| blob | 4568e1e2b5744cf7a2f8895422cafa5a0a509bba |
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 {
2372 }
2373 }
2375 /* Convert expression ARG to type TYPE. Used by the middle-end for
2376 simple conversions in preference to calling the front-end's convert. */
2378 tree
2380 {
2382 tree tem;
2393 {
2396 /* Handle conversions between pointers to different address spaces. */
2401 /* fall through */
2406 {
2410 }
2424 {
2428 }
2430 {
2434 }
2436 {
2440 }
2443 {
2461 }
2466 {
2470 }
2473 {
2487 }
2491 {
2500 integer_zero_node));
2502 {
2506 {
2512 }
2520 }
2524 }
2542 }
2543 fold_convert_exit:
2546 }
2547 \f
2548 /* Return false if expr can be assumed not to be an lvalue, true
2549 otherwise. */
2551 static bool
2553 {
2554 /* We only need to wrap lvalue tree codes. */
2556 {
2587 /* Assume the worst for front-end tree codes. */
2591 }
2594 }
2596 /* Return an expr equal to X but certainly not valid as an lvalue. */
2598 tree
2600 {
2601 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2602 us. */
2609 }
2611 /* When pedantic, return an expr equal to X but certainly not valid as a
2612 pedantic lvalue. Otherwise, return X. */
2614 static tree
2616 {
2618 }
2619 \f
2620 /* Given a tree comparison code, return the code that is the logical inverse.
2621 It is generally not safe to do this for floating-point comparisons, except
2622 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2623 ERROR_MARK in this case. */
2625 enum tree_code
2627 {
2633 {
2664 }
2665 }
2667 /* Similar, but return the comparison that results if the operands are
2668 swapped. This is safe for floating-point. */
2670 enum tree_code
2672 {
2674 {
2700 }
2701 }
2704 /* Convert a comparison tree code from an enum tree_code representation
2705 into a compcode bit-based encoding. This function is the inverse of
2706 compcode_to_comparison. */
2708 static enum comparison_code
2710 {
2712 {
2743 }
2744 }
2746 /* Convert a compcode bit-based encoding of a comparison operator back
2747 to GCC's enum tree_code representation. This function is the
2748 inverse of comparison_to_compcode. */
2750 static enum tree_code
2752 {
2754 {
2785 }
2786 }
2788 /* Return a tree for the comparison which is the combination of
2789 doing the AND or OR (depending on CODE) of the two operations LCODE
2790 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2791 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2792 if this makes the transformation invalid. */
2794 tree
2799 {
2806 {
2817 }
2820 {
2821 /* Eliminate unordered comparisons, as well as LTGT and ORD
2822 which are not used unless the mode has NaNs. */
2828 }
2830 {
2831 /* Check that the original operation and the optimized ones will trap
2832 under the same condition. */
2843 /* In a short-circuited boolean expression the LHS might be
2844 such that the RHS, if evaluated, will never trap. For
2845 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2846 if neither x nor y is NaN. (This is a mixed blessing: for
2847 example, the expression above will never trap, hence
2848 optimizing it to x < y would be invalid). */
2853 /* If the comparison was short-circuited, and only the RHS
2854 trapped, we may now generate a spurious trap. */
2859 /* If we changed the conditions that cause a trap, we lose. */
2862 }
2868 else
2869 {
2874 }
2875 }
2876 \f
2877 /* Return nonzero if two operands (typically of the same tree node)
2878 are necessarily equal. FLAGS modifies behavior as follows:
2880 If OEP_ONLY_CONST is set, only return nonzero for constants.
2881 This function tests whether the operands are indistinguishable;
2882 it does not test whether they are equal using C's == operation.
2883 The distinction is important for IEEE floating point, because
2884 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2885 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2887 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2888 even though it may hold multiple values during a function.
2889 This is because a GCC tree node guarantees that nothing else is
2890 executed between the evaluation of its "operands" (which may often
2891 be evaluated in arbitrary order). Hence if the operands themselves
2892 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2893 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2894 unset means assuming isochronic (or instantaneous) tree equivalence.
2895 Unless comparing arbitrary expression trees, such as from different
2896 statements, this flag can usually be left unset.
2898 If OEP_PURE_SAME is set, then pure functions with identical arguments
2899 are considered the same. It is used when the caller has other ways
2900 to ensure that global memory is unchanged in between.
2902 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2903 not values of expressions.
2905 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2906 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2908 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2909 any operand with side effect. This is unnecesarily conservative in the
2910 case we know that arg0 and arg1 are in disjoint code paths (such as in
2911 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2912 addresses with TREE_CONSTANT flag set so we know that &var == &var
2913 even if var is volatile. */
2915 int
2917 {
2918 /* When checking, verify at the outermost operand_equal_p call that
2919 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2920 hash value. */
2922 {
2924 {
2926 {
2933 }
2935 }
2936 else
2938 }
2940 /* If either is ERROR_MARK, they aren't equal. */
2946 /* Similar, if either does not have a type (like a released SSA name),
2947 they aren't equal. */
2951 /* We cannot consider pointers to different address space equal. */
2958 /* Check equality of integer constants before bailing out due to
2959 precision differences. */
2961 {
2962 /* Address of INTEGER_CST is not defined; check that we did not forget
2963 to drop the OEP_ADDRESS_OF flags. */
2966 }
2969 {
2970 /* If both types don't have the same signedness, then we can't consider
2971 them equal. We must check this before the STRIP_NOPS calls
2972 because they may change the signedness of the arguments. As pointers
2973 strictly don't have a signedness, require either two pointers or
2974 two non-pointers as well. */
2980 /* If both types don't have the same precision, then it is not safe
2981 to strip NOPs. */
2988 }
2989 #if 0
2990 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2991 sanity check once the issue is solved. */
2992 else
2993 /* Addresses of conversions and SSA_NAMEs (and many other things)
2994 are not defined. Check that we did not forget to drop the
2995 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2998 #endif
3000 /* In case both args are comparisons but with different comparison
3001 code, try to swap the comparison operands of one arg to produce
3002 a match and compare that variant. */
3006 {
3014 }
3017 {
3018 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3020 ;
3022 {
3023 /* If we are interested in comparing addresses ignore
3024 MEM_REF wrappings of the base that can appear just for
3025 TBAA reasons. */
3039 }
3040 else
3042 }
3044 /* When not checking adddresses, this is needed for conversions and for
3045 COMPONENT_REF. Might as well play it safe and always test this. */
3052 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3053 We don't care about side effects in that case because the SAVE_EXPR
3054 takes care of that for us. In all other cases, two expressions are
3055 equal if they have no side effects. If we have two identical
3056 expressions with side effects that should be treated the same due
3057 to the only side effects being identical SAVE_EXPR's, that will
3058 be detected in the recursive calls below.
3059 If we are taking an invariant address of two identical objects
3060 they are necessarily equal as well. */
3067 /* Next handle constant cases, those for which we can return 1 even
3068 if ONLY_CONST is set. */
3071 {
3085 {
3086 /* If we do not distinguish between signed and unsigned zero,
3087 consider them equal. */
3090 }
3094 {
3109 }
3113 flags)
3115 flags));
3126 flags | OEP_ADDRESS_OF
3129 /* In GIMPLE empty constructors are allowed in initializers of
3130 aggregates. */
3134 }
3139 /* Define macros to test an operand from arg0 and arg1 for equality and a
3140 variant that allows null and views null as being different from any
3141 non-null value. In the latter case, if either is null, the both
3142 must be; otherwise, do the normal comparison. */
3143 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3144 TREE_OPERAND (arg1, N), flags)
3146 #define OP_SAME_WITH_NULL(N) \
3147 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3148 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3151 {
3153 /* Two conversions are equal only if signedness and modes match. */
3155 {
3156 CASE_CONVERT:
3164 }
3174 /* For commutative ops, allow the other order. */
3182 /* If either of the pointer (or reference) expressions we are
3183 dereferencing contain a side effect, these cannot be equal,
3184 but their addresses can be. */
3191 {
3201 /* Require the same offset. */
3207 /* Fallthru. */
3215 {
3216 /* Require equal access sizes */
3222 flags)))
3224 /* Verify that access happens in similar types. */
3227 /* Verify that accesses are TBAA compatible. */
3236 /* Verify that alignment is compatible. */
3240 }
3243 /* TARGET_MEM_REF require equal extra operands. */
3254 /* Compare the array index by value if it is constant first as we
3255 may have different types but same value here. */
3261 /* Compare low bound and element size as with OEP_ADDRESS_OF
3262 we have to account for the offset of the ref. */
3267 array_ref_low_bound
3271 array_ref_element_size
3273 flags))));
3276 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3277 may be NULL when we're called to compare MEM_EXPRs. */
3292 }
3296 {
3298 /* Be sure we pass right ADDRESS_OF flag. */
3315 /* The multiplcation operands are commutative. */
3316 /* FALLTHRU */
3324 /* Otherwise take into account this is a commutative operation. */
3337 /* BIT_INSERT_EXPR has an implict operand as the type precision
3338 of op1. Need to check to make sure they are the same. */
3344 /* FALLTHRU */
3370 }
3374 {
3378 /* If not both CALL_EXPRs are either internal or normal function
3379 functions, then they are not equal. */
3382 {
3383 /* If the CALL_EXPRs call different internal functions, then they
3384 are not equal. */
3387 }
3388 else
3389 {
3390 /* If the CALL_EXPRs call different functions, then they are not
3391 equal. */
3393 flags))
3395 }
3397 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3398 {
3402 else
3406 }
3408 /* Now see if all the arguments are the same. */
3409 {
3420 /* If we get here and both argument lists are exhausted
3421 then the CALL_EXPRs are equal. */
3423 }
3426 }
3429 /* Consider __builtin_sqrt equal to sqrt. */
3437 {
3438 /* In GIMPLE constructors are used only to build vectors from
3439 elements. Individual elements in the constructor must be
3440 indexed in increasing order and form an initial sequence.
3442 We make no effort to compare constructors in generic.
3443 (see sem_variable::equals in ipa-icf which can do so for
3444 constants). */
3449 /* Be sure that vectors constructed have the same representation.
3450 We only tested element precision and modes to match.
3451 Vectors may be BLKmode and thus also check that the number of
3452 parts match. */
3465 {
3470 /* In GIMPLE the indexes can be either NULL or matching i.
3471 Double check this so we won't get false
3472 positives for GENERIC. */
3480 }
3482 }
3485 {
3486 /* Compare the STATEMENT_LISTs. */
3492 {
3493 /* The lists don't have the same number of statements. */
3499 flags & (OEP_LEXICOGRAPHIC
3502 }
3503 }
3508 {
3519 }
3523 }
3525 #undef OP_SAME
3526 #undef OP_SAME_WITH_NULL
3527 }
3528 \f
3529 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3530 with a different signedness or a narrower precision. */
3532 static bool
3534 {
3542 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3543 and see if the inner values are the same. This removes any
3544 signedness comparison, which doesn't matter here. */
3552 /* Discard a single widening conversion from ARG1 and see if the inner
3553 value is the same as ARG0. */
3562 }
3563 \f
3564 /* See if ARG is an expression that is either a comparison or is performing
3565 arithmetic on comparisons. The comparisons must only be comparing
3566 two different values, which will be stored in *CVAL1 and *CVAL2; if
3567 they are nonzero it means that some operands have already been found.
3568 No variables may be used anywhere else in the expression except in the
3569 comparisons.
3571 If this is true, return 1. Otherwise, return zero. */
3573 static int
3575 {
3579 /* We can handle some of the tcc_expression cases here. */
3588 {
3607 /* First see if we can handle the first operand, then the second. For
3608 the second operand, we know *CVAL1 can't be zero. It must be that
3609 one side of the comparison is each of the values; test for the
3610 case where this isn't true by failing if the two operands
3611 are the same. */
3620 ;
3624 ;
3625 else
3629 ;
3633 ;
3634 else
3641 }
3642 }
3643 \f
3644 /* ARG is a tree that is known to contain just arithmetic operations and
3645 comparisons. Evaluate the operations in the tree substituting NEW0 for
3646 any occurrence of OLD0 as an operand of a comparison and likewise for
3647 NEW1 and OLD1. */
3649 static tree
3652 {
3657 /* We can handle some of the tcc_expression cases here. */
3665 {
3680 {
3699 }
3700 /* Fall through - ??? */
3703 {
3707 /* We need to check both for exact equality and tree equality. The
3708 former will be true if the operand has a side-effect. In that
3709 case, we know the operand occurred exactly once. */
3722 }
3726 }
3727 }
3728 \f
3729 /* Return a tree for the case when the result of an expression is RESULT
3730 converted to TYPE and OMITTED was previously an operand of the expression
3731 but is now not needed (e.g., we folded OMITTED * 0).
3733 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3734 the conversion of RESULT to TYPE. */
3736 tree
3738 {
3741 /* If the resulting operand is an empty statement, just return the omitted
3742 statement casted to void. */
3752 }
3754 /* Return a tree for the case when the result of an expression is RESULT
3755 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3756 of the expression but are now not needed.
3758 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3759 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3760 evaluated before OMITTED2. Otherwise, if neither has side effects,
3761 just do the conversion of RESULT to TYPE. */
3763 tree
3766 {
3775 }
3777 \f
3778 /* Return a simplified tree node for the truth-negation of ARG. This
3779 never alters ARG itself. We assume that ARG is an operation that
3780 returns a truth value (0 or 1).
3782 FIXME: one would think we would fold the result, but it causes
3783 problems with the dominator optimizer. */
3785 static tree
3787 {
3792 /* If this is a comparison, we can simply invert it, except for
3793 floating-point non-equality comparisons, in which case we just
3794 enclose a TRUTH_NOT_EXPR around what we have. */
3797 {
3800 && flag_trapping_math
3814 }
3817 {
3836 /* Here we can invert either operand. We invert the first operand
3837 unless the second operand is a TRUTH_NOT_EXPR in which case our
3838 result is the XOR of the first operand with the inside of the
3839 negation of the second operand. */
3844 else
3867 {
3874 /* A COND_EXPR may have a throw as one operand, which
3875 then has void type. Just leave void operands
3876 as they are. */
3882 }
3894 CASE_CONVERT:
3898 /* fall through */
3920 }
3921 }
3923 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3924 assume that ARG is an operation that returns a truth value (0 or 1
3925 for scalars, 0 or -1 for vectors). Return the folded expression if
3926 folding is successful. Otherwise, return NULL_TREE. */
3928 static tree
3930 {
3933 ? BIT_NOT_EXPR
3936 }
3938 /* Return a simplified tree node for the truth-negation of ARG. This
3939 never alters ARG itself. We assume that ARG is an operation that
3940 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3942 tree
3944 {
3950 ? BIT_NOT_EXPR
3953 }
3954 \f
3955 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3956 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3957 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3958 is the original memory reference used to preserve the alias set of
3959 the access. */
3961 static tree
3965 {
3968 /* Attempt not to lose the access path if possible. */
3970 {
3972 machine_mode nmode;
3974 tree noffset;
3982 && !reversep
3983 && !nreversep
3985 {
3988 }
3989 }
3998 {
4005 }
4020 }
4022 /* Optimize a bit-field compare.
4024 There are two cases: First is a compare against a constant and the
4025 second is a comparison of two items where the fields are at the same
4026 bit position relative to the start of a chunk (byte, halfword, word)
4027 large enough to contain it. In these cases we can avoid the shift
4028 implicit in bitfield extractions.
4030 For constants, we emit a compare of the shifted constant with the
4031 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4032 compared. For two fields at the same position, we do the ANDs with the
4033 similar mask and compare the result of the ANDs.
