| blob | 1197d75ec75924d5aa17b7073aa17f6956103831 |
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. */
1734 {
1735 CASE_CONVERT:
1742 /* If the source address is 0, and the source address space
1743 cannot have a valid object at 0, fold to dest type null. */
1754 {
1755 /* Can't call fold_negate_const directly here as that doesn't
1756 handle all cases and we might not be able to negate some
1757 constants. */
1762 }
1772 {
1776 }
1784 /* Perform BIT_NOT_EXPR on each element individually. */
1786 {
1787 tree elem;
1789 /* This can cope with stepped encodings because ~x == -1 - x. */
1790 tree_vector_builder elements;
1794 {
1800 }
1803 }
1827 {
1850 else
1855 {
1861 }
1864 }
1873 }
1876 }
1878 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1879 indicates which particular sizetype to create. */
1881 tree
1883 {
1885 }
1886 \f
1887 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1888 is a tree code. The type of the result is taken from the operands.
1889 Both must be equivalent integer types, ala int_binop_types_match_p.
1890 If the operands are constant, so is the result. */
1892 tree
1894 {
1903 /* Handle the special case of two poly_int constants faster. */
1905 {
1906 /* And some specific cases even faster than that. */
1908 {
1913 }
1915 {
1918 }
1920 {
1923 }
1925 /* Handle general case of two integer constants. For sizetype
1926 constant calculations we always want to know about overflow,
1927 even in the unsigned case. */
1931 }
1934 }
1936 /* Given two values, either both of sizetype or both of bitsizetype,
1937 compute the difference between the two values. Return the value
1938 in signed type corresponding to the type of the operands. */
1940 tree
1942 {
1944 tree ctype;
1949 /* If the type is already signed, just do the simple thing. */
1957 else
1960 /* If either operand is not a constant, do the conversions to the signed
1961 type and subtract. The hardware will do the right thing with any
1962 overflow in the subtraction. */
1968 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1969 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1970 overflow) and negate (which can't either). Special-case a result
1971 of zero while we're here. */
1977 else
1981 MINUS_EXPR,
1983 }
1984 \f
1985 /* A subroutine of fold_convert_const handling conversions of an
1986 INTEGER_CST to another integer type. */
1988 static tree
1990 {
1991 /* Given an integer constant, make new constant with new type,
1992 appropriately sign-extended or truncated. Use widest_int
1993 so that any extension is done according ARG1's type. */
1997 }
1999 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2000 to an integer type. */
2002 static tree
2004 {
2006 tree t;
2008 /* The following code implements the floating point to integer
2009 conversion rules required by the Java Language Specification,
2010 that IEEE NaNs are mapped to zero and values that overflow
2011 the target precision saturate, i.e. values greater than
2012 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2013 are mapped to INT_MIN. These semantics are allowed by the
2014 C and C++ standards that simply state that the behavior of
2015 FP-to-integer conversion is unspecified upon overflow. */
2017 wide_int val;
2018 REAL_VALUE_TYPE r;
2022 {
2029 }
2031 /* If R is NaN, return zero and show we have an overflow. */
2033 {
2036 }
2038 /* See if R is less than the lower bound or greater than the
2039 upper bound. */
2042 {
2046 {
2049 }
2050 }
2053 {
2056 {
2059 {
2062 }
2063 }
2064 }
2071 }
2073 /* A subroutine of fold_convert_const handling conversions of a
2074 FIXED_CST to an integer type. */
2076 static tree
2078 {
2079 tree t;
2081 scalar_mode mode;
2083 /* Right shift FIXED_CST to temp by fbit. */
2087 {
2089 HOST_BITS_PER_DOUBLE_INT,
2092 /* Left shift temp to temp_trunc by fbit. */
2094 HOST_BITS_PER_DOUBLE_INT,
2096 }
2097 else
2098 {
2101 }
2103 /* If FIXED_CST is negative, we need to round the value toward 0.
2104 By checking if the fractional bits are not zero to add 1 to temp. */
2110 /* Given a fixed-point constant, make new constant with new type,
2111 appropriately sign-extended or truncated. */
2119 }
2121 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2122 to another floating point type. */
2124 static tree
2126 {
2127 REAL_VALUE_TYPE value;
2128 tree t;
2130 /* Don't perform the operation if flag_signaling_nans is on
2131 and the operand is a signaling NaN. */
2139 /* If converting an infinity or NAN to a representation that doesn't
2140 have one, set the overflow bit so that we can produce some kind of
2141 error message at the appropriate point if necessary. It's not the
2142 most user-friendly message, but it's better than nothing. */
2149 /* Regular overflow, conversion produced an infinity in a mode that
2150 can't represent them. */
2155 else
2158 }
2160 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2161 to a floating point type. */
2163 static tree
2165 {
2166 REAL_VALUE_TYPE value;
2167 tree t;
2175 }
2177 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2178 to another fixed-point type. */
2180 static tree
2182 {
2183 FIXED_VALUE_TYPE value;
2184 tree t;
2191 /* Propagate overflow flags. */
2195 }
2197 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2198 to a fixed-point type. */
2200 static tree
2202 {
2203 FIXED_VALUE_TYPE value;
2204 tree t;
2206 double_int di;
2213 else
2221 /* Propagate overflow flags. */
2225 }
2227 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2228 to a fixed-point type. */
2230 static tree
2232 {
2233 FIXED_VALUE_TYPE value;
2234 tree t;
2242 /* Propagate overflow flags. */
2246 }
2248 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2249 type TYPE. If no simplification can be done return NULL_TREE. */
2251 static tree
2253 {
2258 /* We can't widen types, since the runtime value could overflow the
2259 original type before being extended to the new type. */
2270 {
2277 }
2279 {
2286 }
2288 {
2295 }
2297 {
2300 {
2303 /* We can't handle steps directly when extending, since the
2304 values need to wrap at the original precision first. */
2305 bool step_ok_p
2309 tree_vector_builder v;
2314 {
2320 }
2322 }
2323 }
2325 }
2327 /* Construct a vector of zero elements of vector type TYPE. */
2329 static tree
2331 {
2332 tree t;
2336 }
2338 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2340 bool
2342 {
2357 {
2374 }
2375 }
2377 /* Convert expression ARG to type TYPE. Used by the middle-end for
2378 simple conversions in preference to calling the front-end's convert. */
2380 tree
2382 {
2384 tree tem;
2395 {
2398 /* Handle conversions between pointers to different address spaces. */
2403 /* fall through */
2408 {
2412 }
2426 {
2430 }
2432 {
2436 }
2438 {
2442 }
2445 {
2463 }
2468 {
2472 }
2475 {
2489 }
2493 {
2502 integer_zero_node));
2504 {
2508 {
2514 }
2522 }
2526 }
2544 }
2545 fold_convert_exit:
2548 }
2549 \f
2550 /* Return false if expr can be assumed not to be an lvalue, true
2551 otherwise. */
2553 static bool
2555 {
2556 /* We only need to wrap lvalue tree codes. */
2558 {
2589 /* Assume the worst for front-end tree codes. */
2593 }
2596 }
2598 /* Return an expr equal to X but certainly not valid as an lvalue. */
2600 tree
2602 {
2603 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2604 us. */
2611 }
2613 /* When pedantic, return an expr equal to X but certainly not valid as a
2614 pedantic lvalue. Otherwise, return X. */
2616 static tree
2618 {
2620 }
2621 \f
2622 /* Given a tree comparison code, return the code that is the logical inverse.
2623 It is generally not safe to do this for floating-point comparisons, except
2624 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2625 ERROR_MARK in this case. */
2627 enum tree_code
2629 {
2635 {
2666 }
2667 }
2669 /* Similar, but return the comparison that results if the operands are
2670 swapped. This is safe for floating-point. */
2672 enum tree_code
2674 {
2676 {
2702 }
2703 }
2706 /* Convert a comparison tree code from an enum tree_code representation
2707 into a compcode bit-based encoding. This function is the inverse of
2708 compcode_to_comparison. */
2710 static enum comparison_code
2712 {
2714 {
2745 }
2746 }
2748 /* Convert a compcode bit-based encoding of a comparison operator back
2749 to GCC's enum tree_code representation. This function is the
2750 inverse of comparison_to_compcode. */
2752 static enum tree_code
2754 {
2756 {
2787 }
2788 }
2790 /* Return true if COND1 tests the opposite condition of COND2. */
2792 bool
2794 {
2797 && (invert_tree_comparison
2804 }
2806 /* Return a tree for the comparison which is the combination of
2807 doing the AND or OR (depending on CODE) of the two operations LCODE
2808 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2809 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2810 if this makes the transformation invalid. */
2812 tree
2817 {
2824 {
2835 }
2838 {
2839 /* Eliminate unordered comparisons, as well as LTGT and ORD
2840 which are not used unless the mode has NaNs. */
2846 }
2848 {
2849 /* Check that the original operation and the optimized ones will trap
2850 under the same condition. */
2861 /* In a short-circuited boolean expression the LHS might be
2862 such that the RHS, if evaluated, will never trap. For
2863 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2864 if neither x nor y is NaN. (This is a mixed blessing: for
2865 example, the expression above will never trap, hence
2866 optimizing it to x < y would be invalid). */
2871 /* If the comparison was short-circuited, and only the RHS
2872 trapped, we may now generate a spurious trap. */
2877 /* If we changed the conditions that cause a trap, we lose. */
2880 }
2886 else
2887 {
2892 }
2893 }
2894 \f
2895 /* Return nonzero if two operands (typically of the same tree node)
2896 are necessarily equal. FLAGS modifies behavior as follows:
2898 If OEP_ONLY_CONST is set, only return nonzero for constants.
2899 This function tests whether the operands are indistinguishable;
2900 it does not test whether they are equal using C's == operation.
2901 The distinction is important for IEEE floating point, because
2902 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2903 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2905 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2906 even though it may hold multiple values during a function.
2907 This is because a GCC tree node guarantees that nothing else is
2908 executed between the evaluation of its "operands" (which may often
2909 be evaluated in arbitrary order). Hence if the operands themselves
2910 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2911 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2912 unset means assuming isochronic (or instantaneous) tree equivalence.
2913 Unless comparing arbitrary expression trees, such as from different
2914 statements, this flag can usually be left unset.
2916 If OEP_PURE_SAME is set, then pure functions with identical arguments
2917 are considered the same. It is used when the caller has other ways
2918 to ensure that global memory is unchanged in between.
2920 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2921 not values of expressions.
2923 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2924 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2926 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2927 any operand with side effect. This is unnecesarily conservative in the
2928 case we know that arg0 and arg1 are in disjoint code paths (such as in
2929 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2930 addresses with TREE_CONSTANT flag set so we know that &var == &var
2931 even if var is volatile. */
2933 int
2935 {
2936 /* When checking, verify at the outermost operand_equal_p call that
2937 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2938 hash value. */
2940 {
2942 {
2944 {
2951 }
2953 }
2954 else
2956 }
2958 /* If either is ERROR_MARK, they aren't equal. */
2964 /* Similar, if either does not have a type (like a released SSA name),
2965 they aren't equal. */
2969 /* We cannot consider pointers to different address space equal. */
2976 /* Check equality of integer constants before bailing out due to
2977 precision differences. */
2979 {
2980 /* Address of INTEGER_CST is not defined; check that we did not forget
2981 to drop the OEP_ADDRESS_OF flags. */
2984 }
2987 {
2988 /* If both types don't have the same signedness, then we can't consider
2989 them equal. We must check this before the STRIP_NOPS calls
2990 because they may change the signedness of the arguments. As pointers
2991 strictly don't have a signedness, require either two pointers or
2992 two non-pointers as well. */
2998 /* If both types don't have the same precision, then it is not safe
2999 to strip NOPs. */
3006 }
3007 #if 0
3008 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
3009 sanity check once the issue is solved. */
3010 else
3011 /* Addresses of conversions and SSA_NAMEs (and many other things)
3012 are not defined. Check that we did not forget to drop the
3013 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3016 #endif
3018 /* In case both args are comparisons but with different comparison
3019 code, try to swap the comparison operands of one arg to produce
3020 a match and compare that variant. */
3024 {
3032 }
3035 {
3036 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3038 ;
3040 {
3041 /* If we are interested in comparing addresses ignore
3042 MEM_REF wrappings of the base that can appear just for
3043 TBAA reasons. */
3057 }
3058 else
3060 }
3062 /* When not checking adddresses, this is needed for conversions and for
3063 COMPONENT_REF. Might as well play it safe and always test this. */
3070 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3071 We don't care about side effects in that case because the SAVE_EXPR
3072 takes care of that for us. In all other cases, two expressions are
3073 equal if they have no side effects. If we have two identical
3074 expressions with side effects that should be treated the same due
3075 to the only side effects being identical SAVE_EXPR's, that will
3076 be detected in the recursive calls below.
3077 If we are taking an invariant address of two identical objects
3078 they are necessarily equal as well. */
3085 /* Next handle constant cases, those for which we can return 1 even
3086 if ONLY_CONST is set. */
3089 {
3103 {
3104 /* If we do not distinguish between signed and unsigned zero,
3105 consider them equal. */
3108 }
3112 {
3127 }
3131 flags)
3133 flags));
3144 flags | OEP_ADDRESS_OF
3147 /* In GIMPLE empty constructors are allowed in initializers of
3148 aggregates. */
3152 }
3157 /* Define macros to test an operand from arg0 and arg1 for equality and a
3158 variant that allows null and views null as being different from any
3159 non-null value. In the latter case, if either is null, the both
3160 must be; otherwise, do the normal comparison. */
3161 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3162 TREE_OPERAND (arg1, N), flags)
3164 #define OP_SAME_WITH_NULL(N) \
3165 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3166 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3169 {
3171 /* Two conversions are equal only if signedness and modes match. */
3173 {
3174 CASE_CONVERT:
3182 }
3192 /* For commutative ops, allow the other order. */
3200 /* If either of the pointer (or reference) expressions we are
3201 dereferencing contain a side effect, these cannot be equal,
3202 but their addresses can be. */
3209 {
3219 /* Require the same offset. */
3225 /* Fallthru. */
3233 {
3234 /* Require equal access sizes */
3240 flags)))
3242 /* Verify that access happens in similar types. */
3245 /* Verify that accesses are TBAA compatible. */
3254 /* Verify that alignment is compatible. */
3258 }
3261 /* TARGET_MEM_REF require equal extra operands. */
3272 /* Compare the array index by value if it is constant first as we
3273 may have different types but same value here. */
3279 /* Compare low bound and element size as with OEP_ADDRESS_OF
3280 we have to account for the offset of the ref. */
3285 array_ref_low_bound
3289 array_ref_element_size
3291 flags))));
3294 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3295 may be NULL when we're called to compare MEM_EXPRs. */
3310 }
3314 {
3316 /* Be sure we pass right ADDRESS_OF flag. */
3333 /* The multiplcation operands are commutative. */
3334 /* FALLTHRU */
3342 /* Otherwise take into account this is a commutative operation. */
3355 /* BIT_INSERT_EXPR has an implict operand as the type precision
3356 of op1. Need to check to make sure they are the same. */
3362 /* FALLTHRU */
3388 }
3392 {
3396 /* If not both CALL_EXPRs are either internal or normal function
3397 functions, then they are not equal. */
3400 {
3401 /* If the CALL_EXPRs call different internal functions, then they
3402 are not equal. */
3405 }
3406 else
3407 {
3408 /* If the CALL_EXPRs call different functions, then they are not
3409 equal. */
3411 flags))
3413 }
3415 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3416 {
3420 else
3424 }
3426 /* Now see if all the arguments are the same. */
3427 {
3438 /* If we get here and both argument lists are exhausted
3439 then the CALL_EXPRs are equal. */
3441 }
3444 }
3447 /* Consider __builtin_sqrt equal to sqrt. */
3455 {
3456 /* In GIMPLE constructors are used only to build vectors from
3457 elements. Individual elements in the constructor must be
3458 indexed in increasing order and form an initial sequence.
3460 We make no effort to compare constructors in generic.
3461 (see sem_variable::equals in ipa-icf which can do so for
3462 constants). */
3467 /* Be sure that vectors constructed have the same representation.
3468 We only tested element precision and modes to match.
3469 Vectors may be BLKmode and thus also check that the number of
3470 parts match. */
3483 {
3488 /* In GIMPLE the indexes can be either NULL or matching i.
