| blob | 6f80f1b1d695fd6920ddab46ce8ce8db47bb9ed3 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2018 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. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
414 /* Steps don't prevent negation. */
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a (negative) power of two. */
464 /* Fall through. */
477 /* In general we can't negate A in A / B, because if A is INT_MIN and
478 B is not 1 we change the sign of the result. */
482 /* In general we can't negate B in A / B, because if A is INT_MIN and
483 B is 1, we may turn this into INT_MIN / -1 which is undefined
484 and actually traps on some architectures. */
493 /* Negate -((double)float) as (double)(-float). */
495 {
499 }
503 /* Negate -f(x) as f(-x). */
509 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
511 {
515 }
520 }
522 }
524 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
525 simplification is possible.
526 If negate_expr_p would return true for T, NULL_TREE will never be
527 returned. */
529 static tree
531 {
533 tree tem;
536 {
537 /* Convert - (~A) to A + 1. */
561 {
566 }
570 {
571 tree_vector_builder elts;
575 {
580 }
583 }
606 {
607 /* -(A + B) -> (-B) - A. */
609 {
613 }
615 /* -(A + B) -> (-A) - B. */
617 {
621 }
622 }
626 /* - (A - B) -> B - A */
637 /* Fall through. */
641 {
650 }
658 /* In general we can't negate A in A / B, because if A is INT_MIN and
659 B is not 1 we change the sign of the result. */
665 /* In general we can't negate B in A / B, because if A is INT_MIN and
666 B is 1, we may turn this into INT_MIN / -1 which is undefined
667 and actually traps on some architectures. */
679 /* Convert -((double)float) into (double)(-float). */
681 {
685 }
689 /* Negate -f(x) as f(-x). */
692 {
698 }
702 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
704 {
707 {
714 }
715 }
720 }
723 }
725 /* A wrapper for fold_negate_expr_1. */
727 static tree
729 {
736 }
738 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
739 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
740 return NULL_TREE. */
742 static tree
744 {
746 location_t loc;
759 }
760 \f
761 /* Split a tree IN into a constant, literal and variable parts that could be
762 combined with CODE to make IN. "constant" means an expression with
763 TREE_CONSTANT but that isn't an actual constant. CODE must be a
764 commutative arithmetic operation. Store the constant part into *CONP,
765 the literal in *LITP and return the variable part. If a part isn't
766 present, set it to null. If the tree does not decompose in this way,
767 return the entire tree as the variable part and the other parts as null.
769 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
770 case, we negate an operand that was subtracted. Except if it is a
771 literal for which we use *MINUS_LITP instead.
773 If NEGATE_P is true, we are negating all of IN, again except a literal
774 for which we use *MINUS_LITP instead. If a variable part is of pointer
775 type, it is negated after converting to TYPE. This prevents us from
776 generating illegal MINUS pointer expression. LOC is the location of
777 the converted variable part.
779 If IN is itself a literal or constant, return it as appropriate.
781 Note that we do not guarantee that any of the three values will be the
782 same type as IN, but they will have the same signedness and mode. */
784 static tree
788 {
796 /* Strip any conversions that don't change the machine mode or signedness. */
805 /* We can associate addition and subtraction together (even
806 though the C standard doesn't say so) for integers because
807 the value is not affected. For reals, the value might be
808 affected, so we can't. */
814 {
820 /* First see if either of the operands is a literal, then a constant. */
833 /* If we haven't dealt with either operand, this is not a case we can
834 decompose. Otherwise, VAR is either of the ones remaining, if any. */
839 else
842 /* Now do any needed negations. */
849 }
854 {
855 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
856 when IN is constant. */
859 }
860 else
864 {
877 }
887 }
889 /* Re-associate trees split by the above function. T1 and T2 are
890 either expressions to associate or null. Return the new
891 expression, if any. LOC is the location of the new expression. If
892 we build an operation, do it in TYPE and with CODE. */
894 static tree
896 {
898 {
901 }
905 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
906 try to fold this since we will have infinite recursion. But do
907 deal with any NEGATE_EXPRs. */
911 {
913 {
926 }
928 {
931 }
935 }
939 }
940 \f
941 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
942 for use in int_const_binop, size_binop and size_diffop. */
944 static bool
946 {
953 {
962 }
967 }
969 /* Subroutine of int_const_binop_1 that handles two INTEGER_CSTs. */
971 static tree
974 {
975 wide_int res;
976 tree t;
985 {
1001 {
1005 else
1007 }
1010 /* It's unclear from the C standard whether shifts can overflow.
1011 The following code ignores overflow; perhaps a C standard
1012 interpretation ruling is needed. */
1014 else
1021 {
1025 else
1027 }
1031 else
1110 }
1118 }
1120 /* Combine two integer constants PARG1 and PARG2 under operation CODE
1121 to produce a new constant. Return NULL_TREE if we don't know how
1122 to evaluate CODE at compile-time. */
1124 static tree
1127 {
1134 {
1135 poly_wide_int res;
1140 {
1158 else
1165 else
1178 }
1183 }
1186 }
1188 tree
1190 {
1192 }
1194 /* Return true if binary operation OP distributes over addition in operand
1195 OPNO, with the other operand being held constant. OPNO counts from 1. */
1197 static bool
1199 {
1201 {
1212 }
1213 }
1215 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1216 constant. We assume ARG1 and ARG2 have the same data type, or at least
1217 are the same kind of constant and the same machine mode. Return zero if
1218 combining the constants is not allowed in the current operating mode. */
1220 static tree
1222 {
1223 /* Sanity check for the recursive cases. */
1231 {
1237 }
1240 {
1241 machine_mode mode;
1242 REAL_VALUE_TYPE d1;
1243 REAL_VALUE_TYPE d2;
1244 REAL_VALUE_TYPE value;
1245 REAL_VALUE_TYPE result;
1249 /* The following codes are handled by real_arithmetic. */
1251 {
1262 }
1270 /* Don't perform operation if we honor signaling NaNs and
1271 either operand is a signaling NaN. */
1277 /* Don't perform operation if it would raise a division
1278 by zero exception. */
1284 /* If either operand is a NaN, just return it. Otherwise, set up
1285 for floating-point trap; we return an overflow. */
1287 {
1288 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1289 is off. */
1293 }
1295 {
1296 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1297 is off. */
1301 }
1306 /* Don't constant fold this floating point operation if
1307 the result has overflowed and flag_trapping_math. */
1315 /* Don't constant fold this floating point operation if the
1316 result may dependent upon the run-time rounding mode and
1317 flag_rounding_math is set, or if GCC's software emulation
1318 is unable to accurately represent the result. */
1328 }
1331 {
1332 FIXED_VALUE_TYPE f1;
1333 FIXED_VALUE_TYPE f2;
1334 FIXED_VALUE_TYPE result;
1339 /* The following codes are handled by fixed_arithmetic. */
1341 {
1353 {
1360 }
1365 }
1372 /* Propagate overflow flags. */
1376 }
1379 {
1388 {
1399 mpc_mul);
1413 mpc_div);
1414 /* Fallthru. */
1420 {
1421 /* Keep this algorithm in sync with
1422 tree-complex.c:expand_complex_div_straight().
1424 Expand complex division to scalars, straightforward algorithm.
1425 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1426 t = br*br + bi*bi
1427 */
1428 tree magsquared
1432 tree t1
1436 tree t2
1443 }
1444 else
1445 {
1446 /* Keep this algorithm in sync with
1447 tree-complex.c:expand_complex_div_wide().
1449 Expand complex division to scalars, modified algorithm to minimize
1450 overflow with wide input ranges. */
1456 {
1457 /* In the TRUE branch, we compute
1458 ratio = br/bi;
1459 div = (br * ratio) + bi;
1460 tr = (ar * ratio) + ai;
1461 ti = (ai * ratio) - ar;
1462 tr = tr / div;
1463 ti = ti / div; */
1474 }
1475 else
1476 {
1477 /* In the FALSE branch, we compute
1478 ratio = d/c;
1479 divisor = (d * ratio) + c;
1480 tr = (b * ratio) + a;
1481 ti = b - (a * ratio);
1482 tr = tr / div;
1483 ti = ti / div; */
1495 }
1496 }
1501 }
1505 }
1511 {
1516 /* We can operate directly on the encoding if:
1518 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1519 implies
1520 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1522 Addition and subtraction are the supported operators
1523 for which this is true. */
1526 /* We can operate directly on stepped encodings if:
1528 a3 - a2 == a2 - a1
1529 implies:
1530 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1532 which is true if (x -> x op c) distributes over addition. */
1534 else
1535 /* Similarly in reverse. */
1537 tree_vector_builder elts;
1542 {
1548 /* It is possible that const_binop cannot handle the given
1549 code and return NULL_TREE */
1553 }
1556 }
1558 /* Shifts allow a scalar offset for a vector. */
1561 {
1564 tree_vector_builder elts;
1569 {
1574 /* It is possible that const_binop cannot handle the given
1575 code and return NULL_TREE. */
1579 }
1582 }
1584 }
1586 /* Overload that adds a TYPE parameter to be able to dispatch
1587 to fold_relational_const. */
1589 tree
1591 {
1595 /* ??? Until we make the const_binop worker take the type of the
1596 result as argument put those cases that need it here. */
1598 {
1615 {
1620 }
1626 {
1642 {
1647 ? NOP_EXPR
1654 }
1657 }
1663 {
1686 {
1699 }
1702 }
1705 }
1710 /* Make sure type and arg0 have the same saturating flag. */
1715 }
1717 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1718 Return zero if computing the constants is not possible. */
1720 tree
1722 {
1723 /* Don't perform the operation, other than NEGATE and ABS, if
1724 flag_signaling_nans is on and the operand is a signaling NaN. */
1733 {
1734 CASE_CONVERT:
1741 /* If the source address is 0, and the source address space
1742 cannot have a valid object at 0, fold to dest type null. */
1753 {
1754 /* Can't call fold_negate_const directly here as that doesn't
1755 handle all cases and we might not be able to negate some
1756 constants. */
1761 }
1770 {
1774 }
1782 /* Perform BIT_NOT_EXPR on each element individually. */
1784 {
1785 tree elem;
1787 /* This can cope with stepped encodings because ~x == -1 - x. */
1788 tree_vector_builder elements;
1792 {
1798 }
1801 }
1825 {
1848 else
1853 {
1859 }
1862 }
1871 }
1874 }
1876 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1877 indicates which particular sizetype to create. */
1879 tree
1881 {
1883 }
1884 \f
1885 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1886 is a tree code. The type of the result is taken from the operands.
1887 Both must be equivalent integer types, ala int_binop_types_match_p.
1888 If the operands are constant, so is the result. */
1890 tree
1892 {
1901 /* Handle the special case of two poly_int constants faster. */
1903 {
1904 /* And some specific cases even faster than that. */
1906 {
1911 }
1913 {
1916 }
1918 {
1921 }
1923 /* Handle general case of two integer constants. For sizetype
1924 constant calculations we always want to know about overflow,
1925 even in the unsigned case. */
1929 }
1932 }
1934 /* Given two values, either both of sizetype or both of bitsizetype,
1935 compute the difference between the two values. Return the value
1936 in signed type corresponding to the type of the operands. */
1938 tree
1940 {
1942 tree ctype;
1947 /* If the type is already signed, just do the simple thing. */
1955 else
1958 /* If either operand is not a constant, do the conversions to the signed
1959 type and subtract. The hardware will do the right thing with any
1960 overflow in the subtraction. */
1966 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1967 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1968 overflow) and negate (which can't either). Special-case a result
1969 of zero while we're here. */
1975 else
1979 MINUS_EXPR,
1981 }
1982 \f
1983 /* A subroutine of fold_convert_const handling conversions of an
1984 INTEGER_CST to another integer type. */
1986 static tree
1988 {
1989 /* Given an integer constant, make new constant with new type,
1990 appropriately sign-extended or truncated. Use widest_int
1991 so that any extension is done according ARG1's type. */
1995 }
1997 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1998 to an integer type. */
2000 static tree
2002 {
2004 tree t;
2006 /* The following code implements the floating point to integer
2007 conversion rules required by the Java Language Specification,
2008 that IEEE NaNs are mapped to zero and values that overflow
2009 the target precision saturate, i.e. values greater than
2010 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2011 are mapped to INT_MIN. These semantics are allowed by the
2012 C and C++ standards that simply state that the behavior of
2013 FP-to-integer conversion is unspecified upon overflow. */
2015 wide_int val;
2016 REAL_VALUE_TYPE r;
2020 {
2027 }
2029 /* If R is NaN, return zero and show we have an overflow. */
2031 {
2034 }
2036 /* See if R is less than the lower bound or greater than the
2037 upper bound. */
2040 {
2044 {
2047 }
2048 }
2051 {
2054 {
2057 {
2060 }
2061 }
2062 }
2069 }
2071 /* A subroutine of fold_convert_const handling conversions of a
2072 FIXED_CST to an integer type. */
2074 static tree
2076 {
2077 tree t;
2079 scalar_mode mode;
2081 /* Right shift FIXED_CST to temp by fbit. */
2085 {
2087 HOST_BITS_PER_DOUBLE_INT,
2090 /* Left shift temp to temp_trunc by fbit. */
2092 HOST_BITS_PER_DOUBLE_INT,
2094 }
2095 else
2096 {
2099 }
2101 /* If FIXED_CST is negative, we need to round the value toward 0.
2102 By checking if the fractional bits are not zero to add 1 to temp. */
2108 /* Given a fixed-point constant, make new constant with new type,
2109 appropriately sign-extended or truncated. */
2117 }
2119 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2120 to another floating point type. */
2122 static tree
2124 {
2125 REAL_VALUE_TYPE value;
2126 tree t;
2128 /* Don't perform the operation if flag_signaling_nans is on
2129 and the operand is a signaling NaN. */
2137 /* If converting an infinity or NAN to a representation that doesn't
2138 have one, set the overflow bit so that we can produce some kind of
2139 error message at the appropriate point if necessary. It's not the
2140 most user-friendly message, but it's better than nothing. */
2147 /* Regular overflow, conversion produced an infinity in a mode that
2148 can't represent them. */
2153 else
2156 }
2158 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2159 to a floating point type. */
2161 static tree
2163 {
2164 REAL_VALUE_TYPE value;
2165 tree t;
2173 }
2175 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2176 to another fixed-point type. */
2178 static tree
2180 {
2181 FIXED_VALUE_TYPE value;
2182 tree t;
2189 /* Propagate overflow flags. */
2193 }
2195 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2196 to a fixed-point type. */
2198 static tree
2200 {
2201 FIXED_VALUE_TYPE value;
2202 tree t;
2204 double_int di;
2211 else
2219 /* Propagate overflow flags. */
2223 }
2225 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2226 to a fixed-point type. */
2228 static tree
2230 {
2231 FIXED_VALUE_TYPE value;
2232 tree t;
2240 /* Propagate overflow flags. */
2244 }
2246 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2247 type TYPE. If no simplification can be done return NULL_TREE. */
2249 static tree
2251 {
2256 /* We can't widen types, since the runtime value could overflow the
2257 original type before being extended to the new type. */
2268 {
2275 }
2277 {
2284 }
2286 {
2293 }
2295 {
2298 {
2301 /* We can't handle steps directly when extending, since the
2302 values need to wrap at the original precision first. */
2303 bool step_ok_p
2307 tree_vector_builder v;
2312 {
2318 }
2320 }
2321 }
2323 }
2325 /* Construct a vector of zero elements of vector type TYPE. */
2327 static tree
2329 {
2330 tree t;
2334 }
2336 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2338 bool
2340 {
2355 {
2370 }
2371 }
2373 /* Convert expression ARG to type TYPE. Used by the middle-end for
2374 simple conversions in preference to calling the front-end's convert. */
2376 tree
2378 {
2380 tree tem;
2391 {
2394 /* Handle conversions between pointers to different address spaces. */
2399 /* fall through */
2404 {
2408 }
2422 {
2426 }
2428 {
2432 }
2434 {
2438 }
2441 {
2459 }
2464 {
2468 }
2471 {
2485 }
2489 {
2498 integer_zero_node));
2500 {
2504 {
2510 }
2518 }
2522 }
2540 }
2541 fold_convert_exit:
2544 }
2545 \f
2546 /* Return false if expr can be assumed not to be an lvalue, true
2547 otherwise. */
2549 static bool
2551 {
2552 /* We only need to wrap lvalue tree codes. */
2554 {
2585 /* Assume the worst for front-end tree codes. */
2589 }
2592 }
2594 /* Return an expr equal to X but certainly not valid as an lvalue. */
2596 tree
2598 {
2599 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2600 us. */
2607 }
2609 /* When pedantic, return an expr equal to X but certainly not valid as a
2610 pedantic lvalue. Otherwise, return X. */
2612 static tree
2614 {
2616 }
2617 \f
2618 /* Given a tree comparison code, return the code that is the logical inverse.
