| blob | 744c3552ead8d1f9a912dcc42ef2bbf4ad0303ab |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
414 /* Steps don't prevent negation. */
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a (negative) power of two. */
464 /* Fall through. */
479 /* In general we can't negate B in A / B, because if A is INT_MIN and
480 B is 1, we may turn this into INT_MIN / -1 which is undefined
481 and actually traps on some architectures. */
490 /* Negate -((double)float) as (double)(-float). */
492 {
496 }
500 /* Negate -f(x) as f(-x). */
506 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
508 {
512 }
517 }
519 }
521 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
522 simplification is possible.
523 If negate_expr_p would return true for T, NULL_TREE will never be
524 returned. */
526 static tree
528 {
530 tree tem;
533 {
534 /* Convert - (~A) to A + 1. */
558 {
563 }
567 {
568 tree_vector_builder elts;
572 {
577 }
580 }
603 {
604 /* -(A + B) -> (-B) - A. */
606 {
610 }
612 /* -(A + B) -> (-A) - B. */
614 {
618 }
619 }
623 /* - (A - B) -> B - A */
634 /* Fall through. */
638 {
647 }
659 /* In general we can't negate B in A / B, because if A is INT_MIN and
660 B is 1, we may turn this into INT_MIN / -1 which is undefined
661 and actually traps on some architectures. */
673 /* Convert -((double)float) into (double)(-float). */
675 {
679 }
683 /* Negate -f(x) as f(-x). */
686 {
692 }
696 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
698 {
701 {
708 }
709 }
714 }
717 }
719 /* A wrapper for fold_negate_expr_1. */
721 static tree
723 {
730 }
732 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
733 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
734 return NULL_TREE. */
736 static tree
738 {
740 location_t loc;
753 }
754 \f
755 /* Split a tree IN into a constant, literal and variable parts that could be
756 combined with CODE to make IN. "constant" means an expression with
757 TREE_CONSTANT but that isn't an actual constant. CODE must be a
758 commutative arithmetic operation. Store the constant part into *CONP,
759 the literal in *LITP and return the variable part. If a part isn't
760 present, set it to null. If the tree does not decompose in this way,
761 return the entire tree as the variable part and the other parts as null.
763 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
764 case, we negate an operand that was subtracted. Except if it is a
765 literal for which we use *MINUS_LITP instead.
767 If NEGATE_P is true, we are negating all of IN, again except a literal
768 for which we use *MINUS_LITP instead. If a variable part is of pointer
769 type, it is negated after converting to TYPE. This prevents us from
770 generating illegal MINUS pointer expression. LOC is the location of
771 the converted variable part.
773 If IN is itself a literal or constant, return it as appropriate.
775 Note that we do not guarantee that any of the three values will be the
776 same type as IN, but they will have the same signedness and mode. */
778 static tree
782 {
790 /* Strip any conversions that don't change the machine mode or signedness. */
799 /* We can associate addition and subtraction together (even
800 though the C standard doesn't say so) for integers because
801 the value is not affected. For reals, the value might be
802 affected, so we can't. */
808 {
814 /* First see if either of the operands is a literal, then a constant. */
827 /* If we haven't dealt with either operand, this is not a case we can
828 decompose. Otherwise, VAR is either of the ones remaining, if any. */
833 else
836 /* Now do any needed negations. */
843 }
848 {
849 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
850 when IN is constant. */
853 }
854 else
858 {
871 }
881 }
883 /* Re-associate trees split by the above function. T1 and T2 are
884 either expressions to associate or null. Return the new
885 expression, if any. LOC is the location of the new expression. If
886 we build an operation, do it in TYPE and with CODE. */
888 static tree
890 {
892 {
895 }
899 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
900 try to fold this since we will have infinite recursion. But do
901 deal with any NEGATE_EXPRs. */
905 {
907 {
920 }
922 {
925 }
929 }
933 }
934 \f
935 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
936 for use in int_const_binop, size_binop and size_diffop. */
938 static bool
940 {
947 {
956 }
961 }
963 /* Subroutine of int_const_binop_1 that handles two INTEGER_CSTs. */
965 static tree
968 {
969 wide_int res;
970 tree t;
979 {
995 {
999 else
1001 }
1004 /* It's unclear from the C standard whether shifts can overflow.
1005 The following code ignores overflow; perhaps a C standard
1006 interpretation ruling is needed. */
1008 else
1015 {
1019 else
1021 }
1025 else
1104 }
1112 }
1114 /* Combine two integer constants PARG1 and PARG2 under operation CODE
1115 to produce a new constant. Return NULL_TREE if we don't know how
1116 to evaluate CODE at compile-time. */
1118 static tree
1121 {
1128 {
1129 poly_wide_int res;
1134 {
1152 else
1159 else
1172 }
1177 }
1180 }
1182 tree
1184 {
1186 }
1188 /* Return true if binary operation OP distributes over addition in operand
1189 OPNO, with the other operand being held constant. OPNO counts from 1. */
1191 static bool
1193 {
1195 {
1206 }
1207 }
1209 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1210 constant. We assume ARG1 and ARG2 have the same data type, or at least
1211 are the same kind of constant and the same machine mode. Return zero if
1212 combining the constants is not allowed in the current operating mode. */
1214 static tree
1216 {
1217 /* Sanity check for the recursive cases. */
1225 {
1231 }
1234 {
1235 machine_mode mode;
1236 REAL_VALUE_TYPE d1;
1237 REAL_VALUE_TYPE d2;
1238 REAL_VALUE_TYPE value;
1239 REAL_VALUE_TYPE result;
1243 /* The following codes are handled by real_arithmetic. */
1245 {
1256 }
1264 /* Don't perform operation if we honor signaling NaNs and
1265 either operand is a signaling NaN. */
1271 /* Don't perform operation if it would raise a division
1272 by zero exception. */
1278 /* If either operand is a NaN, just return it. Otherwise, set up
1279 for floating-point trap; we return an overflow. */
1281 {
1282 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1283 is off. */
1287 }
1289 {
1290 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1291 is off. */
1295 }
1300 /* Don't constant fold this floating point operation if
1301 the result has overflowed and flag_trapping_math. */
1309 /* Don't constant fold this floating point operation if the
1310 result may dependent upon the run-time rounding mode and
1311 flag_rounding_math is set, or if GCC's software emulation
1312 is unable to accurately represent the result. */
1322 }
1325 {
1326 FIXED_VALUE_TYPE f1;
1327 FIXED_VALUE_TYPE f2;
1328 FIXED_VALUE_TYPE result;
1333 /* The following codes are handled by fixed_arithmetic. */
1335 {
1347 {
1354 }
1359 }
1366 /* Propagate overflow flags. */
1370 }
1373 {
1382 {
1393 mpc_mul);
1407 mpc_div);
1408 /* Fallthru. */
1414 {
1415 /* Keep this algorithm in sync with
1416 tree-complex.c:expand_complex_div_straight().
1418 Expand complex division to scalars, straightforward algorithm.
1419 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1420 t = br*br + bi*bi
1421 */
1422 tree magsquared
1426 tree t1
1430 tree t2
1437 }
1438 else
1439 {
1440 /* Keep this algorithm in sync with
1441 tree-complex.c:expand_complex_div_wide().
1443 Expand complex division to scalars, modified algorithm to minimize
1444 overflow with wide input ranges. */
1450 {
1451 /* In the TRUE branch, we compute
1452 ratio = br/bi;
1453 div = (br * ratio) + bi;
1454 tr = (ar * ratio) + ai;
1455 ti = (ai * ratio) - ar;
1456 tr = tr / div;
1457 ti = ti / div; */
1468 }
1469 else
1470 {
1471 /* In the FALSE branch, we compute
1472 ratio = d/c;
1473 divisor = (d * ratio) + c;
1474 tr = (b * ratio) + a;
1475 ti = b - (a * ratio);
1476 tr = tr / div;
1477 ti = ti / div; */
1489 }
1490 }
1495 }
1499 }
1505 {
1510 /* We can operate directly on the encoding if:
1512 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1513 implies
1514 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1516 Addition and subtraction are the supported operators
1517 for which this is true. */
1520 /* We can operate directly on stepped encodings if:
1522 a3 - a2 == a2 - a1
1523 implies:
1524 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1526 which is true if (x -> x op c) distributes over addition. */
1528 else
1529 /* Similarly in reverse. */
1531 tree_vector_builder elts;
1536 {
1542 /* It is possible that const_binop cannot handle the given
1543 code and return NULL_TREE */
1547 }
1550 }
1552 /* Shifts allow a scalar offset for a vector. */
1555 {
1558 tree_vector_builder elts;
1563 {
1568 /* It is possible that const_binop cannot handle the given
1569 code and return NULL_TREE. */
1573 }
1576 }
1578 }
1580 /* Overload that adds a TYPE parameter to be able to dispatch
1581 to fold_relational_const. */
1583 tree
1585 {
1589 /* ??? Until we make the const_binop worker take the type of the
1590 result as argument put those cases that need it here. */
1592 {
1609 {
1614 }
1619 {
1635 {
1645 }
1648 }
1654 {
1677 {
1690 }
1693 }
1696 }
1701 /* Make sure type and arg0 have the same saturating flag. */
1706 }
1708 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1709 Return zero if computing the constants is not possible. */
1711 tree
1713 {
1714 /* Don't perform the operation, other than NEGATE and ABS, if
1715 flag_signaling_nans is on and the operand is a signaling NaN. */
1724 {
1725 CASE_CONVERT:
1732 /* If the source address is 0, and the source address space
1733 cannot have a valid object at 0, fold to dest type null. */
1744 {
1745 /* Can't call fold_negate_const directly here as that doesn't
1746 handle all cases and we might not be able to negate some
1747 constants. */
1752 }
1761 {
1765 }
1773 /* Perform BIT_NOT_EXPR on each element individually. */
1775 {
1776 tree elem;
1778 /* This can cope with stepped encodings because ~x == -1 - x. */
1779 tree_vector_builder elements;
1783 {
1789 }
1792 }
1814 {
1833 else
1838 {
1844 }
1847 }
1856 }
1859 }
1861 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1862 indicates which particular sizetype to create. */
1864 tree
1866 {
1868 }
1869 \f
1870 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1871 is a tree code. The type of the result is taken from the operands.
1872 Both must be equivalent integer types, ala int_binop_types_match_p.
1873 If the operands are constant, so is the result. */
1875 tree
1877 {
1886 /* Handle the special case of two poly_int constants faster. */
1888 {
1889 /* And some specific cases even faster than that. */
1891 {
1896 }
1898 {
1901 }
1903 {
1906 }
1908 /* Handle general case of two integer constants. For sizetype
1909 constant calculations we always want to know about overflow,
1910 even in the unsigned case. */
1914 }
1917 }
1919 /* Given two values, either both of sizetype or both of bitsizetype,
1920 compute the difference between the two values. Return the value
1921 in signed type corresponding to the type of the operands. */
1923 tree
1925 {
1927 tree ctype;
1932 /* If the type is already signed, just do the simple thing. */
1940 else
1943 /* If either operand is not a constant, do the conversions to the signed
1944 type and subtract. The hardware will do the right thing with any
1945 overflow in the subtraction. */
1951 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1952 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1953 overflow) and negate (which can't either). Special-case a result
1954 of zero while we're here. */
1960 else
1964 MINUS_EXPR,
1966 }
1967 \f
1968 /* A subroutine of fold_convert_const handling conversions of an
1969 INTEGER_CST to another integer type. */
1971 static tree
1973 {
1974 /* Given an integer constant, make new constant with new type,
1975 appropriately sign-extended or truncated. Use widest_int
1976 so that any extension is done according ARG1's type. */
1980 }
1982 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1983 to an integer type. */
1985 static tree
1987 {
1989 tree t;
1991 /* The following code implements the floating point to integer
1992 conversion rules required by the Java Language Specification,
1993 that IEEE NaNs are mapped to zero and values that overflow
1994 the target precision saturate, i.e. values greater than
1995 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1996 are mapped to INT_MIN. These semantics are allowed by the
1997 C and C++ standards that simply state that the behavior of
1998 FP-to-integer conversion is unspecified upon overflow. */
2000 wide_int val;
2001 REAL_VALUE_TYPE r;
2005 {
2012 }
2014 /* If R is NaN, return zero and show we have an overflow. */
2016 {
2019 }
2021 /* See if R is less than the lower bound or greater than the
2022 upper bound. */
2025 {
2029 {
2032 }
2033 }
2036 {
2039 {
2042 {
2045 }
2046 }
2047 }
2054 }
2056 /* A subroutine of fold_convert_const handling conversions of a
2057 FIXED_CST to an integer type. */
2059 static tree
2061 {
2062 tree t;
2064 scalar_mode mode;
2066 /* Right shift FIXED_CST to temp by fbit. */
2070 {
2072 HOST_BITS_PER_DOUBLE_INT,
2075 /* Left shift temp to temp_trunc by fbit. */
2077 HOST_BITS_PER_DOUBLE_INT,
2079 }
2080 else
2081 {
2084 }
2086 /* If FIXED_CST is negative, we need to round the value toward 0.
2087 By checking if the fractional bits are not zero to add 1 to temp. */
2093 /* Given a fixed-point constant, make new constant with new type,
2094 appropriately sign-extended or truncated. */
2102 }
2104 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2105 to another floating point type. */
2107 static tree
2109 {
2110 REAL_VALUE_TYPE value;
2111 tree t;
2113 /* Don't perform the operation if flag_signaling_nans is on
2114 and the operand is a signaling NaN. */
2122 /* If converting an infinity or NAN to a representation that doesn't
2123 have one, set the overflow bit so that we can produce some kind of
2124 error message at the appropriate point if necessary. It's not the
2125 most user-friendly message, but it's better than nothing. */
2132 /* Regular overflow, conversion produced an infinity in a mode that
2133 can't represent them. */
2138 else
2141 }
2143 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2144 to a floating point type. */
2146 static tree
2148 {
2149 REAL_VALUE_TYPE value;
2150 tree t;
2158 }
2160 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2161 to another fixed-point type. */
2163 static tree
2165 {
2166 FIXED_VALUE_TYPE value;
2167 tree t;
2174 /* Propagate overflow flags. */
2178 }
2180 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2181 to a fixed-point type. */
2183 static tree
2185 {
2186 FIXED_VALUE_TYPE value;
2187 tree t;
2189 double_int di;
2196 else
2204 /* Propagate overflow flags. */
2208 }
2210 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2211 to a fixed-point type. */
2213 static tree
2215 {
2216 FIXED_VALUE_TYPE value;
2217 tree t;
2225 /* Propagate overflow flags. */
2229 }
2231 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2232 type TYPE. If no simplification can be done return NULL_TREE. */
2234 static tree
2236 {
2241 /* We can't widen types, since the runtime value could overflow the
2242 original type before being extended to the new type. */
2253 {
2260 }
2262 {
2269 }
2271 {
2278 }
2280 {
2283 {
2286 /* We can't handle steps directly when extending, since the
2287 values need to wrap at the original precision first. */
2288 bool step_ok_p
2292 tree_vector_builder v;
2297 {
2303 }
2305 }
2306 }
2308 }
2310 /* Construct a vector of zero elements of vector type TYPE. */
2312 static tree
2314 {
2315 tree t;
2319 }
2321 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2323 bool
2325 {
2340 {
2355 }
2356 }
2358 /* Convert expression ARG to type TYPE. Used by the middle-end for
2359 simple conversions in preference to calling the front-end's convert. */
2361 tree
2363 {
2365 tree tem;
2376 {
2379 /* Handle conversions between pointers to different address spaces. */
2384 /* fall through */
2389 {
2393 }
2407 {
2411 }
2413 {
2417 }
2419 {
2423 }
2426 {
2444 }
2449 {
2453 }
2456 {
2470 }
2474 {
2483 integer_zero_node));
2485 {
2489 {
2495 }
2503 }
2507 }
2525 }
2526 fold_convert_exit:
2529 }
2530 \f
2531 /* Return false if expr can be assumed not to be an lvalue, true
2532 otherwise. */
2534 static bool
2536 {
2537 /* We only need to wrap lvalue tree codes. */
2539 {
2570 /* Assume the worst for front-end tree codes. */
2574 }
2577 }
2579 /* Return an expr equal to X but certainly not valid as an lvalue. */
2581 tree
2583 {
2584 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2585 us. */
2592 }
2594 /* When pedantic, return an expr equal to X but certainly not valid as a
2595 pedantic lvalue. Otherwise, return X. */
2597 static tree
2599 {
2601 }
2602 \f
2603 /* Given a tree comparison code, return the code that is the logical inverse.
