| blob | 0f110765f44ba42754ddca3dbdcaf36f0809182d |
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. */
86 /* Nonzero if we are folding constants inside an initializer; zero
87 otherwise. */
90 /* The following constants represent a bit based encoding of GCC's
91 comparison operators. This encoding simplifies transformations
92 on relational comparison operators, such as AND and OR. */
110 };
143 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
144 Otherwise, return LOC. */
146 static location_t
148 {
151 }
153 /* Similar to protected_set_expr_location, but never modify x in place,
154 if location can and needs to be set, unshare it. */
158 {
164 {
167 }
169 }
170 \f
171 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
172 division and returns the quotient. Otherwise returns
173 NULL_TREE. */
175 tree
177 {
178 widest_int quo;
185 }
186 \f
187 /* This is nonzero if we should defer warnings about undefined
188 overflow. This facility exists because these warnings are a
189 special case. The code to estimate loop iterations does not want
190 to issue any warnings, since it works with expressions which do not
191 occur in user code. Various bits of cleanup code call fold(), but
192 only use the result if it has certain characteristics (e.g., is a
193 constant); that code only wants to issue a warning if the result is
194 used. */
198 /* If a warning about undefined overflow is deferred, this is the
199 warning. Note that this may cause us to turn two warnings into
200 one, but that is fine since it is sufficient to only give one
201 warning per expression. */
205 /* If a warning about undefined overflow is deferred, this is the
206 level at which the warning should be emitted. */
210 /* Start deferring overflow warnings. We could use a stack here to
211 permit nested calls, but at present it is not necessary. */
213 void
215 {
217 }
219 /* Stop deferring overflow warnings. If there is a pending warning,
220 and ISSUE is true, then issue the warning if appropriate. STMT is
221 the statement with which the warning should be associated (used for
222 location information); STMT may be NULL. CODE is the level of the
223 warning--a warn_strict_overflow_code value. This function will use
224 the smaller of CODE and the deferred code when deciding whether to
225 issue the warning. CODE may be zero to mean to always use the
226 deferred code. */
228 void
230 {
232 location_t locus;
237 {
243 }
254 /* Use the smallest code level when deciding to issue the
255 warning. */
264 else
267 }
269 /* Stop deferring overflow warnings, ignoring any deferred
270 warnings. */
272 void
274 {
276 }
278 /* Whether we are deferring overflow warnings. */
280 bool
282 {
284 }
286 /* This is called when we fold something based on the fact that signed
287 overflow is undefined. */
289 void
291 {
293 {
296 {
299 }
300 }
303 }
304 \f
305 /* Return true if the built-in mathematical function specified by CODE
306 is odd, i.e. -f(x) == f(-x). */
308 bool
310 {
312 {
313 CASE_CFN_ASIN:
314 CASE_CFN_ASINH:
315 CASE_CFN_ATAN:
316 CASE_CFN_ATANH:
317 CASE_CFN_CASIN:
318 CASE_CFN_CASINH:
319 CASE_CFN_CATAN:
320 CASE_CFN_CATANH:
321 CASE_CFN_CBRT:
322 CASE_CFN_CPROJ:
323 CASE_CFN_CSIN:
324 CASE_CFN_CSINH:
325 CASE_CFN_CTAN:
326 CASE_CFN_CTANH:
327 CASE_CFN_ERF:
328 CASE_CFN_LLROUND:
329 CASE_CFN_LROUND:
330 CASE_CFN_ROUND:
331 CASE_CFN_SIN:
332 CASE_CFN_SINH:
333 CASE_CFN_TAN:
334 CASE_CFN_TANH:
335 CASE_CFN_TRUNC:
338 CASE_CFN_LLRINT:
339 CASE_CFN_LRINT:
340 CASE_CFN_NEARBYINT:
341 CASE_CFN_RINT:
346 }
348 }
350 /* Check whether we may negate an integer constant T without causing
351 overflow. */
353 bool
355 {
356 tree type;
365 }
367 /* Determine whether an expression T can be cheaply negated using
368 the function negate_expr without introducing undefined overflow. */
370 static bool
372 {
373 tree type;
382 {
387 /* Check that -CST will not overflow type. */
400 /* We want to canonicalize to positive real constants. Pretend
401 that only negative ones can be easily negated. */
409 {
413 /* Steps don't prevent negation. */
420 }
435 /* -(A + B) -> (-B) - A. */
438 /* -(A + B) -> (-A) - B. */
442 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
451 /* INT_MIN/n * n doesn't overflow while negating one operand it does
452 if n is a (negative) power of two. */
463 /* Fall through. */
478 /* In general we can't negate B in A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. */
489 /* Negate -((double)float) as (double)(-float). */
491 {
495 }
499 /* Negate -f(x) as f(-x). */
505 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
507 {
511 }
516 }
518 }
520 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
521 simplification is possible.
522 If negate_expr_p would return true for T, NULL_TREE will never be
523 returned. */
525 static tree
527 {
529 tree tem;
532 {
533 /* Convert - (~A) to A + 1. */
559 {
564 }
568 {
569 tree_vector_builder elts;
573 {
578 }
581 }
604 {
605 /* -(A + B) -> (-B) - A. */
607 {
611 }
613 /* -(A + B) -> (-A) - B. */
615 {
619 }
620 }
624 /* - (A - B) -> B - A */
635 /* Fall through. */
639 {
648 }
660 /* In general we can't negate B in A / B, because if A is INT_MIN and
661 B is 1, we may turn this into INT_MIN / -1 which is undefined
662 and actually traps on some architectures. */
674 /* Convert -((double)float) into (double)(-float). */
676 {
680 }
684 /* Negate -f(x) as f(-x). */
687 {
693 }
697 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
699 {
702 {
709 }
710 }
715 }
718 }
720 /* A wrapper for fold_negate_expr_1. */
722 static tree
724 {
731 }
733 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
734 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
735 return NULL_TREE. */
737 static tree
739 {
741 location_t loc;
754 }
755 \f
756 /* Split a tree IN into a constant, literal and variable parts that could be
757 combined with CODE to make IN. "constant" means an expression with
758 TREE_CONSTANT but that isn't an actual constant. CODE must be a
759 commutative arithmetic operation. Store the constant part into *CONP,
760 the literal in *LITP and return the variable part. If a part isn't
761 present, set it to null. If the tree does not decompose in this way,
762 return the entire tree as the variable part and the other parts as null.
764 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
765 case, we negate an operand that was subtracted. Except if it is a
766 literal for which we use *MINUS_LITP instead.
768 If NEGATE_P is true, we are negating all of IN, again except a literal
769 for which we use *MINUS_LITP instead. If a variable part is of pointer
770 type, it is negated after converting to TYPE. This prevents us from
771 generating illegal MINUS pointer expression. LOC is the location of
772 the converted variable part.
774 If IN is itself a literal or constant, return it as appropriate.
776 Note that we do not guarantee that any of the three values will be the
777 same type as IN, but they will have the same signedness and mode. */
779 static tree
783 {
791 /* Strip any conversions that don't change the machine mode or signedness. */
800 /* We can associate addition and subtraction together (even
801 though the C standard doesn't say so) for integers because
802 the value is not affected. For reals, the value might be
803 affected, so we can't. */
809 {
815 /* First see if either of the operands is a literal, then a constant. */
828 /* If we haven't dealt with either operand, this is not a case we can
829 decompose. Otherwise, VAR is either of the ones remaining, if any. */
834 else
837 /* Now do any needed negations. */
844 }
849 {
850 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
851 when IN is constant. */
854 }
855 else
859 {
872 }
882 }
884 /* Re-associate trees split by the above function. T1 and T2 are
885 either expressions to associate or null. Return the new
886 expression, if any. LOC is the location of the new expression. If
887 we build an operation, do it in TYPE and with CODE. */
889 static tree
891 {
893 {
896 }
900 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
901 try to fold this since we will have infinite recursion. But do
902 deal with any NEGATE_EXPRs. */
906 {
908 {
921 }
923 {
926 }
930 }
934 }
935 \f
936 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
937 for use in int_const_binop, size_binop and size_diffop. */
939 static bool
941 {
948 {
957 }
962 }
965 /* Combine two integer constants PARG1 and PARG2 under operation CODE
966 to produce a new constant. Return NULL_TREE if we don't know how
967 to evaluate CODE at compile-time. */
969 static tree
972 {
973 wide_int res;
974 tree t;
983 {
999 {
1003 else
1005 }
1008 /* It's unclear from the C standard whether shifts can overflow.
1009 The following code ignores overflow; perhaps a C standard
1010 interpretation ruling is needed. */
1012 else
1019 {
1023 else
1025 }
1029 else
1108 }
1116 }
1118 tree
1120 {
1122 }
1124 /* Return true if binary operation OP distributes over addition in operand
1125 OPNO, with the other operand being held constant. OPNO counts from 1. */
1127 static bool
1129 {
1131 {
1142 }
1143 }
1145 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1146 constant. We assume ARG1 and ARG2 have the same data type, or at least
1147 are the same kind of constant and the same machine mode. Return zero if
1148 combining the constants is not allowed in the current operating mode. */
1150 static tree
1152 {
1153 /* Sanity check for the recursive cases. */
1161 {
1167 }
1170 {
1171 machine_mode mode;
1172 REAL_VALUE_TYPE d1;
1173 REAL_VALUE_TYPE d2;
1174 REAL_VALUE_TYPE value;
1175 REAL_VALUE_TYPE result;
1179 /* The following codes are handled by real_arithmetic. */
1181 {
1192 }
1200 /* Don't perform operation if we honor signaling NaNs and
1201 either operand is a signaling NaN. */
1207 /* Don't perform operation if it would raise a division
1208 by zero exception. */
1214 /* If either operand is a NaN, just return it. Otherwise, set up
1215 for floating-point trap; we return an overflow. */
1217 {
1218 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1219 is off. */
1223 }
1225 {
1226 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1227 is off. */
1231 }
1236 /* Don't constant fold this floating point operation if
1237 the result has overflowed and flag_trapping_math. */
1245 /* Don't constant fold this floating point operation if the
1246 result may dependent upon the run-time rounding mode and
1247 flag_rounding_math is set, or if GCC's software emulation
1248 is unable to accurately represent the result. */
1258 }
1261 {
1262 FIXED_VALUE_TYPE f1;
1263 FIXED_VALUE_TYPE f2;
1264 FIXED_VALUE_TYPE result;
1269 /* The following codes are handled by fixed_arithmetic. */
1271 {
1283 {
1290 }
1295 }
1302 /* Propagate overflow flags. */
1306 }
1309 {
1318 {
1329 mpc_mul);
1343 mpc_div);
1344 /* Fallthru. */
1350 {
1351 /* Keep this algorithm in sync with
1352 tree-complex.c:expand_complex_div_straight().
1354 Expand complex division to scalars, straightforward algorithm.
1355 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1356 t = br*br + bi*bi
1357 */
1358 tree magsquared
1362 tree t1
1366 tree t2
1373 }
1374 else
1375 {
1376 /* Keep this algorithm in sync with
1377 tree-complex.c:expand_complex_div_wide().
1379 Expand complex division to scalars, modified algorithm to minimize
1380 overflow with wide input ranges. */
1386 {
1387 /* In the TRUE branch, we compute
1388 ratio = br/bi;
1389 div = (br * ratio) + bi;
1390 tr = (ar * ratio) + ai;
1391 ti = (ai * ratio) - ar;
1392 tr = tr / div;
1393 ti = ti / div; */
1404 }
1405 else
1406 {
1407 /* In the FALSE branch, we compute
1408 ratio = d/c;
1409 divisor = (d * ratio) + c;
1410 tr = (b * ratio) + a;
1411 ti = b - (a * ratio);
1412 tr = tr / div;
1413 ti = ti / div; */
1425 }
1426 }
1431 }
1435 }
1441 {
1446 /* We can operate directly on the encoding if:
1448 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1449 implies
1450 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1452 Addition and subtraction are the supported operators
1453 for which this is true. */
1456 /* We can operate directly on stepped encodings if:
1458 a3 - a2 == a2 - a1
1459 implies:
1460 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1462 which is true if (x -> x op c) distributes over addition. */
1464 else
1465 /* Similarly in reverse. */
1467 tree_vector_builder elts;
1472 {
1478 /* It is possible that const_binop cannot handle the given
1479 code and return NULL_TREE */
1483 }
1486 }
1488 /* Shifts allow a scalar offset for a vector. */
1491 {
1494 tree_vector_builder elts;
1499 {
1504 /* It is possible that const_binop cannot handle the given
1505 code and return NULL_TREE. */
1509 }
1512 }
1514 }
1516 /* Overload that adds a TYPE parameter to be able to dispatch
1517 to fold_relational_const. */
1519 tree
1521 {
1525 /* ??? Until we make the const_binop worker take the type of the
1526 result as argument put those cases that need it here. */
1528 {
1539 {
1544 }
1549 {
1563 {
1573 }
1576 }
1582 {
1604 {
1617 }
1620 }
1623 }
1628 /* Make sure type and arg0 have the same saturating flag. */
1633 }
1635 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1636 Return zero if computing the constants is not possible. */
1638 tree
1640 {
1641 /* Don't perform the operation, other than NEGATE and ABS, if
1642 flag_signaling_nans is on and the operand is a signaling NaN. */
1651 {
1652 CASE_CONVERT:
1659 /* If the source address is 0, and the source address space
1660 cannot have a valid object at 0, fold to dest type null. */
1671 {
1672 /* Can't call fold_negate_const directly here as that doesn't
1673 handle all cases and we might not be able to negate some
1674 constants. */
1679 }
1688 {
1692 }
1698 /* Perform BIT_NOT_EXPR on each element individually. */
1700 {
1701 tree elem;
1703 /* This can cope with stepped encodings because ~x == -1 - x. */
1704 tree_vector_builder elements;
1708 {
1714 }
1717 }
1739 {
1757 else
1762 {
1768 }
1771 }
1775 }
1778 }
1780 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1781 indicates which particular sizetype to create. */
1783 tree
1785 {
1787 }
1788 \f
1789 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1790 is a tree code. The type of the result is taken from the operands.
1791 Both must be equivalent integer types, ala int_binop_types_match_p.
1792 If the operands are constant, so is the result. */
1794 tree
1796 {
1805 /* Handle the special case of two integer constants faster. */
1807 {
1808 /* And some specific cases even faster than that. */
1810 {
1815 }
1817 {
1820 }
1822 {
1825 }
1827 /* Handle general case of two integer constants. For sizetype
1828 constant calculations we always want to know about overflow,
1829 even in the unsigned case. */
1831 }
1834 }
1836 /* Given two values, either both of sizetype or both of bitsizetype,
1837 compute the difference between the two values. Return the value
1838 in signed type corresponding to the type of the operands. */
1840 tree
1842 {
1844 tree ctype;
1849 /* If the type is already signed, just do the simple thing. */
1857 else
1860 /* If either operand is not a constant, do the conversions to the signed
1861 type and subtract. The hardware will do the right thing with any
1862 overflow in the subtraction. */
1868 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1869 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1870 overflow) and negate (which can't either). Special-case a result
1871 of zero while we're here. */
1877 else
1881 MINUS_EXPR,
1883 }
1884 \f
1885 /* A subroutine of fold_convert_const handling conversions of an
1886 INTEGER_CST to another integer type. */
1888 static tree
1890 {
1891 /* Given an integer constant, make new constant with new type,
1892 appropriately sign-extended or truncated. Use widest_int
1893 so that any extension is done according ARG1's type. */
1897 }
1899 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1900 to an integer type. */
1902 static tree
1904 {
1906 tree t;
1908 /* The following code implements the floating point to integer
1909 conversion rules required by the Java Language Specification,
1910 that IEEE NaNs are mapped to zero and values that overflow
1911 the target precision saturate, i.e. values greater than
1912 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1913 are mapped to INT_MIN. These semantics are allowed by the
1914 C and C++ standards that simply state that the behavior of
1915 FP-to-integer conversion is unspecified upon overflow. */
1917 wide_int val;
1918 REAL_VALUE_TYPE r;
1922 {
1929 }
1931 /* If R is NaN, return zero and show we have an overflow. */
1933 {
1936 }
1938 /* See if R is less than the lower bound or greater than the
1939 upper bound. */
1942 {
1946 {
1949 }
1950 }
1953 {
1956 {
1959 {
1962 }
1963 }
1964 }
1971 }
1973 /* A subroutine of fold_convert_const handling conversions of a
1974 FIXED_CST to an integer type. */
1976 static tree
1978 {
1979 tree t;
1981 scalar_mode mode;
1983 /* Right shift FIXED_CST to temp by fbit. */
1987 {
1989 HOST_BITS_PER_DOUBLE_INT,
1992 /* Left shift temp to temp_trunc by fbit. */
1994 HOST_BITS_PER_DOUBLE_INT,
1996 }
1997 else
1998 {
2001 }
2003 /* If FIXED_CST is negative, we need to round the value toward 0.
