
5055 A >= B? A : B same as max (A, B)
5056 A > B? A : B same as max (B, A)
5057 A <= B? A : B same as min (A, B)
5058 A < B? A : B same as min (B, A)
5060 As above, these transformations don't work in the presence
5061 of signed zeros. For example, if A and B are zeros of
5062 opposite sign, the first two transformations will change
5063 the sign of the result. In the last four, the original
5064 expressions give different results for (A=+0, B=-0) and
5065 (A=-0, B=+0), but the transformed expressions do not.
5067 The first two transformations are correct if either A or B
5068 is a NaN. In the first transformation, the condition will
5069 be false, and B will indeed be chosen. In the case of the
5070 second transformation, the condition A != B will be true,
5071 and A will be chosen.
5073 The conversions to max() and min() are not correct if B is
5074 a number and A is not. The conditions in the original
5075 expressions will be false, so all four give B. The min()
5076 and max() versions would give a NaN instead. */
5079 /* Avoid these transformations if the COND_EXPR may be used
5080 as an lvalue in the C++ front-end. PR c++/19199. */
5081 && (in_gimple_form
5087 {
5092 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
5094 {
5098 }
5101 {
5110 /* In C++ a ?: expression can be an lvalue, so put the
5111 operand which will be used if they are equal first
5112 so that we can convert this back to the
5113 corresponding COND_EXPR. */
5115 {
5124 }
5131 {
5140 }
5155 }
5156 }
5158 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
5159 we might still be able to simplify this. For example,
5160 if C1 is one less or one more than C2, this might have started
5161 out as a MIN or MAX and been transformed by this function.
5162 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
5168 {
5172 /* We can replace A with C1 in this case. */
5177 /* If C1 is C2 + 1, this is min(A, C2), but use ARG00's type for
5178 MIN_EXPR, to preserve the signedness of the comparison. */
5180 OEP_ONLY_CONST)
5184 OEP_ONLY_CONST))
5185 {
5188 arg2));
5191 }
5195 /* If C1 is C2 - 1, this is min(A, C2), with the same care
5196 as above. */
5198 OEP_ONLY_CONST)
5202 OEP_ONLY_CONST))
5203 {
5206 arg2));
5209 }
5213 /* If C1 is C2 - 1, this is max(A, C2), but use ARG00's type for
5214 MAX_EXPR, to preserve the signedness of the comparison. */
5216 OEP_ONLY_CONST)
5220 OEP_ONLY_CONST))
5221 {
5224 arg2));
5226 }
5230 /* If C1 is C2 + 1, this is max(A, C2), with the same care as above. */
5232 OEP_ONLY_CONST)
5236 OEP_ONLY_CONST))
5237 {
5240 arg2));
5242 }
5248 }
5251 }
5254 \f
5255 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5256 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5257 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5258 false) >= 2)
5259 #endif
5261 /* EXP is some logical combination of boolean tests. See if we can
5262 merge it into some range test. Return the new tree if so. */
5264 static tree
5267 {
5283 /* If this is an OR operation, invert both sides; we will invert
5284 again at the end. */
5288 /* If both expressions are the same, if we can merge the ranges, and we
5289 can build the range test, return it or it inverted. If one of the
5290 ranges is always true or always false, consider it to be the same
5291 expression as the other. */
5299 {
5303 }
5305 /* On machines where the branch cost is expensive, if this is a
5306 short-circuited branch and the underlying object on both sides
5307 is the same, make a non-short-circuit operation. */
5313 {
5314 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5315 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5316 which cases we can't do this. */
5324 {
5333 {
5336 WARN_STRICT_OVERFLOW_COMPARISON);
5340 }
5341 }
5342 }
5345 }
5346 \f
5347 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5348 bit value. Arrange things so the extra bits will be set to zero if and
5349 only if C is signed-extended to its full width. If MASK is nonzero,
5350 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5352 static tree
5354 {
5357 tree temp;
5362 /* We work by getting just the sign bit into the low-order bit, then
5363 into the high-order bit, then sign-extend. We then XOR that value
5364 with C. */
5367 /* We must use a signed type in order to get an arithmetic right shift.
5368 However, we must also avoid introducing accidental overflows, so that
5369 a subsequent call to integer_zerop will work. Hence we must
5370 do the type conversion here. At this point, the constant is either
5371 zero or one, and the conversion to a signed type can never overflow.
5372 We could get an overflow if this conversion is done anywhere else. */
5381 /* If necessary, convert the type back to match the type of C. */
5386 }
5387 \f
5388 /* For an expression that has the form
5389 (A && B) || ~B
5390 or
5391 (A || B) && ~B,
5392 we can drop one of the inner expressions and simplify to
5393 A || ~B
5394 or
5395 A && ~B
5396 LOC is the location of the resulting expression. OP is the inner
5397 logical operation; the left-hand side in the examples above, while CMPOP
5398 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5399 removing a condition that guards another, as in
5400 (A != NULL && A->...) || A == NULL
5401 which we must not transform. If RHS_ONLY is true, only eliminate the
5402 right-most operand of the inner logical operation. */
5404 static tree
5407 {
5425 {
5428 {
5431 }
5432 }
5434 {
5437 {
5440 }
5441 }
5456 }
5458 /* Find ways of folding logical expressions of LHS and RHS:
5459 Try to merge two comparisons to the same innermost item.
5460 Look for range tests like "ch >= '0' && ch <= '9'".
5461 Look for combinations of simple terms on machines with expensive branches
5462 and evaluate the RHS unconditionally.
5464 For example, if we have p->a == 2 && p->b == 4 and we can make an
5465 object large enough to span both A and B, we can do this with a comparison
5466 against the object ANDed with the a mask.
5468 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5469 operations to do this with one comparison.
5471 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5472 function and the one above.
5474 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5475 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5477 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5478 two operands.
5480 We return the simplified tree or 0 if no optimization is possible. */
5482 static tree
5485 {
5486 /* If this is the "or" of two comparisons, we can do something if
5487 the comparisons are NE_EXPR. If this is the "and", we can do something
5488 if the comparisons are EQ_EXPR. I.e.,
5489 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5491 WANTED_CODE is this operation code. For single bit fields, we can
5492 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5493 comparison for one-bit fields. */
5514 /* Start by getting the comparison codes. Fail if anything is volatile.
5515 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5516 it were surrounded with a NE_EXPR. */
5525 {
5529 }
5532 {
5536 }
5547 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5550 {
5553 {
5558 }
5561 {
5567 }
5568 }
5573 /* If the RHS can be evaluated unconditionally and its operands are
5574 simple, it wins to evaluate the RHS unconditionally on machines
5575 with expensive branches. In this case, this isn't a comparison
5576 that can be merged. */
5583 {
5584 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5595 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5605 }
5607 /* See if the comparisons can be merged. Then get all the parameters for
5608 each side. */
5633 /* It must be true that the inner operation on the lhs of each
5634 comparison must be the same if we are to be able to do anything.
5635 Then see if we have constants. If not, the same must be true for
5636 the rhs's. */
5645 {
5648 }
5653 else
5656 /* If either comparison code is not correct for our logical operation,
5657 fail. However, we can convert a one-bit comparison against zero into
5658 the opposite comparison against that bit being set in the field. */
5662 {
5664 {
5665 /* Make the left operand unsigned, since we are only interested
5666 in the value of one bit. Otherwise we are doing the wrong
5667 thing below. */
5670 }
5671 else
5673 }
5675 /* This is analogous to the code for l_const above. */
5677 {
5679 {
5682 }
5683 else
5685 }
5687 /* See if we can find a mode that contains both fields being compared on
5688 the left. If we can't, fail. Otherwise, update all constants and masks
5689 to be relative to a field of that size. */
5694 volatilep);
5704 {
5707 }
5715 {
5722 {
5726 }
5727 }
5729 {
5736 {
5740 }
5741 }
5743 /* If the right sides are not constant, do the same for it. Also,
5744 disallow this optimization if a size or signedness mismatch occurs
5745 between the left and right sides. */
5747 {
5750 /* Make sure the two fields on the right
5751 correspond to the left without being swapped. */
5759 volatilep);
5769 {
5772 }
5781 /* Make a mask that corresponds to both fields being compared.
5782 Do this for both items being compared. If the operands are the
5783 same size and the bits being compared are in the same position
5784 then we can do this by masking both and comparing the masked
5785 results. */
5789 {
5801 }
5803 /* There is still another way we can do something: If both pairs of
5804 fields being compared are adjacent, we may be able to make a wider
5805 field containing them both.
5807 Note that we still must mask the lhs/rhs expressions. Furthermore,
5808 the mask must be shifted to account for the shift done by
5809 make_bit_field_ref. */
5814 {
5815 tree type;
5831 /* Convert to the smaller type before masking out unwanted bits. */
5834 {
5836 {
5840 }
5842 {
5846 }
5847 }
5856 }
5859 }
5861 /* Handle the case of comparisons with constants. If there is something in
5862 common between the masks, those bits of the constants must be the same.
5863 If not, the condition is always false. Test for this to avoid generating
5864 incorrect code below. */
5869 {
5871 {
5874 }
5875 else
5876 {
5879 }
5880 }
5882 /* Construct the expression we will return. First get the component
5883 reference we will make. Unless the mask is all ones the width of
5884 that field, perform the mask operation. Then compare with the
5885 merged constant. */
5895 }
5896 \f
5897 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5898 constant. */
5900 static tree
5903 {
5906 tree comp_const;
5907 tree minmax_const;
5909 tree inner;
5920 /* If something does not permit us to optimize, return the original tree. */
5928 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5929 and GT_EXPR, doing the rest with recursive calls using logical
5930 simplifications. */
5932 {
5934 {
5935 tree tem
5942 }
5945 return
5947 optimize_minmax_comparison
5949 optimize_minmax_comparison
5954 /* MAX (X, 0) == 0 -> X <= 0 */
5958 /* MAX (X, 0) == 5 -> X == 5 */
5962 /* MAX (X, 0) == -1 -> false */
5966 /* MIN (X, 0) == 0 -> X >= 0 */
5970 /* MIN (X, 0) == 5 -> false */
5973 else
5974 /* MIN (X, 0) == -1 -> X == -1 */
5979 /* MAX (X, 0) > 0 -> X > 0
5980 MAX (X, 0) > 5 -> X > 5 */
5984 /* MAX (X, 0) > -1 -> true */
5988 /* MIN (X, 0) > 0 -> false
5989 MIN (X, 0) > 5 -> false */
5992 else
5993 /* MIN (X, 0) > -1 -> X > -1 */
5998 }
5999 }
6000 \f
6001 /* T is an integer expression that is being multiplied, divided, or taken a
6002 modulus (CODE says which and what kind of divide or modulus) by a
6003 constant C. See if we can eliminate that operation by folding it with
6004 other operations already in T. WIDE_TYPE, if non-null, is a type that
6005 should be used for the computation if wider than our type.
6007 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6008 (X * 2) + (Y * 4). We must, however, be assured that either the original
6009 expression would not overflow or that overflow is undefined for the type
6010 in the language in question.
6012 If we return a non-null expression, it is an equivalent form of the
6013 original computation, but need not be in the original type.