4035 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4036 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4037 are the left and right operands of the comparison, respectively.
4039 If the optimization described above can be done, we return the resulting
4040 tree. Otherwise we return zero. */
4042 static tree
4045 {
4049 tree unsigned_type;
4052 scalar_int_mode nmode;
4057 tree mask;
4058 tree offset;
4060 /* Get all the information about the extractions being done. If the bit size
4061 is the same as the size of the underlying object, we aren't doing an
4062 extraction at all and so can do nothing. We also don't want to
4063 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4064 then will no longer be able to replace it. */
4079 else
4080 {
4081 /* If this is not a constant, we can only do something if bit positions,
4082 sizes, signedness and storage order are the same. */
4083 rinner
4096 }
4098 /* Honor the C++ memory model and mimic what RTL expansion does. */
4102 {
4106 }
4108 /* See if we can find a mode to refer to this field. We should be able to,
4109 but fail if we can't. */
4117 /* Set signed and unsigned types of the precision of this mode for the
4118 shifts below. */
4121 /* Compute the bit position and size for the new reference and our offset
4122 within it. If the new reference is the same size as the original, we
4123 won't optimize anything, so return zero. */
4133 /* Make the mask to be used against the extracted field. */
4140 {
4144 /* If not comparing with constant, just rework the comparison
4145 and return. */
4153 }
4155 /* Otherwise, we are handling the constant case. See if the constant is too
4156 big for the field. Warn and return a tree for 0 (false) if so. We do
4157 this not only for its own sake, but to avoid having to test for this
4158 error case below. If we didn't, we might generate wrong code.
4160 For unsigned fields, the constant shifted right by the field length should
4161 be all zero. For signed fields, the high-order bits should agree with
4162 the sign bit. */
4165 {
4167 {
4171 }
4172 }
4173 else
4174 {
4177 {
4181 }
4182 }
4187 /* Single-bit compares should always be against zero. */
4189 {
4192 }
4194 /* Make a new bitfield reference, shift the constant over the
4195 appropriate number of bits and mask it with the computed mask
4196 (in case this was a signed field). If we changed it, make a new one. */
4204 mask);
4209 }
4210 \f
4211 /* Subroutine for fold_truth_andor_1: decode a field reference.
4213 If EXP is a comparison reference, we return the innermost reference.
4215 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4216 set to the starting bit number.
4218 If the innermost field can be completely contained in a mode-sized
4219 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4221 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4222 otherwise it is not changed.
4224 *PUNSIGNEDP is set to the signedness of the field.
4226 *PREVERSEP is set to the storage order of the field.
4228 *PMASK is set to the mask used. This is either contained in a
4229 BIT_AND_EXPR or derived from the width of the field.
4231 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4233 Return 0 if this is not a component reference or is one that we can't
4234 do anything with. */
4236 static tree
4241 {
4246 tree unsigned_type;
4249 /* All the optimizations using this function assume integer fields.
4250 There are problems with FP fields since the type_for_size call
4251 below can fail for, e.g., XFmode. */
4255 /* We are interested in the bare arrangement of bits, so strip everything
4256 that doesn't affect the machine mode. However, record the type of the
4257 outermost expression if it may matter below. */
4264 {
4270 }
4281 /* Reject out-of-bound accesses (PR79731). */
4289 /* If the number of bits in the reference is the same as the bitsize of
4290 the outer type, then the outer type gives the signedness. Otherwise
4291 (in case of a small bitfield) the signedness is unchanged. */
4295 /* Compute the mask to access the bitfield. */
4304 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4312 }
4314 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4315 bit positions and MASK is SIGNED. */
4317 static int
4319 {
4323 /* If this function returns true when the type of the mask is
4324 UNSIGNED, then there will be errors. In particular see
4325 gcc.c-torture/execute/990326-1.c. There does not appear to be
4326 any documentation paper trail as to why this is so. But the pre
4327 wide-int worked with that restriction and it has been preserved
4328 here. */
4333 }
4335 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4336 represents the sign bit of EXP's type. If EXP represents a sign
4337 or zero extension, also test VAL against the unextended type.
4338 The return value is the (sub)expression whose sign bit is VAL,
4339 or NULL_TREE otherwise. */
4341 tree
4343 {
4345 tree t;
4347 /* Tree EXP must have an integral type. */
4352 /* Tree VAL must be an integer constant. */
4361 /* Handle extension from a narrower type. */
4367 }
4369 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4370 to be evaluated unconditionally. */
4372 static int
4374 {
4375 /* Strip any conversions that don't change the machine mode. */
4384 /* Don't regard global variables as simple. They may be
4385 allocated in ways unknown to the compiler (shared memory,
4386 #pragma weak, etc). */
4389 /* Weakrefs are not safe to be read, since they can be NULL.
4390 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4391 have DECL_WEAK flag set. */
4393 /* Loading a static variable is unduly expensive, but global
4394 registers aren't expensive. */
4396 }
4398 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4399 to be evaluated unconditionally.
4400 I addition to simple_operand_p, we assume that comparisons, conversions,
4401 and logic-not operations are simple, if their operands are simple, too. */
4403 static bool
4405 {
4425 }
4427 \f
4428 /* The following functions are subroutines to fold_range_test and allow it to
4429 try to change a logical combination of comparisons into a range test.
4431 For example, both
4432 X == 2 || X == 3 || X == 4 || X == 5
4433 and
4434 X >= 2 && X <= 5
4435 are converted to
4436 (unsigned) (X - 2) <= 3
4438 We describe each set of comparisons as being either inside or outside
4439 a range, using a variable named like IN_P, and then describe the
4440 range with a lower and upper bound. If one of the bounds is omitted,
4441 it represents either the highest or lowest value of the type.
4443 In the comments below, we represent a range by two numbers in brackets
4444 preceded by a "+" to designate being inside that range, or a "-" to
4445 designate being outside that range, so the condition can be inverted by
4446 flipping the prefix. An omitted bound is represented by a "-". For
4447 example, "- [-, 10]" means being outside the range starting at the lowest
4448 possible value and ending at 10, in other words, being greater than 10.
4449 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4450 always false.
4452 We set up things so that the missing bounds are handled in a consistent
4453 manner so neither a missing bound nor "true" and "false" need to be
4454 handled using a special case. */
4456 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4457 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4458 and UPPER1_P are nonzero if the respective argument is an upper bound
4459 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4460 must be specified for a comparison. ARG1 will be converted to ARG0's
4461 type if both are specified. */
4463 static tree
4466 {
4467 tree tem;
4471 /* If neither arg represents infinity, do the normal operation.
4472 Else, if not a comparison, return infinity. Else handle the special
4473 comparison rules. Note that most of the cases below won't occur, but
4474 are handled for consistency. */
4477 {
4482 }
4487 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4488 for neither. In real maths, we cannot assume open ended ranges are
4489 the same. But, this is computer arithmetic, where numbers are finite.
4490 We can therefore make the transformation of any unbounded range with
4491 the value Z, Z being greater than any representable number. This permits
4492 us to treat unbounded ranges as equal. */
4496 {
4517 }
4520 }
4521 \f
4522 /* Helper routine for make_range. Perform one step for it, return
4523 new expression if the loop should continue or NULL_TREE if it should
4524 stop. */
4526 tree
4530 {
4536 {
4538 /* We can only do something if the range is testing for zero. */
4547 /* We can only do something if the range is testing for zero
4548 and if the second operand is an integer constant. Note that
4549 saying something is "in" the range we make is done by
4550 complementing IN_P since it will set in the initial case of
4551 being not equal to zero; "out" is leaving it alone. */
4558 {
4579 }
4581 /* If this is an unsigned comparison, we also know that EXP is
4582 greater than or equal to zero. We base the range tests we make
4583 on that fact, so we record it here so we can parse existing
4584 range tests. We test arg0_type since often the return type
4585 of, e.g. EQ_EXPR, is boolean. */
4587 {
4591 NULL_TREE))
4596 /* If the high bound is missing, but we have a nonzero low
4597 bound, reverse the range so it goes from zero to the low bound
4598 minus 1. */
4600 {
4605 }
4606 }
4614 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4615 low and high are non-NULL, then normalize will DTRT. */
4618 {
4623 }
4625 /* (-x) IN [a,b] -> x in [-b, -a] */
4637 /* ~ X -> -X - 1 */
4646 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4647 move a constant to the other side. */
4652 /* If EXP is signed, any overflow in the computation is undefined,
4653 so we don't worry about it so long as our computations on
4654 the bounds don't overflow. For unsigned, overflow is defined
4655 and this is exactly the right thing. */
4667 normalize:
4668 /* Check for an unsigned range which has wrapped around the maximum
4669 value thus making n_high < n_low, and normalize it. */
4671 {
4677 /* If the range is of the form +/- [ x+1, x ], we won't
4678 be able to normalize it. But then, it represents the
4679 whole range or the empty set, so make it
4680 +/- [ -, - ]. */
4684 else
4686 }
4687 else
4695 CASE_CONVERT:
4713 /* If we're converting arg0 from an unsigned type, to exp,
4714 a signed type, we will be doing the comparison as unsigned.
4715 The tests above have already verified that LOW and HIGH
4716 are both positive.
4718 So we have to ensure that we will handle large unsigned
4719 values the same way that the current signed bounds treat
4720 negative values. */
4723 {
4724 tree high_positive;
4725 tree equiv_type;
4726 /* For fixed-point modes, we need to pass the saturating flag
4727 as the 2nd parameter. */
4729 equiv_type
4732 else
4733 equiv_type
4736 /* A range without an upper bound is, naturally, unbounded.
4737 Since convert would have cropped a very large value, use
4738 the max value for the destination type. */
4739 high_positive
4746 high_positive),
4749 /* If the low bound is specified, "and" the range with the
4750 range for which the original unsigned value will be
4751 positive. */
4753 {
4756 integer_zero_node),
4757 high_positive))
4761 }
4762 else
4763 {
4764 /* Otherwise, "or" the range with the range of the input
4765 that will be interpreted as negative. */
4768 integer_zero_node),
4769 high_positive))
4773 }
4774 }
4783 }
4784 }
4786 /* Given EXP, a logical expression, set the range it is testing into
4787 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4788 actually being tested. *PLOW and *PHIGH will be made of the same
4789 type as the returned expression. If EXP is not a comparison, we
4790 will most likely not be returning a useful value and range. Set
4791 *STRICT_OVERFLOW_P to true if the return value is only valid
4792 because signed overflow is undefined; otherwise, do not change
4793 *STRICT_OVERFLOW_P. */
4795 tree
4798 {
4806 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4807 and see if we can refine the range. Some of the cases below may not
4808 happen, but it doesn't seem worth worrying about this. We "continue"
4809 the outer loop when we've changed something; otherwise we "break"
4810 the switch, which will "break" the while. */
4816 {
4822 {
4830 }
4839 }
4841 /* If EXP is a constant, we can evaluate whether this is true or false. */
4843 {
4850 }
4854 }
4856 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4857 a bitwise check i.e. when
4858 LOW == 0xXX...X00...0
4859 HIGH == 0xXX...X11...1
4860 Return corresponding mask in MASK and stem in VALUE. */
4862 static bool
4865 {
4888 }
4889 \f
4890 /* Helper routine for build_range_check and match.pd. Return the type to
4891 perform the check or NULL if it shouldn't be optimized. */
4893 tree
4895 {
4896 /* First make sure that arithmetics in this type is valid, then make sure
4897 that it wraps around. */
4903 {
4906 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4907 for the type in question, as we rely on this here. */
4917 else
4919 }
4921 }
4923 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4924 type, TYPE, return an expression to test if EXP is in (or out of, depending
4925 on IN_P) the range. Return 0 if the test couldn't be created. */
4927 tree
4930 {
4933 /* Disable this optimization for function pointer expressions
4934 on targets that require function pointer canonicalization. */
4941 {
4947 }
4969 value);
4972 {
4974 {
4978 }
4980 }
4982 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4984 {
4988 {
4990 {
4993 etype
4995 else
4998 }
5001 }
5002 }
5004 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5005 This requires wrap-around arithmetics for the type of the expression. */
5025 }
5026 \f
5027 /* Return the predecessor of VAL in its type, handling the infinite case. */
5029 static tree
5031 {
5037 else
5040 }
5042 /* Return the successor of VAL in its type, handling the infinite case. */
5044 static tree
5046 {
5052 else
5055 }
5057 /* Given two ranges, see if we can merge them into one. Return 1 if we
5058 can, 0 if we can't. Set the output range into the specified parameters. */
5060 bool
5063 {
5067 tree tem;
5077 /* Make range 0 be the range that starts first, or ends last if they
5078 start at the same value. Swap them if it isn't. */
5081 || (lowequal
5084 {
5088 }
5090 /* If the second range is != high1 where high1 is the type maximum of
5091 the type, try first merging with < high1 range. */
5093 && high1
5100 {
5105 /* Similarly for the second range != low1 where low1 is the type minimum
5106 of the type, try first merging with > low1 range. */
5111 }
5113 /* Now flag two cases, whether the ranges are disjoint or whether the
5114 second range is totally subsumed in the first. Note that the tests
5115 below are simplified by the ones above. */
5121 /* We now have four cases, depending on whether we are including or
5122 excluding the two ranges. */
5124 {
5125 /* If they don't overlap, the result is false. If the second range
5126 is a subset it is the result. Otherwise, the range is from the start
5127 of the second to the end of the first. */
5132 else
5134 }
5137 {
5138 /* If they don't overlap, the result is the first range. If they are
5139 equal, the result is false. If the second range is a subset of the
5140 first, and the ranges begin at the same place, we go from just after
5141 the end of the second range to the end of the first. If the second
5142 range is not a subset of the first, or if it is a subset and both
5143 ranges end at the same place, the range starts at the start of the
5144 first range and ends just before the second range.
5145 Otherwise, we can't describe this as a single range. */
5151 {
5156 {
5157 /* We are in the weird situation where high0 > high1 but
5158 high1 has no successor. Punt. */
5160 }
5161 }
5163 {
5168 {
5169 /* low0 < low1 but low1 has no predecessor. Punt. */
5171 }
5172 }
5173 else
5175 }
5178 {
5179 /* If they don't overlap, the result is the second range. If the second
5180 is a subset of the first, the result is false. Otherwise,
5181 the range starts just after the first range and ends at the
5182 end of the second. */
5187 else
5188 {
5193 {
5194 /* high1 > high0 but high0 has no successor. Punt. */
5196 }
5197 }
5198 }
5200 else
5201 {
5202 /* The case where we are excluding both ranges. Here the complex case
5203 is if they don't overlap. In that case, the only time we have a
5204 range is if they are adjacent. If the second is a subset of the
5205 first, the result is the first. Otherwise, the range to exclude
5206 starts at the beginning of the first range and ends at the end of the
5207 second. */
5209 {
5214 else
5215 {
5216 /* Canonicalize - [min, x] into - [-, x]. */
5219 {
5222 GET_MODE_BITSIZE
5225 /* FALLTHROUGH */
5238 }
5240 /* Canonicalize - [x, max] into - [x, -]. */
5243 {
5246 GET_MODE_BITSIZE
5249 /* FALLTHROUGH */
5265 }
5267 /* The ranges might be also adjacent between the maximum and
5268 minimum values of the given type. For
5269 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5270 return + [x + 1, y - 1]. */
5272 {
5279 }
5280 else
5282 }
5283 }
5286 else
5288 }
5292 }
5293 \f
5295 /* Subroutine of fold, looking inside expressions of the form
5296 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5297 of the COND_EXPR. This function is being used also to optimize
5298 A op B ? C : A, by reversing the comparison first.
5300 Return a folded expression whose code is not a COND_EXPR
5301 anymore, or NULL_TREE if no folding opportunity is found. */
5303 static tree
5306 {
5311 tree tem;
5316 /* If we have A op 0 ? A : -A, consider applying the following
5317 transformations:
5319 A == 0? A : -A same as -A
5320 A != 0? A : -A same as A
5321 A >= 0? A : -A same as abs (A)
5322 A > 0? A : -A same as abs (A)
5323 A <= 0? A : -A same as -abs (A)
5324 A < 0? A : -A same as -abs (A)
5326 None of these transformations work for modes with signed
5327 zeros. If A is +/-0, the first two transformations will
5328 change the sign of the result (from +0 to -0, or vice
5329 versa). The last four will fix the sign of the result,
5330 even though the original expressions could be positive or
5331 negative, depending on the sign of A.