2619 It is generally not safe to do this for floating-point comparisons, except
2620 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2621 ERROR_MARK in this case. */
2623 enum tree_code
2625 {
2631 {
2662 }
2663 }
2665 /* Similar, but return the comparison that results if the operands are
2666 swapped. This is safe for floating-point. */
2668 enum tree_code
2670 {
2672 {
2698 }
2699 }
2702 /* Convert a comparison tree code from an enum tree_code representation
2703 into a compcode bit-based encoding. This function is the inverse of
2704 compcode_to_comparison. */
2706 static enum comparison_code
2708 {
2710 {
2741 }
2742 }
2744 /* Convert a compcode bit-based encoding of a comparison operator back
2745 to GCC's enum tree_code representation. This function is the
2746 inverse of comparison_to_compcode. */
2748 static enum tree_code
2750 {
2752 {
2783 }
2784 }
2786 /* Return a tree for the comparison which is the combination of
2787 doing the AND or OR (depending on CODE) of the two operations LCODE
2788 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2789 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2790 if this makes the transformation invalid. */
2792 tree
2797 {
2804 {
2815 }
2818 {
2819 /* Eliminate unordered comparisons, as well as LTGT and ORD
2820 which are not used unless the mode has NaNs. */
2826 }
2828 {
2829 /* Check that the original operation and the optimized ones will trap
2830 under the same condition. */
2841 /* In a short-circuited boolean expression the LHS might be
2842 such that the RHS, if evaluated, will never trap. For
2843 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2844 if neither x nor y is NaN. (This is a mixed blessing: for
2845 example, the expression above will never trap, hence
2846 optimizing it to x < y would be invalid). */
2851 /* If the comparison was short-circuited, and only the RHS
2852 trapped, we may now generate a spurious trap. */
2857 /* If we changed the conditions that cause a trap, we lose. */
2860 }
2866 else
2867 {
2872 }
2873 }
2874 \f
2875 /* Return nonzero if two operands (typically of the same tree node)
2876 are necessarily equal. FLAGS modifies behavior as follows:
2878 If OEP_ONLY_CONST is set, only return nonzero for constants.
2879 This function tests whether the operands are indistinguishable;
2880 it does not test whether they are equal using C's == operation.
2881 The distinction is important for IEEE floating point, because
2882 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2883 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2885 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2886 even though it may hold multiple values during a function.
2887 This is because a GCC tree node guarantees that nothing else is
2888 executed between the evaluation of its "operands" (which may often
2889 be evaluated in arbitrary order). Hence if the operands themselves
2890 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2891 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2892 unset means assuming isochronic (or instantaneous) tree equivalence.
2893 Unless comparing arbitrary expression trees, such as from different
2894 statements, this flag can usually be left unset.
2896 If OEP_PURE_SAME is set, then pure functions with identical arguments
2897 are considered the same. It is used when the caller has other ways
2898 to ensure that global memory is unchanged in between.
2900 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2901 not values of expressions.
2903 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2904 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2906 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2907 any operand with side effect. This is unnecesarily conservative in the
2908 case we know that arg0 and arg1 are in disjoint code paths (such as in
2909 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2910 addresses with TREE_CONSTANT flag set so we know that &var == &var
2911 even if var is volatile. */
2913 int
2915 {
2916 /* When checking, verify at the outermost operand_equal_p call that
2917 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2918 hash value. */
2920 {
2922 {
2924 {
2931 }
2933 }
2934 else
2936 }
2938 /* If either is ERROR_MARK, they aren't equal. */
2944 /* Similar, if either does not have a type (like a released SSA name),
2945 they aren't equal. */
2949 /* We cannot consider pointers to different address space equal. */
2956 /* Check equality of integer constants before bailing out due to
2957 precision differences. */
2959 {
2960 /* Address of INTEGER_CST is not defined; check that we did not forget
2961 to drop the OEP_ADDRESS_OF flags. */
2964 }
2967 {
2968 /* If both types don't have the same signedness, then we can't consider
2969 them equal. We must check this before the STRIP_NOPS calls
2970 because they may change the signedness of the arguments. As pointers
2971 strictly don't have a signedness, require either two pointers or
2972 two non-pointers as well. */
2978 /* If both types don't have the same precision, then it is not safe
2979 to strip NOPs. */
2986 }
2987 #if 0
2988 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2989 sanity check once the issue is solved. */
2990 else
2991 /* Addresses of conversions and SSA_NAMEs (and many other things)
2992 are not defined. Check that we did not forget to drop the
2993 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2996 #endif
2998 /* In case both args are comparisons but with different comparison
2999 code, try to swap the comparison operands of one arg to produce
3000 a match and compare that variant. */
3004 {
3012 }
3015 {
3016 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3018 ;
3020 {
3021 /* If we are interested in comparing addresses ignore
3022 MEM_REF wrappings of the base that can appear just for
3023 TBAA reasons. */
3037 }
3038 else
3040 }
3042 /* When not checking adddresses, this is needed for conversions and for
3043 COMPONENT_REF. Might as well play it safe and always test this. */
3050 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3051 We don't care about side effects in that case because the SAVE_EXPR
3052 takes care of that for us. In all other cases, two expressions are
3053 equal if they have no side effects. If we have two identical
3054 expressions with side effects that should be treated the same due
3055 to the only side effects being identical SAVE_EXPR's, that will
3056 be detected in the recursive calls below.
3057 If we are taking an invariant address of two identical objects
3058 they are necessarily equal as well. */
3065 /* Next handle constant cases, those for which we can return 1 even
3066 if ONLY_CONST is set. */
3069 {
3083 {
3084 /* If we do not distinguish between signed and unsigned zero,
3085 consider them equal. */
3088 }
3092 {
3107 }
3111 flags)
3113 flags));
3124 flags | OEP_ADDRESS_OF
3127 /* In GIMPLE empty constructors are allowed in initializers of
3128 aggregates. */
3132 }
3137 /* Define macros to test an operand from arg0 and arg1 for equality and a
3138 variant that allows null and views null as being different from any
3139 non-null value. In the latter case, if either is null, the both
3140 must be; otherwise, do the normal comparison. */
3141 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3142 TREE_OPERAND (arg1, N), flags)
3144 #define OP_SAME_WITH_NULL(N) \
3145 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3146 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3149 {
3151 /* Two conversions are equal only if signedness and modes match. */
3153 {
3154 CASE_CONVERT:
3162 }
3172 /* For commutative ops, allow the other order. */
3180 /* If either of the pointer (or reference) expressions we are
3181 dereferencing contain a side effect, these cannot be equal,
3182 but their addresses can be. */
3189 {
3199 /* Require the same offset. */
3205 /* Fallthru. */
3213 {
3214 /* Require equal access sizes */
3220 flags)))
3222 /* Verify that access happens in similar types. */
3225 /* Verify that accesses are TBAA compatible. */
3234 /* Verify that alignment is compatible. */
3238 }
3241 /* TARGET_MEM_REF require equal extra operands. */
3252 /* Compare the array index by value if it is constant first as we
3253 may have different types but same value here. */
3259 /* Compare low bound and element size as with OEP_ADDRESS_OF
3260 we have to account for the offset of the ref. */
3265 array_ref_low_bound
3269 array_ref_element_size
3271 flags))));
3274 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3275 may be NULL when we're called to compare MEM_EXPRs. */
3290 }
3294 {
3296 /* Be sure we pass right ADDRESS_OF flag. */
3313 /* The multiplcation operands are commutative. */
3314 /* FALLTHRU */
3322 /* Otherwise take into account this is a commutative operation. */
3335 /* BIT_INSERT_EXPR has an implict operand as the type precision
3336 of op1. Need to check to make sure they are the same. */
3342 /* FALLTHRU */
3367 }
3371 {
3375 /* If not both CALL_EXPRs are either internal or normal function
3376 functions, then they are not equal. */
3379 {
3380 /* If the CALL_EXPRs call different internal functions, then they
3381 are not equal. */
3384 }
3385 else
3386 {
3387 /* If the CALL_EXPRs call different functions, then they are not
3388 equal. */
3390 flags))
3392 }
3394 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3395 {
3399 else
3403 }
3405 /* Now see if all the arguments are the same. */
3406 {
3417 /* If we get here and both argument lists are exhausted
3418 then the CALL_EXPRs are equal. */
3420 }
3423 }
3426 /* Consider __builtin_sqrt equal to sqrt. */
3434 {
3435 /* In GIMPLE constructors are used only to build vectors from
3436 elements. Individual elements in the constructor must be
3437 indexed in increasing order and form an initial sequence.
3439 We make no effort to compare constructors in generic.
3440 (see sem_variable::equals in ipa-icf which can do so for
3441 constants). */
3446 /* Be sure that vectors constructed have the same representation.
3447 We only tested element precision and modes to match.
3448 Vectors may be BLKmode and thus also check that the number of
3449 parts match. */
3462 {
3467 /* In GIMPLE the indexes can be either NULL or matching i.
3468 Double check this so we won't get false
3469 positives for GENERIC. */
3477 }
3479 }
3482 {
3483 /* Compare the STATEMENT_LISTs. */
3489 {
3490 /* The lists don't have the same number of statements. */
3496 flags & (OEP_LEXICOGRAPHIC
3499 }
3500 }
3505 {
3516 }
3520 }
3522 #undef OP_SAME
3523 #undef OP_SAME_WITH_NULL
3524 }
3525 \f
3526 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3527 with a different signedness or a narrower precision. */
3529 static bool
3531 {
3539 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3540 and see if the inner values are the same. This removes any
3541 signedness comparison, which doesn't matter here. */
3549 /* Discard a single widening conversion from ARG1 and see if the inner
3550 value is the same as ARG0. */
3559 }
3560 \f
3561 /* See if ARG is an expression that is either a comparison or is performing
3562 arithmetic on comparisons. The comparisons must only be comparing
3563 two different values, which will be stored in *CVAL1 and *CVAL2; if
3564 they are nonzero it means that some operands have already been found.
3565 No variables may be used anywhere else in the expression except in the
3566 comparisons.
3568 If this is true, return 1. Otherwise, return zero. */
3570 static int
3572 {
3576 /* We can handle some of the tcc_expression cases here. */
3585 {
3604 /* First see if we can handle the first operand, then the second. For
3605 the second operand, we know *CVAL1 can't be zero. It must be that
3606 one side of the comparison is each of the values; test for the
3607 case where this isn't true by failing if the two operands
3608 are the same. */
3617 ;
3621 ;
3622 else
3626 ;
3630 ;
3631 else
3638 }
3639 }
3640 \f
3641 /* ARG is a tree that is known to contain just arithmetic operations and
3642 comparisons. Evaluate the operations in the tree substituting NEW0 for
3643 any occurrence of OLD0 as an operand of a comparison and likewise for
3644 NEW1 and OLD1. */
3646 static tree
3649 {
3654 /* We can handle some of the tcc_expression cases here. */
3662 {
3677 {
3696 }
3697 /* Fall through - ??? */
3700 {
3704 /* We need to check both for exact equality and tree equality. The
3705 former will be true if the operand has a side-effect. In that
3706 case, we know the operand occurred exactly once. */
3719 }
3723 }
3724 }
3725 \f
3726 /* Return a tree for the case when the result of an expression is RESULT
3727 converted to TYPE and OMITTED was previously an operand of the expression
3728 but is now not needed (e.g., we folded OMITTED * 0).
3730 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3731 the conversion of RESULT to TYPE. */
3733 tree
3735 {
3738 /* If the resulting operand is an empty statement, just return the omitted
3739 statement casted to void. */
3749 }
3751 /* Return a tree for the case when the result of an expression is RESULT
3752 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3753 of the expression but are now not needed.
3755 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3756 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3757 evaluated before OMITTED2. Otherwise, if neither has side effects,
3758 just do the conversion of RESULT to TYPE. */
3760 tree
3763 {
3772 }
3774 \f
3775 /* Return a simplified tree node for the truth-negation of ARG. This
3776 never alters ARG itself. We assume that ARG is an operation that
3777 returns a truth value (0 or 1).
3779 FIXME: one would think we would fold the result, but it causes
3780 problems with the dominator optimizer. */
3782 static tree
3784 {
3789 /* If this is a comparison, we can simply invert it, except for
3790 floating-point non-equality comparisons, in which case we just
3791 enclose a TRUTH_NOT_EXPR around what we have. */
3794 {
3797 && flag_trapping_math
3811 }
3814 {
3833 /* Here we can invert either operand. We invert the first operand
3834 unless the second operand is a TRUTH_NOT_EXPR in which case our
3835 result is the XOR of the first operand with the inside of the
3836 negation of the second operand. */
3841 else
3864 {
3871 /* A COND_EXPR may have a throw as one operand, which
3872 then has void type. Just leave void operands
3873 as they are. */
3879 }
3891 CASE_CONVERT:
3895 /* fall through */
3917 }
3918 }
3920 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3921 assume that ARG is an operation that returns a truth value (0 or 1
3922 for scalars, 0 or -1 for vectors). Return the folded expression if
3923 folding is successful. Otherwise, return NULL_TREE. */
3925 static tree
3927 {
3930 ? BIT_NOT_EXPR
3933 }
3935 /* Return a simplified tree node for the truth-negation of ARG. This
3936 never alters ARG itself. We assume that ARG is an operation that
3937 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3939 tree
3941 {
3947 ? BIT_NOT_EXPR
3950 }
3951 \f
3952 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3953 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3954 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3955 is the original memory reference used to preserve the alias set of
3956 the access. */
3958 static tree
3962 {
3965 /* Attempt not to lose the access path if possible. */
3967 {
3969 machine_mode nmode;
3971 tree noffset;
3979 && !reversep
3980 && !nreversep
3982 {
3985 }
3986 }
3995 {
4002 }
4017 }
4019 /* Optimize a bit-field compare.
4021 There are two cases: First is a compare against a constant and the
4022 second is a comparison of two items where the fields are at the same
4023 bit position relative to the start of a chunk (byte, halfword, word)
4024 large enough to contain it. In these cases we can avoid the shift
4025 implicit in bitfield extractions.
4027 For constants, we emit a compare of the shifted constant with the
4028 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4029 compared. For two fields at the same position, we do the ANDs with the
4030 similar mask and compare the result of the ANDs.
4032 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4033 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4034 are the left and right operands of the comparison, respectively.
4036 If the optimization described above can be done, we return the resulting
4037 tree. Otherwise we return zero. */
4039 static tree
4042 {
4046 tree unsigned_type;
4049 scalar_int_mode nmode;
4054 tree mask;
4055 tree offset;
4057 /* Get all the information about the extractions being done. If the bit size
4058 is the same as the size of the underlying object, we aren't doing an
4059 extraction at all and so can do nothing. We also don't want to
4060 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4061 then will no longer be able to replace it. */
4076 else
4077 {
4078 /* If this is not a constant, we can only do something if bit positions,
4079 sizes, signedness and storage order are the same. */
4080 rinner
4093 }
4095 /* Honor the C++ memory model and mimic what RTL expansion does. */
4099 {
4103 }
4105 /* See if we can find a mode to refer to this field. We should be able to,
4106 but fail if we can't. */
4114 /* Set signed and unsigned types of the precision of this mode for the
4115 shifts below. */
4118 /* Compute the bit position and size for the new reference and our offset
4119 within it. If the new reference is the same size as the original, we
4120 won't optimize anything, so return zero. */
4130 /* Make the mask to be used against the extracted field. */
4137 {
4141 /* If not comparing with constant, just rework the comparison
4142 and return. */
4150 }
4152 /* Otherwise, we are handling the constant case. See if the constant is too
4153 big for the field. Warn and return a tree for 0 (false) if so. We do
4154 this not only for its own sake, but to avoid having to test for this
4155 error case below. If we didn't, we might generate wrong code.
4157 For unsigned fields, the constant shifted right by the field length should
4158 be all zero. For signed fields, the high-order bits should agree with
4159 the sign bit. */
4162 {
4164 {
4168 }
4169 }
4170 else
4171 {
4174 {
4178 }
4179 }
4184 /* Single-bit compares should always be against zero. */
4186 {
4189 }
4191 /* Make a new bitfield reference, shift the constant over the
4192 appropriate number of bits and mask it with the computed mask
4193 (in case this was a signed field). If we changed it, make a new one. */
4201 mask);
4206 }
4207 \f
4208 /* Subroutine for fold_truth_andor_1: decode a field reference.
4210 If EXP is a comparison reference, we return the innermost reference.
4212 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4213 set to the starting bit number.
4215 If the innermost field can be completely contained in a mode-sized
4216 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4218 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4219 otherwise it is not changed.
4221 *PUNSIGNEDP is set to the signedness of the field.
4223 *PREVERSEP is set to the storage order of the field.
4225 *PMASK is set to the mask used. This is either contained in a
4226 BIT_AND_EXPR or derived from the width of the field.
4228 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4230 Return 0 if this is not a component reference or is one that we can't
4231 do anything with. */
4233 static tree
4238 {
4243 tree unsigned_type;
4246 /* All the optimizations using this function assume integer fields.
4247 There are problems with FP fields since the type_for_size call
4248 below can fail for, e.g., XFmode. */
4252 /* We are interested in the bare arrangement of bits, so strip everything
4253 that doesn't affect the machine mode. However, record the type of the
4254 outermost expression if it may matter below. */
4261 {
4267 }
4278 /* Reject out-of-bound accesses (PR79731). */
4286 /* If the number of bits in the reference is the same as the bitsize of
4287 the outer type, then the outer type gives the signedness. Otherwise
4288 (in case of a small bitfield) the signedness is unchanged. */
4292 /* Compute the mask to access the bitfield. */
4301 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4309 }
4311 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4312 bit positions and MASK is SIGNED. */
4314 static int
4316 {
4320 /* If this function returns true when the type of the mask is
4321 UNSIGNED, then there will be errors. In particular see
4322 gcc.c-torture/execute/990326-1.c. There does not appear to be
4323 any documentation paper trail as to why this is so. But the pre
4324 wide-int worked with that restriction and it has been preserved
4325 here. */
4330 }
4332 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4333 represents the sign bit of EXP's type. If EXP represents a sign
4334 or zero extension, also test VAL against the unextended type.
