| blob | 97c435fa5e0dcf4345b10ea214ffc244cd6e2b7d |
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 a tree for the comparison which is the combination of
2791 doing the AND or OR (depending on CODE) of the two operations LCODE
2792 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2793 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2794 if this makes the transformation invalid. */
2796 tree
2801 {
2808 {
2819 }
2822 {
2823 /* Eliminate unordered comparisons, as well as LTGT and ORD
2824 which are not used unless the mode has NaNs. */
2830 }
2832 {
2833 /* Check that the original operation and the optimized ones will trap
2834 under the same condition. */
2845 /* In a short-circuited boolean expression the LHS might be
2846 such that the RHS, if evaluated, will never trap. For
2847 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2848 if neither x nor y is NaN. (This is a mixed blessing: for
2849 example, the expression above will never trap, hence
2850 optimizing it to x < y would be invalid). */
2855 /* If the comparison was short-circuited, and only the RHS
2856 trapped, we may now generate a spurious trap. */
2861 /* If we changed the conditions that cause a trap, we lose. */
2864 }
2870 else
2871 {
2876 }
2877 }
2878 \f
2879 /* Return nonzero if two operands (typically of the same tree node)
2880 are necessarily equal. FLAGS modifies behavior as follows:
2882 If OEP_ONLY_CONST is set, only return nonzero for constants.
2883 This function tests whether the operands are indistinguishable;
2884 it does not test whether they are equal using C's == operation.
2885 The distinction is important for IEEE floating point, because
2886 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2887 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2889 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2890 even though it may hold multiple values during a function.
2891 This is because a GCC tree node guarantees that nothing else is
2892 executed between the evaluation of its "operands" (which may often
2893 be evaluated in arbitrary order). Hence if the operands themselves
2894 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2895 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2896 unset means assuming isochronic (or instantaneous) tree equivalence.
2897 Unless comparing arbitrary expression trees, such as from different
2898 statements, this flag can usually be left unset.
2900 If OEP_PURE_SAME is set, then pure functions with identical arguments
2901 are considered the same. It is used when the caller has other ways
2902 to ensure that global memory is unchanged in between.
2904 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2905 not values of expressions.
2907 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2908 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2910 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2911 any operand with side effect. This is unnecesarily conservative in the
2912 case we know that arg0 and arg1 are in disjoint code paths (such as in
2913 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2914 addresses with TREE_CONSTANT flag set so we know that &var == &var
2915 even if var is volatile. */
2917 int
2919 {
2920 /* When checking, verify at the outermost operand_equal_p call that
2921 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2922 hash value. */
2924 {
2926 {
2928 {
2935 }
2937 }
2938 else
2940 }
2942 /* If either is ERROR_MARK, they aren't equal. */
2948 /* Similar, if either does not have a type (like a released SSA name),
2949 they aren't equal. */
2953 /* We cannot consider pointers to different address space equal. */
2960 /* Check equality of integer constants before bailing out due to
2961 precision differences. */
2963 {
2964 /* Address of INTEGER_CST is not defined; check that we did not forget
2965 to drop the OEP_ADDRESS_OF flags. */
2968 }
2971 {
2972 /* If both types don't have the same signedness, then we can't consider
2973 them equal. We must check this before the STRIP_NOPS calls
2974 because they may change the signedness of the arguments. As pointers
2975 strictly don't have a signedness, require either two pointers or
2976 two non-pointers as well. */
2982 /* If both types don't have the same precision, then it is not safe
2983 to strip NOPs. */
2990 }
2991 #if 0
2992 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2993 sanity check once the issue is solved. */
2994 else
2995 /* Addresses of conversions and SSA_NAMEs (and many other things)
2996 are not defined. Check that we did not forget to drop the
2997 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3000 #endif
3002 /* In case both args are comparisons but with different comparison
3003 code, try to swap the comparison operands of one arg to produce
3004 a match and compare that variant. */
3008 {
3016 }
3019 {
3020 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3022 ;
3024 {
3025 /* If we are interested in comparing addresses ignore
3026 MEM_REF wrappings of the base that can appear just for
3027 TBAA reasons. */
3041 }
3042 else
3044 }
3046 /* When not checking adddresses, this is needed for conversions and for
3047 COMPONENT_REF. Might as well play it safe and always test this. */
3054 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3055 We don't care about side effects in that case because the SAVE_EXPR
3056 takes care of that for us. In all other cases, two expressions are
3057 equal if they have no side effects. If we have two identical
3058 expressions with side effects that should be treated the same due
3059 to the only side effects being identical SAVE_EXPR's, that will
3060 be detected in the recursive calls below.
3061 If we are taking an invariant address of two identical objects
3062 they are necessarily equal as well. */
3069 /* Next handle constant cases, those for which we can return 1 even
3070 if ONLY_CONST is set. */
3073 {
3087 {
3088 /* If we do not distinguish between signed and unsigned zero,
3089 consider them equal. */
3092 }
3096 {
3111 }
3115 flags)
3117 flags));
3128 flags | OEP_ADDRESS_OF
3131 /* In GIMPLE empty constructors are allowed in initializers of
3132 aggregates. */
3136 }
3141 /* Define macros to test an operand from arg0 and arg1 for equality and a
3142 variant that allows null and views null as being different from any
3143 non-null value. In the latter case, if either is null, the both
3144 must be; otherwise, do the normal comparison. */
3145 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3146 TREE_OPERAND (arg1, N), flags)
3148 #define OP_SAME_WITH_NULL(N) \
3149 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3150 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3153 {
3155 /* Two conversions are equal only if signedness and modes match. */
3157 {
3158 CASE_CONVERT:
3166 }
3176 /* For commutative ops, allow the other order. */
3184 /* If either of the pointer (or reference) expressions we are
3185 dereferencing contain a side effect, these cannot be equal,
3186 but their addresses can be. */
3193 {
3203 /* Require the same offset. */
3209 /* Fallthru. */
3217 {
3218 /* Require equal access sizes */
3224 flags)))
3226 /* Verify that access happens in similar types. */
3229 /* Verify that accesses are TBAA compatible. */
3238 /* Verify that alignment is compatible. */
3242 }
3245 /* TARGET_MEM_REF require equal extra operands. */
3256 /* Compare the array index by value if it is constant first as we
3257 may have different types but same value here. */
3263 /* Compare low bound and element size as with OEP_ADDRESS_OF
3264 we have to account for the offset of the ref. */
3269 array_ref_low_bound
3273 array_ref_element_size
3275 flags))));
3278 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3279 may be NULL when we're called to compare MEM_EXPRs. */
3294 }
3298 {
3300 /* Be sure we pass right ADDRESS_OF flag. */
3317 /* The multiplcation operands are commutative. */
3318 /* FALLTHRU */
3326 /* Otherwise take into account this is a commutative operation. */
3339 /* BIT_INSERT_EXPR has an implict operand as the type precision
3340 of op1. Need to check to make sure they are the same. */
3346 /* FALLTHRU */
3372 }
3376 {
3380 /* If not both CALL_EXPRs are either internal or normal function
3381 functions, then they are not equal. */
3384 {
3385 /* If the CALL_EXPRs call different internal functions, then they
3386 are not equal. */
3389 }
3390 else
3391 {
3392 /* If the CALL_EXPRs call different functions, then they are not
3393 equal. */
3395 flags))
3397 }
3399 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3400 {
3404 else
3408 }
3410 /* Now see if all the arguments are the same. */
3411 {
3422 /* If we get here and both argument lists are exhausted
3423 then the CALL_EXPRs are equal. */
3425 }
3428 }
3431 /* Consider __builtin_sqrt equal to sqrt. */
3439 {
3440 /* In GIMPLE constructors are used only to build vectors from
3441 elements. Individual elements in the constructor must be
3442 indexed in increasing order and form an initial sequence.
3444 We make no effort to compare constructors in generic.
3445 (see sem_variable::equals in ipa-icf which can do so for
3446 constants). */
3451 /* Be sure that vectors constructed have the same representation.
3452 We only tested element precision and modes to match.
3453 Vectors may be BLKmode and thus also check that the number of
3454 parts match. */
3467 {
3472 /* In GIMPLE the indexes can be either NULL or matching i.
3473 Double check this so we won't get false
3474 positives for GENERIC. */
3482 }
3484 }
3487 {
3488 /* Compare the STATEMENT_LISTs. */
3494 {
3495 /* The lists don't have the same number of statements. */
3501 flags & (OEP_LEXICOGRAPHIC
3504 }
3505 }
3510 {
3521 }
3525 }
3527 #undef OP_SAME
3528 #undef OP_SAME_WITH_NULL
3529 }
3530 \f
3531 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3532 with a different signedness or a narrower precision. */
3534 static bool
3536 {
3544 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3545 and see if the inner values are the same. This removes any
3546 signedness comparison, which doesn't matter here. */
3554 /* Discard a single widening conversion from ARG1 and see if the inner
3555 value is the same as ARG0. */
3564 }
3565 \f
3566 /* See if ARG is an expression that is either a comparison or is performing
3567 arithmetic on comparisons. The comparisons must only be comparing
3568 two different values, which will be stored in *CVAL1 and *CVAL2; if
3569 they are nonzero it means that some operands have already been found.
3570 No variables may be used anywhere else in the expression except in the
3571 comparisons.
3573 If this is true, return 1. Otherwise, return zero. */
3575 static int
3577 {
3581 /* We can handle some of the tcc_expression cases here. */
3590 {
3609 /* First see if we can handle the first operand, then the second. For
3610 the second operand, we know *CVAL1 can't be zero. It must be that
3611 one side of the comparison is each of the values; test for the
3612 case where this isn't true by failing if the two operands
3613 are the same. */
3622 ;
3626 ;
3627 else
3631 ;
3635 ;
3636 else
3643 }
3644 }
3645 \f
3646 /* ARG is a tree that is known to contain just arithmetic operations and
3647 comparisons. Evaluate the operations in the tree substituting NEW0 for
3648 any occurrence of OLD0 as an operand of a comparison and likewise for
3649 NEW1 and OLD1. */
3651 static tree
3654 {
3659 /* We can handle some of the tcc_expression cases here. */
3667 {
3682 {
3701 }
3702 /* Fall through - ??? */
3705 {
3709 /* We need to check both for exact equality and tree equality. The
3710 former will be true if the operand has a side-effect. In that
3711 case, we know the operand occurred exactly once. */
3724 }
3728 }
3729 }
3730 \f
3731 /* Return a tree for the case when the result of an expression is RESULT
3732 converted to TYPE and OMITTED was previously an operand of the expression
3733 but is now not needed (e.g., we folded OMITTED * 0).
3735 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3736 the conversion of RESULT to TYPE. */
3738 tree
3740 {
3743 /* If the resulting operand is an empty statement, just return the omitted
3744 statement casted to void. */
3754 }
3756 /* Return a tree for the case when the result of an expression is RESULT
3757 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3758 of the expression but are now not needed.
3760 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3761 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3762 evaluated before OMITTED2. Otherwise, if neither has side effects,
3763 just do the conversion of RESULT to TYPE. */
3765 tree
3768 {
3777 }
3779 \f
3780 /* Return a simplified tree node for the truth-negation of ARG. This
3781 never alters ARG itself. We assume that ARG is an operation that
3782 returns a truth value (0 or 1).
3784 FIXME: one would think we would fold the result, but it causes
3785 problems with the dominator optimizer. */
3787 static tree
3789 {
3794 /* If this is a comparison, we can simply invert it, except for
3795 floating-point non-equality comparisons, in which case we just
3796 enclose a TRUTH_NOT_EXPR around what we have. */
3799 {
3802 && flag_trapping_math
3816 }
3819 {
3838 /* Here we can invert either operand. We invert the first operand
3839 unless the second operand is a TRUTH_NOT_EXPR in which case our
3840 result is the XOR of the first operand with the inside of the
3841 negation of the second operand. */
3846 else
3869 {
3876 /* A COND_EXPR may have a throw as one operand, which
3877 then has void type. Just leave void operands
3878 as they are. */
3884 }
3896 CASE_CONVERT:
3900 /* fall through */
3922 }
3923 }
3925 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3926 assume that ARG is an operation that returns a truth value (0 or 1
3927 for scalars, 0 or -1 for vectors). Return the folded expression if
3928 folding is successful. Otherwise, return NULL_TREE. */
3930 static tree
3932 {
3935 ? BIT_NOT_EXPR
3938 }
3940 /* Return a simplified tree node for the truth-negation of ARG. This
3941 never alters ARG itself. We assume that ARG is an operation that
3942 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3944 tree
3946 {
3952 ? BIT_NOT_EXPR
3955 }
3956 \f
3957 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3958 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3959 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3960 is the original memory reference used to preserve the alias set of
3961 the access. */
3963 static tree
3967 {
3970 /* Attempt not to lose the access path if possible. */
3972 {
3974 machine_mode nmode;
3976 tree noffset;
3984 && !reversep
3985 && !nreversep
3987 {
3990 }
3991 }
4000 {
4007 }
4022 }
4024 /* Optimize a bit-field compare.
4026 There are two cases: First is a compare against a constant and the
4027 second is a comparison of two items where the fields are at the same
4028 bit position relative to the start of a chunk (byte, halfword, word)
4029 large enough to contain it. In these cases we can avoid the shift
4030 implicit in bitfield extractions.
4032 For constants, we emit a compare of the shifted constant with the
4033 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4034 compared. For two fields at the same position, we do the ANDs with the
4035 similar mask and compare the result of the ANDs.
4037 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4038 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4039 are the left and right operands of the comparison, respectively.
4041 If the optimization described above can be done, we return the resulting
4042 tree. Otherwise we return zero. */
4044 static tree
4047 {
4051 tree unsigned_type;
4054 scalar_int_mode nmode;
4059 tree mask;
4060 tree offset;
4062 /* Get all the information about the extractions being done. If the bit size
4063 is the same as the size of the underlying object, we aren't doing an
4064 extraction at all and so can do nothing. We also don't want to
4065 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4066 then will no longer be able to replace it. */
4081 else
4082 {
4083 /* If this is not a constant, we can only do something if bit positions,
4084 sizes, signedness and storage order are the same. */
4085 rinner
4098 }
4100 /* Honor the C++ memory model and mimic what RTL expansion does. */
4104 {
4108 }
4110 /* See if we can find a mode to refer to this field. We should be able to,
4111 but fail if we can't. */
4119 /* Set signed and unsigned types of the precision of this mode for the
4120 shifts below. */
4123 /* Compute the bit position and size for the new reference and our offset
4124 within it. If the new reference is the same size as the original, we
4125 won't optimize anything, so return zero. */
4135 /* Make the mask to be used against the extracted field. */
4142 {
4146 /* If not comparing with constant, just rework the comparison
4147 and return. */
4155 }
4157 /* Otherwise, we are handling the constant case. See if the constant is too
4158 big for the field. Warn and return a tree for 0 (false) if so. We do
4159 this not only for its own sake, but to avoid having to test for this
4160 error case below. If we didn't, we might generate wrong code.
4162 For unsigned fields, the constant shifted right by the field length should
4163 be all zero. For signed fields, the high-order bits should agree with
4164 the sign bit. */
4167 {
4169 {
4173 }
4174 }
4175 else
4176 {
4179 {
4183 }
4184 }
4189 /* Single-bit compares should always be against zero. */
4191 {
4194 }
4196 /* Make a new bitfield reference, shift the constant over the
4197 appropriate number of bits and mask it with the computed mask
4198 (in case this was a signed field). If we changed it, make a new one. */
4206 mask);
4211 }
4212 \f
4213 /* Subroutine for fold_truth_andor_1: decode a field reference.