2004 By checking if the fractional bits are not zero to add 1 to temp. */
2010 /* Given a fixed-point constant, make new constant with new type,
2011 appropriately sign-extended or truncated. */
2019 }
2021 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2022 to another floating point type. */
2024 static tree
2026 {
2027 REAL_VALUE_TYPE value;
2028 tree t;
2030 /* Don't perform the operation if flag_signaling_nans is on
2031 and the operand is a signaling NaN. */
2039 /* If converting an infinity or NAN to a representation that doesn't
2040 have one, set the overflow bit so that we can produce some kind of
2041 error message at the appropriate point if necessary. It's not the
2042 most user-friendly message, but it's better than nothing. */
2049 /* Regular overflow, conversion produced an infinity in a mode that
2050 can't represent them. */
2055 else
2058 }
2060 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2061 to a floating point type. */
2063 static tree
2065 {
2066 REAL_VALUE_TYPE value;
2067 tree t;
2075 }
2077 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2078 to another fixed-point type. */
2080 static tree
2082 {
2083 FIXED_VALUE_TYPE value;
2084 tree t;
2091 /* Propagate overflow flags. */
2095 }
2097 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2098 to a fixed-point type. */
2100 static tree
2102 {
2103 FIXED_VALUE_TYPE value;
2104 tree t;
2106 double_int di;
2113 else
2121 /* Propagate overflow flags. */
2125 }
2127 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2128 to a fixed-point type. */
2130 static tree
2132 {
2133 FIXED_VALUE_TYPE value;
2134 tree t;
2142 /* Propagate overflow flags. */
2146 }
2148 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2149 type TYPE. If no simplification can be done return NULL_TREE. */
2151 static tree
2153 {
2159 {
2166 }
2168 {
2175 }
2177 {
2184 }
2186 {
2189 {
2192 /* We can't handle steps directly when extending, since the
2193 values need to wrap at the original precision first. */
2194 bool step_ok_p
2198 tree_vector_builder v;
2203 {
2209 }
2211 }
2212 }
2214 }
2216 /* Construct a vector of zero elements of vector type TYPE. */
2218 static tree
2220 {
2221 tree t;
2225 }
2227 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2229 bool
2231 {
2246 {
2261 }
2262 }
2264 /* Convert expression ARG to type TYPE. Used by the middle-end for
2265 simple conversions in preference to calling the front-end's convert. */
2267 tree
2269 {
2271 tree tem;
2282 {
2285 /* Handle conversions between pointers to different address spaces. */
2290 /* fall through */
2295 {
2299 }
2313 {
2317 }
2319 {
2323 }
2325 {
2329 }
2332 {
2350 }
2355 {
2359 }
2362 {
2376 }
2380 {
2389 integer_zero_node));
2391 {
2395 {
2401 }
2409 }
2413 }
2431 }
2432 fold_convert_exit:
2435 }
2436 \f
2437 /* Return false if expr can be assumed not to be an lvalue, true
2438 otherwise. */
2440 static bool
2442 {
2443 /* We only need to wrap lvalue tree codes. */
2445 {
2476 /* Assume the worst for front-end tree codes. */
2480 }
2483 }
2485 /* Return an expr equal to X but certainly not valid as an lvalue. */
2487 tree
2489 {
2490 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2491 us. */
2498 }
2500 /* When pedantic, return an expr equal to X but certainly not valid as a
2501 pedantic lvalue. Otherwise, return X. */
2503 static tree
2505 {
2507 }
2508 \f
2509 /* Given a tree comparison code, return the code that is the logical inverse.
2510 It is generally not safe to do this for floating-point comparisons, except
2511 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2512 ERROR_MARK in this case. */
2514 enum tree_code
2516 {
2522 {
2553 }
2554 }
2556 /* Similar, but return the comparison that results if the operands are
2557 swapped. This is safe for floating-point. */
2559 enum tree_code
2561 {
2563 {
2589 }
2590 }
2593 /* Convert a comparison tree code from an enum tree_code representation
2594 into a compcode bit-based encoding. This function is the inverse of
2595 compcode_to_comparison. */
2597 static enum comparison_code
2599 {
2601 {
2632 }
2633 }
2635 /* Convert a compcode bit-based encoding of a comparison operator back
2636 to GCC's enum tree_code representation. This function is the
2637 inverse of comparison_to_compcode. */
2639 static enum tree_code
2641 {
2643 {
2674 }
2675 }
2677 /* Return a tree for the comparison which is the combination of
2678 doing the AND or OR (depending on CODE) of the two operations LCODE
2679 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2680 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2681 if this makes the transformation invalid. */
2683 tree
2688 {
2695 {
2706 }
2709 {
2710 /* Eliminate unordered comparisons, as well as LTGT and ORD
2711 which are not used unless the mode has NaNs. */
2717 }
2719 {
2720 /* Check that the original operation and the optimized ones will trap
2721 under the same condition. */
2732 /* In a short-circuited boolean expression the LHS might be
2733 such that the RHS, if evaluated, will never trap. For
2734 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2735 if neither x nor y is NaN. (This is a mixed blessing: for
2736 example, the expression above will never trap, hence
2737 optimizing it to x < y would be invalid). */
2742 /* If the comparison was short-circuited, and only the RHS
2743 trapped, we may now generate a spurious trap. */
2748 /* If we changed the conditions that cause a trap, we lose. */
2751 }
2757 else
2758 {
2763 }
2764 }
2765 \f
2766 /* Return nonzero if two operands (typically of the same tree node)
2767 are necessarily equal. FLAGS modifies behavior as follows:
2769 If OEP_ONLY_CONST is set, only return nonzero for constants.
2770 This function tests whether the operands are indistinguishable;
2771 it does not test whether they are equal using C's == operation.
2772 The distinction is important for IEEE floating point, because
2773 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2774 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2776 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2777 even though it may hold multiple values during a function.
2778 This is because a GCC tree node guarantees that nothing else is
2779 executed between the evaluation of its "operands" (which may often
2780 be evaluated in arbitrary order). Hence if the operands themselves
2781 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2782 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2783 unset means assuming isochronic (or instantaneous) tree equivalence.
2784 Unless comparing arbitrary expression trees, such as from different
2785 statements, this flag can usually be left unset.
2787 If OEP_PURE_SAME is set, then pure functions with identical arguments
2788 are considered the same. It is used when the caller has other ways
2789 to ensure that global memory is unchanged in between.
2791 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2792 not values of expressions.
2794 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2795 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2797 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2798 any operand with side effect. This is unnecesarily conservative in the
2799 case we know that arg0 and arg1 are in disjoint code paths (such as in
2800 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2801 addresses with TREE_CONSTANT flag set so we know that &var == &var
2802 even if var is volatile. */
2804 int
2806 {
2807 /* When checking, verify at the outermost operand_equal_p call that
2808 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2809 hash value. */
2811 {
2813 {
2815 {
2822 }
2824 }
2825 else
2827 }
2829 /* If either is ERROR_MARK, they aren't equal. */
2835 /* Similar, if either does not have a type (like a released SSA name),
2836 they aren't equal. */
2840 /* We cannot consider pointers to different address space equal. */
2847 /* Check equality of integer constants before bailing out due to
2848 precision differences. */
2850 {
2851 /* Address of INTEGER_CST is not defined; check that we did not forget
2852 to drop the OEP_ADDRESS_OF flags. */
2855 }
2858 {
2859 /* If both types don't have the same signedness, then we can't consider
2860 them equal. We must check this before the STRIP_NOPS calls
2861 because they may change the signedness of the arguments. As pointers
2862 strictly don't have a signedness, require either two pointers or
2863 two non-pointers as well. */
2869 /* If both types don't have the same precision, then it is not safe
2870 to strip NOPs. */
2877 }
2878 #if 0
2879 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2880 sanity check once the issue is solved. */
2881 else
2882 /* Addresses of conversions and SSA_NAMEs (and many other things)
2883 are not defined. Check that we did not forget to drop the
2884 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2887 #endif
2889 /* In case both args are comparisons but with different comparison
2890 code, try to swap the comparison operands of one arg to produce
2891 a match and compare that variant. */
2895 {
2903 }
2906 {
2907 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2909 ;
2911 {
2912 /* If we are interested in comparing addresses ignore
2913 MEM_REF wrappings of the base that can appear just for
2914 TBAA reasons. */
2928 }
2929 else
2931 }
2933 /* When not checking adddresses, this is needed for conversions and for
2934 COMPONENT_REF. Might as well play it safe and always test this. */
2941 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2942 We don't care about side effects in that case because the SAVE_EXPR
2943 takes care of that for us. In all other cases, two expressions are
2944 equal if they have no side effects. If we have two identical
2945 expressions with side effects that should be treated the same due
2946 to the only side effects being identical SAVE_EXPR's, that will
2947 be detected in the recursive calls below.
2948 If we are taking an invariant address of two identical objects
2949 they are necessarily equal as well. */
2956 /* Next handle constant cases, those for which we can return 1 even
2957 if ONLY_CONST is set. */
2960 {
2974 {
2975 /* If we do not distinguish between signed and unsigned zero,
2976 consider them equal. */
2979 }
2983 {
2998 }
3002 flags)
3004 flags));
3015 flags | OEP_ADDRESS_OF
3018 /* In GIMPLE empty constructors are allowed in initializers of
3019 aggregates. */
3023 }
3028 /* Define macros to test an operand from arg0 and arg1 for equality and a
3029 variant that allows null and views null as being different from any
3030 non-null value. In the latter case, if either is null, the both
3031 must be; otherwise, do the normal comparison. */
3032 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3033 TREE_OPERAND (arg1, N), flags)
3035 #define OP_SAME_WITH_NULL(N) \
3036 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3037 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3040 {
3042 /* Two conversions are equal only if signedness and modes match. */
3044 {
3045 CASE_CONVERT:
3053 }
3063 /* For commutative ops, allow the other order. */
3071 /* If either of the pointer (or reference) expressions we are
3072 dereferencing contain a side effect, these cannot be equal,
3073 but their addresses can be. */
3080 {
3090 /* Require the same offset. */
3096 /* Fallthru. */
3104 {
3105 /* Require equal access sizes */
3111 flags)))
3113 /* Verify that access happens in similar types. */
3116 /* Verify that accesses are TBAA compatible. */
3125 /* Verify that alignment is compatible. */
3129 }
3132 /* TARGET_MEM_REF require equal extra operands. */
3143 /* Compare the array index by value if it is constant first as we
3144 may have different types but same value here. */
3150 /* Compare low bound and element size as with OEP_ADDRESS_OF
3151 we have to account for the offset of the ref. */
3156 array_ref_low_bound
3160 array_ref_element_size
3162 flags))));
3165 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3166 may be NULL when we're called to compare MEM_EXPRs. */
3181 }
3185 {
3187 /* Be sure we pass right ADDRESS_OF flag. */
3205 /* The multiplcation operands are commutative. */
3206 /* FALLTHRU */
3214 /* Otherwise take into account this is a commutative operation. */
3227 /* BIT_INSERT_EXPR has an implict operand as the type precision
3228 of op1. Need to check to make sure they are the same. */
3234 /* FALLTHRU */
3259 }
3263 {
3267 /* If not both CALL_EXPRs are either internal or normal function
3268 functions, then they are not equal. */
3271 {
3272 /* If the CALL_EXPRs call different internal functions, then they
3273 are not equal. */
3276 }
3277 else
3278 {
3279 /* If the CALL_EXPRs call different functions, then they are not
3280 equal. */
3282 flags))
3284 }
3286 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3287 {
3291 else
3295 }
3297 /* Now see if all the arguments are the same. */
3298 {
3309 /* If we get here and both argument lists are exhausted
3310 then the CALL_EXPRs are equal. */
3312 }
3315 }
3318 /* Consider __builtin_sqrt equal to sqrt. */
3326 {
3327 /* In GIMPLE constructors are used only to build vectors from
3328 elements. Individual elements in the constructor must be
3329 indexed in increasing order and form an initial sequence.
3331 We make no effort to compare constructors in generic.
3332 (see sem_variable::equals in ipa-icf which can do so for
3333 constants). */
3338 /* Be sure that vectors constructed have the same representation.
3339 We only tested element precision and modes to match.
3340 Vectors may be BLKmode and thus also check that the number of
3341 parts match. */
3354 {
3359 /* In GIMPLE the indexes can be either NULL or matching i.
3360 Double check this so we won't get false
3361 positives for GENERIC. */
3369 }
3371 }
3374 {
3375 /* Compare the STATEMENT_LISTs. */
3381 {
3382 /* The lists don't have the same number of statements. */
3388 OEP_LEXICOGRAPHIC))
3390 }
3391 }
3396 {
3403 }
3407 }
3409 #undef OP_SAME
3410 #undef OP_SAME_WITH_NULL
3411 }
3412 \f
3413 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3414 with a different signedness or a narrower precision. */
3416 static bool
3418 {
3426 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3427 and see if the inner values are the same. This removes any
3428 signedness comparison, which doesn't matter here. */
3436 /* Discard a single widening conversion from ARG1 and see if the inner
3437 value is the same as ARG0. */
3446 }
3447 \f
3448 /* See if ARG is an expression that is either a comparison or is performing
3449 arithmetic on comparisons. The comparisons must only be comparing
3450 two different values, which will be stored in *CVAL1 and *CVAL2; if
3451 they are nonzero it means that some operands have already been found.
3452 No variables may be used anywhere else in the expression except in the
3453 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3454 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3456 If this is true, return 1. Otherwise, return zero. */
3458 static int
3460 {
3464 /* We can handle some of the tcc_expression cases here. */
3474 {
3475 /* If we've already found a CVAL1 or CVAL2, this expression is
3476 two complex to handle. */
3482 }
3485 {
3508 /* First see if we can handle the first operand, then the second. For
3509 the second operand, we know *CVAL1 can't be zero. It must be that
3510 one side of the comparison is each of the values; test for the
3511 case where this isn't true by failing if the two operands
3512 are the same. */
3521 ;
3525 ;
3526 else
3530 ;
3534 ;
3535 else
3542 }
3543 }
3544 \f
3545 /* ARG is a tree that is known to contain just arithmetic operations and
3546 comparisons. Evaluate the operations in the tree substituting NEW0 for
3547 any occurrence of OLD0 as an operand of a comparison and likewise for
3548 NEW1 and OLD1. */
3550 static tree
3553 {
3558 /* We can handle some of the tcc_expression cases here. */
3566 {
3581 {
3600 }
3601 /* Fall through - ??? */
3604 {
3608 /* We need to check both for exact equality and tree equality. The
3609 former will be true if the operand has a side-effect. In that
3610 case, we know the operand occurred exactly once. */
3623 }
3627 }
3628 }
3629 \f
3630 /* Return a tree for the case when the result of an expression is RESULT
3631 converted to TYPE and OMITTED was previously an operand of the expression
3632 but is now not needed (e.g., we folded OMITTED * 0).
3634 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3635 the conversion of RESULT to TYPE. */
3637 tree
3639 {
3642 /* If the resulting operand is an empty statement, just return the omitted
3643 statement casted to void. */
3653 }
3655 /* Return a tree for the case when the result of an expression is RESULT
3656 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3657 of the expression but are now not needed.
3659 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3660 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3661 evaluated before OMITTED2. Otherwise, if neither has side effects,
3662 just do the conversion of RESULT to TYPE. */
3664 tree
3667 {
3676 }
3678 \f
3679 /* Return a simplified tree node for the truth-negation of ARG. This
3680 never alters ARG itself. We assume that ARG is an operation that
3681 returns a truth value (0 or 1).
3683 FIXME: one would think we would fold the result, but it causes
3684 problems with the dominator optimizer. */
3686 static tree
3688 {
3693 /* If this is a comparison, we can simply invert it, except for
3694 floating-point non-equality comparisons, in which case we just
3695 enclose a TRUTH_NOT_EXPR around what we have. */
3698 {
3701 && flag_trapping_math
3715 }
3718 {
3737 /* Here we can invert either operand. We invert the first operand
3738 unless the second operand is a TRUTH_NOT_EXPR in which case our
3739 result is the XOR of the first operand with the inside of the
3740 negation of the second operand. */
3745 else
3768 {
3775 /* A COND_EXPR may have a throw as one operand, which
3776 then has void type. Just leave void operands
3777 as they are. */
3783 }
3795 CASE_CONVERT:
3799 /* fall through */
3821 }
3822 }
3824 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3825 assume that ARG is an operation that returns a truth value (0 or 1
3826 for scalars, 0 or -1 for vectors). Return the folded expression if
3827 folding is successful. Otherwise, return NULL_TREE. */
3829 static tree
3831 {
3834 ? BIT_NOT_EXPR
3837 }
3839 /* Return a simplified tree node for the truth-negation of ARG. This
3840 never alters ARG itself. We assume that ARG is an operation that
3841 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3843 tree
3845 {
3851 ? BIT_NOT_EXPR
3854 }
3855 \f
3856 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3857 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3858 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3859 is the original memory reference used to preserve the alias set of
3860 the access. */
3862 static tree
3866 {
3869 /* Attempt not to lose the access path if possible. */
3871 {
3873 machine_mode nmode;
3875 tree noffset;
3885 && !reversep
3886 && !nreversep
3888 {
3891 }
3892 }
3901 {
3908 }
3923 }
3925 /* Optimize a bit-field compare.
3927 There are two cases: First is a compare against a constant and the
3928 second is a comparison of two items where the fields are at the same
3929 bit position relative to the start of a chunk (byte, halfword, word)
3930 large enough to contain it. In these cases we can avoid the shift
3931 implicit in bitfield extractions.
3933 For constants, we emit a compare of the shifted constant with the
3934 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3935 compared. For two fields at the same position, we do the ANDs with the
3936 similar mask and compare the result of the ANDs.
3938 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3939 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3940 are the left and right operands of the comparison, respectively.
