| blob | 1e8d79e40221ae93cc06b5896dc9312926917acf |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
414 /* Steps don't prevent negation. */
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a (negative) power of two. */
464 /* Fall through. */
477 /* In general we can't negate A in A / B, because if A is INT_MIN and
478 B is not 1 we change the sign of the result. */
482 /* In general we can't negate B in A / B, because if A is INT_MIN and
483 B is 1, we may turn this into INT_MIN / -1 which is undefined
484 and actually traps on some architectures. */
493 /* Negate -((double)float) as (double)(-float). */
495 {
499 }
503 /* Negate -f(x) as f(-x). */
509 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
511 {
515 }
520 }
522 }
524 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
525 simplification is possible.
526 If negate_expr_p would return true for T, NULL_TREE will never be
527 returned. */
529 static tree
531 {
533 tree tem;
536 {
537 /* Convert - (~A) to A + 1. */
561 {
566 }
570 {
571 tree_vector_builder elts;
575 {
580 }
583 }
606 {
607 /* -(A + B) -> (-B) - A. */
609 {
613 }
615 /* -(A + B) -> (-A) - B. */
617 {
621 }
622 }
626 /* - (A - B) -> B - A */
637 /* Fall through. */
641 {
650 }
658 /* In general we can't negate A in A / B, because if A is INT_MIN and
659 B is not 1 we change the sign of the result. */
665 /* In general we can't negate B in A / B, because if A is INT_MIN and
666 B is 1, we may turn this into INT_MIN / -1 which is undefined
667 and actually traps on some architectures. */
679 /* Convert -((double)float) into (double)(-float). */
681 {
685 }
689 /* Negate -f(x) as f(-x). */
692 {
698 }
702 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
704 {
707 {
714 }
715 }
720 }
723 }
725 /* A wrapper for fold_negate_expr_1. */
727 static tree
729 {
736 }
738 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
739 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
740 return NULL_TREE. */
742 static tree
744 {
746 location_t loc;
759 }
760 \f
761 /* Split a tree IN into a constant, literal and variable parts that could be
762 combined with CODE to make IN. "constant" means an expression with
763 TREE_CONSTANT but that isn't an actual constant. CODE must be a
764 commutative arithmetic operation. Store the constant part into *CONP,
765 the literal in *LITP and return the variable part. If a part isn't
766 present, set it to null. If the tree does not decompose in this way,
767 return the entire tree as the variable part and the other parts as null.
769 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
770 case, we negate an operand that was subtracted. Except if it is a
771 literal for which we use *MINUS_LITP instead.
773 If NEGATE_P is true, we are negating all of IN, again except a literal
774 for which we use *MINUS_LITP instead. If a variable part is of pointer
775 type, it is negated after converting to TYPE. This prevents us from
776 generating illegal MINUS pointer expression. LOC is the location of
777 the converted variable part.
779 If IN is itself a literal or constant, return it as appropriate.
781 Note that we do not guarantee that any of the three values will be the
782 same type as IN, but they will have the same signedness and mode. */
784 static tree
788 {
796 /* Strip any conversions that don't change the machine mode or signedness. */
805 /* We can associate addition and subtraction together (even
806 though the C standard doesn't say so) for integers because
807 the value is not affected. For reals, the value might be
808 affected, so we can't. */
814 {
820 /* First see if either of the operands is a literal, then a constant. */
833 /* If we haven't dealt with either operand, this is not a case we can
834 decompose. Otherwise, VAR is either of the ones remaining, if any. */
839 else
842 /* Now do any needed negations. */
849 }
854 {
855 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
856 when IN is constant. */
859 }
860 else
864 {
877 }
887 }
889 /* Re-associate trees split by the above function. T1 and T2 are
890 either expressions to associate or null. Return the new
891 expression, if any. LOC is the location of the new expression. If
892 we build an operation, do it in TYPE and with CODE. */
894 static tree
896 {
898 {
901 }
905 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
906 try to fold this since we will have infinite recursion. But do
907 deal with any NEGATE_EXPRs. */
911 {
913 {
926 }
928 {
931 }
935 }
939 }
940 \f
941 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
942 for use in int_const_binop, size_binop and size_diffop. */
944 static bool
946 {
953 {
962 }
967 }
969 /* Subroutine of int_const_binop_1 that handles two INTEGER_CSTs. */
971 static tree
974 {
975 wide_int res;
976 tree t;
985 {
1001 {
1005 else
1007 }
1010 /* It's unclear from the C standard whether shifts can overflow.
1011 The following code ignores overflow; perhaps a C standard
1012 interpretation ruling is needed. */
1014 else
1021 {
1025 else
1027 }
1031 else
1110 }
1118 }
1120 /* Combine two integer constants PARG1 and PARG2 under operation CODE
1121 to produce a new constant. Return NULL_TREE if we don't know how
1122 to evaluate CODE at compile-time. */
1124 static tree
1127 {
1134 {
1135 poly_wide_int res;
1140 {
1158 else
1165 else
1178 }
1183 }
1186 }
1188 tree
1190 {
1192 }
1194 /* Return true if binary operation OP distributes over addition in operand
1195 OPNO, with the other operand being held constant. OPNO counts from 1. */
1197 static bool
1199 {
1201 {
1212 }
1213 }
1215 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1216 constant. We assume ARG1 and ARG2 have the same data type, or at least
1217 are the same kind of constant and the same machine mode. Return zero if
1218 combining the constants is not allowed in the current operating mode. */
1220 static tree
1222 {
1223 /* Sanity check for the recursive cases. */
1231 {
1237 }
1240 {
1241 machine_mode mode;
1242 REAL_VALUE_TYPE d1;
1243 REAL_VALUE_TYPE d2;
1244 REAL_VALUE_TYPE value;
1245 REAL_VALUE_TYPE result;
1249 /* The following codes are handled by real_arithmetic. */
1251 {
1262 }
1270 /* Don't perform operation if we honor signaling NaNs and
1271 either operand is a signaling NaN. */
1277 /* Don't perform operation if it would raise a division
1278 by zero exception. */
1284 /* If either operand is a NaN, just return it. Otherwise, set up
1285 for floating-point trap; we return an overflow. */
1287 {
1288 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1289 is off. */
1293 }
1295 {
1296 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1297 is off. */
1301 }
1306 /* Don't constant fold this floating point operation if
1307 the result has overflowed and flag_trapping_math. */
1315 /* Don't constant fold this floating point operation if the
1316 result may dependent upon the run-time rounding mode and
1317 flag_rounding_math is set, or if GCC's software emulation
1318 is unable to accurately represent the result. */
1328 }
1331 {
1332 FIXED_VALUE_TYPE f1;
1333 FIXED_VALUE_TYPE f2;
1334 FIXED_VALUE_TYPE result;
1339 /* The following codes are handled by fixed_arithmetic. */
1341 {
1353 {
1360 }
1365 }
1372 /* Propagate overflow flags. */
1376 }
1379 {
1388 {
1399 mpc_mul);
1413 mpc_div);
1414 /* Fallthru. */
1420 {
1421 /* Keep this algorithm in sync with
1422 tree-complex.c:expand_complex_div_straight().
1424 Expand complex division to scalars, straightforward algorithm.
1425 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1426 t = br*br + bi*bi
1427 */
1428 tree magsquared
1432 tree t1
1436 tree t2
1443 }
1444 else
1445 {
1446 /* Keep this algorithm in sync with
1447 tree-complex.c:expand_complex_div_wide().
1449 Expand complex division to scalars, modified algorithm to minimize
1450 overflow with wide input ranges. */
1456 {
1457 /* In the TRUE branch, we compute
1458 ratio = br/bi;
1459 div = (br * ratio) + bi;
1460 tr = (ar * ratio) + ai;
1461 ti = (ai * ratio) - ar;
1462 tr = tr / div;
1463 ti = ti / div; */
1474 }
1475 else
1476 {
1477 /* In the FALSE branch, we compute
1478 ratio = d/c;
1479 divisor = (d * ratio) + c;
1480 tr = (b * ratio) + a;
1481 ti = b - (a * ratio);
1482 tr = tr / div;
1483 ti = ti / div; */
1495 }
1496 }
1501 }
1505 }
1511 {
1516 /* We can operate directly on the encoding if:
1518 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1519 implies
1520 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1522 Addition and subtraction are the supported operators
1523 for which this is true. */
1526 /* We can operate directly on stepped encodings if:
1528 a3 - a2 == a2 - a1
1529 implies:
1530 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1532 which is true if (x -> x op c) distributes over addition. */
1534 else
1535 /* Similarly in reverse. */
1537 tree_vector_builder elts;
1542 {
1548 /* It is possible that const_binop cannot handle the given
1549 code and return NULL_TREE */
1553 }
1556 }
1558 /* Shifts allow a scalar offset for a vector. */
1561 {
1564 tree_vector_builder elts;
1569 {
1574 /* It is possible that const_binop cannot handle the given
1575 code and return NULL_TREE. */
1579 }
1582 }
1584 }
1586 /* Overload that adds a TYPE parameter to be able to dispatch
1587 to fold_relational_const. */
1589 tree
1591 {
1595 /* ??? Until we make the const_binop worker take the type of the
1596 result as argument put those cases that need it here. */
1598 {
1615 {
1620 }
1626 {
1642 {
1647 ? NOP_EXPR
1654 }
1657 }
1663 {
1686 {
1699 }
1702 }
1705 }
1710 /* Make sure type and arg0 have the same saturating flag. */
1715 }
1717 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1718 Return zero if computing the constants is not possible. */
1720 tree
1722 {
1723 /* Don't perform the operation, other than NEGATE and ABS, if
1724 flag_signaling_nans is on and the operand is a signaling NaN. */
1733 {
1734 CASE_CONVERT:
1741 /* If the source address is 0, and the source address space
1742 cannot have a valid object at 0, fold to dest type null. */
1753 {
1754 /* Can't call fold_negate_const directly here as that doesn't
1755 handle all cases and we might not be able to negate some
1756 constants. */
1761 }
1770 {
1774 }
1782 /* Perform BIT_NOT_EXPR on each element individually. */
1784 {
1785 tree elem;
1787 /* This can cope with stepped encodings because ~x == -1 - x. */
1788 tree_vector_builder elements;
1792 {
1798 }
1801 }
1825 {
1848 else
1853 {
1859 }
1862 }
1871 }
1874 }
1876 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1877 indicates which particular sizetype to create. */
1879 tree
1881 {
1883 }
1884 \f
1885 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1886 is a tree code. The type of the result is taken from the operands.
1887 Both must be equivalent integer types, ala int_binop_types_match_p.
1888 If the operands are constant, so is the result. */
1890 tree
1892 {
1901 /* Handle the special case of two poly_int constants faster. */
1903 {
1904 /* And some specific cases even faster than that. */
1906 {
1911 }
1913 {
1916 }
1918 {
1921 }
1923 /* Handle general case of two integer constants. For sizetype
1924 constant calculations we always want to know about overflow,
1925 even in the unsigned case. */
1929 }
1932 }
1934 /* Given two values, either both of sizetype or both of bitsizetype,
1935 compute the difference between the two values. Return the value
1936 in signed type corresponding to the type of the operands. */
1938 tree
1940 {
1942 tree ctype;
1947 /* If the type is already signed, just do the simple thing. */
1955 else
1958 /* If either operand is not a constant, do the conversions to the signed
1959 type and subtract. The hardware will do the right thing with any
1960 overflow in the subtraction. */
1966 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1967 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1968 overflow) and negate (which can't either). Special-case a result
1969 of zero while we're here. */
1975 else
1979 MINUS_EXPR,
1981 }
1982 \f
1983 /* A subroutine of fold_convert_const handling conversions of an
1984 INTEGER_CST to another integer type. */
1986 static tree
1988 {
1989 /* Given an integer constant, make new constant with new type,
1990 appropriately sign-extended or truncated. Use widest_int
1991 so that any extension is done according ARG1's type. */
1995 }
1997 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1998 to an integer type. */
2000 static tree
2002 {
2004 tree t;
2006 /* The following code implements the floating point to integer
2007 conversion rules required by the Java Language Specification,
2008 that IEEE NaNs are mapped to zero and values that overflow
2009 the target precision saturate, i.e. values greater than
2010 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2011 are mapped to INT_MIN. These semantics are allowed by the
2012 C and C++ standards that simply state that the behavior of
2013 FP-to-integer conversion is unspecified upon overflow. */
2015 wide_int val;
2016 REAL_VALUE_TYPE r;
2020 {
2027 }
2029 /* If R is NaN, return zero and show we have an overflow. */
2031 {
2034 }
2036 /* See if R is less than the lower bound or greater than the
2037 upper bound. */
2040 {
2044 {
2047 }
2048 }
2051 {
2054 {
2057 {
2060 }
2061 }
2062 }
2069 }
2071 /* A subroutine of fold_convert_const handling conversions of a
2072 FIXED_CST to an integer type. */
2074 static tree
2076 {
2077 tree t;
2079 scalar_mode mode;
2081 /* Right shift FIXED_CST to temp by fbit. */
2085 {
2087 HOST_BITS_PER_DOUBLE_INT,
2090 /* Left shift temp to temp_trunc by fbit. */
2092 HOST_BITS_PER_DOUBLE_INT,
2094 }
2095 else
2096 {
2099 }
2101 /* If FIXED_CST is negative, we need to round the value toward 0.
2102 By checking if the fractional bits are not zero to add 1 to temp. */
2108 /* Given a fixed-point constant, make new constant with new type,
2109 appropriately sign-extended or truncated. */
2117 }
2119 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2120 to another floating point type. */
2122 static tree
2124 {
2125 REAL_VALUE_TYPE value;
2126 tree t;
2128 /* Don't perform the operation if flag_signaling_nans is on
2129 and the operand is a signaling NaN. */
2137 /* If converting an infinity or NAN to a representation that doesn't
2138 have one, set the overflow bit so that we can produce some kind of
2139 error message at the appropriate point if necessary. It's not the
2140 most user-friendly message, but it's better than nothing. */
2147 /* Regular overflow, conversion produced an infinity in a mode that
2148 can't represent them. */
2153 else
2156 }
2158 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2159 to a floating point type. */
2161 static tree
2163 {
2164 REAL_VALUE_TYPE value;
2165 tree t;
2173 }
2175 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2176 to another fixed-point type. */
2178 static tree
2180 {
2181 FIXED_VALUE_TYPE value;
2182 tree t;
2189 /* Propagate overflow flags. */
2193 }
2195 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2196 to a fixed-point type. */
2198 static tree
2200 {
2201 FIXED_VALUE_TYPE value;
2202 tree t;
2204 double_int di;
2211 else
2219 /* Propagate overflow flags. */
2223 }
2225 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2226 to a fixed-point type. */
2228 static tree
2230 {
2231 FIXED_VALUE_TYPE value;
2232 tree t;
2240 /* Propagate overflow flags. */
2244 }
2246 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2247 type TYPE. If no simplification can be done return NULL_TREE. */
2249 static tree
2251 {
2256 /* We can't widen types, since the runtime value could overflow the
2257 original type before being extended to the new type. */
2268 {
2275 }
2277 {
2284 }
2286 {
2293 }
2295 {
2298 {
2301 /* We can't handle steps directly when extending, since the
2302 values need to wrap at the original precision first. */
2303 bool step_ok_p
2307 tree_vector_builder v;
2312 {
2318 }
2320 }
2321 }
2323 }
2325 /* Construct a vector of zero elements of vector type TYPE. */
2327 static tree
2329 {
2330 tree t;
2334 }
2336 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2338 bool
2340 {
2355 {
2370 }
2371 }
2373 /* Convert expression ARG to type TYPE. Used by the middle-end for
2374 simple conversions in preference to calling the front-end's convert. */
2376 tree
2378 {
2380 tree tem;
2391 {
2394 /* Handle conversions between pointers to different address spaces. */
2399 /* fall through */
2404 {
2408 }
2422 {
2426 }
2428 {
2432 }
2434 {
2438 }
2441 {
2459 }
2464 {
2468 }
2471 {
2485 }
2489 {
2498 integer_zero_node));
2500 {
2504 {
2510 }
2518 }
2522 }
2540 }
2541 fold_convert_exit:
2544 }
2545 \f
2546 /* Return false if expr can be assumed not to be an lvalue, true
2547 otherwise. */
2549 static bool
2551 {
2552 /* We only need to wrap lvalue tree codes. */
2554 {
2585 /* Assume the worst for front-end tree codes. */
2589 }
2592 }
2594 /* Return an expr equal to X but certainly not valid as an lvalue. */
2596 tree
2598 {
2599 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2600 us. */
2607 }
2609 /* When pedantic, return an expr equal to X but certainly not valid as a
2610 pedantic lvalue. Otherwise, return X. */
2612 static tree
2614 {
2616 }
2617 \f
2618 /* Given a tree comparison code, return the code that is the logical inverse.