4335 The return value is the (sub)expression whose sign bit is VAL,
4336 or NULL_TREE otherwise. */
4338 tree
4340 {
4342 tree t;
4344 /* Tree EXP must have an integral type. */
4349 /* Tree VAL must be an integer constant. */
4358 /* Handle extension from a narrower type. */
4364 }
4366 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4367 to be evaluated unconditionally. */
4369 static int
4371 {
4372 /* Strip any conversions that don't change the machine mode. */
4381 /* Don't regard global variables as simple. They may be
4382 allocated in ways unknown to the compiler (shared memory,
4383 #pragma weak, etc). */
4386 /* Weakrefs are not safe to be read, since they can be NULL.
4387 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4388 have DECL_WEAK flag set. */
4390 /* Loading a static variable is unduly expensive, but global
4391 registers aren't expensive. */
4393 }
4395 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4396 to be evaluated unconditionally.
4397 I addition to simple_operand_p, we assume that comparisons, conversions,
4398 and logic-not operations are simple, if their operands are simple, too. */
4400 static bool
4402 {
4422 }
4424 \f
4425 /* The following functions are subroutines to fold_range_test and allow it to
4426 try to change a logical combination of comparisons into a range test.
4428 For example, both
4429 X == 2 || X == 3 || X == 4 || X == 5
4430 and
4431 X >= 2 && X <= 5
4432 are converted to
4433 (unsigned) (X - 2) <= 3
4435 We describe each set of comparisons as being either inside or outside
4436 a range, using a variable named like IN_P, and then describe the
4437 range with a lower and upper bound. If one of the bounds is omitted,
4438 it represents either the highest or lowest value of the type.
4440 In the comments below, we represent a range by two numbers in brackets
4441 preceded by a "+" to designate being inside that range, or a "-" to
4442 designate being outside that range, so the condition can be inverted by
4443 flipping the prefix. An omitted bound is represented by a "-". For
4444 example, "- [-, 10]" means being outside the range starting at the lowest
4445 possible value and ending at 10, in other words, being greater than 10.
4446 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4447 always false.
4449 We set up things so that the missing bounds are handled in a consistent
4450 manner so neither a missing bound nor "true" and "false" need to be
4451 handled using a special case. */
4453 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4454 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4455 and UPPER1_P are nonzero if the respective argument is an upper bound
4456 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4457 must be specified for a comparison. ARG1 will be converted to ARG0's
4458 type if both are specified. */
4460 static tree
4463 {
4464 tree tem;
4468 /* If neither arg represents infinity, do the normal operation.
4469 Else, if not a comparison, return infinity. Else handle the special
4470 comparison rules. Note that most of the cases below won't occur, but
4471 are handled for consistency. */
4474 {
4479 }
4484 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4485 for neither. In real maths, we cannot assume open ended ranges are
4486 the same. But, this is computer arithmetic, where numbers are finite.
4487 We can therefore make the transformation of any unbounded range with
4488 the value Z, Z being greater than any representable number. This permits
4489 us to treat unbounded ranges as equal. */
4493 {
4514 }
4517 }
4518 \f
4519 /* Helper routine for make_range. Perform one step for it, return
4520 new expression if the loop should continue or NULL_TREE if it should
4521 stop. */
4523 tree
4527 {
4533 {
4535 /* We can only do something if the range is testing for zero. */
4544 /* We can only do something if the range is testing for zero
4545 and if the second operand is an integer constant. Note that
4546 saying something is "in" the range we make is done by
4547 complementing IN_P since it will set in the initial case of
4548 being not equal to zero; "out" is leaving it alone. */
4555 {
4576 }
4578 /* If this is an unsigned comparison, we also know that EXP is
4579 greater than or equal to zero. We base the range tests we make
4580 on that fact, so we record it here so we can parse existing
4581 range tests. We test arg0_type since often the return type
4582 of, e.g. EQ_EXPR, is boolean. */
4584 {
4588 NULL_TREE))
4593 /* If the high bound is missing, but we have a nonzero low
4594 bound, reverse the range so it goes from zero to the low bound
4595 minus 1. */
4597 {
4602 }
4603 }
4611 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4612 low and high are non-NULL, then normalize will DTRT. */
4615 {
4620 }
4622 /* (-x) IN [a,b] -> x in [-b, -a] */
4634 /* ~ X -> -X - 1 */
4643 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4644 move a constant to the other side. */
4649 /* If EXP is signed, any overflow in the computation is undefined,
4650 so we don't worry about it so long as our computations on
4651 the bounds don't overflow. For unsigned, overflow is defined
4652 and this is exactly the right thing. */
4664 normalize:
4665 /* Check for an unsigned range which has wrapped around the maximum
4666 value thus making n_high < n_low, and normalize it. */
4668 {
4674 /* If the range is of the form +/- [ x+1, x ], we won't
4675 be able to normalize it. But then, it represents the
4676 whole range or the empty set, so make it
4677 +/- [ -, - ]. */
4681 else
4683 }
4684 else
4692 CASE_CONVERT:
4710 /* If we're converting arg0 from an unsigned type, to exp,
4711 a signed type, we will be doing the comparison as unsigned.
4712 The tests above have already verified that LOW and HIGH
4713 are both positive.
4715 So we have to ensure that we will handle large unsigned
4716 values the same way that the current signed bounds treat
4717 negative values. */
4720 {
4721 tree high_positive;
4722 tree equiv_type;
4723 /* For fixed-point modes, we need to pass the saturating flag
4724 as the 2nd parameter. */
4726 equiv_type
4729 else
4730 equiv_type
4733 /* A range without an upper bound is, naturally, unbounded.
4734 Since convert would have cropped a very large value, use
4735 the max value for the destination type. */
4736 high_positive
4743 high_positive),
4746 /* If the low bound is specified, "and" the range with the
4747 range for which the original unsigned value will be
4748 positive. */
4750 {
4753 integer_zero_node),
4754 high_positive))
4758 }
4759 else
4760 {
4761 /* Otherwise, "or" the range with the range of the input
4762 that will be interpreted as negative. */
4765 integer_zero_node),
4766 high_positive))
4770 }
4771 }
4780 }
4781 }
4783 /* Given EXP, a logical expression, set the range it is testing into
4784 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4785 actually being tested. *PLOW and *PHIGH will be made of the same
4786 type as the returned expression. If EXP is not a comparison, we
4787 will most likely not be returning a useful value and range. Set
4788 *STRICT_OVERFLOW_P to true if the return value is only valid
4789 because signed overflow is undefined; otherwise, do not change
4790 *STRICT_OVERFLOW_P. */
4792 tree
4795 {
4803 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4804 and see if we can refine the range. Some of the cases below may not
4805 happen, but it doesn't seem worth worrying about this. We "continue"
4806 the outer loop when we've changed something; otherwise we "break"
4807 the switch, which will "break" the while. */
4813 {
4819 {
4827 }
4836 }
4838 /* If EXP is a constant, we can evaluate whether this is true or false. */
4840 {
4847 }
4851 }
4853 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4854 a bitwise check i.e. when
4855 LOW == 0xXX...X00...0
4856 HIGH == 0xXX...X11...1
4857 Return corresponding mask in MASK and stem in VALUE. */
4859 static bool
4862 {
4885 }
4886 \f
4887 /* Helper routine for build_range_check and match.pd. Return the type to
4888 perform the check or NULL if it shouldn't be optimized. */
4890 tree
4892 {
4893 /* First make sure that arithmetics in this type is valid, then make sure
4894 that it wraps around. */
4900 {
4903 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4904 for the type in question, as we rely on this here. */
4914 else
4916 }
4918 }
4920 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4921 type, TYPE, return an expression to test if EXP is in (or out of, depending
4922 on IN_P) the range. Return 0 if the test couldn't be created. */
4924 tree
4927 {
4930 /* Disable this optimization for function pointer expressions
4931 on targets that require function pointer canonicalization. */
4938 {
4944 }
4966 value);
4969 {
4971 {
4975 }
4977 }
4979 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4981 {
4985 {
4987 {
4990 etype
4992 else
4995 }
4998 }
4999 }
5001 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5002 This requires wrap-around arithmetics for the type of the expression. */
5022 }
5023 \f
5024 /* Return the predecessor of VAL in its type, handling the infinite case. */
5026 static tree
5028 {
5034 else
5037 }
5039 /* Return the successor of VAL in its type, handling the infinite case. */
5041 static tree
5043 {
5049 else
5052 }
5054 /* Given two ranges, see if we can merge them into one. Return 1 if we
5055 can, 0 if we can't. Set the output range into the specified parameters. */
5057 bool
5060 {
5064 tree tem;
5074 /* Make range 0 be the range that starts first, or ends last if they
5075 start at the same value. Swap them if it isn't. */
5078 || (lowequal
5081 {
5085 }
5087 /* Now flag two cases, whether the ranges are disjoint or whether the
5088 second range is totally subsumed in the first. Note that the tests
5089 below are simplified by the ones above. */
5095 /* We now have four cases, depending on whether we are including or
5096 excluding the two ranges. */
5098 {
5099 /* If they don't overlap, the result is false. If the second range
5100 is a subset it is the result. Otherwise, the range is from the start
5101 of the second to the end of the first. */
5106 else
5108 }
5111 {
5112 /* If they don't overlap, the result is the first range. If they are
5113 equal, the result is false. If the second range is a subset of the
5114 first, and the ranges begin at the same place, we go from just after
5115 the end of the second range to the end of the first. If the second
5116 range is not a subset of the first, or if it is a subset and both
5117 ranges end at the same place, the range starts at the start of the
5118 first range and ends just before the second range.
5119 Otherwise, we can't describe this as a single range. */
5125 {
5130 {
5131 /* We are in the weird situation where high0 > high1 but
5132 high1 has no successor. Punt. */
5134 }
5135 }
5137 {
5142 {
5143 /* low0 < low1 but low1 has no predecessor. Punt. */
5145 }
5146 }
5147 else
5149 }
5152 {
5153 /* If they don't overlap, the result is the second range. If the second
5154 is a subset of the first, the result is false. Otherwise,
5155 the range starts just after the first range and ends at the
5156 end of the second. */
5161 else
5162 {
5167 {
5168 /* high1 > high0 but high0 has no successor. Punt. */
5170 }
5171 }
5172 }
5174 else
5175 {
5176 /* The case where we are excluding both ranges. Here the complex case
5177 is if they don't overlap. In that case, the only time we have a
5178 range is if they are adjacent. If the second is a subset of the
5179 first, the result is the first. Otherwise, the range to exclude
5180 starts at the beginning of the first range and ends at the end of the
5181 second. */
5183 {
5188 else
5189 {
5190 /* Canonicalize - [min, x] into - [-, x]. */
5193 {
5196 GET_MODE_BITSIZE
5199 /* FALLTHROUGH */
5212 }
5214 /* Canonicalize - [x, max] into - [x, -]. */
5217 {
5220 GET_MODE_BITSIZE
5223 /* FALLTHROUGH */
5239 }
5241 /* The ranges might be also adjacent between the maximum and
5242 minimum values of the given type. For
5243 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5244 return + [x + 1, y - 1]. */
5246 {
5253 }
5254 else
5256 }
5257 }
5260 else
5262 }
5266 }
5267 \f
5269 /* Subroutine of fold, looking inside expressions of the form
5270 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5271 of the COND_EXPR. This function is being used also to optimize
5272 A op B ? C : A, by reversing the comparison first.
5274 Return a folded expression whose code is not a COND_EXPR
5275 anymore, or NULL_TREE if no folding opportunity is found. */
5277 static tree
5280 {
5285 tree tem;
5290 /* If we have A op 0 ? A : -A, consider applying the following
5291 transformations:
5293 A == 0? A : -A same as -A
5294 A != 0? A : -A same as A
5295 A >= 0? A : -A same as abs (A)
5296 A > 0? A : -A same as abs (A)
5297 A <= 0? A : -A same as -abs (A)
5298 A < 0? A : -A same as -abs (A)
5300 None of these transformations work for modes with signed
5301 zeros. If A is +/-0, the first two transformations will
5302 change the sign of the result (from +0 to -0, or vice
5303 versa). The last four will fix the sign of the result,
5304 even though the original expressions could be positive or
5305 negative, depending on the sign of A.
5307 Note that all these transformations are correct if A is
5308 NaN, since the two alternatives (A and -A) are also NaNs. */
5315 /* In the case that A is of the form X-Y, '-A' (arg2) may
5316 have already been folded to Y-X, check for that. */
5324 {
5336 /* Fall through. */
5347 /* FALLTHRU */
5357 }
5359 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5360 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5361 both transformations are correct when A is NaN: A != 0
5362 is then true, and A == 0 is false. */
5366 {
5371 }
5373 /* Try some transformations of A op B ? A : B.
5375 A == B? A : B same as B
5376 A != B? A : B same as A
5377 A >= B? A : B same as max (A, B)
5378 A > B? A : B same as max (B, A)
5379 A <= B? A : B same as min (A, B)
5380 A < B? A : B same as min (B, A)
5382 As above, these transformations don't work in the presence
5383 of signed zeros. For example, if A and B are zeros of
5384 opposite sign, the first two transformations will change
5385 the sign of the result. In the last four, the original
5386 expressions give different results for (A=+0, B=-0) and
5387 (A=-0, B=+0), but the transformed expressions do not.
5389 The first two transformations are correct if either A or B
5390 is a NaN. In the first transformation, the condition will
5391 be false, and B will indeed be chosen. In the case of the
5392 second transformation, the condition A != B will be true,
5393 and A will be chosen.
5395 The conversions to max() and min() are not correct if B is
5396 a number and A is not. The conditions in the original
5397 expressions will be false, so all four give B. The min()
5398 and max() versions would give a NaN instead. */
5401 /* Avoid these transformations if the COND_EXPR may be used
5402 as an lvalue in the C++ front-end. PR c++/19199. */
5403 && (in_gimple_form
5409 {
5415 {
5424 /* In C++ a ?: expression can be an lvalue, so put the
5425 operand which will be used if they are equal first
5426 so that we can convert this back to the
5427 corresponding COND_EXPR. */
5429 {
5437 }
5444 {
5452 }
5465 }
5466 }
5469 }
5472 \f
5473 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5474 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5475 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5476 false) >= 2)
5477 #endif
5479 /* EXP is some logical combination of boolean tests. See if we can
5480 merge it into some range test. Return the new tree if so. */
5482 static tree
5485 {
5501 /* If this is an OR operation, invert both sides; we will invert
5502 again at the end. */
5506 /* If both expressions are the same, if we can merge the ranges, and we
5507 can build the range test, return it or it inverted. If one of the
5508 ranges is always true or always false, consider it to be the same
5509 expression as the other. */
5517 {
5521 }
5523 /* On machines where the branch cost is expensive, if this is a
5524 short-circuited branch and the underlying object on both sides
5525 is the same, make a non-short-circuit operation. */
5527 && !flag_sanitize_coverage
5532 {
5533 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5534 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5535 which cases we can't do this. */
5543 {
5552 {
5555 WARN_STRICT_OVERFLOW_COMPARISON);
5559 }
5560 }
5561 }
5564 }
5565 \f
5566 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5567 bit value. Arrange things so the extra bits will be set to zero if and
5568 only if C is signed-extended to its full width. If MASK is nonzero,
5569 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5571 static tree
5573 {
5576 tree temp;
5581 /* We work by getting just the sign bit into the low-order bit, then
5582 into the high-order bit, then sign-extend. We then XOR that value
5583 with C. */
5587 /* We must use a signed type in order to get an arithmetic right shift.
5588 However, we must also avoid introducing accidental overflows, so that
5589 a subsequent call to integer_zerop will work. Hence we must
5590 do the type conversion here. At this point, the constant is either
5591 zero or one, and the conversion to a signed type can never overflow.
5592 We could get an overflow if this conversion is done anywhere else. */
5601 /* If necessary, convert the type back to match the type of C. */
5606 }
5607 \f
5608 /* For an expression that has the form
5609 (A && B) || ~B
5610 or
5611 (A || B) && ~B,
5612 we can drop one of the inner expressions and simplify to
5613 A || ~B
5614 or
5615 A && ~B
5616 LOC is the location of the resulting expression. OP is the inner
5617 logical operation; the left-hand side in the examples above, while CMPOP
5618 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5619 removing a condition that guards another, as in
5620 (A != NULL && A->...) || A == NULL
5621 which we must not transform. If RHS_ONLY is true, only eliminate the
5622 right-most operand of the inner logical operation. */
5624 static tree
5627 {
5645 {
5648 {
5651 }
5652 }
5654 {
5657 {
5660 }
5661 }
5676 }
5678 /* Find ways of folding logical expressions of LHS and RHS:
5679 Try to merge two comparisons to the same innermost item.
5680 Look for range tests like "ch >= '0' && ch <= '9'".
5681 Look for combinations of simple terms on machines with expensive branches
5682 and evaluate the RHS unconditionally.
5684 For example, if we have p->a == 2 && p->b == 4 and we can make an
5685 object large enough to span both A and B, we can do this with a comparison
5686 against the object ANDed with the a mask.
5688 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5689 operations to do this with one comparison.
5691 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5692 function and the one above.
5694 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5695 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5697 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5698 two operands.