3489 Double check this so we won't get false
3490 positives for GENERIC. */
3498 }
3500 }
3503 {
3504 /* Compare the STATEMENT_LISTs. */
3510 {
3511 /* The lists don't have the same number of statements. */
3517 flags & (OEP_LEXICOGRAPHIC
3520 }
3521 }
3526 {
3537 }
3541 }
3543 #undef OP_SAME
3544 #undef OP_SAME_WITH_NULL
3545 }
3546 \f
3547 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3548 with a different signedness or a narrower precision. */
3550 static bool
3552 {
3560 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3561 and see if the inner values are the same. This removes any
3562 signedness comparison, which doesn't matter here. */
3570 /* Discard a single widening conversion from ARG1 and see if the inner
3571 value is the same as ARG0. */
3580 }
3581 \f
3582 /* See if ARG is an expression that is either a comparison or is performing
3583 arithmetic on comparisons. The comparisons must only be comparing
3584 two different values, which will be stored in *CVAL1 and *CVAL2; if
3585 they are nonzero it means that some operands have already been found.
3586 No variables may be used anywhere else in the expression except in the
3587 comparisons.
3589 If this is true, return 1. Otherwise, return zero. */
3591 static int
3593 {
3597 /* We can handle some of the tcc_expression cases here. */
3606 {
3625 /* First see if we can handle the first operand, then the second. For
3626 the second operand, we know *CVAL1 can't be zero. It must be that
3627 one side of the comparison is each of the values; test for the
3628 case where this isn't true by failing if the two operands
3629 are the same. */
3638 ;
3642 ;
3643 else
3647 ;
3651 ;
3652 else
3659 }
3660 }
3661 \f
3662 /* ARG is a tree that is known to contain just arithmetic operations and
3663 comparisons. Evaluate the operations in the tree substituting NEW0 for
3664 any occurrence of OLD0 as an operand of a comparison and likewise for
3665 NEW1 and OLD1. */
3667 static tree
3670 {
3675 /* We can handle some of the tcc_expression cases here. */
3683 {
3698 {
3717 }
3718 /* Fall through - ??? */
3721 {
3725 /* We need to check both for exact equality and tree equality. The
3726 former will be true if the operand has a side-effect. In that
3727 case, we know the operand occurred exactly once. */
3740 }
3744 }
3745 }
3746 \f
3747 /* Return a tree for the case when the result of an expression is RESULT
3748 converted to TYPE and OMITTED was previously an operand of the expression
3749 but is now not needed (e.g., we folded OMITTED * 0).
3751 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3752 the conversion of RESULT to TYPE. */
3754 tree
3756 {
3759 /* If the resulting operand is an empty statement, just return the omitted
3760 statement casted to void. */
3770 }
3772 /* Return a tree for the case when the result of an expression is RESULT
3773 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3774 of the expression but are now not needed.
3776 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3777 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3778 evaluated before OMITTED2. Otherwise, if neither has side effects,
3779 just do the conversion of RESULT to TYPE. */
3781 tree
3784 {
3793 }
3795 \f
3796 /* Return a simplified tree node for the truth-negation of ARG. This
3797 never alters ARG itself. We assume that ARG is an operation that
3798 returns a truth value (0 or 1).
3800 FIXME: one would think we would fold the result, but it causes
3801 problems with the dominator optimizer. */
3803 static tree
3805 {
3810 /* If this is a comparison, we can simply invert it, except for
3811 floating-point non-equality comparisons, in which case we just
3812 enclose a TRUTH_NOT_EXPR around what we have. */
3815 {
3818 && flag_trapping_math
3832 }
3835 {
3854 /* Here we can invert either operand. We invert the first operand
3855 unless the second operand is a TRUTH_NOT_EXPR in which case our
3856 result is the XOR of the first operand with the inside of the
3857 negation of the second operand. */
3862 else
3885 {
3892 /* A COND_EXPR may have a throw as one operand, which
3893 then has void type. Just leave void operands
3894 as they are. */
3900 }
3912 CASE_CONVERT:
3916 /* fall through */
3938 }
3939 }
3941 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3942 assume that ARG is an operation that returns a truth value (0 or 1
3943 for scalars, 0 or -1 for vectors). Return the folded expression if
3944 folding is successful. Otherwise, return NULL_TREE. */
3946 static tree
3948 {
3951 ? BIT_NOT_EXPR
3954 }
3956 /* Return a simplified tree node for the truth-negation of ARG. This
3957 never alters ARG itself. We assume that ARG is an operation that
3958 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3960 tree
3962 {
3968 ? BIT_NOT_EXPR
3971 }
3972 \f
3973 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3974 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3975 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3976 is the original memory reference used to preserve the alias set of
3977 the access. */
3979 static tree
3983 {
3986 /* Attempt not to lose the access path if possible. */
3988 {
3990 machine_mode nmode;
3992 tree noffset;
4000 && !reversep
4001 && !nreversep
4003 {
4006 }
4007 }
4016 {
4023 }
4038 }
4040 /* Optimize a bit-field compare.
4042 There are two cases: First is a compare against a constant and the
4043 second is a comparison of two items where the fields are at the same
4044 bit position relative to the start of a chunk (byte, halfword, word)
4045 large enough to contain it. In these cases we can avoid the shift
4046 implicit in bitfield extractions.
4048 For constants, we emit a compare of the shifted constant with the
4049 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4050 compared. For two fields at the same position, we do the ANDs with the
4051 similar mask and compare the result of the ANDs.
4053 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4054 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4055 are the left and right operands of the comparison, respectively.
4057 If the optimization described above can be done, we return the resulting
4058 tree. Otherwise we return zero. */
4060 static tree
4063 {
4067 tree unsigned_type;
4070 scalar_int_mode nmode;
4075 tree mask;
4076 tree offset;
4078 /* Get all the information about the extractions being done. If the bit size
4079 is the same as the size of the underlying object, we aren't doing an
4080 extraction at all and so can do nothing. We also don't want to
4081 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4082 then will no longer be able to replace it. */
4097 else
4098 {
4099 /* If this is not a constant, we can only do something if bit positions,
4100 sizes, signedness and storage order are the same. */
4101 rinner
4114 }
4116 /* Honor the C++ memory model and mimic what RTL expansion does. */
4120 {
4124 }
4126 /* See if we can find a mode to refer to this field. We should be able to,
4127 but fail if we can't. */
4135 /* Set signed and unsigned types of the precision of this mode for the
4136 shifts below. */
4139 /* Compute the bit position and size for the new reference and our offset
4140 within it. If the new reference is the same size as the original, we
4141 won't optimize anything, so return zero. */
4151 /* Make the mask to be used against the extracted field. */
4158 {
4162 /* If not comparing with constant, just rework the comparison
4163 and return. */
4171 }
4173 /* Otherwise, we are handling the constant case. See if the constant is too
4174 big for the field. Warn and return a tree for 0 (false) if so. We do
4175 this not only for its own sake, but to avoid having to test for this
4176 error case below. If we didn't, we might generate wrong code.
4178 For unsigned fields, the constant shifted right by the field length should
4179 be all zero. For signed fields, the high-order bits should agree with
4180 the sign bit. */
4183 {
4185 {
4189 }
4190 }
4191 else
4192 {
4195 {
4199 }
4200 }
4205 /* Single-bit compares should always be against zero. */
4207 {
4210 }
4212 /* Make a new bitfield reference, shift the constant over the
4213 appropriate number of bits and mask it with the computed mask
4214 (in case this was a signed field). If we changed it, make a new one. */
4222 mask);
4227 }
4228 \f
4229 /* Subroutine for fold_truth_andor_1: decode a field reference.
4231 If EXP is a comparison reference, we return the innermost reference.
4233 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4234 set to the starting bit number.
4236 If the innermost field can be completely contained in a mode-sized
4237 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4239 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4240 otherwise it is not changed.
4242 *PUNSIGNEDP is set to the signedness of the field.
4244 *PREVERSEP is set to the storage order of the field.
4246 *PMASK is set to the mask used. This is either contained in a
4247 BIT_AND_EXPR or derived from the width of the field.
4249 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4251 Return 0 if this is not a component reference or is one that we can't
4252 do anything with. */
4254 static tree
4259 {
4264 tree unsigned_type;
4267 /* All the optimizations using this function assume integer fields.
4268 There are problems with FP fields since the type_for_size call
4269 below can fail for, e.g., XFmode. */
4273 /* We are interested in the bare arrangement of bits, so strip everything
4274 that doesn't affect the machine mode. However, record the type of the
4275 outermost expression if it may matter below. */
4282 {
4288 }
4299 /* Reject out-of-bound accesses (PR79731). */
4307 /* If the number of bits in the reference is the same as the bitsize of
4308 the outer type, then the outer type gives the signedness. Otherwise
4309 (in case of a small bitfield) the signedness is unchanged. */
4313 /* Compute the mask to access the bitfield. */
4322 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4330 }
4332 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4333 bit positions and MASK is SIGNED. */
4335 static int
4337 {
4341 /* If this function returns true when the type of the mask is
4342 UNSIGNED, then there will be errors. In particular see
4343 gcc.c-torture/execute/990326-1.c. There does not appear to be
4344 any documentation paper trail as to why this is so. But the pre
4345 wide-int worked with that restriction and it has been preserved
4346 here. */
4351 }
4353 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4354 represents the sign bit of EXP's type. If EXP represents a sign
4355 or zero extension, also test VAL against the unextended type.
4356 The return value is the (sub)expression whose sign bit is VAL,
4357 or NULL_TREE otherwise. */
4359 tree
4361 {
4363 tree t;
4365 /* Tree EXP must have an integral type. */
4370 /* Tree VAL must be an integer constant. */
4379 /* Handle extension from a narrower type. */
4385 }
4387 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4388 to be evaluated unconditionally. */
4390 static int
4392 {
4393 /* Strip any conversions that don't change the machine mode. */
4402 /* Don't regard global variables as simple. They may be
4403 allocated in ways unknown to the compiler (shared memory,
4404 #pragma weak, etc). */
4407 /* Weakrefs are not safe to be read, since they can be NULL.
4408 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4409 have DECL_WEAK flag set. */
4411 /* Loading a static variable is unduly expensive, but global
4412 registers aren't expensive. */
4414 }
4416 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4417 to be evaluated unconditionally.
4418 I addition to simple_operand_p, we assume that comparisons, conversions,
4419 and logic-not operations are simple, if their operands are simple, too. */
4421 static bool
4423 {
4443 }
4445 \f
4446 /* The following functions are subroutines to fold_range_test and allow it to
4447 try to change a logical combination of comparisons into a range test.
4449 For example, both
4450 X == 2 || X == 3 || X == 4 || X == 5
4451 and
4452 X >= 2 && X <= 5
4453 are converted to
4454 (unsigned) (X - 2) <= 3
4456 We describe each set of comparisons as being either inside or outside
4457 a range, using a variable named like IN_P, and then describe the
4458 range with a lower and upper bound. If one of the bounds is omitted,
4459 it represents either the highest or lowest value of the type.
4461 In the comments below, we represent a range by two numbers in brackets
4462 preceded by a "+" to designate being inside that range, or a "-" to
4463 designate being outside that range, so the condition can be inverted by
4464 flipping the prefix. An omitted bound is represented by a "-". For
4465 example, "- [-, 10]" means being outside the range starting at the lowest
4466 possible value and ending at 10, in other words, being greater than 10.
4467 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4468 always false.
4470 We set up things so that the missing bounds are handled in a consistent
4471 manner so neither a missing bound nor "true" and "false" need to be
4472 handled using a special case. */
4474 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4475 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4476 and UPPER1_P are nonzero if the respective argument is an upper bound
4477 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4478 must be specified for a comparison. ARG1 will be converted to ARG0's
4479 type if both are specified. */
4481 static tree
4484 {
4485 tree tem;
4489 /* If neither arg represents infinity, do the normal operation.
4490 Else, if not a comparison, return infinity. Else handle the special
4491 comparison rules. Note that most of the cases below won't occur, but
4492 are handled for consistency. */
4495 {
4500 }
4505 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4506 for neither. In real maths, we cannot assume open ended ranges are
4507 the same. But, this is computer arithmetic, where numbers are finite.
4508 We can therefore make the transformation of any unbounded range with
4509 the value Z, Z being greater than any representable number. This permits
4510 us to treat unbounded ranges as equal. */
4514 {
4535 }
4538 }
4539 \f
4540 /* Helper routine for make_range. Perform one step for it, return
4541 new expression if the loop should continue or NULL_TREE if it should
4542 stop. */
4544 tree
4548 {
4554 {
4556 /* We can only do something if the range is testing for zero. */
4565 /* We can only do something if the range is testing for zero
4566 and if the second operand is an integer constant. Note that
4567 saying something is "in" the range we make is done by
4568 complementing IN_P since it will set in the initial case of
4569 being not equal to zero; "out" is leaving it alone. */
4576 {
4597 }
4599 /* If this is an unsigned comparison, we also know that EXP is
4600 greater than or equal to zero. We base the range tests we make
4601 on that fact, so we record it here so we can parse existing
4602 range tests. We test arg0_type since often the return type
4603 of, e.g. EQ_EXPR, is boolean. */
4605 {
4609 NULL_TREE))
4614 /* If the high bound is missing, but we have a nonzero low
4615 bound, reverse the range so it goes from zero to the low bound
4616 minus 1. */
4618 {
4623 }
4624 }
4632 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4633 low and high are non-NULL, then normalize will DTRT. */
4636 {
4641 }
4643 /* (-x) IN [a,b] -> x in [-b, -a] */
4655 /* ~ X -> -X - 1 */
4664 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4665 move a constant to the other side. */
4670 /* If EXP is signed, any overflow in the computation is undefined,
4671 so we don't worry about it so long as our computations on
4672 the bounds don't overflow. For unsigned, overflow is defined
4673 and this is exactly the right thing. */
4685 normalize:
4686 /* Check for an unsigned range which has wrapped around the maximum
4687 value thus making n_high < n_low, and normalize it. */
4689 {
4695 /* If the range is of the form +/- [ x+1, x ], we won't
4696 be able to normalize it. But then, it represents the
4697 whole range or the empty set, so make it
4698 +/- [ -, - ]. */
4702 else
4704 }
4705 else
4713 CASE_CONVERT:
4731 /* If we're converting arg0 from an unsigned type, to exp,
4732 a signed type, we will be doing the comparison as unsigned.
4733 The tests above have already verified that LOW and HIGH
4734 are both positive.
4736 So we have to ensure that we will handle large unsigned
4737 values the same way that the current signed bounds treat
4738 negative values. */
4741 {
4742 tree high_positive;
4743 tree equiv_type;
4744 /* For fixed-point modes, we need to pass the saturating flag
4745 as the 2nd parameter. */
4747 equiv_type
4750 else
4751 equiv_type
4754 /* A range without an upper bound is, naturally, unbounded.
