| blob | 1b098d9f4c91af002aeacd433ad92ffda0afb9ab |
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 {
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 {
2990 {
2994 }
2996 }
3000 flags)
3002 flags));
3013 flags | OEP_ADDRESS_OF
3016 /* In GIMPLE empty constructors are allowed in initializers of
3017 aggregates. */
3021 }
3026 /* Define macros to test an operand from arg0 and arg1 for equality and a
3027 variant that allows null and views null as being different from any
3028 non-null value. In the latter case, if either is null, the both
3029 must be; otherwise, do the normal comparison. */
3030 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3031 TREE_OPERAND (arg1, N), flags)
3033 #define OP_SAME_WITH_NULL(N) \
3034 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3035 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3038 {
3040 /* Two conversions are equal only if signedness and modes match. */
3042 {
3043 CASE_CONVERT:
3051 }
3061 /* For commutative ops, allow the other order. */
3069 /* If either of the pointer (or reference) expressions we are
3070 dereferencing contain a side effect, these cannot be equal,
3071 but their addresses can be. */
3078 {
3088 /* Require the same offset. */
3094 /* Fallthru. */
3102 {
3103 /* Require equal access sizes */
3109 flags)))
3111 /* Verify that access happens in similar types. */
3114 /* Verify that accesses are TBAA compatible. */
3123 /* Verify that alignment is compatible. */
3127 }
3130 /* TARGET_MEM_REF require equal extra operands. */
3141 /* Compare the array index by value if it is constant first as we
3142 may have different types but same value here. */
3148 /* Compare low bound and element size as with OEP_ADDRESS_OF
3149 we have to account for the offset of the ref. */
3154 array_ref_low_bound
3158 array_ref_element_size
3160 flags))));
3163 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3164 may be NULL when we're called to compare MEM_EXPRs. */
3179 }
3183 {
3185 /* Be sure we pass right ADDRESS_OF flag. */
3203 /* The multiplcation operands are commutative. */
3204 /* FALLTHRU */
3212 /* Otherwise take into account this is a commutative operation. */
3225 /* BIT_INSERT_EXPR has an implict operand as the type precision
3226 of op1. Need to check to make sure they are the same. */
3232 /* FALLTHRU */
3257 }
3261 {
3265 /* If not both CALL_EXPRs are either internal or normal function
3266 functions, then they are not equal. */
3269 {
3270 /* If the CALL_EXPRs call different internal functions, then they
3271 are not equal. */
3274 }
3275 else
3276 {
3277 /* If the CALL_EXPRs call different functions, then they are not
3278 equal. */
3280 flags))
3282 }
3284 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3285 {
3289 else
3293 }
3295 /* Now see if all the arguments are the same. */
3296 {
3307 /* If we get here and both argument lists are exhausted
3308 then the CALL_EXPRs are equal. */
3310 }
3313 }
3316 /* Consider __builtin_sqrt equal to sqrt. */
3324 {
3325 /* In GIMPLE constructors are used only to build vectors from
3326 elements. Individual elements in the constructor must be
3327 indexed in increasing order and form an initial sequence.
3329 We make no effort to compare constructors in generic.
3330 (see sem_variable::equals in ipa-icf which can do so for
3331 constants). */
3336 /* Be sure that vectors constructed have the same representation.
3337 We only tested element precision and modes to match.
3338 Vectors may be BLKmode and thus also check that the number of
3339 parts match. */
3352 {
3357 /* In GIMPLE the indexes can be either NULL or matching i.
3358 Double check this so we won't get false
3359 positives for GENERIC. */
3367 }
3369 }
3372 {
3373 /* Compare the STATEMENT_LISTs. */
3379 {
3380 /* The lists don't have the same number of statements. */
3386 OEP_LEXICOGRAPHIC))
3388 }
3389 }
3394 {
3401 }
3405 }
3407 #undef OP_SAME
3408 #undef OP_SAME_WITH_NULL
3409 }
3410 \f
3411 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3412 with a different signedness or a narrower precision. */
3414 static bool
3416 {
3424 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3425 and see if the inner values are the same. This removes any
3426 signedness comparison, which doesn't matter here. */
3434 /* Discard a single widening conversion from ARG1 and see if the inner
3435 value is the same as ARG0. */
3444 }
3445 \f
3446 /* See if ARG is an expression that is either a comparison or is performing
3447 arithmetic on comparisons. The comparisons must only be comparing
3448 two different values, which will be stored in *CVAL1 and *CVAL2; if
3449 they are nonzero it means that some operands have already been found.
3450 No variables may be used anywhere else in the expression except in the
3451 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3452 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3454 If this is true, return 1. Otherwise, return zero. */
3456 static int
3458 {
3462 /* We can handle some of the tcc_expression cases here. */
3472 {
3473 /* If we've already found a CVAL1 or CVAL2, this expression is
3474 two complex to handle. */
3480 }
3483 {
3506 /* First see if we can handle the first operand, then the second. For
3507 the second operand, we know *CVAL1 can't be zero. It must be that
3508 one side of the comparison is each of the values; test for the
3509 case where this isn't true by failing if the two operands
3510 are the same. */
3519 ;
3523 ;
3524 else
3528 ;
3532 ;
3533 else
3540 }
3541 }
3542 \f
3543 /* ARG is a tree that is known to contain just arithmetic operations and
3544 comparisons. Evaluate the operations in the tree substituting NEW0 for
3545 any occurrence of OLD0 as an operand of a comparison and likewise for
3546 NEW1 and OLD1. */
3548 static tree
3551 {
3556 /* We can handle some of the tcc_expression cases here. */
3564 {
3579 {
3598 }
3599 /* Fall through - ??? */
3602 {
3606 /* We need to check both for exact equality and tree equality. The
3607 former will be true if the operand has a side-effect. In that
3608 case, we know the operand occurred exactly once. */
3621 }
3625 }
3626 }
3627 \f
3628 /* Return a tree for the case when the result of an expression is RESULT
3629 converted to TYPE and OMITTED was previously an operand of the expression
3630 but is now not needed (e.g., we folded OMITTED * 0).
3632 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3633 the conversion of RESULT to TYPE. */
3635 tree
3637 {
3640 /* If the resulting operand is an empty statement, just return the omitted
3641 statement casted to void. */
3651 }
3653 /* Return a tree for the case when the result of an expression is RESULT
3654 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3655 of the expression but are now not needed.
3657 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3658 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3659 evaluated before OMITTED2. Otherwise, if neither has side effects,
3660 just do the conversion of RESULT to TYPE. */
3662 tree
3665 {
3674 }
3676 \f
3677 /* Return a simplified tree node for the truth-negation of ARG. This
3678 never alters ARG itself. We assume that ARG is an operation that
3679 returns a truth value (0 or 1).
3681 FIXME: one would think we would fold the result, but it causes
3682 problems with the dominator optimizer. */
3684 static tree
3686 {
3691 /* If this is a comparison, we can simply invert it, except for
3692 floating-point non-equality comparisons, in which case we just
3693 enclose a TRUTH_NOT_EXPR around what we have. */
3696 {
3699 && flag_trapping_math
3713 }
3716 {
3735 /* Here we can invert either operand. We invert the first operand
3736 unless the second operand is a TRUTH_NOT_EXPR in which case our
3737 result is the XOR of the first operand with the inside of the
3738 negation of the second operand. */
3743 else
3766 {
3773 /* A COND_EXPR may have a throw as one operand, which
3774 then has void type. Just leave void operands
3775 as they are. */
3781 }
3793 CASE_CONVERT:
3797 /* fall through */
3819 }
3820 }
3822 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3823 assume that ARG is an operation that returns a truth value (0 or 1
3824 for scalars, 0 or -1 for vectors). Return the folded expression if
3825 folding is successful. Otherwise, return NULL_TREE. */
3827 static tree
3829 {
3832 ? BIT_NOT_EXPR
3835 }
3837 /* Return a simplified tree node for the truth-negation of ARG. This
3838 never alters ARG itself. We assume that ARG is an operation that
3839 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3841 tree
3843 {
3849 ? BIT_NOT_EXPR
3852 }
3853 \f
3854 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3855 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3856 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3857 is the original memory reference used to preserve the alias set of
3858 the access. */
3860 static tree
3864 {
3867 /* Attempt not to lose the access path if possible. */
3869 {
3871 machine_mode nmode;
3873 tree noffset;
3883 && !reversep
3884 && !nreversep
3886 {
3889 }
3890 }
3899 {
3906 }
3921 }
3923 /* Optimize a bit-field compare.
3925 There are two cases: First is a compare against a constant and the
3926 second is a comparison of two items where the fields are at the same
3927 bit position relative to the start of a chunk (byte, halfword, word)
3928 large enough to contain it. In these cases we can avoid the shift
3929 implicit in bitfield extractions.
3931 For constants, we emit a compare of the shifted constant with the
3932 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3933 compared. For two fields at the same position, we do the ANDs with the
3934 similar mask and compare the result of the ANDs.
3936 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3937 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3938 are the left and right operands of the comparison, respectively.
3940 If the optimization described above can be done, we return the resulting
3941 tree. Otherwise we return zero. */
3943 static tree
3946 {
3949 tree unsigned_type;
3952 scalar_int_mode nmode;
3957 tree mask;
3958 tree offset;
3960 /* Get all the information about the extractions being done. If the bit size
3961 if the same as the size of the underlying object, we aren't doing an
3962 extraction at all and so can do nothing. We also don't want to
3963 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3964 then will no longer be able to replace it. */
3973 else
3974 {
3975 /* If this is not a constant, we can only do something if bit positions,
3976 sizes, signedness and storage order are the same. */
3977 rinner
3985 }
3987 /* Honor the C++ memory model and mimic what RTL expansion does. */
3991 {
3995 }
3997 /* See if we can find a mode to refer to this field. We should be able to,
3998 but fail if we can't. */
4006 /* Set signed and unsigned types of the precision of this mode for the
4007 shifts below. */
4010 /* Compute the bit position and size for the new reference and our offset
4011 within it. If the new reference is the same size as the original, we
4012 won't optimize anything, so return zero. */
4022 /* Make the mask to be used against the extracted field. */
4029 {
4033 /* If not comparing with constant, just rework the comparison
4034 and return. */
4042 }
4044 /* Otherwise, we are handling the constant case. See if the constant is too
4045 big for the field. Warn and return a tree for 0 (false) if so. We do
4046 this not only for its own sake, but to avoid having to test for this
4047 error case below. If we didn't, we might generate wrong code.
4049 For unsigned fields, the constant shifted right by the field length should
4050 be all zero. For signed fields, the high-order bits should agree with
4051 the sign bit. */
4054 {
4056 {
4060 }
4061 }
4062 else
4063 {
4066 {
4070 }
4071 }
4076 /* Single-bit compares should always be against zero. */
4078 {
4081 }
4083 /* Make a new bitfield reference, shift the constant over the
4084 appropriate number of bits and mask it with the computed mask
4085 (in case this was a signed field). If we changed it, make a new one. */
4093 mask);
4098 }
4099 \f
4100 /* Subroutine for fold_truth_andor_1: decode a field reference.
4102 If EXP is a comparison reference, we return the innermost reference.
4104 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4105 set to the starting bit number.
4107 If the innermost field can be completely contained in a mode-sized
4108 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4110 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4111 otherwise it is not changed.
4113 *PUNSIGNEDP is set to the signedness of the field.
4115 *PREVERSEP is set to the storage order of the field.
4117 *PMASK is set to the mask used. This is either contained in a
4118 BIT_AND_EXPR or derived from the width of the field.
4120 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4122 Return 0 if this is not a component reference or is one that we can't
4123 do anything with. */
4125 static tree
4130 {
4135 tree unsigned_type;
4138 /* All the optimizations using this function assume integer fields.
4139 There are problems with FP fields since the type_for_size call
4140 below can fail for, e.g., XFmode. */
4144 /* We are interested in the bare arrangement of bits, so strip everything
4145 that doesn't affect the machine mode. However, record the type of the
4146 outermost expression if it may matter below. */
4153 {
4159 }
4166 /* Reject out-of-bound accesses (PR79731). */
4174 /* If the number of bits in the reference is the same as the bitsize of
4175 the outer type, then the outer type gives the signedness. Otherwise
4176 (in case of a small bitfield) the signedness is unchanged. */
4180 /* Compute the mask to access the bitfield. */
4189 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4197 }
4199 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4200 bit positions and MASK is SIGNED. */
4202 static int
4204 {
4208 /* If this function returns true when the type of the mask is
4209 UNSIGNED, then there will be errors. In particular see
4210 gcc.c-torture/execute/990326-1.c. There does not appear to be
4211 any documentation paper trail as to why this is so. But the pre
4212 wide-int worked with that restriction and it has been preserved
4213 here. */
4218 }
4220 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4221 represents the sign bit of EXP's type. If EXP represents a sign
4222 or zero extension, also test VAL against the unextended type.
4223 The return value is the (sub)expression whose sign bit is VAL,
4224 or NULL_TREE otherwise. */
4226 tree
4228 {
4230 tree t;
4232 /* Tree EXP must have an integral type. */
4237 /* Tree VAL must be an integer constant. */
4246 /* Handle extension from a narrower type. */
4252 }
4254 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4255 to be evaluated unconditionally. */
4257 static int
4259 {
4260 /* Strip any conversions that don't change the machine mode. */
4269 /* Don't regard global variables as simple. They may be
4270 allocated in ways unknown to the compiler (shared memory,
4271 #pragma weak, etc). */
4274 /* Weakrefs are not safe to be read, since they can be NULL.
4275 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4276 have DECL_WEAK flag set. */
4278 /* Loading a static variable is unduly expensive, but global
4279 registers aren't expensive. */
4281 }
4283 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4284 to be evaluated unconditionally.
4285 I addition to simple_operand_p, we assume that comparisons, conversions,
4286 and logic-not operations are simple, if their operands are simple, too. */
4288 static bool
4290 {
4310 }
4312 \f
4313 /* The following functions are subroutines to fold_range_test and allow it to
4314 try to change a logical combination of comparisons into a range test.
4316 For example, both
4317 X == 2 || X == 3 || X == 4 || X == 5
4318 and
4319 X >= 2 && X <= 5
4320 are converted to
4321 (unsigned) (X - 2) <= 3
4323 We describe each set of comparisons as being either inside or outside
4324 a range, using a variable named like IN_P, and then describe the
4325 range with a lower and upper bound. If one of the bounds is omitted,
4326 it represents either the highest or lowest value of the type.
