| blob | 2039d4dd2f9e3deab1a8cad4d6639cf36347d541 |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2017 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. */
86 /* Nonzero if we are folding constants inside an initializer; zero
87 otherwise. */
90 /* The following constants represent a bit based encoding of GCC's
91 comparison operators. This encoding simplifies transformations
92 on relational comparison operators, such as AND and OR. */
110 };
143 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
144 Otherwise, return LOC. */
146 static location_t
148 {
151 }
153 /* Similar to protected_set_expr_location, but never modify x in place,
154 if location can and needs to be set, unshare it. */
158 {
164 {
167 }
169 }
170 \f
171 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
172 division and returns the quotient. Otherwise returns
173 NULL_TREE. */
175 tree
177 {
178 widest_int quo;
185 }
186 \f
187 /* This is nonzero if we should defer warnings about undefined
188 overflow. This facility exists because these warnings are a
189 special case. The code to estimate loop iterations does not want
190 to issue any warnings, since it works with expressions which do not
191 occur in user code. Various bits of cleanup code call fold(), but
192 only use the result if it has certain characteristics (e.g., is a
193 constant); that code only wants to issue a warning if the result is
194 used. */
198 /* If a warning about undefined overflow is deferred, this is the
199 warning. Note that this may cause us to turn two warnings into
200 one, but that is fine since it is sufficient to only give one
201 warning per expression. */
205 /* If a warning about undefined overflow is deferred, this is the
206 level at which the warning should be emitted. */
210 /* Start deferring overflow warnings. We could use a stack here to
211 permit nested calls, but at present it is not necessary. */
213 void
215 {
217 }
219 /* Stop deferring overflow warnings. If there is a pending warning,
220 and ISSUE is true, then issue the warning if appropriate. STMT is
221 the statement with which the warning should be associated (used for
222 location information); STMT may be NULL. CODE is the level of the
223 warning--a warn_strict_overflow_code value. This function will use
224 the smaller of CODE and the deferred code when deciding whether to
225 issue the warning. CODE may be zero to mean to always use the
226 deferred code. */
228 void
230 {
232 location_t locus;
237 {
243 }
254 /* Use the smallest code level when deciding to issue the
255 warning. */
264 else
267 }
269 /* Stop deferring overflow warnings, ignoring any deferred
270 warnings. */
272 void
274 {
276 }
278 /* Whether we are deferring overflow warnings. */
280 bool
282 {
284 }
286 /* This is called when we fold something based on the fact that signed
287 overflow is undefined. */
289 void
291 {
293 {
296 {
299 }
300 }
303 }
304 \f
305 /* Return true if the built-in mathematical function specified by CODE
306 is odd, i.e. -f(x) == f(-x). */
308 bool
310 {
312 {
313 CASE_CFN_ASIN:
314 CASE_CFN_ASINH:
315 CASE_CFN_ATAN:
316 CASE_CFN_ATANH:
317 CASE_CFN_CASIN:
318 CASE_CFN_CASINH:
319 CASE_CFN_CATAN:
320 CASE_CFN_CATANH:
321 CASE_CFN_CBRT:
322 CASE_CFN_CPROJ:
323 CASE_CFN_CSIN:
324 CASE_CFN_CSINH:
325 CASE_CFN_CTAN:
326 CASE_CFN_CTANH:
327 CASE_CFN_ERF:
328 CASE_CFN_LLROUND:
329 CASE_CFN_LROUND:
330 CASE_CFN_ROUND:
331 CASE_CFN_SIN:
332 CASE_CFN_SINH:
333 CASE_CFN_TAN:
334 CASE_CFN_TANH:
335 CASE_CFN_TRUNC:
338 CASE_CFN_LLRINT:
339 CASE_CFN_LRINT:
340 CASE_CFN_NEARBYINT:
341 CASE_CFN_RINT:
346 }
348 }
350 /* Check whether we may negate an integer constant T without causing
351 overflow. */
353 bool
355 {
356 tree type;
365 }
367 /* Determine whether an expression T can be cheaply negated using
368 the function negate_expr without introducing undefined overflow. */
370 static bool
372 {
373 tree type;
382 {
387 /* Check that -CST will not overflow type. */
400 /* We want to canonicalize to positive real constants. Pretend
401 that only negative ones can be easily negated. */
409 {
413 /* Steps don't prevent negation. */
420 }
435 /* -(A + B) -> (-B) - A. */
438 /* -(A + B) -> (-A) - B. */
442 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
451 /* INT_MIN/n * n doesn't overflow while negating one operand it does
452 if n is a (negative) power of two. */
463 /* Fall through. */
478 /* In general we can't negate B in A / B, because if A is INT_MIN and
479 B is 1, we may turn this into INT_MIN / -1 which is undefined
480 and actually traps on some architectures. */
489 /* Negate -((double)float) as (double)(-float). */
491 {
495 }
499 /* Negate -f(x) as f(-x). */
505 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
507 {
511 }
516 }
518 }
520 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
521 simplification is possible.
522 If negate_expr_p would return true for T, NULL_TREE will never be
523 returned. */
525 static tree
527 {
529 tree tem;
532 {
533 /* Convert - (~A) to A + 1. */
557 {
562 }
566 {
567 tree_vector_builder elts;
571 {
576 }
579 }
602 {
603 /* -(A + B) -> (-B) - A. */
605 {
609 }
611 /* -(A + B) -> (-A) - B. */
613 {
617 }
618 }
622 /* - (A - B) -> B - A */
633 /* Fall through. */
637 {
646 }
658 /* In general we can't negate B in A / B, because if A is INT_MIN and
659 B is 1, we may turn this into INT_MIN / -1 which is undefined
660 and actually traps on some architectures. */
672 /* Convert -((double)float) into (double)(-float). */
674 {
678 }
682 /* Negate -f(x) as f(-x). */
685 {
691 }
695 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
697 {
700 {
707 }
708 }
713 }
716 }
718 /* A wrapper for fold_negate_expr_1. */
720 static tree
722 {
729 }
731 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
732 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
733 return NULL_TREE. */
735 static tree
737 {
739 location_t loc;
752 }
753 \f
754 /* Split a tree IN into a constant, literal and variable parts that could be
755 combined with CODE to make IN. "constant" means an expression with
756 TREE_CONSTANT but that isn't an actual constant. CODE must be a
757 commutative arithmetic operation. Store the constant part into *CONP,
758 the literal in *LITP and return the variable part. If a part isn't
759 present, set it to null. If the tree does not decompose in this way,
760 return the entire tree as the variable part and the other parts as null.
762 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
763 case, we negate an operand that was subtracted. Except if it is a
764 literal for which we use *MINUS_LITP instead.
766 If NEGATE_P is true, we are negating all of IN, again except a literal
767 for which we use *MINUS_LITP instead. If a variable part is of pointer
768 type, it is negated after converting to TYPE. This prevents us from
769 generating illegal MINUS pointer expression. LOC is the location of
770 the converted variable part.
772 If IN is itself a literal or constant, return it as appropriate.
774 Note that we do not guarantee that any of the three values will be the
775 same type as IN, but they will have the same signedness and mode. */
777 static tree
781 {
789 /* Strip any conversions that don't change the machine mode or signedness. */
798 /* We can associate addition and subtraction together (even
799 though the C standard doesn't say so) for integers because
800 the value is not affected. For reals, the value might be
801 affected, so we can't. */
807 {
813 /* First see if either of the operands is a literal, then a constant. */
826 /* If we haven't dealt with either operand, this is not a case we can
827 decompose. Otherwise, VAR is either of the ones remaining, if any. */
832 else
835 /* Now do any needed negations. */
842 }
847 {
848 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
849 when IN is constant. */
852 }
853 else
857 {
870 }
880 }
882 /* Re-associate trees split by the above function. T1 and T2 are
883 either expressions to associate or null. Return the new
884 expression, if any. LOC is the location of the new expression. If
885 we build an operation, do it in TYPE and with CODE. */
887 static tree
889 {
891 {
894 }
898 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
899 try to fold this since we will have infinite recursion. But do
900 deal with any NEGATE_EXPRs. */
904 {
906 {
919 }
921 {
924 }
928 }
932 }
933 \f
934 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
935 for use in int_const_binop, size_binop and size_diffop. */
937 static bool
939 {
946 {
955 }
960 }
962 /* Subroutine of int_const_binop_1 that handles two INTEGER_CSTs. */
964 static tree
967 {
968 wide_int res;
969 tree t;
978 {
994 {
998 else
1000 }
1003 /* It's unclear from the C standard whether shifts can overflow.
1004 The following code ignores overflow; perhaps a C standard
1005 interpretation ruling is needed. */
1007 else
1014 {
1018 else
1020 }
1024 else
1103 }
1111 }
1113 /* Combine two integer constants PARG1 and PARG2 under operation CODE
1114 to produce a new constant. Return NULL_TREE if we don't know how
1115 to evaluate CODE at compile-time. */
1117 static tree
1120 {
1127 {
1128 poly_wide_int res;
1133 {
1151 else
1158 else
1171 }
1176 }
1179 }
1181 tree
1183 {
1185 }
1187 /* Return true if binary operation OP distributes over addition in operand
1188 OPNO, with the other operand being held constant. OPNO counts from 1. */
1190 static bool
1192 {
1194 {
1205 }
1206 }
1208 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1209 constant. We assume ARG1 and ARG2 have the same data type, or at least
1210 are the same kind of constant and the same machine mode. Return zero if
1211 combining the constants is not allowed in the current operating mode. */
1213 static tree
1215 {
1216 /* Sanity check for the recursive cases. */
1224 {
1230 }
1233 {
1234 machine_mode mode;
1235 REAL_VALUE_TYPE d1;
1236 REAL_VALUE_TYPE d2;
1237 REAL_VALUE_TYPE value;
1238 REAL_VALUE_TYPE result;
1242 /* The following codes are handled by real_arithmetic. */
1244 {
1255 }
1263 /* Don't perform operation if we honor signaling NaNs and
1264 either operand is a signaling NaN. */
1270 /* Don't perform operation if it would raise a division
1271 by zero exception. */
1277 /* If either operand is a NaN, just return it. Otherwise, set up
1278 for floating-point trap; we return an overflow. */
1280 {
1281 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1282 is off. */
1286 }
1288 {
1289 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1290 is off. */
1294 }
1299 /* Don't constant fold this floating point operation if
1300 the result has overflowed and flag_trapping_math. */
1308 /* Don't constant fold this floating point operation if the
1309 result may dependent upon the run-time rounding mode and
1310 flag_rounding_math is set, or if GCC's software emulation
1311 is unable to accurately represent the result. */
1321 }
1324 {
1325 FIXED_VALUE_TYPE f1;
1326 FIXED_VALUE_TYPE f2;
1327 FIXED_VALUE_TYPE result;
1332 /* The following codes are handled by fixed_arithmetic. */
1334 {
1346 {
1353 }
1358 }
1365 /* Propagate overflow flags. */
1369 }
1372 {
1381 {
1392 mpc_mul);
1406 mpc_div);
1407 /* Fallthru. */
1413 {
1414 /* Keep this algorithm in sync with
1415 tree-complex.c:expand_complex_div_straight().
1417 Expand complex division to scalars, straightforward algorithm.
1418 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1419 t = br*br + bi*bi
1420 */
1421 tree magsquared
1425 tree t1
1429 tree t2
1436 }
1437 else
1438 {
1439 /* Keep this algorithm in sync with
1440 tree-complex.c:expand_complex_div_wide().
1442 Expand complex division to scalars, modified algorithm to minimize
1443 overflow with wide input ranges. */
1449 {
1450 /* In the TRUE branch, we compute
1451 ratio = br/bi;
1452 div = (br * ratio) + bi;
1453 tr = (ar * ratio) + ai;
1454 ti = (ai * ratio) - ar;
1455 tr = tr / div;
1456 ti = ti / div; */
1467 }
1468 else
1469 {
1470 /* In the FALSE branch, we compute
1471 ratio = d/c;
1472 divisor = (d * ratio) + c;
1473 tr = (b * ratio) + a;
1474 ti = b - (a * ratio);
1475 tr = tr / div;
1476 ti = ti / div; */
1488 }
1489 }
1494 }
1498 }
1504 {
1509 /* We can operate directly on the encoding if:
1511 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1512 implies
1513 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1515 Addition and subtraction are the supported operators
1516 for which this is true. */
1519 /* We can operate directly on stepped encodings if:
1521 a3 - a2 == a2 - a1
1522 implies:
1523 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1525 which is true if (x -> x op c) distributes over addition. */
1527 else
1528 /* Similarly in reverse. */
1530 tree_vector_builder elts;
1535 {
1541 /* It is possible that const_binop cannot handle the given
1542 code and return NULL_TREE */
1546 }
1549 }
1551 /* Shifts allow a scalar offset for a vector. */
1554 {
1557 tree_vector_builder elts;
1562 {
1567 /* It is possible that const_binop cannot handle the given
1568 code and return NULL_TREE. */
1572 }
1575 }
1577 }
1579 /* Overload that adds a TYPE parameter to be able to dispatch
1580 to fold_relational_const. */
1582 tree
1584 {
1588 /* ??? Until we make the const_binop worker take the type of the
1589 result as argument put those cases that need it here. */
1591 {
1608 {
1613 }
1618 {
1632 {
1642 }
1645 }
1651 {
1673 {
1686 }
1689 }
1692 }
1697 /* Make sure type and arg0 have the same saturating flag. */
1702 }
1704 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1705 Return zero if computing the constants is not possible. */
1707 tree
1709 {
1710 /* Don't perform the operation, other than NEGATE and ABS, if
1711 flag_signaling_nans is on and the operand is a signaling NaN. */
1720 {
1721 CASE_CONVERT:
1728 /* If the source address is 0, and the source address space
1729 cannot have a valid object at 0, fold to dest type null. */
1740 {
1741 /* Can't call fold_negate_const directly here as that doesn't
1742 handle all cases and we might not be able to negate some
1743 constants. */
1748 }
1757 {
1761 }
1769 /* Perform BIT_NOT_EXPR on each element individually. */
1771 {
1772 tree elem;
1774 /* This can cope with stepped encodings because ~x == -1 - x. */
1775 tree_vector_builder elements;
1779 {
1785 }
1788 }
1810 {
1828 else
1833 {
1839 }
1842 }
1851 }
1854 }
1856 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1857 indicates which particular sizetype to create. */
1859 tree
1861 {
1863 }
1864 \f
1865 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1866 is a tree code. The type of the result is taken from the operands.
1867 Both must be equivalent integer types, ala int_binop_types_match_p.
1868 If the operands are constant, so is the result. */
1870 tree
1872 {
1881 /* Handle the special case of two poly_int constants faster. */
1883 {
1884 /* And some specific cases even faster than that. */
1886 {
1891 }
1893 {
1896 }
1898 {
1901 }
1903 /* Handle general case of two integer constants. For sizetype
1904 constant calculations we always want to know about overflow,
1905 even in the unsigned case. */
1909 }
1912 }
1914 /* Given two values, either both of sizetype or both of bitsizetype,
1915 compute the difference between the two values. Return the value
1916 in signed type corresponding to the type of the operands. */
1918 tree
1920 {
1922 tree ctype;
1927 /* If the type is already signed, just do the simple thing. */
1935 else
1938 /* If either operand is not a constant, do the conversions to the signed
1939 type and subtract. The hardware will do the right thing with any
1940 overflow in the subtraction. */
1946 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1947 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1948 overflow) and negate (which can't either). Special-case a result
1949 of zero while we're here. */
1955 else
1959 MINUS_EXPR,
1961 }
1962 \f
1963 /* A subroutine of fold_convert_const handling conversions of an
1964 INTEGER_CST to another integer type. */
1966 static tree
1968 {
1969 /* Given an integer constant, make new constant with new type,
1970 appropriately sign-extended or truncated. Use widest_int
1971 so that any extension is done according ARG1's type. */
1975 }
1977 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1978 to an integer type. */
1980 static tree
1982 {
1984 tree t;
1986 /* The following code implements the floating point to integer
1987 conversion rules required by the Java Language Specification,
1988 that IEEE NaNs are mapped to zero and values that overflow
1989 the target precision saturate, i.e. values greater than
1990 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1991 are mapped to INT_MIN. These semantics are allowed by the
1992 C and C++ standards that simply state that the behavior of
1993 FP-to-integer conversion is unspecified upon overflow. */
1995 wide_int val;
1996 REAL_VALUE_TYPE r;
2000 {
2007 }
2009 /* If R is NaN, return zero and show we have an overflow. */
2011 {
2014 }
2016 /* See if R is less than the lower bound or greater than the
2017 upper bound. */
2020 {
2024 {
2027 }
2028 }
2031 {
2034 {
2037 {
2040 }
2041 }
2042 }
2049 }
2051 /* A subroutine of fold_convert_const handling conversions of a
2052 FIXED_CST to an integer type. */
2054 static tree
2056 {
2057 tree t;
2059 scalar_mode mode;
2061 /* Right shift FIXED_CST to temp by fbit. */
2065 {
2067 HOST_BITS_PER_DOUBLE_INT,
2070 /* Left shift temp to temp_trunc by fbit. */
2072 HOST_BITS_PER_DOUBLE_INT,
2074 }
2075 else
2076 {
2079 }
2081 /* If FIXED_CST is negative, we need to round the value toward 0.