2619 It is generally not safe to do this for floating-point comparisons, except
2620 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2621 ERROR_MARK in this case. */
2623 enum tree_code
2625 {
2631 {
2662 }
2663 }
2665 /* Similar, but return the comparison that results if the operands are
2666 swapped. This is safe for floating-point. */
2668 enum tree_code
2670 {
2672 {
2698 }
2699 }
2702 /* Convert a comparison tree code from an enum tree_code representation
2703 into a compcode bit-based encoding. This function is the inverse of
2704 compcode_to_comparison. */
2706 static enum comparison_code
2708 {
2710 {
2741 }
2742 }
2744 /* Convert a compcode bit-based encoding of a comparison operator back
2745 to GCC's enum tree_code representation. This function is the
2746 inverse of comparison_to_compcode. */
2748 static enum tree_code
2750 {
2752 {
2783 }
2784 }
2786 /* Return a tree for the comparison which is the combination of
2787 doing the AND or OR (depending on CODE) of the two operations LCODE
2788 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2789 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2790 if this makes the transformation invalid. */
2792 tree
2797 {
2804 {
2815 }
2818 {
2819 /* Eliminate unordered comparisons, as well as LTGT and ORD
2820 which are not used unless the mode has NaNs. */
2826 }
2828 {
2829 /* Check that the original operation and the optimized ones will trap
2830 under the same condition. */
2841 /* In a short-circuited boolean expression the LHS might be
2842 such that the RHS, if evaluated, will never trap. For
2843 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2844 if neither x nor y is NaN. (This is a mixed blessing: for
2845 example, the expression above will never trap, hence
2846 optimizing it to x < y would be invalid). */
2851 /* If the comparison was short-circuited, and only the RHS
2852 trapped, we may now generate a spurious trap. */
2857 /* If we changed the conditions that cause a trap, we lose. */
2860 }
2866 else
2867 {
2872 }
2873 }
2874 \f
2875 /* Return nonzero if two operands (typically of the same tree node)
2876 are necessarily equal. FLAGS modifies behavior as follows:
2878 If OEP_ONLY_CONST is set, only return nonzero for constants.
2879 This function tests whether the operands are indistinguishable;
2880 it does not test whether they are equal using C's == operation.
2881 The distinction is important for IEEE floating point, because
2882 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2883 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2885 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2886 even though it may hold multiple values during a function.
2887 This is because a GCC tree node guarantees that nothing else is
2888 executed between the evaluation of its "operands" (which may often
2889 be evaluated in arbitrary order). Hence if the operands themselves
2890 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2891 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2892 unset means assuming isochronic (or instantaneous) tree equivalence.
2893 Unless comparing arbitrary expression trees, such as from different
2894 statements, this flag can usually be left unset.
2896 If OEP_PURE_SAME is set, then pure functions with identical arguments
2897 are considered the same. It is used when the caller has other ways
2898 to ensure that global memory is unchanged in between.
2900 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2901 not values of expressions.
2903 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2904 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2906 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2907 any operand with side effect. This is unnecesarily conservative in the
2908 case we know that arg0 and arg1 are in disjoint code paths (such as in
2909 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2910 addresses with TREE_CONSTANT flag set so we know that &var == &var
2911 even if var is volatile. */
2913 int
2915 {
2916 /* When checking, verify at the outermost operand_equal_p call that
2917 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2918 hash value. */
2920 {
2922 {
2924 {
2931 }
2933 }
2934 else
2936 }
2938 /* If either is ERROR_MARK, they aren't equal. */
2944 /* Similar, if either does not have a type (like a released SSA name),
2945 they aren't equal. */
2949 /* We cannot consider pointers to different address space equal. */
2956 /* Check equality of integer constants before bailing out due to
2957 precision differences. */
2959 {
2960 /* Address of INTEGER_CST is not defined; check that we did not forget
2961 to drop the OEP_ADDRESS_OF flags. */
2964 }
2967 {
2968 /* If both types don't have the same signedness, then we can't consider
2969 them equal. We must check this before the STRIP_NOPS calls
2970 because they may change the signedness of the arguments. As pointers
2971 strictly don't have a signedness, require either two pointers or
2972 two non-pointers as well. */
2978 /* If both types don't have the same precision, then it is not safe
2979 to strip NOPs. */
2986 }
2987 #if 0
2988 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2989 sanity check once the issue is solved. */
2990 else
2991 /* Addresses of conversions and SSA_NAMEs (and many other things)
2992 are not defined. Check that we did not forget to drop the
2993 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2996 #endif
2998 /* In case both args are comparisons but with different comparison
2999 code, try to swap the comparison operands of one arg to produce
3000 a match and compare that variant. */
3004 {
3012 }
3015 {
3016 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3018 ;
3020 {
3021 /* If we are interested in comparing addresses ignore
3022 MEM_REF wrappings of the base that can appear just for
3023 TBAA reasons. */
3037 }
3038 else
3040 }
3042 /* When not checking adddresses, this is needed for conversions and for
3043 COMPONENT_REF. Might as well play it safe and always test this. */
3050 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3051 We don't care about side effects in that case because the SAVE_EXPR
3052 takes care of that for us. In all other cases, two expressions are
3053 equal if they have no side effects. If we have two identical
3054 expressions with side effects that should be treated the same due
3055 to the only side effects being identical SAVE_EXPR's, that will
3056 be detected in the recursive calls below.
3057 If we are taking an invariant address of two identical objects
3058 they are necessarily equal as well. */
3065 /* Next handle constant cases, those for which we can return 1 even
3066 if ONLY_CONST is set. */
3069 {
3083 {
3084 /* If we do not distinguish between signed and unsigned zero,
3085 consider them equal. */
3088 }
3092 {
3107 }
3111 flags)
3113 flags));
3124 flags | OEP_ADDRESS_OF
3127 /* In GIMPLE empty constructors are allowed in initializers of
3128 aggregates. */
3132 }
3137 /* Define macros to test an operand from arg0 and arg1 for equality and a
3138 variant that allows null and views null as being different from any
3139 non-null value. In the latter case, if either is null, the both
3140 must be; otherwise, do the normal comparison. */
3141 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3142 TREE_OPERAND (arg1, N), flags)
3144 #define OP_SAME_WITH_NULL(N) \
3145 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3146 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3149 {
3151 /* Two conversions are equal only if signedness and modes match. */
3153 {
3154 CASE_CONVERT:
3162 }
3172 /* For commutative ops, allow the other order. */
3180 /* If either of the pointer (or reference) expressions we are
3181 dereferencing contain a side effect, these cannot be equal,
3182 but their addresses can be. */
3189 {
3199 /* Require the same offset. */
3205 /* Fallthru. */
3213 {
3214 /* Require equal access sizes */
3220 flags)))
3222 /* Verify that access happens in similar types. */
3225 /* Verify that accesses are TBAA compatible. */
3234 /* Verify that alignment is compatible. */
3238 }
3241 /* TARGET_MEM_REF require equal extra operands. */
3252 /* Compare the array index by value if it is constant first as we
3253 may have different types but same value here. */
3259 /* Compare low bound and element size as with OEP_ADDRESS_OF
3260 we have to account for the offset of the ref. */
3265 array_ref_low_bound
3269 array_ref_element_size
3271 flags))));
3274 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3275 may be NULL when we're called to compare MEM_EXPRs. */
3290 }
3294 {
3296 /* Be sure we pass right ADDRESS_OF flag. */
3313 /* The multiplcation operands are commutative. */
3314 /* FALLTHRU */
3322 /* Otherwise take into account this is a commutative operation. */
3335 /* BIT_INSERT_EXPR has an implict operand as the type precision
3336 of op1. Need to check to make sure they are the same. */
3342 /* FALLTHRU */
3367 }
3371 {
3375 /* If not both CALL_EXPRs are either internal or normal function
3376 functions, then they are not equal. */
3379 {
3380 /* If the CALL_EXPRs call different internal functions, then they
3381 are not equal. */
3384 }
3385 else
3386 {
3387 /* If the CALL_EXPRs call different functions, then they are not
3388 equal. */
3390 flags))
3392 }
3394 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3395 {
3399 else
3403 }
3405 /* Now see if all the arguments are the same. */
3406 {
3417 /* If we get here and both argument lists are exhausted
3418 then the CALL_EXPRs are equal. */
3420 }
3423 }
3426 /* Consider __builtin_sqrt equal to sqrt. */
3434 {
3435 /* In GIMPLE constructors are used only to build vectors from
3436 elements. Individual elements in the constructor must be
3437 indexed in increasing order and form an initial sequence.
3439 We make no effort to compare constructors in generic.
3440 (see sem_variable::equals in ipa-icf which can do so for
3441 constants). */
3446 /* Be sure that vectors constructed have the same representation.
3447 We only tested element precision and modes to match.
3448 Vectors may be BLKmode and thus also check that the number of
3449 parts match. */
3462 {
3467 /* In GIMPLE the indexes can be either NULL or matching i.
3468 Double check this so we won't get false
3469 positives for GENERIC. */
3477 }
3479 }
3482 {
3483 /* Compare the STATEMENT_LISTs. */
3489 {
3490 /* The lists don't have the same number of statements. */
3496 flags & (OEP_LEXICOGRAPHIC
3499 }
3500 }
3505 {
3516 }
3520 }
3522 #undef OP_SAME
3523 #undef OP_SAME_WITH_NULL
3524 }
3525 \f
3526 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3527 with a different signedness or a narrower precision. */
3529 static bool
3531 {
3539 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3540 and see if the inner values are the same. This removes any
3541 signedness comparison, which doesn't matter here. */
3549 /* Discard a single widening conversion from ARG1 and see if the inner
3550 value is the same as ARG0. */
3559 }
3560 \f
3561 /* See if ARG is an expression that is either a comparison or is performing
3562 arithmetic on comparisons. The comparisons must only be comparing
3563 two different values, which will be stored in *CVAL1 and *CVAL2; if
3564 they are nonzero it means that some operands have already been found.
3565 No variables may be used anywhere else in the expression except in the
3566 comparisons.
3568 If this is true, return 1. Otherwise, return zero. */
3570 static int
3572 {
3576 /* We can handle some of the tcc_expression cases here. */
3585 {
3604 /* First see if we can handle the first operand, then the second. For
3605 the second operand, we know *CVAL1 can't be zero. It must be that
3606 one side of the comparison is each of the values; test for the
3607 case where this isn't true by failing if the two operands
3608 are the same. */
3617 ;
3621 ;
3622 else
3626 ;
3630 ;
3631 else
3638 }
3639 }
3640 \f
3641 /* ARG is a tree that is known to contain just arithmetic operations and
3642 comparisons. Evaluate the operations in the tree substituting NEW0 for
3643 any occurrence of OLD0 as an operand of a comparison and likewise for
3644 NEW1 and OLD1. */
3646 static tree
3649 {
3654 /* We can handle some of the tcc_expression cases here. */
3662 {
3677 {
3696 }
3697 /* Fall through - ??? */
3700 {
3704 /* We need to check both for exact equality and tree equality. The
3705 former will be true if the operand has a side-effect. In that
3706 case, we know the operand occurred exactly once. */
3719 }
3723 }
3724 }
3725 \f
3726 /* Return a tree for the case when the result of an expression is RESULT
3727 converted to TYPE and OMITTED was previously an operand of the expression
3728 but is now not needed (e.g., we folded OMITTED * 0).
3730 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3731 the conversion of RESULT to TYPE. */
3733 tree
3735 {
3738 /* If the resulting operand is an empty statement, just return the omitted
3739 statement casted to void. */
3749 }
3751 /* Return a tree for the case when the result of an expression is RESULT
3752 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3753 of the expression but are now not needed.
3755 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3756 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3757 evaluated before OMITTED2. Otherwise, if neither has side effects,
3758 just do the conversion of RESULT to TYPE. */
3760 tree
3763 {
3772 }
3774 \f
3775 /* Return a simplified tree node for the truth-negation of ARG. This
3776 never alters ARG itself. We assume that ARG is an operation that
3777 returns a truth value (0 or 1).
3779 FIXME: one would think we would fold the result, but it causes
3780 problems with the dominator optimizer. */
3782 static tree
3784 {
3789 /* If this is a comparison, we can simply invert it, except for
3790 floating-point non-equality comparisons, in which case we just
3791 enclose a TRUTH_NOT_EXPR around what we have. */
3794 {
3797 && flag_trapping_math
3811 }
3814 {
3833 /* Here we can invert either operand. We invert the first operand
3834 unless the second operand is a TRUTH_NOT_EXPR in which case our
3835 result is the XOR of the first operand with the inside of the
3836 negation of the second operand. */
3841 else
3864 {
3871 /* A COND_EXPR may have a throw as one operand, which
3872 then has void type. Just leave void operands
3873 as they are. */
3879 }
3891 CASE_CONVERT:
3895 /* fall through */
3917 }
3918 }
3920 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3921 assume that ARG is an operation that returns a truth value (0 or 1
3922 for scalars, 0 or -1 for vectors). Return the folded expression if
3923 folding is successful. Otherwise, return NULL_TREE. */
3925 static tree
3927 {
3930 ? BIT_NOT_EXPR
3933 }
3935 /* Return a simplified tree node for the truth-negation of ARG. This
3936 never alters ARG itself. We assume that ARG is an operation that
3937 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3939 tree
3941 {
3947 ? BIT_NOT_EXPR
3950 }
3951 \f
3952 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3953 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3954 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3955 is the original memory reference used to preserve the alias set of
3956 the access. */
3958 static tree
3962 {
3965 /* Attempt not to lose the access path if possible. */
3967 {
3969 machine_mode nmode;
3971 tree noffset;
3979 && !reversep
3980 && !nreversep
3982 {
3985 }
3986 }
3995 {
4002 }
4017 }
4019 /* Optimize a bit-field compare.
4021 There are two cases: First is a compare against a constant and the
4022 second is a comparison of two items where the fields are at the same
4023 bit position relative to the start of a chunk (byte, halfword, word)
4024 large enough to contain it. In these cases we can avoid the shift
4025 implicit in bitfield extractions.
4027 For constants, we emit a compare of the shifted constant with the
4028 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4029 compared. For two fields at the same position, we do the ANDs with the
4030 similar mask and compare the result of the ANDs.
4032 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4033 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4034 are the left and right operands of the comparison, respectively.
4036 If the optimization described above can be done, we return the resulting
4037 tree. Otherwise we return zero. */
4039 static tree
4042 {
4046 tree unsigned_type;
4049 scalar_int_mode nmode;
4054 tree mask;
4055 tree offset;
4057 /* Get all the information about the extractions being done. If the bit size
4058 is the same as the size of the underlying object, we aren't doing an
4059 extraction at all and so can do nothing. We also don't want to
4060 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4061 then will no longer be able to replace it. */
4076 else
4077 {
4078 /* If this is not a constant, we can only do something if bit positions,
4079 sizes, signedness and storage order are the same. */
4080 rinner
4093 }
4095 /* Honor the C++ memory model and mimic what RTL expansion does. */
4099 {
4103 }
4105 /* See if we can find a mode to refer to this field. We should be able to,
4106 but fail if we can't. */
4114 /* Set signed and unsigned types of the precision of this mode for the
4115 shifts below. */
4118 /* Compute the bit position and size for the new reference and our offset
4119 within it. If the new reference is the same size as the original, we
4120 won't optimize anything, so return zero. */
4130 /* Make the mask to be used against the extracted field. */
4137 {
4141 /* If not comparing with constant, just rework the comparison
4142 and return. */
4150 }
4152 /* Otherwise, we are handling the constant case. See if the constant is too
4153 big for the field. Warn and return a tree for 0 (false) if so. We do
4154 this not only for its own sake, but to avoid having to test for this
4155 error case below. If we didn't, we might generate wrong code.
4157 For unsigned fields, the constant shifted right by the field length should
4158 be all zero. For signed fields, the high-order bits should agree with
4159 the sign bit. */
4162 {
4164 {
4168 }
4169 }
4170 else
4171 {
4174 {
4178 }
4179 }
4184 /* Single-bit compares should always be against zero. */
4186 {
4189 }
4191 /* Make a new bitfield reference, shift the constant over the
4192 appropriate number of bits and mask it with the computed mask
4193 (in case this was a signed field). If we changed it, make a new one. */
4201 mask);
4206 }
4207 \f
4208 /* Subroutine for fold_truth_andor_1: decode a field reference.
4210 If EXP is a comparison reference, we return the innermost reference.
4212 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4213 set to the starting bit number.
4215 If the innermost field can be completely contained in a mode-sized
4216 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4218 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4219 otherwise it is not changed.
4221 *PUNSIGNEDP is set to the signedness of the field.
4223 *PREVERSEP is set to the storage order of the field.
4225 *PMASK is set to the mask used. This is either contained in a
4226 BIT_AND_EXPR or derived from the width of the field.
4228 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4230 Return 0 if this is not a component reference or is one that we can't
4231 do anything with. */
4233 static tree
4238 {
4243 tree unsigned_type;
4246 /* All the optimizations using this function assume integer fields.
4247 There are problems with FP fields since the type_for_size call
4248 below can fail for, e.g., XFmode. */
4252 /* We are interested in the bare arrangement of bits, so strip everything
4253 that doesn't affect the machine mode. However, record the type of the
4254 outermost expression if it may matter below. */
4261 {
4267 }
4278 /* Reject out-of-bound accesses (PR79731). */
4286 /* If the number of bits in the reference is the same as the bitsize of
4287 the outer type, then the outer type gives the signedness. Otherwise
4288 (in case of a small bitfield) the signedness is unchanged. */
4292 /* Compute the mask to access the bitfield. */
4301 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4309 }
4311 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4312 bit positions and MASK is SIGNED. */
4314 static int
4316 {
4320 /* If this function returns true when the type of the mask is
4321 UNSIGNED, then there will be errors. In particular see
4322 gcc.c-torture/execute/990326-1.c. There does not appear to be
4323 any documentation paper trail as to why this is so. But the pre
4324 wide-int worked with that restriction and it has been preserved
4325 here. */
4330 }
4332 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4333 represents the sign bit of EXP's type. If EXP represents a sign
4334 or zero extension, also test VAL against the unextended type.