5333 Note that all these transformations are correct if A is
5334 NaN, since the two alternatives (A and -A) are also NaNs. */
5341 /* In the case that A is of the form X-Y, '-A' (arg2) may
5342 have already been folded to Y-X, check for that. */
5350 {
5362 /* Fall through. */
5373 /* FALLTHRU */
5383 }
5385 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5386 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5387 both transformations are correct when A is NaN: A != 0
5388 is then true, and A == 0 is false. */
5392 {
5397 }
5399 /* Try some transformations of A op B ? A : B.
5401 A == B? A : B same as B
5402 A != B? A : B same as A
5403 A >= B? A : B same as max (A, B)
5404 A > B? A : B same as max (B, A)
5405 A <= B? A : B same as min (A, B)
5406 A < B? A : B same as min (B, A)
5408 As above, these transformations don't work in the presence
5409 of signed zeros. For example, if A and B are zeros of
5410 opposite sign, the first two transformations will change
5411 the sign of the result. In the last four, the original
5412 expressions give different results for (A=+0, B=-0) and
5413 (A=-0, B=+0), but the transformed expressions do not.
5415 The first two transformations are correct if either A or B
5416 is a NaN. In the first transformation, the condition will
5417 be false, and B will indeed be chosen. In the case of the
5418 second transformation, the condition A != B will be true,
5419 and A will be chosen.
5421 The conversions to max() and min() are not correct if B is
5422 a number and A is not. The conditions in the original
5423 expressions will be false, so all four give B. The min()
5424 and max() versions would give a NaN instead. */
5427 /* Avoid these transformations if the COND_EXPR may be used
5428 as an lvalue in the C++ front-end. PR c++/19199. */
5429 && (in_gimple_form
5435 {
5441 {
5450 /* In C++ a ?: expression can be an lvalue, so put the
5451 operand which will be used if they are equal first
5452 so that we can convert this back to the
5453 corresponding COND_EXPR. */
5455 {
5463 }
5470 {
5478 }
5491 }
5492 }
5495 }
5498 \f
5499 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5500 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5501 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5502 false) >= 2)
5503 #endif
5505 /* EXP is some logical combination of boolean tests. See if we can
5506 merge it into some range test. Return the new tree if so. */
5508 static tree
5511 {
5527 /* If this is an OR operation, invert both sides; we will invert
5528 again at the end. */
5532 /* If both expressions are the same, if we can merge the ranges, and we
5533 can build the range test, return it or it inverted. If one of the
5534 ranges is always true or always false, consider it to be the same
5535 expression as the other. */
5543 {
5547 }
5549 /* On machines where the branch cost is expensive, if this is a
5550 short-circuited branch and the underlying object on both sides
5551 is the same, make a non-short-circuit operation. */
5553 && !flag_sanitize_coverage
5558 {
5559 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5560 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5561 which cases we can't do this. */
5569 {
5578 {
5581 WARN_STRICT_OVERFLOW_COMPARISON);
5585 }
5586 }
5587 }
5590 }
5591 \f
5592 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5593 bit value. Arrange things so the extra bits will be set to zero if and
5594 only if C is signed-extended to its full width. If MASK is nonzero,
5595 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5597 static tree
5599 {
5602 tree temp;
5607 /* We work by getting just the sign bit into the low-order bit, then
5608 into the high-order bit, then sign-extend. We then XOR that value
5609 with C. */
5613 /* We must use a signed type in order to get an arithmetic right shift.
5614 However, we must also avoid introducing accidental overflows, so that
5615 a subsequent call to integer_zerop will work. Hence we must
5616 do the type conversion here. At this point, the constant is either
5617 zero or one, and the conversion to a signed type can never overflow.
5618 We could get an overflow if this conversion is done anywhere else. */
5627 /* If necessary, convert the type back to match the type of C. */
5632 }
5633 \f
5634 /* For an expression that has the form
5635 (A && B) || ~B
5636 or
5637 (A || B) && ~B,
5638 we can drop one of the inner expressions and simplify to
5639 A || ~B
5640 or
5641 A && ~B
5642 LOC is the location of the resulting expression. OP is the inner
5643 logical operation; the left-hand side in the examples above, while CMPOP
5644 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5645 removing a condition that guards another, as in
5646 (A != NULL && A->...) || A == NULL
5647 which we must not transform. If RHS_ONLY is true, only eliminate the
5648 right-most operand of the inner logical operation. */
5650 static tree
5653 {
5671 {
5674 {
5677 }
5678 }
5680 {
5683 {
5686 }
5687 }
5702 }
5704 /* Find ways of folding logical expressions of LHS and RHS:
5705 Try to merge two comparisons to the same innermost item.
5706 Look for range tests like "ch >= '0' && ch <= '9'".
5707 Look for combinations of simple terms on machines with expensive branches
5708 and evaluate the RHS unconditionally.
5710 For example, if we have p->a == 2 && p->b == 4 and we can make an
5711 object large enough to span both A and B, we can do this with a comparison
5712 against the object ANDed with the a mask.
5714 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5715 operations to do this with one comparison.
5717 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5718 function and the one above.
5720 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5721 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5723 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5724 two operands.
5726 We return the simplified tree or 0 if no optimization is possible. */
5728 static tree
5731 {
5732 /* If this is the "or" of two comparisons, we can do something if
5733 the comparisons are NE_EXPR. If this is the "and", we can do something
5734 if the comparisons are EQ_EXPR. I.e.,
5735 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5737 WANTED_CODE is this operation code. For single bit fields, we can
5738 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5739 comparison for one-bit fields. */
5760 /* Start by getting the comparison codes. Fail if anything is volatile.
5761 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5762 it were surrounded with a NE_EXPR. */
5771 {
5775 }
5778 {
5782 }
5793 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5796 {
5799 {
5804 }
5807 {
5813 }
5814 }
5819 /* If the RHS can be evaluated unconditionally and its operands are
5820 simple, it wins to evaluate the RHS unconditionally on machines
5821 with expensive branches. In this case, this isn't a comparison
5822 that can be merged. */
5829 {
5830 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5841 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5851 }
5853 /* See if the comparisons can be merged. Then get all the parameters for
5854 each side. */
5879 /* It must be true that the inner operation on the lhs of each
5880 comparison must be the same if we are to be able to do anything.
5881 Then see if we have constants. If not, the same must be true for
5882 the rhs's. */
5891 {
5894 }
5899 else
5902 /* If either comparison code is not correct for our logical operation,
5903 fail. However, we can convert a one-bit comparison against zero into
5904 the opposite comparison against that bit being set in the field. */
5908 {
5910 {
5911 /* Make the left operand unsigned, since we are only interested
5912 in the value of one bit. Otherwise we are doing the wrong
5913 thing below. */
5916 }
5917 else
5919 }
5921 /* This is analogous to the code for l_const above. */
5923 {
5925 {
5928 }
5929 else
5931 }
5933 /* See if we can find a mode that contains both fields being compared on
5934 the left. If we can't, fail. Otherwise, update all constants and masks
5935 to be relative to a field of that size. */
5949 {
5952 }
5960 {
5967 {
5971 }
5972 }
5974 {
5981 {
5985 }
5986 }
5988 /* If the right sides are not constant, do the same for it. Also,
5989 disallow this optimization if a size or signedness mismatch occurs
5990 between the left and right sides. */
5992 {
5995 /* Make sure the two fields on the right
5996 correspond to the left without being swapped. */
6013 {
6016 }
6025 /* Make a mask that corresponds to both fields being compared.
6026 Do this for both items being compared. If the operands are the
6027 same size and the bits being compared are in the same position
6028 then we can do this by masking both and comparing the masked
6029 results. */
6036 {
6050 }
6052 /* There is still another way we can do something: If both pairs of
6053 fields being compared are adjacent, we may be able to make a wider
6054 field containing them both.
6056 Note that we still must mask the lhs/rhs expressions. Furthermore,
6057 the mask must be shifted to account for the shift done by
6058 make_bit_field_ref. */
6067 {
6068 tree type;
6084 /* Convert to the smaller type before masking out unwanted bits. */
6087 {
6089 {
6093 }
6095 {
6099 }
6100 }
6109 }
6112 }
6114 /* Handle the case of comparisons with constants. If there is something in
6115 common between the masks, those bits of the constants must be the same.
6116 If not, the condition is always false. Test for this to avoid generating
6117 incorrect code below. */
6122 {
6124 {
6127 }
6128 else
6129 {
6132 }
6133 }
6138 /* Construct the expression we will return. First get the component
6139 reference we will make. Unless the mask is all ones the width of
6140 that field, perform the mask operation. Then compare with the
6141 merged constant. */
6152 }
6153 \f
6154 /* T is an integer expression that is being multiplied, divided, or taken a
6155 modulus (CODE says which and what kind of divide or modulus) by a
6156 constant C. See if we can eliminate that operation by folding it with
6157 other operations already in T. WIDE_TYPE, if non-null, is a type that
6158 should be used for the computation if wider than our type.
6160 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6161 (X * 2) + (Y * 4). We must, however, be assured that either the original
6162 expression would not overflow or that overflow is undefined for the type
6163 in the language in question.
6165 If we return a non-null expression, it is an equivalent form of the
6166 original computation, but need not be in the original type.
6168 We set *STRICT_OVERFLOW_P to true if the return values depends on
6169 signed overflow being undefined. Otherwise we do not change
6170 *STRICT_OVERFLOW_P. */
6172 static tree
6175 {
6176 /* To avoid exponential search depth, refuse to allow recursion past
6177 three levels. Beyond that (1) it's highly unlikely that we'll find
6178 something interesting and (2) we've probably processed it before
6179 when we built the inner expression. */
6182 tree ret;
6187 depth++;
6189 depth--;
6192 }
6194 static tree
6197 {
6209 /* Don't deal with constants of zero here; they confuse the code below. */
6219 /* Note that we need not handle conditional operations here since fold
6220 already handles those cases. So just do arithmetic here. */
6222 {
6224 /* For a constant, we can always simplify if we are a multiply
6225 or (for divide and modulus) if it is a multiple of our constant. */
6229 {
6232 /* If the multiplication overflowed, we lost information on it.
6233 See PR68142 and PR69845. */
6237 }
6241 /* If op0 is an expression ... */
6247 /* ... and has wrapping overflow, and its type is smaller
6248 than ctype, then we cannot pass through as widening. */
6253 /* ... or this is a truncation (t is narrower than op0),
6254 then we cannot pass through this narrowing. */
6257 /* ... or signedness changes for division or modulus,
6258 then we cannot pass through this conversion. */
6262 /* ... or has undefined overflow while the converted to
6263 type has not, we cannot do the operation in the inner type
6264 as that would introduce undefined overflow. */
6270 /* Pass the constant down and see if we can make a simplification. If
6271 we can, replace this expression with the inner simplification for
6272 possible later conversion to our or some other type. */
6283 /* If widening the type changes it from signed to unsigned, then we
6284 must avoid building ABS_EXPR itself as unsigned. */
6286 {
6290 {
6293 }
6295 }
6296 /* If the constant is negative, we cannot simplify this. */
6299 /* FALLTHROUGH */
6301 /* For division and modulus, type can't be unsigned, as e.g.
6302 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6303 For signed types, even with wrapping overflow, this is fine. */
6312 /* If widening the type changes the signedness, then we can't perform
6313 this optimization as that changes the result. */
6317 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6323 {
6330 }
6334 /* If the second operand is constant, this is a multiplication
6335 or floor division, by a power of two, so we can treat it that
6336 way unless the multiplier or divisor overflows. Signed
6337 left-shift overflow is implementation-defined rather than
6338 undefined in C90, so do not convert signed left shift into
6339 multiplication. */
6342 /* const_binop may not detect overflow correctly,
6343 so check for it explicitly here. */
6352 ctype,
6354 t1),
6359 /* See if we can eliminate the operation on both sides. If we can, we
6360 can return a new PLUS or MINUS. If we can't, the only remaining
6361 cases where we can do anything are if the second operand is a
6362 constant. */
6369 /* If not multiplication, we can only do this if both operands
6370 are divisible by c. */
6373 {
6378 }
6380 /* If this was a subtraction, negate OP1 and set it to be an addition.
6381 This simplifies the logic below. */
6383 {
6385 /* If OP1 was not easily negatable, the constant may be OP0. */
6387 {
6390 }
6391 }
6396 /* If either OP1 or C are negative, this optimization is not safe for
6397 some of the division and remainder types while for others we need
6398 to change the code. */
6400 {
6408 }
6410 /* If it's a multiply or a division/modulus operation of a multiple
6411 of our constant, do the operation and verify it doesn't overflow. */
6415 {
6418 /* We allow the constant to overflow with wrapping semantics. */
6422 }
6423 else
6426 /* If we have an unsigned type, we cannot widen the operation since it
6427 will change the result if the original computation overflowed. */
6431 /* The last case is if we are a multiply. In that case, we can
6432 apply the distributive law to commute the multiply and addition
6433 if the multiplication of the constants doesn't overflow
6434 and overflow is defined. With undefined overflow
6435 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6441 op1);
6446 /* We have a special case here if we are doing something like
6447 (C * 8) % 4 since we know that's zero. */
6450 /* If the multiplication can overflow we cannot optimize this. */
6455 {
6458 }
6460 /* ... fall through ... */
6464 /* If we can extract our operation from the LHS, do so and return a
6465 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6466 do something only if the second operand is a constant. */
6482 /* If these are the same operation types, we can associate them
6483 assuming no overflow. */
6485 {
6500 }
6502 /* If these operations "cancel" each other, we have the main
6503 optimizations of this pass, which occur when either constant is a
6504 multiple of the other, in which case we replace this with either an
6505 operation or CODE or TCODE.
6507 If we have an unsigned type, we cannot do this since it will change
6508 the result if the original computation overflowed. */
6515 {
6518 {
6525 }
6528 {
6535 }
6536 }
6541 }
6544 }
6545 \f
6546 /* Return a node which has the indicated constant VALUE (either 0 or
6547 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6548 and is of the indicated TYPE. */
6550 tree
6552 {
6561 else
6563 }
6566 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6567 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6568 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6569 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6570 COND is the first argument to CODE; otherwise (as in the example
6571 given here), it is the second argument. TYPE is the type of the
6572 original expression. Return NULL_TREE if no simplification is
6573 possible. */
6575 static tree
6580 {
6590 {
6594 /* If this operand throws an expression, then it does not make
6595 sense to try to perform a logical or arithmetic operation
6596 involving it. */
6601 }
6604 {
6609 }
6610 else
6611 /* Detect the case of mixing vector and scalar types - bail out. */
6617 /* This transformation is only worthwhile if we don't have to wrap ARG
6618 in a SAVE_EXPR and the operation can be simplified without recursing
6619 on at least one of the branches once its pushed inside the COND_EXPR. */
6628 {
6632 else
6634 }
6636 {
6640 else
6642 }
6644 /* Check that we have simplified at least one of the branches. */
6649 }
6651 \f
6652 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6654 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6655 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6656 ADDEND is the same as X.