2082 By checking if the fractional bits are not zero to add 1 to temp. */
2088 /* Given a fixed-point constant, make new constant with new type,
2089 appropriately sign-extended or truncated. */
2097 }
2099 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2100 to another floating point type. */
2102 static tree
2104 {
2105 REAL_VALUE_TYPE value;
2106 tree t;
2108 /* Don't perform the operation if flag_signaling_nans is on
2109 and the operand is a signaling NaN. */
2117 /* If converting an infinity or NAN to a representation that doesn't
2118 have one, set the overflow bit so that we can produce some kind of
2119 error message at the appropriate point if necessary. It's not the
2120 most user-friendly message, but it's better than nothing. */
2127 /* Regular overflow, conversion produced an infinity in a mode that
2128 can't represent them. */
2133 else
2136 }
2138 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2139 to a floating point type. */
2141 static tree
2143 {
2144 REAL_VALUE_TYPE value;
2145 tree t;
2153 }
2155 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2156 to another fixed-point type. */
2158 static tree
2160 {
2161 FIXED_VALUE_TYPE value;
2162 tree t;
2169 /* Propagate overflow flags. */
2173 }
2175 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2176 to a fixed-point type. */
2178 static tree
2180 {
2181 FIXED_VALUE_TYPE value;
2182 tree t;
2184 double_int di;
2191 else
2199 /* Propagate overflow flags. */
2203 }
2205 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2206 to a fixed-point type. */
2208 static tree
2210 {
2211 FIXED_VALUE_TYPE value;
2212 tree t;
2220 /* Propagate overflow flags. */
2224 }
2226 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2227 type TYPE. If no simplification can be done return NULL_TREE. */
2229 static tree
2231 {
2236 /* We can't widen types, since the runtime value could overflow the
2237 original type before being extended to the new type. */
2248 {
2255 }
2257 {
2264 }
2266 {
2273 }
2275 {
2278 {
2281 /* We can't handle steps directly when extending, since the
2282 values need to wrap at the original precision first. */
2283 bool step_ok_p
2287 tree_vector_builder v;
2292 {
2298 }
2300 }
2301 }
2303 }
2305 /* Construct a vector of zero elements of vector type TYPE. */
2307 static tree
2309 {
2310 tree t;
2314 }
2316 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2318 bool
2320 {
2335 {
2350 }
2351 }
2353 /* Convert expression ARG to type TYPE. Used by the middle-end for
2354 simple conversions in preference to calling the front-end's convert. */
2356 tree
2358 {
2360 tree tem;
2371 {
2374 /* Handle conversions between pointers to different address spaces. */
2379 /* fall through */
2384 {
2388 }
2402 {
2406 }
2408 {
2412 }
2414 {
2418 }
2421 {
2439 }
2444 {
2448 }
2451 {
2465 }
2469 {
2478 integer_zero_node));
2480 {
2484 {
2490 }
2498 }
2502 }
2520 }
2521 fold_convert_exit:
2524 }
2525 \f
2526 /* Return false if expr can be assumed not to be an lvalue, true
2527 otherwise. */
2529 static bool
2531 {
2532 /* We only need to wrap lvalue tree codes. */
2534 {
2565 /* Assume the worst for front-end tree codes. */
2569 }
2572 }
2574 /* Return an expr equal to X but certainly not valid as an lvalue. */
2576 tree
2578 {
2579 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2580 us. */
2587 }
2589 /* When pedantic, return an expr equal to X but certainly not valid as a
2590 pedantic lvalue. Otherwise, return X. */
2592 static tree
2594 {
2596 }
2597 \f
2598 /* Given a tree comparison code, return the code that is the logical inverse.
2599 It is generally not safe to do this for floating-point comparisons, except
2600 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2601 ERROR_MARK in this case. */
2603 enum tree_code
2605 {
2611 {
2642 }
2643 }
2645 /* Similar, but return the comparison that results if the operands are
2646 swapped. This is safe for floating-point. */
2648 enum tree_code
2650 {
2652 {
2678 }
2679 }
2682 /* Convert a comparison tree code from an enum tree_code representation
2683 into a compcode bit-based encoding. This function is the inverse of
2684 compcode_to_comparison. */
2686 static enum comparison_code
2688 {
2690 {
2721 }
2722 }
2724 /* Convert a compcode bit-based encoding of a comparison operator back
2725 to GCC's enum tree_code representation. This function is the
2726 inverse of comparison_to_compcode. */
2728 static enum tree_code
2730 {
2732 {
2763 }
2764 }
2766 /* Return a tree for the comparison which is the combination of
2767 doing the AND or OR (depending on CODE) of the two operations LCODE
2768 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2769 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2770 if this makes the transformation invalid. */
2772 tree
2777 {
2784 {
2795 }
2798 {
2799 /* Eliminate unordered comparisons, as well as LTGT and ORD
2800 which are not used unless the mode has NaNs. */
2806 }
2808 {
2809 /* Check that the original operation and the optimized ones will trap
2810 under the same condition. */
2821 /* In a short-circuited boolean expression the LHS might be
2822 such that the RHS, if evaluated, will never trap. For
2823 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2824 if neither x nor y is NaN. (This is a mixed blessing: for
2825 example, the expression above will never trap, hence
2826 optimizing it to x < y would be invalid). */
2831 /* If the comparison was short-circuited, and only the RHS
2832 trapped, we may now generate a spurious trap. */
2837 /* If we changed the conditions that cause a trap, we lose. */
2840 }
2846 else
2847 {
2852 }
2853 }
2854 \f
2855 /* Return nonzero if two operands (typically of the same tree node)
2856 are necessarily equal. FLAGS modifies behavior as follows:
2858 If OEP_ONLY_CONST is set, only return nonzero for constants.
2859 This function tests whether the operands are indistinguishable;
2860 it does not test whether they are equal using C's == operation.
2861 The distinction is important for IEEE floating point, because
2862 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2863 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2865 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2866 even though it may hold multiple values during a function.
2867 This is because a GCC tree node guarantees that nothing else is
2868 executed between the evaluation of its "operands" (which may often
2869 be evaluated in arbitrary order). Hence if the operands themselves
2870 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2871 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2872 unset means assuming isochronic (or instantaneous) tree equivalence.
2873 Unless comparing arbitrary expression trees, such as from different
2874 statements, this flag can usually be left unset.
2876 If OEP_PURE_SAME is set, then pure functions with identical arguments
2877 are considered the same. It is used when the caller has other ways
2878 to ensure that global memory is unchanged in between.
2880 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2881 not values of expressions.
2883 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2884 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2886 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2887 any operand with side effect. This is unnecesarily conservative in the
2888 case we know that arg0 and arg1 are in disjoint code paths (such as in
2889 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2890 addresses with TREE_CONSTANT flag set so we know that &var == &var
2891 even if var is volatile. */
2893 int
2895 {
2896 /* When checking, verify at the outermost operand_equal_p call that
2897 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2898 hash value. */
2900 {
2902 {
2904 {
2911 }
2913 }
2914 else
2916 }
2918 /* If either is ERROR_MARK, they aren't equal. */
2924 /* Similar, if either does not have a type (like a released SSA name),
2925 they aren't equal. */
2929 /* We cannot consider pointers to different address space equal. */
2936 /* Check equality of integer constants before bailing out due to
2937 precision differences. */
2939 {
2940 /* Address of INTEGER_CST is not defined; check that we did not forget
2941 to drop the OEP_ADDRESS_OF flags. */
2944 }
2947 {
2948 /* If both types don't have the same signedness, then we can't consider
2949 them equal. We must check this before the STRIP_NOPS calls
2950 because they may change the signedness of the arguments. As pointers
2951 strictly don't have a signedness, require either two pointers or
2952 two non-pointers as well. */
2958 /* If both types don't have the same precision, then it is not safe
2959 to strip NOPs. */
2966 }
2967 #if 0
2968 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2969 sanity check once the issue is solved. */
2970 else
2971 /* Addresses of conversions and SSA_NAMEs (and many other things)
2972 are not defined. Check that we did not forget to drop the
2973 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2976 #endif
2978 /* In case both args are comparisons but with different comparison
2979 code, try to swap the comparison operands of one arg to produce
2980 a match and compare that variant. */
2984 {
2992 }
2995 {
2996 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
2998 ;
3000 {
3001 /* If we are interested in comparing addresses ignore
3002 MEM_REF wrappings of the base that can appear just for
3003 TBAA reasons. */
3017 }
3018 else
3020 }
3022 /* When not checking adddresses, this is needed for conversions and for
3023 COMPONENT_REF. Might as well play it safe and always test this. */
3030 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3031 We don't care about side effects in that case because the SAVE_EXPR
3032 takes care of that for us. In all other cases, two expressions are
3033 equal if they have no side effects. If we have two identical
3034 expressions with side effects that should be treated the same due
3035 to the only side effects being identical SAVE_EXPR's, that will
3036 be detected in the recursive calls below.
3037 If we are taking an invariant address of two identical objects
3038 they are necessarily equal as well. */
3045 /* Next handle constant cases, those for which we can return 1 even
3046 if ONLY_CONST is set. */
3049 {
3063 {
3064 /* If we do not distinguish between signed and unsigned zero,
3065 consider them equal. */
3068 }
3072 {
3087 }
3091 flags)
3093 flags));
3104 flags | OEP_ADDRESS_OF
3107 /* In GIMPLE empty constructors are allowed in initializers of
3108 aggregates. */
3112 }
3117 /* Define macros to test an operand from arg0 and arg1 for equality and a
3118 variant that allows null and views null as being different from any
3119 non-null value. In the latter case, if either is null, the both
3120 must be; otherwise, do the normal comparison. */
3121 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3122 TREE_OPERAND (arg1, N), flags)
3124 #define OP_SAME_WITH_NULL(N) \
3125 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3126 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3129 {
3131 /* Two conversions are equal only if signedness and modes match. */
3133 {
3134 CASE_CONVERT:
3142 }
3152 /* For commutative ops, allow the other order. */
3160 /* If either of the pointer (or reference) expressions we are
3161 dereferencing contain a side effect, these cannot be equal,
3162 but their addresses can be. */
3169 {
3179 /* Require the same offset. */
3185 /* Fallthru. */
3193 {
3194 /* Require equal access sizes */
3200 flags)))
3202 /* Verify that access happens in similar types. */
3205 /* Verify that accesses are TBAA compatible. */
3214 /* Verify that alignment is compatible. */
3218 }
3221 /* TARGET_MEM_REF require equal extra operands. */
3232 /* Compare the array index by value if it is constant first as we
3233 may have different types but same value here. */
3239 /* Compare low bound and element size as with OEP_ADDRESS_OF
3240 we have to account for the offset of the ref. */
3245 array_ref_low_bound
3249 array_ref_element_size
3251 flags))));
3254 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3255 may be NULL when we're called to compare MEM_EXPRs. */
3270 }
3274 {
3276 /* Be sure we pass right ADDRESS_OF flag. */
3294 /* The multiplcation operands are commutative. */
3295 /* FALLTHRU */
3303 /* Otherwise take into account this is a commutative operation. */
3316 /* BIT_INSERT_EXPR has an implict operand as the type precision
3317 of op1. Need to check to make sure they are the same. */
3323 /* FALLTHRU */
3348 }
3352 {
3356 /* If not both CALL_EXPRs are either internal or normal function
3357 functions, then they are not equal. */
3360 {
3361 /* If the CALL_EXPRs call different internal functions, then they
3362 are not equal. */
3365 }
3366 else
3367 {
3368 /* If the CALL_EXPRs call different functions, then they are not
3369 equal. */
3371 flags))
3373 }
3375 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3376 {
3380 else
3384 }
3386 /* Now see if all the arguments are the same. */
3387 {
3398 /* If we get here and both argument lists are exhausted
3399 then the CALL_EXPRs are equal. */
3401 }
3404 }
3407 /* Consider __builtin_sqrt equal to sqrt. */
3415 {
3416 /* In GIMPLE constructors are used only to build vectors from
3417 elements. Individual elements in the constructor must be
3418 indexed in increasing order and form an initial sequence.
3420 We make no effort to compare constructors in generic.
3421 (see sem_variable::equals in ipa-icf which can do so for
3422 constants). */
3427 /* Be sure that vectors constructed have the same representation.
3428 We only tested element precision and modes to match.
3429 Vectors may be BLKmode and thus also check that the number of
3430 parts match. */
3443 {
3448 /* In GIMPLE the indexes can be either NULL or matching i.
3449 Double check this so we won't get false
3450 positives for GENERIC. */
3458 }
3460 }
3463 {
3464 /* Compare the STATEMENT_LISTs. */
3470 {
3471 /* The lists don't have the same number of statements. */
3477 OEP_LEXICOGRAPHIC))
3479 }
3480 }
3485 {
3492 }
3496 }
3498 #undef OP_SAME
3499 #undef OP_SAME_WITH_NULL
3500 }
3501 \f
3502 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3503 with a different signedness or a narrower precision. */
3505 static bool
3507 {
3515 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3516 and see if the inner values are the same. This removes any
3517 signedness comparison, which doesn't matter here. */
3525 /* Discard a single widening conversion from ARG1 and see if the inner
3526 value is the same as ARG0. */
3535 }
3536 \f
3537 /* See if ARG is an expression that is either a comparison or is performing
3538 arithmetic on comparisons. The comparisons must only be comparing
3539 two different values, which will be stored in *CVAL1 and *CVAL2; if
3540 they are nonzero it means that some operands have already been found.
3541 No variables may be used anywhere else in the expression except in the
3542 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3543 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3545 If this is true, return 1. Otherwise, return zero. */
3547 static int
3549 {
3553 /* We can handle some of the tcc_expression cases here. */
3563 {
3564 /* If we've already found a CVAL1 or CVAL2, this expression is
3565 two complex to handle. */
3571 }
3574 {
3597 /* First see if we can handle the first operand, then the second. For
3598 the second operand, we know *CVAL1 can't be zero. It must be that
3599 one side of the comparison is each of the values; test for the
3600 case where this isn't true by failing if the two operands
3601 are the same. */
3610 ;
3614 ;
3615 else
3619 ;
3623 ;
3624 else
3631 }
3632 }
3633 \f
3634 /* ARG is a tree that is known to contain just arithmetic operations and
3635 comparisons. Evaluate the operations in the tree substituting NEW0 for
3636 any occurrence of OLD0 as an operand of a comparison and likewise for
3637 NEW1 and OLD1. */
3639 static tree
3642 {
3647 /* We can handle some of the tcc_expression cases here. */
3655 {
3670 {
3689 }
3690 /* Fall through - ??? */
3693 {
3697 /* We need to check both for exact equality and tree equality. The
3698 former will be true if the operand has a side-effect. In that
3699 case, we know the operand occurred exactly once. */
3712 }
3716 }
3717 }
3718 \f
3719 /* Return a tree for the case when the result of an expression is RESULT
3720 converted to TYPE and OMITTED was previously an operand of the expression
3721 but is now not needed (e.g., we folded OMITTED * 0).
3723 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3724 the conversion of RESULT to TYPE. */
3726 tree
3728 {
3731 /* If the resulting operand is an empty statement, just return the omitted
3732 statement casted to void. */
3742 }
3744 /* Return a tree for the case when the result of an expression is RESULT
3745 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3746 of the expression but are now not needed.
3748 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3749 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3750 evaluated before OMITTED2. Otherwise, if neither has side effects,
3751 just do the conversion of RESULT to TYPE. */
3753 tree
3756 {
3765 }
3767 \f
3768 /* Return a simplified tree node for the truth-negation of ARG. This
3769 never alters ARG itself. We assume that ARG is an operation that
3770 returns a truth value (0 or 1).
3772 FIXME: one would think we would fold the result, but it causes
3773 problems with the dominator optimizer. */
3775 static tree
3777 {
3782 /* If this is a comparison, we can simply invert it, except for
3783 floating-point non-equality comparisons, in which case we just
3784 enclose a TRUTH_NOT_EXPR around what we have. */
3787 {
3790 && flag_trapping_math
3804 }
3807 {
3826 /* Here we can invert either operand. We invert the first operand
3827 unless the second operand is a TRUTH_NOT_EXPR in which case our
3828 result is the XOR of the first operand with the inside of the
3829 negation of the second operand. */
3834 else
3857 {
3864 /* A COND_EXPR may have a throw as one operand, which
3865 then has void type. Just leave void operands
3866 as they are. */
3872 }
3884 CASE_CONVERT:
3888 /* fall through */
3910 }
3911 }
3913 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3914 assume that ARG is an operation that returns a truth value (0 or 1
3915 for scalars, 0 or -1 for vectors). Return the folded expression if
3916 folding is successful. Otherwise, return NULL_TREE. */
3918 static tree
3920 {
3923 ? BIT_NOT_EXPR
3926 }
3928 /* Return a simplified tree node for the truth-negation of ARG. This
3929 never alters ARG itself. We assume that ARG is an operation that
3930 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3932 tree
3934 {
3940 ? BIT_NOT_EXPR
3943 }
3944 \f
3945 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3946 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3947 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3948 is the original memory reference used to preserve the alias set of
3949 the access. */
3951 static tree
3955 {
3958 /* Attempt not to lose the access path if possible. */
3960 {
3962 machine_mode nmode;
3964 tree noffset;
3972 && !reversep
3973 && !nreversep
3975 {
3978 }
3979 }
3988 {
3995 }
4010 }
4012 /* Optimize a bit-field compare.
4014 There are two cases: First is a compare against a constant and the
4015 second is a comparison of two items where the fields are at the same
4016 bit position relative to the start of a chunk (byte, halfword, word)
4017 large enough to contain it. In these cases we can avoid the shift
4018 implicit in bitfield extractions.
4020 For constants, we emit a compare of the shifted constant with the
4021 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4022 compared. For two fields at the same position, we do the ANDs with the
4023 similar mask and compare the result of the ANDs.
4025 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4026 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4027 are the left and right operands of the comparison, respectively.