4335 The return value is the (sub)expression whose sign bit is VAL,
4336 or NULL_TREE otherwise. */
4338 tree
4340 {
4342 tree t;
4344 /* Tree EXP must have an integral type. */
4349 /* Tree VAL must be an integer constant. */
4358 /* Handle extension from a narrower type. */
4364 }
4366 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4367 to be evaluated unconditionally. */
4369 static int
4371 {
4372 /* Strip any conversions that don't change the machine mode. */
4381 /* Don't regard global variables as simple. They may be
4382 allocated in ways unknown to the compiler (shared memory,
4383 #pragma weak, etc). */
4386 /* Weakrefs are not safe to be read, since they can be NULL.
4387 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4388 have DECL_WEAK flag set. */
4390 /* Loading a static variable is unduly expensive, but global
4391 registers aren't expensive. */
4393 }
4395 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4396 to be evaluated unconditionally.
4397 I addition to simple_operand_p, we assume that comparisons, conversions,
4398 and logic-not operations are simple, if their operands are simple, too. */
4400 static bool
4402 {
4422 }
4424 \f
4425 /* The following functions are subroutines to fold_range_test and allow it to
4426 try to change a logical combination of comparisons into a range test.
4428 For example, both
4429 X == 2 || X == 3 || X == 4 || X == 5
4430 and
4431 X >= 2 && X <= 5
4432 are converted to
4433 (unsigned) (X - 2) <= 3
4435 We describe each set of comparisons as being either inside or outside
4436 a range, using a variable named like IN_P, and then describe the
4437 range with a lower and upper bound. If one of the bounds is omitted,
4438 it represents either the highest or lowest value of the type.
4440 In the comments below, we represent a range by two numbers in brackets
4441 preceded by a "+" to designate being inside that range, or a "-" to
4442 designate being outside that range, so the condition can be inverted by
4443 flipping the prefix. An omitted bound is represented by a "-". For
4444 example, "- [-, 10]" means being outside the range starting at the lowest
4445 possible value and ending at 10, in other words, being greater than 10.
4446 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4447 always false.
4449 We set up things so that the missing bounds are handled in a consistent
4450 manner so neither a missing bound nor "true" and "false" need to be
4451 handled using a special case. */
4453 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4454 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4455 and UPPER1_P are nonzero if the respective argument is an upper bound
4456 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4457 must be specified for a comparison. ARG1 will be converted to ARG0's
4458 type if both are specified. */
4460 static tree
4463 {
4464 tree tem;
4468 /* If neither arg represents infinity, do the normal operation.
4469 Else, if not a comparison, return infinity. Else handle the special
4470 comparison rules. Note that most of the cases below won't occur, but
4471 are handled for consistency. */
4474 {
4479 }
4484 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4485 for neither. In real maths, we cannot assume open ended ranges are
4486 the same. But, this is computer arithmetic, where numbers are finite.
4487 We can therefore make the transformation of any unbounded range with
4488 the value Z, Z being greater than any representable number. This permits
4489 us to treat unbounded ranges as equal. */
4493 {
4514 }
4517 }
4518 \f
4519 /* Helper routine for make_range. Perform one step for it, return
4520 new expression if the loop should continue or NULL_TREE if it should
4521 stop. */
4523 tree
4527 {
4533 {
4535 /* We can only do something if the range is testing for zero. */
4544 /* We can only do something if the range is testing for zero
4545 and if the second operand is an integer constant. Note that
4546 saying something is "in" the range we make is done by
4547 complementing IN_P since it will set in the initial case of
4548 being not equal to zero; "out" is leaving it alone. */
4555 {
4576 }
4578 /* If this is an unsigned comparison, we also know that EXP is
4579 greater than or equal to zero. We base the range tests we make
4580 on that fact, so we record it here so we can parse existing
4581 range tests. We test arg0_type since often the return type
4582 of, e.g. EQ_EXPR, is boolean. */
4584 {
4588 NULL_TREE))
4593 /* If the high bound is missing, but we have a nonzero low
4594 bound, reverse the range so it goes from zero to the low bound
4595 minus 1. */
4597 {
4602 }
4603 }
4611 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4612 low and high are non-NULL, then normalize will DTRT. */
4615 {
4620 }
4622 /* (-x) IN [a,b] -> x in [-b, -a] */
4634 /* ~ X -> -X - 1 */
4643 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4644 move a constant to the other side. */
4649 /* If EXP is signed, any overflow in the computation is undefined,
4650 so we don't worry about it so long as our computations on
4651 the bounds don't overflow. For unsigned, overflow is defined
4652 and this is exactly the right thing. */
4664 normalize:
4665 /* Check for an unsigned range which has wrapped around the maximum
4666 value thus making n_high < n_low, and normalize it. */
4668 {
4674 /* If the range is of the form +/- [ x+1, x ], we won't
4675 be able to normalize it. But then, it represents the
4676 whole range or the empty set, so make it
4677 +/- [ -, - ]. */
4681 else
4683 }
4684 else
4692 CASE_CONVERT:
4710 /* If we're converting arg0 from an unsigned type, to exp,
4711 a signed type, we will be doing the comparison as unsigned.
4712 The tests above have already verified that LOW and HIGH
4713 are both positive.
4715 So we have to ensure that we will handle large unsigned
4716 values the same way that the current signed bounds treat
4717 negative values. */
4720 {
4721 tree high_positive;
4722 tree equiv_type;
4723 /* For fixed-point modes, we need to pass the saturating flag
4724 as the 2nd parameter. */
4726 equiv_type
4729 else
4730 equiv_type
4733 /* A range without an upper bound is, naturally, unbounded.
4734 Since convert would have cropped a very large value, use
4735 the max value for the destination type. */
4736 high_positive
4743 high_positive),
4746 /* If the low bound is specified, "and" the range with the
4747 range for which the original unsigned value will be
4748 positive. */
4750 {
4753 integer_zero_node),
4754 high_positive))
4758 }
4759 else
4760 {
4761 /* Otherwise, "or" the range with the range of the input
4762 that will be interpreted as negative. */
4765 integer_zero_node),
4766 high_positive))
4770 }
4771 }
4780 }
4781 }
4783 /* Given EXP, a logical expression, set the range it is testing into
4784 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4785 actually being tested. *PLOW and *PHIGH will be made of the same
4786 type as the returned expression. If EXP is not a comparison, we
4787 will most likely not be returning a useful value and range. Set
4788 *STRICT_OVERFLOW_P to true if the return value is only valid
4789 because signed overflow is undefined; otherwise, do not change
4790 *STRICT_OVERFLOW_P. */
4792 tree
4795 {
4803 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4804 and see if we can refine the range. Some of the cases below may not
4805 happen, but it doesn't seem worth worrying about this. We "continue"
4806 the outer loop when we've changed something; otherwise we "break"
4807 the switch, which will "break" the while. */
4813 {
4819 {
4827 }
4836 }
4838 /* If EXP is a constant, we can evaluate whether this is true or false. */
4840 {
4847 }
4851 }
4853 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4854 a bitwise check i.e. when
4855 LOW == 0xXX...X00...0
4856 HIGH == 0xXX...X11...1
4857 Return corresponding mask in MASK and stem in VALUE. */
4859 static bool
4862 {
4885 }
4886 \f
4887 /* Helper routine for build_range_check and match.pd. Return the type to
4888 perform the check or NULL if it shouldn't be optimized. */
4890 tree
4892 {
4893 /* First make sure that arithmetics in this type is valid, then make sure
4894 that it wraps around. */
4900 {
4903 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4904 for the type in question, as we rely on this here. */
4914 else
4916 }
4918 }
4920 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4921 type, TYPE, return an expression to test if EXP is in (or out of, depending
4922 on IN_P) the range. Return 0 if the test couldn't be created. */
4924 tree
4927 {
4930 /* Disable this optimization for function pointer expressions
4931 on targets that require function pointer canonicalization. */
4938 {
4944 }
4966 value);
4969 {
4971 {
4975 }
4977 }
4979 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4981 {
4985 {
4987 {
4990 etype
4992 else
4995 }
4998 }
4999 }
5001 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5002 This requires wrap-around arithmetics for the type of the expression. */
5022 }
5023 \f
5024 /* Return the predecessor of VAL in its type, handling the infinite case. */
5026 static tree
5028 {
5034 else
5037 }
5039 /* Return the successor of VAL in its type, handling the infinite case. */
5041 static tree
5043 {
5049 else
5052 }
5054 /* Given two ranges, see if we can merge them into one. Return 1 if we
5055 can, 0 if we can't. Set the output range into the specified parameters. */
5057 bool
5060 {
5064 tree tem;
5074 /* Make range 0 be the range that starts first, or ends last if they
5075 start at the same value. Swap them if it isn't. */
5078 || (lowequal
5081 {
5085 }
5087 /* If the second range is != high1 where high1 is the type maximum of
5088 the type, try first merging with < high1 range. */
5090 && high1
5097 {
5102 /* Similarly for the second range != low1 where low1 is the type minimum
5103 of the type, try first merging with > low1 range. */
5108 }
5110 /* Now flag two cases, whether the ranges are disjoint or whether the
5111 second range is totally subsumed in the first. Note that the tests
5112 below are simplified by the ones above. */
5118 /* We now have four cases, depending on whether we are including or
5119 excluding the two ranges. */
5121 {
5122 /* If they don't overlap, the result is false. If the second range
5123 is a subset it is the result. Otherwise, the range is from the start
5124 of the second to the end of the first. */
5129 else
5131 }
5134 {
5135 /* If they don't overlap, the result is the first range. If they are
5136 equal, the result is false. If the second range is a subset of the
5137 first, and the ranges begin at the same place, we go from just after
5138 the end of the second range to the end of the first. If the second
5139 range is not a subset of the first, or if it is a subset and both
5140 ranges end at the same place, the range starts at the start of the
5141 first range and ends just before the second range.
5142 Otherwise, we can't describe this as a single range. */
5148 {
5153 {
5154 /* We are in the weird situation where high0 > high1 but
5155 high1 has no successor. Punt. */
5157 }
5158 }
5160 {
5165 {
5166 /* low0 < low1 but low1 has no predecessor. Punt. */
5168 }
5169 }
5170 else
5172 }
5175 {
5176 /* If they don't overlap, the result is the second range. If the second
5177 is a subset of the first, the result is false. Otherwise,
5178 the range starts just after the first range and ends at the
5179 end of the second. */
5184 else
5185 {
5190 {
5191 /* high1 > high0 but high0 has no successor. Punt. */
5193 }
5194 }
5195 }
5197 else
5198 {
5199 /* The case where we are excluding both ranges. Here the complex case
5200 is if they don't overlap. In that case, the only time we have a
5201 range is if they are adjacent. If the second is a subset of the
5202 first, the result is the first. Otherwise, the range to exclude
5203 starts at the beginning of the first range and ends at the end of the
5204 second. */
5206 {
5211 else
5212 {
5213 /* Canonicalize - [min, x] into - [-, x]. */
5216 {
5219 GET_MODE_BITSIZE
5222 /* FALLTHROUGH */
5235 }
5237 /* Canonicalize - [x, max] into - [x, -]. */
5240 {
5243 GET_MODE_BITSIZE
5246 /* FALLTHROUGH */
5262 }
5264 /* The ranges might be also adjacent between the maximum and
5265 minimum values of the given type. For
5266 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5267 return + [x + 1, y - 1]. */
5269 {
5276 }
5277 else
5279 }
5280 }
5283 else
5285 }
5289 }
5290 \f
5292 /* Subroutine of fold, looking inside expressions of the form
5293 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5294 of the COND_EXPR. This function is being used also to optimize
5295 A op B ? C : A, by reversing the comparison first.
5297 Return a folded expression whose code is not a COND_EXPR
5298 anymore, or NULL_TREE if no folding opportunity is found. */
5300 static tree
5303 {
5308 tree tem;
5313 /* If we have A op 0 ? A : -A, consider applying the following
5314 transformations:
5316 A == 0? A : -A same as -A
5317 A != 0? A : -A same as A
5318 A >= 0? A : -A same as abs (A)
5319 A > 0? A : -A same as abs (A)
5320 A <= 0? A : -A same as -abs (A)
5321 A < 0? A : -A same as -abs (A)
5323 None of these transformations work for modes with signed
5324 zeros. If A is +/-0, the first two transformations will
5325 change the sign of the result (from +0 to -0, or vice
5326 versa). The last four will fix the sign of the result,
5327 even though the original expressions could be positive or
5328 negative, depending on the sign of A.
5330 Note that all these transformations are correct if A is
5331 NaN, since the two alternatives (A and -A) are also NaNs. */
5338 /* In the case that A is of the form X-Y, '-A' (arg2) may
5339 have already been folded to Y-X, check for that. */
5347 {
5359 /* Fall through. */
5370 /* FALLTHRU */
5380 }
5382 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5383 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5384 both transformations are correct when A is NaN: A != 0
5385 is then true, and A == 0 is false. */
5389 {
5394 }
5396 /* Try some transformations of A op B ? A : B.
5398 A == B? A : B same as B
5399 A != B? A : B same as A
5400 A >= B? A : B same as max (A, B)
5401 A > B? A : B same as max (B, A)
5402 A <= B? A : B same as min (A, B)
5403 A < B? A : B same as min (B, A)
5405 As above, these transformations don't work in the presence
5406 of signed zeros. For example, if A and B are zeros of
5407 opposite sign, the first two transformations will change
5408 the sign of the result. In the last four, the original
5409 expressions give different results for (A=+0, B=-0) and
5410 (A=-0, B=+0), but the transformed expressions do not.
5412 The first two transformations are correct if either A or B
5413 is a NaN. In the first transformation, the condition will
5414 be false, and B will indeed be chosen. In the case of the
5415 second transformation, the condition A != B will be true,
5416 and A will be chosen.
5418 The conversions to max() and min() are not correct if B is
5419 a number and A is not. The conditions in the original
5420 expressions will be false, so all four give B. The min()
5421 and max() versions would give a NaN instead. */
5424 /* Avoid these transformations if the COND_EXPR may be used
5425 as an lvalue in the C++ front-end. PR c++/19199. */
5426 && (in_gimple_form
5432 {
5438 {
5447 /* In C++ a ?: expression can be an lvalue, so put the
5448 operand which will be used if they are equal first
5449 so that we can convert this back to the
5450 corresponding COND_EXPR. */
5452 {
5460 }
5467 {
5475 }
5488 }
5489 }
5492 }
5495 \f
5496 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5497 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5498 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5499 false) >= 2)
5500 #endif
5502 /* EXP is some logical combination of boolean tests. See if we can
5503 merge it into some range test. Return the new tree if so. */
5505 static tree
5508 {
5524 /* If this is an OR operation, invert both sides; we will invert
5525 again at the end. */
5529 /* If both expressions are the same, if we can merge the ranges, and we
5530 can build the range test, return it or it inverted. If one of the
5531 ranges is always true or always false, consider it to be the same
5532 expression as the other. */
5540 {
5544 }
5546 /* On machines where the branch cost is expensive, if this is a
5547 short-circuited branch and the underlying object on both sides
5548 is the same, make a non-short-circuit operation. */
5550 && !flag_sanitize_coverage
5555 {
5556 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5557 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5558 which cases we can't do this. */
5566 {
5575 {
5578 WARN_STRICT_OVERFLOW_COMPARISON);
5582 }
5583 }
5584 }
5587 }
5588 \f
5589 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5590 bit value. Arrange things so the extra bits will be set to zero if and
5591 only if C is signed-extended to its full width. If MASK is nonzero,
5592 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5594 static tree
5596 {
5599 tree temp;
5604 /* We work by getting just the sign bit into the low-order bit, then
5605 into the high-order bit, then sign-extend. We then XOR that value
5606 with C. */
5610 /* We must use a signed type in order to get an arithmetic right shift.
5611 However, we must also avoid introducing accidental overflows, so that
5612 a subsequent call to integer_zerop will work. Hence we must
5613 do the type conversion here. At this point, the constant is either
5614 zero or one, and the conversion to a signed type can never overflow.
5615 We could get an overflow if this conversion is done anywhere else. */
5624 /* If necessary, convert the type back to match the type of C. */
5629 }
5630 \f
5631 /* For an expression that has the form
5632 (A && B) || ~B
5633 or
5634 (A || B) && ~B,
5635 we can drop one of the inner expressions and simplify to
5636 A || ~B
5637 or
5638 A && ~B
5639 LOC is the location of the resulting expression. OP is the inner
5640 logical operation; the left-hand side in the examples above, while CMPOP
5641 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5642 removing a condition that guards another, as in
5643 (A != NULL && A->...) || A == NULL
5644 which we must not transform. If RHS_ONLY is true, only eliminate the
5645 right-most operand of the inner logical operation. */
5647 static tree
5650 {
5668 {
5671 {
5674 }
5675 }
5677 {
5680 {
5683 }
5684 }
5699 }
5701 /* Find ways of folding logical expressions of LHS and RHS:
5702 Try to merge two comparisons to the same innermost item.
5703 Look for range tests like "ch >= '0' && ch <= '9'".
5704 Look for combinations of simple terms on machines with expensive branches
5705 and evaluate the RHS unconditionally.
5707 For example, if we have p->a == 2 && p->b == 4 and we can make an
5708 object large enough to span both A and B, we can do this with a comparison
5709 against the object ANDed with the a mask.
5711 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5712 operations to do this with one comparison.
5714 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5715 function and the one above.
5717 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5718 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5720 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5721 two operands.