5700 We return the simplified tree or 0 if no optimization is possible. */
5702 static tree
5705 {
5706 /* If this is the "or" of two comparisons, we can do something if
5707 the comparisons are NE_EXPR. If this is the "and", we can do something
5708 if the comparisons are EQ_EXPR. I.e.,
5709 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5711 WANTED_CODE is this operation code. For single bit fields, we can
5712 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5713 comparison for one-bit fields. */
5734 /* Start by getting the comparison codes. Fail if anything is volatile.
5735 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5736 it were surrounded with a NE_EXPR. */
5745 {
5749 }
5752 {
5756 }
5767 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5770 {
5773 {
5778 }
5781 {
5787 }
5788 }
5793 /* If the RHS can be evaluated unconditionally and its operands are
5794 simple, it wins to evaluate the RHS unconditionally on machines
5795 with expensive branches. In this case, this isn't a comparison
5796 that can be merged. */
5803 {
5804 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5815 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5825 }
5827 /* See if the comparisons can be merged. Then get all the parameters for
5828 each side. */
5853 /* It must be true that the inner operation on the lhs of each
5854 comparison must be the same if we are to be able to do anything.
5855 Then see if we have constants. If not, the same must be true for
5856 the rhs's. */
5865 {
5868 }
5873 else
5876 /* If either comparison code is not correct for our logical operation,
5877 fail. However, we can convert a one-bit comparison against zero into
5878 the opposite comparison against that bit being set in the field. */
5882 {
5884 {
5885 /* Make the left operand unsigned, since we are only interested
5886 in the value of one bit. Otherwise we are doing the wrong
5887 thing below. */
5890 }
5891 else
5893 }
5895 /* This is analogous to the code for l_const above. */
5897 {
5899 {
5902 }
5903 else
5905 }
5907 /* See if we can find a mode that contains both fields being compared on
5908 the left. If we can't, fail. Otherwise, update all constants and masks
5909 to be relative to a field of that size. */
5923 {
5926 }
5934 {
5941 {
5945 }
5946 }
5948 {
5955 {
5959 }
5960 }
5962 /* If the right sides are not constant, do the same for it. Also,
5963 disallow this optimization if a size or signedness mismatch occurs
5964 between the left and right sides. */
5966 {
5969 /* Make sure the two fields on the right
5970 correspond to the left without being swapped. */
5987 {
5990 }
5999 /* Make a mask that corresponds to both fields being compared.
6000 Do this for both items being compared. If the operands are the
6001 same size and the bits being compared are in the same position
6002 then we can do this by masking both and comparing the masked
6003 results. */
6010 {
6024 }
6026 /* There is still another way we can do something: If both pairs of
6027 fields being compared are adjacent, we may be able to make a wider
6028 field containing them both.
6030 Note that we still must mask the lhs/rhs expressions. Furthermore,
6031 the mask must be shifted to account for the shift done by
6032 make_bit_field_ref. */
6041 {
6042 tree type;
6058 /* Convert to the smaller type before masking out unwanted bits. */
6061 {
6063 {
6067 }
6069 {
6073 }
6074 }
6083 }
6086 }
6088 /* Handle the case of comparisons with constants. If there is something in
6089 common between the masks, those bits of the constants must be the same.
6090 If not, the condition is always false. Test for this to avoid generating
6091 incorrect code below. */
6096 {
6098 {
6101 }
6102 else
6103 {
6106 }
6107 }
6112 /* Construct the expression we will return. First get the component
6113 reference we will make. Unless the mask is all ones the width of
6114 that field, perform the mask operation. Then compare with the
6115 merged constant. */
6126 }
6127 \f
6128 /* T is an integer expression that is being multiplied, divided, or taken a
6129 modulus (CODE says which and what kind of divide or modulus) by a
6130 constant C. See if we can eliminate that operation by folding it with
6131 other operations already in T. WIDE_TYPE, if non-null, is a type that
6132 should be used for the computation if wider than our type.
6134 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6135 (X * 2) + (Y * 4). We must, however, be assured that either the original
6136 expression would not overflow or that overflow is undefined for the type
6137 in the language in question.
6139 If we return a non-null expression, it is an equivalent form of the
6140 original computation, but need not be in the original type.
6142 We set *STRICT_OVERFLOW_P to true if the return values depends on
6143 signed overflow being undefined. Otherwise we do not change
6144 *STRICT_OVERFLOW_P. */
6146 static tree
6149 {
6150 /* To avoid exponential search depth, refuse to allow recursion past
6151 three levels. Beyond that (1) it's highly unlikely that we'll find
6152 something interesting and (2) we've probably processed it before
6153 when we built the inner expression. */
6156 tree ret;
6161 depth++;
6163 depth--;
6166 }
6168 static tree
6171 {
6183 /* Don't deal with constants of zero here; they confuse the code below. */
6193 /* Note that we need not handle conditional operations here since fold
6194 already handles those cases. So just do arithmetic here. */
6196 {
6198 /* For a constant, we can always simplify if we are a multiply
6199 or (for divide and modulus) if it is a multiple of our constant. */
6203 {
6206 /* If the multiplication overflowed, we lost information on it.
6207 See PR68142 and PR69845. */
6211 }
6215 /* If op0 is an expression ... */
6221 /* ... and has wrapping overflow, and its type is smaller
6222 than ctype, then we cannot pass through as widening. */
6227 /* ... or this is a truncation (t is narrower than op0),
6228 then we cannot pass through this narrowing. */
6231 /* ... or signedness changes for division or modulus,
6232 then we cannot pass through this conversion. */
6236 /* ... or has undefined overflow while the converted to
6237 type has not, we cannot do the operation in the inner type
6238 as that would introduce undefined overflow. */
6244 /* Pass the constant down and see if we can make a simplification. If
6245 we can, replace this expression with the inner simplification for
6246 possible later conversion to our or some other type. */
6257 /* If widening the type changes it from signed to unsigned, then we
6258 must avoid building ABS_EXPR itself as unsigned. */
6260 {
6264 {
6267 }
6269 }
6270 /* If the constant is negative, we cannot simplify this. */
6273 /* FALLTHROUGH */
6275 /* For division and modulus, type can't be unsigned, as e.g.
6276 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6277 For signed types, even with wrapping overflow, this is fine. */
6286 /* If widening the type changes the signedness, then we can't perform
6287 this optimization as that changes the result. */
6291 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6297 {
6304 }
6308 /* If the second operand is constant, this is a multiplication
6309 or floor division, by a power of two, so we can treat it that
6310 way unless the multiplier or divisor overflows. Signed
6311 left-shift overflow is implementation-defined rather than
6312 undefined in C90, so do not convert signed left shift into
6313 multiplication. */
6316 /* const_binop may not detect overflow correctly,
6317 so check for it explicitly here. */
6326 ctype,
6328 t1),
6333 /* See if we can eliminate the operation on both sides. If we can, we
6334 can return a new PLUS or MINUS. If we can't, the only remaining
6335 cases where we can do anything are if the second operand is a
6336 constant. */
6343 /* If not multiplication, we can only do this if both operands
6344 are divisible by c. */
6347 {
6352 }
6354 /* If this was a subtraction, negate OP1 and set it to be an addition.
6355 This simplifies the logic below. */
6357 {
6359 /* If OP1 was not easily negatable, the constant may be OP0. */
6361 {
6364 }
6365 }
6370 /* If either OP1 or C are negative, this optimization is not safe for
6371 some of the division and remainder types while for others we need
6372 to change the code. */
6374 {
6382 }
6384 /* If it's a multiply or a division/modulus operation of a multiple
6385 of our constant, do the operation and verify it doesn't overflow. */
6389 {
6392 /* We allow the constant to overflow with wrapping semantics. */
6396 }
6397 else
6400 /* If we have an unsigned type, we cannot widen the operation since it
6401 will change the result if the original computation overflowed. */
6405 /* The last case is if we are a multiply. In that case, we can
6406 apply the distributive law to commute the multiply and addition
6407 if the multiplication of the constants doesn't overflow
6408 and overflow is defined. With undefined overflow
6409 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6415 op1);
6420 /* We have a special case here if we are doing something like
6421 (C * 8) % 4 since we know that's zero. */
6424 /* If the multiplication can overflow we cannot optimize this. */
6429 {
6432 }
6434 /* ... fall through ... */
6438 /* If we can extract our operation from the LHS, do so and return a
6439 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6440 do something only if the second operand is a constant. */
6456 /* If these are the same operation types, we can associate them
6457 assuming no overflow. */
6459 {
6474 }
6476 /* If these operations "cancel" each other, we have the main
6477 optimizations of this pass, which occur when either constant is a
6478 multiple of the other, in which case we replace this with either an
6479 operation or CODE or TCODE.
6481 If we have an unsigned type, we cannot do this since it will change
6482 the result if the original computation overflowed. */
6489 {
6492 {
6499 }
6502 {
6509 }
6510 }
6515 }
6518 }
6519 \f
6520 /* Return a node which has the indicated constant VALUE (either 0 or
6521 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6522 and is of the indicated TYPE. */
6524 tree
6526 {
6535 else
6537 }
6540 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6541 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6542 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6543 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6544 COND is the first argument to CODE; otherwise (as in the example
6545 given here), it is the second argument. TYPE is the type of the
6546 original expression. Return NULL_TREE if no simplification is
6547 possible. */
6549 static tree
6554 {
6564 {
6568 /* If this operand throws an expression, then it does not make
6569 sense to try to perform a logical or arithmetic operation
6570 involving it. */
6575 }
6578 {
6583 }
6584 else
6585 /* Detect the case of mixing vector and scalar types - bail out. */
6591 /* This transformation is only worthwhile if we don't have to wrap ARG
6592 in a SAVE_EXPR and the operation can be simplified without recursing
6593 on at least one of the branches once its pushed inside the COND_EXPR. */
6602 {
6606 else
6608 }
6610 {
6614 else
6616 }
6618 /* Check that we have simplified at least one of the branches. */
6623 }
6625 \f
6626 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6628 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6629 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6630 ADDEND is the same as X.
6632 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6633 and finite. The problematic cases are when X is zero, and its mode
6634 has signed zeros. In the case of rounding towards -infinity,
6635 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6636 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6638 bool
6640 {
6644 /* Don't allow the fold with -fsignaling-nans. */
6648 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6652 /* In a vector or complex, we would need to check the sign of all zeros. */
6656 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6660 /* The mode has signed zeros, and we have to honor their sign.
6661 In this situation, there is only one case we can return true for.
6662 X - 0 is the same as X unless rounding towards -infinity is
6663 supported. */
6665 }
6667 /* Subroutine of match.pd that optimizes comparisons of a division by
6668 a nonzero integer constant against an integer constant, i.e.
6669 X/C1 op C2.
6671 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6672 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6674 enum tree_code
6677 {
6682 /* We have to do this the hard way to detect unsigned overflow.
6683 prod = int_const_binop (MULT_EXPR, c1, c2); */
6689 {
6693 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6696 }
6698 {
6701 {
6720 }
6721 }
6722 else
6723 {
6724 /* A negative divisor reverses the relational operators. */
6729 {
6748 }
6749 }
6762 }
6765 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6766 equality/inequality test, then return a simplified form of the test
6767 using a sign testing. Otherwise return NULL. TYPE is the desired
6768 result type. */
6770 static tree
6773 tree result_type)
6774 {
6775 /* If this is testing a single bit, we can optimize the test. */
6779 {
6780 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6781 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6785 /* This is only a win if casting to a signed type is cheap,
6786 i.e. when arg00's type is not a partial mode. */
6788 {
6791 result_type,
6794 }
6795 }
6798 }
6800 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6801 equality/inequality test, then return a simplified form of
6802 the test using shifts and logical operations. Otherwise return
6803 NULL. TYPE is the desired result type. */
6805 tree
6808 {
6809 /* If this is testing a single bit, we can optimize the test. */
6813 {
6822 /* First, see if we can fold the single bit test into a sign-bit
6823 test. */
6825 result_type);
6829 /* Otherwise we have (A & C) != 0 where C is a single bit,
6830 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6831 Similarly for (A & C) == 0. */
6833 /* If INNER is a right shift of a constant and it plus BITNUM does
6834 not overflow, adjust BITNUM and INNER. */
6840 {
6843 }
6845 /* If we are going to be able to omit the AND below, we must do our
6846 operations as unsigned. If we must use the AND, we have a choice.
6847 Normally unsigned is faster, but for some machines signed is. */
6865 /* Put the AND last so it can combine with more things. */
6868 /* Make sure to return the proper type. */
6872 }
6874 }
6876 /* Test whether it is preferable two swap two operands, ARG0 and
6877 ARG1, for example because ARG0 is an integer constant and ARG1
6878 isn't. */
6880 bool
6882 {
6896 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6897 for commutative and comparison operators. Ensuring a canonical
6898 form allows the optimizers to find additional redundancies without
6899 having to explicitly check for both orderings. */
6905 /* Put SSA_NAMEs last. */
6911 /* Put variables last. */
6918 }
6921 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6922 means A >= Y && A != MAX, but in this case we know that
6923 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6925 static tree
6927 {
6934 else
6943 {
6946 }
6948 {
6951 }
6952 else
6959 {
6960 /* Convert the pointer types into integer before taking the difference. */
6964 }
6965 else
6972 }
6974 /* Fold a sum or difference of at least one multiplication.
6975 Returns the folded tree or NULL if no simplification could be made. */
6977 static tree
6980 {
6984 /* (A * C) +- (B * C) -> (A+-B) * C.
6985 (A * C) +- A -> A * (C+-1).
6986 We are most concerned about the case where C is a constant,
6987 but other combinations show up during loop reduction. Since
6988 it is not difficult, try all four possibilities. */
6991 {
6994 }
6996 {
6999 }
7000 else
7001 {
7002 /* We cannot generate constant 1 for fract. */
7007 }
7009 {
7012 }
7014 {
7016 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7017 the purpose of this canonicalization. */
7021 {
7024 }
7025 else
7027 }
7028 else
7029 {
7030 /* We cannot generate constant 1 for fract. */
7035 }
7038 /* Prefer factoring a common non-constant. */
7048 /* No identical multiplicands; see if we can find a common
7049 power-of-two factor in non-power-of-two multiplies. This
7050 can help in multi-dimensional array access. */
7053 {
7056 tree maybe_same;
7060 /* Move min of absolute values to int11. */
7062 {
7067 }
7068 else
7072 /* The remainder should not be a constant, otherwise we
7073 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7074 increased the number of multiplications necessary. */
7076 {
7084 }
7085 }
7092 /* We are neither factoring zero nor minus one. */
7100 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7101 same may be minus one and thus the multiplication may overflow. Perform
7102 the sum operation in an unsigned type. */
7107 /* If the sum evaluated to a constant that is not -INF the multiplication
7108 cannot overflow. */
7115 /* Do not resort to unsigned multiplication because
7116 we lose the no-overflow property of the expression. */
7118 }
7120 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7121 specified by EXPR into the buffer PTR of length LEN bytes.
7122 Return the number of bytes placed in the buffer, or zero
7123 upon failure. */
7125 static int
7127 {
7139 /* Dry run. */
7145 {
7147 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7148 number of bytes. */
7152 {
7159 else
7161 }
7162 else
7166 }
7168 }
7171 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7172 specified by EXPR into the buffer PTR of length LEN bytes.
7173 Return the number of bytes placed in the buffer, or zero
7174 upon failure. */
7176 static int
7178 {
7182 FIXED_VALUE_TYPE value;
7197 }
7200 /* Subroutine of native_encode_expr. Encode the REAL_CST
7201 specified by EXPR into the buffer PTR of length LEN bytes.
7202 Return the number of bytes placed in the buffer, or zero
7203 upon failure. */
7205 static int
7207 {
7213 /* There are always 32 bits in each long, no matter the size of
7214 the hosts long. We handle floating point representations with
7215 up to 192 bits. */
7224 /* Dry run. */
7233 {
7238 {
7245 else
7247 }
7248 else
7249 {
7252 {
7253 /* Reverse bytes within each long, or within the entire float
7254 if it's smaller than a long (for HFmode). */
7257 }
7258 }
7263 }
7265 }
7267 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7268 specified by EXPR into the buffer PTR of length LEN bytes.
7269 Return the number of bytes placed in the buffer, or zero
7270 upon failure. */
7272 static int
7274 {
7276 tree part;
7290 }
7293 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7294 specified by EXPR into the buffer PTR of length LEN bytes.
7295 Return the number of bytes placed in the buffer, or zero
7296 upon failure. */
7298 static int
7300 {
7311 {
7313 {
7316 }
7327 }
7329 }
7332 /* Subroutine of native_encode_expr. Encode the STRING_CST
7333 specified by EXPR into the buffer PTR of length LEN bytes.
7334 Return the number of bytes placed in the buffer, or zero
7335 upon failure. */
7337 static int
7339 {
7342 /* Wide-char strings are encoded in target byte-order so native
7343 encoding them is trivial. */
7358 {
7361 {
7364 }
7367 }
7368 else
7371 }
7374 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7375 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7376 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7377 anything, just do a dry run. If OFF is not -1 then start
7378 the encoding at byte offset OFF and encode at most LEN bytes.