6015 We set *STRICT_OVERFLOW_P to true if the return values depends on
6016 signed overflow being undefined. Otherwise we do not change
6017 *STRICT_OVERFLOW_P. */
6019 static tree
6022 {
6023 /* To avoid exponential search depth, refuse to allow recursion past
6024 three levels. Beyond that (1) it's highly unlikely that we'll find
6025 something interesting and (2) we've probably processed it before
6026 when we built the inner expression. */
6029 tree ret;
6034 depth++;
6036 depth--;
6039 }
6041 static tree
6044 {
6055 /* Don't deal with constants of zero here; they confuse the code below. */
6065 /* Note that we need not handle conditional operations here since fold
6066 already handles those cases. So just do arithmetic here. */
6068 {
6070 /* For a constant, we can always simplify if we are a multiply
6071 or (for divide and modulus) if it is a multiple of our constant. */
6074 {
6077 /* If the multiplication overflowed to INT_MIN then we lost sign
6078 information on it and a subsequent multiplication might
6079 spuriously overflow. See PR68142. */
6084 }
6088 /* If op0 is an expression ... */
6094 /* ... and has wrapping overflow, and its type is smaller
6095 than ctype, then we cannot pass through as widening. */
6100 /* ... or this is a truncation (t is narrower than op0),
6101 then we cannot pass through this narrowing. */
6104 /* ... or signedness changes for division or modulus,
6105 then we cannot pass through this conversion. */
6109 /* ... or has undefined overflow while the converted to
6110 type has not, we cannot do the operation in the inner type
6111 as that would introduce undefined overflow. */
6117 /* Pass the constant down and see if we can make a simplification. If
6118 we can, replace this expression with the inner simplification for
6119 possible later conversion to our or some other type. */
6124 code == MULT_EXPR
6126 strict_overflow_p))))
6131 /* If widening the type changes it from signed to unsigned, then we
6132 must avoid building ABS_EXPR itself as unsigned. */
6134 {
6138 {
6141 }
6143 }
6144 /* If the constant is negative, we cannot simplify this. */
6147 /* FALLTHROUGH */
6149 /* For division and modulus, type can't be unsigned, as e.g.
6150 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6151 For signed types, even with wrapping overflow, this is fine. */
6160 /* If widening the type changes the signedness, then we can't perform
6161 this optimization as that changes the result. */
6165 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6171 {
6178 }
6182 /* If the second operand is constant, this is a multiplication
6183 or floor division, by a power of two, so we can treat it that
6184 way unless the multiplier or divisor overflows. Signed
6185 left-shift overflow is implementation-defined rather than
6186 undefined in C90, so do not convert signed left shift into
6187 multiplication. */
6190 /* const_binop may not detect overflow correctly,
6191 so check for it explicitly here. */
6195 size_one_node,
6196 op1)))
6200 ctype,
6202 t1),
6207 /* See if we can eliminate the operation on both sides. If we can, we
6208 can return a new PLUS or MINUS. If we can't, the only remaining
6209 cases where we can do anything are if the second operand is a
6210 constant. */
6216 /* If not multiplication, we can only do this if both operands
6217 are divisible by c. */
6220 {
6225 }
6227 /* If this was a subtraction, negate OP1 and set it to be an addition.
6228 This simplifies the logic below. */
6230 {
6232 /* If OP1 was not easily negatable, the constant may be OP0. */
6234 {
6237 }
6238 }
6243 /* If either OP1 or C are negative, this optimization is not safe for
6244 some of the division and remainder types while for others we need
6245 to change the code. */
6247 {
6255 }
6257 /* If it's a multiply or a division/modulus operation of a multiple
6258 of our constant, do the operation and verify it doesn't overflow. */
6261 {
6264 /* We allow the constant to overflow with wrapping semantics. */
6268 }
6269 else
6272 /* If we have an unsigned type, we cannot widen the operation since it
6273 will change the result if the original computation overflowed. */
6277 /* If we were able to eliminate our operation from the first side,
6278 apply our operation to the second side and reform the PLUS. */
6282 /* The last case is if we are a multiply. In that case, we can
6283 apply the distributive law to commute the multiply and addition
6284 if the multiplication of the constants doesn't overflow
6285 and overflow is defined. With undefined overflow
6286 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6292 op1);
6297 /* We have a special case here if we are doing something like
6298 (C * 8) % 4 since we know that's zero. */
6301 /* If the multiplication can overflow we cannot optimize this. */
6305 {
6308 }
6310 /* ... fall through ... */
6314 /* If we can extract our operation from the LHS, do so and return a
6315 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6316 do something only if the second operand is a constant. */
6330 /* If these are the same operation types, we can associate them
6331 assuming no overflow. */
6333 {
6343 {
6348 }
6349 }
6351 /* If these operations "cancel" each other, we have the main
6352 optimizations of this pass, which occur when either constant is a
6353 multiple of the other, in which case we replace this with either an
6354 operation or CODE or TCODE.
6356 If we have an unsigned type, we cannot do this since it will change
6357 the result if the original computation overflowed. */
6364 {
6366 {
6373 }
6375 {
6382 }
6383 }
6388 }
6391 }
6392 \f
6393 /* Return a node which has the indicated constant VALUE (either 0 or
6394 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6395 and is of the indicated TYPE. */
6397 tree
6399 {
6408 else
6410 }
6413 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6414 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6415 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6416 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6417 COND is the first argument to CODE; otherwise (as in the example
6418 given here), it is the second argument. TYPE is the type of the
6419 original expression. Return NULL_TREE if no simplification is
6420 possible. */
6422 static tree
6427 {
6437 {
6441 /* If this operand throws an expression, then it does not make
6442 sense to try to perform a logical or arithmetic operation
6443 involving it. */
6448 }
6451 {
6456 }
6457 else
6458 /* Detect the case of mixing vector and scalar types - bail out. */
6464 /* This transformation is only worthwhile if we don't have to wrap ARG
6465 in a SAVE_EXPR and the operation can be simplified without recursing
6466 on at least one of the branches once its pushed inside the COND_EXPR. */
6475 {
6479 else
6481 }
6483 {
6487 else
6489 }
6491 /* Check that we have simplified at least one of the branches. */
6496 }
6498 \f
6499 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6501 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6502 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6503 ADDEND is the same as X.
6505 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6506 and finite. The problematic cases are when X is zero, and its mode
6507 has signed zeros. In the case of rounding towards -infinity,
6508 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6509 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6511 bool
6513 {
6517 /* Don't allow the fold with -fsignaling-nans. */
6521 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6525 /* In a vector or complex, we would need to check the sign of all zeros. */
6529 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6533 /* The mode has signed zeros, and we have to honor their sign.
6534 In this situation, there is only one case we can return true for.
6535 X - 0 is the same as X unless rounding towards -infinity is
6536 supported. */
6538 }
6540 /* Subroutine of fold() that optimizes comparisons of a division by
6541 a nonzero integer constant against an integer constant, i.e.
6542 X/C1 op C2.
6544 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6545 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6546 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6548 The function returns the constant folded tree if a simplification
6549 can be made, and NULL_TREE otherwise. */
6551 static tree
6554 {
6562 /* We have to do this the hard way to detect unsigned overflow.
6563 prod = int_const_binop (MULT_EXPR, arg01, arg1); */
6569 {
6574 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6578 }
6580 {
6584 {
6603 }
6604 }
6605 else
6606 {
6607 /* A negative divisor reverses the relational operators. */
6613 {
6632 }
6633 }
6636 {
6657 {
6660 }
6665 {
6668 }
6673 {
6676 }
6681 {
6684 }
6689 }
6692 }
6695 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6696 equality/inequality test, then return a simplified form of the test
6697 using a sign testing. Otherwise return NULL. TYPE is the desired
6698 result type. */
6700 static tree
6703 tree result_type)
6704 {
6705 /* If this is testing a single bit, we can optimize the test. */
6709 {
6710 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6711 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6715 /* This is only a win if casting to a signed type is cheap,
6716 i.e. when arg00's type is not a partial mode. */
6719 {
6722 result_type,
6725 }
6726 }
6729 }
6731 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6732 equality/inequality test, then return a simplified form of
6733 the test using shifts and logical operations. Otherwise return
6734 NULL. TYPE is the desired result type. */
6736 tree
6739 {
6740 /* If this is testing a single bit, we can optimize the test. */
6744 {
6753 /* First, see if we can fold the single bit test into a sign-bit
6754 test. */
6756 result_type);
6760 /* Otherwise we have (A & C) != 0 where C is a single bit,
6761 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6762 Similarly for (A & C) == 0. */
6764 /* If INNER is a right shift of a constant and it plus BITNUM does
6765 not overflow, adjust BITNUM and INNER. */
6771 {
6774 }
6776 /* If we are going to be able to omit the AND below, we must do our
6777 operations as unsigned. If we must use the AND, we have a choice.
6778 Normally unsigned is faster, but for some machines signed is. */
6796 /* Put the AND last so it can combine with more things. */
6799 /* Make sure to return the proper type. */
6803 }
6805 }
6807 /* Check whether we are allowed to reorder operands arg0 and arg1,
6808 such that the evaluation of arg1 occurs before arg0. */
6810 static bool
6812 {
6819 }
6821 /* Test whether it is preferable two swap two operands, ARG0 and
6822 ARG1, for example because ARG0 is an integer constant and ARG1
6823 isn't. If REORDER is true, only recommend swapping if we can
6824 evaluate the operands in reverse order. */
6826 bool
6828 {
6846 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6847 for commutative and comparison operators. Ensuring a canonical
6848 form allows the optimizers to find additional redundancies without
6849 having to explicitly check for both orderings. */
6855 /* Put SSA_NAMEs last. */
6861 /* Put variables last. */
6868 }
6871 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6872 means A >= Y && A != MAX, but in this case we know that
6873 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6875 static tree
6877 {
6884 else
6893 {
6896 }
6898 {
6901 }
6902 else
6909 {
6910 /* Convert the pointer types into integer before taking the difference. */
6914 }
6915 else
6922 }
6924 /* Fold a sum or difference of at least one multiplication.
6925 Returns the folded tree or NULL if no simplification could be made. */
6927 static tree
6930 {
6934 /* (A * C) +- (B * C) -> (A+-B) * C.
6935 (A * C) +- A -> A * (C+-1).
6936 We are most concerned about the case where C is a constant,
6937 but other combinations show up during loop reduction. Since
6938 it is not difficult, try all four possibilities. */
6941 {
6944 }
6946 {
6949 }
6950 else
6951 {
6952 /* We cannot generate constant 1 for fract. */
6957 }
6959 {
6962 }
6964 {
6966 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6967 the purpose of this canonicalization. */
6971 {
6974 }
6975 else
6977 }
6978 else
6979 {
6980 /* We cannot generate constant 1 for fract. */
6985 }
6997 /* No identical multiplicands; see if we can find a common
6998 power-of-two factor in non-power-of-two multiplies. This
6999 can help in multi-dimensional array access. */
7002 {
7005 tree maybe_same;
7009 /* Move min of absolute values to int11. */
7011 {
7016 }
7017 else
7021 /* The remainder should not be a constant, otherwise we
7022 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7023 increased the number of multiplications necessary. */
7025 {
7033 }
7034 }
7044 }
7046 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7047 specified by EXPR into the buffer PTR of length LEN bytes.
7048 Return the number of bytes placed in the buffer, or zero
7049 upon failure. */
7051 static int
7053 {
7067 {
7069 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7070 number of bytes. */
7074 {
7081 else
7083 }
7084 else
7089 }
7091 }
7094 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7095 specified by EXPR into the buffer PTR of length LEN bytes.
7096 Return the number of bytes placed in the buffer, or zero
7097 upon failure. */
7099 static int
7101 {
7105 FIXED_VALUE_TYPE value;
7121 }
7124 /* Subroutine of native_encode_expr. Encode the REAL_CST
7125 specified by EXPR into the buffer PTR of length LEN bytes.