4328 In the comments below, we represent a range by two numbers in brackets
4329 preceded by a "+" to designate being inside that range, or a "-" to
4330 designate being outside that range, so the condition can be inverted by
4331 flipping the prefix. An omitted bound is represented by a "-". For
4332 example, "- [-, 10]" means being outside the range starting at the lowest
4333 possible value and ending at 10, in other words, being greater than 10.
4334 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4335 always false.
4337 We set up things so that the missing bounds are handled in a consistent
4338 manner so neither a missing bound nor "true" and "false" need to be
4339 handled using a special case. */
4341 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4342 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4343 and UPPER1_P are nonzero if the respective argument is an upper bound
4344 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4345 must be specified for a comparison. ARG1 will be converted to ARG0's
4346 type if both are specified. */
4348 static tree
4351 {
4352 tree tem;
4356 /* If neither arg represents infinity, do the normal operation.
4357 Else, if not a comparison, return infinity. Else handle the special
4358 comparison rules. Note that most of the cases below won't occur, but
4359 are handled for consistency. */
4362 {
4367 }
4372 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4373 for neither. In real maths, we cannot assume open ended ranges are
4374 the same. But, this is computer arithmetic, where numbers are finite.
4375 We can therefore make the transformation of any unbounded range with
4376 the value Z, Z being greater than any representable number. This permits
4377 us to treat unbounded ranges as equal. */
4381 {
4402 }
4405 }
4406 \f
4407 /* Helper routine for make_range. Perform one step for it, return
4408 new expression if the loop should continue or NULL_TREE if it should
4409 stop. */
4411 tree
4415 {
4421 {
4423 /* We can only do something if the range is testing for zero. */
4432 /* We can only do something if the range is testing for zero
4433 and if the second operand is an integer constant. Note that
4434 saying something is "in" the range we make is done by
4435 complementing IN_P since it will set in the initial case of
4436 being not equal to zero; "out" is leaving it alone. */
4443 {
4464 }
4466 /* If this is an unsigned comparison, we also know that EXP is
4467 greater than or equal to zero. We base the range tests we make
4468 on that fact, so we record it here so we can parse existing
4469 range tests. We test arg0_type since often the return type
4470 of, e.g. EQ_EXPR, is boolean. */
4472 {
4476 NULL_TREE))
4481 /* If the high bound is missing, but we have a nonzero low
4482 bound, reverse the range so it goes from zero to the low bound
4483 minus 1. */
4485 {
4490 }
4491 }
4499 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4500 low and high are non-NULL, then normalize will DTRT. */
4503 {
4508 }
4510 /* (-x) IN [a,b] -> x in [-b, -a] */
4522 /* ~ X -> -X - 1 */
4531 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4532 move a constant to the other side. */
4537 /* If EXP is signed, any overflow in the computation is undefined,
4538 so we don't worry about it so long as our computations on
4539 the bounds don't overflow. For unsigned, overflow is defined
4540 and this is exactly the right thing. */
4552 normalize:
4553 /* Check for an unsigned range which has wrapped around the maximum
4554 value thus making n_high < n_low, and normalize it. */
4556 {
4562 /* If the range is of the form +/- [ x+1, x ], we won't
4563 be able to normalize it. But then, it represents the
4564 whole range or the empty set, so make it
4565 +/- [ -, - ]. */
4569 else
4571 }
4572 else
4580 CASE_CONVERT:
4598 /* If we're converting arg0 from an unsigned type, to exp,
4599 a signed type, we will be doing the comparison as unsigned.
4600 The tests above have already verified that LOW and HIGH
4601 are both positive.
4603 So we have to ensure that we will handle large unsigned
4604 values the same way that the current signed bounds treat
4605 negative values. */
4608 {
4609 tree high_positive;
4610 tree equiv_type;
4611 /* For fixed-point modes, we need to pass the saturating flag
4612 as the 2nd parameter. */
4614 equiv_type
4617 else
4618 equiv_type
4621 /* A range without an upper bound is, naturally, unbounded.
4622 Since convert would have cropped a very large value, use
4623 the max value for the destination type. */
4624 high_positive
4631 high_positive),
4634 /* If the low bound is specified, "and" the range with the
4635 range for which the original unsigned value will be
4636 positive. */
4638 {
4641 integer_zero_node),
4642 high_positive))
4646 }
4647 else
4648 {
4649 /* Otherwise, "or" the range with the range of the input
4650 that will be interpreted as negative. */
4653 integer_zero_node),
4654 high_positive))
4658 }
4659 }
4668 }
4669 }
4671 /* Given EXP, a logical expression, set the range it is testing into
4672 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4673 actually being tested. *PLOW and *PHIGH will be made of the same
4674 type as the returned expression. If EXP is not a comparison, we
4675 will most likely not be returning a useful value and range. Set
4676 *STRICT_OVERFLOW_P to true if the return value is only valid
4677 because signed overflow is undefined; otherwise, do not change
4678 *STRICT_OVERFLOW_P. */
4680 tree
4683 {
4691 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4692 and see if we can refine the range. Some of the cases below may not
4693 happen, but it doesn't seem worth worrying about this. We "continue"
4694 the outer loop when we've changed something; otherwise we "break"
4695 the switch, which will "break" the while. */
4701 {
4707 {
4715 }
4724 }
4726 /* If EXP is a constant, we can evaluate whether this is true or false. */
4728 {
4735 }
4739 }
4741 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4742 a bitwise check i.e. when
4743 LOW == 0xXX...X00...0
4744 HIGH == 0xXX...X11...1
4745 Return corresponding mask in MASK and stem in VALUE. */
4747 static bool
4750 {
4773 }
4774 \f
4775 /* Helper routine for build_range_check and match.pd. Return the type to
4776 perform the check or NULL if it shouldn't be optimized. */
4778 tree
4780 {
4781 /* First make sure that arithmetics in this type is valid, then make sure
4782 that it wraps around. */
4788 {
4791 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4792 for the type in question, as we rely on this here. */
4802 else
4804 }
4806 }
4808 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4809 type, TYPE, return an expression to test if EXP is in (or out of, depending
4810 on IN_P) the range. Return 0 if the test couldn't be created. */
4812 tree
4815 {
4818 /* Disable this optimization for function pointer expressions
4819 on targets that require function pointer canonicalization. */
4826 {
4832 }
4854 value);
4857 {
4859 {
4863 }
4865 }
4867 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4869 {
4873 {
4875 {
4878 etype
4880 else
4883 }
4886 }
4887 }
4889 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4890 This requires wrap-around arithmetics for the type of the expression. */
4910 }
4911 \f
4912 /* Return the predecessor of VAL in its type, handling the infinite case. */
4914 static tree
4916 {
4922 else
4925 }
4927 /* Return the successor of VAL in its type, handling the infinite case. */
4929 static tree
4931 {
4937 else
4940 }
4942 /* Given two ranges, see if we can merge them into one. Return 1 if we
4943 can, 0 if we can't. Set the output range into the specified parameters. */
4945 bool
4948 {
4952 tree tem;
4962 /* Make range 0 be the range that starts first, or ends last if they
4963 start at the same value. Swap them if it isn't. */
4966 || (lowequal
4969 {
4973 }
4975 /* Now flag two cases, whether the ranges are disjoint or whether the
4976 second range is totally subsumed in the first. Note that the tests
4977 below are simplified by the ones above. */
4983 /* We now have four cases, depending on whether we are including or
4984 excluding the two ranges. */
4986 {
4987 /* If they don't overlap, the result is false. If the second range
4988 is a subset it is the result. Otherwise, the range is from the start
4989 of the second to the end of the first. */
4994 else
4996 }
4999 {
5000 /* If they don't overlap, the result is the first range. If they are
5001 equal, the result is false. If the second range is a subset of the
5002 first, and the ranges begin at the same place, we go from just after
5003 the end of the second range to the end of the first. If the second
5004 range is not a subset of the first, or if it is a subset and both
5005 ranges end at the same place, the range starts at the start of the
5006 first range and ends just before the second range.
5007 Otherwise, we can't describe this as a single range. */
5013 {
5018 {
5019 /* We are in the weird situation where high0 > high1 but
5020 high1 has no successor. Punt. */
5022 }
5023 }
5025 {
5030 {
5031 /* low0 < low1 but low1 has no predecessor. Punt. */
5033 }
5034 }
5035 else
5037 }
5040 {
5041 /* If they don't overlap, the result is the second range. If the second
5042 is a subset of the first, the result is false. Otherwise,
5043 the range starts just after the first range and ends at the
5044 end of the second. */
5049 else
5050 {
5055 {
5056 /* high1 > high0 but high0 has no successor. Punt. */
5058 }
5059 }
5060 }
5062 else
5063 {
5064 /* The case where we are excluding both ranges. Here the complex case
5065 is if they don't overlap. In that case, the only time we have a
5066 range is if they are adjacent. If the second is a subset of the
5067 first, the result is the first. Otherwise, the range to exclude
5068 starts at the beginning of the first range and ends at the end of the
5069 second. */
5071 {
5076 else
5077 {
5078 /* Canonicalize - [min, x] into - [-, x]. */
5081 {
5086 /* FALLTHROUGH */
5099 }
5101 /* Canonicalize - [x, max] into - [x, -]. */
5104 {
5109 /* FALLTHROUGH */
5125 }
5127 /* The ranges might be also adjacent between the maximum and
5128 minimum values of the given type. For
5129 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5130 return + [x + 1, y - 1]. */
5132 {
5139 }
5140 else
5142 }
5143 }
5146 else
5148 }
5152 }
5153 \f
5155 /* Subroutine of fold, looking inside expressions of the form
5156 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5157 of the COND_EXPR. This function is being used also to optimize
5158 A op B ? C : A, by reversing the comparison first.
5160 Return a folded expression whose code is not a COND_EXPR
5161 anymore, or NULL_TREE if no folding opportunity is found. */
5163 static tree
5166 {
5171 tree tem;
5176 /* If we have A op 0 ? A : -A, consider applying the following
5177 transformations:
5179 A == 0? A : -A same as -A
5180 A != 0? A : -A same as A
5181 A >= 0? A : -A same as abs (A)
5182 A > 0? A : -A same as abs (A)
5183 A <= 0? A : -A same as -abs (A)
5184 A < 0? A : -A same as -abs (A)
5186 None of these transformations work for modes with signed
5187 zeros. If A is +/-0, the first two transformations will
5188 change the sign of the result (from +0 to -0, or vice
5189 versa). The last four will fix the sign of the result,
5190 even though the original expressions could be positive or
5191 negative, depending on the sign of A.
5193 Note that all these transformations are correct if A is
5194 NaN, since the two alternatives (A and -A) are also NaNs. */
5201 /* In the case that A is of the form X-Y, '-A' (arg2) may
5202 have already been folded to Y-X, check for that. */
5210 {
5222 /* Fall through. */
5233 /* FALLTHRU */
5243 }
5245 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5246 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5247 both transformations are correct when A is NaN: A != 0
5248 is then true, and A == 0 is false. */
5252 {
5257 }
5259 /* Try some transformations of A op B ? A : B.
5261 A == B? A : B same as B
5262 A != B? A : B same as A
5263 A >= B? A : B same as max (A, B)
5264 A > B? A : B same as max (B, A)
5265 A <= B? A : B same as min (A, B)
5266 A < B? A : B same as min (B, A)
5268 As above, these transformations don't work in the presence
5269 of signed zeros. For example, if A and B are zeros of
5270 opposite sign, the first two transformations will change
5271 the sign of the result. In the last four, the original
5272 expressions give different results for (A=+0, B=-0) and
5273 (A=-0, B=+0), but the transformed expressions do not.
5275 The first two transformations are correct if either A or B
5276 is a NaN. In the first transformation, the condition will
5277 be false, and B will indeed be chosen. In the case of the
5278 second transformation, the condition A != B will be true,
5279 and A will be chosen.
5281 The conversions to max() and min() are not correct if B is
5282 a number and A is not. The conditions in the original
5283 expressions will be false, so all four give B. The min()
5284 and max() versions would give a NaN instead. */
5287 /* Avoid these transformations if the COND_EXPR may be used
5288 as an lvalue in the C++ front-end. PR c++/19199. */
5289 && (in_gimple_form
5295 {
5301 {
5310 /* In C++ a ?: expression can be an lvalue, so put the
5311 operand which will be used if they are equal first
5312 so that we can convert this back to the
5313 corresponding COND_EXPR. */
5315 {
5323 }
5330 {
5338 }
5351 }
5352 }
5355 }
5358 \f
5359 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5360 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5361 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5362 false) >= 2)
5363 #endif
5365 /* EXP is some logical combination of boolean tests. See if we can
5366 merge it into some range test. Return the new tree if so. */
5368 static tree
5371 {
5387 /* If this is an OR operation, invert both sides; we will invert
5388 again at the end. */
5392 /* If both expressions are the same, if we can merge the ranges, and we
5393 can build the range test, return it or it inverted. If one of the
5394 ranges is always true or always false, consider it to be the same
5395 expression as the other. */
5403 {
5407 }
5409 /* On machines where the branch cost is expensive, if this is a
5410 short-circuited branch and the underlying object on both sides
5411 is the same, make a non-short-circuit operation. */
5413 && !flag_sanitize_coverage
5418 {
5419 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5420 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5421 which cases we can't do this. */
5429 {
5438 {
5441 WARN_STRICT_OVERFLOW_COMPARISON);
5445 }
5446 }
5447 }
5450 }
5451 \f
5452 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5453 bit value. Arrange things so the extra bits will be set to zero if and
5454 only if C is signed-extended to its full width. If MASK is nonzero,
5455 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5457 static tree
5459 {
5462 tree temp;
5467 /* We work by getting just the sign bit into the low-order bit, then
5468 into the high-order bit, then sign-extend. We then XOR that value
5469 with C. */
5473 /* We must use a signed type in order to get an arithmetic right shift.
5474 However, we must also avoid introducing accidental overflows, so that
5475 a subsequent call to integer_zerop will work. Hence we must
5476 do the type conversion here. At this point, the constant is either
5477 zero or one, and the conversion to a signed type can never overflow.