3942 If the optimization described above can be done, we return the resulting
3943 tree. Otherwise we return zero. */
3945 static tree
3948 {
3951 tree unsigned_type;
3954 scalar_int_mode nmode;
3959 tree mask;
3960 tree offset;
3962 /* Get all the information about the extractions being done. If the bit size
3963 if the same as the size of the underlying object, we aren't doing an
3964 extraction at all and so can do nothing. We also don't want to
3965 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3966 then will no longer be able to replace it. */
3975 else
3976 {
3977 /* If this is not a constant, we can only do something if bit positions,
3978 sizes, signedness and storage order are the same. */
3979 rinner
3987 }
3989 /* Honor the C++ memory model and mimic what RTL expansion does. */
3993 {
3997 }
3999 /* See if we can find a mode to refer to this field. We should be able to,
4000 but fail if we can't. */
4008 /* Set signed and unsigned types of the precision of this mode for the
4009 shifts below. */
4012 /* Compute the bit position and size for the new reference and our offset
4013 within it. If the new reference is the same size as the original, we
4014 won't optimize anything, so return zero. */
4024 /* Make the mask to be used against the extracted field. */
4031 {
4035 /* If not comparing with constant, just rework the comparison
4036 and return. */
4044 }
4046 /* Otherwise, we are handling the constant case. See if the constant is too
4047 big for the field. Warn and return a tree for 0 (false) if so. We do
4048 this not only for its own sake, but to avoid having to test for this
4049 error case below. If we didn't, we might generate wrong code.
4051 For unsigned fields, the constant shifted right by the field length should
4052 be all zero. For signed fields, the high-order bits should agree with
4053 the sign bit. */
4056 {
4058 {
4062 }
4063 }
4064 else
4065 {
4068 {
4072 }
4073 }
4078 /* Single-bit compares should always be against zero. */
4080 {
4083 }
4085 /* Make a new bitfield reference, shift the constant over the
4086 appropriate number of bits and mask it with the computed mask
4087 (in case this was a signed field). If we changed it, make a new one. */
4095 mask);
4100 }
4101 \f
4102 /* Subroutine for fold_truth_andor_1: decode a field reference.
4104 If EXP is a comparison reference, we return the innermost reference.
4106 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4107 set to the starting bit number.
4109 If the innermost field can be completely contained in a mode-sized
4110 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4112 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4113 otherwise it is not changed.
4115 *PUNSIGNEDP is set to the signedness of the field.
4117 *PREVERSEP is set to the storage order of the field.
4119 *PMASK is set to the mask used. This is either contained in a
4120 BIT_AND_EXPR or derived from the width of the field.
4122 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4124 Return 0 if this is not a component reference or is one that we can't
4125 do anything with. */
4127 static tree
4132 {
4137 tree unsigned_type;
4140 /* All the optimizations using this function assume integer fields.
4141 There are problems with FP fields since the type_for_size call
4142 below can fail for, e.g., XFmode. */
4146 /* We are interested in the bare arrangement of bits, so strip everything
4147 that doesn't affect the machine mode. However, record the type of the
4148 outermost expression if it may matter below. */
4155 {
4161 }
4168 /* Reject out-of-bound accesses (PR79731). */
4176 /* If the number of bits in the reference is the same as the bitsize of
4177 the outer type, then the outer type gives the signedness. Otherwise
4178 (in case of a small bitfield) the signedness is unchanged. */
4182 /* Compute the mask to access the bitfield. */
4191 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4199 }
4201 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4202 bit positions and MASK is SIGNED. */
4204 static int
4206 {
4210 /* If this function returns true when the type of the mask is
4211 UNSIGNED, then there will be errors. In particular see
4212 gcc.c-torture/execute/990326-1.c. There does not appear to be
4213 any documentation paper trail as to why this is so. But the pre
4214 wide-int worked with that restriction and it has been preserved
4215 here. */
4220 }
4222 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4223 represents the sign bit of EXP's type. If EXP represents a sign
4224 or zero extension, also test VAL against the unextended type.
4225 The return value is the (sub)expression whose sign bit is VAL,
4226 or NULL_TREE otherwise. */
4228 tree
4230 {
4232 tree t;
4234 /* Tree EXP must have an integral type. */
4239 /* Tree VAL must be an integer constant. */
4248 /* Handle extension from a narrower type. */
4254 }
4256 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4257 to be evaluated unconditionally. */
4259 static int
4261 {
4262 /* Strip any conversions that don't change the machine mode. */
4271 /* Don't regard global variables as simple. They may be
4272 allocated in ways unknown to the compiler (shared memory,
4273 #pragma weak, etc). */
4276 /* Weakrefs are not safe to be read, since they can be NULL.
4277 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4278 have DECL_WEAK flag set. */
4280 /* Loading a static variable is unduly expensive, but global
4281 registers aren't expensive. */
4283 }
4285 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4286 to be evaluated unconditionally.
4287 I addition to simple_operand_p, we assume that comparisons, conversions,
4288 and logic-not operations are simple, if their operands are simple, too. */
4290 static bool
4292 {
4312 }
4314 \f
4315 /* The following functions are subroutines to fold_range_test and allow it to
4316 try to change a logical combination of comparisons into a range test.
4318 For example, both
4319 X == 2 || X == 3 || X == 4 || X == 5
4320 and
4321 X >= 2 && X <= 5
4322 are converted to
4323 (unsigned) (X - 2) <= 3
4325 We describe each set of comparisons as being either inside or outside
4326 a range, using a variable named like IN_P, and then describe the
4327 range with a lower and upper bound. If one of the bounds is omitted,
4328 it represents either the highest or lowest value of the type.
4330 In the comments below, we represent a range by two numbers in brackets
4331 preceded by a "+" to designate being inside that range, or a "-" to
4332 designate being outside that range, so the condition can be inverted by
4333 flipping the prefix. An omitted bound is represented by a "-". For
4334 example, "- [-, 10]" means being outside the range starting at the lowest
4335 possible value and ending at 10, in other words, being greater than 10.
4336 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4337 always false.
4339 We set up things so that the missing bounds are handled in a consistent
4340 manner so neither a missing bound nor "true" and "false" need to be
4341 handled using a special case. */
4343 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4344 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4345 and UPPER1_P are nonzero if the respective argument is an upper bound
4346 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4347 must be specified for a comparison. ARG1 will be converted to ARG0's
4348 type if both are specified. */
4350 static tree
4353 {
4354 tree tem;
4358 /* If neither arg represents infinity, do the normal operation.
4359 Else, if not a comparison, return infinity. Else handle the special
4360 comparison rules. Note that most of the cases below won't occur, but
4361 are handled for consistency. */
4364 {
4369 }
4374 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4375 for neither. In real maths, we cannot assume open ended ranges are
4376 the same. But, this is computer arithmetic, where numbers are finite.
4377 We can therefore make the transformation of any unbounded range with
4378 the value Z, Z being greater than any representable number. This permits
4379 us to treat unbounded ranges as equal. */
4383 {
4404 }
4407 }
4408 \f
4409 /* Helper routine for make_range. Perform one step for it, return
4410 new expression if the loop should continue or NULL_TREE if it should
4411 stop. */
4413 tree
4417 {
4423 {
4425 /* We can only do something if the range is testing for zero. */
4434 /* We can only do something if the range is testing for zero
4435 and if the second operand is an integer constant. Note that
4436 saying something is "in" the range we make is done by
4437 complementing IN_P since it will set in the initial case of
4438 being not equal to zero; "out" is leaving it alone. */
4445 {
4466 }
4468 /* If this is an unsigned comparison, we also know that EXP is
4469 greater than or equal to zero. We base the range tests we make
4470 on that fact, so we record it here so we can parse existing
4471 range tests. We test arg0_type since often the return type
4472 of, e.g. EQ_EXPR, is boolean. */
4474 {
4478 NULL_TREE))
4483 /* If the high bound is missing, but we have a nonzero low
4484 bound, reverse the range so it goes from zero to the low bound
4485 minus 1. */
4487 {
4492 }
4493 }
4501 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4502 low and high are non-NULL, then normalize will DTRT. */
4505 {
4510 }
4512 /* (-x) IN [a,b] -> x in [-b, -a] */
4524 /* ~ X -> -X - 1 */
4533 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4534 move a constant to the other side. */
4539 /* If EXP is signed, any overflow in the computation is undefined,
4540 so we don't worry about it so long as our computations on
4541 the bounds don't overflow. For unsigned, overflow is defined
4542 and this is exactly the right thing. */
4554 normalize:
4555 /* Check for an unsigned range which has wrapped around the maximum
4556 value thus making n_high < n_low, and normalize it. */
4558 {
4564 /* If the range is of the form +/- [ x+1, x ], we won't
4565 be able to normalize it. But then, it represents the
4566 whole range or the empty set, so make it
4567 +/- [ -, - ]. */
4571 else
4573 }
4574 else
4582 CASE_CONVERT:
4600 /* If we're converting arg0 from an unsigned type, to exp,
4601 a signed type, we will be doing the comparison as unsigned.
4602 The tests above have already verified that LOW and HIGH
4603 are both positive.
4605 So we have to ensure that we will handle large unsigned
4606 values the same way that the current signed bounds treat
4607 negative values. */
4610 {
4611 tree high_positive;
4612 tree equiv_type;
4613 /* For fixed-point modes, we need to pass the saturating flag
4614 as the 2nd parameter. */
4616 equiv_type
4619 else
4620 equiv_type
4623 /* A range without an upper bound is, naturally, unbounded.
4624 Since convert would have cropped a very large value, use
4625 the max value for the destination type. */
4626 high_positive
4633 high_positive),
4636 /* If the low bound is specified, "and" the range with the
4637 range for which the original unsigned value will be
4638 positive. */
4640 {
4643 integer_zero_node),
4644 high_positive))
4648 }
4649 else
4650 {
4651 /* Otherwise, "or" the range with the range of the input
4652 that will be interpreted as negative. */
4655 integer_zero_node),
4656 high_positive))
4660 }
4661 }
4670 }
4671 }
4673 /* Given EXP, a logical expression, set the range it is testing into
4674 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4675 actually being tested. *PLOW and *PHIGH will be made of the same
4676 type as the returned expression. If EXP is not a comparison, we
4677 will most likely not be returning a useful value and range. Set
4678 *STRICT_OVERFLOW_P to true if the return value is only valid
4679 because signed overflow is undefined; otherwise, do not change
4680 *STRICT_OVERFLOW_P. */
4682 tree
4685 {
4693 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4694 and see if we can refine the range. Some of the cases below may not
4695 happen, but it doesn't seem worth worrying about this. We "continue"
4696 the outer loop when we've changed something; otherwise we "break"
4697 the switch, which will "break" the while. */
4703 {
4709 {
4717 }
4726 }
4728 /* If EXP is a constant, we can evaluate whether this is true or false. */
4730 {
4737 }
4741 }
4743 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4744 a bitwise check i.e. when
4745 LOW == 0xXX...X00...0
4746 HIGH == 0xXX...X11...1
4747 Return corresponding mask in MASK and stem in VALUE. */
4749 static bool
4752 {
4775 }
4776 \f
4777 /* Helper routine for build_range_check and match.pd. Return the type to
4778 perform the check or NULL if it shouldn't be optimized. */
4780 tree
4782 {
4783 /* First make sure that arithmetics in this type is valid, then make sure
4784 that it wraps around. */
4790 {
4793 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4794 for the type in question, as we rely on this here. */
4804 else
4806 }
4808 }
4810 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4811 type, TYPE, return an expression to test if EXP is in (or out of, depending
4812 on IN_P) the range. Return 0 if the test couldn't be created. */
4814 tree
4817 {
4820 /* Disable this optimization for function pointer expressions
4821 on targets that require function pointer canonicalization. */
4828 {
4834 }
4856 value);
4859 {
4861 {
4865 }
4867 }
4869 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4871 {
4875 {
4877 {
4880 etype
4882 else
4885 }
4888 }
4889 }
4891 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4892 This requires wrap-around arithmetics for the type of the expression. */
4912 }
4913 \f
4914 /* Return the predecessor of VAL in its type, handling the infinite case. */
4916 static tree
4918 {
4924 else
4927 }
4929 /* Return the successor of VAL in its type, handling the infinite case. */
4931 static tree
4933 {
4939 else
4942 }
4944 /* Given two ranges, see if we can merge them into one. Return 1 if we
4945 can, 0 if we can't. Set the output range into the specified parameters. */
4947 bool
4950 {
4954 tree tem;
4964 /* Make range 0 be the range that starts first, or ends last if they
4965 start at the same value. Swap them if it isn't. */
4968 || (lowequal
4971 {
4975 }
4977 /* Now flag two cases, whether the ranges are disjoint or whether the
4978 second range is totally subsumed in the first. Note that the tests
4979 below are simplified by the ones above. */
4985 /* We now have four cases, depending on whether we are including or
4986 excluding the two ranges. */
4988 {
4989 /* If they don't overlap, the result is false. If the second range
4990 is a subset it is the result. Otherwise, the range is from the start
4991 of the second to the end of the first. */
4996 else
4998 }
5001 {
5002 /* If they don't overlap, the result is the first range. If they are
5003 equal, the result is false. If the second range is a subset of the
5004 first, and the ranges begin at the same place, we go from just after
5005 the end of the second range to the end of the first. If the second
5006 range is not a subset of the first, or if it is a subset and both
5007 ranges end at the same place, the range starts at the start of the
5008 first range and ends just before the second range.
5009 Otherwise, we can't describe this as a single range. */
5015 {
5020 {
5021 /* We are in the weird situation where high0 > high1 but
5022 high1 has no successor. Punt. */
5024 }
5025 }
5027 {
5032 {
5033 /* low0 < low1 but low1 has no predecessor. Punt. */
5035 }
5036 }
5037 else
5039 }
5042 {
5043 /* If they don't overlap, the result is the second range. If the second
5044 is a subset of the first, the result is false. Otherwise,
5045 the range starts just after the first range and ends at the
5046 end of the second. */
5051 else
5052 {
5057 {
5058 /* high1 > high0 but high0 has no successor. Punt. */
5060 }
5061 }
5062 }
5064 else
5065 {
5066 /* The case where we are excluding both ranges. Here the complex case
5067 is if they don't overlap. In that case, the only time we have a
5068 range is if they are adjacent. If the second is a subset of the
5069 first, the result is the first. Otherwise, the range to exclude
5070 starts at the beginning of the first range and ends at the end of the
5071 second. */
5073 {
5078 else
5079 {
5080 /* Canonicalize - [min, x] into - [-, x]. */
5083 {
5088 /* FALLTHROUGH */
5101 }
5103 /* Canonicalize - [x, max] into - [x, -]. */
5106 {
5111 /* FALLTHROUGH */
5127 }
5129 /* The ranges might be also adjacent between the maximum and
5130 minimum values of the given type. For
5131 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5132 return + [x + 1, y - 1]. */
5134 {
5141 }
5142 else
5144 }
5145 }
5148 else
5150 }
5154 }
5155 \f
5157 /* Subroutine of fold, looking inside expressions of the form
5158 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5159 of the COND_EXPR. This function is being used also to optimize
5160 A op B ? C : A, by reversing the comparison first.
5162 Return a folded expression whose code is not a COND_EXPR
5163 anymore, or NULL_TREE if no folding opportunity is found. */
5165 static tree
5168 {
5173 tree tem;
5178 /* If we have A op 0 ? A : -A, consider applying the following
5179 transformations:
5181 A == 0? A : -A same as -A
5182 A != 0? A : -A same as A
5183 A >= 0? A : -A same as abs (A)
5184 A > 0? A : -A same as abs (A)
5185 A <= 0? A : -A same as -abs (A)
5186 A < 0? A : -A same as -abs (A)
5188 None of these transformations work for modes with signed
5189 zeros. If A is +/-0, the first two transformations will
5190 change the sign of the result (from +0 to -0, or vice
5191 versa). The last four will fix the sign of the result,
5192 even though the original expressions could be positive or
5193 negative, depending on the sign of A.
5195 Note that all these transformations are correct if A is
5196 NaN, since the two alternatives (A and -A) are also NaNs. */
5203 /* In the case that A is of the form X-Y, '-A' (arg2) may
5204 have already been folded to Y-X, check for that. */
5212 {
5224 /* Fall through. */
5235 /* FALLTHRU */
5245 }
5247 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5248 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5249 both transformations are correct when A is NaN: A != 0
5250 is then true, and A == 0 is false. */
5254 {
5259 }
5261 /* Try some transformations of A op B ? A : B.
5263 A == B? A : B same as B
5264 A != B? A : B same as A
5265 A >= B? A : B same as max (A, B)
5266 A > B? A : B same as max (B, A)
5267 A <= B? A : B same as min (A, B)
5268 A < B? A : B same as min (B, A)
5270 As above, these transformations don't work in the presence
5271 of signed zeros. For example, if A and B are zeros of
5272 opposite sign, the first two transformations will change
5273 the sign of the result. In the last four, the original
5274 expressions give different results for (A=+0, B=-0) and
5275 (A=-0, B=+0), but the transformed expressions do not.
5277 The first two transformations are correct if either A or B
5278 is a NaN. In the first transformation, the condition will
5279 be false, and B will indeed be chosen. In the case of the
5280 second transformation, the condition A != B will be true,
5281 and A will be chosen.
5283 The conversions to max() and min() are not correct if B is
5284 a number and A is not. The conditions in the original
5285 expressions will be false, so all four give B. The min()
5286 and max() versions would give a NaN instead. */
5289 /* Avoid these transformations if the COND_EXPR may be used
5290 as an lvalue in the C++ front-end. PR c++/19199. */
5291 && (in_gimple_form
5297 {
5303 {
5312 /* In C++ a ?: expression can be an lvalue, so put the
5313 operand which will be used if they are equal first
5314 so that we can convert this back to the
5315 corresponding COND_EXPR. */
5317 {
5325 }
5332 {
5340 }
5353 }
5354 }
5357 }
5360 \f
5361 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5362 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5363 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5364 false) >= 2)
5365 #endif
5367 /* EXP is some logical combination of boolean tests. See if we can
5368 merge it into some range test. Return the new tree if so. */
5370 static tree
5373 {
5389 /* If this is an OR operation, invert both sides; we will invert
5390 again at the end. */
5394 /* If both expressions are the same, if we can merge the ranges, and we
5395 can build the range test, return it or it inverted. If one of the
5396 ranges is always true or always false, consider it to be the same
5397 expression as the other. */
5405 {
5409 }
5411 /* On machines where the branch cost is expensive, if this is a
5412 short-circuited branch and the underlying object on both sides
5413 is the same, make a non-short-circuit operation. */
5415 && !flag_sanitize_coverage
5420 {
5421 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5422 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5423 which cases we can't do this. */
5431 {
5440 {
5443 WARN_STRICT_OVERFLOW_COMPARISON);
5447 }
5448 }
5449 }
5452 }
5453 \f
5454 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5455 bit value. Arrange things so the extra bits will be set to zero if and
5456 only if C is signed-extended to its full width. If MASK is nonzero,
5457 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5459 static tree
5461 {
5464 tree temp;
5469 /* We work by getting just the sign bit into the low-order bit, then
5470 into the high-order bit, then sign-extend. We then XOR that value
5471 with C. */
5475 /* We must use a signed type in order to get an arithmetic right shift.