4755 Since convert would have cropped a very large value, use
4756 the max value for the destination type. */
4757 high_positive
4764 high_positive),
4767 /* If the low bound is specified, "and" the range with the
4768 range for which the original unsigned value will be
4769 positive. */
4771 {
4774 integer_zero_node),
4775 high_positive))
4779 }
4780 else
4781 {
4782 /* Otherwise, "or" the range with the range of the input
4783 that will be interpreted as negative. */
4786 integer_zero_node),
4787 high_positive))
4791 }
4792 }
4801 }
4802 }
4804 /* Given EXP, a logical expression, set the range it is testing into
4805 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4806 actually being tested. *PLOW and *PHIGH will be made of the same
4807 type as the returned expression. If EXP is not a comparison, we
4808 will most likely not be returning a useful value and range. Set
4809 *STRICT_OVERFLOW_P to true if the return value is only valid
4810 because signed overflow is undefined; otherwise, do not change
4811 *STRICT_OVERFLOW_P. */
4813 tree
4816 {
4824 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4825 and see if we can refine the range. Some of the cases below may not
4826 happen, but it doesn't seem worth worrying about this. We "continue"
4827 the outer loop when we've changed something; otherwise we "break"
4828 the switch, which will "break" the while. */
4834 {
4840 {
4848 }
4857 }
4859 /* If EXP is a constant, we can evaluate whether this is true or false. */
4861 {
4868 }
4872 }
4874 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4875 a bitwise check i.e. when
4876 LOW == 0xXX...X00...0
4877 HIGH == 0xXX...X11...1
4878 Return corresponding mask in MASK and stem in VALUE. */
4880 static bool
4883 {
4906 }
4907 \f
4908 /* Helper routine for build_range_check and match.pd. Return the type to
4909 perform the check or NULL if it shouldn't be optimized. */
4911 tree
4913 {
4914 /* First make sure that arithmetics in this type is valid, then make sure
4915 that it wraps around. */
4921 {
4924 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4925 for the type in question, as we rely on this here. */
4935 else
4937 }
4939 }
4941 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4942 type, TYPE, return an expression to test if EXP is in (or out of, depending
4943 on IN_P) the range. Return 0 if the test couldn't be created. */
4945 tree
4948 {
4951 /* Disable this optimization for function pointer expressions
4952 on targets that require function pointer canonicalization. */
4959 {
4965 }
4987 value);
4990 {
4992 {
4996 }
4998 }
5000 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5002 {
5006 {
5008 {
5011 etype
5013 else
5016 }
5019 }
5020 }
5022 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5023 This requires wrap-around arithmetics for the type of the expression. */
5043 }
5044 \f
5045 /* Return the predecessor of VAL in its type, handling the infinite case. */
5047 static tree
5049 {
5055 else
5058 }
5060 /* Return the successor of VAL in its type, handling the infinite case. */
5062 static tree
5064 {
5070 else
5073 }
5075 /* Given two ranges, see if we can merge them into one. Return 1 if we
5076 can, 0 if we can't. Set the output range into the specified parameters. */
5078 bool
5081 {
5085 tree tem;
5095 /* Make range 0 be the range that starts first, or ends last if they
5096 start at the same value. Swap them if it isn't. */
5099 || (lowequal
5102 {
5106 }
5108 /* If the second range is != high1 where high1 is the type maximum of
5109 the type, try first merging with < high1 range. */
5111 && high1
5118 {
5123 /* Similarly for the second range != low1 where low1 is the type minimum
5124 of the type, try first merging with > low1 range. */
5129 }
5131 /* Now flag two cases, whether the ranges are disjoint or whether the
5132 second range is totally subsumed in the first. Note that the tests
5133 below are simplified by the ones above. */
5139 /* We now have four cases, depending on whether we are including or
5140 excluding the two ranges. */
5142 {
5143 /* If they don't overlap, the result is false. If the second range
5144 is a subset it is the result. Otherwise, the range is from the start
5145 of the second to the end of the first. */
5150 else
5152 }
5155 {
5156 /* If they don't overlap, the result is the first range. If they are
5157 equal, the result is false. If the second range is a subset of the
5158 first, and the ranges begin at the same place, we go from just after
5159 the end of the second range to the end of the first. If the second
5160 range is not a subset of the first, or if it is a subset and both
5161 ranges end at the same place, the range starts at the start of the
5162 first range and ends just before the second range.
5163 Otherwise, we can't describe this as a single range. */
5169 {
5174 {
5175 /* We are in the weird situation where high0 > high1 but
5176 high1 has no successor. Punt. */
5178 }
5179 }
5181 {
5186 {
5187 /* low0 < low1 but low1 has no predecessor. Punt. */
5189 }
5190 }
5191 else
5193 }
5196 {
5197 /* If they don't overlap, the result is the second range. If the second
5198 is a subset of the first, the result is false. Otherwise,
5199 the range starts just after the first range and ends at the
5200 end of the second. */
5205 else
5206 {
5211 {
5212 /* high1 > high0 but high0 has no successor. Punt. */
5214 }
5215 }
5216 }
5218 else
5219 {
5220 /* The case where we are excluding both ranges. Here the complex case
5221 is if they don't overlap. In that case, the only time we have a
5222 range is if they are adjacent. If the second is a subset of the
5223 first, the result is the first. Otherwise, the range to exclude
5224 starts at the beginning of the first range and ends at the end of the
5225 second. */
5227 {
5232 else
5233 {
5234 /* Canonicalize - [min, x] into - [-, x]. */
5237 {
5240 GET_MODE_BITSIZE
5243 /* FALLTHROUGH */
5256 }
5258 /* Canonicalize - [x, max] into - [x, -]. */
5261 {
5264 GET_MODE_BITSIZE
5267 /* FALLTHROUGH */
5283 }
5285 /* The ranges might be also adjacent between the maximum and
5286 minimum values of the given type. For
5287 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5288 return + [x + 1, y - 1]. */
5290 {
5297 }
5298 else
5300 }
5301 }
5304 else
5306 }
5310 }
5311 \f
5313 /* Subroutine of fold, looking inside expressions of the form
5314 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5315 of the COND_EXPR. This function is being used also to optimize
5316 A op B ? C : A, by reversing the comparison first.
5318 Return a folded expression whose code is not a COND_EXPR
5319 anymore, or NULL_TREE if no folding opportunity is found. */
5321 static tree
5324 {
5329 tree tem;
5334 /* If we have A op 0 ? A : -A, consider applying the following
5335 transformations:
5337 A == 0? A : -A same as -A
5338 A != 0? A : -A same as A
5339 A >= 0? A : -A same as abs (A)
5340 A > 0? A : -A same as abs (A)
5341 A <= 0? A : -A same as -abs (A)
5342 A < 0? A : -A same as -abs (A)
5344 None of these transformations work for modes with signed
5345 zeros. If A is +/-0, the first two transformations will
5346 change the sign of the result (from +0 to -0, or vice
5347 versa). The last four will fix the sign of the result,
5348 even though the original expressions could be positive or
5349 negative, depending on the sign of A.
5351 Note that all these transformations are correct if A is
5352 NaN, since the two alternatives (A and -A) are also NaNs. */
5359 /* In the case that A is of the form X-Y, '-A' (arg2) may
5360 have already been folded to Y-X, check for that. */
5368 {
5380 /* Fall through. */
5391 /* FALLTHRU */
5401 }
5403 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5404 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5405 both transformations are correct when A is NaN: A != 0
5406 is then true, and A == 0 is false. */
5410 {
5415 }
5417 /* Try some transformations of A op B ? A : B.
5419 A == B? A : B same as B
5420 A != B? A : B same as A
5421 A >= B? A : B same as max (A, B)
5422 A > B? A : B same as max (B, A)
5423 A <= B? A : B same as min (A, B)
5424 A < B? A : B same as min (B, A)
5426 As above, these transformations don't work in the presence
5427 of signed zeros. For example, if A and B are zeros of
5428 opposite sign, the first two transformations will change
5429 the sign of the result. In the last four, the original
5430 expressions give different results for (A=+0, B=-0) and
5431 (A=-0, B=+0), but the transformed expressions do not.
5433 The first two transformations are correct if either A or B
5434 is a NaN. In the first transformation, the condition will
5435 be false, and B will indeed be chosen. In the case of the
5436 second transformation, the condition A != B will be true,
5437 and A will be chosen.
5439 The conversions to max() and min() are not correct if B is
5440 a number and A is not. The conditions in the original
5441 expressions will be false, so all four give B. The min()
5442 and max() versions would give a NaN instead. */
5445 /* Avoid these transformations if the COND_EXPR may be used
5446 as an lvalue in the C++ front-end. PR c++/19199. */
5447 && (in_gimple_form
5453 {
5459 {
5468 /* In C++ a ?: expression can be an lvalue, so put the
5469 operand which will be used if they are equal first
5470 so that we can convert this back to the
5471 corresponding COND_EXPR. */
5473 {
5481 }
5488 {
5496 }
5509 }
5510 }
5513 }
5516 \f
5517 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5518 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5519 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5520 false) >= 2)
5521 #endif
5523 /* EXP is some logical combination of boolean tests. See if we can
5524 merge it into some range test. Return the new tree if so. */
5526 static tree
5529 {
5545 /* If this is an OR operation, invert both sides; we will invert
5546 again at the end. */
5550 /* If both expressions are the same, if we can merge the ranges, and we
5551 can build the range test, return it or it inverted. If one of the
5552 ranges is always true or always false, consider it to be the same
5553 expression as the other. */
5561 {
5565 }
5567 /* On machines where the branch cost is expensive, if this is a
5568 short-circuited branch and the underlying object on both sides
5569 is the same, make a non-short-circuit operation. */
5571 && !flag_sanitize_coverage
5576 {
5577 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5578 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5579 which cases we can't do this. */
5587 {
5596 {
5599 WARN_STRICT_OVERFLOW_COMPARISON);
5603 }
5604 }
5605 }
5608 }
5609 \f
5610 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5611 bit value. Arrange things so the extra bits will be set to zero if and
5612 only if C is signed-extended to its full width. If MASK is nonzero,
5613 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5615 static tree
5617 {
5620 tree temp;
5625 /* We work by getting just the sign bit into the low-order bit, then
5626 into the high-order bit, then sign-extend. We then XOR that value
5627 with C. */
5631 /* We must use a signed type in order to get an arithmetic right shift.
5632 However, we must also avoid introducing accidental overflows, so that
5633 a subsequent call to integer_zerop will work. Hence we must
5634 do the type conversion here. At this point, the constant is either
5635 zero or one, and the conversion to a signed type can never overflow.
5636 We could get an overflow if this conversion is done anywhere else. */
5645 /* If necessary, convert the type back to match the type of C. */
5650 }
5651 \f
5652 /* For an expression that has the form
5653 (A && B) || ~B
5654 or
5655 (A || B) && ~B,
5656 we can drop one of the inner expressions and simplify to
5657 A || ~B
5658 or
5659 A && ~B
5660 LOC is the location of the resulting expression. OP is the inner
5661 logical operation; the left-hand side in the examples above, while CMPOP
5662 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5663 removing a condition that guards another, as in
5664 (A != NULL && A->...) || A == NULL
5665 which we must not transform. If RHS_ONLY is true, only eliminate the
5666 right-most operand of the inner logical operation. */
5668 static tree
5671 {
5689 {
5692 {
5695 }
5696 }
5698 {
5701 {
5704 }
5705 }
5720 }
5722 /* Find ways of folding logical expressions of LHS and RHS:
5723 Try to merge two comparisons to the same innermost item.
5724 Look for range tests like "ch >= '0' && ch <= '9'".
5725 Look for combinations of simple terms on machines with expensive branches
5726 and evaluate the RHS unconditionally.
5728 For example, if we have p->a == 2 && p->b == 4 and we can make an
5729 object large enough to span both A and B, we can do this with a comparison
5730 against the object ANDed with the a mask.
5732 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5733 operations to do this with one comparison.
5735 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5736 function and the one above.
5738 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5739 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5741 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5742 two operands.
5744 We return the simplified tree or 0 if no optimization is possible. */
5746 static tree
5749 {
5750 /* If this is the "or" of two comparisons, we can do something if
5751 the comparisons are NE_EXPR. If this is the "and", we can do something
5752 if the comparisons are EQ_EXPR. I.e.,
5753 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5755 WANTED_CODE is this operation code. For single bit fields, we can
5756 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5757 comparison for one-bit fields. */
5778 /* Start by getting the comparison codes. Fail if anything is volatile.
5779 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5780 it were surrounded with a NE_EXPR. */
5789 {
5793 }
5796 {
5800 }
5811 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5814 {
5817 {
5822 }
5825 {
5831 }
5832 }
5837 /* If the RHS can be evaluated unconditionally and its operands are
5838 simple, it wins to evaluate the RHS unconditionally on machines
5839 with expensive branches. In this case, this isn't a comparison
5840 that can be merged. */
5847 {
5848 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5859 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5869 }
5871 /* See if the comparisons can be merged. Then get all the parameters for
5872 each side. */
5897 /* It must be true that the inner operation on the lhs of each
5898 comparison must be the same if we are to be able to do anything.
5899 Then see if we have constants. If not, the same must be true for
5900 the rhs's. */
5909 {
5912 }
5917 else
5920 /* If either comparison code is not correct for our logical operation,
5921 fail. However, we can convert a one-bit comparison against zero into
5922 the opposite comparison against that bit being set in the field. */
5926 {
5928 {
5929 /* Make the left operand unsigned, since we are only interested
5930 in the value of one bit. Otherwise we are doing the wrong
5931 thing below. */
5934 }
5935 else
5937 }
5939 /* This is analogous to the code for l_const above. */
5941 {
5943 {
5946 }
5947 else
5949 }
5951 /* See if we can find a mode that contains both fields being compared on
5952 the left. If we can't, fail. Otherwise, update all constants and masks
5953 to be relative to a field of that size. */
5967 {
5970 }
5978 {
5985 {
5989 }
5990 }
5992 {
5999 {
6003 }
6004 }
6006 /* If the right sides are not constant, do the same for it. Also,
6007 disallow this optimization if a size or signedness mismatch occurs
6008 between the left and right sides. */
6010 {
6013 /* Make sure the two fields on the right
6014 correspond to the left without being swapped. */
6031 {
6034 }
6043 /* Make a mask that corresponds to both fields being compared.
6044 Do this for both items being compared. If the operands are the
6045 same size and the bits being compared are in the same position
6046 then we can do this by masking both and comparing the masked
6047 results. */
6054 {
6068 }
6070 /* There is still another way we can do something: If both pairs of
6071 fields being compared are adjacent, we may be able to make a wider
6072 field containing them both.
6074 Note that we still must mask the lhs/rhs expressions. Furthermore,
6075 the mask must be shifted to account for the shift done by
6076 make_bit_field_ref. */
6085 {
6086 tree type;
6102 /* Convert to the smaller type before masking out unwanted bits. */
6105 {
6107 {
6111 }
6113 {
6117 }
6118 }
6127 }
6130 }
6132 /* Handle the case of comparisons with constants. If there is something in
6133 common between the masks, those bits of the constants must be the same.
6134 If not, the condition is always false. Test for this to avoid generating
6135 incorrect code below. */
6140 {
6142 {
6145 }
6146 else
6147 {
6150 }
6151 }
6156 /* Construct the expression we will return. First get the component
6157 reference we will make. Unless the mask is all ones the width of
6158 that field, perform the mask operation. Then compare with the
6159 merged constant. */
6170 }
6171 \f
6172 /* T is an integer expression that is being multiplied, divided, or taken a
6173 modulus (CODE says which and what kind of divide or modulus) by a
6174 constant C. See if we can eliminate that operation by folding it with
6175 other operations already in T. WIDE_TYPE, if non-null, is a type that
6176 should be used for the computation if wider than our type.
6178 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6179 (X * 2) + (Y * 4). We must, however, be assured that either the original
6180 expression would not overflow or that overflow is undefined for the type
6181 in the language in question.
6183 If we return a non-null expression, it is an equivalent form of the
6184 original computation, but need not be in the original type.
6186 We set *STRICT_OVERFLOW_P to true if the return values depends on
6187 signed overflow being undefined. Otherwise we do not change
6188 *STRICT_OVERFLOW_P. */
6190 static tree
6193 {
6194 /* To avoid exponential search depth, refuse to allow recursion past
6195 three levels. Beyond that (1) it's highly unlikely that we'll find
6196 something interesting and (2) we've probably processed it before
6197 when we built the inner expression. */
6200 tree ret;
6205 depth++;
6207 depth--;
6210 }
6212 static tree
6215 {
6227 /* Don't deal with constants of zero here; they confuse the code below. */
6237 /* Note that we need not handle conditional operations here since fold
6238 already handles those cases. So just do arithmetic here. */
6240 {
6242 /* For a constant, we can always simplify if we are a multiply
6243 or (for divide and modulus) if it is a multiple of our constant. */
6247 {
6250 /* If the multiplication overflowed, we lost information on it.
6251 See PR68142 and PR69845. */
6255 }
6259 /* If op0 is an expression ... */
6265 /* ... and has wrapping overflow, and its type is smaller
6266 than ctype, then we cannot pass through as widening. */
6271 /* ... or this is a truncation (t is narrower than op0),
6272 then we cannot pass through this narrowing. */
6275 /* ... or signedness changes for division or modulus,
6276 then we cannot pass through this conversion. */
6280 /* ... or has undefined overflow while the converted to
6281 type has not, we cannot do the operation in the inner type
6282 as that would introduce undefined overflow. */
6288 /* Pass the constant down and see if we can make a simplification. If
6289 we can, replace this expression with the inner simplification for
6290 possible later conversion to our or some other type. */
6301 /* If widening the type changes it from signed to unsigned, then we
6302 must avoid building ABS_EXPR itself as unsigned. */
6304 {
6308 {
6311 }
6313 }
6314 /* If the constant is negative, we cannot simplify this. */
6317 /* FALLTHROUGH */
6319 /* For division and modulus, type can't be unsigned, as e.g.