2604 It is generally not safe to do this for floating-point comparisons, except
2605 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2606 ERROR_MARK in this case. */
2608 enum tree_code
2610 {
2616 {
2647 }
2648 }
2650 /* Similar, but return the comparison that results if the operands are
2651 swapped. This is safe for floating-point. */
2653 enum tree_code
2655 {
2657 {
2683 }
2684 }
2687 /* Convert a comparison tree code from an enum tree_code representation
2688 into a compcode bit-based encoding. This function is the inverse of
2689 compcode_to_comparison. */
2691 static enum comparison_code
2693 {
2695 {
2726 }
2727 }
2729 /* Convert a compcode bit-based encoding of a comparison operator back
2730 to GCC's enum tree_code representation. This function is the
2731 inverse of comparison_to_compcode. */
2733 static enum tree_code
2735 {
2737 {
2768 }
2769 }
2771 /* Return a tree for the comparison which is the combination of
2772 doing the AND or OR (depending on CODE) of the two operations LCODE
2773 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2774 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2775 if this makes the transformation invalid. */
2777 tree
2782 {
2789 {
2800 }
2803 {
2804 /* Eliminate unordered comparisons, as well as LTGT and ORD
2805 which are not used unless the mode has NaNs. */
2811 }
2813 {
2814 /* Check that the original operation and the optimized ones will trap
2815 under the same condition. */
2826 /* In a short-circuited boolean expression the LHS might be
2827 such that the RHS, if evaluated, will never trap. For
2828 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2829 if neither x nor y is NaN. (This is a mixed blessing: for
2830 example, the expression above will never trap, hence
2831 optimizing it to x < y would be invalid). */
2836 /* If the comparison was short-circuited, and only the RHS
2837 trapped, we may now generate a spurious trap. */
2842 /* If we changed the conditions that cause a trap, we lose. */
2845 }
2851 else
2852 {
2857 }
2858 }
2859 \f
2860 /* Return nonzero if two operands (typically of the same tree node)
2861 are necessarily equal. FLAGS modifies behavior as follows:
2863 If OEP_ONLY_CONST is set, only return nonzero for constants.
2864 This function tests whether the operands are indistinguishable;
2865 it does not test whether they are equal using C's == operation.
2866 The distinction is important for IEEE floating point, because
2867 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2868 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2870 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2871 even though it may hold multiple values during a function.
2872 This is because a GCC tree node guarantees that nothing else is
2873 executed between the evaluation of its "operands" (which may often
2874 be evaluated in arbitrary order). Hence if the operands themselves
2875 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2876 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2877 unset means assuming isochronic (or instantaneous) tree equivalence.
2878 Unless comparing arbitrary expression trees, such as from different
2879 statements, this flag can usually be left unset.
2881 If OEP_PURE_SAME is set, then pure functions with identical arguments
2882 are considered the same. It is used when the caller has other ways
2883 to ensure that global memory is unchanged in between.
2885 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2886 not values of expressions.
2888 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2889 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2891 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2892 any operand with side effect. This is unnecesarily conservative in the
2893 case we know that arg0 and arg1 are in disjoint code paths (such as in
2894 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2895 addresses with TREE_CONSTANT flag set so we know that &var == &var
2896 even if var is volatile. */
2898 int
2900 {
2901 /* When checking, verify at the outermost operand_equal_p call that
2902 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2903 hash value. */
2905 {
2907 {
2909 {
2916 }
2918 }
2919 else
2921 }
2923 /* If either is ERROR_MARK, they aren't equal. */
2929 /* Similar, if either does not have a type (like a released SSA name),
2930 they aren't equal. */
2934 /* We cannot consider pointers to different address space equal. */
2941 /* Check equality of integer constants before bailing out due to
2942 precision differences. */
2944 {
2945 /* Address of INTEGER_CST is not defined; check that we did not forget
2946 to drop the OEP_ADDRESS_OF flags. */
2949 }
2952 {
2953 /* If both types don't have the same signedness, then we can't consider
2954 them equal. We must check this before the STRIP_NOPS calls
2955 because they may change the signedness of the arguments. As pointers
2956 strictly don't have a signedness, require either two pointers or
2957 two non-pointers as well. */
2963 /* If both types don't have the same precision, then it is not safe
2964 to strip NOPs. */
2971 }
2972 #if 0
2973 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
2974 sanity check once the issue is solved. */
2975 else
2976 /* Addresses of conversions and SSA_NAMEs (and many other things)
2977 are not defined. Check that we did not forget to drop the
2978 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
2981 #endif
2983 /* In case both args are comparisons but with different comparison
2984 code, try to swap the comparison operands of one arg to produce
2985 a match and compare that variant. */
2989 {
2997 }
3000 {
3001 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3003 ;
3005 {
3006 /* If we are interested in comparing addresses ignore
3007 MEM_REF wrappings of the base that can appear just for
3008 TBAA reasons. */
3022 }
3023 else
3025 }
3027 /* When not checking adddresses, this is needed for conversions and for
3028 COMPONENT_REF. Might as well play it safe and always test this. */
3035 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3036 We don't care about side effects in that case because the SAVE_EXPR
3037 takes care of that for us. In all other cases, two expressions are
3038 equal if they have no side effects. If we have two identical
3039 expressions with side effects that should be treated the same due
3040 to the only side effects being identical SAVE_EXPR's, that will
3041 be detected in the recursive calls below.
3042 If we are taking an invariant address of two identical objects
3043 they are necessarily equal as well. */
3050 /* Next handle constant cases, those for which we can return 1 even
3051 if ONLY_CONST is set. */
3054 {
3068 {
3069 /* If we do not distinguish between signed and unsigned zero,
3070 consider them equal. */
3073 }
3077 {
3092 }
3096 flags)
3098 flags));
3109 flags | OEP_ADDRESS_OF
3112 /* In GIMPLE empty constructors are allowed in initializers of
3113 aggregates. */
3117 }
3122 /* Define macros to test an operand from arg0 and arg1 for equality and a
3123 variant that allows null and views null as being different from any
3124 non-null value. In the latter case, if either is null, the both
3125 must be; otherwise, do the normal comparison. */
3126 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3127 TREE_OPERAND (arg1, N), flags)
3129 #define OP_SAME_WITH_NULL(N) \
3130 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3131 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3134 {
3136 /* Two conversions are equal only if signedness and modes match. */
3138 {
3139 CASE_CONVERT:
3147 }
3157 /* For commutative ops, allow the other order. */
3165 /* If either of the pointer (or reference) expressions we are
3166 dereferencing contain a side effect, these cannot be equal,
3167 but their addresses can be. */
3174 {
3184 /* Require the same offset. */
3190 /* Fallthru. */
3198 {
3199 /* Require equal access sizes */
3205 flags)))
3207 /* Verify that access happens in similar types. */
3210 /* Verify that accesses are TBAA compatible. */
3219 /* Verify that alignment is compatible. */
3223 }
3226 /* TARGET_MEM_REF require equal extra operands. */
3237 /* Compare the array index by value if it is constant first as we
3238 may have different types but same value here. */
3244 /* Compare low bound and element size as with OEP_ADDRESS_OF
3245 we have to account for the offset of the ref. */
3250 array_ref_low_bound
3254 array_ref_element_size
3256 flags))));
3259 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3260 may be NULL when we're called to compare MEM_EXPRs. */
3275 }
3279 {
3281 /* Be sure we pass right ADDRESS_OF flag. */
3299 /* The multiplcation operands are commutative. */
3300 /* FALLTHRU */
3308 /* Otherwise take into account this is a commutative operation. */
3321 /* BIT_INSERT_EXPR has an implict operand as the type precision
3322 of op1. Need to check to make sure they are the same. */
3328 /* FALLTHRU */
3353 }
3357 {
3361 /* If not both CALL_EXPRs are either internal or normal function
3362 functions, then they are not equal. */
3365 {
3366 /* If the CALL_EXPRs call different internal functions, then they
3367 are not equal. */
3370 }
3371 else
3372 {
3373 /* If the CALL_EXPRs call different functions, then they are not
3374 equal. */
3376 flags))
3378 }
3380 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3381 {
3385 else
3389 }
3391 /* Now see if all the arguments are the same. */
3392 {
3403 /* If we get here and both argument lists are exhausted
3404 then the CALL_EXPRs are equal. */
3406 }
3409 }
3412 /* Consider __builtin_sqrt equal to sqrt. */
3420 {
3421 /* In GIMPLE constructors are used only to build vectors from
3422 elements. Individual elements in the constructor must be
3423 indexed in increasing order and form an initial sequence.
3425 We make no effort to compare constructors in generic.
3426 (see sem_variable::equals in ipa-icf which can do so for
3427 constants). */
3432 /* Be sure that vectors constructed have the same representation.
3433 We only tested element precision and modes to match.
3434 Vectors may be BLKmode and thus also check that the number of
3435 parts match. */
3448 {
3453 /* In GIMPLE the indexes can be either NULL or matching i.
3454 Double check this so we won't get false
3455 positives for GENERIC. */
3463 }
3465 }
3468 {
3469 /* Compare the STATEMENT_LISTs. */
3475 {
3476 /* The lists don't have the same number of statements. */
3482 OEP_LEXICOGRAPHIC))
3484 }
3485 }
3490 {
3497 }
3501 }
3503 #undef OP_SAME
3504 #undef OP_SAME_WITH_NULL
3505 }
3506 \f
3507 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3508 with a different signedness or a narrower precision. */
3510 static bool
3512 {
3520 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3521 and see if the inner values are the same. This removes any
3522 signedness comparison, which doesn't matter here. */
3530 /* Discard a single widening conversion from ARG1 and see if the inner
3531 value is the same as ARG0. */
3540 }
3541 \f
3542 /* See if ARG is an expression that is either a comparison or is performing
3543 arithmetic on comparisons. The comparisons must only be comparing
3544 two different values, which will be stored in *CVAL1 and *CVAL2; if
3545 they are nonzero it means that some operands have already been found.
3546 No variables may be used anywhere else in the expression except in the
3547 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3548 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3550 If this is true, return 1. Otherwise, return zero. */
3552 static int
3554 {
3558 /* We can handle some of the tcc_expression cases here. */
3568 {
3569 /* If we've already found a CVAL1 or CVAL2, this expression is
3570 two complex to handle. */
3576 }
3579 {
3602 /* First see if we can handle the first operand, then the second. For
3603 the second operand, we know *CVAL1 can't be zero. It must be that
3604 one side of the comparison is each of the values; test for the
3605 case where this isn't true by failing if the two operands
3606 are the same. */
3615 ;
3619 ;
3620 else
3624 ;
3628 ;
3629 else
3636 }
3637 }
3638 \f
3639 /* ARG is a tree that is known to contain just arithmetic operations and
3640 comparisons. Evaluate the operations in the tree substituting NEW0 for
3641 any occurrence of OLD0 as an operand of a comparison and likewise for
3642 NEW1 and OLD1. */
3644 static tree
3647 {
3652 /* We can handle some of the tcc_expression cases here. */
3660 {
3675 {
3694 }
3695 /* Fall through - ??? */
3698 {
3702 /* We need to check both for exact equality and tree equality. The
3703 former will be true if the operand has a side-effect. In that
3704 case, we know the operand occurred exactly once. */
3717 }
3721 }
3722 }
3723 \f
3724 /* Return a tree for the case when the result of an expression is RESULT
3725 converted to TYPE and OMITTED was previously an operand of the expression
3726 but is now not needed (e.g., we folded OMITTED * 0).
3728 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3729 the conversion of RESULT to TYPE. */
3731 tree
3733 {
3736 /* If the resulting operand is an empty statement, just return the omitted
3737 statement casted to void. */
3747 }
3749 /* Return a tree for the case when the result of an expression is RESULT
3750 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3751 of the expression but are now not needed.
3753 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3754 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3755 evaluated before OMITTED2. Otherwise, if neither has side effects,
3756 just do the conversion of RESULT to TYPE. */
3758 tree
3761 {
3770 }
3772 \f
3773 /* Return a simplified tree node for the truth-negation of ARG. This
3774 never alters ARG itself. We assume that ARG is an operation that
3775 returns a truth value (0 or 1).
3777 FIXME: one would think we would fold the result, but it causes
3778 problems with the dominator optimizer. */
3780 static tree
3782 {
3787 /* If this is a comparison, we can simply invert it, except for
3788 floating-point non-equality comparisons, in which case we just
3789 enclose a TRUTH_NOT_EXPR around what we have. */
3792 {
3795 && flag_trapping_math
3809 }
3812 {
3831 /* Here we can invert either operand. We invert the first operand
3832 unless the second operand is a TRUTH_NOT_EXPR in which case our
3833 result is the XOR of the first operand with the inside of the
3834 negation of the second operand. */
3839 else
3862 {
3869 /* A COND_EXPR may have a throw as one operand, which
3870 then has void type. Just leave void operands
3871 as they are. */
3877 }
3889 CASE_CONVERT:
3893 /* fall through */
3915 }
3916 }
3918 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3919 assume that ARG is an operation that returns a truth value (0 or 1
3920 for scalars, 0 or -1 for vectors). Return the folded expression if
3921 folding is successful. Otherwise, return NULL_TREE. */
3923 static tree
3925 {
3928 ? BIT_NOT_EXPR
3931 }
3933 /* Return a simplified tree node for the truth-negation of ARG. This
3934 never alters ARG itself. We assume that ARG is an operation that
3935 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3937 tree
3939 {
3945 ? BIT_NOT_EXPR
3948 }
3949 \f
3950 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3951 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3952 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3953 is the original memory reference used to preserve the alias set of
3954 the access. */
3956 static tree
3960 {
3963 /* Attempt not to lose the access path if possible. */
3965 {
3967 machine_mode nmode;
3969 tree noffset;
3977 && !reversep
3978 && !nreversep
3980 {
3983 }
3984 }
3993 {
4000 }
4015 }
4017 /* Optimize a bit-field compare.
4019 There are two cases: First is a compare against a constant and the
4020 second is a comparison of two items where the fields are at the same
4021 bit position relative to the start of a chunk (byte, halfword, word)
4022 large enough to contain it. In these cases we can avoid the shift
4023 implicit in bitfield extractions.
4025 For constants, we emit a compare of the shifted constant with the
4026 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4027 compared. For two fields at the same position, we do the ANDs with the
4028 similar mask and compare the result of the ANDs.
4030 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4031 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4032 are the left and right operands of the comparison, respectively.
4034 If the optimization described above can be done, we return the resulting
4035 tree. Otherwise we return zero. */
4037 static tree
4040 {
4044 tree unsigned_type;
4047 scalar_int_mode nmode;
4052 tree mask;
4053 tree offset;
4055 /* Get all the information about the extractions being done. If the bit size
4056 is the same as the size of the underlying object, we aren't doing an
4057 extraction at all and so can do nothing. We also don't want to
4058 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4059 then will no longer be able to replace it. */
4074 else
4075 {
4076 /* If this is not a constant, we can only do something if bit positions,
4077 sizes, signedness and storage order are the same. */
4078 rinner
4091 }
4093 /* Honor the C++ memory model and mimic what RTL expansion does. */
4097 {
4101 }
4103 /* See if we can find a mode to refer to this field. We should be able to,
4104 but fail if we can't. */
4112 /* Set signed and unsigned types of the precision of this mode for the
4113 shifts below. */
4116 /* Compute the bit position and size for the new reference and our offset
4117 within it. If the new reference is the same size as the original, we
4118 won't optimize anything, so return zero. */
4128 /* Make the mask to be used against the extracted field. */
4135 {
4139 /* If not comparing with constant, just rework the comparison
4140 and return. */
4148 }
4150 /* Otherwise, we are handling the constant case. See if the constant is too
4151 big for the field. Warn and return a tree for 0 (false) if so. We do
4152 this not only for its own sake, but to avoid having to test for this
4153 error case below. If we didn't, we might generate wrong code.
4155 For unsigned fields, the constant shifted right by the field length should
4156 be all zero. For signed fields, the high-order bits should agree with
4157 the sign bit. */
4160 {
4162 {
4166 }
4167 }
4168 else
4169 {
4172 {
4176 }
4177 }
4182 /* Single-bit compares should always be against zero. */
4184 {
4187 }
4189 /* Make a new bitfield reference, shift the constant over the
4190 appropriate number of bits and mask it with the computed mask
4191 (in case this was a signed field). If we changed it, make a new one. */
4199 mask);
4204 }
4205 \f
4206 /* Subroutine for fold_truth_andor_1: decode a field reference.
4208 If EXP is a comparison reference, we return the innermost reference.
4210 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4211 set to the starting bit number.
4213 If the innermost field can be completely contained in a mode-sized
4214 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4216 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4217 otherwise it is not changed.
4219 *PUNSIGNEDP is set to the signedness of the field.
4221 *PREVERSEP is set to the storage order of the field.
4223 *PMASK is set to the mask used. This is either contained in a
4224 BIT_AND_EXPR or derived from the width of the field.
4226 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4228 Return 0 if this is not a component reference or is one that we can't
4229 do anything with. */
4231 static tree
4236 {
4241 tree unsigned_type;
4244 /* All the optimizations using this function assume integer fields.
4245 There are problems with FP fields since the type_for_size call
4246 below can fail for, e.g., XFmode. */
4250 /* We are interested in the bare arrangement of bits, so strip everything
4251 that doesn't affect the machine mode. However, record the type of the
4252 outermost expression if it may matter below. */
4259 {
4265 }
4276 /* Reject out-of-bound accesses (PR79731). */
4284 /* If the number of bits in the reference is the same as the bitsize of
4285 the outer type, then the outer type gives the signedness. Otherwise
4286 (in case of a small bitfield) the signedness is unchanged. */
4290 /* Compute the mask to access the bitfield. */
4299 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4307 }
4309 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4310 bit positions and MASK is SIGNED. */
4312 static int
4314 {
4318 /* If this function returns true when the type of the mask is
4319 UNSIGNED, then there will be errors. In particular see
4320 gcc.c-torture/execute/990326-1.c. There does not appear to be
4321 any documentation paper trail as to why this is so. But the pre
4322 wide-int worked with that restriction and it has been preserved
4323 here. */
4328 }
4330 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4331 represents the sign bit of EXP's type. If EXP represents a sign
4332 or zero extension, also test VAL against the unextended type.