5723 We return the simplified tree or 0 if no optimization is possible. */
5725 static tree
5728 {
5729 /* If this is the "or" of two comparisons, we can do something if
5730 the comparisons are NE_EXPR. If this is the "and", we can do something
5731 if the comparisons are EQ_EXPR. I.e.,
5732 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5734 WANTED_CODE is this operation code. For single bit fields, we can
5735 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5736 comparison for one-bit fields. */
5757 /* Start by getting the comparison codes. Fail if anything is volatile.
5758 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5759 it were surrounded with a NE_EXPR. */
5768 {
5772 }
5775 {
5779 }
5790 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5793 {
5796 {
5801 }
5804 {
5810 }
5811 }
5816 /* If the RHS can be evaluated unconditionally and its operands are
5817 simple, it wins to evaluate the RHS unconditionally on machines
5818 with expensive branches. In this case, this isn't a comparison
5819 that can be merged. */
5826 {
5827 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5838 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5848 }
5850 /* See if the comparisons can be merged. Then get all the parameters for
5851 each side. */
5876 /* It must be true that the inner operation on the lhs of each
5877 comparison must be the same if we are to be able to do anything.
5878 Then see if we have constants. If not, the same must be true for
5879 the rhs's. */
5888 {
5891 }
5896 else
5899 /* If either comparison code is not correct for our logical operation,
5900 fail. However, we can convert a one-bit comparison against zero into
5901 the opposite comparison against that bit being set in the field. */
5905 {
5907 {
5908 /* Make the left operand unsigned, since we are only interested
5909 in the value of one bit. Otherwise we are doing the wrong
5910 thing below. */
5913 }
5914 else
5916 }
5918 /* This is analogous to the code for l_const above. */
5920 {
5922 {
5925 }
5926 else
5928 }
5930 /* See if we can find a mode that contains both fields being compared on
5931 the left. If we can't, fail. Otherwise, update all constants and masks
5932 to be relative to a field of that size. */
5946 {
5949 }
5957 {
5964 {
5968 }
5969 }
5971 {
5978 {
5982 }
5983 }
5985 /* If the right sides are not constant, do the same for it. Also,
5986 disallow this optimization if a size or signedness mismatch occurs
5987 between the left and right sides. */
5989 {
5992 /* Make sure the two fields on the right
5993 correspond to the left without being swapped. */
6010 {
6013 }
6022 /* Make a mask that corresponds to both fields being compared.
6023 Do this for both items being compared. If the operands are the
6024 same size and the bits being compared are in the same position
6025 then we can do this by masking both and comparing the masked
6026 results. */
6033 {
6047 }
6049 /* There is still another way we can do something: If both pairs of
6050 fields being compared are adjacent, we may be able to make a wider
6051 field containing them both.
6053 Note that we still must mask the lhs/rhs expressions. Furthermore,
6054 the mask must be shifted to account for the shift done by
6055 make_bit_field_ref. */
6064 {
6065 tree type;
6081 /* Convert to the smaller type before masking out unwanted bits. */
6084 {
6086 {
6090 }
6092 {
6096 }
6097 }
6106 }
6109 }
6111 /* Handle the case of comparisons with constants. If there is something in
6112 common between the masks, those bits of the constants must be the same.
6113 If not, the condition is always false. Test for this to avoid generating
6114 incorrect code below. */
6119 {
6121 {
6124 }
6125 else
6126 {
6129 }
6130 }
6135 /* Construct the expression we will return. First get the component
6136 reference we will make. Unless the mask is all ones the width of
6137 that field, perform the mask operation. Then compare with the
6138 merged constant. */
6149 }
6150 \f
6151 /* T is an integer expression that is being multiplied, divided, or taken a
6152 modulus (CODE says which and what kind of divide or modulus) by a
6153 constant C. See if we can eliminate that operation by folding it with
6154 other operations already in T. WIDE_TYPE, if non-null, is a type that
6155 should be used for the computation if wider than our type.
6157 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6158 (X * 2) + (Y * 4). We must, however, be assured that either the original
6159 expression would not overflow or that overflow is undefined for the type
6160 in the language in question.
6162 If we return a non-null expression, it is an equivalent form of the
6163 original computation, but need not be in the original type.
6165 We set *STRICT_OVERFLOW_P to true if the return values depends on
6166 signed overflow being undefined. Otherwise we do not change
6167 *STRICT_OVERFLOW_P. */
6169 static tree
6172 {
6173 /* To avoid exponential search depth, refuse to allow recursion past
6174 three levels. Beyond that (1) it's highly unlikely that we'll find
6175 something interesting and (2) we've probably processed it before
6176 when we built the inner expression. */
6179 tree ret;
6184 depth++;
6186 depth--;
6189 }
6191 static tree
6194 {
6206 /* Don't deal with constants of zero here; they confuse the code below. */
6216 /* Note that we need not handle conditional operations here since fold
6217 already handles those cases. So just do arithmetic here. */
6219 {
6221 /* For a constant, we can always simplify if we are a multiply
6222 or (for divide and modulus) if it is a multiple of our constant. */
6226 {
6229 /* If the multiplication overflowed, we lost information on it.
6230 See PR68142 and PR69845. */
6234 }
6238 /* If op0 is an expression ... */
6244 /* ... and has wrapping overflow, and its type is smaller
6245 than ctype, then we cannot pass through as widening. */
6250 /* ... or this is a truncation (t is narrower than op0),
6251 then we cannot pass through this narrowing. */
6254 /* ... or signedness changes for division or modulus,
6255 then we cannot pass through this conversion. */
6259 /* ... or has undefined overflow while the converted to
6260 type has not, we cannot do the operation in the inner type
6261 as that would introduce undefined overflow. */
6267 /* Pass the constant down and see if we can make a simplification. If
6268 we can, replace this expression with the inner simplification for
6269 possible later conversion to our or some other type. */
6280 /* If widening the type changes it from signed to unsigned, then we
6281 must avoid building ABS_EXPR itself as unsigned. */
6283 {
6287 {
6290 }
6292 }
6293 /* If the constant is negative, we cannot simplify this. */
6296 /* FALLTHROUGH */
6298 /* For division and modulus, type can't be unsigned, as e.g.
6299 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6300 For signed types, even with wrapping overflow, this is fine. */
6309 /* If widening the type changes the signedness, then we can't perform
6310 this optimization as that changes the result. */
6314 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6320 {
6327 }
6331 /* If the second operand is constant, this is a multiplication
6332 or floor division, by a power of two, so we can treat it that
6333 way unless the multiplier or divisor overflows. Signed
6334 left-shift overflow is implementation-defined rather than
6335 undefined in C90, so do not convert signed left shift into
6336 multiplication. */
6339 /* const_binop may not detect overflow correctly,
6340 so check for it explicitly here. */
6349 ctype,
6351 t1),
6356 /* See if we can eliminate the operation on both sides. If we can, we
6357 can return a new PLUS or MINUS. If we can't, the only remaining
6358 cases where we can do anything are if the second operand is a
6359 constant. */
6366 /* If not multiplication, we can only do this if both operands
6367 are divisible by c. */
6370 {
6375 }
6377 /* If this was a subtraction, negate OP1 and set it to be an addition.
6378 This simplifies the logic below. */
6380 {
6382 /* If OP1 was not easily negatable, the constant may be OP0. */
6384 {
6387 }
6388 }
6393 /* If either OP1 or C are negative, this optimization is not safe for
6394 some of the division and remainder types while for others we need
6395 to change the code. */
6397 {
6405 }
6407 /* If it's a multiply or a division/modulus operation of a multiple
6408 of our constant, do the operation and verify it doesn't overflow. */
6412 {
6415 /* We allow the constant to overflow with wrapping semantics. */
6419 }
6420 else
6423 /* If we have an unsigned type, we cannot widen the operation since it
6424 will change the result if the original computation overflowed. */
6428 /* The last case is if we are a multiply. In that case, we can
6429 apply the distributive law to commute the multiply and addition
6430 if the multiplication of the constants doesn't overflow
6431 and overflow is defined. With undefined overflow
6432 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6438 op1);
6443 /* We have a special case here if we are doing something like
6444 (C * 8) % 4 since we know that's zero. */
6447 /* If the multiplication can overflow we cannot optimize this. */
6452 {
6455 }
6457 /* ... fall through ... */
6461 /* If we can extract our operation from the LHS, do so and return a
6462 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6463 do something only if the second operand is a constant. */
6479 /* If these are the same operation types, we can associate them
6480 assuming no overflow. */
6482 {
6497 }
6499 /* If these operations "cancel" each other, we have the main
6500 optimizations of this pass, which occur when either constant is a
6501 multiple of the other, in which case we replace this with either an
6502 operation or CODE or TCODE.
6504 If we have an unsigned type, we cannot do this since it will change
6505 the result if the original computation overflowed. */
6512 {
6515 {
6522 }
6525 {
6532 }
6533 }
6538 }
6541 }
6542 \f
6543 /* Return a node which has the indicated constant VALUE (either 0 or
6544 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6545 and is of the indicated TYPE. */
6547 tree
6549 {
6558 else
6560 }
6563 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6564 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6565 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6566 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6567 COND is the first argument to CODE; otherwise (as in the example
6568 given here), it is the second argument. TYPE is the type of the
6569 original expression. Return NULL_TREE if no simplification is
6570 possible. */
6572 static tree
6577 {
6587 {
6591 /* If this operand throws an expression, then it does not make
6592 sense to try to perform a logical or arithmetic operation
6593 involving it. */
6598 }
6601 {
6606 }
6607 else
6608 /* Detect the case of mixing vector and scalar types - bail out. */
6614 /* This transformation is only worthwhile if we don't have to wrap ARG
6615 in a SAVE_EXPR and the operation can be simplified without recursing
6616 on at least one of the branches once its pushed inside the COND_EXPR. */
6625 {
6629 else
6631 }
6633 {
6637 else
6639 }
6641 /* Check that we have simplified at least one of the branches. */
6646 }
6648 \f
6649 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6651 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6652 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6653 ADDEND is the same as X.
6655 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6656 and finite. The problematic cases are when X is zero, and its mode
6657 has signed zeros. In the case of rounding towards -infinity,
6658 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6659 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6661 bool
6663 {
6667 /* Don't allow the fold with -fsignaling-nans. */
6671 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6675 /* In a vector or complex, we would need to check the sign of all zeros. */
6679 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6683 /* The mode has signed zeros, and we have to honor their sign.
6684 In this situation, there is only one case we can return true for.
6685 X - 0 is the same as X unless rounding towards -infinity is
6686 supported. */
6688 }
6690 /* Subroutine of match.pd that optimizes comparisons of a division by
6691 a nonzero integer constant against an integer constant, i.e.
6692 X/C1 op C2.
6694 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6695 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6697 enum tree_code
6700 {
6705 /* We have to do this the hard way to detect unsigned overflow.
6706 prod = int_const_binop (MULT_EXPR, c1, c2); */
6712 {
6716 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6719 }
6721 {
6724 {
6743 }
6744 }
6745 else
6746 {
6747 /* A negative divisor reverses the relational operators. */
6752 {
6771 }
6772 }
6785 }
6788 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6789 equality/inequality test, then return a simplified form of the test
6790 using a sign testing. Otherwise return NULL. TYPE is the desired
6791 result type. */
6793 static tree
6796 tree result_type)
6797 {
6798 /* If this is testing a single bit, we can optimize the test. */
6802 {
6803 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6804 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6808 /* This is only a win if casting to a signed type is cheap,
6809 i.e. when arg00's type is not a partial mode. */
6811 {
6814 result_type,
6817 }
6818 }
6821 }
6823 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6824 equality/inequality test, then return a simplified form of
6825 the test using shifts and logical operations. Otherwise return
6826 NULL. TYPE is the desired result type. */
6828 tree
6831 {
6832 /* If this is testing a single bit, we can optimize the test. */
6836 {
6845 /* First, see if we can fold the single bit test into a sign-bit
6846 test. */
6848 result_type);
6852 /* Otherwise we have (A & C) != 0 where C is a single bit,
6853 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6854 Similarly for (A & C) == 0. */
6856 /* If INNER is a right shift of a constant and it plus BITNUM does
6857 not overflow, adjust BITNUM and INNER. */
6863 {
6866 }
6868 /* If we are going to be able to omit the AND below, we must do our
6869 operations as unsigned. If we must use the AND, we have a choice.
6870 Normally unsigned is faster, but for some machines signed is. */
6888 /* Put the AND last so it can combine with more things. */
6891 /* Make sure to return the proper type. */
6895 }
6897 }
6899 /* Test whether it is preferable two swap two operands, ARG0 and
6900 ARG1, for example because ARG0 is an integer constant and ARG1
6901 isn't. */
6903 bool
6905 {
6919 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6920 for commutative and comparison operators. Ensuring a canonical
6921 form allows the optimizers to find additional redundancies without
6922 having to explicitly check for both orderings. */
6928 /* Put SSA_NAMEs last. */
6934 /* Put variables last. */
6941 }
6944 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6945 means A >= Y && A != MAX, but in this case we know that
6946 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6948 static tree
6950 {
6957 else
6966 {
6969 }
6971 {
6974 }
6975 else
6982 {
6983 /* Convert the pointer types into integer before taking the difference. */
6987 }
6988 else
6995 }
6997 /* Fold a sum or difference of at least one multiplication.
6998 Returns the folded tree or NULL if no simplification could be made. */
7000 static tree
7003 {
7007 /* (A * C) +- (B * C) -> (A+-B) * C.
7008 (A * C) +- A -> A * (C+-1).
7009 We are most concerned about the case where C is a constant,
7010 but other combinations show up during loop reduction. Since
7011 it is not difficult, try all four possibilities. */
7014 {
7017 }
7019 {
7022 }
7023 else
7024 {
7025 /* We cannot generate constant 1 for fract. */
7030 }
7032 {
7035 }
7037 {
7039 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7040 the purpose of this canonicalization. */
7044 {
7047 }
7048 else
7050 }
7051 else
7052 {
7053 /* We cannot generate constant 1 for fract. */
7058 }
7061 /* Prefer factoring a common non-constant. */
7071 /* No identical multiplicands; see if we can find a common
7072 power-of-two factor in non-power-of-two multiplies. This
7073 can help in multi-dimensional array access. */
7076 {
7079 tree maybe_same;
7083 /* Move min of absolute values to int11. */
7085 {
7090 }
7091 else
7095 /* The remainder should not be a constant, otherwise we
7096 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7097 increased the number of multiplications necessary. */
7099 {
7107 }
7108 }
7115 /* We are neither factoring zero nor minus one. */
7123 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7124 same may be minus one and thus the multiplication may overflow. Perform
7125 the sum operation in an unsigned type. */
7130 /* If the sum evaluated to a constant that is not -INF the multiplication
7131 cannot overflow. */
7138 /* Do not resort to unsigned multiplication because
7139 we lose the no-overflow property of the expression. */
7141 }
7143 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7144 specified by EXPR into the buffer PTR of length LEN bytes.
7145 Return the number of bytes placed in the buffer, or zero
7146 upon failure. */
7148 static int
7150 {
7162 /* Dry run. */
7168 {
7170 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7171 number of bytes. */
7175 {
7182 else
7184 }
7185 else
7189 }
7191 }
7194 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7195 specified by EXPR into the buffer PTR of length LEN bytes.
7196 Return the number of bytes placed in the buffer, or zero
7197 upon failure. */
7199 static int
7201 {
7205 FIXED_VALUE_TYPE value;
7220 }
7223 /* Subroutine of native_encode_expr. Encode the REAL_CST
7224 specified by EXPR into the buffer PTR of length LEN bytes.
7225 Return the number of bytes placed in the buffer, or zero
7226 upon failure. */
7228 static int
7230 {
7236 /* There are always 32 bits in each long, no matter the size of
7237 the hosts long. We handle floating point representations with
7238 up to 192 bits. */
7247 /* Dry run. */
7256 {
7261 {
7268 else
7270 }
7271 else
7272 {
7275 {
7276 /* Reverse bytes within each long, or within the entire float
7277 if it's smaller than a long (for HFmode). */
7280 }
7281 }
7286 }
7288 }
7290 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7291 specified by EXPR into the buffer PTR of length LEN bytes.
7292 Return the number of bytes placed in the buffer, or zero
7293 upon failure. */
7295 static int
7297 {
7299 tree part;
7313 }
7316 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7317 specified by EXPR into the buffer PTR of length LEN bytes.
7318 Return the number of bytes placed in the buffer, or zero
7319 upon failure. */
7321 static int
7323 {
7334 {
7336 {
7339 }
7350 }
7352 }
7355 /* Subroutine of native_encode_expr. Encode the STRING_CST
7356 specified by EXPR into the buffer PTR of length LEN bytes.
7357 Return the number of bytes placed in the buffer, or zero
7358 upon failure. */
7360 static int
7362 {
7365 /* Wide-char strings are encoded in target byte-order so native
7366 encoding them is trivial. */
7381 {
7384 {
7387 }
7390 }
7391 else
7394 }
7397 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7398 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7399 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7400 anything, just do a dry run. If OFF is not -1 then start
7401 the encoding at byte offset OFF and encode at most LEN bytes.