4215 If EXP is a comparison reference, we return the innermost reference.
4217 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4218 set to the starting bit number.
4220 If the innermost field can be completely contained in a mode-sized
4221 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4223 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4224 otherwise it is not changed.
4226 *PUNSIGNEDP is set to the signedness of the field.
4228 *PREVERSEP is set to the storage order of the field.
4230 *PMASK is set to the mask used. This is either contained in a
4231 BIT_AND_EXPR or derived from the width of the field.
4233 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4235 Return 0 if this is not a component reference or is one that we can't
4236 do anything with. */
4238 static tree
4243 {
4248 tree unsigned_type;
4251 /* All the optimizations using this function assume integer fields.
4252 There are problems with FP fields since the type_for_size call
4253 below can fail for, e.g., XFmode. */
4257 /* We are interested in the bare arrangement of bits, so strip everything
4258 that doesn't affect the machine mode. However, record the type of the
4259 outermost expression if it may matter below. */
4266 {
4272 }
4283 /* Reject out-of-bound accesses (PR79731). */
4291 /* If the number of bits in the reference is the same as the bitsize of
4292 the outer type, then the outer type gives the signedness. Otherwise
4293 (in case of a small bitfield) the signedness is unchanged. */
4297 /* Compute the mask to access the bitfield. */
4306 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4314 }
4316 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4317 bit positions and MASK is SIGNED. */
4319 static int
4321 {
4325 /* If this function returns true when the type of the mask is
4326 UNSIGNED, then there will be errors. In particular see
4327 gcc.c-torture/execute/990326-1.c. There does not appear to be
4328 any documentation paper trail as to why this is so. But the pre
4329 wide-int worked with that restriction and it has been preserved
4330 here. */
4335 }
4337 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4338 represents the sign bit of EXP's type. If EXP represents a sign
4339 or zero extension, also test VAL against the unextended type.
4340 The return value is the (sub)expression whose sign bit is VAL,
4341 or NULL_TREE otherwise. */
4343 tree
4345 {
4347 tree t;
4349 /* Tree EXP must have an integral type. */
4354 /* Tree VAL must be an integer constant. */
4363 /* Handle extension from a narrower type. */
4369 }
4371 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4372 to be evaluated unconditionally. */
4374 static int
4376 {
4377 /* Strip any conversions that don't change the machine mode. */
4386 /* Don't regard global variables as simple. They may be
4387 allocated in ways unknown to the compiler (shared memory,
4388 #pragma weak, etc). */
4391 /* Weakrefs are not safe to be read, since they can be NULL.
4392 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4393 have DECL_WEAK flag set. */
4395 /* Loading a static variable is unduly expensive, but global
4396 registers aren't expensive. */
4398 }
4400 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4401 to be evaluated unconditionally.
4402 I addition to simple_operand_p, we assume that comparisons, conversions,
4403 and logic-not operations are simple, if their operands are simple, too. */
4405 static bool
4407 {
4427 }
4429 \f
4430 /* The following functions are subroutines to fold_range_test and allow it to
4431 try to change a logical combination of comparisons into a range test.
4433 For example, both
4434 X == 2 || X == 3 || X == 4 || X == 5
4435 and
4436 X >= 2 && X <= 5
4437 are converted to
4438 (unsigned) (X - 2) <= 3
4440 We describe each set of comparisons as being either inside or outside
4441 a range, using a variable named like IN_P, and then describe the
4442 range with a lower and upper bound. If one of the bounds is omitted,
4443 it represents either the highest or lowest value of the type.
4445 In the comments below, we represent a range by two numbers in brackets
4446 preceded by a "+" to designate being inside that range, or a "-" to
4447 designate being outside that range, so the condition can be inverted by
4448 flipping the prefix. An omitted bound is represented by a "-". For
4449 example, "- [-, 10]" means being outside the range starting at the lowest
4450 possible value and ending at 10, in other words, being greater than 10.
4451 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4452 always false.
4454 We set up things so that the missing bounds are handled in a consistent
4455 manner so neither a missing bound nor "true" and "false" need to be
4456 handled using a special case. */
4458 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4459 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4460 and UPPER1_P are nonzero if the respective argument is an upper bound
4461 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4462 must be specified for a comparison. ARG1 will be converted to ARG0's
4463 type if both are specified. */
4465 static tree
4468 {
4469 tree tem;
4473 /* If neither arg represents infinity, do the normal operation.
4474 Else, if not a comparison, return infinity. Else handle the special
4475 comparison rules. Note that most of the cases below won't occur, but
4476 are handled for consistency. */
4479 {
4484 }
4489 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4490 for neither. In real maths, we cannot assume open ended ranges are
4491 the same. But, this is computer arithmetic, where numbers are finite.
4492 We can therefore make the transformation of any unbounded range with
4493 the value Z, Z being greater than any representable number. This permits
4494 us to treat unbounded ranges as equal. */
4498 {
4519 }
4522 }
4523 \f
4524 /* Helper routine for make_range. Perform one step for it, return
4525 new expression if the loop should continue or NULL_TREE if it should
4526 stop. */
4528 tree
4532 {
4538 {
4540 /* We can only do something if the range is testing for zero. */
4549 /* We can only do something if the range is testing for zero
4550 and if the second operand is an integer constant. Note that
4551 saying something is "in" the range we make is done by
4552 complementing IN_P since it will set in the initial case of
4553 being not equal to zero; "out" is leaving it alone. */
4560 {
4581 }
4583 /* If this is an unsigned comparison, we also know that EXP is
4584 greater than or equal to zero. We base the range tests we make
4585 on that fact, so we record it here so we can parse existing
4586 range tests. We test arg0_type since often the return type
4587 of, e.g. EQ_EXPR, is boolean. */
4589 {
4593 NULL_TREE))
4598 /* If the high bound is missing, but we have a nonzero low
4599 bound, reverse the range so it goes from zero to the low bound
4600 minus 1. */
4602 {
4607 }
4608 }
4616 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4617 low and high are non-NULL, then normalize will DTRT. */
4620 {
4625 }
4627 /* (-x) IN [a,b] -> x in [-b, -a] */
4639 /* ~ X -> -X - 1 */
4648 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4649 move a constant to the other side. */
4654 /* If EXP is signed, any overflow in the computation is undefined,
4655 so we don't worry about it so long as our computations on
4656 the bounds don't overflow. For unsigned, overflow is defined
4657 and this is exactly the right thing. */
4669 normalize:
4670 /* Check for an unsigned range which has wrapped around the maximum
4671 value thus making n_high < n_low, and normalize it. */
4673 {
4679 /* If the range is of the form +/- [ x+1, x ], we won't
4680 be able to normalize it. But then, it represents the
4681 whole range or the empty set, so make it
4682 +/- [ -, - ]. */
4686 else
4688 }
4689 else
4697 CASE_CONVERT:
4715 /* If we're converting arg0 from an unsigned type, to exp,
4716 a signed type, we will be doing the comparison as unsigned.
4717 The tests above have already verified that LOW and HIGH
4718 are both positive.
4720 So we have to ensure that we will handle large unsigned
4721 values the same way that the current signed bounds treat
4722 negative values. */
4725 {
4726 tree high_positive;
4727 tree equiv_type;
4728 /* For fixed-point modes, we need to pass the saturating flag
4729 as the 2nd parameter. */
4731 equiv_type
4734 else
4735 equiv_type
4738 /* A range without an upper bound is, naturally, unbounded.
4739 Since convert would have cropped a very large value, use
4740 the max value for the destination type. */
4741 high_positive
4748 high_positive),
4751 /* If the low bound is specified, "and" the range with the
4752 range for which the original unsigned value will be
4753 positive. */
4755 {
4758 integer_zero_node),
4759 high_positive))
4763 }
4764 else
4765 {
4766 /* Otherwise, "or" the range with the range of the input
4767 that will be interpreted as negative. */
4770 integer_zero_node),
4771 high_positive))
4775 }
4776 }
4785 }
4786 }
4788 /* Given EXP, a logical expression, set the range it is testing into
4789 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4790 actually being tested. *PLOW and *PHIGH will be made of the same
4791 type as the returned expression. If EXP is not a comparison, we
4792 will most likely not be returning a useful value and range. Set
4793 *STRICT_OVERFLOW_P to true if the return value is only valid
4794 because signed overflow is undefined; otherwise, do not change
4795 *STRICT_OVERFLOW_P. */
4797 tree
4800 {
4808 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4809 and see if we can refine the range. Some of the cases below may not
4810 happen, but it doesn't seem worth worrying about this. We "continue"
4811 the outer loop when we've changed something; otherwise we "break"
4812 the switch, which will "break" the while. */
4818 {
4824 {
4832 }
4841 }
4843 /* If EXP is a constant, we can evaluate whether this is true or false. */
4845 {
4852 }
4856 }
4858 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4859 a bitwise check i.e. when
4860 LOW == 0xXX...X00...0
4861 HIGH == 0xXX...X11...1
4862 Return corresponding mask in MASK and stem in VALUE. */
4864 static bool
4867 {
4890 }
4891 \f
4892 /* Helper routine for build_range_check and match.pd. Return the type to
4893 perform the check or NULL if it shouldn't be optimized. */
4895 tree
4897 {
4898 /* First make sure that arithmetics in this type is valid, then make sure
4899 that it wraps around. */
4905 {
4908 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4909 for the type in question, as we rely on this here. */
4919 else
4921 }
4923 }
4925 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4926 type, TYPE, return an expression to test if EXP is in (or out of, depending
4927 on IN_P) the range. Return 0 if the test couldn't be created. */
4929 tree
4932 {
4935 /* Disable this optimization for function pointer expressions
4936 on targets that require function pointer canonicalization. */
4943 {
4949 }
4971 value);
4974 {
4976 {
4980 }
4982 }
4984 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4986 {
4990 {
4992 {
4995 etype
4997 else
5000 }
5003 }
5004 }
5006 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5007 This requires wrap-around arithmetics for the type of the expression. */
5027 }
5028 \f
5029 /* Return the predecessor of VAL in its type, handling the infinite case. */
5031 static tree
5033 {
5039 else
5042 }
5044 /* Return the successor of VAL in its type, handling the infinite case. */
5046 static tree
5048 {
5054 else
5057 }
5059 /* Given two ranges, see if we can merge them into one. Return 1 if we
5060 can, 0 if we can't. Set the output range into the specified parameters. */
5062 bool
5065 {
5069 tree tem;
5079 /* Make range 0 be the range that starts first, or ends last if they
5080 start at the same value. Swap them if it isn't. */
5083 || (lowequal
5086 {
5090 }
5092 /* If the second range is != high1 where high1 is the type maximum of
5093 the type, try first merging with < high1 range. */
5095 && high1
5102 {
5107 /* Similarly for the second range != low1 where low1 is the type minimum
5108 of the type, try first merging with > low1 range. */
5113 }
5115 /* Now flag two cases, whether the ranges are disjoint or whether the
5116 second range is totally subsumed in the first. Note that the tests
5117 below are simplified by the ones above. */
5123 /* We now have four cases, depending on whether we are including or
5124 excluding the two ranges. */
5126 {
5127 /* If they don't overlap, the result is false. If the second range
5128 is a subset it is the result. Otherwise, the range is from the start
5129 of the second to the end of the first. */
5134 else
5136 }
5139 {
5140 /* If they don't overlap, the result is the first range. If they are
5141 equal, the result is false. If the second range is a subset of the
5142 first, and the ranges begin at the same place, we go from just after
5143 the end of the second range to the end of the first. If the second
5144 range is not a subset of the first, or if it is a subset and both
5145 ranges end at the same place, the range starts at the start of the
5146 first range and ends just before the second range.
5147 Otherwise, we can't describe this as a single range. */
5153 {
5158 {
5159 /* We are in the weird situation where high0 > high1 but
5160 high1 has no successor. Punt. */
5162 }
5163 }
5165 {
5170 {
5171 /* low0 < low1 but low1 has no predecessor. Punt. */
5173 }
5174 }
5175 else
5177 }
5180 {
5181 /* If they don't overlap, the result is the second range. If the second
5182 is a subset of the first, the result is false. Otherwise,
5183 the range starts just after the first range and ends at the
5184 end of the second. */
5189 else
5190 {
5195 {
5196 /* high1 > high0 but high0 has no successor. Punt. */
5198 }
5199 }
5200 }
5202 else
5203 {
5204 /* The case where we are excluding both ranges. Here the complex case
5205 is if they don't overlap. In that case, the only time we have a
5206 range is if they are adjacent. If the second is a subset of the
5207 first, the result is the first. Otherwise, the range to exclude
5208 starts at the beginning of the first range and ends at the end of the
5209 second. */
5211 {
5216 else
5217 {
5218 /* Canonicalize - [min, x] into - [-, x]. */
5221 {
5224 GET_MODE_BITSIZE
5227 /* FALLTHROUGH */
5240 }
5242 /* Canonicalize - [x, max] into - [x, -]. */
5245 {
5248 GET_MODE_BITSIZE
5251 /* FALLTHROUGH */
5267 }
5269 /* The ranges might be also adjacent between the maximum and
5270 minimum values of the given type. For
5271 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5272 return + [x + 1, y - 1]. */
5274 {
5281 }
5282 else
5284 }
5285 }
5288 else
5290 }
5294 }
5295 \f
5297 /* Subroutine of fold, looking inside expressions of the form
5298 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5299 of the COND_EXPR. This function is being used also to optimize
5300 A op B ? C : A, by reversing the comparison first.
5302 Return a folded expression whose code is not a COND_EXPR
5303 anymore, or NULL_TREE if no folding opportunity is found. */
5305 static tree
5308 {
5313 tree tem;
5318 /* If we have A op 0 ? A : -A, consider applying the following
5319 transformations:
5321 A == 0? A : -A same as -A
5322 A != 0? A : -A same as A
5323 A >= 0? A : -A same as abs (A)
5324 A > 0? A : -A same as abs (A)
5325 A <= 0? A : -A same as -abs (A)
5326 A < 0? A : -A same as -abs (A)
5328 None of these transformations work for modes with signed
5329 zeros. If A is +/-0, the first two transformations will
5330 change the sign of the result (from +0 to -0, or vice
5331 versa). The last four will fix the sign of the result,
5332 even though the original expressions could be positive or
5333 negative, depending on the sign of A.
5335 Note that all these transformations are correct if A is
5336 NaN, since the two alternatives (A and -A) are also NaNs. */
5343 /* In the case that A is of the form X-Y, '-A' (arg2) may
5344 have already been folded to Y-X, check for that. */
5352 {
5364 /* Fall through. */
5375 /* FALLTHRU */
5385 }
5387 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5388 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5389 both transformations are correct when A is NaN: A != 0
5390 is then true, and A == 0 is false. */
5394 {
5399 }
5401 /* Try some transformations of A op B ? A : B.
5403 A == B? A : B same as B
5404 A != B? A : B same as A
5405 A >= B? A : B same as max (A, B)
5406 A > B? A : B same as max (B, A)
5407 A <= B? A : B same as min (A, B)
5408 A < B? A : B same as min (B, A)
5410 As above, these transformations don't work in the presence
5411 of signed zeros. For example, if A and B are zeros of
5412 opposite sign, the first two transformations will change
5413 the sign of the result. In the last four, the original
5414 expressions give different results for (A=+0, B=-0) and
5415 (A=-0, B=+0), but the transformed expressions do not.