7379 Return the number of bytes placed in the buffer, or zero upon failure. */
7381 int
7383 {
7384 /* We don't support starting at negative offset and -1 is special. */
7389 {
7410 }
7411 }
7414 /* Subroutine of native_interpret_expr. Interpret the contents of
7415 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7416 If the buffer cannot be interpreted, return NULL_TREE. */
7418 static tree
7420 {
7430 }
7433 /* Subroutine of native_interpret_expr. Interpret the contents of
7434 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7435 If the buffer cannot be interpreted, return NULL_TREE. */
7437 static tree
7439 {
7442 double_int result;
7443 FIXED_VALUE_TYPE fixed_value;
7453 }
7456 /* Subroutine of native_interpret_expr. Interpret the contents of
7457 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7458 If the buffer cannot be interpreted, return NULL_TREE. */
7460 static tree
7462 {
7466 /* There are always 32 bits in each long, no matter the size of
7467 the hosts long. We handle floating point representations with
7468 up to 192 bits. */
7469 REAL_VALUE_TYPE r;
7479 {
7480 /* Both OFFSET and BYTE index within a long;
7481 bitpos indexes the whole float. */
7484 {
7491 else
7493 }
7494 else
7495 {
7498 {
7499 /* Reverse bytes within each long, or within the entire float
7500 if it's smaller than a long (for HFmode). */
7503 }
7504 }
7508 }
7512 }
7515 /* Subroutine of native_interpret_expr. Interpret the contents of
7516 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7517 If the buffer cannot be interpreted, return NULL_TREE. */
7519 static tree
7521 {
7536 }
7539 /* Subroutine of native_interpret_expr. Interpret the contents of
7540 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7541 If the buffer cannot be interpreted, return NULL_TREE. */
7543 static tree
7545 {
7558 {
7563 }
7565 }
7568 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7569 the buffer PTR of length LEN as a constant of type TYPE. For
7570 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7571 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7572 return NULL_TREE. */
7574 tree
7576 {
7578 {
7600 }
7601 }
7603 /* Returns true if we can interpret the contents of a native encoding
7604 as TYPE. */
7606 static bool
7608 {
7610 {
7623 }
7624 }
7627 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7628 TYPE at compile-time. If we're unable to perform the conversion
7629 return NULL_TREE. */
7631 static tree
7633 {
7634 /* We support up to 512-bit values (for V8DFmode). */
7638 /* Check that the host and target are sane. */
7647 }
7649 /* Build an expression for the address of T. Folds away INDIRECT_REF
7650 to avoid confusing the gimplify process. */
7652 tree
7654 {
7655 /* The size of the object is not relevant when talking about its address. */
7660 {
7665 }
7675 {
7680 }
7681 else
7685 }
7687 /* Build an expression for the address of T. */
7689 tree
7691 {
7695 }
7697 /* Fold a unary expression of code CODE and type TYPE with operand
7698 OP0. Return the folded expression if folding is successful.
7699 Otherwise, return NULL_TREE. */
7701 tree
7703 {
7704 tree tem;
7705 tree arg0;
7713 {
7716 {
7717 /* Don't use STRIP_NOPS, because signedness of argument type
7718 matters. */
7720 }
7721 else
7722 {
7723 /* Strip any conversions that don't change the mode. This
7724 is safe for every expression, except for a comparison
7725 expression because its signedness is derived from its
7726 operands.
7728 Note that this is done as an internal manipulation within
7729 the constant folder, in order to find the simplest
7730 representation of the arguments so that their form can be
7731 studied. In any cases, the appropriate type conversions
7732 should be put back in the tree that will get out of the
7733 constant folder. */
7735 }
7738 {
7741 {
7745 }
7746 }
7747 }
7754 {
7761 {
7775 /* If this was a conversion, and all we did was to move into
7776 inside the COND_EXPR, bring it back out. But leave it if
7777 it is a conversion from integer to integer and the
7778 result precision is no wider than a word since such a
7779 conversion is cheap and may be optimized away by combine,
7780 while it couldn't if it were outside the COND_EXPR. Then return
7781 so we don't get into an infinite recursion loop taking the
7782 conversion out and then back in. */
7794 && (INTEGRAL_TYPE_P
7807 }
7808 }
7811 {
7817 CASE_CONVERT:
7821 {
7822 /* If we have (type) (a CMP b) and type is an integral type, return
7823 new expression involving the new type. Canonicalize
7824 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7825 non-integral type.
7826 Do not fold the result as that would not simplify further, also
7827 folding again results in recursions. */
7837 }
7839 /* Handle (T *)&A.B.C for A being of type T and B and C
7840 living at offset zero. This occurs frequently in
7841 C++ upcasting and then accessing the base. */
7845 {
7847 tree offset;
7848 machine_mode mode;
7850 tree base
7854 /* If the reference was to a (constant) zero offset, we can use
7855 the address of the base if it has the same base type
7856 as the result type and the pointer type is unqualified. */
7864 }
7868 /* Detect assigning a bitfield. */
7870 && DECL_BIT_FIELD
7872 {
7873 /* Don't leave an assignment inside a conversion
7874 unless assigning a bitfield. */
7876 /* First do the assignment, then return converted constant. */
7881 }
7883 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7884 constants (if x has signed type, the sign bit cannot be set
7885 in c). This folds extension into the BIT_AND_EXPR.
7886 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7887 very likely don't have maximal range for their precision and this
7888 transformation effectively doesn't preserve non-maximal ranges. */
7892 {
7903 <= HOST_BITS_PER_WIDE_INT
7905 {
7909 cst &= HOST_WIDE_INT_M1U
7913 && !flag_syntax_only
7916 {
7920 }
7921 }
7923 {
7928 }
7929 }
7931 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7932 cast (T1)X will fold away. We assume that this happens when X itself
7933 is a cast. */
7937 {
7941 return fold_build_pointer_plus_loc
7943 }
7945 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7946 of the same precision, and X is an integer type not narrower than
7947 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7953 {
7959 }
7961 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7962 type of X and Y (integer types only). */
7967 {
7968 /* Be careful not to introduce new overflows. */
7969 tree mult_type;
7972 else
7976 {
7983 }
7984 }
7990 {
7997 }
8008 /* Convert fabs((double)float) into (double)fabsf(float). */
8011 {
8017 targ0));
8018 }
8022 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8041 /* Note that the operand of this must be an int
8042 and its values must be 0 or 1.
8043 ("true" is a fixed value perhaps depending on the language,
8044 but we don't handle values other than 1 correctly yet.) */
8051 /* Fold *&X to X if X is an lvalue. */
8053 {
8060 }
8066 }
8069 /* If the operation was a conversion do _not_ mark a resulting constant
8070 with TREE_OVERFLOW if the original constant was not. These conversions
8071 have implementation defined behavior and retaining the TREE_OVERFLOW
8072 flag here would confuse later passes such as VRP. */
8073 tree
8076 {
8085 }
8087 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8088 operands OP0 and OP1. LOC is the location of the resulting expression.
8089 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8090 Return the folded expression if folding is successful. Otherwise,
8091 return NULL_TREE. */
8092 static tree
8095 {
8096 tree tem;
8098 /* We only do these simplifications if we are optimizing. */
8102 /* Check for things like (A || B) && (A || C). We can convert this
8103 to A || (B && C). Note that either operator can be any of the four
8104 truth and/or operations and the transformation will still be
8105 valid. Also note that we only care about order for the
8106 ANDIF and ORIF operators. If B contains side effects, this
8107 might change the truth-value of A. */
8114 {
8134 /* This case if tricky because we must either have commutative
8135 operators or else A10 must not have side-effects. */
8141 a01);
8142 }
8144 /* See if we can build a range comparison. */
8150 {
8154 }
8158 {
8162 }
8164 /* Check for the possibility of merging component references. If our
8165 lhs is another similar operation, try to merge its rhs with our
8166 rhs. Then try to merge our lhs and rhs. */
8176 && !flag_sanitize_coverage
8181 {
8188 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8189 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8190 We don't want to pack more than two leafs to a non-IF AND/OR
8191 expression.
8192 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8193 equal to IF-CODE, then we don't want to add right-hand operand.
8194 If the inner right-hand side of left-hand operand has
8195 side-effects, or isn't simple, then we can't add to it,
8196 as otherwise we might destroy if-sequence. */
8199 /* Needed for sequence points to handle trappings, and
8200 side-effects. */
8202 {
8204 arg1);
8206 tem);
8207 }
8208 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8209 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8212 /* Needed for sequence points to handle trappings, and
8213 side-effects. */
8215 {
8220 }
8221 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8222 into (A OR B).
8223 For sequence point consistancy, we need to check for trapping,
8224 and side-effects. */
8228 }
8231 }
8233 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8234 by changing CODE to reduce the magnitude of constants involved in
8235 ARG0 of the comparison.
8236 Returns a canonicalized comparison tree if a simplification was
8237 possible, otherwise returns NULL_TREE.
8238 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8239 valid if signed overflow is undefined. */
8241 static tree
8245 {
8250 /* Match A +- CST code arg1. We can change this only if overflow
8251 is undefined. */
8254 /* In principle pointers also have undefined overflow behavior,
8255 but that causes problems elsewhere. */
8262 /* Identify the constant in arg0 and its sign. */
8266 /* Overflowed constants and zero will cause problems. */
8271 /* See if we can reduce the magnitude of the constant in
8272 arg0 by changing the comparison code. */
8273 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8277 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8281 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8285 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8289 else
8293 /* Now build the constant reduced in magnitude. But not if that
8294 would produce one outside of its types range. */
8310 }
8312 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8313 overflow further. Try to decrease the magnitude of constants involved
8314 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8315 and put sole constants at the second argument position.
8316 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8318 static tree
8321 {
8322 tree t;
8327 /* Try canonicalization by simplifying arg0. */
8332 {
8336 }
8338 /* Try canonicalization by simplifying arg1 using the swapped
8339 comparison. */
8347 }
8349 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8350 space. This is used to avoid issuing overflow warnings for
8351 expressions like &p->x which can not wrap. */
8353 static bool
8355 {
8362 poly_wide_int wi_offset;
8368 else
8373 precision);
8388 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8389 array. */
8398 }
8400 /* Return a positive integer when the symbol DECL is known to have
8401 a nonzero address, zero when it's known not to (e.g., it's a weak
8402 symbol), and a negative integer when the symbol is not yet in the
8403 symbol table and so whether or not its address is zero is unknown.
8404 For function local objects always return positive integer. */
8405 static int
8407 {
8412 /* Function local objects are never NULL. */
8420 }
8422 /* Subroutine of fold_binary. This routine performs all of the
8423 transformations that are common to the equality/inequality
8424 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8425 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8426 fold_binary should call fold_binary. Fold a comparison with
8427 tree code CODE and type TYPE with operands OP0 and OP1. Return
8428 the folded comparison or NULL_TREE. */
8430 static tree
8433 {
8443 /* For comparisons of pointers we can decompose it to a compile time
8444 comparison of the base objects and the offsets into the object.
8445 This requires at least one operand being an ADDR_EXPR or a
8446 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8452 {
8455 machine_mode mode;
8459 /* Get base and offset for the access. Strip ADDR_EXPR for
8460 get_inner_reference, but put it back by stripping INDIRECT_REF
8461 off the base object if possible. indirect_baseN will be true
8462 if baseN is not an address but refers to the object itself. */
8465 {
8466 base0
8472 else
8474 }
8476 {
8480 {
8481 base0
8487 else
8489 }
8492 else
8496 {
8503 }
8504 }
8508 {
8509 base1
8515 else
8517 }
8519 {
8523 {
8524 base1
8530 else
8532 }
8535 else
8539 {
8546 }
8547 }
8549 /* If we have equivalent bases we might be able to simplify. */
8553 {
8554 /* We can fold this expression to a constant if the non-constant
8555 offset parts are equal. */
8559 && (equality_code
8560 || (indirect_base0
8563 {
8569 "occur when comparing P +- C1 with "
8571 WARN_STRICT_OVERFLOW_CONDITIONAL);
8574 {
8612 }
8613 }
8614 /* We can simplify the comparison to a comparison of the variable
8615 offset parts if the constant offset parts are equal.
8616 Be careful to use signed sizetype here because otherwise we
8617 mess with array offsets in the wrong way. This is possible
8618 because pointer arithmetic is restricted to retain within an
8619 object and overflow on pointer differences is undefined as of
8620 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8622 && (equality_code
8623 || (indirect_base0
8626 {
8627 /* By converting to signed sizetype we cover middle-end pointer
8628 arithmetic which operates on unsigned pointer types of size
8629 type size and ARRAY_REF offsets which are properly sign or
8630 zero extended from their type in case it is narrower than
8631 sizetype. */
8634 else
8638 else
8645 "occur when comparing P +- C1 with "
8647 WARN_STRICT_OVERFLOW_COMPARISON);
8650 }
8651 }
8652 /* For equal offsets we can simplify to a comparison of the
8653 base addresses. */
8655 && (indirect_base0
8657 && (indirect_base1
8662 {
8668 }
8669 /* Comparison between an ordinary (non-weak) symbol and a null
8670 pointer can be eliminated since such symbols must have a non
8671 null address. In C, relational expressions between pointers
8672 to objects and null pointers are undefined. The results
8673 below follow the C++ rules with the additional property that
8674 every object pointer compares greater than a null pointer.
8675 */
8678 /* Avoid folding references to struct members at offset 0 to
8679 prevent tests like '&ptr->firstmember == 0' from getting
8680 eliminated. When ptr is null, although the -> expression
8681 is strictly speaking invalid, GCC retains it as a matter
8682 of QoI. See PR c/44555. */
8685 && indirect_base0
8686 /* The caller guarantees that when one of the arguments is
8687 constant (i.e., null in this case) it is second. */
8689 {
8691 {
8702 }
8703 }
8704 }
8706 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8707 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8708 the resulting offset is smaller in absolute value than the
8709 original one and has the same sign. */
8718 {
8723 tree cst;
8725 "occur when combining constants around "
8728 /* Put the constant on the side where it doesn't overflow and is
8729 of lower absolute value and of same sign than before. */
8736 {
8739 variable1,
8743 }
8751 {
8757 variable2);
8758 }
8759 }
8765 /* If we are comparing an expression that just has comparisons
8766 of two integer values, arithmetic expressions of those comparisons,
8767 and constants, we can simplify it. There are only three cases
8768 to check: the two values can either be equal, the first can be
8769 greater, or the second can be greater. Fold the expression for
8770 those three values. Since each value must be 0 or 1, we have
8771 eight possibilities, each of which corresponds to the constant 0
8772 or 1 or one of the six possible comparisons.
8774 This handles common cases like (a > b) == 0 but also handles
8775 expressions like ((x > y) - (y > x)) > 0, which supposedly
8776 occur in macroized code. */
8779 {
8783 /* Don't handle degenerate cases here; they should already
8784 have been handled anyway. */
8793 {
8797 /* We can't just pass T to eval_subst in case cval1 or cval2
8798 was the same as ARG1. */
8800 tree high_result
8804 arg1);
8805 tree equal_result
8809 arg1);
8810 tree low_result
8814 arg1);
8816 /* All three of these results should be 0 or 1. Confirm they are.
8817 Then use those values to select the proper code to use. */
8822 {
8823 /* Make a 3-bit mask with the high-order bit being the
8824 value for `>', the next for '=', and the low for '<'. */
8828 {
8830 /* Always false. */
8851 /* Always true. */
8853 }
8856 }
8857 }
8858 }
8861 }
8864 /* Subroutine of fold_binary. Optimize complex multiplications of the
8865 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8866 argument EXPR represents the expression "z" of type TYPE. */
8868 static tree
8870 {
8875 {
8878 }
8880 {
8883 }
8884 else
8885 {
8889 }
8898 }
8901 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8902 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8903 true if successful. */
8905 static bool
8907 {
8912 {
8915 }
8917 {
8923 else
8925 }
8926 else
8932 }
8934 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8935 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8936 NULL_TREE otherwise. */
8938 static tree
8940 {
8961 {
8962 HOST_WIDE_INT index;
8968 }
8971 {
8977 }
8978 else
8980 }
8982 /* Try to fold a pointer difference of type TYPE two address expressions of
8983 array references AREF0 and AREF1 using location LOC. Return a
8984 simplified expression for the difference or NULL_TREE. */
8986 static tree
8990 {
8995 /* If the bases are array references as well, recurse. If the bases
8996 are pointer indirections compute the difference of the pointers.
8997 If the bases are equal, we are set. */
9000 && (base_offset
9002 use_pointer_diff)))
9005 && (base_offset
9006 = use_pointer_diff
9016 {
9022 base_offset,
9025 }
9027 }
9029 /* If the real or vector real constant CST of type TYPE has an exact
9030 inverse, return it, else return NULL. */
9032 tree
9034 {
9035 REAL_VALUE_TYPE r;
9036 tree unit_type;
9037 machine_mode mode;
9040 {
9050 {
9054 tree_vector_builder elts;
9059 {
9064 }
9067 }
9071 }
9072 }
9074 /* Mask out the tz least significant bits of X of type TYPE where
9075 tz is the number of trailing zeroes in Y. */
9076 static wide_int
9078 {
9083 }
9085 /* Return true when T is an address and is known to be nonzero.
9086 For floating point we further ensure that T is not denormal.
9087 Similar logic is present in nonzero_address in rtlanal.h.
9089 If the return value is based on the assumption that signed overflow
9090 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9091 change *STRICT_OVERFLOW_P. */
9093 static bool
9095 {
9099 /* Doing something useful for floating point would need more work. */
9105 {
9108 strict_overflow_p);
9114 strict_overflow_p);
9122 }
9125 {
9128 strict_overflow_p);
9136 strict_overflow_p);
9151 strict_overflow_p);
9155 strict_overflow_p);
9158 {
9170 }
9174 }
9176 }
9178 /* Return true when T is an address and is known to be nonzero.
