| blob | c16959b84ace943d5be3ce18cca7df8f98f2e347 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
85 /* Nonzero if we are folding constants inside an initializer; zero
86 otherwise. */
89 /* The following constants represent a bit based encoding of GCC's
90 comparison operators. This encoding simplifies transformations
91 on relational comparison operators, such as AND and OR. */
109 };
142 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
143 Otherwise, return LOC. */
145 static location_t
147 {
150 }
152 /* Similar to protected_set_expr_location, but never modify x in place,
153 if location can and needs to be set, unshare it. */
157 {
163 {
166 }
168 }
169 \f
170 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
171 division and returns the quotient. Otherwise returns
172 NULL_TREE. */
174 tree
176 {
177 widest_int quo;
184 }
185 \f
186 /* This is nonzero if we should defer warnings about undefined
187 overflow. This facility exists because these warnings are a
188 special case. The code to estimate loop iterations does not want
189 to issue any warnings, since it works with expressions which do not
190 occur in user code. Various bits of cleanup code call fold(), but
191 only use the result if it has certain characteristics (e.g., is a
192 constant); that code only wants to issue a warning if the result is
193 used. */
197 /* If a warning about undefined overflow is deferred, this is the
198 warning. Note that this may cause us to turn two warnings into
199 one, but that is fine since it is sufficient to only give one
200 warning per expression. */
204 /* If a warning about undefined overflow is deferred, this is the
205 level at which the warning should be emitted. */
209 /* Start deferring overflow warnings. We could use a stack here to
210 permit nested calls, but at present it is not necessary. */
212 void
214 {
216 }
218 /* Stop deferring overflow warnings. If there is a pending warning,
219 and ISSUE is true, then issue the warning if appropriate. STMT is
220 the statement with which the warning should be associated (used for
221 location information); STMT may be NULL. CODE is the level of the
222 warning--a warn_strict_overflow_code value. This function will use
223 the smaller of CODE and the deferred code when deciding whether to
224 issue the warning. CODE may be zero to mean to always use the
225 deferred code. */
227 void
229 {
231 location_t locus;
236 {
242 }
253 /* Use the smallest code level when deciding to issue the
254 warning. */
263 else
266 }
268 /* Stop deferring overflow warnings, ignoring any deferred
269 warnings. */
271 void
273 {
275 }
277 /* Whether we are deferring overflow warnings. */
279 bool
281 {
283 }
285 /* This is called when we fold something based on the fact that signed
286 overflow is undefined. */
288 void
290 {
292 {
295 {
298 }
299 }
302 }
303 \f
304 /* Return true if the built-in mathematical function specified by CODE
305 is odd, i.e. -f(x) == f(-x). */
307 bool
309 {
311 {
312 CASE_CFN_ASIN:
313 CASE_CFN_ASINH:
314 CASE_CFN_ATAN:
315 CASE_CFN_ATANH:
316 CASE_CFN_CASIN:
317 CASE_CFN_CASINH:
318 CASE_CFN_CATAN:
319 CASE_CFN_CATANH:
320 CASE_CFN_CBRT:
321 CASE_CFN_CPROJ:
322 CASE_CFN_CSIN:
323 CASE_CFN_CSINH:
324 CASE_CFN_CTAN:
325 CASE_CFN_CTANH:
326 CASE_CFN_ERF:
327 CASE_CFN_LLROUND:
328 CASE_CFN_LROUND:
329 CASE_CFN_ROUND:
330 CASE_CFN_SIN:
331 CASE_CFN_SINH:
332 CASE_CFN_TAN:
333 CASE_CFN_TANH:
334 CASE_CFN_TRUNC:
337 CASE_CFN_LLRINT:
338 CASE_CFN_LRINT:
339 CASE_CFN_NEARBYINT:
340 CASE_CFN_RINT:
345 }
347 }
349 /* Check whether we may negate an integer constant T without causing
350 overflow. */
352 bool
354 {
355 tree type;
364 }
366 /* Determine whether an expression T can be cheaply negated using
367 the function negate_expr without introducing undefined overflow. */
369 static bool
371 {
372 tree type;
381 {
386 /* Check that -CST will not overflow type. */
399 /* We want to canonicalize to positive real constants. Pretend
400 that only negative ones can be easily negated. */
408 {
419 }
434 /* -(A + B) -> (-B) - A. */
437 /* -(A + B) -> (-A) - B. */
441 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
450 /* INT_MIN/n * n doesn't overflow while negating one operand it does
451 if n is a (negative) power of two. */
462 /* Fall through. */
477 /* In general we can't negate B in A / B, because if A is INT_MIN and
478 B is 1, we may turn this into INT_MIN / -1 which is undefined
479 and actually traps on some architectures. */
488 /* Negate -((double)float) as (double)(-float). */
490 {
494 }
498 /* Negate -f(x) as f(-x). */
504 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
506 {
510 }
515 }
517 }
519 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
520 simplification is possible.
521 If negate_expr_p would return true for T, NULL_TREE will never be
522 returned. */
524 static tree
526 {
528 tree tem;
531 {
532 /* Convert - (~A) to A + 1. */
558 {
563 }
567 {
572 {
577 }
580 }
603 {
604 /* -(A + B) -> (-B) - A. */
606 {
610 }
612 /* -(A + B) -> (-A) - B. */
614 {
618 }
619 }
623 /* - (A - B) -> B - A */
634 /* Fall through. */
638 {
647 }
659 /* In general we can't negate B in A / B, because if A is INT_MIN and
660 B is 1, we may turn this into INT_MIN / -1 which is undefined
661 and actually traps on some architectures. */
673 /* Convert -((double)float) into (double)(-float). */
675 {
679 }
683 /* Negate -f(x) as f(-x). */
686 {
692 }
696 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
698 {
701 {
708 }
709 }
714 }
717 }
719 /* A wrapper for fold_negate_expr_1. */
721 static tree
723 {
730 }
732 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
733 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
734 return NULL_TREE. */
736 static tree
738 {
740 location_t loc;
753 }
754 \f
755 /* Split a tree IN into a constant, literal and variable parts that could be
756 combined with CODE to make IN. "constant" means an expression with
757 TREE_CONSTANT but that isn't an actual constant. CODE must be a
758 commutative arithmetic operation. Store the constant part into *CONP,
759 the literal in *LITP and return the variable part. If a part isn't
760 present, set it to null. If the tree does not decompose in this way,
761 return the entire tree as the variable part and the other parts as null.
763 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
764 case, we negate an operand that was subtracted. Except if it is a
765 literal for which we use *MINUS_LITP instead.
767 If NEGATE_P is true, we are negating all of IN, again except a literal
768 for which we use *MINUS_LITP instead. If a variable part is of pointer
769 type, it is negated after converting to TYPE. This prevents us from
770 generating illegal MINUS pointer expression. LOC is the location of
771 the converted variable part.
773 If IN is itself a literal or constant, return it as appropriate.
775 Note that we do not guarantee that any of the three values will be the
776 same type as IN, but they will have the same signedness and mode. */
778 static tree
782 {
790 /* Strip any conversions that don't change the machine mode or signedness. */
799 /* We can associate addition and subtraction together (even
800 though the C standard doesn't say so) for integers because
801 the value is not affected. For reals, the value might be
802 affected, so we can't. */
808 {
814 /* First see if either of the operands is a literal, then a constant. */
827 /* If we haven't dealt with either operand, this is not a case we can
828 decompose. Otherwise, VAR is either of the ones remaining, if any. */
833 else
836 /* Now do any needed negations. */
843 }
848 {
849 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
850 when IN is constant. */
853 }
854 else
858 {
871 }
881 }
883 /* Re-associate trees split by the above function. T1 and T2 are
884 either expressions to associate or null. Return the new
885 expression, if any. LOC is the location of the new expression. If
886 we build an operation, do it in TYPE and with CODE. */
888 static tree
890 {
892 {
895 }
899 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
900 try to fold this since we will have infinite recursion. But do
901 deal with any NEGATE_EXPRs. */
905 {
907 {
920 }
922 {
925 }
929 }
933 }
934 \f
935 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
936 for use in int_const_binop, size_binop and size_diffop. */
938 static bool
940 {
947 {
956 }
961 }
964 /* Combine two integer constants PARG1 and PARG2 under operation CODE
965 to produce a new constant. Return NULL_TREE if we don't know how
966 to evaluate CODE at compile-time. */
968 static tree
971 {
972 wide_int res;
973 tree t;
982 {
998 {
1002 else
1004 }
1007 /* It's unclear from the C standard whether shifts can overflow.
1008 The following code ignores overflow; perhaps a C standard
1009 interpretation ruling is needed. */
1011 else
1018 {
1022 else
1024 }
1028 else
1107 }
1115 }
1117 tree
1119 {
1121 }
1123 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1124 constant. We assume ARG1 and ARG2 have the same data type, or at least
1125 are the same kind of constant and the same machine mode. Return zero if
1126 combining the constants is not allowed in the current operating mode. */
1128 static tree
1130 {
1131 /* Sanity check for the recursive cases. */
1139 {
1145 }
1148 {
1149 machine_mode mode;
1150 REAL_VALUE_TYPE d1;
1151 REAL_VALUE_TYPE d2;
1152 REAL_VALUE_TYPE value;
1153 REAL_VALUE_TYPE result;
1157 /* The following codes are handled by real_arithmetic. */
1159 {
1170 }
1178 /* Don't perform operation if we honor signaling NaNs and
1179 either operand is a signaling NaN. */
1185 /* Don't perform operation if it would raise a division
1186 by zero exception. */
1192 /* If either operand is a NaN, just return it. Otherwise, set up
1193 for floating-point trap; we return an overflow. */
1195 {
1196 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1197 is off. */
1201 }
1203 {
1204 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1205 is off. */
1209 }
1214 /* Don't constant fold this floating point operation if
1215 the result has overflowed and flag_trapping_math. */
1223 /* Don't constant fold this floating point operation if the
1224 result may dependent upon the run-time rounding mode and
1225 flag_rounding_math is set, or if GCC's software emulation
1226 is unable to accurately represent the result. */
1236 }
1239 {
1240 FIXED_VALUE_TYPE f1;
1241 FIXED_VALUE_TYPE f2;
1242 FIXED_VALUE_TYPE result;
1247 /* The following codes are handled by fixed_arithmetic. */
1249 {
1261 {
1268 }
1273 }
1280 /* Propagate overflow flags. */
1284 }
1287 {
1296 {
1307 mpc_mul);
1321 mpc_div);
1322 /* Fallthru. */
1328 {
1329 /* Keep this algorithm in sync with
1330 tree-complex.c:expand_complex_div_straight().
1332 Expand complex division to scalars, straightforward algorithm.
1333 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1334 t = br*br + bi*bi
1335 */
1336 tree magsquared
1340 tree t1
1344 tree t2
1351 }
1352 else
1353 {
1354 /* Keep this algorithm in sync with
1355 tree-complex.c:expand_complex_div_wide().
1357 Expand complex division to scalars, modified algorithm to minimize
1358 overflow with wide input ranges. */
1364 {
1365 /* In the TRUE branch, we compute
1366 ratio = br/bi;
1367 div = (br * ratio) + bi;
1368 tr = (ar * ratio) + ai;
1369 ti = (ai * ratio) - ar;
1370 tr = tr / div;
1371 ti = ti / div; */
1382 }
1383 else
1384 {
1385 /* In the FALSE branch, we compute
1386 ratio = d/c;
1387 divisor = (d * ratio) + c;
1388 tr = (b * ratio) + a;
1389 ti = b - (a * ratio);
1390 tr = tr / div;
1391 ti = ti / div; */
1403 }
1404 }
1409 }
1413 }
1417 {
1423 {
1429 /* It is possible that const_binop cannot handle the given
1430 code and return NULL_TREE */
1434 }
1437 }
1439 /* Shifts allow a scalar offset for a vector. */
1442 {
1448 {
1453 /* It is possible that const_binop cannot handle the given
1454 code and return NULL_TREE. */
1458 }
1461 }
1463 }
1465 /* Overload that adds a TYPE parameter to be able to dispatch
1466 to fold_relational_const. */
1468 tree
1470 {
1474 /* ??? Until we make the const_binop worker take the type of the
1475 result as argument put those cases that need it here. */
1477 {
1488 {
1502 {
1512 }
1515 }
1521 {
1543 {
1556 }
1559 }
1562 }
1567 /* Make sure type and arg0 have the same saturating flag. */
1572 }
1574 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1575 Return zero if computing the constants is not possible. */
1577 tree
1579 {
1580 /* Don't perform the operation, other than NEGATE and ABS, if
1581 flag_signaling_nans is on and the operand is a signaling NaN. */
1590 {
1591 CASE_CONVERT:
1598 /* If the source address is 0, and the source address space
1599 cannot have a valid object at 0, fold to dest type null. */
1610 {
1611 /* Can't call fold_negate_const directly here as that doesn't
1612 handle all cases and we might not be able to negate some
1613 constants. */
1618 }
1627 {
1631 }
1637 /* Perform BIT_NOT_EXPR on each element individually. */
1639 {
1640 tree elem;
1645 {
1651 }
1654 }
1676 {
1694 else
1699 {
1705 }
1708 }
1713 {
1722 {
1727 }
1731 {
1735 }
1738 }
1742 }
1745 }
1747 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1748 indicates which particular sizetype to create. */
1750 tree
1752 {
1754 }
1755 \f
1756 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1757 is a tree code. The type of the result is taken from the operands.
1758 Both must be equivalent integer types, ala int_binop_types_match_p.
1759 If the operands are constant, so is the result. */
1761 tree
1763 {
1772 /* Handle the special case of two integer constants faster. */
1774 {
1775 /* And some specific cases even faster than that. */
1777 {
1782 }
1784 {
1787 }
1789 {
1792 }
1794 /* Handle general case of two integer constants. For sizetype
1795 constant calculations we always want to know about overflow,
1796 even in the unsigned case. */
1798 }
1801 }
1803 /* Given two values, either both of sizetype or both of bitsizetype,
1804 compute the difference between the two values. Return the value
1805 in signed type corresponding to the type of the operands. */
1807 tree
1809 {
1811 tree ctype;
1816 /* If the type is already signed, just do the simple thing. */
1824 else
1827 /* If either operand is not a constant, do the conversions to the signed
1828 type and subtract. The hardware will do the right thing with any
1829 overflow in the subtraction. */
1835 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1836 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1837 overflow) and negate (which can't either). Special-case a result
1838 of zero while we're here. */
1844 else
1848 MINUS_EXPR,
1850 }
1851 \f
1852 /* A subroutine of fold_convert_const handling conversions of an
1853 INTEGER_CST to another integer type. */
1855 static tree
1857 {
1858 /* Given an integer constant, make new constant with new type,
1859 appropriately sign-extended or truncated. Use widest_int
1860 so that any extension is done according ARG1's type. */
1864 }
1866 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1867 to an integer type. */
1869 static tree
1871 {
1873 tree t;
1875 /* The following code implements the floating point to integer
1876 conversion rules required by the Java Language Specification,
1877 that IEEE NaNs are mapped to zero and values that overflow
1878 the target precision saturate, i.e. values greater than
1879 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1880 are mapped to INT_MIN. These semantics are allowed by the
1881 C and C++ standards that simply state that the behavior of
1882 FP-to-integer conversion is unspecified upon overflow. */
1884 wide_int val;
1885 REAL_VALUE_TYPE r;
1889 {
1896 }
1898 /* If R is NaN, return zero and show we have an overflow. */
1900 {
1903 }
1905 /* See if R is less than the lower bound or greater than the
1906 upper bound. */
1909 {
1913 {
1916 }
1917 }
1920 {
1923 {
1926 {
1929 }
1930 }
1931 }
1938 }
1940 /* A subroutine of fold_convert_const handling conversions of a
1941 FIXED_CST to an integer type. */
1943 static tree
1945 {
1946 tree t;
1948 scalar_mode mode;
1950 /* Right shift FIXED_CST to temp by fbit. */
1954 {
1956 HOST_BITS_PER_DOUBLE_INT,
1959 /* Left shift temp to temp_trunc by fbit. */
1961 HOST_BITS_PER_DOUBLE_INT,
1963 }
1964 else
1965 {
1968 }
1970 /* If FIXED_CST is negative, we need to round the value toward 0.