7126 Return the number of bytes placed in the buffer, or zero
7127 upon failure. */
7129 static int
7131 {
7137 /* There are always 32 bits in each long, no matter the size of
7138 the hosts long. We handle floating point representations with
7139 up to 192 bits. */
7153 {
7158 {
7165 else
7167 }
7168 else
7174 }
7176 }
7178 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7179 specified by EXPR into the buffer PTR of length LEN bytes.
7180 Return the number of bytes placed in the buffer, or zero
7181 upon failure. */
7183 static int
7185 {
7187 tree part;
7202 }
7205 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7206 specified by EXPR into the buffer PTR of length LEN bytes.
7207 Return the number of bytes placed in the buffer, or zero
7208 upon failure. */
7210 static int
7212 {
7222 {
7224 {
7227 }
7238 }
7240 }
7243 /* Subroutine of native_encode_expr. Encode the STRING_CST
7244 specified by EXPR into the buffer PTR of length LEN bytes.
7245 Return the number of bytes placed in the buffer, or zero
7246 upon failure. */
7248 static int
7250 {
7252 HOST_WIDE_INT total_bytes;
7266 {
7269 {
7272 }
7275 }
7276 else
7279 }
7282 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7283 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7284 buffer PTR of length LEN bytes. If OFF is not -1 then start
7285 the encoding at byte offset OFF and encode at most LEN bytes.
7286 Return the number of bytes placed in the buffer, or zero upon failure. */
7288 int
7290 {
7291 /* We don't support starting at negative offset and -1 is special. */
7296 {
7317 }
7318 }
7321 /* Subroutine of native_interpret_expr. Interpret the contents of
7322 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7323 If the buffer cannot be interpreted, return NULL_TREE. */
7325 static tree
7327 {
7337 }
7340 /* Subroutine of native_interpret_expr. Interpret the contents of
7341 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7342 If the buffer cannot be interpreted, return NULL_TREE. */
7344 static tree
7346 {
7348 double_int result;
7349 FIXED_VALUE_TYPE fixed_value;
7359 }
7362 /* Subroutine of native_interpret_expr. Interpret the contents of
7363 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7364 If the buffer cannot be interpreted, return NULL_TREE. */
7366 static tree
7368 {
7372 /* There are always 32 bits in each long, no matter the size of
7373 the hosts long. We handle floating point representations with
7374 up to 192 bits. */
7375 REAL_VALUE_TYPE r;
7386 {
7387 /* Both OFFSET and BYTE index within a long;
7388 bitpos indexes the whole float. */
7391 {
7398 else
7400 }
7401 else
7402 {
7405 {
7406 /* Reverse bytes within each long, or within the entire float
7407 if it's smaller than a long (for HFmode). */
7410 }
7411 }
7415 }
7419 }
7422 /* Subroutine of native_interpret_expr. Interpret the contents of
7423 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7424 If the buffer cannot be interpreted, return NULL_TREE. */
7426 static tree
7428 {
7443 }
7446 /* Subroutine of native_interpret_expr. Interpret the contents of
7447 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7448 If the buffer cannot be interpreted, return NULL_TREE. */
7450 static tree
7452 {
7465 {
7470 }
7472 }
7475 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7476 the buffer PTR of length LEN as a constant of type TYPE. For
7477 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7478 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7479 return NULL_TREE. */
7481 tree
7483 {
7485 {
7507 }
7508 }
7510 /* Returns true if we can interpret the contents of a native encoding
7511 as TYPE. */
7513 static bool
7515 {
7517 {
7530 }
7531 }
7533 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7534 TYPE at compile-time. If we're unable to perform the conversion
7535 return NULL_TREE. */
7537 static tree
7539 {
7540 /* We support up to 512-bit values (for V8DFmode). */
7544 /* Check that the host and target are sane. */
7553 }
7555 /* Build an expression for the address of T. Folds away INDIRECT_REF
7556 to avoid confusing the gimplify process. */
7558 tree
7560 {
7561 /* The size of the object is not relevant when talking about its address. */
7566 {
7571 }
7581 {
7586 }
7587 else
7591 }
7593 /* Build an expression for the address of T. */
7595 tree
7597 {
7601 }
7603 /* Fold a unary expression of code CODE and type TYPE with operand
7604 OP0. Return the folded expression if folding is successful.
7605 Otherwise, return NULL_TREE. */
7607 tree
7609 {
7610 tree tem;
7611 tree arg0;
7619 {
7622 {
7623 /* Don't use STRIP_NOPS, because signedness of argument type
7624 matters. */
7626 }
7627 else
7628 {
7629 /* Strip any conversions that don't change the mode. This
7630 is safe for every expression, except for a comparison
7631 expression because its signedness is derived from its
7632 operands.
7634 Note that this is done as an internal manipulation within
7635 the constant folder, in order to find the simplest
7636 representation of the arguments so that their form can be
7637 studied. In any cases, the appropriate type conversions
7638 should be put back in the tree that will get out of the
7639 constant folder. */
7641 }
7644 {
7647 {
7651 }
7652 }
7653 }
7660 {
7667 {
7681 /* If this was a conversion, and all we did was to move into
7682 inside the COND_EXPR, bring it back out. But leave it if
7683 it is a conversion from integer to integer and the
7684 result precision is no wider than a word since such a
7685 conversion is cheap and may be optimized away by combine,
7686 while it couldn't if it were outside the COND_EXPR. Then return
7687 so we don't get into an infinite recursion loop taking the
7688 conversion out and then back in. */
7700 && (INTEGRAL_TYPE_P
7713 }
7714 }
7717 {
7723 CASE_CONVERT:
7727 {
7728 /* If we have (type) (a CMP b) and type is an integral type, return
7729 new expression involving the new type. Canonicalize
7730 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7731 non-integral type.
7732 Do not fold the result as that would not simplify further, also
7733 folding again results in recursions. */
7743 }
7745 /* Handle (T *)&A.B.C for A being of type T and B and C
7746 living at offset zero. This occurs frequently in
7747 C++ upcasting and then accessing the base. */
7751 {
7753 tree offset;
7754 machine_mode mode;
7756 tree base
7760 /* If the reference was to a (constant) zero offset, we can use
7761 the address of the base if it has the same base type
7762 as the result type and the pointer type is unqualified. */
7769 }
7773 /* Detect assigning a bitfield. */
7775 && DECL_BIT_FIELD
7777 {
7778 /* Don't leave an assignment inside a conversion
7779 unless assigning a bitfield. */
7781 /* First do the assignment, then return converted constant. */
7786 }
7788 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7789 constants (if x has signed type, the sign bit cannot be set
7790 in c). This folds extension into the BIT_AND_EXPR.
7791 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7792 very likely don't have maximal range for their precision and this
7793 transformation effectively doesn't preserve non-maximal ranges. */
7797 {
7808 <= HOST_BITS_PER_WIDE_INT
7810 {
7814 cst &= HOST_WIDE_INT_M1U
7818 && !flag_syntax_only
7821 {
7825 }
7826 }
7828 {
7833 }
7834 }
7836 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7837 cast (T1)X will fold away. We assume that this happens when X itself
7838 is a cast. */
7842 {
7846 return fold_build_pointer_plus_loc
7848 }
7850 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7851 of the same precision, and X is an integer type not narrower than
7852 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7858 {
7864 }
7866 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7867 type of X and Y (integer types only). */
7872 {
7873 /* Be careful not to introduce new overflows. */
7874 tree mult_type;
7877 else
7881 {
7888 }
7889 }
7895 {
7900 }
7911 /* Convert fabs((double)float) into (double)fabsf(float). */
7914 {
7920 targ0));
7921 }
7925 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7944 /* Note that the operand of this must be an int
7945 and its values must be 0 or 1.
7946 ("true" is a fixed value perhaps depending on the language,
7947 but we don't handle values other than 1 correctly yet.) */
7954 /* Fold *&X to X if X is an lvalue. */
7956 {
7963 }
7969 }
7972 /* If the operation was a conversion do _not_ mark a resulting constant
7973 with TREE_OVERFLOW if the original constant was not. These conversions
7974 have implementation defined behavior and retaining the TREE_OVERFLOW
7975 flag here would confuse later passes such as VRP. */
7976 tree
7979 {
7988 }
7990 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7991 operands OP0 and OP1. LOC is the location of the resulting expression.
7992 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7993 Return the folded expression if folding is successful. Otherwise,
7994 return NULL_TREE. */
7995 static tree
7998 {
7999 tree tem;
8001 /* We only do these simplifications if we are optimizing. */
8005 /* Check for things like (A || B) && (A || C). We can convert this
8006 to A || (B && C). Note that either operator can be any of the four
8007 truth and/or operations and the transformation will still be
8008 valid. Also note that we only care about order for the
8009 ANDIF and ORIF operators. If B contains side effects, this
8010 might change the truth-value of A. */
8017 {
8037 /* This case if tricky because we must either have commutative
8038 operators or else A10 must not have side-effects. */
8044 a01);
8045 }
8047 /* See if we can build a range comparison. */
8053 {
8057 }
8061 {
8065 }
8067 /* Check for the possibility of merging component references. If our
8068 lhs is another similar operation, try to merge its rhs with our
8069 rhs. Then try to merge our lhs and rhs. */
8083 {
8090 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8091 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8092 We don't want to pack more than two leafs to a non-IF AND/OR
8093 expression.
8094 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8095 equal to IF-CODE, then we don't want to add right-hand operand.
8096 If the inner right-hand side of left-hand operand has
8097 side-effects, or isn't simple, then we can't add to it,
8098 as otherwise we might destroy if-sequence. */
8101 /* Needed for sequence points to handle trappings, and
8102 side-effects. */
8104 {
8106 arg1);
8108 tem);
8109 }
8110 /* Same as abouve but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8111 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8114 /* Needed for sequence points to handle trappings, and
8115 side-effects. */
8117 {
8122 }
8123 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8124 into (A OR B).
8125 For sequence point consistancy, we need to check for trapping,
8126 and side-effects. */
8130 }
8133 }
8135 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8136 by changing CODE to reduce the magnitude of constants involved in
8137 ARG0 of the comparison.
8138 Returns a canonicalized comparison tree if a simplification was
8139 possible, otherwise returns NULL_TREE.
8140 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8141 valid if signed overflow is undefined. */
8143 static tree
8147 {
8152 /* Match A +- CST code arg1. We can change this only if overflow
8153 is undefined. */
8156 /* In principle pointers also have undefined overflow behavior,
8157 but that causes problems elsewhere. */
8164 /* Identify the constant in arg0 and its sign. */
8168 /* Overflowed constants and zero will cause problems. */
8173 /* See if we can reduce the magnitude of the constant in
8174 arg0 by changing the comparison code. */
8175 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8179 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8183 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8187 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8191 else
8195 /* Now build the constant reduced in magnitude. But not if that
8196 would produce one outside of its types range. */
8212 }
8214 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8215 overflow further. Try to decrease the magnitude of constants involved
8216 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8217 and put sole constants at the second argument position.