6658 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6659 and finite. The problematic cases are when X is zero, and its mode
6660 has signed zeros. In the case of rounding towards -infinity,
6661 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6662 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6664 bool
6666 {
6670 /* Don't allow the fold with -fsignaling-nans. */
6674 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6678 /* In a vector or complex, we would need to check the sign of all zeros. */
6682 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6686 /* The mode has signed zeros, and we have to honor their sign.
6687 In this situation, there is only one case we can return true for.
6688 X - 0 is the same as X unless rounding towards -infinity is
6689 supported. */
6691 }
6693 /* Subroutine of match.pd that optimizes comparisons of a division by
6694 a nonzero integer constant against an integer constant, i.e.
6695 X/C1 op C2.
6697 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6698 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6700 enum tree_code
6703 {
6708 /* We have to do this the hard way to detect unsigned overflow.
6709 prod = int_const_binop (MULT_EXPR, c1, c2); */
6715 {
6719 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6722 }
6724 {
6727 {
6746 }
6747 }
6748 else
6749 {
6750 /* A negative divisor reverses the relational operators. */
6755 {
6774 }
6775 }
6788 }
6791 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6792 equality/inequality test, then return a simplified form of the test
6793 using a sign testing. Otherwise return NULL. TYPE is the desired
6794 result type. */
6796 static tree
6799 tree result_type)
6800 {
6801 /* If this is testing a single bit, we can optimize the test. */
6805 {
6806 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6807 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6811 /* This is only a win if casting to a signed type is cheap,
6812 i.e. when arg00's type is not a partial mode. */
6814 {
6817 result_type,
6820 }
6821 }
6824 }
6826 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6827 equality/inequality test, then return a simplified form of
6828 the test using shifts and logical operations. Otherwise return
6829 NULL. TYPE is the desired result type. */
6831 tree
6834 {
6835 /* If this is testing a single bit, we can optimize the test. */
6839 {
6848 /* First, see if we can fold the single bit test into a sign-bit
6849 test. */
6851 result_type);
6855 /* Otherwise we have (A & C) != 0 where C is a single bit,
6856 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6857 Similarly for (A & C) == 0. */
6859 /* If INNER is a right shift of a constant and it plus BITNUM does
6860 not overflow, adjust BITNUM and INNER. */
6866 {
6869 }
6871 /* If we are going to be able to omit the AND below, we must do our
6872 operations as unsigned. If we must use the AND, we have a choice.
6873 Normally unsigned is faster, but for some machines signed is. */
6891 /* Put the AND last so it can combine with more things. */
6894 /* Make sure to return the proper type. */
6898 }
6900 }
6902 /* Test whether it is preferable two swap two operands, ARG0 and
6903 ARG1, for example because ARG0 is an integer constant and ARG1
6904 isn't. */
6906 bool
6908 {
6922 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6923 for commutative and comparison operators. Ensuring a canonical
6924 form allows the optimizers to find additional redundancies without
6925 having to explicitly check for both orderings. */
6931 /* Put SSA_NAMEs last. */
6937 /* Put variables last. */
6944 }
6947 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6948 means A >= Y && A != MAX, but in this case we know that
6949 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6951 static tree
6953 {
6960 else
6969 {
6972 }
6974 {
6977 }
6978 else
6985 {
6986 /* Convert the pointer types into integer before taking the difference. */
6990 }
6991 else
6998 }
7000 /* Fold a sum or difference of at least one multiplication.
7001 Returns the folded tree or NULL if no simplification could be made. */
7003 static tree
7006 {
7010 /* (A * C) +- (B * C) -> (A+-B) * C.
7011 (A * C) +- A -> A * (C+-1).
7012 We are most concerned about the case where C is a constant,
7013 but other combinations show up during loop reduction. Since
7014 it is not difficult, try all four possibilities. */
7017 {
7020 }
7022 {
7025 }
7026 else
7027 {
7028 /* We cannot generate constant 1 for fract. */
7033 }
7035 {
7038 }
7040 {
7042 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7043 the purpose of this canonicalization. */
7047 {
7050 }
7051 else
7053 }
7054 else
7055 {
7056 /* We cannot generate constant 1 for fract. */
7061 }
7064 /* Prefer factoring a common non-constant. */
7074 /* No identical multiplicands; see if we can find a common
7075 power-of-two factor in non-power-of-two multiplies. This
7076 can help in multi-dimensional array access. */
7079 {
7082 tree maybe_same;
7086 /* Move min of absolute values to int11. */
7088 {
7093 }
7094 else
7098 /* The remainder should not be a constant, otherwise we
7099 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7100 increased the number of multiplications necessary. */
7102 {
7110 }
7111 }
7118 /* We are neither factoring zero nor minus one. */
7126 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7127 same may be minus one and thus the multiplication may overflow. Perform
7128 the sum operation in an unsigned type. */
7133 /* If the sum evaluated to a constant that is not -INF the multiplication
7134 cannot overflow. */
7141 /* Do not resort to unsigned multiplication because
7142 we lose the no-overflow property of the expression. */
7144 }
7146 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7147 specified by EXPR into the buffer PTR of length LEN bytes.
7148 Return the number of bytes placed in the buffer, or zero
7149 upon failure. */
7151 static int
7153 {
7165 /* Dry run. */
7171 {
7173 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7174 number of bytes. */
7178 {
7185 else
7187 }
7188 else
7192 }
7194 }
7197 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7198 specified by EXPR into the buffer PTR of length LEN bytes.
7199 Return the number of bytes placed in the buffer, or zero
7200 upon failure. */
7202 static int
7204 {
7208 FIXED_VALUE_TYPE value;
7223 }
7226 /* Subroutine of native_encode_expr. Encode the REAL_CST
7227 specified by EXPR into the buffer PTR of length LEN bytes.
7228 Return the number of bytes placed in the buffer, or zero
7229 upon failure. */
7231 static int
7233 {
7239 /* There are always 32 bits in each long, no matter the size of
7240 the hosts long. We handle floating point representations with
7241 up to 192 bits. */
7250 /* Dry run. */
7259 {
7264 {
7271 else
7273 }
7274 else
7275 {
7278 {
7279 /* Reverse bytes within each long, or within the entire float
7280 if it's smaller than a long (for HFmode). */
7283 }
7284 }
7289 }
7291 }
7293 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7294 specified by EXPR into the buffer PTR of length LEN bytes.
7295 Return the number of bytes placed in the buffer, or zero
7296 upon failure. */
7298 static int
7300 {
7302 tree part;
7316 }
7319 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7320 specified by EXPR into the buffer PTR of length LEN bytes.
7321 Return the number of bytes placed in the buffer, or zero
7322 upon failure. */
7324 static int
7326 {
7337 {
7339 {
7342 }
7353 }
7355 }
7358 /* Subroutine of native_encode_expr. Encode the STRING_CST
7359 specified by EXPR into the buffer PTR of length LEN bytes.
7360 Return the number of bytes placed in the buffer, or zero
7361 upon failure. */
7363 static int
7365 {
7368 /* Wide-char strings are encoded in target byte-order so native
7369 encoding them is trivial. */
7384 {
7387 {
7390 }
7393 }
7394 else
7397 }
7400 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7401 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7402 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7403 anything, just do a dry run. If OFF is not -1 then start
7404 the encoding at byte offset OFF and encode at most LEN bytes.
7405 Return the number of bytes placed in the buffer, or zero upon failure. */
7407 int
7409 {
7410 /* We don't support starting at negative offset and -1 is special. */
7415 {
7436 }
7437 }
7440 /* Subroutine of native_interpret_expr. Interpret the contents of
7441 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7442 If the buffer cannot be interpreted, return NULL_TREE. */
7444 static tree
7446 {
7456 }
7459 /* Subroutine of native_interpret_expr. Interpret the contents of
7460 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7461 If the buffer cannot be interpreted, return NULL_TREE. */
7463 static tree
7465 {
7468 double_int result;
7469 FIXED_VALUE_TYPE fixed_value;
7479 }
7482 /* Subroutine of native_interpret_expr. Interpret the contents of
7483 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7484 If the buffer cannot be interpreted, return NULL_TREE. */
7486 static tree
7488 {
7492 /* There are always 32 bits in each long, no matter the size of
7493 the hosts long. We handle floating point representations with
7494 up to 192 bits. */
7495 REAL_VALUE_TYPE r;
7505 {
7506 /* Both OFFSET and BYTE index within a long;
7507 bitpos indexes the whole float. */
7510 {
7517 else
7519 }
7520 else
7521 {
7524 {
7525 /* Reverse bytes within each long, or within the entire float
7526 if it's smaller than a long (for HFmode). */
7529 }
7530 }
7534 }
7538 }
7541 /* Subroutine of native_interpret_expr. Interpret the contents of
7542 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7543 If the buffer cannot be interpreted, return NULL_TREE. */
7545 static tree
7547 {
7562 }
7565 /* Subroutine of native_interpret_expr. Interpret the contents of
7566 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7567 If the buffer cannot be interpreted, return NULL_TREE. */
7569 static tree
7571 {
7584 {
7589 }
7591 }
7594 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7595 the buffer PTR of length LEN as a constant of type TYPE. For
7596 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7597 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7598 return NULL_TREE. */
7600 tree
7602 {
7604 {
7626 }
7627 }
7629 /* Returns true if we can interpret the contents of a native encoding
7630 as TYPE. */
7632 static bool
7634 {
7636 {
7649 }
7650 }
7653 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7654 TYPE at compile-time. If we're unable to perform the conversion
7655 return NULL_TREE. */
7657 static tree
7659 {
7660 /* We support up to 512-bit values (for V8DFmode). */
7664 /* Check that the host and target are sane. */
7673 }
7675 /* Build an expression for the address of T. Folds away INDIRECT_REF
7676 to avoid confusing the gimplify process. */
7678 tree
7680 {
7681 /* The size of the object is not relevant when talking about its address. */
7686 {
7691 }
7701 {
7706 }
7707 else
7711 }
7713 /* Build an expression for the address of T. */
7715 tree
7717 {
7721 }
7723 /* Fold a unary expression of code CODE and type TYPE with operand
7724 OP0. Return the folded expression if folding is successful.
7725 Otherwise, return NULL_TREE. */
7727 tree
7729 {
7730 tree tem;
7731 tree arg0;
7739 {
7742 {
7743 /* Don't use STRIP_NOPS, because signedness of argument type
7744 matters. */
7746 }
7747 else
7748 {
7749 /* Strip any conversions that don't change the mode. This
7750 is safe for every expression, except for a comparison
7751 expression because its signedness is derived from its
7752 operands.
7754 Note that this is done as an internal manipulation within
7755 the constant folder, in order to find the simplest
7756 representation of the arguments so that their form can be
7757 studied. In any cases, the appropriate type conversions
7758 should be put back in the tree that will get out of the
7759 constant folder. */
7761 }
7764 {
7767 {
7771 }
7772 }
7773 }
7780 {
7787 {
7801 /* If this was a conversion, and all we did was to move into
7802 inside the COND_EXPR, bring it back out. But leave it if
7803 it is a conversion from integer to integer and the
7804 result precision is no wider than a word since such a
7805 conversion is cheap and may be optimized away by combine,
7806 while it couldn't if it were outside the COND_EXPR. Then return
7807 so we don't get into an infinite recursion loop taking the
7808 conversion out and then back in. */
7820 && (INTEGRAL_TYPE_P
7833 }
7834 }
7837 {
7843 CASE_CONVERT:
7847 {
7848 /* If we have (type) (a CMP b) and type is an integral type, return
7849 new expression involving the new type. Canonicalize
7850 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7851 non-integral type.
7852 Do not fold the result as that would not simplify further, also
7853 folding again results in recursions. */
7863 }
7865 /* Handle (T *)&A.B.C for A being of type T and B and C
7866 living at offset zero. This occurs frequently in
7867 C++ upcasting and then accessing the base. */
7871 {
7873 tree offset;
7874 machine_mode mode;
7876 tree base
7880 /* If the reference was to a (constant) zero offset, we can use
7881 the address of the base if it has the same base type
7882 as the result type and the pointer type is unqualified. */
7890 }
7894 /* Detect assigning a bitfield. */
7896 && DECL_BIT_FIELD
7898 {
7899 /* Don't leave an assignment inside a conversion
7900 unless assigning a bitfield. */
7902 /* First do the assignment, then return converted constant. */
7907 }
7909 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7910 constants (if x has signed type, the sign bit cannot be set
7911 in c). This folds extension into the BIT_AND_EXPR.
7912 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7913 very likely don't have maximal range for their precision and this
7914 transformation effectively doesn't preserve non-maximal ranges. */
7918 {
7929 <= HOST_BITS_PER_WIDE_INT
7931 {
7935 cst &= HOST_WIDE_INT_M1U
7939 && !flag_syntax_only
7942 {
7946 }
7947 }
7949 {
7954 }
7955 }
7957 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7958 cast (T1)X will fold away. We assume that this happens when X itself
7959 is a cast. */
7963 {
7967 return fold_build_pointer_plus_loc
7969 }
7971 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7972 of the same precision, and X is an integer type not narrower than
7973 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7979 {
7985 }
7987 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7988 type of X and Y (integer types only). */
7993 {
7994 /* Be careful not to introduce new overflows. */
7995 tree mult_type;
7998 else
8002 {
8009 }
8010 }
8016 {
8023 }
8034 /* Convert fabs((double)float) into (double)fabsf(float). */
8037 {
8043 targ0));
8044 }
8048 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8067 /* Note that the operand of this must be an int
8068 and its values must be 0 or 1.
8069 ("true" is a fixed value perhaps depending on the language,
8070 but we don't handle values other than 1 correctly yet.) */
8077 /* Fold *&X to X if X is an lvalue. */
8079 {
8086 }
8092 }
8095 /* If the operation was a conversion do _not_ mark a resulting constant
8096 with TREE_OVERFLOW if the original constant was not. These conversions
8097 have implementation defined behavior and retaining the TREE_OVERFLOW
8098 flag here would confuse later passes such as VRP. */
8099 tree
8102 {
8111 }
8113 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8114 operands OP0 and OP1. LOC is the location of the resulting expression.
8115 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8116 Return the folded expression if folding is successful. Otherwise,
8117 return NULL_TREE. */
8118 static tree
8121 {
8122 tree tem;
8124 /* We only do these simplifications if we are optimizing. */
8128 /* Check for things like (A || B) && (A || C). We can convert this
8129 to A || (B && C). Note that either operator can be any of the four
8130 truth and/or operations and the transformation will still be
8131 valid. Also note that we only care about order for the
8132 ANDIF and ORIF operators. If B contains side effects, this
8133 might change the truth-value of A. */
8140 {
8160 /* This case if tricky because we must either have commutative
8161 operators or else A10 must not have side-effects. */
8167 a01);
8168 }
8170 /* See if we can build a range comparison. */
8176 {
8180 }
8184 {
8188 }
8190 /* Check for the possibility of merging component references. If our
8191 lhs is another similar operation, try to merge its rhs with our
8192 rhs. Then try to merge our lhs and rhs. */
8202 && !flag_sanitize_coverage
8207 {
8214 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8215 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8216 We don't want to pack more than two leafs to a non-IF AND/OR
8217 expression.
8218 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8219 equal to IF-CODE, then we don't want to add right-hand operand.