1971 By checking if the fractional bits are not zero to add 1 to temp. */
1977 /* Given a fixed-point constant, make new constant with new type,
1978 appropriately sign-extended or truncated. */
1986 }
1988 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1989 to another floating point type. */
1991 static tree
1993 {
1994 REAL_VALUE_TYPE value;
1995 tree t;
1997 /* Don't perform the operation if flag_signaling_nans is on
1998 and the operand is a signaling NaN. */
2006 /* If converting an infinity or NAN to a representation that doesn't
2007 have one, set the overflow bit so that we can produce some kind of
2008 error message at the appropriate point if necessary. It's not the
2009 most user-friendly message, but it's better than nothing. */
2016 /* Regular overflow, conversion produced an infinity in a mode that
2017 can't represent them. */
2022 else
2025 }
2027 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2028 to a floating point type. */
2030 static tree
2032 {
2033 REAL_VALUE_TYPE value;
2034 tree t;
2042 }
2044 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2045 to another fixed-point type. */
2047 static tree
2049 {
2050 FIXED_VALUE_TYPE value;
2051 tree t;
2058 /* Propagate overflow flags. */
2062 }
2064 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2065 to a fixed-point type. */
2067 static tree
2069 {
2070 FIXED_VALUE_TYPE value;
2071 tree t;
2073 double_int di;
2080 else
2088 /* Propagate overflow flags. */
2092 }
2094 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2095 to a fixed-point type. */
2097 static tree
2099 {
2100 FIXED_VALUE_TYPE value;
2101 tree t;
2109 /* Propagate overflow flags. */
2113 }
2115 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2116 type TYPE. If no simplification can be done return NULL_TREE. */
2118 static tree
2120 {
2126 {
2133 }
2135 {
2142 }
2144 {
2151 }
2153 {
2156 {
2161 {
2167 }
2169 }
2170 }
2172 }
2174 /* Construct a vector of zero elements of vector type TYPE. */
2176 static tree
2178 {
2179 tree t;
2183 }
2185 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2187 bool
2189 {
2204 {
2219 }
2220 }
2222 /* Convert expression ARG to type TYPE. Used by the middle-end for
2223 simple conversions in preference to calling the front-end's convert. */
2225 tree
2227 {
2229 tree tem;
2240 {
2243 /* Handle conversions between pointers to different address spaces. */
2248 /* fall through */
2253 {
2257 }
2271 {
2275 }
2277 {
2281 }
2283 {
2287 }
2290 {
2308 }
2313 {
2317 }
2320 {
2334 }
2338 {
2347 integer_zero_node));
2349 {
2353 {
2359 }
2367 }
2371 }
2389 }
2390 fold_convert_exit:
2393 }
2394 \f
2395 /* Return false if expr can be assumed not to be an lvalue, true
2396 otherwise. */
2398 static bool
2400 {
2401 /* We only need to wrap lvalue tree codes. */
2403 {
2434 /* Assume the worst for front-end tree codes. */
2438 }
2441 }
2443 /* Return an expr equal to X but certainly not valid as an lvalue. */
2445 tree
2447 {
2448 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2449 us. */
2456 }
2458 /* When pedantic, return an expr equal to X but certainly not valid as a
2459 pedantic lvalue. Otherwise, return X. */
2461 static tree
2463 {
2465 }
2466 \f
2467 /* Given a tree comparison code, return the code that is the logical inverse.
2468 It is generally not safe to do this for floating-point comparisons, except
2469 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2470 ERROR_MARK in this case. */
2472 enum tree_code
2474 {
2480 {
2511 }
2512 }
2514 /* Similar, but return the comparison that results if the operands are
2515 swapped. This is safe for floating-point. */
2517 enum tree_code
2519 {
2521 {
2547 }
2548 }
2551 /* Convert a comparison tree code from an enum tree_code representation
2552 into a compcode bit-based encoding. This function is the inverse of
2553 compcode_to_comparison. */
2555 static enum comparison_code
2557 {
2559 {
2590 }
2591 }
2593 /* Convert a compcode bit-based encoding of a comparison operator back
2594 to GCC's enum tree_code representation. This function is the
2595 inverse of comparison_to_compcode. */
2597 static enum tree_code
2599 {
2601 {
2632 }
2633 }
2635 /* Return a tree for the comparison which is the combination of
2636 doing the AND or OR (depending on CODE) of the two operations LCODE
2637 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2638 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2639 if this makes the transformation invalid. */
2641 tree
2646 {
2653 {
2664 }
2667 {
2668 /* Eliminate unordered comparisons, as well as LTGT and ORD
2669 which are not used unless the mode has NaNs. */
2675 }
2677 {
2678 /* Check that the original operation and the optimized ones will trap
2679 under the same condition. */
2690 /* In a short-circuited boolean expression the LHS might be
2691 such that the RHS, if evaluated, will never trap. For
2692 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2693 if neither x nor y is NaN. (This is a mixed blessing: for
2694 example, the expression above will never trap, hence
2695 optimizing it to x < y would be invalid). */
2700 /* If the comparison was short-circuited, and only the RHS
2701 trapped, we may now generate a spurious trap. */
2706 /* If we changed the conditions that cause a trap, we lose. */
2709 }
2715 else
2716 {
2721 }
2722 }
2723 \f
2724 /* Return nonzero if two operands (typically of the same tree node)
2725 are necessarily equal. FLAGS modifies behavior as follows:
2727 If OEP_ONLY_CONST is set, only return nonzero for constants.
2728 This function tests whether the operands are indistinguishable;
2729 it does not test whether they are equal using C's == operation.
2730 The distinction is important for IEEE floating point, because
2731 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2732 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2734 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2735 even though it may hold multiple values during a function.
2736 This is because a GCC tree node guarantees that nothing else is
2737 executed between the evaluation of its "operands" (which may often
2738 be evaluated in arbitrary order). Hence if the operands themselves
2739 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2740 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2741 unset means assuming isochronic (or instantaneous) tree equivalence.
2742 Unless comparing arbitrary expression trees, such as from different
2743 statements, this flag can usually be left unset.
2745 If OEP_PURE_SAME is set, then pure functions with identical arguments
2746 are considered the same. It is used when the caller has other ways
2747 to ensure that global memory is unchanged in between.
2749 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2750 not values of expressions.
2752 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2753 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2755 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2756 any operand with side effect. This is unnecesarily conservative in the
2757 case we know that arg0 and arg1 are in disjoint code paths (such as in
2758 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2759 addresses with TREE_CONSTANT flag set so we know that &var == &var
2760 even if var is volatile. */
2762 int
2764 {
2765 /* When checking, verify at the outermost operand_equal_p call that
2766 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2767 hash value. */
2769 {
2771 {
2773 {
2780 }
2782 }
2783 else
2785 }
2787 /* If either is ERROR_MARK, they aren't equal. */
2793 /* Similar, if either does not have a type (like a released SSA name),
2794 they aren't equal. */
2798 /* We cannot consider pointers to different address space equal. */
2805 /* Check equality of integer constants before bailing out due to
2806 precision differences. */
2808 {
2809 /* Address of INTEGER_CST is not defined; check that we did not forget
2810 to drop the OEP_ADDRESS_OF flags. */
2813 }
2816 {
2817 /* If both types don't have the same signedness, then we can't consider
2818 them equal. We must check this before the STRIP_NOPS calls
2819 because they may change the signedness of the arguments. As pointers
2820 strictly don't have a signedness, require either two pointers or
2821 two non-pointers as well. */
2827 /* If both types don't have the same precision, then it is not safe
2828 to strip NOPs. */
2835 }
2836 #if 0
2837 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2838 sanity check once the issue is solved. */
2839 else
2840 /* Addresses of conversions and SSA_NAMEs (and many other things)
2841 are not defined. Check that we did not forget to drop the
2842 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2845 #endif
2847 /* In case both args are comparisons but with different comparison
2848 code, try to swap the comparison operands of one arg to produce
2849 a match and compare that variant. */
2853 {
2861 }
2864 {
2865 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2867 ;
2869 {
2870 /* If we are interested in comparing addresses ignore
2871 MEM_REF wrappings of the base that can appear just for
2872 TBAA reasons. */
2886 }
2887 else
2889 }
2891 /* When not checking adddresses, this is needed for conversions and for
2892 COMPONENT_REF. Might as well play it safe and always test this. */
2899 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2900 We don't care about side effects in that case because the SAVE_EXPR
2901 takes care of that for us. In all other cases, two expressions are
2902 equal if they have no side effects. If we have two identical
2903 expressions with side effects that should be treated the same due
2904 to the only side effects being identical SAVE_EXPR's, that will
2905 be detected in the recursive calls below.
2906 If we are taking an invariant address of two identical objects
2907 they are necessarily equal as well. */
2914 /* Next handle constant cases, those for which we can return 1 even
2915 if ONLY_CONST is set. */
2918 {
2932 {
2933 /* If we do not distinguish between signed and unsigned zero,
2934 consider them equal. */
2937 }
2941 {
2948 {
2952 }
2954 }
2958 flags)
2960 flags));
2971 flags | OEP_ADDRESS_OF
2974 /* In GIMPLE empty constructors are allowed in initializers of
2975 aggregates. */
2979 }
2984 /* Define macros to test an operand from arg0 and arg1 for equality and a
2985 variant that allows null and views null as being different from any
2986 non-null value. In the latter case, if either is null, the both
2987 must be; otherwise, do the normal comparison. */
2988 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2989 TREE_OPERAND (arg1, N), flags)
2991 #define OP_SAME_WITH_NULL(N) \
2992 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2993 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2996 {
2998 /* Two conversions are equal only if signedness and modes match. */
3000 {
3001 CASE_CONVERT:
3009 }
3019 /* For commutative ops, allow the other order. */
3027 /* If either of the pointer (or reference) expressions we are
3028 dereferencing contain a side effect, these cannot be equal,
3029 but their addresses can be. */
3036 {
3046 /* Require the same offset. */
3052 /* Fallthru. */
3060 {
3061 /* Require equal access sizes */
3067 flags)))
3069 /* Verify that access happens in similar types. */
3072 /* Verify that accesses are TBAA compatible. */
3081 /* Verify that alignment is compatible. */
3085 }
3088 /* TARGET_MEM_REF require equal extra operands. */
3099 /* Compare the array index by value if it is constant first as we
3100 may have different types but same value here. */
3106 /* Compare low bound and element size as with OEP_ADDRESS_OF
3107 we have to account for the offset of the ref. */
3112 array_ref_low_bound
3116 array_ref_element_size
3118 flags))));
3121 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3122 may be NULL when we're called to compare MEM_EXPRs. */
3137 }
3141 {
3143 /* Be sure we pass right ADDRESS_OF flag. */
3161 /* The multiplcation operands are commutative. */
3162 /* FALLTHRU */
3170 /* Otherwise take into account this is a commutative operation. */
3183 /* BIT_INSERT_EXPR has an implict operand as the type precision
3184 of op1. Need to check to make sure they are the same. */
3190 /* FALLTHRU */
3215 }
3219 {
3223 /* If not both CALL_EXPRs are either internal or normal function
3224 functions, then they are not equal. */
3227 {
3228 /* If the CALL_EXPRs call different internal functions, then they
3229 are not equal. */
3232 }
3233 else
3234 {
3235 /* If the CALL_EXPRs call different functions, then they are not
3236 equal. */
3238 flags))
3240 }
3242 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3243 {
3247 else
3251 }
3253 /* Now see if all the arguments are the same. */
3254 {
3265 /* If we get here and both argument lists are exhausted
3266 then the CALL_EXPRs are equal. */
3268 }
3271 }
3274 /* Consider __builtin_sqrt equal to sqrt. */
3282 {
3283 /* In GIMPLE constructors are used only to build vectors from
3284 elements. Individual elements in the constructor must be
3285 indexed in increasing order and form an initial sequence.
3287 We make no effort to compare constructors in generic.
3288 (see sem_variable::equals in ipa-icf which can do so for
3289 constants). */
3294 /* Be sure that vectors constructed have the same representation.
3295 We only tested element precision and modes to match.
3296 Vectors may be BLKmode and thus also check that the number of
3297 parts match. */
3310 {
3315 /* In GIMPLE the indexes can be either NULL or matching i.
3316 Double check this so we won't get false
3317 positives for GENERIC. */
3325 }
3327 }
3330 {
3331 /* Compare the STATEMENT_LISTs. */
3337 {
3338 /* The lists don't have the same number of statements. */
3344 OEP_LEXICOGRAPHIC))
3346 }
3347 }
3352 {
3359 }
3363 }
3365 #undef OP_SAME
3366 #undef OP_SAME_WITH_NULL
3367 }
3368 \f
3369 /* Similar to operand_equal_p, but strip nops first. */
3371 static bool
3373 {
3381 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3382 and see if the inner values are the same. This removes any
3383 signedness comparison, which doesn't matter here. */
3390 }
3391 \f
3392 /* See if ARG is an expression that is either a comparison or is performing
3393 arithmetic on comparisons. The comparisons must only be comparing
3394 two different values, which will be stored in *CVAL1 and *CVAL2; if
3395 they are nonzero it means that some operands have already been found.
3396 No variables may be used anywhere else in the expression except in the
3397 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3398 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3400 If this is true, return 1. Otherwise, return zero. */
3402 static int
3404 {
3408 /* We can handle some of the tcc_expression cases here. */
3418 {
3419 /* If we've already found a CVAL1 or CVAL2, this expression is
3420 two complex to handle. */
3426 }
3429 {
3452 /* First see if we can handle the first operand, then the second. For
3453 the second operand, we know *CVAL1 can't be zero. It must be that
3454 one side of the comparison is each of the values; test for the
3455 case where this isn't true by failing if the two operands
3456 are the same. */
3465 ;
3469 ;
3470 else
3474 ;
3478 ;
3479 else
3486 }
3487 }
3488 \f
3489 /* ARG is a tree that is known to contain just arithmetic operations and
3490 comparisons. Evaluate the operations in the tree substituting NEW0 for
3491 any occurrence of OLD0 as an operand of a comparison and likewise for
3492 NEW1 and OLD1. */
3494 static tree
3497 {
3502 /* We can handle some of the tcc_expression cases here. */
3510 {
3525 {
3544 }
3545 /* Fall through - ??? */
3548 {
3552 /* We need to check both for exact equality and tree equality. The
3553 former will be true if the operand has a side-effect. In that
3554 case, we know the operand occurred exactly once. */
3567 }
3571 }
3572 }
3573 \f
3574 /* Return a tree for the case when the result of an expression is RESULT
3575 converted to TYPE and OMITTED was previously an operand of the expression
3576 but is now not needed (e.g., we folded OMITTED * 0).
3578 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3579 the conversion of RESULT to TYPE. */
3581 tree
3583 {
3586 /* If the resulting operand is an empty statement, just return the omitted
3587 statement casted to void. */
3597 }
3599 /* Return a tree for the case when the result of an expression is RESULT
3600 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3601 of the expression but are now not needed.
3603 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3604 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3605 evaluated before OMITTED2. Otherwise, if neither has side effects,
3606 just do the conversion of RESULT to TYPE. */
3608 tree
3611 {
3620 }
3622 \f
3623 /* Return a simplified tree node for the truth-negation of ARG. This
3624 never alters ARG itself. We assume that ARG is an operation that
3625 returns a truth value (0 or 1).
3627 FIXME: one would think we would fold the result, but it causes
3628 problems with the dominator optimizer. */
3630 static tree
3632 {
3637 /* If this is a comparison, we can simply invert it, except for
3638 floating-point non-equality comparisons, in which case we just
3639 enclose a TRUTH_NOT_EXPR around what we have. */
3642 {
3645 && flag_trapping_math
3659 }
3662 {
3681 /* Here we can invert either operand. We invert the first operand
3682 unless the second operand is a TRUTH_NOT_EXPR in which case our
3683 result is the XOR of the first operand with the inside of the
3684 negation of the second operand. */
3689 else
3712 {
3719 /* A COND_EXPR may have a throw as one operand, which
3720 then has void type. Just leave void operands
3721 as they are. */
3727 }
3739 CASE_CONVERT:
3743 /* fall through */
3765 }
3766 }
3768 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3769 assume that ARG is an operation that returns a truth value (0 or 1
3770 for scalars, 0 or -1 for vectors). Return the folded expression if
3771 folding is successful. Otherwise, return NULL_TREE. */
3773 static tree
3775 {
3778 ? BIT_NOT_EXPR
3781 }
3783 /* Return a simplified tree node for the truth-negation of ARG. This
3784 never alters ARG itself. We assume that ARG is an operation that
3785 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3787 tree
3789 {
3795 ? BIT_NOT_EXPR
3798 }
3799 \f
3800 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3801 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3802 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3803 is the original memory reference used to preserve the alias set of
3804 the access. */
3806 static tree
3810 {
3813 /* Attempt not to lose the access path if possible. */
3815 {
3817 machine_mode nmode;
3819 tree noffset;
3829 && !reversep
3830 && !nreversep
3832 {
3835 }
3836 }
3845 {
3852 }
3867 }
3869 /* Optimize a bit-field compare.
3871 There are two cases: First is a compare against a constant and the
3872 second is a comparison of two items where the fields are at the same
3873 bit position relative to the start of a chunk (byte, halfword, word)
3874 large enough to contain it. In these cases we can avoid the shift
3875 implicit in bitfield extractions.
3877 For constants, we emit a compare of the shifted constant with the
3878 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3879 compared. For two fields at the same position, we do the ANDs with the
3880 similar mask and compare the result of the ANDs.
3882 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3883 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3884 are the left and right operands of the comparison, respectively.
3886 If the optimization described above can be done, we return the resulting
3887 tree. Otherwise we return zero. */
3889 static tree
3892 {
3895 tree unsigned_type;
3898 scalar_int_mode nmode;
3903 tree mask;
3904 tree offset;
3906 /* Get all the information about the extractions being done. If the bit size
3907 if the same as the size of the underlying object, we aren't doing an
3908 extraction at all and so can do nothing. We also don't want to
3909 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3910 then will no longer be able to replace it. */
3919 else
3920 {
3921 /* If this is not a constant, we can only do something if bit positions,
3922 sizes, signedness and storage order are the same. */
3923 rinner
3931 }
3933 /* Honor the C++ memory model and mimic what RTL expansion does. */
3937 {
3941 }
3943 /* See if we can find a mode to refer to this field. We should be able to,
3944 but fail if we can't. */
3952 /* Set signed and unsigned types of the precision of this mode for the
3953 shifts below. */
3956 /* Compute the bit position and size for the new reference and our offset
3957 within it. If the new reference is the same size as the original, we
3958 won't optimize anything, so return zero. */
3968 /* Make the mask to be used against the extracted field. */
3975 {
3979 /* If not comparing with constant, just rework the comparison
3980 and return. */
3988 }
3990 /* Otherwise, we are handling the constant case. See if the constant is too
3991 big for the field. Warn and return a tree for 0 (false) if so. We do
3992 this not only for its own sake, but to avoid having to test for this
3993 error case below. If we didn't, we might generate wrong code.
