| blob | 014c7d4aab6731352de5859706f1b754294d0d29 |
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 flags & (OEP_LEXICOGRAPHIC
3485 }
3486 }
3491 {
3502 }
3506 }
3508 #undef OP_SAME
3509 #undef OP_SAME_WITH_NULL
3510 }
3511 \f
3512 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3513 with a different signedness or a narrower precision. */
3515 static bool
3517 {
3525 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3526 and see if the inner values are the same. This removes any
3527 signedness comparison, which doesn't matter here. */
3535 /* Discard a single widening conversion from ARG1 and see if the inner
3536 value is the same as ARG0. */
3545 }
3546 \f
3547 /* See if ARG is an expression that is either a comparison or is performing
3548 arithmetic on comparisons. The comparisons must only be comparing
3549 two different values, which will be stored in *CVAL1 and *CVAL2; if
3550 they are nonzero it means that some operands have already been found.
3551 No variables may be used anywhere else in the expression except in the
3552 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3553 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3555 If this is true, return 1. Otherwise, return zero. */
3557 static int
3559 {
3563 /* We can handle some of the tcc_expression cases here. */
3573 {
3574 /* If we've already found a CVAL1 or CVAL2, this expression is
3575 two complex to handle. */
3581 }
3584 {
3607 /* First see if we can handle the first operand, then the second. For
3608 the second operand, we know *CVAL1 can't be zero. It must be that
3609 one side of the comparison is each of the values; test for the
3610 case where this isn't true by failing if the two operands
3611 are the same. */
3620 ;
3624 ;
3625 else
3629 ;
3633 ;
3634 else
3641 }
3642 }
3643 \f
3644 /* ARG is a tree that is known to contain just arithmetic operations and
3645 comparisons. Evaluate the operations in the tree substituting NEW0 for
3646 any occurrence of OLD0 as an operand of a comparison and likewise for
3647 NEW1 and OLD1. */
3649 static tree
3652 {
3657 /* We can handle some of the tcc_expression cases here. */
3665 {
3680 {
3699 }
3700 /* Fall through - ??? */
3703 {
3707 /* We need to check both for exact equality and tree equality. The
3708 former will be true if the operand has a side-effect. In that
3709 case, we know the operand occurred exactly once. */
3722 }
3726 }
3727 }
3728 \f
3729 /* Return a tree for the case when the result of an expression is RESULT
3730 converted to TYPE and OMITTED was previously an operand of the expression
3731 but is now not needed (e.g., we folded OMITTED * 0).
3733 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3734 the conversion of RESULT to TYPE. */
3736 tree
3738 {
3741 /* If the resulting operand is an empty statement, just return the omitted
3742 statement casted to void. */
3752 }
3754 /* Return a tree for the case when the result of an expression is RESULT
3755 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3756 of the expression but are now not needed.
3758 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3759 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3760 evaluated before OMITTED2. Otherwise, if neither has side effects,
3761 just do the conversion of RESULT to TYPE. */
3763 tree
3766 {
3775 }
3777 \f
3778 /* Return a simplified tree node for the truth-negation of ARG. This
3779 never alters ARG itself. We assume that ARG is an operation that
3780 returns a truth value (0 or 1).