4029 If the optimization described above can be done, we return the resulting
4030 tree. Otherwise we return zero. */
4032 static tree
4035 {
4039 tree unsigned_type;
4042 scalar_int_mode nmode;
4047 tree mask;
4048 tree offset;
4050 /* Get all the information about the extractions being done. If the bit size
4051 is the same as the size of the underlying object, we aren't doing an
4052 extraction at all and so can do nothing. We also don't want to
4053 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4054 then will no longer be able to replace it. */
4069 else
4070 {
4071 /* If this is not a constant, we can only do something if bit positions,
4072 sizes, signedness and storage order are the same. */
4073 rinner
4086 }
4088 /* Honor the C++ memory model and mimic what RTL expansion does. */
4092 {
4096 }
4098 /* See if we can find a mode to refer to this field. We should be able to,
4099 but fail if we can't. */
4107 /* Set signed and unsigned types of the precision of this mode for the
4108 shifts below. */
4111 /* Compute the bit position and size for the new reference and our offset
4112 within it. If the new reference is the same size as the original, we
4113 won't optimize anything, so return zero. */
4123 /* Make the mask to be used against the extracted field. */
4130 {
4134 /* If not comparing with constant, just rework the comparison
4135 and return. */
4143 }
4145 /* Otherwise, we are handling the constant case. See if the constant is too
4146 big for the field. Warn and return a tree for 0 (false) if so. We do
4147 this not only for its own sake, but to avoid having to test for this
4148 error case below. If we didn't, we might generate wrong code.
4150 For unsigned fields, the constant shifted right by the field length should
4151 be all zero. For signed fields, the high-order bits should agree with
4152 the sign bit. */
4155 {
4157 {
4161 }
4162 }
4163 else
4164 {
4167 {
4171 }
4172 }
4177 /* Single-bit compares should always be against zero. */
4179 {
4182 }
4184 /* Make a new bitfield reference, shift the constant over the
4185 appropriate number of bits and mask it with the computed mask
4186 (in case this was a signed field). If we changed it, make a new one. */
4194 mask);
4199 }
4200 \f
4201 /* Subroutine for fold_truth_andor_1: decode a field reference.
4203 If EXP is a comparison reference, we return the innermost reference.
4205 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4206 set to the starting bit number.
4208 If the innermost field can be completely contained in a mode-sized
4209 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4211 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4212 otherwise it is not changed.
4214 *PUNSIGNEDP is set to the signedness of the field.
4216 *PREVERSEP is set to the storage order of the field.
4218 *PMASK is set to the mask used. This is either contained in a
4219 BIT_AND_EXPR or derived from the width of the field.
4221 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4223 Return 0 if this is not a component reference or is one that we can't
4224 do anything with. */
4226 static tree
4231 {
4236 tree unsigned_type;
4239 /* All the optimizations using this function assume integer fields.
4240 There are problems with FP fields since the type_for_size call
4241 below can fail for, e.g., XFmode. */
4245 /* We are interested in the bare arrangement of bits, so strip everything
4246 that doesn't affect the machine mode. However, record the type of the
4247 outermost expression if it may matter below. */
4254 {
4260 }
4271 /* Reject out-of-bound accesses (PR79731). */
4279 /* If the number of bits in the reference is the same as the bitsize of
4280 the outer type, then the outer type gives the signedness. Otherwise
4281 (in case of a small bitfield) the signedness is unchanged. */
4285 /* Compute the mask to access the bitfield. */
4294 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4302 }
4304 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4305 bit positions and MASK is SIGNED. */
4307 static int
4309 {
4313 /* If this function returns true when the type of the mask is
4314 UNSIGNED, then there will be errors. In particular see
4315 gcc.c-torture/execute/990326-1.c. There does not appear to be
4316 any documentation paper trail as to why this is so. But the pre
4317 wide-int worked with that restriction and it has been preserved
4318 here. */
4323 }
4325 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4326 represents the sign bit of EXP's type. If EXP represents a sign
4327 or zero extension, also test VAL against the unextended type.
4328 The return value is the (sub)expression whose sign bit is VAL,
4329 or NULL_TREE otherwise. */
4331 tree
4333 {
4335 tree t;
4337 /* Tree EXP must have an integral type. */
4342 /* Tree VAL must be an integer constant. */
4351 /* Handle extension from a narrower type. */
4357 }
4359 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4360 to be evaluated unconditionally. */
4362 static int
4364 {
4365 /* Strip any conversions that don't change the machine mode. */
4374 /* Don't regard global variables as simple. They may be
4375 allocated in ways unknown to the compiler (shared memory,
4376 #pragma weak, etc). */
4379 /* Weakrefs are not safe to be read, since they can be NULL.
4380 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4381 have DECL_WEAK flag set. */
4383 /* Loading a static variable is unduly expensive, but global
4384 registers aren't expensive. */
4386 }
4388 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4389 to be evaluated unconditionally.
4390 I addition to simple_operand_p, we assume that comparisons, conversions,
4391 and logic-not operations are simple, if their operands are simple, too. */
4393 static bool
4395 {
4415 }
4417 \f
4418 /* The following functions are subroutines to fold_range_test and allow it to
4419 try to change a logical combination of comparisons into a range test.
4421 For example, both
4422 X == 2 || X == 3 || X == 4 || X == 5
4423 and
4424 X >= 2 && X <= 5
4425 are converted to
4426 (unsigned) (X - 2) <= 3
4428 We describe each set of comparisons as being either inside or outside
4429 a range, using a variable named like IN_P, and then describe the
4430 range with a lower and upper bound. If one of the bounds is omitted,
4431 it represents either the highest or lowest value of the type.
4433 In the comments below, we represent a range by two numbers in brackets
4434 preceded by a "+" to designate being inside that range, or a "-" to
4435 designate being outside that range, so the condition can be inverted by
4436 flipping the prefix. An omitted bound is represented by a "-". For
4437 example, "- [-, 10]" means being outside the range starting at the lowest
4438 possible value and ending at 10, in other words, being greater than 10.
4439 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4440 always false.
4442 We set up things so that the missing bounds are handled in a consistent
4443 manner so neither a missing bound nor "true" and "false" need to be
4444 handled using a special case. */
4446 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4447 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4448 and UPPER1_P are nonzero if the respective argument is an upper bound
4449 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4450 must be specified for a comparison. ARG1 will be converted to ARG0's
4451 type if both are specified. */
4453 static tree
4456 {
4457 tree tem;
4461 /* If neither arg represents infinity, do the normal operation.
4462 Else, if not a comparison, return infinity. Else handle the special
4463 comparison rules. Note that most of the cases below won't occur, but
4464 are handled for consistency. */
4467 {
4472 }
4477 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4478 for neither. In real maths, we cannot assume open ended ranges are
4479 the same. But, this is computer arithmetic, where numbers are finite.
4480 We can therefore make the transformation of any unbounded range with
4481 the value Z, Z being greater than any representable number. This permits
4482 us to treat unbounded ranges as equal. */
4486 {
4507 }
4510 }
4511 \f
4512 /* Helper routine for make_range. Perform one step for it, return
4513 new expression if the loop should continue or NULL_TREE if it should
4514 stop. */
4516 tree
4520 {
4526 {
4528 /* We can only do something if the range is testing for zero. */
4537 /* We can only do something if the range is testing for zero
4538 and if the second operand is an integer constant. Note that
4539 saying something is "in" the range we make is done by
4540 complementing IN_P since it will set in the initial case of
4541 being not equal to zero; "out" is leaving it alone. */
4548 {
4569 }
4571 /* If this is an unsigned comparison, we also know that EXP is
4572 greater than or equal to zero. We base the range tests we make
4573 on that fact, so we record it here so we can parse existing
4574 range tests. We test arg0_type since often the return type
4575 of, e.g. EQ_EXPR, is boolean. */
4577 {
4581 NULL_TREE))
4586 /* If the high bound is missing, but we have a nonzero low
4587 bound, reverse the range so it goes from zero to the low bound
4588 minus 1. */
4590 {
4595 }
4596 }
4604 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4605 low and high are non-NULL, then normalize will DTRT. */
4608 {
4613 }
4615 /* (-x) IN [a,b] -> x in [-b, -a] */
4627 /* ~ X -> -X - 1 */
4636 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4637 move a constant to the other side. */
4642 /* If EXP is signed, any overflow in the computation is undefined,
4643 so we don't worry about it so long as our computations on
4644 the bounds don't overflow. For unsigned, overflow is defined
4645 and this is exactly the right thing. */
4657 normalize:
4658 /* Check for an unsigned range which has wrapped around the maximum
4659 value thus making n_high < n_low, and normalize it. */
4661 {
4667 /* If the range is of the form +/- [ x+1, x ], we won't
4668 be able to normalize it. But then, it represents the
4669 whole range or the empty set, so make it
4670 +/- [ -, - ]. */
4674 else
4676 }
4677 else
4685 CASE_CONVERT:
4703 /* If we're converting arg0 from an unsigned type, to exp,
4704 a signed type, we will be doing the comparison as unsigned.
4705 The tests above have already verified that LOW and HIGH
4706 are both positive.
4708 So we have to ensure that we will handle large unsigned
4709 values the same way that the current signed bounds treat
4710 negative values. */
4713 {
4714 tree high_positive;
4715 tree equiv_type;
4716 /* For fixed-point modes, we need to pass the saturating flag
4717 as the 2nd parameter. */
4719 equiv_type
4722 else
4723 equiv_type
4726 /* A range without an upper bound is, naturally, unbounded.
4727 Since convert would have cropped a very large value, use
4728 the max value for the destination type. */
4729 high_positive
4736 high_positive),
4739 /* If the low bound is specified, "and" the range with the
4740 range for which the original unsigned value will be
4741 positive. */
4743 {
4746 integer_zero_node),
4747 high_positive))
4751 }
4752 else
4753 {
4754 /* Otherwise, "or" the range with the range of the input
4755 that will be interpreted as negative. */
4758 integer_zero_node),
4759 high_positive))
4763 }
4764 }
4773 }
4774 }
4776 /* Given EXP, a logical expression, set the range it is testing into
4777 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4778 actually being tested. *PLOW and *PHIGH will be made of the same
4779 type as the returned expression. If EXP is not a comparison, we
4780 will most likely not be returning a useful value and range. Set
4781 *STRICT_OVERFLOW_P to true if the return value is only valid
4782 because signed overflow is undefined; otherwise, do not change
4783 *STRICT_OVERFLOW_P. */
4785 tree
4788 {
4796 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4797 and see if we can refine the range. Some of the cases below may not
4798 happen, but it doesn't seem worth worrying about this. We "continue"
4799 the outer loop when we've changed something; otherwise we "break"
4800 the switch, which will "break" the while. */
4806 {
4812 {
4820 }
4829 }
4831 /* If EXP is a constant, we can evaluate whether this is true or false. */
4833 {
4840 }
4844 }
4846 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4847 a bitwise check i.e. when
4848 LOW == 0xXX...X00...0
4849 HIGH == 0xXX...X11...1
4850 Return corresponding mask in MASK and stem in VALUE. */
4852 static bool
4855 {
4878 }
4879 \f
4880 /* Helper routine for build_range_check and match.pd. Return the type to
4881 perform the check or NULL if it shouldn't be optimized. */
4883 tree
4885 {
4886 /* First make sure that arithmetics in this type is valid, then make sure
4887 that it wraps around. */
4893 {
4896 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4897 for the type in question, as we rely on this here. */
4907 else
4909 }
4911 }
4913 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4914 type, TYPE, return an expression to test if EXP is in (or out of, depending
4915 on IN_P) the range. Return 0 if the test couldn't be created. */
4917 tree
4920 {
4923 /* Disable this optimization for function pointer expressions
4924 on targets that require function pointer canonicalization. */
4931 {
4937 }
4959 value);
4962 {
4964 {
4968 }
4970 }
4972 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4974 {
4978 {
4980 {
4983 etype
4985 else
4988 }
4991 }
4992 }
4994 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4995 This requires wrap-around arithmetics for the type of the expression. */
5015 }
5016 \f
5017 /* Return the predecessor of VAL in its type, handling the infinite case. */
5019 static tree
5021 {
5027 else
5030 }
5032 /* Return the successor of VAL in its type, handling the infinite case. */
5034 static tree
5036 {
5042 else
5045 }
5047 /* Given two ranges, see if we can merge them into one. Return 1 if we
5048 can, 0 if we can't. Set the output range into the specified parameters. */
5050 bool
5053 {
5057 tree tem;
5067 /* Make range 0 be the range that starts first, or ends last if they
5068 start at the same value. Swap them if it isn't. */
5071 || (lowequal
5074 {
5078 }
5080 /* Now flag two cases, whether the ranges are disjoint or whether the
5081 second range is totally subsumed in the first. Note that the tests
5082 below are simplified by the ones above. */
5088 /* We now have four cases, depending on whether we are including or
5089 excluding the two ranges. */
5091 {
5092 /* If they don't overlap, the result is false. If the second range
5093 is a subset it is the result. Otherwise, the range is from the start
5094 of the second to the end of the first. */
5099 else
5101 }
5104 {
5105 /* If they don't overlap, the result is the first range. If they are
5106 equal, the result is false. If the second range is a subset of the
5107 first, and the ranges begin at the same place, we go from just after
5108 the end of the second range to the end of the first. If the second
5109 range is not a subset of the first, or if it is a subset and both
5110 ranges end at the same place, the range starts at the start of the
5111 first range and ends just before the second range.
5112 Otherwise, we can't describe this as a single range. */
5118 {
5123 {
5124 /* We are in the weird situation where high0 > high1 but
5125 high1 has no successor. Punt. */
5127 }
5128 }
5130 {
5135 {
5136 /* low0 < low1 but low1 has no predecessor. Punt. */
5138 }
5139 }
5140 else
5142 }
5145 {
5146 /* If they don't overlap, the result is the second range. If the second
5147 is a subset of the first, the result is false. Otherwise,
5148 the range starts just after the first range and ends at the
5149 end of the second. */
5154 else
5155 {
5160 {
5161 /* high1 > high0 but high0 has no successor. Punt. */
5163 }
5164 }
5165 }
5167 else
5168 {
5169 /* The case where we are excluding both ranges. Here the complex case
5170 is if they don't overlap. In that case, the only time we have a
5171 range is if they are adjacent. If the second is a subset of the
5172 first, the result is the first. Otherwise, the range to exclude
5173 starts at the beginning of the first range and ends at the end of the
5174 second. */
5176 {
5181 else
5182 {
5183 /* Canonicalize - [min, x] into - [-, x]. */
5186 {
5191 /* FALLTHROUGH */
5204 }
5206 /* Canonicalize - [x, max] into - [x, -]. */
5209 {
5214 /* FALLTHROUGH */
5230 }
5232 /* The ranges might be also adjacent between the maximum and
5233 minimum values of the given type. For
5234 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5235 return + [x + 1, y - 1]. */
5237 {
5244 }
5245 else
5247 }
5248 }
5251 else
5253 }
5257 }
5258 \f
5260 /* Subroutine of fold, looking inside expressions of the form
5261 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5262 of the COND_EXPR. This function is being used also to optimize
5263 A op B ? C : A, by reversing the comparison first.
5265 Return a folded expression whose code is not a COND_EXPR
5266 anymore, or NULL_TREE if no folding opportunity is found. */
5268 static tree
5271 {
5276 tree tem;
5281 /* If we have A op 0 ? A : -A, consider applying the following
5282 transformations:
5284 A == 0? A : -A same as -A
5285 A != 0? A : -A same as A
5286 A >= 0? A : -A same as abs (A)
5287 A > 0? A : -A same as abs (A)
5288 A <= 0? A : -A same as -abs (A)
5289 A < 0? A : -A same as -abs (A)
5291 None of these transformations work for modes with signed
5292 zeros. If A is +/-0, the first two transformations will
5293 change the sign of the result (from +0 to -0, or vice
5294 versa). The last four will fix the sign of the result,
5295 even though the original expressions could be positive or
5296 negative, depending on the sign of A.
5298 Note that all these transformations are correct if A is
5299 NaN, since the two alternatives (A and -A) are also NaNs. */
5306 /* In the case that A is of the form X-Y, '-A' (arg2) may
5307 have already been folded to Y-X, check for that. */
5315 {
5327 /* Fall through. */
5338 /* FALLTHRU */
5348 }
5350 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5351 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5352 both transformations are correct when A is NaN: A != 0
5353 is then true, and A == 0 is false. */
5357 {
5362 }
5364 /* Try some transformations of A op B ? A : B.
5366 A == B? A : B same as B
5367 A != B? A : B same as A
5368 A >= B? A : B same as max (A, B)
5369 A > B? A : B same as max (B, A)
5370 A <= B? A : B same as min (A, B)
5371 A < B? A : B same as min (B, A)
5373 As above, these transformations don't work in the presence
5374 of signed zeros. For example, if A and B are zeros of
5375 opposite sign, the first two transformations will change
5376 the sign of the result. In the last four, the original
5377 expressions give different results for (A=+0, B=-0) and
5378 (A=-0, B=+0), but the transformed expressions do not.
5380 The first two transformations are correct if either A or B
5381 is a NaN. In the first transformation, the condition will
5382 be false, and B will indeed be chosen. In the case of the
5383 second transformation, the condition A != B will be true,
5384 and A will be chosen.