3995 For unsigned fields, the constant shifted right by the field length should
3996 be all zero. For signed fields, the high-order bits should agree with
3997 the sign bit. */
4000 {
4002 {
4006 }
4007 }
4008 else
4009 {
4012 {
4016 }
4017 }
4022 /* Single-bit compares should always be against zero. */
4024 {
4027 }
4029 /* Make a new bitfield reference, shift the constant over the
4030 appropriate number of bits and mask it with the computed mask
4031 (in case this was a signed field). If we changed it, make a new one. */
4039 mask);
4044 }
4045 \f
4046 /* Subroutine for fold_truth_andor_1: decode a field reference.
4048 If EXP is a comparison reference, we return the innermost reference.
4050 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4051 set to the starting bit number.
4053 If the innermost field can be completely contained in a mode-sized
4054 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4056 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4057 otherwise it is not changed.
4059 *PUNSIGNEDP is set to the signedness of the field.
4061 *PREVERSEP is set to the storage order of the field.
4063 *PMASK is set to the mask used. This is either contained in a
4064 BIT_AND_EXPR or derived from the width of the field.
4066 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4068 Return 0 if this is not a component reference or is one that we can't
4069 do anything with. */
4071 static tree
4076 {
4081 tree unsigned_type;
4084 /* All the optimizations using this function assume integer fields.
4085 There are problems with FP fields since the type_for_size call
4086 below can fail for, e.g., XFmode. */
4090 /* We are interested in the bare arrangement of bits, so strip everything
4091 that doesn't affect the machine mode. However, record the type of the
4092 outermost expression if it may matter below. */
4099 {
4105 }
4112 /* Reject out-of-bound accesses (PR79731). */
4120 /* If the number of bits in the reference is the same as the bitsize of
4121 the outer type, then the outer type gives the signedness. Otherwise
4122 (in case of a small bitfield) the signedness is unchanged. */
4126 /* Compute the mask to access the bitfield. */
4135 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4143 }
4145 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4146 bit positions and MASK is SIGNED. */
4148 static int
4150 {
4154 /* If this function returns true when the type of the mask is
4155 UNSIGNED, then there will be errors. In particular see
4156 gcc.c-torture/execute/990326-1.c. There does not appear to be
4157 any documentation paper trail as to why this is so. But the pre
4158 wide-int worked with that restriction and it has been preserved
4159 here. */
4164 }
4166 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4167 represents the sign bit of EXP's type. If EXP represents a sign
4168 or zero extension, also test VAL against the unextended type.
4169 The return value is the (sub)expression whose sign bit is VAL,
4170 or NULL_TREE otherwise. */
4172 tree
4174 {
4176 tree t;
4178 /* Tree EXP must have an integral type. */
4183 /* Tree VAL must be an integer constant. */
4192 /* Handle extension from a narrower type. */
4198 }
4200 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4201 to be evaluated unconditionally. */
4203 static int
4205 {
4206 /* Strip any conversions that don't change the machine mode. */
4215 /* Don't regard global variables as simple. They may be
4216 allocated in ways unknown to the compiler (shared memory,
4217 #pragma weak, etc). */
4220 /* Weakrefs are not safe to be read, since they can be NULL.
4221 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4222 have DECL_WEAK flag set. */
4224 /* Loading a static variable is unduly expensive, but global
4225 registers aren't expensive. */
4227 }
4229 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4230 to be evaluated unconditionally.
4231 I addition to simple_operand_p, we assume that comparisons, conversions,
4232 and logic-not operations are simple, if their operands are simple, too. */
4234 static bool
4236 {
4256 }
4258 \f
4259 /* The following functions are subroutines to fold_range_test and allow it to
4260 try to change a logical combination of comparisons into a range test.
4262 For example, both
4263 X == 2 || X == 3 || X == 4 || X == 5
4264 and
4265 X >= 2 && X <= 5
4266 are converted to
4267 (unsigned) (X - 2) <= 3
4269 We describe each set of comparisons as being either inside or outside
4270 a range, using a variable named like IN_P, and then describe the
4271 range with a lower and upper bound. If one of the bounds is omitted,
4272 it represents either the highest or lowest value of the type.
4274 In the comments below, we represent a range by two numbers in brackets
4275 preceded by a "+" to designate being inside that range, or a "-" to
4276 designate being outside that range, so the condition can be inverted by
4277 flipping the prefix. An omitted bound is represented by a "-". For
4278 example, "- [-, 10]" means being outside the range starting at the lowest
4279 possible value and ending at 10, in other words, being greater than 10.
4280 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4281 always false.
4283 We set up things so that the missing bounds are handled in a consistent
4284 manner so neither a missing bound nor "true" and "false" need to be
4285 handled using a special case. */
4287 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4288 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4289 and UPPER1_P are nonzero if the respective argument is an upper bound
4290 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4291 must be specified for a comparison. ARG1 will be converted to ARG0's
4292 type if both are specified. */
4294 static tree
4297 {
4298 tree tem;
4302 /* If neither arg represents infinity, do the normal operation.
4303 Else, if not a comparison, return infinity. Else handle the special
4304 comparison rules. Note that most of the cases below won't occur, but
4305 are handled for consistency. */
4308 {
4313 }
4318 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4319 for neither. In real maths, we cannot assume open ended ranges are
4320 the same. But, this is computer arithmetic, where numbers are finite.
4321 We can therefore make the transformation of any unbounded range with
4322 the value Z, Z being greater than any representable number. This permits
4323 us to treat unbounded ranges as equal. */
4327 {
4348 }
4351 }
4352 \f
4353 /* Helper routine for make_range. Perform one step for it, return
4354 new expression if the loop should continue or NULL_TREE if it should
4355 stop. */
4357 tree
4361 {
4367 {
4369 /* We can only do something if the range is testing for zero. */
4378 /* We can only do something if the range is testing for zero
4379 and if the second operand is an integer constant. Note that
4380 saying something is "in" the range we make is done by
4381 complementing IN_P since it will set in the initial case of
4382 being not equal to zero; "out" is leaving it alone. */
4389 {
4410 }
4412 /* If this is an unsigned comparison, we also know that EXP is
4413 greater than or equal to zero. We base the range tests we make
4414 on that fact, so we record it here so we can parse existing
4415 range tests. We test arg0_type since often the return type
4416 of, e.g. EQ_EXPR, is boolean. */
4418 {
4422 NULL_TREE))
4427 /* If the high bound is missing, but we have a nonzero low
4428 bound, reverse the range so it goes from zero to the low bound
4429 minus 1. */
4431 {
4436 }
4437 }
4445 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4446 low and high are non-NULL, then normalize will DTRT. */
4449 {
4454 }
4456 /* (-x) IN [a,b] -> x in [-b, -a] */
4468 /* ~ X -> -X - 1 */
4477 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4478 move a constant to the other side. */
4483 /* If EXP is signed, any overflow in the computation is undefined,
4484 so we don't worry about it so long as our computations on
4485 the bounds don't overflow. For unsigned, overflow is defined
4486 and this is exactly the right thing. */
4498 normalize:
4499 /* Check for an unsigned range which has wrapped around the maximum
4500 value thus making n_high < n_low, and normalize it. */
4502 {
4508 /* If the range is of the form +/- [ x+1, x ], we won't
4509 be able to normalize it. But then, it represents the
4510 whole range or the empty set, so make it
4511 +/- [ -, - ]. */
4515 else
4517 }
4518 else
4526 CASE_CONVERT:
4544 /* If we're converting arg0 from an unsigned type, to exp,
4545 a signed type, we will be doing the comparison as unsigned.
4546 The tests above have already verified that LOW and HIGH
4547 are both positive.
4549 So we have to ensure that we will handle large unsigned
4550 values the same way that the current signed bounds treat
4551 negative values. */
4554 {
4555 tree high_positive;
4556 tree equiv_type;
4557 /* For fixed-point modes, we need to pass the saturating flag
4558 as the 2nd parameter. */
4560 equiv_type
4563 else
4564 equiv_type
4567 /* A range without an upper bound is, naturally, unbounded.
4568 Since convert would have cropped a very large value, use
4569 the max value for the destination type. */
4570 high_positive
4577 high_positive),
4580 /* If the low bound is specified, "and" the range with the
4581 range for which the original unsigned value will be
4582 positive. */
4584 {
4587 integer_zero_node),
4588 high_positive))
4592 }
4593 else
4594 {
4595 /* Otherwise, "or" the range with the range of the input
4596 that will be interpreted as negative. */
4599 integer_zero_node),
4600 high_positive))
4604 }
4605 }
4614 }
4615 }
4617 /* Given EXP, a logical expression, set the range it is testing into
4618 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4619 actually being tested. *PLOW and *PHIGH will be made of the same
4620 type as the returned expression. If EXP is not a comparison, we
4621 will most likely not be returning a useful value and range. Set
4622 *STRICT_OVERFLOW_P to true if the return value is only valid
4623 because signed overflow is undefined; otherwise, do not change
4624 *STRICT_OVERFLOW_P. */
4626 tree
4629 {
4637 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4638 and see if we can refine the range. Some of the cases below may not
4639 happen, but it doesn't seem worth worrying about this. We "continue"
4640 the outer loop when we've changed something; otherwise we "break"
4641 the switch, which will "break" the while. */
4647 {
4653 {
4661 }
4670 }
4672 /* If EXP is a constant, we can evaluate whether this is true or false. */
4674 {
4681 }
4685 }
4687 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4688 a bitwise check i.e. when
4689 LOW == 0xXX...X00...0
4690 HIGH == 0xXX...X11...1
4691 Return corresponding mask in MASK and stem in VALUE. */
4693 static bool
4696 {
4719 }
4720 \f
4721 /* Helper routine for build_range_check and match.pd. Return the type to
4722 perform the check or NULL if it shouldn't be optimized. */
4724 tree
4726 {
4727 /* First make sure that arithmetics in this type is valid, then make sure
4728 that it wraps around. */
4734 {
4737 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4738 for the type in question, as we rely on this here. */
4748 else
4750 }
4752 }
4754 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4755 type, TYPE, return an expression to test if EXP is in (or out of, depending
4756 on IN_P) the range. Return 0 if the test couldn't be created. */
4758 tree
4761 {
4764 /* Disable this optimization for function pointer expressions
4765 on targets that require function pointer canonicalization. */
4772 {
4778 }
4800 value);
4803 {
4805 {
4809 }
4811 }
4813 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4815 {
4819 {
4821 {
4824 etype
4826 else
4829 }
4832 }
4833 }
4835 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4836 This requires wrap-around arithmetics for the type of the expression. */
4856 }
4857 \f
4858 /* Return the predecessor of VAL in its type, handling the infinite case. */
4860 static tree
4862 {
4868 else
4871 }
4873 /* Return the successor of VAL in its type, handling the infinite case. */
4875 static tree
4877 {
4883 else
4886 }
4888 /* Given two ranges, see if we can merge them into one. Return 1 if we
4889 can, 0 if we can't. Set the output range into the specified parameters. */
4891 bool
4894 {
4898 tree tem;
4908 /* Make range 0 be the range that starts first, or ends last if they
4909 start at the same value. Swap them if it isn't. */
4912 || (lowequal
4915 {
4919 }
4921 /* Now flag two cases, whether the ranges are disjoint or whether the
4922 second range is totally subsumed in the first. Note that the tests
4923 below are simplified by the ones above. */
4929 /* We now have four cases, depending on whether we are including or
4930 excluding the two ranges. */
4932 {
4933 /* If they don't overlap, the result is false. If the second range
4934 is a subset it is the result. Otherwise, the range is from the start
4935 of the second to the end of the first. */
4940 else
4942 }
4945 {
4946 /* If they don't overlap, the result is the first range. If they are
4947 equal, the result is false. If the second range is a subset of the
4948 first, and the ranges begin at the same place, we go from just after
4949 the end of the second range to the end of the first. If the second
4950 range is not a subset of the first, or if it is a subset and both
4951 ranges end at the same place, the range starts at the start of the
4952 first range and ends just before the second range.
4953 Otherwise, we can't describe this as a single range. */
4959 {
4964 {
4965 /* We are in the weird situation where high0 > high1 but
4966 high1 has no successor. Punt. */
4968 }
4969 }
4971 {
4976 {
4977 /* low0 < low1 but low1 has no predecessor. Punt. */
4979 }
4980 }
4981 else
4983 }
4986 {
4987 /* If they don't overlap, the result is the second range. If the second
4988 is a subset of the first, the result is false. Otherwise,
4989 the range starts just after the first range and ends at the
4990 end of the second. */
4995 else
4996 {
5001 {
5002 /* high1 > high0 but high0 has no successor. Punt. */
5004 }
5005 }
5006 }
5008 else
5009 {
5010 /* The case where we are excluding both ranges. Here the complex case
5011 is if they don't overlap. In that case, the only time we have a
5012 range is if they are adjacent. If the second is a subset of the
5013 first, the result is the first. Otherwise, the range to exclude
5014 starts at the beginning of the first range and ends at the end of the
5015 second. */
5017 {
5022 else
5023 {
5024 /* Canonicalize - [min, x] into - [-, x]. */
5027 {
5032 /* FALLTHROUGH */
5045 }
5047 /* Canonicalize - [x, max] into - [x, -]. */
5050 {
5055 /* FALLTHROUGH */
5071 }
5073 /* The ranges might be also adjacent between the maximum and
5074 minimum values of the given type. For
5075 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5076 return + [x + 1, y - 1]. */
5078 {
5085 }
5086 else
5088 }
5089 }
5092 else
5094 }
5098 }
5099 \f
5101 /* Subroutine of fold, looking inside expressions of the form
5102 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5103 of the COND_EXPR. This function is being used also to optimize
5104 A op B ? C : A, by reversing the comparison first.
5106 Return a folded expression whose code is not a COND_EXPR
5107 anymore, or NULL_TREE if no folding opportunity is found. */
5109 static tree
5112 {
5117 tree tem;
5122 /* If we have A op 0 ? A : -A, consider applying the following
5123 transformations:
5125 A == 0? A : -A same as -A
5126 A != 0? A : -A same as A
5127 A >= 0? A : -A same as abs (A)
5128 A > 0? A : -A same as abs (A)
5129 A <= 0? A : -A same as -abs (A)
5130 A < 0? A : -A same as -abs (A)
5132 None of these transformations work for modes with signed
5133 zeros. If A is +/-0, the first two transformations will
5134 change the sign of the result (from +0 to -0, or vice
5135 versa). The last four will fix the sign of the result,
5136 even though the original expressions could be positive or
5137 negative, depending on the sign of A.
5139 Note that all these transformations are correct if A is
5140 NaN, since the two alternatives (A and -A) are also NaNs. */
5147 /* In the case that A is of the form X-Y, '-A' (arg2) may
5148 have already been folded to Y-X, check for that. */
5156 {
5168 /* Fall through. */
5179 /* FALLTHRU */
5189 }
5191 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5192 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5193 both transformations are correct when A is NaN: A != 0
5194 is then true, and A == 0 is false. */
5198 {
5203 }
5205 /* Try some transformations of A op B ? A : B.
5207 A == B? A : B same as B
5208 A != B? A : B same as A
5209 A >= B? A : B same as max (A, B)
5210 A > B? A : B same as max (B, A)
5211 A <= B? A : B same as min (A, B)
5212 A < B? A : B same as min (B, A)
5214 As above, these transformations don't work in the presence
5215 of signed zeros. For example, if A and B are zeros of
5216 opposite sign, the first two transformations will change
5217 the sign of the result. In the last four, the original
5218 expressions give different results for (A=+0, B=-0) and
5219 (A=-0, B=+0), but the transformed expressions do not.
5221 The first two transformations are correct if either A or B
5222 is a NaN. In the first transformation, the condition will
5223 be false, and B will indeed be chosen. In the case of the
5224 second transformation, the condition A != B will be true,
5225 and A will be chosen.
5227 The conversions to max() and min() are not correct if B is
5228 a number and A is not. The conditions in the original
5229 expressions will be false, so all four give B. The min()
5230 and max() versions would give a NaN instead. */
5233 /* Avoid these transformations if the COND_EXPR may be used
5234 as an lvalue in the C++ front-end. PR c++/19199. */
5235 && (in_gimple_form
5241 {
5247 {
5256 /* In C++ a ?: expression can be an lvalue, so put the
5257 operand which will be used if they are equal first
5258 so that we can convert this back to the
5259 corresponding COND_EXPR. */
5261 {
5269 }
5276 {
5284 }
5297 }
5298 }
5301 }
5304 \f
5305 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5306 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5307 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5308 false) >= 2)
5309 #endif
5311 /* EXP is some logical combination of boolean tests. See if we can
5312 merge it into some range test. Return the new tree if so. */
5314 static tree
5317 {
5333 /* If this is an OR operation, invert both sides; we will invert
5334 again at the end. */
5338 /* If both expressions are the same, if we can merge the ranges, and we
5339 can build the range test, return it or it inverted. If one of the
5340 ranges is always true or always false, consider it to be the same
5341 expression as the other. */
5349 {
5353 }
5355 /* On machines where the branch cost is expensive, if this is a
5356 short-circuited branch and the underlying object on both sides
5357 is the same, make a non-short-circuit operation. */
5359 && !flag_sanitize_coverage
5364 {
5365 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5366 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5367 which cases we can't do this. */
5375 {
5384 {
5387 WARN_STRICT_OVERFLOW_COMPARISON);
5391 }
5392 }
5393 }
5396 }
5397 \f
5398 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5399 bit value. Arrange things so the extra bits will be set to zero if and
5400 only if C is signed-extended to its full width. If MASK is nonzero,
5401 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5403 static tree
5405 {
5408 tree temp;
5413 /* We work by getting just the sign bit into the low-order bit, then
5414 into the high-order bit, then sign-extend. We then XOR that value
5415 with C. */
5419 /* We must use a signed type in order to get an arithmetic right shift.