3782 FIXME: one would think we would fold the result, but it causes
3783 problems with the dominator optimizer. */
3785 static tree
3787 {
3792 /* If this is a comparison, we can simply invert it, except for
3793 floating-point non-equality comparisons, in which case we just
3794 enclose a TRUTH_NOT_EXPR around what we have. */
3797 {
3800 && flag_trapping_math
3814 }
3817 {
3836 /* Here we can invert either operand. We invert the first operand
3837 unless the second operand is a TRUTH_NOT_EXPR in which case our
3838 result is the XOR of the first operand with the inside of the
3839 negation of the second operand. */
3844 else
3867 {
3874 /* A COND_EXPR may have a throw as one operand, which
3875 then has void type. Just leave void operands
3876 as they are. */
3882 }
3894 CASE_CONVERT:
3898 /* fall through */
3920 }
3921 }
3923 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3924 assume that ARG is an operation that returns a truth value (0 or 1
3925 for scalars, 0 or -1 for vectors). Return the folded expression if
3926 folding is successful. Otherwise, return NULL_TREE. */
3928 static tree
3930 {
3933 ? BIT_NOT_EXPR
3936 }
3938 /* Return a simplified tree node for the truth-negation of ARG. This
3939 never alters ARG itself. We assume that ARG is an operation that
3940 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3942 tree
3944 {
3950 ? BIT_NOT_EXPR
3953 }
3954 \f
3955 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3956 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3957 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3958 is the original memory reference used to preserve the alias set of
3959 the access. */
3961 static tree
3965 {
3968 /* Attempt not to lose the access path if possible. */
3970 {
3972 machine_mode nmode;
3974 tree noffset;
3982 && !reversep
3983 && !nreversep
3985 {
3988 }
3989 }
3998 {
4005 }
4020 }
4022 /* Optimize a bit-field compare.
4024 There are two cases: First is a compare against a constant and the
4025 second is a comparison of two items where the fields are at the same
4026 bit position relative to the start of a chunk (byte, halfword, word)
4027 large enough to contain it. In these cases we can avoid the shift
4028 implicit in bitfield extractions.
4030 For constants, we emit a compare of the shifted constant with the
4031 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4032 compared. For two fields at the same position, we do the ANDs with the
4033 similar mask and compare the result of the ANDs.
4035 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4036 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4037 are the left and right operands of the comparison, respectively.
4039 If the optimization described above can be done, we return the resulting
4040 tree. Otherwise we return zero. */
4042 static tree
4045 {
4049 tree unsigned_type;
4052 scalar_int_mode nmode;
4057 tree mask;
4058 tree offset;
4060 /* Get all the information about the extractions being done. If the bit size
4061 is the same as the size of the underlying object, we aren't doing an
4062 extraction at all and so can do nothing. We also don't want to
4063 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4064 then will no longer be able to replace it. */
4079 else
4080 {
4081 /* If this is not a constant, we can only do something if bit positions,
4082 sizes, signedness and storage order are the same. */
4083 rinner
4096 }
4098 /* Honor the C++ memory model and mimic what RTL expansion does. */
4102 {
4106 }
4108 /* See if we can find a mode to refer to this field. We should be able to,
4109 but fail if we can't. */
4117 /* Set signed and unsigned types of the precision of this mode for the
4118 shifts below. */
4121 /* Compute the bit position and size for the new reference and our offset
4122 within it. If the new reference is the same size as the original, we
4123 won't optimize anything, so return zero. */
4133 /* Make the mask to be used against the extracted field. */
4140 {
4144 /* If not comparing with constant, just rework the comparison
4145 and return. */
4153 }
4155 /* Otherwise, we are handling the constant case. See if the constant is too
4156 big for the field. Warn and return a tree for 0 (false) if so. We do
4157 this not only for its own sake, but to avoid having to test for this
4158 error case below. If we didn't, we might generate wrong code.
4160 For unsigned fields, the constant shifted right by the field length should
4161 be all zero. For signed fields, the high-order bits should agree with
4162 the sign bit. */
4165 {
4167 {
4171 }
4172 }
4173 else
4174 {
4177 {
4181 }
4182 }
4187 /* Single-bit compares should always be against zero. */
4189 {
4192 }
4194 /* Make a new bitfield reference, shift the constant over the
4195 appropriate number of bits and mask it with the computed mask
4196 (in case this was a signed field). If we changed it, make a new one. */
4204 mask);
4209 }
4210 \f
4211 /* Subroutine for fold_truth_andor_1: decode a field reference.
4213 If EXP is a comparison reference, we return the innermost reference.
4215 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4216 set to the starting bit number.
4218 If the innermost field can be completely contained in a mode-sized
4219 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4221 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4222 otherwise it is not changed.
4224 *PUNSIGNEDP is set to the signedness of the field.
4226 *PREVERSEP is set to the storage order of the field.