4333 The return value is the (sub)expression whose sign bit is VAL,
4334 or NULL_TREE otherwise. */
4336 tree
4338 {
4340 tree t;
4342 /* Tree EXP must have an integral type. */
4347 /* Tree VAL must be an integer constant. */
4356 /* Handle extension from a narrower type. */
4362 }
4364 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4365 to be evaluated unconditionally. */
4367 static int
4369 {
4370 /* Strip any conversions that don't change the machine mode. */
4379 /* Don't regard global variables as simple. They may be
4380 allocated in ways unknown to the compiler (shared memory,
4381 #pragma weak, etc). */
4384 /* Weakrefs are not safe to be read, since they can be NULL.
4385 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4386 have DECL_WEAK flag set. */
4388 /* Loading a static variable is unduly expensive, but global
4389 registers aren't expensive. */
4391 }
4393 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4394 to be evaluated unconditionally.
4395 I addition to simple_operand_p, we assume that comparisons, conversions,
4396 and logic-not operations are simple, if their operands are simple, too. */
4398 static bool
4400 {
4420 }
4422 \f
4423 /* The following functions are subroutines to fold_range_test and allow it to
4424 try to change a logical combination of comparisons into a range test.
4426 For example, both
4427 X == 2 || X == 3 || X == 4 || X == 5
4428 and
4429 X >= 2 && X <= 5
4430 are converted to
4431 (unsigned) (X - 2) <= 3
4433 We describe each set of comparisons as being either inside or outside
4434 a range, using a variable named like IN_P, and then describe the
4435 range with a lower and upper bound. If one of the bounds is omitted,
4436 it represents either the highest or lowest value of the type.
4438 In the comments below, we represent a range by two numbers in brackets
4439 preceded by a "+" to designate being inside that range, or a "-" to
4440 designate being outside that range, so the condition can be inverted by
4441 flipping the prefix. An omitted bound is represented by a "-". For
4442 example, "- [-, 10]" means being outside the range starting at the lowest
4443 possible value and ending at 10, in other words, being greater than 10.
4444 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4445 always false.
4447 We set up things so that the missing bounds are handled in a consistent
4448 manner so neither a missing bound nor "true" and "false" need to be
4449 handled using a special case. */
4451 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4452 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4453 and UPPER1_P are nonzero if the respective argument is an upper bound
4454 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4455 must be specified for a comparison. ARG1 will be converted to ARG0's
4456 type if both are specified. */
4458 static tree
4461 {
4462 tree tem;
4466 /* If neither arg represents infinity, do the normal operation.
4467 Else, if not a comparison, return infinity. Else handle the special
4468 comparison rules. Note that most of the cases below won't occur, but
4469 are handled for consistency. */
4472 {
4477 }
4482 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4483 for neither. In real maths, we cannot assume open ended ranges are
4484 the same. But, this is computer arithmetic, where numbers are finite.
4485 We can therefore make the transformation of any unbounded range with
4486 the value Z, Z being greater than any representable number. This permits
4487 us to treat unbounded ranges as equal. */
4491 {
4512 }
4515 }
4516 \f
4517 /* Helper routine for make_range. Perform one step for it, return
4518 new expression if the loop should continue or NULL_TREE if it should
4519 stop. */
4521 tree
4525 {
4531 {
4533 /* We can only do something if the range is testing for zero. */
4542 /* We can only do something if the range is testing for zero
4543 and if the second operand is an integer constant. Note that
4544 saying something is "in" the range we make is done by
4545 complementing IN_P since it will set in the initial case of
4546 being not equal to zero; "out" is leaving it alone. */
4553 {
4574 }
4576 /* If this is an unsigned comparison, we also know that EXP is
4577 greater than or equal to zero. We base the range tests we make
4578 on that fact, so we record it here so we can parse existing
4579 range tests. We test arg0_type since often the return type
4580 of, e.g. EQ_EXPR, is boolean. */
4582 {
4586 NULL_TREE))
4591 /* If the high bound is missing, but we have a nonzero low
4592 bound, reverse the range so it goes from zero to the low bound
4593 minus 1. */
4595 {
4600 }
4601 }
4609 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4610 low and high are non-NULL, then normalize will DTRT. */
4613 {
4618 }
4620 /* (-x) IN [a,b] -> x in [-b, -a] */
4632 /* ~ X -> -X - 1 */
4641 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4642 move a constant to the other side. */
4647 /* If EXP is signed, any overflow in the computation is undefined,
4648 so we don't worry about it so long as our computations on
4649 the bounds don't overflow. For unsigned, overflow is defined
4650 and this is exactly the right thing. */
4662 normalize:
4663 /* Check for an unsigned range which has wrapped around the maximum
4664 value thus making n_high < n_low, and normalize it. */
4666 {
4672 /* If the range is of the form +/- [ x+1, x ], we won't
4673 be able to normalize it. But then, it represents the
4674 whole range or the empty set, so make it
4675 +/- [ -, - ]. */
4679 else
4681 }
4682 else
4690 CASE_CONVERT:
4708 /* If we're converting arg0 from an unsigned type, to exp,
4709 a signed type, we will be doing the comparison as unsigned.
4710 The tests above have already verified that LOW and HIGH
4711 are both positive.
4713 So we have to ensure that we will handle large unsigned
4714 values the same way that the current signed bounds treat
4715 negative values. */
4718 {
4719 tree high_positive;
4720 tree equiv_type;
4721 /* For fixed-point modes, we need to pass the saturating flag
4722 as the 2nd parameter. */
4724 equiv_type
4727 else
4728 equiv_type
4731 /* A range without an upper bound is, naturally, unbounded.
4732 Since convert would have cropped a very large value, use
4733 the max value for the destination type. */
4734 high_positive
4741 high_positive),
4744 /* If the low bound is specified, "and" the range with the
4745 range for which the original unsigned value will be
4746 positive. */
4748 {
4751 integer_zero_node),
4752 high_positive))
4756 }
4757 else
4758 {
4759 /* Otherwise, "or" the range with the range of the input
4760 that will be interpreted as negative. */
4763 integer_zero_node),
4764 high_positive))
4768 }
4769 }
4778 }
4779 }
4781 /* Given EXP, a logical expression, set the range it is testing into
4782 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4783 actually being tested. *PLOW and *PHIGH will be made of the same
4784 type as the returned expression. If EXP is not a comparison, we
4785 will most likely not be returning a useful value and range. Set
4786 *STRICT_OVERFLOW_P to true if the return value is only valid
4787 because signed overflow is undefined; otherwise, do not change
4788 *STRICT_OVERFLOW_P. */
4790 tree
4793 {
4801 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4802 and see if we can refine the range. Some of the cases below may not
4803 happen, but it doesn't seem worth worrying about this. We "continue"
4804 the outer loop when we've changed something; otherwise we "break"
4805 the switch, which will "break" the while. */
4811 {
4817 {
4825 }
4834 }
4836 /* If EXP is a constant, we can evaluate whether this is true or false. */
4838 {
4845 }
4849 }
4851 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4852 a bitwise check i.e. when
4853 LOW == 0xXX...X00...0
4854 HIGH == 0xXX...X11...1
4855 Return corresponding mask in MASK and stem in VALUE. */
4857 static bool
4860 {
4883 }
4884 \f
4885 /* Helper routine for build_range_check and match.pd. Return the type to
4886 perform the check or NULL if it shouldn't be optimized. */
4888 tree
4890 {
4891 /* First make sure that arithmetics in this type is valid, then make sure
4892 that it wraps around. */
4898 {
4901 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4902 for the type in question, as we rely on this here. */
4912 else
4914 }
4916 }
4918 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4919 type, TYPE, return an expression to test if EXP is in (or out of, depending
4920 on IN_P) the range. Return 0 if the test couldn't be created. */
4922 tree
4925 {
4928 /* Disable this optimization for function pointer expressions
4929 on targets that require function pointer canonicalization. */
4936 {
4942 }
4964 value);
4967 {
4969 {
4973 }
4975 }
4977 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4979 {
4983 {
4985 {
4988 etype
4990 else
4993 }
4996 }
4997 }
4999 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5000 This requires wrap-around arithmetics for the type of the expression. */
5020 }
5021 \f
5022 /* Return the predecessor of VAL in its type, handling the infinite case. */
5024 static tree
5026 {
5032 else
5035 }
5037 /* Return the successor of VAL in its type, handling the infinite case. */
5039 static tree
5041 {
5047 else
5050 }
5052 /* Given two ranges, see if we can merge them into one. Return 1 if we
5053 can, 0 if we can't. Set the output range into the specified parameters. */
5055 bool
5058 {
5062 tree tem;
5072 /* Make range 0 be the range that starts first, or ends last if they
5073 start at the same value. Swap them if it isn't. */
5076 || (lowequal
5079 {
5083 }
5085 /* Now flag two cases, whether the ranges are disjoint or whether the
5086 second range is totally subsumed in the first. Note that the tests
5087 below are simplified by the ones above. */
5093 /* We now have four cases, depending on whether we are including or
5094 excluding the two ranges. */
5096 {
5097 /* If they don't overlap, the result is false. If the second range
5098 is a subset it is the result. Otherwise, the range is from the start
5099 of the second to the end of the first. */
5104 else
5106 }
5109 {
5110 /* If they don't overlap, the result is the first range. If they are
5111 equal, the result is false. If the second range is a subset of the
5112 first, and the ranges begin at the same place, we go from just after
5113 the end of the second range to the end of the first. If the second
5114 range is not a subset of the first, or if it is a subset and both
5115 ranges end at the same place, the range starts at the start of the
5116 first range and ends just before the second range.
5117 Otherwise, we can't describe this as a single range. */
5123 {
5128 {
5129 /* We are in the weird situation where high0 > high1 but
5130 high1 has no successor. Punt. */
5132 }
5133 }
5135 {
5140 {
5141 /* low0 < low1 but low1 has no predecessor. Punt. */
5143 }
5144 }
5145 else
5147 }
5150 {
5151 /* If they don't overlap, the result is the second range. If the second
5152 is a subset of the first, the result is false. Otherwise,
5153 the range starts just after the first range and ends at the
5154 end of the second. */
5159 else
5160 {
5165 {
5166 /* high1 > high0 but high0 has no successor. Punt. */
5168 }
5169 }
5170 }
5172 else
5173 {
5174 /* The case where we are excluding both ranges. Here the complex case
5175 is if they don't overlap. In that case, the only time we have a
5176 range is if they are adjacent. If the second is a subset of the
5177 first, the result is the first. Otherwise, the range to exclude
5178 starts at the beginning of the first range and ends at the end of the
5179 second. */
5181 {
5186 else
5187 {
5188 /* Canonicalize - [min, x] into - [-, x]. */
5191 {
5194 GET_MODE_BITSIZE
5197 /* FALLTHROUGH */
5210 }
5212 /* Canonicalize - [x, max] into - [x, -]. */
5215 {
5218 GET_MODE_BITSIZE
5221 /* FALLTHROUGH */
5237 }
5239 /* The ranges might be also adjacent between the maximum and
5240 minimum values of the given type. For
5241 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5242 return + [x + 1, y - 1]. */
5244 {
5251 }
5252 else
5254 }
5255 }
5258 else
5260 }
5264 }
5265 \f
5267 /* Subroutine of fold, looking inside expressions of the form
5268 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5269 of the COND_EXPR. This function is being used also to optimize
5270 A op B ? C : A, by reversing the comparison first.
5272 Return a folded expression whose code is not a COND_EXPR
5273 anymore, or NULL_TREE if no folding opportunity is found. */
5275 static tree
5278 {
5283 tree tem;
5288 /* If we have A op 0 ? A : -A, consider applying the following
5289 transformations:
5291 A == 0? A : -A same as -A
5292 A != 0? A : -A same as A
5293 A >= 0? A : -A same as abs (A)
5294 A > 0? A : -A same as abs (A)
5295 A <= 0? A : -A same as -abs (A)
5296 A < 0? A : -A same as -abs (A)
5298 None of these transformations work for modes with signed
5299 zeros. If A is +/-0, the first two transformations will
5300 change the sign of the result (from +0 to -0, or vice
5301 versa). The last four will fix the sign of the result,
5302 even though the original expressions could be positive or
5303 negative, depending on the sign of A.
5305 Note that all these transformations are correct if A is
5306 NaN, since the two alternatives (A and -A) are also NaNs. */
5313 /* In the case that A is of the form X-Y, '-A' (arg2) may
5314 have already been folded to Y-X, check for that. */
5322 {
5334 /* Fall through. */
5345 /* FALLTHRU */
5355 }
5357 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5358 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5359 both transformations are correct when A is NaN: A != 0
5360 is then true, and A == 0 is false. */
5364 {
5369 }
5371 /* Try some transformations of A op B ? A : B.
5373 A == B? A : B same as B
5374 A != B? A : B same as A
5375 A >= B? A : B same as max (A, B)
5376 A > B? A : B same as max (B, A)
5377 A <= B? A : B same as min (A, B)
5378 A < B? A : B same as min (B, A)
5380 As above, these transformations don't work in the presence
5381 of signed zeros. For example, if A and B are zeros of
5382 opposite sign, the first two transformations will change
5383 the sign of the result. In the last four, the original
5384 expressions give different results for (A=+0, B=-0) and
5385 (A=-0, B=+0), but the transformed expressions do not.
5387 The first two transformations are correct if either A or B
5388 is a NaN. In the first transformation, the condition will
5389 be false, and B will indeed be chosen. In the case of the
5390 second transformation, the condition A != B will be true,
5391 and A will be chosen.
5393 The conversions to max() and min() are not correct if B is
5394 a number and A is not. The conditions in the original
5395 expressions will be false, so all four give B. The min()
5396 and max() versions would give a NaN instead. */
5399 /* Avoid these transformations if the COND_EXPR may be used
5400 as an lvalue in the C++ front-end. PR c++/19199. */
5401 && (in_gimple_form
5407 {
5413 {
5422 /* In C++ a ?: expression can be an lvalue, so put the
5423 operand which will be used if they are equal first
5424 so that we can convert this back to the
5425 corresponding COND_EXPR. */
5427 {
5435 }
5442 {
5450 }
5463 }
5464 }
5467 }
5470 \f
5471 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5472 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5473 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5474 false) >= 2)
5475 #endif
5477 /* EXP is some logical combination of boolean tests. See if we can
5478 merge it into some range test. Return the new tree if so. */
5480 static tree
5483 {
5499 /* If this is an OR operation, invert both sides; we will invert
5500 again at the end. */
5504 /* If both expressions are the same, if we can merge the ranges, and we
5505 can build the range test, return it or it inverted. If one of the
5506 ranges is always true or always false, consider it to be the same
5507 expression as the other. */
5515 {
5519 }
5521 /* On machines where the branch cost is expensive, if this is a
5522 short-circuited branch and the underlying object on both sides
5523 is the same, make a non-short-circuit operation. */
5525 && !flag_sanitize_coverage
5530 {
5531 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5532 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5533 which cases we can't do this. */
5541 {
5550 {
5553 WARN_STRICT_OVERFLOW_COMPARISON);
5557 }
5558 }
5559 }
5562 }
5563 \f
5564 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5565 bit value. Arrange things so the extra bits will be set to zero if and
5566 only if C is signed-extended to its full width. If MASK is nonzero,
5567 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5569 static tree
5571 {
5574 tree temp;
5579 /* We work by getting just the sign bit into the low-order bit, then
5580 into the high-order bit, then sign-extend. We then XOR that value
5581 with C. */
5585 /* We must use a signed type in order to get an arithmetic right shift.
5586 However, we must also avoid introducing accidental overflows, so that
5587 a subsequent call to integer_zerop will work. Hence we must
5588 do the type conversion here. At this point, the constant is either
5589 zero or one, and the conversion to a signed type can never overflow.
5590 We could get an overflow if this conversion is done anywhere else. */
5599 /* If necessary, convert the type back to match the type of C. */
5604 }
5605 \f
5606 /* For an expression that has the form
5607 (A && B) || ~B
5608 or
5609 (A || B) && ~B,
5610 we can drop one of the inner expressions and simplify to
5611 A || ~B
5612 or
5613 A && ~B
5614 LOC is the location of the resulting expression. OP is the inner
5615 logical operation; the left-hand side in the examples above, while CMPOP
5616 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5617 removing a condition that guards another, as in
5618 (A != NULL && A->...) || A == NULL
5619 which we must not transform. If RHS_ONLY is true, only eliminate the
5620 right-most operand of the inner logical operation. */
5622 static tree
5625 {
5643 {
5646 {
5649 }
5650 }
5652 {
5655 {
5658 }
5659 }
5674 }
5676 /* Find ways of folding logical expressions of LHS and RHS:
5677 Try to merge two comparisons to the same innermost item.
5678 Look for range tests like "ch >= '0' && ch <= '9'".
5679 Look for combinations of simple terms on machines with expensive branches
5680 and evaluate the RHS unconditionally.
5682 For example, if we have p->a == 2 && p->b == 4 and we can make an
5683 object large enough to span both A and B, we can do this with a comparison
5684 against the object ANDed with the a mask.
5686 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5687 operations to do this with one comparison.
5689 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5690 function and the one above.
5692 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5693 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5695 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5696 two operands.