7402 Return the number of bytes placed in the buffer, or zero upon failure. */
7404 int
7406 {
7407 /* We don't support starting at negative offset and -1 is special. */
7412 {
7433 }
7434 }
7437 /* Subroutine of native_interpret_expr. Interpret the contents of
7438 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7439 If the buffer cannot be interpreted, return NULL_TREE. */
7441 static tree
7443 {
7453 }
7456 /* Subroutine of native_interpret_expr. Interpret the contents of
7457 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7458 If the buffer cannot be interpreted, return NULL_TREE. */
7460 static tree
7462 {
7465 double_int result;
7466 FIXED_VALUE_TYPE fixed_value;
7476 }
7479 /* Subroutine of native_interpret_expr. Interpret the contents of
7480 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7481 If the buffer cannot be interpreted, return NULL_TREE. */
7483 static tree
7485 {
7489 /* There are always 32 bits in each long, no matter the size of
7490 the hosts long. We handle floating point representations with
7491 up to 192 bits. */
7492 REAL_VALUE_TYPE r;
7502 {
7503 /* Both OFFSET and BYTE index within a long;
7504 bitpos indexes the whole float. */
7507 {
7514 else
7516 }
7517 else
7518 {
7521 {
7522 /* Reverse bytes within each long, or within the entire float
7523 if it's smaller than a long (for HFmode). */
7526 }
7527 }
7531 }
7535 }
7538 /* Subroutine of native_interpret_expr. Interpret the contents of
7539 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7540 If the buffer cannot be interpreted, return NULL_TREE. */
7542 static tree
7544 {
7559 }
7562 /* Subroutine of native_interpret_expr. Interpret the contents of
7563 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7564 If the buffer cannot be interpreted, return NULL_TREE. */
7566 static tree
7568 {
7581 {
7586 }
7588 }
7591 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7592 the buffer PTR of length LEN as a constant of type TYPE. For
7593 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7594 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7595 return NULL_TREE. */
7597 tree
7599 {
7601 {
7623 }
7624 }
7626 /* Returns true if we can interpret the contents of a native encoding
7627 as TYPE. */
7629 static bool
7631 {
7633 {
7646 }
7647 }
7650 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7651 TYPE at compile-time. If we're unable to perform the conversion
7652 return NULL_TREE. */
7654 static tree
7656 {
7657 /* We support up to 512-bit values (for V8DFmode). */
7661 /* Check that the host and target are sane. */
7670 }
7672 /* Build an expression for the address of T. Folds away INDIRECT_REF
7673 to avoid confusing the gimplify process. */
7675 tree
7677 {
7678 /* The size of the object is not relevant when talking about its address. */
7683 {
7688 }
7698 {
7703 }
7704 else
7708 }
7710 /* Build an expression for the address of T. */
7712 tree
7714 {
7718 }
7720 /* Fold a unary expression of code CODE and type TYPE with operand
7721 OP0. Return the folded expression if folding is successful.
7722 Otherwise, return NULL_TREE. */
7724 tree
7726 {
7727 tree tem;
7728 tree arg0;
7736 {
7739 {
7740 /* Don't use STRIP_NOPS, because signedness of argument type
7741 matters. */
7743 }
7744 else
7745 {
7746 /* Strip any conversions that don't change the mode. This
7747 is safe for every expression, except for a comparison
7748 expression because its signedness is derived from its
7749 operands.
7751 Note that this is done as an internal manipulation within
7752 the constant folder, in order to find the simplest
7753 representation of the arguments so that their form can be
7754 studied. In any cases, the appropriate type conversions
7755 should be put back in the tree that will get out of the
7756 constant folder. */
7758 }
7761 {
7764 {
7768 }
7769 }
7770 }
7777 {
7784 {
7798 /* If this was a conversion, and all we did was to move into
7799 inside the COND_EXPR, bring it back out. But leave it if
7800 it is a conversion from integer to integer and the
7801 result precision is no wider than a word since such a
7802 conversion is cheap and may be optimized away by combine,
7803 while it couldn't if it were outside the COND_EXPR. Then return
7804 so we don't get into an infinite recursion loop taking the
7805 conversion out and then back in. */
7817 && (INTEGRAL_TYPE_P
7830 }
7831 }
7834 {
7840 CASE_CONVERT:
7844 {
7845 /* If we have (type) (a CMP b) and type is an integral type, return
7846 new expression involving the new type. Canonicalize
7847 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7848 non-integral type.
7849 Do not fold the result as that would not simplify further, also
7850 folding again results in recursions. */
7860 }
7862 /* Handle (T *)&A.B.C for A being of type T and B and C
7863 living at offset zero. This occurs frequently in
7864 C++ upcasting and then accessing the base. */
7868 {
7870 tree offset;
7871 machine_mode mode;
7873 tree base
7877 /* If the reference was to a (constant) zero offset, we can use
7878 the address of the base if it has the same base type
7879 as the result type and the pointer type is unqualified. */
7887 }
7891 /* Detect assigning a bitfield. */
7893 && DECL_BIT_FIELD
7895 {
7896 /* Don't leave an assignment inside a conversion
7897 unless assigning a bitfield. */
7899 /* First do the assignment, then return converted constant. */
7904 }
7906 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7907 constants (if x has signed type, the sign bit cannot be set
7908 in c). This folds extension into the BIT_AND_EXPR.
7909 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7910 very likely don't have maximal range for their precision and this
7911 transformation effectively doesn't preserve non-maximal ranges. */
7915 {
7926 <= HOST_BITS_PER_WIDE_INT
7928 {
7932 cst &= HOST_WIDE_INT_M1U
7936 && !flag_syntax_only
7939 {
7943 }
7944 }
7946 {
7951 }
7952 }
7954 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7955 cast (T1)X will fold away. We assume that this happens when X itself
7956 is a cast. */
7960 {
7964 return fold_build_pointer_plus_loc
7966 }
7968 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7969 of the same precision, and X is an integer type not narrower than
7970 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7976 {
7982 }
7984 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7985 type of X and Y (integer types only). */
7990 {
7991 /* Be careful not to introduce new overflows. */
7992 tree mult_type;
7995 else
7999 {
8006 }
8007 }
8013 {
8020 }
8031 /* Convert fabs((double)float) into (double)fabsf(float). */
8034 {
8040 targ0));
8041 }
8045 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8064 /* Note that the operand of this must be an int
8065 and its values must be 0 or 1.
8066 ("true" is a fixed value perhaps depending on the language,
8067 but we don't handle values other than 1 correctly yet.) */
8074 /* Fold *&X to X if X is an lvalue. */
8076 {
8083 }
8089 }
8092 /* If the operation was a conversion do _not_ mark a resulting constant
8093 with TREE_OVERFLOW if the original constant was not. These conversions
8094 have implementation defined behavior and retaining the TREE_OVERFLOW
8095 flag here would confuse later passes such as VRP. */
8096 tree
8099 {
8108 }
8110 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8111 operands OP0 and OP1. LOC is the location of the resulting expression.
8112 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8113 Return the folded expression if folding is successful. Otherwise,
8114 return NULL_TREE. */
8115 static tree
8118 {
8119 tree tem;
8121 /* We only do these simplifications if we are optimizing. */
8125 /* Check for things like (A || B) && (A || C). We can convert this
8126 to A || (B && C). Note that either operator can be any of the four
8127 truth and/or operations and the transformation will still be
8128 valid. Also note that we only care about order for the
8129 ANDIF and ORIF operators. If B contains side effects, this
8130 might change the truth-value of A. */
8137 {
8157 /* This case if tricky because we must either have commutative
8158 operators or else A10 must not have side-effects. */
8164 a01);
8165 }
8167 /* See if we can build a range comparison. */
8173 {
8177 }
8181 {
8185 }
8187 /* Check for the possibility of merging component references. If our
8188 lhs is another similar operation, try to merge its rhs with our
8189 rhs. Then try to merge our lhs and rhs. */
8199 && !flag_sanitize_coverage
8204 {
8211 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8212 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8213 We don't want to pack more than two leafs to a non-IF AND/OR
8214 expression.
8215 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8216 equal to IF-CODE, then we don't want to add right-hand operand.
8217 If the inner right-hand side of left-hand operand has
8218 side-effects, or isn't simple, then we can't add to it,
8219 as otherwise we might destroy if-sequence. */
8222 /* Needed for sequence points to handle trappings, and
8223 side-effects. */
8225 {
8227 arg1);
8229 tem);
8230 }
8231 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8232 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8235 /* Needed for sequence points to handle trappings, and
8236 side-effects. */
8238 {
8243 }
8244 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8245 into (A OR B).
8246 For sequence point consistancy, we need to check for trapping,
8247 and side-effects. */
8251 }
8254 }
8256 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8257 by changing CODE to reduce the magnitude of constants involved in
8258 ARG0 of the comparison.
8259 Returns a canonicalized comparison tree if a simplification was
8260 possible, otherwise returns NULL_TREE.
8261 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8262 valid if signed overflow is undefined. */
8264 static tree
8268 {
8273 /* Match A +- CST code arg1. We can change this only if overflow
8274 is undefined. */
8277 /* In principle pointers also have undefined overflow behavior,
8278 but that causes problems elsewhere. */
8285 /* Identify the constant in arg0 and its sign. */
8289 /* Overflowed constants and zero will cause problems. */
8294 /* See if we can reduce the magnitude of the constant in
8295 arg0 by changing the comparison code. */
8296 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8300 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8304 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8308 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8312 else
8316 /* Now build the constant reduced in magnitude. But not if that
8317 would produce one outside of its types range. */
8333 }
8335 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8336 overflow further. Try to decrease the magnitude of constants involved
8337 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8338 and put sole constants at the second argument position.
8339 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8341 static tree
8344 {
8345 tree t;
8350 /* Try canonicalization by simplifying arg0. */
8355 {
8359 }
8361 /* Try canonicalization by simplifying arg1 using the swapped
8362 comparison. */
8370 }
8372 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8373 space. This is used to avoid issuing overflow warnings for
8374 expressions like &p->x which can not wrap. */
8376 static bool
8378 {
8385 poly_wide_int wi_offset;
8391 else
8396 precision);
8411 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8412 array. */
8421 }
8423 /* Return a positive integer when the symbol DECL is known to have
8424 a nonzero address, zero when it's known not to (e.g., it's a weak
8425 symbol), and a negative integer when the symbol is not yet in the
8426 symbol table and so whether or not its address is zero is unknown.
8427 For function local objects always return positive integer. */
8428 static int
8430 {
8435 /* Function local objects are never NULL. */
8443 }
8445 /* Subroutine of fold_binary. This routine performs all of the
8446 transformations that are common to the equality/inequality
8447 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8448 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8449 fold_binary should call fold_binary. Fold a comparison with
8450 tree code CODE and type TYPE with operands OP0 and OP1. Return
8451 the folded comparison or NULL_TREE. */
8453 static tree
8456 {
8466 /* For comparisons of pointers we can decompose it to a compile time
8467 comparison of the base objects and the offsets into the object.
8468 This requires at least one operand being an ADDR_EXPR or a
8469 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8475 {
8478 machine_mode mode;
8482 /* Get base and offset for the access. Strip ADDR_EXPR for
8483 get_inner_reference, but put it back by stripping INDIRECT_REF
8484 off the base object if possible. indirect_baseN will be true
8485 if baseN is not an address but refers to the object itself. */
8488 {
8489 base0
8495 else
8497 }
8499 {
8503 {
8504 base0
8510 else
8512 }
8515 else
8519 {
8526 }
8527 }
8531 {
8532 base1
8538 else
8540 }
8542 {
8546 {
8547 base1
8553 else
8555 }
8558 else
8562 {
8569 }
8570 }
8572 /* If we have equivalent bases we might be able to simplify. */
8576 {
8577 /* We can fold this expression to a constant if the non-constant
8578 offset parts are equal. */
8582 && (equality_code
8583 || (indirect_base0
8586 {
8592 "occur when comparing P +- C1 with "
8594 WARN_STRICT_OVERFLOW_CONDITIONAL);
8597 {
8635 }
8636 }
8637 /* We can simplify the comparison to a comparison of the variable
8638 offset parts if the constant offset parts are equal.
8639 Be careful to use signed sizetype here because otherwise we
8640 mess with array offsets in the wrong way. This is possible
8641 because pointer arithmetic is restricted to retain within an
8642 object and overflow on pointer differences is undefined as of
8643 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8645 && (equality_code
8646 || (indirect_base0
8649 {
8650 /* By converting to signed sizetype we cover middle-end pointer
8651 arithmetic which operates on unsigned pointer types of size
8652 type size and ARRAY_REF offsets which are properly sign or
8653 zero extended from their type in case it is narrower than
8654 sizetype. */
8657 else
8661 else
8668 "occur when comparing P +- C1 with "
8670 WARN_STRICT_OVERFLOW_COMPARISON);
8673 }
8674 }
8675 /* For equal offsets we can simplify to a comparison of the
8676 base addresses. */
8678 && (indirect_base0
8680 && (indirect_base1
8685 {
8691 }
8692 /* Comparison between an ordinary (non-weak) symbol and a null
8693 pointer can be eliminated since such symbols must have a non
8694 null address. In C, relational expressions between pointers
8695 to objects and null pointers are undefined. The results
8696 below follow the C++ rules with the additional property that
8697 every object pointer compares greater than a null pointer.
8698 */
8701 /* Avoid folding references to struct members at offset 0 to
8702 prevent tests like '&ptr->firstmember == 0' from getting
8703 eliminated. When ptr is null, although the -> expression
8704 is strictly speaking invalid, GCC retains it as a matter
8705 of QoI. See PR c/44555. */
8708 && indirect_base0
8709 /* The caller guarantees that when one of the arguments is
8710 constant (i.e., null in this case) it is second. */
8712 {
8714 {
8725 }
8726 }
8727 }
8729 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8730 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8731 the resulting offset is smaller in absolute value than the
8732 original one and has the same sign. */
8741 {
8746 tree cst;
8748 "occur when combining constants around "
8751 /* Put the constant on the side where it doesn't overflow and is
8752 of lower absolute value and of same sign than before. */
8759 {
8762 variable1,
8766 }
8774 {
8780 variable2);
8781 }
8782 }
8788 /* If we are comparing an expression that just has comparisons
8789 of two integer values, arithmetic expressions of those comparisons,
8790 and constants, we can simplify it. There are only three cases
8791 to check: the two values can either be equal, the first can be
8792 greater, or the second can be greater. Fold the expression for
8793 those three values. Since each value must be 0 or 1, we have
8794 eight possibilities, each of which corresponds to the constant 0
8795 or 1 or one of the six possible comparisons.
8797 This handles common cases like (a > b) == 0 but also handles
8798 expressions like ((x > y) - (y > x)) > 0, which supposedly
8799 occur in macroized code. */
8802 {
8806 /* Don't handle degenerate cases here; they should already
8807 have been handled anyway. */
8816 {
8820 /* We can't just pass T to eval_subst in case cval1 or cval2
8821 was the same as ARG1. */
8823 tree high_result
8827 arg1);
8828 tree equal_result
8832 arg1);
8833 tree low_result
8837 arg1);
8839 /* All three of these results should be 0 or 1. Confirm they are.
8840 Then use those values to select the proper code to use. */
8845 {
8846 /* Make a 3-bit mask with the high-order bit being the
8847 value for `>', the next for '=', and the low for '<'. */
8851 {
8853 /* Always false. */
8874 /* Always true. */
8876 }
8879 }
8880 }
8881 }
8884 }
8887 /* Subroutine of fold_binary. Optimize complex multiplications of the
8888 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8889 argument EXPR represents the expression "z" of type TYPE. */
8891 static tree
8893 {
8898 {
8901 }
8903 {
8906 }
8907 else
8908 {
8912 }
8921 }
8924 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8925 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8926 true if successful. */
8928 static bool
8930 {
8935 {
8938 }
8940 {
8946 else
8948 }
8949 else
8955 }
8957 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8958 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8959 NULL_TREE otherwise. */
8961 static tree
8963 {
8984 {
8985 HOST_WIDE_INT index;
8991 }
8994 {
9000 }
9001 else
9003 }
9005 /* Try to fold a pointer difference of type TYPE two address expressions of
9006 array references AREF0 and AREF1 using location LOC. Return a
9007 simplified expression for the difference or NULL_TREE. */
9009 static tree
9013 {
9018 /* If the bases are array references as well, recurse. If the bases
9019 are pointer indirections compute the difference of the pointers.
9020 If the bases are equal, we are set. */
9023 && (base_offset
9025 use_pointer_diff)))
9028 && (base_offset
9029 = use_pointer_diff
9039 {
9045 base_offset,
9048 }
9050 }
9052 /* If the real or vector real constant CST of type TYPE has an exact
9053 inverse, return it, else return NULL. */
9055 tree
9057 {
9058 REAL_VALUE_TYPE r;
9059 tree unit_type;
9060 machine_mode mode;
9063 {
9073 {
9077 tree_vector_builder elts;
9082 {
9087 }
9090 }
9094 }
9095 }
9097 /* Mask out the tz least significant bits of X of type TYPE where
9098 tz is the number of trailing zeroes in Y. */
9099 static wide_int
9101 {
9106 }
9108 /* Return true when T is an address and is known to be nonzero.
9109 For floating point we further ensure that T is not denormal.
9110 Similar logic is present in nonzero_address in rtlanal.h.
9112 If the return value is based on the assumption that signed overflow
9113 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9114 change *STRICT_OVERFLOW_P. */
9116 static bool
9118 {
9122 /* Doing something useful for floating point would need more work. */
9128 {
9131 strict_overflow_p);
9137 strict_overflow_p);
9145 }
9148 {
9151 strict_overflow_p);
9159 strict_overflow_p);
9174 strict_overflow_p);
9178 strict_overflow_p);
9181 {
9193 }
9197 }
9199 }
9201 /* Return true when T is an address and is known to be nonzero.