4228 *PMASK is set to the mask used. This is either contained in a
4229 BIT_AND_EXPR or derived from the width of the field.
4231 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4233 Return 0 if this is not a component reference or is one that we can't
4234 do anything with. */
4236 static tree
4241 {
4246 tree unsigned_type;
4249 /* All the optimizations using this function assume integer fields.
4250 There are problems with FP fields since the type_for_size call
4251 below can fail for, e.g., XFmode. */
4255 /* We are interested in the bare arrangement of bits, so strip everything
4256 that doesn't affect the machine mode. However, record the type of the
4257 outermost expression if it may matter below. */
4264 {
4270 }
4281 /* Reject out-of-bound accesses (PR79731). */
4289 /* If the number of bits in the reference is the same as the bitsize of
4290 the outer type, then the outer type gives the signedness. Otherwise
4291 (in case of a small bitfield) the signedness is unchanged. */
4295 /* Compute the mask to access the bitfield. */
4304 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4312 }
4314 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4315 bit positions and MASK is SIGNED. */
4317 static int
4319 {
4323 /* If this function returns true when the type of the mask is
4324 UNSIGNED, then there will be errors. In particular see
4325 gcc.c-torture/execute/990326-1.c. There does not appear to be
4326 any documentation paper trail as to why this is so. But the pre
4327 wide-int worked with that restriction and it has been preserved
4328 here. */
4333 }
4335 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4336 represents the sign bit of EXP's type. If EXP represents a sign
4337 or zero extension, also test VAL against the unextended type.
4338 The return value is the (sub)expression whose sign bit is VAL,
4339 or NULL_TREE otherwise. */
4341 tree
4343 {
4345 tree t;
4347 /* Tree EXP must have an integral type. */
4352 /* Tree VAL must be an integer constant. */
4361 /* Handle extension from a narrower type. */
4367 }
4369 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4370 to be evaluated unconditionally. */
4372 static int
4374 {
4375 /* Strip any conversions that don't change the machine mode. */
4384 /* Don't regard global variables as simple. They may be
4385 allocated in ways unknown to the compiler (shared memory,
4386 #pragma weak, etc). */
4389 /* Weakrefs are not safe to be read, since they can be NULL.
4390 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4391 have DECL_WEAK flag set. */
4393 /* Loading a static variable is unduly expensive, but global
4394 registers aren't expensive. */
4396 }
4398 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4399 to be evaluated unconditionally.
4400 I addition to simple_operand_p, we assume that comparisons, conversions,
4401 and logic-not operations are simple, if their operands are simple, too. */
4403 static bool
4405 {
4425 }
4427 \f
4428 /* The following functions are subroutines to fold_range_test and allow it to
4429 try to change a logical combination of comparisons into a range test.
4431 For example, both
4432 X == 2 || X == 3 || X == 4 || X == 5
4433 and
4434 X >= 2 && X <= 5
4435 are converted to
4436 (unsigned) (X - 2) <= 3
4438 We describe each set of comparisons as being either inside or outside
4439 a range, using a variable named like IN_P, and then describe the
4440 range with a lower and upper bound. If one of the bounds is omitted,
4441 it represents either the highest or lowest value of the type.
4443 In the comments below, we represent a range by two numbers in brackets
4444 preceded by a "+" to designate being inside that range, or a "-" to
4445 designate being outside that range, so the condition can be inverted by
4446 flipping the prefix. An omitted bound is represented by a "-". For
4447 example, "- [-, 10]" means being outside the range starting at the lowest
4448 possible value and ending at 10, in other words, being greater than 10.
4449 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4450 always false.
4452 We set up things so that the missing bounds are handled in a consistent
4453 manner so neither a missing bound nor "true" and "false" need to be
4454 handled using a special case. */
4456 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4457 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4458 and UPPER1_P are nonzero if the respective argument is an upper bound
4459 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4460 must be specified for a comparison. ARG1 will be converted to ARG0's
4461 type if both are specified. */
4463 static tree
4466 {
4467 tree tem;
4471 /* If neither arg represents infinity, do the normal operation.
4472 Else, if not a comparison, return infinity. Else handle the special
4473 comparison rules. Note that most of the cases below won't occur, but
4474 are handled for consistency. */
4477 {
4482 }
4487 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4488 for neither. In real maths, we cannot assume open ended ranges are
4489 the same. But, this is computer arithmetic, where numbers are finite.