5698 We return the simplified tree or 0 if no optimization is possible. */
5700 static tree
5703 {
5704 /* If this is the "or" of two comparisons, we can do something if
5705 the comparisons are NE_EXPR. If this is the "and", we can do something
5706 if the comparisons are EQ_EXPR. I.e.,
5707 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5709 WANTED_CODE is this operation code. For single bit fields, we can
5710 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5711 comparison for one-bit fields. */
5732 /* Start by getting the comparison codes. Fail if anything is volatile.
5733 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5734 it were surrounded with a NE_EXPR. */
5743 {
5747 }
5750 {
5754 }
5765 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5768 {
5771 {
5776 }
5779 {
5785 }
5786 }
5791 /* If the RHS can be evaluated unconditionally and its operands are
5792 simple, it wins to evaluate the RHS unconditionally on machines
5793 with expensive branches. In this case, this isn't a comparison
5794 that can be merged. */
5801 {
5802 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5813 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5823 }
5825 /* See if the comparisons can be merged. Then get all the parameters for
5826 each side. */
5851 /* It must be true that the inner operation on the lhs of each
5852 comparison must be the same if we are to be able to do anything.
5853 Then see if we have constants. If not, the same must be true for
5854 the rhs's. */
5863 {
5866 }
5871 else
5874 /* If either comparison code is not correct for our logical operation,
5875 fail. However, we can convert a one-bit comparison against zero into
5876 the opposite comparison against that bit being set in the field. */
5880 {
5882 {
5883 /* Make the left operand unsigned, since we are only interested
5884 in the value of one bit. Otherwise we are doing the wrong
5885 thing below. */
5888 }
5889 else
5891 }
5893 /* This is analogous to the code for l_const above. */
5895 {
5897 {
5900 }
5901 else
5903 }
5905 /* See if we can find a mode that contains both fields being compared on
5906 the left. If we can't, fail. Otherwise, update all constants and masks
5907 to be relative to a field of that size. */
5921 {
5924 }
5932 {
5939 {
5943 }
5944 }
5946 {
5953 {
5957 }
5958 }
5960 /* If the right sides are not constant, do the same for it. Also,
5961 disallow this optimization if a size or signedness mismatch occurs
5962 between the left and right sides. */
5964 {
5967 /* Make sure the two fields on the right
5968 correspond to the left without being swapped. */
5985 {
5988 }
5997 /* Make a mask that corresponds to both fields being compared.
5998 Do this for both items being compared. If the operands are the
5999 same size and the bits being compared are in the same position
6000 then we can do this by masking both and comparing the masked
6001 results. */
6008 {
6022 }
6024 /* There is still another way we can do something: If both pairs of
6025 fields being compared are adjacent, we may be able to make a wider
6026 field containing them both.
6028 Note that we still must mask the lhs/rhs expressions. Furthermore,
6029 the mask must be shifted to account for the shift done by
6030 make_bit_field_ref. */
6039 {
6040 tree type;
6056 /* Convert to the smaller type before masking out unwanted bits. */
6059 {
6061 {
6065 }
6067 {
6071 }
6072 }
6081 }
6084 }
6086 /* Handle the case of comparisons with constants. If there is something in
6087 common between the masks, those bits of the constants must be the same.
6088 If not, the condition is always false. Test for this to avoid generating
6089 incorrect code below. */
6094 {
6096 {
6099 }
6100 else
6101 {
6104 }
6105 }
6110 /* Construct the expression we will return. First get the component
6111 reference we will make. Unless the mask is all ones the width of
6112 that field, perform the mask operation. Then compare with the
6113 merged constant. */
6124 }
6125 \f
6126 /* T is an integer expression that is being multiplied, divided, or taken a
6127 modulus (CODE says which and what kind of divide or modulus) by a
6128 constant C. See if we can eliminate that operation by folding it with
6129 other operations already in T. WIDE_TYPE, if non-null, is a type that
6130 should be used for the computation if wider than our type.
6132 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6133 (X * 2) + (Y * 4). We must, however, be assured that either the original
6134 expression would not overflow or that overflow is undefined for the type
6135 in the language in question.
6137 If we return a non-null expression, it is an equivalent form of the
6138 original computation, but need not be in the original type.
6140 We set *STRICT_OVERFLOW_P to true if the return values depends on
6141 signed overflow being undefined. Otherwise we do not change
6142 *STRICT_OVERFLOW_P. */
6144 static tree
6147 {
6148 /* To avoid exponential search depth, refuse to allow recursion past
6149 three levels. Beyond that (1) it's highly unlikely that we'll find
6150 something interesting and (2) we've probably processed it before
6151 when we built the inner expression. */
6154 tree ret;
6159 depth++;
6161 depth--;
6164 }
6166 static tree
6169 {
6181 /* Don't deal with constants of zero here; they confuse the code below. */
6191 /* Note that we need not handle conditional operations here since fold
6192 already handles those cases. So just do arithmetic here. */
6194 {
6196 /* For a constant, we can always simplify if we are a multiply
6197 or (for divide and modulus) if it is a multiple of our constant. */
6201 {
6204 /* If the multiplication overflowed, we lost information on it.
6205 See PR68142 and PR69845. */
6209 }
6213 /* If op0 is an expression ... */
6219 /* ... and has wrapping overflow, and its type is smaller
6220 than ctype, then we cannot pass through as widening. */
6225 /* ... or this is a truncation (t is narrower than op0),
6226 then we cannot pass through this narrowing. */
6229 /* ... or signedness changes for division or modulus,
6230 then we cannot pass through this conversion. */
6234 /* ... or has undefined overflow while the converted to
6235 type has not, we cannot do the operation in the inner type
6236 as that would introduce undefined overflow. */
6242 /* Pass the constant down and see if we can make a simplification. If
6243 we can, replace this expression with the inner simplification for
6244 possible later conversion to our or some other type. */
6255 /* If widening the type changes it from signed to unsigned, then we
6256 must avoid building ABS_EXPR itself as unsigned. */
6258 {
6262 {
6265 }
6267 }
6268 /* If the constant is negative, we cannot simplify this. */
6271 /* FALLTHROUGH */
6273 /* For division and modulus, type can't be unsigned, as e.g.
6274 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6275 For signed types, even with wrapping overflow, this is fine. */
6284 /* If widening the type changes the signedness, then we can't perform
6285 this optimization as that changes the result. */
6289 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6295 {
6302 }
6306 /* If the second operand is constant, this is a multiplication
6307 or floor division, by a power of two, so we can treat it that
6308 way unless the multiplier or divisor overflows. Signed
6309 left-shift overflow is implementation-defined rather than
6310 undefined in C90, so do not convert signed left shift into
6311 multiplication. */
6314 /* const_binop may not detect overflow correctly,
6315 so check for it explicitly here. */
6324 ctype,
6326 t1),
6331 /* See if we can eliminate the operation on both sides. If we can, we
6332 can return a new PLUS or MINUS. If we can't, the only remaining
6333 cases where we can do anything are if the second operand is a
6334 constant. */
6341 /* If not multiplication, we can only do this if both operands
6342 are divisible by c. */
6345 {
6350 }
6352 /* If this was a subtraction, negate OP1 and set it to be an addition.
6353 This simplifies the logic below. */
6355 {
6357 /* If OP1 was not easily negatable, the constant may be OP0. */
6359 {
6362 }
6363 }
6368 /* If either OP1 or C are negative, this optimization is not safe for
6369 some of the division and remainder types while for others we need
6370 to change the code. */
6372 {
6380 }
6382 /* If it's a multiply or a division/modulus operation of a multiple
6383 of our constant, do the operation and verify it doesn't overflow. */
6387 {
6390 /* We allow the constant to overflow with wrapping semantics. */
6394 }
6395 else
6398 /* If we have an unsigned type, we cannot widen the operation since it
6399 will change the result if the original computation overflowed. */
6403 /* The last case is if we are a multiply. In that case, we can
6404 apply the distributive law to commute the multiply and addition
6405 if the multiplication of the constants doesn't overflow
6406 and overflow is defined. With undefined overflow
6407 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6413 op1);
6418 /* We have a special case here if we are doing something like
6419 (C * 8) % 4 since we know that's zero. */
6422 /* If the multiplication can overflow we cannot optimize this. */
6427 {
6430 }
6432 /* ... fall through ... */
6436 /* If we can extract our operation from the LHS, do so and return a
6437 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6438 do something only if the second operand is a constant. */
6454 /* If these are the same operation types, we can associate them
6455 assuming no overflow. */
6457 {
6472 }
6474 /* If these operations "cancel" each other, we have the main
6475 optimizations of this pass, which occur when either constant is a
6476 multiple of the other, in which case we replace this with either an
6477 operation or CODE or TCODE.
6479 If we have an unsigned type, we cannot do this since it will change
6480 the result if the original computation overflowed. */
6487 {
6490 {
6497 }
6500 {
6507 }
6508 }
6513 }
6516 }
6517 \f
6518 /* Return a node which has the indicated constant VALUE (either 0 or
6519 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6520 and is of the indicated TYPE. */
6522 tree
6524 {
6533 else
6535 }
6538 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6539 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6540 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6541 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6542 COND is the first argument to CODE; otherwise (as in the example
6543 given here), it is the second argument. TYPE is the type of the
6544 original expression. Return NULL_TREE if no simplification is
6545 possible. */
6547 static tree
6552 {
6562 {
6566 /* If this operand throws an expression, then it does not make
6567 sense to try to perform a logical or arithmetic operation
6568 involving it. */
6573 }
6576 {
6581 }
6582 else
6583 /* Detect the case of mixing vector and scalar types - bail out. */
6589 /* This transformation is only worthwhile if we don't have to wrap ARG
6590 in a SAVE_EXPR and the operation can be simplified without recursing
6591 on at least one of the branches once its pushed inside the COND_EXPR. */
6600 {
6604 else
6606 }
6608 {
6612 else
6614 }
6616 /* Check that we have simplified at least one of the branches. */
6621 }
6623 \f
6624 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6626 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6627 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6628 ADDEND is the same as X.
6630 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6631 and finite. The problematic cases are when X is zero, and its mode
6632 has signed zeros. In the case of rounding towards -infinity,
6633 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6634 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6636 bool
6638 {
6642 /* Don't allow the fold with -fsignaling-nans. */
6646 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6650 /* In a vector or complex, we would need to check the sign of all zeros. */
6654 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6658 /* The mode has signed zeros, and we have to honor their sign.
6659 In this situation, there is only one case we can return true for.
6660 X - 0 is the same as X unless rounding towards -infinity is
6661 supported. */
6663 }
6665 /* Subroutine of match.pd that optimizes comparisons of a division by
6666 a nonzero integer constant against an integer constant, i.e.
6667 X/C1 op C2.
6669 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6670 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6672 enum tree_code
6675 {
6680 /* We have to do this the hard way to detect unsigned overflow.
6681 prod = int_const_binop (MULT_EXPR, c1, c2); */
6687 {
6691 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6694 }
6696 {
6699 {
6718 }
6719 }
6720 else
6721 {
6722 /* A negative divisor reverses the relational operators. */
6727 {
6746 }
6747 }
6760 }
6763 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6764 equality/inequality test, then return a simplified form of the test
6765 using a sign testing. Otherwise return NULL. TYPE is the desired
6766 result type. */
6768 static tree
6771 tree result_type)
6772 {
6773 /* If this is testing a single bit, we can optimize the test. */
6777 {
6778 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6779 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6783 /* This is only a win if casting to a signed type is cheap,
6784 i.e. when arg00's type is not a partial mode. */
6786 {
6789 result_type,
6792 }
6793 }
6796 }
6798 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6799 equality/inequality test, then return a simplified form of
6800 the test using shifts and logical operations. Otherwise return
6801 NULL. TYPE is the desired result type. */
6803 tree
6806 {
6807 /* If this is testing a single bit, we can optimize the test. */
6811 {
6820 /* First, see if we can fold the single bit test into a sign-bit
6821 test. */
6823 result_type);
6827 /* Otherwise we have (A & C) != 0 where C is a single bit,
6828 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6829 Similarly for (A & C) == 0. */
6831 /* If INNER is a right shift of a constant and it plus BITNUM does
6832 not overflow, adjust BITNUM and INNER. */
6838 {
6841 }
6843 /* If we are going to be able to omit the AND below, we must do our
6844 operations as unsigned. If we must use the AND, we have a choice.
6845 Normally unsigned is faster, but for some machines signed is. */
6863 /* Put the AND last so it can combine with more things. */
6866 /* Make sure to return the proper type. */
6870 }
6872 }
6874 /* Test whether it is preferable two swap two operands, ARG0 and
6875 ARG1, for example because ARG0 is an integer constant and ARG1
6876 isn't. */
6878 bool
6880 {
6894 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6895 for commutative and comparison operators. Ensuring a canonical
6896 form allows the optimizers to find additional redundancies without
6897 having to explicitly check for both orderings. */
6903 /* Put SSA_NAMEs last. */
6909 /* Put variables last. */
6916 }
6919 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6920 means A >= Y && A != MAX, but in this case we know that
6921 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6923 static tree
6925 {
6932 else
6941 {
6944 }
6946 {
6949 }
6950 else
6957 {
6958 /* Convert the pointer types into integer before taking the difference. */
6962 }
6963 else
6970 }
6972 /* Fold a sum or difference of at least one multiplication.
6973 Returns the folded tree or NULL if no simplification could be made. */
6975 static tree
6978 {
6982 /* (A * C) +- (B * C) -> (A+-B) * C.
6983 (A * C) +- A -> A * (C+-1).
6984 We are most concerned about the case where C is a constant,
6985 but other combinations show up during loop reduction. Since
6986 it is not difficult, try all four possibilities. */
6989 {
6992 }
6994 {
6997 }
6998 else
6999 {
7000 /* We cannot generate constant 1 for fract. */
7005 }
7007 {
7010 }
7012 {
7014 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7015 the purpose of this canonicalization. */
7019 {
7022 }
7023 else
7025 }
7026 else
7027 {
7028 /* We cannot generate constant 1 for fract. */
7033 }
7036 /* Prefer factoring a common non-constant. */
7046 /* No identical multiplicands; see if we can find a common
7047 power-of-two factor in non-power-of-two multiplies. This
7048 can help in multi-dimensional array access. */
7051 {
7054 tree maybe_same;
7058 /* Move min of absolute values to int11. */
7060 {
7065 }
7066 else
7070 /* The remainder should not be a constant, otherwise we
7071 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7072 increased the number of multiplications necessary. */
7074 {
7082 }
7083 }
7090 /* We are neither factoring zero nor minus one. */
7098 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7099 same may be minus one and thus the multiplication may overflow. Perform
7100 the operations in an unsigned type. */
7105 /* If the sum evaluated to a constant that is not -INF the multiplication
7106 cannot overflow. */
7116 }
7118 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7119 specified by EXPR into the buffer PTR of length LEN bytes.
7120 Return the number of bytes placed in the buffer, or zero
7121 upon failure. */
7123 static int
7125 {
7137 /* Dry run. */
7143 {
7145 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7146 number of bytes. */
7150 {
7157 else
7159 }
7160 else
7164 }
7166 }
7169 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7170 specified by EXPR into the buffer PTR of length LEN bytes.
7171 Return the number of bytes placed in the buffer, or zero
7172 upon failure. */
7174 static int
7176 {
7180 FIXED_VALUE_TYPE value;
7195 }
7198 /* Subroutine of native_encode_expr. Encode the REAL_CST
7199 specified by EXPR into the buffer PTR of length LEN bytes.
7200 Return the number of bytes placed in the buffer, or zero
7201 upon failure. */
7203 static int
7205 {
7211 /* There are always 32 bits in each long, no matter the size of
7212 the hosts long. We handle floating point representations with
7213 up to 192 bits. */
7222 /* Dry run. */
7231 {
7236 {
7243 else
7245 }
7246 else
7247 {
7250 {
7251 /* Reverse bytes within each long, or within the entire float
7252 if it's smaller than a long (for HFmode). */
7255 }
7256 }
7261 }
7263 }
7265 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7266 specified by EXPR into the buffer PTR of length LEN bytes.
7267 Return the number of bytes placed in the buffer, or zero
7268 upon failure. */
7270 static int
7272 {
7274 tree part;
7288 }
7291 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7292 specified by EXPR into the buffer PTR of length LEN bytes.
7293 Return the number of bytes placed in the buffer, or zero
7294 upon failure. */
7296 static int
7298 {
7309 {
7311 {
7314 }
7325 }
7327 }
7330 /* Subroutine of native_encode_expr. Encode the STRING_CST
7331 specified by EXPR into the buffer PTR of length LEN bytes.
7332 Return the number of bytes placed in the buffer, or zero
7333 upon failure. */
7335 static int
7337 {
7340 /* Wide-char strings are encoded in target byte-order so native
7341 encoding them is trivial. */
7356 {
7359 {
7362 }
7365 }
7366 else
7369 }
7372 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7373 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7374 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7375 anything, just do a dry run. If OFF is not -1 then start
7376 the encoding at byte offset OFF and encode at most LEN bytes.