9202 Handle warnings about undefined signed overflow. */
9204 bool
9206 {
9213 "determining that expression is always "
9215 WARN_STRICT_OVERFLOW_MISC);
9217 }
9219 /* Return true if T is known not to be equal to an integer W. */
9221 bool
9223 {
9225 value_range_type rtype;
9227 {
9236 {
9241 }
9246 /* If T has some known zero bits and W has any of those bits set,
9247 then T is known not to be equal to W. */
9255 }
9256 }
9258 /* Fold a binary expression of code CODE and type TYPE with operands
9259 OP0 and OP1. LOC is the location of the resulting expression.
9260 Return the folded expression if folding is successful. Otherwise,
9261 return NULL_TREE. */
9263 tree
9266 {
9281 /* Strip any conversions that don't change the mode. This is
9282 safe for every expression, except for a comparison expression
9283 because its signedness is derived from its operands. So, in
9284 the latter case, only strip conversions that don't change the
9285 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9286 preserved.
9288 Note that this is done as an internal manipulation within the
9289 constant folder, in order to find the simplest representation
9290 of the arguments so that their form can be studied. In any
9291 cases, the appropriate type conversions should be put back in
9292 the tree that will get out of the constant folder. */
9295 {
9298 }
9299 else
9300 {
9303 }
9305 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9306 constant but we can't do arithmetic on them. */
9308 {
9311 {
9315 }
9316 }
9318 /* If this is a commutative operation, and ARG0 is a constant, move it
9319 to ARG1 to reduce the number of tests below. */
9324 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9325 to ARG1 to reduce the number of tests below. */
9334 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9336 First check for cases where an arithmetic operation is applied to a
9337 compound, conditional, or comparison operation. Push the arithmetic
9338 operation inside the compound or conditional to see if any folding
9339 can then be done. Convert comparison to conditional for this purpose.
9340 The also optimizes non-constant cases that used to be done in
9341 expand_expr.
9343 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9344 one of the operands is a comparison and the other is a comparison, a
9345 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9346 code below would make the expression more complex. Change it to a
9347 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9348 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9361 {
9365 boolean_type_node,
9373 }
9377 {
9379 {
9384 tem);
9385 }
9387 {
9392 tem);
9393 }
9398 {
9404 }
9409 {
9415 }
9416 }
9419 {
9421 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9424 {
9430 }
9432 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9435 {
9436 tree base;
9437 poly_int64 coffset;
9446 }
9451 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9457 arg1),
9459 arg0)));
9465 {
9466 /* X + (X / CST) * -CST is X % CST. */
9471 {
9480 cst0));
9481 }
9482 }
9484 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9485 one. Make sure the type is not saturating and has the signedness of
9486 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9487 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9494 {
9498 }
9501 {
9502 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9503 (plus (plus (mult) (mult)) (foo)) so that we can
9504 take advantage of the factoring cases below. */
9513 {
9519 else
9532 parg0),
9534 marg)),
9538 return
9544 parg1)));
9545 }
9546 }
9547 else
9548 {
9549 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9550 to __complex__ ( x, y ). This is not the same for SNaNs or
9551 if signed zeros are involved. */
9555 {
9562 {
9566 {
9572 }
9574 {
9580 }
9581 }
9582 }
9584 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9585 We associate floats only if the user has specified
9586 -fassociative-math. */
9590 {
9595 {
9596 tree tree0;
9599 }
9600 }
9601 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9602 We associate floats only if the user has specified
9603 -fassociative-math. */
9607 {
9612 {
9613 tree tree0;
9616 }
9617 }
9618 }
9620 bit_rotate:
9621 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9622 is a rotate of A by C1 bits. */
9623 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9624 is a rotate of A by B bits.
9625 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9626 though in this case CODE must be | and not + or ^, otherwise
9627 it doesn't return A when B is 0. */
9628 {
9630 tree rtype;
9639 /* Only create rotates in complete modes. Other cases are not
9640 expanded properly. */
9643 {
9656 {
9661 }
9666 {
9669 code0 == LSHIFT_EXPR
9672 }
9674 {
9684 {
9688 orig_tree01);
9690 }
9691 }
9695 {
9706 {
9710 orig_tree01);
9712 }
9713 }
9714 }
9715 }
9717 associate:
9718 /* In most languages, can't associate operations on floats through
9719 parentheses. Rather than remember where the parentheses were, we
9720 don't associate floats at all, unless the user has specified
9721 -fassociative-math.
9722 And, we need to make sure type is not saturating. */
9726 {
9732 /* Split both trees into variables, constants, and literals. Then
9733 associate each group together, the constants with literals,
9734 then the result with variables. This increases the chances of
9735 literals being recombined later and of generating relocatable
9736 expressions for the sum of a constant and literal. */
9744 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9748 /* With undefined overflow prefer doing association in a type
9749 which wraps on overflow, if that is one of the operand types. */
9752 {
9760 }
9762 /* With undefined overflow we can only associate constants with one
9763 variable, and constants whose association doesn't overflow. */
9766 {
9768 {
9769 /* ??? If split_tree would handle NEGATE_EXPR we could
9770 simply reject these cases and the allowed cases would
9771 be the var0/minus_var1 ones. */
9777 {
9780 }
9787 {
9790 }
9796 /* The only case we can still associate with two variables
9797 is if they cancel out. */
9801 }
9807 }
9809 /* Only do something if we found more than two objects. Otherwise,
9810 nothing has changed and we risk infinite recursion. */
9818 {
9830 {
9834 }
9836 {
9840 }
9842 /* Preserve the MINUS_EXPR if the negative part of the literal is
9843 greater than the positive part. Otherwise, the multiplicative
9844 folding code (i.e extract_muldiv) may be fooled in case
9845 unsigned constants are subtracted, like in the following
9846 example: ((X*2 + 4) - 8U)/2. */
9848 {
9852 /* But avoid ending up with only negated parts. */
9854 {
9858 }
9859 else
9860 {
9864 }
9865 }
9867 /* Don't introduce overflows through reassociation. */
9872 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9879 /* Eliminate minus_con0. */
9881 {
9888 else
9891 }
9893 /* Eliminate minus_var0. */
9895 {
9899 else
9902 }
9904 return
9907 }
9908 }
9914 /* Fold &a[i] - &a[j] to i-j. */
9919 {
9923 code
9927 }
9929 /* Further transformations are not for pointers. */
9933 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9936 /* If arg0 is e.g. unsigned int and type is int, then this could
9937 introduce UB, because if A is INT_MIN at runtime, the original
9938 expression can be well defined while the latter is not.
9939 See PR83269. */
9948 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9949 __complex__ ( x, -y ). This is not the same for SNaNs or if
9950 signed zeros are involved. */
9954 {
9961 {
9965 {
9967 arg1r ? arg1r
9972 }
9974 {
9978 arg1i ? arg1i
9981 }
9982 }
9983 }
9985 /* A - B -> A + (-B) if B is easily negatable. */
9989 /* Avoid this transformation if B is a positive REAL_CST. */
9997 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9998 one. Make sure the type is not saturating and has the signedness of
9999 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10000 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10007 {
10011 }
10017 {
10018 /* Transform x * -C into -x * C if x is easily negatable. */
10033 {
10036 "occur when simplifying "
10038 WARN_STRICT_OVERFLOW_MISC);
10040 }
10042 /* Optimize z * conj(z) for integer complex numbers. */
10049 }
10050 else
10051 {
10052 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10053 This is not the same for NaNs or if signed zeros are
10054 involved. */
10060 {
10063 return
10069 return
10074 }
10076 /* Optimize z * conj(z) for floating point complex numbers.
10077 Guarded by flag_unsafe_math_optimizations as non-finite
10078 imaginary components don't produce scalar results. */
10087 }
10091 /* Canonicalize (X & C1) | C2. */
10095 {
10100 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10108 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10110 {
10113 }
10115 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10116 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10117 mode which allows further optimizations. */
10122 {
10127 {
10130 }
10131 }
10134 {
10139 }
10140 }
10142 /* See if this can be simplified into a rotate first. If that
10143 is unsuccessful continue in the association code. */
10147 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10155 /* See if this can be simplified into a rotate first. If that
10156 is unsuccessful continue in the association code. */
10160 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10165 {
10166 tree tem2;
10173 }
10174 /* Fold ~X & 1 as (X & 1) == 0. */
10178 {
10179 tree tem2;
10186 }
10187 /* Fold !X & 1 as X == 0. */
10190 {
10194 }
10196 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10197 multiple of 1 << CST. */
10199 {
10206 }
10208 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10209 bits from CST2. */
10213 {
10215 wide_int masked
10222 {
10223 /* Avoid the transform if arg1 is a mask of some
10224 mode which allows further optimizations. */
10231 }
10232 }
10234 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10235 ((A & N) + B) & M -> (A + B) & M
10236 Similarly if (N & M) == 0,
10237 ((A | N) + B) & M -> (A + B) & M
10238 and for - instead of + (or unary - instead of +)
10239 and/or ^ instead of |.
10240 If B is constant and (B & M) == 0, fold into A & M. */
10242 {
10251 {
10254 wide_int cst0;
10256 /* Now we know that arg0 is (C + D) or (C - D) or
10257 -C and arg1 (M) is == (1LL << cst) - 1.
10258 Store C into PMOP[0] and D into PMOP[1]. */
10262 {
10265 }
10272 {
10281 {
10284 }
10287 /* If C or D is of the form (A & N) where
10288 (N & M) == M, or of the form (A | N) or
10289 (A ^ N) where (N & M) == 0, replace it with A. */
10293 /* If C or D is a N where (N & M) == 0, it can be
10294 omitted (assumed 0). */
10302 }
10304 /* Only build anything new if we optimized one or both arguments
10305 above. */
10309 {
10312 {
10313 /* Perform the operations in a type that has defined
10314 overflow behavior. */
10320 }
10325 {
10333 else
10335 }
10338 else
10341 /* TEM is now the new binary +, - or unary - replacement. */
10345 }
10346 }
10347 }
10349 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10352 {
10357 return
10359 }
10364 /* Don't touch a floating-point divide by zero unless the mode
10365 of the constant can represent infinity. */
10371 /* (-A) / (-B) -> A / B */
10383 /* Fall through */
10386 /* Simplify A / (B << N) where A and B are positive and B is
10387 a power of 2, to A >> (N + log2(B)). */
10392 {
10395 {
10403 WARN_STRICT_OVERFLOW_MISC);
10409 }
10410 }
10412 /* Fall through */
10420 /* Convert -A / -B to A / B when the type is signed and overflow is
10421 undefined. */
10425 {
10428 "when distributing negation across "
10430 WARN_STRICT_OVERFLOW_MISC);
10435 }
10439 {
10442 "when distributing negation across "
10444 WARN_STRICT_OVERFLOW_MISC);
10449 }
10451 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10452 operation, EXACT_DIV_EXPR.
10454 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10455 At one time others generated faster code, it's not clear if they do
10456 after the last round to changes to the DIV code in expmed.c. */
10467 {
10471 WARN_STRICT_OVERFLOW_MISC);
10473 }
10485 {
10489 WARN_STRICT_OVERFLOW_MISC);
10491 }
10499 /* Since negative shift count is not well-defined,
10500 don't try to compute it in the compiler. */
10506 /* If we have a rotate of a bit operation with the rotate count and
10507 the second operand of the bit operation both constant,
10508 permute the two operations. */
10514 {
10522 }
10524 /* Two consecutive rotates adding up to the some integer
10525 multiple of the precision of the type can be ignored. */
10541 /* Note that the operands of this must be ints
10542 and their values must be 0 or 1.
10543 ("true" is a fixed value perhaps depending on the language.) */
10544 /* If first arg is constant zero, return it. */
10547 /* FALLTHRU */
10549 /* If either arg is constant true, drop it. */
10553 /* Preserve sequence points. */
10556 /* If second arg is constant zero, result is zero, but first arg
10557 must be evaluated. */
10560 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10561 case will be handled here. */
10565 /* !X && X is always false. */
10569 /* X && !X is always false. */
10574 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10575 means A >= Y && A != MAX, but in this case we know that
10576 A < X <= MAX. */
10580 {
10588 }
10597 /* Note that the operands of this must be ints
10598 and their values must be 0 or true.
10599 ("true" is a fixed value perhaps depending on the language.) */
10600 /* If first arg is constant true, return it. */
10603 /* FALLTHRU */
10605 /* If either arg is constant zero, drop it. */
10609 /* Preserve sequence points. */
10612 /* If second arg is constant true, result is true, but we must
10613 evaluate first arg. */
10616 /* Likewise for first arg, but note this only occurs here for
10617 TRUTH_OR_EXPR. */
10621 /* !X || X is always true. */
10625 /* X || !X is always true. */
10630 /* (X && !Y) || (!X && Y) is X ^ Y */
10633 {
10650 }
10659 /* If the second arg is constant zero, drop it. */
10662 /* If the second arg is constant true, this is a logical inversion. */
10664 {
10667 }
10668 /* Identical arguments cancel to zero. */
10672 /* !X ^ X is always true. */
10677 /* X ^ !X is always true. */
10693 /* bool_var != 1 becomes !bool_var. */
10700 /* bool_var == 0 becomes !bool_var. */
10707 /* !exp != 0 becomes !exp */
10712 /* If this is an EQ or NE comparison with zero and ARG0 is
10713 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10714 two operations, but the latter can be done in one less insn
10715 on machines that have only two-operand insns or on which a
10716 constant cannot be the first operand. */
10719 {
10724 {
10731 arg1);
10732 }
10735 {
10742 arg1);
10743 }
10744 }
10746 /* If this is an NE or EQ comparison of zero against the result of a
10747 signed MOD operation whose second operand is a power of 2, make
10748 the MOD operation unsigned since it is simpler and equivalent. */
10756 {
10766 }
10768 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10769 C1 is a valid shift constant, and C2 is a power of two, i.e.
10770 a single bit. */
10774 == INTEGER_CST
10777 {
10782 /* Check for a valid shift count. */
10784 {
10788 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10789 can be rewritten as (X & (C2 << C1)) != 0. */
10791 {
10796 }
10797 /* Otherwise, for signed (arithmetic) shifts,
10798 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10799 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10803 /* Otherwise, of unsigned (logical) shifts,
10804 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10805 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10806 else
10810 arg000);
10811 }
10812 }
10814 /* If this is a comparison of a field, we may be able to simplify it. */
10817 /* Handle the constant case even without -O
10818 to make sure the warnings are given. */
10820 {
10824 }
10826 /* Optimize comparisons of strlen vs zero to a compare of the
10827 first character of the string vs zero. To wit,
10828 strlen(ptr) == 0 => *ptr == 0
10829 strlen(ptr) != 0 => *ptr != 0
10830 Other cases should reduce to one of these two (or a constant)
10831 due to the return value of strlen being unsigned. */
10834 {
10842 {
10847 }
10848 }
10850 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10851 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10855 {
10860 {
10862 {
10865 }
10868 }
10869 }
10871 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10872 (X & C) == 0 when C is a single bit. */
10877 {
10884 arg1));
10885 }
10887 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10888 constant C is a power of two, i.e. a single bit. */
10895 {
10899 }
10901 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10902 when is C is a power of two, i.e. a single bit. */
10909 {
10915 }
10919 {
10922 }
10924 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10927 {
10935 {
10941 }
10943 {
10949 }
10951 {
10957 }
10959 {
10965 }
10966 }
10970 {
10977 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10978 operand_equal_p guarantees no side-effects so we don't need
10979 to use omit_one_operand on Z. */
10983 arg10));
10987 arg11));
10991 arg10));
10995 arg11));
10997 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11000 {
11006 }
11007 }
11009 /* Attempt to simplify equality/inequality comparisons of complex
11010 values. Only lower the comparison if the result is known or
11011 can be simplified to a single scalar comparison. */
11016 {
11021 {
11024 }
11025 else
11026 {
11029 }
11032 {
11035 }
11036 else
11037 {
11040 }
11044 {
11046 {
11051 }
11052 else
11053 {
11058 }
11059 }
11063 {
11065 {
11070 }
11071 else
11072 {
11077 }
11078 }
11079 }
11091 /* Transform comparisons of the form X +- C CMP X. */
11096 {
11101 /* (X - c) > X becomes false. */
11107 /* Likewise (X + c) < X becomes false. */
11113 /* Convert (X - c) <= X to true. */
11120 /* Convert (X + c) >= X to true. */
11126 }
11128 /* If we are comparing an ABS_EXPR with a constant, we can
11129 convert all the cases into explicit comparisons, but they may
11130 well not be faster than doing the ABS and one comparison.
11131 But ABS (X) <= C is a range comparison, which becomes a subtraction
11132 and a comparison, and is probably faster. */
11146 /* Convert ABS_EXPR<x> >= 0 to true. */
11153 {
11156 "when simplifying comparison of "
11158 WARN_STRICT_OVERFLOW_CONDITIONAL);
11161 arg0);
11162 }
11164 /* Convert ABS_EXPR<x> < 0 to false. */
11169 {
11172 "when simplifying comparison of "
11174 WARN_STRICT_OVERFLOW_CONDITIONAL);
11177 arg0);
11178 }
11180 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11181 and similarly for >= into !=. */
11191 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11192 otherwise Y might be >= # of bits in X's type and thus e.g.
11193 (unsigned char) (1 << Y) for Y 15 might be 0.