4490 We can therefore make the transformation of any unbounded range with
4491 the value Z, Z being greater than any representable number. This permits
4492 us to treat unbounded ranges as equal. */
4496 {
4517 }
4520 }
4521 \f
4522 /* Helper routine for make_range. Perform one step for it, return
4523 new expression if the loop should continue or NULL_TREE if it should
4524 stop. */
4526 tree
4530 {
4536 {
4538 /* We can only do something if the range is testing for zero. */
4547 /* We can only do something if the range is testing for zero
4548 and if the second operand is an integer constant. Note that
4549 saying something is "in" the range we make is done by
4550 complementing IN_P since it will set in the initial case of
4551 being not equal to zero; "out" is leaving it alone. */
4558 {
4579 }
4581 /* If this is an unsigned comparison, we also know that EXP is
4582 greater than or equal to zero. We base the range tests we make
4583 on that fact, so we record it here so we can parse existing
4584 range tests. We test arg0_type since often the return type
4585 of, e.g. EQ_EXPR, is boolean. */
4587 {
4591 NULL_TREE))
4596 /* If the high bound is missing, but we have a nonzero low
4597 bound, reverse the range so it goes from zero to the low bound
4598 minus 1. */
4600 {
4605 }
4606 }
4614 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4615 low and high are non-NULL, then normalize will DTRT. */
4618 {
4623 }
4625 /* (-x) IN [a,b] -> x in [-b, -a] */
4637 /* ~ X -> -X - 1 */
4646 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4647 move a constant to the other side. */
4652 /* If EXP is signed, any overflow in the computation is undefined,
4653 so we don't worry about it so long as our computations on
4654 the bounds don't overflow. For unsigned, overflow is defined
4655 and this is exactly the right thing. */
4667 normalize:
4668 /* Check for an unsigned range which has wrapped around the maximum
4669 value thus making n_high < n_low, and normalize it. */
4671 {
4677 /* If the range is of the form +/- [ x+1, x ], we won't
4678 be able to normalize it. But then, it represents the
4679 whole range or the empty set, so make it
4680 +/- [ -, - ]. */
4684 else
4686 }
4687 else
4695 CASE_CONVERT:
4713 /* If we're converting arg0 from an unsigned type, to exp,
4714 a signed type, we will be doing the comparison as unsigned.
4715 The tests above have already verified that LOW and HIGH
4716 are both positive.
4718 So we have to ensure that we will handle large unsigned
4719 values the same way that the current signed bounds treat
4720 negative values. */
4723 {
4724 tree high_positive;
4725 tree equiv_type;
4726 /* For fixed-point modes, we need to pass the saturating flag
4727 as the 2nd parameter. */
4729 equiv_type
4732 else
4733 equiv_type
4736 /* A range without an upper bound is, naturally, unbounded.