5417 The first two transformations are correct if either A or B
5418 is a NaN. In the first transformation, the condition will
5419 be false, and B will indeed be chosen. In the case of the
5420 second transformation, the condition A != B will be true,
5421 and A will be chosen.
5423 The conversions to max() and min() are not correct if B is
5424 a number and A is not. The conditions in the original
5425 expressions will be false, so all four give B. The min()
5426 and max() versions would give a NaN instead. */
5429 /* Avoid these transformations if the COND_EXPR may be used
5430 as an lvalue in the C++ front-end. PR c++/19199. */
5431 && (in_gimple_form
5437 {
5443 {
5452 /* In C++ a ?: expression can be an lvalue, so put the
5453 operand which will be used if they are equal first
5454 so that we can convert this back to the
5455 corresponding COND_EXPR. */
5457 {
5465 }
5472 {
5480 }
5493 }
5494 }
5497 }
5500 \f
5501 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5502 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5503 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5504 false) >= 2)
5505 #endif
5507 /* EXP is some logical combination of boolean tests. See if we can
5508 merge it into some range test. Return the new tree if so. */
5510 static tree
5513 {
5529 /* If this is an OR operation, invert both sides; we will invert
5530 again at the end. */
5534 /* If both expressions are the same, if we can merge the ranges, and we
5535 can build the range test, return it or it inverted. If one of the
5536 ranges is always true or always false, consider it to be the same
5537 expression as the other. */
5545 {
5549 }
5551 /* On machines where the branch cost is expensive, if this is a
5552 short-circuited branch and the underlying object on both sides
5553 is the same, make a non-short-circuit operation. */
5555 && !flag_sanitize_coverage
5560 {
5561 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5562 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5563 which cases we can't do this. */
5571 {
5580 {
5583 WARN_STRICT_OVERFLOW_COMPARISON);
5587 }
5588 }
5589 }
5592 }
5593 \f
5594 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5595 bit value. Arrange things so the extra bits will be set to zero if and
5596 only if C is signed-extended to its full width. If MASK is nonzero,
5597 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5599 static tree
5601 {
5604 tree temp;
5609 /* We work by getting just the sign bit into the low-order bit, then
5610 into the high-order bit, then sign-extend. We then XOR that value
5611 with C. */
5615 /* We must use a signed type in order to get an arithmetic right shift.
5616 However, we must also avoid introducing accidental overflows, so that
5617 a subsequent call to integer_zerop will work. Hence we must
5618 do the type conversion here. At this point, the constant is either
5619 zero or one, and the conversion to a signed type can never overflow.
5620 We could get an overflow if this conversion is done anywhere else. */
5629 /* If necessary, convert the type back to match the type of C. */
5634 }
5635 \f
5636 /* For an expression that has the form
5637 (A && B) || ~B
5638 or
5639 (A || B) && ~B,
5640 we can drop one of the inner expressions and simplify to
5641 A || ~B
5642 or
5643 A && ~B
5644 LOC is the location of the resulting expression. OP is the inner
5645 logical operation; the left-hand side in the examples above, while CMPOP
5646 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5647 removing a condition that guards another, as in
5648 (A != NULL && A->...) || A == NULL
5649 which we must not transform. If RHS_ONLY is true, only eliminate the
5650 right-most operand of the inner logical operation. */
5652 static tree
5655 {
5673 {
5676 {
5679 }
5680 }
5682 {
5685 {
5688 }
5689 }
5704 }
5706 /* Find ways of folding logical expressions of LHS and RHS:
5707 Try to merge two comparisons to the same innermost item.
5708 Look for range tests like "ch >= '0' && ch <= '9'".
5709 Look for combinations of simple terms on machines with expensive branches
5710 and evaluate the RHS unconditionally.
5712 For example, if we have p->a == 2 && p->b == 4 and we can make an
5713 object large enough to span both A and B, we can do this with a comparison
5714 against the object ANDed with the a mask.
5716 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5717 operations to do this with one comparison.
5719 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5720 function and the one above.
5722 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5723 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5725 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5726 two operands.
5728 We return the simplified tree or 0 if no optimization is possible. */
5730 static tree
5733 {
5734 /* If this is the "or" of two comparisons, we can do something if
5735 the comparisons are NE_EXPR. If this is the "and", we can do something
5736 if the comparisons are EQ_EXPR. I.e.,
5737 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5739 WANTED_CODE is this operation code. For single bit fields, we can
5740 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5741 comparison for one-bit fields. */
5762 /* Start by getting the comparison codes. Fail if anything is volatile.
5763 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5764 it were surrounded with a NE_EXPR. */
5773 {
5777 }
5780 {
5784 }
5795 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5798 {
5801 {
5806 }
5809 {
5815 }
5816 }
5821 /* If the RHS can be evaluated unconditionally and its operands are
5822 simple, it wins to evaluate the RHS unconditionally on machines
5823 with expensive branches. In this case, this isn't a comparison
5824 that can be merged. */
5831 {
5832 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5843 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5853 }
5855 /* See if the comparisons can be merged. Then get all the parameters for
5856 each side. */
5881 /* It must be true that the inner operation on the lhs of each
5882 comparison must be the same if we are to be able to do anything.
5883 Then see if we have constants. If not, the same must be true for
5884 the rhs's. */
5893 {
5896 }
5901 else
5904 /* If either comparison code is not correct for our logical operation,
5905 fail. However, we can convert a one-bit comparison against zero into
5906 the opposite comparison against that bit being set in the field. */
5910 {
5912 {
5913 /* Make the left operand unsigned, since we are only interested
5914 in the value of one bit. Otherwise we are doing the wrong
5915 thing below. */
5918 }
5919 else
5921 }
5923 /* This is analogous to the code for l_const above. */
5925 {
5927 {
5930 }
5931 else
5933 }
5935 /* See if we can find a mode that contains both fields being compared on
5936 the left. If we can't, fail. Otherwise, update all constants and masks
5937 to be relative to a field of that size. */
5951 {
5954 }
5962 {
5969 {
5973 }
5974 }
5976 {
5983 {
5987 }
5988 }
5990 /* If the right sides are not constant, do the same for it. Also,
5991 disallow this optimization if a size or signedness mismatch occurs
5992 between the left and right sides. */
5994 {
5997 /* Make sure the two fields on the right
5998 correspond to the left without being swapped. */
6015 {
6018 }
6027 /* Make a mask that corresponds to both fields being compared.
6028 Do this for both items being compared. If the operands are the
6029 same size and the bits being compared are in the same position
6030 then we can do this by masking both and comparing the masked
6031 results. */
6038 {
6052 }
6054 /* There is still another way we can do something: If both pairs of
6055 fields being compared are adjacent, we may be able to make a wider
6056 field containing them both.
6058 Note that we still must mask the lhs/rhs expressions. Furthermore,
6059 the mask must be shifted to account for the shift done by
6060 make_bit_field_ref. */
6069 {
6070 tree type;
6086 /* Convert to the smaller type before masking out unwanted bits. */
6089 {
6091 {
6095 }
6097 {
6101 }
6102 }
6111 }
6114 }
6116 /* Handle the case of comparisons with constants. If there is something in
6117 common between the masks, those bits of the constants must be the same.
6118 If not, the condition is always false. Test for this to avoid generating
6119 incorrect code below. */
6124 {
6126 {
6129 }
6130 else
6131 {
6134 }
6135 }
6140 /* Construct the expression we will return. First get the component
6141 reference we will make. Unless the mask is all ones the width of
6142 that field, perform the mask operation. Then compare with the
6143 merged constant. */
6154 }
6155 \f
6156 /* T is an integer expression that is being multiplied, divided, or taken a
6157 modulus (CODE says which and what kind of divide or modulus) by a
6158 constant C. See if we can eliminate that operation by folding it with
6159 other operations already in T. WIDE_TYPE, if non-null, is a type that
6160 should be used for the computation if wider than our type.
6162 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6163 (X * 2) + (Y * 4). We must, however, be assured that either the original
6164 expression would not overflow or that overflow is undefined for the type
6165 in the language in question.
6167 If we return a non-null expression, it is an equivalent form of the
6168 original computation, but need not be in the original type.
6170 We set *STRICT_OVERFLOW_P to true if the return values depends on
6171 signed overflow being undefined. Otherwise we do not change
6172 *STRICT_OVERFLOW_P. */
6174 static tree
6177 {
6178 /* To avoid exponential search depth, refuse to allow recursion past
6179 three levels. Beyond that (1) it's highly unlikely that we'll find
6180 something interesting and (2) we've probably processed it before
6181 when we built the inner expression. */
6184 tree ret;
6189 depth++;
6191 depth--;
6194 }
6196 static tree
6199 {
6211 /* Don't deal with constants of zero here; they confuse the code below. */
6221 /* Note that we need not handle conditional operations here since fold
6222 already handles those cases. So just do arithmetic here. */
6224 {
6226 /* For a constant, we can always simplify if we are a multiply
6227 or (for divide and modulus) if it is a multiple of our constant. */
6231 {
6234 /* If the multiplication overflowed, we lost information on it.
6235 See PR68142 and PR69845. */
6239 }
6243 /* If op0 is an expression ... */
6249 /* ... and has wrapping overflow, and its type is smaller
6250 than ctype, then we cannot pass through as widening. */
6255 /* ... or this is a truncation (t is narrower than op0),
6256 then we cannot pass through this narrowing. */
6259 /* ... or signedness changes for division or modulus,
6260 then we cannot pass through this conversion. */
6264 /* ... or has undefined overflow while the converted to
6265 type has not, we cannot do the operation in the inner type
6266 as that would introduce undefined overflow. */
6272 /* Pass the constant down and see if we can make a simplification. If
6273 we can, replace this expression with the inner simplification for
6274 possible later conversion to our or some other type. */
6285 /* If widening the type changes it from signed to unsigned, then we
6286 must avoid building ABS_EXPR itself as unsigned. */
6288 {
6292 {
6295 }
6297 }
6298 /* If the constant is negative, we cannot simplify this. */
6301 /* FALLTHROUGH */
6303 /* For division and modulus, type can't be unsigned, as e.g.
6304 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6305 For signed types, even with wrapping overflow, this is fine. */
6314 /* If widening the type changes the signedness, then we can't perform
6315 this optimization as that changes the result. */
6319 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6325 {
6332 }
6336 /* If the second operand is constant, this is a multiplication
6337 or floor division, by a power of two, so we can treat it that
6338 way unless the multiplier or divisor overflows. Signed
6339 left-shift overflow is implementation-defined rather than
6340 undefined in C90, so do not convert signed left shift into
6341 multiplication. */
6344 /* const_binop may not detect overflow correctly,
6345 so check for it explicitly here. */
6354 ctype,
6356 t1),
6361 /* See if we can eliminate the operation on both sides. If we can, we
6362 can return a new PLUS or MINUS. If we can't, the only remaining
6363 cases where we can do anything are if the second operand is a
6364 constant. */
6371 /* If not multiplication, we can only do this if both operands
6372 are divisible by c. */
6375 {
6380 }
6382 /* If this was a subtraction, negate OP1 and set it to be an addition.
6383 This simplifies the logic below. */
6385 {
6387 /* If OP1 was not easily negatable, the constant may be OP0. */
6389 {
6392 }
6393 }
6398 /* If either OP1 or C are negative, this optimization is not safe for
6399 some of the division and remainder types while for others we need
6400 to change the code. */
6402 {
6410 }
6412 /* If it's a multiply or a division/modulus operation of a multiple
6413 of our constant, do the operation and verify it doesn't overflow. */
6417 {
6420 /* We allow the constant to overflow with wrapping semantics. */
6424 }
6425 else
6428 /* If we have an unsigned type, we cannot widen the operation since it
6429 will change the result if the original computation overflowed. */
6433 /* The last case is if we are a multiply. In that case, we can
6434 apply the distributive law to commute the multiply and addition
6435 if the multiplication of the constants doesn't overflow
6436 and overflow is defined. With undefined overflow
6437 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6443 op1);
6448 /* We have a special case here if we are doing something like
6449 (C * 8) % 4 since we know that's zero. */
6452 /* If the multiplication can overflow we cannot optimize this. */
6457 {
6460 }
6462 /* ... fall through ... */
6466 /* If we can extract our operation from the LHS, do so and return a
6467 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6468 do something only if the second operand is a constant. */
6484 /* If these are the same operation types, we can associate them
6485 assuming no overflow. */
6487 {
6502 }
6504 /* If these operations "cancel" each other, we have the main
6505 optimizations of this pass, which occur when either constant is a
6506 multiple of the other, in which case we replace this with either an
6507 operation or CODE or TCODE.
6509 If we have an unsigned type, we cannot do this since it will change
6510 the result if the original computation overflowed. */
6517 {
6520 {
6527 }
6530 {
6537 }
6538 }
6543 }
6546 }
6547 \f
6548 /* Return a node which has the indicated constant VALUE (either 0 or
6549 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6550 and is of the indicated TYPE. */
6552 tree
6554 {
6563 else
6565 }
6568 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6569 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6570 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6571 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6572 COND is the first argument to CODE; otherwise (as in the example
6573 given here), it is the second argument. TYPE is the type of the
6574 original expression. Return NULL_TREE if no simplification is
6575 possible. */
6577 static tree
6582 {
6592 {
6596 /* If this operand throws an expression, then it does not make
6597 sense to try to perform a logical or arithmetic operation
6598 involving it. */
6603 }
6606 {
6611 }
6612 else
6613 /* Detect the case of mixing vector and scalar types - bail out. */
6619 /* This transformation is only worthwhile if we don't have to wrap ARG
6620 in a SAVE_EXPR and the operation can be simplified without recursing
6621 on at least one of the branches once its pushed inside the COND_EXPR. */
6630 {
6634 else
6636 }
6638 {
6642 else
6644 }
6646 /* Check that we have simplified at least one of the branches. */
6651 }
6653 \f
6654 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6656 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6657 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6658 ADDEND is the same as X.
6660 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6661 and finite. The problematic cases are when X is zero, and its mode
6662 has signed zeros. In the case of rounding towards -infinity,
6663 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6664 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6666 bool
6668 {
6672 /* Don't allow the fold with -fsignaling-nans. */
6676 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6680 /* In a vector or complex, we would need to check the sign of all zeros. */
6684 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6688 /* The mode has signed zeros, and we have to honor their sign.
6689 In this situation, there is only one case we can return true for.
6690 X - 0 is the same as X unless rounding towards -infinity is
6691 supported. */
6693 }
6695 /* Subroutine of match.pd that optimizes comparisons of a division by
6696 a nonzero integer constant against an integer constant, i.e.
6697 X/C1 op C2.
6699 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6700 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6702 enum tree_code
6705 {
6710 /* We have to do this the hard way to detect unsigned overflow.