5476 However, we must also avoid introducing accidental overflows, so that
5477 a subsequent call to integer_zerop will work. Hence we must
5478 do the type conversion here. At this point, the constant is either
5479 zero or one, and the conversion to a signed type can never overflow.
5480 We could get an overflow if this conversion is done anywhere else. */
5489 /* If necessary, convert the type back to match the type of C. */
5494 }
5495 \f
5496 /* For an expression that has the form
5497 (A && B) || ~B
5498 or
5499 (A || B) && ~B,
5500 we can drop one of the inner expressions and simplify to
5501 A || ~B
5502 or
5503 A && ~B
5504 LOC is the location of the resulting expression. OP is the inner
5505 logical operation; the left-hand side in the examples above, while CMPOP
5506 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5507 removing a condition that guards another, as in
5508 (A != NULL && A->...) || A == NULL
5509 which we must not transform. If RHS_ONLY is true, only eliminate the
5510 right-most operand of the inner logical operation. */
5512 static tree
5515 {
5533 {
5536 {
5539 }
5540 }
5542 {
5545 {
5548 }
5549 }
5564 }
5566 /* Find ways of folding logical expressions of LHS and RHS:
5567 Try to merge two comparisons to the same innermost item.
5568 Look for range tests like "ch >= '0' && ch <= '9'".
5569 Look for combinations of simple terms on machines with expensive branches
5570 and evaluate the RHS unconditionally.
5572 For example, if we have p->a == 2 && p->b == 4 and we can make an
5573 object large enough to span both A and B, we can do this with a comparison
5574 against the object ANDed with the a mask.
5576 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5577 operations to do this with one comparison.
5579 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5580 function and the one above.
5582 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5583 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5585 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5586 two operands.
5588 We return the simplified tree or 0 if no optimization is possible. */
5590 static tree
5593 {
5594 /* If this is the "or" of two comparisons, we can do something if
5595 the comparisons are NE_EXPR. If this is the "and", we can do something
5596 if the comparisons are EQ_EXPR. I.e.,
5597 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5599 WANTED_CODE is this operation code. For single bit fields, we can
5600 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5601 comparison for one-bit fields. */
5622 /* Start by getting the comparison codes. Fail if anything is volatile.
5623 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5624 it were surrounded with a NE_EXPR. */
5633 {
5637 }
5640 {
5644 }
5655 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5658 {
5661 {
5666 }
5669 {
5675 }
5676 }
5681 /* If the RHS can be evaluated unconditionally and its operands are
5682 simple, it wins to evaluate the RHS unconditionally on machines
5683 with expensive branches. In this case, this isn't a comparison
5684 that can be merged. */
5691 {
5692 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5703 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5713 }
5715 /* See if the comparisons can be merged. Then get all the parameters for
5716 each side. */
5741 /* It must be true that the inner operation on the lhs of each
5742 comparison must be the same if we are to be able to do anything.
5743 Then see if we have constants. If not, the same must be true for
5744 the rhs's. */
5753 {
5756 }
5761 else
5764 /* If either comparison code is not correct for our logical operation,
5765 fail. However, we can convert a one-bit comparison against zero into
5766 the opposite comparison against that bit being set in the field. */
5770 {
5772 {
5773 /* Make the left operand unsigned, since we are only interested
5774 in the value of one bit. Otherwise we are doing the wrong
5775 thing below. */
5778 }
5779 else
5781 }
5783 /* This is analogous to the code for l_const above. */
5785 {
5787 {
5790 }
5791 else
5793 }
5795 /* See if we can find a mode that contains both fields being compared on
5796 the left. If we can't, fail. Otherwise, update all constants and masks
5797 to be relative to a field of that size. */
5811 {
5814 }
5822 {
5829 {
5833 }
5834 }
5836 {
5843 {
5847 }
5848 }
5850 /* If the right sides are not constant, do the same for it. Also,
5851 disallow this optimization if a size or signedness mismatch occurs
5852 between the left and right sides. */
5854 {
5857 /* Make sure the two fields on the right
5858 correspond to the left without being swapped. */
5875 {
5878 }
5887 /* Make a mask that corresponds to both fields being compared.
5888 Do this for both items being compared. If the operands are the
5889 same size and the bits being compared are in the same position
5890 then we can do this by masking both and comparing the masked
5891 results. */
5898 {
5912 }
5914 /* There is still another way we can do something: If both pairs of
5915 fields being compared are adjacent, we may be able to make a wider
5916 field containing them both.
5918 Note that we still must mask the lhs/rhs expressions. Furthermore,
5919 the mask must be shifted to account for the shift done by
5920 make_bit_field_ref. */
5929 {
5930 tree type;
5946 /* Convert to the smaller type before masking out unwanted bits. */
5949 {
5951 {
5955 }
5957 {
5961 }
5962 }
5971 }
5974 }
5976 /* Handle the case of comparisons with constants. If there is something in
5977 common between the masks, those bits of the constants must be the same.
5978 If not, the condition is always false. Test for this to avoid generating
5979 incorrect code below. */
5984 {
5986 {
5989 }
5990 else
5991 {
5994 }
5995 }
6000 /* Construct the expression we will return. First get the component
6001 reference we will make. Unless the mask is all ones the width of
6002 that field, perform the mask operation. Then compare with the
6003 merged constant. */
6014 }
6015 \f
6016 /* T is an integer expression that is being multiplied, divided, or taken a
6017 modulus (CODE says which and what kind of divide or modulus) by a
6018 constant C. See if we can eliminate that operation by folding it with
6019 other operations already in T. WIDE_TYPE, if non-null, is a type that
6020 should be used for the computation if wider than our type.
6022 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6023 (X * 2) + (Y * 4). We must, however, be assured that either the original
6024 expression would not overflow or that overflow is undefined for the type
6025 in the language in question.
6027 If we return a non-null expression, it is an equivalent form of the
6028 original computation, but need not be in the original type.
6030 We set *STRICT_OVERFLOW_P to true if the return values depends on
6031 signed overflow being undefined. Otherwise we do not change
6032 *STRICT_OVERFLOW_P. */
6034 static tree
6037 {
6038 /* To avoid exponential search depth, refuse to allow recursion past
6039 three levels. Beyond that (1) it's highly unlikely that we'll find
6040 something interesting and (2) we've probably processed it before
6041 when we built the inner expression. */
6044 tree ret;
6049 depth++;
6051 depth--;
6054 }
6056 static tree
6059 {
6071 /* Don't deal with constants of zero here; they confuse the code below. */
6081 /* Note that we need not handle conditional operations here since fold
6082 already handles those cases. So just do arithmetic here. */
6084 {
6086 /* For a constant, we can always simplify if we are a multiply
6087 or (for divide and modulus) if it is a multiple of our constant. */
6091 {
6094 /* If the multiplication overflowed, we lost information on it.
6095 See PR68142 and PR69845. */
6099 }
6103 /* If op0 is an expression ... */
6109 /* ... and has wrapping overflow, and its type is smaller
6110 than ctype, then we cannot pass through as widening. */
6115 /* ... or this is a truncation (t is narrower than op0),
6116 then we cannot pass through this narrowing. */
6119 /* ... or signedness changes for division or modulus,
6120 then we cannot pass through this conversion. */
6124 /* ... or has undefined overflow while the converted to
6125 type has not, we cannot do the operation in the inner type
6126 as that would introduce undefined overflow. */
6132 /* Pass the constant down and see if we can make a simplification. If
6133 we can, replace this expression with the inner simplification for
6134 possible later conversion to our or some other type. */
6139 code == MULT_EXPR
6141 strict_overflow_p))))
6146 /* If widening the type changes it from signed to unsigned, then we
6147 must avoid building ABS_EXPR itself as unsigned. */
6149 {
6153 {
6156 }
6158 }
6159 /* If the constant is negative, we cannot simplify this. */
6162 /* FALLTHROUGH */
6164 /* For division and modulus, type can't be unsigned, as e.g.
6165 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6166 For signed types, even with wrapping overflow, this is fine. */
6175 /* If widening the type changes the signedness, then we can't perform
6176 this optimization as that changes the result. */
6180 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6186 {
6193 }
6197 /* If the second operand is constant, this is a multiplication
6198 or floor division, by a power of two, so we can treat it that
6199 way unless the multiplier or divisor overflows. Signed
6200 left-shift overflow is implementation-defined rather than
6201 undefined in C90, so do not convert signed left shift into
6202 multiplication. */
6205 /* const_binop may not detect overflow correctly,
6206 so check for it explicitly here. */
6211 size_one_node,
6212 op1)))
6216 ctype,
6218 t1),
6223 /* See if we can eliminate the operation on both sides. If we can, we
6224 can return a new PLUS or MINUS. If we can't, the only remaining
6225 cases where we can do anything are if the second operand is a
6226 constant. */
6233 /* If not multiplication, we can only do this if both operands
6234 are divisible by c. */
6237 {
6242 }
6244 /* If this was a subtraction, negate OP1 and set it to be an addition.
6245 This simplifies the logic below. */
6247 {
6249 /* If OP1 was not easily negatable, the constant may be OP0. */
6251 {
6254 }
6255 }
6260 /* If either OP1 or C are negative, this optimization is not safe for
6261 some of the division and remainder types while for others we need
6262 to change the code. */
6264 {
6272 }
6274 /* If it's a multiply or a division/modulus operation of a multiple
6275 of our constant, do the operation and verify it doesn't overflow. */
6279 {
6282 /* We allow the constant to overflow with wrapping semantics. */
6286 }
6287 else
6290 /* If we have an unsigned type, we cannot widen the operation since it
6291 will change the result if the original computation overflowed. */
6295 /* The last case is if we are a multiply. In that case, we can
6296 apply the distributive law to commute the multiply and addition
6297 if the multiplication of the constants doesn't overflow
6298 and overflow is defined. With undefined overflow
6299 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6305 op1);
6310 /* We have a special case here if we are doing something like
6311 (C * 8) % 4 since we know that's zero. */
6314 /* If the multiplication can overflow we cannot optimize this. */
6319 {
6322 }
6324 /* ... fall through ... */
6328 /* If we can extract our operation from the LHS, do so and return a
6329 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6330 do something only if the second operand is a constant. */
6346 /* If these are the same operation types, we can associate them
6347 assuming no overflow. */
6349 {
6364 }
6366 /* If these operations "cancel" each other, we have the main
6367 optimizations of this pass, which occur when either constant is a
6368 multiple of the other, in which case we replace this with either an
6369 operation or CODE or TCODE.
6371 If we have an unsigned type, we cannot do this since it will change
6372 the result if the original computation overflowed. */
6379 {
6382 {
6389 }
6392 {
6399 }
6400 }
6405 }
6408 }
6409 \f
6410 /* Return a node which has the indicated constant VALUE (either 0 or
6411 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6412 and is of the indicated TYPE. */
6414 tree
6416 {
6425 else
6427 }
6430 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6431 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6432 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6433 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6434 COND is the first argument to CODE; otherwise (as in the example
6435 given here), it is the second argument. TYPE is the type of the
6436 original expression. Return NULL_TREE if no simplification is
6437 possible. */
6439 static tree
6444 {
6454 {
6458 /* If this operand throws an expression, then it does not make
6459 sense to try to perform a logical or arithmetic operation
6460 involving it. */
6465 }
6468 {
6473 }
6474 else
6475 /* Detect the case of mixing vector and scalar types - bail out. */
6481 /* This transformation is only worthwhile if we don't have to wrap ARG
6482 in a SAVE_EXPR and the operation can be simplified without recursing
6483 on at least one of the branches once its pushed inside the COND_EXPR. */
6492 {
6496 else
6498 }
6500 {
6504 else
6506 }
6508 /* Check that we have simplified at least one of the branches. */
6513 }
6515 \f
6516 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6518 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6519 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6520 ADDEND is the same as X.
6522 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6523 and finite. The problematic cases are when X is zero, and its mode
6524 has signed zeros. In the case of rounding towards -infinity,
6525 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6526 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6528 bool
6530 {
6534 /* Don't allow the fold with -fsignaling-nans. */
6538 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6542 /* In a vector or complex, we would need to check the sign of all zeros. */
6546 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6550 /* The mode has signed zeros, and we have to honor their sign.
6551 In this situation, there is only one case we can return true for.
6552 X - 0 is the same as X unless rounding towards -infinity is
6553 supported. */
6555 }
6557 /* Subroutine of match.pd that optimizes comparisons of a division by
6558 a nonzero integer constant against an integer constant, i.e.
6559 X/C1 op C2.
6561 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6562 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6564 enum tree_code
6567 {
6572 /* We have to do this the hard way to detect unsigned overflow.
6573 prod = int_const_binop (MULT_EXPR, c1, c2); */
6579 {
6583 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6586 }
6588 {
6591 {
6610 }
6611 }
6612 else
6613 {
6614 /* A negative divisor reverses the relational operators. */
6619 {
6638 }
6639 }
6652 }
6655 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6656 equality/inequality test, then return a simplified form of the test
6657 using a sign testing. Otherwise return NULL. TYPE is the desired
6658 result type. */
6660 static tree
6663 tree result_type)
6664 {
6665 /* If this is testing a single bit, we can optimize the test. */
6669 {
6670 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6671 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6675 /* This is only a win if casting to a signed type is cheap,
6676 i.e. when arg00's type is not a partial mode. */
6678 {
6681 result_type,
6684 }
6685 }
6688 }
6690 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6691 equality/inequality test, then return a simplified form of
6692 the test using shifts and logical operations. Otherwise return
6693 NULL. TYPE is the desired result type. */
6695 tree
6698 {
6699 /* If this is testing a single bit, we can optimize the test. */
6703 {
6712 /* First, see if we can fold the single bit test into a sign-bit
6713 test. */
6715 result_type);
6719 /* Otherwise we have (A & C) != 0 where C is a single bit,
6720 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6721 Similarly for (A & C) == 0. */
6723 /* If INNER is a right shift of a constant and it plus BITNUM does
6724 not overflow, adjust BITNUM and INNER. */
6730 {
6733 }
6735 /* If we are going to be able to omit the AND below, we must do our
6736 operations as unsigned. If we must use the AND, we have a choice.
6737 Normally unsigned is faster, but for some machines signed is. */
6755 /* Put the AND last so it can combine with more things. */
6758 /* Make sure to return the proper type. */
6762 }
6764 }
6766 /* Test whether it is preferable two swap two operands, ARG0 and
6767 ARG1, for example because ARG0 is an integer constant and ARG1
6768 isn't. */
6770 bool
6772 {
6786 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6787 for commutative and comparison operators. Ensuring a canonical
6788 form allows the optimizers to find additional redundancies without
6789 having to explicitly check for both orderings. */
6795 /* Put SSA_NAMEs last. */
6801 /* Put variables last. */
6808 }
6811 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6812 means A >= Y && A != MAX, but in this case we know that
6813 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6815 static tree
6817 {
6824 else
6833 {
6836 }
6838 {
6841 }
6842 else
6849 {
6850 /* Convert the pointer types into integer before taking the difference. */
6854 }
6855 else
6862 }
6864 /* Fold a sum or difference of at least one multiplication.
6865 Returns the folded tree or NULL if no simplification could be made. */
6867 static tree
6870 {
6874 /* (A * C) +- (B * C) -> (A+-B) * C.
6875 (A * C) +- A -> A * (C+-1).
6876 We are most concerned about the case where C is a constant,
6877 but other combinations show up during loop reduction. Since
6878 it is not difficult, try all four possibilities. */
6881 {
6884 }
6886 {
6889 }
6890 else
6891 {
6892 /* We cannot generate constant 1 for fract. */
6897 }
6899 {
6902 }
6904 {
6906 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6907 the purpose of this canonicalization. */
6911 {
6914 }
6915 else
6917 }
6918 else
6919 {
6920 /* We cannot generate constant 1 for fract. */
6925 }
6928 /* Prefer factoring a common non-constant. */
6938 /* No identical multiplicands; see if we can find a common
6939 power-of-two factor in non-power-of-two multiplies. This
6940 can help in multi-dimensional array access. */
6943 {
6946 tree maybe_same;
6950 /* Move min of absolute values to int11. */
6952 {
6957 }
6958 else
6962 /* The remainder should not be a constant, otherwise we
6963 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6964 increased the number of multiplications necessary. */
6966 {
6974 }
6975 }
6982 /* We are neither factoring zero nor minus one. */
6990 /* Same may be zero and thus the operation 'code' may overflow. Likewise
6991 same may be minus one and thus the multiplication may overflow. Perform
6992 the operations in an unsigned type. */
6997 /* If the sum evaluated to a constant that is not -INF the multiplication
6998 cannot overflow. */
7008 }
7010 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7011 specified by EXPR into the buffer PTR of length LEN bytes.