8218 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8220 static tree
8223 {
8224 tree t;
8229 /* Try canonicalization by simplifying arg0. */
8234 {
8238 }
8240 /* Try canonicalization by simplifying arg1 using the swapped
8241 comparison. */
8249 }
8251 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8252 space. This is used to avoid issuing overflow warnings for
8253 expressions like &p->x which can not wrap. */
8255 static bool
8257 {
8264 wide_int wi_offset;
8270 else
8286 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8287 array. */
8289 {
8290 HOST_WIDE_INT base_size;
8295 }
8298 }
8300 /* Subroutine of fold_binary. This routine performs all of the
8301 transformations that are common to the equality/inequality
8302 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8303 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8304 fold_binary should call fold_binary. Fold a comparison with
8305 tree code CODE and type TYPE with operands OP0 and OP1. Return
8306 the folded comparison or NULL_TREE. */
8308 static tree
8311 {
8321 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 -+ C1. */
8323 && (equality_code
8330 {
8331 const enum tree_code
8338 /* If the constant operation overflowed this can be
8339 simplified as a comparison against INT_MAX/INT_MIN. */
8342 {
8346 /* Get the sign of the constant on the lhs if the
8347 operation were VARIABLE + CONST1. */
8351 /* The sign of the constant determines if we overflowed
8352 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8353 Canonicalize to the INT_MIN overflow by swapping the comparison
8354 if necessary. */
8358 /* We now can look at the canonicalized case
8359 VARIABLE + 1 CODE2 INT_MIN
8360 and decide on the result. */
8362 {
8366 return
8372 return
8377 }
8378 }
8379 else
8380 {
8383 "when changing X +- C1 cmp C2 to "
8385 WARN_STRICT_OVERFLOW_COMPARISON);
8387 }
8388 }
8390 /* For comparisons of pointers we can decompose it to a compile time
8391 comparison of the base objects and the offsets into the object.
8392 This requires at least one operand being an ADDR_EXPR or a
8393 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8399 {
8402 machine_mode mode;
8406 /* Get base and offset for the access. Strip ADDR_EXPR for
8407 get_inner_reference, but put it back by stripping INDIRECT_REF
8408 off the base object if possible. indirect_baseN will be true
8409 if baseN is not an address but refers to the object itself. */
8412 {
8413 base0
8419 else
8421 }
8423 {
8427 {
8428 base0
8435 else
8437 }
8440 else
8444 {
8450 {
8453 }
8454 }
8455 }
8459 {
8460 base1
8466 else
8468 }
8470 {
8474 {
8475 base1
8482 else
8484 }
8487 else
8491 {
8497 {
8500 }
8501 }
8502 }
8504 /* If we have equivalent bases we might be able to simplify. */
8508 {
8509 /* We can fold this expression to a constant if the non-constant
8510 offset parts are equal. */
8519 {
8525 "occur when comparing P +- C1 with "
8527 WARN_STRICT_OVERFLOW_CONDITIONAL);
8530 {
8544 }
8545 }
8546 /* We can simplify the comparison to a comparison of the variable
8547 offset parts if the constant offset parts are equal.
8548 Be careful to use signed sizetype here because otherwise we
8549 mess with array offsets in the wrong way. This is possible
8550 because pointer arithmetic is restricted to retain within an
8551 object and overflow on pointer differences is undefined as of
8552 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8554 && (equality_code
8557 {
8558 /* By converting to signed sizetype we cover middle-end pointer
8559 arithmetic which operates on unsigned pointer types of size
8560 type size and ARRAY_REF offsets which are properly sign or
8561 zero extended from their type in case it is narrower than
8562 sizetype. */
8565 else
8569 else
8576 "occur when comparing P +- C1 with "
8578 WARN_STRICT_OVERFLOW_COMPARISON);
8581 }
8582 }
8583 /* For equal offsets we can simplify to a comparison of the
8584 base addresses. */
8586 && (indirect_base0
8588 && (indirect_base1
8593 {
8599 }
8600 }
8602 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8603 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8604 the resulting offset is smaller in absolute value than the
8605 original one and has the same sign. */
8614 {
8619 tree cst;
8621 "occur when combining constants around "
8624 /* Put the constant on the side where it doesn't overflow and is
8625 of lower absolute value and of same sign than before. */
8632 {
8635 variable1,
8639 }
8647 {
8653 variable2);
8654 }
8655 }
8661 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8662 constant, we can simplify it. */
8667 {
8671 }
8673 /* If we are comparing an expression that just has comparisons
8674 of two integer values, arithmetic expressions of those comparisons,
8675 and constants, we can simplify it. There are only three cases
8676 to check: the two values can either be equal, the first can be
8677 greater, or the second can be greater. Fold the expression for
8678 those three values. Since each value must be 0 or 1, we have
8679 eight possibilities, each of which corresponds to the constant 0
8680 or 1 or one of the six possible comparisons.
8682 This handles common cases like (a > b) == 0 but also handles
8683 expressions like ((x > y) - (y > x)) > 0, which supposedly
8684 occur in macroized code. */
8687 {
8692 /* Don't handle degenerate cases here; they should already
8693 have been handled anyway. */
8702 {
8706 /* We can't just pass T to eval_subst in case cval1 or cval2
8707 was the same as ARG1. */
8709 tree high_result
8713 arg1);
8714 tree equal_result
8718 arg1);
8719 tree low_result
8723 arg1);
8725 /* All three of these results should be 0 or 1. Confirm they are.
8726 Then use those values to select the proper code to use. */
8731 {
8732 /* Make a 3-bit mask with the high-order bit being the
8733 value for `>', the next for '=', and the low for '<'. */
8737 {
8739 /* Always false. */
8760 /* Always true. */
8762 }
8765 {
8769 }
8771 }
8772 }
8773 }
8775 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8776 into a single range test. */
8784 {
8788 }
8791 }
8794 /* Subroutine of fold_binary. Optimize complex multiplications of the
8795 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8796 argument EXPR represents the expression "z" of type TYPE. */
8798 static tree
8800 {
8805 {
8808 }
8810 {
8813 }
8814 else
8815 {
8819 }
8828 }
8831 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8832 CONSTRUCTOR ARG into array ELTS and return true if successful. */
8834 static bool
8836 {
8840 {
8843 }
8845 {
8851 else
8853 }
8854 else
8860 }
8862 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8863 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8864 NULL_TREE otherwise. */
8866 static tree
8868 {
8885 {
8889 }
8892 {
8898 }
8899 else
8901 }
8903 /* Try to fold a pointer difference of type TYPE two address expressions of
8904 array references AREF0 and AREF1 using location LOC. Return a
8905 simplified expression for the difference or NULL_TREE. */
8907 static tree
8910 {
8915 /* If the bases are array references as well, recurse. If the bases
8916 are pointer indirections compute the difference of the pointers.
8917 If the bases are equal, we are set. */
8920 && (base_offset
8924 && (base_offset
8930 {
8936 base_offset,
8939 }
8941 }
8943 /* If the real or vector real constant CST of type TYPE has an exact
8944 inverse, return it, else return NULL. */
8946 tree
8948 {
8949 REAL_VALUE_TYPE r;
8951 machine_mode mode;
8955 {
8971 {
8976 }
8982 }
8983 }
8985 /* Mask out the tz least significant bits of X of type TYPE where
8986 tz is the number of trailing zeroes in Y. */
8987 static wide_int
8989 {
8994 }
8996 /* Return true when T is an address and is known to be nonzero.
8997 For floating point we further ensure that T is not denormal.
8998 Similar logic is present in nonzero_address in rtlanal.h.
9000 If the return value is based on the assumption that signed overflow
9001 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9002 change *STRICT_OVERFLOW_P. */
9004 static bool
9006 {
9010 /* Doing something useful for floating point would need more work. */
9016 {
9019 strict_overflow_p);
9025 strict_overflow_p);
9033 }
9036 {
9039 strict_overflow_p);
9047 strict_overflow_p);
9062 strict_overflow_p);
9066 strict_overflow_p);
9069 {
9081 }
9085 }
9087 }
9089 /* Return true when T is an address and is known to be nonzero.
9090 Handle warnings about undefined signed overflow. */
9092 static bool
9094 {
9101 "determining that expression is always "
9103 WARN_STRICT_OVERFLOW_MISC);
9105 }
9107 /* Return true if T is known not to be equal to an integer W. */
9109 bool
9111 {
9113 value_range_type rtype;
9115 {
9124 {
9129 }
9134 /* If T has some known zero bits and W has any of those bits set,
9135 then T is known not to be equal to W. */
9143 }
9144 }
9146 /* Fold a binary expression of code CODE and type TYPE with operands
9147 OP0 and OP1. LOC is the location of the resulting expression.
9148 Return the folded expression if folding is successful. Otherwise,
9149 return NULL_TREE. */
9151 tree
9154 {
9169 /* Strip any conversions that don't change the mode. This is
9170 safe for every expression, except for a comparison expression
9171 because its signedness is derived from its operands. So, in
9172 the latter case, only strip conversions that don't change the
9173 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9174 preserved.
9176 Note that this is done as an internal manipulation within the
9177 constant folder, in order to find the simplest representation
9178 of the arguments so that their form can be studied. In any
9179 cases, the appropriate type conversions should be put back in
9180 the tree that will get out of the constant folder. */
9183 {
9186 }
9187 else
9188 {
9191 }
9193 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9194 constant but we can't do arithmetic on them. */
9196 {
9199 {
9203 }
9204 }
9206 /* If this is a commutative operation, and ARG0 is a constant, move it
9207 to ARG1 to reduce the number of tests below. */
9212 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9213 to ARG1 to reduce the number of tests below. */
9222 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9224 First check for cases where an arithmetic operation is applied to a
9225 compound, conditional, or comparison operation. Push the arithmetic
9226 operation inside the compound or conditional to see if any folding
9227 can then be done. Convert comparison to conditional for this purpose.
9228 The also optimizes non-constant cases that used to be done in
9229 expand_expr.
9231 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9232 one of the operands is a comparison and the other is a comparison, a
9233 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9234 code below would make the expression more complex. Change it to a
9235 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9236 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9249 {
9253 boolean_type_node,
9261 }
9265 {
9267 {
9272 tem);
9273 }
9276 {
9281 tem);
9282 }
9287 {
9293 }
9298 {
9304 }
9305 }
9308 {
9310 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9313 {
9319 }
9321 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9324 {
9325 tree base;
9326 HOST_WIDE_INT coffset;
9335 }
9340 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9346 arg1),
9348 arg0)));
9354 {
9355 /* X + (X / CST) * -CST is X % CST. */
9360 {
9369 cst0));
9370 }
9371 }
9373 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9374 one. Make sure the type is not saturating and has the signedness of
9375 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9376 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9383 {
9387 }
9390 {
9391 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9392 (plus (plus (mult) (mult)) (foo)) so that we can
9393 take advantage of the factoring cases below. */
9402 {
9408 else
9421 parg0),
9423 marg)),
9427 return
9433 parg1)));
9434 }
9435 }
9436 else
9437 {
9438 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9439 to __complex__ ( x, y ). This is not the same for SNaNs or
9440 if signed zeros are involved. */
9444 {
9451 {
9455 {
9461 }
9463 {
9469 }
9470 }
9471 }
9479 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9480 We associate floats only if the user has specified
9481 -fassociative-math. */
9485 {
9490 {
9491 tree tree0;
9494 }
9495 }
9496 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9497 We associate floats only if the user has specified
9498 -fassociative-math. */
9502 {
9507 {
9508 tree tree0;
9511 }
9512 }
9513 }
9515 bit_rotate:
9516 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9517 is a rotate of A by C1 bits. */
9518 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9519 is a rotate of A by B bits. */
9520 {
9522 tree rtype;
9531 /* Only create rotates in complete modes. Other cases are not
9532 expanded properly. */
9535 {
9549 {
9553 code0 == LSHIFT_EXPR
9557 }
9559 {
9567 element_precision
9571 return
9574 ? LROTATE_EXPR
9579 }
9581 {
9589 element_precision
9593 return fold_convert_loc
9596 ? LROTATE_EXPR
9600 }
9601 }
9602 }
9604 associate:
9605 /* In most languages, can't associate operations on floats through
9606 parentheses. Rather than remember where the parentheses were, we
9607 don't associate floats at all, unless the user has specified
9608 -fassociative-math.