6711 prod = int_const_binop (MULT_EXPR, c1, c2); */
6717 {
6721 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6724 }
6726 {
6729 {
6748 }
6749 }
6750 else
6751 {
6752 /* A negative divisor reverses the relational operators. */
6757 {
6776 }
6777 }
6790 }
6793 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6794 equality/inequality test, then return a simplified form of the test
6795 using a sign testing. Otherwise return NULL. TYPE is the desired
6796 result type. */
6798 static tree
6801 tree result_type)
6802 {
6803 /* If this is testing a single bit, we can optimize the test. */
6807 {
6808 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6809 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6813 /* This is only a win if casting to a signed type is cheap,
6814 i.e. when arg00's type is not a partial mode. */
6816 {
6819 result_type,
6822 }
6823 }
6826 }
6828 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6829 equality/inequality test, then return a simplified form of
6830 the test using shifts and logical operations. Otherwise return
6831 NULL. TYPE is the desired result type. */
6833 tree
6836 {
6837 /* If this is testing a single bit, we can optimize the test. */
6841 {
6850 /* First, see if we can fold the single bit test into a sign-bit
6851 test. */
6853 result_type);
6857 /* Otherwise we have (A & C) != 0 where C is a single bit,
6858 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6859 Similarly for (A & C) == 0. */
6861 /* If INNER is a right shift of a constant and it plus BITNUM does
6862 not overflow, adjust BITNUM and INNER. */
6868 {
6871 }
6873 /* If we are going to be able to omit the AND below, we must do our
6874 operations as unsigned. If we must use the AND, we have a choice.
6875 Normally unsigned is faster, but for some machines signed is. */
6893 /* Put the AND last so it can combine with more things. */
6896 /* Make sure to return the proper type. */
6900 }
6902 }
6904 /* Test whether it is preferable two swap two operands, ARG0 and
6905 ARG1, for example because ARG0 is an integer constant and ARG1
6906 isn't. */
6908 bool
6910 {
6924 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6925 for commutative and comparison operators. Ensuring a canonical
6926 form allows the optimizers to find additional redundancies without
6927 having to explicitly check for both orderings. */
6933 /* Put SSA_NAMEs last. */
6939 /* Put variables last. */
6946 }
6949 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6950 means A >= Y && A != MAX, but in this case we know that
6951 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6953 static tree
6955 {
6962 else
6971 {
6974 }
6976 {
6979 }
6980 else
6987 {
6988 /* Convert the pointer types into integer before taking the difference. */
6992 }
6993 else
7000 }
7002 /* Fold a sum or difference of at least one multiplication.
7003 Returns the folded tree or NULL if no simplification could be made. */
7005 static tree
7008 {
7012 /* (A * C) +- (B * C) -> (A+-B) * C.
7013 (A * C) +- A -> A * (C+-1).
7014 We are most concerned about the case where C is a constant,
7015 but other combinations show up during loop reduction. Since
7016 it is not difficult, try all four possibilities. */
7019 {
7022 }
7024 {
7027 }
7028 else
7029 {
7030 /* We cannot generate constant 1 for fract. */
7035 }
7037 {
7040 }
7042 {
7044 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7045 the purpose of this canonicalization. */
7049 {
7052 }
7053 else
7055 }
7056 else
7057 {
7058 /* We cannot generate constant 1 for fract. */
7063 }
7066 /* Prefer factoring a common non-constant. */
7076 /* No identical multiplicands; see if we can find a common
7077 power-of-two factor in non-power-of-two multiplies. This
7078 can help in multi-dimensional array access. */
7081 {
7084 tree maybe_same;
7088 /* Move min of absolute values to int11. */
7090 {
7095 }
7096 else
7100 /* The remainder should not be a constant, otherwise we
7101 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7102 increased the number of multiplications necessary. */
7104 {
7112 }
7113 }
7120 /* We are neither factoring zero nor minus one. */
7128 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7129 same may be minus one and thus the multiplication may overflow. Perform
7130 the sum operation in an unsigned type. */
7135 /* If the sum evaluated to a constant that is not -INF the multiplication
7136 cannot overflow. */
7143 /* Do not resort to unsigned multiplication because
7144 we lose the no-overflow property of the expression. */
7146 }
7148 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7149 specified by EXPR into the buffer PTR of length LEN bytes.
7150 Return the number of bytes placed in the buffer, or zero
7151 upon failure. */
7153 static int
7155 {
7167 /* Dry run. */
7173 {
7175 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7176 number of bytes. */
7180 {
7187 else
7189 }
7190 else
7194 }
7196 }
7199 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7200 specified by EXPR into the buffer PTR of length LEN bytes.
7201 Return the number of bytes placed in the buffer, or zero
7202 upon failure. */
7204 static int
7206 {
7210 FIXED_VALUE_TYPE value;
7225 }
7228 /* Subroutine of native_encode_expr. Encode the REAL_CST
7229 specified by EXPR into the buffer PTR of length LEN bytes.
7230 Return the number of bytes placed in the buffer, or zero
7231 upon failure. */
7233 static int
7235 {
7241 /* There are always 32 bits in each long, no matter the size of
7242 the hosts long. We handle floating point representations with
7243 up to 192 bits. */
7252 /* Dry run. */
7261 {
7266 {
7273 else
7275 }
7276 else
7277 {
7280 {
7281 /* Reverse bytes within each long, or within the entire float
7282 if it's smaller than a long (for HFmode). */
7285 }
7286 }
7291 }
7293 }
7295 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7296 specified by EXPR into the buffer PTR of length LEN bytes.
7297 Return the number of bytes placed in the buffer, or zero
7298 upon failure. */
7300 static int
7302 {
7304 tree part;
7318 }
7321 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7322 specified by EXPR into the buffer PTR of length LEN bytes.
7323 Return the number of bytes placed in the buffer, or zero
7324 upon failure. */
7326 static int
7328 {
7339 {
7341 {
7344 }
7355 }
7357 }
7360 /* Subroutine of native_encode_expr. Encode the STRING_CST
7361 specified by EXPR into the buffer PTR of length LEN bytes.
7362 Return the number of bytes placed in the buffer, or zero
7363 upon failure. */
7365 static int
7367 {
7370 /* Wide-char strings are encoded in target byte-order so native
7371 encoding them is trivial. */
7386 {
7389 {
7392 }
7395 }
7396 else
7399 }
7402 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7403 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7404 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7405 anything, just do a dry run. If OFF is not -1 then start
7406 the encoding at byte offset OFF and encode at most LEN bytes.
7407 Return the number of bytes placed in the buffer, or zero upon failure. */
7409 int
7411 {
7412 /* We don't support starting at negative offset and -1 is special. */
7417 {
7438 }
7439 }
7442 /* Subroutine of native_interpret_expr. Interpret the contents of
7443 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7444 If the buffer cannot be interpreted, return NULL_TREE. */
7446 static tree
7448 {
7458 }
7461 /* Subroutine of native_interpret_expr. Interpret the contents of
7462 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7463 If the buffer cannot be interpreted, return NULL_TREE. */
7465 static tree
7467 {
7470 double_int result;
7471 FIXED_VALUE_TYPE fixed_value;
7481 }
7484 /* Subroutine of native_interpret_expr. Interpret the contents of
7485 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7486 If the buffer cannot be interpreted, return NULL_TREE. */
7488 static tree
7490 {
7494 /* There are always 32 bits in each long, no matter the size of
7495 the hosts long. We handle floating point representations with
7496 up to 192 bits. */
7497 REAL_VALUE_TYPE r;
7507 {
7508 /* Both OFFSET and BYTE index within a long;
7509 bitpos indexes the whole float. */
7512 {
7519 else
7521 }
7522 else
7523 {
7526 {
7527 /* Reverse bytes within each long, or within the entire float
7528 if it's smaller than a long (for HFmode). */
7531 }
7532 }
7536 }
7540 }
7543 /* Subroutine of native_interpret_expr. Interpret the contents of
7544 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7545 If the buffer cannot be interpreted, return NULL_TREE. */
7547 static tree
7549 {
7564 }
7567 /* Subroutine of native_interpret_expr. Interpret the contents of
7568 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7569 If the buffer cannot be interpreted, return NULL_TREE. */
7571 static tree
7573 {
7586 {
7591 }
7593 }
7596 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7597 the buffer PTR of length LEN as a constant of type TYPE. For
7598 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7599 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7600 return NULL_TREE. */
7602 tree
7604 {
7606 {
7628 }
7629 }
7631 /* Returns true if we can interpret the contents of a native encoding
7632 as TYPE. */
7634 static bool
7636 {
7638 {
7651 }
7652 }
7655 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7656 TYPE at compile-time. If we're unable to perform the conversion
7657 return NULL_TREE. */
7659 static tree
7661 {
7662 /* We support up to 512-bit values (for V8DFmode). */
7666 /* Check that the host and target are sane. */
7675 }
7677 /* Build an expression for the address of T. Folds away INDIRECT_REF
7678 to avoid confusing the gimplify process. */
7680 tree
7682 {
7683 /* The size of the object is not relevant when talking about its address. */
7688 {
7693 }
7703 {
7708 }
7709 else
7713 }
7715 /* Build an expression for the address of T. */
7717 tree
7719 {
7723 }
7725 /* Fold a unary expression of code CODE and type TYPE with operand
7726 OP0. Return the folded expression if folding is successful.
7727 Otherwise, return NULL_TREE. */
7729 tree
7731 {
7732 tree tem;
7733 tree arg0;
7741 {
7744 {
7745 /* Don't use STRIP_NOPS, because signedness of argument type
7746 matters. */
7748 }
7749 else
7750 {
7751 /* Strip any conversions that don't change the mode. This
7752 is safe for every expression, except for a comparison
7753 expression because its signedness is derived from its
7754 operands.
7756 Note that this is done as an internal manipulation within
7757 the constant folder, in order to find the simplest
7758 representation of the arguments so that their form can be
7759 studied. In any cases, the appropriate type conversions
7760 should be put back in the tree that will get out of the
7761 constant folder. */
7763 }
7766 {
7769 {
7773 }
7774 }
7775 }
7782 {
7789 {
7803 /* If this was a conversion, and all we did was to move into
7804 inside the COND_EXPR, bring it back out. But leave it if
7805 it is a conversion from integer to integer and the
7806 result precision is no wider than a word since such a
7807 conversion is cheap and may be optimized away by combine,
7808 while it couldn't if it were outside the COND_EXPR. Then return
7809 so we don't get into an infinite recursion loop taking the
7810 conversion out and then back in. */
7822 && (INTEGRAL_TYPE_P
7835 }
7836 }
7839 {
7845 CASE_CONVERT:
7849 {
7850 /* If we have (type) (a CMP b) and type is an integral type, return
7851 new expression involving the new type. Canonicalize
7852 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7853 non-integral type.
7854 Do not fold the result as that would not simplify further, also
7855 folding again results in recursions. */
7865 }
7867 /* Handle (T *)&A.B.C for A being of type T and B and C
7868 living at offset zero. This occurs frequently in
7869 C++ upcasting and then accessing the base. */
7873 {
7875 tree offset;
7876 machine_mode mode;
7878 tree base
7882 /* If the reference was to a (constant) zero offset, we can use
7883 the address of the base if it has the same base type
7884 as the result type and the pointer type is unqualified. */
7892 }
7896 /* Detect assigning a bitfield. */
7898 && DECL_BIT_FIELD
7900 {
7901 /* Don't leave an assignment inside a conversion
7902 unless assigning a bitfield. */
7904 /* First do the assignment, then return converted constant. */
7909 }
7911 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7912 constants (if x has signed type, the sign bit cannot be set
7913 in c). This folds extension into the BIT_AND_EXPR.
7914 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7915 very likely don't have maximal range for their precision and this
7916 transformation effectively doesn't preserve non-maximal ranges. */
7920 {
7931 <= HOST_BITS_PER_WIDE_INT
7933 {
7937 cst &= HOST_WIDE_INT_M1U
7941 && !flag_syntax_only
7944 {
7948 }
7949 }
7951 {
7956 }
7957 }
7959 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7960 cast (T1)X will fold away. We assume that this happens when X itself
7961 is a cast. */
7965 {
7969 return fold_build_pointer_plus_loc
7971 }
7973 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7974 of the same precision, and X is an integer type not narrower than
7975 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7981 {
7987 }
7989 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7990 type of X and Y (integer types only). */
7995 {
7996 /* Be careful not to introduce new overflows. */
7997 tree mult_type;
8000 else
8004 {
8011 }
8012 }
8018 {
8025 }
8036 /* Convert fabs((double)float) into (double)fabsf(float). */
8039 {
8045 targ0));
8046 }
8050 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8069 /* Note that the operand of this must be an int
8070 and its values must be 0 or 1.
8071 ("true" is a fixed value perhaps depending on the language,
8072 but we don't handle values other than 1 correctly yet.) */
8079 /* Fold *&X to X if X is an lvalue. */
8081 {
8088 }
8094 }
8097 /* If the operation was a conversion do _not_ mark a resulting constant
8098 with TREE_OVERFLOW if the original constant was not. These conversions
8099 have implementation defined behavior and retaining the TREE_OVERFLOW
8100 flag here would confuse later passes such as VRP. */
8101 tree
8104 {
8113 }
8115 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8116 operands OP0 and OP1. LOC is the location of the resulting expression.
8117 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8118 Return the folded expression if folding is successful. Otherwise,
8119 return NULL_TREE. */
8120 static tree
8123 {
8124 tree tem;
8126 /* We only do these simplifications if we are optimizing. */
8130 /* Check for things like (A || B) && (A || C). We can convert this
8131 to A || (B && C). Note that either operator can be any of the four
8132 truth and/or operations and the transformation will still be
8133 valid. Also note that we only care about order for the
8134 ANDIF and ORIF operators. If B contains side effects, this
8135 might change the truth-value of A. */
8142 {
8162 /* This case if tricky because we must either have commutative
8163 operators or else A10 must not have side-effects. */
8169 a01);
8170 }
8172 /* See if we can build a range comparison. */
8178 {
8182 }
8186 {
8190 }
8192 /* Check for the possibility of merging component references. If our
8193 lhs is another similar operation, try to merge its rhs with our
8194 rhs. Then try to merge our lhs and rhs. */
8204 && !flag_sanitize_coverage
8209 {
8216 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8217 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8218 We don't want to pack more than two leafs to a non-IF AND/OR
8219 expression.
8220 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8221 equal to IF-CODE, then we don't want to add right-hand operand.
8222 If the inner right-hand side of left-hand operand has
8223 side-effects, or isn't simple, then we can't add to it,
8224 as otherwise we might destroy if-sequence. */
8227 /* Needed for sequence points to handle trappings, and
8228 side-effects. */
8230 {
8232 arg1);
8234 tem);
8235 }
8236 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8237 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8240 /* Needed for sequence points to handle trappings, and
8241 side-effects. */
8243 {
8248 }
8249 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8250 into (A OR B).
8251 For sequence point consistancy, we need to check for trapping,
8252 and side-effects. */
8256 }
8259 }
8261 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8262 by changing CODE to reduce the magnitude of constants involved in
8263 ARG0 of the comparison.
8264 Returns a canonicalized comparison tree if a simplification was
8265 possible, otherwise returns NULL_TREE.
8266 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8267 valid if signed overflow is undefined. */
8269 static tree
8273 {
8278 /* Match A +- CST code arg1. We can change this only if overflow
8279 is undefined. */
8282 /* In principle pointers also have undefined overflow behavior,
8283 but that causes problems elsewhere. */
8290 /* Identify the constant in arg0 and its sign. */
8294 /* Overflowed constants and zero will cause problems. */
8299 /* See if we can reduce the magnitude of the constant in
8300 arg0 by changing the comparison code. */
8301 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8305 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8309 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8313 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8317 else
8321 /* Now build the constant reduced in magnitude. But not if that
8322 would produce one outside of its types range. */
8338 }
8340 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8341 overflow further. Try to decrease the magnitude of constants involved
8342 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8343 and put sole constants at the second argument position.