5420 However, we must also avoid introducing accidental overflows, so that
5421 a subsequent call to integer_zerop will work. Hence we must
5422 do the type conversion here. At this point, the constant is either
5423 zero or one, and the conversion to a signed type can never overflow.
5424 We could get an overflow if this conversion is done anywhere else. */
5433 /* If necessary, convert the type back to match the type of C. */
5438 }
5439 \f
5440 /* For an expression that has the form
5441 (A && B) || ~B
5442 or
5443 (A || B) && ~B,
5444 we can drop one of the inner expressions and simplify to
5445 A || ~B
5446 or
5447 A && ~B
5448 LOC is the location of the resulting expression. OP is the inner
5449 logical operation; the left-hand side in the examples above, while CMPOP
5450 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5451 removing a condition that guards another, as in
5452 (A != NULL && A->...) || A == NULL
5453 which we must not transform. If RHS_ONLY is true, only eliminate the
5454 right-most operand of the inner logical operation. */
5456 static tree
5459 {
5477 {
5480 {
5483 }
5484 }
5486 {
5489 {
5492 }
5493 }
5508 }
5510 /* Find ways of folding logical expressions of LHS and RHS:
5511 Try to merge two comparisons to the same innermost item.
5512 Look for range tests like "ch >= '0' && ch <= '9'".
5513 Look for combinations of simple terms on machines with expensive branches
5514 and evaluate the RHS unconditionally.
5516 For example, if we have p->a == 2 && p->b == 4 and we can make an
5517 object large enough to span both A and B, we can do this with a comparison
5518 against the object ANDed with the a mask.
5520 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5521 operations to do this with one comparison.
5523 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5524 function and the one above.
5526 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5527 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5529 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5530 two operands.
5532 We return the simplified tree or 0 if no optimization is possible. */
5534 static tree
5537 {
5538 /* If this is the "or" of two comparisons, we can do something if
5539 the comparisons are NE_EXPR. If this is the "and", we can do something
5540 if the comparisons are EQ_EXPR. I.e.,
5541 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5543 WANTED_CODE is this operation code. For single bit fields, we can
5544 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5545 comparison for one-bit fields. */
5566 /* Start by getting the comparison codes. Fail if anything is volatile.
5567 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5568 it were surrounded with a NE_EXPR. */
5577 {
5581 }
5584 {
5588 }
5599 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5602 {
5605 {
5610 }
5613 {
5619 }
5620 }
5625 /* If the RHS can be evaluated unconditionally and its operands are
5626 simple, it wins to evaluate the RHS unconditionally on machines
5627 with expensive branches. In this case, this isn't a comparison
5628 that can be merged. */
5635 {
5636 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5647 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5657 }
5659 /* See if the comparisons can be merged. Then get all the parameters for
5660 each side. */
5685 /* It must be true that the inner operation on the lhs of each
5686 comparison must be the same if we are to be able to do anything.
5687 Then see if we have constants. If not, the same must be true for
5688 the rhs's. */
5697 {
5700 }
5705 else
5708 /* If either comparison code is not correct for our logical operation,
5709 fail. However, we can convert a one-bit comparison against zero into
5710 the opposite comparison against that bit being set in the field. */
5714 {
5716 {
5717 /* Make the left operand unsigned, since we are only interested
5718 in the value of one bit. Otherwise we are doing the wrong
5719 thing below. */
5722 }
5723 else
5725 }
5727 /* This is analogous to the code for l_const above. */
5729 {
5731 {
5734 }
5735 else
5737 }
5739 /* See if we can find a mode that contains both fields being compared on
5740 the left. If we can't, fail. Otherwise, update all constants and masks
5741 to be relative to a field of that size. */
5755 {
5758 }
5766 {
5773 {
5777 }
5778 }
5780 {
5787 {
5791 }
5792 }
5794 /* If the right sides are not constant, do the same for it. Also,
5795 disallow this optimization if a size or signedness mismatch occurs
5796 between the left and right sides. */
5798 {
5801 /* Make sure the two fields on the right
5802 correspond to the left without being swapped. */
5819 {
5822 }
5831 /* Make a mask that corresponds to both fields being compared.
5832 Do this for both items being compared. If the operands are the
5833 same size and the bits being compared are in the same position
5834 then we can do this by masking both and comparing the masked
5835 results. */
5842 {
5856 }
5858 /* There is still another way we can do something: If both pairs of
5859 fields being compared are adjacent, we may be able to make a wider
5860 field containing them both.
5862 Note that we still must mask the lhs/rhs expressions. Furthermore,
5863 the mask must be shifted to account for the shift done by
5864 make_bit_field_ref. */
5873 {
5874 tree type;
5890 /* Convert to the smaller type before masking out unwanted bits. */
5893 {
5895 {
5899 }
5901 {
5905 }
5906 }
5915 }
5918 }
5920 /* Handle the case of comparisons with constants. If there is something in
5921 common between the masks, those bits of the constants must be the same.
5922 If not, the condition is always false. Test for this to avoid generating
5923 incorrect code below. */
5928 {
5930 {
5933 }
5934 else
5935 {
5938 }
5939 }
5944 /* Construct the expression we will return. First get the component
5945 reference we will make. Unless the mask is all ones the width of
5946 that field, perform the mask operation. Then compare with the
5947 merged constant. */
5958 }
5959 \f
5960 /* T is an integer expression that is being multiplied, divided, or taken a
5961 modulus (CODE says which and what kind of divide or modulus) by a
5962 constant C. See if we can eliminate that operation by folding it with
5963 other operations already in T. WIDE_TYPE, if non-null, is a type that
5964 should be used for the computation if wider than our type.
5966 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5967 (X * 2) + (Y * 4). We must, however, be assured that either the original
5968 expression would not overflow or that overflow is undefined for the type
5969 in the language in question.
5971 If we return a non-null expression, it is an equivalent form of the
5972 original computation, but need not be in the original type.
5974 We set *STRICT_OVERFLOW_P to true if the return values depends on
5975 signed overflow being undefined. Otherwise we do not change
5976 *STRICT_OVERFLOW_P. */
5978 static tree
5981 {
5982 /* To avoid exponential search depth, refuse to allow recursion past
5983 three levels. Beyond that (1) it's highly unlikely that we'll find
5984 something interesting and (2) we've probably processed it before
5985 when we built the inner expression. */
5988 tree ret;
5993 depth++;
5995 depth--;
5998 }
6000 static tree
6003 {
6015 /* Don't deal with constants of zero here; they confuse the code below. */
6025 /* Note that we need not handle conditional operations here since fold
6026 already handles those cases. So just do arithmetic here. */
6028 {
6030 /* For a constant, we can always simplify if we are a multiply
6031 or (for divide and modulus) if it is a multiple of our constant. */
6035 {
6038 /* If the multiplication overflowed, we lost information on it.
6039 See PR68142 and PR69845. */
6043 }
6047 /* If op0 is an expression ... */
6053 /* ... and has wrapping overflow, and its type is smaller
6054 than ctype, then we cannot pass through as widening. */
6059 /* ... or this is a truncation (t is narrower than op0),
6060 then we cannot pass through this narrowing. */
6063 /* ... or signedness changes for division or modulus,
6064 then we cannot pass through this conversion. */
6068 /* ... or has undefined overflow while the converted to
6069 type has not, we cannot do the operation in the inner type
6070 as that would introduce undefined overflow. */
6076 /* Pass the constant down and see if we can make a simplification. If
6077 we can, replace this expression with the inner simplification for
6078 possible later conversion to our or some other type. */
6083 code == MULT_EXPR
6085 strict_overflow_p))))
6090 /* If widening the type changes it from signed to unsigned, then we
6091 must avoid building ABS_EXPR itself as unsigned. */
6093 {
6097 {
6100 }
6102 }
6103 /* If the constant is negative, we cannot simplify this. */
6106 /* FALLTHROUGH */
6108 /* For division and modulus, type can't be unsigned, as e.g.
6109 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6110 For signed types, even with wrapping overflow, this is fine. */
6119 /* If widening the type changes the signedness, then we can't perform
6120 this optimization as that changes the result. */
6124 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6130 {
6137 }
6141 /* If the second operand is constant, this is a multiplication
6142 or floor division, by a power of two, so we can treat it that
6143 way unless the multiplier or divisor overflows. Signed
6144 left-shift overflow is implementation-defined rather than
6145 undefined in C90, so do not convert signed left shift into
6146 multiplication. */
6149 /* const_binop may not detect overflow correctly,
6150 so check for it explicitly here. */
6155 size_one_node,
6156 op1)))
6160 ctype,
6162 t1),
6167 /* See if we can eliminate the operation on both sides. If we can, we
6168 can return a new PLUS or MINUS. If we can't, the only remaining
6169 cases where we can do anything are if the second operand is a
6170 constant. */
6177 /* If not multiplication, we can only do this if both operands
6178 are divisible by c. */
6181 {
6186 }
6188 /* If this was a subtraction, negate OP1 and set it to be an addition.
6189 This simplifies the logic below. */
6191 {
6193 /* If OP1 was not easily negatable, the constant may be OP0. */
6195 {
6198 }
6199 }
6204 /* If either OP1 or C are negative, this optimization is not safe for
6205 some of the division and remainder types while for others we need
6206 to change the code. */
6208 {
6216 }
6218 /* If it's a multiply or a division/modulus operation of a multiple
6219 of our constant, do the operation and verify it doesn't overflow. */
6223 {
6226 /* We allow the constant to overflow with wrapping semantics. */
6230 }
6231 else
6234 /* If we have an unsigned type, we cannot widen the operation since it
6235 will change the result if the original computation overflowed. */
6239 /* The last case is if we are a multiply. In that case, we can
6240 apply the distributive law to commute the multiply and addition
6241 if the multiplication of the constants doesn't overflow
6242 and overflow is defined. With undefined overflow
6243 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6249 op1);
6254 /* We have a special case here if we are doing something like
6255 (C * 8) % 4 since we know that's zero. */
6258 /* If the multiplication can overflow we cannot optimize this. */
6263 {
6266 }
6268 /* ... fall through ... */
6272 /* If we can extract our operation from the LHS, do so and return a
6273 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6274 do something only if the second operand is a constant. */
6290 /* If these are the same operation types, we can associate them
6291 assuming no overflow. */
6293 {
6308 }
6310 /* If these operations "cancel" each other, we have the main
6311 optimizations of this pass, which occur when either constant is a
6312 multiple of the other, in which case we replace this with either an
6313 operation or CODE or TCODE.
6315 If we have an unsigned type, we cannot do this since it will change
6316 the result if the original computation overflowed. */
6323 {
6326 {
6333 }
6336 {
6343 }
6344 }
6349 }
6352 }
6353 \f
6354 /* Return a node which has the indicated constant VALUE (either 0 or
6355 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6356 and is of the indicated TYPE. */
6358 tree
6360 {
6369 else
6371 }
6374 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6375 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6376 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6377 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6378 COND is the first argument to CODE; otherwise (as in the example
6379 given here), it is the second argument. TYPE is the type of the
6380 original expression. Return NULL_TREE if no simplification is
6381 possible. */
6383 static tree
6388 {
6398 {
6402 /* If this operand throws an expression, then it does not make
6403 sense to try to perform a logical or arithmetic operation
6404 involving it. */
6409 }
6412 {
6417 }
6418 else
6419 /* Detect the case of mixing vector and scalar types - bail out. */
6425 /* This transformation is only worthwhile if we don't have to wrap ARG
6426 in a SAVE_EXPR and the operation can be simplified without recursing
6427 on at least one of the branches once its pushed inside the COND_EXPR. */
6436 {
6440 else
6442 }
6444 {
6448 else
6450 }
6452 /* Check that we have simplified at least one of the branches. */
6457 }
6459 \f
6460 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6462 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6463 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6464 ADDEND is the same as X.
6466 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6467 and finite. The problematic cases are when X is zero, and its mode
6468 has signed zeros. In the case of rounding towards -infinity,
6469 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6470 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6472 bool
6474 {
6478 /* Don't allow the fold with -fsignaling-nans. */
6482 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6486 /* In a vector or complex, we would need to check the sign of all zeros. */
6490 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6494 /* The mode has signed zeros, and we have to honor their sign.
6495 In this situation, there is only one case we can return true for.
6496 X - 0 is the same as X unless rounding towards -infinity is
6497 supported. */
6499 }
6501 /* Subroutine of match.pd that optimizes comparisons of a division by
6502 a nonzero integer constant against an integer constant, i.e.
6503 X/C1 op C2.
6505 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6506 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6508 enum tree_code
6511 {
6516 /* We have to do this the hard way to detect unsigned overflow.
6517 prod = int_const_binop (MULT_EXPR, c1, c2); */
6523 {
6527 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6530 }
6532 {
6535 {
6554 }
6555 }
6556 else
6557 {
6558 /* A negative divisor reverses the relational operators. */
6563 {
6582 }
6583 }
6596 }
6599 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6600 equality/inequality test, then return a simplified form of the test
6601 using a sign testing. Otherwise return NULL. TYPE is the desired
6602 result type. */
6604 static tree
6607 tree result_type)
6608 {
6609 /* If this is testing a single bit, we can optimize the test. */
6613 {
6614 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6615 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6619 /* This is only a win if casting to a signed type is cheap,
6620 i.e. when arg00's type is not a partial mode. */
6622 {
6625 result_type,
6628 }
6629 }
6632 }
6634 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6635 equality/inequality test, then return a simplified form of
6636 the test using shifts and logical operations. Otherwise return
6637 NULL. TYPE is the desired result type. */
6639 tree
6642 {
6643 /* If this is testing a single bit, we can optimize the test. */
6647 {
6656 /* First, see if we can fold the single bit test into a sign-bit
6657 test. */
6659 result_type);
6663 /* Otherwise we have (A & C) != 0 where C is a single bit,
6664 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6665 Similarly for (A & C) == 0. */
6667 /* If INNER is a right shift of a constant and it plus BITNUM does
6668 not overflow, adjust BITNUM and INNER. */
6674 {
6677 }
6679 /* If we are going to be able to omit the AND below, we must do our
6680 operations as unsigned. If we must use the AND, we have a choice.
6681 Normally unsigned is faster, but for some machines signed is. */
6699 /* Put the AND last so it can combine with more things. */
6702 /* Make sure to return the proper type. */
6706 }
6708 }
6710 /* Test whether it is preferable two swap two operands, ARG0 and
6711 ARG1, for example because ARG0 is an integer constant and ARG1
6712 isn't. */
6714 bool
6716 {
6730 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6731 for commutative and comparison operators. Ensuring a canonical
6732 form allows the optimizers to find additional redundancies without
6733 having to explicitly check for both orderings. */
6739 /* Put SSA_NAMEs last. */
6745 /* Put variables last. */
6752 }
6755 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6756 means A >= Y && A != MAX, but in this case we know that
6757 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6759 static tree
6761 {
6768 else
6777 {
6780 }
6782 {
6785 }
6786 else
6793 {
6794 /* Convert the pointer types into integer before taking the difference. */
6798 }
6799 else
6806 }
6808 /* Fold a sum or difference of at least one multiplication.
6809 Returns the folded tree or NULL if no simplification could be made. */
6811 static tree
6814 {
6818 /* (A * C) +- (B * C) -> (A+-B) * C.
6819 (A * C) +- A -> A * (C+-1).
6820 We are most concerned about the case where C is a constant,
6821 but other combinations show up during loop reduction. Since
6822 it is not difficult, try all four possibilities. */
6825 {
6828 }
6830 {
6833 }
6834 else
6835 {
6836 /* We cannot generate constant 1 for fract. */
6841 }
6843 {
6846 }
6848 {
6850 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6851 the purpose of this canonicalization. */
6855 {
6858 }
6859 else
6861 }
6862 else
6863 {
6864 /* We cannot generate constant 1 for fract. */
6869 }
6872 /* Prefer factoring a common non-constant. */
6882 /* No identical multiplicands; see if we can find a common
6883 power-of-two factor in non-power-of-two multiplies. This
6884 can help in multi-dimensional array access. */
6887 {
6890 tree maybe_same;
6894 /* Move min of absolute values to int11. */
6896 {
6901 }
6902 else
6906 /* The remainder should not be a constant, otherwise we
6907 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6908 increased the number of multiplications necessary. */
6910 {
6918 }
6919 }
6926 /* We are neither factoring zero nor minus one. */
6934 /* Same may be zero and thus the operation 'code' may overflow. Likewise
6935 same may be minus one and thus the multiplication may overflow. Perform
6936 the operations in an unsigned type. */
6941 /* If the sum evaluated to a constant that is not -INF the multiplication
6942 cannot overflow. */
6952 }
6954 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6955 specified by EXPR into the buffer PTR of length LEN bytes.
6956 Return the number of bytes placed in the buffer, or zero
6957 upon failure. */
6959 static int
6961 {
6973 /* Dry run. */
6979 {
6981 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
6982 number of bytes. */
6986 {
6993 else
6995 }
6996 else
7000 }
7002 }
7005 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7006 specified by EXPR into the buffer PTR of length LEN bytes.