9609 And, we need to make sure type is not saturating. */
9613 {
9619 /* Split both trees into variables, constants, and literals. Then
9620 associate each group together, the constants with literals,
9621 then the result with variables. This increases the chances of
9622 literals being recombined later and of generating relocatable
9623 expressions for the sum of a constant and literal. */
9628 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9632 /* With undefined overflow prefer doing association in a type
9633 which wraps on overflow, if that is one of the operand types. */
9636 {
9644 }
9646 /* With undefined overflow we can only associate constants with one
9647 variable, and constants whose association doesn't overflow. */
9650 {
9652 {
9658 {
9661 }
9668 {
9671 }
9677 /* The only case we can still associate with two variables
9678 is if they cancel out. */
9682 }
9683 }
9685 /* Only do something if we found more than two objects. Otherwise,
9686 nothing has changed and we risk infinite recursion. */
9692 {
9704 /* Preserve the MINUS_EXPR if the negative part of the literal is
9705 greater than the positive part. Otherwise, the multiplicative
9706 folding code (i.e extract_muldiv) may be fooled in case
9707 unsigned constants are subtracted, like in the following
9708 example: ((X*2 + 4) - 8U)/2. */
9710 {
9714 {
9718 }
9719 else
9720 {
9724 }
9725 }
9727 /* Don't introduce overflows through reassociation. */
9734 {
9736 return
9740 else
9741 {
9744 return
9748 }
9749 }
9752 return
9755 }
9756 }
9761 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9770 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9771 __complex__ ( x, -y ). This is not the same for SNaNs or if
9772 signed zeros are involved. */
9776 {
9783 {
9787 {
9789 arg1r ? arg1r
9794 }
9796 {
9800 arg1i ? arg1i
9803 }
9804 }
9805 }
9807 /* A - B -> A + (-B) if B is easily negatable. */
9811 /* Avoid this transformation if B is a positive REAL_CST. */
9819 /* Fold &a[i] - &a[j] to i-j. */
9824 {
9830 }
9833 && flag_unsafe_math_optimizations
9839 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9840 one. Make sure the type is not saturating and has the signedness of
9841 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9842 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9849 {
9853 }
9859 {
9860 /* Transform x * -C into -x * C if x is easily negatable. */
9870 /* (A + A) * C -> A * 2 * C */
9882 /* ((T) (X /[ex] C)) * C cancels out if the conversion is
9883 sign-changing only. */
9893 {
9896 "occur when simplifying "
9898 WARN_STRICT_OVERFLOW_MISC);
9900 }
9902 /* Optimize z * conj(z) for integer complex numbers. */
9909 }
9910 else
9911 {
9912 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9913 This is not the same for NaNs or if signed zeros are
9914 involved. */
9920 {
9923 return
9929 return
9934 }
9936 /* Optimize z * conj(z) for floating point complex numbers.
9937 Guarded by flag_unsafe_math_optimizations as non-finite
9938 imaginary components don't produce scalar results. */
9949 {
9951 /* Canonicalize x*x as pow(x,2.0), which is expanded as x*x. */
9953 && optimize
9955 {
9959 {
9962 }
9963 }
9964 }
9965 }
9969 /* Canonicalize (X & C1) | C2. */
9973 {
9978 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9986 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9991 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9992 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9993 mode which allows further optimizations. */
9998 {
10002 {
10005 }
10006 }
10013 c3)),
10014 arg1);
10015 }
10017 /* See if this can be simplified into a rotate first. If that
10018 is unsuccessful continue in the association code. */
10022 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10030 /* See if this can be simplified into a rotate first. If that
10031 is unsuccessful continue in the association code. */
10035 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10040 {
10041 tree tem2;
10048 }
10049 /* Fold ~X & 1 as (X & 1) == 0. */
10053 {
10054 tree tem2;
10061 }
10062 /* Fold !X & 1 as X == 0. */
10065 {
10069 }
10071 /* Fold (X ^ Y) & Y as ~X & Y. */
10074 {
10079 }
10080 /* Fold (X ^ Y) & X as ~Y & X. */
10084 {
10089 }
10090 /* Fold X & (X ^ Y) as X & ~Y. */
10093 {
10098 }
10099 /* Fold X & (Y ^ X) as ~Y & X. */
10103 {
10108 }
10110 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10111 multiple of 1 << CST. */
10113 {
10120 }
10122 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10123 bits from CST2. */
10127 {
10135 {
10136 /* Avoid the transform if arg1 is a mask of some
10137 mode which allows further optimizations. */
10144 }
10145 }
10147 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10148 ((A & N) + B) & M -> (A + B) & M
10149 Similarly if (N & M) == 0,
10150 ((A | N) + B) & M -> (A + B) & M
10151 and for - instead of + (or unary - instead of +)
10152 and/or ^ instead of |.
10153 If B is constant and (B & M) == 0, fold into A & M. */
10155 {
10164 {
10167 wide_int cst0;
10169 /* Now we know that arg0 is (C + D) or (C - D) or
10170 -C and arg1 (M) is == (1LL << cst) - 1.
10171 Store C into PMOP[0] and D into PMOP[1]. */
10175 {
10178 }
10185 {
10195 {
10198 }
10201 /* If C or D is of the form (A & N) where
10202 (N & M) == M, or of the form (A | N) or
10203 (A ^ N) where (N & M) == 0, replace it with A. */
10207 /* If C or D is a N where (N & M) == 0, it can be
10208 omitted (assumed 0). */
10216 }
10218 /* Only build anything new if we optimized one or both arguments
10219 above. */
10223 {
10226 {
10227 /* Perform the operations in a type that has defined
10228 overflow behavior. */
10234 }
10239 {
10247 else
10249 }
10252 else
10255 /* TEM is now the new binary +, - or unary - replacement. */
10259 }
10260 }
10261 }
10263 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10266 {
10271 return
10273 }
10278 /* Don't touch a floating-point divide by zero unless the mode
10279 of the constant can represent infinity. */
10285 /* (-A) / (-B) -> A / B */
10297 /* Fall through */
10300 /* Simplify A / (B << N) where A and B are positive and B is
10301 a power of 2, to A >> (N + log2(B)). */
10306 {
10309 {
10317 WARN_STRICT_OVERFLOW_MISC);
10323 }
10324 }
10326 /* Fall through */
10334 /* Convert -A / -B to A / B when the type is signed and overflow is
10335 undefined. */
10339 {
10342 "when distributing negation across "
10344 WARN_STRICT_OVERFLOW_MISC);
10349 }
10353 {
10356 "when distributing negation across "
10358 WARN_STRICT_OVERFLOW_MISC);
10363 }
10365 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10366 operation, EXACT_DIV_EXPR.
10368 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10369 At one time others generated faster code, it's not clear if they do
10370 after the last round to changes to the DIV code in expmed.c. */
10381 {
10385 WARN_STRICT_OVERFLOW_MISC);
10387 }
10399 {
10403 WARN_STRICT_OVERFLOW_MISC);
10405 }
10413 /* Since negative shift count is not well-defined,
10414 don't try to compute it in the compiler. */
10420 /* If we have a rotate of a bit operation with the rotate count and
10421 the second operand of the bit operation both constant,
10422 permute the two operations. */
10434 /* Two consecutive rotates adding up to the some integer
10435 multiple of the precision of the type can be ignored. */
10450 /* Note that the operands of this must be ints
10451 and their values must be 0 or 1.
10452 ("true" is a fixed value perhaps depending on the language.) */
10453 /* If first arg is constant zero, return it. */
10457 /* If either arg is constant true, drop it. */
10461 /* Preserve sequence points. */
10464 /* If second arg is constant zero, result is zero, but first arg
10465 must be evaluated. */
10468 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10469 case will be handled here. */
10473 /* !X && X is always false. */
10477 /* X && !X is always false. */
10482 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10483 means A >= Y && A != MAX, but in this case we know that
10484 A < X <= MAX. */
10488 {
10496 }
10505 /* Note that the operands of this must be ints
10506 and their values must be 0 or true.
10507 ("true" is a fixed value perhaps depending on the language.) */
10508 /* If first arg is constant true, return it. */
10512 /* If either arg is constant zero, drop it. */
10516 /* Preserve sequence points. */
10519 /* If second arg is constant true, result is true, but we must
10520 evaluate first arg. */
10523 /* Likewise for first arg, but note this only occurs here for
10524 TRUTH_OR_EXPR. */
10528 /* !X || X is always true. */
10532 /* X || !X is always true. */
10537 /* (X && !Y) || (!X && Y) is X ^ Y */
10540 {
10557 }
10566 /* If the second arg is constant zero, drop it. */
10569 /* If the second arg is constant true, this is a logical inversion. */
10571 {
10574 }
10575 /* Identical arguments cancel to zero. */
10579 /* !X ^ X is always true. */
10584 /* X ^ !X is always true. */
10600 /* bool_var != 1 becomes !bool_var. */
10607 /* bool_var == 0 becomes !bool_var. */
10614 /* !exp != 0 becomes !exp */
10619 /* Transform comparisons of the form X +- Y CMP X to Y CMP 0. */
10628 {
10634 }
10636 /* Transform comparisons of the form X CMP X +- Y to Y CMP 0. */
10645 {
10651 }
10653 /* Transform comparisons of the form C - X CMP X if C % 2 == 1. */
10661 code == NE_EXPR
10665 /* Transform comparisons of the form X CMP C - X if C % 2 == 1. */
10673 code == NE_EXPR
10677 /* If this is an EQ or NE comparison with zero and ARG0 is
10678 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10679 two operations, but the latter can be done in one less insn
10680 on machines that have only two-operand insns or on which a
10681 constant cannot be the first operand. */
10684 {
10689 {
10696 arg1);
10697 }
10700 {
10707 arg1);
10708 }
10709 }
10711 /* If this is an NE or EQ comparison of zero against the result of a
10712 signed MOD operation whose second operand is a power of 2, make
10713 the MOD operation unsigned since it is simpler and equivalent. */
10721 {
10731 }
10733 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10734 C1 is a valid shift constant, and C2 is a power of two, i.e.