5478 We could get an overflow if this conversion is done anywhere else. */
5487 /* If necessary, convert the type back to match the type of C. */
5492 }
5493 \f
5494 /* For an expression that has the form
5495 (A && B) || ~B
5496 or
5497 (A || B) && ~B,
5498 we can drop one of the inner expressions and simplify to
5499 A || ~B
5500 or
5501 A && ~B
5502 LOC is the location of the resulting expression. OP is the inner
5503 logical operation; the left-hand side in the examples above, while CMPOP
5504 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5505 removing a condition that guards another, as in
5506 (A != NULL && A->...) || A == NULL
5507 which we must not transform. If RHS_ONLY is true, only eliminate the
5508 right-most operand of the inner logical operation. */
5510 static tree
5513 {
5531 {
5534 {
5537 }
5538 }
5540 {
5543 {
5546 }
5547 }
5562 }
5564 /* Find ways of folding logical expressions of LHS and RHS:
5565 Try to merge two comparisons to the same innermost item.
5566 Look for range tests like "ch >= '0' && ch <= '9'".
5567 Look for combinations of simple terms on machines with expensive branches
5568 and evaluate the RHS unconditionally.
5570 For example, if we have p->a == 2 && p->b == 4 and we can make an
5571 object large enough to span both A and B, we can do this with a comparison
5572 against the object ANDed with the a mask.
5574 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5575 operations to do this with one comparison.
5577 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5578 function and the one above.
5580 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5581 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5583 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5584 two operands.
5586 We return the simplified tree or 0 if no optimization is possible. */
5588 static tree
5591 {
5592 /* If this is the "or" of two comparisons, we can do something if
5593 the comparisons are NE_EXPR. If this is the "and", we can do something
5594 if the comparisons are EQ_EXPR. I.e.,
5595 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5597 WANTED_CODE is this operation code. For single bit fields, we can
5598 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5599 comparison for one-bit fields. */
5620 /* Start by getting the comparison codes. Fail if anything is volatile.
5621 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5622 it were surrounded with a NE_EXPR. */
5631 {
5635 }
5638 {
5642 }
5653 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5656 {
5659 {
5664 }
5667 {
5673 }
5674 }
5679 /* If the RHS can be evaluated unconditionally and its operands are
5680 simple, it wins to evaluate the RHS unconditionally on machines
5681 with expensive branches. In this case, this isn't a comparison
5682 that can be merged. */
5689 {
5690 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5701 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5711 }
5713 /* See if the comparisons can be merged. Then get all the parameters for
5714 each side. */
5739 /* It must be true that the inner operation on the lhs of each
5740 comparison must be the same if we are to be able to do anything.
5741 Then see if we have constants. If not, the same must be true for
5742 the rhs's. */
5751 {
5754 }
5759 else
5762 /* If either comparison code is not correct for our logical operation,
5763 fail. However, we can convert a one-bit comparison against zero into
5764 the opposite comparison against that bit being set in the field. */
5768 {
5770 {
5771 /* Make the left operand unsigned, since we are only interested
5772 in the value of one bit. Otherwise we are doing the wrong
5773 thing below. */
5776 }
5777 else
5779 }
5781 /* This is analogous to the code for l_const above. */
5783 {
5785 {
5788 }
5789 else
5791 }
5793 /* See if we can find a mode that contains both fields being compared on
5794 the left. If we can't, fail. Otherwise, update all constants and masks
5795 to be relative to a field of that size. */
5809 {
5812 }
5820 {
5827 {
5831 }
5832 }
5834 {
5841 {
5845 }
5846 }
5848 /* If the right sides are not constant, do the same for it. Also,
5849 disallow this optimization if a size or signedness mismatch occurs
5850 between the left and right sides. */
5852 {
5855 /* Make sure the two fields on the right
5856 correspond to the left without being swapped. */
5873 {
5876 }
5885 /* Make a mask that corresponds to both fields being compared.
5886 Do this for both items being compared. If the operands are the
5887 same size and the bits being compared are in the same position
5888 then we can do this by masking both and comparing the masked
5889 results. */
5896 {
5910 }
5912 /* There is still another way we can do something: If both pairs of
5913 fields being compared are adjacent, we may be able to make a wider
5914 field containing them both.
5916 Note that we still must mask the lhs/rhs expressions. Furthermore,
5917 the mask must be shifted to account for the shift done by
5918 make_bit_field_ref. */
5927 {
5928 tree type;
5944 /* Convert to the smaller type before masking out unwanted bits. */
5947 {
5949 {
5953 }
5955 {
5959 }
5960 }
5969 }
5972 }
5974 /* Handle the case of comparisons with constants. If there is something in
5975 common between the masks, those bits of the constants must be the same.
5976 If not, the condition is always false. Test for this to avoid generating
5977 incorrect code below. */
5982 {
5984 {
5987 }
5988 else
5989 {
5992 }
5993 }
5998 /* Construct the expression we will return. First get the component
5999 reference we will make. Unless the mask is all ones the width of
6000 that field, perform the mask operation. Then compare with the
6001 merged constant. */
6012 }
6013 \f
6014 /* T is an integer expression that is being multiplied, divided, or taken a
6015 modulus (CODE says which and what kind of divide or modulus) by a
6016 constant C. See if we can eliminate that operation by folding it with
6017 other operations already in T. WIDE_TYPE, if non-null, is a type that
6018 should be used for the computation if wider than our type.
6020 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6021 (X * 2) + (Y * 4). We must, however, be assured that either the original
6022 expression would not overflow or that overflow is undefined for the type
6023 in the language in question.
6025 If we return a non-null expression, it is an equivalent form of the
6026 original computation, but need not be in the original type.
6028 We set *STRICT_OVERFLOW_P to true if the return values depends on
6029 signed overflow being undefined. Otherwise we do not change
6030 *STRICT_OVERFLOW_P. */
6032 static tree
6035 {
6036 /* To avoid exponential search depth, refuse to allow recursion past
6037 three levels. Beyond that (1) it's highly unlikely that we'll find
6038 something interesting and (2) we've probably processed it before
6039 when we built the inner expression. */
6042 tree ret;
6047 depth++;
6049 depth--;
6052 }
6054 static tree
6057 {
6069 /* Don't deal with constants of zero here; they confuse the code below. */
6079 /* Note that we need not handle conditional operations here since fold
6080 already handles those cases. So just do arithmetic here. */
6082 {
6084 /* For a constant, we can always simplify if we are a multiply
6085 or (for divide and modulus) if it is a multiple of our constant. */
6089 {
6092 /* If the multiplication overflowed, we lost information on it.
6093 See PR68142 and PR69845. */
6097 }
6101 /* If op0 is an expression ... */
6107 /* ... and has wrapping overflow, and its type is smaller
6108 than ctype, then we cannot pass through as widening. */
6113 /* ... or this is a truncation (t is narrower than op0),
6114 then we cannot pass through this narrowing. */
6117 /* ... or signedness changes for division or modulus,
6118 then we cannot pass through this conversion. */
6122 /* ... or has undefined overflow while the converted to
6123 type has not, we cannot do the operation in the inner type
6124 as that would introduce undefined overflow. */
6130 /* Pass the constant down and see if we can make a simplification. If
6131 we can, replace this expression with the inner simplification for
6132 possible later conversion to our or some other type. */
6137 code == MULT_EXPR
6139 strict_overflow_p))))
6144 /* If widening the type changes it from signed to unsigned, then we
6145 must avoid building ABS_EXPR itself as unsigned. */
6147 {
6151 {
6154 }
6156 }
6157 /* If the constant is negative, we cannot simplify this. */
6160 /* FALLTHROUGH */
6162 /* For division and modulus, type can't be unsigned, as e.g.
6163 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6164 For signed types, even with wrapping overflow, this is fine. */
6173 /* If widening the type changes the signedness, then we can't perform
6174 this optimization as that changes the result. */
6178 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6184 {
6191 }
6195 /* If the second operand is constant, this is a multiplication
6196 or floor division, by a power of two, so we can treat it that
6197 way unless the multiplier or divisor overflows. Signed
6198 left-shift overflow is implementation-defined rather than
6199 undefined in C90, so do not convert signed left shift into
6200 multiplication. */
6203 /* const_binop may not detect overflow correctly,
6204 so check for it explicitly here. */
6209 size_one_node,
6210 op1)))
6214 ctype,
6216 t1),
6221 /* See if we can eliminate the operation on both sides. If we can, we
6222 can return a new PLUS or MINUS. If we can't, the only remaining
6223 cases where we can do anything are if the second operand is a
6224 constant. */
6231 /* If not multiplication, we can only do this if both operands
6232 are divisible by c. */
6235 {
6240 }
6242 /* If this was a subtraction, negate OP1 and set it to be an addition.
6243 This simplifies the logic below. */
6245 {
6247 /* If OP1 was not easily negatable, the constant may be OP0. */
6249 {
6252 }
6253 }
6258 /* If either OP1 or C are negative, this optimization is not safe for
6259 some of the division and remainder types while for others we need
6260 to change the code. */
6262 {
6270 }
6272 /* If it's a multiply or a division/modulus operation of a multiple
6273 of our constant, do the operation and verify it doesn't overflow. */
6277 {
6280 /* We allow the constant to overflow with wrapping semantics. */
6284 }
6285 else
6288 /* If we have an unsigned type, we cannot widen the operation since it
6289 will change the result if the original computation overflowed. */
6293 /* The last case is if we are a multiply. In that case, we can
6294 apply the distributive law to commute the multiply and addition
6295 if the multiplication of the constants doesn't overflow
6296 and overflow is defined. With undefined overflow
6297 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6303 op1);
6308 /* We have a special case here if we are doing something like
6309 (C * 8) % 4 since we know that's zero. */
6312 /* If the multiplication can overflow we cannot optimize this. */
6317 {
6320 }
6322 /* ... fall through ... */
6326 /* If we can extract our operation from the LHS, do so and return a
6327 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6328 do something only if the second operand is a constant. */
6344 /* If these are the same operation types, we can associate them
6345 assuming no overflow. */
6347 {
6362 }
6364 /* If these operations "cancel" each other, we have the main
6365 optimizations of this pass, which occur when either constant is a
6366 multiple of the other, in which case we replace this with either an
6367 operation or CODE or TCODE.
6369 If we have an unsigned type, we cannot do this since it will change
6370 the result if the original computation overflowed. */
6377 {
6380 {
6387 }
6390 {
6397 }
6398 }
6403 }
6406 }
6407 \f
6408 /* Return a node which has the indicated constant VALUE (either 0 or
6409 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6410 and is of the indicated TYPE. */
6412 tree
6414 {
6423 else
6425 }
6428 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6429 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6430 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6431 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6432 COND is the first argument to CODE; otherwise (as in the example
6433 given here), it is the second argument. TYPE is the type of the
6434 original expression. Return NULL_TREE if no simplification is
6435 possible. */
6437 static tree
6442 {
6452 {
6456 /* If this operand throws an expression, then it does not make
6457 sense to try to perform a logical or arithmetic operation
6458 involving it. */
6463 }
6466 {
6471 }
6472 else
6473 /* Detect the case of mixing vector and scalar types - bail out. */
6479 /* This transformation is only worthwhile if we don't have to wrap ARG
6480 in a SAVE_EXPR and the operation can be simplified without recursing
6481 on at least one of the branches once its pushed inside the COND_EXPR. */
6490 {
6494 else
6496 }
6498 {
6502 else
6504 }
6506 /* Check that we have simplified at least one of the branches. */
6511 }
6513 \f
6514 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6516 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6517 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6518 ADDEND is the same as X.
6520 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6521 and finite. The problematic cases are when X is zero, and its mode
6522 has signed zeros. In the case of rounding towards -infinity,
6523 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6524 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6526 bool
6528 {
6532 /* Don't allow the fold with -fsignaling-nans. */
6536 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6540 /* In a vector or complex, we would need to check the sign of all zeros. */
6544 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6548 /* The mode has signed zeros, and we have to honor their sign.
6549 In this situation, there is only one case we can return true for.
6550 X - 0 is the same as X unless rounding towards -infinity is
6551 supported. */
6553 }
6555 /* Subroutine of match.pd that optimizes comparisons of a division by
6556 a nonzero integer constant against an integer constant, i.e.
6557 X/C1 op C2.
6559 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6560 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6562 enum tree_code
6565 {
6570 /* We have to do this the hard way to detect unsigned overflow.
6571 prod = int_const_binop (MULT_EXPR, c1, c2); */
6577 {
6581 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6584 }
6586 {
6589 {
6608 }
6609 }
6610 else
6611 {
6612 /* A negative divisor reverses the relational operators. */
6617 {
6636 }
6637 }
6650 }
6653 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6654 equality/inequality test, then return a simplified form of the test
6655 using a sign testing. Otherwise return NULL. TYPE is the desired
6656 result type. */
6658 static tree
6661 tree result_type)
6662 {
6663 /* If this is testing a single bit, we can optimize the test. */
6667 {
6668 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6669 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6673 /* This is only a win if casting to a signed type is cheap,
6674 i.e. when arg00's type is not a partial mode. */
6676 {
6679 result_type,
6682 }
6683 }
6686 }
6688 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6689 equality/inequality test, then return a simplified form of
6690 the test using shifts and logical operations. Otherwise return
6691 NULL. TYPE is the desired result type. */
6693 tree
6696 {
6697 /* If this is testing a single bit, we can optimize the test. */
6701 {
6710 /* First, see if we can fold the single bit test into a sign-bit
6711 test. */
6713 result_type);
6717 /* Otherwise we have (A & C) != 0 where C is a single bit,
6718 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6719 Similarly for (A & C) == 0. */
6721 /* If INNER is a right shift of a constant and it plus BITNUM does
6722 not overflow, adjust BITNUM and INNER. */
6728 {
6731 }
6733 /* If we are going to be able to omit the AND below, we must do our
6734 operations as unsigned. If we must use the AND, we have a choice.
6735 Normally unsigned is faster, but for some machines signed is. */
6753 /* Put the AND last so it can combine with more things. */
6756 /* Make sure to return the proper type. */
6760 }
6762 }
6764 /* Test whether it is preferable two swap two operands, ARG0 and
6765 ARG1, for example because ARG0 is an integer constant and ARG1
6766 isn't. */
6768 bool
6770 {
6784 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6785 for commutative and comparison operators. Ensuring a canonical
6786 form allows the optimizers to find additional redundancies without
6787 having to explicitly check for both orderings. */
6793 /* Put SSA_NAMEs last. */
6799 /* Put variables last. */
6806 }
6809 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6810 means A >= Y && A != MAX, but in this case we know that
6811 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6813 static tree
6815 {
6822 else
6831 {
6834 }
6836 {
6839 }
6840 else
6847 {
6848 /* Convert the pointer types into integer before taking the difference. */
6852 }
6853 else
6860 }
6862 /* Fold a sum or difference of at least one multiplication.
6863 Returns the folded tree or NULL if no simplification could be made. */
6865 static tree
6868 {
6872 /* (A * C) +- (B * C) -> (A+-B) * C.