11194 If the cast is widening, then 1 << Y should have unsigned type,
11195 otherwise if Y is number of bits in the signed shift type minus 1,
11196 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11197 31 might be 0xffffffff80000000. */
11208 {
11214 }
11226 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11227 {
11239 }
11244 /* When pedantic, a compound expression can be neither an lvalue
11245 nor an integer constant expression. */
11248 /* Don't let (0, 0) be null pointer constant. */
11254 /* An ASSERT_EXPR should never be passed to fold_binary. */
11260 }
11262 /* Used by contains_label_[p1]. */
11264 struct contains_label_data
11265 {
11268 };
11270 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11271 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11272 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11274 static tree
11276 {
11279 {
11290 {
11298 }
11307 }
11308 }
11310 /* Return whether the sub-tree ST contains a label which is accessible from
11311 outside the sub-tree. */
11313 static bool
11315 {
11319 }
11321 /* Fold a ternary expression of code CODE and type TYPE with operands
11322 OP0, OP1, and OP2. Return the folded expression if folding is
11323 successful. Otherwise, return NULL_TREE. */
11325 tree
11328 {
11329 tree tem;
11336 /* If this is a commutative operation, and OP0 is a constant, move it
11337 to OP1 to reduce the number of tests below. */
11346 /* Strip any conversions that don't change the mode. This is safe
11347 for every expression, except for a comparison expression because
11348 its signedness is derived from its operands. So, in the latter
11349 case, only strip conversions that don't change the signedness.
11351 Note that this is done as an internal manipulation within the
11352 constant folder, in order to find the simplest representation of
11353 the arguments so that their form can be studied. In any cases,
11354 the appropriate type conversions should be put back in the tree
11355 that will get out of the constant folder. */
11357 {
11360 }
11363 {
11366 }
11369 {
11372 }
11375 {
11379 {
11385 }
11390 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11391 so all simple results must be passed through pedantic_non_lvalue. */
11393 {
11396 /* Only optimize constant conditions when the selected branch
11397 has the same type as the COND_EXPR. This avoids optimizing
11398 away "c ? x : throw", where the throw has a void type.
11399 Avoid throwing away that operand which contains label. */
11406 }
11408 {
11415 {
11418 {
11426 }
11431 }
11432 }
11434 /* If we have A op B ? A : C, we may be able to convert this to a
11435 simpler expression, depending on the operation and the values
11436 of B and C. Signed zeros prevent all of these transformations,
11437 for reasons given above each one.
11439 Also try swapping the arguments and inverting the conditional. */
11443 {
11447 }
11452 {
11456 {
11460 }
11461 }
11463 /* If the second operand is simpler than the third, swap them
11464 since that produces better jump optimization results. */
11467 {
11469 /* See if this can be inverted. If it can't, possibly because
11470 it was a floating-point inequality comparison, don't do
11471 anything. */
11475 }
11477 /* Convert A ? 1 : 0 to simply A. */
11482 /* If we try to convert OP0 to our type, the
11483 call to fold will try to move the conversion inside
11484 a COND, which will recurse. In that case, the COND_EXPR
11485 is probably the best choice, so leave it alone. */
11489 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11490 over COND_EXPR in cases such as floating point comparisons. */
11499 arg0)));
11501 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11506 {
11507 /* sign_bit_p looks through both zero and sign extensions,
11508 but for this optimization only sign extensions are
11509 usable. */
11512 {
11515 {
11518 }
11520 }
11521 /* sign_bit_p only checks ARG1 bits within A's precision.
11522 If <sign bit of A> has wider type than A, bits outside
11523 of A's precision in <sign bit of A> need to be checked.
11524 If they are all 0, this optimization needs to be done
11525 in unsigned A's type, if they are all 1 in signed A's type,
11526 otherwise this can't be done. */
11532 {
11534 tree tem_type;
11547 {
11550 }
11552 {
11555 }
11556 else
11558 }
11561 return
11567 arg1)));
11568 }
11570 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11571 already handled above. */
11576 {
11586 op1);
11587 }
11589 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11590 is probably obsolete because the first operand should be a
11591 truth value (that's why we have the two cases above), but let's
11592 leave it in until we can confirm this for all front-ends. */
11604 /* Disable the transformations below for vectors, since
11605 fold_binary_op_with_conditional_arg may undo them immediately,
11606 yielding an infinite loop. */
11610 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11619 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11624 {
11626 /* Only perform transformation if ARG0 is easily inverted. */
11630 ? BIT_IOR_EXPR
11633 op1);
11634 }
11636 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11641 {
11643 /* Only perform transformation if ARG0 is easily inverted. */
11649 op2);
11650 }
11652 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11664 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11665 of fold_ternary on them. */
11675 {
11686 {
11691 {
11693 {
11698 }
11704 }
11705 }
11706 }
11708 /* On constants we can use native encode/interpret to constant
11709 fold (nearly) all BIT_FIELD_REFs. */
11715 {
11718 /* Limit us to a reasonable amount of work. To relax the
11719 other limitations we need bit-shifting of the buffer
11720 and rounding up the size. */
11724 {
11726 unsigned HOST_WIDE_INT len
11731 {
11736 }
11737 }
11738 }
11744 {
11745 /* Build a vector of integers from the tree mask. */
11746 vec_perm_builder builder;
11750 /* Create a vec_perm_indices for the integer vector. */
11755 /* Check for cases that fold to OP0 or OP1 in their original
11756 element order. */
11763 {
11767 {
11770 }
11771 }
11777 {
11781 }
11785 /* Generate a canonical form of the selector. */
11787 {
11788 /* Some targets are deficient and fail to expand a single
11789 argument permutation while still allowing an equivalent
11790 2-argument version. */
11794 else
11795 {
11799 else
11800 /* Not directly supported with either encoding,
11801 so use the preferred form. */
11803 }
11805 }
11809 }
11813 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11816 {
11822 wide_int tem2
11826 }
11831 {
11833 unsigned HOST_WIDE_INT elsize
11836 {
11842 {
11848 }
11849 }
11850 }
11856 }
11858 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11859 of an array (or vector). */
11861 tree
11863 {
11868 {
11871 {
11872 /* Static constructors for variably sized objects makes no sense. */
11876 }
11877 }
11888 offset_int max_index;
11893 {
11894 /* Array constructor might explicitly set index, or specify a range,
11895 or leave index NULL meaning that it is next index after previous
11896 one. */
11898 {
11901 else
11902 {
11906 }
11907 }
11908 else
11909 {
11915 }
11917 /* Do we have match? */
11921 }
11923 }
11925 /* Perform constant folding and related simplification of EXPR.
11926 The related simplifications include x*1 => x, x*0 => 0, etc.,
11927 and application of the associative law.
11928 NOP_EXPR conversions may be removed freely (as long as we
11929 are careful not to change the type of the overall expression).
11930 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11931 but we can constant-fold them if they have constant operands. */
11933 #ifdef ENABLE_FOLD_CHECKING
11934 # define fold(x) fold_1 (x)
11936 static
11937 #endif
11938 tree
11940 {
11944 tree tem;
11947 /* Return right away if a constant. */
11951 /* CALL_EXPR-like objects with variable numbers of operands are
11952 treated specially. */
11954 {
11956 {
11959 }
11961 }
11964 {
11969 {
11987 }
11988 }
11991 {
11993 {
12000 {
12005 }
12008 }
12010 /* Return a VECTOR_CST if possible. */
12012 {
12018 tree val;
12024 }
12032 }
12034 #ifdef ENABLE_FOLD_CHECKING
12035 #undef fold
12042 /* When --enable-checking=fold, compute a digest of expr before
12043 and after actual fold call to see if fold did not accidentally
12044 change original expr. */
12046 tree
12048 {
12049 tree ret;
12069 }
12071 void
12073 {
12084 }
12086 static void
12088 {
12090 }
12092 static void
12095 {
12101 recursive_label:
12111 {
12112 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12117 }
12125 {
12126 /* Allow these fields to be modified. */
12127 tree tmp;
12136 {
12139 }
12140 }
12151 {
12154 {
12170 }
12174 {
12187 }
12204 {
12210 }
12213 {
12215 {
12218 }
12220 }
12231 {
12234 }
12244 }
12245 }
12247 /* Helper function for outputting the checksum of a tree T. When
12248 debugging with gdb, you can "define mynext" to be "next" followed
12249 by "call debug_fold_checksum (op0)", then just trace down till the
12250 outputs differ. */
12252 DEBUG_FUNCTION void
12254 {
12269 }
12271 #endif
12273 /* Fold a unary tree expression with code CODE of type TYPE with an
12274 operand OP0. LOC is the location of the resulting expression.
12275 Return a folded expression if successful. Otherwise, return a tree
12276 expression with code CODE of type TYPE with an operand OP0. */
12278 tree
12281 {
12282 tree tem;
12283 #ifdef ENABLE_FOLD_CHECKING
12292 #endif
12298 #ifdef ENABLE_FOLD_CHECKING
12305 #endif
12307 }
12309 /* Fold a binary tree expression with code CODE of type TYPE with
12310 operands OP0 and OP1. LOC is the location of the resulting
12311 expression. Return a folded expression if successful. Otherwise,
12312 return a tree expression with code CODE of type TYPE with operands
12313 OP0 and OP1. */
12315 tree
12318 MEM_STAT_DECL)
12319 {
12320 tree tem;
12321 #ifdef ENABLE_FOLD_CHECKING
12338 #endif
12344 #ifdef ENABLE_FOLD_CHECKING
12359 #endif
12361 }
12363 /* Fold a ternary tree expression with code CODE of type TYPE with
12364 operands OP0, OP1, and OP2. Return a folded expression if
12365 successful. Otherwise, return a tree expression with code CODE of
12366 type TYPE with operands OP0, OP1, and OP2. */
12368 tree
12371 {
12372 tree tem;
12373 #ifdef ENABLE_FOLD_CHECKING
12397 #endif
12404 #ifdef ENABLE_FOLD_CHECKING
12427 #endif
12429 }
12431 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12432 arguments in ARGARRAY, and a null static chain.
12433 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12434 of type TYPE from the given operands as constructed by build_call_array. */
12436 tree
12439 {
12440 tree tem;
12441 #ifdef ENABLE_FOLD_CHECKING
12460 #endif
12466 #ifdef ENABLE_FOLD_CHECKING
12482 #endif
12484 }
12486 /* Perform constant folding and related simplification of initializer
12487 expression EXPR. These behave identically to "fold_buildN" but ignore
12488 potential run-time traps and exceptions that fold must preserve. */
12490 #define START_FOLD_INIT \
12491 int saved_signaling_nans = flag_signaling_nans;\
12492 int saved_trapping_math = flag_trapping_math;\
12493 int saved_rounding_math = flag_rounding_math;\
12494 int saved_trapv = flag_trapv;\
12495 int saved_folding_initializer = folding_initializer;\
12496 flag_signaling_nans = 0;\
12497 flag_trapping_math = 0;\
12498 flag_rounding_math = 0;\
12499 flag_trapv = 0;\
12500 folding_initializer = 1;
12502 #define END_FOLD_INIT \
12503 flag_signaling_nans = saved_signaling_nans;\
12504 flag_trapping_math = saved_trapping_math;\
12505 flag_rounding_math = saved_rounding_math;\
12506 flag_trapv = saved_trapv;\
12507 folding_initializer = saved_folding_initializer;
12509 tree
12512 {
12513 tree result;
12514 START_FOLD_INIT;
12518 END_FOLD_INIT;
12520 }
12522 tree
12525 {
12526 tree result;
12527 START_FOLD_INIT;
12531 END_FOLD_INIT;
12533 }
12535 tree
12538 {
12539 tree result;
12540 START_FOLD_INIT;
12544 END_FOLD_INIT;
12546 }
12548 #undef START_FOLD_INIT
12549 #undef END_FOLD_INIT
12551 /* Determine if first argument is a multiple of second argument. Return 0 if
12552 it is not, or we cannot easily determined it to be.
12554 An example of the sort of thing we care about (at this point; this routine
12555 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12556 fold cases do now) is discovering that
12558 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12560 is a multiple of
12562 SAVE_EXPR (J * 8)
12564 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12566 This code also handles discovering that
12568 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12570 is a multiple of 8 so we don't have to worry about dealing with a
12571 possible remainder.
12573 Note that we *look* inside a SAVE_EXPR only to determine how it was
12574 calculated; it is not safe for fold to do much of anything else with the
12575 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12576 at run time. For example, the latter example above *cannot* be implemented
12577 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12578 evaluation time of the original SAVE_EXPR is not necessarily the same at
12579 the time the new expression is evaluated. The only optimization of this
12580 sort that would be valid is changing
12582 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12584 divided by 8 to
12586 SAVE_EXPR (I) * SAVE_EXPR (J)
12588 (where the same SAVE_EXPR (J) is used in the original and the
12589 transformed version). */
12591 int
12593 {
12604 {
12606 /* Bitwise and provides a power of two multiple. If the mask is
12607 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12615 {
12621 {
12624 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12626 {
12630 {
12633 }
12634 }
12636 }
12637 }
12642 /* It is impossible to prove if op0 - op1 is multiple of bottom
12643 precisely, so be conservative here checking if both op0 and op1
12644 are multiple of bottom. Note we check the second operand first
12645 since it's usually simpler. */
12650 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12651 as op0 - 3 if the expression has unsigned type. For example,
12652 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12662 {
12664 /* const_binop may not detect overflow correctly,
12665 so check for it explicitly here. */
12673 }
12677 /* Can't handle conversions from non-integral or wider integral type. */
12683 /* fall through */
12700 SIGNED);
12706 {
12709 /* Check for special cases to see if top is defined as multiple
12710 of bottom:
12712 top = (X & ~(bottom - 1) ; bottom is power of 2
12714 or
12716 Y = X % bottom
12717 top = X - Y. */
12736 }
12738 /* fall through */
12746 }
12747 }
12749 #define tree_expr_nonnegative_warnv_p(X, Y) \
12752 #define RECURSE(X) \
12753 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12755 /* Return true if CODE or TYPE is known to be non-negative. */
12757 static bool
12759 {
12762 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12763 have a signed:1 type (where the value is -1 and 0). */
12766 }
12768 /* Return true if (CODE OP0) is known to be non-negative. If the return
12769 value is based on the assumption that signed overflow is undefined,
12770 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12771 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12773 bool
12776 {
12781 {
12783 /* We can't return 1 if flag_wrapv is set because
12784 ABS_EXPR<INT_MIN> = INT_MIN. */
12788 {
12791 }
12799 CASE_CONVERT:
12800 {
12805 {
12809 {
12813 }
12814 }
12816 {
12822 }
12823 }
12828 }
12830 /* We don't know sign of `t', so be conservative and return false. */
12832 }
12834 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12835 value is based on the assumption that signed overflow is undefined,
12836 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12837 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12839 bool
12843 {
12848 {
12854 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12855 both unsigned and at least 2 bits shorter than the result. */
12859 {
12864 {
12868 }
12869 }
12874 {
12875 /* x * x is always non-negative for floating point x
12876 or without overflow. */
12879 {
12884 }
12885 }
12887 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12888 both unsigned and their total bits is shorter than the result. */
12892 {
12911 {
12921 }
12922 }
12949 }
12951 /* We don't know sign of `t', so be conservative and return false. */
12953 }
12955 /* Return true if T is known to be non-negative. If the return
12956 value is based on the assumption that signed overflow is undefined,
12957 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12958 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12960 bool
12962 {
12967 {
12981 /* Limit the depth of recursion to avoid quadratic behavior.