7007 Return the number of bytes placed in the buffer, or zero
7008 upon failure. */
7010 static int
7012 {
7016 FIXED_VALUE_TYPE value;
7031 }
7034 /* Subroutine of native_encode_expr. Encode the REAL_CST
7035 specified by EXPR into the buffer PTR of length LEN bytes.
7036 Return the number of bytes placed in the buffer, or zero
7037 upon failure. */
7039 static int
7041 {
7047 /* There are always 32 bits in each long, no matter the size of
7048 the hosts long. We handle floating point representations with
7049 up to 192 bits. */
7058 /* Dry run. */
7067 {
7072 {
7079 else
7081 }
7082 else
7083 {
7086 {
7087 /* Reverse bytes within each long, or within the entire float
7088 if it's smaller than a long (for HFmode). */
7091 }
7092 }
7097 }
7099 }
7101 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7102 specified by EXPR into the buffer PTR of length LEN bytes.
7103 Return the number of bytes placed in the buffer, or zero
7104 upon failure. */
7106 static int
7108 {
7110 tree part;
7124 }
7127 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7128 specified by EXPR into the buffer PTR of length LEN bytes.
7129 Return the number of bytes placed in the buffer, or zero
7130 upon failure. */
7132 static int
7134 {
7144 {
7146 {
7149 }
7160 }
7162 }
7165 /* Subroutine of native_encode_expr. Encode the STRING_CST
7166 specified by EXPR into the buffer PTR of length LEN bytes.
7167 Return the number of bytes placed in the buffer, or zero
7168 upon failure. */
7170 static int
7172 {
7175 /* Wide-char strings are encoded in target byte-order so native
7176 encoding them is trivial. */
7191 {
7194 {
7197 }
7200 }
7201 else
7204 }
7207 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7208 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7209 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7210 anything, just do a dry run. If OFF is not -1 then start
7211 the encoding at byte offset OFF and encode at most LEN bytes.
7212 Return the number of bytes placed in the buffer, or zero upon failure. */
7214 int
7216 {
7217 /* We don't support starting at negative offset and -1 is special. */
7222 {
7243 }
7244 }
7247 /* Subroutine of native_interpret_expr. Interpret the contents of
7248 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7249 If the buffer cannot be interpreted, return NULL_TREE. */
7251 static tree
7253 {
7263 }
7266 /* Subroutine of native_interpret_expr. Interpret the contents of
7267 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7268 If the buffer cannot be interpreted, return NULL_TREE. */
7270 static tree
7272 {
7275 double_int result;
7276 FIXED_VALUE_TYPE fixed_value;
7286 }
7289 /* Subroutine of native_interpret_expr. Interpret the contents of
7290 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7291 If the buffer cannot be interpreted, return NULL_TREE. */
7293 static tree
7295 {
7299 /* There are always 32 bits in each long, no matter the size of
7300 the hosts long. We handle floating point representations with
7301 up to 192 bits. */
7302 REAL_VALUE_TYPE r;
7312 {
7313 /* Both OFFSET and BYTE index within a long;
7314 bitpos indexes the whole float. */
7317 {
7324 else
7326 }
7327 else
7328 {
7331 {
7332 /* Reverse bytes within each long, or within the entire float
7333 if it's smaller than a long (for HFmode). */
7336 }
7337 }
7341 }
7345 }
7348 /* Subroutine of native_interpret_expr. Interpret the contents of
7349 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7350 If the buffer cannot be interpreted, return NULL_TREE. */
7352 static tree
7354 {
7369 }
7372 /* Subroutine of native_interpret_expr. Interpret the contents of
7373 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7374 If the buffer cannot be interpreted, return NULL_TREE. */
7376 static tree
7378 {
7390 {
7395 }
7397 }
7400 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7401 the buffer PTR of length LEN as a constant of type TYPE. For
7402 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7403 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7404 return NULL_TREE. */
7406 tree
7408 {
7410 {
7432 }
7433 }
7435 /* Returns true if we can interpret the contents of a native encoding
7436 as TYPE. */
7438 static bool
7440 {
7442 {
7455 }
7456 }
7459 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7460 TYPE at compile-time. If we're unable to perform the conversion
7461 return NULL_TREE. */
7463 static tree
7465 {
7466 /* We support up to 512-bit values (for V8DFmode). */
7470 /* Check that the host and target are sane. */
7479 }
7481 /* Build an expression for the address of T. Folds away INDIRECT_REF
7482 to avoid confusing the gimplify process. */
7484 tree
7486 {
7487 /* The size of the object is not relevant when talking about its address. */
7492 {
7497 }
7507 {
7512 }
7513 else
7517 }
7519 /* Build an expression for the address of T. */
7521 tree
7523 {
7527 }
7529 /* Fold a unary expression of code CODE and type TYPE with operand
7530 OP0. Return the folded expression if folding is successful.
7531 Otherwise, return NULL_TREE. */
7533 tree
7535 {
7536 tree tem;
7537 tree arg0;
7545 {
7548 {
7549 /* Don't use STRIP_NOPS, because signedness of argument type
7550 matters. */
7552 }
7553 else
7554 {
7555 /* Strip any conversions that don't change the mode. This
7556 is safe for every expression, except for a comparison
7557 expression because its signedness is derived from its
7558 operands.
7560 Note that this is done as an internal manipulation within
7561 the constant folder, in order to find the simplest
7562 representation of the arguments so that their form can be
7563 studied. In any cases, the appropriate type conversions
7564 should be put back in the tree that will get out of the
7565 constant folder. */
7567 }
7570 {
7573 {
7577 }
7578 }
7579 }
7586 {
7593 {
7607 /* If this was a conversion, and all we did was to move into
7608 inside the COND_EXPR, bring it back out. But leave it if
7609 it is a conversion from integer to integer and the
7610 result precision is no wider than a word since such a
7611 conversion is cheap and may be optimized away by combine,
7612 while it couldn't if it were outside the COND_EXPR. Then return
7613 so we don't get into an infinite recursion loop taking the
7614 conversion out and then back in. */
7626 && (INTEGRAL_TYPE_P
7639 }
7640 }
7643 {
7649 CASE_CONVERT:
7653 {
7654 /* If we have (type) (a CMP b) and type is an integral type, return
7655 new expression involving the new type. Canonicalize
7656 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7657 non-integral type.
7658 Do not fold the result as that would not simplify further, also
7659 folding again results in recursions. */
7669 }
7671 /* Handle (T *)&A.B.C for A being of type T and B and C
7672 living at offset zero. This occurs frequently in
7673 C++ upcasting and then accessing the base. */
7677 {
7679 tree offset;
7680 machine_mode mode;
7682 tree base
7686 /* If the reference was to a (constant) zero offset, we can use
7687 the address of the base if it has the same base type
7688 as the result type and the pointer type is unqualified. */
7695 }
7699 /* Detect assigning a bitfield. */
7701 && DECL_BIT_FIELD
7703 {
7704 /* Don't leave an assignment inside a conversion
7705 unless assigning a bitfield. */
7707 /* First do the assignment, then return converted constant. */
7712 }
7714 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7715 constants (if x has signed type, the sign bit cannot be set
7716 in c). This folds extension into the BIT_AND_EXPR.
7717 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7718 very likely don't have maximal range for their precision and this
7719 transformation effectively doesn't preserve non-maximal ranges. */
7723 {
7734 <= HOST_BITS_PER_WIDE_INT
7736 {
7740 cst &= HOST_WIDE_INT_M1U
7744 && !flag_syntax_only
7747 {
7751 }
7752 }
7754 {
7759 }
7760 }
7762 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7763 cast (T1)X will fold away. We assume that this happens when X itself
7764 is a cast. */
7768 {
7772 return fold_build_pointer_plus_loc
7774 }
7776 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7777 of the same precision, and X is an integer type not narrower than
7778 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7784 {
7790 }
7792 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7793 type of X and Y (integer types only). */
7798 {
7799 /* Be careful not to introduce new overflows. */
7800 tree mult_type;
7803 else
7807 {
7814 }
7815 }
7821 {
7828 }
7839 /* Convert fabs((double)float) into (double)fabsf(float). */
7842 {
7848 targ0));
7849 }
7853 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7872 /* Note that the operand of this must be an int
7873 and its values must be 0 or 1.
7874 ("true" is a fixed value perhaps depending on the language,
7875 but we don't handle values other than 1 correctly yet.) */
7882 /* Fold *&X to X if X is an lvalue. */
7884 {
7891 }
7897 }
7900 /* If the operation was a conversion do _not_ mark a resulting constant
7901 with TREE_OVERFLOW if the original constant was not. These conversions
7902 have implementation defined behavior and retaining the TREE_OVERFLOW
7903 flag here would confuse later passes such as VRP. */
7904 tree
7907 {
7916 }
7918 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7919 operands OP0 and OP1. LOC is the location of the resulting expression.
7920 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7921 Return the folded expression if folding is successful. Otherwise,
7922 return NULL_TREE. */
7923 static tree
7926 {
7927 tree tem;
7929 /* We only do these simplifications if we are optimizing. */
7933 /* Check for things like (A || B) && (A || C). We can convert this
7934 to A || (B && C). Note that either operator can be any of the four
7935 truth and/or operations and the transformation will still be
7936 valid. Also note that we only care about order for the
7937 ANDIF and ORIF operators. If B contains side effects, this
7938 might change the truth-value of A. */
7945 {
7965 /* This case if tricky because we must either have commutative
7966 operators or else A10 must not have side-effects. */
7972 a01);
7973 }
7975 /* See if we can build a range comparison. */
7981 {
7985 }
7989 {
7993 }
7995 /* Check for the possibility of merging component references. If our
7996 lhs is another similar operation, try to merge its rhs with our
7997 rhs. Then try to merge our lhs and rhs. */
8007 && !flag_sanitize_coverage
8012 {
8019 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8020 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8021 We don't want to pack more than two leafs to a non-IF AND/OR
8022 expression.
8023 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8024 equal to IF-CODE, then we don't want to add right-hand operand.
8025 If the inner right-hand side of left-hand operand has
8026 side-effects, or isn't simple, then we can't add to it,
8027 as otherwise we might destroy if-sequence. */
8030 /* Needed for sequence points to handle trappings, and
8031 side-effects. */
8033 {
8035 arg1);
8037 tem);
8038 }
8039 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8040 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8043 /* Needed for sequence points to handle trappings, and
8044 side-effects. */
8046 {
8051 }
8052 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8053 into (A OR B).
8054 For sequence point consistancy, we need to check for trapping,
8055 and side-effects. */
8059 }
8062 }
8064 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8065 by changing CODE to reduce the magnitude of constants involved in
8066 ARG0 of the comparison.
8067 Returns a canonicalized comparison tree if a simplification was
8068 possible, otherwise returns NULL_TREE.
8069 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8070 valid if signed overflow is undefined. */
8072 static tree
8076 {
8081 /* Match A +- CST code arg1. We can change this only if overflow
8082 is undefined. */
8085 /* In principle pointers also have undefined overflow behavior,
8086 but that causes problems elsewhere. */
8093 /* Identify the constant in arg0 and its sign. */
8097 /* Overflowed constants and zero will cause problems. */
8102 /* See if we can reduce the magnitude of the constant in
8103 arg0 by changing the comparison code. */
8104 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8108 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8112 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8116 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8120 else
8124 /* Now build the constant reduced in magnitude. But not if that
8125 would produce one outside of its types range. */
8141 }
8143 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8144 overflow further. Try to decrease the magnitude of constants involved
8145 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8146 and put sole constants at the second argument position.
8147 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8149 static tree
8152 {
8153 tree t;
8158 /* Try canonicalization by simplifying arg0. */
8163 {
8167 }
8169 /* Try canonicalization by simplifying arg1 using the swapped
8170 comparison. */
8178 }
8180 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8181 space. This is used to avoid issuing overflow warnings for
8182 expressions like &p->x which can not wrap. */
8184 static bool
8186 {
8193 wide_int wi_offset;
8199 else
8215 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8216 array. */
8218 {
8219 HOST_WIDE_INT base_size;
8224 }
8227 }
8229 /* Return a positive integer when the symbol DECL is known to have
8230 a nonzero address, zero when it's known not to (e.g., it's a weak
8231 symbol), and a negative integer when the symbol is not yet in the
8232 symbol table and so whether or not its address is zero is unknown.
8233 For function local objects always return positive integer. */
8234 static int
8236 {
8241 /* Function local objects are never NULL. */
8249 }
8251 /* Subroutine of fold_binary. This routine performs all of the
8252 transformations that are common to the equality/inequality
8253 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8254 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8255 fold_binary should call fold_binary. Fold a comparison with
8256 tree code CODE and type TYPE with operands OP0 and OP1. Return
8257 the folded comparison or NULL_TREE. */
8259 static tree
8262 {
8272 /* For comparisons of pointers we can decompose it to a compile time
8273 comparison of the base objects and the offsets into the object.
8274 This requires at least one operand being an ADDR_EXPR or a
8275 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8281 {
8284 machine_mode mode;
8288 /* Get base and offset for the access. Strip ADDR_EXPR for
8289 get_inner_reference, but put it back by stripping INDIRECT_REF
8290 off the base object if possible. indirect_baseN will be true
8291 if baseN is not an address but refers to the object itself. */
8294 {
8295 base0
8301 else
8303 }
8305 {
8309 {
8310 base0
8316 else
8318 }
8321 else
8325 {
8331 {
8334 }
8335 }
8336 }
8340 {
8341 base1
8347 else
8349 }
8351 {
8355 {
8356 base1
8362 else
8364 }
8367 else
8371 {
8377 {
8380 }
8381 }
8382 }
8384 /* If we have equivalent bases we might be able to simplify. */
8388 {
8389 /* We can fold this expression to a constant if the non-constant
8390 offset parts are equal. */
8394 {
8400 "occur when comparing P +- C1 with "
8402 WARN_STRICT_OVERFLOW_CONDITIONAL);
8405 {
8419 }
8420 }
8421 /* We can simplify the comparison to a comparison of the variable
8422 offset parts if the constant offset parts are equal.
8423 Be careful to use signed sizetype here because otherwise we
8424 mess with array offsets in the wrong way. This is possible
8425 because pointer arithmetic is restricted to retain within an
8426 object and overflow on pointer differences is undefined as of
8427 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8429 {
8430 /* By converting to signed sizetype we cover middle-end pointer
8431 arithmetic which operates on unsigned pointer types of size
8432 type size and ARRAY_REF offsets which are properly sign or
8433 zero extended from their type in case it is narrower than
8434 sizetype. */
8437 else
8441 else
8448 "occur when comparing P +- C1 with "
8450 WARN_STRICT_OVERFLOW_COMPARISON);
8453 }
8454 }
8455 /* For equal offsets we can simplify to a comparison of the
8456 base addresses. */
8458 && (indirect_base0
8460 && (indirect_base1
8465 {
8471 }
8472 /* Comparison between an ordinary (non-weak) symbol and a null
8473 pointer can be eliminated since such symbols must have a non
8474 null address. In C, relational expressions between pointers
8475 to objects and null pointers are undefined. The results
8476 below follow the C++ rules with the additional property that
8477 every object pointer compares greater than a null pointer.
8478 */
8481 /* Avoid folding references to struct members at offset 0 to
8482 prevent tests like '&ptr->firstmember == 0' from getting
8483 eliminated. When ptr is null, although the -> expression
8484 is strictly speaking invalid, GCC retains it as a matter
8485 of QoI. See PR c/44555. */
8488 && indirect_base0
8489 /* The caller guarantees that when one of the arguments is
8490 constant (i.e., null in this case) it is second. */
8492 {
8494 {
8505 }
8506 }
8507 }
8509 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8510 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8511 the resulting offset is smaller in absolute value than the
8512 original one and has the same sign. */
8521 {
8526 tree cst;
8528 "occur when combining constants around "
8531 /* Put the constant on the side where it doesn't overflow and is
8532 of lower absolute value and of same sign than before. */
8539 {
8542 variable1,
8546 }
8554 {
8560 variable2);
8561 }
8562 }
8568 /* If we are comparing an expression that just has comparisons
8569 of two integer values, arithmetic expressions of those comparisons,
8570 and constants, we can simplify it. There are only three cases
8571 to check: the two values can either be equal, the first can be
8572 greater, or the second can be greater. Fold the expression for
8573 those three values. Since each value must be 0 or 1, we have
8574 eight possibilities, each of which corresponds to the constant 0
8575 or 1 or one of the six possible comparisons.
8577 This handles common cases like (a > b) == 0 but also handles
8578 expressions like ((x > y) - (y > x)) > 0, which supposedly
8579 occur in macroized code. */
8582 {
8587 /* Don't handle degenerate cases here; they should already
8588 have been handled anyway. */
8597 {
8601 /* We can't just pass T to eval_subst in case cval1 or cval2
8602 was the same as ARG1. */
8604 tree high_result
8608 arg1);
8609 tree equal_result
8613 arg1);
8614 tree low_result
8618 arg1);
8620 /* All three of these results should be 0 or 1. Confirm they are.