10735 a single bit. */
10739 == INTEGER_CST
10742 {
10747 /* Check for a valid shift count. */
10749 {
10753 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10754 can be rewritten as (X & (C2 << C1)) != 0. */
10756 {
10761 }
10762 /* Otherwise, for signed (arithmetic) shifts,
10763 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10764 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10768 /* Otherwise, of unsigned (logical) shifts,
10769 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10770 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10771 else
10775 arg000);
10776 }
10777 }
10779 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
10780 Similarly for NE_EXPR. */
10784 {
10788 tree dandnotc
10791 notc);
10795 }
10797 /* If this is a comparison of a field, we may be able to simplify it. */
10800 /* Handle the constant case even without -O
10801 to make sure the warnings are given. */
10803 {
10807 }
10809 /* Optimize comparisons of strlen vs zero to a compare of the
10810 first character of the string vs zero. To wit,
10811 strlen(ptr) == 0 => *ptr == 0
10812 strlen(ptr) != 0 => *ptr != 0
10813 Other cases should reduce to one of these two (or a constant)
10814 due to the return value of strlen being unsigned. */
10817 {
10825 {
10830 }
10831 }
10833 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10834 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10838 {
10843 {
10845 {
10848 }
10851 }
10852 }
10854 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10855 (X & C) == 0 when C is a single bit. */
10860 {
10867 arg1));
10868 }
10870 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10871 constant C is a power of two, i.e. a single bit. */
10878 {
10882 }
10884 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10885 when is C is a power of two, i.e. a single bit. */
10892 {
10898 }
10902 {
10905 }
10907 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10910 {
10923 arg01),
10932 arg01),
10941 arg00),
10950 arg00),
10952 }
10956 {
10963 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10964 operand_equal_p guarantees no side-effects so we don't need
10965 to use omit_one_operand on Z. */
10969 arg10));
10973 arg11));
10977 arg10));
10981 arg11));
10983 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10986 {
10992 }
10993 }
10995 /* Attempt to simplify equality/inequality comparisons of complex
10996 values. Only lower the comparison if the result is known or
10997 can be simplified to a single scalar comparison. */
11002 {
11007 {
11010 }
11011 else
11012 {
11015 }
11018 {
11021 }
11022 else
11023 {
11026 }
11030 {
11032 {
11037 }
11038 else
11039 {
11044 }
11045 }
11049 {
11051 {
11056 }
11057 else
11058 {
11063 }
11064 }
11065 }
11077 /* Transform comparisons of the form X +- C CMP X. */
11084 {
11091 else
11094 /* (X - c) > X becomes false. */
11098 {
11102 "occur when assuming that (X - c) > X "
11104 WARN_STRICT_OVERFLOW_ALL);
11106 }
11108 /* Likewise (X + c) < X becomes false. */
11112 {
11116 "occur when assuming that "
11118 WARN_STRICT_OVERFLOW_ALL);
11120 }
11122 /* Convert (X - c) <= X to true. */
11127 {
11131 "occur when assuming that "
11133 WARN_STRICT_OVERFLOW_ALL);
11135 }
11137 /* Convert (X + c) >= X to true. */
11142 {
11146 "occur when assuming that "
11148 WARN_STRICT_OVERFLOW_ALL);
11150 }
11153 {
11154 /* Convert X + c > X and X - c < X to true for integers. */
11158 {
11161 "not occur when assuming that "
11163 WARN_STRICT_OVERFLOW_ALL);
11165 }
11170 {
11173 "not occur when assuming that "
11175 WARN_STRICT_OVERFLOW_ALL);
11177 }
11179 /* Convert X + c <= X and X - c >= X to false for integers. */
11183 {
11186 "not occur when assuming that "
11188 WARN_STRICT_OVERFLOW_ALL);
11190 }
11195 {
11198 "not occur when assuming that "
11200 WARN_STRICT_OVERFLOW_ALL);
11202 }
11203 }
11204 }
11206 /* If we are comparing an ABS_EXPR with a constant, we can
11207 convert all the cases into explicit comparisons, but they may
11208 well not be faster than doing the ABS and one comparison.
11209 But ABS (X) <= C is a range comparison, which becomes a subtraction
11210 and a comparison, and is probably faster. */
11224 /* Convert ABS_EXPR<x> >= 0 to true. */
11231 {
11234 "when simplifying comparison of "
11236 WARN_STRICT_OVERFLOW_CONDITIONAL);
11239 arg0);
11240 }
11242 /* Convert ABS_EXPR<x> < 0 to false. */
11247 {
11250 "when simplifying comparison of "
11252 WARN_STRICT_OVERFLOW_CONDITIONAL);
11255 arg0);
11256 }
11258 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11259 and similarly for >= into !=. */
11269 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11270 otherwise Y might be >= # of bits in X's type and thus e.g.
11271 (unsigned char) (1 << Y) for Y 15 might be 0.
11272 If the cast is widening, then 1 << Y should have unsigned type,
11273 otherwise if Y is number of bits in the signed shift type minus 1,
11274 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11275 31 might be 0xffffffff80000000. */
11286 {
11292 }
11304 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11305 {
11317 }
11322 /* When pedantic, a compound expression can be neither an lvalue
11323 nor an integer constant expression. */
11326 /* Don't let (0, 0) be null pointer constant. */
11332 /* An ASSERT_EXPR should never be passed to fold_binary. */
11338 }
11340 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11341 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11342 of GOTO_EXPR. */
11344 static tree
11346 {
11348 {
11355 /* ... fall through ... */
11359 }
11360 }
11362 /* Return whether the sub-tree ST contains a label which is accessible from
11363 outside the sub-tree. */
11365 static bool
11367 {
11368 return
11370 }
11372 /* Fold a ternary expression of code CODE and type TYPE with operands
11373 OP0, OP1, and OP2. Return the folded expression if folding is
11374 successful. Otherwise, return NULL_TREE. */
11376 tree
11379 {
11380 tree tem;
11387 /* If this is a commutative operation, and OP0 is a constant, move it
11388 to OP1 to reduce the number of tests below. */
11397 /* Strip any conversions that don't change the mode. This is safe
11398 for every expression, except for a comparison expression because
11399 its signedness is derived from its operands. So, in the latter
11400 case, only strip conversions that don't change the signedness.
11402 Note that this is done as an internal manipulation within the
11403 constant folder, in order to find the simplest representation of
11404 the arguments so that their form can be studied. In any cases,
11405 the appropriate type conversions should be put back in the tree
11406 that will get out of the constant folder. */
11408 {
11411 }
11414 {
11417 }
11420 {
11423 }
11426 {
11430 {
11436 }
11441 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11442 so all simple results must be passed through pedantic_non_lvalue. */
11444 {
11447 /* Only optimize constant conditions when the selected branch
11448 has the same type as the COND_EXPR. This avoids optimizing
11449 away "c ? x : throw", where the throw has a void type.
11450 Avoid throwing away that operand which contains label. */
11457 }
11459 {
11464 {
11469 {
11477 }
11481 }
11482 }
11484 /* If we have A op B ? A : C, we may be able to convert this to a
11485 simpler expression, depending on the operation and the values
11486 of B and C. Signed zeros prevent all of these transformations,
11487 for reasons given above each one.
11489 Also try swapping the arguments and inverting the conditional. */
11494 {
11498 }
11502 op2,
11505 {
11509 {
11513 }
11514 }
11516 /* If the second operand is simpler than the third, swap them
11517 since that produces better jump optimization results. */
11520 {
11522 /* See if this can be inverted. If it can't, possibly because
11523 it was a floating-point inequality comparison, don't do
11524 anything. */
11528 }
11530 /* Convert A ? 1 : 0 to simply A. */
11535 /* If we try to convert OP0 to our type, the
11536 call to fold will try to move the conversion inside
11537 a COND, which will recurse. In that case, the COND_EXPR
11538 is probably the best choice, so leave it alone. */
11542 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11543 over COND_EXPR in cases such as floating point comparisons. */
11552 arg0)));
11554 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11559 {
11560 /* sign_bit_p looks through both zero and sign extensions,
11561 but for this optimization only sign extensions are
11562 usable. */
11565 {
11568 {
11571 }
11573 }
11574 /* sign_bit_p only checks ARG1 bits within A's precision.
11575 If <sign bit of A> has wider type than A, bits outside
11576 of A's precision in <sign bit of A> need to be checked.
11577 If they are all 0, this optimization needs to be done
11578 in unsigned A's type, if they are all 1 in signed A's type,
11579 otherwise this can't be done. */
11585 {
11587 tree tem_type;
11600 {
11603 }
11605 {
11608 }
11609 else
11611 }
11614 return
11620 arg1)));
11621 }
11623 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11624 already handled above. */
11629 {
11638 }
11640 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11641 is probably obsolete because the first operand should be a
11642 truth value (that's why we have the two cases above), but let's
11643 leave it in until we can confirm this for all front-ends. */
11655 /* Disable the transformations below for vectors, since
11656 fold_binary_op_with_conditional_arg may undo them immediately,
11657 yielding an infinite loop. */
11661 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11670 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11675 {
11677 /* Only perform transformation if ARG0 is easily inverted. */
11681 ? BIT_IOR_EXPR
11684 arg1);
11685 }
11687 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11692 {
11694 /* Only perform transformation if ARG0 is easily inverted. */
11700 op2);
11701 }
11703 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11715 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11716 of fold_ternary on them. */
11726 {
11736 {
11741 {
11749 }
11751 /* Constructor elements can be subvectors. */
11754 {
11758 }
11760 /* We keep an exact subset of the constructor elements. */
11762 {
11768 {
11772 }
11780 CONSTRUCTOR_ELT
11783 }
11784 /* The bitfield references a single constructor element. */
11786 {
11791 else
11795 }
11796 }
11797 }
11799 /* A bit-field-ref that referenced the full argument can be stripped. */
11805 /* On constants we can use native encode/interpret to constant
11806 fold (nearly) all BIT_FIELD_REFs. */
11810 /* This limitation should not be necessary, we just need to
11811 round this up to mode size. */
11813 /* Need bit-shifting of the buffer to relax the following. */
11815 {
11820 /* ??? We cannot tell native_encode_expr to start at
11821 some random byte only. So limit us to a reasonable amount
11822 of work. */
11824 {
11829 {
11835 }
11836 }
11837 }
11842 /* For integers we can decompose the FMA if possible. */
11854 {
11870 {
11875 /* Make sure that the perm value is in an acceptable
11876 range. */
11885 else
11890 }
11893 {
11898 }
11903 {
11908 }
11914 {
11918 }
11923 /* Some targets are deficient and fail to expand a single
11924 argument permutation while still allowing an equivalent
11925 2-argument version. */
11929 {
11932 }
11935 {
11942 }
11946 }
11952 }
11954 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11955 of an array (or vector). */
11957 tree
11959 {
11964 {
11967 {
11968 /* Static constructors for variably sized objects makes no sense. */
11972 }
11973 }
11984 offset_int max_index;
11989 {
11990 /* Array constructor might explicitly set index, or specify a range,
11991 or leave index NULL meaning that it is next index after previous
11992 one. */
11994 {
11997 else
11998 {
12002 }
12003 }
12004 else
12005 {
12011 }
12013 /* Do we have match? */
12017 }
12019 }
12021 /* Perform constant folding and related simplification of EXPR.
12022 The related simplifications include x*1 => x, x*0 => 0, etc.,
12023 and application of the associative law.
12024 NOP_EXPR conversions may be removed freely (as long as we
12025 are careful not to change the type of the overall expression).
12026 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12027 but we can constant-fold them if they have constant operands. */
12029 #ifdef ENABLE_FOLD_CHECKING
12030 # define fold(x) fold_1 (x)
12032 static
12033 #endif
12034 tree
12036 {
12040 tree tem;
12043 /* Return right away if a constant. */
12047 /* CALL_EXPR-like objects with variable numbers of operands are
12048 treated specially. */
12050 {
12052 {
12055 }
12057 }
12060 {
12065 {
12083 }
12084 }
12087 {
12089 {
12096 {
12101 }
12104 }
12106 /* Return a VECTOR_CST if possible. */
12108 {
12114 tree val;
12120 }
12128 }
12130 #ifdef ENABLE_FOLD_CHECKING
12131 #undef fold
12138 /* When --enable-checking=fold, compute a digest of expr before
12139 and after actual fold call to see if fold did not accidentally
12140 change original expr. */
12142 tree
12144 {
12145 tree ret;
12165 }
12167 void
12169 {
12180 }
12182 static void
12184 {
12186 }
12188 static void
12191 {
12197 recursive_label:
12207 {
12208 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12213 }
12220 {
12221 /* Allow these fields to be modified. */
12222 tree tmp;
12230 {
12233 }
12234 }
12245 {
12248 {
12263 }
12267 {
12280 }
12297 {
12303 }
12306 {
12308 {
12311 }
12313 }
12324 {
12327 }
12337 }
12338 }
12340 /* Helper function for outputting the checksum of a tree T. When
12341 debugging with gdb, you can "define mynext" to be "next" followed
12342 by "call debug_fold_checksum (op0)", then just trace down till the
12343 outputs differ. */
12345 DEBUG_FUNCTION void
12347 {
12362 }
12364 #endif
12366 /* Fold a unary tree expression with code CODE of type TYPE with an
12367 operand OP0. LOC is the location of the resulting expression.