7377 Return the number of bytes placed in the buffer, or zero upon failure. */
7379 int
7381 {
7382 /* We don't support starting at negative offset and -1 is special. */
7387 {
7408 }
7409 }
7412 /* Subroutine of native_interpret_expr. Interpret the contents of
7413 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7414 If the buffer cannot be interpreted, return NULL_TREE. */
7416 static tree
7418 {
7428 }
7431 /* Subroutine of native_interpret_expr. Interpret the contents of
7432 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7433 If the buffer cannot be interpreted, return NULL_TREE. */
7435 static tree
7437 {
7440 double_int result;
7441 FIXED_VALUE_TYPE fixed_value;
7451 }
7454 /* Subroutine of native_interpret_expr. Interpret the contents of
7455 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7456 If the buffer cannot be interpreted, return NULL_TREE. */
7458 static tree
7460 {
7464 /* There are always 32 bits in each long, no matter the size of
7465 the hosts long. We handle floating point representations with
7466 up to 192 bits. */
7467 REAL_VALUE_TYPE r;
7477 {
7478 /* Both OFFSET and BYTE index within a long;
7479 bitpos indexes the whole float. */
7482 {
7489 else
7491 }
7492 else
7493 {
7496 {
7497 /* Reverse bytes within each long, or within the entire float
7498 if it's smaller than a long (for HFmode). */
7501 }
7502 }
7506 }
7510 }
7513 /* Subroutine of native_interpret_expr. Interpret the contents of
7514 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7515 If the buffer cannot be interpreted, return NULL_TREE. */
7517 static tree
7519 {
7534 }
7537 /* Subroutine of native_interpret_expr. Interpret the contents of
7538 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7539 If the buffer cannot be interpreted, return NULL_TREE. */
7541 static tree
7543 {
7556 {
7561 }
7563 }
7566 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7567 the buffer PTR of length LEN as a constant of type TYPE. For
7568 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7569 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7570 return NULL_TREE. */
7572 tree
7574 {
7576 {
7598 }
7599 }
7601 /* Returns true if we can interpret the contents of a native encoding
7602 as TYPE. */
7604 static bool
7606 {
7608 {
7621 }
7622 }
7625 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7626 TYPE at compile-time. If we're unable to perform the conversion
7627 return NULL_TREE. */
7629 static tree
7631 {
7632 /* We support up to 512-bit values (for V8DFmode). */
7636 /* Check that the host and target are sane. */
7645 }
7647 /* Build an expression for the address of T. Folds away INDIRECT_REF
7648 to avoid confusing the gimplify process. */
7650 tree
7652 {
7653 /* The size of the object is not relevant when talking about its address. */
7658 {
7663 }
7673 {
7678 }
7679 else
7683 }
7685 /* Build an expression for the address of T. */
7687 tree
7689 {
7693 }
7695 /* Fold a unary expression of code CODE and type TYPE with operand
7696 OP0. Return the folded expression if folding is successful.
7697 Otherwise, return NULL_TREE. */
7699 tree
7701 {
7702 tree tem;
7703 tree arg0;
7711 {
7714 {
7715 /* Don't use STRIP_NOPS, because signedness of argument type
7716 matters. */
7718 }
7719 else
7720 {
7721 /* Strip any conversions that don't change the mode. This
7722 is safe for every expression, except for a comparison
7723 expression because its signedness is derived from its
7724 operands.
7726 Note that this is done as an internal manipulation within
7727 the constant folder, in order to find the simplest
7728 representation of the arguments so that their form can be
7729 studied. In any cases, the appropriate type conversions
7730 should be put back in the tree that will get out of the
7731 constant folder. */
7733 }
7736 {
7739 {
7743 }
7744 }
7745 }
7752 {
7759 {
7773 /* If this was a conversion, and all we did was to move into
7774 inside the COND_EXPR, bring it back out. But leave it if
7775 it is a conversion from integer to integer and the
7776 result precision is no wider than a word since such a
7777 conversion is cheap and may be optimized away by combine,
7778 while it couldn't if it were outside the COND_EXPR. Then return
7779 so we don't get into an infinite recursion loop taking the
7780 conversion out and then back in. */
7792 && (INTEGRAL_TYPE_P
7805 }
7806 }
7809 {
7815 CASE_CONVERT:
7819 {
7820 /* If we have (type) (a CMP b) and type is an integral type, return
7821 new expression involving the new type. Canonicalize
7822 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7823 non-integral type.
7824 Do not fold the result as that would not simplify further, also
7825 folding again results in recursions. */
7835 }
7837 /* Handle (T *)&A.B.C for A being of type T and B and C
7838 living at offset zero. This occurs frequently in
7839 C++ upcasting and then accessing the base. */
7843 {
7845 tree offset;
7846 machine_mode mode;
7848 tree base
7852 /* If the reference was to a (constant) zero offset, we can use
7853 the address of the base if it has the same base type
7854 as the result type and the pointer type is unqualified. */
7862 }
7866 /* Detect assigning a bitfield. */
7868 && DECL_BIT_FIELD
7870 {
7871 /* Don't leave an assignment inside a conversion
7872 unless assigning a bitfield. */
7874 /* First do the assignment, then return converted constant. */
7879 }
7881 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7882 constants (if x has signed type, the sign bit cannot be set
7883 in c). This folds extension into the BIT_AND_EXPR.
7884 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7885 very likely don't have maximal range for their precision and this
7886 transformation effectively doesn't preserve non-maximal ranges. */
7890 {
7901 <= HOST_BITS_PER_WIDE_INT
7903 {
7907 cst &= HOST_WIDE_INT_M1U
7911 && !flag_syntax_only
7914 {
7918 }
7919 }
7921 {
7926 }
7927 }
7929 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7930 cast (T1)X will fold away. We assume that this happens when X itself
7931 is a cast. */
7935 {
7939 return fold_build_pointer_plus_loc
7941 }
7943 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7944 of the same precision, and X is an integer type not narrower than
7945 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7951 {
7957 }
7959 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7960 type of X and Y (integer types only). */
7965 {
7966 /* Be careful not to introduce new overflows. */
7967 tree mult_type;
7970 else
7974 {
7981 }
7982 }
7988 {
7995 }
8006 /* Convert fabs((double)float) into (double)fabsf(float). */
8009 {
8015 targ0));
8016 }
8020 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8039 /* Note that the operand of this must be an int
8040 and its values must be 0 or 1.
8041 ("true" is a fixed value perhaps depending on the language,
8042 but we don't handle values other than 1 correctly yet.) */
8049 /* Fold *&X to X if X is an lvalue. */
8051 {
8058 }
8064 }
8067 /* If the operation was a conversion do _not_ mark a resulting constant
8068 with TREE_OVERFLOW if the original constant was not. These conversions
8069 have implementation defined behavior and retaining the TREE_OVERFLOW
8070 flag here would confuse later passes such as VRP. */
8071 tree
8074 {
8083 }
8085 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8086 operands OP0 and OP1. LOC is the location of the resulting expression.
8087 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8088 Return the folded expression if folding is successful. Otherwise,
8089 return NULL_TREE. */
8090 static tree
8093 {
8094 tree tem;
8096 /* We only do these simplifications if we are optimizing. */
8100 /* Check for things like (A || B) && (A || C). We can convert this
8101 to A || (B && C). Note that either operator can be any of the four
8102 truth and/or operations and the transformation will still be
8103 valid. Also note that we only care about order for the
8104 ANDIF and ORIF operators. If B contains side effects, this
8105 might change the truth-value of A. */
8112 {
8132 /* This case if tricky because we must either have commutative
8133 operators or else A10 must not have side-effects. */
8139 a01);
8140 }
8142 /* See if we can build a range comparison. */
8148 {
8152 }
8156 {
8160 }
8162 /* Check for the possibility of merging component references. If our
8163 lhs is another similar operation, try to merge its rhs with our
8164 rhs. Then try to merge our lhs and rhs. */
8174 && !flag_sanitize_coverage
8179 {
8186 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8187 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8188 We don't want to pack more than two leafs to a non-IF AND/OR
8189 expression.
8190 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8191 equal to IF-CODE, then we don't want to add right-hand operand.
8192 If the inner right-hand side of left-hand operand has
8193 side-effects, or isn't simple, then we can't add to it,
8194 as otherwise we might destroy if-sequence. */
8197 /* Needed for sequence points to handle trappings, and
8198 side-effects. */
8200 {
8202 arg1);
8204 tem);
8205 }
8206 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8207 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8210 /* Needed for sequence points to handle trappings, and
8211 side-effects. */
8213 {
8218 }
8219 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8220 into (A OR B).
8221 For sequence point consistancy, we need to check for trapping,
8222 and side-effects. */
8226 }
8229 }
8231 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8232 by changing CODE to reduce the magnitude of constants involved in
8233 ARG0 of the comparison.
8234 Returns a canonicalized comparison tree if a simplification was
8235 possible, otherwise returns NULL_TREE.
8236 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8237 valid if signed overflow is undefined. */
8239 static tree
8243 {
8248 /* Match A +- CST code arg1. We can change this only if overflow
8249 is undefined. */
8252 /* In principle pointers also have undefined overflow behavior,
8253 but that causes problems elsewhere. */
8260 /* Identify the constant in arg0 and its sign. */
8264 /* Overflowed constants and zero will cause problems. */
8269 /* See if we can reduce the magnitude of the constant in
8270 arg0 by changing the comparison code. */
8271 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8275 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8279 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8283 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8287 else
8291 /* Now build the constant reduced in magnitude. But not if that
8292 would produce one outside of its types range. */
8308 }
8310 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8311 overflow further. Try to decrease the magnitude of constants involved
8312 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8313 and put sole constants at the second argument position.
8314 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8316 static tree
8319 {
8320 tree t;
8325 /* Try canonicalization by simplifying arg0. */
8330 {
8334 }
8336 /* Try canonicalization by simplifying arg1 using the swapped
8337 comparison. */
8345 }
8347 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8348 space. This is used to avoid issuing overflow warnings for
8349 expressions like &p->x which can not wrap. */
8351 static bool
8353 {
8360 poly_wide_int wi_offset;
8366 else
8371 precision);
8386 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8387 array. */
8396 }
8398 /* Return a positive integer when the symbol DECL is known to have
8399 a nonzero address, zero when it's known not to (e.g., it's a weak
8400 symbol), and a negative integer when the symbol is not yet in the
8401 symbol table and so whether or not its address is zero is unknown.
8402 For function local objects always return positive integer. */
8403 static int
8405 {
8410 /* Function local objects are never NULL. */
8418 }
8420 /* Subroutine of fold_binary. This routine performs all of the
8421 transformations that are common to the equality/inequality
8422 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8423 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8424 fold_binary should call fold_binary. Fold a comparison with
8425 tree code CODE and type TYPE with operands OP0 and OP1. Return
8426 the folded comparison or NULL_TREE. */
8428 static tree
8431 {
8441 /* For comparisons of pointers we can decompose it to a compile time
8442 comparison of the base objects and the offsets into the object.
8443 This requires at least one operand being an ADDR_EXPR or a
8444 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8450 {
8453 machine_mode mode;
8457 /* Get base and offset for the access. Strip ADDR_EXPR for
8458 get_inner_reference, but put it back by stripping INDIRECT_REF
8459 off the base object if possible. indirect_baseN will be true
8460 if baseN is not an address but refers to the object itself. */
8463 {
8464 base0
8470 else
8472 }
8474 {
8478 {
8479 base0
8485 else
8487 }
8490 else
8494 {
8501 }
8502 }
8506 {
8507 base1
8513 else
8515 }
8517 {
8521 {
8522 base1
8528 else
8530 }
8533 else
8537 {
8544 }
8545 }
8547 /* If we have equivalent bases we might be able to simplify. */
8551 {
8552 /* We can fold this expression to a constant if the non-constant
8553 offset parts are equal. */
8557 && (equality_code
8558 || (indirect_base0
8561 {
8567 "occur when comparing P +- C1 with "
8569 WARN_STRICT_OVERFLOW_CONDITIONAL);
8572 {
8610 }
8611 }
8612 /* We can simplify the comparison to a comparison of the variable
8613 offset parts if the constant offset parts are equal.
8614 Be careful to use signed sizetype here because otherwise we
8615 mess with array offsets in the wrong way. This is possible
8616 because pointer arithmetic is restricted to retain within an
8617 object and overflow on pointer differences is undefined as of
8618 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8620 && (equality_code
8621 || (indirect_base0
8624 {
8625 /* By converting to signed sizetype we cover middle-end pointer
8626 arithmetic which operates on unsigned pointer types of size
8627 type size and ARRAY_REF offsets which are properly sign or
8628 zero extended from their type in case it is narrower than
8629 sizetype. */
8632 else
8636 else
8643 "occur when comparing P +- C1 with "
8645 WARN_STRICT_OVERFLOW_COMPARISON);
8648 }
8649 }
8650 /* For equal offsets we can simplify to a comparison of the
8651 base addresses. */
8653 && (indirect_base0
8655 && (indirect_base1
8660 {
8666 }
8667 /* Comparison between an ordinary (non-weak) symbol and a null
8668 pointer can be eliminated since such symbols must have a non
8669 null address. In C, relational expressions between pointers
8670 to objects and null pointers are undefined. The results
8671 below follow the C++ rules with the additional property that
8672 every object pointer compares greater than a null pointer.
8673 */
8676 /* Avoid folding references to struct members at offset 0 to
8677 prevent tests like '&ptr->firstmember == 0' from getting
8678 eliminated. When ptr is null, although the -> expression
8679 is strictly speaking invalid, GCC retains it as a matter
8680 of QoI. See PR c/44555. */
8683 && indirect_base0
8684 /* The caller guarantees that when one of the arguments is
8685 constant (i.e., null in this case) it is second. */
8687 {
8689 {
8700 }
8701 }
8702 }
8704 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8705 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8706 the resulting offset is smaller in absolute value than the
8707 original one and has the same sign. */
8716 {
8721 tree cst;
8723 "occur when combining constants around "
8726 /* Put the constant on the side where it doesn't overflow and is
8727 of lower absolute value and of same sign than before. */
8734 {
8737 variable1,
8741 }
8749 {
8755 variable2);
8756 }
8757 }
8763 /* If we are comparing an expression that just has comparisons
8764 of two integer values, arithmetic expressions of those comparisons,
8765 and constants, we can simplify it. There are only three cases
8766 to check: the two values can either be equal, the first can be
8767 greater, or the second can be greater. Fold the expression for
8768 those three values. Since each value must be 0 or 1, we have
8769 eight possibilities, each of which corresponds to the constant 0
8770 or 1 or one of the six possible comparisons.
8772 This handles common cases like (a > b) == 0 but also handles
8773 expressions like ((x > y) - (y > x)) > 0, which supposedly
8774 occur in macroized code. */
8777 {
8782 /* Don't handle degenerate cases here; they should already
8783 have been handled anyway. */
8792 {
8796 /* We can't just pass T to eval_subst in case cval1 or cval2
8797 was the same as ARG1. */
8799 tree high_result
8803 arg1);
8804 tree equal_result
8808 arg1);
8809 tree low_result
8813 arg1);
8815 /* All three of these results should be 0 or 1. Confirm they are.
8816 Then use those values to select the proper code to use. */
8821 {
8822 /* Make a 3-bit mask with the high-order bit being the
8823 value for `>', the next for '=', and the low for '<'. */
8827 {
8829 /* Always false. */
8850 /* Always true. */
8852 }
8855 {
8859 }
8861 }
8862 }
8863 }
8866 }
8869 /* Subroutine of fold_binary. Optimize complex multiplications of the
8870 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8871 argument EXPR represents the expression "z" of type TYPE. */
8873 static tree
8875 {
8880 {
8883 }
8885 {
8888 }
8889 else
8890 {
8894 }
8903 }
8906 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8907 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8908 true if successful. */
8910 static bool
8912 {
8917 {
8920 }
8922 {
8928 else
8930 }
8931 else
8937 }
8939 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8940 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8941 NULL_TREE otherwise. */
8943 static tree
8945 {
8966 {
8967 HOST_WIDE_INT index;
8973 }
8976 {
8982 }
8983 else
8985 }
8987 /* Try to fold a pointer difference of type TYPE two address expressions of
8988 array references AREF0 and AREF1 using location LOC. Return a
8989 simplified expression for the difference or NULL_TREE. */
8991 static tree
8995 {
9000 /* If the bases are array references as well, recurse. If the bases
9001 are pointer indirections compute the difference of the pointers.
9002 If the bases are equal, we are set. */
9005 && (base_offset
9007 use_pointer_diff)))
9010 && (base_offset
9011 = use_pointer_diff
9021 {
9027 base_offset,
9030 }
9032 }
9034 /* If the real or vector real constant CST of type TYPE has an exact
9035 inverse, return it, else return NULL. */
9037 tree
9039 {
9040 REAL_VALUE_TYPE r;
9041 tree unit_type;
9042 machine_mode mode;
9045 {
9055 {
9059 tree_vector_builder elts;
9064 {
9069 }
9072 }
9076 }
9077 }
9079 /* Mask out the tz least significant bits of X of type TYPE where
9080 tz is the number of trailing zeroes in Y. */
9081 static wide_int
9083 {
9088 }
9090 /* Return true when T is an address and is known to be nonzero.
9091 For floating point we further ensure that T is not denormal.
9092 Similar logic is present in nonzero_address in rtlanal.h.
9094 If the return value is based on the assumption that signed overflow
9095 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9096 change *STRICT_OVERFLOW_P. */
9098 static bool
9100 {
9104 /* Doing something useful for floating point would need more work. */
9110 {
9113 strict_overflow_p);
9119 strict_overflow_p);
9127 }
9130 {
9133 strict_overflow_p);
9141 strict_overflow_p);
9156 strict_overflow_p);
9160 strict_overflow_p);
9163 {
9175 }
9179 }
9181 }
9183 /* Return true when T is an address and is known to be nonzero.