6873 (A * C) +- A -> A * (C+-1).
6874 We are most concerned about the case where C is a constant,
6875 but other combinations show up during loop reduction. Since
6876 it is not difficult, try all four possibilities. */
6879 {
6882 }
6884 {
6887 }
6888 else
6889 {
6890 /* We cannot generate constant 1 for fract. */
6895 }
6897 {
6900 }
6902 {
6904 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
6905 the purpose of this canonicalization. */
6909 {
6912 }
6913 else
6915 }
6916 else
6917 {
6918 /* We cannot generate constant 1 for fract. */
6923 }
6926 /* Prefer factoring a common non-constant. */
6936 /* No identical multiplicands; see if we can find a common
6937 power-of-two factor in non-power-of-two multiplies. This
6938 can help in multi-dimensional array access. */
6941 {
6944 tree maybe_same;
6948 /* Move min of absolute values to int11. */
6950 {
6955 }
6956 else
6960 /* The remainder should not be a constant, otherwise we
6961 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
6962 increased the number of multiplications necessary. */
6964 {
6972 }
6973 }
6980 /* We are neither factoring zero nor minus one. */
6988 /* Same may be zero and thus the operation 'code' may overflow. Likewise
6989 same may be minus one and thus the multiplication may overflow. Perform
6990 the operations in an unsigned type. */
6995 /* If the sum evaluated to a constant that is not -INF the multiplication
6996 cannot overflow. */
7006 }
7008 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7009 specified by EXPR into the buffer PTR of length LEN bytes.
7010 Return the number of bytes placed in the buffer, or zero
7011 upon failure. */
7013 static int
7015 {
7027 /* Dry run. */
7033 {
7035 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7036 number of bytes. */
7040 {
7047 else
7049 }
7050 else
7054 }
7056 }
7059 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7060 specified by EXPR into the buffer PTR of length LEN bytes.
7061 Return the number of bytes placed in the buffer, or zero
7062 upon failure. */
7064 static int
7066 {
7070 FIXED_VALUE_TYPE value;
7085 }
7088 /* Subroutine of native_encode_expr. Encode the REAL_CST
7089 specified by EXPR into the buffer PTR of length LEN bytes.
7090 Return the number of bytes placed in the buffer, or zero
7091 upon failure. */
7093 static int
7095 {
7101 /* There are always 32 bits in each long, no matter the size of
7102 the hosts long. We handle floating point representations with
7103 up to 192 bits. */
7112 /* Dry run. */
7121 {
7126 {
7133 else
7135 }
7136 else
7137 {
7140 {
7141 /* Reverse bytes within each long, or within the entire float
7142 if it's smaller than a long (for HFmode). */
7145 }
7146 }
7151 }
7153 }
7155 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7156 specified by EXPR into the buffer PTR of length LEN bytes.
7157 Return the number of bytes placed in the buffer, or zero
7158 upon failure. */
7160 static int
7162 {
7164 tree part;
7178 }
7181 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7182 specified by EXPR into the buffer PTR of length LEN bytes.
7183 Return the number of bytes placed in the buffer, or zero
7184 upon failure. */
7186 static int
7188 {
7198 {
7200 {
7203 }
7214 }
7216 }
7219 /* Subroutine of native_encode_expr. Encode the STRING_CST
7220 specified by EXPR into the buffer PTR of length LEN bytes.
7221 Return the number of bytes placed in the buffer, or zero
7222 upon failure. */
7224 static int
7226 {
7229 /* Wide-char strings are encoded in target byte-order so native
7230 encoding them is trivial. */
7245 {
7248 {
7251 }
7254 }
7255 else
7258 }
7261 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7262 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7263 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7264 anything, just do a dry run. If OFF is not -1 then start
7265 the encoding at byte offset OFF and encode at most LEN bytes.
7266 Return the number of bytes placed in the buffer, or zero upon failure. */
7268 int
7270 {
7271 /* We don't support starting at negative offset and -1 is special. */
7276 {
7297 }
7298 }
7301 /* Subroutine of native_interpret_expr. Interpret the contents of
7302 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7303 If the buffer cannot be interpreted, return NULL_TREE. */
7305 static tree
7307 {
7317 }
7320 /* Subroutine of native_interpret_expr. Interpret the contents of
7321 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7322 If the buffer cannot be interpreted, return NULL_TREE. */
7324 static tree
7326 {
7329 double_int result;
7330 FIXED_VALUE_TYPE fixed_value;
7340 }
7343 /* Subroutine of native_interpret_expr. Interpret the contents of
7344 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7345 If the buffer cannot be interpreted, return NULL_TREE. */
7347 static tree
7349 {
7353 /* There are always 32 bits in each long, no matter the size of
7354 the hosts long. We handle floating point representations with
7355 up to 192 bits. */
7356 REAL_VALUE_TYPE r;
7366 {
7367 /* Both OFFSET and BYTE index within a long;
7368 bitpos indexes the whole float. */
7371 {
7378 else
7380 }
7381 else
7382 {
7385 {
7386 /* Reverse bytes within each long, or within the entire float
7387 if it's smaller than a long (for HFmode). */
7390 }
7391 }
7395 }
7399 }
7402 /* Subroutine of native_interpret_expr. Interpret the contents of
7403 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7404 If the buffer cannot be interpreted, return NULL_TREE. */
7406 static tree
7408 {
7423 }
7426 /* Subroutine of native_interpret_expr. Interpret the contents of
7427 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7428 If the buffer cannot be interpreted, return NULL_TREE. */
7430 static tree
7432 {
7444 {
7449 }
7451 }
7454 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7455 the buffer PTR of length LEN as a constant of type TYPE. For
7456 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7457 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7458 return NULL_TREE. */
7460 tree
7462 {
7464 {
7486 }
7487 }
7489 /* Returns true if we can interpret the contents of a native encoding
7490 as TYPE. */
7492 static bool
7494 {
7496 {
7509 }
7510 }
7513 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7514 TYPE at compile-time. If we're unable to perform the conversion
7515 return NULL_TREE. */
7517 static tree
7519 {
7520 /* We support up to 512-bit values (for V8DFmode). */
7524 /* Check that the host and target are sane. */
7533 }
7535 /* Build an expression for the address of T. Folds away INDIRECT_REF
7536 to avoid confusing the gimplify process. */
7538 tree
7540 {
7541 /* The size of the object is not relevant when talking about its address. */
7546 {
7551 }
7561 {
7566 }
7567 else
7571 }
7573 /* Build an expression for the address of T. */
7575 tree
7577 {
7581 }
7583 /* Fold a unary expression of code CODE and type TYPE with operand
7584 OP0. Return the folded expression if folding is successful.
7585 Otherwise, return NULL_TREE. */
7587 tree
7589 {
7590 tree tem;
7591 tree arg0;
7599 {
7602 {
7603 /* Don't use STRIP_NOPS, because signedness of argument type
7604 matters. */
7606 }
7607 else
7608 {
7609 /* Strip any conversions that don't change the mode. This
7610 is safe for every expression, except for a comparison
7611 expression because its signedness is derived from its
7612 operands.
7614 Note that this is done as an internal manipulation within
7615 the constant folder, in order to find the simplest
7616 representation of the arguments so that their form can be
7617 studied. In any cases, the appropriate type conversions
7618 should be put back in the tree that will get out of the
7619 constant folder. */
7621 }
7624 {
7627 {
7631 }
7632 }
7633 }
7640 {
7647 {
7661 /* If this was a conversion, and all we did was to move into
7662 inside the COND_EXPR, bring it back out. But leave it if
7663 it is a conversion from integer to integer and the
7664 result precision is no wider than a word since such a
7665 conversion is cheap and may be optimized away by combine,
7666 while it couldn't if it were outside the COND_EXPR. Then return
7667 so we don't get into an infinite recursion loop taking the
7668 conversion out and then back in. */
7680 && (INTEGRAL_TYPE_P
7693 }
7694 }
7697 {
7703 CASE_CONVERT:
7707 {
7708 /* If we have (type) (a CMP b) and type is an integral type, return
7709 new expression involving the new type. Canonicalize
7710 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7711 non-integral type.
7712 Do not fold the result as that would not simplify further, also
7713 folding again results in recursions. */
7723 }
7725 /* Handle (T *)&A.B.C for A being of type T and B and C
7726 living at offset zero. This occurs frequently in
7727 C++ upcasting and then accessing the base. */
7731 {
7733 tree offset;
7734 machine_mode mode;
7736 tree base
7740 /* If the reference was to a (constant) zero offset, we can use
7741 the address of the base if it has the same base type
7742 as the result type and the pointer type is unqualified. */
7749 }
7753 /* Detect assigning a bitfield. */
7755 && DECL_BIT_FIELD
7757 {
7758 /* Don't leave an assignment inside a conversion
7759 unless assigning a bitfield. */
7761 /* First do the assignment, then return converted constant. */
7766 }
7768 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7769 constants (if x has signed type, the sign bit cannot be set
7770 in c). This folds extension into the BIT_AND_EXPR.
7771 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7772 very likely don't have maximal range for their precision and this
7773 transformation effectively doesn't preserve non-maximal ranges. */
7777 {
7788 <= HOST_BITS_PER_WIDE_INT
7790 {
7794 cst &= HOST_WIDE_INT_M1U
7798 && !flag_syntax_only
7801 {
7805 }
7806 }
7808 {
7813 }
7814 }
7816 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7817 cast (T1)X will fold away. We assume that this happens when X itself
7818 is a cast. */
7822 {
7826 return fold_build_pointer_plus_loc
7828 }
7830 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7831 of the same precision, and X is an integer type not narrower than
7832 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7838 {
7844 }
7846 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7847 type of X and Y (integer types only). */
7852 {
7853 /* Be careful not to introduce new overflows. */
7854 tree mult_type;
7857 else
7861 {
7868 }
7869 }
7875 {
7882 }
7893 /* Convert fabs((double)float) into (double)fabsf(float). */
7896 {
7902 targ0));
7903 }
7907 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7926 /* Note that the operand of this must be an int
7927 and its values must be 0 or 1.
7928 ("true" is a fixed value perhaps depending on the language,
7929 but we don't handle values other than 1 correctly yet.) */
7936 /* Fold *&X to X if X is an lvalue. */
7938 {
7945 }
7951 }
7954 /* If the operation was a conversion do _not_ mark a resulting constant
7955 with TREE_OVERFLOW if the original constant was not. These conversions
7956 have implementation defined behavior and retaining the TREE_OVERFLOW
7957 flag here would confuse later passes such as VRP. */
7958 tree
7961 {
7970 }
7972 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
7973 operands OP0 and OP1. LOC is the location of the resulting expression.
7974 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
7975 Return the folded expression if folding is successful. Otherwise,
7976 return NULL_TREE. */
7977 static tree
7980 {
7981 tree tem;
7983 /* We only do these simplifications if we are optimizing. */
7987 /* Check for things like (A || B) && (A || C). We can convert this
7988 to A || (B && C). Note that either operator can be any of the four
7989 truth and/or operations and the transformation will still be
7990 valid. Also note that we only care about order for the
7991 ANDIF and ORIF operators. If B contains side effects, this
7992 might change the truth-value of A. */
7999 {
8019 /* This case if tricky because we must either have commutative
8020 operators or else A10 must not have side-effects. */
8026 a01);
8027 }
8029 /* See if we can build a range comparison. */
8035 {
8039 }
8043 {
8047 }
8049 /* Check for the possibility of merging component references. If our
8050 lhs is another similar operation, try to merge its rhs with our
8051 rhs. Then try to merge our lhs and rhs. */
8061 && !flag_sanitize_coverage
8066 {
8073 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8074 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8075 We don't want to pack more than two leafs to a non-IF AND/OR
8076 expression.
8077 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8078 equal to IF-CODE, then we don't want to add right-hand operand.
8079 If the inner right-hand side of left-hand operand has
8080 side-effects, or isn't simple, then we can't add to it,
8081 as otherwise we might destroy if-sequence. */
8084 /* Needed for sequence points to handle trappings, and
8085 side-effects. */
8087 {
8089 arg1);
8091 tem);
8092 }
8093 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8094 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8097 /* Needed for sequence points to handle trappings, and
8098 side-effects. */
8100 {
8105 }
8106 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8107 into (A OR B).
8108 For sequence point consistancy, we need to check for trapping,
8109 and side-effects. */
8113 }
8116 }
8118 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8119 by changing CODE to reduce the magnitude of constants involved in
8120 ARG0 of the comparison.
8121 Returns a canonicalized comparison tree if a simplification was
8122 possible, otherwise returns NULL_TREE.
8123 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8124 valid if signed overflow is undefined. */
8126 static tree
8130 {
8135 /* Match A +- CST code arg1. We can change this only if overflow
8136 is undefined. */
8139 /* In principle pointers also have undefined overflow behavior,
8140 but that causes problems elsewhere. */
8147 /* Identify the constant in arg0 and its sign. */
8151 /* Overflowed constants and zero will cause problems. */
8156 /* See if we can reduce the magnitude of the constant in
8157 arg0 by changing the comparison code. */
8158 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8162 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8166 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8170 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8174 else
8178 /* Now build the constant reduced in magnitude. But not if that
8179 would produce one outside of its types range. */
8195 }
8197 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8198 overflow further. Try to decrease the magnitude of constants involved
8199 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8200 and put sole constants at the second argument position.
8201 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8203 static tree
8206 {
8207 tree t;
8212 /* Try canonicalization by simplifying arg0. */
8217 {
8221 }
8223 /* Try canonicalization by simplifying arg1 using the swapped
8224 comparison. */
8232 }
8234 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8235 space. This is used to avoid issuing overflow warnings for
8236 expressions like &p->x which can not wrap. */
8238 static bool
8240 {
8247 wide_int wi_offset;
8253 else
8269 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8270 array. */
8272 {
8273 HOST_WIDE_INT base_size;
8278 }
8281 }
8283 /* Return a positive integer when the symbol DECL is known to have
8284 a nonzero address, zero when it's known not to (e.g., it's a weak
8285 symbol), and a negative integer when the symbol is not yet in the
8286 symbol table and so whether or not its address is zero is unknown.
8287 For function local objects always return positive integer. */
8288 static int
8290 {
8295 /* Function local objects are never NULL. */
8303 }
8305 /* Subroutine of fold_binary. This routine performs all of the
8306 transformations that are common to the equality/inequality
8307 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8308 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8309 fold_binary should call fold_binary. Fold a comparison with
8310 tree code CODE and type TYPE with operands OP0 and OP1. Return
8311 the folded comparison or NULL_TREE. */
8313 static tree
8316 {
8326 /* For comparisons of pointers we can decompose it to a compile time
8327 comparison of the base objects and the offsets into the object.