12368 Return a folded expression if successful. Otherwise, return a tree
12369 expression with code CODE of type TYPE with an operand OP0. */
12371 tree
12374 {
12375 tree tem;
12376 #ifdef ENABLE_FOLD_CHECKING
12385 #endif
12391 #ifdef ENABLE_FOLD_CHECKING
12398 #endif
12400 }
12402 /* Fold a binary tree expression with code CODE of type TYPE with
12403 operands OP0 and OP1. LOC is the location of the resulting
12404 expression. Return a folded expression if successful. Otherwise,
12405 return a tree expression with code CODE of type TYPE with operands
12406 OP0 and OP1. */
12408 tree
12411 MEM_STAT_DECL)
12412 {
12413 tree tem;
12414 #ifdef ENABLE_FOLD_CHECKING
12431 #endif
12437 #ifdef ENABLE_FOLD_CHECKING
12452 #endif
12454 }
12456 /* Fold a ternary tree expression with code CODE of type TYPE with
12457 operands OP0, OP1, and OP2. Return a folded expression if
12458 successful. Otherwise, return a tree expression with code CODE of
12459 type TYPE with operands OP0, OP1, and OP2. */
12461 tree
12464 {
12465 tree tem;
12466 #ifdef ENABLE_FOLD_CHECKING
12490 #endif
12497 #ifdef ENABLE_FOLD_CHECKING
12520 #endif
12522 }
12524 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12525 arguments in ARGARRAY, and a null static chain.
12526 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12527 of type TYPE from the given operands as constructed by build_call_array. */
12529 tree
12532 {
12533 tree tem;
12534 #ifdef ENABLE_FOLD_CHECKING
12553 #endif
12559 #ifdef ENABLE_FOLD_CHECKING
12575 #endif
12577 }
12579 /* Perform constant folding and related simplification of initializer
12580 expression EXPR. These behave identically to "fold_buildN" but ignore
12581 potential run-time traps and exceptions that fold must preserve. */
12583 #define START_FOLD_INIT \
12584 int saved_signaling_nans = flag_signaling_nans;\
12585 int saved_trapping_math = flag_trapping_math;\
12586 int saved_rounding_math = flag_rounding_math;\
12587 int saved_trapv = flag_trapv;\
12588 int saved_folding_initializer = folding_initializer;\
12589 flag_signaling_nans = 0;\
12590 flag_trapping_math = 0;\
12591 flag_rounding_math = 0;\
12592 flag_trapv = 0;\
12593 folding_initializer = 1;
12595 #define END_FOLD_INIT \
12596 flag_signaling_nans = saved_signaling_nans;\
12597 flag_trapping_math = saved_trapping_math;\
12598 flag_rounding_math = saved_rounding_math;\
12599 flag_trapv = saved_trapv;\
12600 folding_initializer = saved_folding_initializer;
12602 tree
12605 {
12606 tree result;
12607 START_FOLD_INIT;
12611 END_FOLD_INIT;
12613 }
12615 tree
12618 {
12619 tree result;
12620 START_FOLD_INIT;
12624 END_FOLD_INIT;
12626 }
12628 tree
12631 {
12632 tree result;
12633 START_FOLD_INIT;
12637 END_FOLD_INIT;
12639 }
12641 #undef START_FOLD_INIT
12642 #undef END_FOLD_INIT
12644 /* Determine if first argument is a multiple of second argument. Return 0 if
12645 it is not, or we cannot easily determined it to be.
12647 An example of the sort of thing we care about (at this point; this routine
12648 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12649 fold cases do now) is discovering that
12651 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12653 is a multiple of
12655 SAVE_EXPR (J * 8)
12657 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12659 This code also handles discovering that
12661 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12663 is a multiple of 8 so we don't have to worry about dealing with a
12664 possible remainder.
12666 Note that we *look* inside a SAVE_EXPR only to determine how it was
12667 calculated; it is not safe for fold to do much of anything else with the
12668 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12669 at run time. For example, the latter example above *cannot* be implemented
12670 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12671 evaluation time of the original SAVE_EXPR is not necessarily the same at
12672 the time the new expression is evaluated. The only optimization of this
12673 sort that would be valid is changing
12675 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12677 divided by 8 to
12679 SAVE_EXPR (I) * SAVE_EXPR (J)
12681 (where the same SAVE_EXPR (J) is used in the original and the
12682 transformed version). */
12684 int
12686 {
12694 {
12696 /* Bitwise and provides a power of two multiple. If the mask is
12697 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12700 /* FALLTHRU */
12713 {
12717 /* const_binop may not detect overflow correctly,
12718 so check for it explicitly here. */
12722 size_one_node,
12723 op1)))
12726 }
12730 /* Can't handle conversions from non-integral or wider integral type. */
12736 /* .. fall through ... */
12753 SIGNED);
12757 }
12758 }
12760 #define tree_expr_nonnegative_warnv_p(X, Y) \
12763 #define RECURSE(X) \
12764 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12766 /* Return true if CODE or TYPE is known to be non-negative. */
12768 static bool
12770 {
12773 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12774 have a signed:1 type (where the value is -1 and 0). */
12777 }
12779 /* Return true if (CODE OP0) is known to be non-negative. If the return
12780 value is based on the assumption that signed overflow is undefined,
12781 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12782 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12784 bool
12787 {
12792 {
12794 /* We can't return 1 if flag_wrapv is set because
12795 ABS_EXPR<INT_MIN> = INT_MIN. */
12799 {
12802 }
12810 CASE_CONVERT:
12811 {
12816 {
12820 {
12824 }
12825 }
12827 {
12833 }
12834 }
12839 }
12841 /* We don't know sign of `t', so be conservative and return false. */
12843 }
12845 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12846 value is based on the assumption that signed overflow is undefined,
12847 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12848 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12850 bool
12854 {
12859 {
12865 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12866 both unsigned and at least 2 bits shorter than the result. */
12870 {
12875 {
12879 }
12880 }
12885 {
12886 /* x * x is always non-negative for floating point x
12887 or without overflow. */
12890 {
12895 }
12896 }
12898 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12899 both unsigned and their total bits is shorter than the result. */
12903 {
12922 {
12932 }
12933 }
12960 }
12962 /* We don't know sign of `t', so be conservative and return false. */
12964 }
12966 /* Return true if T is known to be non-negative. If the return
12967 value is based on the assumption that signed overflow is undefined,
12968 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12969 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12971 bool
12973 {
12978 {
12992 /* Limit the depth of recursion to avoid quadratic behavior.
12993 This is expected to catch almost all occurrences in practice.
12994 If this code misses important cases that unbounded recursion
12995 would not, passes that need this information could be revised
12996 to provide it through dataflow propagation. */
13004 }
13005 }
13007 /* Return true if T is known to be non-negative. If the return
13008 value is based on the assumption that signed overflow is undefined,
13009 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13010 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13012 bool
13015 {
13017 {
13018 CASE_CFN_ACOS:
13019 CASE_CFN_ACOSH:
13020 CASE_CFN_CABS:
13021 CASE_CFN_COSH:
13022 CASE_CFN_ERFC:
13023 CASE_CFN_EXP:
13024 CASE_CFN_EXP10:
13025 CASE_CFN_EXP2:
13026 CASE_CFN_FABS:
13027 CASE_CFN_FDIM:
13028 CASE_CFN_HYPOT:
13029 CASE_CFN_POW10:
13030 CASE_CFN_FFS:
13031 CASE_CFN_PARITY:
13032 CASE_CFN_POPCOUNT:
13033 CASE_CFN_CLZ:
13034 CASE_CFN_CLRSB:
13037 /* Always true. */
13040 CASE_CFN_SQRT:
13041 /* sqrt(-0.0) is -0.0. */
13046 CASE_CFN_ASINH:
13047 CASE_CFN_ATAN:
13048 CASE_CFN_ATANH:
13049 CASE_CFN_CBRT:
13050 CASE_CFN_CEIL:
13051 CASE_CFN_ERF:
13052 CASE_CFN_EXPM1:
13053 CASE_CFN_FLOOR:
13054 CASE_CFN_FMOD:
13055 CASE_CFN_FREXP:
13056 CASE_CFN_ICEIL:
13057 CASE_CFN_IFLOOR:
13058 CASE_CFN_IRINT:
13059 CASE_CFN_IROUND:
13060 CASE_CFN_LCEIL:
13061 CASE_CFN_LDEXP:
13062 CASE_CFN_LFLOOR:
13063 CASE_CFN_LLCEIL:
13064 CASE_CFN_LLFLOOR:
13065 CASE_CFN_LLRINT:
13066 CASE_CFN_LLROUND:
13067 CASE_CFN_LRINT:
13068 CASE_CFN_LROUND:
13069 CASE_CFN_MODF:
13070 CASE_CFN_NEARBYINT:
13071 CASE_CFN_RINT:
13072 CASE_CFN_ROUND:
13073 CASE_CFN_SCALB:
13074 CASE_CFN_SCALBLN:
13075 CASE_CFN_SCALBN:
13076 CASE_CFN_SIGNBIT:
13077 CASE_CFN_SIGNIFICAND:
13078 CASE_CFN_SINH:
13079 CASE_CFN_TANH:
13080 CASE_CFN_TRUNC:
13081 /* True if the 1st argument is nonnegative. */
13084 CASE_CFN_FMAX:
13085 /* True if the 1st OR 2nd arguments are nonnegative. */
13088 CASE_CFN_FMIN:
13089 /* True if the 1st AND 2nd arguments are nonnegative. */
13092 CASE_CFN_COPYSIGN:
13093 /* True if the 2nd argument is nonnegative. */
13096 CASE_CFN_POWI:
13097 /* True if the 1st argument is nonnegative or the second
13098 argument is an even integer. */
13104 CASE_CFN_POW:
13105 /* True if the 1st argument is nonnegative or the second
13106 argument is an even integer valued real. */
13108 {
13109 REAL_VALUE_TYPE c;
13110 HOST_WIDE_INT n;
13115 {
13116 REAL_VALUE_TYPE cint;
13120 }
13121 }
13126 }
13128 }
13130 /* Return true if T is known to be non-negative. If the return
13131 value is based on the assumption that signed overflow is undefined,
13132 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13133 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13135 static bool
13137 {
13143 {
13145 {
13149 /* If the initializer is non-void, then it's a normal expression
13150 that will be assigned to the slot. */
13154 /* Otherwise, the initializer sets the slot in some way. One common
13155 way is an assignment statement at the end of the initializer. */
13157 {
13165 else
13167 }
13173 }
13176 {
13182 arg0,
13183 arg1,
13185 }
13198 }
13199 }
13201 #undef RECURSE
13202 #undef tree_expr_nonnegative_warnv_p
13204 /* Return true if T is known to be non-negative. If the return
13205 value is based on the assumption that signed overflow is undefined,
13206 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13207 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13209 bool
13211 {
13218 {
13240 }
13243 {
13269 }
13270 }
13272 /* Return true if `t' is known to be non-negative. Handle warnings
13273 about undefined signed overflow. */
13275 bool
13277 {
13284 "determining that expression is always "
13286 WARN_STRICT_OVERFLOW_MISC);
13288 }
13291 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13292 For floating point we further ensure that T is not denormal.
13293 Similar logic is present in nonzero_address in rtlanal.h.
13295 If the return value is based on the assumption that signed overflow
13296 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13297 change *STRICT_OVERFLOW_P. */
13299 bool
13302 {
13304 {
13307 strict_overflow_p);
13310 {
13316 strict_overflow_p));
13317 }
13322 strict_overflow_p);
13326 }
13329 }
13331 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13332 For floating point we further ensure that T is not denormal.