8344 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8346 static tree
8349 {
8350 tree t;
8355 /* Try canonicalization by simplifying arg0. */
8360 {
8364 }
8366 /* Try canonicalization by simplifying arg1 using the swapped
8367 comparison. */
8375 }
8377 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8378 space. This is used to avoid issuing overflow warnings for
8379 expressions like &p->x which can not wrap. */
8381 static bool
8383 {
8390 poly_wide_int wi_offset;
8396 else
8401 precision);
8416 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8417 array. */
8426 }
8428 /* Return a positive integer when the symbol DECL is known to have
8429 a nonzero address, zero when it's known not to (e.g., it's a weak
8430 symbol), and a negative integer when the symbol is not yet in the
8431 symbol table and so whether or not its address is zero is unknown.
8432 For function local objects always return positive integer. */
8433 static int
8435 {
8440 /* Function local objects are never NULL. */
8448 }
8450 /* Subroutine of fold_binary. This routine performs all of the
8451 transformations that are common to the equality/inequality
8452 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8453 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8454 fold_binary should call fold_binary. Fold a comparison with
8455 tree code CODE and type TYPE with operands OP0 and OP1. Return
8456 the folded comparison or NULL_TREE. */
8458 static tree
8461 {
8471 /* For comparisons of pointers we can decompose it to a compile time
8472 comparison of the base objects and the offsets into the object.
8473 This requires at least one operand being an ADDR_EXPR or a
8474 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8480 {
8483 machine_mode mode;
8487 /* Get base and offset for the access. Strip ADDR_EXPR for
8488 get_inner_reference, but put it back by stripping INDIRECT_REF
8489 off the base object if possible. indirect_baseN will be true
8490 if baseN is not an address but refers to the object itself. */
8493 {
8494 base0
8500 else
8502 }
8504 {
8508 {
8509 base0
8515 else
8517 }
8520 else
8524 {
8531 }
8532 }
8536 {
8537 base1
8543 else
8545 }
8547 {
8551 {
8552 base1
8558 else
8560 }
8563 else
8567 {
8574 }
8575 }
8577 /* If we have equivalent bases we might be able to simplify. */
8581 {
8582 /* We can fold this expression to a constant if the non-constant
8583 offset parts are equal. */
8587 && (equality_code
8588 || (indirect_base0
8591 {
8597 "occur when comparing P +- C1 with "
8599 WARN_STRICT_OVERFLOW_CONDITIONAL);
8602 {
8640 }
8641 }
8642 /* We can simplify the comparison to a comparison of the variable
8643 offset parts if the constant offset parts are equal.
8644 Be careful to use signed sizetype here because otherwise we
8645 mess with array offsets in the wrong way. This is possible
8646 because pointer arithmetic is restricted to retain within an
8647 object and overflow on pointer differences is undefined as of
8648 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8650 && (equality_code
8651 || (indirect_base0
8654 {
8655 /* By converting to signed sizetype we cover middle-end pointer
8656 arithmetic which operates on unsigned pointer types of size
8657 type size and ARRAY_REF offsets which are properly sign or
8658 zero extended from their type in case it is narrower than
8659 sizetype. */
8662 else
8666 else
8673 "occur when comparing P +- C1 with "
8675 WARN_STRICT_OVERFLOW_COMPARISON);
8678 }
8679 }
8680 /* For equal offsets we can simplify to a comparison of the
8681 base addresses. */
8683 && (indirect_base0
8685 && (indirect_base1
8690 {
8696 }
8697 /* Comparison between an ordinary (non-weak) symbol and a null
8698 pointer can be eliminated since such symbols must have a non
8699 null address. In C, relational expressions between pointers
8700 to objects and null pointers are undefined. The results
8701 below follow the C++ rules with the additional property that
8702 every object pointer compares greater than a null pointer.
8703 */
8706 /* Avoid folding references to struct members at offset 0 to
8707 prevent tests like '&ptr->firstmember == 0' from getting
8708 eliminated. When ptr is null, although the -> expression
8709 is strictly speaking invalid, GCC retains it as a matter
8710 of QoI. See PR c/44555. */
8713 && indirect_base0
8714 /* The caller guarantees that when one of the arguments is
8715 constant (i.e., null in this case) it is second. */
8717 {
8719 {
8730 }
8731 }
8732 }
8734 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8735 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8736 the resulting offset is smaller in absolute value than the
8737 original one and has the same sign. */
8746 {
8751 tree cst;
8753 "occur when combining constants around "
8756 /* Put the constant on the side where it doesn't overflow and is
8757 of lower absolute value and of same sign than before. */
8764 {
8767 variable1,
8771 }
8779 {
8785 variable2);
8786 }
8787 }
8793 /* If we are comparing an expression that just has comparisons
8794 of two integer values, arithmetic expressions of those comparisons,
8795 and constants, we can simplify it. There are only three cases
8796 to check: the two values can either be equal, the first can be
8797 greater, or the second can be greater. Fold the expression for
8798 those three values. Since each value must be 0 or 1, we have
8799 eight possibilities, each of which corresponds to the constant 0
8800 or 1 or one of the six possible comparisons.
8802 This handles common cases like (a > b) == 0 but also handles
8803 expressions like ((x > y) - (y > x)) > 0, which supposedly
8804 occur in macroized code. */
8807 {
8811 /* Don't handle degenerate cases here; they should already
8812 have been handled anyway. */
8821 {
8825 /* We can't just pass T to eval_subst in case cval1 or cval2
8826 was the same as ARG1. */
8828 tree high_result
8832 arg1);
8833 tree equal_result
8837 arg1);
8838 tree low_result
8842 arg1);
8844 /* All three of these results should be 0 or 1. Confirm they are.
8845 Then use those values to select the proper code to use. */
8850 {
8851 /* Make a 3-bit mask with the high-order bit being the
8852 value for `>', the next for '=', and the low for '<'. */
8856 {
8858 /* Always false. */
8879 /* Always true. */
8881 }
8884 }
8885 }
8886 }
8889 }
8892 /* Subroutine of fold_binary. Optimize complex multiplications of the
8893 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8894 argument EXPR represents the expression "z" of type TYPE. */
8896 static tree
8898 {
8903 {
8906 }
8908 {
8911 }
8912 else
8913 {
8917 }
8926 }
8929 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8930 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8931 true if successful. */
8933 static bool
8935 {
8940 {
8943 }
8945 {
8951 else
8953 }
8954 else
8960 }
8962 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8963 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8964 NULL_TREE otherwise. */
8966 static tree
8968 {
8989 {
8990 HOST_WIDE_INT index;
8996 }
8999 {
9005 }
9006 else
9008 }
9010 /* Try to fold a pointer difference of type TYPE two address expressions of
9011 array references AREF0 and AREF1 using location LOC. Return a
9012 simplified expression for the difference or NULL_TREE. */
9014 static tree
9018 {
9023 /* If the bases are array references as well, recurse. If the bases
9024 are pointer indirections compute the difference of the pointers.
9025 If the bases are equal, we are set. */
9028 && (base_offset
9030 use_pointer_diff)))
9033 && (base_offset
9034 = use_pointer_diff
9044 {
9050 base_offset,
9053 }
9055 }
9057 /* If the real or vector real constant CST of type TYPE has an exact
9058 inverse, return it, else return NULL. */
9060 tree
9062 {
9063 REAL_VALUE_TYPE r;
9064 tree unit_type;
9065 machine_mode mode;
9068 {
9078 {
9082 tree_vector_builder elts;
9087 {
9092 }
9095 }
9099 }
9100 }
9102 /* Mask out the tz least significant bits of X of type TYPE where
9103 tz is the number of trailing zeroes in Y. */
9104 static wide_int
9106 {
9111 }
9113 /* Return true when T is an address and is known to be nonzero.
9114 For floating point we further ensure that T is not denormal.
9115 Similar logic is present in nonzero_address in rtlanal.h.
9117 If the return value is based on the assumption that signed overflow
9118 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9119 change *STRICT_OVERFLOW_P. */
9121 static bool
9123 {
9127 /* Doing something useful for floating point would need more work. */
9133 {
9136 strict_overflow_p);
9142 strict_overflow_p);
9150 }
9153 {
9156 strict_overflow_p);
9164 strict_overflow_p);
9179 strict_overflow_p);
9183 strict_overflow_p);
9186 {
9198 }
9202 }
9204 }
9206 /* Return true when T is an address and is known to be nonzero.
9207 Handle warnings about undefined signed overflow. */
9209 bool
9211 {
9218 "determining that expression is always "
9220 WARN_STRICT_OVERFLOW_MISC);
9222 }
9224 /* Return true if T is known not to be equal to an integer W. */
9226 bool
9228 {
9230 value_range_type rtype;
9232 {
9241 {
9246 }
9251 /* If T has some known zero bits and W has any of those bits set,
9252 then T is known not to be equal to W. */
9260 }
9261 }
9263 /* Fold a binary expression of code CODE and type TYPE with operands
9264 OP0 and OP1. LOC is the location of the resulting expression.
9265 Return the folded expression if folding is successful. Otherwise,
9266 return NULL_TREE. */
9268 tree
9271 {
9286 /* Strip any conversions that don't change the mode. This is
9287 safe for every expression, except for a comparison expression
9288 because its signedness is derived from its operands. So, in
9289 the latter case, only strip conversions that don't change the
9290 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9291 preserved.
9293 Note that this is done as an internal manipulation within the
9294 constant folder, in order to find the simplest representation
9295 of the arguments so that their form can be studied. In any
9296 cases, the appropriate type conversions should be put back in
9297 the tree that will get out of the constant folder. */
9300 {
9303 }
9304 else
9305 {
9308 }
9310 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9311 constant but we can't do arithmetic on them. */
9313 {
9316 {
9320 }
9321 }
9323 /* If this is a commutative operation, and ARG0 is a constant, move it
9324 to ARG1 to reduce the number of tests below. */
9329 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9330 to ARG1 to reduce the number of tests below. */
9339 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9341 First check for cases where an arithmetic operation is applied to a
9342 compound, conditional, or comparison operation. Push the arithmetic
9343 operation inside the compound or conditional to see if any folding
9344 can then be done. Convert comparison to conditional for this purpose.
9345 The also optimizes non-constant cases that used to be done in
9346 expand_expr.
9348 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9349 one of the operands is a comparison and the other is a comparison, a
9350 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9351 code below would make the expression more complex. Change it to a
9352 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9353 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9366 {
9370 boolean_type_node,
9378 }
9382 {
9384 {
9389 tem);
9390 }
9392 {
9397 tem);
9398 }
9403 {
9409 }
9414 {
9420 }
9421 }
9424 {
9426 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9429 {
9435 }
9437 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9440 {
9441 tree base;
9442 poly_int64 coffset;
9451 }
9456 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9462 arg1),
9464 arg0)));
9470 {
9471 /* X + (X / CST) * -CST is X % CST. */
9476 {
9485 cst0));
9486 }
9487 }
9489 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9490 one. Make sure the type is not saturating and has the signedness of
9491 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9492 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9499 {
9503 }
9506 {
9507 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9508 (plus (plus (mult) (mult)) (foo)) so that we can
9509 take advantage of the factoring cases below. */
9518 {
9524 else
9537 parg0),
9539 marg)),
9543 return
9549 parg1)));
9550 }
9551 }
9552 else
9553 {
9554 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9555 to __complex__ ( x, y ). This is not the same for SNaNs or
9556 if signed zeros are involved. */
9560 {
9567 {
9571 {
9577 }
9579 {
9585 }
9586 }
9587 }
9589 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9590 We associate floats only if the user has specified
9591 -fassociative-math. */
9595 {
9600 {
9601 tree tree0;
9604 }
9605 }
9606 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9607 We associate floats only if the user has specified
9608 -fassociative-math. */
9612 {
9617 {
9618 tree tree0;
9621 }
9622 }
9623 }
9625 bit_rotate:
9626 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9627 is a rotate of A by C1 bits. */
9628 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9629 is a rotate of A by B bits.
9630 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9631 though in this case CODE must be | and not + or ^, otherwise
9632 it doesn't return A when B is 0. */
9633 {
9635 tree rtype;
9644 /* Only create rotates in complete modes. Other cases are not
9645 expanded properly. */
9648 {
9661 {
9666 }
9671 {
9674 code0 == LSHIFT_EXPR
9677 }
9679 {
9689 {
9693 orig_tree01);
9695 }
9696 }
9700 {
9711 {
9715 orig_tree01);
9717 }
9718 }
9719 }
9720 }
9722 associate:
9723 /* In most languages, can't associate operations on floats through
9724 parentheses. Rather than remember where the parentheses were, we
9725 don't associate floats at all, unless the user has specified
9726 -fassociative-math.
9727 And, we need to make sure type is not saturating. */
9731 {
9737 /* Split both trees into variables, constants, and literals. Then
9738 associate each group together, the constants with literals,
9739 then the result with variables. This increases the chances of
9740 literals being recombined later and of generating relocatable
9741 expressions for the sum of a constant and literal. */
9749 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9753 /* With undefined overflow prefer doing association in a type
9754 which wraps on overflow, if that is one of the operand types. */
9757 {
9765 }
9767 /* With undefined overflow we can only associate constants with one
9768 variable, and constants whose association doesn't overflow. */
9771 {
9773 {
9774 /* ??? If split_tree would handle NEGATE_EXPR we could
9775 simply reject these cases and the allowed cases would
9776 be the var0/minus_var1 ones. */
9782 {
9785 }
9792 {
9795 }
9801 /* The only case we can still associate with two variables
9802 is if they cancel out. */
9806 }
9812 }
9814 /* Only do something if we found more than two objects. Otherwise,
9815 nothing has changed and we risk infinite recursion. */
9823 {
9835 {
9839 }
9841 {
9845 }
9847 /* Preserve the MINUS_EXPR if the negative part of the literal is
9848 greater than the positive part. Otherwise, the multiplicative
9849 folding code (i.e extract_muldiv) may be fooled in case
9850 unsigned constants are subtracted, like in the following
9851 example: ((X*2 + 4) - 8U)/2. */
9853 {
9857 /* But avoid ending up with only negated parts. */
9859 {
9863 }
9864 else
9865 {
9869 }
9870 }
9872 /* Don't introduce overflows through reassociation. */
9877 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9884 /* Eliminate minus_con0. */
9886 {
9893 else
9896 }
9898 /* Eliminate minus_var0. */
9900 {
9904 else
9907 }
9909 return
9912 }
9913 }
9919 /* Fold &a[i] - &a[j] to i-j. */
9924 {
9928 code
9932 }
9934 /* Further transformations are not for pointers. */
9938 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9941 /* If arg0 is e.g. unsigned int and type is int, then this could
9942 introduce UB, because if A is INT_MIN at runtime, the original
9943 expression can be well defined while the latter is not.
9944 See PR83269. */
9953 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9954 __complex__ ( x, -y ). This is not the same for SNaNs or if
9955 signed zeros are involved. */
9959 {
9966 {
9970 {
9972 arg1r ? arg1r
9977 }
9979 {
9983 arg1i ? arg1i
9986 }
9987 }
9988 }
9990 /* A - B -> A + (-B) if B is easily negatable. */
9994 /* Avoid this transformation if B is a positive REAL_CST. */
10002 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10003 one. Make sure the type is not saturating and has the signedness of
10004 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10005 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10012 {
10016 }
10022 {
10023 /* Transform x * -C into -x * C if x is easily negatable. */
10038 {
10041 "occur when simplifying "
10043 WARN_STRICT_OVERFLOW_MISC);
10045 }
10047 /* Optimize z * conj(z) for integer complex numbers. */
10054 }
10055 else
10056 {
10057 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10058 This is not the same for NaNs or if signed zeros are
10059 involved. */
10065 {
10068 return
10074 return
10079 }
10081 /* Optimize z * conj(z) for floating point complex numbers.