6320 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6321 For signed types, even with wrapping overflow, this is fine. */
6330 /* If widening the type changes the signedness, then we can't perform
6331 this optimization as that changes the result. */
6335 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6341 {
6348 }
6352 /* If the second operand is constant, this is a multiplication
6353 or floor division, by a power of two, so we can treat it that
6354 way unless the multiplier or divisor overflows. Signed
6355 left-shift overflow is implementation-defined rather than
6356 undefined in C90, so do not convert signed left shift into
6357 multiplication. */
6360 /* const_binop may not detect overflow correctly,
6361 so check for it explicitly here. */
6370 ctype,
6372 t1),
6377 /* See if we can eliminate the operation on both sides. If we can, we
6378 can return a new PLUS or MINUS. If we can't, the only remaining
6379 cases where we can do anything are if the second operand is a
6380 constant. */
6387 /* If not multiplication, we can only do this if both operands
6388 are divisible by c. */
6391 {
6396 }
6398 /* If this was a subtraction, negate OP1 and set it to be an addition.
6399 This simplifies the logic below. */
6401 {
6403 /* If OP1 was not easily negatable, the constant may be OP0. */
6405 {
6408 }
6409 }
6414 /* If either OP1 or C are negative, this optimization is not safe for
6415 some of the division and remainder types while for others we need
6416 to change the code. */
6418 {
6426 }
6428 /* If it's a multiply or a division/modulus operation of a multiple
6429 of our constant, do the operation and verify it doesn't overflow. */
6433 {
6436 /* We allow the constant to overflow with wrapping semantics. */
6440 }
6441 else
6444 /* If we have an unsigned type, we cannot widen the operation since it
6445 will change the result if the original computation overflowed. */
6449 /* The last case is if we are a multiply. In that case, we can
6450 apply the distributive law to commute the multiply and addition
6451 if the multiplication of the constants doesn't overflow
6452 and overflow is defined. With undefined overflow
6453 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6459 op1);
6464 /* We have a special case here if we are doing something like
6465 (C * 8) % 4 since we know that's zero. */
6468 /* If the multiplication can overflow we cannot optimize this. */
6473 {
6476 }
6478 /* ... fall through ... */
6482 /* If we can extract our operation from the LHS, do so and return a
6483 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6484 do something only if the second operand is a constant. */
6500 /* If these are the same operation types, we can associate them
6501 assuming no overflow. */
6503 {
6518 }
6520 /* If these operations "cancel" each other, we have the main
6521 optimizations of this pass, which occur when either constant is a
6522 multiple of the other, in which case we replace this with either an
6523 operation or CODE or TCODE.
6525 If we have an unsigned type, we cannot do this since it will change
6526 the result if the original computation overflowed. */
6533 {
6536 {
6543 }
6546 {
6553 }
6554 }
6559 }
6562 }
6563 \f
6564 /* Return a node which has the indicated constant VALUE (either 0 or
6565 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6566 and is of the indicated TYPE. */
6568 tree
6570 {
6579 else
6581 }
6584 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6585 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6586 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6587 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6588 COND is the first argument to CODE; otherwise (as in the example
6589 given here), it is the second argument. TYPE is the type of the
6590 original expression. Return NULL_TREE if no simplification is
6591 possible. */
6593 static tree
6598 {
6606 /* Do not move possibly trapping operations into the conditional as this
6607 pessimizes code and causes gimplification issues when applied late. */
6615 {
6619 /* If this operand throws an expression, then it does not make
6620 sense to try to perform a logical or arithmetic operation
6621 involving it. */
6626 }
6629 {
6634 }
6635 else
6636 /* Detect the case of mixing vector and scalar types - bail out. */
6642 /* This transformation is only worthwhile if we don't have to wrap ARG
6643 in a SAVE_EXPR and the operation can be simplified without recursing
6644 on at least one of the branches once its pushed inside the COND_EXPR. */
6653 {
6657 else
6659 }
6661 {
6665 else
6667 }
6669 /* Check that we have simplified at least one of the branches. */
6674 }
6676 \f
6677 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6679 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6680 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6681 ADDEND is the same as X.
6683 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6684 and finite. The problematic cases are when X is zero, and its mode
6685 has signed zeros. In the case of rounding towards -infinity,
6686 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6687 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6689 bool
6691 {
6695 /* Don't allow the fold with -fsignaling-nans. */
6699 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6703 /* In a vector or complex, we would need to check the sign of all zeros. */
6707 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6711 /* The mode has signed zeros, and we have to honor their sign.
6712 In this situation, there is only one case we can return true for.
6713 X - 0 is the same as X unless rounding towards -infinity is
6714 supported. */
6716 }
6718 /* Subroutine of match.pd that optimizes comparisons of a division by
6719 a nonzero integer constant against an integer constant, i.e.
6720 X/C1 op C2.
6722 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6723 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6725 enum tree_code
6728 {
6733 /* We have to do this the hard way to detect unsigned overflow.
6734 prod = int_const_binop (MULT_EXPR, c1, c2); */
6740 {
6744 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6747 }
6749 {
6752 {
6771 }
6772 }
6773 else
6774 {
6775 /* A negative divisor reverses the relational operators. */
6780 {
6799 }
6800 }
6813 }
6816 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6817 equality/inequality test, then return a simplified form of the test
6818 using a sign testing. Otherwise return NULL. TYPE is the desired
6819 result type. */
6821 static tree
6824 tree result_type)
6825 {
6826 /* If this is testing a single bit, we can optimize the test. */
6830 {
6831 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6832 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6836 /* This is only a win if casting to a signed type is cheap,
6837 i.e. when arg00's type is not a partial mode. */
6839 {
6842 result_type,
6845 }
6846 }
6849 }
6851 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6852 equality/inequality test, then return a simplified form of
6853 the test using shifts and logical operations. Otherwise return
6854 NULL. TYPE is the desired result type. */
6856 tree
6859 {
6860 /* If this is testing a single bit, we can optimize the test. */
6864 {
6873 /* First, see if we can fold the single bit test into a sign-bit
6874 test. */
6876 result_type);
6880 /* Otherwise we have (A & C) != 0 where C is a single bit,
6881 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6882 Similarly for (A & C) == 0. */
6884 /* If INNER is a right shift of a constant and it plus BITNUM does
6885 not overflow, adjust BITNUM and INNER. */
6891 {
6894 }
6896 /* If we are going to be able to omit the AND below, we must do our
6897 operations as unsigned. If we must use the AND, we have a choice.
6898 Normally unsigned is faster, but for some machines signed is. */
6916 /* Put the AND last so it can combine with more things. */
6919 /* Make sure to return the proper type. */
6923 }
6925 }
6927 /* Test whether it is preferable two swap two operands, ARG0 and
6928 ARG1, for example because ARG0 is an integer constant and ARG1
6929 isn't. */
6931 bool
6933 {
6947 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6948 for commutative and comparison operators. Ensuring a canonical
6949 form allows the optimizers to find additional redundancies without
6950 having to explicitly check for both orderings. */
6956 /* Put SSA_NAMEs last. */
6962 /* Put variables last. */
6969 }
6972 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6973 means A >= Y && A != MAX, but in this case we know that
6974 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6976 static tree
6978 {
6985 else
6994 {
6997 }
6999 {
7002 }
7003 else
7010 {
7011 /* Convert the pointer types into integer before taking the difference. */
7015 }
7016 else
7023 }
7025 /* Fold a sum or difference of at least one multiplication.
7026 Returns the folded tree or NULL if no simplification could be made. */
7028 static tree
7031 {
7035 /* (A * C) +- (B * C) -> (A+-B) * C.
7036 (A * C) +- A -> A * (C+-1).
7037 We are most concerned about the case where C is a constant,
7038 but other combinations show up during loop reduction. Since
7039 it is not difficult, try all four possibilities. */
7042 {
7045 }
7047 {
7050 }
7051 else
7052 {
7053 /* We cannot generate constant 1 for fract. */
7058 }
7060 {
7063 }
7065 {
7067 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7068 the purpose of this canonicalization. */
7072 {
7075 }
7076 else
7078 }
7079 else
7080 {
7081 /* We cannot generate constant 1 for fract. */
7086 }
7089 /* Prefer factoring a common non-constant. */
7099 /* No identical multiplicands; see if we can find a common
7100 power-of-two factor in non-power-of-two multiplies. This
7101 can help in multi-dimensional array access. */
7104 {
7107 tree maybe_same;
7111 /* Move min of absolute values to int11. */
7113 {
7118 }
7119 else
7123 /* The remainder should not be a constant, otherwise we
7124 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7125 increased the number of multiplications necessary. */
7127 {
7135 }
7136 }
7143 /* We are neither factoring zero nor minus one. */
7151 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7152 same may be minus one and thus the multiplication may overflow. Perform
7153 the sum operation in an unsigned type. */
7158 /* If the sum evaluated to a constant that is not -INF the multiplication
7159 cannot overflow. */
7166 /* Do not resort to unsigned multiplication because
7167 we lose the no-overflow property of the expression. */
7169 }
7171 /* Subroutine of native_encode_expr. Encode the INTEGER_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 {
7190 /* Dry run. */
7196 {
7198 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7199 number of bytes. */
7203 {
7210 else
7212 }
7213 else
7217 }
7219 }
7222 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7223 specified by EXPR into the buffer PTR of length LEN bytes.
7224 Return the number of bytes placed in the buffer, or zero
7225 upon failure. */
7227 static int
7229 {
7233 FIXED_VALUE_TYPE value;
7248 }
7251 /* Subroutine of native_encode_expr. Encode the REAL_CST
7252 specified by EXPR into the buffer PTR of length LEN bytes.
7253 Return the number of bytes placed in the buffer, or zero
7254 upon failure. */
7256 static int
7258 {
7264 /* There are always 32 bits in each long, no matter the size of
7265 the hosts long. We handle floating point representations with
7266 up to 192 bits. */
7275 /* Dry run. */
7284 {
7289 {
7296 else
7298 }
7299 else
7300 {
7303 {
7304 /* Reverse bytes within each long, or within the entire float
7305 if it's smaller than a long (for HFmode). */
7308 }
7309 }
7314 }
7316 }
7318 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7319 specified by EXPR into the buffer PTR of length LEN bytes.
7320 Return the number of bytes placed in the buffer, or zero
7321 upon failure. */
7323 static int
7325 {
7327 tree part;
7341 }
7344 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7345 specified by EXPR into the buffer PTR of length LEN bytes.
7346 Return the number of bytes placed in the buffer, or zero
7347 upon failure. */
7349 static int
7351 {
7362 {
7364 {
7367 }
7378 }
7380 }
7383 /* Subroutine of native_encode_expr. Encode the STRING_CST
7384 specified by EXPR into the buffer PTR of length LEN bytes.
7385 Return the number of bytes placed in the buffer, or zero
7386 upon failure. */
7388 static int
7390 {
7393 /* Wide-char strings are encoded in target byte-order so native
7394 encoding them is trivial. */
7409 {
7412 {
7415 }
7418 }
7419 else
7422 }
7425 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7426 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7427 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7428 anything, just do a dry run. If OFF is not -1 then start
7429 the encoding at byte offset OFF and encode at most LEN bytes.
7430 Return the number of bytes placed in the buffer, or zero upon failure. */
7432 int
7434 {
7435 /* We don't support starting at negative offset and -1 is special. */
7440 {
7461 }
7462 }
7465 /* Subroutine of native_interpret_expr. Interpret the contents of
7466 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7467 If the buffer cannot be interpreted, return NULL_TREE. */
7469 static tree
7471 {
7481 }
7484 /* Subroutine of native_interpret_expr. Interpret the contents of
7485 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7486 If the buffer cannot be interpreted, return NULL_TREE. */
7488 static tree
7490 {
7493 double_int result;
7494 FIXED_VALUE_TYPE fixed_value;
7504 }
7507 /* Subroutine of native_interpret_expr. Interpret the contents of
7508 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7509 If the buffer cannot be interpreted, return NULL_TREE. */
7511 static tree
7513 {
7517 /* There are always 32 bits in each long, no matter the size of
7518 the hosts long. We handle floating point representations with
7519 up to 192 bits. */
7520 REAL_VALUE_TYPE r;
7530 {
7531 /* Both OFFSET and BYTE index within a long;
7532 bitpos indexes the whole float. */
7535 {
7542 else
7544 }
7545 else
7546 {
7549 {
7550 /* Reverse bytes within each long, or within the entire float
7551 if it's smaller than a long (for HFmode). */
7554 }
7555 }
7559 }
7563 }
7566 /* Subroutine of native_interpret_expr. Interpret the contents of
7567 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7568 If the buffer cannot be interpreted, return NULL_TREE. */
7570 static tree
7572 {
7587 }
7590 /* Subroutine of native_interpret_expr. Interpret the contents of
7591 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7592 If the buffer cannot be interpreted, return NULL_TREE. */
7594 static tree
7596 {
7609 {
7614 }
7616 }
7619 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7620 the buffer PTR of length LEN as a constant of type TYPE. For
7621 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7622 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7623 return NULL_TREE. */
7625 tree
7627 {
7629 {
7651 }
7652 }
7654 /* Returns true if we can interpret the contents of a native encoding
7655 as TYPE. */
7657 static bool
7659 {
7661 {
7674 }
7675 }
7678 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7679 TYPE at compile-time. If we're unable to perform the conversion
7680 return NULL_TREE. */
7682 static tree
7684 {
7685 /* We support up to 512-bit values (for V8DFmode). */
7689 /* Check that the host and target are sane. */
7698 }
7700 /* Build an expression for the address of T. Folds away INDIRECT_REF
7701 to avoid confusing the gimplify process. */
7703 tree
7705 {
7706 /* The size of the object is not relevant when talking about its address. */
7711 {
7716 }
7726 {
7731 }
7732 else
7736 }
7738 /* Build an expression for the address of T. */
7740 tree
7742 {
7746 }
7748 /* Fold a unary expression of code CODE and type TYPE with operand
7749 OP0. Return the folded expression if folding is successful.
7750 Otherwise, return NULL_TREE. */
7752 tree
7754 {
7755 tree tem;
7756 tree arg0;
7764 {
7767 {
7768 /* Don't use STRIP_NOPS, because signedness of argument type
7769 matters. */
7771 }
7772 else
7773 {
7774 /* Strip any conversions that don't change the mode. This
7775 is safe for every expression, except for a comparison
7776 expression because its signedness is derived from its
7777 operands.
7779 Note that this is done as an internal manipulation within
7780 the constant folder, in order to find the simplest
7781 representation of the arguments so that their form can be
7782 studied. In any cases, the appropriate type conversions
7783 should be put back in the tree that will get out of the
7784 constant folder. */
7786 }
7789 {
7792 {
7796 }
7797 }
7798 }
7805 {
7812 {
7826 /* If this was a conversion, and all we did was to move into
7827 inside the COND_EXPR, bring it back out. But leave it if
7828 it is a conversion from integer to integer and the
7829 result precision is no wider than a word since such a
7830 conversion is cheap and may be optimized away by combine,
7831 while it couldn't if it were outside the COND_EXPR. Then return
7832 so we don't get into an infinite recursion loop taking the
7833 conversion out and then back in. */
7845 && (INTEGRAL_TYPE_P
7858 }
7859 }
7862 {
7868 CASE_CONVERT:
7872 {
7873 /* If we have (type) (a CMP b) and type is an integral type, return
7874 new expression involving the new type. Canonicalize
7875 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7876 non-integral type.
7877 Do not fold the result as that would not simplify further, also
7878 folding again results in recursions. */
7888 }
7890 /* Handle (T *)&A.B.C for A being of type T and B and C
7891 living at offset zero. This occurs frequently in
7892 C++ upcasting and then accessing the base. */
7896 {
7898 tree offset;
7899 machine_mode mode;
7901 tree base
7905 /* If the reference was to a (constant) zero offset, we can use
7906 the address of the base if it has the same base type
7907 as the result type and the pointer type is unqualified. */
7915 }
7919 /* Detect assigning a bitfield. */
7921 && DECL_BIT_FIELD
7923 {
7924 /* Don't leave an assignment inside a conversion
7925 unless assigning a bitfield. */
7927 /* First do the assignment, then return converted constant. */
7932 }
7934 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7935 constants (if x has signed type, the sign bit cannot be set
7936 in c). This folds extension into the BIT_AND_EXPR.