5386 The conversions to max() and min() are not correct if B is
5387 a number and A is not. The conditions in the original
5388 expressions will be false, so all four give B. The min()
5389 and max() versions would give a NaN instead. */
5392 /* Avoid these transformations if the COND_EXPR may be used
5393 as an lvalue in the C++ front-end. PR c++/19199. */
5394 && (in_gimple_form
5400 {
5406 {
5415 /* In C++ a ?: expression can be an lvalue, so put the
5416 operand which will be used if they are equal first
5417 so that we can convert this back to the
5418 corresponding COND_EXPR. */
5420 {
5428 }
5435 {
5443 }
5456 }
5457 }
5460 }
5463 \f
5464 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5465 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5466 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5467 false) >= 2)
5468 #endif
5470 /* EXP is some logical combination of boolean tests. See if we can
5471 merge it into some range test. Return the new tree if so. */
5473 static tree
5476 {
5492 /* If this is an OR operation, invert both sides; we will invert
5493 again at the end. */
5497 /* If both expressions are the same, if we can merge the ranges, and we
5498 can build the range test, return it or it inverted. If one of the
5499 ranges is always true or always false, consider it to be the same
5500 expression as the other. */
5508 {
5512 }
5514 /* On machines where the branch cost is expensive, if this is a
5515 short-circuited branch and the underlying object on both sides
5516 is the same, make a non-short-circuit operation. */
5518 && !flag_sanitize_coverage
5523 {
5524 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5525 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5526 which cases we can't do this. */
5534 {
5543 {
5546 WARN_STRICT_OVERFLOW_COMPARISON);
5550 }
5551 }
5552 }
5555 }
5556 \f
5557 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5558 bit value. Arrange things so the extra bits will be set to zero if and
5559 only if C is signed-extended to its full width. If MASK is nonzero,
5560 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5562 static tree
5564 {
5567 tree temp;
5572 /* We work by getting just the sign bit into the low-order bit, then
5573 into the high-order bit, then sign-extend. We then XOR that value
5574 with C. */
5578 /* We must use a signed type in order to get an arithmetic right shift.
5579 However, we must also avoid introducing accidental overflows, so that
5580 a subsequent call to integer_zerop will work. Hence we must
5581 do the type conversion here. At this point, the constant is either
5582 zero or one, and the conversion to a signed type can never overflow.
5583 We could get an overflow if this conversion is done anywhere else. */
5592 /* If necessary, convert the type back to match the type of C. */
5597 }
5598 \f
5599 /* For an expression that has the form
5600 (A && B) || ~B
5601 or
5602 (A || B) && ~B,
5603 we can drop one of the inner expressions and simplify to
5604 A || ~B
5605 or
5606 A && ~B
5607 LOC is the location of the resulting expression. OP is the inner
5608 logical operation; the left-hand side in the examples above, while CMPOP
5609 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5610 removing a condition that guards another, as in
5611 (A != NULL && A->...) || A == NULL
5612 which we must not transform. If RHS_ONLY is true, only eliminate the
5613 right-most operand of the inner logical operation. */
5615 static tree
5618 {
5636 {
5639 {
5642 }
5643 }
5645 {
5648 {
5651 }
5652 }
5667 }
5669 /* Find ways of folding logical expressions of LHS and RHS:
5670 Try to merge two comparisons to the same innermost item.
5671 Look for range tests like "ch >= '0' && ch <= '9'".
5672 Look for combinations of simple terms on machines with expensive branches
5673 and evaluate the RHS unconditionally.
5675 For example, if we have p->a == 2 && p->b == 4 and we can make an
5676 object large enough to span both A and B, we can do this with a comparison
5677 against the object ANDed with the a mask.
5679 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5680 operations to do this with one comparison.
5682 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5683 function and the one above.
5685 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5686 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5688 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5689 two operands.
5691 We return the simplified tree or 0 if no optimization is possible. */
5693 static tree
5696 {
5697 /* If this is the "or" of two comparisons, we can do something if
5698 the comparisons are NE_EXPR. If this is the "and", we can do something
5699 if the comparisons are EQ_EXPR. I.e.,
5700 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5702 WANTED_CODE is this operation code. For single bit fields, we can
5703 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5704 comparison for one-bit fields. */
5725 /* Start by getting the comparison codes. Fail if anything is volatile.
5726 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5727 it were surrounded with a NE_EXPR. */
5736 {
5740 }
5743 {
5747 }
5758 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5761 {
5764 {
5769 }
5772 {
5778 }
5779 }
5784 /* If the RHS can be evaluated unconditionally and its operands are
5785 simple, it wins to evaluate the RHS unconditionally on machines
5786 with expensive branches. In this case, this isn't a comparison
5787 that can be merged. */
5794 {
5795 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5806 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5816 }
5818 /* See if the comparisons can be merged. Then get all the parameters for
5819 each side. */
5844 /* It must be true that the inner operation on the lhs of each
5845 comparison must be the same if we are to be able to do anything.
5846 Then see if we have constants. If not, the same must be true for
5847 the rhs's. */
5856 {
5859 }
5864 else
5867 /* If either comparison code is not correct for our logical operation,
5868 fail. However, we can convert a one-bit comparison against zero into
5869 the opposite comparison against that bit being set in the field. */
5873 {
5875 {
5876 /* Make the left operand unsigned, since we are only interested
5877 in the value of one bit. Otherwise we are doing the wrong
5878 thing below. */
5881 }
5882 else
5884 }
5886 /* This is analogous to the code for l_const above. */
5888 {
5890 {
5893 }
5894 else
5896 }
5898 /* See if we can find a mode that contains both fields being compared on
5899 the left. If we can't, fail. Otherwise, update all constants and masks
5900 to be relative to a field of that size. */
5914 {
5917 }
5925 {
5932 {
5936 }
5937 }
5939 {
5946 {
5950 }
5951 }
5953 /* If the right sides are not constant, do the same for it. Also,
5954 disallow this optimization if a size or signedness mismatch occurs
5955 between the left and right sides. */
5957 {
5960 /* Make sure the two fields on the right
5961 correspond to the left without being swapped. */
5978 {
5981 }
5990 /* Make a mask that corresponds to both fields being compared.
5991 Do this for both items being compared. If the operands are the
5992 same size and the bits being compared are in the same position
5993 then we can do this by masking both and comparing the masked
5994 results. */
6001 {
6015 }
6017 /* There is still another way we can do something: If both pairs of
6018 fields being compared are adjacent, we may be able to make a wider
6019 field containing them both.
6021 Note that we still must mask the lhs/rhs expressions. Furthermore,
6022 the mask must be shifted to account for the shift done by
6023 make_bit_field_ref. */
6032 {
6033 tree type;
6049 /* Convert to the smaller type before masking out unwanted bits. */
6052 {
6054 {
6058 }
6060 {
6064 }
6065 }
6074 }
6077 }
6079 /* Handle the case of comparisons with constants. If there is something in
6080 common between the masks, those bits of the constants must be the same.
6081 If not, the condition is always false. Test for this to avoid generating
6082 incorrect code below. */
6087 {
6089 {
6092 }
6093 else
6094 {
6097 }
6098 }
6103 /* Construct the expression we will return. First get the component
6104 reference we will make. Unless the mask is all ones the width of
6105 that field, perform the mask operation. Then compare with the
6106 merged constant. */
6117 }
6118 \f
6119 /* T is an integer expression that is being multiplied, divided, or taken a
6120 modulus (CODE says which and what kind of divide or modulus) by a
6121 constant C. See if we can eliminate that operation by folding it with
6122 other operations already in T. WIDE_TYPE, if non-null, is a type that
6123 should be used for the computation if wider than our type.
6125 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6126 (X * 2) + (Y * 4). We must, however, be assured that either the original
6127 expression would not overflow or that overflow is undefined for the type
6128 in the language in question.
6130 If we return a non-null expression, it is an equivalent form of the
6131 original computation, but need not be in the original type.
6133 We set *STRICT_OVERFLOW_P to true if the return values depends on
6134 signed overflow being undefined. Otherwise we do not change
6135 *STRICT_OVERFLOW_P. */
6137 static tree
6140 {
6141 /* To avoid exponential search depth, refuse to allow recursion past
6142 three levels. Beyond that (1) it's highly unlikely that we'll find
6143 something interesting and (2) we've probably processed it before
6144 when we built the inner expression. */
6147 tree ret;
6152 depth++;
6154 depth--;
6157 }
6159 static tree
6162 {
6174 /* Don't deal with constants of zero here; they confuse the code below. */
6184 /* Note that we need not handle conditional operations here since fold
6185 already handles those cases. So just do arithmetic here. */
6187 {
6189 /* For a constant, we can always simplify if we are a multiply
6190 or (for divide and modulus) if it is a multiple of our constant. */
6194 {
6197 /* If the multiplication overflowed, we lost information on it.
6198 See PR68142 and PR69845. */
6202 }
6206 /* If op0 is an expression ... */
6212 /* ... and has wrapping overflow, and its type is smaller
6213 than ctype, then we cannot pass through as widening. */
6218 /* ... or this is a truncation (t is narrower than op0),
6219 then we cannot pass through this narrowing. */
6222 /* ... or signedness changes for division or modulus,
6223 then we cannot pass through this conversion. */
6227 /* ... or has undefined overflow while the converted to
6228 type has not, we cannot do the operation in the inner type
6229 as that would introduce undefined overflow. */
6235 /* Pass the constant down and see if we can make a simplification. If
6236 we can, replace this expression with the inner simplification for
6237 possible later conversion to our or some other type. */
6248 /* If widening the type changes it from signed to unsigned, then we
6249 must avoid building ABS_EXPR itself as unsigned. */
6251 {
6255 {
6258 }
6260 }
6261 /* If the constant is negative, we cannot simplify this. */
6264 /* FALLTHROUGH */
6266 /* For division and modulus, type can't be unsigned, as e.g.
6267 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6268 For signed types, even with wrapping overflow, this is fine. */
6277 /* If widening the type changes the signedness, then we can't perform
6278 this optimization as that changes the result. */
6282 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6288 {
6295 }
6299 /* If the second operand is constant, this is a multiplication
6300 or floor division, by a power of two, so we can treat it that
6301 way unless the multiplier or divisor overflows. Signed
6302 left-shift overflow is implementation-defined rather than
6303 undefined in C90, so do not convert signed left shift into
6304 multiplication. */
6307 /* const_binop may not detect overflow correctly,
6308 so check for it explicitly here. */
6317 ctype,
6319 t1),
6324 /* See if we can eliminate the operation on both sides. If we can, we
6325 can return a new PLUS or MINUS. If we can't, the only remaining
6326 cases where we can do anything are if the second operand is a
6327 constant. */
6334 /* If not multiplication, we can only do this if both operands
6335 are divisible by c. */
6338 {
6343 }
6345 /* If this was a subtraction, negate OP1 and set it to be an addition.
6346 This simplifies the logic below. */
6348 {
6350 /* If OP1 was not easily negatable, the constant may be OP0. */
6352 {
6355 }
6356 }
6361 /* If either OP1 or C are negative, this optimization is not safe for
6362 some of the division and remainder types while for others we need
6363 to change the code. */
6365 {
6373 }
6375 /* If it's a multiply or a division/modulus operation of a multiple
6376 of our constant, do the operation and verify it doesn't overflow. */
6380 {
6383 /* We allow the constant to overflow with wrapping semantics. */
6387 }
6388 else
6391 /* If we have an unsigned type, we cannot widen the operation since it
6392 will change the result if the original computation overflowed. */
6396 /* The last case is if we are a multiply. In that case, we can
6397 apply the distributive law to commute the multiply and addition
6398 if the multiplication of the constants doesn't overflow
6399 and overflow is defined. With undefined overflow
6400 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6406 op1);
6411 /* We have a special case here if we are doing something like
6412 (C * 8) % 4 since we know that's zero. */
6415 /* If the multiplication can overflow we cannot optimize this. */
6420 {
6423 }
6425 /* ... fall through ... */
6429 /* If we can extract our operation from the LHS, do so and return a
6430 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6431 do something only if the second operand is a constant. */
6447 /* If these are the same operation types, we can associate them
6448 assuming no overflow. */
6450 {
6465 }
6467 /* If these operations "cancel" each other, we have the main
6468 optimizations of this pass, which occur when either constant is a
6469 multiple of the other, in which case we replace this with either an
6470 operation or CODE or TCODE.
6472 If we have an unsigned type, we cannot do this since it will change
6473 the result if the original computation overflowed. */
6480 {
6483 {
6490 }
6493 {
6500 }
6501 }
6506 }
6509 }
6510 \f
6511 /* Return a node which has the indicated constant VALUE (either 0 or
6512 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6513 and is of the indicated TYPE. */
6515 tree
6517 {
6526 else
6528 }
6531 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6532 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6533 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6534 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6535 COND is the first argument to CODE; otherwise (as in the example
6536 given here), it is the second argument. TYPE is the type of the
6537 original expression. Return NULL_TREE if no simplification is
6538 possible. */
6540 static tree
6545 {
6555 {
6559 /* If this operand throws an expression, then it does not make
6560 sense to try to perform a logical or arithmetic operation
6561 involving it. */
6566 }
6569 {
6574 }
6575 else
6576 /* Detect the case of mixing vector and scalar types - bail out. */
6582 /* This transformation is only worthwhile if we don't have to wrap ARG
6583 in a SAVE_EXPR and the operation can be simplified without recursing
6584 on at least one of the branches once its pushed inside the COND_EXPR. */
6593 {
6597 else
6599 }
6601 {
6605 else
6607 }
6609 /* Check that we have simplified at least one of the branches. */
6614 }
6616 \f
6617 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6619 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6620 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6621 ADDEND is the same as X.
6623 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6624 and finite. The problematic cases are when X is zero, and its mode
6625 has signed zeros. In the case of rounding towards -infinity,
6626 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6627 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6629 bool
6631 {
6635 /* Don't allow the fold with -fsignaling-nans. */
6639 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6643 /* In a vector or complex, we would need to check the sign of all zeros. */
6647 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6651 /* The mode has signed zeros, and we have to honor their sign.
6652 In this situation, there is only one case we can return true for.
6653 X - 0 is the same as X unless rounding towards -infinity is
6654 supported. */
6656 }
6658 /* Subroutine of match.pd that optimizes comparisons of a division by
6659 a nonzero integer constant against an integer constant, i.e.
6660 X/C1 op C2.
6662 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6663 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6665 enum tree_code
6668 {
6673 /* We have to do this the hard way to detect unsigned overflow.
6674 prod = int_const_binop (MULT_EXPR, c1, c2); */
6680 {
6684 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6687 }
6689 {
6692 {
6711 }
6712 }
6713 else
6714 {
6715 /* A negative divisor reverses the relational operators. */
6720 {
6739 }
6740 }
6753 }
6756 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6757 equality/inequality test, then return a simplified form of the test
6758 using a sign testing. Otherwise return NULL. TYPE is the desired
6759 result type. */
6761 static tree
6764 tree result_type)
6765 {
6766 /* If this is testing a single bit, we can optimize the test. */
6770 {
6771 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6772 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6776 /* This is only a win if casting to a signed type is cheap,
6777 i.e. when arg00's type is not a partial mode. */
6779 {
6782 result_type,
6785 }
6786 }
6789 }
6791 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6792 equality/inequality test, then return a simplified form of
6793 the test using shifts and logical operations. Otherwise return
6794 NULL. TYPE is the desired result type. */
6796 tree
6799 {
6800 /* If this is testing a single bit, we can optimize the test. */
6804 {
6813 /* First, see if we can fold the single bit test into a sign-bit
6814 test. */
6816 result_type);
6820 /* Otherwise we have (A & C) != 0 where C is a single bit,
6821 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6822 Similarly for (A & C) == 0. */
6824 /* If INNER is a right shift of a constant and it plus BITNUM does
6825 not overflow, adjust BITNUM and INNER. */
6831 {
6834 }
6836 /* If we are going to be able to omit the AND below, we must do our
6837 operations as unsigned. If we must use the AND, we have a choice.
6838 Normally unsigned is faster, but for some machines signed is. */
6856 /* Put the AND last so it can combine with more things. */
6859 /* Make sure to return the proper type. */
6863 }
6865 }
6867 /* Test whether it is preferable two swap two operands, ARG0 and
6868 ARG1, for example because ARG0 is an integer constant and ARG1
6869 isn't. */
6871 bool
6873 {
6887 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6888 for commutative and comparison operators. Ensuring a canonical
6889 form allows the optimizers to find additional redundancies without
6890 having to explicitly check for both orderings. */
6896 /* Put SSA_NAMEs last. */
6902 /* Put variables last. */
6909 }
6912 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6913 means A >= Y && A != MAX, but in this case we know that
6914 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6916 static tree
6918 {
6925 else
6934 {
6937 }
6939 {
6942 }
6943 else
6950 {
6951 /* Convert the pointer types into integer before taking the difference. */
6955 }
6956 else
6963 }
6965 /* Fold a sum or difference of at least one multiplication.
6966 Returns the folded tree or NULL if no simplification could be made. */
6968 static tree
6971 {
6975 /* (A * C) +- (B * C) -> (A+-B) * C.
6976 (A * C) +- A -> A * (C+-1).
6977 We are most concerned about the case where C is a constant,
6978 but other combinations show up during loop reduction. Since
6979 it is not difficult, try all four possibilities. */
6982 {
6985 }
6987 {
6990 }
6991 else
6992 {
6993 /* We cannot generate constant 1 for fract. */
6998 }
7000 {
7003 }
7005 {
7007 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7008 the purpose of this canonicalization. */
7012 {
7015 }
7016 else
7018 }
7019 else
7020 {
7021 /* We cannot generate constant 1 for fract. */
7026 }
7029 /* Prefer factoring a common non-constant. */
7039 /* No identical multiplicands; see if we can find a common
7040 power-of-two factor in non-power-of-two multiplies. This
7041 can help in multi-dimensional array access. */
7044 {
7047 tree maybe_same;
7051 /* Move min of absolute values to int11. */
7053 {
7058 }
7059 else
7063 /* The remainder should not be a constant, otherwise we
7064 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7065 increased the number of multiplications necessary. */
7067 {
7075 }
7076 }
7083 /* We are neither factoring zero nor minus one. */
7091 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7092 same may be minus one and thus the multiplication may overflow. Perform
7093 the operations in an unsigned type. */
7098 /* If the sum evaluated to a constant that is not -INF the multiplication
7099 cannot overflow. */
7109 }
7111 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7112 specified by EXPR into the buffer PTR of length LEN bytes.