10082 Guarded by flag_unsafe_math_optimizations as non-finite
10083 imaginary components don't produce scalar results. */
10092 }
10096 /* Canonicalize (X & C1) | C2. */
10100 {
10105 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10113 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10115 {
10118 }
10120 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10121 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10122 mode which allows further optimizations. */
10127 {
10132 {
10135 }
10136 }
10139 {
10144 }
10145 }
10147 /* See if this can be simplified into a rotate first. If that
10148 is unsuccessful continue in the association code. */
10152 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10160 /* See if this can be simplified into a rotate first. If that
10161 is unsuccessful continue in the association code. */
10165 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10170 {
10171 tree tem2;
10178 }
10179 /* Fold ~X & 1 as (X & 1) == 0. */
10183 {
10184 tree tem2;
10191 }
10192 /* Fold !X & 1 as X == 0. */
10195 {
10199 }
10201 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10202 multiple of 1 << CST. */
10204 {
10211 }
10213 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10214 bits from CST2. */
10218 {
10220 wide_int masked
10227 {
10228 /* Avoid the transform if arg1 is a mask of some
10229 mode which allows further optimizations. */
10236 }
10237 }
10239 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10242 {
10247 return
10249 }
10254 /* Don't touch a floating-point divide by zero unless the mode
10255 of the constant can represent infinity. */
10261 /* (-A) / (-B) -> A / B */
10273 /* Fall through */
10276 /* Simplify A / (B << N) where A and B are positive and B is
10277 a power of 2, to A >> (N + log2(B)). */
10282 {
10285 {
10293 WARN_STRICT_OVERFLOW_MISC);
10299 }
10300 }
10302 /* Fall through */
10310 /* Convert -A / -B to A / B when the type is signed and overflow is
10311 undefined. */
10315 {
10318 "when distributing negation across "
10320 WARN_STRICT_OVERFLOW_MISC);
10325 }
10329 {
10332 "when distributing negation across "
10334 WARN_STRICT_OVERFLOW_MISC);
10339 }
10341 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10342 operation, EXACT_DIV_EXPR.
10344 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10345 At one time others generated faster code, it's not clear if they do
10346 after the last round to changes to the DIV code in expmed.c. */
10357 {
10361 WARN_STRICT_OVERFLOW_MISC);
10363 }
10375 {
10379 WARN_STRICT_OVERFLOW_MISC);
10381 }
10389 /* Since negative shift count is not well-defined,
10390 don't try to compute it in the compiler. */
10396 /* If we have a rotate of a bit operation with the rotate count and
10397 the second operand of the bit operation both constant,
10398 permute the two operations. */
10404 {
10412 }
10414 /* Two consecutive rotates adding up to the some integer
10415 multiple of the precision of the type can be ignored. */
10431 /* Note that the operands of this must be ints
10432 and their values must be 0 or 1.
10433 ("true" is a fixed value perhaps depending on the language.) */
10434 /* If first arg is constant zero, return it. */
10437 /* FALLTHRU */
10439 /* If either arg is constant true, drop it. */
10443 /* Preserve sequence points. */
10446 /* If second arg is constant zero, result is zero, but first arg
10447 must be evaluated. */
10450 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10451 case will be handled here. */
10455 /* !X && X is always false. */
10459 /* X && !X is always false. */
10464 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10465 means A >= Y && A != MAX, but in this case we know that
10466 A < X <= MAX. */
10470 {
10478 }
10487 /* Note that the operands of this must be ints
10488 and their values must be 0 or true.
10489 ("true" is a fixed value perhaps depending on the language.) */
10490 /* If first arg is constant true, return it. */
10493 /* FALLTHRU */
10495 /* If either arg is constant zero, drop it. */
10499 /* Preserve sequence points. */
10502 /* If second arg is constant true, result is true, but we must
10503 evaluate first arg. */
10506 /* Likewise for first arg, but note this only occurs here for
10507 TRUTH_OR_EXPR. */
10511 /* !X || X is always true. */
10515 /* X || !X is always true. */
10520 /* (X && !Y) || (!X && Y) is X ^ Y */
10523 {
10540 }
10549 /* If the second arg is constant zero, drop it. */
10552 /* If the second arg is constant true, this is a logical inversion. */
10554 {
10557 }
10558 /* Identical arguments cancel to zero. */
10562 /* !X ^ X is always true. */
10567 /* X ^ !X is always true. */
10583 /* bool_var != 1 becomes !bool_var. */
10590 /* bool_var == 0 becomes !bool_var. */
10597 /* !exp != 0 becomes !exp */
10602 /* If this is an EQ or NE comparison with zero and ARG0 is
10603 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10604 two operations, but the latter can be done in one less insn
10605 on machines that have only two-operand insns or on which a
10606 constant cannot be the first operand. */
10609 {
10614 {
10621 arg1);
10622 }
10625 {
10632 arg1);
10633 }
10634 }
10636 /* If this is an NE or EQ comparison of zero against the result of a
10637 signed MOD operation whose second operand is a power of 2, make
10638 the MOD operation unsigned since it is simpler and equivalent. */
10646 {
10656 }
10658 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10659 C1 is a valid shift constant, and C2 is a power of two, i.e.
10660 a single bit. */
10664 == INTEGER_CST
10667 {
10672 /* Check for a valid shift count. */
10674 {
10678 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10679 can be rewritten as (X & (C2 << C1)) != 0. */
10681 {
10686 }
10687 /* Otherwise, for signed (arithmetic) shifts,
10688 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10689 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10693 /* Otherwise, of unsigned (logical) shifts,
10694 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10695 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10696 else
10700 arg000);
10701 }
10702 }
10704 /* If this is a comparison of a field, we may be able to simplify it. */
10707 /* Handle the constant case even without -O
10708 to make sure the warnings are given. */
10710 {
10714 }
10716 /* Optimize comparisons of strlen vs zero to a compare of the
10717 first character of the string vs zero. To wit,
10718 strlen(ptr) == 0 => *ptr == 0
10719 strlen(ptr) != 0 => *ptr != 0
10720 Other cases should reduce to one of these two (or a constant)
10721 due to the return value of strlen being unsigned. */
10724 {
10732 {
10737 }
10738 }
10740 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10741 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10745 {
10750 {
10752 {
10755 }
10758 }
10759 }
10761 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10762 (X & C) == 0 when C is a single bit. */
10767 {
10774 arg1));
10775 }
10777 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10778 constant C is a power of two, i.e. a single bit. */
10785 {
10789 }
10791 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10792 when is C is a power of two, i.e. a single bit. */
10799 {
10805 }
10809 {
10812 }
10814 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10817 {
10825 {
10831 }
10833 {
10839 }
10841 {
10847 }
10849 {
10855 }
10856 }
10860 {
10867 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10868 operand_equal_p guarantees no side-effects so we don't need
10869 to use omit_one_operand on Z. */
10873 arg10));
10877 arg11));
10881 arg10));
10885 arg11));
10887 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10890 {
10896 }
10897 }
10899 /* Attempt to simplify equality/inequality comparisons of complex
10900 values. Only lower the comparison if the result is known or
10901 can be simplified to a single scalar comparison. */
10906 {
10911 {
10914 }
10915 else
10916 {
10919 }
10922 {
10925 }
10926 else
10927 {
10930 }
10934 {
10936 {
10941 }
10942 else
10943 {
10948 }
10949 }
10953 {
10955 {
10960 }
10961 else
10962 {
10967 }
10968 }
10969 }
10981 /* Transform comparisons of the form X +- C CMP X. */
10986 {
10991 /* (X - c) > X becomes false. */
10997 /* Likewise (X + c) < X becomes false. */
11003 /* Convert (X - c) <= X to true. */
11010 /* Convert (X + c) >= X to true. */
11016 }
11018 /* If we are comparing an ABS_EXPR with a constant, we can
11019 convert all the cases into explicit comparisons, but they may
11020 well not be faster than doing the ABS and one comparison.
11021 But ABS (X) <= C is a range comparison, which becomes a subtraction
11022 and a comparison, and is probably faster. */
11036 /* Convert ABS_EXPR<x> >= 0 to true. */
11043 {
11046 "when simplifying comparison of "
11048 WARN_STRICT_OVERFLOW_CONDITIONAL);
11051 arg0);
11052 }
11054 /* Convert ABS_EXPR<x> < 0 to false. */
11059 {
11062 "when simplifying comparison of "
11064 WARN_STRICT_OVERFLOW_CONDITIONAL);
11067 arg0);
11068 }
11070 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11071 and similarly for >= into !=. */
11081 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11082 otherwise Y might be >= # of bits in X's type and thus e.g.
11083 (unsigned char) (1 << Y) for Y 15 might be 0.
11084 If the cast is widening, then 1 << Y should have unsigned type,
11085 otherwise if Y is number of bits in the signed shift type minus 1,
11086 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11087 31 might be 0xffffffff80000000. */
11098 {
11104 }
11116 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11117 {
11129 }
11134 /* When pedantic, a compound expression can be neither an lvalue
11135 nor an integer constant expression. */
11138 /* Don't let (0, 0) be null pointer constant. */
11144 /* An ASSERT_EXPR should never be passed to fold_binary. */
11150 }
11152 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11153 ((A & N) + B) & M -> (A + B) & M
11154 Similarly if (N & M) == 0,
11155 ((A | N) + B) & M -> (A + B) & M
11156 and for - instead of + (or unary - instead of +)
11157 and/or ^ instead of |.
11158 If B is constant and (B & M) == 0, fold into A & M.
11160 This function is a helper for match.pd patterns. Return non-NULL
11161 type in which the simplified operation should be performed only
11162 if any optimization is possible.
11164 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11165 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11166 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11167 +/-. */
11168 tree
11173 {
11188 wide_int cst0;
11190 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11191 arg1 (M) is == (1LL << cst) - 1.
11192 Store C into PMOP[0] and D into PMOP[1]. */
11199 {
11206 {
11209 }
11212 /* If C or D is of the form (A & N) where
11213 (N & M) == M, or of the form (A | N) or
11214 (A ^ N) where (N & M) == 0, replace it with A. */
11220 /* If C or D is a N where (N & M) == 0, it can be
11221 omitted (replaced with 0). */
11226 /* Similarly, with C - N where (-N & M) == 0. */
11234 }
11236 /* Only build anything new if we optimized one or both arguments above. */
11242 else
11244 }
11246 /* Used by contains_label_[p1]. */
11248 struct contains_label_data
11249 {
11252 };
11254 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11255 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11256 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11258 static tree
11260 {
11263 {
11274 {
11282 }
11291 }
11292 }
11294 /* Return whether the sub-tree ST contains a label which is accessible from
11295 outside the sub-tree. */
11297 static bool
11299 {
11303 }
11305 /* Fold a ternary expression of code CODE and type TYPE with operands
11306 OP0, OP1, and OP2. Return the folded expression if folding is
11307 successful. Otherwise, return NULL_TREE. */
11309 tree
11312 {
11313 tree tem;
11320 /* If this is a commutative operation, and OP0 is a constant, move it
11321 to OP1 to reduce the number of tests below. */
11330 /* Strip any conversions that don't change the mode. This is safe
11331 for every expression, except for a comparison expression because
11332 its signedness is derived from its operands. So, in the latter
11333 case, only strip conversions that don't change the signedness.
11335 Note that this is done as an internal manipulation within the
11336 constant folder, in order to find the simplest representation of
11337 the arguments so that their form can be studied. In any cases,
11338 the appropriate type conversions should be put back in the tree
11339 that will get out of the constant folder. */
11341 {
11344 }
11347 {
11350 }
11353 {
11356 }
11359 {
11363 {
11369 }
11374 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11375 so all simple results must be passed through pedantic_non_lvalue. */
11377 {
11380 /* Only optimize constant conditions when the selected branch
11381 has the same type as the COND_EXPR. This avoids optimizing
11382 away "c ? x : throw", where the throw has a void type.
11383 Avoid throwing away that operand which contains label. */
11390 }
11392 {
11399 {
11402 {
11410 }
11415 }
11416 }
11418 /* If we have A op B ? A : C, we may be able to convert this to a
11419 simpler expression, depending on the operation and the values
11420 of B and C. Signed zeros prevent all of these transformations,
11421 for reasons given above each one.
11423 Also try swapping the arguments and inverting the conditional. */
11427 {
11431 }
11436 {
11440 {
11444 }
11445 }
11447 /* If the second operand is simpler than the third, swap them
11448 since that produces better jump optimization results. */
11451 {
11453 /* See if this can be inverted. If it can't, possibly because
11454 it was a floating-point inequality comparison, don't do
11455 anything. */
11459 }
11461 /* Convert A ? 1 : 0 to simply A. */
11466 /* If we try to convert OP0 to our type, the
11467 call to fold will try to move the conversion inside
11468 a COND, which will recurse. In that case, the COND_EXPR
11469 is probably the best choice, so leave it alone. */
11473 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11474 over COND_EXPR in cases such as floating point comparisons. */
11483 arg0)));
11485 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11490 {
11491 /* sign_bit_p looks through both zero and sign extensions,
11492 but for this optimization only sign extensions are
11493 usable. */
11496 {
11499 {
11502 }
11504 }
11505 /* sign_bit_p only checks ARG1 bits within A's precision.
11506 If <sign bit of A> has wider type than A, bits outside
11507 of A's precision in <sign bit of A> need to be checked.
11508 If they are all 0, this optimization needs to be done
11509 in unsigned A's type, if they are all 1 in signed A's type,
11510 otherwise this can't be done. */
11516 {
11518 tree tem_type;
11531 {
11534 }
11536 {
11539 }
11540 else
11542 }
11545 return
11551 arg1)));
11552 }
11554 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11555 already handled above. */
11560 {
11570 op1);
11571 }
11573 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11574 is probably obsolete because the first operand should be a
11575 truth value (that's why we have the two cases above), but let's
11576 leave it in until we can confirm this for all front-ends. */
11588 /* Disable the transformations below for vectors, since
11589 fold_binary_op_with_conditional_arg may undo them immediately,
11590 yielding an infinite loop. */
11594 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11603 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11608 {
11610 /* Only perform transformation if ARG0 is easily inverted. */
11614 ? BIT_IOR_EXPR
11617 op1);
11618 }
11620 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11625 {
11627 /* Only perform transformation if ARG0 is easily inverted. */
11633 op2);
11634 }
11636 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11648 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11649 of fold_ternary on them. */
11659 {
11670 {
11675 {
11677 {
11682 }
11688 }
11689 }
11690 }
11692 /* On constants we can use native encode/interpret to constant
11693 fold (nearly) all BIT_FIELD_REFs. */
11699 {
11702 /* Limit us to a reasonable amount of work. To relax the
11703 other limitations we need bit-shifting of the buffer
11704 and rounding up the size. */
11708 {
11710 unsigned HOST_WIDE_INT len
11715 {
11720 }
11721 }
11722 }
11728 {
11729 /* Build a vector of integers from the tree mask. */
11730 vec_perm_builder builder;
11734 /* Create a vec_perm_indices for the integer vector. */
11739 /* Check for cases that fold to OP0 or OP1 in their original
11740 element order. */
11747 {
11751 {
11754 }
11755 }
11761 {
11765 }
11769 /* Generate a canonical form of the selector. */
11771 {
11772 /* Some targets are deficient and fail to expand a single
11773 argument permutation while still allowing an equivalent
11774 2-argument version. */
11778 else
11779 {
11783 else
11784 /* Not directly supported with either encoding,
11785 so use the preferred form. */
11787 }
11789 }
11793 }
11797 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11800 {
11806 wide_int tem2
11810 }
11815 {
11817 unsigned HOST_WIDE_INT elsize
11820 {
11826 {
11832 }
11833 }
11834 }
11840 }
11842 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11843 of an array (or vector). */
11845 tree
11847 {
11852 {
11855 {
11856 /* Static constructors for variably sized objects makes no sense. */
11860 }
11861 }
11872 offset_int max_index;
11877 {
11878 /* Array constructor might explicitly set index, or specify a range,
11879 or leave index NULL meaning that it is next index after previous
11880 one. */
11882 {
11885 else
11886 {
11890 }
11891 }
11892 else
11893 {
11899 }
11901 /* Do we have match? */
11905 }
11907 }
11909 /* Perform constant folding and related simplification of EXPR.