8621 Then use those values to select the proper code to use. */
8626 {
8627 /* Make a 3-bit mask with the high-order bit being the
8628 value for `>', the next for '=', and the low for '<'. */
8632 {
8634 /* Always false. */
8655 /* Always true. */
8657 }
8660 {
8664 }
8666 }
8667 }
8668 }
8671 }
8674 /* Subroutine of fold_binary. Optimize complex multiplications of the
8675 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8676 argument EXPR represents the expression "z" of type TYPE. */
8678 static tree
8680 {
8685 {
8688 }
8690 {
8693 }
8694 else
8695 {
8699 }
8708 }
8711 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8712 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8713 true if successful. */
8715 static bool
8717 {
8721 {
8724 }
8726 {
8732 else
8734 }
8735 else
8741 }
8743 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8744 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8745 NULL_TREE otherwise. */
8747 static tree
8749 {
8768 {
8772 }
8775 {
8781 }
8782 else
8784 }
8786 /* Try to fold a pointer difference of type TYPE two address expressions of
8787 array references AREF0 and AREF1 using location LOC. Return a
8788 simplified expression for the difference or NULL_TREE. */
8790 static tree
8793 {
8798 /* If the bases are array references as well, recurse. If the bases
8799 are pointer indirections compute the difference of the pointers.
8800 If the bases are equal, we are set. */
8803 && (base_offset
8807 && (base_offset
8813 {
8819 base_offset,
8822 }
8824 }
8826 /* If the real or vector real constant CST of type TYPE has an exact
8827 inverse, return it, else return NULL. */
8829 tree
8831 {
8832 REAL_VALUE_TYPE r;
8833 tree unit_type;
8834 machine_mode mode;
8838 {
8848 {
8855 {
8860 }
8863 }
8867 }
8868 }
8870 /* Mask out the tz least significant bits of X of type TYPE where
8871 tz is the number of trailing zeroes in Y. */
8872 static wide_int
8874 {
8879 }
8881 /* Return true when T is an address and is known to be nonzero.
8882 For floating point we further ensure that T is not denormal.
8883 Similar logic is present in nonzero_address in rtlanal.h.
8885 If the return value is based on the assumption that signed overflow
8886 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8887 change *STRICT_OVERFLOW_P. */
8889 static bool
8891 {
8895 /* Doing something useful for floating point would need more work. */
8901 {
8904 strict_overflow_p);
8910 strict_overflow_p);
8918 }
8921 {
8924 strict_overflow_p);
8932 strict_overflow_p);
8947 strict_overflow_p);
8951 strict_overflow_p);
8954 {
8966 }
8970 }
8972 }
8974 /* Return true when T is an address and is known to be nonzero.
8975 Handle warnings about undefined signed overflow. */
8977 bool
8979 {
8986 "determining that expression is always "
8988 WARN_STRICT_OVERFLOW_MISC);
8990 }
8992 /* Return true if T is known not to be equal to an integer W. */
8994 bool
8996 {
8998 value_range_type rtype;
9000 {
9009 {
9014 }
9019 /* If T has some known zero bits and W has any of those bits set,
9020 then T is known not to be equal to W. */
9028 }
9029 }
9031 /* Fold a binary expression of code CODE and type TYPE with operands
9032 OP0 and OP1. LOC is the location of the resulting expression.
9033 Return the folded expression if folding is successful. Otherwise,
9034 return NULL_TREE. */
9036 tree
9039 {
9054 /* Strip any conversions that don't change the mode. This is
9055 safe for every expression, except for a comparison expression
9056 because its signedness is derived from its operands. So, in
9057 the latter case, only strip conversions that don't change the
9058 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9059 preserved.
9061 Note that this is done as an internal manipulation within the
9062 constant folder, in order to find the simplest representation
9063 of the arguments so that their form can be studied. In any
9064 cases, the appropriate type conversions should be put back in
9065 the tree that will get out of the constant folder. */
9068 {
9071 }
9072 else
9073 {
9076 }
9078 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9079 constant but we can't do arithmetic on them. */
9081 {
9084 {
9088 }
9089 }
9091 /* If this is a commutative operation, and ARG0 is a constant, move it
9092 to ARG1 to reduce the number of tests below. */
9097 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9098 to ARG1 to reduce the number of tests below. */
9107 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9109 First check for cases where an arithmetic operation is applied to a
9110 compound, conditional, or comparison operation. Push the arithmetic
9111 operation inside the compound or conditional to see if any folding
9112 can then be done. Convert comparison to conditional for this purpose.
9113 The also optimizes non-constant cases that used to be done in
9114 expand_expr.
9116 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9117 one of the operands is a comparison and the other is a comparison, a
9118 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9119 code below would make the expression more complex. Change it to a
9120 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9121 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9134 {
9138 boolean_type_node,
9146 }
9150 {
9152 {
9157 tem);
9158 }
9160 {
9165 tem);
9166 }
9171 {
9177 }
9182 {
9188 }
9189 }
9192 {
9194 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9197 {
9203 }
9205 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9208 {
9209 tree base;
9210 HOST_WIDE_INT coffset;
9219 }
9224 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9230 arg1),
9232 arg0)));
9238 {
9239 /* X + (X / CST) * -CST is X % CST. */
9244 {
9253 cst0));
9254 }
9255 }
9257 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9258 one. Make sure the type is not saturating and has the signedness of
9259 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9260 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9267 {
9271 }
9274 {
9275 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9276 (plus (plus (mult) (mult)) (foo)) so that we can
9277 take advantage of the factoring cases below. */
9286 {
9292 else
9305 parg0),
9307 marg)),
9311 return
9317 parg1)));
9318 }
9319 }
9320 else
9321 {
9322 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9323 to __complex__ ( x, y ). This is not the same for SNaNs or
9324 if signed zeros are involved. */
9328 {
9335 {
9339 {
9345 }
9347 {
9353 }
9354 }
9355 }
9357 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9358 We associate floats only if the user has specified
9359 -fassociative-math. */
9363 {
9368 {
9369 tree tree0;
9372 }
9373 }
9374 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9375 We associate floats only if the user has specified
9376 -fassociative-math. */
9380 {
9385 {
9386 tree tree0;
9389 }
9390 }
9391 }
9393 bit_rotate:
9394 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9395 is a rotate of A by C1 bits. */
9396 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9397 is a rotate of A by B bits.
9398 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9399 though in this case CODE must be | and not + or ^, otherwise
9400 it doesn't return A when B is 0. */
9401 {
9403 tree rtype;
9412 /* Only create rotates in complete modes. Other cases are not
9413 expanded properly. */
9416 {
9429 {
9434 }
9439 {
9442 code0 == LSHIFT_EXPR
9445 }
9447 {
9457 {
9461 orig_tree01);
9463 }
9464 }
9468 {
9479 {
9483 orig_tree01);
9485 }
9486 }
9487 }
9488 }
9490 associate:
9491 /* In most languages, can't associate operations on floats through
9492 parentheses. Rather than remember where the parentheses were, we
9493 don't associate floats at all, unless the user has specified
9494 -fassociative-math.
9495 And, we need to make sure type is not saturating. */
9499 {
9505 /* Split both trees into variables, constants, and literals. Then
9506 associate each group together, the constants with literals,
9507 then the result with variables. This increases the chances of
9508 literals being recombined later and of generating relocatable
9509 expressions for the sum of a constant and literal. */
9517 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9521 /* With undefined overflow prefer doing association in a type
9522 which wraps on overflow, if that is one of the operand types. */
9525 {
9533 }
9535 /* With undefined overflow we can only associate constants with one
9536 variable, and constants whose association doesn't overflow. */
9539 {
9541 {
9542 /* ??? If split_tree would handle NEGATE_EXPR we could
9543 simply reject these cases and the allowed cases would
9544 be the var0/minus_var1 ones. */
9550 {
9553 }
9560 {
9563 }
9569 /* The only case we can still associate with two variables
9570 is if they cancel out. */
9574 }
9580 }
9582 /* Only do something if we found more than two objects. Otherwise,
9583 nothing has changed and we risk infinite recursion. */
9591 {
9603 {
9607 }
9609 {
9613 }
9615 /* Preserve the MINUS_EXPR if the negative part of the literal is
9616 greater than the positive part. Otherwise, the multiplicative
9617 folding code (i.e extract_muldiv) may be fooled in case
9618 unsigned constants are subtracted, like in the following
9619 example: ((X*2 + 4) - 8U)/2. */
9621 {
9625 /* But avoid ending up with only negated parts. */
9627 {
9631 }
9632 else
9633 {
9637 }
9638 }
9640 /* Don't introduce overflows through reassociation. */
9645 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9652 /* Eliminate minus_con0. */
9654 {
9661 else
9664 }
9666 /* Eliminate minus_var0. */
9668 {
9672 else
9675 }
9677 return
9680 }
9681 }
9686 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9694 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9695 __complex__ ( x, -y ). This is not the same for SNaNs or if
9696 signed zeros are involved. */
9700 {
9707 {
9711 {
9713 arg1r ? arg1r
9718 }
9720 {
9724 arg1i ? arg1i
9727 }
9728 }
9729 }
9731 /* A - B -> A + (-B) if B is easily negatable. */
9735 /* Avoid this transformation if B is a positive REAL_CST. */
9743 /* Fold &a[i] - &a[j] to i-j. */
9748 {
9754 }
9756 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9757 one. Make sure the type is not saturating and has the signedness of
9758 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9759 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9766 {
9770 }
9776 {
9777 /* Transform x * -C into -x * C if x is easily negatable. */
9792 {
9795 "occur when simplifying "
9797 WARN_STRICT_OVERFLOW_MISC);
9799 }
9801 /* Optimize z * conj(z) for integer complex numbers. */
9808 }
9809 else
9810 {
9811 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9812 This is not the same for NaNs or if signed zeros are
9813 involved. */
9819 {
9822 return
9828 return
9833 }
9835 /* Optimize z * conj(z) for floating point complex numbers.
9836 Guarded by flag_unsafe_math_optimizations as non-finite
9837 imaginary components don't produce scalar results. */
9846 }
9850 /* Canonicalize (X & C1) | C2. */
9854 {
9859 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9867 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9869 {
9872 }
9874 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9875 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9876 mode which allows further optimizations. */
9881 {
9886 {
9889 }
9890 }
9893 {
9898 }
9899 }
9901 /* See if this can be simplified into a rotate first. If that
9902 is unsuccessful continue in the association code. */
9906 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9914 /* See if this can be simplified into a rotate first. If that
9915 is unsuccessful continue in the association code. */
9919 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9924 {
9925 tree tem2;
9932 }
9933 /* Fold ~X & 1 as (X & 1) == 0. */
9937 {
9938 tree tem2;
9945 }
9946 /* Fold !X & 1 as X == 0. */
9949 {
9953 }
9955 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
9956 multiple of 1 << CST. */
9958 {
9965 }
9967 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
9968 bits from CST2. */
9972 {
9974 wide_int masked
9981 {
9982 /* Avoid the transform if arg1 is a mask of some
9983 mode which allows further optimizations. */
9990 }
9991 }
9993 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
9994 ((A & N) + B) & M -> (A + B) & M
9995 Similarly if (N & M) == 0,
9996 ((A | N) + B) & M -> (A + B) & M
9997 and for - instead of + (or unary - instead of +)
9998 and/or ^ instead of |.
9999 If B is constant and (B & M) == 0, fold into A & M. */
10001 {
10010 {
10013 wide_int cst0;
10015 /* Now we know that arg0 is (C + D) or (C - D) or
10016 -C and arg1 (M) is == (1LL << cst) - 1.
10017 Store C into PMOP[0] and D into PMOP[1]. */
10021 {
10024 }
10031 {
10040 {
10043 }
10046 /* If C or D is of the form (A & N) where
10047 (N & M) == M, or of the form (A | N) or
10048 (A ^ N) where (N & M) == 0, replace it with A. */
10052 /* If C or D is a N where (N & M) == 0, it can be
10053 omitted (assumed 0). */
10061 }
10063 /* Only build anything new if we optimized one or both arguments
10064 above. */
10068 {
10071 {
10072 /* Perform the operations in a type that has defined
10073 overflow behavior. */
10079 }
10084 {
10092 else
10094 }
10097 else
10100 /* TEM is now the new binary +, - or unary - replacement. */
10104 }
10105 }
10106 }
10108 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10111 {
10116 return
10118 }
10123 /* Don't touch a floating-point divide by zero unless the mode
10124 of the constant can represent infinity. */
10130 /* (-A) / (-B) -> A / B */
10142 /* Fall through */
10145 /* Simplify A / (B << N) where A and B are positive and B is
10146 a power of 2, to A >> (N + log2(B)). */
10151 {
10154 {
10162 WARN_STRICT_OVERFLOW_MISC);
10168 }
10169 }
10171 /* Fall through */
10179 /* Convert -A / -B to A / B when the type is signed and overflow is
10180 undefined. */
10184 {
10187 "when distributing negation across "
10189 WARN_STRICT_OVERFLOW_MISC);
10194 }
10198 {
10201 "when distributing negation across "
10203 WARN_STRICT_OVERFLOW_MISC);
10208 }
10210 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10211 operation, EXACT_DIV_EXPR.
10213 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10214 At one time others generated faster code, it's not clear if they do
10215 after the last round to changes to the DIV code in expmed.c. */
10226 {
10230 WARN_STRICT_OVERFLOW_MISC);
10232 }
10244 {
10248 WARN_STRICT_OVERFLOW_MISC);
10250 }
10258 /* Since negative shift count is not well-defined,
10259 don't try to compute it in the compiler. */
10265 /* If we have a rotate of a bit operation with the rotate count and
10266 the second operand of the bit operation both constant,
10267 permute the two operations. */
10273 {
10281 }
10283 /* Two consecutive rotates adding up to the some integer
10284 multiple of the precision of the type can be ignored. */
10300 /* Note that the operands of this must be ints
10301 and their values must be 0 or 1.
10302 ("true" is a fixed value perhaps depending on the language.) */
10303 /* If first arg is constant zero, return it. */
10306 /* FALLTHRU */
10308 /* If either arg is constant true, drop it. */
10312 /* Preserve sequence points. */
10315 /* If second arg is constant zero, result is zero, but first arg
10316 must be evaluated. */
10319 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10320 case will be handled here. */
10324 /* !X && X is always false. */
10328 /* X && !X is always false. */
10333 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10334 means A >= Y && A != MAX, but in this case we know that
10335 A < X <= MAX. */
10339 {
10347 }
10356 /* Note that the operands of this must be ints
10357 and their values must be 0 or true.
10358 ("true" is a fixed value perhaps depending on the language.) */
10359 /* If first arg is constant true, return it. */
10362 /* FALLTHRU */
10364 /* If either arg is constant zero, drop it. */
10368 /* Preserve sequence points. */
10371 /* If second arg is constant true, result is true, but we must
10372 evaluate first arg. */
10375 /* Likewise for first arg, but note this only occurs here for
10376 TRUTH_OR_EXPR. */
10380 /* !X || X is always true. */
10384 /* X || !X is always true. */
10389 /* (X && !Y) || (!X && Y) is X ^ Y */
10392 {
10409 }
10418 /* If the second arg is constant zero, drop it. */
10421 /* If the second arg is constant true, this is a logical inversion. */
10423 {
10426 }
10427 /* Identical arguments cancel to zero. */
10431 /* !X ^ X is always true. */
10436 /* X ^ !X is always true. */
10452 /* bool_var != 1 becomes !bool_var. */
10459 /* bool_var == 0 becomes !bool_var. */
10466 /* !exp != 0 becomes !exp */
10471 /* If this is an EQ or NE comparison with zero and ARG0 is
10472 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10473 two operations, but the latter can be done in one less insn
10474 on machines that have only two-operand insns or on which a
10475 constant cannot be the first operand. */
10478 {
10483 {
10490 arg1);
10491 }
10494 {
10501 arg1);
10502 }
10503 }
10505 /* If this is an NE or EQ comparison of zero against the result of a
10506 signed MOD operation whose second operand is a power of 2, make
10507 the MOD operation unsigned since it is simpler and equivalent. */
10515 {
10525 }
10527 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10528 C1 is a valid shift constant, and C2 is a power of two, i.e.
10529 a single bit. */
10533 == INTEGER_CST
10536 {
10541 /* Check for a valid shift count. */
10543 {
10547 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10548 can be rewritten as (X & (C2 << C1)) != 0. */
10550 {
10555 }
10556 /* Otherwise, for signed (arithmetic) shifts,
10557 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10558 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10562 /* Otherwise, of unsigned (logical) shifts,
10563 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10564 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10565 else
10569 arg000);
10570 }
10571 }
10573 /* If this is a comparison of a field, we may be able to simplify it. */
10576 /* Handle the constant case even without -O
10577 to make sure the warnings are given. */
10579 {
10583 }
10585 /* Optimize comparisons of strlen vs zero to a compare of the
10586 first character of the string vs zero. To wit,
10587 strlen(ptr) == 0 => *ptr == 0
10588 strlen(ptr) != 0 => *ptr != 0
10589 Other cases should reduce to one of these two (or a constant)
10590 due to the return value of strlen being unsigned. */
10593 {
10601 {
10606 }
10607 }
10609 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10610 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10614 {
10619 {
10621 {
10624 }
10627 }
10628 }
10630 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10631 (X & C) == 0 when C is a single bit. */
10636 {
10643 arg1));
10644 }
10646 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10647 constant C is a power of two, i.e. a single bit. */
10654 {
10658 }
10660 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10661 when is C is a power of two, i.e. a single bit. */
10668 {
10674 }
10678 {
10681 }
10683 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10686 {
10694 {
10700 }
10702 {
10708 }
10710 {
10716 }
10718 {
10724 }
10725 }
10729 {
10736 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10737 operand_equal_p guarantees no side-effects so we don't need
10738 to use omit_one_operand on Z. */
10742 arg10));
10746 arg11));
10750 arg10));
10754 arg11));
10756 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10759 {
10765 }
10766 }
10768 /* Attempt to simplify equality/inequality comparisons of complex
10769 values. Only lower the comparison if the result is known or
10770 can be simplified to a single scalar comparison. */
10775 {
10780 {
10783 }
10784 else
10785 {
10788 }
10791 {
10794 }
10795 else
10796 {
10799 }
10803 {
10805 {
10810 }
10811 else
10812 {
10817 }
10818 }
10822 {
10824 {
10829 }
10830 else
10831 {
10836 }
10837 }
10838 }
10850 /* Transform comparisons of the form X +- C CMP X. */
10855 {
10860 /* (X - c) > X becomes false. */
10866 /* Likewise (X + c) < X becomes false. */
10872 /* Convert (X - c) <= X to true. */
10879 /* Convert (X + c) >= X to true. */
10885 }
10887 /* If we are comparing an ABS_EXPR with a constant, we can
10888 convert all the cases into explicit comparisons, but they may
10889 well not be faster than doing the ABS and one comparison.