7113 Return the number of bytes placed in the buffer, or zero
7114 upon failure. */
7116 static int
7118 {
7130 /* Dry run. */
7136 {
7138 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7139 number of bytes. */
7143 {
7150 else
7152 }
7153 else
7157 }
7159 }
7162 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7163 specified by EXPR into the buffer PTR of length LEN bytes.
7164 Return the number of bytes placed in the buffer, or zero
7165 upon failure. */
7167 static int
7169 {
7173 FIXED_VALUE_TYPE value;
7188 }
7191 /* Subroutine of native_encode_expr. Encode the REAL_CST
7192 specified by EXPR into the buffer PTR of length LEN bytes.
7193 Return the number of bytes placed in the buffer, or zero
7194 upon failure. */
7196 static int
7198 {
7204 /* There are always 32 bits in each long, no matter the size of
7205 the hosts long. We handle floating point representations with
7206 up to 192 bits. */
7215 /* Dry run. */
7224 {
7229 {
7236 else
7238 }
7239 else
7240 {
7243 {
7244 /* Reverse bytes within each long, or within the entire float
7245 if it's smaller than a long (for HFmode). */
7248 }
7249 }
7254 }
7256 }
7258 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7259 specified by EXPR into the buffer PTR of length LEN bytes.
7260 Return the number of bytes placed in the buffer, or zero
7261 upon failure. */
7263 static int
7265 {
7267 tree part;
7281 }
7284 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7285 specified by EXPR into the buffer PTR of length LEN bytes.
7286 Return the number of bytes placed in the buffer, or zero
7287 upon failure. */
7289 static int
7291 {
7301 {
7303 {
7306 }
7317 }
7319 }
7322 /* Subroutine of native_encode_expr. Encode the STRING_CST
7323 specified by EXPR into the buffer PTR of length LEN bytes.
7324 Return the number of bytes placed in the buffer, or zero
7325 upon failure. */
7327 static int
7329 {
7332 /* Wide-char strings are encoded in target byte-order so native
7333 encoding them is trivial. */
7348 {
7351 {
7354 }
7357 }
7358 else
7361 }
7364 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7365 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7366 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7367 anything, just do a dry run. If OFF is not -1 then start
7368 the encoding at byte offset OFF and encode at most LEN bytes.
7369 Return the number of bytes placed in the buffer, or zero upon failure. */
7371 int
7373 {
7374 /* We don't support starting at negative offset and -1 is special. */
7379 {
7400 }
7401 }
7404 /* Subroutine of native_interpret_expr. Interpret the contents of
7405 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7406 If the buffer cannot be interpreted, return NULL_TREE. */
7408 static tree
7410 {
7420 }
7423 /* Subroutine of native_interpret_expr. Interpret the contents of
7424 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7425 If the buffer cannot be interpreted, return NULL_TREE. */
7427 static tree
7429 {
7432 double_int result;
7433 FIXED_VALUE_TYPE fixed_value;
7443 }
7446 /* Subroutine of native_interpret_expr. Interpret the contents of
7447 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7448 If the buffer cannot be interpreted, return NULL_TREE. */
7450 static tree
7452 {
7456 /* There are always 32 bits in each long, no matter the size of
7457 the hosts long. We handle floating point representations with
7458 up to 192 bits. */
7459 REAL_VALUE_TYPE r;
7469 {
7470 /* Both OFFSET and BYTE index within a long;
7471 bitpos indexes the whole float. */
7474 {
7481 else
7483 }
7484 else
7485 {
7488 {
7489 /* Reverse bytes within each long, or within the entire float
7490 if it's smaller than a long (for HFmode). */
7493 }
7494 }
7498 }
7502 }
7505 /* Subroutine of native_interpret_expr. Interpret the contents of
7506 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7507 If the buffer cannot be interpreted, return NULL_TREE. */
7509 static tree
7511 {
7526 }
7529 /* Subroutine of native_interpret_expr. Interpret the contents of
7530 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7531 If the buffer cannot be interpreted, return NULL_TREE. */
7533 static tree
7535 {
7547 {
7552 }
7554 }
7557 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7558 the buffer PTR of length LEN as a constant of type TYPE. For
7559 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7560 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7561 return NULL_TREE. */
7563 tree
7565 {
7567 {
7589 }
7590 }
7592 /* Returns true if we can interpret the contents of a native encoding
7593 as TYPE. */
7595 static bool
7597 {
7599 {
7612 }
7613 }
7616 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7617 TYPE at compile-time. If we're unable to perform the conversion
7618 return NULL_TREE. */
7620 static tree
7622 {
7623 /* We support up to 512-bit values (for V8DFmode). */
7627 /* Check that the host and target are sane. */
7636 }
7638 /* Build an expression for the address of T. Folds away INDIRECT_REF
7639 to avoid confusing the gimplify process. */
7641 tree
7643 {
7644 /* The size of the object is not relevant when talking about its address. */
7649 {
7654 }
7664 {
7669 }
7670 else
7674 }
7676 /* Build an expression for the address of T. */
7678 tree
7680 {
7684 }
7686 /* Fold a unary expression of code CODE and type TYPE with operand
7687 OP0. Return the folded expression if folding is successful.
7688 Otherwise, return NULL_TREE. */
7690 tree
7692 {
7693 tree tem;
7694 tree arg0;
7702 {
7705 {
7706 /* Don't use STRIP_NOPS, because signedness of argument type
7707 matters. */
7709 }
7710 else
7711 {
7712 /* Strip any conversions that don't change the mode. This
7713 is safe for every expression, except for a comparison
7714 expression because its signedness is derived from its
7715 operands.
7717 Note that this is done as an internal manipulation within
7718 the constant folder, in order to find the simplest
7719 representation of the arguments so that their form can be
7720 studied. In any cases, the appropriate type conversions
7721 should be put back in the tree that will get out of the
7722 constant folder. */
7724 }
7727 {
7730 {
7734 }
7735 }
7736 }
7743 {
7750 {
7764 /* If this was a conversion, and all we did was to move into
7765 inside the COND_EXPR, bring it back out. But leave it if
7766 it is a conversion from integer to integer and the
7767 result precision is no wider than a word since such a
7768 conversion is cheap and may be optimized away by combine,
7769 while it couldn't if it were outside the COND_EXPR. Then return
7770 so we don't get into an infinite recursion loop taking the
7771 conversion out and then back in. */
7783 && (INTEGRAL_TYPE_P
7796 }
7797 }
7800 {
7806 CASE_CONVERT:
7810 {
7811 /* If we have (type) (a CMP b) and type is an integral type, return
7812 new expression involving the new type. Canonicalize
7813 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7814 non-integral type.
7815 Do not fold the result as that would not simplify further, also
7816 folding again results in recursions. */
7826 }
7828 /* Handle (T *)&A.B.C for A being of type T and B and C
7829 living at offset zero. This occurs frequently in
7830 C++ upcasting and then accessing the base. */
7834 {
7836 tree offset;
7837 machine_mode mode;
7839 tree base
7843 /* If the reference was to a (constant) zero offset, we can use
7844 the address of the base if it has the same base type
7845 as the result type and the pointer type is unqualified. */
7853 }
7857 /* Detect assigning a bitfield. */
7859 && DECL_BIT_FIELD
7861 {
7862 /* Don't leave an assignment inside a conversion
7863 unless assigning a bitfield. */
7865 /* First do the assignment, then return converted constant. */
7870 }
7872 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7873 constants (if x has signed type, the sign bit cannot be set
7874 in c). This folds extension into the BIT_AND_EXPR.
7875 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7876 very likely don't have maximal range for their precision and this
7877 transformation effectively doesn't preserve non-maximal ranges. */
7881 {
7892 <= HOST_BITS_PER_WIDE_INT
7894 {
7898 cst &= HOST_WIDE_INT_M1U
7902 && !flag_syntax_only
7905 {
7909 }
7910 }
7912 {
7917 }
7918 }
7920 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7921 cast (T1)X will fold away. We assume that this happens when X itself
7922 is a cast. */
7926 {
7930 return fold_build_pointer_plus_loc
7932 }
7934 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7935 of the same precision, and X is an integer type not narrower than
7936 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7942 {
7948 }
7950 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7951 type of X and Y (integer types only). */
7956 {
7957 /* Be careful not to introduce new overflows. */
7958 tree mult_type;
7961 else
7965 {
7972 }
7973 }
7979 {
7986 }
7997 /* Convert fabs((double)float) into (double)fabsf(float). */
8000 {
8006 targ0));
8007 }
8011 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8030 /* Note that the operand of this must be an int
8031 and its values must be 0 or 1.
8032 ("true" is a fixed value perhaps depending on the language,
8033 but we don't handle values other than 1 correctly yet.) */
8040 /* Fold *&X to X if X is an lvalue. */
8042 {
8049 }
8055 }
8058 /* If the operation was a conversion do _not_ mark a resulting constant
8059 with TREE_OVERFLOW if the original constant was not. These conversions
8060 have implementation defined behavior and retaining the TREE_OVERFLOW
8061 flag here would confuse later passes such as VRP. */
8062 tree
8065 {
8074 }
8076 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8077 operands OP0 and OP1. LOC is the location of the resulting expression.
8078 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8079 Return the folded expression if folding is successful. Otherwise,
8080 return NULL_TREE. */
8081 static tree
8084 {
8085 tree tem;
8087 /* We only do these simplifications if we are optimizing. */
8091 /* Check for things like (A || B) && (A || C). We can convert this
8092 to A || (B && C). Note that either operator can be any of the four
8093 truth and/or operations and the transformation will still be
8094 valid. Also note that we only care about order for the
8095 ANDIF and ORIF operators. If B contains side effects, this
8096 might change the truth-value of A. */
8103 {
8123 /* This case if tricky because we must either have commutative
8124 operators or else A10 must not have side-effects. */
8130 a01);
8131 }
8133 /* See if we can build a range comparison. */
8139 {
8143 }
8147 {
8151 }
8153 /* Check for the possibility of merging component references. If our
8154 lhs is another similar operation, try to merge its rhs with our
8155 rhs. Then try to merge our lhs and rhs. */
8165 && !flag_sanitize_coverage
8170 {
8177 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8178 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8179 We don't want to pack more than two leafs to a non-IF AND/OR
8180 expression.
8181 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8182 equal to IF-CODE, then we don't want to add right-hand operand.
8183 If the inner right-hand side of left-hand operand has
8184 side-effects, or isn't simple, then we can't add to it,
8185 as otherwise we might destroy if-sequence. */
8188 /* Needed for sequence points to handle trappings, and
8189 side-effects. */
8191 {
8193 arg1);
8195 tem);
8196 }
8197 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8198 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8201 /* Needed for sequence points to handle trappings, and
8202 side-effects. */
8204 {
8209 }
8210 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8211 into (A OR B).
8212 For sequence point consistancy, we need to check for trapping,
8213 and side-effects. */
8217 }
8220 }
8222 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8223 by changing CODE to reduce the magnitude of constants involved in
8224 ARG0 of the comparison.
8225 Returns a canonicalized comparison tree if a simplification was
8226 possible, otherwise returns NULL_TREE.
8227 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8228 valid if signed overflow is undefined. */
8230 static tree
8234 {
8239 /* Match A +- CST code arg1. We can change this only if overflow
8240 is undefined. */
8243 /* In principle pointers also have undefined overflow behavior,
8244 but that causes problems elsewhere. */
8251 /* Identify the constant in arg0 and its sign. */
8255 /* Overflowed constants and zero will cause problems. */
8260 /* See if we can reduce the magnitude of the constant in
8261 arg0 by changing the comparison code. */
8262 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8266 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8270 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8274 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8278 else
8282 /* Now build the constant reduced in magnitude. But not if that
8283 would produce one outside of its types range. */
8299 }
8301 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8302 overflow further. Try to decrease the magnitude of constants involved
8303 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8304 and put sole constants at the second argument position.
8305 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8307 static tree
8310 {
8311 tree t;
8316 /* Try canonicalization by simplifying arg0. */
8321 {
8325 }
8327 /* Try canonicalization by simplifying arg1 using the swapped
8328 comparison. */
8336 }
8338 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8339 space. This is used to avoid issuing overflow warnings for
8340 expressions like &p->x which can not wrap. */
8342 static bool
8344 {
8351 poly_wide_int wi_offset;
8357 else
8362 precision);
8377 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8378 array. */
8387 }
8389 /* Return a positive integer when the symbol DECL is known to have
8390 a nonzero address, zero when it's known not to (e.g., it's a weak
8391 symbol), and a negative integer when the symbol is not yet in the
8392 symbol table and so whether or not its address is zero is unknown.
8393 For function local objects always return positive integer. */
8394 static int
8396 {
8401 /* Function local objects are never NULL. */
8409 }
8411 /* Subroutine of fold_binary. This routine performs all of the
8412 transformations that are common to the equality/inequality
8413 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8414 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8415 fold_binary should call fold_binary. Fold a comparison with
8416 tree code CODE and type TYPE with operands OP0 and OP1. Return
8417 the folded comparison or NULL_TREE. */
8419 static tree
8422 {
8432 /* For comparisons of pointers we can decompose it to a compile time
8433 comparison of the base objects and the offsets into the object.
8434 This requires at least one operand being an ADDR_EXPR or a
8435 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8441 {
8444 machine_mode mode;
8448 /* Get base and offset for the access. Strip ADDR_EXPR for
8449 get_inner_reference, but put it back by stripping INDIRECT_REF
8450 off the base object if possible. indirect_baseN will be true
8451 if baseN is not an address but refers to the object itself. */
8454 {
8455 base0
8461 else
8463 }
8465 {
8469 {
8470 base0
8476 else
8478 }
8481 else
8485 {
8492 }
8493 }
8497 {
8498 base1
8504 else
8506 }
8508 {
8512 {
8513 base1
8519 else
8521 }
8524 else
8528 {
8535 }
8536 }
8538 /* If we have equivalent bases we might be able to simplify. */
8542 {
8543 /* We can fold this expression to a constant if the non-constant
8544 offset parts are equal. */
8548 {
8554 "occur when comparing P +- C1 with "
8556 WARN_STRICT_OVERFLOW_CONDITIONAL);
8559 {
8597 }
8598 }
8599 /* We can simplify the comparison to a comparison of the variable
8600 offset parts if the constant offset parts are equal.
8601 Be careful to use signed sizetype here because otherwise we
8602 mess with array offsets in the wrong way. This is possible
8603 because pointer arithmetic is restricted to retain within an
8604 object and overflow on pointer differences is undefined as of
8605 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8607 {
8608 /* By converting to signed sizetype we cover middle-end pointer
8609 arithmetic which operates on unsigned pointer types of size
8610 type size and ARRAY_REF offsets which are properly sign or
8611 zero extended from their type in case it is narrower than
8612 sizetype. */
8615 else
8619 else
8626 "occur when comparing P +- C1 with "
8628 WARN_STRICT_OVERFLOW_COMPARISON);
8631 }
8632 }
8633 /* For equal offsets we can simplify to a comparison of the
8634 base addresses. */
8636 && (indirect_base0
8638 && (indirect_base1
8643 {
8649 }
8650 /* Comparison between an ordinary (non-weak) symbol and a null
8651 pointer can be eliminated since such symbols must have a non
8652 null address. In C, relational expressions between pointers
8653 to objects and null pointers are undefined. The results
8654 below follow the C++ rules with the additional property that
8655 every object pointer compares greater than a null pointer.
8656 */
8659 /* Avoid folding references to struct members at offset 0 to
8660 prevent tests like '&ptr->firstmember == 0' from getting
8661 eliminated. When ptr is null, although the -> expression
8662 is strictly speaking invalid, GCC retains it as a matter
8663 of QoI. See PR c/44555. */
8666 && indirect_base0
8667 /* The caller guarantees that when one of the arguments is
8668 constant (i.e., null in this case) it is second. */
8670 {
8672 {
8683 }
8684 }
8685 }
8687 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8688 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8689 the resulting offset is smaller in absolute value than the
8690 original one and has the same sign. */
8699 {
8704 tree cst;
8706 "occur when combining constants around "
8709 /* Put the constant on the side where it doesn't overflow and is
8710 of lower absolute value and of same sign than before. */
8717 {
8720 variable1,
8724 }
8732 {
8738 variable2);
8739 }
8740 }
8746 /* If we are comparing an expression that just has comparisons
8747 of two integer values, arithmetic expressions of those comparisons,
8748 and constants, we can simplify it. There are only three cases
8749 to check: the two values can either be equal, the first can be
8750 greater, or the second can be greater. Fold the expression for
8751 those three values. Since each value must be 0 or 1, we have
8752 eight possibilities, each of which corresponds to the constant 0
8753 or 1 or one of the six possible comparisons.
8755 This handles common cases like (a > b) == 0 but also handles
8756 expressions like ((x > y) - (y > x)) > 0, which supposedly
8757 occur in macroized code. */
8760 {
8765 /* Don't handle degenerate cases here; they should already
8766 have been handled anyway. */
8775 {
8779 /* We can't just pass T to eval_subst in case cval1 or cval2
8780 was the same as ARG1. */
8782 tree high_result
8786 arg1);
8787 tree equal_result
8791 arg1);
8792 tree low_result
8796 arg1);
8798 /* All three of these results should be 0 or 1. Confirm they are.