8220 If the inner right-hand side of left-hand operand has
8221 side-effects, or isn't simple, then we can't add to it,
8222 as otherwise we might destroy if-sequence. */
8225 /* Needed for sequence points to handle trappings, and
8226 side-effects. */
8228 {
8230 arg1);
8232 tem);
8233 }
8234 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8235 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8238 /* Needed for sequence points to handle trappings, and
8239 side-effects. */
8241 {
8246 }
8247 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8248 into (A OR B).
8249 For sequence point consistancy, we need to check for trapping,
8250 and side-effects. */
8254 }
8257 }
8259 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8260 by changing CODE to reduce the magnitude of constants involved in
8261 ARG0 of the comparison.
8262 Returns a canonicalized comparison tree if a simplification was
8263 possible, otherwise returns NULL_TREE.
8264 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8265 valid if signed overflow is undefined. */
8267 static tree
8271 {
8276 /* Match A +- CST code arg1. We can change this only if overflow
8277 is undefined. */
8280 /* In principle pointers also have undefined overflow behavior,
8281 but that causes problems elsewhere. */
8288 /* Identify the constant in arg0 and its sign. */
8292 /* Overflowed constants and zero will cause problems. */
8297 /* See if we can reduce the magnitude of the constant in
8298 arg0 by changing the comparison code. */
8299 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8303 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8307 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8311 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8315 else
8319 /* Now build the constant reduced in magnitude. But not if that
8320 would produce one outside of its types range. */
8336 }
8338 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8339 overflow further. Try to decrease the magnitude of constants involved
8340 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8341 and put sole constants at the second argument position.
8342 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8344 static tree
8347 {
8348 tree t;
8353 /* Try canonicalization by simplifying arg0. */
8358 {
8362 }
8364 /* Try canonicalization by simplifying arg1 using the swapped
8365 comparison. */
8373 }
8375 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8376 space. This is used to avoid issuing overflow warnings for
8377 expressions like &p->x which can not wrap. */
8379 static bool
8381 {
8388 poly_wide_int wi_offset;
8394 else
8399 precision);
8414 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8415 array. */
8424 }
8426 /* Return a positive integer when the symbol DECL is known to have
8427 a nonzero address, zero when it's known not to (e.g., it's a weak
8428 symbol), and a negative integer when the symbol is not yet in the
8429 symbol table and so whether or not its address is zero is unknown.
8430 For function local objects always return positive integer. */
8431 static int
8433 {
8438 /* Function local objects are never NULL. */
8446 }
8448 /* Subroutine of fold_binary. This routine performs all of the
8449 transformations that are common to the equality/inequality
8450 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8451 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8452 fold_binary should call fold_binary. Fold a comparison with
8453 tree code CODE and type TYPE with operands OP0 and OP1. Return
8454 the folded comparison or NULL_TREE. */
8456 static tree
8459 {
8469 /* For comparisons of pointers we can decompose it to a compile time
8470 comparison of the base objects and the offsets into the object.
8471 This requires at least one operand being an ADDR_EXPR or a
8472 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8478 {
8481 machine_mode mode;
8485 /* Get base and offset for the access. Strip ADDR_EXPR for
8486 get_inner_reference, but put it back by stripping INDIRECT_REF
8487 off the base object if possible. indirect_baseN will be true
8488 if baseN is not an address but refers to the object itself. */
8491 {
8492 base0
8498 else
8500 }
8502 {
8506 {
8507 base0
8513 else
8515 }
8518 else
8522 {
8529 }
8530 }
8534 {
8535 base1
8541 else
8543 }
8545 {
8549 {
8550 base1
8556 else
8558 }
8561 else
8565 {
8572 }
8573 }
8575 /* If we have equivalent bases we might be able to simplify. */
8579 {
8580 /* We can fold this expression to a constant if the non-constant
8581 offset parts are equal. */
8585 && (equality_code
8586 || (indirect_base0
8589 {
8595 "occur when comparing P +- C1 with "
8597 WARN_STRICT_OVERFLOW_CONDITIONAL);
8600 {
8638 }
8639 }
8640 /* We can simplify the comparison to a comparison of the variable
8641 offset parts if the constant offset parts are equal.
8642 Be careful to use signed sizetype here because otherwise we
8643 mess with array offsets in the wrong way. This is possible
8644 because pointer arithmetic is restricted to retain within an
8645 object and overflow on pointer differences is undefined as of
8646 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8648 && (equality_code
8649 || (indirect_base0
8652 {
8653 /* By converting to signed sizetype we cover middle-end pointer
8654 arithmetic which operates on unsigned pointer types of size
8655 type size and ARRAY_REF offsets which are properly sign or
8656 zero extended from their type in case it is narrower than
8657 sizetype. */
8660 else
8664 else
8671 "occur when comparing P +- C1 with "
8673 WARN_STRICT_OVERFLOW_COMPARISON);
8676 }
8677 }
8678 /* For equal offsets we can simplify to a comparison of the
8679 base addresses. */
8681 && (indirect_base0
8683 && (indirect_base1
8688 {
8694 }
8695 /* Comparison between an ordinary (non-weak) symbol and a null
8696 pointer can be eliminated since such symbols must have a non
8697 null address. In C, relational expressions between pointers
8698 to objects and null pointers are undefined. The results
8699 below follow the C++ rules with the additional property that
8700 every object pointer compares greater than a null pointer.
8701 */
8704 /* Avoid folding references to struct members at offset 0 to
8705 prevent tests like '&ptr->firstmember == 0' from getting
8706 eliminated. When ptr is null, although the -> expression
8707 is strictly speaking invalid, GCC retains it as a matter
8708 of QoI. See PR c/44555. */
8711 && indirect_base0
8712 /* The caller guarantees that when one of the arguments is
8713 constant (i.e., null in this case) it is second. */
8715 {
8717 {
8728 }
8729 }
8730 }
8732 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8733 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8734 the resulting offset is smaller in absolute value than the
8735 original one and has the same sign. */
8744 {
8749 tree cst;
8751 "occur when combining constants around "
8754 /* Put the constant on the side where it doesn't overflow and is
8755 of lower absolute value and of same sign than before. */
8762 {
8765 variable1,
8769 }
8777 {
8783 variable2);
8784 }
8785 }
8791 /* If we are comparing an expression that just has comparisons
8792 of two integer values, arithmetic expressions of those comparisons,
8793 and constants, we can simplify it. There are only three cases
8794 to check: the two values can either be equal, the first can be
8795 greater, or the second can be greater. Fold the expression for
8796 those three values. Since each value must be 0 or 1, we have
8797 eight possibilities, each of which corresponds to the constant 0
8798 or 1 or one of the six possible comparisons.
8800 This handles common cases like (a > b) == 0 but also handles
8801 expressions like ((x > y) - (y > x)) > 0, which supposedly
8802 occur in macroized code. */
8805 {
8809 /* Don't handle degenerate cases here; they should already
8810 have been handled anyway. */
8819 {
8823 /* We can't just pass T to eval_subst in case cval1 or cval2
8824 was the same as ARG1. */
8826 tree high_result
8830 arg1);
8831 tree equal_result
8835 arg1);
8836 tree low_result
8840 arg1);
8842 /* All three of these results should be 0 or 1. Confirm they are.
8843 Then use those values to select the proper code to use. */
8848 {
8849 /* Make a 3-bit mask with the high-order bit being the
8850 value for `>', the next for '=', and the low for '<'. */
8854 {
8856 /* Always false. */
8877 /* Always true. */
8879 }
8882 }
8883 }
8884 }
8887 }
8890 /* Subroutine of fold_binary. Optimize complex multiplications of the
8891 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8892 argument EXPR represents the expression "z" of type TYPE. */
8894 static tree
8896 {
8901 {
8904 }
8906 {
8909 }
8910 else
8911 {
8915 }
8924 }
8927 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8928 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8929 true if successful. */
8931 static bool
8933 {
8938 {
8941 }
8943 {
8949 else
8951 }
8952 else
8958 }
8960 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8961 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8962 NULL_TREE otherwise. */
8964 static tree
8966 {
8987 {
8988 HOST_WIDE_INT index;
8994 }
8997 {
9003 }
9004 else
9006 }
9008 /* Try to fold a pointer difference of type TYPE two address expressions of
9009 array references AREF0 and AREF1 using location LOC. Return a
9010 simplified expression for the difference or NULL_TREE. */
9012 static tree
9016 {
9021 /* If the bases are array references as well, recurse. If the bases
9022 are pointer indirections compute the difference of the pointers.
9023 If the bases are equal, we are set. */
9026 && (base_offset
9028 use_pointer_diff)))
9031 && (base_offset
9032 = use_pointer_diff
9042 {
9048 base_offset,
9051 }
9053 }
9055 /* If the real or vector real constant CST of type TYPE has an exact
9056 inverse, return it, else return NULL. */
9058 tree
9060 {
9061 REAL_VALUE_TYPE r;
9062 tree unit_type;
9063 machine_mode mode;
9066 {
9076 {
9080 tree_vector_builder elts;
9085 {
9090 }
9093 }
9097 }
9098 }
9100 /* Mask out the tz least significant bits of X of type TYPE where
9101 tz is the number of trailing zeroes in Y. */
9102 static wide_int
9104 {
9109 }
9111 /* Return true when T is an address and is known to be nonzero.
9112 For floating point we further ensure that T is not denormal.
9113 Similar logic is present in nonzero_address in rtlanal.h.
9115 If the return value is based on the assumption that signed overflow
9116 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9117 change *STRICT_OVERFLOW_P. */
9119 static bool
9121 {
9125 /* Doing something useful for floating point would need more work. */
9131 {
9134 strict_overflow_p);
9140 strict_overflow_p);
9148 }
9151 {
9154 strict_overflow_p);
9162 strict_overflow_p);
9177 strict_overflow_p);
9181 strict_overflow_p);
9184 {
9196 }
9200 }
9202 }
9204 /* Return true when T is an address and is known to be nonzero.
9205 Handle warnings about undefined signed overflow. */
9207 bool
9209 {
9216 "determining that expression is always "
9218 WARN_STRICT_OVERFLOW_MISC);
9220 }
9222 /* Return true if T is known not to be equal to an integer W. */
9224 bool
9226 {
9228 value_range_type rtype;
9230 {
9239 {
9244 }
9249 /* If T has some known zero bits and W has any of those bits set,
9250 then T is known not to be equal to W. */
9258 }
9259 }
9261 /* Fold a binary expression of code CODE and type TYPE with operands
9262 OP0 and OP1. LOC is the location of the resulting expression.
9263 Return the folded expression if folding is successful. Otherwise,
9264 return NULL_TREE. */
9266 tree
9269 {
9284 /* Strip any conversions that don't change the mode. This is
9285 safe for every expression, except for a comparison expression
9286 because its signedness is derived from its operands. So, in
9287 the latter case, only strip conversions that don't change the
9288 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9289 preserved.
9291 Note that this is done as an internal manipulation within the
9292 constant folder, in order to find the simplest representation
9293 of the arguments so that their form can be studied. In any
9294 cases, the appropriate type conversions should be put back in
9295 the tree that will get out of the constant folder. */
9298 {
9301 }
9302 else
9303 {
9306 }
9308 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9309 constant but we can't do arithmetic on them. */
9311 {
9314 {
9318 }
9319 }
9321 /* If this is a commutative operation, and ARG0 is a constant, move it
9322 to ARG1 to reduce the number of tests below. */
9327 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9328 to ARG1 to reduce the number of tests below. */
9337 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9339 First check for cases where an arithmetic operation is applied to a
9340 compound, conditional, or comparison operation. Push the arithmetic
9341 operation inside the compound or conditional to see if any folding
9342 can then be done. Convert comparison to conditional for this purpose.
9343 The also optimizes non-constant cases that used to be done in
9344 expand_expr.
9346 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9347 one of the operands is a comparison and the other is a comparison, a
9348 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9349 code below would make the expression more complex. Change it to a
9350 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9351 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9364 {
9368 boolean_type_node,
9376 }
9380 {
9382 {
9387 tem);
9388 }
9390 {
9395 tem);
9396 }
9401 {
9407 }
9412 {
9418 }
9419 }
9422 {
9424 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9427 {
9433 }
9435 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9438 {
9439 tree base;
9440 poly_int64 coffset;
9449 }
9454 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9460 arg1),
9462 arg0)));
9468 {
9469 /* X + (X / CST) * -CST is X % CST. */
9474 {
9483 cst0));
9484 }
9485 }
9487 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9488 one. Make sure the type is not saturating and has the signedness of
9489 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9490 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9497 {
9501 }
9504 {
9505 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9506 (plus (plus (mult) (mult)) (foo)) so that we can
9507 take advantage of the factoring cases below. */
9516 {
9522 else
9535 parg0),
9537 marg)),
9541 return
9547 parg1)));
9548 }
9549 }
9550 else
9551 {
9552 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9553 to __complex__ ( x, y ). This is not the same for SNaNs or
9554 if signed zeros are involved. */
9558 {
9565 {
9569 {
9575 }
9577 {
9583 }
9584 }
9585 }
9587 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9588 We associate floats only if the user has specified
9589 -fassociative-math. */
9593 {
9598 {
9599 tree tree0;
9602 }
9603 }
9604 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9605 We associate floats only if the user has specified
9606 -fassociative-math. */
9610 {
9615 {
9616 tree tree0;
9619 }
9620 }
9621 }
9623 bit_rotate:
9624 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9625 is a rotate of A by C1 bits. */
9626 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9627 is a rotate of A by B bits.
9628 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9629 though in this case CODE must be | and not + or ^, otherwise
9630 it doesn't return A when B is 0. */
9631 {
9633 tree rtype;
9642 /* Only create rotates in complete modes. Other cases are not
9643 expanded properly. */
9646 {
9659 {
9664 }
9669 {
9672 code0 == LSHIFT_EXPR
9675 }
9677 {
9687 {
9691 orig_tree01);
9693 }
9694 }
9698 {
9709 {
9713 orig_tree01);
9715 }
9716 }
9717 }
9718 }
9720 associate:
9721 /* In most languages, can't associate operations on floats through
9722 parentheses. Rather than remember where the parentheses were, we
9723 don't associate floats at all, unless the user has specified
9724 -fassociative-math.
9725 And, we need to make sure type is not saturating. */
9729 {
9735 /* Split both trees into variables, constants, and literals. Then
9736 associate each group together, the constants with literals,
9737 then the result with variables. This increases the chances of
9738 literals being recombined later and of generating relocatable
9739 expressions for the sum of a constant and literal. */
9747 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9751 /* With undefined overflow prefer doing association in a type
9752 which wraps on overflow, if that is one of the operand types. */
9755 {
9763 }
9765 /* With undefined overflow we can only associate constants with one
9766 variable, and constants whose association doesn't overflow. */
9769 {
9771 {
9772 /* ??? If split_tree would handle NEGATE_EXPR we could
9773 simply reject these cases and the allowed cases would
9774 be the var0/minus_var1 ones. */
9780 {
9783 }
9790 {
9793 }
9799 /* The only case we can still associate with two variables
9800 is if they cancel out. */
9804 }
9810 }
9812 /* Only do something if we found more than two objects. Otherwise,
9813 nothing has changed and we risk infinite recursion. */
9821 {
9833 {
9837 }
9839 {
9843 }
9845 /* Preserve the MINUS_EXPR if the negative part of the literal is
9846 greater than the positive part. Otherwise, the multiplicative
9847 folding code (i.e extract_muldiv) may be fooled in case
9848 unsigned constants are subtracted, like in the following
9849 example: ((X*2 + 4) - 8U)/2. */
9851 {
9855 /* But avoid ending up with only negated parts. */
9857 {
9861 }
9862 else
9863 {
9867 }
9868 }
9870 /* Don't introduce overflows through reassociation. */
9875 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9882 /* Eliminate minus_con0. */
9884 {
9891 else
9894 }
9896 /* Eliminate minus_var0. */
9898 {
9902 else
9905 }
9907 return
9910 }
9911 }
9917 /* Fold &a[i] - &a[j] to i-j. */
9922 {
9926 code
9930 }
9932 /* Further transformations are not for pointers. */
9936 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9939 /* If arg0 is e.g. unsigned int and type is int, then this could
9940 introduce UB, because if A is INT_MIN at runtime, the original
9941 expression can be well defined while the latter is not.