10890 But ABS (X) <= C is a range comparison, which becomes a subtraction
10891 and a comparison, and is probably faster. */
10905 /* Convert ABS_EXPR<x> >= 0 to true. */
10912 {
10915 "when simplifying comparison of "
10917 WARN_STRICT_OVERFLOW_CONDITIONAL);
10920 arg0);
10921 }
10923 /* Convert ABS_EXPR<x> < 0 to false. */
10928 {
10931 "when simplifying comparison of "
10933 WARN_STRICT_OVERFLOW_CONDITIONAL);
10936 arg0);
10937 }
10939 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
10940 and similarly for >= into !=. */
10950 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
10951 otherwise Y might be >= # of bits in X's type and thus e.g.
10952 (unsigned char) (1 << Y) for Y 15 might be 0.
10953 If the cast is widening, then 1 << Y should have unsigned type,
10954 otherwise if Y is number of bits in the signed shift type minus 1,
10955 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
10956 31 might be 0xffffffff80000000. */
10967 {
10973 }
10985 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
10986 {
10998 }
11003 /* When pedantic, a compound expression can be neither an lvalue
11004 nor an integer constant expression. */
11007 /* Don't let (0, 0) be null pointer constant. */
11013 /* An ASSERT_EXPR should never be passed to fold_binary. */
11019 }
11021 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11022 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11023 of GOTO_EXPR. */
11025 static tree
11027 {
11029 {
11036 /* fall through */
11040 }
11041 }
11043 /* Return whether the sub-tree ST contains a label which is accessible from
11044 outside the sub-tree. */
11046 static bool
11048 {
11049 return
11051 }
11053 /* Fold a ternary expression of code CODE and type TYPE with operands
11054 OP0, OP1, and OP2. Return the folded expression if folding is
11055 successful. Otherwise, return NULL_TREE. */
11057 tree
11060 {
11061 tree tem;
11068 /* If this is a commutative operation, and OP0 is a constant, move it
11069 to OP1 to reduce the number of tests below. */
11078 /* Strip any conversions that don't change the mode. This is safe
11079 for every expression, except for a comparison expression because
11080 its signedness is derived from its operands. So, in the latter
11081 case, only strip conversions that don't change the signedness.
11083 Note that this is done as an internal manipulation within the
11084 constant folder, in order to find the simplest representation of
11085 the arguments so that their form can be studied. In any cases,
11086 the appropriate type conversions should be put back in the tree
11087 that will get out of the constant folder. */
11089 {
11092 }
11095 {
11098 }
11101 {
11104 }
11107 {
11111 {
11117 }
11122 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11123 so all simple results must be passed through pedantic_non_lvalue. */
11125 {
11128 /* Only optimize constant conditions when the selected branch
11129 has the same type as the COND_EXPR. This avoids optimizing
11130 away "c ? x : throw", where the throw has a void type.
11131 Avoid throwing away that operand which contains label. */
11138 }
11140 {
11145 {
11150 {
11158 }
11162 }
11163 }
11165 /* If we have A op B ? A : C, we may be able to convert this to a
11166 simpler expression, depending on the operation and the values
11167 of B and C. Signed zeros prevent all of these transformations,
11168 for reasons given above each one.
11170 Also try swapping the arguments and inverting the conditional. */
11174 {
11178 }
11183 {
11187 {
11191 }
11192 }
11194 /* If the second operand is simpler than the third, swap them
11195 since that produces better jump optimization results. */
11198 {
11200 /* See if this can be inverted. If it can't, possibly because
11201 it was a floating-point inequality comparison, don't do
11202 anything. */
11206 }
11208 /* Convert A ? 1 : 0 to simply A. */
11213 /* If we try to convert OP0 to our type, the
11214 call to fold will try to move the conversion inside
11215 a COND, which will recurse. In that case, the COND_EXPR
11216 is probably the best choice, so leave it alone. */
11220 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11221 over COND_EXPR in cases such as floating point comparisons. */
11230 arg0)));
11232 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11237 {
11238 /* sign_bit_p looks through both zero and sign extensions,
11239 but for this optimization only sign extensions are
11240 usable. */
11243 {
11246 {
11249 }
11251 }
11252 /* sign_bit_p only checks ARG1 bits within A's precision.
11253 If <sign bit of A> has wider type than A, bits outside
11254 of A's precision in <sign bit of A> need to be checked.
11255 If they are all 0, this optimization needs to be done
11256 in unsigned A's type, if they are all 1 in signed A's type,
11257 otherwise this can't be done. */
11263 {
11265 tree tem_type;
11278 {
11281 }
11283 {
11286 }
11287 else
11289 }
11292 return
11298 arg1)));
11299 }
11301 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11302 already handled above. */
11307 {
11317 op1);
11318 }
11320 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11321 is probably obsolete because the first operand should be a
11322 truth value (that's why we have the two cases above), but let's
11323 leave it in until we can confirm this for all front-ends. */
11335 /* Disable the transformations below for vectors, since
11336 fold_binary_op_with_conditional_arg may undo them immediately,
11337 yielding an infinite loop. */
11341 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11350 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11355 {
11357 /* Only perform transformation if ARG0 is easily inverted. */
11361 ? BIT_IOR_EXPR
11364 op1);
11365 }
11367 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11372 {
11374 /* Only perform transformation if ARG0 is easily inverted. */
11380 op2);
11381 }
11383 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11395 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11396 of fold_ternary on them. */
11404 {
11414 {
11419 {
11427 }
11428 }
11429 }
11431 /* On constants we can use native encode/interpret to constant
11432 fold (nearly) all BIT_FIELD_REFs. */
11436 {
11439 /* Limit us to a reasonable amount of work. To relax the
11440 other limitations we need bit-shifting of the buffer
11441 and rounding up the size. */
11445 {
11447 unsigned HOST_WIDE_INT len
11452 {
11457 }
11458 }
11459 }
11464 /* For integers we can decompose the FMA if possible. */
11476 {
11492 {
11497 /* Make sure that the perm value is in an acceptable
11498 range. */
11507 else
11515 }
11518 {
11523 }
11528 {
11533 }
11539 {
11543 }
11548 /* Some targets are deficient and fail to expand a single
11549 argument permutation while still allowing an equivalent
11550 2-argument version. */
11554 {
11557 }
11560 {
11567 }
11571 }
11575 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11578 {
11584 wide_int tem2
11588 }
11593 {
11595 unsigned HOST_WIDE_INT elsize
11598 {
11602 else
11603 {
11611 }
11612 }
11613 }
11619 }
11621 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11622 of an array (or vector). */
11624 tree
11626 {
11631 {
11634 {
11635 /* Static constructors for variably sized objects makes no sense. */
11639 }
11640 }
11651 offset_int max_index;
11656 {
11657 /* Array constructor might explicitly set index, or specify a range,
11658 or leave index NULL meaning that it is next index after previous
11659 one. */
11661 {
11664 else
11665 {
11669 }
11670 }
11671 else
11672 {
11678 }
11680 /* Do we have match? */
11684 }
11686 }
11688 /* Perform constant folding and related simplification of EXPR.
11689 The related simplifications include x*1 => x, x*0 => 0, etc.,
11690 and application of the associative law.
11691 NOP_EXPR conversions may be removed freely (as long as we
11692 are careful not to change the type of the overall expression).
11693 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11694 but we can constant-fold them if they have constant operands. */
11696 #ifdef ENABLE_FOLD_CHECKING
11697 # define fold(x) fold_1 (x)
11699 static
11700 #endif
11701 tree
11703 {
11707 tree tem;
11710 /* Return right away if a constant. */
11714 /* CALL_EXPR-like objects with variable numbers of operands are
11715 treated specially. */
11717 {
11719 {
11722 }
11724 }
11727 {
11732 {
11750 }
11751 }
11754 {
11756 {
11763 {
11768 }
11771 }
11773 /* Return a VECTOR_CST if possible. */
11775 {
11781 tree val;
11787 }
11795 }
11797 #ifdef ENABLE_FOLD_CHECKING
11798 #undef fold
11805 /* When --enable-checking=fold, compute a digest of expr before
11806 and after actual fold call to see if fold did not accidentally
11807 change original expr. */
11809 tree
11811 {
11812 tree ret;
11832 }
11834 void
11836 {
11847 }
11849 static void
11851 {
11853 }
11855 static void
11858 {
11864 recursive_label:
11874 {
11875 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
11880 }
11888 {
11889 /* Allow these fields to be modified. */
11890 tree tmp;
11899 {
11902 }
11903 }
11914 {
11917 {
11932 }
11936 {
11949 }
11966 {
11972 }
11975 {
11977 {
11980 }
11982 }
11993 {
11996 }
12006 }
12007 }
12009 /* Helper function for outputting the checksum of a tree T. When
12010 debugging with gdb, you can "define mynext" to be "next" followed
12011 by "call debug_fold_checksum (op0)", then just trace down till the
12012 outputs differ. */
12014 DEBUG_FUNCTION void
12016 {
12031 }
12033 #endif
12035 /* Fold a unary tree expression with code CODE of type TYPE with an
12036 operand OP0. LOC is the location of the resulting expression.
12037 Return a folded expression if successful. Otherwise, return a tree
12038 expression with code CODE of type TYPE with an operand OP0. */
12040 tree
12043 {
12044 tree tem;
12045 #ifdef ENABLE_FOLD_CHECKING
12054 #endif
12060 #ifdef ENABLE_FOLD_CHECKING
12067 #endif
12069 }
12071 /* Fold a binary tree expression with code CODE of type TYPE with
12072 operands OP0 and OP1. LOC is the location of the resulting
12073 expression. Return a folded expression if successful. Otherwise,
12074 return a tree expression with code CODE of type TYPE with operands
12075 OP0 and OP1. */
12077 tree
12080 MEM_STAT_DECL)
12081 {
12082 tree tem;
12083 #ifdef ENABLE_FOLD_CHECKING
12100 #endif
12106 #ifdef ENABLE_FOLD_CHECKING
12121 #endif
12123 }
12125 /* Fold a ternary tree expression with code CODE of type TYPE with
12126 operands OP0, OP1, and OP2. Return a folded expression if
12127 successful. Otherwise, return a tree expression with code CODE of
12128 type TYPE with operands OP0, OP1, and OP2. */
12130 tree
12133 {
12134 tree tem;
12135 #ifdef ENABLE_FOLD_CHECKING
12159 #endif
12166 #ifdef ENABLE_FOLD_CHECKING
12189 #endif
12191 }
12193 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12194 arguments in ARGARRAY, and a null static chain.
12195 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12196 of type TYPE from the given operands as constructed by build_call_array. */
12198 tree
12201 {
12202 tree tem;
12203 #ifdef ENABLE_FOLD_CHECKING
12222 #endif
12228 #ifdef ENABLE_FOLD_CHECKING
12244 #endif
12246 }
12248 /* Perform constant folding and related simplification of initializer
12249 expression EXPR. These behave identically to "fold_buildN" but ignore
12250 potential run-time traps and exceptions that fold must preserve. */
12252 #define START_FOLD_INIT \
12253 int saved_signaling_nans = flag_signaling_nans;\
12254 int saved_trapping_math = flag_trapping_math;\
12255 int saved_rounding_math = flag_rounding_math;\
12256 int saved_trapv = flag_trapv;\
12257 int saved_folding_initializer = folding_initializer;\
12258 flag_signaling_nans = 0;\
12259 flag_trapping_math = 0;\
12260 flag_rounding_math = 0;\
12261 flag_trapv = 0;\
12262 folding_initializer = 1;
12264 #define END_FOLD_INIT \
12265 flag_signaling_nans = saved_signaling_nans;\
12266 flag_trapping_math = saved_trapping_math;\
12267 flag_rounding_math = saved_rounding_math;\
12268 flag_trapv = saved_trapv;\
12269 folding_initializer = saved_folding_initializer;
12271 tree
12274 {
12275 tree result;
12276 START_FOLD_INIT;
12280 END_FOLD_INIT;
12282 }
12284 tree
12287 {
12288 tree result;
12289 START_FOLD_INIT;
12293 END_FOLD_INIT;
12295 }
12297 tree
12300 {
12301 tree result;
12302 START_FOLD_INIT;
12306 END_FOLD_INIT;
12308 }
12310 #undef START_FOLD_INIT
12311 #undef END_FOLD_INIT
12313 /* Determine if first argument is a multiple of second argument. Return 0 if
12314 it is not, or we cannot easily determined it to be.
12316 An example of the sort of thing we care about (at this point; this routine
12317 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12318 fold cases do now) is discovering that
12320 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12322 is a multiple of
12324 SAVE_EXPR (J * 8)
12326 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12328 This code also handles discovering that
12330 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12332 is a multiple of 8 so we don't have to worry about dealing with a
12333 possible remainder.
12335 Note that we *look* inside a SAVE_EXPR only to determine how it was
12336 calculated; it is not safe for fold to do much of anything else with the
12337 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12338 at run time. For example, the latter example above *cannot* be implemented
12339 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12340 evaluation time of the original SAVE_EXPR is not necessarily the same at
12341 the time the new expression is evaluated. The only optimization of this
12342 sort that would be valid is changing
12344 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12346 divided by 8 to
12348 SAVE_EXPR (I) * SAVE_EXPR (J)
12350 (where the same SAVE_EXPR (J) is used in the original and the
12351 transformed version). */
12353 int
12355 {
12366 {
12368 /* Bitwise and provides a power of two multiple. If the mask is
12369 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12372 /* FALLTHRU */
12379 /* It is impossible to prove if op0 - op1 is multiple of bottom
12380 precisely, so be conservative here checking if both op0 and op1
12381 are multiple of bottom. Note we check the second operand first
12382 since it's usually simpler. */
12387 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12388 as op0 - 3 if the expression has unsigned type. For example,
12389 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12399 {
12401 /* const_binop may not detect overflow correctly,
12402 so check for it explicitly here. */
12407 size_one_node,
12408 op1)))
12411 }
12415 /* Can't handle conversions from non-integral or wider integral type. */
12421 /* fall through */
12438 SIGNED);
12444 {
12447 /* Check for special cases to see if top is defined as multiple
12448 of bottom:
12450 top = (X & ~(bottom - 1) ; bottom is power of 2
12452 or
12454 Y = X % bottom
12455 top = X - Y. */
12474 }
12476 /* fall through */
12480 }
12481 }
12483 #define tree_expr_nonnegative_warnv_p(X, Y) \
12486 #define RECURSE(X) \
12487 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12489 /* Return true if CODE or TYPE is known to be non-negative. */
12491 static bool
12493 {
12496 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12497 have a signed:1 type (where the value is -1 and 0). */
12500 }
12502 /* Return true if (CODE OP0) is known to be non-negative. If the return
12503 value is based on the assumption that signed overflow is undefined,
12504 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12505 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12507 bool
12510 {
12515 {
12517 /* We can't return 1 if flag_wrapv is set because
12518 ABS_EXPR<INT_MIN> = INT_MIN. */
12522 {
12525 }
12533 CASE_CONVERT:
12534 {
12539 {
12543 {
12547 }
12548 }
12550 {
12556 }
12557 }
12562 }
12564 /* We don't know sign of `t', so be conservative and return false. */
12566 }
12568 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12569 value is based on the assumption that signed overflow is undefined,
12570 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12571 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12573 bool
12577 {
12582 {
12588 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12589 both unsigned and at least 2 bits shorter than the result. */
12593 {
12598 {
12602 }
12603 }
12608 {
12609 /* x * x is always non-negative for floating point x
12610 or without overflow. */
12613 {
12618 }
12619 }
12621 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12622 both unsigned and their total bits is shorter than the result. */
12626 {
12645 {
12655 }
12656 }
12683 }
12685 /* We don't know sign of `t', so be conservative and return false. */
12687 }
12689 /* Return true if T is known to be non-negative. If the return
12690 value is based on the assumption that signed overflow is undefined,
12691 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12692 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12694 bool
12696 {
12701 {
12715 /* Limit the depth of recursion to avoid quadratic behavior.