4737 Since convert would have cropped a very large value, use
4738 the max value for the destination type. */
4739 high_positive
4746 high_positive),
4749 /* If the low bound is specified, "and" the range with the
4750 range for which the original unsigned value will be
4751 positive. */
4753 {
4756 integer_zero_node),
4757 high_positive))
4761 }
4762 else
4763 {
4764 /* Otherwise, "or" the range with the range of the input
4765 that will be interpreted as negative. */
4768 integer_zero_node),
4769 high_positive))
4773 }
4774 }
4783 }
4784 }
4786 /* Given EXP, a logical expression, set the range it is testing into
4787 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4788 actually being tested. *PLOW and *PHIGH will be made of the same
4789 type as the returned expression. If EXP is not a comparison, we
4790 will most likely not be returning a useful value and range. Set
4791 *STRICT_OVERFLOW_P to true if the return value is only valid
4792 because signed overflow is undefined; otherwise, do not change
4793 *STRICT_OVERFLOW_P. */
4795 tree
4798 {
4806 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4807 and see if we can refine the range. Some of the cases below may not
4808 happen, but it doesn't seem worth worrying about this. We "continue"
4809 the outer loop when we've changed something; otherwise we "break"
4810 the switch, which will "break" the while. */
4816 {
4822 {
4830 }
4839 }
4841 /* If EXP is a constant, we can evaluate whether this is true or false. */
4843 {
4850 }
4854 }
4856 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4857 a bitwise check i.e. when
4858 LOW == 0xXX...X00...0
4859 HIGH == 0xXX...X11...1
4860 Return corresponding mask in MASK and stem in VALUE. */
4862 static bool
4865 {
4888 }
4889 \f
4890 /* Helper routine for build_range_check and match.pd. Return the type to
4891 perform the check or NULL if it shouldn't be optimized. */
4893 tree
4895 {
4896 /* First make sure that arithmetics in this type is valid, then make sure
4897 that it wraps around. */
4903 {
4906 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4907 for the type in question, as we rely on this here. */
4917 else
4919 }
4921 }
4923 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4924 type, TYPE, return an expression to test if EXP is in (or out of, depending
4925 on IN_P) the range. Return 0 if the test couldn't be created. */
4927 tree
4930 {
4933 /* Disable this optimization for function pointer expressions
4934 on targets that require function pointer canonicalization. */
4941 {
4947 }
4969 value);
4972 {
4974 {
4978 }
4980 }
4982 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4984 {
4988 {
4990 {
4993 etype
4995 else
4998 }
5001 }
5002 }
5004 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5005 This requires wrap-around arithmetics for the type of the expression. */
5025 }
5026 \f
5027 /* Return the predecessor of VAL in its type, handling the infinite case. */
5029 static tree
5031 {
5037 else
5040 }
5042 /* Return the successor of VAL in its type, handling the infinite case. */
5044 static tree
5046 {
5052 else
5055 }
5057 /* Given two ranges, see if we can merge them into one. Return 1 if we
5058 can, 0 if we can't. Set the output range into the specified parameters. */
5060 bool
5063 {
5067 tree tem;
5077 /* Make range 0 be the range that starts first, or ends last if they
5078 start at the same value. Swap them if it isn't. */
5081 || (lowequal
5084 {
5088 }
5090 /* Now flag two cases, whether the ranges are disjoint or whether the
5091 second range is totally subsumed in the first. Note that the tests
5092 below are simplified by the ones above. */
5098 /* We now have four cases, depending on whether we are including or
5099 excluding the two ranges. */
5101 {
5102 /* If they don't overlap, the result is false. If the second range
5103 is a subset it is the result. Otherwise, the range is from the start
5104 of the second to the end of the first. */
5109 else
5111 }
5114 {
5115 /* If they don't overlap, the result is the first range. If they are
5116 equal, the result is false. If the second range is a subset of the
5117 first, and the ranges begin at the same place, we go from just after
5118 the end of the second range to the end of the first. If the second
5119 range is not a subset of the first, or if it is a subset and both
5120 ranges end at the same place, the range starts at the start of the
5121 first range and ends just before the second range.
5122 Otherwise, we can't describe this as a single range. */
5128 {
5133 {
5134 /* We are in the weird situation where high0 > high1 but
5135 high1 has no successor. Punt. */
5137 }
5138 }
5140 {
5145 {
5146 /* low0 < low1 but low1 has no predecessor. Punt. */
5148 }
5149 }
5150 else
5152 }
5155 {
5156 /* If they don't overlap, the result is the second range. If the second
5157 is a subset of the first, the result is false. Otherwise,
5158 the range starts just after the first range and ends at the
5159 end of the second. */
5164 else
5165 {
5170 {
5171 /* high1 > high0 but high0 has no successor. Punt. */
5173 }
5174 }
5175 }
5177 else
5178 {
5179 /* The case where we are excluding both ranges. Here the complex case
5180 is if they don't overlap. In that case, the only time we have a
5181 range is if they are adjacent. If the second is a subset of the
5182 first, the result is the first. Otherwise, the range to exclude
5183 starts at the beginning of the first range and ends at the end of the
5184 second. */
5186 {
5191 else
5192 {
5193 /* Canonicalize - [min, x] into - [-, x]. */
5196 {
5199 GET_MODE_BITSIZE
5202 /* FALLTHROUGH */
5215 }
5217 /* Canonicalize - [x, max] into - [x, -]. */
5220 {
5223 GET_MODE_BITSIZE
5226 /* FALLTHROUGH */
5242 }
5244 /* The ranges might be also adjacent between the maximum and
5245 minimum values of the given type. For
5246 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5247 return + [x + 1, y - 1]. */
5249 {
5256 }
5257 else
5259 }
5260 }
5263 else
5265 }
5269 }
5270 \f
5272 /* Subroutine of fold, looking inside expressions of the form
5273 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5274 of the COND_EXPR. This function is being used also to optimize