7012 Return the number of bytes placed in the buffer, or zero
7013 upon failure. */
7015 static int
7017 {
7029 /* Dry run. */
7035 {
7037 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7038 number of bytes. */
7042 {
7049 else
7051 }
7052 else
7056 }
7058 }
7061 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7062 specified by EXPR into the buffer PTR of length LEN bytes.
7063 Return the number of bytes placed in the buffer, or zero
7064 upon failure. */
7066 static int
7068 {
7072 FIXED_VALUE_TYPE value;
7087 }
7090 /* Subroutine of native_encode_expr. Encode the REAL_CST
7091 specified by EXPR into the buffer PTR of length LEN bytes.
7092 Return the number of bytes placed in the buffer, or zero
7093 upon failure. */
7095 static int
7097 {
7103 /* There are always 32 bits in each long, no matter the size of
7104 the hosts long. We handle floating point representations with
7105 up to 192 bits. */
7114 /* Dry run. */
7123 {
7128 {
7135 else
7137 }
7138 else
7139 {
7142 {
7143 /* Reverse bytes within each long, or within the entire float
7144 if it's smaller than a long (for HFmode). */
7147 }
7148 }
7153 }
7155 }
7157 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7158 specified by EXPR into the buffer PTR of length LEN bytes.
7159 Return the number of bytes placed in the buffer, or zero
7160 upon failure. */
7162 static int
7164 {
7166 tree part;
7180 }
7183 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7184 specified by EXPR into the buffer PTR of length LEN bytes.
7185 Return the number of bytes placed in the buffer, or zero
7186 upon failure. */
7188 static int
7190 {
7200 {
7202 {
7205 }
7216 }
7218 }
7221 /* Subroutine of native_encode_expr. Encode the STRING_CST
7222 specified by EXPR into the buffer PTR of length LEN bytes.
7223 Return the number of bytes placed in the buffer, or zero
7224 upon failure. */
7226 static int
7228 {
7231 /* Wide-char strings are encoded in target byte-order so native
7232 encoding them is trivial. */
7247 {
7250 {
7253 }
7256 }
7257 else
7260 }
7263 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7264 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7265 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7266 anything, just do a dry run. If OFF is not -1 then start
7267 the encoding at byte offset OFF and encode at most LEN bytes.
7268 Return the number of bytes placed in the buffer, or zero upon failure. */
7270 int
7272 {
7273 /* We don't support starting at negative offset and -1 is special. */
7278 {
7299 }
7300 }
7303 /* Subroutine of native_interpret_expr. Interpret the contents of
7304 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7305 If the buffer cannot be interpreted, return NULL_TREE. */
7307 static tree
7309 {
7319 }
7322 /* Subroutine of native_interpret_expr. Interpret the contents of
7323 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7324 If the buffer cannot be interpreted, return NULL_TREE. */
7326 static tree
7328 {
7331 double_int result;
7332 FIXED_VALUE_TYPE fixed_value;
7342 }
7345 /* Subroutine of native_interpret_expr. Interpret the contents of
7346 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7347 If the buffer cannot be interpreted, return NULL_TREE. */
7349 static tree
7351 {
7355 /* There are always 32 bits in each long, no matter the size of
7356 the hosts long. We handle floating point representations with
7357 up to 192 bits. */
7358 REAL_VALUE_TYPE r;
7368 {
7369 /* Both OFFSET and BYTE index within a long;
7370 bitpos indexes the whole float. */
7373 {
7380 else
7382 }
7383 else
7384 {
7387 {
7388 /* Reverse bytes within each long, or within the entire float
7389 if it's smaller than a long (for HFmode). */
7392 }
7393 }
7397 }
7401 }
7404 /* Subroutine of native_interpret_expr. Interpret the contents of
7405 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7406 If the buffer cannot be interpreted, return NULL_TREE. */
7408 static tree
7410 {
7425 }
7428 /* Subroutine of native_interpret_expr. Interpret the contents of
7429 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7430 If the buffer cannot be interpreted, return NULL_TREE. */
7432 static tree
7434 {
7446 {
7451 }
7453 }
7456 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7457 the buffer PTR of length LEN as a constant of type TYPE. For
7458 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7459 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7460 return NULL_TREE. */
7462 tree
7464 {
7466 {
7488 }
7489 }
7491 /* Returns true if we can interpret the contents of a native encoding
7492 as TYPE. */
7494 static bool
7496 {
7498 {
7511 }
7512 }
7515 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7516 TYPE at compile-time. If we're unable to perform the conversion
7517 return NULL_TREE. */
7519 static tree
7521 {
7522 /* We support up to 512-bit values (for V8DFmode). */
7526 /* Check that the host and target are sane. */
7535 }
7537 /* Build an expression for the address of T. Folds away INDIRECT_REF
7538 to avoid confusing the gimplify process. */
7540 tree
7542 {
7543 /* The size of the object is not relevant when talking about its address. */
7548 {
7553 }
7563 {
7568 }
7569 else
7573 }
7575 /* Build an expression for the address of T. */
7577 tree
7579 {
7583 }
7585 /* Fold a unary expression of code CODE and type TYPE with operand
7586 OP0. Return the folded expression if folding is successful.
7587 Otherwise, return NULL_TREE. */
7589 tree
7591 {
7592 tree tem;
7593 tree arg0;
7601 {
7604 {
7605 /* Don't use STRIP_NOPS, because signedness of argument type
7606 matters. */
7608 }
7609 else
7610 {
7611 /* Strip any conversions that don't change the mode. This
7612 is safe for every expression, except for a comparison
7613 expression because its signedness is derived from its
7614 operands.
7616 Note that this is done as an internal manipulation within
7617 the constant folder, in order to find the simplest
7618 representation of the arguments so that their form can be
7619 studied. In any cases, the appropriate type conversions
7620 should be put back in the tree that will get out of the
7621 constant folder. */
7623 }
7626 {
7629 {
7633 }
7634 }
7635 }
7642 {
7649 {
7663 /* If this was a conversion, and all we did was to move into
7664 inside the COND_EXPR, bring it back out. But leave it if
7665 it is a conversion from integer to integer and the
7666 result precision is no wider than a word since such a
7667 conversion is cheap and may be optimized away by combine,
7668 while it couldn't if it were outside the COND_EXPR. Then return
7669 so we don't get into an infinite recursion loop taking the
7670 conversion out and then back in. */
7682 && (INTEGRAL_TYPE_P
7695 }
7696 }
7699 {
7705 CASE_CONVERT:
7709 {
7710 /* If we have (type) (a CMP b) and type is an integral type, return
7711 new expression involving the new type. Canonicalize
7712 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7713 non-integral type.
7714 Do not fold the result as that would not simplify further, also
7715 folding again results in recursions. */
7725 }
7727 /* Handle (T *)&A.B.C for A being of type T and B and C
7728 living at offset zero. This occurs frequently in
7729 C++ upcasting and then accessing the base. */
7733 {
7735 tree offset;
7736 machine_mode mode;
7738 tree base
7742 /* If the reference was to a (constant) zero offset, we can use
7743 the address of the base if it has the same base type
7744 as the result type and the pointer type is unqualified. */
7751 }
7755 /* Detect assigning a bitfield. */
7757 && DECL_BIT_FIELD
7759 {
7760 /* Don't leave an assignment inside a conversion
7761 unless assigning a bitfield. */
7763 /* First do the assignment, then return converted constant. */
7768 }
7770 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7771 constants (if x has signed type, the sign bit cannot be set
7772 in c). This folds extension into the BIT_AND_EXPR.
7773 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7774 very likely don't have maximal range for their precision and this
7775 transformation effectively doesn't preserve non-maximal ranges. */
7779 {
7790 <= HOST_BITS_PER_WIDE_INT
7792 {
7796 cst &= HOST_WIDE_INT_M1U
7800 && !flag_syntax_only
7803 {
7807 }
7808 }
7810 {
7815 }
7816 }
7818 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7819 cast (T1)X will fold away. We assume that this happens when X itself
7820 is a cast. */
7824 {
7828 return fold_build_pointer_plus_loc
7830 }
7832 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7833 of the same precision, and X is an integer type not narrower than
7834 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7840 {
7846 }
7848 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7849 type of X and Y (integer types only). */
7854 {
7855 /* Be careful not to introduce new overflows. */
7856 tree mult_type;
7859 else
7863 {
7870 }
7871 }
7877 {
7884 }
7895 /* Convert fabs((double)float) into (double)fabsf(float). */
7898 {
7904 targ0));
7905 }
7909 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7928 /* Note that the operand of this must be an int
7929 and its values must be 0 or 1.
7930 ("true" is a fixed value perhaps depending on the language,
7931 but we don't handle values other than 1 correctly yet.) */
7938 /* Fold *&X to X if X is an lvalue. */
7940 {
7947 }
7953 }
7956 /* If the operation was a conversion do _not_ mark a resulting constant
7957 with TREE_OVERFLOW if the original constant was not. These conversions
7958 have implementation defined behavior and retaining the TREE_OVERFLOW
7959 flag here would confuse later passes such as VRP. */
7960 tree
7963 {
7972 }
7974 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7975 operands OP0 and OP1. LOC is the location of the resulting expression.
7976 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7977 Return the folded expression if folding is successful. Otherwise,
7978 return NULL_TREE. */
7979 static tree
7982 {
7983 tree tem;
7985 /* We only do these simplifications if we are optimizing. */
7989 /* Check for things like (A || B) && (A || C). We can convert this
7990 to A || (B && C). Note that either operator can be any of the four
7991 truth and/or operations and the transformation will still be
7992 valid. Also note that we only care about order for the
7993 ANDIF and ORIF operators. If B contains side effects, this
7994 might change the truth-value of A. */
8001 {
8021 /* This case if tricky because we must either have commutative
8022 operators or else A10 must not have side-effects. */
8028 a01);
8029 }
8031 /* See if we can build a range comparison. */
8037 {
8041 }
8045 {
8049 }
8051 /* Check for the possibility of merging component references. If our
8052 lhs is another similar operation, try to merge its rhs with our
8053 rhs. Then try to merge our lhs and rhs. */
8063 && !flag_sanitize_coverage
8068 {
8075 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8076 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8077 We don't want to pack more than two leafs to a non-IF AND/OR
8078 expression.
8079 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8080 equal to IF-CODE, then we don't want to add right-hand operand.
8081 If the inner right-hand side of left-hand operand has
8082 side-effects, or isn't simple, then we can't add to it,
8083 as otherwise we might destroy if-sequence. */
8086 /* Needed for sequence points to handle trappings, and
8087 side-effects. */
8089 {
8091 arg1);
8093 tem);
8094 }
8095 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8096 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8099 /* Needed for sequence points to handle trappings, and
8100 side-effects. */
8102 {
8107 }
8108 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8109 into (A OR B).
8110 For sequence point consistancy, we need to check for trapping,
8111 and side-effects. */
8115 }
8118 }
8120 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8121 by changing CODE to reduce the magnitude of constants involved in
8122 ARG0 of the comparison.
8123 Returns a canonicalized comparison tree if a simplification was
8124 possible, otherwise returns NULL_TREE.
8125 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8126 valid if signed overflow is undefined. */
8128 static tree
8132 {
8137 /* Match A +- CST code arg1. We can change this only if overflow
8138 is undefined. */
8141 /* In principle pointers also have undefined overflow behavior,
8142 but that causes problems elsewhere. */
8149 /* Identify the constant in arg0 and its sign. */
8153 /* Overflowed constants and zero will cause problems. */
8158 /* See if we can reduce the magnitude of the constant in
8159 arg0 by changing the comparison code. */
8160 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8164 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8168 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8172 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8176 else
8180 /* Now build the constant reduced in magnitude. But not if that
8181 would produce one outside of its types range. */
8197 }
8199 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8200 overflow further. Try to decrease the magnitude of constants involved
8201 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8202 and put sole constants at the second argument position.
8203 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8205 static tree
8208 {
8209 tree t;
8214 /* Try canonicalization by simplifying arg0. */
8219 {
8223 }
8225 /* Try canonicalization by simplifying arg1 using the swapped
8226 comparison. */
8234 }
8236 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8237 space. This is used to avoid issuing overflow warnings for
8238 expressions like &p->x which can not wrap. */
8240 static bool
8242 {
8249 wide_int wi_offset;
8255 else
8271 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8272 array. */
8274 {
8275 HOST_WIDE_INT base_size;
8280 }
8283 }
8285 /* Return a positive integer when the symbol DECL is known to have
8286 a nonzero address, zero when it's known not to (e.g., it's a weak
8287 symbol), and a negative integer when the symbol is not yet in the
8288 symbol table and so whether or not its address is zero is unknown.
8289 For function local objects always return positive integer. */
8290 static int
8292 {
8297 /* Function local objects are never NULL. */
8305 }
8307 /* Subroutine of fold_binary. This routine performs all of the
8308 transformations that are common to the equality/inequality
8309 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8310 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8311 fold_binary should call fold_binary. Fold a comparison with
8312 tree code CODE and type TYPE with operands OP0 and OP1. Return
8313 the folded comparison or NULL_TREE. */
8315 static tree
8318 {
8328 /* For comparisons of pointers we can decompose it to a compile time
8329 comparison of the base objects and the offsets into the object.
8330 This requires at least one operand being an ADDR_EXPR or a
8331 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8337 {
8340 machine_mode mode;
8344 /* Get base and offset for the access. Strip ADDR_EXPR for
8345 get_inner_reference, but put it back by stripping INDIRECT_REF
8346 off the base object if possible. indirect_baseN will be true
8347 if baseN is not an address but refers to the object itself. */
8350 {
8351 base0
8357 else
8359 }
8361 {
8365 {
8366 base0
8372 else
8374 }
8377 else
8381 {
8387 {
8390 }
8391 }
8392 }
8396 {
8397 base1
8403 else
8405 }
8407 {
8411 {
8412 base1
8418 else
8420 }
8423 else
8427 {
8433 {
8436 }
8437 }
8438 }
8440 /* If we have equivalent bases we might be able to simplify. */
8444 {
8445 /* We can fold this expression to a constant if the non-constant
8446 offset parts are equal. */
8450 {
8456 "occur when comparing P +- C1 with "
8458 WARN_STRICT_OVERFLOW_CONDITIONAL);
8461 {
8475 }
8476 }
8477 /* We can simplify the comparison to a comparison of the variable
8478 offset parts if the constant offset parts are equal.
8479 Be careful to use signed sizetype here because otherwise we
8480 mess with array offsets in the wrong way. This is possible
8481 because pointer arithmetic is restricted to retain within an
8482 object and overflow on pointer differences is undefined as of
8483 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8485 {
8486 /* By converting to signed sizetype we cover middle-end pointer
8487 arithmetic which operates on unsigned pointer types of size
8488 type size and ARRAY_REF offsets which are properly sign or
8489 zero extended from their type in case it is narrower than
8490 sizetype. */
8493 else
8497 else
8504 "occur when comparing P +- C1 with "
8506 WARN_STRICT_OVERFLOW_COMPARISON);
8509 }
8510 }
8511 /* For equal offsets we can simplify to a comparison of the
8512 base addresses. */
8514 && (indirect_base0
8516 && (indirect_base1
8521 {
8527 }
8528 /* Comparison between an ordinary (non-weak) symbol and a null
8529 pointer can be eliminated since such symbols must have a non
8530 null address. In C, relational expressions between pointers
8531 to objects and null pointers are undefined. The results
8532 below follow the C++ rules with the additional property that
8533 every object pointer compares greater than a null pointer.
8534 */
8537 /* Avoid folding references to struct members at offset 0 to
8538 prevent tests like '&ptr->firstmember == 0' from getting
8539 eliminated. When ptr is null, although the -> expression
8540 is strictly speaking invalid, GCC retains it as a matter
8541 of QoI. See PR c/44555. */
8544 && indirect_base0
8545 /* The caller guarantees that when one of the arguments is
8546 constant (i.e., null in this case) it is second. */
8548 {
8550 {
8561 }
8562 }
8563 }
8565 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8566 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8567 the resulting offset is smaller in absolute value than the
8568 original one and has the same sign. */
8577 {
8582 tree cst;
8584 "occur when combining constants around "
8587 /* Put the constant on the side where it doesn't overflow and is
8588 of lower absolute value and of same sign than before. */
8595 {
8598 variable1,
8602 }
8610 {
8616 variable2);
8617 }
8618 }
8624 /* If we are comparing an expression that just has comparisons
8625 of two integer values, arithmetic expressions of those comparisons,
8626 and constants, we can simplify it. There are only three cases
8627 to check: the two values can either be equal, the first can be
8628 greater, or the second can be greater. Fold the expression for
8629 those three values. Since each value must be 0 or 1, we have
8630 eight possibilities, each of which corresponds to the constant 0
8631 or 1 or one of the six possible comparisons.
8633 This handles common cases like (a > b) == 0 but also handles
8634 expressions like ((x > y) - (y > x)) > 0, which supposedly
8635 occur in macroized code. */
8638 {
8643 /* Don't handle degenerate cases here; they should already
8644 have been handled anyway. */
8653 {
8657 /* We can't just pass T to eval_subst in case cval1 or cval2
8658 was the same as ARG1. */
8660 tree high_result
8664 arg1);
8665 tree equal_result
8669 arg1);
8670 tree low_result
8674 arg1);
8676 /* All three of these results should be 0 or 1. Confirm they are.