9942 See PR83269. */
9951 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9952 __complex__ ( x, -y ). This is not the same for SNaNs or if
9953 signed zeros are involved. */
9957 {
9964 {
9968 {
9970 arg1r ? arg1r
9975 }
9977 {
9981 arg1i ? arg1i
9984 }
9985 }
9986 }
9988 /* A - B -> A + (-B) if B is easily negatable. */
9992 /* Avoid this transformation if B is a positive REAL_CST. */
10000 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10001 one. Make sure the type is not saturating and has the signedness of
10002 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10003 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10010 {
10014 }
10020 {
10021 /* Transform x * -C into -x * C if x is easily negatable. */
10036 {
10039 "occur when simplifying "
10041 WARN_STRICT_OVERFLOW_MISC);
10043 }
10045 /* Optimize z * conj(z) for integer complex numbers. */
10052 }
10053 else
10054 {
10055 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10056 This is not the same for NaNs or if signed zeros are
10057 involved. */
10063 {
10066 return
10072 return
10077 }
10079 /* Optimize z * conj(z) for floating point complex numbers.
10080 Guarded by flag_unsafe_math_optimizations as non-finite
10081 imaginary components don't produce scalar results. */
10090 }
10094 /* Canonicalize (X & C1) | C2. */
10098 {
10103 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10111 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10113 {
10116 }
10118 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10119 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10120 mode which allows further optimizations. */
10125 {
10130 {
10133 }
10134 }
10137 {
10142 }
10143 }
10145 /* See if this can be simplified into a rotate first. If that
10146 is unsuccessful continue in the association code. */
10150 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10158 /* See if this can be simplified into a rotate first. If that
10159 is unsuccessful continue in the association code. */
10163 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10168 {
10169 tree tem2;
10176 }
10177 /* Fold ~X & 1 as (X & 1) == 0. */
10181 {
10182 tree tem2;
10189 }
10190 /* Fold !X & 1 as X == 0. */
10193 {
10197 }
10199 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10200 multiple of 1 << CST. */
10202 {
10209 }
10211 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10212 bits from CST2. */
10216 {
10218 wide_int masked
10225 {
10226 /* Avoid the transform if arg1 is a mask of some
10227 mode which allows further optimizations. */
10234 }
10235 }
10237 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10238 ((A & N) + B) & M -> (A + B) & M
10239 Similarly if (N & M) == 0,
10240 ((A | N) + B) & M -> (A + B) & M
10241 and for - instead of + (or unary - instead of +)
10242 and/or ^ instead of |.
10243 If B is constant and (B & M) == 0, fold into A & M. */
10245 {
10254 {
10257 wide_int cst0;
10259 /* Now we know that arg0 is (C + D) or (C - D) or
10260 -C and arg1 (M) is == (1LL << cst) - 1.
10261 Store C into PMOP[0] and D into PMOP[1]. */
10265 {
10268 }
10275 {
10284 {
10287 }
10290 /* If C or D is of the form (A & N) where
10291 (N & M) == M, or of the form (A | N) or
10292 (A ^ N) where (N & M) == 0, replace it with A. */
10296 /* If C or D is a N where (N & M) == 0, it can be
10297 omitted (assumed 0). */
10305 }
10307 /* Only build anything new if we optimized one or both arguments
10308 above. */
10312 {
10315 {
10316 /* Perform the operations in a type that has defined
10317 overflow behavior. */
10323 }
10328 {
10336 else
10338 }
10341 else
10344 /* TEM is now the new binary +, - or unary - replacement. */
10348 }
10349 }
10350 }
10352 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10355 {
10360 return
10362 }
10367 /* Don't touch a floating-point divide by zero unless the mode
10368 of the constant can represent infinity. */
10374 /* (-A) / (-B) -> A / B */
10386 /* Fall through */
10389 /* Simplify A / (B << N) where A and B are positive and B is
10390 a power of 2, to A >> (N + log2(B)). */
10395 {
10398 {
10406 WARN_STRICT_OVERFLOW_MISC);
10412 }
10413 }
10415 /* Fall through */
10423 /* Convert -A / -B to A / B when the type is signed and overflow is
10424 undefined. */
10428 {
10431 "when distributing negation across "
10433 WARN_STRICT_OVERFLOW_MISC);
10438 }
10442 {
10445 "when distributing negation across "
10447 WARN_STRICT_OVERFLOW_MISC);
10452 }
10454 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10455 operation, EXACT_DIV_EXPR.
10457 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10458 At one time others generated faster code, it's not clear if they do
10459 after the last round to changes to the DIV code in expmed.c. */
10470 {
10474 WARN_STRICT_OVERFLOW_MISC);
10476 }
10488 {
10492 WARN_STRICT_OVERFLOW_MISC);
10494 }
10502 /* Since negative shift count is not well-defined,
10503 don't try to compute it in the compiler. */
10509 /* If we have a rotate of a bit operation with the rotate count and
10510 the second operand of the bit operation both constant,
10511 permute the two operations. */
10517 {
10525 }
10527 /* Two consecutive rotates adding up to the some integer
10528 multiple of the precision of the type can be ignored. */
10544 /* Note that the operands of this must be ints
10545 and their values must be 0 or 1.
10546 ("true" is a fixed value perhaps depending on the language.) */
10547 /* If first arg is constant zero, return it. */
10550 /* FALLTHRU */
10552 /* If either arg is constant true, drop it. */
10556 /* Preserve sequence points. */
10559 /* If second arg is constant zero, result is zero, but first arg
10560 must be evaluated. */
10563 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10564 case will be handled here. */
10568 /* !X && X is always false. */
10572 /* X && !X is always false. */
10577 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10578 means A >= Y && A != MAX, but in this case we know that
10579 A < X <= MAX. */
10583 {
10591 }
10600 /* Note that the operands of this must be ints
10601 and their values must be 0 or true.
10602 ("true" is a fixed value perhaps depending on the language.) */
10603 /* If first arg is constant true, return it. */
10606 /* FALLTHRU */
10608 /* If either arg is constant zero, drop it. */
10612 /* Preserve sequence points. */
10615 /* If second arg is constant true, result is true, but we must
10616 evaluate first arg. */
10619 /* Likewise for first arg, but note this only occurs here for
10620 TRUTH_OR_EXPR. */
10624 /* !X || X is always true. */
10628 /* X || !X is always true. */
10633 /* (X && !Y) || (!X && Y) is X ^ Y */
10636 {
10653 }
10662 /* If the second arg is constant zero, drop it. */
10665 /* If the second arg is constant true, this is a logical inversion. */
10667 {
10670 }
10671 /* Identical arguments cancel to zero. */
10675 /* !X ^ X is always true. */
10680 /* X ^ !X is always true. */
10696 /* bool_var != 1 becomes !bool_var. */
10703 /* bool_var == 0 becomes !bool_var. */
10710 /* !exp != 0 becomes !exp */
10715 /* If this is an EQ or NE comparison with zero and ARG0 is
10716 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10717 two operations, but the latter can be done in one less insn
10718 on machines that have only two-operand insns or on which a
10719 constant cannot be the first operand. */
10722 {
10727 {
10734 arg1);
10735 }
10738 {
10745 arg1);
10746 }
10747 }
10749 /* If this is an NE or EQ comparison of zero against the result of a
10750 signed MOD operation whose second operand is a power of 2, make
10751 the MOD operation unsigned since it is simpler and equivalent. */
10759 {
10769 }
10771 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10772 C1 is a valid shift constant, and C2 is a power of two, i.e.
10773 a single bit. */
10777 == INTEGER_CST
10780 {
10785 /* Check for a valid shift count. */
10787 {
10791 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10792 can be rewritten as (X & (C2 << C1)) != 0. */
10794 {
10799 }
10800 /* Otherwise, for signed (arithmetic) shifts,
10801 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10802 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10806 /* Otherwise, of unsigned (logical) shifts,
10807 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10808 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10809 else
10813 arg000);
10814 }
10815 }
10817 /* If this is a comparison of a field, we may be able to simplify it. */
10820 /* Handle the constant case even without -O
10821 to make sure the warnings are given. */
10823 {
10827 }
10829 /* Optimize comparisons of strlen vs zero to a compare of the
10830 first character of the string vs zero. To wit,
10831 strlen(ptr) == 0 => *ptr == 0
10832 strlen(ptr) != 0 => *ptr != 0
10833 Other cases should reduce to one of these two (or a constant)
10834 due to the return value of strlen being unsigned. */
10837 {
10845 {
10850 }
10851 }
10853 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10854 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10858 {
10863 {
10865 {
10868 }
10871 }
10872 }
10874 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10875 (X & C) == 0 when C is a single bit. */
10880 {
10887 arg1));
10888 }
10890 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10891 constant C is a power of two, i.e. a single bit. */
10898 {
10902 }
10904 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10905 when is C is a power of two, i.e. a single bit. */
10912 {
10918 }
10922 {
10925 }
10927 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10930 {
10938 {
10944 }
10946 {
10952 }
10954 {
10960 }
10962 {
10968 }
10969 }
10973 {
10980 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10981 operand_equal_p guarantees no side-effects so we don't need
10982 to use omit_one_operand on Z. */
10986 arg10));
10990 arg11));
10994 arg10));
10998 arg11));
11000 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11003 {
11009 }
11010 }
11012 /* Attempt to simplify equality/inequality comparisons of complex
11013 values. Only lower the comparison if the result is known or
11014 can be simplified to a single scalar comparison. */
11019 {
11024 {
11027 }
11028 else
11029 {
11032 }
11035 {
11038 }
11039 else
11040 {
11043 }
11047 {
11049 {
11054 }
11055 else
11056 {
11061 }
11062 }
11066 {
11068 {
11073 }
11074 else
11075 {
11080 }
11081 }
11082 }
11094 /* Transform comparisons of the form X +- C CMP X. */
11099 {
11104 /* (X - c) > X becomes false. */
11110 /* Likewise (X + c) < X becomes false. */
11116 /* Convert (X - c) <= X to true. */
11123 /* Convert (X + c) >= X to true. */
11129 }
11131 /* If we are comparing an ABS_EXPR with a constant, we can
11132 convert all the cases into explicit comparisons, but they may
11133 well not be faster than doing the ABS and one comparison.
11134 But ABS (X) <= C is a range comparison, which becomes a subtraction
11135 and a comparison, and is probably faster. */
11149 /* Convert ABS_EXPR<x> >= 0 to true. */
11156 {
11159 "when simplifying comparison of "
11161 WARN_STRICT_OVERFLOW_CONDITIONAL);
11164 arg0);
11165 }
11167 /* Convert ABS_EXPR<x> < 0 to false. */
11172 {
11175 "when simplifying comparison of "
11177 WARN_STRICT_OVERFLOW_CONDITIONAL);
11180 arg0);
11181 }
11183 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11184 and similarly for >= into !=. */
11194 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11195 otherwise Y might be >= # of bits in X's type and thus e.g.
11196 (unsigned char) (1 << Y) for Y 15 might be 0.
11197 If the cast is widening, then 1 << Y should have unsigned type,
11198 otherwise if Y is number of bits in the signed shift type minus 1,
11199 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11200 31 might be 0xffffffff80000000. */
11211 {
11217 }
11229 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11230 {
11242 }
11247 /* When pedantic, a compound expression can be neither an lvalue
11248 nor an integer constant expression. */
11251 /* Don't let (0, 0) be null pointer constant. */
11257 /* An ASSERT_EXPR should never be passed to fold_binary. */
11263 }
11265 /* Used by contains_label_[p1]. */
11267 struct contains_label_data
11268 {
11271 };
11273 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11274 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11275 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11277 static tree
11279 {
11282 {
11293 {
11301 }
11310 }
11311 }
11313 /* Return whether the sub-tree ST contains a label which is accessible from
11314 outside the sub-tree. */
11316 static bool
11318 {
11322 }
11324 /* Fold a ternary expression of code CODE and type TYPE with operands
11325 OP0, OP1, and OP2. Return the folded expression if folding is
11326 successful. Otherwise, return NULL_TREE. */
11328 tree
11331 {
11332 tree tem;
11339 /* If this is a commutative operation, and OP0 is a constant, move it
11340 to OP1 to reduce the number of tests below. */
11349 /* Strip any conversions that don't change the mode. This is safe
11350 for every expression, except for a comparison expression because
11351 its signedness is derived from its operands. So, in the latter
11352 case, only strip conversions that don't change the signedness.
11354 Note that this is done as an internal manipulation within the
11355 constant folder, in order to find the simplest representation of
11356 the arguments so that their form can be studied. In any cases,
11357 the appropriate type conversions should be put back in the tree
11358 that will get out of the constant folder. */
11360 {
11363 }
11366 {
11369 }
11372 {
11375 }
11378 {
11382 {
11388 }
11393 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11394 so all simple results must be passed through pedantic_non_lvalue. */
11396 {
11399 /* Only optimize constant conditions when the selected branch
11400 has the same type as the COND_EXPR. This avoids optimizing
11401 away "c ? x : throw", where the throw has a void type.
11402 Avoid throwing away that operand which contains label. */
11409 }
11411 {
11418 {
11421 {
11429 }
11434 }
11435 }
11437 /* If we have A op B ? A : C, we may be able to convert this to a
11438 simpler expression, depending on the operation and the values
11439 of B and C. Signed zeros prevent all of these transformations,
11440 for reasons given above each one.
11442 Also try swapping the arguments and inverting the conditional. */
11446 {
11450 }
11455 {
11459 {
11463 }
11464 }
11466 /* If the second operand is simpler than the third, swap them
11467 since that produces better jump optimization results. */
11470 {
11472 /* See if this can be inverted. If it can't, possibly because
11473 it was a floating-point inequality comparison, don't do
11474 anything. */
11478 }
11480 /* Convert A ? 1 : 0 to simply A. */
11485 /* If we try to convert OP0 to our type, the
11486 call to fold will try to move the conversion inside
11487 a COND, which will recurse. In that case, the COND_EXPR
11488 is probably the best choice, so leave it alone. */
11492 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11493 over COND_EXPR in cases such as floating point comparisons. */
11502 arg0)));
11504 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11509 {
11510 /* sign_bit_p looks through both zero and sign extensions,
11511 but for this optimization only sign extensions are
11512 usable. */
11515 {
11518 {
11521 }
11523 }
11524 /* sign_bit_p only checks ARG1 bits within A's precision.
11525 If <sign bit of A> has wider type than A, bits outside
11526 of A's precision in <sign bit of A> need to be checked.