8328 This requires at least one operand being an ADDR_EXPR or a
8329 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8335 {
8338 machine_mode mode;
8342 /* Get base and offset for the access. Strip ADDR_EXPR for
8343 get_inner_reference, but put it back by stripping INDIRECT_REF
8344 off the base object if possible. indirect_baseN will be true
8345 if baseN is not an address but refers to the object itself. */
8348 {
8349 base0
8355 else
8357 }
8359 {
8363 {
8364 base0
8370 else
8372 }
8375 else
8379 {
8385 {
8388 }
8389 }
8390 }
8394 {
8395 base1
8401 else
8403 }
8405 {
8409 {
8410 base1
8416 else
8418 }
8421 else
8425 {
8431 {
8434 }
8435 }
8436 }
8438 /* If we have equivalent bases we might be able to simplify. */
8442 {
8443 /* We can fold this expression to a constant if the non-constant
8444 offset parts are equal. */
8448 {
8454 "occur when comparing P +- C1 with "
8456 WARN_STRICT_OVERFLOW_CONDITIONAL);
8459 {
8473 }
8474 }
8475 /* We can simplify the comparison to a comparison of the variable
8476 offset parts if the constant offset parts are equal.
8477 Be careful to use signed sizetype here because otherwise we
8478 mess with array offsets in the wrong way. This is possible
8479 because pointer arithmetic is restricted to retain within an
8480 object and overflow on pointer differences is undefined as of
8481 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8483 {
8484 /* By converting to signed sizetype we cover middle-end pointer
8485 arithmetic which operates on unsigned pointer types of size
8486 type size and ARRAY_REF offsets which are properly sign or
8487 zero extended from their type in case it is narrower than
8488 sizetype. */
8491 else
8495 else
8502 "occur when comparing P +- C1 with "
8504 WARN_STRICT_OVERFLOW_COMPARISON);
8507 }
8508 }
8509 /* For equal offsets we can simplify to a comparison of the
8510 base addresses. */
8512 && (indirect_base0
8514 && (indirect_base1
8519 {
8525 }
8526 /* Comparison between an ordinary (non-weak) symbol and a null
8527 pointer can be eliminated since such symbols must have a non
8528 null address. In C, relational expressions between pointers
8529 to objects and null pointers are undefined. The results
8530 below follow the C++ rules with the additional property that
8531 every object pointer compares greater than a null pointer.
8532 */
8535 /* Avoid folding references to struct members at offset 0 to
8536 prevent tests like '&ptr->firstmember == 0' from getting
8537 eliminated. When ptr is null, although the -> expression
8538 is strictly speaking invalid, GCC retains it as a matter
8539 of QoI. See PR c/44555. */
8542 && indirect_base0
8543 /* The caller guarantees that when one of the arguments is
8544 constant (i.e., null in this case) it is second. */
8546 {
8548 {
8559 }
8560 }
8561 }
8563 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8564 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8565 the resulting offset is smaller in absolute value than the
8566 original one and has the same sign. */
8575 {
8580 tree cst;
8582 "occur when combining constants around "
8585 /* Put the constant on the side where it doesn't overflow and is
8586 of lower absolute value and of same sign than before. */
8593 {
8596 variable1,
8600 }
8608 {
8614 variable2);
8615 }
8616 }
8622 /* If we are comparing an expression that just has comparisons
8623 of two integer values, arithmetic expressions of those comparisons,
8624 and constants, we can simplify it. There are only three cases
8625 to check: the two values can either be equal, the first can be
8626 greater, or the second can be greater. Fold the expression for
8627 those three values. Since each value must be 0 or 1, we have
8628 eight possibilities, each of which corresponds to the constant 0
8629 or 1 or one of the six possible comparisons.
8631 This handles common cases like (a > b) == 0 but also handles
8632 expressions like ((x > y) - (y > x)) > 0, which supposedly
8633 occur in macroized code. */
8636 {
8641 /* Don't handle degenerate cases here; they should already
8642 have been handled anyway. */
8651 {
8655 /* We can't just pass T to eval_subst in case cval1 or cval2
8656 was the same as ARG1. */
8658 tree high_result
8662 arg1);
8663 tree equal_result
8667 arg1);
8668 tree low_result
8672 arg1);
8674 /* All three of these results should be 0 or 1. Confirm they are.
8675 Then use those values to select the proper code to use. */
8680 {
8681 /* Make a 3-bit mask with the high-order bit being the
8682 value for `>', the next for '=', and the low for '<'. */
8686 {
8688 /* Always false. */
8709 /* Always true. */
8711 }
8714 {
8718 }
8720 }
8721 }
8722 }
8725 }
8728 /* Subroutine of fold_binary. Optimize complex multiplications of the
8729 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8730 argument EXPR represents the expression "z" of type TYPE. */
8732 static tree
8734 {
8739 {
8742 }
8744 {
8747 }
8748 else
8749 {
8753 }
8762 }
8765 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8766 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8767 true if successful. */
8769 static bool
8771 {
8775 {
8778 }
8780 {
8786 else
8788 }
8789 else
8795 }
8797 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8798 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8799 NULL_TREE otherwise. */
8801 static tree
8803 {
8822 {
8826 }
8829 {
8835 }
8836 else
8838 }
8840 /* Try to fold a pointer difference of type TYPE two address expressions of
8841 array references AREF0 and AREF1 using location LOC. Return a
8842 simplified expression for the difference or NULL_TREE. */
8844 static tree
8848 {
8853 /* If the bases are array references as well, recurse. If the bases
8854 are pointer indirections compute the difference of the pointers.
8855 If the bases are equal, we are set. */
8858 && (base_offset
8860 use_pointer_diff)))
8863 && (base_offset
8864 = use_pointer_diff
8874 {
8880 base_offset,
8883 }
8885 }
8887 /* If the real or vector real constant CST of type TYPE has an exact
8888 inverse, return it, else return NULL. */
8890 tree
8892 {
8893 REAL_VALUE_TYPE r;
8894 tree unit_type;
8895 machine_mode mode;
8898 {
8908 {
8912 tree_vector_builder elts;
8917 {
8922 }
8925 }
8929 }
8930 }
8932 /* Mask out the tz least significant bits of X of type TYPE where
8933 tz is the number of trailing zeroes in Y. */
8934 static wide_int
8936 {
8941 }
8943 /* Return true when T is an address and is known to be nonzero.
8944 For floating point we further ensure that T is not denormal.
8945 Similar logic is present in nonzero_address in rtlanal.h.
8947 If the return value is based on the assumption that signed overflow
8948 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
8949 change *STRICT_OVERFLOW_P. */
8951 static bool
8953 {
8957 /* Doing something useful for floating point would need more work. */
8963 {
8966 strict_overflow_p);
8972 strict_overflow_p);
8980 }
8983 {
8986 strict_overflow_p);
8994 strict_overflow_p);
9009 strict_overflow_p);
9013 strict_overflow_p);
9016 {
9028 }
9032 }
9034 }
9036 /* Return true when T is an address and is known to be nonzero.
9037 Handle warnings about undefined signed overflow. */
9039 bool
9041 {
9048 "determining that expression is always "
9050 WARN_STRICT_OVERFLOW_MISC);
9052 }
9054 /* Return true if T is known not to be equal to an integer W. */
9056 bool
9058 {
9060 value_range_type rtype;
9062 {
9071 {
9076 }
9081 /* If T has some known zero bits and W has any of those bits set,
9082 then T is known not to be equal to W. */
9090 }
9091 }
9093 /* Fold a binary expression of code CODE and type TYPE with operands
9094 OP0 and OP1. LOC is the location of the resulting expression.
9095 Return the folded expression if folding is successful. Otherwise,
9096 return NULL_TREE. */
9098 tree
9101 {
9116 /* Strip any conversions that don't change the mode. This is
9117 safe for every expression, except for a comparison expression
9118 because its signedness is derived from its operands. So, in
9119 the latter case, only strip conversions that don't change the
9120 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9121 preserved.
9123 Note that this is done as an internal manipulation within the
9124 constant folder, in order to find the simplest representation
9125 of the arguments so that their form can be studied. In any
9126 cases, the appropriate type conversions should be put back in
9127 the tree that will get out of the constant folder. */
9130 {
9133 }
9134 else
9135 {
9138 }
9140 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9141 constant but we can't do arithmetic on them. */
9143 {
9146 {
9150 }
9151 }
9153 /* If this is a commutative operation, and ARG0 is a constant, move it
9154 to ARG1 to reduce the number of tests below. */
9159 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9160 to ARG1 to reduce the number of tests below. */
9169 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9171 First check for cases where an arithmetic operation is applied to a
9172 compound, conditional, or comparison operation. Push the arithmetic
9173 operation inside the compound or conditional to see if any folding
9174 can then be done. Convert comparison to conditional for this purpose.
9175 The also optimizes non-constant cases that used to be done in
9176 expand_expr.
9178 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9179 one of the operands is a comparison and the other is a comparison, a
9180 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9181 code below would make the expression more complex. Change it to a
9182 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9183 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9196 {
9200 boolean_type_node,
9208 }
9212 {
9214 {
9219 tem);
9220 }
9222 {
9227 tem);
9228 }
9233 {
9239 }
9244 {
9250 }
9251 }
9254 {
9256 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9259 {
9265 }
9267 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9270 {
9271 tree base;
9272 HOST_WIDE_INT coffset;
9281 }
9286 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9292 arg1),
9294 arg0)));
9300 {
9301 /* X + (X / CST) * -CST is X % CST. */
9306 {
9315 cst0));
9316 }
9317 }
9319 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9320 one. Make sure the type is not saturating and has the signedness of
9321 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9322 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9329 {
9333 }
9336 {
9337 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9338 (plus (plus (mult) (mult)) (foo)) so that we can
9339 take advantage of the factoring cases below. */
9348 {
9354 else
9367 parg0),
9369 marg)),
9373 return
9379 parg1)));
9380 }
9381 }
9382 else
9383 {
9384 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9385 to __complex__ ( x, y ). This is not the same for SNaNs or
9386 if signed zeros are involved. */
9390 {
9397 {
9401 {
9407 }
9409 {
9415 }
9416 }
9417 }
9419 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9420 We associate floats only if the user has specified
9421 -fassociative-math. */
9425 {
9430 {
9431 tree tree0;
9434 }
9435 }
9436 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9437 We associate floats only if the user has specified
9438 -fassociative-math. */
9442 {
9447 {
9448 tree tree0;
9451 }
9452 }
9453 }
9455 bit_rotate:
9456 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9457 is a rotate of A by C1 bits. */
9458 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9459 is a rotate of A by B bits.
9460 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9461 though in this case CODE must be | and not + or ^, otherwise
9462 it doesn't return A when B is 0. */
9463 {
9465 tree rtype;
9474 /* Only create rotates in complete modes. Other cases are not
9475 expanded properly. */
9478 {
9491 {
9496 }
9501 {
9504 code0 == LSHIFT_EXPR
9507 }
9509 {
9519 {
9523 orig_tree01);
9525 }
9526 }
9530 {
9541 {
9545 orig_tree01);
9547 }
9548 }
9549 }
9550 }
9552 associate:
9553 /* In most languages, can't associate operations on floats through
9554 parentheses. Rather than remember where the parentheses were, we
9555 don't associate floats at all, unless the user has specified
9556 -fassociative-math.
9557 And, we need to make sure type is not saturating. */
9561 {
9567 /* Split both trees into variables, constants, and literals. Then
9568 associate each group together, the constants with literals,
9569 then the result with variables. This increases the chances of
9570 literals being recombined later and of generating relocatable
9571 expressions for the sum of a constant and literal. */
9579 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9583 /* With undefined overflow prefer doing association in a type
9584 which wraps on overflow, if that is one of the operand types. */
9587 {
9595 }
9597 /* With undefined overflow we can only associate constants with one
9598 variable, and constants whose association doesn't overflow. */
9601 {
9603 {
9604 /* ??? If split_tree would handle NEGATE_EXPR we could
9605 simply reject these cases and the allowed cases would
9606 be the var0/minus_var1 ones. */
9612 {
9615 }
9622 {
9625 }
9631 /* The only case we can still associate with two variables
9632 is if they cancel out. */
9636 }
9642 }
9644 /* Only do something if we found more than two objects. Otherwise,
9645 nothing has changed and we risk infinite recursion. */
9653 {
9665 {
9669 }
9671 {
9675 }
9677 /* Preserve the MINUS_EXPR if the negative part of the literal is
9678 greater than the positive part. Otherwise, the multiplicative
9679 folding code (i.e extract_muldiv) may be fooled in case
9680 unsigned constants are subtracted, like in the following
9681 example: ((X*2 + 4) - 8U)/2. */
9683 {
9687 /* But avoid ending up with only negated parts. */
9689 {
9693 }
9694 else
9695 {
9699 }
9700 }
9702 /* Don't introduce overflows through reassociation. */
9707 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9714 /* Eliminate minus_con0. */
9716 {
9723 else
9726 }
9728 /* Eliminate minus_var0. */
9730 {
9734 else
9737 }
9739 return
9742 }
9743 }
9749 /* Fold &a[i] - &a[j] to i-j. */
9754 {
9758 code
9762 }
9764 /* Further transformations are not for pointers. */
9768 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9776 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9777 __complex__ ( x, -y ). This is not the same for SNaNs or if
9778 signed zeros are involved. */
9782 {
9789 {
9793 {
9795 arg1r ? arg1r
9800 }
9802 {
9806 arg1i ? arg1i
9809 }
9810 }
9811 }
9813 /* A - B -> A + (-B) if B is easily negatable. */
9817 /* Avoid this transformation if B is a positive REAL_CST. */
9825 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9826 one. Make sure the type is not saturating and has the signedness of
9827 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9828 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9835 {
9839 }
9845 {
9846 /* Transform x * -C into -x * C if x is easily negatable. */
9861 {
9864 "occur when simplifying "
9866 WARN_STRICT_OVERFLOW_MISC);
9868 }
9870 /* Optimize z * conj(z) for integer complex numbers. */
9877 }
9878 else
9879 {
9880 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9881 This is not the same for NaNs or if signed zeros are
9882 involved. */
9888 {
9891 return
9897 return
9902 }
9904 /* Optimize z * conj(z) for floating point complex numbers.