8677 Then use those values to select the proper code to use. */
8682 {
8683 /* Make a 3-bit mask with the high-order bit being the
8684 value for `>', the next for '=', and the low for '<'. */
8688 {
8690 /* Always false. */
8711 /* Always true. */
8713 }
8716 {
8720 }
8722 }
8723 }
8724 }
8727 }
8730 /* Subroutine of fold_binary. Optimize complex multiplications of the
8731 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8732 argument EXPR represents the expression "z" of type TYPE. */
8734 static tree
8736 {
8741 {
8744 }
8746 {
8749 }
8750 else
8751 {
8755 }
8764 }
8767 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8768 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8769 true if successful. */
8771 static bool
8773 {
8777 {
8780 }
8782 {
8788 else
8790 }
8791 else
8797 }
8799 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8800 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8801 NULL_TREE otherwise. */
8803 static tree
8805 {
8824 {
8828 }
8831 {
8837 }
8838 else
8840 }
8842 /* Try to fold a pointer difference of type TYPE two address expressions of
8843 array references AREF0 and AREF1 using location LOC. Return a
8844 simplified expression for the difference or NULL_TREE. */
8846 static tree
8850 {
8855 /* If the bases are array references as well, recurse. If the bases
8856 are pointer indirections compute the difference of the pointers.
8857 If the bases are equal, we are set. */
8860 && (base_offset
8862 use_pointer_diff)))
8865 && (base_offset
8866 = use_pointer_diff
8876 {
8882 base_offset,
8885 }
8887 }
8889 /* If the real or vector real constant CST of type TYPE has an exact
8890 inverse, return it, else return NULL. */
8892 tree
8894 {
8895 REAL_VALUE_TYPE r;
8896 tree unit_type;
8897 machine_mode mode;
8900 {
8910 {
8914 tree_vector_builder elts;
8919 {
8924 }
8927 }
8931 }
8932 }
8934 /* Mask out the tz least significant bits of X of type TYPE where
8935 tz is the number of trailing zeroes in Y. */
8936 static wide_int
8938 {
8943 }
8945 /* Return true when T is an address and is known to be nonzero.
8946 For floating point we further ensure that T is not denormal.
8947 Similar logic is present in nonzero_address in rtlanal.h.
8949 If the return value is based on the assumption that signed overflow
8950 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8951 change *STRICT_OVERFLOW_P. */
8953 static bool
8955 {
8959 /* Doing something useful for floating point would need more work. */
8965 {
8968 strict_overflow_p);
8974 strict_overflow_p);
8982 }
8985 {
8988 strict_overflow_p);
8996 strict_overflow_p);
9011 strict_overflow_p);
9015 strict_overflow_p);
9018 {
9030 }
9034 }
9036 }
9038 /* Return true when T is an address and is known to be nonzero.
9039 Handle warnings about undefined signed overflow. */
9041 bool
9043 {
9050 "determining that expression is always "
9052 WARN_STRICT_OVERFLOW_MISC);
9054 }
9056 /* Return true if T is known not to be equal to an integer W. */
9058 bool
9060 {
9062 value_range_type rtype;
9064 {
9073 {
9078 }
9083 /* If T has some known zero bits and W has any of those bits set,
9084 then T is known not to be equal to W. */
9092 }
9093 }
9095 /* Fold a binary expression of code CODE and type TYPE with operands
9096 OP0 and OP1. LOC is the location of the resulting expression.
9097 Return the folded expression if folding is successful. Otherwise,
9098 return NULL_TREE. */
9100 tree
9103 {
9118 /* Strip any conversions that don't change the mode. This is
9119 safe for every expression, except for a comparison expression
9120 because its signedness is derived from its operands. So, in
9121 the latter case, only strip conversions that don't change the
9122 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9123 preserved.
9125 Note that this is done as an internal manipulation within the
9126 constant folder, in order to find the simplest representation
9127 of the arguments so that their form can be studied. In any
9128 cases, the appropriate type conversions should be put back in
9129 the tree that will get out of the constant folder. */
9132 {
9135 }
9136 else
9137 {
9140 }
9142 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9143 constant but we can't do arithmetic on them. */
9145 {
9148 {
9152 }
9153 }
9155 /* If this is a commutative operation, and ARG0 is a constant, move it
9156 to ARG1 to reduce the number of tests below. */
9161 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9162 to ARG1 to reduce the number of tests below. */
9171 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9173 First check for cases where an arithmetic operation is applied to a
9174 compound, conditional, or comparison operation. Push the arithmetic
9175 operation inside the compound or conditional to see if any folding
9176 can then be done. Convert comparison to conditional for this purpose.
9177 The also optimizes non-constant cases that used to be done in
9178 expand_expr.
9180 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9181 one of the operands is a comparison and the other is a comparison, a
9182 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9183 code below would make the expression more complex. Change it to a
9184 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9185 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9198 {
9202 boolean_type_node,
9210 }
9214 {
9216 {
9221 tem);
9222 }
9224 {
9229 tem);
9230 }
9235 {
9241 }
9246 {
9252 }
9253 }
9256 {
9258 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9261 {
9267 }
9269 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9272 {
9273 tree base;
9274 HOST_WIDE_INT coffset;
9283 }
9288 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9294 arg1),
9296 arg0)));
9302 {
9303 /* X + (X / CST) * -CST is X % CST. */
9308 {
9317 cst0));
9318 }
9319 }
9321 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9322 one. Make sure the type is not saturating and has the signedness of
9323 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9324 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9331 {
9335 }
9338 {
9339 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9340 (plus (plus (mult) (mult)) (foo)) so that we can
9341 take advantage of the factoring cases below. */
9350 {
9356 else
9369 parg0),
9371 marg)),
9375 return
9381 parg1)));
9382 }
9383 }
9384 else
9385 {
9386 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9387 to __complex__ ( x, y ). This is not the same for SNaNs or
9388 if signed zeros are involved. */
9392 {
9399 {
9403 {
9409 }
9411 {
9417 }
9418 }
9419 }
9421 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9422 We associate floats only if the user has specified
9423 -fassociative-math. */
9427 {
9432 {
9433 tree tree0;
9436 }
9437 }
9438 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9439 We associate floats only if the user has specified
9440 -fassociative-math. */
9444 {
9449 {
9450 tree tree0;
9453 }
9454 }
9455 }
9457 bit_rotate:
9458 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9459 is a rotate of A by C1 bits. */
9460 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9461 is a rotate of A by B bits.
9462 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9463 though in this case CODE must be | and not + or ^, otherwise
9464 it doesn't return A when B is 0. */
9465 {
9467 tree rtype;
9476 /* Only create rotates in complete modes. Other cases are not
9477 expanded properly. */
9480 {
9493 {
9498 }
9503 {
9506 code0 == LSHIFT_EXPR
9509 }
9511 {
9521 {
9525 orig_tree01);
9527 }
9528 }
9532 {
9543 {
9547 orig_tree01);
9549 }
9550 }
9551 }
9552 }
9554 associate:
9555 /* In most languages, can't associate operations on floats through
9556 parentheses. Rather than remember where the parentheses were, we
9557 don't associate floats at all, unless the user has specified
9558 -fassociative-math.
9559 And, we need to make sure type is not saturating. */
9563 {
9569 /* Split both trees into variables, constants, and literals. Then
9570 associate each group together, the constants with literals,
9571 then the result with variables. This increases the chances of
9572 literals being recombined later and of generating relocatable
9573 expressions for the sum of a constant and literal. */
9581 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9585 /* With undefined overflow prefer doing association in a type
9586 which wraps on overflow, if that is one of the operand types. */
9589 {
9597 }
9599 /* With undefined overflow we can only associate constants with one
9600 variable, and constants whose association doesn't overflow. */
9603 {
9605 {
9606 /* ??? If split_tree would handle NEGATE_EXPR we could
9607 simply reject these cases and the allowed cases would
9608 be the var0/minus_var1 ones. */
9614 {
9617 }
9624 {
9627 }
9633 /* The only case we can still associate with two variables
9634 is if they cancel out. */
9638 }
9644 }
9646 /* Only do something if we found more than two objects. Otherwise,
9647 nothing has changed and we risk infinite recursion. */
9655 {
9667 {
9671 }
9673 {
9677 }
9679 /* Preserve the MINUS_EXPR if the negative part of the literal is
9680 greater than the positive part. Otherwise, the multiplicative
9681 folding code (i.e extract_muldiv) may be fooled in case
9682 unsigned constants are subtracted, like in the following
9683 example: ((X*2 + 4) - 8U)/2. */
9685 {
9689 /* But avoid ending up with only negated parts. */
9691 {
9695 }
9696 else
9697 {
9701 }
9702 }
9704 /* Don't introduce overflows through reassociation. */
9709 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9716 /* Eliminate minus_con0. */
9718 {
9725 else
9728 }
9730 /* Eliminate minus_var0. */
9732 {
9736 else
9739 }
9741 return
9744 }
9745 }
9751 /* Fold &a[i] - &a[j] to i-j. */
9756 {
9760 code
9764 }
9766 /* Further transformations are not for pointers. */
9770 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9778 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9779 __complex__ ( x, -y ). This is not the same for SNaNs or if
9780 signed zeros are involved. */
9784 {
9791 {
9795 {
9797 arg1r ? arg1r
9802 }
9804 {
9808 arg1i ? arg1i
9811 }
9812 }
9813 }
9815 /* A - B -> A + (-B) if B is easily negatable. */
9819 /* Avoid this transformation if B is a positive REAL_CST. */
9827 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9828 one. Make sure the type is not saturating and has the signedness of
9829 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9830 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9837 {
9841 }
9847 {
9848 /* Transform x * -C into -x * C if x is easily negatable. */
9863 {
9866 "occur when simplifying "
9868 WARN_STRICT_OVERFLOW_MISC);
9870 }
9872 /* Optimize z * conj(z) for integer complex numbers. */
9879 }
9880 else
9881 {
9882 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9883 This is not the same for NaNs or if signed zeros are
9884 involved. */
9890 {
9893 return
9899 return
9904 }
9906 /* Optimize z * conj(z) for floating point complex numbers.
9907 Guarded by flag_unsafe_math_optimizations as non-finite
9908 imaginary components don't produce scalar results. */
9917 }
9921 /* Canonicalize (X & C1) | C2. */
9925 {
9930 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9938 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9940 {
9943 }
9945 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9946 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9947 mode which allows further optimizations. */
9952 {
9957 {
9960 }
9961 }
9964 {
9969 }
9970 }
9972 /* See if this can be simplified into a rotate first. If that
9973 is unsuccessful continue in the association code. */
9977 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9985 /* See if this can be simplified into a rotate first. If that
9986 is unsuccessful continue in the association code. */
9990 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9995 {
9996 tree tem2;
10003 }
10004 /* Fold ~X & 1 as (X & 1) == 0. */
10008 {
10009 tree tem2;
10016 }
10017 /* Fold !X & 1 as X == 0. */
10020 {
10024 }
10026 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10027 multiple of 1 << CST. */
10029 {
10036 }
10038 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10039 bits from CST2. */
10043 {
10045 wide_int masked
10052 {
10053 /* Avoid the transform if arg1 is a mask of some
10054 mode which allows further optimizations. */
10061 }
10062 }
10064 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10065 ((A & N) + B) & M -> (A + B) & M
10066 Similarly if (N & M) == 0,
10067 ((A | N) + B) & M -> (A + B) & M
10068 and for - instead of + (or unary - instead of +)
10069 and/or ^ instead of |.
10070 If B is constant and (B & M) == 0, fold into A & M. */
10072 {
10081 {
10084 wide_int cst0;
10086 /* Now we know that arg0 is (C + D) or (C - D) or
10087 -C and arg1 (M) is == (1LL << cst) - 1.
10088 Store C into PMOP[0] and D into PMOP[1]. */
10092 {
10095 }
10102 {
10111 {
10114 }
10117 /* If C or D is of the form (A & N) where
10118 (N & M) == M, or of the form (A | N) or
10119 (A ^ N) where (N & M) == 0, replace it with A. */
10123 /* If C or D is a N where (N & M) == 0, it can be
10124 omitted (assumed 0). */
10132 }
10134 /* Only build anything new if we optimized one or both arguments
10135 above. */
10139 {
10142 {
10143 /* Perform the operations in a type that has defined
10144 overflow behavior. */
10150 }
10155 {
10163 else
10165 }
10168 else
10171 /* TEM is now the new binary +, - or unary - replacement. */
10175 }
10176 }
10177 }
10179 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10182 {
10187 return
10189 }
10194 /* Don't touch a floating-point divide by zero unless the mode
10195 of the constant can represent infinity. */
10201 /* (-A) / (-B) -> A / B */
10213 /* Fall through */
10216 /* Simplify A / (B << N) where A and B are positive and B is
10217 a power of 2, to A >> (N + log2(B)). */
10222 {
10225 {
10233 WARN_STRICT_OVERFLOW_MISC);
10239 }
10240 }
10242 /* Fall through */
10250 /* Convert -A / -B to A / B when the type is signed and overflow is
10251 undefined. */
10255 {
10258 "when distributing negation across "
10260 WARN_STRICT_OVERFLOW_MISC);
10265 }
10269 {
10272 "when distributing negation across "
10274 WARN_STRICT_OVERFLOW_MISC);
10279 }
10281 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10282 operation, EXACT_DIV_EXPR.
10284 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10285 At one time others generated faster code, it's not clear if they do
10286 after the last round to changes to the DIV code in expmed.c. */
10297 {
10301 WARN_STRICT_OVERFLOW_MISC);
10303 }
10315 {
10319 WARN_STRICT_OVERFLOW_MISC);
10321 }
10329 /* Since negative shift count is not well-defined,
10330 don't try to compute it in the compiler. */
10336 /* If we have a rotate of a bit operation with the rotate count and
10337 the second operand of the bit operation both constant,
10338 permute the two operations. */
10344 {
10352 }
10354 /* Two consecutive rotates adding up to the some integer
10355 multiple of the precision of the type can be ignored. */
10371 /* Note that the operands of this must be ints
10372 and their values must be 0 or 1.
10373 ("true" is a fixed value perhaps depending on the language.) */
10374 /* If first arg is constant zero, return it. */
10377 /* FALLTHRU */
10379 /* If either arg is constant true, drop it. */
10383 /* Preserve sequence points. */
10386 /* If second arg is constant zero, result is zero, but first arg
10387 must be evaluated. */
10390 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10391 case will be handled here. */
10395 /* !X && X is always false. */
10399 /* X && !X is always false. */
10404 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10405 means A >= Y && A != MAX, but in this case we know that
10406 A < X <= MAX. */
10410 {
10418 }
10427 /* Note that the operands of this must be ints
10428 and their values must be 0 or true.
10429 ("true" is a fixed value perhaps depending on the language.) */
10430 /* If first arg is constant true, return it. */
10433 /* FALLTHRU */
10435 /* If either arg is constant zero, drop it. */
10439 /* Preserve sequence points. */
10442 /* If second arg is constant true, result is true, but we must
10443 evaluate first arg. */
10446 /* Likewise for first arg, but note this only occurs here for
10447 TRUTH_OR_EXPR. */
10451 /* !X || X is always true. */
10455 /* X || !X is always true. */
10460 /* (X && !Y) || (!X && Y) is X ^ Y */
10463 {
10480 }
10489 /* If the second arg is constant zero, drop it. */
10492 /* If the second arg is constant true, this is a logical inversion. */
10494 {
10497 }
10498 /* Identical arguments cancel to zero. */
10502 /* !X ^ X is always true. */
10507 /* X ^ !X is always true. */
10523 /* bool_var != 1 becomes !bool_var. */
10530 /* bool_var == 0 becomes !bool_var. */
10537 /* !exp != 0 becomes !exp */
10542 /* If this is an EQ or NE comparison with zero and ARG0 is
10543 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10544 two operations, but the latter can be done in one less insn
10545 on machines that have only two-operand insns or on which a
10546 constant cannot be the first operand. */
10549 {
10554 {
10561 arg1);
10562 }
10565 {
10572 arg1);
10573 }
10574 }
10576 /* If this is an NE or EQ comparison of zero against the result of a
10577 signed MOD operation whose second operand is a power of 2, make
10578 the MOD operation unsigned since it is simpler and equivalent. */
10586 {
10596 }
10598 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10599 C1 is a valid shift constant, and C2 is a power of two, i.e.
10600 a single bit. */
10604 == INTEGER_CST
10607 {
10612 /* Check for a valid shift count. */
10614 {
10618 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10619 can be rewritten as (X & (C2 << C1)) != 0. */
10621 {
10626 }
10627 /* Otherwise, for signed (arithmetic) shifts,
10628 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10629 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10633 /* Otherwise, of unsigned (logical) shifts,
10634 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10635 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10636 else
10640 arg000);
10641 }
10642 }
10644 /* If this is a comparison of a field, we may be able to simplify it. */
10647 /* Handle the constant case even without -O
10648 to make sure the warnings are given. */
10650 {
10654 }
10656 /* Optimize comparisons of strlen vs zero to a compare of the
10657 first character of the string vs zero. To wit,
10658 strlen(ptr) == 0 => *ptr == 0
10659 strlen(ptr) != 0 => *ptr != 0
10660 Other cases should reduce to one of these two (or a constant)
10661 due to the return value of strlen being unsigned. */
10664 {
10672 {
10677 }
10678 }
10680 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10681 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10685 {
10690 {
10692 {
10695 }
10698 }
10699 }
10701 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10702 (X & C) == 0 when C is a single bit. */
10707 {
10714 arg1));
10715 }
10717 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10718 constant C is a power of two, i.e. a single bit. */
10725 {
10729 }
10731 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10732 when is C is a power of two, i.e. a single bit. */
10739 {
10745 }
10749 {
10752 }
10754 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10757 {
10765 {
10771 }
10773 {
10779 }
10781 {
10787 }
10789 {
10795 }
10796 }
10800 {
10807 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10808 operand_equal_p guarantees no side-effects so we don't need
10809 to use omit_one_operand on Z. */
10813 arg10));
10817 arg11));
10821 arg10));
10825 arg11));
10827 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10830 {
10836 }
10837 }
10839 /* Attempt to simplify equality/inequality comparisons of complex
10840 values. Only lower the comparison if the result is known or
10841 can be simplified to a single scalar comparison. */
10846 {
10851 {
10854 }
10855 else
10856 {
10859 }
10862 {
10865 }
10866 else
10867 {
10870 }
10874 {
10876 {
10881 }
10882 else
10883 {
10888 }
10889 }
10893 {
10895 {
10900 }
10901 else
10902 {
10907 }
10908 }
10909 }
10921 /* Transform comparisons of the form X +- C CMP X. */
10926 {
10931 /* (X - c) > X becomes false. */
10937 /* Likewise (X + c) < X becomes false. */
10943 /* Convert (X - c) <= X to true. */
10950 /* Convert (X + c) >= X to true. */
10956 }
10958 /* If we are comparing an ABS_EXPR with a constant, we can
10959 convert all the cases into explicit comparisons, but they may
10960 well not be faster than doing the ABS and one comparison.