11527 If they are all 0, this optimization needs to be done
11528 in unsigned A's type, if they are all 1 in signed A's type,
11529 otherwise this can't be done. */
11535 {
11537 tree tem_type;
11550 {
11553 }
11555 {
11558 }
11559 else
11561 }
11564 return
11570 arg1)));
11571 }
11573 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11574 already handled above. */
11579 {
11589 op1);
11590 }
11592 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11593 is probably obsolete because the first operand should be a
11594 truth value (that's why we have the two cases above), but let's
11595 leave it in until we can confirm this for all front-ends. */
11607 /* Disable the transformations below for vectors, since
11608 fold_binary_op_with_conditional_arg may undo them immediately,
11609 yielding an infinite loop. */
11613 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11622 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11627 {
11629 /* Only perform transformation if ARG0 is easily inverted. */
11633 ? BIT_IOR_EXPR
11636 op1);
11637 }
11639 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11644 {
11646 /* Only perform transformation if ARG0 is easily inverted. */
11652 op2);
11653 }
11655 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11667 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11668 of fold_ternary on them. */
11678 {
11689 {
11694 {
11696 {
11701 }
11707 }
11708 }
11709 }
11711 /* On constants we can use native encode/interpret to constant
11712 fold (nearly) all BIT_FIELD_REFs. */
11718 {
11721 /* Limit us to a reasonable amount of work. To relax the
11722 other limitations we need bit-shifting of the buffer
11723 and rounding up the size. */
11727 {
11729 unsigned HOST_WIDE_INT len
11734 {
11739 }
11740 }
11741 }
11747 {
11748 /* Build a vector of integers from the tree mask. */
11749 vec_perm_builder builder;
11753 /* Create a vec_perm_indices for the integer vector. */
11758 /* Check for cases that fold to OP0 or OP1 in their original
11759 element order. */
11766 {
11770 {
11773 }
11774 }
11780 {
11784 }
11788 /* Generate a canonical form of the selector. */
11790 {
11791 /* Some targets are deficient and fail to expand a single
11792 argument permutation while still allowing an equivalent
11793 2-argument version. */
11797 else
11798 {
11802 else
11803 /* Not directly supported with either encoding,
11804 so use the preferred form. */
11806 }
11808 }
11812 }
11816 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11819 {
11825 wide_int tem2
11829 }
11834 {
11836 unsigned HOST_WIDE_INT elsize
11839 {
11845 {
11851 }
11852 }
11853 }
11859 }
11861 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11862 of an array (or vector). */
11864 tree
11866 {
11871 {
11874 {
11875 /* Static constructors for variably sized objects makes no sense. */
11879 }
11880 }
11891 offset_int max_index;
11896 {
11897 /* Array constructor might explicitly set index, or specify a range,
11898 or leave index NULL meaning that it is next index after previous
11899 one. */
11901 {
11904 else
11905 {
11909 }
11910 }
11911 else
11912 {
11918 }
11920 /* Do we have match? */
11924 }
11926 }
11928 /* Perform constant folding and related simplification of EXPR.
11929 The related simplifications include x*1 => x, x*0 => 0, etc.,
11930 and application of the associative law.
11931 NOP_EXPR conversions may be removed freely (as long as we
11932 are careful not to change the type of the overall expression).
11933 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11934 but we can constant-fold them if they have constant operands. */
11936 #ifdef ENABLE_FOLD_CHECKING
11937 # define fold(x) fold_1 (x)
11939 static
11940 #endif
11941 tree
11943 {
11947 tree tem;
11950 /* Return right away if a constant. */
11954 /* CALL_EXPR-like objects with variable numbers of operands are
11955 treated specially. */
11957 {
11959 {
11962 }
11964 }
11967 {
11972 {
11990 }
11991 }
11994 {
11996 {
12003 {
12008 }
12011 }
12013 /* Return a VECTOR_CST if possible. */
12015 {
12021 tree val;
12027 }
12035 }
12037 #ifdef ENABLE_FOLD_CHECKING
12038 #undef fold
12045 /* When --enable-checking=fold, compute a digest of expr before
12046 and after actual fold call to see if fold did not accidentally
12047 change original expr. */
12049 tree
12051 {
12052 tree ret;
12072 }
12074 void
12076 {
12087 }
12089 static void
12091 {
12093 }
12095 static void
12098 {
12104 recursive_label:
12114 {
12115 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12120 }
12128 {
12129 /* Allow these fields to be modified. */
12130 tree tmp;
12139 {
12142 }
12143 }
12154 {
12157 {
12173 }
12177 {
12190 }
12207 {
12213 }
12216 {
12218 {
12221 }
12223 }
12234 {
12237 }
12247 }
12248 }
12250 /* Helper function for outputting the checksum of a tree T. When
12251 debugging with gdb, you can "define mynext" to be "next" followed
12252 by "call debug_fold_checksum (op0)", then just trace down till the
12253 outputs differ. */
12255 DEBUG_FUNCTION void
12257 {
12272 }
12274 #endif
12276 /* Fold a unary tree expression with code CODE of type TYPE with an
12277 operand OP0. LOC is the location of the resulting expression.
12278 Return a folded expression if successful. Otherwise, return a tree
12279 expression with code CODE of type TYPE with an operand OP0. */
12281 tree
12284 {
12285 tree tem;
12286 #ifdef ENABLE_FOLD_CHECKING
12295 #endif
12301 #ifdef ENABLE_FOLD_CHECKING
12308 #endif
12310 }
12312 /* Fold a binary tree expression with code CODE of type TYPE with
12313 operands OP0 and OP1. LOC is the location of the resulting
12314 expression. Return a folded expression if successful. Otherwise,
12315 return a tree expression with code CODE of type TYPE with operands
12316 OP0 and OP1. */
12318 tree
12321 MEM_STAT_DECL)
12322 {
12323 tree tem;
12324 #ifdef ENABLE_FOLD_CHECKING
12341 #endif
12347 #ifdef ENABLE_FOLD_CHECKING
12362 #endif
12364 }
12366 /* Fold a ternary tree expression with code CODE of type TYPE with
12367 operands OP0, OP1, and OP2. Return a folded expression if
12368 successful. Otherwise, return a tree expression with code CODE of
12369 type TYPE with operands OP0, OP1, and OP2. */
12371 tree
12374 {
12375 tree tem;
12376 #ifdef ENABLE_FOLD_CHECKING
12400 #endif
12407 #ifdef ENABLE_FOLD_CHECKING
12430 #endif
12432 }
12434 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12435 arguments in ARGARRAY, and a null static chain.
12436 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12437 of type TYPE from the given operands as constructed by build_call_array. */
12439 tree
12442 {
12443 tree tem;
12444 #ifdef ENABLE_FOLD_CHECKING
12463 #endif
12469 #ifdef ENABLE_FOLD_CHECKING
12485 #endif
12487 }
12489 /* Perform constant folding and related simplification of initializer
12490 expression EXPR. These behave identically to "fold_buildN" but ignore
12491 potential run-time traps and exceptions that fold must preserve. */
12493 #define START_FOLD_INIT \
12494 int saved_signaling_nans = flag_signaling_nans;\
12495 int saved_trapping_math = flag_trapping_math;\
12496 int saved_rounding_math = flag_rounding_math;\
12497 int saved_trapv = flag_trapv;\
12498 int saved_folding_initializer = folding_initializer;\
12499 flag_signaling_nans = 0;\
12500 flag_trapping_math = 0;\
12501 flag_rounding_math = 0;\
12502 flag_trapv = 0;\
12503 folding_initializer = 1;
12505 #define END_FOLD_INIT \
12506 flag_signaling_nans = saved_signaling_nans;\
12507 flag_trapping_math = saved_trapping_math;\
12508 flag_rounding_math = saved_rounding_math;\
12509 flag_trapv = saved_trapv;\
12510 folding_initializer = saved_folding_initializer;
12512 tree
12515 {
12516 tree result;
12517 START_FOLD_INIT;
12521 END_FOLD_INIT;
12523 }
12525 tree
12528 {
12529 tree result;
12530 START_FOLD_INIT;
12534 END_FOLD_INIT;
12536 }
12538 tree
12541 {
12542 tree result;
12543 START_FOLD_INIT;
12547 END_FOLD_INIT;
12549 }
12551 #undef START_FOLD_INIT
12552 #undef END_FOLD_INIT
12554 /* Determine if first argument is a multiple of second argument. Return 0 if
12555 it is not, or we cannot easily determined it to be.
12557 An example of the sort of thing we care about (at this point; this routine
12558 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12559 fold cases do now) is discovering that
12561 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12563 is a multiple of
12565 SAVE_EXPR (J * 8)
12567 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12569 This code also handles discovering that
12571 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12573 is a multiple of 8 so we don't have to worry about dealing with a
12574 possible remainder.
12576 Note that we *look* inside a SAVE_EXPR only to determine how it was
12577 calculated; it is not safe for fold to do much of anything else with the
12578 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12579 at run time. For example, the latter example above *cannot* be implemented
12580 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12581 evaluation time of the original SAVE_EXPR is not necessarily the same at
12582 the time the new expression is evaluated. The only optimization of this
12583 sort that would be valid is changing
12585 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12587 divided by 8 to
12589 SAVE_EXPR (I) * SAVE_EXPR (J)
12591 (where the same SAVE_EXPR (J) is used in the original and the
12592 transformed version). */
12594 int
12596 {
12607 {
12609 /* Bitwise and provides a power of two multiple. If the mask is
12610 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12618 {
12624 {
12627 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12629 {
12633 {
12636 }
12637 }
12639 }
12640 }
12645 /* It is impossible to prove if op0 - op1 is multiple of bottom
12646 precisely, so be conservative here checking if both op0 and op1
12647 are multiple of bottom. Note we check the second operand first
12648 since it's usually simpler. */
12653 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12654 as op0 - 3 if the expression has unsigned type. For example,
12655 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12665 {
12667 /* const_binop may not detect overflow correctly,
12668 so check for it explicitly here. */
12676 }
12680 /* Can't handle conversions from non-integral or wider integral type. */
12686 /* fall through */
12703 SIGNED);
12709 {
12712 /* Check for special cases to see if top is defined as multiple
12713 of bottom:
12715 top = (X & ~(bottom - 1) ; bottom is power of 2
12717 or
12719 Y = X % bottom
12720 top = X - Y. */
12739 }
12741 /* fall through */
12749 }
12750 }
12752 #define tree_expr_nonnegative_warnv_p(X, Y) \
12755 #define RECURSE(X) \
12756 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12758 /* Return true if CODE or TYPE is known to be non-negative. */
12760 static bool
12762 {
12765 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12766 have a signed:1 type (where the value is -1 and 0). */
12769 }
12771 /* Return true if (CODE OP0) is known to be non-negative. If the return
12772 value is based on the assumption that signed overflow is undefined,
12773 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12774 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12776 bool
12779 {
12784 {
12786 /* We can't return 1 if flag_wrapv is set because
12787 ABS_EXPR<INT_MIN> = INT_MIN. */
12791 {
12794 }
12802 CASE_CONVERT:
12803 {
12808 {
12812 {
12816 }
12817 }
12819 {
12825 }
12826 }
12831 }
12833 /* We don't know sign of `t', so be conservative and return false. */
12835 }
12837 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12838 value is based on the assumption that signed overflow is undefined,
12839 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12840 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12842 bool
12846 {
12851 {
12857 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12858 both unsigned and at least 2 bits shorter than the result. */
12862 {
12867 {
12871 }
12872 }
12877 {
12878 /* x * x is always non-negative for floating point x
12879 or without overflow. */
12882 {
12887 }
12888 }
12890 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12891 both unsigned and their total bits is shorter than the result. */
12895 {
12914 {
12924 }
12925 }
12952 }
12954 /* We don't know sign of `t', so be conservative and return false. */
12956 }
12958 /* Return true if T is known to be non-negative. If the return
12959 value is based on the assumption that signed overflow is undefined,
12960 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12961 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12963 bool
12965 {
12970 {
12984 /* Limit the depth of recursion to avoid quadratic behavior.
12985 This is expected to catch almost all occurrences in practice.
12986 If this code misses important cases that unbounded recursion
12987 would not, passes that need this information could be revised
12988 to provide it through dataflow propagation. */
12996 }
12997 }
12999 /* Return true if T is known to be non-negative. If the return
13000 value is based on the assumption that signed overflow is undefined,
13001 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13002 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13004 bool
13007 {
13009 {
13010 CASE_CFN_ACOS:
13011 CASE_CFN_ACOSH:
13012 CASE_CFN_CABS:
13013 CASE_CFN_COSH:
13014 CASE_CFN_ERFC:
13015 CASE_CFN_EXP:
13016 CASE_CFN_EXP10:
13017 CASE_CFN_EXP2:
13018 CASE_CFN_FABS:
13019 CASE_CFN_FDIM:
13020 CASE_CFN_HYPOT:
13021 CASE_CFN_POW10:
13022 CASE_CFN_FFS:
13023 CASE_CFN_PARITY:
13024 CASE_CFN_POPCOUNT:
13025 CASE_CFN_CLZ:
13026 CASE_CFN_CLRSB:
13029 /* Always true. */
13032 CASE_CFN_SQRT:
13033 CASE_CFN_SQRT_FN:
13034 /* sqrt(-0.0) is -0.0. */
13039 CASE_CFN_ASINH:
13040 CASE_CFN_ATAN:
13041 CASE_CFN_ATANH:
13042 CASE_CFN_CBRT:
13043 CASE_CFN_CEIL:
13044 CASE_CFN_CEIL_FN:
13045 CASE_CFN_ERF:
13046 CASE_CFN_EXPM1:
13047 CASE_CFN_FLOOR:
13048 CASE_CFN_FLOOR_FN:
13049 CASE_CFN_FMOD:
13050 CASE_CFN_FREXP:
13051 CASE_CFN_ICEIL:
13052 CASE_CFN_IFLOOR:
13053 CASE_CFN_IRINT:
13054 CASE_CFN_IROUND:
13055 CASE_CFN_LCEIL:
13056 CASE_CFN_LDEXP:
13057 CASE_CFN_LFLOOR:
13058 CASE_CFN_LLCEIL:
13059 CASE_CFN_LLFLOOR:
13060 CASE_CFN_LLRINT:
13061 CASE_CFN_LLROUND:
13062 CASE_CFN_LRINT:
13063 CASE_CFN_LROUND:
13064 CASE_CFN_MODF:
13065 CASE_CFN_NEARBYINT:
13066 CASE_CFN_NEARBYINT_FN:
13067 CASE_CFN_RINT:
13068 CASE_CFN_RINT_FN:
13069 CASE_CFN_ROUND:
13070 CASE_CFN_ROUND_FN:
13071 CASE_CFN_SCALB:
13072 CASE_CFN_SCALBLN:
13073 CASE_CFN_SCALBN:
13074 CASE_CFN_SIGNBIT:
13075 CASE_CFN_SIGNIFICAND:
13076 CASE_CFN_SINH:
13077 CASE_CFN_TANH:
13078 CASE_CFN_TRUNC:
13079 CASE_CFN_TRUNC_FN:
13080 /* True if the 1st argument is nonnegative. */
13083 CASE_CFN_FMAX:
13084 CASE_CFN_FMAX_FN:
13085 /* True if the 1st OR 2nd arguments are nonnegative. */
13088 CASE_CFN_FMIN:
13089 CASE_CFN_FMIN_FN:
13090 /* True if the 1st AND 2nd arguments are nonnegative. */
13093 CASE_CFN_COPYSIGN:
13094 CASE_CFN_COPYSIGN_FN:
13095 /* True if the 2nd argument is nonnegative. */
13098 CASE_CFN_POWI:
13099 /* True if the 1st argument is nonnegative or the second
13100 argument is an even integer. */
13106 CASE_CFN_POW:
13107 /* True if the 1st argument is nonnegative or the second
13108 argument is an even integer valued real. */
13110 {
13111 REAL_VALUE_TYPE c;
13112 HOST_WIDE_INT n;
13117 {
13118 REAL_VALUE_TYPE cint;
13122 }
13123 }
13128 }
13130 }
13132 /* Return true if T is known to be non-negative. If the return
13133 value is based on the assumption that signed overflow is undefined,
13134 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13135 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13137 static bool
13139 {
13145 {
13147 {
13151 /* If the initializer is non-void, then it's a normal expression
13152 that will be assigned to the slot. */
13156 /* Otherwise, the initializer sets the slot in some way. One common
13157 way is an assignment statement at the end of the initializer. */
13159 {
13167 else
13169 }
13175 }
13178 {
13184 arg0,
13185 arg1,
13187 }
13200 }
13201 }
13203 #undef RECURSE
13204 #undef tree_expr_nonnegative_warnv_p
13206 /* Return true if T is known to be non-negative. If the return
13207 value is based on the assumption that signed overflow is undefined,
13208 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13209 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13211 bool
13213 {
13220 {
13242 }
13245 {
13271 }
13272 }
13274 /* Return true if `t' is known to be non-negative. Handle warnings
13275 about undefined signed overflow. */
13277 bool
13279 {
13286 "determining that expression is always "
13288 WARN_STRICT_OVERFLOW_MISC);
13290 }
13293 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13294 For floating point we further ensure that T is not denormal.