7937 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7938 very likely don't have maximal range for their precision and this
7939 transformation effectively doesn't preserve non-maximal ranges. */
7943 {
7954 <= HOST_BITS_PER_WIDE_INT
7956 {
7960 cst &= HOST_WIDE_INT_M1U
7964 && !flag_syntax_only
7967 {
7971 }
7972 }
7974 {
7979 }
7980 }
7982 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7983 cast (T1)X will fold away. We assume that this happens when X itself
7984 is a cast. */
7988 {
7992 return fold_build_pointer_plus_loc
7994 }
7996 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7997 of the same precision, and X is an integer type not narrower than
7998 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8004 {
8010 }
8012 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8013 type of X and Y (integer types only). */
8018 {
8019 /* Be careful not to introduce new overflows. */
8020 tree mult_type;
8023 else
8027 {
8034 }
8035 }
8041 {
8048 }
8059 /* Convert fabs((double)float) into (double)fabsf(float). */
8062 {
8068 targ0));
8069 }
8073 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8092 /* Note that the operand of this must be an int
8093 and its values must be 0 or 1.
8094 ("true" is a fixed value perhaps depending on the language,
8095 but we don't handle values other than 1 correctly yet.) */
8102 /* Fold *&X to X if X is an lvalue. */
8104 {
8111 }
8117 }
8120 /* If the operation was a conversion do _not_ mark a resulting constant
8121 with TREE_OVERFLOW if the original constant was not. These conversions
8122 have implementation defined behavior and retaining the TREE_OVERFLOW
8123 flag here would confuse later passes such as VRP. */
8124 tree
8127 {
8136 }
8138 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8139 operands OP0 and OP1. LOC is the location of the resulting expression.
8140 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8141 Return the folded expression if folding is successful. Otherwise,
8142 return NULL_TREE. */
8143 static tree
8146 {
8147 tree tem;
8149 /* We only do these simplifications if we are optimizing. */
8153 /* Check for things like (A || B) && (A || C). We can convert this
8154 to A || (B && C). Note that either operator can be any of the four
8155 truth and/or operations and the transformation will still be
8156 valid. Also note that we only care about order for the
8157 ANDIF and ORIF operators. If B contains side effects, this
8158 might change the truth-value of A. */
8165 {
8185 /* This case if tricky because we must either have commutative
8186 operators or else A10 must not have side-effects. */
8192 a01);
8193 }
8195 /* See if we can build a range comparison. */
8201 {
8205 }
8209 {
8213 }
8215 /* Check for the possibility of merging component references. If our
8216 lhs is another similar operation, try to merge its rhs with our
8217 rhs. Then try to merge our lhs and rhs. */
8227 && !flag_sanitize_coverage
8232 {
8239 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8240 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8241 We don't want to pack more than two leafs to a non-IF AND/OR
8242 expression.
8243 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8244 equal to IF-CODE, then we don't want to add right-hand operand.
8245 If the inner right-hand side of left-hand operand has
8246 side-effects, or isn't simple, then we can't add to it,
8247 as otherwise we might destroy if-sequence. */
8250 /* Needed for sequence points to handle trappings, and
8251 side-effects. */
8253 {
8255 arg1);
8257 tem);
8258 }
8259 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8260 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8263 /* Needed for sequence points to handle trappings, and
8264 side-effects. */
8266 {
8271 }
8272 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8273 into (A OR B).
8274 For sequence point consistancy, we need to check for trapping,
8275 and side-effects. */
8279 }
8282 }
8284 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8285 by changing CODE to reduce the magnitude of constants involved in
8286 ARG0 of the comparison.
8287 Returns a canonicalized comparison tree if a simplification was
8288 possible, otherwise returns NULL_TREE.
8289 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8290 valid if signed overflow is undefined. */
8292 static tree
8296 {
8301 /* Match A +- CST code arg1. We can change this only if overflow
8302 is undefined. */
8305 /* In principle pointers also have undefined overflow behavior,
8306 but that causes problems elsewhere. */
8313 /* Identify the constant in arg0 and its sign. */
8317 /* Overflowed constants and zero will cause problems. */
8322 /* See if we can reduce the magnitude of the constant in
8323 arg0 by changing the comparison code. */
8324 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8328 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8332 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8336 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8340 else
8344 /* Now build the constant reduced in magnitude. But not if that
8345 would produce one outside of its types range. */
8361 }
8363 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8364 overflow further. Try to decrease the magnitude of constants involved
8365 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8366 and put sole constants at the second argument position.
8367 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8369 static tree
8372 {
8373 tree t;
8378 /* Try canonicalization by simplifying arg0. */
8383 {
8387 }
8389 /* Try canonicalization by simplifying arg1 using the swapped
8390 comparison. */
8398 }
8400 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8401 space. This is used to avoid issuing overflow warnings for
8402 expressions like &p->x which can not wrap. */
8404 static bool
8406 {
8413 poly_wide_int wi_offset;
8419 else
8424 precision);
8439 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8440 array. */
8449 }
8451 /* Return a positive integer when the symbol DECL is known to have
8452 a nonzero address, zero when it's known not to (e.g., it's a weak
8453 symbol), and a negative integer when the symbol is not yet in the
8454 symbol table and so whether or not its address is zero is unknown.
8455 For function local objects always return positive integer. */
8456 static int
8458 {
8463 /* Function local objects are never NULL. */
8471 }
8473 /* Subroutine of fold_binary. This routine performs all of the
8474 transformations that are common to the equality/inequality
8475 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8476 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8477 fold_binary should call fold_binary. Fold a comparison with
8478 tree code CODE and type TYPE with operands OP0 and OP1. Return
8479 the folded comparison or NULL_TREE. */
8481 static tree
8484 {
8494 /* For comparisons of pointers we can decompose it to a compile time
8495 comparison of the base objects and the offsets into the object.
8496 This requires at least one operand being an ADDR_EXPR or a
8497 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8503 {
8506 machine_mode mode;
8510 /* Get base and offset for the access. Strip ADDR_EXPR for
8511 get_inner_reference, but put it back by stripping INDIRECT_REF
8512 off the base object if possible. indirect_baseN will be true
8513 if baseN is not an address but refers to the object itself. */
8516 {
8517 base0
8523 else
8525 }
8527 {
8531 {
8532 base0
8538 else
8540 }
8543 else
8547 {
8554 }
8555 }
8559 {
8560 base1
8566 else
8568 }
8570 {
8574 {
8575 base1
8581 else
8583 }
8586 else
8590 {
8597 }
8598 }
8600 /* If we have equivalent bases we might be able to simplify. */
8604 {
8605 /* We can fold this expression to a constant if the non-constant
8606 offset parts are equal. */
8610 && (equality_code
8611 || (indirect_base0
8614 {
8620 "occur when comparing P +- C1 with "
8622 WARN_STRICT_OVERFLOW_CONDITIONAL);
8625 {
8663 }
8664 }
8665 /* We can simplify the comparison to a comparison of the variable
8666 offset parts if the constant offset parts are equal.
8667 Be careful to use signed sizetype here because otherwise we
8668 mess with array offsets in the wrong way. This is possible
8669 because pointer arithmetic is restricted to retain within an
8670 object and overflow on pointer differences is undefined as of
8671 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8673 && (equality_code
8674 || (indirect_base0
8677 {
8678 /* By converting to signed sizetype we cover middle-end pointer
8679 arithmetic which operates on unsigned pointer types of size
8680 type size and ARRAY_REF offsets which are properly sign or
8681 zero extended from their type in case it is narrower than
8682 sizetype. */
8685 else
8689 else
8696 "occur when comparing P +- C1 with "
8698 WARN_STRICT_OVERFLOW_COMPARISON);
8701 }
8702 }
8703 /* For equal offsets we can simplify to a comparison of the
8704 base addresses. */
8706 && (indirect_base0
8708 && (indirect_base1
8713 {
8719 }
8720 /* Comparison between an ordinary (non-weak) symbol and a null
8721 pointer can be eliminated since such symbols must have a non
8722 null address. In C, relational expressions between pointers
8723 to objects and null pointers are undefined. The results
8724 below follow the C++ rules with the additional property that
8725 every object pointer compares greater than a null pointer.
8726 */
8729 /* Avoid folding references to struct members at offset 0 to
8730 prevent tests like '&ptr->firstmember == 0' from getting
8731 eliminated. When ptr is null, although the -> expression
8732 is strictly speaking invalid, GCC retains it as a matter
8733 of QoI. See PR c/44555. */
8736 && indirect_base0
8737 /* The caller guarantees that when one of the arguments is
8738 constant (i.e., null in this case) it is second. */
8740 {
8742 {
8753 }
8754 }
8755 }
8757 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8758 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8759 the resulting offset is smaller in absolute value than the
8760 original one and has the same sign. */
8769 {
8774 tree cst;
8776 "occur when combining constants around "
8779 /* Put the constant on the side where it doesn't overflow and is
8780 of lower absolute value and of same sign than before. */
8787 {
8790 variable1,
8794 }
8802 {
8808 variable2);
8809 }
8810 }
8816 /* If we are comparing an expression that just has comparisons
8817 of two integer values, arithmetic expressions of those comparisons,
8818 and constants, we can simplify it. There are only three cases
8819 to check: the two values can either be equal, the first can be
8820 greater, or the second can be greater. Fold the expression for
8821 those three values. Since each value must be 0 or 1, we have
8822 eight possibilities, each of which corresponds to the constant 0
8823 or 1 or one of the six possible comparisons.
8825 This handles common cases like (a > b) == 0 but also handles
8826 expressions like ((x > y) - (y > x)) > 0, which supposedly
8827 occur in macroized code. */
8830 {
8834 /* Don't handle degenerate cases here; they should already
8835 have been handled anyway. */
8844 {
8848 /* We can't just pass T to eval_subst in case cval1 or cval2
8849 was the same as ARG1. */
8851 tree high_result
8855 arg1);
8856 tree equal_result
8860 arg1);
8861 tree low_result
8865 arg1);
8867 /* All three of these results should be 0 or 1. Confirm they are.
8868 Then use those values to select the proper code to use. */
8873 {
8874 /* Make a 3-bit mask with the high-order bit being the
8875 value for `>', the next for '=', and the low for '<'. */
8879 {
8881 /* Always false. */
8902 /* Always true. */
8904 }
8907 }
8908 }
8909 }
8912 }
8915 /* Subroutine of fold_binary. Optimize complex multiplications of the
8916 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8917 argument EXPR represents the expression "z" of type TYPE. */
8919 static tree
8921 {
8926 {
8929 }
8931 {
8934 }
8935 else
8936 {
8940 }
8949 }
8952 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8953 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8954 true if successful. */
8956 static bool
8958 {
8963 {
8966 }
8968 {
8974 else
8976 }
8977 else
8983 }
8985 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8986 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8987 NULL_TREE otherwise. */
8989 static tree
8991 {
9012 {
9013 HOST_WIDE_INT index;
9019 }
9022 {
9028 }
9029 else
9031 }
9033 /* Try to fold a pointer difference of type TYPE two address expressions of
9034 array references AREF0 and AREF1 using location LOC. Return a
9035 simplified expression for the difference or NULL_TREE. */
9037 static tree
9041 {
9046 /* If the bases are array references as well, recurse. If the bases
9047 are pointer indirections compute the difference of the pointers.
9048 If the bases are equal, we are set. */
9051 && (base_offset
9053 use_pointer_diff)))
9056 && (base_offset
9057 = use_pointer_diff
9067 {
9073 base_offset,
9076 }
9078 }
9080 /* If the real or vector real constant CST of type TYPE has an exact
9081 inverse, return it, else return NULL. */
9083 tree
9085 {
9086 REAL_VALUE_TYPE r;
9087 tree unit_type;
9088 machine_mode mode;
9091 {
9101 {
9105 tree_vector_builder elts;
9110 {
9115 }
9118 }
9122 }
9123 }
9125 /* Mask out the tz least significant bits of X of type TYPE where
9126 tz is the number of trailing zeroes in Y. */
9127 static wide_int
9129 {
9134 }
9136 /* Return true when T is an address and is known to be nonzero.
9137 For floating point we further ensure that T is not denormal.
9138 Similar logic is present in nonzero_address in rtlanal.h.
9140 If the return value is based on the assumption that signed overflow
9141 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9142 change *STRICT_OVERFLOW_P. */
9144 static bool
9146 {
9150 /* Doing something useful for floating point would need more work. */
9156 {
9159 strict_overflow_p);
9165 strict_overflow_p);
9173 }
9176 {
9179 strict_overflow_p);
9187 strict_overflow_p);
9202 strict_overflow_p);
9206 strict_overflow_p);
9209 {
9221 }
9225 }
9227 }
9229 /* Return true when T is an address and is known to be nonzero.
9230 Handle warnings about undefined signed overflow. */
9232 bool
9234 {
9241 "determining that expression is always "
9243 WARN_STRICT_OVERFLOW_MISC);
9245 }
9247 /* Return true if T is known not to be equal to an integer W. */
9249 bool
9251 {
9253 value_range_type rtype;
9255 {
9264 {
9269 }
9274 /* If T has some known zero bits and W has any of those bits set,
9275 then T is known not to be equal to W. */
9283 }
9284 }
9286 /* Fold a binary expression of code CODE and type TYPE with operands
9287 OP0 and OP1. LOC is the location of the resulting expression.
9288 Return the folded expression if folding is successful. Otherwise,
9289 return NULL_TREE. */
9291 tree
9294 {
9309 /* Strip any conversions that don't change the mode. This is
9310 safe for every expression, except for a comparison expression
9311 because its signedness is derived from its operands. So, in
9312 the latter case, only strip conversions that don't change the
9313 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9314 preserved.
9316 Note that this is done as an internal manipulation within the
9317 constant folder, in order to find the simplest representation
9318 of the arguments so that their form can be studied. In any
9319 cases, the appropriate type conversions should be put back in
9320 the tree that will get out of the constant folder. */
9323 {
9326 }
9327 else
9328 {
9331 }
9333 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9334 constant but we can't do arithmetic on them. */
9336 {
9339 {
9343 }
9344 }
9346 /* If this is a commutative operation, and ARG0 is a constant, move it
9347 to ARG1 to reduce the number of tests below. */
9352 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9353 to ARG1 to reduce the number of tests below. */
9362 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9364 First check for cases where an arithmetic operation is applied to a
9365 compound, conditional, or comparison operation. Push the arithmetic
9366 operation inside the compound or conditional to see if any folding
9367 can then be done. Convert comparison to conditional for this purpose.
9368 The also optimizes non-constant cases that used to be done in
9369 expand_expr.
9371 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9372 one of the operands is a comparison and the other is a comparison, a
9373 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9374 code below would make the expression more complex. Change it to a
9375 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9376 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9389 {
9393 boolean_type_node,
9401 }
9405 {
9407 {
9412 tem);
9413 }
9415 {
9420 tem);
9421 }
9426 {
9432 }
9437 {
9443 }
9444 }
9447 {
9449 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9452 {
9458 }
9460 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9463 {
9464 tree base;
9465 poly_int64 coffset;
9474 }
9479 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9485 arg1),
9487 arg0)));
9493 {
9494 /* X + (X / CST) * -CST is X % CST. */
9499 {
9508 cst0));
9509 }
9510 }
9512 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9513 one. Make sure the type is not saturating and has the signedness of
9514 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9515 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9522 {
9526 }
9529 {
9530 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9531 (plus (plus (mult) (mult)) (foo)) so that we can
9532 take advantage of the factoring cases below. */
9541 {
9547 else
9560 parg0),
9562 marg)),
9566 return
9572 parg1)));
9573 }
9574 }
9575 else
9576 {
9577 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9578 to __complex__ ( x, y ). This is not the same for SNaNs or
9579 if signed zeros are involved. */
9583 {
9590 {
9594 {
9600 }
9602 {
9608 }
9609 }
9610 }
9612 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9613 We associate floats only if the user has specified
9614 -fassociative-math. */
9618 {
9623 {
9624 tree tree0;
9627 }
9628 }
9629 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9630 We associate floats only if the user has specified
9631 -fassociative-math. */
9635 {
9640 {
9641 tree tree0;
9644 }
9645 }
9646 }
9648 bit_rotate:
9649 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9650 is a rotate of A by C1 bits. */
9651 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9652 is a rotate of A by B bits.
9653 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9654 though in this case CODE must be | and not + or ^, otherwise
9655 it doesn't return A when B is 0. */
9656 {
9658 tree rtype;
9667 /* Only create rotates in complete modes. Other cases are not
9668 expanded properly. */
9671 {
9684 {
9689 }
9694 {
9697 code0 == LSHIFT_EXPR
9700 }
9702 {
9712 {
9716 orig_tree01);
9718 }
9719 }
9723 {
9734 {
9738 orig_tree01);
9740 }
9741 }
9742 }
9743 }
9745 associate:
9746 /* In most languages, can't associate operations on floats through
9747 parentheses. Rather than remember where the parentheses were, we
9748 don't associate floats at all, unless the user has specified
9749 -fassociative-math.