9179 Handle warnings about undefined signed overflow. */
9181 bool
9183 {
9190 "determining that expression is always "
9192 WARN_STRICT_OVERFLOW_MISC);
9194 }
9196 /* Return true if T is known not to be equal to an integer W. */
9198 bool
9200 {
9202 value_range_type rtype;
9204 {
9213 {
9218 }
9223 /* If T has some known zero bits and W has any of those bits set,
9224 then T is known not to be equal to W. */
9232 }
9233 }
9235 /* Fold a binary expression of code CODE and type TYPE with operands
9236 OP0 and OP1. LOC is the location of the resulting expression.
9237 Return the folded expression if folding is successful. Otherwise,
9238 return NULL_TREE. */
9240 tree
9243 {
9258 /* Strip any conversions that don't change the mode. This is
9259 safe for every expression, except for a comparison expression
9260 because its signedness is derived from its operands. So, in
9261 the latter case, only strip conversions that don't change the
9262 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9263 preserved.
9265 Note that this is done as an internal manipulation within the
9266 constant folder, in order to find the simplest representation
9267 of the arguments so that their form can be studied. In any
9268 cases, the appropriate type conversions should be put back in
9269 the tree that will get out of the constant folder. */
9272 {
9275 }
9276 else
9277 {
9280 }
9282 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9283 constant but we can't do arithmetic on them. */
9285 {
9288 {
9292 }
9293 }
9295 /* If this is a commutative operation, and ARG0 is a constant, move it
9296 to ARG1 to reduce the number of tests below. */
9301 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9302 to ARG1 to reduce the number of tests below. */
9311 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9313 First check for cases where an arithmetic operation is applied to a
9314 compound, conditional, or comparison operation. Push the arithmetic
9315 operation inside the compound or conditional to see if any folding
9316 can then be done. Convert comparison to conditional for this purpose.
9317 The also optimizes non-constant cases that used to be done in
9318 expand_expr.
9320 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9321 one of the operands is a comparison and the other is a comparison, a
9322 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9323 code below would make the expression more complex. Change it to a
9324 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9325 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9338 {
9342 boolean_type_node,
9350 }
9354 {
9356 {
9361 tem);
9362 }
9364 {
9369 tem);
9370 }
9375 {
9381 }
9386 {
9392 }
9393 }
9396 {
9398 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9401 {
9407 }
9409 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9412 {
9413 tree base;
9414 poly_int64 coffset;
9423 }
9428 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9434 arg1),
9436 arg0)));
9442 {
9443 /* X + (X / CST) * -CST is X % CST. */
9448 {
9457 cst0));
9458 }
9459 }
9461 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9462 one. Make sure the type is not saturating and has the signedness of
9463 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9464 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9471 {
9475 }
9478 {
9479 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9480 (plus (plus (mult) (mult)) (foo)) so that we can
9481 take advantage of the factoring cases below. */
9490 {
9496 else
9509 parg0),
9511 marg)),
9515 return
9521 parg1)));
9522 }
9523 }
9524 else
9525 {
9526 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9527 to __complex__ ( x, y ). This is not the same for SNaNs or
9528 if signed zeros are involved. */
9532 {
9539 {
9543 {
9549 }
9551 {
9557 }
9558 }
9559 }
9561 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9562 We associate floats only if the user has specified
9563 -fassociative-math. */
9567 {
9572 {
9573 tree tree0;
9576 }
9577 }
9578 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9579 We associate floats only if the user has specified
9580 -fassociative-math. */
9584 {
9589 {
9590 tree tree0;
9593 }
9594 }
9595 }
9597 bit_rotate:
9598 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9599 is a rotate of A by C1 bits. */
9600 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9601 is a rotate of A by B bits.
9602 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9603 though in this case CODE must be | and not + or ^, otherwise
9604 it doesn't return A when B is 0. */
9605 {
9607 tree rtype;
9616 /* Only create rotates in complete modes. Other cases are not
9617 expanded properly. */
9620 {
9633 {
9638 }
9643 {
9646 code0 == LSHIFT_EXPR
9649 }
9651 {
9661 {
9665 orig_tree01);
9667 }
9668 }
9672 {
9683 {
9687 orig_tree01);
9689 }
9690 }
9691 }
9692 }
9694 associate:
9695 /* In most languages, can't associate operations on floats through
9696 parentheses. Rather than remember where the parentheses were, we
9697 don't associate floats at all, unless the user has specified
9698 -fassociative-math.
9699 And, we need to make sure type is not saturating. */
9703 {
9709 /* Split both trees into variables, constants, and literals. Then
9710 associate each group together, the constants with literals,
9711 then the result with variables. This increases the chances of
9712 literals being recombined later and of generating relocatable
9713 expressions for the sum of a constant and literal. */
9721 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9725 /* With undefined overflow prefer doing association in a type
9726 which wraps on overflow, if that is one of the operand types. */
9729 {
9737 }
9739 /* With undefined overflow we can only associate constants with one
9740 variable, and constants whose association doesn't overflow. */
9743 {
9745 {
9746 /* ??? If split_tree would handle NEGATE_EXPR we could
9747 simply reject these cases and the allowed cases would
9748 be the var0/minus_var1 ones. */
9754 {
9757 }
9764 {
9767 }
9773 /* The only case we can still associate with two variables
9774 is if they cancel out. */
9778 }
9784 }
9786 /* Only do something if we found more than two objects. Otherwise,
9787 nothing has changed and we risk infinite recursion. */
9795 {
9807 {
9811 }
9813 {
9817 }
9819 /* Preserve the MINUS_EXPR if the negative part of the literal is
9820 greater than the positive part. Otherwise, the multiplicative
9821 folding code (i.e extract_muldiv) may be fooled in case
9822 unsigned constants are subtracted, like in the following
9823 example: ((X*2 + 4) - 8U)/2. */
9825 {
9829 /* But avoid ending up with only negated parts. */
9831 {
9835 }
9836 else
9837 {
9841 }
9842 }
9844 /* Don't introduce overflows through reassociation. */
9849 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9856 /* Eliminate minus_con0. */
9858 {
9865 else
9868 }
9870 /* Eliminate minus_var0. */
9872 {
9876 else
9879 }
9881 return
9884 }
9885 }
9891 /* Fold &a[i] - &a[j] to i-j. */
9896 {
9900 code
9904 }
9906 /* Further transformations are not for pointers. */
9910 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9913 /* If arg0 is e.g. unsigned int and type is int, then this could
9914 introduce UB, because if A is INT_MIN at runtime, the original
9915 expression can be well defined while the latter is not.
9916 See PR83269. */
9925 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9926 __complex__ ( x, -y ). This is not the same for SNaNs or if
9927 signed zeros are involved. */
9931 {
9938 {
9942 {
9944 arg1r ? arg1r
9949 }
9951 {
9955 arg1i ? arg1i
9958 }
9959 }
9960 }
9962 /* A - B -> A + (-B) if B is easily negatable. */
9966 /* Avoid this transformation if B is a positive REAL_CST. */
9974 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9975 one. Make sure the type is not saturating and has the signedness of
9976 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9977 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9984 {
9988 }
9994 {
9995 /* Transform x * -C into -x * C if x is easily negatable. */
10010 {
10013 "occur when simplifying "
10015 WARN_STRICT_OVERFLOW_MISC);
10017 }
10019 /* Optimize z * conj(z) for integer complex numbers. */
10026 }
10027 else
10028 {
10029 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10030 This is not the same for NaNs or if signed zeros are
10031 involved. */
10037 {
10040 return
10046 return
10051 }
10053 /* Optimize z * conj(z) for floating point complex numbers.
10054 Guarded by flag_unsafe_math_optimizations as non-finite
10055 imaginary components don't produce scalar results. */
10064 }
10068 /* Canonicalize (X & C1) | C2. */
10072 {
10077 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10085 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10087 {
10090 }
10092 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10093 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10094 mode which allows further optimizations. */
10099 {
10104 {
10107 }
10108 }
10111 {
10116 }
10117 }
10119 /* See if this can be simplified into a rotate first. If that
10120 is unsuccessful continue in the association code. */
10124 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10132 /* See if this can be simplified into a rotate first. If that
10133 is unsuccessful continue in the association code. */
10137 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10142 {
10143 tree tem2;
10150 }
10151 /* Fold ~X & 1 as (X & 1) == 0. */
10155 {
10156 tree tem2;
10163 }
10164 /* Fold !X & 1 as X == 0. */
10167 {
10171 }
10173 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10174 multiple of 1 << CST. */
10176 {
10183 }
10185 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10186 bits from CST2. */
10190 {
10192 wide_int masked
10199 {
10200 /* Avoid the transform if arg1 is a mask of some
10201 mode which allows further optimizations. */
10208 }
10209 }
10211 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10212 ((A & N) + B) & M -> (A + B) & M
10213 Similarly if (N & M) == 0,
10214 ((A | N) + B) & M -> (A + B) & M
10215 and for - instead of + (or unary - instead of +)
10216 and/or ^ instead of |.
10217 If B is constant and (B & M) == 0, fold into A & M. */
10219 {
10228 {
10231 wide_int cst0;
10233 /* Now we know that arg0 is (C + D) or (C - D) or
10234 -C and arg1 (M) is == (1LL << cst) - 1.
10235 Store C into PMOP[0] and D into PMOP[1]. */
10239 {
10242 }
10249 {
10258 {
10261 }
10264 /* If C or D is of the form (A & N) where
10265 (N & M) == M, or of the form (A | N) or
10266 (A ^ N) where (N & M) == 0, replace it with A. */
10270 /* If C or D is a N where (N & M) == 0, it can be
10271 omitted (assumed 0). */
10279 }
10281 /* Only build anything new if we optimized one or both arguments
10282 above. */
10286 {
10289 {
10290 /* Perform the operations in a type that has defined
10291 overflow behavior. */
10297 }
10302 {
10310 else
10312 }
10315 else
10318 /* TEM is now the new binary +, - or unary - replacement. */
10322 }
10323 }
10324 }
10326 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10329 {
10334 return
10336 }
10341 /* Don't touch a floating-point divide by zero unless the mode
10342 of the constant can represent infinity. */
10348 /* (-A) / (-B) -> A / B */
10360 /* Fall through */
10363 /* Simplify A / (B << N) where A and B are positive and B is
10364 a power of 2, to A >> (N + log2(B)). */
10369 {
10372 {
10380 WARN_STRICT_OVERFLOW_MISC);
10386 }
10387 }
10389 /* Fall through */
10397 /* Convert -A / -B to A / B when the type is signed and overflow is
10398 undefined. */
10402 {
10405 "when distributing negation across "
10407 WARN_STRICT_OVERFLOW_MISC);
10412 }
10416 {
10419 "when distributing negation across "
10421 WARN_STRICT_OVERFLOW_MISC);
10426 }
10428 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10429 operation, EXACT_DIV_EXPR.
10431 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10432 At one time others generated faster code, it's not clear if they do
10433 after the last round to changes to the DIV code in expmed.c. */
10444 {
10448 WARN_STRICT_OVERFLOW_MISC);
10450 }
10462 {
10466 WARN_STRICT_OVERFLOW_MISC);
10468 }
10476 /* Since negative shift count is not well-defined,
10477 don't try to compute it in the compiler. */
10483 /* If we have a rotate of a bit operation with the rotate count and
10484 the second operand of the bit operation both constant,
10485 permute the two operations. */
10491 {
10499 }
10501 /* Two consecutive rotates adding up to the some integer
10502 multiple of the precision of the type can be ignored. */
10518 /* Note that the operands of this must be ints
10519 and their values must be 0 or 1.
10520 ("true" is a fixed value perhaps depending on the language.) */
10521 /* If first arg is constant zero, return it. */
10524 /* FALLTHRU */
10526 /* If either arg is constant true, drop it. */
10530 /* Preserve sequence points. */
10533 /* If second arg is constant zero, result is zero, but first arg
10534 must be evaluated. */
10537 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10538 case will be handled here. */
10542 /* !X && X is always false. */
10546 /* X && !X is always false. */
10551 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10552 means A >= Y && A != MAX, but in this case we know that
10553 A < X <= MAX. */
10557 {
10565 }
10574 /* Note that the operands of this must be ints
10575 and their values must be 0 or true.
10576 ("true" is a fixed value perhaps depending on the language.) */
10577 /* If first arg is constant true, return it. */
10580 /* FALLTHRU */
10582 /* If either arg is constant zero, drop it. */
10586 /* Preserve sequence points. */
10589 /* If second arg is constant true, result is true, but we must
10590 evaluate first arg. */
10593 /* Likewise for first arg, but note this only occurs here for
10594 TRUTH_OR_EXPR. */
10598 /* !X || X is always true. */
10602 /* X || !X is always true. */
10607 /* (X && !Y) || (!X && Y) is X ^ Y */
10610 {
10627 }
10636 /* If the second arg is constant zero, drop it. */
10639 /* If the second arg is constant true, this is a logical inversion. */
10641 {
10644 }
10645 /* Identical arguments cancel to zero. */
10649 /* !X ^ X is always true. */
10654 /* X ^ !X is always true. */
10670 /* bool_var != 1 becomes !bool_var. */
10677 /* bool_var == 0 becomes !bool_var. */
10684 /* !exp != 0 becomes !exp */
10689 /* If this is an EQ or NE comparison with zero and ARG0 is
10690 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10691 two operations, but the latter can be done in one less insn
10692 on machines that have only two-operand insns or on which a
10693 constant cannot be the first operand. */
10696 {
10701 {
10708 arg1);
10709 }
10712 {
10719 arg1);
10720 }
10721 }
10723 /* If this is an NE or EQ comparison of zero against the result of a
10724 signed MOD operation whose second operand is a power of 2, make
10725 the MOD operation unsigned since it is simpler and equivalent. */
10733 {
10743 }
10745 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10746 C1 is a valid shift constant, and C2 is a power of two, i.e.
10747 a single bit. */
10751 == INTEGER_CST
10754 {
10759 /* Check for a valid shift count. */
10761 {
10765 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10766 can be rewritten as (X & (C2 << C1)) != 0. */
10768 {
10773 }
10774 /* Otherwise, for signed (arithmetic) shifts,
10775 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10776 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10780 /* Otherwise, of unsigned (logical) shifts,
10781 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10782 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10783 else
10787 arg000);
10788 }
10789 }
10791 /* If this is a comparison of a field, we may be able to simplify it. */
10794 /* Handle the constant case even without -O
10795 to make sure the warnings are given. */
10797 {
10801 }
10803 /* Optimize comparisons of strlen vs zero to a compare of the
10804 first character of the string vs zero. To wit,
10805 strlen(ptr) == 0 => *ptr == 0
10806 strlen(ptr) != 0 => *ptr != 0
10807 Other cases should reduce to one of these two (or a constant)
10808 due to the return value of strlen being unsigned. */
10811 {
10819 {
10824 }
10825 }
10827 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10828 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10832 {
10837 {
10839 {
10842 }
10845 }
10846 }
10848 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10849 (X & C) == 0 when C is a single bit. */
10854 {
10861 arg1));
10862 }
10864 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10865 constant C is a power of two, i.e. a single bit. */
10872 {
10876 }
10878 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10879 when is C is a power of two, i.e. a single bit. */
10886 {
10892 }
10896 {
10899 }
10901 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10904 {
10912 {
10918 }
10920 {
10926 }
10928 {
10934 }
10936 {
10942 }
10943 }
10947 {
10954 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10955 operand_equal_p guarantees no side-effects so we don't need
10956 to use omit_one_operand on Z. */
10960 arg10));
10964 arg11));
10968 arg10));
10972 arg11));
10974 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10977 {
10983 }
10984 }
10986 /* Attempt to simplify equality/inequality comparisons of complex
10987 values. Only lower the comparison if the result is known or
10988 can be simplified to a single scalar comparison. */
10993 {
10998 {
11001 }
11002 else
11003 {
11006 }
11009 {
11012 }
11013 else
11014 {
11017 }
11021 {
11023 {
11028 }
11029 else
11030 {
11035 }
11036 }
11040 {
11042 {
11047 }
11048 else
11049 {
11054 }
11055 }
11056 }
11068 /* Transform comparisons of the form X +- C CMP X. */
11073 {
11078 /* (X - c) > X becomes false. */
11084 /* Likewise (X + c) < X becomes false. */
11090 /* Convert (X - c) <= X to true. */
11097 /* Convert (X + c) >= X to true. */
11103 }
11105 /* If we are comparing an ABS_EXPR with a constant, we can
11106 convert all the cases into explicit comparisons, but they may
11107 well not be faster than doing the ABS and one comparison.
11108 But ABS (X) <= C is a range comparison, which becomes a subtraction
11109 and a comparison, and is probably faster. */
11123 /* Convert ABS_EXPR<x> >= 0 to true. */
11130 {
11133 "when simplifying comparison of "
11135 WARN_STRICT_OVERFLOW_CONDITIONAL);
11138 arg0);
11139 }
11141 /* Convert ABS_EXPR<x> < 0 to false. */
11146 {
11149 "when simplifying comparison of "
11151 WARN_STRICT_OVERFLOW_CONDITIONAL);
11154 arg0);
11155 }
11157 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11158 and similarly for >= into !=. */
11168 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11169 otherwise Y might be >= # of bits in X's type and thus e.g.
11170 (unsigned char) (1 << Y) for Y 15 might be 0.