13333 Similar logic is present in nonzero_address in rtlanal.h.
13335 If the return value is based on the assumption that signed overflow
13336 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13337 change *STRICT_OVERFLOW_P. */
13339 bool
13341 tree type,
13342 tree op0,
13344 {
13347 {
13351 {
13352 /* With the presence of negative values it is hard
13353 to say something. */
13360 /* One of operands must be positive and the other non-negative. */
13361 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13362 overflows, on a twos-complement machine the sum of two
13363 nonnegative numbers can never be zero. */
13365 strict_overflow_p)
13367 strict_overflow_p));
13368 }
13373 {
13375 strict_overflow_p)
13377 strict_overflow_p))
13378 {
13381 }
13382 }
13391 {
13394 }
13401 {
13405 /* When both operands are nonzero, then MAX must be too. */
13407 strict_overflow_p))
13410 /* MAX where operand 0 is positive is positive. */
13412 strict_overflow_p);
13413 }
13414 /* MAX where operand 1 is positive is positive. */
13419 {
13423 }
13428 strict_overflow_p)
13430 strict_overflow_p));
13434 }
13437 }
13439 /* Return true when T is an address and is known to be nonzero.
13440 For floating point we further ensure that T is not denormal.
13441 Similar logic is present in nonzero_address in rtlanal.h.
13443 If the return value is based on the assumption that signed overflow
13444 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13445 change *STRICT_OVERFLOW_P. */
13447 bool
13449 {
13452 {
13457 {
13466 /* For objects in symbol table check if we know they are non-zero.
13467 Don't do anything for variables and functions before symtab is built;
13468 it is quite possible that they will be declared weak later. */
13470 {
13476 else
13478 }
13480 /* Function local objects are never NULL. */
13487 /* Constants are never weak. */
13492 }
13500 {
13504 }
13509 }
13511 }
13513 #define integer_valued_real_p(X) \
13516 #define RECURSE(X) \
13517 ((integer_valued_real_p) (X, depth + 1))
13519 /* Return true if the floating point result of (CODE OP0) has an
13520 integer value. We also allow +Inf, -Inf and NaN to be considered
13521 integer values. Return false for signaling NaN.
13523 DEPTH is the current nesting depth of the query. */
13525 bool
13527 {
13529 {
13536 CASE_CONVERT:
13537 {
13544 }
13548 }
13550 }
13552 /* Return true if the floating point result of (CODE OP0 OP1) has an
13553 integer value. We also allow +Inf, -Inf and NaN to be considered
13554 integer values. Return false for signaling NaN.
13556 DEPTH is the current nesting depth of the query. */
13558 bool
13560 {
13562 {
13572 }
13574 }
13576 /* Return true if the floating point result of calling FNDECL with arguments
13577 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13578 considered integer values. Return false for signaling NaN. If FNDECL
13579 takes fewer than 2 arguments, the remaining ARGn are null.
13581 DEPTH is the current nesting depth of the query. */
13583 bool
13585 {
13587 {
13588 CASE_CFN_CEIL:
13589 CASE_CFN_FLOOR:
13590 CASE_CFN_NEARBYINT:
13591 CASE_CFN_RINT:
13592 CASE_CFN_ROUND:
13593 CASE_CFN_TRUNC:
13596 CASE_CFN_FMIN:
13597 CASE_CFN_FMAX:
13602 }
13604 }
13606 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13607 has an integer value. We also allow +Inf, -Inf and NaN to be
13608 considered integer values. Return false for signaling NaN.
13610 DEPTH is the current nesting depth of the query. */
13612 bool
13614 {
13616 {
13624 /* Limit the depth of recursion to avoid quadratic behavior.
13625 This is expected to catch almost all occurrences in practice.
13626 If this code misses important cases that unbounded recursion
13627 would not, passes that need this information could be revised
13628 to provide it through dataflow propagation. */
13632 depth));
13636 }
13638 }
13640 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13641 has an integer value. We also allow +Inf, -Inf and NaN to be
13642 considered integer values. Return false for signaling NaN.
13644 DEPTH is the current nesting depth of the query. */
13646 static bool
13648 {
13650 {
13661 }
13663 }
13665 #undef RECURSE
13666 #undef integer_valued_real_p
13668 /* Return true if the floating point expression T has an integer value.
13669 We also allow +Inf, -Inf and NaN to be considered integer values.
13670 Return false for signaling NaN.
13672 DEPTH is the current nesting depth of the query. */
13674 bool
13676 {
13682 {
13698 }
13701 {
13707 {
13716 }
13720 }
13721 }
13723 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13724 attempt to fold the expression to a constant without modifying TYPE,
13725 OP0 or OP1.
13727 If the expression could be simplified to a constant, then return
13728 the constant. If the expression would not be simplified to a
13729 constant, then return NULL_TREE. */
13731 tree
13733 {
13736 }
13738 /* Given the components of a unary expression CODE, TYPE and OP0,
13739 attempt to fold the expression to a constant without modifying
13740 TYPE or OP0.
13742 If the expression could be simplified to a constant, then return
13743 the constant. If the expression would not be simplified to a
13744 constant, then return NULL_TREE. */
13746 tree
13748 {
13751 }
13753 /* If EXP represents referencing an element in a constant string
13754 (either via pointer arithmetic or array indexing), return the
13755 tree representing the value accessed, otherwise return NULL. */
13757 tree
13759 {
13763 {
13765 tree index;
13766 tree string;
13771 else
13772 {
13776 /* Optimize the special-case of a zero lower bound.
13778 We convert the low_bound to sizetype to avoid some problems
13779 with constant folding. (E.g. suppose the lower bound is 1,
13780 and its mode is QI. Without the conversion,l (ARRAY
13781 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13782 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13788 }
13801 }
13803 }
13805 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13806 an integer constant, real, or fixed-point constant.
13808 TYPE is the type of the result. */
13810 static tree
13812 {
13816 {
13818 {
13825 }
13832 {
13833 FIXED_VALUE_TYPE f;
13838 /* Propagate overflow flags. */
13842 }
13846 }
13849 }
13851 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13852 an integer constant or real constant.
13854 TYPE is the type of the result. */
13856 tree
13858 {
13862 {
13864 {
13865 /* If the value is unsigned or non-negative, then the absolute value
13866 is the same as the ordinary value. */
13870 /* If the value is negative, then the absolute value is
13871 its negation. */
13872 else
13873 {
13878 }
13879 }
13885 else
13891 }
13894 }
13896 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13897 constant. TYPE is the type of the result. */
13899 static tree
13901 {
13905 }
13907 /* Given CODE, a relational operator, the target type, TYPE and two
13908 constant operands OP0 and OP1, return the result of the
13909 relational operation. If the result is not a compile time
13910 constant, then return NULL_TREE. */
13912 static tree
13914 {
13917 /* From here on, the only cases we handle are when the result is
13918 known to be a constant. */
13921 {
13925 /* Handle the cases where either operand is a NaN. */
13927 {
13929 {
13957 }
13960 }
13963 }
13966 {
13970 }
13972 /* Handle equality/inequality of complex constants. */
13974 {
13985 else
13987 }
13990 {
13992 {
13993 /* Have vector comparison with scalar boolean result. */
13998 {
14003 }
14007 }
14014 {
14026 }
14029 }
14031 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14033 To compute GT, swap the arguments and do LT.
14034 To compute GE, do LT and invert the result.
14035 To compute LE, swap the arguments, do LT and invert the result.
14036 To compute NE, do EQ and invert the result.
14038 Therefore, the code below must handle only EQ and LT. */
14041 {
14044 }
14046 /* Note that it is safe to invert for real values here because we
14047 have already handled the one case that it matters. */
14051 {
14054 }
14056 /* Compute a result for LT or EQ if args permit;
14057 Otherwise return T. */
14059 {
14062 else
14064 }
14065 else
14071 }
14073 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14074 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14075 itself. */
14077 tree
14079 {
14080 /* If the expression does not have side effects then we don't have to wrap
14081 it with a cleanup point expression. */
14085 /* If the expression is a return, check to see if the expression inside the
14086 return has no side effects or the right hand side of the modify expression
14087 inside the return. If either don't have side effects set we don't need to
14088 wrap the expression in a cleanup point expression. Note we don't check the
14089 left hand side of the modify because it should always be a return decl. */
14091 {
14098 }
14101 }
14103 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14104 of an indirection through OP0, or NULL_TREE if no simplification is
14105 possible. */
14107 tree
14109 {
14111 tree subtype;
14119 {
14122 /* *&CONST_DECL -> to the value of the const decl. */
14125 /* *&p => p; make sure to handle *&"str"[cst] here. */
14127 {
14131 else
14133 }
14134 /* *(foo *)&fooarray => fooarray[0] */
14137 && (!in_gimple_form
14139 {
14149 }
14150 /* *(foo *)&complexfoo => __real__ complexfoo */
14154 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14157 {
14161 }
14162 }
14166 {
14172 {
14173 tree op00type;
14177 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14180 {
14192 }
14193 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14196 {
14200 }
14201 /* ((foo *)&fooarray)[1] => fooarray[1] */
14204 {
14214 }
14215 }
14216 }
14218 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14221 && (!in_gimple_form
14223 {
14224 tree type_domain;
14234 NULL_TREE);
14235 }
14238 }
14240 /* Builds an expression for an indirection through T, simplifying some
14241 cases. */
14243 tree
14245 {
14253 }
14255 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14257 tree
14259 {
14264 else
14266 }
14268 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14269 whose result is ignored. The type of the returned tree need not be
14270 the same as the original expression. */
14272 tree
14274 {
14280 {
14291 else
14297 {
14313 }
14318 }
14319 }
14321 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14323 tree
14325 {
14331 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14332 have to do anything. Only do this when we are not given a const,
14333 because in that case, this check is more expensive than just
14334 doing it. */
14336 {
14341 }
14343 /* If divisor is a power of two, simplify this to bit manipulation. */
14345 {
14347 {
14361 }
14362 else
14363 {
14364 tree t;
14370 }
14371 }
14372 else
14373 {
14378 }
14381 }
14383 /* Likewise, but round down. */
14385 tree
14387 {
14394 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14395 have to do anything. Only do this when we are not given a const,
14396 because in that case, this check is more expensive than just
14397 doing it. */
14399 {
14404 }
14406 /* If divisor is a power of two, simplify this to bit manipulation. */
14408 {
14409 tree t;
14413 }
14414 else
14415 {
14420 }
14423 }
14425 /* Returns the pointer to the base of the object addressed by EXP and
14426 extracts the information about the offset of the access, storing it
14427 to PBITPOS and POFFSET. */
14429 static tree
14432 {
14433 tree core;
14434 machine_mode mode;
14436 HOST_WIDE_INT bitsize;
14440 {
14445 }
14446 else
14447 {
14451 }
14454 }
14456 /* Returns true if addresses of E1 and E2 differ by a constant, false
14457 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14459 bool
14461 {
14475 {
14485 }
14487 {
14488 /* If only one of the offsets is non-constant, the difference cannot
14489 be a constant. */
14491 }
14492 else
14497 }
14499 /* Return OFF converted to a pointer offset type suitable as offset for
14500 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14501 tree
14503 {
14505 }
14507 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14508 tree
14510 {
14513 }
14515 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14516 tree
14518 {
14521 }
14523 /* Return a char pointer for a C string if it is a string constant
14524 or sum of string constant and integer constant. */
14528 {
14529 tree offset_node;
14542 }