12982 This is expected to catch almost all occurrences in practice.
12983 If this code misses important cases that unbounded recursion
12984 would not, passes that need this information could be revised
12985 to provide it through dataflow propagation. */
12993 }
12994 }
12996 /* Return true if T is known to be non-negative. If the return
12997 value is based on the assumption that signed overflow is undefined,
12998 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12999 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13001 bool
13004 {
13006 {
13007 CASE_CFN_ACOS:
13008 CASE_CFN_ACOSH:
13009 CASE_CFN_CABS:
13010 CASE_CFN_COSH:
13011 CASE_CFN_ERFC:
13012 CASE_CFN_EXP:
13013 CASE_CFN_EXP10:
13014 CASE_CFN_EXP2:
13015 CASE_CFN_FABS:
13016 CASE_CFN_FDIM:
13017 CASE_CFN_HYPOT:
13018 CASE_CFN_POW10:
13019 CASE_CFN_FFS:
13020 CASE_CFN_PARITY:
13021 CASE_CFN_POPCOUNT:
13022 CASE_CFN_CLZ:
13023 CASE_CFN_CLRSB:
13026 /* Always true. */
13029 CASE_CFN_SQRT:
13030 CASE_CFN_SQRT_FN:
13031 /* sqrt(-0.0) is -0.0. */
13036 CASE_CFN_ASINH:
13037 CASE_CFN_ATAN:
13038 CASE_CFN_ATANH:
13039 CASE_CFN_CBRT:
13040 CASE_CFN_CEIL:
13041 CASE_CFN_CEIL_FN:
13042 CASE_CFN_ERF:
13043 CASE_CFN_EXPM1:
13044 CASE_CFN_FLOOR:
13045 CASE_CFN_FLOOR_FN:
13046 CASE_CFN_FMOD:
13047 CASE_CFN_FREXP:
13048 CASE_CFN_ICEIL:
13049 CASE_CFN_IFLOOR:
13050 CASE_CFN_IRINT:
13051 CASE_CFN_IROUND:
13052 CASE_CFN_LCEIL:
13053 CASE_CFN_LDEXP:
13054 CASE_CFN_LFLOOR:
13055 CASE_CFN_LLCEIL:
13056 CASE_CFN_LLFLOOR:
13057 CASE_CFN_LLRINT:
13058 CASE_CFN_LLROUND:
13059 CASE_CFN_LRINT:
13060 CASE_CFN_LROUND:
13061 CASE_CFN_MODF:
13062 CASE_CFN_NEARBYINT:
13063 CASE_CFN_NEARBYINT_FN:
13064 CASE_CFN_RINT:
13065 CASE_CFN_RINT_FN:
13066 CASE_CFN_ROUND:
13067 CASE_CFN_ROUND_FN:
13068 CASE_CFN_SCALB:
13069 CASE_CFN_SCALBLN:
13070 CASE_CFN_SCALBN:
13071 CASE_CFN_SIGNBIT:
13072 CASE_CFN_SIGNIFICAND:
13073 CASE_CFN_SINH:
13074 CASE_CFN_TANH:
13075 CASE_CFN_TRUNC:
13076 CASE_CFN_TRUNC_FN:
13077 /* True if the 1st argument is nonnegative. */
13080 CASE_CFN_FMAX:
13081 CASE_CFN_FMAX_FN:
13082 /* True if the 1st OR 2nd arguments are nonnegative. */
13085 CASE_CFN_FMIN:
13086 CASE_CFN_FMIN_FN:
13087 /* True if the 1st AND 2nd arguments are nonnegative. */
13090 CASE_CFN_COPYSIGN:
13091 CASE_CFN_COPYSIGN_FN:
13092 /* True if the 2nd argument is nonnegative. */
13095 CASE_CFN_POWI:
13096 /* True if the 1st argument is nonnegative or the second
13097 argument is an even integer. */
13103 CASE_CFN_POW:
13104 /* True if the 1st argument is nonnegative or the second
13105 argument is an even integer valued real. */
13107 {
13108 REAL_VALUE_TYPE c;
13109 HOST_WIDE_INT n;
13114 {
13115 REAL_VALUE_TYPE cint;
13119 }
13120 }
13125 }
13127 }
13129 /* Return true if T is known to be non-negative. If the return
13130 value is based on the assumption that signed overflow is undefined,
13131 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13132 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13134 static bool
13136 {
13142 {
13144 {
13148 /* If the initializer is non-void, then it's a normal expression
13149 that will be assigned to the slot. */
13153 /* Otherwise, the initializer sets the slot in some way. One common
13154 way is an assignment statement at the end of the initializer. */
13156 {
13164 else
13166 }
13172 }
13175 {
13181 arg0,
13182 arg1,
13184 }
13197 }
13198 }
13200 #undef RECURSE
13201 #undef tree_expr_nonnegative_warnv_p
13203 /* Return true if T is known to be non-negative. If the return
13204 value is based on the assumption that signed overflow is undefined,
13205 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13206 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13208 bool
13210 {
13217 {
13239 }
13242 {
13268 }
13269 }
13271 /* Return true if `t' is known to be non-negative. Handle warnings
13272 about undefined signed overflow. */
13274 bool
13276 {
13283 "determining that expression is always "
13285 WARN_STRICT_OVERFLOW_MISC);
13287 }
13290 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13291 For floating point we further ensure that T is not denormal.
13292 Similar logic is present in nonzero_address in rtlanal.h.
13294 If the return value is based on the assumption that signed overflow
13295 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13296 change *STRICT_OVERFLOW_P. */
13298 bool
13301 {
13303 {
13306 strict_overflow_p);
13309 {
13315 strict_overflow_p));
13316 }
13321 strict_overflow_p);
13325 }
13328 }
13330 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13331 For floating point we further ensure that T is not denormal.
13332 Similar logic is present in nonzero_address in rtlanal.h.
13334 If the return value is based on the assumption that signed overflow
13335 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13336 change *STRICT_OVERFLOW_P. */
13338 bool
13340 tree type,
13341 tree op0,
13343 {
13346 {
13350 {
13351 /* With the presence of negative values it is hard
13352 to say something. */
13359 /* One of operands must be positive and the other non-negative. */
13360 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13361 overflows, on a twos-complement machine the sum of two
13362 nonnegative numbers can never be zero. */
13364 strict_overflow_p)
13366 strict_overflow_p));
13367 }
13372 {
13374 strict_overflow_p)
13376 strict_overflow_p))
13377 {
13380 }
13381 }
13390 {
13393 }
13400 {
13404 /* When both operands are nonzero, then MAX must be too. */
13406 strict_overflow_p))
13409 /* MAX where operand 0 is positive is positive. */
13411 strict_overflow_p);
13412 }
13413 /* MAX where operand 1 is positive is positive. */
13418 {
13422 }
13427 strict_overflow_p)
13429 strict_overflow_p));
13433 }
13436 }
13438 /* Return true when T is an address and is known to be nonzero.
13439 For floating point we further ensure that T is not denormal.
13440 Similar logic is present in nonzero_address in rtlanal.h.
13442 If the return value is based on the assumption that signed overflow
13443 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13444 change *STRICT_OVERFLOW_P. */
13446 bool
13448 {
13451 {
13456 {
13468 /* For objects in symbol table check if we know they are non-zero.
13469 Don't do anything for variables and functions before symtab is built;
13470 it is quite possible that they will be declared weak later. */
13475 /* Constants are never weak. */
13480 }
13488 {
13492 }
13502 }
13504 }
13506 #define integer_valued_real_p(X) \
13509 #define RECURSE(X) \
13510 ((integer_valued_real_p) (X, depth + 1))
13512 /* Return true if the floating point result of (CODE OP0) has an
13513 integer value. We also allow +Inf, -Inf and NaN to be considered
13514 integer values. Return false for signaling NaN.
13516 DEPTH is the current nesting depth of the query. */
13518 bool
13520 {
13522 {
13529 CASE_CONVERT:
13530 {
13537 }
13541 }
13543 }
13545 /* Return true if the floating point result of (CODE OP0 OP1) has an
13546 integer value. We also allow +Inf, -Inf and NaN to be considered
13547 integer values. Return false for signaling NaN.
13549 DEPTH is the current nesting depth of the query. */
13551 bool
13553 {
13555 {
13565 }
13567 }
13569 /* Return true if the floating point result of calling FNDECL with arguments
13570 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13571 considered integer values. Return false for signaling NaN. If FNDECL
13572 takes fewer than 2 arguments, the remaining ARGn are null.
13574 DEPTH is the current nesting depth of the query. */
13576 bool
13578 {
13580 {
13581 CASE_CFN_CEIL:
13582 CASE_CFN_CEIL_FN:
13583 CASE_CFN_FLOOR:
13584 CASE_CFN_FLOOR_FN:
13585 CASE_CFN_NEARBYINT:
13586 CASE_CFN_NEARBYINT_FN:
13587 CASE_CFN_RINT:
13588 CASE_CFN_RINT_FN:
13589 CASE_CFN_ROUND:
13590 CASE_CFN_ROUND_FN:
13591 CASE_CFN_TRUNC:
13592 CASE_CFN_TRUNC_FN:
13595 CASE_CFN_FMIN:
13596 CASE_CFN_FMIN_FN:
13597 CASE_CFN_FMAX:
13598 CASE_CFN_FMAX_FN:
13603 }
13605 }
13607 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13608 has an integer value. We also allow +Inf, -Inf and NaN to be
13609 considered integer values. Return false for signaling NaN.
13611 DEPTH is the current nesting depth of the query. */
13613 bool
13615 {
13617 {
13625 /* Limit the depth of recursion to avoid quadratic behavior.
13626 This is expected to catch almost all occurrences in practice.
13627 If this code misses important cases that unbounded recursion
13628 would not, passes that need this information could be revised
13629 to provide it through dataflow propagation. */
13633 depth));
13637 }
13639 }
13641 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13642 has an integer value. We also allow +Inf, -Inf and NaN to be
13643 considered integer values. Return false for signaling NaN.
13645 DEPTH is the current nesting depth of the query. */
13647 static bool
13649 {
13651 {
13662 }
13664 }
13666 #undef RECURSE
13667 #undef integer_valued_real_p
13669 /* Return true if the floating point expression T has an integer value.
13670 We also allow +Inf, -Inf and NaN to be considered integer values.
13671 Return false for signaling NaN.
13673 DEPTH is the current nesting depth of the query. */
13675 bool
13677 {
13683 {
13699 }
13702 {
13708 {
13717 }
13721 }
13722 }
13724 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13725 attempt to fold the expression to a constant without modifying TYPE,
13726 OP0 or OP1.
13728 If the expression could be simplified to a constant, then return
13729 the constant. If the expression would not be simplified to a
13730 constant, then return NULL_TREE. */
13732 tree
13734 {
13737 }
13739 /* Given the components of a unary expression CODE, TYPE and OP0,
13740 attempt to fold the expression to a constant without modifying
13741 TYPE or OP0.
13743 If the expression could be simplified to a constant, then return
13744 the constant. If the expression would not be simplified to a
13745 constant, then return NULL_TREE. */
13747 tree
13749 {
13752 }
13754 /* If EXP represents referencing an element in a constant string
13755 (either via pointer arithmetic or array indexing), return the
13756 tree representing the value accessed, otherwise return NULL. */
13758 tree
13760 {
13764 {
13766 tree index;
13767 tree string;
13772 else
13773 {
13777 /* Optimize the special-case of a zero lower bound.
13779 We convert the low_bound to sizetype to avoid some problems
13780 with constant folding. (E.g. suppose the lower bound is 1,
13781 and its mode is QI. Without the conversion,l (ARRAY
13782 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13783 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13789 }
13791 scalar_int_mode char_mode;
13803 }
13805 }
13807 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13808 an integer constant, real, or fixed-point constant.
13810 TYPE is the type of the result. */
13812 static tree
13814 {
13818 {
13824 {
13825 FIXED_VALUE_TYPE f;
13830 /* Propagate overflow flags. */
13834 }
13838 {
13845 }
13848 }
13851 }
13853 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13854 an integer constant or real constant.
13856 TYPE is the type of the result. */
13858 tree
13860 {
13864 {
13866 {
13867 /* If the value is unsigned or non-negative, then the absolute value
13868 is the same as the ordinary value. */
13872 /* If the value is negative, then the absolute value is
13873 its negation. */
13874 else
13875 {
13880 }
13881 }
13887 else
13893 }
13896 }
13898 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13899 constant. TYPE is the type of the result. */
13901 static tree
13903 {
13907 }
13909 /* Given CODE, a relational operator, the target type, TYPE and two
13910 constant operands OP0 and OP1, return the result of the
13911 relational operation. If the result is not a compile time
13912 constant, then return NULL_TREE. */
13914 static tree
13916 {
13919 /* From here on, the only cases we handle are when the result is
13920 known to be a constant. */
13923 {
13927 /* Handle the cases where either operand is a NaN. */
13929 {
13931 {
13959 }
13962 }
13965 }
13968 {
13972 }
13974 /* Handle equality/inequality of complex constants. */
13976 {
13987 else
13989 }
13992 {
13994 {
13995 /* Have vector comparison with scalar boolean result. */
14003 {
14011 }
14013 }
14014 tree_vector_builder elts;
14019 {
14032 }
14035 }
14037 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14039 To compute GT, swap the arguments and do LT.
14040 To compute GE, do LT and invert the result.
14041 To compute LE, swap the arguments, do LT and invert the result.
14042 To compute NE, do EQ and invert the result.
14044 Therefore, the code below must handle only EQ and LT. */
14047 {
14050 }
14052 /* Note that it is safe to invert for real values here because we
14053 have already handled the one case that it matters. */
14057 {
14060 }
14062 /* Compute a result for LT or EQ if args permit;
14063 Otherwise return T. */
14065 {
14068 else
14070 }
14071 else
14077 }
14079 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14080 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14081 itself. */
14083 tree
14085 {
14086 /* If the expression does not have side effects then we don't have to wrap
14087 it with a cleanup point expression. */
14091 /* If the expression is a return, check to see if the expression inside the
14092 return has no side effects or the right hand side of the modify expression
14093 inside the return. If either don't have side effects set we don't need to
14094 wrap the expression in a cleanup point expression. Note we don't check the
14095 left hand side of the modify because it should always be a return decl. */
14097 {
14104 }
14107 }
14109 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14110 of an indirection through OP0, or NULL_TREE if no simplification is
14111 possible. */
14113 tree
14115 {
14117 tree subtype;
14118 poly_uint64 const_op01;
14127 {
14131 /* *&CONST_DECL -> to the value of the const decl. */
14134 /* *&p => p; make sure to handle *&"str"[cst] here. */
14136 {
14140 else
14142 }
14143 /* *(foo *)&fooarray => fooarray[0] */
14146 && (!in_gimple_form
14148 {
14158 }
14159 /* *(foo *)&complexfoo => __real__ complexfoo */
14163 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14166 {
14170 index);
14171 }
14172 }
14176 {
14182 {
14183 tree op00type;
14187 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14190 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14191 but we want to treat offsets with MSB set as negative.
14192 For the code below negative offsets are invalid and
14193 TYPE_SIZE of the element is something unsigned, so
14194 check whether op01 fits into poly_int64, which implies
14195 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14196 then just use poly_uint64 because we want to treat the
14197 value as unsigned. */
14199 {
14201 poly_uint64 max_offset
14205 {
14210 }
14211 }
14212 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14215 {
14217 const_op01))
14219 }
14220 /* ((foo *)&fooarray)[1] => fooarray[1] */
14223 {
14232 {
14237 }
14238 }
14239 }
14240 }
14242 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14245 && (!in_gimple_form
14247 {
14248 tree type_domain;
14258 NULL_TREE);
14259 }
14262 }
14264 /* Builds an expression for an indirection through T, simplifying some
14265 cases. */
14267 tree
14269 {
14277 }
14279 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14281 tree
14283 {
14288 else
14290 }
14292 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14293 whose result is ignored. The type of the returned tree need not be
14294 the same as the original expression. */
14296 tree
14298 {
14304 {
14315 else
14321 {
14337 }
14342 }
14343 }
14345 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14347 tree
14349 {
14355 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14356 have to do anything. Only do this when we are not given a const,
14357 because in that case, this check is more expensive than just
14358 doing it. */
14360 {
14365 }
14367 /* If divisor is a power of two, simplify this to bit manipulation. */
14369 {
14371 {
14385 }
14386 else
14387 {
14388 tree t;
14394 }
14395 }
14396 else
14397 {
14402 }
14405 }
14407 /* Likewise, but round down. */
14409 tree
14411 {
14418 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14419 have to do anything. Only do this when we are not given a const,
14420 because in that case, this check is more expensive than just
14421 doing it. */
14423 {
14428 }
14430 /* If divisor is a power of two, simplify this to bit manipulation. */
14432 {
14433 tree t;
14437 }
14438 else
14439 {
14444 }
14447 }
14449 /* Returns the pointer to the base of the object addressed by EXP and
14450 extracts the information about the offset of the access, storing it
14451 to PBITPOS and POFFSET. */
14453 static tree
14456 {
14457 tree core;
14458 machine_mode mode;
14460 poly_int64 bitsize;
14464 {
14469 }
14471 {
14477 {
14478 poly_offset_int tem
14484 }
14485 }
14486 else
14487 {
14491 }
14494 }
14496 /* Returns true if addresses of E1 and E2 differ by a constant, false
14497 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14499 bool
14501 {
14516 {
14526 }
14528 {
14529 /* If only one of the offsets is non-constant, the difference cannot
14530 be a constant. */
14532 }
14533 else
14538 }
14540 /* Return OFF converted to a pointer offset type suitable as offset for
14541 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14542 tree
14544 {
14546 }
14548 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14549 tree
14551 {
14554 }
14556 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14557 tree
14559 {
14562 }
14564 /* Return a char pointer for a C string if it is a string constant
14565 or sum of string constant and integer constant. We only support
14566 string constants properly terminated with '\0' character.
14567 If STRLEN is a valid pointer, length (including terminating character)
14568 of returned string is stored to the argument. */
14572 {
14573 tree offset_node;
14584 {
14587 else
14589 }
14594 /* Support only properly null-terminated strings. */
14603 }
14605 /* Given a tree T, compute which bits in T may be nonzero. */
14607 wide_int
14609 {
14611 {
14629 CASE_CONVERT:
14635 {
14640 }
14644 {
14652 }
14656 {
14664 }
14668 }
14671 }
14673 #if CHECKING_P
14677 /* Helper functions for writing tests of folding trees. */
14679 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14681 static void
14683 tree constant)
14684 {
14686 }
14688 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14689 wrapping WRAPPED_EXPR. */
14691 static void
14693 tree wrapped_expr)
14694 {
14699 }
14701 /* Verify that various arithmetic binary operations are folded
14702 correctly. */
14704 static void
14706 {
14712 /* Addition. */
14713 /* 1 <-- (0 + 1) */
14715 one);
14717 one);
14719 /* (nonlvalue)x <-- (x + 0) */
14721 x);
14723 /* Subtraction. */
14724 /* 0 <-- (x - x) */
14726 zero);
14728 x);
14730 /* Multiplication. */
14731 /* 0 <-- (x * 0) */
14733 zero);
14735 /* (nonlvalue)x <-- (x * 1) */
14737 x);
14738 }
14740 /* Verify that various binary operations on vectors are folded
14741 correctly. */
14743 static void
14745 {
14751 /* Verify equality tests that return a scalar boolean result. */
14757 }
14759 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14761 static void
14763 {
14766 /* This will be 1 if VEC_MODE isn't a vector mode. */
14773 }
14775 /* Run all of the selftests within this file. */
14777 void
14779 {
14783 }