11910 The related simplifications include x*1 => x, x*0 => 0, etc.,
11911 and application of the associative law.
11912 NOP_EXPR conversions may be removed freely (as long as we
11913 are careful not to change the type of the overall expression).
11914 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11915 but we can constant-fold them if they have constant operands. */
11917 #ifdef ENABLE_FOLD_CHECKING
11918 # define fold(x) fold_1 (x)
11920 static
11921 #endif
11922 tree
11924 {
11928 tree tem;
11931 /* Return right away if a constant. */
11935 /* CALL_EXPR-like objects with variable numbers of operands are
11936 treated specially. */
11938 {
11940 {
11943 }
11945 }
11948 {
11953 {
11971 }
11972 }
11975 {
11977 {
11984 {
11989 }
11992 }
11994 /* Return a VECTOR_CST if possible. */
11996 {
12002 tree val;
12008 }
12016 }
12018 #ifdef ENABLE_FOLD_CHECKING
12019 #undef fold
12026 /* When --enable-checking=fold, compute a digest of expr before
12027 and after actual fold call to see if fold did not accidentally
12028 change original expr. */
12030 tree
12032 {
12033 tree ret;
12053 }
12055 void
12057 {
12068 }
12070 static void
12072 {
12074 }
12076 static void
12079 {
12085 recursive_label:
12095 {
12096 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12101 }
12109 {
12110 /* Allow these fields to be modified. */
12111 tree tmp;
12120 {
12123 }
12124 }
12135 {
12138 {
12154 }
12158 {
12171 }
12188 {
12194 }
12197 {
12199 {
12202 }
12204 }
12215 {
12218 }
12228 }
12229 }
12231 /* Helper function for outputting the checksum of a tree T. When
12232 debugging with gdb, you can "define mynext" to be "next" followed
12233 by "call debug_fold_checksum (op0)", then just trace down till the
12234 outputs differ. */
12236 DEBUG_FUNCTION void
12238 {
12253 }
12255 #endif
12257 /* Fold a unary tree expression with code CODE of type TYPE with an
12258 operand OP0. LOC is the location of the resulting expression.
12259 Return a folded expression if successful. Otherwise, return a tree
12260 expression with code CODE of type TYPE with an operand OP0. */
12262 tree
12265 {
12266 tree tem;
12267 #ifdef ENABLE_FOLD_CHECKING
12276 #endif
12282 #ifdef ENABLE_FOLD_CHECKING
12289 #endif
12291 }
12293 /* Fold a binary tree expression with code CODE of type TYPE with
12294 operands OP0 and OP1. LOC is the location of the resulting
12295 expression. Return a folded expression if successful. Otherwise,
12296 return a tree expression with code CODE of type TYPE with operands
12297 OP0 and OP1. */
12299 tree
12302 MEM_STAT_DECL)
12303 {
12304 tree tem;
12305 #ifdef ENABLE_FOLD_CHECKING
12322 #endif
12328 #ifdef ENABLE_FOLD_CHECKING
12343 #endif
12345 }
12347 /* Fold a ternary tree expression with code CODE of type TYPE with
12348 operands OP0, OP1, and OP2. Return a folded expression if
12349 successful. Otherwise, return a tree expression with code CODE of
12350 type TYPE with operands OP0, OP1, and OP2. */
12352 tree
12355 {
12356 tree tem;
12357 #ifdef ENABLE_FOLD_CHECKING
12381 #endif
12388 #ifdef ENABLE_FOLD_CHECKING
12411 #endif
12413 }
12415 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12416 arguments in ARGARRAY, and a null static chain.
12417 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12418 of type TYPE from the given operands as constructed by build_call_array. */
12420 tree
12423 {
12424 tree tem;
12425 #ifdef ENABLE_FOLD_CHECKING
12444 #endif
12450 #ifdef ENABLE_FOLD_CHECKING
12466 #endif
12468 }
12470 /* Perform constant folding and related simplification of initializer
12471 expression EXPR. These behave identically to "fold_buildN" but ignore
12472 potential run-time traps and exceptions that fold must preserve. */
12474 #define START_FOLD_INIT \
12475 int saved_signaling_nans = flag_signaling_nans;\
12476 int saved_trapping_math = flag_trapping_math;\
12477 int saved_rounding_math = flag_rounding_math;\
12478 int saved_trapv = flag_trapv;\
12479 int saved_folding_initializer = folding_initializer;\
12480 flag_signaling_nans = 0;\
12481 flag_trapping_math = 0;\
12482 flag_rounding_math = 0;\
12483 flag_trapv = 0;\
12484 folding_initializer = 1;
12486 #define END_FOLD_INIT \
12487 flag_signaling_nans = saved_signaling_nans;\
12488 flag_trapping_math = saved_trapping_math;\
12489 flag_rounding_math = saved_rounding_math;\
12490 flag_trapv = saved_trapv;\
12491 folding_initializer = saved_folding_initializer;
12493 tree
12496 {
12497 tree result;
12498 START_FOLD_INIT;
12502 END_FOLD_INIT;
12504 }
12506 tree
12509 {
12510 tree result;
12511 START_FOLD_INIT;
12515 END_FOLD_INIT;
12517 }
12519 tree
12522 {
12523 tree result;
12524 START_FOLD_INIT;
12528 END_FOLD_INIT;
12530 }
12532 #undef START_FOLD_INIT
12533 #undef END_FOLD_INIT
12535 /* Determine if first argument is a multiple of second argument. Return 0 if
12536 it is not, or we cannot easily determined it to be.
12538 An example of the sort of thing we care about (at this point; this routine
12539 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12540 fold cases do now) is discovering that
12542 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12544 is a multiple of
12546 SAVE_EXPR (J * 8)
12548 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12550 This code also handles discovering that
12552 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12554 is a multiple of 8 so we don't have to worry about dealing with a
12555 possible remainder.
12557 Note that we *look* inside a SAVE_EXPR only to determine how it was
12558 calculated; it is not safe for fold to do much of anything else with the
12559 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12560 at run time. For example, the latter example above *cannot* be implemented
12561 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12562 evaluation time of the original SAVE_EXPR is not necessarily the same at
12563 the time the new expression is evaluated. The only optimization of this
12564 sort that would be valid is changing
12566 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12568 divided by 8 to
12570 SAVE_EXPR (I) * SAVE_EXPR (J)
12572 (where the same SAVE_EXPR (J) is used in the original and the
12573 transformed version). */
12575 int
12577 {
12588 {
12590 /* Bitwise and provides a power of two multiple. If the mask is
12591 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12599 {
12605 {
12608 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12610 {
12614 {
12617 }
12618 }
12620 }
12621 }
12626 /* It is impossible to prove if op0 - op1 is multiple of bottom
12627 precisely, so be conservative here checking if both op0 and op1
12628 are multiple of bottom. Note we check the second operand first
12629 since it's usually simpler. */
12634 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12635 as op0 - 3 if the expression has unsigned type. For example,
12636 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12646 {
12648 /* const_binop may not detect overflow correctly,
12649 so check for it explicitly here. */
12657 }
12661 /* Can't handle conversions from non-integral or wider integral type. */
12667 /* fall through */
12684 SIGNED);
12690 {
12693 /* Check for special cases to see if top is defined as multiple
12694 of bottom:
12696 top = (X & ~(bottom - 1) ; bottom is power of 2
12698 or
12700 Y = X % bottom
12701 top = X - Y. */
12720 }
12722 /* fall through */
12730 }
12731 }
12733 #define tree_expr_nonnegative_warnv_p(X, Y) \
12736 #define RECURSE(X) \
12737 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12739 /* Return true if CODE or TYPE is known to be non-negative. */
12741 static bool
12743 {
12746 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12747 have a signed:1 type (where the value is -1 and 0). */
12750 }
12752 /* Return true if (CODE OP0) is known to be non-negative. If the return
12753 value is based on the assumption that signed overflow is undefined,
12754 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12755 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12757 bool
12760 {
12765 {
12767 /* We can't return 1 if flag_wrapv is set because
12768 ABS_EXPR<INT_MIN> = INT_MIN. */
12772 {
12775 }
12783 CASE_CONVERT:
12784 {
12789 {
12793 {
12797 }
12798 }
12800 {
12806 }
12807 }
12812 }
12814 /* We don't know sign of `t', so be conservative and return false. */
12816 }
12818 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12819 value is based on the assumption that signed overflow is undefined,
12820 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12821 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12823 bool
12827 {
12832 {
12838 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12839 both unsigned and at least 2 bits shorter than the result. */
12843 {
12848 {
12852 }
12853 }
12858 {
12859 /* x * x is always non-negative for floating point x
12860 or without overflow. */
12863 {
12868 }
12869 }
12871 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12872 both unsigned and their total bits is shorter than the result. */
12876 {
12895 {
12905 }
12906 }
12933 }
12935 /* We don't know sign of `t', so be conservative and return false. */
12937 }
12939 /* Return true if T is known to be non-negative. If the return
12940 value is based on the assumption that signed overflow is undefined,
12941 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12942 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12944 bool
12946 {
12951 {
12965 /* Limit the depth of recursion to avoid quadratic behavior.
12966 This is expected to catch almost all occurrences in practice.
12967 If this code misses important cases that unbounded recursion
12968 would not, passes that need this information could be revised
12969 to provide it through dataflow propagation. */
12977 }
12978 }
12980 /* Return true if T is known to be non-negative. If the return
12981 value is based on the assumption that signed overflow is undefined,
12982 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12983 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12985 bool
12988 {
12990 {
12991 CASE_CFN_ACOS:
12992 CASE_CFN_ACOSH:
12993 CASE_CFN_CABS:
12994 CASE_CFN_COSH:
12995 CASE_CFN_ERFC:
12996 CASE_CFN_EXP:
12997 CASE_CFN_EXP10:
12998 CASE_CFN_EXP2:
12999 CASE_CFN_FABS:
13000 CASE_CFN_FDIM:
13001 CASE_CFN_HYPOT:
13002 CASE_CFN_POW10:
13003 CASE_CFN_FFS:
13004 CASE_CFN_PARITY:
13005 CASE_CFN_POPCOUNT:
13006 CASE_CFN_CLZ:
13007 CASE_CFN_CLRSB:
13010 /* Always true. */
13013 CASE_CFN_SQRT:
13014 CASE_CFN_SQRT_FN:
13015 /* sqrt(-0.0) is -0.0. */
13020 CASE_CFN_ASINH:
13021 CASE_CFN_ATAN:
13022 CASE_CFN_ATANH:
13023 CASE_CFN_CBRT:
13024 CASE_CFN_CEIL:
13025 CASE_CFN_CEIL_FN:
13026 CASE_CFN_ERF:
13027 CASE_CFN_EXPM1:
13028 CASE_CFN_FLOOR:
13029 CASE_CFN_FLOOR_FN:
13030 CASE_CFN_FMOD:
13031 CASE_CFN_FREXP:
13032 CASE_CFN_ICEIL:
13033 CASE_CFN_IFLOOR:
13034 CASE_CFN_IRINT:
13035 CASE_CFN_IROUND:
13036 CASE_CFN_LCEIL:
13037 CASE_CFN_LDEXP:
13038 CASE_CFN_LFLOOR:
13039 CASE_CFN_LLCEIL:
13040 CASE_CFN_LLFLOOR:
13041 CASE_CFN_LLRINT:
13042 CASE_CFN_LLROUND:
13043 CASE_CFN_LRINT:
13044 CASE_CFN_LROUND:
13045 CASE_CFN_MODF:
13046 CASE_CFN_NEARBYINT:
13047 CASE_CFN_NEARBYINT_FN:
13048 CASE_CFN_RINT:
13049 CASE_CFN_RINT_FN:
13050 CASE_CFN_ROUND:
13051 CASE_CFN_ROUND_FN:
13052 CASE_CFN_SCALB:
13053 CASE_CFN_SCALBLN:
13054 CASE_CFN_SCALBN:
13055 CASE_CFN_SIGNBIT:
13056 CASE_CFN_SIGNIFICAND:
13057 CASE_CFN_SINH:
13058 CASE_CFN_TANH:
13059 CASE_CFN_TRUNC:
13060 CASE_CFN_TRUNC_FN:
13061 /* True if the 1st argument is nonnegative. */
13064 CASE_CFN_FMAX:
13065 CASE_CFN_FMAX_FN:
13066 /* True if the 1st OR 2nd arguments are nonnegative. */
13069 CASE_CFN_FMIN:
13070 CASE_CFN_FMIN_FN:
13071 /* True if the 1st AND 2nd arguments are nonnegative. */
13074 CASE_CFN_COPYSIGN:
13075 CASE_CFN_COPYSIGN_FN:
13076 /* True if the 2nd argument is nonnegative. */
13079 CASE_CFN_POWI:
13080 /* True if the 1st argument is nonnegative or the second
13081 argument is an even integer. */
13087 CASE_CFN_POW:
13088 /* True if the 1st argument is nonnegative or the second
13089 argument is an even integer valued real. */
13091 {
13092 REAL_VALUE_TYPE c;
13093 HOST_WIDE_INT n;
13098 {
13099 REAL_VALUE_TYPE cint;
13103 }
13104 }
13109 }
13111 }
13113 /* Return true if T is known to be non-negative. If the return
13114 value is based on the assumption that signed overflow is undefined,
13115 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13116 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13118 static bool
13120 {
13126 {
13128 {
13132 /* If the initializer is non-void, then it's a normal expression
13133 that will be assigned to the slot. */
13137 /* Otherwise, the initializer sets the slot in some way. One common
13138 way is an assignment statement at the end of the initializer. */
13140 {
13148 else
13150 }
13156 }
13159 {
13165 arg0,
13166 arg1,
13168 }
13181 }
13182 }
13184 #undef RECURSE
13185 #undef tree_expr_nonnegative_warnv_p
13187 /* Return true if T is known to be non-negative. If the return
13188 value is based on the assumption that signed overflow is undefined,
13189 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13190 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13192 bool
13194 {
13201 {
13223 }
13226 {
13252 }
13253 }
13255 /* Return true if `t' is known to be non-negative. Handle warnings
13256 about undefined signed overflow. */
13258 bool
13260 {
13267 "determining that expression is always "
13269 WARN_STRICT_OVERFLOW_MISC);
13271 }
13274 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13275 For floating point we further ensure that T is not denormal.