9184 Handle warnings about undefined signed overflow. */
9186 bool
9188 {
9195 "determining that expression is always "
9197 WARN_STRICT_OVERFLOW_MISC);
9199 }
9201 /* Return true if T is known not to be equal to an integer W. */
9203 bool
9205 {
9207 value_range_type rtype;
9209 {
9218 {
9223 }
9228 /* If T has some known zero bits and W has any of those bits set,
9229 then T is known not to be equal to W. */
9237 }
9238 }
9240 /* Fold a binary expression of code CODE and type TYPE with operands
9241 OP0 and OP1. LOC is the location of the resulting expression.
9242 Return the folded expression if folding is successful. Otherwise,
9243 return NULL_TREE. */
9245 tree
9248 {
9263 /* Strip any conversions that don't change the mode. This is
9264 safe for every expression, except for a comparison expression
9265 because its signedness is derived from its operands. So, in
9266 the latter case, only strip conversions that don't change the
9267 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9268 preserved.
9270 Note that this is done as an internal manipulation within the
9271 constant folder, in order to find the simplest representation
9272 of the arguments so that their form can be studied. In any
9273 cases, the appropriate type conversions should be put back in
9274 the tree that will get out of the constant folder. */
9277 {
9280 }
9281 else
9282 {
9285 }
9287 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9288 constant but we can't do arithmetic on them. */
9290 {
9293 {
9297 }
9298 }
9300 /* If this is a commutative operation, and ARG0 is a constant, move it
9301 to ARG1 to reduce the number of tests below. */
9306 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9307 to ARG1 to reduce the number of tests below. */
9316 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9318 First check for cases where an arithmetic operation is applied to a
9319 compound, conditional, or comparison operation. Push the arithmetic
9320 operation inside the compound or conditional to see if any folding
9321 can then be done. Convert comparison to conditional for this purpose.
9322 The also optimizes non-constant cases that used to be done in
9323 expand_expr.
9325 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9326 one of the operands is a comparison and the other is a comparison, a
9327 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9328 code below would make the expression more complex. Change it to a
9329 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9330 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9343 {
9347 boolean_type_node,
9355 }
9359 {
9361 {
9366 tem);
9367 }
9369 {
9374 tem);
9375 }
9380 {
9386 }
9391 {
9397 }
9398 }
9401 {
9403 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9406 {
9412 }
9414 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9417 {
9418 tree base;
9419 poly_int64 coffset;
9428 }
9433 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9439 arg1),
9441 arg0)));
9447 {
9448 /* X + (X / CST) * -CST is X % CST. */
9453 {
9462 cst0));
9463 }
9464 }
9466 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9467 one. Make sure the type is not saturating and has the signedness of
9468 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9469 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9476 {
9480 }
9483 {
9484 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9485 (plus (plus (mult) (mult)) (foo)) so that we can
9486 take advantage of the factoring cases below. */
9495 {
9501 else
9514 parg0),
9516 marg)),
9520 return
9526 parg1)));
9527 }
9528 }
9529 else
9530 {
9531 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9532 to __complex__ ( x, y ). This is not the same for SNaNs or
9533 if signed zeros are involved. */
9537 {
9544 {
9548 {
9554 }
9556 {
9562 }
9563 }
9564 }
9566 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9567 We associate floats only if the user has specified
9568 -fassociative-math. */
9572 {
9577 {
9578 tree tree0;
9581 }
9582 }
9583 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9584 We associate floats only if the user has specified
9585 -fassociative-math. */
9589 {
9594 {
9595 tree tree0;
9598 }
9599 }
9600 }
9602 bit_rotate:
9603 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9604 is a rotate of A by C1 bits. */
9605 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9606 is a rotate of A by B bits.
9607 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9608 though in this case CODE must be | and not + or ^, otherwise
9609 it doesn't return A when B is 0. */
9610 {
9612 tree rtype;
9621 /* Only create rotates in complete modes. Other cases are not
9622 expanded properly. */
9625 {
9638 {
9643 }
9648 {
9651 code0 == LSHIFT_EXPR
9654 }
9656 {
9666 {
9670 orig_tree01);
9672 }
9673 }
9677 {
9688 {
9692 orig_tree01);
9694 }
9695 }
9696 }
9697 }
9699 associate:
9700 /* In most languages, can't associate operations on floats through
9701 parentheses. Rather than remember where the parentheses were, we
9702 don't associate floats at all, unless the user has specified
9703 -fassociative-math.
9704 And, we need to make sure type is not saturating. */
9708 {
9714 /* Split both trees into variables, constants, and literals. Then
9715 associate each group together, the constants with literals,
9716 then the result with variables. This increases the chances of
9717 literals being recombined later and of generating relocatable
9718 expressions for the sum of a constant and literal. */
9726 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9730 /* With undefined overflow prefer doing association in a type
9731 which wraps on overflow, if that is one of the operand types. */
9734 {
9742 }
9744 /* With undefined overflow we can only associate constants with one
9745 variable, and constants whose association doesn't overflow. */
9748 {
9750 {
9751 /* ??? If split_tree would handle NEGATE_EXPR we could
9752 simply reject these cases and the allowed cases would
9753 be the var0/minus_var1 ones. */
9759 {
9762 }
9769 {
9772 }
9778 /* The only case we can still associate with two variables
9779 is if they cancel out. */
9783 }
9789 }
9791 /* Only do something if we found more than two objects. Otherwise,
9792 nothing has changed and we risk infinite recursion. */
9800 {
9812 {
9816 }
9818 {
9822 }
9824 /* Preserve the MINUS_EXPR if the negative part of the literal is
9825 greater than the positive part. Otherwise, the multiplicative
9826 folding code (i.e extract_muldiv) may be fooled in case
9827 unsigned constants are subtracted, like in the following
9828 example: ((X*2 + 4) - 8U)/2. */
9830 {
9834 /* But avoid ending up with only negated parts. */
9836 {
9840 }
9841 else
9842 {
9846 }
9847 }
9849 /* Don't introduce overflows through reassociation. */
9854 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9861 /* Eliminate minus_con0. */
9863 {
9870 else
9873 }
9875 /* Eliminate minus_var0. */
9877 {
9881 else
9884 }
9886 return
9889 }
9890 }
9896 /* Fold &a[i] - &a[j] to i-j. */
9901 {
9905 code
9909 }
9911 /* Further transformations are not for pointers. */
9915 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9918 /* If arg0 is e.g. unsigned int and type is int, then this could
9919 introduce UB, because if A is INT_MIN at runtime, the original
9920 expression can be well defined while the latter is not.
9921 See PR83269. */
9930 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9931 __complex__ ( x, -y ). This is not the same for SNaNs or if
9932 signed zeros are involved. */
9936 {
9943 {
9947 {
9949 arg1r ? arg1r
9954 }
9956 {
9960 arg1i ? arg1i
9963 }
9964 }
9965 }
9967 /* A - B -> A + (-B) if B is easily negatable. */
9971 /* Avoid this transformation if B is a positive REAL_CST. */
9979 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9980 one. Make sure the type is not saturating and has the signedness of
9981 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9982 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9989 {
9993 }
9999 {
10000 /* Transform x * -C into -x * C if x is easily negatable. */
10015 {
10018 "occur when simplifying "
10020 WARN_STRICT_OVERFLOW_MISC);
10022 }
10024 /* Optimize z * conj(z) for integer complex numbers. */
10031 }
10032 else
10033 {
10034 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10035 This is not the same for NaNs or if signed zeros are
10036 involved. */
10042 {
10045 return
10051 return
10056 }
10058 /* Optimize z * conj(z) for floating point complex numbers.
10059 Guarded by flag_unsafe_math_optimizations as non-finite
10060 imaginary components don't produce scalar results. */
10069 }
10073 /* Canonicalize (X & C1) | C2. */
10077 {
10082 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10090 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10092 {
10095 }
10097 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10098 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10099 mode which allows further optimizations. */
10104 {
10109 {
10112 }
10113 }
10116 {
10121 }
10122 }
10124 /* See if this can be simplified into a rotate first. If that
10125 is unsuccessful continue in the association code. */
10129 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10137 /* See if this can be simplified into a rotate first. If that
10138 is unsuccessful continue in the association code. */
10142 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10147 {
10148 tree tem2;
10155 }
10156 /* Fold ~X & 1 as (X & 1) == 0. */
10160 {
10161 tree tem2;
10168 }
10169 /* Fold !X & 1 as X == 0. */
10172 {
10176 }
10178 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10179 multiple of 1 << CST. */
10181 {
10188 }
10190 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10191 bits from CST2. */
10195 {
10197 wide_int masked
10204 {
10205 /* Avoid the transform if arg1 is a mask of some
10206 mode which allows further optimizations. */
10213 }
10214 }
10216 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10217 ((A & N) + B) & M -> (A + B) & M
10218 Similarly if (N & M) == 0,
10219 ((A | N) + B) & M -> (A + B) & M
10220 and for - instead of + (or unary - instead of +)
10221 and/or ^ instead of |.
10222 If B is constant and (B & M) == 0, fold into A & M. */
10224 {
10233 {
10236 wide_int cst0;
10238 /* Now we know that arg0 is (C + D) or (C - D) or
10239 -C and arg1 (M) is == (1LL << cst) - 1.
10240 Store C into PMOP[0] and D into PMOP[1]. */
10244 {
10247 }
10254 {
10263 {
10266 }
10269 /* If C or D is of the form (A & N) where
10270 (N & M) == M, or of the form (A | N) or
10271 (A ^ N) where (N & M) == 0, replace it with A. */
10275 /* If C or D is a N where (N & M) == 0, it can be
10276 omitted (assumed 0). */
10284 }
10286 /* Only build anything new if we optimized one or both arguments
10287 above. */
10291 {
10294 {
10295 /* Perform the operations in a type that has defined
10296 overflow behavior. */
10302 }
10307 {
10315 else
10317 }
10320 else
10323 /* TEM is now the new binary +, - or unary - replacement. */
10327 }
10328 }
10329 }
10331 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10334 {
10339 return
10341 }
10346 /* Don't touch a floating-point divide by zero unless the mode
10347 of the constant can represent infinity. */
10353 /* (-A) / (-B) -> A / B */
10365 /* Fall through */
10368 /* Simplify A / (B << N) where A and B are positive and B is
10369 a power of 2, to A >> (N + log2(B)). */
10374 {
10377 {
10385 WARN_STRICT_OVERFLOW_MISC);
10391 }
10392 }
10394 /* Fall through */
10402 /* Convert -A / -B to A / B when the type is signed and overflow is
10403 undefined. */
10407 {
10410 "when distributing negation across "
10412 WARN_STRICT_OVERFLOW_MISC);
10417 }
10421 {
10424 "when distributing negation across "
10426 WARN_STRICT_OVERFLOW_MISC);
10431 }
10433 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10434 operation, EXACT_DIV_EXPR.
10436 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10437 At one time others generated faster code, it's not clear if they do
10438 after the last round to changes to the DIV code in expmed.c. */
10449 {
10453 WARN_STRICT_OVERFLOW_MISC);
10455 }
10467 {
10471 WARN_STRICT_OVERFLOW_MISC);
10473 }
10481 /* Since negative shift count is not well-defined,
10482 don't try to compute it in the compiler. */
10488 /* If we have a rotate of a bit operation with the rotate count and
10489 the second operand of the bit operation both constant,
10490 permute the two operations. */
10496 {
10504 }
10506 /* Two consecutive rotates adding up to the some integer
10507 multiple of the precision of the type can be ignored. */
10523 /* Note that the operands of this must be ints
10524 and their values must be 0 or 1.
10525 ("true" is a fixed value perhaps depending on the language.) */
10526 /* If first arg is constant zero, return it. */
10529 /* FALLTHRU */
10531 /* If either arg is constant true, drop it. */
10535 /* Preserve sequence points. */
10538 /* If second arg is constant zero, result is zero, but first arg
10539 must be evaluated. */
10542 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10543 case will be handled here. */
10547 /* !X && X is always false. */
10551 /* X && !X is always false. */
10556 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10557 means A >= Y && A != MAX, but in this case we know that
10558 A < X <= MAX. */
10562 {
10570 }
10579 /* Note that the operands of this must be ints
10580 and their values must be 0 or true.
10581 ("true" is a fixed value perhaps depending on the language.) */
10582 /* If first arg is constant true, return it. */
10585 /* FALLTHRU */
10587 /* If either arg is constant zero, drop it. */
10591 /* Preserve sequence points. */
10594 /* If second arg is constant true, result is true, but we must
10595 evaluate first arg. */
10598 /* Likewise for first arg, but note this only occurs here for
10599 TRUTH_OR_EXPR. */
10603 /* !X || X is always true. */
10607 /* X || !X is always true. */
10612 /* (X && !Y) || (!X && Y) is X ^ Y */
10615 {
10632 }
10641 /* If the second arg is constant zero, drop it. */
10644 /* If the second arg is constant true, this is a logical inversion. */
10646 {
10649 }
10650 /* Identical arguments cancel to zero. */
10654 /* !X ^ X is always true. */
10659 /* X ^ !X is always true. */
10675 /* bool_var != 1 becomes !bool_var. */
10682 /* bool_var == 0 becomes !bool_var. */
10689 /* !exp != 0 becomes !exp */
10694 /* If this is an EQ or NE comparison with zero and ARG0 is
10695 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10696 two operations, but the latter can be done in one less insn
10697 on machines that have only two-operand insns or on which a
10698 constant cannot be the first operand. */
10701 {
10706 {
10713 arg1);
10714 }
10717 {
10724 arg1);
10725 }
10726 }
10728 /* If this is an NE or EQ comparison of zero against the result of a
10729 signed MOD operation whose second operand is a power of 2, make
10730 the MOD operation unsigned since it is simpler and equivalent. */
10738 {
10748 }
10750 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10751 C1 is a valid shift constant, and C2 is a power of two, i.e.
10752 a single bit. */
10756 == INTEGER_CST
10759 {
10764 /* Check for a valid shift count. */
10766 {
10770 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10771 can be rewritten as (X & (C2 << C1)) != 0. */
10773 {
10778 }
10779 /* Otherwise, for signed (arithmetic) shifts,
10780 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10781 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10785 /* Otherwise, of unsigned (logical) shifts,
10786 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10787 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10788 else
10792 arg000);
10793 }
10794 }
10796 /* If this is a comparison of a field, we may be able to simplify it. */
10799 /* Handle the constant case even without -O
10800 to make sure the warnings are given. */
10802 {
10806 }
10808 /* Optimize comparisons of strlen vs zero to a compare of the
10809 first character of the string vs zero. To wit,
10810 strlen(ptr) == 0 => *ptr == 0
10811 strlen(ptr) != 0 => *ptr != 0
10812 Other cases should reduce to one of these two (or a constant)
10813 due to the return value of strlen being unsigned. */
10816 {
10824 {
10829 }
10830 }
10832 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10833 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10837 {
10842 {
10844 {
10847 }
10850 }
10851 }
10853 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10854 (X & C) == 0 when C is a single bit. */
10859 {
10866 arg1));
10867 }
10869 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10870 constant C is a power of two, i.e. a single bit. */
10877 {
10881 }
10883 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10884 when is C is a power of two, i.e. a single bit. */
10891 {
10897 }
10901 {
10904 }
10906 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10909 {
10917 {
10923 }
10925 {
10931 }
10933 {
10939 }
10941 {
10947 }
10948 }
10952 {
10959 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10960 operand_equal_p guarantees no side-effects so we don't need
10961 to use omit_one_operand on Z. */
10965 arg10));
10969 arg11));
10973 arg10));
10977 arg11));
10979 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10982 {
10988 }
10989 }
10991 /* Attempt to simplify equality/inequality comparisons of complex
10992 values. Only lower the comparison if the result is known or
10993 can be simplified to a single scalar comparison. */
10998 {
11003 {
11006 }
11007 else
11008 {
11011 }
11014 {
11017 }
11018 else
11019 {
11022 }
11026 {
11028 {
11033 }
11034 else
11035 {
11040 }
11041 }
11045 {
11047 {
11052 }
11053 else
11054 {
11059 }
11060 }
11061 }
11073 /* Transform comparisons of the form X +- C CMP X. */
11078 {
11083 /* (X - c) > X becomes false. */
11089 /* Likewise (X + c) < X becomes false. */
11095 /* Convert (X - c) <= X to true. */
11102 /* Convert (X + c) >= X to true. */
11108 }
11110 /* If we are comparing an ABS_EXPR with a constant, we can
11111 convert all the cases into explicit comparisons, but they may
11112 well not be faster than doing the ABS and one comparison.
11113 But ABS (X) <= C is a range comparison, which becomes a subtraction
11114 and a comparison, and is probably faster. */
11128 /* Convert ABS_EXPR<x> >= 0 to true. */
11135 {
11138 "when simplifying comparison of "
11140 WARN_STRICT_OVERFLOW_CONDITIONAL);
11143 arg0);
11144 }
11146 /* Convert ABS_EXPR<x> < 0 to false. */
11151 {
11154 "when simplifying comparison of "
11156 WARN_STRICT_OVERFLOW_CONDITIONAL);
11159 arg0);
11160 }
11162 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11163 and similarly for >= into !=. */
11173 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11174 otherwise Y might be >= # of bits in X's type and thus e.g.