9905 Guarded by flag_unsafe_math_optimizations as non-finite
9906 imaginary components don't produce scalar results. */
9915 }
9919 /* Canonicalize (X & C1) | C2. */
9923 {
9928 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9936 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9938 {
9941 }
9943 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
9944 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
9945 mode which allows further optimizations. */
9950 {
9955 {
9958 }
9959 }
9962 {
9967 }
9968 }
9970 /* See if this can be simplified into a rotate first. If that
9971 is unsuccessful continue in the association code. */
9975 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9983 /* See if this can be simplified into a rotate first. If that
9984 is unsuccessful continue in the association code. */
9988 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9993 {
9994 tree tem2;
10001 }
10002 /* Fold ~X & 1 as (X & 1) == 0. */
10006 {
10007 tree tem2;
10014 }
10015 /* Fold !X & 1 as X == 0. */
10018 {
10022 }
10024 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10025 multiple of 1 << CST. */
10027 {
10034 }
10036 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10037 bits from CST2. */
10041 {
10043 wide_int masked
10050 {
10051 /* Avoid the transform if arg1 is a mask of some
10052 mode which allows further optimizations. */
10059 }
10060 }
10062 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10063 ((A & N) + B) & M -> (A + B) & M
10064 Similarly if (N & M) == 0,
10065 ((A | N) + B) & M -> (A + B) & M
10066 and for - instead of + (or unary - instead of +)
10067 and/or ^ instead of |.
10068 If B is constant and (B & M) == 0, fold into A & M. */
10070 {
10079 {
10082 wide_int cst0;
10084 /* Now we know that arg0 is (C + D) or (C - D) or
10085 -C and arg1 (M) is == (1LL << cst) - 1.
10086 Store C into PMOP[0] and D into PMOP[1]. */
10090 {
10093 }
10100 {
10109 {
10112 }
10115 /* If C or D is of the form (A & N) where
10116 (N & M) == M, or of the form (A | N) or
10117 (A ^ N) where (N & M) == 0, replace it with A. */
10121 /* If C or D is a N where (N & M) == 0, it can be
10122 omitted (assumed 0). */
10130 }
10132 /* Only build anything new if we optimized one or both arguments
10133 above. */
10137 {
10140 {
10141 /* Perform the operations in a type that has defined
10142 overflow behavior. */
10148 }
10153 {
10161 else
10163 }
10166 else
10169 /* TEM is now the new binary +, - or unary - replacement. */
10173 }
10174 }
10175 }
10177 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10180 {
10185 return
10187 }
10192 /* Don't touch a floating-point divide by zero unless the mode
10193 of the constant can represent infinity. */
10199 /* (-A) / (-B) -> A / B */
10211 /* Fall through */
10214 /* Simplify A / (B << N) where A and B are positive and B is
10215 a power of 2, to A >> (N + log2(B)). */
10220 {
10223 {
10231 WARN_STRICT_OVERFLOW_MISC);
10237 }
10238 }
10240 /* Fall through */
10248 /* Convert -A / -B to A / B when the type is signed and overflow is
10249 undefined. */
10253 {
10256 "when distributing negation across "
10258 WARN_STRICT_OVERFLOW_MISC);
10263 }
10267 {
10270 "when distributing negation across "
10272 WARN_STRICT_OVERFLOW_MISC);
10277 }
10279 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10280 operation, EXACT_DIV_EXPR.
10282 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10283 At one time others generated faster code, it's not clear if they do
10284 after the last round to changes to the DIV code in expmed.c. */
10295 {
10299 WARN_STRICT_OVERFLOW_MISC);
10301 }
10313 {
10317 WARN_STRICT_OVERFLOW_MISC);
10319 }
10327 /* Since negative shift count is not well-defined,
10328 don't try to compute it in the compiler. */
10334 /* If we have a rotate of a bit operation with the rotate count and
10335 the second operand of the bit operation both constant,
10336 permute the two operations. */
10342 {
10350 }
10352 /* Two consecutive rotates adding up to the some integer
10353 multiple of the precision of the type can be ignored. */
10369 /* Note that the operands of this must be ints
10370 and their values must be 0 or 1.
10371 ("true" is a fixed value perhaps depending on the language.) */
10372 /* If first arg is constant zero, return it. */
10375 /* FALLTHRU */
10377 /* If either arg is constant true, drop it. */
10381 /* Preserve sequence points. */
10384 /* If second arg is constant zero, result is zero, but first arg
10385 must be evaluated. */
10388 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10389 case will be handled here. */
10393 /* !X && X is always false. */
10397 /* X && !X is always false. */
10402 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10403 means A >= Y && A != MAX, but in this case we know that
10404 A < X <= MAX. */
10408 {
10416 }
10425 /* Note that the operands of this must be ints
10426 and their values must be 0 or true.
10427 ("true" is a fixed value perhaps depending on the language.) */
10428 /* If first arg is constant true, return it. */
10431 /* FALLTHRU */
10433 /* If either arg is constant zero, drop it. */
10437 /* Preserve sequence points. */
10440 /* If second arg is constant true, result is true, but we must
10441 evaluate first arg. */
10444 /* Likewise for first arg, but note this only occurs here for
10445 TRUTH_OR_EXPR. */
10449 /* !X || X is always true. */
10453 /* X || !X is always true. */
10458 /* (X && !Y) || (!X && Y) is X ^ Y */
10461 {
10478 }
10487 /* If the second arg is constant zero, drop it. */
10490 /* If the second arg is constant true, this is a logical inversion. */
10492 {
10495 }
10496 /* Identical arguments cancel to zero. */
10500 /* !X ^ X is always true. */
10505 /* X ^ !X is always true. */
10521 /* bool_var != 1 becomes !bool_var. */
10528 /* bool_var == 0 becomes !bool_var. */
10535 /* !exp != 0 becomes !exp */
10540 /* If this is an EQ or NE comparison with zero and ARG0 is
10541 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10542 two operations, but the latter can be done in one less insn
10543 on machines that have only two-operand insns or on which a
10544 constant cannot be the first operand. */
10547 {
10552 {
10559 arg1);
10560 }
10563 {
10570 arg1);
10571 }
10572 }
10574 /* If this is an NE or EQ comparison of zero against the result of a
10575 signed MOD operation whose second operand is a power of 2, make
10576 the MOD operation unsigned since it is simpler and equivalent. */
10584 {
10594 }
10596 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10597 C1 is a valid shift constant, and C2 is a power of two, i.e.
10598 a single bit. */
10602 == INTEGER_CST
10605 {
10610 /* Check for a valid shift count. */
10612 {
10616 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10617 can be rewritten as (X & (C2 << C1)) != 0. */
10619 {
10624 }
10625 /* Otherwise, for signed (arithmetic) shifts,
10626 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10627 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10631 /* Otherwise, of unsigned (logical) shifts,
10632 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10633 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10634 else
10638 arg000);
10639 }
10640 }
10642 /* If this is a comparison of a field, we may be able to simplify it. */
10645 /* Handle the constant case even without -O
10646 to make sure the warnings are given. */
10648 {
10652 }
10654 /* Optimize comparisons of strlen vs zero to a compare of the
10655 first character of the string vs zero. To wit,
10656 strlen(ptr) == 0 => *ptr == 0
10657 strlen(ptr) != 0 => *ptr != 0
10658 Other cases should reduce to one of these two (or a constant)
10659 due to the return value of strlen being unsigned. */
10662 {
10670 {
10675 }
10676 }
10678 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10679 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10683 {
10688 {
10690 {
10693 }
10696 }
10697 }
10699 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10700 (X & C) == 0 when C is a single bit. */
10705 {
10712 arg1));
10713 }
10715 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10716 constant C is a power of two, i.e. a single bit. */
10723 {
10727 }
10729 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10730 when is C is a power of two, i.e. a single bit. */
10737 {
10743 }
10747 {
10750 }
10752 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10755 {
10763 {
10769 }
10771 {
10777 }
10779 {
10785 }
10787 {
10793 }
10794 }
10798 {
10805 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10806 operand_equal_p guarantees no side-effects so we don't need
10807 to use omit_one_operand on Z. */
10811 arg10));
10815 arg11));
10819 arg10));
10823 arg11));
10825 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10828 {
10834 }
10835 }
10837 /* Attempt to simplify equality/inequality comparisons of complex
10838 values. Only lower the comparison if the result is known or
10839 can be simplified to a single scalar comparison. */
10844 {
10849 {
10852 }
10853 else
10854 {
10857 }
10860 {
10863 }
10864 else
10865 {
10868 }
10872 {
10874 {
10879 }
10880 else
10881 {
10886 }
10887 }
10891 {
10893 {
10898 }
10899 else
10900 {
10905 }
10906 }
10907 }
10919 /* Transform comparisons of the form X +- C CMP X. */
10924 {
10929 /* (X - c) > X becomes false. */
10935 /* Likewise (X + c) < X becomes false. */
10941 /* Convert (X - c) <= X to true. */
10948 /* Convert (X + c) >= X to true. */
10954 }
10956 /* If we are comparing an ABS_EXPR with a constant, we can
10957 convert all the cases into explicit comparisons, but they may
10958 well not be faster than doing the ABS and one comparison.
10959 But ABS (X) <= C is a range comparison, which becomes a subtraction
10960 and a comparison, and is probably faster. */
10974 /* Convert ABS_EXPR<x> >= 0 to true. */
10981 {
10984 "when simplifying comparison of "
10986 WARN_STRICT_OVERFLOW_CONDITIONAL);
10989 arg0);
10990 }
10992 /* Convert ABS_EXPR<x> < 0 to false. */
10997 {
11000 "when simplifying comparison of "
11002 WARN_STRICT_OVERFLOW_CONDITIONAL);
11005 arg0);
11006 }
11008 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11009 and similarly for >= into !=. */
11019 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11020 otherwise Y might be >= # of bits in X's type and thus e.g.
11021 (unsigned char) (1 << Y) for Y 15 might be 0.
11022 If the cast is widening, then 1 << Y should have unsigned type,
11023 otherwise if Y is number of bits in the signed shift type minus 1,
11024 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11025 31 might be 0xffffffff80000000. */
11036 {
11042 }
11054 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11055 {
11067 }
11072 /* When pedantic, a compound expression can be neither an lvalue
11073 nor an integer constant expression. */
11076 /* Don't let (0, 0) be null pointer constant. */
11082 /* An ASSERT_EXPR should never be passed to fold_binary. */
11088 }
11090 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11091 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11092 of GOTO_EXPR. */
11094 static tree
11096 {
11098 {
11105 /* fall through */
11109 }
11110 }
11112 /* Return whether the sub-tree ST contains a label which is accessible from
11113 outside the sub-tree. */
11115 static bool
11117 {
11118 return
11120 }
11122 /* Fold a ternary expression of code CODE and type TYPE with operands
11123 OP0, OP1, and OP2. Return the folded expression if folding is
11124 successful. Otherwise, return NULL_TREE. */
11126 tree
11129 {
11130 tree tem;
11137 /* If this is a commutative operation, and OP0 is a constant, move it
11138 to OP1 to reduce the number of tests below. */
11147 /* Strip any conversions that don't change the mode. This is safe
11148 for every expression, except for a comparison expression because
11149 its signedness is derived from its operands. So, in the latter
11150 case, only strip conversions that don't change the signedness.
11152 Note that this is done as an internal manipulation within the
11153 constant folder, in order to find the simplest representation of
11154 the arguments so that their form can be studied. In any cases,
11155 the appropriate type conversions should be put back in the tree
11156 that will get out of the constant folder. */
11158 {
11161 }
11164 {
11167 }
11170 {
11173 }
11176 {
11180 {
11186 }
11191 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11192 so all simple results must be passed through pedantic_non_lvalue. */
11194 {
11197 /* Only optimize constant conditions when the selected branch
11198 has the same type as the COND_EXPR. This avoids optimizing
11199 away "c ? x : throw", where the throw has a void type.
11200 Avoid throwing away that operand which contains label. */
11207 }
11209 {
11214 {
11219 {
11227 }
11231 }
11232 }
11234 /* If we have A op B ? A : C, we may be able to convert this to a
11235 simpler expression, depending on the operation and the values
11236 of B and C. Signed zeros prevent all of these transformations,
11237 for reasons given above each one.
11239 Also try swapping the arguments and inverting the conditional. */
11243 {
11247 }
11252 {
11256 {
11260 }
11261 }
11263 /* If the second operand is simpler than the third, swap them
11264 since that produces better jump optimization results. */
11267 {
11269 /* See if this can be inverted. If it can't, possibly because
11270 it was a floating-point inequality comparison, don't do
11271 anything. */
11275 }
11277 /* Convert A ? 1 : 0 to simply A. */
11282 /* If we try to convert OP0 to our type, the
11283 call to fold will try to move the conversion inside
11284 a COND, which will recurse. In that case, the COND_EXPR
11285 is probably the best choice, so leave it alone. */
11289 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11290 over COND_EXPR in cases such as floating point comparisons. */
11299 arg0)));
11301 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11306 {
11307 /* sign_bit_p looks through both zero and sign extensions,
11308 but for this optimization only sign extensions are
11309 usable. */
11312 {
11315 {
11318 }
11320 }
11321 /* sign_bit_p only checks ARG1 bits within A's precision.
11322 If <sign bit of A> has wider type than A, bits outside
11323 of A's precision in <sign bit of A> need to be checked.