8799 Then use those values to select the proper code to use. */
8804 {
8805 /* Make a 3-bit mask with the high-order bit being the
8806 value for `>', the next for '=', and the low for '<'. */
8810 {
8812 /* Always false. */
8833 /* Always true. */
8835 }
8838 {
8842 }
8844 }
8845 }
8846 }
8849 }
8852 /* Subroutine of fold_binary. Optimize complex multiplications of the
8853 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8854 argument EXPR represents the expression "z" of type TYPE. */
8856 static tree
8858 {
8863 {
8866 }
8868 {
8871 }
8872 else
8873 {
8877 }
8886 }
8889 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8890 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8891 true if successful. */
8893 static bool
8895 {
8899 {
8902 }
8904 {
8910 else
8912 }
8913 else
8919 }
8921 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8922 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8923 NULL_TREE otherwise. */
8925 static tree
8927 {
8946 {
8950 }
8953 {
8959 }
8960 else
8962 }
8964 /* Try to fold a pointer difference of type TYPE two address expressions of
8965 array references AREF0 and AREF1 using location LOC. Return a
8966 simplified expression for the difference or NULL_TREE. */
8968 static tree
8972 {
8977 /* If the bases are array references as well, recurse. If the bases
8978 are pointer indirections compute the difference of the pointers.
8979 If the bases are equal, we are set. */
8982 && (base_offset
8984 use_pointer_diff)))
8987 && (base_offset
8988 = use_pointer_diff
8998 {
9004 base_offset,
9007 }
9009 }
9011 /* If the real or vector real constant CST of type TYPE has an exact
9012 inverse, return it, else return NULL. */
9014 tree
9016 {
9017 REAL_VALUE_TYPE r;
9018 tree unit_type;
9019 machine_mode mode;
9022 {
9032 {
9036 tree_vector_builder elts;
9041 {
9046 }
9049 }
9053 }
9054 }
9056 /* Mask out the tz least significant bits of X of type TYPE where
9057 tz is the number of trailing zeroes in Y. */
9058 static wide_int
9060 {
9065 }
9067 /* Return true when T is an address and is known to be nonzero.
9068 For floating point we further ensure that T is not denormal.
9069 Similar logic is present in nonzero_address in rtlanal.h.
9071 If the return value is based on the assumption that signed overflow
9072 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9073 change *STRICT_OVERFLOW_P. */
9075 static bool
9077 {
9081 /* Doing something useful for floating point would need more work. */
9087 {
9090 strict_overflow_p);
9096 strict_overflow_p);
9104 }
9107 {
9110 strict_overflow_p);
9118 strict_overflow_p);
9133 strict_overflow_p);
9137 strict_overflow_p);
9140 {
9152 }
9156 }
9158 }
9160 /* Return true when T is an address and is known to be nonzero.
9161 Handle warnings about undefined signed overflow. */
9163 bool
9165 {
9172 "determining that expression is always "
9174 WARN_STRICT_OVERFLOW_MISC);
9176 }
9178 /* Return true if T is known not to be equal to an integer W. */
9180 bool
9182 {
9184 value_range_type rtype;
9186 {
9195 {
9200 }
9205 /* If T has some known zero bits and W has any of those bits set,
9206 then T is known not to be equal to W. */
9214 }
9215 }
9217 /* Fold a binary expression of code CODE and type TYPE with operands
9218 OP0 and OP1. LOC is the location of the resulting expression.
9219 Return the folded expression if folding is successful. Otherwise,
9220 return NULL_TREE. */
9222 tree
9225 {
9240 /* Strip any conversions that don't change the mode. This is
9241 safe for every expression, except for a comparison expression
9242 because its signedness is derived from its operands. So, in
9243 the latter case, only strip conversions that don't change the
9244 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9245 preserved.
9247 Note that this is done as an internal manipulation within the
9248 constant folder, in order to find the simplest representation
9249 of the arguments so that their form can be studied. In any
9250 cases, the appropriate type conversions should be put back in
9251 the tree that will get out of the constant folder. */
9254 {
9257 }
9258 else
9259 {
9262 }
9264 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9265 constant but we can't do arithmetic on them. */
9267 {
9270 {
9274 }
9275 }
9277 /* If this is a commutative operation, and ARG0 is a constant, move it
9278 to ARG1 to reduce the number of tests below. */
9283 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9284 to ARG1 to reduce the number of tests below. */
9293 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9295 First check for cases where an arithmetic operation is applied to a
9296 compound, conditional, or comparison operation. Push the arithmetic
9297 operation inside the compound or conditional to see if any folding
9298 can then be done. Convert comparison to conditional for this purpose.
9299 The also optimizes non-constant cases that used to be done in
9300 expand_expr.
9302 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9303 one of the operands is a comparison and the other is a comparison, a
9304 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9305 code below would make the expression more complex. Change it to a
9306 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9307 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9320 {
9324 boolean_type_node,
9332 }
9336 {
9338 {
9343 tem);
9344 }
9346 {
9351 tem);
9352 }
9357 {
9363 }
9368 {
9374 }
9375 }
9378 {
9380 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9383 {
9389 }
9391 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9394 {
9395 tree base;
9396 poly_int64 coffset;
9405 }
9410 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9416 arg1),
9418 arg0)));
9424 {
9425 /* X + (X / CST) * -CST is X % CST. */
9430 {
9439 cst0));
9440 }
9441 }
9443 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9444 one. Make sure the type is not saturating and has the signedness of
9445 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9446 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9453 {
9457 }
9460 {
9461 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9462 (plus (plus (mult) (mult)) (foo)) so that we can
9463 take advantage of the factoring cases below. */
9472 {
9478 else
9491 parg0),
9493 marg)),
9497 return
9503 parg1)));
9504 }
9505 }
9506 else
9507 {
9508 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9509 to __complex__ ( x, y ). This is not the same for SNaNs or
9510 if signed zeros are involved. */
9514 {
9521 {
9525 {
9531 }
9533 {
9539 }
9540 }
9541 }
9543 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9544 We associate floats only if the user has specified
9545 -fassociative-math. */
9549 {
9554 {
9555 tree tree0;
9558 }
9559 }
9560 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9561 We associate floats only if the user has specified
9562 -fassociative-math. */
9566 {
9571 {
9572 tree tree0;
9575 }
9576 }
9577 }
9579 bit_rotate:
9580 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9581 is a rotate of A by C1 bits. */
9582 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9583 is a rotate of A by B bits.
9584 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9585 though in this case CODE must be | and not + or ^, otherwise
9586 it doesn't return A when B is 0. */
9587 {
9589 tree rtype;
9598 /* Only create rotates in complete modes. Other cases are not
9599 expanded properly. */
9602 {
9615 {
9620 }
9625 {
9628 code0 == LSHIFT_EXPR
9631 }
9633 {
9643 {
9647 orig_tree01);
9649 }
9650 }
9654 {
9665 {
9669 orig_tree01);
9671 }
9672 }
9673 }
9674 }
9676 associate:
9677 /* In most languages, can't associate operations on floats through
9678 parentheses. Rather than remember where the parentheses were, we
9679 don't associate floats at all, unless the user has specified
9680 -fassociative-math.
9681 And, we need to make sure type is not saturating. */
9685 {
9691 /* Split both trees into variables, constants, and literals. Then
9692 associate each group together, the constants with literals,
9693 then the result with variables. This increases the chances of
9694 literals being recombined later and of generating relocatable
9695 expressions for the sum of a constant and literal. */
9703 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9707 /* With undefined overflow prefer doing association in a type
9708 which wraps on overflow, if that is one of the operand types. */
9711 {
9719 }
9721 /* With undefined overflow we can only associate constants with one
9722 variable, and constants whose association doesn't overflow. */
9725 {
9727 {
9728 /* ??? If split_tree would handle NEGATE_EXPR we could
9729 simply reject these cases and the allowed cases would
9730 be the var0/minus_var1 ones. */
9736 {
9739 }
9746 {
9749 }
9755 /* The only case we can still associate with two variables
9756 is if they cancel out. */
9760 }
9766 }
9768 /* Only do something if we found more than two objects. Otherwise,
9769 nothing has changed and we risk infinite recursion. */
9777 {
9789 {
9793 }
9795 {
9799 }
9801 /* Preserve the MINUS_EXPR if the negative part of the literal is
9802 greater than the positive part. Otherwise, the multiplicative
9803 folding code (i.e extract_muldiv) may be fooled in case
9804 unsigned constants are subtracted, like in the following
9805 example: ((X*2 + 4) - 8U)/2. */
9807 {
9811 /* But avoid ending up with only negated parts. */
9813 {
9817 }
9818 else
9819 {
9823 }
9824 }
9826 /* Don't introduce overflows through reassociation. */
9831 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9838 /* Eliminate minus_con0. */
9840 {
9847 else
9850 }
9852 /* Eliminate minus_var0. */
9854 {
9858 else
9861 }
9863 return
9866 }
9867 }
9873 /* Fold &a[i] - &a[j] to i-j. */
9878 {
9882 code
9886 }
9888 /* Further transformations are not for pointers. */
9892 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9895 /* If arg0 is e.g. unsigned int and type is int, then this could
9896 introduce UB, because if A is INT_MIN at runtime, the original
9897 expression can be well defined while the latter is not.
9898 See PR83269. */
9907 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9908 __complex__ ( x, -y ). This is not the same for SNaNs or if
9909 signed zeros are involved. */
9913 {
9920 {
9924 {
9926 arg1r ? arg1r
9931 }
9933 {
9937 arg1i ? arg1i
9940 }
9941 }
9942 }
9944 /* A - B -> A + (-B) if B is easily negatable. */
9948 /* Avoid this transformation if B is a positive REAL_CST. */
9956 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9957 one. Make sure the type is not saturating and has the signedness of
9958 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9959 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9966 {
9970 }
9976 {
9977 /* Transform x * -C into -x * C if x is easily negatable. */
9992 {
9995 "occur when simplifying "
9997 WARN_STRICT_OVERFLOW_MISC);
9999 }
10001 /* Optimize z * conj(z) for integer complex numbers. */
10008 }
10009 else
10010 {
10011 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10012 This is not the same for NaNs or if signed zeros are
10013 involved. */
10019 {
10022 return
10028 return
10033 }
10035 /* Optimize z * conj(z) for floating point complex numbers.
10036 Guarded by flag_unsafe_math_optimizations as non-finite
10037 imaginary components don't produce scalar results. */
10046 }
10050 /* Canonicalize (X & C1) | C2. */
10054 {
10059 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10067 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10069 {
10072 }
10074 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10075 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10076 mode which allows further optimizations. */
10081 {
10086 {
10089 }
10090 }
10093 {
10098 }
10099 }
10101 /* See if this can be simplified into a rotate first. If that
10102 is unsuccessful continue in the association code. */
10106 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10114 /* See if this can be simplified into a rotate first. If that
10115 is unsuccessful continue in the association code. */
10119 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10124 {
10125 tree tem2;
10132 }
10133 /* Fold ~X & 1 as (X & 1) == 0. */
10137 {
10138 tree tem2;
10145 }
10146 /* Fold !X & 1 as X == 0. */
10149 {
10153 }
10155 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10156 multiple of 1 << CST. */
10158 {
10165 }
10167 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10168 bits from CST2. */
10172 {
10174 wide_int masked
10181 {
10182 /* Avoid the transform if arg1 is a mask of some
10183 mode which allows further optimizations. */
10190 }
10191 }
10193 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10194 ((A & N) + B) & M -> (A + B) & M
10195 Similarly if (N & M) == 0,
10196 ((A | N) + B) & M -> (A + B) & M
10197 and for - instead of + (or unary - instead of +)
10198 and/or ^ instead of |.
10199 If B is constant and (B & M) == 0, fold into A & M. */
10201 {
10210 {
10213 wide_int cst0;
10215 /* Now we know that arg0 is (C + D) or (C - D) or
10216 -C and arg1 (M) is == (1LL << cst) - 1.
10217 Store C into PMOP[0] and D into PMOP[1]. */
10221 {
10224 }
10231 {
10240 {
10243 }
10246 /* If C or D is of the form (A & N) where
10247 (N & M) == M, or of the form (A | N) or
10248 (A ^ N) where (N & M) == 0, replace it with A. */
10252 /* If C or D is a N where (N & M) == 0, it can be
10253 omitted (assumed 0). */
10261 }
10263 /* Only build anything new if we optimized one or both arguments
10264 above. */
10268 {
10271 {
10272 /* Perform the operations in a type that has defined
10273 overflow behavior. */
10279 }
10284 {
10292 else
10294 }
10297 else
10300 /* TEM is now the new binary +, - or unary - replacement. */
10304 }
10305 }
10306 }
10308 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10311 {
10316 return
10318 }
10323 /* Don't touch a floating-point divide by zero unless the mode
10324 of the constant can represent infinity. */
10330 /* (-A) / (-B) -> A / B */
10342 /* Fall through */
10345 /* Simplify A / (B << N) where A and B are positive and B is
10346 a power of 2, to A >> (N + log2(B)). */
10351 {
10354 {
10362 WARN_STRICT_OVERFLOW_MISC);
10368 }
10369 }
10371 /* Fall through */
10379 /* Convert -A / -B to A / B when the type is signed and overflow is
10380 undefined. */
10384 {
10387 "when distributing negation across "
10389 WARN_STRICT_OVERFLOW_MISC);
10394 }
10398 {
10401 "when distributing negation across "
10403 WARN_STRICT_OVERFLOW_MISC);
10408 }
10410 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10411 operation, EXACT_DIV_EXPR.
10413 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10414 At one time others generated faster code, it's not clear if they do
10415 after the last round to changes to the DIV code in expmed.c. */
10426 {
10430 WARN_STRICT_OVERFLOW_MISC);
10432 }
10444 {
10448 WARN_STRICT_OVERFLOW_MISC);
10450 }
10458 /* Since negative shift count is not well-defined,
10459 don't try to compute it in the compiler. */
10465 /* If we have a rotate of a bit operation with the rotate count and
10466 the second operand of the bit operation both constant,
10467 permute the two operations. */
10473 {
10481 }
10483 /* Two consecutive rotates adding up to the some integer
10484 multiple of the precision of the type can be ignored. */
10500 /* Note that the operands of this must be ints
10501 and their values must be 0 or 1.
10502 ("true" is a fixed value perhaps depending on the language.) */
10503 /* If first arg is constant zero, return it. */
10506 /* FALLTHRU */
10508 /* If either arg is constant true, drop it. */
10512 /* Preserve sequence points. */
10515 /* If second arg is constant zero, result is zero, but first arg
10516 must be evaluated. */
10519 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10520 case will be handled here. */
10524 /* !X && X is always false. */
10528 /* X && !X is always false. */
10533 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10534 means A >= Y && A != MAX, but in this case we know that
10535 A < X <= MAX. */
10539 {
10547 }
10556 /* Note that the operands of this must be ints
10557 and their values must be 0 or true.
10558 ("true" is a fixed value perhaps depending on the language.) */
10559 /* If first arg is constant true, return it. */
10562 /* FALLTHRU */
10564 /* If either arg is constant zero, drop it. */
10568 /* Preserve sequence points. */
10571 /* If second arg is constant true, result is true, but we must
10572 evaluate first arg. */
10575 /* Likewise for first arg, but note this only occurs here for
10576 TRUTH_OR_EXPR. */
10580 /* !X || X is always true. */
10584 /* X || !X is always true. */
10589 /* (X && !Y) || (!X && Y) is X ^ Y */
10592 {
10609 }
10618 /* If the second arg is constant zero, drop it. */
10621 /* If the second arg is constant true, this is a logical inversion. */
10623 {
10626 }
10627 /* Identical arguments cancel to zero. */
10631 /* !X ^ X is always true. */
10636 /* X ^ !X is always true. */
10652 /* bool_var != 1 becomes !bool_var. */
10659 /* bool_var == 0 becomes !bool_var. */
10666 /* !exp != 0 becomes !exp */
10671 /* If this is an EQ or NE comparison with zero and ARG0 is
10672 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10673 two operations, but the latter can be done in one less insn
10674 on machines that have only two-operand insns or on which a
10675 constant cannot be the first operand. */
10678 {
10683 {
10690 arg1);
10691 }
10694 {
10701 arg1);
10702 }
10703 }
10705 /* If this is an NE or EQ comparison of zero against the result of a
10706 signed MOD operation whose second operand is a power of 2, make
10707 the MOD operation unsigned since it is simpler and equivalent. */
10715 {
10725 }
10727 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10728 C1 is a valid shift constant, and C2 is a power of two, i.e.
10729 a single bit. */
10733 == INTEGER_CST
10736 {
10741 /* Check for a valid shift count. */
10743 {
10747 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10748 can be rewritten as (X & (C2 << C1)) != 0. */
10750 {
10755 }
10756 /* Otherwise, for signed (arithmetic) shifts,
10757 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10758 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10762 /* Otherwise, of unsigned (logical) shifts,
10763 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10764 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10765 else
10769 arg000);
10770 }
10771 }
10773 /* If this is a comparison of a field, we may be able to simplify it. */
10776 /* Handle the constant case even without -O
10777 to make sure the warnings are given. */
10779 {
10783 }
10785 /* Optimize comparisons of strlen vs zero to a compare of the
10786 first character of the string vs zero. To wit,
10787 strlen(ptr) == 0 => *ptr == 0
10788 strlen(ptr) != 0 => *ptr != 0
10789 Other cases should reduce to one of these two (or a constant)
10790 due to the return value of strlen being unsigned. */
10793 {
10801 {
10806 }
10807 }
10809 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10810 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10814 {
10819 {
10821 {
10824 }
10827 }
10828 }
10830 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10831 (X & C) == 0 when C is a single bit. */
10836 {
10843 arg1));
10844 }
10846 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10847 constant C is a power of two, i.e. a single bit. */
10854 {
10858 }
10860 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10861 when is C is a power of two, i.e. a single bit. */
10868 {
10874 }
10878 {
10881 }
10883 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10886 {
10894 {
10900 }
10902 {
10908 }
10910 {
10916 }
10918 {
10924 }
10925 }
10929 {
10936 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10937 operand_equal_p guarantees no side-effects so we don't need
10938 to use omit_one_operand on Z. */
10942 arg10));
10946 arg11));
10950 arg10));
10954 arg11));
10956 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10959 {
10965 }
10966 }
10968 /* Attempt to simplify equality/inequality comparisons of complex
10969 values. Only lower the comparison if the result is known or
10970 can be simplified to a single scalar comparison. */
10975 {
10980 {
10983 }
10984 else
10985 {
10988 }
10991 {
10994 }
10995 else
10996 {
10999 }
11003 {
11005 {
11010 }
11011 else
11012 {
11017 }
11018 }
11022 {
11024 {
11029 }
11030 else
11031 {
11036 }
11037 }
11038 }
11050 /* Transform comparisons of the form X +- C CMP X. */
11055 {
11060 /* (X - c) > X becomes false. */
11066 /* Likewise (X + c) < X becomes false. */
11072 /* Convert (X - c) <= X to true. */
11079 /* Convert (X + c) >= X to true. */
11085 }
11087 /* If we are comparing an ABS_EXPR with a constant, we can
11088 convert all the cases into explicit comparisons, but they may
11089 well not be faster than doing the ABS and one comparison.