9750 And, we need to make sure type is not saturating. */
9754 {
9760 /* Split both trees into variables, constants, and literals. Then
9761 associate each group together, the constants with literals,
9762 then the result with variables. This increases the chances of
9763 literals being recombined later and of generating relocatable
9764 expressions for the sum of a constant and literal. */
9772 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9776 /* With undefined overflow prefer doing association in a type
9777 which wraps on overflow, if that is one of the operand types. */
9780 {
9788 }
9790 /* With undefined overflow we can only associate constants with one
9791 variable, and constants whose association doesn't overflow. */
9794 {
9796 {
9797 /* ??? If split_tree would handle NEGATE_EXPR we could
9798 simply reject these cases and the allowed cases would
9799 be the var0/minus_var1 ones. */
9805 {
9808 }
9815 {
9818 }
9824 /* The only case we can still associate with two variables
9825 is if they cancel out. */
9829 }
9835 }
9837 /* Only do something if we found more than two objects. Otherwise,
9838 nothing has changed and we risk infinite recursion. */
9846 {
9858 {
9862 }
9864 {
9868 }
9870 /* Preserve the MINUS_EXPR if the negative part of the literal is
9871 greater than the positive part. Otherwise, the multiplicative
9872 folding code (i.e extract_muldiv) may be fooled in case
9873 unsigned constants are subtracted, like in the following
9874 example: ((X*2 + 4) - 8U)/2. */
9876 {
9880 /* But avoid ending up with only negated parts. */
9882 {
9886 }
9887 else
9888 {
9892 }
9893 }
9895 /* Don't introduce overflows through reassociation. */
9900 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9907 /* Eliminate minus_con0. */
9909 {
9916 else
9919 }
9921 /* Eliminate minus_var0. */
9923 {
9927 else
9930 }
9932 return
9935 }
9936 }
9942 /* Fold &a[i] - &a[j] to i-j. */
9947 {
9951 code
9955 }
9957 /* Further transformations are not for pointers. */
9961 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9964 /* If arg0 is e.g. unsigned int and type is int, then this could
9965 introduce UB, because if A is INT_MIN at runtime, the original
9966 expression can be well defined while the latter is not.
9967 See PR83269. */
9976 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9977 __complex__ ( x, -y ). This is not the same for SNaNs or if
9978 signed zeros are involved. */
9982 {
9989 {
9993 {
9995 arg1r ? arg1r
10000 }
10002 {
10006 arg1i ? arg1i
10009 }
10010 }
10011 }
10013 /* A - B -> A + (-B) if B is easily negatable. */
10017 /* Avoid this transformation if B is a positive REAL_CST. */
10025 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10026 one. Make sure the type is not saturating and has the signedness of
10027 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10028 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10035 {
10039 }
10045 {
10046 /* Transform x * -C into -x * C if x is easily negatable. */
10061 {
10064 "occur when simplifying "
10066 WARN_STRICT_OVERFLOW_MISC);
10068 }
10070 /* Optimize z * conj(z) for integer complex numbers. */
10077 }
10078 else
10079 {
10080 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10081 This is not the same for NaNs or if signed zeros are
10082 involved. */
10088 {
10091 return
10097 return
10102 }
10104 /* Optimize z * conj(z) for floating point complex numbers.
10105 Guarded by flag_unsafe_math_optimizations as non-finite
10106 imaginary components don't produce scalar results. */
10115 }
10119 /* Canonicalize (X & C1) | C2. */
10123 {
10128 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10136 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10138 {
10141 }
10143 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10144 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10145 mode which allows further optimizations. */
10150 {
10155 {
10158 }
10159 }
10162 {
10167 }
10168 }
10170 /* See if this can be simplified into a rotate first. If that
10171 is unsuccessful continue in the association code. */
10175 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10183 /* See if this can be simplified into a rotate first. If that
10184 is unsuccessful continue in the association code. */
10188 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10193 {
10194 tree tem2;
10201 }
10202 /* Fold ~X & 1 as (X & 1) == 0. */
10206 {
10207 tree tem2;
10214 }
10215 /* Fold !X & 1 as X == 0. */
10218 {
10222 }
10224 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10225 multiple of 1 << CST. */
10227 {
10234 }
10236 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10237 bits from CST2. */
10241 {
10243 wide_int masked
10250 {
10251 /* Avoid the transform if arg1 is a mask of some
10252 mode which allows further optimizations. */
10259 }
10260 }
10262 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10265 {
10270 return
10272 }
10277 /* Don't touch a floating-point divide by zero unless the mode
10278 of the constant can represent infinity. */
10284 /* (-A) / (-B) -> A / B */
10296 /* Fall through */
10299 /* Simplify A / (B << N) where A and B are positive and B is
10300 a power of 2, to A >> (N + log2(B)). */
10305 {
10308 {
10316 WARN_STRICT_OVERFLOW_MISC);
10322 }
10323 }
10325 /* Fall through */
10333 /* Convert -A / -B to A / B when the type is signed and overflow is
10334 undefined. */
10338 {
10341 "when distributing negation across "
10343 WARN_STRICT_OVERFLOW_MISC);
10348 }
10352 {
10355 "when distributing negation across "
10357 WARN_STRICT_OVERFLOW_MISC);
10362 }
10364 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10365 operation, EXACT_DIV_EXPR.
10367 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10368 At one time others generated faster code, it's not clear if they do
10369 after the last round to changes to the DIV code in expmed.c. */
10380 {
10384 WARN_STRICT_OVERFLOW_MISC);
10386 }
10398 {
10402 WARN_STRICT_OVERFLOW_MISC);
10404 }
10412 /* Since negative shift count is not well-defined,
10413 don't try to compute it in the compiler. */
10419 /* If we have a rotate of a bit operation with the rotate count and
10420 the second operand of the bit operation both constant,
10421 permute the two operations. */
10427 {
10435 }
10437 /* Two consecutive rotates adding up to the some integer
10438 multiple of the precision of the type can be ignored. */
10454 /* Note that the operands of this must be ints
10455 and their values must be 0 or 1.
10456 ("true" is a fixed value perhaps depending on the language.) */
10457 /* If first arg is constant zero, return it. */
10460 /* FALLTHRU */
10462 /* If either arg is constant true, drop it. */
10466 /* Preserve sequence points. */
10469 /* If second arg is constant zero, result is zero, but first arg
10470 must be evaluated. */
10473 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10474 case will be handled here. */
10478 /* !X && X is always false. */
10482 /* X && !X is always false. */
10487 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10488 means A >= Y && A != MAX, but in this case we know that
10489 A < X <= MAX. */
10493 {
10501 }
10510 /* Note that the operands of this must be ints
10511 and their values must be 0 or true.
10512 ("true" is a fixed value perhaps depending on the language.) */
10513 /* If first arg is constant true, return it. */
10516 /* FALLTHRU */
10518 /* If either arg is constant zero, drop it. */
10522 /* Preserve sequence points. */
10525 /* If second arg is constant true, result is true, but we must
10526 evaluate first arg. */
10529 /* Likewise for first arg, but note this only occurs here for
10530 TRUTH_OR_EXPR. */
10534 /* !X || X is always true. */
10538 /* X || !X is always true. */
10543 /* (X && !Y) || (!X && Y) is X ^ Y */
10546 {
10563 }
10572 /* If the second arg is constant zero, drop it. */
10575 /* If the second arg is constant true, this is a logical inversion. */
10577 {
10580 }
10581 /* Identical arguments cancel to zero. */
10585 /* !X ^ X is always true. */
10590 /* X ^ !X is always true. */
10606 /* bool_var != 1 becomes !bool_var. */
10613 /* bool_var == 0 becomes !bool_var. */
10620 /* !exp != 0 becomes !exp */
10625 /* If this is an EQ or NE comparison with zero and ARG0 is
10626 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10627 two operations, but the latter can be done in one less insn
10628 on machines that have only two-operand insns or on which a
10629 constant cannot be the first operand. */
10632 {
10637 {
10644 arg1);
10645 }
10648 {
10655 arg1);
10656 }
10657 }
10659 /* If this is an NE or EQ comparison of zero against the result of a
10660 signed MOD operation whose second operand is a power of 2, make
10661 the MOD operation unsigned since it is simpler and equivalent. */
10669 {
10679 }
10681 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10682 C1 is a valid shift constant, and C2 is a power of two, i.e.
10683 a single bit. */
10687 == INTEGER_CST
10690 {
10695 /* Check for a valid shift count. */
10697 {
10701 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10702 can be rewritten as (X & (C2 << C1)) != 0. */
10704 {
10709 }
10710 /* Otherwise, for signed (arithmetic) shifts,
10711 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10712 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10716 /* Otherwise, of unsigned (logical) shifts,
10717 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10718 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10719 else
10723 arg000);
10724 }
10725 }
10727 /* If this is a comparison of a field, we may be able to simplify it. */
10730 /* Handle the constant case even without -O
10731 to make sure the warnings are given. */
10733 {
10737 }
10739 /* Optimize comparisons of strlen vs zero to a compare of the
10740 first character of the string vs zero. To wit,
10741 strlen(ptr) == 0 => *ptr == 0
10742 strlen(ptr) != 0 => *ptr != 0
10743 Other cases should reduce to one of these two (or a constant)
10744 due to the return value of strlen being unsigned. */
10747 {
10755 {
10760 }
10761 }
10763 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10764 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10768 {
10773 {
10775 {
10778 }
10781 }
10782 }
10784 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10785 (X & C) == 0 when C is a single bit. */
10790 {
10797 arg1));
10798 }
10800 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10801 constant C is a power of two, i.e. a single bit. */
10808 {
10812 }
10814 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10815 when is C is a power of two, i.e. a single bit. */
10822 {
10828 }
10832 {
10835 }
10837 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10840 {
10848 {
10854 }
10856 {
10862 }
10864 {
10870 }
10872 {
10878 }
10879 }
10883 {
10890 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10891 operand_equal_p guarantees no side-effects so we don't need
10892 to use omit_one_operand on Z. */
10896 arg10));
10900 arg11));
10904 arg10));
10908 arg11));
10910 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10913 {
10919 }
10920 }
10922 /* Attempt to simplify equality/inequality comparisons of complex
10923 values. Only lower the comparison if the result is known or
10924 can be simplified to a single scalar comparison. */
10929 {
10934 {
10937 }
10938 else
10939 {
10942 }
10945 {
10948 }
10949 else
10950 {
10953 }
10957 {
10959 {
10964 }
10965 else
10966 {
10971 }
10972 }
10976 {
10978 {
10983 }
10984 else
10985 {
10990 }
10991 }
10992 }
11004 /* Transform comparisons of the form X +- C CMP X. */
11009 {
11014 /* (X - c) > X becomes false. */
11020 /* Likewise (X + c) < X becomes false. */
11026 /* Convert (X - c) <= X to true. */
11033 /* Convert (X + c) >= X to true. */
11039 }
11041 /* If we are comparing an ABS_EXPR with a constant, we can
11042 convert all the cases into explicit comparisons, but they may
11043 well not be faster than doing the ABS and one comparison.
11044 But ABS (X) <= C is a range comparison, which becomes a subtraction
11045 and a comparison, and is probably faster. */
11059 /* Convert ABS_EXPR<x> >= 0 to true. */
11066 {
11069 "when simplifying comparison of "
11071 WARN_STRICT_OVERFLOW_CONDITIONAL);
11074 arg0);
11075 }
11077 /* Convert ABS_EXPR<x> < 0 to false. */
11082 {
11085 "when simplifying comparison of "
11087 WARN_STRICT_OVERFLOW_CONDITIONAL);
11090 arg0);
11091 }
11093 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11094 and similarly for >= into !=. */
11104 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11105 otherwise Y might be >= # of bits in X's type and thus e.g.
11106 (unsigned char) (1 << Y) for Y 15 might be 0.
11107 If the cast is widening, then 1 << Y should have unsigned type,
11108 otherwise if Y is number of bits in the signed shift type minus 1,
11109 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11110 31 might be 0xffffffff80000000. */
11121 {
11127 }
11139 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11140 {
11152 }
11157 /* When pedantic, a compound expression can be neither an lvalue
11158 nor an integer constant expression. */
11161 /* Don't let (0, 0) be null pointer constant. */
11167 /* An ASSERT_EXPR should never be passed to fold_binary. */
11173 }
11175 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11176 ((A & N) + B) & M -> (A + B) & M
11177 Similarly if (N & M) == 0,
11178 ((A | N) + B) & M -> (A + B) & M
11179 and for - instead of + (or unary - instead of +)
11180 and/or ^ instead of |.
11181 If B is constant and (B & M) == 0, fold into A & M.
11183 This function is a helper for match.pd patterns. Return non-NULL
11184 type in which the simplified operation should be performed only
11185 if any optimization is possible.
11187 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11188 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11189 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11190 +/-. */
11191 tree
11196 {
11211 wide_int cst0;
11213 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11214 arg1 (M) is == (1LL << cst) - 1.
11215 Store C into PMOP[0] and D into PMOP[1]. */
11222 {
11229 {
11232 }
11235 /* If C or D is of the form (A & N) where
11236 (N & M) == M, or of the form (A | N) or
11237 (A ^ N) where (N & M) == 0, replace it with A. */
11243 /* If C or D is a N where (N & M) == 0, it can be
11244 omitted (replaced with 0). */
11249 /* Similarly, with C - N where (-N & M) == 0. */
11257 }
11259 /* Only build anything new if we optimized one or both arguments above. */
11265 else
11267 }
11269 /* Used by contains_label_[p1]. */
11271 struct contains_label_data
11272 {
11275 };
11277 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11278 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11279 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11281 static tree
11283 {
11286 {
11297 {
11305 }
11314 }
11315 }
11317 /* Return whether the sub-tree ST contains a label which is accessible from
11318 outside the sub-tree. */
11320 static bool
11322 {
11326 }
11328 /* Fold a ternary expression of code CODE and type TYPE with operands
11329 OP0, OP1, and OP2. Return the folded expression if folding is
11330 successful. Otherwise, return NULL_TREE. */
11332 tree
11335 {
11336 tree tem;
11343 /* If this is a commutative operation, and OP0 is a constant, move it
11344 to OP1 to reduce the number of tests below. */
11353 /* Strip any conversions that don't change the mode. This is safe
11354 for every expression, except for a comparison expression because
11355 its signedness is derived from its operands. So, in the latter
11356 case, only strip conversions that don't change the signedness.
11358 Note that this is done as an internal manipulation within the
11359 constant folder, in order to find the simplest representation of
11360 the arguments so that their form can be studied. In any cases,
11361 the appropriate type conversions should be put back in the tree
11362 that will get out of the constant folder. */
11364 {
11367 }
11370 {
11373 }
11376 {
11379 }
11382 {
11386 {
11392 }
11397 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11398 so all simple results must be passed through pedantic_non_lvalue. */
11400 {
11403 /* Only optimize constant conditions when the selected branch
11404 has the same type as the COND_EXPR. This avoids optimizing
11405 away "c ? x : throw", where the throw has a void type.
11406 Avoid throwing away that operand which contains label. */
11413 }
11415 {
11422 {
11425 {
11433 }
11438 }
11439 }
11441 /* If we have A op B ? A : C, we may be able to convert this to a
11442 simpler expression, depending on the operation and the values
11443 of B and C. Signed zeros prevent all of these transformations,
11444 for reasons given above each one.
11446 Also try swapping the arguments and inverting the conditional. */
11450 {
11454 }
11459 {
11463 {
11467 }
11468 }
11470 /* If the second operand is simpler than the third, swap them
11471 since that produces better jump optimization results. */
11474 {
11476 /* See if this can be inverted. If it can't, possibly because
11477 it was a floating-point inequality comparison, don't do
11478 anything. */
11482 }
11484 /* Convert A ? 1 : 0 to simply A. */
11489 /* If we try to convert OP0 to our type, the
11490 call to fold will try to move the conversion inside
11491 a COND, which will recurse. In that case, the COND_EXPR
11492 is probably the best choice, so leave it alone. */
11496 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11497 over COND_EXPR in cases such as floating point comparisons. */
11506 arg0)));
11508 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11513 {
11514 /* sign_bit_p looks through both zero and sign extensions,
11515 but for this optimization only sign extensions are
11516 usable. */
11519 {
11522 {
11525 }
11527 }
11528 /* sign_bit_p only checks ARG1 bits within A's precision.