11324 If they are all 0, this optimization needs to be done
11325 in unsigned A's type, if they are all 1 in signed A's type,
11326 otherwise this can't be done. */
11332 {
11334 tree tem_type;
11347 {
11350 }
11352 {
11355 }
11356 else
11358 }
11361 return
11367 arg1)));
11368 }
11370 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11371 already handled above. */
11376 {
11386 op1);
11387 }
11389 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11390 is probably obsolete because the first operand should be a
11391 truth value (that's why we have the two cases above), but let's
11392 leave it in until we can confirm this for all front-ends. */
11404 /* Disable the transformations below for vectors, since
11405 fold_binary_op_with_conditional_arg may undo them immediately,
11406 yielding an infinite loop. */
11410 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11419 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11424 {
11426 /* Only perform transformation if ARG0 is easily inverted. */
11430 ? BIT_IOR_EXPR
11433 op1);
11434 }
11436 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11441 {
11443 /* Only perform transformation if ARG0 is easily inverted. */
11449 op2);
11450 }
11452 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11464 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11465 of fold_ternary on them. */
11473 {
11483 {
11488 {
11496 }
11497 }
11498 }
11500 /* On constants we can use native encode/interpret to constant
11501 fold (nearly) all BIT_FIELD_REFs. */
11505 {
11508 /* Limit us to a reasonable amount of work. To relax the
11509 other limitations we need bit-shifting of the buffer
11510 and rounding up the size. */
11514 {
11516 unsigned HOST_WIDE_INT len
11521 {
11526 }
11527 }
11528 }
11533 /* For integers we can decompose the FMA if possible. */
11545 {
11561 {
11566 /* Make sure that the perm value is in an acceptable
11567 range. */
11576 else
11584 }
11587 {
11592 }
11597 {
11602 }
11608 {
11612 }
11617 /* Some targets are deficient and fail to expand a single
11618 argument permutation while still allowing an equivalent
11619 2-argument version. */
11623 {
11626 }
11629 {
11636 }
11640 }
11644 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11647 {
11653 wide_int tem2
11657 }
11662 {
11664 unsigned HOST_WIDE_INT elsize
11667 {
11671 else
11672 {
11679 }
11680 }
11681 }
11687 }
11689 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11690 of an array (or vector). */
11692 tree
11694 {
11699 {
11702 {
11703 /* Static constructors for variably sized objects makes no sense. */
11707 }
11708 }
11719 offset_int max_index;
11724 {
11725 /* Array constructor might explicitly set index, or specify a range,
11726 or leave index NULL meaning that it is next index after previous
11727 one. */
11729 {
11732 else
11733 {
11737 }
11738 }
11739 else
11740 {
11746 }
11748 /* Do we have match? */
11752 }
11754 }
11756 /* Perform constant folding and related simplification of EXPR.
11757 The related simplifications include x*1 => x, x*0 => 0, etc.,
11758 and application of the associative law.
11759 NOP_EXPR conversions may be removed freely (as long as we
11760 are careful not to change the type of the overall expression).
11761 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11762 but we can constant-fold them if they have constant operands. */
11764 #ifdef ENABLE_FOLD_CHECKING
11765 # define fold(x) fold_1 (x)
11767 static
11768 #endif
11769 tree
11771 {
11775 tree tem;
11778 /* Return right away if a constant. */
11782 /* CALL_EXPR-like objects with variable numbers of operands are
11783 treated specially. */
11785 {
11787 {
11790 }
11792 }
11795 {
11800 {
11818 }
11819 }
11822 {
11824 {
11831 {
11836 }
11839 }
11841 /* Return a VECTOR_CST if possible. */
11843 {
11849 tree val;
11855 }
11863 }
11865 #ifdef ENABLE_FOLD_CHECKING
11866 #undef fold
11873 /* When --enable-checking=fold, compute a digest of expr before
11874 and after actual fold call to see if fold did not accidentally
11875 change original expr. */
11877 tree
11879 {
11880 tree ret;
11900 }
11902 void
11904 {
11915 }
11917 static void
11919 {
11921 }
11923 static void
11926 {
11932 recursive_label:
11942 {
11943 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
11948 }
11956 {
11957 /* Allow these fields to be modified. */
11958 tree tmp;
11967 {
11970 }
11971 }
11982 {
11985 {
12000 }
12004 {
12017 }
12034 {
12040 }
12043 {
12045 {
12048 }
12050 }
12061 {
12064 }
12074 }
12075 }
12077 /* Helper function for outputting the checksum of a tree T. When
12078 debugging with gdb, you can "define mynext" to be "next" followed
12079 by "call debug_fold_checksum (op0)", then just trace down till the
12080 outputs differ. */
12082 DEBUG_FUNCTION void
12084 {
12099 }
12101 #endif
12103 /* Fold a unary tree expression with code CODE of type TYPE with an
12104 operand OP0. LOC is the location of the resulting expression.
12105 Return a folded expression if successful. Otherwise, return a tree
12106 expression with code CODE of type TYPE with an operand OP0. */
12108 tree
12111 {
12112 tree tem;
12113 #ifdef ENABLE_FOLD_CHECKING
12122 #endif
12128 #ifdef ENABLE_FOLD_CHECKING
12135 #endif
12137 }
12139 /* Fold a binary tree expression with code CODE of type TYPE with
12140 operands OP0 and OP1. LOC is the location of the resulting
12141 expression. Return a folded expression if successful. Otherwise,
12142 return a tree expression with code CODE of type TYPE with operands
12143 OP0 and OP1. */
12145 tree
12148 MEM_STAT_DECL)
12149 {
12150 tree tem;
12151 #ifdef ENABLE_FOLD_CHECKING
12168 #endif
12174 #ifdef ENABLE_FOLD_CHECKING
12189 #endif
12191 }
12193 /* Fold a ternary tree expression with code CODE of type TYPE with
12194 operands OP0, OP1, and OP2. Return a folded expression if
12195 successful. Otherwise, return a tree expression with code CODE of
12196 type TYPE with operands OP0, OP1, and OP2. */
12198 tree
12201 {
12202 tree tem;
12203 #ifdef ENABLE_FOLD_CHECKING
12227 #endif
12234 #ifdef ENABLE_FOLD_CHECKING
12257 #endif
12259 }
12261 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12262 arguments in ARGARRAY, and a null static chain.
12263 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12264 of type TYPE from the given operands as constructed by build_call_array. */
12266 tree
12269 {
12270 tree tem;
12271 #ifdef ENABLE_FOLD_CHECKING
12290 #endif
12296 #ifdef ENABLE_FOLD_CHECKING
12312 #endif
12314 }
12316 /* Perform constant folding and related simplification of initializer
12317 expression EXPR. These behave identically to "fold_buildN" but ignore
12318 potential run-time traps and exceptions that fold must preserve. */
12320 #define START_FOLD_INIT \
12321 int saved_signaling_nans = flag_signaling_nans;\
12322 int saved_trapping_math = flag_trapping_math;\
12323 int saved_rounding_math = flag_rounding_math;\
12324 int saved_trapv = flag_trapv;\
12325 int saved_folding_initializer = folding_initializer;\
12326 flag_signaling_nans = 0;\
12327 flag_trapping_math = 0;\
12328 flag_rounding_math = 0;\
12329 flag_trapv = 0;\
12330 folding_initializer = 1;
12332 #define END_FOLD_INIT \
12333 flag_signaling_nans = saved_signaling_nans;\
12334 flag_trapping_math = saved_trapping_math;\
12335 flag_rounding_math = saved_rounding_math;\
12336 flag_trapv = saved_trapv;\
12337 folding_initializer = saved_folding_initializer;
12339 tree
12342 {
12343 tree result;
12344 START_FOLD_INIT;
12348 END_FOLD_INIT;
12350 }
12352 tree
12355 {
12356 tree result;
12357 START_FOLD_INIT;
12361 END_FOLD_INIT;
12363 }
12365 tree
12368 {
12369 tree result;
12370 START_FOLD_INIT;
12374 END_FOLD_INIT;
12376 }
12378 #undef START_FOLD_INIT
12379 #undef END_FOLD_INIT
12381 /* Determine if first argument is a multiple of second argument. Return 0 if
12382 it is not, or we cannot easily determined it to be.
12384 An example of the sort of thing we care about (at this point; this routine
12385 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12386 fold cases do now) is discovering that
12388 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12390 is a multiple of
12392 SAVE_EXPR (J * 8)
12394 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12396 This code also handles discovering that
12398 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12400 is a multiple of 8 so we don't have to worry about dealing with a
12401 possible remainder.
12403 Note that we *look* inside a SAVE_EXPR only to determine how it was
12404 calculated; it is not safe for fold to do much of anything else with the
12405 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12406 at run time. For example, the latter example above *cannot* be implemented
12407 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12408 evaluation time of the original SAVE_EXPR is not necessarily the same at
12409 the time the new expression is evaluated. The only optimization of this
12410 sort that would be valid is changing
12412 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12414 divided by 8 to
12416 SAVE_EXPR (I) * SAVE_EXPR (J)
12418 (where the same SAVE_EXPR (J) is used in the original and the
12419 transformed version). */
12421 int
12423 {
12434 {
12436 /* Bitwise and provides a power of two multiple. If the mask is
12437 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12440 /* FALLTHRU */
12447 /* It is impossible to prove if op0 - op1 is multiple of bottom
12448 precisely, so be conservative here checking if both op0 and op1
12449 are multiple of bottom. Note we check the second operand first
12450 since it's usually simpler. */
12455 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12456 as op0 - 3 if the expression has unsigned type. For example,
12457 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12467 {
12469 /* const_binop may not detect overflow correctly,
12470 so check for it explicitly here. */
12475 size_one_node,
12476 op1)))
12479 }
12483 /* Can't handle conversions from non-integral or wider integral type. */
12489 /* fall through */
12506 SIGNED);
12512 {
12515 /* Check for special cases to see if top is defined as multiple
12516 of bottom:
12518 top = (X & ~(bottom - 1) ; bottom is power of 2
12520 or
12522 Y = X % bottom
12523 top = X - Y. */
12542 }
12544 /* fall through */
12548 }
12549 }
12551 #define tree_expr_nonnegative_warnv_p(X, Y) \
12554 #define RECURSE(X) \
12555 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12557 /* Return true if CODE or TYPE is known to be non-negative. */
12559 static bool
12561 {
12564 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12565 have a signed:1 type (where the value is -1 and 0). */
12568 }
12570 /* Return true if (CODE OP0) is known to be non-negative. If the return
12571 value is based on the assumption that signed overflow is undefined,
12572 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12573 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12575 bool
12578 {
12583 {
12585 /* We can't return 1 if flag_wrapv is set because
12586 ABS_EXPR<INT_MIN> = INT_MIN. */
12590 {
12593 }
12601 CASE_CONVERT:
12602 {
12607 {
12611 {
12615 }
12616 }
12618 {
12624 }
12625 }
12630 }
12632 /* We don't know sign of `t', so be conservative and return false. */
12634 }
12636 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12637 value is based on the assumption that signed overflow is undefined,
12638 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12639 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12641 bool
12645 {
12650 {
12656 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12657 both unsigned and at least 2 bits shorter than the result. */
12661 {
12666 {
12670 }
12671 }
12676 {
12677 /* x * x is always non-negative for floating point x
12678 or without overflow. */
12681 {
12686 }
12687 }
12689 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12690 both unsigned and their total bits is shorter than the result. */
12694 {
12713 {
12723 }
12724 }
12751 }
12753 /* We don't know sign of `t', so be conservative and return false. */
12755 }
12757 /* Return true if T is known to be non-negative. If the return
12758 value is based on the assumption that signed overflow is undefined,
12759 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12760 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12762 bool
12764 {
12769 {
12783 /* Limit the depth of recursion to avoid quadratic behavior.
12784 This is expected to catch almost all occurrences in practice.
12785 If this code misses important cases that unbounded recursion
12786 would not, passes that need this information could be revised
12787 to provide it through dataflow propagation. */
12795 }
12796 }
12798 /* Return true if T is known to be non-negative. If the return
12799 value is based on the assumption that signed overflow is undefined,
12800 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12801 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12803 bool
12806 {
12808 {
12809 CASE_CFN_ACOS:
12810 CASE_CFN_ACOSH:
12811 CASE_CFN_CABS:
12812 CASE_CFN_COSH:
12813 CASE_CFN_ERFC:
12814 CASE_CFN_EXP:
12815 CASE_CFN_EXP10:
12816 CASE_CFN_EXP2:
12817 CASE_CFN_FABS:
12818 CASE_CFN_FDIM:
12819 CASE_CFN_HYPOT:
12820 CASE_CFN_POW10:
12821 CASE_CFN_FFS:
12822 CASE_CFN_PARITY:
12823 CASE_CFN_POPCOUNT:
12824 CASE_CFN_CLZ:
12825 CASE_CFN_CLRSB:
12828 /* Always true. */
12831 CASE_CFN_SQRT:
12832 CASE_CFN_SQRT_FN:
12833 /* sqrt(-0.0) is -0.0. */
12838 CASE_CFN_ASINH:
12839 CASE_CFN_ATAN:
12840 CASE_CFN_ATANH:
12841 CASE_CFN_CBRT:
12842 CASE_CFN_CEIL:
12843 CASE_CFN_ERF:
12844 CASE_CFN_EXPM1:
12845 CASE_CFN_FLOOR:
12846 CASE_CFN_FMOD:
12847 CASE_CFN_FREXP:
12848 CASE_CFN_ICEIL:
12849 CASE_CFN_IFLOOR:
12850 CASE_CFN_IRINT:
12851 CASE_CFN_IROUND:
12852 CASE_CFN_LCEIL:
12853 CASE_CFN_LDEXP:
12854 CASE_CFN_LFLOOR:
12855 CASE_CFN_LLCEIL:
12856 CASE_CFN_LLFLOOR:
12857 CASE_CFN_LLRINT:
12858 CASE_CFN_LLROUND:
12859 CASE_CFN_LRINT:
12860 CASE_CFN_LROUND:
12861 CASE_CFN_MODF:
12862 CASE_CFN_NEARBYINT:
12863 CASE_CFN_RINT:
12864 CASE_CFN_ROUND:
12865 CASE_CFN_SCALB:
12866 CASE_CFN_SCALBLN:
12867 CASE_CFN_SCALBN:
12868 CASE_CFN_SIGNBIT:
12869 CASE_CFN_SIGNIFICAND:
12870 CASE_CFN_SINH:
12871 CASE_CFN_TANH:
12872 CASE_CFN_TRUNC:
12873 /* True if the 1st argument is nonnegative. */
12876 CASE_CFN_FMAX:
12877 CASE_CFN_FMAX_FN:
12878 /* True if the 1st OR 2nd arguments are nonnegative. */
12881 CASE_CFN_FMIN:
12882 CASE_CFN_FMIN_FN:
12883 /* True if the 1st AND 2nd arguments are nonnegative. */
12886 CASE_CFN_COPYSIGN:
12887 CASE_CFN_COPYSIGN_FN:
12888 /* True if the 2nd argument is nonnegative. */
12891 CASE_CFN_POWI:
12892 /* True if the 1st argument is nonnegative or the second
12893 argument is an even integer. */
12899 CASE_CFN_POW:
12900 /* True if the 1st argument is nonnegative or the second
12901 argument is an even integer valued real. */
12903 {
12904 REAL_VALUE_TYPE c;
12905 HOST_WIDE_INT n;
12910 {
12911 REAL_VALUE_TYPE cint;
12915 }
12916 }
12921 }
12923 }
12925 /* Return true if T is known to be non-negative. If the return
12926 value is based on the assumption that signed overflow is undefined,
12927 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12928 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12930 static bool
12932 {
12938 {
12940 {
12944 /* If the initializer is non-void, then it's a normal expression
12945 that will be assigned to the slot. */
12949 /* Otherwise, the initializer sets the slot in some way. One common
12950 way is an assignment statement at the end of the initializer. */
12952 {
12960 else
12962 }
12968 }
12971 {
12977 arg0,
12978 arg1,
12980 }
12993 }
12994 }
12996 #undef RECURSE
12997 #undef tree_expr_nonnegative_warnv_p
12999 /* Return true if T is known to be non-negative. If the return
13000 value is based on the assumption that signed overflow is undefined,
13001 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13002 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13004 bool
13006 {
13013 {
13035 }
13038 {
13064 }
13065 }
13067 /* Return true if `t' is known to be non-negative. Handle warnings
13068 about undefined signed overflow. */
13070 bool
13072 {
13079 "determining that expression is always "
13081 WARN_STRICT_OVERFLOW_MISC);
13083 }
13086 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13087 For floating point we further ensure that T is not denormal.