11175 (unsigned char) (1 << Y) for Y 15 might be 0.
11176 If the cast is widening, then 1 << Y should have unsigned type,
11177 otherwise if Y is number of bits in the signed shift type minus 1,
11178 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11179 31 might be 0xffffffff80000000. */
11190 {
11196 }
11208 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11209 {
11221 }
11226 /* When pedantic, a compound expression can be neither an lvalue
11227 nor an integer constant expression. */
11230 /* Don't let (0, 0) be null pointer constant. */
11236 /* An ASSERT_EXPR should never be passed to fold_binary. */
11242 }
11244 /* Used by contains_label_[p1]. */
11246 struct contains_label_data
11247 {
11250 };
11252 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11253 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11254 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11256 static tree
11258 {
11261 {
11272 {
11280 }
11289 }
11290 }
11292 /* Return whether the sub-tree ST contains a label which is accessible from
11293 outside the sub-tree. */
11295 static bool
11297 {
11301 }
11303 /* Fold a ternary expression of code CODE and type TYPE with operands
11304 OP0, OP1, and OP2. Return the folded expression if folding is
11305 successful. Otherwise, return NULL_TREE. */
11307 tree
11310 {
11311 tree tem;
11318 /* If this is a commutative operation, and OP0 is a constant, move it
11319 to OP1 to reduce the number of tests below. */
11328 /* Strip any conversions that don't change the mode. This is safe
11329 for every expression, except for a comparison expression because
11330 its signedness is derived from its operands. So, in the latter
11331 case, only strip conversions that don't change the signedness.
11333 Note that this is done as an internal manipulation within the
11334 constant folder, in order to find the simplest representation of
11335 the arguments so that their form can be studied. In any cases,
11336 the appropriate type conversions should be put back in the tree
11337 that will get out of the constant folder. */
11339 {
11342 }
11345 {
11348 }
11351 {
11354 }
11357 {
11361 {
11367 }
11372 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11373 so all simple results must be passed through pedantic_non_lvalue. */
11375 {
11378 /* Only optimize constant conditions when the selected branch
11379 has the same type as the COND_EXPR. This avoids optimizing
11380 away "c ? x : throw", where the throw has a void type.
11381 Avoid throwing away that operand which contains label. */
11388 }
11390 {
11397 {
11400 {
11408 }
11413 }
11414 }
11416 /* If we have A op B ? A : C, we may be able to convert this to a
11417 simpler expression, depending on the operation and the values
11418 of B and C. Signed zeros prevent all of these transformations,
11419 for reasons given above each one.
11421 Also try swapping the arguments and inverting the conditional. */
11425 {
11429 }
11434 {
11438 {
11442 }
11443 }
11445 /* If the second operand is simpler than the third, swap them
11446 since that produces better jump optimization results. */
11449 {
11451 /* See if this can be inverted. If it can't, possibly because
11452 it was a floating-point inequality comparison, don't do
11453 anything. */
11457 }
11459 /* Convert A ? 1 : 0 to simply A. */
11464 /* If we try to convert OP0 to our type, the
11465 call to fold will try to move the conversion inside
11466 a COND, which will recurse. In that case, the COND_EXPR
11467 is probably the best choice, so leave it alone. */
11471 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11472 over COND_EXPR in cases such as floating point comparisons. */
11481 arg0)));
11483 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11488 {
11489 /* sign_bit_p looks through both zero and sign extensions,
11490 but for this optimization only sign extensions are
11491 usable. */
11494 {
11497 {
11500 }
11502 }
11503 /* sign_bit_p only checks ARG1 bits within A's precision.
11504 If <sign bit of A> has wider type than A, bits outside
11505 of A's precision in <sign bit of A> need to be checked.
11506 If they are all 0, this optimization needs to be done
11507 in unsigned A's type, if they are all 1 in signed A's type,
11508 otherwise this can't be done. */
11514 {
11516 tree tem_type;
11529 {
11532 }
11534 {
11537 }
11538 else
11540 }
11543 return
11549 arg1)));
11550 }
11552 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11553 already handled above. */
11558 {
11568 op1);
11569 }
11571 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11572 is probably obsolete because the first operand should be a
11573 truth value (that's why we have the two cases above), but let's
11574 leave it in until we can confirm this for all front-ends. */
11586 /* Disable the transformations below for vectors, since
11587 fold_binary_op_with_conditional_arg may undo them immediately,
11588 yielding an infinite loop. */
11592 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11601 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11606 {
11608 /* Only perform transformation if ARG0 is easily inverted. */
11612 ? BIT_IOR_EXPR
11615 op1);
11616 }
11618 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11623 {
11625 /* Only perform transformation if ARG0 is easily inverted. */
11631 op2);
11632 }
11634 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11646 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11647 of fold_ternary on them. */
11657 {
11668 {
11673 {
11681 }
11682 }
11683 }
11685 /* On constants we can use native encode/interpret to constant
11686 fold (nearly) all BIT_FIELD_REFs. */
11692 {
11695 /* Limit us to a reasonable amount of work. To relax the
11696 other limitations we need bit-shifting of the buffer
11697 and rounding up the size. */
11701 {
11703 unsigned HOST_WIDE_INT len
11708 {
11713 }
11714 }
11715 }
11720 /* For integers we can decompose the FMA if possible. */
11732 {
11733 /* Build a vector of integers from the tree mask. */
11734 vec_perm_builder builder;
11738 /* Create a vec_perm_indices for the integer vector. */
11743 /* Check for cases that fold to OP0 or OP1 in their original
11744 element order. */
11751 {
11755 {
11758 }
11759 }
11765 {
11769 }
11773 /* Generate a canonical form of the selector. */
11775 {
11776 /* Some targets are deficient and fail to expand a single
11777 argument permutation while still allowing an equivalent
11778 2-argument version. */
11782 else
11783 {
11787 else
11788 /* Not directly supported with either encoding,
11789 so use the preferred form. */
11791 }
11793 }
11797 }
11801 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11804 {
11810 wide_int tem2
11814 }
11819 {
11821 unsigned HOST_WIDE_INT elsize
11824 {
11830 {
11836 }
11837 }
11838 }
11844 }
11846 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11847 of an array (or vector). */
11849 tree
11851 {
11856 {
11859 {
11860 /* Static constructors for variably sized objects makes no sense. */
11864 }
11865 }
11876 offset_int max_index;
11881 {
11882 /* Array constructor might explicitly set index, or specify a range,
11883 or leave index NULL meaning that it is next index after previous
11884 one. */
11886 {
11889 else
11890 {
11894 }
11895 }
11896 else
11897 {
11903 }
11905 /* Do we have match? */
11909 }
11911 }
11913 /* Perform constant folding and related simplification of EXPR.
11914 The related simplifications include x*1 => x, x*0 => 0, etc.,
11915 and application of the associative law.
11916 NOP_EXPR conversions may be removed freely (as long as we
11917 are careful not to change the type of the overall expression).
11918 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11919 but we can constant-fold them if they have constant operands. */
11921 #ifdef ENABLE_FOLD_CHECKING
11922 # define fold(x) fold_1 (x)
11924 static
11925 #endif
11926 tree
11928 {
11932 tree tem;
11935 /* Return right away if a constant. */
11939 /* CALL_EXPR-like objects with variable numbers of operands are
11940 treated specially. */
11942 {
11944 {
11947 }
11949 }
11952 {
11957 {
11975 }
11976 }
11979 {
11981 {
11988 {
11993 }
11996 }
11998 /* Return a VECTOR_CST if possible. */
12000 {
12006 tree val;
12012 }
12020 }
12022 #ifdef ENABLE_FOLD_CHECKING
12023 #undef fold
12030 /* When --enable-checking=fold, compute a digest of expr before
12031 and after actual fold call to see if fold did not accidentally
12032 change original expr. */
12034 tree
12036 {
12037 tree ret;
12057 }
12059 void
12061 {
12072 }
12074 static void
12076 {
12078 }
12080 static void
12083 {
12089 recursive_label:
12099 {
12100 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12105 }
12113 {
12114 /* Allow these fields to be modified. */
12115 tree tmp;
12124 {
12127 }
12128 }
12139 {
12142 {
12158 }
12162 {
12175 }
12192 {
12198 }
12201 {
12203 {
12206 }
12208 }
12219 {
12222 }
12232 }
12233 }
12235 /* Helper function for outputting the checksum of a tree T. When
12236 debugging with gdb, you can "define mynext" to be "next" followed
12237 by "call debug_fold_checksum (op0)", then just trace down till the
12238 outputs differ. */
12240 DEBUG_FUNCTION void
12242 {
12257 }
12259 #endif
12261 /* Fold a unary tree expression with code CODE of type TYPE with an
12262 operand OP0. LOC is the location of the resulting expression.
12263 Return a folded expression if successful. Otherwise, return a tree
12264 expression with code CODE of type TYPE with an operand OP0. */
12266 tree
12269 {
12270 tree tem;
12271 #ifdef ENABLE_FOLD_CHECKING
12280 #endif
12286 #ifdef ENABLE_FOLD_CHECKING
12293 #endif
12295 }
12297 /* Fold a binary tree expression with code CODE of type TYPE with
12298 operands OP0 and OP1. LOC is the location of the resulting
12299 expression. Return a folded expression if successful. Otherwise,
12300 return a tree expression with code CODE of type TYPE with operands
12301 OP0 and OP1. */
12303 tree
12306 MEM_STAT_DECL)
12307 {
12308 tree tem;
12309 #ifdef ENABLE_FOLD_CHECKING
12326 #endif
12332 #ifdef ENABLE_FOLD_CHECKING
12347 #endif
12349 }
12351 /* Fold a ternary tree expression with code CODE of type TYPE with
12352 operands OP0, OP1, and OP2. Return a folded expression if
12353 successful. Otherwise, return a tree expression with code CODE of
12354 type TYPE with operands OP0, OP1, and OP2. */
12356 tree
12359 {
12360 tree tem;
12361 #ifdef ENABLE_FOLD_CHECKING
12385 #endif
12392 #ifdef ENABLE_FOLD_CHECKING
12415 #endif
12417 }
12419 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12420 arguments in ARGARRAY, and a null static chain.
12421 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12422 of type TYPE from the given operands as constructed by build_call_array. */
12424 tree
12427 {
12428 tree tem;
12429 #ifdef ENABLE_FOLD_CHECKING
12448 #endif
12454 #ifdef ENABLE_FOLD_CHECKING
12470 #endif
12472 }
12474 /* Perform constant folding and related simplification of initializer
12475 expression EXPR. These behave identically to "fold_buildN" but ignore
12476 potential run-time traps and exceptions that fold must preserve. */
12478 #define START_FOLD_INIT \
12479 int saved_signaling_nans = flag_signaling_nans;\
12480 int saved_trapping_math = flag_trapping_math;\
12481 int saved_rounding_math = flag_rounding_math;\
12482 int saved_trapv = flag_trapv;\
12483 int saved_folding_initializer = folding_initializer;\
12484 flag_signaling_nans = 0;\
12485 flag_trapping_math = 0;\
12486 flag_rounding_math = 0;\
12487 flag_trapv = 0;\
12488 folding_initializer = 1;
12490 #define END_FOLD_INIT \
12491 flag_signaling_nans = saved_signaling_nans;\
12492 flag_trapping_math = saved_trapping_math;\
12493 flag_rounding_math = saved_rounding_math;\
12494 flag_trapv = saved_trapv;\
12495 folding_initializer = saved_folding_initializer;
12497 tree
12500 {
12501 tree result;
12502 START_FOLD_INIT;
12506 END_FOLD_INIT;
12508 }
12510 tree
12513 {
12514 tree result;
12515 START_FOLD_INIT;
12519 END_FOLD_INIT;
12521 }
12523 tree
12526 {
12527 tree result;
12528 START_FOLD_INIT;
12532 END_FOLD_INIT;
12534 }
12536 #undef START_FOLD_INIT
12537 #undef END_FOLD_INIT
12539 /* Determine if first argument is a multiple of second argument. Return 0 if
12540 it is not, or we cannot easily determined it to be.
12542 An example of the sort of thing we care about (at this point; this routine
12543 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12544 fold cases do now) is discovering that
12546 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12548 is a multiple of
12550 SAVE_EXPR (J * 8)
12552 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12554 This code also handles discovering that
12556 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12558 is a multiple of 8 so we don't have to worry about dealing with a
12559 possible remainder.
12561 Note that we *look* inside a SAVE_EXPR only to determine how it was
12562 calculated; it is not safe for fold to do much of anything else with the
12563 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12564 at run time. For example, the latter example above *cannot* be implemented
12565 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12566 evaluation time of the original SAVE_EXPR is not necessarily the same at
12567 the time the new expression is evaluated. The only optimization of this
12568 sort that would be valid is changing
12570 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12572 divided by 8 to
12574 SAVE_EXPR (I) * SAVE_EXPR (J)
12576 (where the same SAVE_EXPR (J) is used in the original and the
12577 transformed version). */
12579 int
12581 {
12592 {
12594 /* Bitwise and provides a power of two multiple. If the mask is
12595 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12603 {
12609 {
12612 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12614 {
12618 {
12621 }
12622 }
12624 }
12625 }
12630 /* It is impossible to prove if op0 - op1 is multiple of bottom
12631 precisely, so be conservative here checking if both op0 and op1
12632 are multiple of bottom. Note we check the second operand first
12633 since it's usually simpler. */
12638 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12639 as op0 - 3 if the expression has unsigned type. For example,
12640 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12650 {
12652 /* const_binop may not detect overflow correctly,
12653 so check for it explicitly here. */
12661 }
12665 /* Can't handle conversions from non-integral or wider integral type. */
12671 /* fall through */
12688 SIGNED);
12694 {
12697 /* Check for special cases to see if top is defined as multiple
12698 of bottom:
12700 top = (X & ~(bottom - 1) ; bottom is power of 2
12702 or
12704 Y = X % bottom
12705 top = X - Y. */
12724 }
12726 /* fall through */
12734 }
12735 }
12737 #define tree_expr_nonnegative_warnv_p(X, Y) \
12740 #define RECURSE(X) \
12741 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12743 /* Return true if CODE or TYPE is known to be non-negative. */
12745 static bool
12747 {
12750 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12751 have a signed:1 type (where the value is -1 and 0). */
12754 }
12756 /* Return true if (CODE OP0) is known to be non-negative. If the return
12757 value is based on the assumption that signed overflow is undefined,
12758 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12759 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12761 bool
12764 {
12769 {
12771 /* We can't return 1 if flag_wrapv is set because
12772 ABS_EXPR<INT_MIN> = INT_MIN. */
12776 {
12779 }
12787 CASE_CONVERT:
12788 {
12793 {
12797 {
12801 }
12802 }
12804 {
12810 }
12811 }
12816 }
12818 /* We don't know sign of `t', so be conservative and return false. */
12820 }
12822 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12823 value is based on the assumption that signed overflow is undefined,
12824 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12825 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12827 bool
12831 {
12836 {
12842 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12843 both unsigned and at least 2 bits shorter than the result. */
12847 {
12852 {
12856 }
12857 }
12862 {
12863 /* x * x is always non-negative for floating point x
12864 or without overflow. */
12867 {
12872 }
12873 }
12875 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12876 both unsigned and their total bits is shorter than the result. */
12880 {
12899 {
12909 }
12910 }
12937 }
12939 /* We don't know sign of `t', so be conservative and return false. */
12941 }
12943 /* Return true if T is known to be non-negative. If the return
12944 value is based on the assumption that signed overflow is undefined,
12945 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12946 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12948 bool
12950 {
12955 {
12969 /* Limit the depth of recursion to avoid quadratic behavior.