13295 Similar logic is present in nonzero_address in rtlanal.h.
13297 If the return value is based on the assumption that signed overflow
13298 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13299 change *STRICT_OVERFLOW_P. */
13301 bool
13304 {
13306 {
13309 strict_overflow_p);
13312 {
13318 strict_overflow_p));
13319 }
13324 strict_overflow_p);
13328 }
13331 }
13333 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13334 For floating point we further ensure that T is not denormal.
13335 Similar logic is present in nonzero_address in rtlanal.h.
13337 If the return value is based on the assumption that signed overflow
13338 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13339 change *STRICT_OVERFLOW_P. */
13341 bool
13343 tree type,
13344 tree op0,
13346 {
13349 {
13353 {
13354 /* With the presence of negative values it is hard
13355 to say something. */
13362 /* One of operands must be positive and the other non-negative. */
13363 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13364 overflows, on a twos-complement machine the sum of two
13365 nonnegative numbers can never be zero. */
13367 strict_overflow_p)
13369 strict_overflow_p));
13370 }
13375 {
13377 strict_overflow_p)
13379 strict_overflow_p))
13380 {
13383 }
13384 }
13393 {
13396 }
13403 {
13407 /* When both operands are nonzero, then MAX must be too. */
13409 strict_overflow_p))
13412 /* MAX where operand 0 is positive is positive. */
13414 strict_overflow_p);
13415 }
13416 /* MAX where operand 1 is positive is positive. */
13421 {
13425 }
13430 strict_overflow_p)
13432 strict_overflow_p));
13436 }
13439 }
13441 /* Return true when T is an address and is known to be nonzero.
13442 For floating point we further ensure that T is not denormal.
13443 Similar logic is present in nonzero_address in rtlanal.h.
13445 If the return value is based on the assumption that signed overflow
13446 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13447 change *STRICT_OVERFLOW_P. */
13449 bool
13451 {
13454 {
13459 {
13471 /* For objects in symbol table check if we know they are non-zero.
13472 Don't do anything for variables and functions before symtab is built;
13473 it is quite possible that they will be declared weak later. */
13478 /* Constants are never weak. */
13483 }
13491 {
13495 }
13505 }
13507 }
13509 #define integer_valued_real_p(X) \
13512 #define RECURSE(X) \
13513 ((integer_valued_real_p) (X, depth + 1))
13515 /* Return true if the floating point result of (CODE OP0) has an
13516 integer value. We also allow +Inf, -Inf and NaN to be considered
13517 integer values. Return false for signaling NaN.
13519 DEPTH is the current nesting depth of the query. */
13521 bool
13523 {
13525 {
13532 CASE_CONVERT:
13533 {
13540 }
13544 }
13546 }
13548 /* Return true if the floating point result of (CODE OP0 OP1) has an
13549 integer value. We also allow +Inf, -Inf and NaN to be considered
13550 integer values. Return false for signaling NaN.
13552 DEPTH is the current nesting depth of the query. */
13554 bool
13556 {
13558 {
13568 }
13570 }
13572 /* Return true if the floating point result of calling FNDECL with arguments
13573 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13574 considered integer values. Return false for signaling NaN. If FNDECL
13575 takes fewer than 2 arguments, the remaining ARGn are null.
13577 DEPTH is the current nesting depth of the query. */
13579 bool
13581 {
13583 {
13584 CASE_CFN_CEIL:
13585 CASE_CFN_CEIL_FN:
13586 CASE_CFN_FLOOR:
13587 CASE_CFN_FLOOR_FN:
13588 CASE_CFN_NEARBYINT:
13589 CASE_CFN_NEARBYINT_FN:
13590 CASE_CFN_RINT:
13591 CASE_CFN_RINT_FN:
13592 CASE_CFN_ROUND:
13593 CASE_CFN_ROUND_FN:
13594 CASE_CFN_TRUNC:
13595 CASE_CFN_TRUNC_FN:
13598 CASE_CFN_FMIN:
13599 CASE_CFN_FMIN_FN:
13600 CASE_CFN_FMAX:
13601 CASE_CFN_FMAX_FN:
13606 }
13608 }
13610 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13611 has an integer value. We also allow +Inf, -Inf and NaN to be
13612 considered integer values. Return false for signaling NaN.
13614 DEPTH is the current nesting depth of the query. */
13616 bool
13618 {
13620 {
13628 /* Limit the depth of recursion to avoid quadratic behavior.
13629 This is expected to catch almost all occurrences in practice.
13630 If this code misses important cases that unbounded recursion
13631 would not, passes that need this information could be revised
13632 to provide it through dataflow propagation. */
13636 depth));
13640 }
13642 }
13644 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13645 has an integer value. We also allow +Inf, -Inf and NaN to be
13646 considered integer values. Return false for signaling NaN.
13648 DEPTH is the current nesting depth of the query. */
13650 static bool
13652 {
13654 {
13665 }
13667 }
13669 #undef RECURSE
13670 #undef integer_valued_real_p
13672 /* Return true if the floating point expression T has an integer value.
13673 We also allow +Inf, -Inf and NaN to be considered integer values.
13674 Return false for signaling NaN.
13676 DEPTH is the current nesting depth of the query. */
13678 bool
13680 {
13686 {
13702 }
13705 {
13711 {
13720 }
13724 }
13725 }
13727 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13728 attempt to fold the expression to a constant without modifying TYPE,
13729 OP0 or OP1.
13731 If the expression could be simplified to a constant, then return
13732 the constant. If the expression would not be simplified to a
13733 constant, then return NULL_TREE. */
13735 tree
13737 {
13740 }
13742 /* Given the components of a unary expression CODE, TYPE and OP0,
13743 attempt to fold the expression to a constant without modifying
13744 TYPE or OP0.
13746 If the expression could be simplified to a constant, then return
13747 the constant. If the expression would not be simplified to a
13748 constant, then return NULL_TREE. */
13750 tree
13752 {
13755 }
13757 /* If EXP represents referencing an element in a constant string
13758 (either via pointer arithmetic or array indexing), return the
13759 tree representing the value accessed, otherwise return NULL. */
13761 tree
13763 {
13767 {
13769 tree index;
13770 tree string;
13775 else
13776 {
13780 /* Optimize the special-case of a zero lower bound.
13782 We convert the low_bound to sizetype to avoid some problems
13783 with constant folding. (E.g. suppose the lower bound is 1,
13784 and its mode is QI. Without the conversion,l (ARRAY
13785 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13786 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13792 }
13794 scalar_int_mode char_mode;
13806 }
13808 }
13810 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13811 an integer constant, real, or fixed-point constant.
13813 TYPE is the type of the result. */
13815 static tree
13817 {
13821 {
13827 {
13828 FIXED_VALUE_TYPE f;
13833 /* Propagate overflow flags. */
13837 }
13841 {
13848 }
13851 }
13854 }
13856 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13857 an integer constant or real constant.
13859 TYPE is the type of the result. */
13861 tree
13863 {
13867 {
13869 {
13870 /* If the value is unsigned or non-negative, then the absolute value
13871 is the same as the ordinary value. */
13875 ;
13877 /* If the value is negative, then the absolute value is
13878 its negation. */
13879 else
13882 /* Force to the destination type, set TREE_OVERFLOW for signed
13883 TYPE only. */
13885 }
13891 else
13897 }
13900 }
13902 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13903 constant. TYPE is the type of the result. */
13905 static tree
13907 {
13911 }
13913 /* Given CODE, a relational operator, the target type, TYPE and two
13914 constant operands OP0 and OP1, return the result of the
13915 relational operation. If the result is not a compile time
13916 constant, then return NULL_TREE. */
13918 static tree
13920 {
13923 /* From here on, the only cases we handle are when the result is
13924 known to be a constant. */
13927 {
13931 /* Handle the cases where either operand is a NaN. */
13933 {
13935 {
13963 }
13966 }
13969 }
13972 {
13976 }
13978 /* Handle equality/inequality of complex constants. */
13980 {
13991 else
13993 }
13996 {
13998 {
13999 /* Have vector comparison with scalar boolean result. */
14007 {
14015 }
14017 }
14018 tree_vector_builder elts;
14023 {
14036 }
14039 }
14041 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14043 To compute GT, swap the arguments and do LT.
14044 To compute GE, do LT and invert the result.
14045 To compute LE, swap the arguments, do LT and invert the result.
14046 To compute NE, do EQ and invert the result.
14048 Therefore, the code below must handle only EQ and LT. */
14051 {
14054 }
14056 /* Note that it is safe to invert for real values here because we
14057 have already handled the one case that it matters. */
14061 {
14064 }
14066 /* Compute a result for LT or EQ if args permit;
14067 Otherwise return T. */
14069 {
14072 else
14074 }
14075 else
14081 }
14083 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14084 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14085 itself. */
14087 tree
14089 {
14090 /* If the expression does not have side effects then we don't have to wrap
14091 it with a cleanup point expression. */
14095 /* If the expression is a return, check to see if the expression inside the
14096 return has no side effects or the right hand side of the modify expression
14097 inside the return. If either don't have side effects set we don't need to
14098 wrap the expression in a cleanup point expression. Note we don't check the
14099 left hand side of the modify because it should always be a return decl. */
14101 {
14108 }
14111 }
14113 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14114 of an indirection through OP0, or NULL_TREE if no simplification is
14115 possible. */
14117 tree
14119 {
14121 tree subtype;
14122 poly_uint64 const_op01;
14131 {
14135 /* *&CONST_DECL -> to the value of the const decl. */
14138 /* *&p => p; make sure to handle *&"str"[cst] here. */
14140 {
14144 else
14146 }
14147 /* *(foo *)&fooarray => fooarray[0] */
14150 && (!in_gimple_form
14152 {
14162 }
14163 /* *(foo *)&complexfoo => __real__ complexfoo */
14167 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14170 {
14174 index);
14175 }
14176 }
14180 {
14186 {
14187 tree op00type;
14191 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14194 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14195 but we want to treat offsets with MSB set as negative.
14196 For the code below negative offsets are invalid and
14197 TYPE_SIZE of the element is something unsigned, so
14198 check whether op01 fits into poly_int64, which implies
14199 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14200 then just use poly_uint64 because we want to treat the
14201 value as unsigned. */
14203 {
14205 poly_uint64 max_offset
14209 {
14214 }
14215 }
14216 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14219 {
14221 const_op01))
14223 }
14224 /* ((foo *)&fooarray)[1] => fooarray[1] */
14227 {
14236 {
14241 }
14242 }
14243 }
14244 }
14246 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14249 && (!in_gimple_form
14251 {
14252 tree type_domain;
14262 NULL_TREE);
14263 }
14266 }
14268 /* Builds an expression for an indirection through T, simplifying some
14269 cases. */
14271 tree
14273 {
14281 }
14283 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14285 tree
14287 {
14292 else
14294 }
14296 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14297 whose result is ignored. The type of the returned tree need not be
14298 the same as the original expression. */
14300 tree
14302 {
14308 {
14319 else
14325 {
14341 }
14346 }
14347 }
14349 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14351 tree
14353 {
14359 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14360 have to do anything. Only do this when we are not given a const,
14361 because in that case, this check is more expensive than just
14362 doing it. */
14364 {
14369 }
14371 /* If divisor is a power of two, simplify this to bit manipulation. */
14373 {
14375 {
14389 }
14390 else
14391 {
14392 tree t;
14398 }
14399 }
14400 else
14401 {
14406 }
14409 }
14411 /* Likewise, but round down. */
14413 tree
14415 {
14422 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14423 have to do anything. Only do this when we are not given a const,
14424 because in that case, this check is more expensive than just
14425 doing it. */
14427 {
14432 }
14434 /* If divisor is a power of two, simplify this to bit manipulation. */
14436 {
14437 tree t;
14441 }
14442 else
14443 {
14448 }
14451 }
14453 /* Returns the pointer to the base of the object addressed by EXP and
14454 extracts the information about the offset of the access, storing it
14455 to PBITPOS and POFFSET. */
14457 static tree
14460 {
14461 tree core;
14462 machine_mode mode;
14464 poly_int64 bitsize;
14468 {
14473 }
14475 {
14481 {
14482 poly_offset_int tem
14488 }
14489 }
14490 else
14491 {
14495 }
14498 }
14500 /* Returns true if addresses of E1 and E2 differ by a constant, false
14501 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14503 bool
14505 {
14520 {
14530 }
14532 {
14533 /* If only one of the offsets is non-constant, the difference cannot
14534 be a constant. */
14536 }
14537 else
14542 }
14544 /* Return OFF converted to a pointer offset type suitable as offset for
14545 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14546 tree
14548 {
14550 }
14552 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14553 tree
14555 {
14558 }
14560 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14561 tree
14563 {
14566 }
14568 /* Return a char pointer for a C string if it is a string constant
14569 or sum of string constant and integer constant. We only support
14570 string constants properly terminated with '\0' character.
14571 If STRLEN is a valid pointer, length (including terminating character)
14572 of returned string is stored to the argument. */
14576 {
14577 tree offset_node;
14588 {
14591 else
14593 }
14598 /* Support only properly null-terminated strings. */
14607 }
14609 /* Given a tree T, compute which bits in T may be nonzero. */
14611 wide_int
14613 {
14615 {
14633 CASE_CONVERT:
14639 {
14644 }
14648 {
14656 }
14660 {
14668 }
14672 }
14675 }
14677 #if CHECKING_P
14681 /* Helper functions for writing tests of folding trees. */
14683 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14685 static void
14687 tree constant)
14688 {
14690 }
14692 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14693 wrapping WRAPPED_EXPR. */
14695 static void
14697 tree wrapped_expr)
14698 {
14703 }
14705 /* Verify that various arithmetic binary operations are folded
14706 correctly. */
14708 static void
14710 {
14716 /* Addition. */
14717 /* 1 <-- (0 + 1) */
14719 one);
14721 one);
14723 /* (nonlvalue)x <-- (x + 0) */
14725 x);
14727 /* Subtraction. */
14728 /* 0 <-- (x - x) */
14730 zero);
14732 x);
14734 /* Multiplication. */
14735 /* 0 <-- (x * 0) */
14737 zero);
14739 /* (nonlvalue)x <-- (x * 1) */
14741 x);
14742 }
14744 /* Verify that various binary operations on vectors are folded
14745 correctly. */
14747 static void
14749 {
14755 /* Verify equality tests that return a scalar boolean result. */
14761 }
14763 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14765 static void
14767 {
14770 /* This will be 1 if VEC_MODE isn't a vector mode. */
14777 }
14779 /* Run all of the selftests within this file. */
14781 void
14783 {
14787 }