13088 Similar logic is present in nonzero_address in rtlanal.h.
13090 If the return value is based on the assumption that signed overflow
13091 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13092 change *STRICT_OVERFLOW_P. */
13094 bool
13097 {
13099 {
13102 strict_overflow_p);
13105 {
13111 strict_overflow_p));
13112 }
13117 strict_overflow_p);
13121 }
13124 }
13126 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13127 For floating point we further ensure that T is not denormal.
13128 Similar logic is present in nonzero_address in rtlanal.h.
13130 If the return value is based on the assumption that signed overflow
13131 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13132 change *STRICT_OVERFLOW_P. */
13134 bool
13136 tree type,
13137 tree op0,
13139 {
13142 {
13146 {
13147 /* With the presence of negative values it is hard
13148 to say something. */
13155 /* One of operands must be positive and the other non-negative. */
13156 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13157 overflows, on a twos-complement machine the sum of two
13158 nonnegative numbers can never be zero. */
13160 strict_overflow_p)
13162 strict_overflow_p));
13163 }
13168 {
13170 strict_overflow_p)
13172 strict_overflow_p))
13173 {
13176 }
13177 }
13186 {
13189 }
13196 {
13200 /* When both operands are nonzero, then MAX must be too. */
13202 strict_overflow_p))
13205 /* MAX where operand 0 is positive is positive. */
13207 strict_overflow_p);
13208 }
13209 /* MAX where operand 1 is positive is positive. */
13214 {
13218 }
13223 strict_overflow_p)
13225 strict_overflow_p));
13229 }
13232 }
13234 /* Return true when T is an address and is known to be nonzero.
13235 For floating point we further ensure that T is not denormal.
13236 Similar logic is present in nonzero_address in rtlanal.h.
13238 If the return value is based on the assumption that signed overflow
13239 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13240 change *STRICT_OVERFLOW_P. */
13242 bool
13244 {
13247 {
13252 {
13264 /* For objects in symbol table check if we know they are non-zero.
13265 Don't do anything for variables and functions before symtab is built;
13266 it is quite possible that they will be declared weak later. */
13271 /* Constants are never weak. */
13276 }
13284 {
13288 }
13298 }
13300 }
13302 #define integer_valued_real_p(X) \
13305 #define RECURSE(X) \
13306 ((integer_valued_real_p) (X, depth + 1))
13308 /* Return true if the floating point result of (CODE OP0) has an
13309 integer value. We also allow +Inf, -Inf and NaN to be considered
13310 integer values. Return false for signaling NaN.
13312 DEPTH is the current nesting depth of the query. */
13314 bool
13316 {
13318 {
13325 CASE_CONVERT:
13326 {
13333 }
13337 }
13339 }
13341 /* Return true if the floating point result of (CODE OP0 OP1) has an
13342 integer value. We also allow +Inf, -Inf and NaN to be considered
13343 integer values. Return false for signaling NaN.
13345 DEPTH is the current nesting depth of the query. */
13347 bool
13349 {
13351 {
13361 }
13363 }
13365 /* Return true if the floating point result of calling FNDECL with arguments
13366 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13367 considered integer values. Return false for signaling NaN. If FNDECL
13368 takes fewer than 2 arguments, the remaining ARGn are null.
13370 DEPTH is the current nesting depth of the query. */
13372 bool
13374 {
13376 {
13377 CASE_CFN_CEIL:
13378 CASE_CFN_FLOOR:
13379 CASE_CFN_NEARBYINT:
13380 CASE_CFN_RINT:
13381 CASE_CFN_ROUND:
13382 CASE_CFN_TRUNC:
13385 CASE_CFN_FMIN:
13386 CASE_CFN_FMIN_FN:
13387 CASE_CFN_FMAX:
13388 CASE_CFN_FMAX_FN:
13393 }
13395 }
13397 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13398 has an integer value. We also allow +Inf, -Inf and NaN to be
13399 considered integer values. Return false for signaling NaN.
13401 DEPTH is the current nesting depth of the query. */
13403 bool
13405 {
13407 {
13415 /* Limit the depth of recursion to avoid quadratic behavior.
13416 This is expected to catch almost all occurrences in practice.
13417 If this code misses important cases that unbounded recursion
13418 would not, passes that need this information could be revised
13419 to provide it through dataflow propagation. */
13423 depth));
13427 }
13429 }
13431 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13432 has an integer value. We also allow +Inf, -Inf and NaN to be
13433 considered integer values. Return false for signaling NaN.
13435 DEPTH is the current nesting depth of the query. */
13437 static bool
13439 {
13441 {
13452 }
13454 }
13456 #undef RECURSE
13457 #undef integer_valued_real_p
13459 /* Return true if the floating point expression T has an integer value.
13460 We also allow +Inf, -Inf and NaN to be considered integer values.
13461 Return false for signaling NaN.
13463 DEPTH is the current nesting depth of the query. */
13465 bool
13467 {
13473 {
13489 }
13492 {
13498 {
13507 }
13511 }
13512 }
13514 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13515 attempt to fold the expression to a constant without modifying TYPE,
13516 OP0 or OP1.
13518 If the expression could be simplified to a constant, then return
13519 the constant. If the expression would not be simplified to a
13520 constant, then return NULL_TREE. */
13522 tree
13524 {
13527 }
13529 /* Given the components of a unary expression CODE, TYPE and OP0,
13530 attempt to fold the expression to a constant without modifying
13531 TYPE or OP0.
13533 If the expression could be simplified to a constant, then return
13534 the constant. If the expression would not be simplified to a
13535 constant, then return NULL_TREE. */
13537 tree
13539 {
13542 }
13544 /* If EXP represents referencing an element in a constant string
13545 (either via pointer arithmetic or array indexing), return the
13546 tree representing the value accessed, otherwise return NULL. */
13548 tree
13550 {
13554 {
13556 tree index;
13557 tree string;
13562 else
13563 {
13567 /* Optimize the special-case of a zero lower bound.
13569 We convert the low_bound to sizetype to avoid some problems
13570 with constant folding. (E.g. suppose the lower bound is 1,
13571 and its mode is QI. Without the conversion,l (ARRAY
13572 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13573 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13579 }
13581 scalar_int_mode char_mode;
13593 }
13595 }
13597 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13598 an integer constant, real, or fixed-point constant.
13600 TYPE is the type of the result. */
13602 static tree
13604 {
13608 {
13610 {
13617 }
13624 {
13625 FIXED_VALUE_TYPE f;
13630 /* Propagate overflow flags. */
13634 }
13638 }
13641 }
13643 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13644 an integer constant or real constant.
13646 TYPE is the type of the result. */
13648 tree
13650 {
13654 {
13656 {
13657 /* If the value is unsigned or non-negative, then the absolute value
13658 is the same as the ordinary value. */
13662 /* If the value is negative, then the absolute value is
13663 its negation. */
13664 else
13665 {
13670 }
13671 }
13677 else
13683 }
13686 }
13688 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13689 constant. TYPE is the type of the result. */
13691 static tree
13693 {
13697 }
13699 /* Given CODE, a relational operator, the target type, TYPE and two
13700 constant operands OP0 and OP1, return the result of the
13701 relational operation. If the result is not a compile time
13702 constant, then return NULL_TREE. */
13704 static tree
13706 {
13709 /* From here on, the only cases we handle are when the result is
13710 known to be a constant. */
13713 {
13717 /* Handle the cases where either operand is a NaN. */
13719 {
13721 {
13749 }
13752 }
13755 }
13758 {
13762 }
13764 /* Handle equality/inequality of complex constants. */
13766 {
13777 else
13779 }
13782 {
13784 {
13785 /* Have vector comparison with scalar boolean result. */
13789 {
13797 }
13799 }
13800 tree_vector_builder elts;
13805 {
13818 }
13821 }
13823 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13825 To compute GT, swap the arguments and do LT.
13826 To compute GE, do LT and invert the result.
13827 To compute LE, swap the arguments, do LT and invert the result.
13828 To compute NE, do EQ and invert the result.
13830 Therefore, the code below must handle only EQ and LT. */
13833 {
13836 }
13838 /* Note that it is safe to invert for real values here because we
13839 have already handled the one case that it matters. */
13843 {
13846 }
13848 /* Compute a result for LT or EQ if args permit;
13849 Otherwise return T. */
13851 {
13854 else
13856 }
13857 else
13863 }
13865 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
13866 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
13867 itself. */
13869 tree
13871 {
13872 /* If the expression does not have side effects then we don't have to wrap
13873 it with a cleanup point expression. */
13877 /* If the expression is a return, check to see if the expression inside the
13878 return has no side effects or the right hand side of the modify expression
13879 inside the return. If either don't have side effects set we don't need to
13880 wrap the expression in a cleanup point expression. Note we don't check the
13881 left hand side of the modify because it should always be a return decl. */
13883 {
13890 }
13893 }
13895 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13896 of an indirection through OP0, or NULL_TREE if no simplification is
13897 possible. */
13899 tree
13901 {
13903 tree subtype;
13912 {
13915 /* *&CONST_DECL -> to the value of the const decl. */
13918 /* *&p => p; make sure to handle *&"str"[cst] here. */
13920 {
13924 else
13926 }
13927 /* *(foo *)&fooarray => fooarray[0] */
13930 && (!in_gimple_form
13932 {
13942 }
13943 /* *(foo *)&complexfoo => __real__ complexfoo */
13947 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
13950 {
13954 }
13955 }
13959 {
13965 {
13966 tree op00type;
13970 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
13973 {
13975 unsigned HOST_WIDE_INT max_offset
13980 {
13987 }
13988 }
13989 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13992 {
13996 }
13997 /* ((foo *)&fooarray)[1] => fooarray[1] */
14000 {
14007 offset_int remainder;
14010 {
14015 }
14016 }
14017 }
14018 }
14020 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14023 && (!in_gimple_form
14025 {
14026 tree type_domain;
14036 NULL_TREE);
14037 }
14040 }
14042 /* Builds an expression for an indirection through T, simplifying some
14043 cases. */
14045 tree
14047 {
14055 }
14057 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14059 tree
14061 {
14066 else
14068 }
14070 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14071 whose result is ignored. The type of the returned tree need not be
14072 the same as the original expression. */
14074 tree
14076 {
14082 {
14093 else
14099 {
14115 }
14120 }
14121 }
14123 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14125 tree
14127 {
14133 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14134 have to do anything. Only do this when we are not given a const,
14135 because in that case, this check is more expensive than just
14136 doing it. */
14138 {
14143 }
14145 /* If divisor is a power of two, simplify this to bit manipulation. */
14147 {
14149 {
14163 }
14164 else
14165 {
14166 tree t;
14172 }
14173 }
14174 else
14175 {
14180 }
14183 }
14185 /* Likewise, but round down. */
14187 tree
14189 {
14196 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14197 have to do anything. Only do this when we are not given a const,
14198 because in that case, this check is more expensive than just
14199 doing it. */
14201 {
14206 }
14208 /* If divisor is a power of two, simplify this to bit manipulation. */
14210 {
14211 tree t;
14215 }
14216 else
14217 {
14222 }
14225 }
14227 /* Returns the pointer to the base of the object addressed by EXP and
14228 extracts the information about the offset of the access, storing it
14229 to PBITPOS and POFFSET. */
14231 static tree
14234 {
14235 tree core;
14236 machine_mode mode;
14238 HOST_WIDE_INT bitsize;
14242 {
14247 }
14249 {
14255 {
14260 {
14263 }
14264 }
14265 }
14266 else
14267 {
14271 }
14274 }
14276 /* Returns true if addresses of E1 and E2 differ by a constant, false
14277 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14279 bool
14281 {
14295 {
14305 }
14307 {
14308 /* If only one of the offsets is non-constant, the difference cannot
14309 be a constant. */
14311 }
14312 else
14317 }
14319 /* Return OFF converted to a pointer offset type suitable as offset for
14320 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14321 tree
14323 {
14325 }
14327 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14328 tree
14330 {
14333 }
14335 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14336 tree
14338 {
14341 }
14343 /* Return a char pointer for a C string if it is a string constant
14344 or sum of string constant and integer constant. We only support
14345 string constants properly terminated with '\0' character.
14346 If STRLEN is a valid pointer, length (including terminating character)
14347 of returned string is stored to the argument. */
14351 {
14352 tree offset_node;
14363 {
14366 else
14368 }
14373 /* Support only properly null-terminated strings. */
14382 }
14384 #if CHECKING_P
14388 /* Helper functions for writing tests of folding trees. */
14390 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14392 static void
14394 tree constant)
14395 {
14397 }
14399 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14400 wrapping WRAPPED_EXPR. */
14402 static void
14404 tree wrapped_expr)
14405 {
14410 }
14412 /* Verify that various arithmetic binary operations are folded
14413 correctly. */
14415 static void
14417 {
14423 /* Addition. */
14424 /* 1 <-- (0 + 1) */
14426 one);
14428 one);
14430 /* (nonlvalue)x <-- (x + 0) */
14432 x);
14434 /* Subtraction. */
14435 /* 0 <-- (x - x) */
14437 zero);
14439 x);
14441 /* Multiplication. */
14442 /* 0 <-- (x * 0) */
14444 zero);
14446 /* (nonlvalue)x <-- (x * 1) */
14448 x);
14449 }
14451 /* Verify that various binary operations on vectors are folded
14452 correctly. */
14454 static void
14456 {
14462 /* Verify equality tests that return a scalar boolean result. */
14468 }
14470 /* Run all of the selftests within this file. */
14472 void
14474 {
14477 }