11171 If the cast is widening, then 1 << Y should have unsigned type,
11172 otherwise if Y is number of bits in the signed shift type minus 1,
11173 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11174 31 might be 0xffffffff80000000. */
11185 {
11191 }
11203 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11204 {
11216 }
11221 /* When pedantic, a compound expression can be neither an lvalue
11222 nor an integer constant expression. */
11225 /* Don't let (0, 0) be null pointer constant. */
11231 /* An ASSERT_EXPR should never be passed to fold_binary. */
11237 }
11239 /* Used by contains_label_[p1]. */
11241 struct contains_label_data
11242 {
11245 };
11247 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11248 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11249 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11251 static tree
11253 {
11256 {
11267 {
11275 }
11284 }
11285 }
11287 /* Return whether the sub-tree ST contains a label which is accessible from
11288 outside the sub-tree. */
11290 static bool
11292 {
11296 }
11298 /* Fold a ternary expression of code CODE and type TYPE with operands
11299 OP0, OP1, and OP2. Return the folded expression if folding is
11300 successful. Otherwise, return NULL_TREE. */
11302 tree
11305 {
11306 tree tem;
11313 /* If this is a commutative operation, and OP0 is a constant, move it
11314 to OP1 to reduce the number of tests below. */
11323 /* Strip any conversions that don't change the mode. This is safe
11324 for every expression, except for a comparison expression because
11325 its signedness is derived from its operands. So, in the latter
11326 case, only strip conversions that don't change the signedness.
11328 Note that this is done as an internal manipulation within the
11329 constant folder, in order to find the simplest representation of
11330 the arguments so that their form can be studied. In any cases,
11331 the appropriate type conversions should be put back in the tree
11332 that will get out of the constant folder. */
11334 {
11337 }
11340 {
11343 }
11346 {
11349 }
11352 {
11356 {
11362 }
11367 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11368 so all simple results must be passed through pedantic_non_lvalue. */
11370 {
11373 /* Only optimize constant conditions when the selected branch
11374 has the same type as the COND_EXPR. This avoids optimizing
11375 away "c ? x : throw", where the throw has a void type.
11376 Avoid throwing away that operand which contains label. */
11383 }
11385 {
11392 {
11395 {
11403 }
11408 }
11409 }
11411 /* If we have A op B ? A : C, we may be able to convert this to a
11412 simpler expression, depending on the operation and the values
11413 of B and C. Signed zeros prevent all of these transformations,
11414 for reasons given above each one.
11416 Also try swapping the arguments and inverting the conditional. */
11420 {
11424 }
11429 {
11433 {
11437 }
11438 }
11440 /* If the second operand is simpler than the third, swap them
11441 since that produces better jump optimization results. */
11444 {
11446 /* See if this can be inverted. If it can't, possibly because
11447 it was a floating-point inequality comparison, don't do
11448 anything. */
11452 }
11454 /* Convert A ? 1 : 0 to simply A. */
11459 /* If we try to convert OP0 to our type, the
11460 call to fold will try to move the conversion inside
11461 a COND, which will recurse. In that case, the COND_EXPR
11462 is probably the best choice, so leave it alone. */
11466 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11467 over COND_EXPR in cases such as floating point comparisons. */
11476 arg0)));
11478 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11483 {
11484 /* sign_bit_p looks through both zero and sign extensions,
11485 but for this optimization only sign extensions are
11486 usable. */
11489 {
11492 {
11495 }
11497 }
11498 /* sign_bit_p only checks ARG1 bits within A's precision.
11499 If <sign bit of A> has wider type than A, bits outside
11500 of A's precision in <sign bit of A> need to be checked.
11501 If they are all 0, this optimization needs to be done
11502 in unsigned A's type, if they are all 1 in signed A's type,
11503 otherwise this can't be done. */
11509 {
11511 tree tem_type;
11524 {
11527 }
11529 {
11532 }
11533 else
11535 }
11538 return
11544 arg1)));
11545 }
11547 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11548 already handled above. */
11553 {
11563 op1);
11564 }
11566 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11567 is probably obsolete because the first operand should be a
11568 truth value (that's why we have the two cases above), but let's
11569 leave it in until we can confirm this for all front-ends. */
11581 /* Disable the transformations below for vectors, since
11582 fold_binary_op_with_conditional_arg may undo them immediately,
11583 yielding an infinite loop. */
11587 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11596 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11601 {
11603 /* Only perform transformation if ARG0 is easily inverted. */
11607 ? BIT_IOR_EXPR
11610 op1);
11611 }
11613 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11618 {
11620 /* Only perform transformation if ARG0 is easily inverted. */
11626 op2);
11627 }
11629 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11641 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11642 of fold_ternary on them. */
11652 {
11663 {
11668 {
11670 {
11675 }
11681 }
11682 }
11683 }
11685 /* On constants we can use native encode/interpret to constant
11686 fold (nearly) all BIT_FIELD_REFs. */
11692 {
11695 /* Limit us to a reasonable amount of work. To relax the
11696 other limitations we need bit-shifting of the buffer
11697 and rounding up the size. */
11701 {
11703 unsigned HOST_WIDE_INT len
11708 {
11713 }
11714 }
11715 }
11721 {
11722 /* Build a vector of integers from the tree mask. */
11723 vec_perm_builder builder;
11727 /* Create a vec_perm_indices for the integer vector. */
11732 /* Check for cases that fold to OP0 or OP1 in their original
11733 element order. */
11740 {
11744 {
11747 }
11748 }
11754 {
11758 }
11762 /* Generate a canonical form of the selector. */
11764 {
11765 /* Some targets are deficient and fail to expand a single
11766 argument permutation while still allowing an equivalent
11767 2-argument version. */
11771 else
11772 {
11776 else
11777 /* Not directly supported with either encoding,
11778 so use the preferred form. */
11780 }
11782 }
11786 }
11790 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11793 {
11799 wide_int tem2
11803 }
11808 {
11810 unsigned HOST_WIDE_INT elsize
11813 {
11819 {
11825 }
11826 }
11827 }
11833 }
11835 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11836 of an array (or vector). */
11838 tree
11840 {
11845 {
11848 {
11849 /* Static constructors for variably sized objects makes no sense. */
11853 }
11854 }
11865 offset_int max_index;
11870 {
11871 /* Array constructor might explicitly set index, or specify a range,
11872 or leave index NULL meaning that it is next index after previous
11873 one. */
11875 {
11878 else
11879 {
11883 }
11884 }
11885 else
11886 {
11892 }
11894 /* Do we have match? */
11898 }
11900 }
11902 /* Perform constant folding and related simplification of EXPR.
11903 The related simplifications include x*1 => x, x*0 => 0, etc.,
11904 and application of the associative law.
11905 NOP_EXPR conversions may be removed freely (as long as we
11906 are careful not to change the type of the overall expression).
11907 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11908 but we can constant-fold them if they have constant operands. */
11910 #ifdef ENABLE_FOLD_CHECKING
11911 # define fold(x) fold_1 (x)
11913 static
11914 #endif
11915 tree
11917 {
11921 tree tem;
11924 /* Return right away if a constant. */
11928 /* CALL_EXPR-like objects with variable numbers of operands are
11929 treated specially. */
11931 {
11933 {
11936 }
11938 }
11941 {
11946 {
11964 }
11965 }
11968 {
11970 {
11977 {
11982 }
11985 }
11987 /* Return a VECTOR_CST if possible. */
11989 {
11995 tree val;
12001 }
12009 }
12011 #ifdef ENABLE_FOLD_CHECKING
12012 #undef fold
12019 /* When --enable-checking=fold, compute a digest of expr before
12020 and after actual fold call to see if fold did not accidentally
12021 change original expr. */
12023 tree
12025 {
12026 tree ret;
12046 }
12048 void
12050 {
12061 }
12063 static void
12065 {
12067 }
12069 static void
12072 {
12078 recursive_label:
12088 {
12089 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12094 }
12102 {
12103 /* Allow these fields to be modified. */
12104 tree tmp;
12113 {
12116 }
12117 }
12128 {
12131 {
12147 }
12151 {
12164 }
12181 {
12187 }
12190 {
12192 {
12195 }
12197 }
12208 {
12211 }
12221 }
12222 }
12224 /* Helper function for outputting the checksum of a tree T. When
12225 debugging with gdb, you can "define mynext" to be "next" followed
12226 by "call debug_fold_checksum (op0)", then just trace down till the
12227 outputs differ. */
12229 DEBUG_FUNCTION void
12231 {
12246 }
12248 #endif
12250 /* Fold a unary tree expression with code CODE of type TYPE with an
12251 operand OP0. LOC is the location of the resulting expression.
12252 Return a folded expression if successful. Otherwise, return a tree
12253 expression with code CODE of type TYPE with an operand OP0. */
12255 tree
12258 {
12259 tree tem;
12260 #ifdef ENABLE_FOLD_CHECKING
12269 #endif
12275 #ifdef ENABLE_FOLD_CHECKING
12282 #endif
12284 }
12286 /* Fold a binary tree expression with code CODE of type TYPE with
12287 operands OP0 and OP1. LOC is the location of the resulting
12288 expression. Return a folded expression if successful. Otherwise,
12289 return a tree expression with code CODE of type TYPE with operands
12290 OP0 and OP1. */
12292 tree
12295 MEM_STAT_DECL)
12296 {
12297 tree tem;
12298 #ifdef ENABLE_FOLD_CHECKING
12315 #endif
12321 #ifdef ENABLE_FOLD_CHECKING
12336 #endif
12338 }
12340 /* Fold a ternary tree expression with code CODE of type TYPE with
12341 operands OP0, OP1, and OP2. Return a folded expression if
12342 successful. Otherwise, return a tree expression with code CODE of
12343 type TYPE with operands OP0, OP1, and OP2. */
12345 tree
12348 {
12349 tree tem;
12350 #ifdef ENABLE_FOLD_CHECKING
12374 #endif
12381 #ifdef ENABLE_FOLD_CHECKING
12404 #endif
12406 }
12408 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12409 arguments in ARGARRAY, and a null static chain.
12410 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12411 of type TYPE from the given operands as constructed by build_call_array. */
12413 tree
12416 {
12417 tree tem;
12418 #ifdef ENABLE_FOLD_CHECKING
12437 #endif
12443 #ifdef ENABLE_FOLD_CHECKING
12459 #endif
12461 }
12463 /* Perform constant folding and related simplification of initializer
12464 expression EXPR. These behave identically to "fold_buildN" but ignore
12465 potential run-time traps and exceptions that fold must preserve. */
12467 #define START_FOLD_INIT \
12468 int saved_signaling_nans = flag_signaling_nans;\
12469 int saved_trapping_math = flag_trapping_math;\
12470 int saved_rounding_math = flag_rounding_math;\
12471 int saved_trapv = flag_trapv;\
12472 int saved_folding_initializer = folding_initializer;\
12473 flag_signaling_nans = 0;\
12474 flag_trapping_math = 0;\
12475 flag_rounding_math = 0;\
12476 flag_trapv = 0;\
12477 folding_initializer = 1;
12479 #define END_FOLD_INIT \
12480 flag_signaling_nans = saved_signaling_nans;\
12481 flag_trapping_math = saved_trapping_math;\
12482 flag_rounding_math = saved_rounding_math;\
12483 flag_trapv = saved_trapv;\
12484 folding_initializer = saved_folding_initializer;
12486 tree
12489 {
12490 tree result;
12491 START_FOLD_INIT;
12495 END_FOLD_INIT;
12497 }
12499 tree
12502 {
12503 tree result;
12504 START_FOLD_INIT;
12508 END_FOLD_INIT;
12510 }
12512 tree
12515 {
12516 tree result;
12517 START_FOLD_INIT;
12521 END_FOLD_INIT;
12523 }
12525 #undef START_FOLD_INIT
12526 #undef END_FOLD_INIT
12528 /* Determine if first argument is a multiple of second argument. Return 0 if
12529 it is not, or we cannot easily determined it to be.
12531 An example of the sort of thing we care about (at this point; this routine
12532 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12533 fold cases do now) is discovering that
12535 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12537 is a multiple of
12539 SAVE_EXPR (J * 8)
12541 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12543 This code also handles discovering that
12545 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12547 is a multiple of 8 so we don't have to worry about dealing with a
12548 possible remainder.
12550 Note that we *look* inside a SAVE_EXPR only to determine how it was
12551 calculated; it is not safe for fold to do much of anything else with the
12552 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12553 at run time. For example, the latter example above *cannot* be implemented
12554 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12555 evaluation time of the original SAVE_EXPR is not necessarily the same at
12556 the time the new expression is evaluated. The only optimization of this
12557 sort that would be valid is changing
12559 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12561 divided by 8 to
12563 SAVE_EXPR (I) * SAVE_EXPR (J)
12565 (where the same SAVE_EXPR (J) is used in the original and the
12566 transformed version). */
12568 int
12570 {
12581 {
12583 /* Bitwise and provides a power of two multiple. If the mask is
12584 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12592 {
12598 {
12601 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12603 {
12607 {
12610 }
12611 }
12613 }
12614 }
12619 /* It is impossible to prove if op0 - op1 is multiple of bottom
12620 precisely, so be conservative here checking if both op0 and op1
12621 are multiple of bottom. Note we check the second operand first
12622 since it's usually simpler. */
12627 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12628 as op0 - 3 if the expression has unsigned type. For example,
12629 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12639 {
12641 /* const_binop may not detect overflow correctly,
12642 so check for it explicitly here. */
12650 }
12654 /* Can't handle conversions from non-integral or wider integral type. */
12660 /* fall through */
12677 SIGNED);
12683 {
12686 /* Check for special cases to see if top is defined as multiple
12687 of bottom:
12689 top = (X & ~(bottom - 1) ; bottom is power of 2
12691 or
12693 Y = X % bottom
12694 top = X - Y. */
12713 }
12715 /* fall through */
12723 }
12724 }
12726 #define tree_expr_nonnegative_warnv_p(X, Y) \
12729 #define RECURSE(X) \
12730 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12732 /* Return true if CODE or TYPE is known to be non-negative. */
12734 static bool
12736 {
12739 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12740 have a signed:1 type (where the value is -1 and 0). */
12743 }
12745 /* Return true if (CODE OP0) is known to be non-negative. If the return
12746 value is based on the assumption that signed overflow is undefined,
12747 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12748 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12750 bool
12753 {
12758 {
12760 /* We can't return 1 if flag_wrapv is set because
12761 ABS_EXPR<INT_MIN> = INT_MIN. */
12765 {
12768 }
12776 CASE_CONVERT:
12777 {
12782 {
12786 {
12790 }
12791 }
12793 {
12799 }
12800 }
12805 }
12807 /* We don't know sign of `t', so be conservative and return false. */
12809 }
12811 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12812 value is based on the assumption that signed overflow is undefined,
12813 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12814 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12816 bool
12820 {
12825 {
12831 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12832 both unsigned and at least 2 bits shorter than the result. */
12836 {
12841 {
12845 }
12846 }
12851 {
12852 /* x * x is always non-negative for floating point x
12853 or without overflow. */
12856 {
12861 }
12862 }
12864 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12865 both unsigned and their total bits is shorter than the result. */
12869 {
12888 {
12898 }
12899 }
12926 }
12928 /* We don't know sign of `t', so be conservative and return false. */
12930 }
12932 /* Return true if T is known to be non-negative. If the return
12933 value is based on the assumption that signed overflow is undefined,
12934 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12935 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12937 bool
12939 {
12944 {
12958 /* Limit the depth of recursion to avoid quadratic behavior.