11090 But ABS (X) <= C is a range comparison, which becomes a subtraction
11091 and a comparison, and is probably faster. */
11105 /* Convert ABS_EXPR<x> >= 0 to true. */
11112 {
11115 "when simplifying comparison of "
11117 WARN_STRICT_OVERFLOW_CONDITIONAL);
11120 arg0);
11121 }
11123 /* Convert ABS_EXPR<x> < 0 to false. */
11128 {
11131 "when simplifying comparison of "
11133 WARN_STRICT_OVERFLOW_CONDITIONAL);
11136 arg0);
11137 }
11139 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11140 and similarly for >= into !=. */
11150 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11151 otherwise Y might be >= # of bits in X's type and thus e.g.
11152 (unsigned char) (1 << Y) for Y 15 might be 0.
11153 If the cast is widening, then 1 << Y should have unsigned type,
11154 otherwise if Y is number of bits in the signed shift type minus 1,
11155 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11156 31 might be 0xffffffff80000000. */
11167 {
11173 }
11185 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11186 {
11198 }
11203 /* When pedantic, a compound expression can be neither an lvalue
11204 nor an integer constant expression. */
11207 /* Don't let (0, 0) be null pointer constant. */
11213 /* An ASSERT_EXPR should never be passed to fold_binary. */
11219 }
11221 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11222 a LABEL_EXPR; otherwise return NULL_TREE. Do not check the subtrees
11223 of GOTO_EXPR. */
11225 static tree
11227 {
11229 {
11236 /* fall through */
11240 }
11241 }
11243 /* Return whether the sub-tree ST contains a label which is accessible from
11244 outside the sub-tree. */
11246 static bool
11248 {
11249 return
11251 }
11253 /* Fold a ternary expression of code CODE and type TYPE with operands
11254 OP0, OP1, and OP2. Return the folded expression if folding is
11255 successful. Otherwise, return NULL_TREE. */
11257 tree
11260 {
11261 tree tem;
11268 /* If this is a commutative operation, and OP0 is a constant, move it
11269 to OP1 to reduce the number of tests below. */
11278 /* Strip any conversions that don't change the mode. This is safe
11279 for every expression, except for a comparison expression because
11280 its signedness is derived from its operands. So, in the latter
11281 case, only strip conversions that don't change the signedness.
11283 Note that this is done as an internal manipulation within the
11284 constant folder, in order to find the simplest representation of
11285 the arguments so that their form can be studied. In any cases,
11286 the appropriate type conversions should be put back in the tree
11287 that will get out of the constant folder. */
11289 {
11292 }
11295 {
11298 }
11301 {
11304 }
11307 {
11311 {
11317 }
11322 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11323 so all simple results must be passed through pedantic_non_lvalue. */
11325 {
11328 /* Only optimize constant conditions when the selected branch
11329 has the same type as the COND_EXPR. This avoids optimizing
11330 away "c ? x : throw", where the throw has a void type.
11331 Avoid throwing away that operand which contains label. */
11338 }
11340 {
11345 {
11350 {
11358 }
11362 }
11363 }
11365 /* If we have A op B ? A : C, we may be able to convert this to a
11366 simpler expression, depending on the operation and the values
11367 of B and C. Signed zeros prevent all of these transformations,
11368 for reasons given above each one.
11370 Also try swapping the arguments and inverting the conditional. */
11374 {
11378 }
11383 {
11387 {
11391 }
11392 }
11394 /* If the second operand is simpler than the third, swap them
11395 since that produces better jump optimization results. */
11398 {
11400 /* See if this can be inverted. If it can't, possibly because
11401 it was a floating-point inequality comparison, don't do
11402 anything. */
11406 }
11408 /* Convert A ? 1 : 0 to simply A. */
11413 /* If we try to convert OP0 to our type, the
11414 call to fold will try to move the conversion inside
11415 a COND, which will recurse. In that case, the COND_EXPR
11416 is probably the best choice, so leave it alone. */
11420 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11421 over COND_EXPR in cases such as floating point comparisons. */
11430 arg0)));
11432 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11437 {
11438 /* sign_bit_p looks through both zero and sign extensions,
11439 but for this optimization only sign extensions are
11440 usable. */
11443 {
11446 {
11449 }
11451 }
11452 /* sign_bit_p only checks ARG1 bits within A's precision.
11453 If <sign bit of A> has wider type than A, bits outside
11454 of A's precision in <sign bit of A> need to be checked.
11455 If they are all 0, this optimization needs to be done
11456 in unsigned A's type, if they are all 1 in signed A's type,
11457 otherwise this can't be done. */
11463 {
11465 tree tem_type;
11478 {
11481 }
11483 {
11486 }
11487 else
11489 }
11492 return
11498 arg1)));
11499 }
11501 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11502 already handled above. */
11507 {
11517 op1);
11518 }
11520 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11521 is probably obsolete because the first operand should be a
11522 truth value (that's why we have the two cases above), but let's
11523 leave it in until we can confirm this for all front-ends. */
11535 /* Disable the transformations below for vectors, since
11536 fold_binary_op_with_conditional_arg may undo them immediately,
11537 yielding an infinite loop. */
11541 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11550 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11555 {
11557 /* Only perform transformation if ARG0 is easily inverted. */
11561 ? BIT_IOR_EXPR
11564 op1);
11565 }
11567 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11572 {
11574 /* Only perform transformation if ARG0 is easily inverted. */
11580 op2);
11581 }
11583 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11595 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11596 of fold_ternary on them. */
11604 {
11614 {
11619 {
11627 }
11628 }
11629 }
11631 /* On constants we can use native encode/interpret to constant
11632 fold (nearly) all BIT_FIELD_REFs. */
11636 {
11639 /* Limit us to a reasonable amount of work. To relax the
11640 other limitations we need bit-shifting of the buffer
11641 and rounding up the size. */
11645 {
11647 unsigned HOST_WIDE_INT len
11652 {
11657 }
11658 }
11659 }
11664 /* For integers we can decompose the FMA if possible. */
11676 {
11692 {
11697 /* Make sure that the perm value is in an acceptable
11698 range. */
11707 else
11715 }
11718 {
11723 }
11728 {
11733 }
11739 {
11743 }
11748 /* Some targets are deficient and fail to expand a single
11749 argument permutation while still allowing an equivalent
11750 2-argument version. */
11754 {
11757 }
11760 {
11767 }
11771 }
11775 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11778 {
11784 wide_int tem2
11788 }
11793 {
11795 unsigned HOST_WIDE_INT elsize
11798 {
11802 else
11803 {
11810 }
11811 }
11812 }
11818 }
11820 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11821 of an array (or vector). */
11823 tree
11825 {
11830 {
11833 {
11834 /* Static constructors for variably sized objects makes no sense. */
11838 }
11839 }
11850 offset_int max_index;
11855 {
11856 /* Array constructor might explicitly set index, or specify a range,
11857 or leave index NULL meaning that it is next index after previous
11858 one. */
11860 {
11863 else
11864 {
11868 }
11869 }
11870 else
11871 {
11877 }
11879 /* Do we have match? */
11883 }
11885 }
11887 /* Perform constant folding and related simplification of EXPR.
11888 The related simplifications include x*1 => x, x*0 => 0, etc.,
11889 and application of the associative law.
11890 NOP_EXPR conversions may be removed freely (as long as we
11891 are careful not to change the type of the overall expression).
11892 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11893 but we can constant-fold them if they have constant operands. */
11895 #ifdef ENABLE_FOLD_CHECKING
11896 # define fold(x) fold_1 (x)
11898 static
11899 #endif
11900 tree
11902 {
11906 tree tem;
11909 /* Return right away if a constant. */
11913 /* CALL_EXPR-like objects with variable numbers of operands are
11914 treated specially. */
11916 {
11918 {
11921 }
11923 }
11926 {
11931 {
11949 }
11950 }
11953 {
11955 {
11962 {
11967 }
11970 }
11972 /* Return a VECTOR_CST if possible. */
11974 {
11980 tree val;
11986 }
11994 }
11996 #ifdef ENABLE_FOLD_CHECKING
11997 #undef fold
12004 /* When --enable-checking=fold, compute a digest of expr before
12005 and after actual fold call to see if fold did not accidentally
12006 change original expr. */
12008 tree
12010 {
12011 tree ret;
12031 }
12033 void
12035 {
12046 }
12048 static void
12050 {
12052 }
12054 static void
12057 {
12063 recursive_label:
12073 {
12074 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12079 }
12087 {
12088 /* Allow these fields to be modified. */
12089 tree tmp;
12098 {
12101 }
12102 }
12113 {
12116 {
12132 }
12136 {
12149 }
12166 {
12172 }
12175 {
12177 {
12180 }
12182 }
12193 {
12196 }
12206 }
12207 }
12209 /* Helper function for outputting the checksum of a tree T. When
12210 debugging with gdb, you can "define mynext" to be "next" followed
12211 by "call debug_fold_checksum (op0)", then just trace down till the
12212 outputs differ. */
12214 DEBUG_FUNCTION void
12216 {
12231 }
12233 #endif
12235 /* Fold a unary tree expression with code CODE of type TYPE with an
12236 operand OP0. LOC is the location of the resulting expression.
12237 Return a folded expression if successful. Otherwise, return a tree
12238 expression with code CODE of type TYPE with an operand OP0. */
12240 tree
12243 {
12244 tree tem;
12245 #ifdef ENABLE_FOLD_CHECKING
12254 #endif
12260 #ifdef ENABLE_FOLD_CHECKING
12267 #endif
12269 }
12271 /* Fold a binary tree expression with code CODE of type TYPE with
12272 operands OP0 and OP1. LOC is the location of the resulting
12273 expression. Return a folded expression if successful. Otherwise,
12274 return a tree expression with code CODE of type TYPE with operands
12275 OP0 and OP1. */
12277 tree
12280 MEM_STAT_DECL)
12281 {
12282 tree tem;
12283 #ifdef ENABLE_FOLD_CHECKING
12300 #endif
12306 #ifdef ENABLE_FOLD_CHECKING
12321 #endif
12323 }
12325 /* Fold a ternary tree expression with code CODE of type TYPE with
12326 operands OP0, OP1, and OP2. Return a folded expression if
12327 successful. Otherwise, return a tree expression with code CODE of
12328 type TYPE with operands OP0, OP1, and OP2. */
12330 tree
12333 {
12334 tree tem;
12335 #ifdef ENABLE_FOLD_CHECKING
12359 #endif
12366 #ifdef ENABLE_FOLD_CHECKING
12389 #endif
12391 }
12393 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12394 arguments in ARGARRAY, and a null static chain.
12395 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12396 of type TYPE from the given operands as constructed by build_call_array. */
12398 tree
12401 {
12402 tree tem;
12403 #ifdef ENABLE_FOLD_CHECKING
12422 #endif
12428 #ifdef ENABLE_FOLD_CHECKING
12444 #endif
12446 }
12448 /* Perform constant folding and related simplification of initializer
12449 expression EXPR. These behave identically to "fold_buildN" but ignore
12450 potential run-time traps and exceptions that fold must preserve. */
12452 #define START_FOLD_INIT \
12453 int saved_signaling_nans = flag_signaling_nans;\
12454 int saved_trapping_math = flag_trapping_math;\
12455 int saved_rounding_math = flag_rounding_math;\
12456 int saved_trapv = flag_trapv;\
12457 int saved_folding_initializer = folding_initializer;\
12458 flag_signaling_nans = 0;\
12459 flag_trapping_math = 0;\
12460 flag_rounding_math = 0;\
12461 flag_trapv = 0;\
12462 folding_initializer = 1;
12464 #define END_FOLD_INIT \
12465 flag_signaling_nans = saved_signaling_nans;\
12466 flag_trapping_math = saved_trapping_math;\
12467 flag_rounding_math = saved_rounding_math;\
12468 flag_trapv = saved_trapv;\
12469 folding_initializer = saved_folding_initializer;
12471 tree
12474 {
12475 tree result;
12476 START_FOLD_INIT;
12480 END_FOLD_INIT;
12482 }
12484 tree
12487 {
12488 tree result;
12489 START_FOLD_INIT;
12493 END_FOLD_INIT;
12495 }
12497 tree
12500 {
12501 tree result;
12502 START_FOLD_INIT;
12506 END_FOLD_INIT;
12508 }
12510 #undef START_FOLD_INIT
12511 #undef END_FOLD_INIT
12513 /* Determine if first argument is a multiple of second argument. Return 0 if
12514 it is not, or we cannot easily determined it to be.
12516 An example of the sort of thing we care about (at this point; this routine
12517 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12518 fold cases do now) is discovering that
12520 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12522 is a multiple of
12524 SAVE_EXPR (J * 8)
12526 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12528 This code also handles discovering that
12530 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12532 is a multiple of 8 so we don't have to worry about dealing with a
12533 possible remainder.
12535 Note that we *look* inside a SAVE_EXPR only to determine how it was
12536 calculated; it is not safe for fold to do much of anything else with the
12537 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12538 at run time. For example, the latter example above *cannot* be implemented
12539 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12540 evaluation time of the original SAVE_EXPR is not necessarily the same at
12541 the time the new expression is evaluated. The only optimization of this
12542 sort that would be valid is changing
12544 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12546 divided by 8 to
12548 SAVE_EXPR (I) * SAVE_EXPR (J)
12550 (where the same SAVE_EXPR (J) is used in the original and the
12551 transformed version). */
12553 int
12555 {
12566 {
12568 /* Bitwise and provides a power of two multiple. If the mask is
12569 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12572 /* FALLTHRU */
12579 /* It is impossible to prove if op0 - op1 is multiple of bottom
12580 precisely, so be conservative here checking if both op0 and op1
12581 are multiple of bottom. Note we check the second operand first
12582 since it's usually simpler. */
12587 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12588 as op0 - 3 if the expression has unsigned type. For example,
12589 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12599 {
12601 /* const_binop may not detect overflow correctly,
12602 so check for it explicitly here. */
12610 }
12614 /* Can't handle conversions from non-integral or wider integral type. */
12620 /* fall through */
12637 SIGNED);
12643 {
12646 /* Check for special cases to see if top is defined as multiple
12647 of bottom:
12649 top = (X & ~(bottom - 1) ; bottom is power of 2
12651 or
12653 Y = X % bottom
12654 top = X - Y. */
12673 }
12675 /* fall through */
12683 }
12684 }
12686 #define tree_expr_nonnegative_warnv_p(X, Y) \
12689 #define RECURSE(X) \
12690 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12692 /* Return true if CODE or TYPE is known to be non-negative. */
12694 static bool
12696 {
12699 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12700 have a signed:1 type (where the value is -1 and 0). */
12703 }
12705 /* Return true if (CODE OP0) is known to be non-negative. If the return
12706 value is based on the assumption that signed overflow is undefined,
12707 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12708 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12710 bool
12713 {
12718 {
12720 /* We can't return 1 if flag_wrapv is set because
12721 ABS_EXPR<INT_MIN> = INT_MIN. */
12725 {
12728 }
12736 CASE_CONVERT:
12737 {
12742 {
12746 {
12750 }
12751 }
12753 {
12759 }
12760 }
12765 }
12767 /* We don't know sign of `t', so be conservative and return false. */
12769 }
12771 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12772 value is based on the assumption that signed overflow is undefined,
12773 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12774 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12776 bool
12780 {
12785 {
12791 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12792 both unsigned and at least 2 bits shorter than the result. */
12796 {
12801 {
12805 }
12806 }
12811 {
12812 /* x * x is always non-negative for floating point x
12813 or without overflow. */
12816 {
12821 }
12822 }
12824 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12825 both unsigned and their total bits is shorter than the result. */
12829 {
12848 {
12858 }
12859 }
12886 }
12888 /* We don't know sign of `t', so be conservative and return false. */
12890 }
12892 /* Return true if T is known to be non-negative. If the return
12893 value is based on the assumption that signed overflow is undefined,
12894 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12895 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12897 bool
12899 {
12904 {
12918 /* Limit the depth of recursion to avoid quadratic behavior.