10961 But ABS (X) <= C is a range comparison, which becomes a subtraction
10962 and a comparison, and is probably faster. */
10976 /* Convert ABS_EXPR<x> >= 0 to true. */
10983 {
10986 "when simplifying comparison of "
10988 WARN_STRICT_OVERFLOW_CONDITIONAL);
10991 arg0);
10992 }
10994 /* Convert ABS_EXPR<x> < 0 to false. */
10999 {
11002 "when simplifying comparison of "
11004 WARN_STRICT_OVERFLOW_CONDITIONAL);
11007 arg0);
11008 }
11010 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11011 and similarly for >= into !=. */
11021 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11022 otherwise Y might be >= # of bits in X's type and thus e.g.
11023 (unsigned char) (1 << Y) for Y 15 might be 0.
11024 If the cast is widening, then 1 << Y should have unsigned type,
11025 otherwise if Y is number of bits in the signed shift type minus 1,
11026 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11027 31 might be 0xffffffff80000000. */
11038 {
11044 }
11056 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11057 {
11069 }
11074 /* When pedantic, a compound expression can be neither an lvalue
11075 nor an integer constant expression. */
11078 /* Don't let (0, 0) be null pointer constant. */
11084 /* An ASSERT_EXPR should never be passed to fold_binary. */
11090 }
11092 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11093 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11094 of GOTO_EXPR. */
11096 static tree
11098 {
11100 {
11107 /* fall through */
11111 }
11112 }
11114 /* Return whether the sub-tree ST contains a label which is accessible from
11115 outside the sub-tree. */
11117 static bool
11119 {
11120 return
11122 }
11124 /* Fold a ternary expression of code CODE and type TYPE with operands
11125 OP0, OP1, and OP2. Return the folded expression if folding is
11126 successful. Otherwise, return NULL_TREE. */
11128 tree
11131 {
11132 tree tem;
11139 /* If this is a commutative operation, and OP0 is a constant, move it
11140 to OP1 to reduce the number of tests below. */
11149 /* Strip any conversions that don't change the mode. This is safe
11150 for every expression, except for a comparison expression because
11151 its signedness is derived from its operands. So, in the latter
11152 case, only strip conversions that don't change the signedness.
11154 Note that this is done as an internal manipulation within the
11155 constant folder, in order to find the simplest representation of
11156 the arguments so that their form can be studied. In any cases,
11157 the appropriate type conversions should be put back in the tree
11158 that will get out of the constant folder. */
11160 {
11163 }
11166 {
11169 }
11172 {
11175 }
11178 {
11182 {
11188 }
11193 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11194 so all simple results must be passed through pedantic_non_lvalue. */
11196 {
11199 /* Only optimize constant conditions when the selected branch
11200 has the same type as the COND_EXPR. This avoids optimizing
11201 away "c ? x : throw", where the throw has a void type.
11202 Avoid throwing away that operand which contains label. */
11209 }
11211 {
11216 {
11221 {
11229 }
11233 }
11234 }
11236 /* If we have A op B ? A : C, we may be able to convert this to a
11237 simpler expression, depending on the operation and the values
11238 of B and C. Signed zeros prevent all of these transformations,
11239 for reasons given above each one.
11241 Also try swapping the arguments and inverting the conditional. */
11245 {
11249 }
11254 {
11258 {
11262 }
11263 }
11265 /* If the second operand is simpler than the third, swap them
11266 since that produces better jump optimization results. */
11269 {
11271 /* See if this can be inverted. If it can't, possibly because
11272 it was a floating-point inequality comparison, don't do
11273 anything. */
11277 }
11279 /* Convert A ? 1 : 0 to simply A. */
11284 /* If we try to convert OP0 to our type, the
11285 call to fold will try to move the conversion inside
11286 a COND, which will recurse. In that case, the COND_EXPR
11287 is probably the best choice, so leave it alone. */
11291 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11292 over COND_EXPR in cases such as floating point comparisons. */
11301 arg0)));
11303 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11308 {
11309 /* sign_bit_p looks through both zero and sign extensions,
11310 but for this optimization only sign extensions are
11311 usable. */
11314 {
11317 {
11320 }
11322 }
11323 /* sign_bit_p only checks ARG1 bits within A's precision.
11324 If <sign bit of A> has wider type than A, bits outside
11325 of A's precision in <sign bit of A> need to be checked.
11326 If they are all 0, this optimization needs to be done
11327 in unsigned A's type, if they are all 1 in signed A's type,
11328 otherwise this can't be done. */
11334 {
11336 tree tem_type;
11349 {
11352 }
11354 {
11357 }
11358 else
11360 }
11363 return
11369 arg1)));
11370 }
11372 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11373 already handled above. */
11378 {
11388 op1);
11389 }
11391 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11392 is probably obsolete because the first operand should be a
11393 truth value (that's why we have the two cases above), but let's
11394 leave it in until we can confirm this for all front-ends. */
11406 /* Disable the transformations below for vectors, since
11407 fold_binary_op_with_conditional_arg may undo them immediately,
11408 yielding an infinite loop. */
11412 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11421 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11426 {
11428 /* Only perform transformation if ARG0 is easily inverted. */
11432 ? BIT_IOR_EXPR
11435 op1);
11436 }
11438 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11443 {
11445 /* Only perform transformation if ARG0 is easily inverted. */
11451 op2);
11452 }
11454 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11466 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11467 of fold_ternary on them. */
11475 {
11485 {
11490 {
11498 }
11499 }
11500 }
11502 /* On constants we can use native encode/interpret to constant
11503 fold (nearly) all BIT_FIELD_REFs. */
11507 {
11510 /* Limit us to a reasonable amount of work. To relax the
11511 other limitations we need bit-shifting of the buffer
11512 and rounding up the size. */
11516 {
11518 unsigned HOST_WIDE_INT len
11523 {
11528 }
11529 }
11530 }
11535 /* For integers we can decompose the FMA if possible. */
11547 {
11563 {
11568 /* Make sure that the perm value is in an acceptable
11569 range. */
11578 else
11586 }
11589 {
11594 }
11599 {
11604 }
11610 {
11614 }
11619 /* Some targets are deficient and fail to expand a single
11620 argument permutation while still allowing an equivalent
11621 2-argument version. */
11625 {
11628 }
11631 {
11638 }
11642 }
11646 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11649 {
11655 wide_int tem2
11659 }
11664 {
11666 unsigned HOST_WIDE_INT elsize
11669 {
11673 else
11674 {
11681 }
11682 }
11683 }
11689 }
11691 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11692 of an array (or vector). */
11694 tree
11696 {
11701 {
11704 {
11705 /* Static constructors for variably sized objects makes no sense. */
11709 }
11710 }
11721 offset_int max_index;
11726 {
11727 /* Array constructor might explicitly set index, or specify a range,
11728 or leave index NULL meaning that it is next index after previous
11729 one. */
11731 {
11734 else
11735 {
11739 }
11740 }
11741 else
11742 {
11748 }
11750 /* Do we have match? */
11754 }
11756 }
11758 /* Perform constant folding and related simplification of EXPR.
11759 The related simplifications include x*1 => x, x*0 => 0, etc.,
11760 and application of the associative law.
11761 NOP_EXPR conversions may be removed freely (as long as we
11762 are careful not to change the type of the overall expression).
11763 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11764 but we can constant-fold them if they have constant operands. */
11766 #ifdef ENABLE_FOLD_CHECKING
11767 # define fold(x) fold_1 (x)
11769 static
11770 #endif
11771 tree
11773 {
11777 tree tem;
11780 /* Return right away if a constant. */
11784 /* CALL_EXPR-like objects with variable numbers of operands are
11785 treated specially. */
11787 {
11789 {
11792 }
11794 }
11797 {
11802 {
11820 }
11821 }
11824 {
11826 {
11833 {
11838 }
11841 }
11843 /* Return a VECTOR_CST if possible. */
11845 {
11851 tree val;
11857 }
11865 }
11867 #ifdef ENABLE_FOLD_CHECKING
11868 #undef fold
11875 /* When --enable-checking=fold, compute a digest of expr before
11876 and after actual fold call to see if fold did not accidentally
11877 change original expr. */
11879 tree
11881 {
11882 tree ret;
11902 }
11904 void
11906 {
11917 }
11919 static void
11921 {
11923 }
11925 static void
11928 {
11934 recursive_label:
11944 {
11945 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
11950 }
11958 {
11959 /* Allow these fields to be modified. */
11960 tree tmp;
11969 {
11972 }
11973 }
11984 {
11987 {
12003 }
12007 {
12020 }
12037 {
12043 }
12046 {
12048 {
12051 }
12053 }
12064 {
12067 }
12077 }
12078 }
12080 /* Helper function for outputting the checksum of a tree T. When
12081 debugging with gdb, you can "define mynext" to be "next" followed
12082 by "call debug_fold_checksum (op0)", then just trace down till the
12083 outputs differ. */
12085 DEBUG_FUNCTION void
12087 {
12102 }
12104 #endif
12106 /* Fold a unary tree expression with code CODE of type TYPE with an
12107 operand OP0. LOC is the location of the resulting expression.
12108 Return a folded expression if successful. Otherwise, return a tree
12109 expression with code CODE of type TYPE with an operand OP0. */
12111 tree
12114 {
12115 tree tem;
12116 #ifdef ENABLE_FOLD_CHECKING
12125 #endif
12131 #ifdef ENABLE_FOLD_CHECKING
12138 #endif
12140 }
12142 /* Fold a binary tree expression with code CODE of type TYPE with
12143 operands OP0 and OP1. LOC is the location of the resulting
12144 expression. Return a folded expression if successful. Otherwise,
12145 return a tree expression with code CODE of type TYPE with operands
12146 OP0 and OP1. */
12148 tree
12151 MEM_STAT_DECL)
12152 {
12153 tree tem;
12154 #ifdef ENABLE_FOLD_CHECKING
12171 #endif
12177 #ifdef ENABLE_FOLD_CHECKING
12192 #endif
12194 }
12196 /* Fold a ternary tree expression with code CODE of type TYPE with
12197 operands OP0, OP1, and OP2. Return a folded expression if
12198 successful. Otherwise, return a tree expression with code CODE of
12199 type TYPE with operands OP0, OP1, and OP2. */
12201 tree
12204 {
12205 tree tem;
12206 #ifdef ENABLE_FOLD_CHECKING
12230 #endif
12237 #ifdef ENABLE_FOLD_CHECKING
12260 #endif
12262 }
12264 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12265 arguments in ARGARRAY, and a null static chain.
12266 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12267 of type TYPE from the given operands as constructed by build_call_array. */
12269 tree
12272 {
12273 tree tem;
12274 #ifdef ENABLE_FOLD_CHECKING
12293 #endif
12299 #ifdef ENABLE_FOLD_CHECKING
12315 #endif
12317 }
12319 /* Perform constant folding and related simplification of initializer
12320 expression EXPR. These behave identically to "fold_buildN" but ignore
12321 potential run-time traps and exceptions that fold must preserve. */
12323 #define START_FOLD_INIT \
12324 int saved_signaling_nans = flag_signaling_nans;\
12325 int saved_trapping_math = flag_trapping_math;\
12326 int saved_rounding_math = flag_rounding_math;\
12327 int saved_trapv = flag_trapv;\
12328 int saved_folding_initializer = folding_initializer;\
12329 flag_signaling_nans = 0;\
12330 flag_trapping_math = 0;\
12331 flag_rounding_math = 0;\
12332 flag_trapv = 0;\
12333 folding_initializer = 1;
12335 #define END_FOLD_INIT \
12336 flag_signaling_nans = saved_signaling_nans;\
12337 flag_trapping_math = saved_trapping_math;\
12338 flag_rounding_math = saved_rounding_math;\
12339 flag_trapv = saved_trapv;\
12340 folding_initializer = saved_folding_initializer;
12342 tree
12345 {
12346 tree result;
12347 START_FOLD_INIT;
12351 END_FOLD_INIT;
12353 }
12355 tree
12358 {
12359 tree result;
12360 START_FOLD_INIT;
12364 END_FOLD_INIT;
12366 }
12368 tree
12371 {
12372 tree result;
12373 START_FOLD_INIT;
12377 END_FOLD_INIT;
12379 }
12381 #undef START_FOLD_INIT
12382 #undef END_FOLD_INIT
12384 /* Determine if first argument is a multiple of second argument. Return 0 if
12385 it is not, or we cannot easily determined it to be.
12387 An example of the sort of thing we care about (at this point; this routine
12388 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12389 fold cases do now) is discovering that
12391 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12393 is a multiple of
12395 SAVE_EXPR (J * 8)
12397 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12399 This code also handles discovering that
12401 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12403 is a multiple of 8 so we don't have to worry about dealing with a
12404 possible remainder.
12406 Note that we *look* inside a SAVE_EXPR only to determine how it was
12407 calculated; it is not safe for fold to do much of anything else with the
12408 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12409 at run time. For example, the latter example above *cannot* be implemented
12410 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12411 evaluation time of the original SAVE_EXPR is not necessarily the same at
12412 the time the new expression is evaluated. The only optimization of this
12413 sort that would be valid is changing
12415 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12417 divided by 8 to
12419 SAVE_EXPR (I) * SAVE_EXPR (J)
12421 (where the same SAVE_EXPR (J) is used in the original and the
12422 transformed version). */
12424 int
12426 {
12437 {
12439 /* Bitwise and provides a power of two multiple. If the mask is
12440 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12443 /* FALLTHRU */
12450 /* It is impossible to prove if op0 - op1 is multiple of bottom
12451 precisely, so be conservative here checking if both op0 and op1
12452 are multiple of bottom. Note we check the second operand first
12453 since it's usually simpler. */
12458 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12459 as op0 - 3 if the expression has unsigned type. For example,
12460 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12470 {
12472 /* const_binop may not detect overflow correctly,
12473 so check for it explicitly here. */
12478 size_one_node,
12479 op1)))
12482 }
12486 /* Can't handle conversions from non-integral or wider integral type. */
12492 /* fall through */
12509 SIGNED);
12515 {
12518 /* Check for special cases to see if top is defined as multiple
12519 of bottom:
12521 top = (X & ~(bottom - 1) ; bottom is power of 2
12523 or
12525 Y = X % bottom
12526 top = X - Y. */
12545 }
12547 /* fall through */
12551 }
12552 }
12554 #define tree_expr_nonnegative_warnv_p(X, Y) \
12557 #define RECURSE(X) \
12558 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12560 /* Return true if CODE or TYPE is known to be non-negative. */
12562 static bool
12564 {
12567 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12568 have a signed:1 type (where the value is -1 and 0). */
12571 }
12573 /* Return true if (CODE OP0) is known to be non-negative. If the return
12574 value is based on the assumption that signed overflow is undefined,
12575 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12576 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12578 bool
12581 {
12586 {
12588 /* We can't return 1 if flag_wrapv is set because
12589 ABS_EXPR<INT_MIN> = INT_MIN. */
12593 {
12596 }
12604 CASE_CONVERT:
12605 {
12610 {
12614 {
12618 }
12619 }
12621 {
12627 }
12628 }
12633 }
12635 /* We don't know sign of `t', so be conservative and return false. */
12637 }
12639 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12640 value is based on the assumption that signed overflow is undefined,
12641 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12642 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12644 bool
12648 {
12653 {
12659 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12660 both unsigned and at least 2 bits shorter than the result. */
12664 {
12669 {
12673 }
12674 }
12679 {
12680 /* x * x is always non-negative for floating point x
12681 or without overflow. */
12684 {
12689 }
12690 }
12692 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12693 both unsigned and their total bits is shorter than the result. */
12697 {
12716 {
12726 }
12727 }
12754 }
12756 /* We don't know sign of `t', so be conservative and return false. */
12758 }
12760 /* Return true if T is known to be non-negative. If the return
12761 value is based on the assumption that signed overflow is undefined,
12762 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12763 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12765 bool
12767 {
12772 {
12786 /* Limit the depth of recursion to avoid quadratic behavior.