12959 This is expected to catch almost all occurrences in practice.
12960 If this code misses important cases that unbounded recursion
12961 would not, passes that need this information could be revised
12962 to provide it through dataflow propagation. */
12970 }
12971 }
12973 /* Return true if T is known to be non-negative. If the return
12974 value is based on the assumption that signed overflow is undefined,
12975 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12976 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12978 bool
12981 {
12983 {
12984 CASE_CFN_ACOS:
12985 CASE_CFN_ACOSH:
12986 CASE_CFN_CABS:
12987 CASE_CFN_COSH:
12988 CASE_CFN_ERFC:
12989 CASE_CFN_EXP:
12990 CASE_CFN_EXP10:
12991 CASE_CFN_EXP2:
12992 CASE_CFN_FABS:
12993 CASE_CFN_FDIM:
12994 CASE_CFN_HYPOT:
12995 CASE_CFN_POW10:
12996 CASE_CFN_FFS:
12997 CASE_CFN_PARITY:
12998 CASE_CFN_POPCOUNT:
12999 CASE_CFN_CLZ:
13000 CASE_CFN_CLRSB:
13003 /* Always true. */
13006 CASE_CFN_SQRT:
13007 CASE_CFN_SQRT_FN:
13008 /* sqrt(-0.0) is -0.0. */
13013 CASE_CFN_ASINH:
13014 CASE_CFN_ATAN:
13015 CASE_CFN_ATANH:
13016 CASE_CFN_CBRT:
13017 CASE_CFN_CEIL:
13018 CASE_CFN_CEIL_FN:
13019 CASE_CFN_ERF:
13020 CASE_CFN_EXPM1:
13021 CASE_CFN_FLOOR:
13022 CASE_CFN_FLOOR_FN:
13023 CASE_CFN_FMOD:
13024 CASE_CFN_FREXP:
13025 CASE_CFN_ICEIL:
13026 CASE_CFN_IFLOOR:
13027 CASE_CFN_IRINT:
13028 CASE_CFN_IROUND:
13029 CASE_CFN_LCEIL:
13030 CASE_CFN_LDEXP:
13031 CASE_CFN_LFLOOR:
13032 CASE_CFN_LLCEIL:
13033 CASE_CFN_LLFLOOR:
13034 CASE_CFN_LLRINT:
13035 CASE_CFN_LLROUND:
13036 CASE_CFN_LRINT:
13037 CASE_CFN_LROUND:
13038 CASE_CFN_MODF:
13039 CASE_CFN_NEARBYINT:
13040 CASE_CFN_NEARBYINT_FN:
13041 CASE_CFN_RINT:
13042 CASE_CFN_RINT_FN:
13043 CASE_CFN_ROUND:
13044 CASE_CFN_ROUND_FN:
13045 CASE_CFN_SCALB:
13046 CASE_CFN_SCALBLN:
13047 CASE_CFN_SCALBN:
13048 CASE_CFN_SIGNBIT:
13049 CASE_CFN_SIGNIFICAND:
13050 CASE_CFN_SINH:
13051 CASE_CFN_TANH:
13052 CASE_CFN_TRUNC:
13053 CASE_CFN_TRUNC_FN:
13054 /* True if the 1st argument is nonnegative. */
13057 CASE_CFN_FMAX:
13058 CASE_CFN_FMAX_FN:
13059 /* True if the 1st OR 2nd arguments are nonnegative. */
13062 CASE_CFN_FMIN:
13063 CASE_CFN_FMIN_FN:
13064 /* True if the 1st AND 2nd arguments are nonnegative. */
13067 CASE_CFN_COPYSIGN:
13068 CASE_CFN_COPYSIGN_FN:
13069 /* True if the 2nd argument is nonnegative. */
13072 CASE_CFN_POWI:
13073 /* True if the 1st argument is nonnegative or the second
13074 argument is an even integer. */
13080 CASE_CFN_POW:
13081 /* True if the 1st argument is nonnegative or the second
13082 argument is an even integer valued real. */
13084 {
13085 REAL_VALUE_TYPE c;
13086 HOST_WIDE_INT n;
13091 {
13092 REAL_VALUE_TYPE cint;
13096 }
13097 }
13102 }
13104 }
13106 /* Return true if T is known to be non-negative. If the return
13107 value is based on the assumption that signed overflow is undefined,
13108 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13109 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13111 static bool
13113 {
13119 {
13121 {
13125 /* If the initializer is non-void, then it's a normal expression
13126 that will be assigned to the slot. */
13130 /* Otherwise, the initializer sets the slot in some way. One common
13131 way is an assignment statement at the end of the initializer. */
13133 {
13141 else
13143 }
13149 }
13152 {
13158 arg0,
13159 arg1,
13161 }
13174 }
13175 }
13177 #undef RECURSE
13178 #undef tree_expr_nonnegative_warnv_p
13180 /* Return true if T is known to be non-negative. If the return
13181 value is based on the assumption that signed overflow is undefined,
13182 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13183 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13185 bool
13187 {
13194 {
13216 }
13219 {
13245 }
13246 }
13248 /* Return true if `t' is known to be non-negative. Handle warnings
13249 about undefined signed overflow. */
13251 bool
13253 {
13260 "determining that expression is always "
13262 WARN_STRICT_OVERFLOW_MISC);
13264 }
13267 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13268 For floating point we further ensure that T is not denormal.
13269 Similar logic is present in nonzero_address in rtlanal.h.
13271 If the return value is based on the assumption that signed overflow
13272 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13273 change *STRICT_OVERFLOW_P. */
13275 bool
13278 {
13280 {
13283 strict_overflow_p);
13286 {
13292 strict_overflow_p));
13293 }
13298 strict_overflow_p);
13302 }
13305 }
13307 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13308 For floating point we further ensure that T is not denormal.
13309 Similar logic is present in nonzero_address in rtlanal.h.
13311 If the return value is based on the assumption that signed overflow
13312 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13313 change *STRICT_OVERFLOW_P. */
13315 bool
13317 tree type,
13318 tree op0,
13320 {
13323 {
13327 {
13328 /* With the presence of negative values it is hard
13329 to say something. */
13336 /* One of operands must be positive and the other non-negative. */
13337 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13338 overflows, on a twos-complement machine the sum of two
13339 nonnegative numbers can never be zero. */
13341 strict_overflow_p)
13343 strict_overflow_p));
13344 }
13349 {
13351 strict_overflow_p)
13353 strict_overflow_p))
13354 {
13357 }
13358 }
13367 {
13370 }
13377 {
13381 /* When both operands are nonzero, then MAX must be too. */
13383 strict_overflow_p))
13386 /* MAX where operand 0 is positive is positive. */
13388 strict_overflow_p);
13389 }
13390 /* MAX where operand 1 is positive is positive. */
13395 {
13399 }
13404 strict_overflow_p)
13406 strict_overflow_p));
13410 }
13413 }
13415 /* Return true when T is an address and is known to be nonzero.
13416 For floating point we further ensure that T is not denormal.
13417 Similar logic is present in nonzero_address in rtlanal.h.
13419 If the return value is based on the assumption that signed overflow
13420 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13421 change *STRICT_OVERFLOW_P. */
13423 bool
13425 {
13428 {
13433 {
13445 /* For objects in symbol table check if we know they are non-zero.
13446 Don't do anything for variables and functions before symtab is built;
13447 it is quite possible that they will be declared weak later. */
13452 /* Constants are never weak. */
13457 }
13465 {
13469 }
13479 }
13481 }
13483 #define integer_valued_real_p(X) \
13486 #define RECURSE(X) \
13487 ((integer_valued_real_p) (X, depth + 1))
13489 /* Return true if the floating point result of (CODE OP0) has an
13490 integer value. We also allow +Inf, -Inf and NaN to be considered
13491 integer values. Return false for signaling NaN.
13493 DEPTH is the current nesting depth of the query. */
13495 bool
13497 {
13499 {
13506 CASE_CONVERT:
13507 {
13514 }
13518 }
13520 }
13522 /* Return true if the floating point result of (CODE OP0 OP1) has an
13523 integer value. We also allow +Inf, -Inf and NaN to be considered
13524 integer values. Return false for signaling NaN.
13526 DEPTH is the current nesting depth of the query. */
13528 bool
13530 {
13532 {
13542 }
13544 }
13546 /* Return true if the floating point result of calling FNDECL with arguments
13547 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13548 considered integer values. Return false for signaling NaN. If FNDECL
13549 takes fewer than 2 arguments, the remaining ARGn are null.
13551 DEPTH is the current nesting depth of the query. */
13553 bool
13555 {
13557 {
13558 CASE_CFN_CEIL:
13559 CASE_CFN_CEIL_FN:
13560 CASE_CFN_FLOOR:
13561 CASE_CFN_FLOOR_FN:
13562 CASE_CFN_NEARBYINT:
13563 CASE_CFN_NEARBYINT_FN:
13564 CASE_CFN_RINT:
13565 CASE_CFN_RINT_FN:
13566 CASE_CFN_ROUND:
13567 CASE_CFN_ROUND_FN:
13568 CASE_CFN_TRUNC:
13569 CASE_CFN_TRUNC_FN:
13572 CASE_CFN_FMIN:
13573 CASE_CFN_FMIN_FN:
13574 CASE_CFN_FMAX:
13575 CASE_CFN_FMAX_FN:
13580 }
13582 }
13584 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13585 has an integer value. We also allow +Inf, -Inf and NaN to be
13586 considered integer values. Return false for signaling NaN.
13588 DEPTH is the current nesting depth of the query. */
13590 bool
13592 {
13594 {
13602 /* Limit the depth of recursion to avoid quadratic behavior.
13603 This is expected to catch almost all occurrences in practice.
13604 If this code misses important cases that unbounded recursion
13605 would not, passes that need this information could be revised
13606 to provide it through dataflow propagation. */
13610 depth));
13614 }
13616 }
13618 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13619 has an integer value. We also allow +Inf, -Inf and NaN to be
13620 considered integer values. Return false for signaling NaN.
13622 DEPTH is the current nesting depth of the query. */
13624 static bool
13626 {
13628 {
13639 }
13641 }
13643 #undef RECURSE
13644 #undef integer_valued_real_p
13646 /* Return true if the floating point expression T has an integer value.
13647 We also allow +Inf, -Inf and NaN to be considered integer values.
13648 Return false for signaling NaN.
13650 DEPTH is the current nesting depth of the query. */
13652 bool
13654 {
13660 {
13676 }
13679 {
13685 {
13694 }
13698 }
13699 }
13701 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13702 attempt to fold the expression to a constant without modifying TYPE,
13703 OP0 or OP1.
13705 If the expression could be simplified to a constant, then return
13706 the constant. If the expression would not be simplified to a
13707 constant, then return NULL_TREE. */
13709 tree
13711 {
13714 }
13716 /* Given the components of a unary expression CODE, TYPE and OP0,
13717 attempt to fold the expression to a constant without modifying
13718 TYPE or OP0.
13720 If the expression could be simplified to a constant, then return
13721 the constant. If the expression would not be simplified to a
13722 constant, then return NULL_TREE. */
13724 tree
13726 {
13729 }
13731 /* If EXP represents referencing an element in a constant string
13732 (either via pointer arithmetic or array indexing), return the
13733 tree representing the value accessed, otherwise return NULL. */
13735 tree
13737 {
13741 {
13743 tree index;
13744 tree string;
13749 else
13750 {
13754 /* Optimize the special-case of a zero lower bound.
13756 We convert the low_bound to sizetype to avoid some problems
13757 with constant folding. (E.g. suppose the lower bound is 1,
13758 and its mode is QI. Without the conversion,l (ARRAY
13759 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13760 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13766 }
13768 scalar_int_mode char_mode;
13780 }
13782 }
13784 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13785 an integer constant, real, or fixed-point constant.
13787 TYPE is the type of the result. */
13789 static tree
13791 {
13795 {
13801 {
13802 FIXED_VALUE_TYPE f;
13807 /* Propagate overflow flags. */
13811 }
13815 {
13822 }
13825 }
13828 }
13830 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13831 an integer constant or real constant.
13833 TYPE is the type of the result. */
13835 tree
13837 {
13841 {
13843 {
13844 /* If the value is unsigned or non-negative, then the absolute value
13845 is the same as the ordinary value. */
13849 /* If the value is negative, then the absolute value is
13850 its negation. */
13851 else
13852 {
13857 }
13858 }
13864 else
13870 }
13873 }
13875 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13876 constant. TYPE is the type of the result. */
13878 static tree
13880 {
13884 }
13886 /* Given CODE, a relational operator, the target type, TYPE and two
13887 constant operands OP0 and OP1, return the result of the
13888 relational operation. If the result is not a compile time
13889 constant, then return NULL_TREE. */
13891 static tree
13893 {
13896 /* From here on, the only cases we handle are when the result is
13897 known to be a constant. */
13900 {
13904 /* Handle the cases where either operand is a NaN. */
13906 {
13908 {
13936 }
13939 }
13942 }
13945 {
13949 }
13951 /* Handle equality/inequality of complex constants. */
13953 {
13964 else
13966 }
13969 {
13971 {
13972 /* Have vector comparison with scalar boolean result. */
13980 {
13988 }
13990 }
13991 tree_vector_builder elts;
13996 {
14009 }
14012 }
14014 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14016 To compute GT, swap the arguments and do LT.
14017 To compute GE, do LT and invert the result.
14018 To compute LE, swap the arguments, do LT and invert the result.
14019 To compute NE, do EQ and invert the result.
14021 Therefore, the code below must handle only EQ and LT. */
14024 {
14027 }
14029 /* Note that it is safe to invert for real values here because we
14030 have already handled the one case that it matters. */
14034 {
14037 }
14039 /* Compute a result for LT or EQ if args permit;
14040 Otherwise return T. */
14042 {
14045 else
14047 }
14048 else
14054 }
14056 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14057 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14058 itself. */
14060 tree
14062 {
14063 /* If the expression does not have side effects then we don't have to wrap
14064 it with a cleanup point expression. */
14068 /* If the expression is a return, check to see if the expression inside the
14069 return has no side effects or the right hand side of the modify expression
14070 inside the return. If either don't have side effects set we don't need to
14071 wrap the expression in a cleanup point expression. Note we don't check the
14072 left hand side of the modify because it should always be a return decl. */
14074 {
14081 }
14084 }
14086 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14087 of an indirection through OP0, or NULL_TREE if no simplification is
14088 possible. */
14090 tree
14092 {
14094 tree subtype;
14095 poly_uint64 const_op01;
14104 {
14108 /* *&CONST_DECL -> to the value of the const decl. */
14111 /* *&p => p; make sure to handle *&"str"[cst] here. */
14113 {
14117 else
14119 }
14120 /* *(foo *)&fooarray => fooarray[0] */
14123 && (!in_gimple_form
14125 {
14135 }
14136 /* *(foo *)&complexfoo => __real__ complexfoo */
14140 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14143 {
14147 index);
14148 }
14149 }
14153 {
14159 {
14160 tree op00type;
14164 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14167 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14168 but we want to treat offsets with MSB set as negative.
14169 For the code below negative offsets are invalid and
14170 TYPE_SIZE of the element is something unsigned, so
14171 check whether op01 fits into poly_int64, which implies
14172 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14173 then just use poly_uint64 because we want to treat the
14174 value as unsigned. */
14176 {
14178 poly_uint64 max_offset
14182 {
14187 }
14188 }
14189 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14192 {
14194 const_op01))
14196 }
14197 /* ((foo *)&fooarray)[1] => fooarray[1] */
14200 {
14209 {
14214 }
14215 }
14216 }
14217 }
14219 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14222 && (!in_gimple_form
14224 {
14225 tree type_domain;
14235 NULL_TREE);
14236 }
14239 }
14241 /* Builds an expression for an indirection through T, simplifying some
14242 cases. */
14244 tree
14246 {
14254 }
14256 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14258 tree
14260 {
14265 else
14267 }
14269 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14270 whose result is ignored. The type of the returned tree need not be
14271 the same as the original expression. */
14273 tree
14275 {
14281 {
14292 else
14298 {
14314 }
14319 }
14320 }
14322 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14324 tree
14326 {
14332 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14333 have to do anything. Only do this when we are not given a const,
14334 because in that case, this check is more expensive than just
14335 doing it. */
14337 {
14342 }
14344 /* If divisor is a power of two, simplify this to bit manipulation. */
14346 {
14348 {
14362 }
14363 else
14364 {
14365 tree t;
14371 }
14372 }
14373 else
14374 {
14379 }
14382 }
14384 /* Likewise, but round down. */
14386 tree
14388 {
14395 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14396 have to do anything. Only do this when we are not given a const,
14397 because in that case, this check is more expensive than just
14398 doing it. */
14400 {
14405 }
14407 /* If divisor is a power of two, simplify this to bit manipulation. */
14409 {
14410 tree t;
14414 }
14415 else
14416 {
14421 }
14424 }
14426 /* Returns the pointer to the base of the object addressed by EXP and
14427 extracts the information about the offset of the access, storing it
14428 to PBITPOS and POFFSET. */
14430 static tree
14433 {
14434 tree core;
14435 machine_mode mode;
14437 poly_int64 bitsize;
14441 {
14446 }
14448 {
14454 {
14455 poly_offset_int tem
14461 }
14462 }
14463 else
14464 {
14468 }
14471 }
14473 /* Returns true if addresses of E1 and E2 differ by a constant, false
14474 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14476 bool
14478 {
14493 {
14503 }
14505 {
14506 /* If only one of the offsets is non-constant, the difference cannot
14507 be a constant. */
14509 }
14510 else
14515 }
14517 /* Return OFF converted to a pointer offset type suitable as offset for
14518 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14519 tree
14521 {
14523 }
14525 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14526 tree
14528 {
14531 }
14533 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14534 tree
14536 {
14539 }
14541 /* Return a char pointer for a C string if it is a string constant
14542 or sum of string constant and integer constant. We only support
14543 string constants properly terminated with '\0' character.
14544 If STRLEN is a valid pointer, length (including terminating character)
14545 of returned string is stored to the argument. */
14549 {
14550 tree offset_node;
14561 {
14564 else
14566 }
14571 /* Support only properly null-terminated strings. */
14580 }
14582 /* Given a tree T, compute which bits in T may be nonzero. */
14584 wide_int
14586 {
14588 {
14606 CASE_CONVERT:
14612 {
14617 }
14621 {
14629 }
14633 {
14641 }
14645 }
14648 }
14650 #if CHECKING_P
14654 /* Helper functions for writing tests of folding trees. */
14656 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14658 static void
14660 tree constant)
14661 {
14663 }
14665 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14666 wrapping WRAPPED_EXPR. */
14668 static void
14670 tree wrapped_expr)
14671 {
14676 }
14678 /* Verify that various arithmetic binary operations are folded
14679 correctly. */
14681 static void
14683 {
14689 /* Addition. */
14690 /* 1 <-- (0 + 1) */
14692 one);
14694 one);
14696 /* (nonlvalue)x <-- (x + 0) */
14698 x);
14700 /* Subtraction. */
14701 /* 0 <-- (x - x) */
14703 zero);
14705 x);
14707 /* Multiplication. */
14708 /* 0 <-- (x * 0) */
14710 zero);
14712 /* (nonlvalue)x <-- (x * 1) */
14714 x);
14715 }
14717 /* Verify that various binary operations on vectors are folded
14718 correctly. */
14720 static void
14722 {
14728 /* Verify equality tests that return a scalar boolean result. */
14734 }
14736 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14738 static void
14740 {
14743 /* This will be 1 if VEC_MODE isn't a vector mode. */
14750 }
14752 /* Run all of the selftests within this file. */
14754 void
14756 {
14760 }