11529 If <sign bit of A> has wider type than A, bits outside
11530 of A's precision in <sign bit of A> need to be checked.
11531 If they are all 0, this optimization needs to be done
11532 in unsigned A's type, if they are all 1 in signed A's type,
11533 otherwise this can't be done. */
11539 {
11541 tree tem_type;
11554 {
11557 }
11559 {
11562 }
11563 else
11565 }
11568 return
11574 arg1)));
11575 }
11577 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11578 already handled above. */
11583 {
11593 op1);
11594 }
11596 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11597 is probably obsolete because the first operand should be a
11598 truth value (that's why we have the two cases above), but let's
11599 leave it in until we can confirm this for all front-ends. */
11611 /* Disable the transformations below for vectors, since
11612 fold_binary_op_with_conditional_arg may undo them immediately,
11613 yielding an infinite loop. */
11617 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11626 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11631 {
11633 /* Only perform transformation if ARG0 is easily inverted. */
11637 ? BIT_IOR_EXPR
11640 op1);
11641 }
11643 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11648 {
11650 /* Only perform transformation if ARG0 is easily inverted. */
11656 op2);
11657 }
11659 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11671 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11672 of fold_ternary on them. */
11682 {
11693 {
11698 {
11700 {
11705 }
11711 }
11712 }
11713 }
11715 /* On constants we can use native encode/interpret to constant
11716 fold (nearly) all BIT_FIELD_REFs. */
11722 {
11725 /* Limit us to a reasonable amount of work. To relax the
11726 other limitations we need bit-shifting of the buffer
11727 and rounding up the size. */
11731 {
11733 unsigned HOST_WIDE_INT len
11738 {
11743 }
11744 }
11745 }
11751 {
11752 /* Build a vector of integers from the tree mask. */
11753 vec_perm_builder builder;
11757 /* Create a vec_perm_indices for the integer vector. */
11762 /* Check for cases that fold to OP0 or OP1 in their original
11763 element order. */
11770 {
11774 {
11777 }
11778 }
11784 {
11788 }
11792 /* Generate a canonical form of the selector. */
11794 {
11795 /* Some targets are deficient and fail to expand a single
11796 argument permutation while still allowing an equivalent
11797 2-argument version. */
11801 else
11802 {
11806 else
11807 /* Not directly supported with either encoding,
11808 so use the preferred form. */
11810 }
11812 }
11816 }
11820 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11823 {
11829 wide_int tem2
11833 }
11838 {
11840 unsigned HOST_WIDE_INT elsize
11843 {
11849 {
11855 }
11856 }
11857 }
11863 }
11865 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11866 of an array (or vector). */
11868 tree
11870 {
11875 {
11878 {
11879 /* Static constructors for variably sized objects makes no sense. */
11883 }
11884 }
11895 offset_int max_index;
11900 {
11901 /* Array constructor might explicitly set index, or specify a range,
11902 or leave index NULL meaning that it is next index after previous
11903 one. */
11905 {
11908 else
11909 {
11913 }
11914 }
11915 else
11916 {
11922 }
11924 /* Do we have match? */
11928 }
11930 }
11932 /* Perform constant folding and related simplification of EXPR.
11933 The related simplifications include x*1 => x, x*0 => 0, etc.,
11934 and application of the associative law.
11935 NOP_EXPR conversions may be removed freely (as long as we
11936 are careful not to change the type of the overall expression).
11937 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11938 but we can constant-fold them if they have constant operands. */
11940 #ifdef ENABLE_FOLD_CHECKING
11941 # define fold(x) fold_1 (x)
11943 static
11944 #endif
11945 tree
11947 {
11951 tree tem;
11954 /* Return right away if a constant. */
11958 /* CALL_EXPR-like objects with variable numbers of operands are
11959 treated specially. */
11961 {
11963 {
11966 }
11968 }
11971 {
11976 {
11994 }
11995 }
11998 {
12000 {
12007 {
12012 }
12015 }
12017 /* Return a VECTOR_CST if possible. */
12019 {
12025 tree val;
12031 }
12039 }
12041 #ifdef ENABLE_FOLD_CHECKING
12042 #undef fold
12049 /* When --enable-checking=fold, compute a digest of expr before
12050 and after actual fold call to see if fold did not accidentally
12051 change original expr. */
12053 tree
12055 {
12056 tree ret;
12076 }
12078 void
12080 {
12091 }
12093 static void
12095 {
12097 }
12099 static void
12102 {
12108 recursive_label:
12118 {
12119 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12124 }
12132 {
12133 /* Allow these fields to be modified. */
12134 tree tmp;
12143 {
12146 }
12147 }
12158 {
12161 {
12177 }
12181 {
12194 }
12211 {
12217 }
12220 {
12222 {
12225 }
12227 }
12238 {
12241 }
12251 }
12252 }
12254 /* Helper function for outputting the checksum of a tree T. When
12255 debugging with gdb, you can "define mynext" to be "next" followed
12256 by "call debug_fold_checksum (op0)", then just trace down till the
12257 outputs differ. */
12259 DEBUG_FUNCTION void
12261 {
12276 }
12278 #endif
12280 /* Fold a unary tree expression with code CODE of type TYPE with an
12281 operand OP0. LOC is the location of the resulting expression.
12282 Return a folded expression if successful. Otherwise, return a tree
12283 expression with code CODE of type TYPE with an operand OP0. */
12285 tree
12288 {
12289 tree tem;
12290 #ifdef ENABLE_FOLD_CHECKING
12299 #endif
12305 #ifdef ENABLE_FOLD_CHECKING
12312 #endif
12314 }
12316 /* Fold a binary tree expression with code CODE of type TYPE with
12317 operands OP0 and OP1. LOC is the location of the resulting
12318 expression. Return a folded expression if successful. Otherwise,
12319 return a tree expression with code CODE of type TYPE with operands
12320 OP0 and OP1. */
12322 tree
12325 MEM_STAT_DECL)
12326 {
12327 tree tem;
12328 #ifdef ENABLE_FOLD_CHECKING
12345 #endif
12351 #ifdef ENABLE_FOLD_CHECKING
12366 #endif
12368 }
12370 /* Fold a ternary tree expression with code CODE of type TYPE with
12371 operands OP0, OP1, and OP2. Return a folded expression if
12372 successful. Otherwise, return a tree expression with code CODE of
12373 type TYPE with operands OP0, OP1, and OP2. */
12375 tree
12378 {
12379 tree tem;
12380 #ifdef ENABLE_FOLD_CHECKING
12404 #endif
12411 #ifdef ENABLE_FOLD_CHECKING
12434 #endif
12436 }
12438 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12439 arguments in ARGARRAY, and a null static chain.
12440 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12441 of type TYPE from the given operands as constructed by build_call_array. */
12443 tree
12446 {
12447 tree tem;
12448 #ifdef ENABLE_FOLD_CHECKING
12467 #endif
12473 #ifdef ENABLE_FOLD_CHECKING
12489 #endif
12491 }
12493 /* Perform constant folding and related simplification of initializer
12494 expression EXPR. These behave identically to "fold_buildN" but ignore
12495 potential run-time traps and exceptions that fold must preserve. */
12497 #define START_FOLD_INIT \
12498 int saved_signaling_nans = flag_signaling_nans;\
12499 int saved_trapping_math = flag_trapping_math;\
12500 int saved_rounding_math = flag_rounding_math;\
12501 int saved_trapv = flag_trapv;\
12502 int saved_folding_initializer = folding_initializer;\
12503 flag_signaling_nans = 0;\
12504 flag_trapping_math = 0;\
12505 flag_rounding_math = 0;\
12506 flag_trapv = 0;\
12507 folding_initializer = 1;
12509 #define END_FOLD_INIT \
12510 flag_signaling_nans = saved_signaling_nans;\
12511 flag_trapping_math = saved_trapping_math;\
12512 flag_rounding_math = saved_rounding_math;\
12513 flag_trapv = saved_trapv;\
12514 folding_initializer = saved_folding_initializer;
12516 tree
12519 {
12520 tree result;
12521 START_FOLD_INIT;
12525 END_FOLD_INIT;
12527 }
12529 tree
12532 {
12533 tree result;
12534 START_FOLD_INIT;
12538 END_FOLD_INIT;
12540 }
12542 tree
12545 {
12546 tree result;
12547 START_FOLD_INIT;
12551 END_FOLD_INIT;
12553 }
12555 #undef START_FOLD_INIT
12556 #undef END_FOLD_INIT
12558 /* Determine if first argument is a multiple of second argument. Return 0 if
12559 it is not, or we cannot easily determined it to be.
12561 An example of the sort of thing we care about (at this point; this routine
12562 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12563 fold cases do now) is discovering that
12565 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12567 is a multiple of
12569 SAVE_EXPR (J * 8)
12571 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12573 This code also handles discovering that
12575 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12577 is a multiple of 8 so we don't have to worry about dealing with a
12578 possible remainder.
12580 Note that we *look* inside a SAVE_EXPR only to determine how it was
12581 calculated; it is not safe for fold to do much of anything else with the
12582 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12583 at run time. For example, the latter example above *cannot* be implemented
12584 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12585 evaluation time of the original SAVE_EXPR is not necessarily the same at
12586 the time the new expression is evaluated. The only optimization of this
12587 sort that would be valid is changing
12589 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12591 divided by 8 to
12593 SAVE_EXPR (I) * SAVE_EXPR (J)
12595 (where the same SAVE_EXPR (J) is used in the original and the
12596 transformed version). */
12598 int
12600 {
12611 {
12613 /* Bitwise and provides a power of two multiple. If the mask is
12614 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12622 {
12628 {
12631 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12633 {
12637 {
12640 }
12641 }
12643 }
12644 }
12649 /* It is impossible to prove if op0 - op1 is multiple of bottom
12650 precisely, so be conservative here checking if both op0 and op1
12651 are multiple of bottom. Note we check the second operand first
12652 since it's usually simpler. */
12657 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12658 as op0 - 3 if the expression has unsigned type. For example,
12659 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12669 {
12671 /* const_binop may not detect overflow correctly,
12672 so check for it explicitly here. */
12680 }
12684 /* Can't handle conversions from non-integral or wider integral type. */
12690 /* fall through */
12707 SIGNED);
12713 {
12716 /* Check for special cases to see if top is defined as multiple
12717 of bottom:
12719 top = (X & ~(bottom - 1) ; bottom is power of 2
12721 or
12723 Y = X % bottom
12724 top = X - Y. */
12743 }
12745 /* fall through */
12753 }
12754 }
12756 #define tree_expr_nonnegative_warnv_p(X, Y) \
12759 #define RECURSE(X) \
12760 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12762 /* Return true if CODE or TYPE is known to be non-negative. */
12764 static bool
12766 {
12769 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12770 have a signed:1 type (where the value is -1 and 0). */
12773 }
12775 /* Return true if (CODE OP0) is known to be non-negative. If the return
12776 value is based on the assumption that signed overflow is undefined,
12777 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12778 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12780 bool
12783 {
12788 {
12790 /* We can't return 1 if flag_wrapv is set because
12791 ABS_EXPR<INT_MIN> = INT_MIN. */
12795 {
12798 }
12806 CASE_CONVERT:
12807 {
12812 {
12816 {
12820 }
12821 }
12823 {
12829 }
12830 }
12835 }
12837 /* We don't know sign of `t', so be conservative and return false. */
12839 }
12841 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12842 value is based on the assumption that signed overflow is undefined,
12843 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12844 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12846 bool
12850 {
12855 {
12861 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12862 both unsigned and at least 2 bits shorter than the result. */
12866 {
12871 {
12875 }
12876 }
12881 {
12882 /* x * x is always non-negative for floating point x
12883 or without overflow. */
12886 {
12891 }
12892 }
12894 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12895 both unsigned and their total bits is shorter than the result. */
12899 {
12918 {
12928 }
12929 }
12956 }
12958 /* We don't know sign of `t', so be conservative and return false. */
12960 }
12962 /* Return true if T is known to be non-negative. If the return
12963 value is based on the assumption that signed overflow is undefined,
12964 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12965 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12967 bool
12969 {
12974 {
12988 /* Limit the depth of recursion to avoid quadratic behavior.
12989 This is expected to catch almost all occurrences in practice.
12990 If this code misses important cases that unbounded recursion
12991 would not, passes that need this information could be revised
12992 to provide it through dataflow propagation. */
13000 }
13001 }
13003 /* Return true if T is known to be non-negative. If the return
13004 value is based on the assumption that signed overflow is undefined,
13005 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13006 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13008 bool
13011 {
13013 {
13014 CASE_CFN_ACOS:
13015 CASE_CFN_ACOSH:
13016 CASE_CFN_CABS:
13017 CASE_CFN_COSH:
13018 CASE_CFN_ERFC:
13019 CASE_CFN_EXP:
13020 CASE_CFN_EXP10:
13021 CASE_CFN_EXP2:
13022 CASE_CFN_FABS:
13023 CASE_CFN_FDIM:
13024 CASE_CFN_HYPOT:
13025 CASE_CFN_POW10:
13026 CASE_CFN_FFS:
13027 CASE_CFN_PARITY:
13028 CASE_CFN_POPCOUNT:
13029 CASE_CFN_CLZ:
13030 CASE_CFN_CLRSB:
13033 /* Always true. */
13036 CASE_CFN_SQRT:
13037 CASE_CFN_SQRT_FN:
13038 /* sqrt(-0.0) is -0.0. */
13043 CASE_CFN_ASINH:
13044 CASE_CFN_ATAN:
13045 CASE_CFN_ATANH:
13046 CASE_CFN_CBRT:
13047 CASE_CFN_CEIL:
13048 CASE_CFN_CEIL_FN:
13049 CASE_CFN_ERF:
13050 CASE_CFN_EXPM1:
13051 CASE_CFN_FLOOR:
13052 CASE_CFN_FLOOR_FN:
13053 CASE_CFN_FMOD:
13054 CASE_CFN_FREXP:
13055 CASE_CFN_ICEIL:
13056 CASE_CFN_IFLOOR:
13057 CASE_CFN_IRINT:
13058 CASE_CFN_IROUND:
13059 CASE_CFN_LCEIL:
13060 CASE_CFN_LDEXP:
13061 CASE_CFN_LFLOOR:
13062 CASE_CFN_LLCEIL:
13063 CASE_CFN_LLFLOOR:
13064 CASE_CFN_LLRINT:
13065 CASE_CFN_LLROUND:
13066 CASE_CFN_LRINT:
13067 CASE_CFN_LROUND:
13068 CASE_CFN_MODF:
13069 CASE_CFN_NEARBYINT:
13070 CASE_CFN_NEARBYINT_FN:
13071 CASE_CFN_RINT:
13072 CASE_CFN_RINT_FN:
13073 CASE_CFN_ROUND:
13074 CASE_CFN_ROUND_FN:
13075 CASE_CFN_SCALB:
13076 CASE_CFN_SCALBLN:
13077 CASE_CFN_SCALBN:
13078 CASE_CFN_SIGNBIT:
13079 CASE_CFN_SIGNIFICAND:
13080 CASE_CFN_SINH:
13081 CASE_CFN_TANH:
13082 CASE_CFN_TRUNC:
13083 CASE_CFN_TRUNC_FN:
13084 /* True if the 1st argument is nonnegative. */
13087 CASE_CFN_FMAX:
13088 CASE_CFN_FMAX_FN:
13089 /* True if the 1st OR 2nd arguments are nonnegative. */
13092 CASE_CFN_FMIN:
13093 CASE_CFN_FMIN_FN:
13094 /* True if the 1st AND 2nd arguments are nonnegative. */
13097 CASE_CFN_COPYSIGN:
13098 CASE_CFN_COPYSIGN_FN:
13099 /* True if the 2nd argument is nonnegative. */
13102 CASE_CFN_POWI:
13103 /* True if the 1st argument is nonnegative or the second
13104 argument is an even integer. */
13110 CASE_CFN_POW:
13111 /* True if the 1st argument is nonnegative or the second
13112 argument is an even integer valued real. */
13114 {
13115 REAL_VALUE_TYPE c;
13116 HOST_WIDE_INT n;
13121 {
13122 REAL_VALUE_TYPE cint;
13126 }
13127 }
13132 }
13134 }
13136 /* Return true if T is known to be non-negative. If the return
13137 value is based on the assumption that signed overflow is undefined,
13138 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13139 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13141 static bool
13143 {
13149 {
13151 {
13155 /* If the initializer is non-void, then it's a normal expression
13156 that will be assigned to the slot. */
13160 /* Otherwise, the initializer sets the slot in some way. One common
13161 way is an assignment statement at the end of the initializer. */
13163 {
13171 else
13173 }
13179 }
13182 {
13188 arg0,
13189 arg1,
13191 }
13204 }
13205 }
13207 #undef RECURSE
13208 #undef tree_expr_nonnegative_warnv_p
13210 /* Return true if T is known to be non-negative. If the return
13211 value is based on the assumption that signed overflow is undefined,
13212 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13213 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13215 bool
13217 {
13224 {
13246 }
13249 {
13275 }
13276 }
13278 /* Return true if `t' is known to be non-negative. Handle warnings
13279 about undefined signed overflow. */
13281 bool
13283 {
13290 "determining that expression is always "
13292 WARN_STRICT_OVERFLOW_MISC);
13294 }
13297 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13298 For floating point we further ensure that T is not denormal.