12787 This is expected to catch almost all occurrences in practice.
12788 If this code misses important cases that unbounded recursion
12789 would not, passes that need this information could be revised
12790 to provide it through dataflow propagation. */
12798 }
12799 }
12801 /* Return true if T is known to be non-negative. If the return
12802 value is based on the assumption that signed overflow is undefined,
12803 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12804 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12806 bool
12809 {
12811 {
12812 CASE_CFN_ACOS:
12813 CASE_CFN_ACOSH:
12814 CASE_CFN_CABS:
12815 CASE_CFN_COSH:
12816 CASE_CFN_ERFC:
12817 CASE_CFN_EXP:
12818 CASE_CFN_EXP10:
12819 CASE_CFN_EXP2:
12820 CASE_CFN_FABS:
12821 CASE_CFN_FDIM:
12822 CASE_CFN_HYPOT:
12823 CASE_CFN_POW10:
12824 CASE_CFN_FFS:
12825 CASE_CFN_PARITY:
12826 CASE_CFN_POPCOUNT:
12827 CASE_CFN_CLZ:
12828 CASE_CFN_CLRSB:
12831 /* Always true. */
12834 CASE_CFN_SQRT:
12835 CASE_CFN_SQRT_FN:
12836 /* sqrt(-0.0) is -0.0. */
12841 CASE_CFN_ASINH:
12842 CASE_CFN_ATAN:
12843 CASE_CFN_ATANH:
12844 CASE_CFN_CBRT:
12845 CASE_CFN_CEIL:
12846 CASE_CFN_ERF:
12847 CASE_CFN_EXPM1:
12848 CASE_CFN_FLOOR:
12849 CASE_CFN_FMOD:
12850 CASE_CFN_FREXP:
12851 CASE_CFN_ICEIL:
12852 CASE_CFN_IFLOOR:
12853 CASE_CFN_IRINT:
12854 CASE_CFN_IROUND:
12855 CASE_CFN_LCEIL:
12856 CASE_CFN_LDEXP:
12857 CASE_CFN_LFLOOR:
12858 CASE_CFN_LLCEIL:
12859 CASE_CFN_LLFLOOR:
12860 CASE_CFN_LLRINT:
12861 CASE_CFN_LLROUND:
12862 CASE_CFN_LRINT:
12863 CASE_CFN_LROUND:
12864 CASE_CFN_MODF:
12865 CASE_CFN_NEARBYINT:
12866 CASE_CFN_RINT:
12867 CASE_CFN_ROUND:
12868 CASE_CFN_SCALB:
12869 CASE_CFN_SCALBLN:
12870 CASE_CFN_SCALBN:
12871 CASE_CFN_SIGNBIT:
12872 CASE_CFN_SIGNIFICAND:
12873 CASE_CFN_SINH:
12874 CASE_CFN_TANH:
12875 CASE_CFN_TRUNC:
12876 /* True if the 1st argument is nonnegative. */
12879 CASE_CFN_FMAX:
12880 CASE_CFN_FMAX_FN:
12881 /* True if the 1st OR 2nd arguments are nonnegative. */
12884 CASE_CFN_FMIN:
12885 CASE_CFN_FMIN_FN:
12886 /* True if the 1st AND 2nd arguments are nonnegative. */
12889 CASE_CFN_COPYSIGN:
12890 CASE_CFN_COPYSIGN_FN:
12891 /* True if the 2nd argument is nonnegative. */
12894 CASE_CFN_POWI:
12895 /* True if the 1st argument is nonnegative or the second
12896 argument is an even integer. */
12902 CASE_CFN_POW:
12903 /* True if the 1st argument is nonnegative or the second
12904 argument is an even integer valued real. */
12906 {
12907 REAL_VALUE_TYPE c;
12908 HOST_WIDE_INT n;
12913 {
12914 REAL_VALUE_TYPE cint;
12918 }
12919 }
12924 }
12926 }
12928 /* Return true if T is known to be non-negative. If the return
12929 value is based on the assumption that signed overflow is undefined,
12930 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12931 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12933 static bool
12935 {
12941 {
12943 {
12947 /* If the initializer is non-void, then it's a normal expression
12948 that will be assigned to the slot. */
12952 /* Otherwise, the initializer sets the slot in some way. One common
12953 way is an assignment statement at the end of the initializer. */
12955 {
12963 else
12965 }
12971 }
12974 {
12980 arg0,
12981 arg1,
12983 }
12996 }
12997 }
12999 #undef RECURSE
13000 #undef tree_expr_nonnegative_warnv_p
13002 /* Return true if T is known to be non-negative. If the return
13003 value is based on the assumption that signed overflow is undefined,
13004 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13005 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13007 bool
13009 {
13016 {
13038 }
13041 {
13067 }
13068 }
13070 /* Return true if `t' is known to be non-negative. Handle warnings
13071 about undefined signed overflow. */
13073 bool
13075 {
13082 "determining that expression is always "
13084 WARN_STRICT_OVERFLOW_MISC);
13086 }
13089 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13090 For floating point we further ensure that T is not denormal.
13091 Similar logic is present in nonzero_address in rtlanal.h.
13093 If the return value is based on the assumption that signed overflow
13094 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13095 change *STRICT_OVERFLOW_P. */
13097 bool
13100 {
13102 {
13105 strict_overflow_p);
13108 {
13114 strict_overflow_p));
13115 }
13120 strict_overflow_p);
13124 }
13127 }
13129 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13130 For floating point we further ensure that T is not denormal.
13131 Similar logic is present in nonzero_address in rtlanal.h.
13133 If the return value is based on the assumption that signed overflow
13134 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13135 change *STRICT_OVERFLOW_P. */
13137 bool
13139 tree type,
13140 tree op0,
13142 {
13145 {
13149 {
13150 /* With the presence of negative values it is hard
13151 to say something. */
13158 /* One of operands must be positive and the other non-negative. */
13159 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13160 overflows, on a twos-complement machine the sum of two
13161 nonnegative numbers can never be zero. */
13163 strict_overflow_p)
13165 strict_overflow_p));
13166 }
13171 {
13173 strict_overflow_p)
13175 strict_overflow_p))
13176 {
13179 }
13180 }
13189 {
13192 }
13199 {
13203 /* When both operands are nonzero, then MAX must be too. */
13205 strict_overflow_p))
13208 /* MAX where operand 0 is positive is positive. */
13210 strict_overflow_p);
13211 }
13212 /* MAX where operand 1 is positive is positive. */
13217 {
13221 }
13226 strict_overflow_p)
13228 strict_overflow_p));
13232 }
13235 }
13237 /* Return true when T is an address and is known to be nonzero.
13238 For floating point we further ensure that T is not denormal.
13239 Similar logic is present in nonzero_address in rtlanal.h.
13241 If the return value is based on the assumption that signed overflow
13242 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13243 change *STRICT_OVERFLOW_P. */
13245 bool
13247 {
13250 {
13255 {
13267 /* For objects in symbol table check if we know they are non-zero.
13268 Don't do anything for variables and functions before symtab is built;
13269 it is quite possible that they will be declared weak later. */
13274 /* Constants are never weak. */
13279 }
13287 {
13291 }
13301 }
13303 }
13305 #define integer_valued_real_p(X) \
13308 #define RECURSE(X) \
13309 ((integer_valued_real_p) (X, depth + 1))
13311 /* Return true if the floating point result of (CODE OP0) has an
13312 integer value. We also allow +Inf, -Inf and NaN to be considered
13313 integer values. Return false for signaling NaN.
13315 DEPTH is the current nesting depth of the query. */
13317 bool
13319 {
13321 {
13328 CASE_CONVERT:
13329 {
13336 }
13340 }
13342 }
13344 /* Return true if the floating point result of (CODE OP0 OP1) has an
13345 integer value. We also allow +Inf, -Inf and NaN to be considered
13346 integer values. Return false for signaling NaN.
13348 DEPTH is the current nesting depth of the query. */
13350 bool
13352 {
13354 {
13364 }
13366 }
13368 /* Return true if the floating point result of calling FNDECL with arguments
13369 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13370 considered integer values. Return false for signaling NaN. If FNDECL
13371 takes fewer than 2 arguments, the remaining ARGn are null.
13373 DEPTH is the current nesting depth of the query. */
13375 bool
13377 {
13379 {
13380 CASE_CFN_CEIL:
13381 CASE_CFN_FLOOR:
13382 CASE_CFN_NEARBYINT:
13383 CASE_CFN_RINT:
13384 CASE_CFN_ROUND:
13385 CASE_CFN_TRUNC:
13388 CASE_CFN_FMIN:
13389 CASE_CFN_FMIN_FN:
13390 CASE_CFN_FMAX:
13391 CASE_CFN_FMAX_FN:
13396 }
13398 }
13400 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13401 has an integer value. We also allow +Inf, -Inf and NaN to be
13402 considered integer values. Return false for signaling NaN.
13404 DEPTH is the current nesting depth of the query. */
13406 bool
13408 {
13410 {
13418 /* Limit the depth of recursion to avoid quadratic behavior.
13419 This is expected to catch almost all occurrences in practice.
13420 If this code misses important cases that unbounded recursion
13421 would not, passes that need this information could be revised
13422 to provide it through dataflow propagation. */
13426 depth));
13430 }
13432 }
13434 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13435 has an integer value. We also allow +Inf, -Inf and NaN to be
13436 considered integer values. Return false for signaling NaN.
13438 DEPTH is the current nesting depth of the query. */
13440 static bool
13442 {
13444 {
13455 }
13457 }
13459 #undef RECURSE
13460 #undef integer_valued_real_p
13462 /* Return true if the floating point expression T has an integer value.
13463 We also allow +Inf, -Inf and NaN to be considered integer values.
13464 Return false for signaling NaN.
13466 DEPTH is the current nesting depth of the query. */
13468 bool
13470 {
13476 {
13492 }
13495 {
13501 {
13510 }
13514 }
13515 }
13517 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13518 attempt to fold the expression to a constant without modifying TYPE,
13519 OP0 or OP1.
13521 If the expression could be simplified to a constant, then return
13522 the constant. If the expression would not be simplified to a
13523 constant, then return NULL_TREE. */
13525 tree
13527 {
13530 }
13532 /* Given the components of a unary expression CODE, TYPE and OP0,
13533 attempt to fold the expression to a constant without modifying
13534 TYPE or OP0.
13536 If the expression could be simplified to a constant, then return
13537 the constant. If the expression would not be simplified to a
13538 constant, then return NULL_TREE. */
13540 tree
13542 {
13545 }
13547 /* If EXP represents referencing an element in a constant string
13548 (either via pointer arithmetic or array indexing), return the
13549 tree representing the value accessed, otherwise return NULL. */
13551 tree
13553 {
13557 {
13559 tree index;
13560 tree string;
13565 else
13566 {
13570 /* Optimize the special-case of a zero lower bound.
13572 We convert the low_bound to sizetype to avoid some problems
13573 with constant folding. (E.g. suppose the lower bound is 1,
13574 and its mode is QI. Without the conversion,l (ARRAY
13575 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13576 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13582 }
13584 scalar_int_mode char_mode;
13596 }
13598 }
13600 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13601 an integer constant, real, or fixed-point constant.
13603 TYPE is the type of the result. */
13605 static tree
13607 {
13611 {
13613 {
13620 }
13627 {
13628 FIXED_VALUE_TYPE f;
13633 /* Propagate overflow flags. */
13637 }
13641 }
13644 }
13646 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13647 an integer constant or real constant.
13649 TYPE is the type of the result. */
13651 tree
13653 {
13657 {
13659 {
13660 /* If the value is unsigned or non-negative, then the absolute value
13661 is the same as the ordinary value. */
13665 /* If the value is negative, then the absolute value is
13666 its negation. */
13667 else
13668 {
13673 }
13674 }
13680 else
13686 }
13689 }
13691 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13692 constant. TYPE is the type of the result. */
13694 static tree
13696 {
13700 }
13702 /* Given CODE, a relational operator, the target type, TYPE and two
13703 constant operands OP0 and OP1, return the result of the
13704 relational operation. If the result is not a compile time
13705 constant, then return NULL_TREE. */
13707 static tree
13709 {
13712 /* From here on, the only cases we handle are when the result is
13713 known to be a constant. */
13716 {
13720 /* Handle the cases where either operand is a NaN. */
13722 {
13724 {
13752 }
13755 }
13758 }
13761 {
13765 }
13767 /* Handle equality/inequality of complex constants. */
13769 {
13780 else
13782 }
13785 {
13787 {
13788 /* Have vector comparison with scalar boolean result. */
13792 {
13800 }
13802 }
13803 tree_vector_builder elts;
13808 {
13821 }
13824 }
13826 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13828 To compute GT, swap the arguments and do LT.
13829 To compute GE, do LT and invert the result.
13830 To compute LE, swap the arguments, do LT and invert the result.
13831 To compute NE, do EQ and invert the result.
13833 Therefore, the code below must handle only EQ and LT. */
13836 {
13839 }
13841 /* Note that it is safe to invert for real values here because we
13842 have already handled the one case that it matters. */
13846 {
13849 }
13851 /* Compute a result for LT or EQ if args permit;
13852 Otherwise return T. */
13854 {
13857 else
13859 }
13860 else
13866 }
13868 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13869 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13870 itself. */
13872 tree
13874 {
13875 /* If the expression does not have side effects then we don't have to wrap
13876 it with a cleanup point expression. */
13880 /* If the expression is a return, check to see if the expression inside the
13881 return has no side effects or the right hand side of the modify expression
13882 inside the return. If either don't have side effects set we don't need to
13883 wrap the expression in a cleanup point expression. Note we don't check the
13884 left hand side of the modify because it should always be a return decl. */
13886 {
13893 }
13896 }
13898 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13899 of an indirection through OP0, or NULL_TREE if no simplification is
13900 possible. */
13902 tree
13904 {
13906 tree subtype;
13915 {
13918 /* *&CONST_DECL -> to the value of the const decl. */
13921 /* *&p => p; make sure to handle *&"str"[cst] here. */
13923 {
13927 else
13929 }
13930 /* *(foo *)&fooarray => fooarray[0] */
13933 && (!in_gimple_form
13935 {
13945 }
13946 /* *(foo *)&complexfoo => __real__ complexfoo */
13950 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
13953 {
13957 }
13958 }
13962 {
13968 {
13969 tree op00type;
13973 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
13976 {
13978 unsigned HOST_WIDE_INT max_offset
13983 {
13990 }
13991 }
13992 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13995 {
13999 }
14000 /* ((foo *)&fooarray)[1] => fooarray[1] */
14003 {
14010 offset_int remainder;
14013 {
14018 }
14019 }
14020 }
14021 }
14023 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14026 && (!in_gimple_form
14028 {
14029 tree type_domain;
14039 NULL_TREE);
14040 }
14043 }
14045 /* Builds an expression for an indirection through T, simplifying some
14046 cases. */
14048 tree
14050 {
14058 }
14060 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14062 tree
14064 {
14069 else
14071 }
14073 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14074 whose result is ignored. The type of the returned tree need not be
14075 the same as the original expression. */
14077 tree
14079 {
14085 {
14096 else
14102 {
14118 }
14123 }
14124 }
14126 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14128 tree
14130 {
14136 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14137 have to do anything. Only do this when we are not given a const,
14138 because in that case, this check is more expensive than just
14139 doing it. */
14141 {
14146 }
14148 /* If divisor is a power of two, simplify this to bit manipulation. */
14150 {
14152 {
14166 }
14167 else
14168 {
14169 tree t;
14175 }
14176 }
14177 else
14178 {
14183 }
14186 }
14188 /* Likewise, but round down. */
14190 tree
14192 {
14199 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14200 have to do anything. Only do this when we are not given a const,
14201 because in that case, this check is more expensive than just
14202 doing it. */
14204 {
14209 }
14211 /* If divisor is a power of two, simplify this to bit manipulation. */
14213 {
14214 tree t;
14218 }
14219 else
14220 {
14225 }
14228 }
14230 /* Returns the pointer to the base of the object addressed by EXP and
14231 extracts the information about the offset of the access, storing it
14232 to PBITPOS and POFFSET. */
14234 static tree
14237 {
14238 tree core;
14239 machine_mode mode;
14241 HOST_WIDE_INT bitsize;
14245 {
14250 }
14252 {
14258 {
14263 {
14266 }
14267 }
14268 }
14269 else
14270 {
14274 }
14277 }
14279 /* Returns true if addresses of E1 and E2 differ by a constant, false
14280 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14282 bool
14284 {
14298 {
14308 }
14310 {
14311 /* If only one of the offsets is non-constant, the difference cannot
14312 be a constant. */
14314 }
14315 else
14320 }
14322 /* Return OFF converted to a pointer offset type suitable as offset for
14323 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14324 tree
14326 {
14328 }
14330 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14331 tree
14333 {
14336 }
14338 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14339 tree
14341 {
14344 }
14346 /* Return a char pointer for a C string if it is a string constant
14347 or sum of string constant and integer constant. We only support
14348 string constants properly terminated with '\0' character.
14349 If STRLEN is a valid pointer, length (including terminating character)
14350 of returned string is stored to the argument. */
14354 {
14355 tree offset_node;
14366 {
14369 else
14371 }
14376 /* Support only properly null-terminated strings. */
14385 }
14387 #if CHECKING_P
14391 /* Helper functions for writing tests of folding trees. */
14393 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14395 static void
14397 tree constant)
14398 {
14400 }
14402 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14403 wrapping WRAPPED_EXPR. */
14405 static void
14407 tree wrapped_expr)
14408 {
14413 }
14415 /* Verify that various arithmetic binary operations are folded
14416 correctly. */
14418 static void
14420 {
14426 /* Addition. */
14427 /* 1 <-- (0 + 1) */
14429 one);
14431 one);
14433 /* (nonlvalue)x <-- (x + 0) */
14435 x);
14437 /* Subtraction. */
14438 /* 0 <-- (x - x) */
14440 zero);
14442 x);
14444 /* Multiplication. */
14445 /* 0 <-- (x * 0) */
14447 zero);
14449 /* (nonlvalue)x <-- (x * 1) */
14451 x);
14452 }
14454 /* Verify that various binary operations on vectors are folded
14455 correctly. */
14457 static void
14459 {
14465 /* Verify equality tests that return a scalar boolean result. */
14471 }
14473 /* Run all of the selftests within this file. */
14475 void
14477 {
14480 }