12716 This is expected to catch almost all occurrences in practice.
12717 If this code misses important cases that unbounded recursion
12718 would not, passes that need this information could be revised
12719 to provide it through dataflow propagation. */
12727 }
12728 }
12730 /* Return true if T is known to be non-negative. If the return
12731 value is based on the assumption that signed overflow is undefined,
12732 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12733 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12735 bool
12738 {
12740 {
12741 CASE_CFN_ACOS:
12742 CASE_CFN_ACOSH:
12743 CASE_CFN_CABS:
12744 CASE_CFN_COSH:
12745 CASE_CFN_ERFC:
12746 CASE_CFN_EXP:
12747 CASE_CFN_EXP10:
12748 CASE_CFN_EXP2:
12749 CASE_CFN_FABS:
12750 CASE_CFN_FDIM:
12751 CASE_CFN_HYPOT:
12752 CASE_CFN_POW10:
12753 CASE_CFN_FFS:
12754 CASE_CFN_PARITY:
12755 CASE_CFN_POPCOUNT:
12756 CASE_CFN_CLZ:
12757 CASE_CFN_CLRSB:
12760 /* Always true. */
12763 CASE_CFN_SQRT:
12764 /* sqrt(-0.0) is -0.0. */
12769 CASE_CFN_ASINH:
12770 CASE_CFN_ATAN:
12771 CASE_CFN_ATANH:
12772 CASE_CFN_CBRT:
12773 CASE_CFN_CEIL:
12774 CASE_CFN_ERF:
12775 CASE_CFN_EXPM1:
12776 CASE_CFN_FLOOR:
12777 CASE_CFN_FMOD:
12778 CASE_CFN_FREXP:
12779 CASE_CFN_ICEIL:
12780 CASE_CFN_IFLOOR:
12781 CASE_CFN_IRINT:
12782 CASE_CFN_IROUND:
12783 CASE_CFN_LCEIL:
12784 CASE_CFN_LDEXP:
12785 CASE_CFN_LFLOOR:
12786 CASE_CFN_LLCEIL:
12787 CASE_CFN_LLFLOOR:
12788 CASE_CFN_LLRINT:
12789 CASE_CFN_LLROUND:
12790 CASE_CFN_LRINT:
12791 CASE_CFN_LROUND:
12792 CASE_CFN_MODF:
12793 CASE_CFN_NEARBYINT:
12794 CASE_CFN_RINT:
12795 CASE_CFN_ROUND:
12796 CASE_CFN_SCALB:
12797 CASE_CFN_SCALBLN:
12798 CASE_CFN_SCALBN:
12799 CASE_CFN_SIGNBIT:
12800 CASE_CFN_SIGNIFICAND:
12801 CASE_CFN_SINH:
12802 CASE_CFN_TANH:
12803 CASE_CFN_TRUNC:
12804 /* True if the 1st argument is nonnegative. */
12807 CASE_CFN_FMAX:
12808 /* True if the 1st OR 2nd arguments are nonnegative. */
12811 CASE_CFN_FMIN:
12812 /* True if the 1st AND 2nd arguments are nonnegative. */
12815 CASE_CFN_COPYSIGN:
12816 /* True if the 2nd argument is nonnegative. */
12819 CASE_CFN_POWI:
12820 /* True if the 1st argument is nonnegative or the second
12821 argument is an even integer. */
12827 CASE_CFN_POW:
12828 /* True if the 1st argument is nonnegative or the second
12829 argument is an even integer valued real. */
12831 {
12832 REAL_VALUE_TYPE c;
12833 HOST_WIDE_INT n;
12838 {
12839 REAL_VALUE_TYPE cint;
12843 }
12844 }
12849 }
12851 }
12853 /* Return true if T is known to be non-negative. If the return
12854 value is based on the assumption that signed overflow is undefined,
12855 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12856 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12858 static bool
12860 {
12866 {
12868 {
12872 /* If the initializer is non-void, then it's a normal expression
12873 that will be assigned to the slot. */
12877 /* Otherwise, the initializer sets the slot in some way. One common
12878 way is an assignment statement at the end of the initializer. */
12880 {
12888 else
12890 }
12896 }
12899 {
12905 arg0,
12906 arg1,
12908 }
12921 }
12922 }
12924 #undef RECURSE
12925 #undef tree_expr_nonnegative_warnv_p
12927 /* Return true if T is known to be non-negative. If the return
12928 value is based on the assumption that signed overflow is undefined,
12929 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12930 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12932 bool
12934 {
12941 {
12963 }
12966 {
12992 }
12993 }
12995 /* Return true if `t' is known to be non-negative. Handle warnings
12996 about undefined signed overflow. */
12998 bool
13000 {
13007 "determining that expression is always "
13009 WARN_STRICT_OVERFLOW_MISC);
13011 }
13014 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13015 For floating point we further ensure that T is not denormal.
13016 Similar logic is present in nonzero_address in rtlanal.h.
13018 If the return value is based on the assumption that signed overflow
13019 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13020 change *STRICT_OVERFLOW_P. */
13022 bool
13025 {
13027 {
13030 strict_overflow_p);
13033 {
13039 strict_overflow_p));
13040 }
13045 strict_overflow_p);
13049 }
13052 }
13054 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13055 For floating point we further ensure that T is not denormal.
13056 Similar logic is present in nonzero_address in rtlanal.h.
13058 If the return value is based on the assumption that signed overflow
13059 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13060 change *STRICT_OVERFLOW_P. */
13062 bool
13064 tree type,
13065 tree op0,
13067 {
13070 {
13074 {
13075 /* With the presence of negative values it is hard
13076 to say something. */
13083 /* One of operands must be positive and the other non-negative. */
13084 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13085 overflows, on a twos-complement machine the sum of two
13086 nonnegative numbers can never be zero. */
13088 strict_overflow_p)
13090 strict_overflow_p));
13091 }
13096 {
13098 strict_overflow_p)
13100 strict_overflow_p))
13101 {
13104 }
13105 }
13114 {
13117 }
13124 {
13128 /* When both operands are nonzero, then MAX must be too. */
13130 strict_overflow_p))
13133 /* MAX where operand 0 is positive is positive. */
13135 strict_overflow_p);
13136 }
13137 /* MAX where operand 1 is positive is positive. */
13142 {
13146 }
13151 strict_overflow_p)
13153 strict_overflow_p));
13157 }
13160 }
13162 /* Return true when T is an address and is known to be nonzero.
13163 For floating point we further ensure that T is not denormal.
13164 Similar logic is present in nonzero_address in rtlanal.h.
13166 If the return value is based on the assumption that signed overflow
13167 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13168 change *STRICT_OVERFLOW_P. */
13170 bool
13172 {
13175 {
13180 {
13192 /* For objects in symbol table check if we know they are non-zero.
13193 Don't do anything for variables and functions before symtab is built;
13194 it is quite possible that they will be declared weak later. */
13199 /* Constants are never weak. */
13204 }
13212 {
13216 }
13226 }
13228 }
13230 #define integer_valued_real_p(X) \
13233 #define RECURSE(X) \
13234 ((integer_valued_real_p) (X, depth + 1))
13236 /* Return true if the floating point result of (CODE OP0) has an
13237 integer value. We also allow +Inf, -Inf and NaN to be considered
13238 integer values. Return false for signaling NaN.
13240 DEPTH is the current nesting depth of the query. */
13242 bool
13244 {
13246 {
13253 CASE_CONVERT:
13254 {
13261 }
13265 }
13267 }
13269 /* Return true if the floating point result of (CODE OP0 OP1) has an
13270 integer value. We also allow +Inf, -Inf and NaN to be considered
13271 integer values. Return false for signaling NaN.
13273 DEPTH is the current nesting depth of the query. */
13275 bool
13277 {
13279 {
13289 }
13291 }
13293 /* Return true if the floating point result of calling FNDECL with arguments
13294 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13295 considered integer values. Return false for signaling NaN. If FNDECL
13296 takes fewer than 2 arguments, the remaining ARGn are null.
13298 DEPTH is the current nesting depth of the query. */
13300 bool
13302 {
13304 {
13305 CASE_CFN_CEIL:
13306 CASE_CFN_FLOOR:
13307 CASE_CFN_NEARBYINT:
13308 CASE_CFN_RINT:
13309 CASE_CFN_ROUND:
13310 CASE_CFN_TRUNC:
13313 CASE_CFN_FMIN:
13314 CASE_CFN_FMAX:
13319 }
13321 }
13323 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13324 has an integer value. We also allow +Inf, -Inf and NaN to be
13325 considered integer values. Return false for signaling NaN.
13327 DEPTH is the current nesting depth of the query. */
13329 bool
13331 {
13333 {
13341 /* Limit the depth of recursion to avoid quadratic behavior.
13342 This is expected to catch almost all occurrences in practice.
13343 If this code misses important cases that unbounded recursion
13344 would not, passes that need this information could be revised
13345 to provide it through dataflow propagation. */
13349 depth));
13353 }
13355 }
13357 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13358 has an integer value. We also allow +Inf, -Inf and NaN to be
13359 considered integer values. Return false for signaling NaN.
13361 DEPTH is the current nesting depth of the query. */
13363 static bool
13365 {
13367 {
13378 }
13380 }
13382 #undef RECURSE
13383 #undef integer_valued_real_p
13385 /* Return true if the floating point expression T has an integer value.
13386 We also allow +Inf, -Inf and NaN to be considered integer values.
13387 Return false for signaling NaN.
13389 DEPTH is the current nesting depth of the query. */
13391 bool
13393 {
13399 {
13415 }
13418 {
13424 {
13433 }
13437 }
13438 }
13440 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13441 attempt to fold the expression to a constant without modifying TYPE,
13442 OP0 or OP1.
13444 If the expression could be simplified to a constant, then return
13445 the constant. If the expression would not be simplified to a
13446 constant, then return NULL_TREE. */
13448 tree
13450 {
13453 }
13455 /* Given the components of a unary expression CODE, TYPE and OP0,
13456 attempt to fold the expression to a constant without modifying
13457 TYPE or OP0.
13459 If the expression could be simplified to a constant, then return
13460 the constant. If the expression would not be simplified to a
13461 constant, then return NULL_TREE. */
13463 tree
13465 {
13468 }
13470 /* If EXP represents referencing an element in a constant string
13471 (either via pointer arithmetic or array indexing), return the
13472 tree representing the value accessed, otherwise return NULL. */
13474 tree
13476 {
13480 {
13482 tree index;
13483 tree string;
13488 else
13489 {
13493 /* Optimize the special-case of a zero lower bound.
13495 We convert the low_bound to sizetype to avoid some problems
13496 with constant folding. (E.g. suppose the lower bound is 1,
13497 and its mode is QI. Without the conversion,l (ARRAY
13498 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13499 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13505 }
13507 scalar_int_mode char_mode;
13519 }
13521 }
13523 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13524 an integer constant, real, or fixed-point constant.
13526 TYPE is the type of the result. */
13528 static tree
13530 {
13534 {
13536 {
13543 }
13550 {
13551 FIXED_VALUE_TYPE f;
13556 /* Propagate overflow flags. */
13560 }
13564 }
13567 }
13569 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13570 an integer constant or real constant.
13572 TYPE is the type of the result. */
13574 tree
13576 {
13580 {
13582 {
13583 /* If the value is unsigned or non-negative, then the absolute value
13584 is the same as the ordinary value. */
13588 /* If the value is negative, then the absolute value is
13589 its negation. */
13590 else
13591 {
13596 }
13597 }
13603 else
13609 }
13612 }
13614 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13615 constant. TYPE is the type of the result. */
13617 static tree
13619 {
13623 }
13625 /* Given CODE, a relational operator, the target type, TYPE and two
13626 constant operands OP0 and OP1, return the result of the
13627 relational operation. If the result is not a compile time
13628 constant, then return NULL_TREE. */
13630 static tree
13632 {
13635 /* From here on, the only cases we handle are when the result is
13636 known to be a constant. */
13639 {
13643 /* Handle the cases where either operand is a NaN. */
13645 {
13647 {
13675 }
13678 }
13681 }
13684 {
13688 }
13690 /* Handle equality/inequality of complex constants. */
13692 {
13703 else
13705 }
13708 {
13710 {
13711 /* Have vector comparison with scalar boolean result. */
13715 {
13723 }
13725 }
13732 {
13745 }
13748 }
13750 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13752 To compute GT, swap the arguments and do LT.
13753 To compute GE, do LT and invert the result.
13754 To compute LE, swap the arguments, do LT and invert the result.
13755 To compute NE, do EQ and invert the result.
13757 Therefore, the code below must handle only EQ and LT. */
13760 {
13763 }
13765 /* Note that it is safe to invert for real values here because we
13766 have already handled the one case that it matters. */
13770 {
13773 }
13775 /* Compute a result for LT or EQ if args permit;
13776 Otherwise return T. */
13778 {
13781 else
13783 }
13784 else
13790 }
13792 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13793 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13794 itself. */
13796 tree
13798 {
13799 /* If the expression does not have side effects then we don't have to wrap
13800 it with a cleanup point expression. */
13804 /* If the expression is a return, check to see if the expression inside the
13805 return has no side effects or the right hand side of the modify expression
13806 inside the return. If either don't have side effects set we don't need to
13807 wrap the expression in a cleanup point expression. Note we don't check the
13808 left hand side of the modify because it should always be a return decl. */
13810 {
13817 }
13820 }
13822 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13823 of an indirection through OP0, or NULL_TREE if no simplification is
13824 possible. */
13826 tree
13828 {
13830 tree subtype;
13839 {
13842 /* *&CONST_DECL -> to the value of the const decl. */
13845 /* *&p => p; make sure to handle *&"str"[cst] here. */
13847 {
13851 else
13853 }
13854 /* *(foo *)&fooarray => fooarray[0] */
13857 && (!in_gimple_form
13859 {
13869 }
13870 /* *(foo *)&complexfoo => __real__ complexfoo */
13874 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
13877 {
13881 }
13882 }
13886 {
13892 {
13893 tree op00type;
13897 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
13900 {
13902 unsigned HOST_WIDE_INT max_offset
13907 {
13914 }
13915 }
13916 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13919 {
13923 }
13924 /* ((foo *)&fooarray)[1] => fooarray[1] */
13927 {
13934 offset_int remainder;
13937 {
13942 }
13943 }
13944 }
13945 }
13947 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
13950 && (!in_gimple_form
13952 {
13953 tree type_domain;
13963 NULL_TREE);
13964 }
13967 }
13969 /* Builds an expression for an indirection through T, simplifying some
13970 cases. */
13972 tree
13974 {
13982 }
13984 /* Given an INDIRECT_REF T, return either T or a simplified version. */
13986 tree
13988 {
13993 else
13995 }
13997 /* Strip non-trapping, non-side-effecting tree nodes from an expression
13998 whose result is ignored. The type of the returned tree need not be
13999 the same as the original expression. */
14001 tree
14003 {
14009 {
14020 else
14026 {
14042 }
14047 }
14048 }
14050 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14052 tree
14054 {
14060 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14061 have to do anything. Only do this when we are not given a const,
14062 because in that case, this check is more expensive than just
14063 doing it. */
14065 {
14070 }
14072 /* If divisor is a power of two, simplify this to bit manipulation. */
14074 {
14076 {
14090 }
14091 else
14092 {
14093 tree t;
14099 }
14100 }
14101 else
14102 {
14107 }
14110 }
14112 /* Likewise, but round down. */
14114 tree
14116 {
14123 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14124 have to do anything. Only do this when we are not given a const,
14125 because in that case, this check is more expensive than just
14126 doing it. */
14128 {
14133 }
14135 /* If divisor is a power of two, simplify this to bit manipulation. */
14137 {
14138 tree t;
14142 }
14143 else
14144 {
14149 }
14152 }
14154 /* Returns the pointer to the base of the object addressed by EXP and
14155 extracts the information about the offset of the access, storing it
14156 to PBITPOS and POFFSET. */
14158 static tree
14161 {
14162 tree core;
14163 machine_mode mode;
14165 HOST_WIDE_INT bitsize;
14169 {
14174 }
14176 {
14182 {
14187 {
14190 }
14191 }
14192 }
14193 else
14194 {
14198 }
14201 }
14203 /* Returns true if addresses of E1 and E2 differ by a constant, false
14204 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14206 bool
14208 {
14222 {
14232 }
14234 {
14235 /* If only one of the offsets is non-constant, the difference cannot
14236 be a constant. */
14238 }
14239 else
14244 }
14246 /* Return OFF converted to a pointer offset type suitable as offset for
14247 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14248 tree
14250 {
14252 }
14254 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14255 tree
14257 {
14260 }
14262 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14263 tree
14265 {
14268 }
14270 /* Return a char pointer for a C string if it is a string constant
14271 or sum of string constant and integer constant. We only support
14272 string constants properly terminated with '\0' character.
14273 If STRLEN is a valid pointer, length (including terminating character)
14274 of returned string is stored to the argument. */
14278 {
14279 tree offset_node;
14290 {
14293 else
14295 }
14300 /* Support only properly null-terminated strings. */
14309 }
14311 #if CHECKING_P
14315 /* Helper functions for writing tests of folding trees. */
14317 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14319 static void
14321 tree constant)
14322 {
14324 }
14326 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14327 wrapping WRAPPED_EXPR. */
14329 static void
14331 tree wrapped_expr)
14332 {
14337 }
14339 /* Verify that various arithmetic binary operations are folded
14340 correctly. */
14342 static void
14344 {
14350 /* Addition. */
14351 /* 1 <-- (0 + 1) */
14353 one);
14355 one);
14357 /* (nonlvalue)x <-- (x + 0) */
14359 x);
14361 /* Subtraction. */
14362 /* 0 <-- (x - x) */
14364 zero);
14366 x);
14368 /* Multiplication. */
14369 /* 0 <-- (x * 0) */
14371 zero);
14373 /* (nonlvalue)x <-- (x * 1) */
14375 x);
14376 }
14378 /* Verify that various binary operations on vectors are folded
14379 correctly. */
14381 static void
14383 {
14389 /* Verify equality tests that return a scalar boolean result. */
14395 }
14397 /* Run all of the selftests within this file. */
14399 void
14401 {
14404 }