5275 A op B ? C : A, by reversing the comparison first.
5277 Return a folded expression whose code is not a COND_EXPR
5278 anymore, or NULL_TREE if no folding opportunity is found. */
5280 static tree
5283 {
5288 tree tem;
5293 /* If we have A op 0 ? A : -A, consider applying the following
5294 transformations:
5296 A == 0? A : -A same as -A
5297 A != 0? A : -A same as A
5298 A >= 0? A : -A same as abs (A)
5299 A > 0? A : -A same as abs (A)
5300 A <= 0? A : -A same as -abs (A)
5301 A < 0? A : -A same as -abs (A)
5303 None of these transformations work for modes with signed
5304 zeros. If A is +/-0, the first two transformations will
5305 change the sign of the result (from +0 to -0, or vice
5306 versa). The last four will fix the sign of the result,
5307 even though the original expressions could be positive or
5308 negative, depending on the sign of A.
5310 Note that all these transformations are correct if A is
5311 NaN, since the two alternatives (A and -A) are also NaNs. */
5318 /* In the case that A is of the form X-Y, '-A' (arg2) may
5319 have already been folded to Y-X, check for that. */
5327 {
5339 /* Fall through. */
5350 /* FALLTHRU */
5360 }
5362 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5363 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5364 both transformations are correct when A is NaN: A != 0
5365 is then true, and A == 0 is false. */
5369 {
5374 }
5376 /* Try some transformations of A op B ? A : B.
5378 A == B? A : B same as B
5379 A != B? A : B same as A
5380 A >= B? A : B same as max (A, B)
5381 A > B? A : B same as max (B, A)
5382 A <= B? A : B same as min (A, B)
5383 A < B? A : B same as min (B, A)
5385 As above, these transformations don't work in the presence
5386 of signed zeros. For example, if A and B are zeros of
5387 opposite sign, the first two transformations will change
5388 the sign of the result. In the last four, the original
5389 expressions give different results for (A=+0, B=-0) and
5390 (A=-0, B=+0), but the transformed expressions do not.
5392 The first two transformations are correct if either A or B
5393 is a NaN. In the first transformation, the condition will
5394 be false, and B will indeed be chosen. In the case of the
5395 second transformation, the condition A != B will be true,
5396 and A will be chosen.
5398 The conversions to max() and min() are not correct if B is
5399 a number and A is not. The conditions in the original
5400 expressions will be false, so all four give B. The min()
5401 and max() versions would give a NaN instead. */
5404 /* Avoid these transformations if the COND_EXPR may be used
5405 as an lvalue in the C++ front-end. PR c++/19199. */
5406 && (in_gimple_form
5412 {
5418 {
5427 /* In C++ a ?: expression can be an lvalue, so put the
5428 operand which will be used if they are equal first
5429 so that we can convert this back to the
5430 corresponding COND_EXPR. */
5432 {
5440 }
5447 {
5455 }
5468 }
5469 }
5472 }
5475 \f
5476 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5477 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5478 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5479 false) >= 2)
5480 #endif
5482 /* EXP is some logical combination of boolean tests. See if we can
5483 merge it into some range test. Return the new tree if so. */
5485 static tree
5488 {
5504 /* If this is an OR operation, invert both sides; we will invert
5505 again at the end. */
5509 /* If both expressions are the same, if we can merge the ranges, and we
5510 can build the range test, return it or it inverted. If one of the
5511 ranges is always true or always false, consider it to be the same
5512 expression as the other. */
5520 {
5524 }
5526 /* On machines where the branch cost is expensive, if this is a
5527 short-circuited branch and the underlying object on both sides
5528 is the same, make a non-short-circuit operation. */
5530 && !flag_sanitize_coverage
5535 {
5536 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5537 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5538 which cases we can't do this. */
5546 {
5555 {
5558 WARN_STRICT_OVERFLOW_COMPARISON);
5562 }
5563 }
5564 }
5567 }
5568 \f
5569 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5570 bit value. Arrange things so the extra bits will be set to zero if and
5571 only if C is signed-extended to its full width. If MASK is nonzero,
5572 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5574 static tree
5576 {
5579 tree temp;
5584 /* We work by getting just the sign bit into the low-order bit, then
5585 into the high-order bit, then sign-extend. We then XOR that value
5586 with C. */
5590 /* We must use a signed type in order to get an arithmetic right shift.