12919 This is expected to catch almost all occurrences in practice.
12920 If this code misses important cases that unbounded recursion
12921 would not, passes that need this information could be revised
12922 to provide it through dataflow propagation. */
12930 }
12931 }
12933 /* Return true if T is known to be non-negative. If the return
12934 value is based on the assumption that signed overflow is undefined,
12935 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12936 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12938 bool
12941 {
12943 {
12944 CASE_CFN_ACOS:
12945 CASE_CFN_ACOSH:
12946 CASE_CFN_CABS:
12947 CASE_CFN_COSH:
12948 CASE_CFN_ERFC:
12949 CASE_CFN_EXP:
12950 CASE_CFN_EXP10:
12951 CASE_CFN_EXP2:
12952 CASE_CFN_FABS:
12953 CASE_CFN_FDIM:
12954 CASE_CFN_HYPOT:
12955 CASE_CFN_POW10:
12956 CASE_CFN_FFS:
12957 CASE_CFN_PARITY:
12958 CASE_CFN_POPCOUNT:
12959 CASE_CFN_CLZ:
12960 CASE_CFN_CLRSB:
12963 /* Always true. */
12966 CASE_CFN_SQRT:
12967 CASE_CFN_SQRT_FN:
12968 /* sqrt(-0.0) is -0.0. */
12973 CASE_CFN_ASINH:
12974 CASE_CFN_ATAN:
12975 CASE_CFN_ATANH:
12976 CASE_CFN_CBRT:
12977 CASE_CFN_CEIL:
12978 CASE_CFN_ERF:
12979 CASE_CFN_EXPM1:
12980 CASE_CFN_FLOOR:
12981 CASE_CFN_FMOD:
12982 CASE_CFN_FREXP:
12983 CASE_CFN_ICEIL:
12984 CASE_CFN_IFLOOR:
12985 CASE_CFN_IRINT:
12986 CASE_CFN_IROUND:
12987 CASE_CFN_LCEIL:
12988 CASE_CFN_LDEXP:
12989 CASE_CFN_LFLOOR:
12990 CASE_CFN_LLCEIL:
12991 CASE_CFN_LLFLOOR:
12992 CASE_CFN_LLRINT:
12993 CASE_CFN_LLROUND:
12994 CASE_CFN_LRINT:
12995 CASE_CFN_LROUND:
12996 CASE_CFN_MODF:
12997 CASE_CFN_NEARBYINT:
12998 CASE_CFN_RINT:
12999 CASE_CFN_ROUND:
13000 CASE_CFN_SCALB:
13001 CASE_CFN_SCALBLN:
13002 CASE_CFN_SCALBN:
13003 CASE_CFN_SIGNBIT:
13004 CASE_CFN_SIGNIFICAND:
13005 CASE_CFN_SINH:
13006 CASE_CFN_TANH:
13007 CASE_CFN_TRUNC:
13008 /* True if the 1st argument is nonnegative. */
13011 CASE_CFN_FMAX:
13012 CASE_CFN_FMAX_FN:
13013 /* True if the 1st OR 2nd arguments are nonnegative. */
13016 CASE_CFN_FMIN:
13017 CASE_CFN_FMIN_FN:
13018 /* True if the 1st AND 2nd arguments are nonnegative. */
13021 CASE_CFN_COPYSIGN:
13022 CASE_CFN_COPYSIGN_FN:
13023 /* True if the 2nd argument is nonnegative. */
13026 CASE_CFN_POWI:
13027 /* True if the 1st argument is nonnegative or the second
13028 argument is an even integer. */
13034 CASE_CFN_POW:
13035 /* True if the 1st argument is nonnegative or the second
13036 argument is an even integer valued real. */
13038 {
13039 REAL_VALUE_TYPE c;
13040 HOST_WIDE_INT n;
13045 {
13046 REAL_VALUE_TYPE cint;
13050 }
13051 }
13056 }
13058 }
13060 /* Return true if T is known to be non-negative. If the return
13061 value is based on the assumption that signed overflow is undefined,
13062 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13063 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13065 static bool
13067 {
13073 {
13075 {
13079 /* If the initializer is non-void, then it's a normal expression
13080 that will be assigned to the slot. */
13084 /* Otherwise, the initializer sets the slot in some way. One common
13085 way is an assignment statement at the end of the initializer. */
13087 {
13095 else
13097 }
13103 }
13106 {
13112 arg0,
13113 arg1,
13115 }
13128 }
13129 }
13131 #undef RECURSE
13132 #undef tree_expr_nonnegative_warnv_p
13134 /* Return true if T is known to be non-negative. If the return
13135 value is based on the assumption that signed overflow is undefined,
13136 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13137 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13139 bool
13141 {
13148 {
13170 }
13173 {
13199 }
13200 }
13202 /* Return true if `t' is known to be non-negative. Handle warnings
13203 about undefined signed overflow. */
13205 bool
13207 {
13214 "determining that expression is always "
13216 WARN_STRICT_OVERFLOW_MISC);
13218 }
13221 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13222 For floating point we further ensure that T is not denormal.
13223 Similar logic is present in nonzero_address in rtlanal.h.
13225 If the return value is based on the assumption that signed overflow
13226 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13227 change *STRICT_OVERFLOW_P. */
13229 bool
13232 {
13234 {
13237 strict_overflow_p);
13240 {
13246 strict_overflow_p));
13247 }
13252 strict_overflow_p);
13256 }
13259 }
13261 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13262 For floating point we further ensure that T is not denormal.
13263 Similar logic is present in nonzero_address in rtlanal.h.
13265 If the return value is based on the assumption that signed overflow
13266 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13267 change *STRICT_OVERFLOW_P. */
13269 bool
13271 tree type,
13272 tree op0,
13274 {
13277 {
13281 {
13282 /* With the presence of negative values it is hard
13283 to say something. */
13290 /* One of operands must be positive and the other non-negative. */
13291 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13292 overflows, on a twos-complement machine the sum of two
13293 nonnegative numbers can never be zero. */
13295 strict_overflow_p)
13297 strict_overflow_p));
13298 }
13303 {
13305 strict_overflow_p)
13307 strict_overflow_p))
13308 {
13311 }
13312 }
13321 {
13324 }
13331 {
13335 /* When both operands are nonzero, then MAX must be too. */
13337 strict_overflow_p))
13340 /* MAX where operand 0 is positive is positive. */
13342 strict_overflow_p);
13343 }
13344 /* MAX where operand 1 is positive is positive. */
13349 {
13353 }
13358 strict_overflow_p)
13360 strict_overflow_p));
13364 }
13367 }
13369 /* Return true when T is an address and is known to be nonzero.
13370 For floating point we further ensure that T is not denormal.
13371 Similar logic is present in nonzero_address in rtlanal.h.
13373 If the return value is based on the assumption that signed overflow
13374 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13375 change *STRICT_OVERFLOW_P. */
13377 bool
13379 {
13382 {
13387 {
13399 /* For objects in symbol table check if we know they are non-zero.
13400 Don't do anything for variables and functions before symtab is built;
13401 it is quite possible that they will be declared weak later. */
13406 /* Constants are never weak. */
13411 }
13419 {
13423 }
13433 }
13435 }
13437 #define integer_valued_real_p(X) \
13440 #define RECURSE(X) \
13441 ((integer_valued_real_p) (X, depth + 1))
13443 /* Return true if the floating point result of (CODE OP0) has an
13444 integer value. We also allow +Inf, -Inf and NaN to be considered
13445 integer values. Return false for signaling NaN.
13447 DEPTH is the current nesting depth of the query. */
13449 bool
13451 {
13453 {
13460 CASE_CONVERT:
13461 {
13468 }
13472 }
13474 }
13476 /* Return true if the floating point result of (CODE OP0 OP1) has an
13477 integer value. We also allow +Inf, -Inf and NaN to be considered
13478 integer values. Return false for signaling NaN.
13480 DEPTH is the current nesting depth of the query. */
13482 bool
13484 {
13486 {
13496 }
13498 }
13500 /* Return true if the floating point result of calling FNDECL with arguments
13501 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13502 considered integer values. Return false for signaling NaN. If FNDECL
13503 takes fewer than 2 arguments, the remaining ARGn are null.
13505 DEPTH is the current nesting depth of the query. */
13507 bool
13509 {
13511 {
13512 CASE_CFN_CEIL:
13513 CASE_CFN_FLOOR:
13514 CASE_CFN_NEARBYINT:
13515 CASE_CFN_RINT:
13516 CASE_CFN_ROUND:
13517 CASE_CFN_TRUNC:
13520 CASE_CFN_FMIN:
13521 CASE_CFN_FMIN_FN:
13522 CASE_CFN_FMAX:
13523 CASE_CFN_FMAX_FN:
13528 }
13530 }
13532 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13533 has an integer value. We also allow +Inf, -Inf and NaN to be
13534 considered integer values. Return false for signaling NaN.
13536 DEPTH is the current nesting depth of the query. */
13538 bool
13540 {
13542 {
13550 /* Limit the depth of recursion to avoid quadratic behavior.
13551 This is expected to catch almost all occurrences in practice.
13552 If this code misses important cases that unbounded recursion
13553 would not, passes that need this information could be revised
13554 to provide it through dataflow propagation. */
13558 depth));
13562 }
13564 }
13566 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13567 has an integer value. We also allow +Inf, -Inf and NaN to be
13568 considered integer values. Return false for signaling NaN.
13570 DEPTH is the current nesting depth of the query. */
13572 static bool
13574 {
13576 {
13587 }
13589 }
13591 #undef RECURSE
13592 #undef integer_valued_real_p
13594 /* Return true if the floating point expression T has an integer value.
13595 We also allow +Inf, -Inf and NaN to be considered integer values.
13596 Return false for signaling NaN.
13598 DEPTH is the current nesting depth of the query. */
13600 bool
13602 {
13608 {
13624 }
13627 {
13633 {
13642 }
13646 }
13647 }
13649 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13650 attempt to fold the expression to a constant without modifying TYPE,
13651 OP0 or OP1.
13653 If the expression could be simplified to a constant, then return
13654 the constant. If the expression would not be simplified to a
13655 constant, then return NULL_TREE. */
13657 tree
13659 {
13662 }
13664 /* Given the components of a unary expression CODE, TYPE and OP0,
13665 attempt to fold the expression to a constant without modifying
13666 TYPE or OP0.
13668 If the expression could be simplified to a constant, then return
13669 the constant. If the expression would not be simplified to a
13670 constant, then return NULL_TREE. */
13672 tree
13674 {
13677 }
13679 /* If EXP represents referencing an element in a constant string
13680 (either via pointer arithmetic or array indexing), return the
13681 tree representing the value accessed, otherwise return NULL. */
13683 tree
13685 {
13689 {
13691 tree index;
13692 tree string;
13697 else
13698 {
13702 /* Optimize the special-case of a zero lower bound.
13704 We convert the low_bound to sizetype to avoid some problems
13705 with constant folding. (E.g. suppose the lower bound is 1,
13706 and its mode is QI. Without the conversion,l (ARRAY
13707 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13708 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13714 }
13716 scalar_int_mode char_mode;
13728 }
13730 }
13732 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13733 an integer constant, real, or fixed-point constant.
13735 TYPE is the type of the result. */
13737 static tree
13739 {
13743 {
13749 {
13750 FIXED_VALUE_TYPE f;
13755 /* Propagate overflow flags. */
13759 }
13763 {
13770 }
13773 }
13776 }
13778 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13779 an integer constant or real constant.
13781 TYPE is the type of the result. */
13783 tree
13785 {
13789 {
13791 {
13792 /* If the value is unsigned or non-negative, then the absolute value
13793 is the same as the ordinary value. */
13797 /* If the value is negative, then the absolute value is
13798 its negation. */
13799 else
13800 {
13805 }
13806 }
13812 else
13818 }
13821 }
13823 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13824 constant. TYPE is the type of the result. */
13826 static tree
13828 {
13832 }
13834 /* Given CODE, a relational operator, the target type, TYPE and two
13835 constant operands OP0 and OP1, return the result of the
13836 relational operation. If the result is not a compile time
13837 constant, then return NULL_TREE. */
13839 static tree
13841 {
13844 /* From here on, the only cases we handle are when the result is
13845 known to be a constant. */
13848 {
13852 /* Handle the cases where either operand is a NaN. */
13854 {
13856 {
13884 }
13887 }
13890 }
13893 {
13897 }
13899 /* Handle equality/inequality of complex constants. */
13901 {
13912 else
13914 }
13917 {
13919 {
13920 /* Have vector comparison with scalar boolean result. */
13924 {
13932 }
13934 }
13935 tree_vector_builder elts;
13940 {
13953 }
13956 }
13958 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13960 To compute GT, swap the arguments and do LT.
13961 To compute GE, do LT and invert the result.
13962 To compute LE, swap the arguments, do LT and invert the result.
13963 To compute NE, do EQ and invert the result.
13965 Therefore, the code below must handle only EQ and LT. */
13968 {
13971 }
13973 /* Note that it is safe to invert for real values here because we
13974 have already handled the one case that it matters. */
13978 {
13981 }
13983 /* Compute a result for LT or EQ if args permit;
13984 Otherwise return T. */
13986 {
13989 else
13991 }
13992 else
13998 }
14000 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14001 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14002 itself. */
14004 tree
14006 {
14007 /* If the expression does not have side effects then we don't have to wrap
14008 it with a cleanup point expression. */
14012 /* If the expression is a return, check to see if the expression inside the
14013 return has no side effects or the right hand side of the modify expression
14014 inside the return. If either don't have side effects set we don't need to
14015 wrap the expression in a cleanup point expression. Note we don't check the
14016 left hand side of the modify because it should always be a return decl. */
14018 {
14025 }
14028 }
14030 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14031 of an indirection through OP0, or NULL_TREE if no simplification is
14032 possible. */
14034 tree
14036 {
14038 tree subtype;
14047 {
14050 /* *&CONST_DECL -> to the value of the const decl. */
14053 /* *&p => p; make sure to handle *&"str"[cst] here. */
14055 {
14059 else
14061 }
14062 /* *(foo *)&fooarray => fooarray[0] */
14065 && (!in_gimple_form
14067 {
14077 }
14078 /* *(foo *)&complexfoo => __real__ complexfoo */
14082 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14085 {
14089 }
14090 }
14094 {
14100 {
14101 tree op00type;
14105 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14108 {
14110 unsigned HOST_WIDE_INT max_offset
14115 {
14122 }
14123 }
14124 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14127 {
14131 }
14132 /* ((foo *)&fooarray)[1] => fooarray[1] */
14135 {
14142 offset_int remainder;
14145 {
14150 }
14151 }
14152 }
14153 }
14155 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14158 && (!in_gimple_form
14160 {
14161 tree type_domain;
14171 NULL_TREE);
14172 }
14175 }
14177 /* Builds an expression for an indirection through T, simplifying some
14178 cases. */
14180 tree
14182 {
14190 }
14192 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14194 tree
14196 {
14201 else
14203 }
14205 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14206 whose result is ignored. The type of the returned tree need not be
14207 the same as the original expression. */
14209 tree
14211 {
14217 {
14228 else
14234 {
14250 }
14255 }
14256 }
14258 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14260 tree
14262 {
14268 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14269 have to do anything. Only do this when we are not given a const,
14270 because in that case, this check is more expensive than just
14271 doing it. */
14273 {
14278 }
14280 /* If divisor is a power of two, simplify this to bit manipulation. */
14282 {
14284 {
14298 }
14299 else
14300 {
14301 tree t;
14307 }
14308 }
14309 else
14310 {
14315 }
14318 }
14320 /* Likewise, but round down. */
14322 tree
14324 {
14331 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14332 have to do anything. Only do this when we are not given a const,
14333 because in that case, this check is more expensive than just
14334 doing it. */
14336 {
14341 }
14343 /* If divisor is a power of two, simplify this to bit manipulation. */
14345 {
14346 tree t;
14350 }
14351 else
14352 {
14357 }
14360 }
14362 /* Returns the pointer to the base of the object addressed by EXP and
14363 extracts the information about the offset of the access, storing it
14364 to PBITPOS and POFFSET. */
14366 static tree
14369 {
14370 tree core;
14371 machine_mode mode;
14373 poly_int64 bitsize;
14377 {
14382 }
14384 {
14390 {
14391 poly_offset_int tem
14397 }
14398 }
14399 else
14400 {
14404 }
14407 }
14409 /* Returns true if addresses of E1 and E2 differ by a constant, false
14410 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14412 bool
14414 {
14429 {
14439 }
14441 {
14442 /* If only one of the offsets is non-constant, the difference cannot
14443 be a constant. */
14445 }
14446 else
14451 }
14453 /* Return OFF converted to a pointer offset type suitable as offset for
14454 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14455 tree
14457 {
14459 }
14461 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14462 tree
14464 {
14467 }
14469 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14470 tree
14472 {
14475 }
14477 /* Return a char pointer for a C string if it is a string constant
14478 or sum of string constant and integer constant. We only support
14479 string constants properly terminated with '\0' character.
14480 If STRLEN is a valid pointer, length (including terminating character)
14481 of returned string is stored to the argument. */
14485 {
14486 tree offset_node;
14497 {
14500 else
14502 }
14507 /* Support only properly null-terminated strings. */
14516 }
14518 #if CHECKING_P
14522 /* Helper functions for writing tests of folding trees. */
14524 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14526 static void
14528 tree constant)
14529 {
14531 }
14533 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14534 wrapping WRAPPED_EXPR. */
14536 static void
14538 tree wrapped_expr)
14539 {
14544 }
14546 /* Verify that various arithmetic binary operations are folded
14547 correctly. */
14549 static void
14551 {
14557 /* Addition. */
14558 /* 1 <-- (0 + 1) */
14560 one);
14562 one);
14564 /* (nonlvalue)x <-- (x + 0) */
14566 x);
14568 /* Subtraction. */
14569 /* 0 <-- (x - x) */
14571 zero);
14573 x);
14575 /* Multiplication. */
14576 /* 0 <-- (x * 0) */
14578 zero);
14580 /* (nonlvalue)x <-- (x * 1) */
14582 x);
14583 }
14585 /* Verify that various binary operations on vectors are folded
14586 correctly. */
14588 static void
14590 {
14596 /* Verify equality tests that return a scalar boolean result. */
14602 }
14604 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14606 static void
14608 {
14611 /* This will be 1 if VEC_MODE isn't a vector mode. */
14618 }
14620 /* Run all of the selftests within this file. */
14622 void
14624 {
14628 }