13276 Similar logic is present in nonzero_address in rtlanal.h.
13278 If the return value is based on the assumption that signed overflow
13279 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13280 change *STRICT_OVERFLOW_P. */
13282 bool
13285 {
13287 {
13290 strict_overflow_p);
13293 {
13299 strict_overflow_p));
13300 }
13305 strict_overflow_p);
13309 }
13312 }
13314 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13315 For floating point we further ensure that T is not denormal.
13316 Similar logic is present in nonzero_address in rtlanal.h.
13318 If the return value is based on the assumption that signed overflow
13319 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13320 change *STRICT_OVERFLOW_P. */
13322 bool
13324 tree type,
13325 tree op0,
13327 {
13330 {
13334 {
13335 /* With the presence of negative values it is hard
13336 to say something. */
13343 /* One of operands must be positive and the other non-negative. */
13344 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13345 overflows, on a twos-complement machine the sum of two
13346 nonnegative numbers can never be zero. */
13348 strict_overflow_p)
13350 strict_overflow_p));
13351 }
13356 {
13358 strict_overflow_p)
13360 strict_overflow_p))
13361 {
13364 }
13365 }
13374 {
13377 }
13384 {
13388 /* When both operands are nonzero, then MAX must be too. */
13390 strict_overflow_p))
13393 /* MAX where operand 0 is positive is positive. */
13395 strict_overflow_p);
13396 }
13397 /* MAX where operand 1 is positive is positive. */
13402 {
13406 }
13411 strict_overflow_p)
13413 strict_overflow_p));
13417 }
13420 }
13422 /* Return true when T is an address and is known to be nonzero.
13423 For floating point we further ensure that T is not denormal.
13424 Similar logic is present in nonzero_address in rtlanal.h.
13426 If the return value is based on the assumption that signed overflow
13427 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13428 change *STRICT_OVERFLOW_P. */
13430 bool
13432 {
13435 {
13440 {
13452 /* For objects in symbol table check if we know they are non-zero.
13453 Don't do anything for variables and functions before symtab is built;
13454 it is quite possible that they will be declared weak later. */
13459 /* Constants are never weak. */
13464 }
13472 {
13476 }
13486 }
13488 }
13490 #define integer_valued_real_p(X) \
13493 #define RECURSE(X) \
13494 ((integer_valued_real_p) (X, depth + 1))
13496 /* Return true if the floating point result of (CODE OP0) has an
13497 integer value. We also allow +Inf, -Inf and NaN to be considered
13498 integer values. Return false for signaling NaN.
13500 DEPTH is the current nesting depth of the query. */
13502 bool
13504 {
13506 {
13513 CASE_CONVERT:
13514 {
13521 }
13525 }
13527 }
13529 /* Return true if the floating point result of (CODE OP0 OP1) has an
13530 integer value. We also allow +Inf, -Inf and NaN to be considered
13531 integer values. Return false for signaling NaN.
13533 DEPTH is the current nesting depth of the query. */
13535 bool
13537 {
13539 {
13549 }
13551 }
13553 /* Return true if the floating point result of calling FNDECL with arguments
13554 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13555 considered integer values. Return false for signaling NaN. If FNDECL
13556 takes fewer than 2 arguments, the remaining ARGn are null.
13558 DEPTH is the current nesting depth of the query. */
13560 bool
13562 {
13564 {
13565 CASE_CFN_CEIL:
13566 CASE_CFN_CEIL_FN:
13567 CASE_CFN_FLOOR:
13568 CASE_CFN_FLOOR_FN:
13569 CASE_CFN_NEARBYINT:
13570 CASE_CFN_NEARBYINT_FN:
13571 CASE_CFN_RINT:
13572 CASE_CFN_RINT_FN:
13573 CASE_CFN_ROUND:
13574 CASE_CFN_ROUND_FN:
13575 CASE_CFN_TRUNC:
13576 CASE_CFN_TRUNC_FN:
13579 CASE_CFN_FMIN:
13580 CASE_CFN_FMIN_FN:
13581 CASE_CFN_FMAX:
13582 CASE_CFN_FMAX_FN:
13587 }
13589 }
13591 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13592 has an integer value. We also allow +Inf, -Inf and NaN to be
13593 considered integer values. Return false for signaling NaN.
13595 DEPTH is the current nesting depth of the query. */
13597 bool
13599 {
13601 {
13609 /* Limit the depth of recursion to avoid quadratic behavior.
13610 This is expected to catch almost all occurrences in practice.
13611 If this code misses important cases that unbounded recursion
13612 would not, passes that need this information could be revised
13613 to provide it through dataflow propagation. */
13617 depth));
13621 }
13623 }
13625 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13626 has an integer value. We also allow +Inf, -Inf and NaN to be
13627 considered integer values. Return false for signaling NaN.
13629 DEPTH is the current nesting depth of the query. */
13631 static bool
13633 {
13635 {
13646 }
13648 }
13650 #undef RECURSE
13651 #undef integer_valued_real_p
13653 /* Return true if the floating point expression T has an integer value.
13654 We also allow +Inf, -Inf and NaN to be considered integer values.
13655 Return false for signaling NaN.
13657 DEPTH is the current nesting depth of the query. */
13659 bool
13661 {
13667 {
13683 }
13686 {
13692 {
13701 }
13705 }
13706 }
13708 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13709 attempt to fold the expression to a constant without modifying TYPE,
13710 OP0 or OP1.
13712 If the expression could be simplified to a constant, then return
13713 the constant. If the expression would not be simplified to a
13714 constant, then return NULL_TREE. */
13716 tree
13718 {
13721 }
13723 /* Given the components of a unary expression CODE, TYPE and OP0,
13724 attempt to fold the expression to a constant without modifying
13725 TYPE or OP0.
13727 If the expression could be simplified to a constant, then return
13728 the constant. If the expression would not be simplified to a
13729 constant, then return NULL_TREE. */
13731 tree
13733 {
13736 }
13738 /* If EXP represents referencing an element in a constant string
13739 (either via pointer arithmetic or array indexing), return the
13740 tree representing the value accessed, otherwise return NULL. */
13742 tree
13744 {
13748 {
13750 tree index;
13751 tree string;
13756 else
13757 {
13761 /* Optimize the special-case of a zero lower bound.
13763 We convert the low_bound to sizetype to avoid some problems
13764 with constant folding. (E.g. suppose the lower bound is 1,
13765 and its mode is QI. Without the conversion,l (ARRAY
13766 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13767 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13773 }
13775 scalar_int_mode char_mode;
13787 }
13789 }
13791 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13792 an integer constant, real, or fixed-point constant.
13794 TYPE is the type of the result. */
13796 static tree
13798 {
13802 {
13808 {
13809 FIXED_VALUE_TYPE f;
13814 /* Propagate overflow flags. */
13818 }
13822 {
13829 }
13832 }
13835 }
13837 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13838 an integer constant or real constant.
13840 TYPE is the type of the result. */
13842 tree
13844 {
13848 {
13850 {
13851 /* If the value is unsigned or non-negative, then the absolute value
13852 is the same as the ordinary value. */
13856 ;
13858 /* If the value is negative, then the absolute value is
13859 its negation. */
13860 else
13863 /* Force to the destination type, set TREE_OVERFLOW for signed
13864 TYPE only. */
13866 }
13872 else
13878 }
13881 }
13883 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13884 constant. TYPE is the type of the result. */
13886 static tree
13888 {
13892 }
13894 /* Given CODE, a relational operator, the target type, TYPE and two
13895 constant operands OP0 and OP1, return the result of the
13896 relational operation. If the result is not a compile time
13897 constant, then return NULL_TREE. */
13899 static tree
13901 {
13904 /* From here on, the only cases we handle are when the result is
13905 known to be a constant. */
13908 {
13912 /* Handle the cases where either operand is a NaN. */
13914 {
13916 {
13944 }
13947 }
13950 }
13953 {
13957 }
13959 /* Handle equality/inequality of complex constants. */
13961 {
13972 else
13974 }
13977 {
13979 {
13980 /* Have vector comparison with scalar boolean result. */
13988 {
13996 }
13998 }
13999 tree_vector_builder elts;
14004 {
14017 }
14020 }
14022 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14024 To compute GT, swap the arguments and do LT.
14025 To compute GE, do LT and invert the result.
14026 To compute LE, swap the arguments, do LT and invert the result.
14027 To compute NE, do EQ and invert the result.
14029 Therefore, the code below must handle only EQ and LT. */
14032 {
14035 }
14037 /* Note that it is safe to invert for real values here because we
14038 have already handled the one case that it matters. */
14042 {
14045 }
14047 /* Compute a result for LT or EQ if args permit;
14048 Otherwise return T. */
14050 {
14053 else
14055 }
14056 else
14062 }
14064 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14065 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14066 itself. */
14068 tree
14070 {
14071 /* If the expression does not have side effects then we don't have to wrap
14072 it with a cleanup point expression. */
14076 /* If the expression is a return, check to see if the expression inside the
14077 return has no side effects or the right hand side of the modify expression
14078 inside the return. If either don't have side effects set we don't need to
14079 wrap the expression in a cleanup point expression. Note we don't check the
14080 left hand side of the modify because it should always be a return decl. */
14082 {
14089 }
14092 }
14094 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14095 of an indirection through OP0, or NULL_TREE if no simplification is
14096 possible. */
14098 tree
14100 {
14102 tree subtype;
14103 poly_uint64 const_op01;
14112 {
14116 /* *&CONST_DECL -> to the value of the const decl. */
14119 /* *&p => p; make sure to handle *&"str"[cst] here. */
14121 {
14125 else
14127 }
14128 /* *(foo *)&fooarray => fooarray[0] */
14131 && (!in_gimple_form
14133 {
14143 }
14144 /* *(foo *)&complexfoo => __real__ complexfoo */
14148 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14151 {
14155 index);
14156 }
14157 }
14161 {
14167 {
14168 tree op00type;
14172 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14175 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14176 but we want to treat offsets with MSB set as negative.
14177 For the code below negative offsets are invalid and
14178 TYPE_SIZE of the element is something unsigned, so
14179 check whether op01 fits into poly_int64, which implies
14180 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14181 then just use poly_uint64 because we want to treat the
14182 value as unsigned. */
14184 {
14186 poly_uint64 max_offset
14190 {
14195 }
14196 }
14197 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14200 {
14202 const_op01))
14204 }
14205 /* ((foo *)&fooarray)[1] => fooarray[1] */
14208 {
14217 {
14222 }
14223 }
14224 }
14225 }
14227 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14230 && (!in_gimple_form
14232 {
14233 tree type_domain;
14243 NULL_TREE);
14244 }
14247 }
14249 /* Builds an expression for an indirection through T, simplifying some
14250 cases. */
14252 tree
14254 {
14262 }
14264 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14266 tree
14268 {
14273 else
14275 }
14277 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14278 whose result is ignored. The type of the returned tree need not be
14279 the same as the original expression. */
14281 tree
14283 {
14289 {
14300 else
14306 {
14322 }
14327 }
14328 }
14330 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14332 tree
14334 {
14340 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14341 have to do anything. Only do this when we are not given a const,
14342 because in that case, this check is more expensive than just
14343 doing it. */
14345 {
14350 }
14352 /* If divisor is a power of two, simplify this to bit manipulation. */
14354 {
14356 {
14370 }
14371 else
14372 {
14373 tree t;
14379 }
14380 }
14381 else
14382 {
14387 }
14390 }
14392 /* Likewise, but round down. */
14394 tree
14396 {
14403 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14404 have to do anything. Only do this when we are not given a const,
14405 because in that case, this check is more expensive than just
14406 doing it. */
14408 {
14413 }
14415 /* If divisor is a power of two, simplify this to bit manipulation. */
14417 {
14418 tree t;
14422 }
14423 else
14424 {
14429 }
14432 }
14434 /* Returns the pointer to the base of the object addressed by EXP and
14435 extracts the information about the offset of the access, storing it
14436 to PBITPOS and POFFSET. */
14438 static tree
14441 {
14442 tree core;
14443 machine_mode mode;
14445 poly_int64 bitsize;
14449 {
14454 }
14456 {
14462 {
14463 poly_offset_int tem
14469 }
14470 }
14471 else
14472 {
14476 }
14479 }
14481 /* Returns true if addresses of E1 and E2 differ by a constant, false
14482 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14484 bool
14486 {
14501 {
14511 }
14513 {
14514 /* If only one of the offsets is non-constant, the difference cannot
14515 be a constant. */
14517 }
14518 else
14523 }
14525 /* Return OFF converted to a pointer offset type suitable as offset for
14526 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14527 tree
14529 {
14531 }
14533 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14534 tree
14536 {
14539 }
14541 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14542 tree
14544 {
14547 }
14549 /* Return a pointer P to a NUL-terminated string representing the sequence
14550 of constant characters referred to by SRC (or a subsequence of such
14551 characters within it if SRC is a reference to a string plus some
14552 constant offset). If STRLEN is non-null, store stgrlen(P) in *STRLEN.
14553 If STRSIZE is non-null, store in *STRSIZE the size of the array
14554 the string is stored in; in that case, even though P points to a NUL
14555 terminated string, SRC need not refer to one. This can happen when
14556 SRC refers to a constant character array initialized to all non-NUL
14557 values, as in the C declaration: char a[4] = "1234"; */
14562 {
14563 tree offset_node;
14574 {
14577 else
14579 }
14581 /* STRING_LENGTH is the size of the string literal, including any
14582 embedded NULs. STRING_SIZE is the size of the array the string
14583 literal is stored in. */
14592 {
14593 /* Compute and store the length of the substring at OFFSET.
14594 All offsets past the initial length refer to null strings. */
14597 else
14599 }
14608 {
14609 /* Support even constant character arrays that aren't proper
14610 NUL-terminated strings. */
14612 }
14614 {
14615 /* Support only properly NUL-terminated strings but handle
14616 consecutive strings within the same array, such as the six
14617 substrings in "1\0002\0003". */
14619 }
14622 }
14624 /* Given a tree T, compute which bits in T may be nonzero. */
14626 wide_int
14628 {
14630 {
14648 CASE_CONVERT:
14654 {
14659 }
14663 {
14671 }
14675 {
14683 }
14687 }
14690 }
14692 #if CHECKING_P
14696 /* Helper functions for writing tests of folding trees. */
14698 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14700 static void
14702 tree constant)
14703 {
14705 }
14707 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14708 wrapping WRAPPED_EXPR. */
14710 static void
14712 tree wrapped_expr)
14713 {
14718 }
14720 /* Verify that various arithmetic binary operations are folded
14721 correctly. */
14723 static void
14725 {
14731 /* Addition. */
14732 /* 1 <-- (0 + 1) */
14734 one);
14736 one);
14738 /* (nonlvalue)x <-- (x + 0) */
14740 x);
14742 /* Subtraction. */
14743 /* 0 <-- (x - x) */
14745 zero);
14747 x);
14749 /* Multiplication. */
14750 /* 0 <-- (x * 0) */
14752 zero);
14754 /* (nonlvalue)x <-- (x * 1) */
14756 x);
14757 }
14759 /* Verify that various binary operations on vectors are folded
14760 correctly. */
14762 static void
14764 {
14770 /* Verify equality tests that return a scalar boolean result. */
14776 }
14778 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14780 static void
14782 {
14785 /* This will be 1 if VEC_MODE isn't a vector mode. */
14792 }
14794 /* Run all of the selftests within this file. */
14796 void
14798 {
14802 }