13299 Similar logic is present in nonzero_address in rtlanal.h.
13301 If the return value is based on the assumption that signed overflow
13302 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13303 change *STRICT_OVERFLOW_P. */
13305 bool
13308 {
13310 {
13313 strict_overflow_p);
13316 {
13322 strict_overflow_p));
13323 }
13328 strict_overflow_p);
13332 }
13335 }
13337 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13338 For floating point we further ensure that T is not denormal.
13339 Similar logic is present in nonzero_address in rtlanal.h.
13341 If the return value is based on the assumption that signed overflow
13342 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13343 change *STRICT_OVERFLOW_P. */
13345 bool
13347 tree type,
13348 tree op0,
13350 {
13353 {
13357 {
13358 /* With the presence of negative values it is hard
13359 to say something. */
13366 /* One of operands must be positive and the other non-negative. */
13367 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13368 overflows, on a twos-complement machine the sum of two
13369 nonnegative numbers can never be zero. */
13371 strict_overflow_p)
13373 strict_overflow_p));
13374 }
13379 {
13381 strict_overflow_p)
13383 strict_overflow_p))
13384 {
13387 }
13388 }
13397 {
13400 }
13407 {
13411 /* When both operands are nonzero, then MAX must be too. */
13413 strict_overflow_p))
13416 /* MAX where operand 0 is positive is positive. */
13418 strict_overflow_p);
13419 }
13420 /* MAX where operand 1 is positive is positive. */
13425 {
13429 }
13434 strict_overflow_p)
13436 strict_overflow_p));
13440 }
13443 }
13445 /* Return true when T is an address and is known to be nonzero.
13446 For floating point we further ensure that T is not denormal.
13447 Similar logic is present in nonzero_address in rtlanal.h.
13449 If the return value is based on the assumption that signed overflow
13450 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13451 change *STRICT_OVERFLOW_P. */
13453 bool
13455 {
13458 {
13463 {
13475 /* For objects in symbol table check if we know they are non-zero.
13476 Don't do anything for variables and functions before symtab is built;
13477 it is quite possible that they will be declared weak later. */
13482 /* Constants are never weak. */
13487 }
13495 {
13499 }
13509 }
13511 }
13513 #define integer_valued_real_p(X) \
13516 #define RECURSE(X) \
13517 ((integer_valued_real_p) (X, depth + 1))
13519 /* Return true if the floating point result of (CODE OP0) has an
13520 integer value. We also allow +Inf, -Inf and NaN to be considered
13521 integer values. Return false for signaling NaN.
13523 DEPTH is the current nesting depth of the query. */
13525 bool
13527 {
13529 {
13536 CASE_CONVERT:
13537 {
13544 }
13548 }
13550 }
13552 /* Return true if the floating point result of (CODE OP0 OP1) has an
13553 integer value. We also allow +Inf, -Inf and NaN to be considered
13554 integer values. Return false for signaling NaN.
13556 DEPTH is the current nesting depth of the query. */
13558 bool
13560 {
13562 {
13572 }
13574 }
13576 /* Return true if the floating point result of calling FNDECL with arguments
13577 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13578 considered integer values. Return false for signaling NaN. If FNDECL
13579 takes fewer than 2 arguments, the remaining ARGn are null.
13581 DEPTH is the current nesting depth of the query. */
13583 bool
13585 {
13587 {
13588 CASE_CFN_CEIL:
13589 CASE_CFN_CEIL_FN:
13590 CASE_CFN_FLOOR:
13591 CASE_CFN_FLOOR_FN:
13592 CASE_CFN_NEARBYINT:
13593 CASE_CFN_NEARBYINT_FN:
13594 CASE_CFN_RINT:
13595 CASE_CFN_RINT_FN:
13596 CASE_CFN_ROUND:
13597 CASE_CFN_ROUND_FN:
13598 CASE_CFN_TRUNC:
13599 CASE_CFN_TRUNC_FN:
13602 CASE_CFN_FMIN:
13603 CASE_CFN_FMIN_FN:
13604 CASE_CFN_FMAX:
13605 CASE_CFN_FMAX_FN:
13610 }
13612 }
13614 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13615 has an integer value. We also allow +Inf, -Inf and NaN to be
13616 considered integer values. Return false for signaling NaN.
13618 DEPTH is the current nesting depth of the query. */
13620 bool
13622 {
13624 {
13632 /* Limit the depth of recursion to avoid quadratic behavior.
13633 This is expected to catch almost all occurrences in practice.
13634 If this code misses important cases that unbounded recursion
13635 would not, passes that need this information could be revised
13636 to provide it through dataflow propagation. */
13640 depth));
13644 }
13646 }
13648 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13649 has an integer value. We also allow +Inf, -Inf and NaN to be
13650 considered integer values. Return false for signaling NaN.
13652 DEPTH is the current nesting depth of the query. */
13654 static bool
13656 {
13658 {
13669 }
13671 }
13673 #undef RECURSE
13674 #undef integer_valued_real_p
13676 /* Return true if the floating point expression T has an integer value.
13677 We also allow +Inf, -Inf and NaN to be considered integer values.
13678 Return false for signaling NaN.
13680 DEPTH is the current nesting depth of the query. */
13682 bool
13684 {
13690 {
13706 }
13709 {
13715 {
13724 }
13728 }
13729 }
13731 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13732 attempt to fold the expression to a constant without modifying TYPE,
13733 OP0 or OP1.
13735 If the expression could be simplified to a constant, then return
13736 the constant. If the expression would not be simplified to a
13737 constant, then return NULL_TREE. */
13739 tree
13741 {
13744 }
13746 /* Given the components of a unary expression CODE, TYPE and OP0,
13747 attempt to fold the expression to a constant without modifying
13748 TYPE or OP0.
13750 If the expression could be simplified to a constant, then return
13751 the constant. If the expression would not be simplified to a
13752 constant, then return NULL_TREE. */
13754 tree
13756 {
13759 }
13761 /* If EXP represents referencing an element in a constant string
13762 (either via pointer arithmetic or array indexing), return the
13763 tree representing the value accessed, otherwise return NULL. */
13765 tree
13767 {
13771 {
13773 tree index;
13774 tree string;
13779 else
13780 {
13784 /* Optimize the special-case of a zero lower bound.
13786 We convert the low_bound to sizetype to avoid some problems
13787 with constant folding. (E.g. suppose the lower bound is 1,
13788 and its mode is QI. Without the conversion,l (ARRAY
13789 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13790 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13796 }
13798 scalar_int_mode char_mode;
13810 }
13812 }
13814 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13815 an integer constant, real, or fixed-point constant.
13817 TYPE is the type of the result. */
13819 static tree
13821 {
13825 {
13831 {
13832 FIXED_VALUE_TYPE f;
13837 /* Propagate overflow flags. */
13841 }
13845 {
13852 }
13855 }
13858 }
13860 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13861 an integer constant or real constant.
13863 TYPE is the type of the result. */
13865 tree
13867 {
13871 {
13873 {
13874 /* If the value is unsigned or non-negative, then the absolute value
13875 is the same as the ordinary value. */
13879 ;
13881 /* If the value is negative, then the absolute value is
13882 its negation. */
13883 else
13886 /* Force to the destination type, set TREE_OVERFLOW for signed
13887 TYPE only. */
13889 }
13895 else
13901 }
13904 }
13906 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13907 constant. TYPE is the type of the result. */
13909 static tree
13911 {
13915 }
13917 /* Given CODE, a relational operator, the target type, TYPE and two
13918 constant operands OP0 and OP1, return the result of the
13919 relational operation. If the result is not a compile time
13920 constant, then return NULL_TREE. */
13922 static tree
13924 {
13927 /* From here on, the only cases we handle are when the result is
13928 known to be a constant. */
13931 {
13935 /* Handle the cases where either operand is a NaN. */
13937 {
13939 {
13967 }
13970 }
13973 }
13976 {
13980 }
13982 /* Handle equality/inequality of complex constants. */
13984 {
13995 else
13997 }
14000 {
14002 {
14003 /* Have vector comparison with scalar boolean result. */
14011 {
14019 }
14021 }
14022 tree_vector_builder elts;
14027 {
14040 }
14043 }
14045 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14047 To compute GT, swap the arguments and do LT.
14048 To compute GE, do LT and invert the result.
14049 To compute LE, swap the arguments, do LT and invert the result.
14050 To compute NE, do EQ and invert the result.
14052 Therefore, the code below must handle only EQ and LT. */
14055 {
14058 }
14060 /* Note that it is safe to invert for real values here because we
14061 have already handled the one case that it matters. */
14065 {
14068 }
14070 /* Compute a result for LT or EQ if args permit;
14071 Otherwise return T. */
14073 {
14076 else
14078 }
14079 else
14085 }
14087 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14088 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14089 itself. */
14091 tree
14093 {
14094 /* If the expression does not have side effects then we don't have to wrap
14095 it with a cleanup point expression. */
14099 /* If the expression is a return, check to see if the expression inside the
14100 return has no side effects or the right hand side of the modify expression
14101 inside the return. If either don't have side effects set we don't need to
14102 wrap the expression in a cleanup point expression. Note we don't check the
14103 left hand side of the modify because it should always be a return decl. */
14105 {
14112 }
14115 }
14117 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14118 of an indirection through OP0, or NULL_TREE if no simplification is
14119 possible. */
14121 tree
14123 {
14125 tree subtype;
14126 poly_uint64 const_op01;
14135 {
14139 /* *&CONST_DECL -> to the value of the const decl. */
14142 /* *&p => p; make sure to handle *&"str"[cst] here. */
14144 {
14148 else
14150 }
14151 /* *(foo *)&fooarray => fooarray[0] */
14154 && (!in_gimple_form
14156 {
14166 }
14167 /* *(foo *)&complexfoo => __real__ complexfoo */
14171 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14174 {
14178 index);
14179 }
14180 }
14184 {
14190 {
14191 tree op00type;
14195 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14198 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14199 but we want to treat offsets with MSB set as negative.
14200 For the code below negative offsets are invalid and
14201 TYPE_SIZE of the element is something unsigned, so
14202 check whether op01 fits into poly_int64, which implies
14203 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14204 then just use poly_uint64 because we want to treat the
14205 value as unsigned. */
14207 {
14209 poly_uint64 max_offset
14213 {
14218 }
14219 }
14220 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14223 {
14225 const_op01))
14227 }
14228 /* ((foo *)&fooarray)[1] => fooarray[1] */
14231 {
14240 {
14245 }
14246 }
14247 }
14248 }
14250 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14253 && (!in_gimple_form
14255 {
14256 tree type_domain;
14266 NULL_TREE);
14267 }
14270 }
14272 /* Builds an expression for an indirection through T, simplifying some
14273 cases. */
14275 tree
14277 {
14285 }
14287 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14289 tree
14291 {
14296 else
14298 }
14300 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14301 whose result is ignored. The type of the returned tree need not be
14302 the same as the original expression. */
14304 tree
14306 {
14312 {
14323 else
14329 {
14345 }
14350 }
14351 }
14353 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14355 tree
14357 {
14363 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14364 have to do anything. Only do this when we are not given a const,
14365 because in that case, this check is more expensive than just
14366 doing it. */
14368 {
14373 }
14375 /* If divisor is a power of two, simplify this to bit manipulation. */
14377 {
14379 {
14393 }
14394 else
14395 {
14396 tree t;
14402 }
14403 }
14404 else
14405 {
14410 }
14413 }
14415 /* Likewise, but round down. */
14417 tree
14419 {
14426 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14427 have to do anything. Only do this when we are not given a const,
14428 because in that case, this check is more expensive than just
14429 doing it. */
14431 {
14436 }
14438 /* If divisor is a power of two, simplify this to bit manipulation. */
14440 {
14441 tree t;
14445 }
14446 else
14447 {
14452 }
14455 }
14457 /* Returns the pointer to the base of the object addressed by EXP and
14458 extracts the information about the offset of the access, storing it
14459 to PBITPOS and POFFSET. */
14461 static tree
14464 {
14465 tree core;
14466 machine_mode mode;
14468 poly_int64 bitsize;
14472 {
14477 }
14479 {
14485 {
14486 poly_offset_int tem
14492 }
14493 }
14494 else
14495 {
14499 }
14502 }
14504 /* Returns true if addresses of E1 and E2 differ by a constant, false
14505 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14507 bool
14509 {
14524 {
14534 }
14536 {
14537 /* If only one of the offsets is non-constant, the difference cannot
14538 be a constant. */
14540 }
14541 else
14546 }
14548 /* Return OFF converted to a pointer offset type suitable as offset for
14549 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14550 tree
14552 {
14554 }
14556 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14557 tree
14559 {
14562 }
14564 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14565 tree
14567 {
14570 }
14572 /* Return a pointer P to a NUL-terminated string representing the sequence
14573 of constant characters referred to by SRC (or a subsequence of such
14574 characters within it if SRC is a reference to a string plus some
14575 constant offset). If STRLEN is non-null, store stgrlen(P) in *STRLEN.
14576 If STRSIZE is non-null, store in *STRSIZE the size of the array
14577 the string is stored in; in that case, even though P points to a NUL
14578 terminated string, SRC need not refer to one. This can happen when
14579 SRC refers to a constant character array initialized to all non-NUL
14580 values, as in the C declaration: char a[4] = "1234"; */
14585 {
14586 tree offset_node;
14597 {
14600 else
14602 }
14604 /* STRING_LENGTH is the size of the string literal, including any
14605 embedded NULs. STRING_SIZE is the size of the array the string
14606 literal is stored in. */
14615 {
14616 /* Compute and store the length of the substring at OFFSET.
14617 All offsets past the initial length refer to null strings. */
14620 else
14622 }
14631 {
14632 /* Support even constant character arrays that aren't proper
14633 NUL-terminated strings. */
14635 }
14637 {
14638 /* Support only properly NUL-terminated strings but handle
14639 consecutive strings within the same array, such as the six
14640 substrings in "1\0002\0003". */
14642 }
14645 }
14647 /* Given a tree T, compute which bits in T may be nonzero. */
14649 wide_int
14651 {
14653 {
14671 CASE_CONVERT:
14677 {
14682 }
14686 {
14694 }
14698 {
14706 }
14710 }
14713 }
14715 #if CHECKING_P
14719 /* Helper functions for writing tests of folding trees. */
14721 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14723 static void
14725 tree constant)
14726 {
14728 }
14730 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14731 wrapping WRAPPED_EXPR. */
14733 static void
14735 tree wrapped_expr)
14736 {
14741 }
14743 /* Verify that various arithmetic binary operations are folded
14744 correctly. */
14746 static void
14748 {
14754 /* Addition. */
14755 /* 1 <-- (0 + 1) */
14757 one);
14759 one);
14761 /* (nonlvalue)x <-- (x + 0) */
14763 x);
14765 /* Subtraction. */
14766 /* 0 <-- (x - x) */
14768 zero);
14770 x);
14772 /* Multiplication. */
14773 /* 0 <-- (x * 0) */
14775 zero);
14777 /* (nonlvalue)x <-- (x * 1) */
14779 x);
14780 }
14782 /* Verify that various binary operations on vectors are folded
14783 correctly. */
14785 static void
14787 {
14793 /* Verify equality tests that return a scalar boolean result. */
14799 }
14801 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14803 static void
14805 {
14808 /* This will be 1 if VEC_MODE isn't a vector mode. */
14815 }
14817 /* Run all of the selftests within this file. */
14819 void
14821 {
14825 }