12970 This is expected to catch almost all occurrences in practice.
12971 If this code misses important cases that unbounded recursion
12972 would not, passes that need this information could be revised
12973 to provide it through dataflow propagation. */
12981 }
12982 }
12984 /* Return true if T is known to be non-negative. If the return
12985 value is based on the assumption that signed overflow is undefined,
12986 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12987 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12989 bool
12992 {
12994 {
12995 CASE_CFN_ACOS:
12996 CASE_CFN_ACOSH:
12997 CASE_CFN_CABS:
12998 CASE_CFN_COSH:
12999 CASE_CFN_ERFC:
13000 CASE_CFN_EXP:
13001 CASE_CFN_EXP10:
13002 CASE_CFN_EXP2:
13003 CASE_CFN_FABS:
13004 CASE_CFN_FDIM:
13005 CASE_CFN_HYPOT:
13006 CASE_CFN_POW10:
13007 CASE_CFN_FFS:
13008 CASE_CFN_PARITY:
13009 CASE_CFN_POPCOUNT:
13010 CASE_CFN_CLZ:
13011 CASE_CFN_CLRSB:
13014 /* Always true. */
13017 CASE_CFN_SQRT:
13018 CASE_CFN_SQRT_FN:
13019 /* sqrt(-0.0) is -0.0. */
13024 CASE_CFN_ASINH:
13025 CASE_CFN_ATAN:
13026 CASE_CFN_ATANH:
13027 CASE_CFN_CBRT:
13028 CASE_CFN_CEIL:
13029 CASE_CFN_CEIL_FN:
13030 CASE_CFN_ERF:
13031 CASE_CFN_EXPM1:
13032 CASE_CFN_FLOOR:
13033 CASE_CFN_FLOOR_FN:
13034 CASE_CFN_FMOD:
13035 CASE_CFN_FREXP:
13036 CASE_CFN_ICEIL:
13037 CASE_CFN_IFLOOR:
13038 CASE_CFN_IRINT:
13039 CASE_CFN_IROUND:
13040 CASE_CFN_LCEIL:
13041 CASE_CFN_LDEXP:
13042 CASE_CFN_LFLOOR:
13043 CASE_CFN_LLCEIL:
13044 CASE_CFN_LLFLOOR:
13045 CASE_CFN_LLRINT:
13046 CASE_CFN_LLROUND:
13047 CASE_CFN_LRINT:
13048 CASE_CFN_LROUND:
13049 CASE_CFN_MODF:
13050 CASE_CFN_NEARBYINT:
13051 CASE_CFN_NEARBYINT_FN:
13052 CASE_CFN_RINT:
13053 CASE_CFN_RINT_FN:
13054 CASE_CFN_ROUND:
13055 CASE_CFN_ROUND_FN:
13056 CASE_CFN_SCALB:
13057 CASE_CFN_SCALBLN:
13058 CASE_CFN_SCALBN:
13059 CASE_CFN_SIGNBIT:
13060 CASE_CFN_SIGNIFICAND:
13061 CASE_CFN_SINH:
13062 CASE_CFN_TANH:
13063 CASE_CFN_TRUNC:
13064 CASE_CFN_TRUNC_FN:
13065 /* True if the 1st argument is nonnegative. */
13068 CASE_CFN_FMAX:
13069 CASE_CFN_FMAX_FN:
13070 /* True if the 1st OR 2nd arguments are nonnegative. */
13073 CASE_CFN_FMIN:
13074 CASE_CFN_FMIN_FN:
13075 /* True if the 1st AND 2nd arguments are nonnegative. */
13078 CASE_CFN_COPYSIGN:
13079 CASE_CFN_COPYSIGN_FN:
13080 /* True if the 2nd argument is nonnegative. */
13083 CASE_CFN_POWI:
13084 /* True if the 1st argument is nonnegative or the second
13085 argument is an even integer. */
13091 CASE_CFN_POW:
13092 /* True if the 1st argument is nonnegative or the second
13093 argument is an even integer valued real. */
13095 {
13096 REAL_VALUE_TYPE c;
13097 HOST_WIDE_INT n;
13102 {
13103 REAL_VALUE_TYPE cint;
13107 }
13108 }
13113 }
13115 }
13117 /* Return true if T is known to be non-negative. If the return
13118 value is based on the assumption that signed overflow is undefined,
13119 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13120 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13122 static bool
13124 {
13130 {
13132 {
13136 /* If the initializer is non-void, then it's a normal expression
13137 that will be assigned to the slot. */
13141 /* Otherwise, the initializer sets the slot in some way. One common
13142 way is an assignment statement at the end of the initializer. */
13144 {
13152 else
13154 }
13160 }
13163 {
13169 arg0,
13170 arg1,
13172 }
13185 }
13186 }
13188 #undef RECURSE
13189 #undef tree_expr_nonnegative_warnv_p
13191 /* Return true if T is known to be non-negative. If the return
13192 value is based on the assumption that signed overflow is undefined,
13193 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13194 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13196 bool
13198 {
13205 {
13227 }
13230 {
13256 }
13257 }
13259 /* Return true if `t' is known to be non-negative. Handle warnings
13260 about undefined signed overflow. */
13262 bool
13264 {
13271 "determining that expression is always "
13273 WARN_STRICT_OVERFLOW_MISC);
13275 }
13278 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13279 For floating point we further ensure that T is not denormal.
13280 Similar logic is present in nonzero_address in rtlanal.h.
13282 If the return value is based on the assumption that signed overflow
13283 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13284 change *STRICT_OVERFLOW_P. */
13286 bool
13289 {
13291 {
13294 strict_overflow_p);
13297 {
13303 strict_overflow_p));
13304 }
13309 strict_overflow_p);
13313 }
13316 }
13318 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13319 For floating point we further ensure that T is not denormal.
13320 Similar logic is present in nonzero_address in rtlanal.h.
13322 If the return value is based on the assumption that signed overflow
13323 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13324 change *STRICT_OVERFLOW_P. */
13326 bool
13328 tree type,
13329 tree op0,
13331 {
13334 {
13338 {
13339 /* With the presence of negative values it is hard
13340 to say something. */
13347 /* One of operands must be positive and the other non-negative. */
13348 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13349 overflows, on a twos-complement machine the sum of two
13350 nonnegative numbers can never be zero. */
13352 strict_overflow_p)
13354 strict_overflow_p));
13355 }
13360 {
13362 strict_overflow_p)
13364 strict_overflow_p))
13365 {
13368 }
13369 }
13378 {
13381 }
13388 {
13392 /* When both operands are nonzero, then MAX must be too. */
13394 strict_overflow_p))
13397 /* MAX where operand 0 is positive is positive. */
13399 strict_overflow_p);
13400 }
13401 /* MAX where operand 1 is positive is positive. */
13406 {
13410 }
13415 strict_overflow_p)
13417 strict_overflow_p));
13421 }
13424 }
13426 /* Return true when T is an address and is known to be nonzero.
13427 For floating point we further ensure that T is not denormal.
13428 Similar logic is present in nonzero_address in rtlanal.h.
13430 If the return value is based on the assumption that signed overflow
13431 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13432 change *STRICT_OVERFLOW_P. */
13434 bool
13436 {
13439 {
13444 {
13456 /* For objects in symbol table check if we know they are non-zero.
13457 Don't do anything for variables and functions before symtab is built;
13458 it is quite possible that they will be declared weak later. */
13463 /* Constants are never weak. */
13468 }
13476 {
13480 }
13490 }
13492 }
13494 #define integer_valued_real_p(X) \
13497 #define RECURSE(X) \
13498 ((integer_valued_real_p) (X, depth + 1))
13500 /* Return true if the floating point result of (CODE OP0) has an
13501 integer value. We also allow +Inf, -Inf and NaN to be considered
13502 integer values. Return false for signaling NaN.
13504 DEPTH is the current nesting depth of the query. */
13506 bool
13508 {
13510 {
13517 CASE_CONVERT:
13518 {
13525 }
13529 }
13531 }
13533 /* Return true if the floating point result of (CODE OP0 OP1) has an
13534 integer value. We also allow +Inf, -Inf and NaN to be considered
13535 integer values. Return false for signaling NaN.
13537 DEPTH is the current nesting depth of the query. */
13539 bool
13541 {
13543 {
13553 }
13555 }
13557 /* Return true if the floating point result of calling FNDECL with arguments
13558 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13559 considered integer values. Return false for signaling NaN. If FNDECL
13560 takes fewer than 2 arguments, the remaining ARGn are null.
13562 DEPTH is the current nesting depth of the query. */
13564 bool
13566 {
13568 {
13569 CASE_CFN_CEIL:
13570 CASE_CFN_CEIL_FN:
13571 CASE_CFN_FLOOR:
13572 CASE_CFN_FLOOR_FN:
13573 CASE_CFN_NEARBYINT:
13574 CASE_CFN_NEARBYINT_FN:
13575 CASE_CFN_RINT:
13576 CASE_CFN_RINT_FN:
13577 CASE_CFN_ROUND:
13578 CASE_CFN_ROUND_FN:
13579 CASE_CFN_TRUNC:
13580 CASE_CFN_TRUNC_FN:
13583 CASE_CFN_FMIN:
13584 CASE_CFN_FMIN_FN:
13585 CASE_CFN_FMAX:
13586 CASE_CFN_FMAX_FN:
13591 }
13593 }
13595 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13596 has an integer value. We also allow +Inf, -Inf and NaN to be
13597 considered integer values. Return false for signaling NaN.
13599 DEPTH is the current nesting depth of the query. */
13601 bool
13603 {
13605 {
13613 /* Limit the depth of recursion to avoid quadratic behavior.
13614 This is expected to catch almost all occurrences in practice.
13615 If this code misses important cases that unbounded recursion
13616 would not, passes that need this information could be revised
13617 to provide it through dataflow propagation. */
13621 depth));
13625 }
13627 }
13629 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13630 has an integer value. We also allow +Inf, -Inf and NaN to be
13631 considered integer values. Return false for signaling NaN.
13633 DEPTH is the current nesting depth of the query. */
13635 static bool
13637 {
13639 {
13650 }
13652 }
13654 #undef RECURSE
13655 #undef integer_valued_real_p
13657 /* Return true if the floating point expression T has an integer value.
13658 We also allow +Inf, -Inf and NaN to be considered integer values.
13659 Return false for signaling NaN.
13661 DEPTH is the current nesting depth of the query. */
13663 bool
13665 {
13671 {
13687 }
13690 {
13696 {
13705 }
13709 }
13710 }
13712 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13713 attempt to fold the expression to a constant without modifying TYPE,
13714 OP0 or OP1.
13716 If the expression could be simplified to a constant, then return
13717 the constant. If the expression would not be simplified to a
13718 constant, then return NULL_TREE. */
13720 tree
13722 {
13725 }
13727 /* Given the components of a unary expression CODE, TYPE and OP0,
13728 attempt to fold the expression to a constant without modifying
13729 TYPE or OP0.
13731 If the expression could be simplified to a constant, then return
13732 the constant. If the expression would not be simplified to a
13733 constant, then return NULL_TREE. */
13735 tree
13737 {
13740 }
13742 /* If EXP represents referencing an element in a constant string
13743 (either via pointer arithmetic or array indexing), return the
13744 tree representing the value accessed, otherwise return NULL. */
13746 tree
13748 {
13752 {
13754 tree index;
13755 tree string;
13760 else
13761 {
13765 /* Optimize the special-case of a zero lower bound.
13767 We convert the low_bound to sizetype to avoid some problems
13768 with constant folding. (E.g. suppose the lower bound is 1,
13769 and its mode is QI. Without the conversion,l (ARRAY
13770 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13771 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13777 }
13779 scalar_int_mode char_mode;
13791 }
13793 }
13795 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13796 an integer constant, real, or fixed-point constant.
13798 TYPE is the type of the result. */
13800 static tree
13802 {
13806 {
13812 {
13813 FIXED_VALUE_TYPE f;
13818 /* Propagate overflow flags. */
13822 }
13826 {
13833 }
13836 }
13839 }
13841 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13842 an integer constant or real constant.
13844 TYPE is the type of the result. */
13846 tree
13848 {
13852 {
13854 {
13855 /* If the value is unsigned or non-negative, then the absolute value
13856 is the same as the ordinary value. */
13860 /* If the value is negative, then the absolute value is
13861 its negation. */
13862 else
13863 {
13868 }
13869 }
13875 else
13881 }
13884 }
13886 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13887 constant. TYPE is the type of the result. */
13889 static tree
13891 {
13895 }
13897 /* Given CODE, a relational operator, the target type, TYPE and two
13898 constant operands OP0 and OP1, return the result of the
13899 relational operation. If the result is not a compile time
13900 constant, then return NULL_TREE. */
13902 static tree
13904 {
13907 /* From here on, the only cases we handle are when the result is
13908 known to be a constant. */
13911 {
13915 /* Handle the cases where either operand is a NaN. */
13917 {
13919 {
13947 }
13950 }
13953 }
13956 {
13960 }
13962 /* Handle equality/inequality of complex constants. */
13964 {
13975 else
13977 }
13980 {
13982 {
13983 /* Have vector comparison with scalar boolean result. */
13991 {
13999 }
14001 }
14002 tree_vector_builder elts;
14007 {
14020 }
14023 }
14025 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14027 To compute GT, swap the arguments and do LT.
14028 To compute GE, do LT and invert the result.
14029 To compute LE, swap the arguments, do LT and invert the result.
14030 To compute NE, do EQ and invert the result.
14032 Therefore, the code below must handle only EQ and LT. */
14035 {
14038 }
14040 /* Note that it is safe to invert for real values here because we
14041 have already handled the one case that it matters. */
14045 {
14048 }
14050 /* Compute a result for LT or EQ if args permit;
14051 Otherwise return T. */
14053 {
14056 else
14058 }
14059 else
14065 }
14067 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14068 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14069 itself. */
14071 tree
14073 {
14074 /* If the expression does not have side effects then we don't have to wrap
14075 it with a cleanup point expression. */
14079 /* If the expression is a return, check to see if the expression inside the
14080 return has no side effects or the right hand side of the modify expression
14081 inside the return. If either don't have side effects set we don't need to
14082 wrap the expression in a cleanup point expression. Note we don't check the
14083 left hand side of the modify because it should always be a return decl. */
14085 {
14092 }
14095 }
14097 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14098 of an indirection through OP0, or NULL_TREE if no simplification is
14099 possible. */
14101 tree
14103 {
14105 tree subtype;
14106 poly_uint64 const_op01;
14115 {
14118 /* *&CONST_DECL -> to the value of the const decl. */
14121 /* *&p => p; make sure to handle *&"str"[cst] here. */
14123 {
14127 else
14129 }
14130 /* *(foo *)&fooarray => fooarray[0] */
14133 && (!in_gimple_form
14135 {
14145 }
14146 /* *(foo *)&complexfoo => __real__ complexfoo */
14150 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14153 {
14157 }
14158 }
14162 {
14168 {
14169 tree op00type;
14173 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14176 {
14178 poly_uint64 max_offset
14182 {
14187 }
14188 }
14189 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14192 {
14194 const_op01))
14196 }
14197 /* ((foo *)&fooarray)[1] => fooarray[1] */
14200 {
14207 offset_int remainder;
14210 {
14215 }
14216 }
14217 }
14218 }
14220 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14223 && (!in_gimple_form
14225 {
14226 tree type_domain;
14236 NULL_TREE);
14237 }
14240 }
14242 /* Builds an expression for an indirection through T, simplifying some
14243 cases. */
14245 tree
14247 {
14255 }
14257 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14259 tree
14261 {
14266 else
14268 }
14270 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14271 whose result is ignored. The type of the returned tree need not be
14272 the same as the original expression. */
14274 tree
14276 {
14282 {
14293 else
14299 {
14315 }
14320 }
14321 }
14323 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14325 tree
14327 {
14333 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14334 have to do anything. Only do this when we are not given a const,
14335 because in that case, this check is more expensive than just
14336 doing it. */
14338 {
14343 }
14345 /* If divisor is a power of two, simplify this to bit manipulation. */
14347 {
14349 {
14363 }
14364 else
14365 {
14366 tree t;
14372 }
14373 }
14374 else
14375 {
14380 }
14383 }
14385 /* Likewise, but round down. */
14387 tree
14389 {
14396 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14397 have to do anything. Only do this when we are not given a const,
14398 because in that case, this check is more expensive than just
14399 doing it. */
14401 {
14406 }
14408 /* If divisor is a power of two, simplify this to bit manipulation. */
14410 {
14411 tree t;
14415 }
14416 else
14417 {
14422 }
14425 }
14427 /* Returns the pointer to the base of the object addressed by EXP and
14428 extracts the information about the offset of the access, storing it
14429 to PBITPOS and POFFSET. */
14431 static tree
14434 {
14435 tree core;
14436 machine_mode mode;
14438 poly_int64 bitsize;
14442 {
14447 }
14449 {
14455 {
14456 poly_offset_int tem
14462 }
14463 }
14464 else
14465 {
14469 }
14472 }
14474 /* Returns true if addresses of E1 and E2 differ by a constant, false
14475 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14477 bool
14479 {
14494 {
14504 }
14506 {
14507 /* If only one of the offsets is non-constant, the difference cannot
14508 be a constant. */
14510 }
14511 else
14516 }
14518 /* Return OFF converted to a pointer offset type suitable as offset for
14519 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14520 tree
14522 {
14524 }
14526 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14527 tree
14529 {
14532 }
14534 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14535 tree
14537 {
14540 }
14542 /* Return a char pointer for a C string if it is a string constant
14543 or sum of string constant and integer constant. We only support
14544 string constants properly terminated with '\0' character.
14545 If STRLEN is a valid pointer, length (including terminating character)
14546 of returned string is stored to the argument. */
14550 {
14551 tree offset_node;
14562 {
14565 else
14567 }
14572 /* Support only properly null-terminated strings. */
14581 }
14583 #if CHECKING_P
14587 /* Helper functions for writing tests of folding trees. */
14589 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14591 static void
14593 tree constant)
14594 {
14596 }
14598 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14599 wrapping WRAPPED_EXPR. */
14601 static void
14603 tree wrapped_expr)
14604 {
14609 }
14611 /* Verify that various arithmetic binary operations are folded
14612 correctly. */
14614 static void
14616 {
14622 /* Addition. */
14623 /* 1 <-- (0 + 1) */
14625 one);
14627 one);
14629 /* (nonlvalue)x <-- (x + 0) */
14631 x);
14633 /* Subtraction. */
14634 /* 0 <-- (x - x) */
14636 zero);
14638 x);
14640 /* Multiplication. */
14641 /* 0 <-- (x * 0) */
14643 zero);
14645 /* (nonlvalue)x <-- (x * 1) */
14647 x);
14648 }
14650 /* Verify that various binary operations on vectors are folded
14651 correctly. */
14653 static void
14655 {
14661 /* Verify equality tests that return a scalar boolean result. */
14667 }
14669 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14671 static void
14673 {
14676 /* This will be 1 if VEC_MODE isn't a vector mode. */
14683 }
14685 /* Run all of the selftests within this file. */
14687 void
14689 {
14693 }