5591 However, we must also avoid introducing accidental overflows, so that
5592 a subsequent call to integer_zerop will work. Hence we must
5593 do the type conversion here. At this point, the constant is either
5594 zero or one, and the conversion to a signed type can never overflow.
5595 We could get an overflow if this conversion is done anywhere else. */
5604 /* If necessary, convert the type back to match the type of C. */
5609 }
5610 \f
5611 /* For an expression that has the form
5612 (A && B) || ~B
5613 or
5614 (A || B) && ~B,
5615 we can drop one of the inner expressions and simplify to
5616 A || ~B
5617 or
5618 A && ~B
5619 LOC is the location of the resulting expression. OP is the inner
5620 logical operation; the left-hand side in the examples above, while CMPOP
5621 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5622 removing a condition that guards another, as in
5623 (A != NULL && A->...) || A == NULL
5624 which we must not transform. If RHS_ONLY is true, only eliminate the
5625 right-most operand of the inner logical operation. */
5627 static tree
5630 {
5648 {
5651 {
5654 }
5655 }
5657 {
5660 {
5663 }
5664 }
5679 }
5681 /* Find ways of folding logical expressions of LHS and RHS:
5682 Try to merge two comparisons to the same innermost item.
5683 Look for range tests like "ch >= '0' && ch <= '9'".
5684 Look for combinations of simple terms on machines with expensive branches
5685 and evaluate the RHS unconditionally.
5687 For example, if we have p->a == 2 && p->b == 4 and we can make an
5688 object large enough to span both A and B, we can do this with a comparison
5689 against the object ANDed with the a mask.
5691 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5692 operations to do this with one comparison.
5694 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5695 function and the one above.
5697 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5698 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5700 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5701 two operands.
5703 We return the simplified tree or 0 if no optimization is possible. */
5705 static tree
5708 {
5709 /* If this is the "or" of two comparisons, we can do something if
5710 the comparisons are NE_EXPR. If this is the "and", we can do something
5711 if the comparisons are EQ_EXPR. I.e.,
5712 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5714 WANTED_CODE is this operation code. For single bit fields, we can
5715 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5716 comparison for one-bit fields. */
5737 /* Start by getting the comparison codes. Fail if anything is volatile.
5738 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5739 it were surrounded with a NE_EXPR. */
5748 {
5752 }
5755 {
5759 }
5770 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5773 {
5776 {
5781 }
5784 {
5790 }
5791 }
5796 /* If the RHS can be evaluated unconditionally and its operands are
5797 simple, it wins to evaluate the RHS unconditionally on machines
5798 with expensive branches. In this case, this isn't a comparison
5799 that can be merged. */
5806 {
5807 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5818 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5828 }
5830 /* See if the comparisons can be merged. Then get all the parameters for
5831 each side. */
5856 /* It must be true that the inner operation on the lhs of each
5857 comparison must be the same if we are to be able to do anything.
5858 Then see if we have constants. If not, the same must be true for
5859 the rhs's. */
5868 {
5871 }
5876 else
5879 /* If either comparison code is not correct for our logical operation,
5880 fail. However, we can convert a one-bit comparison against zero into
5881 the opposite comparison against that bit being set in the field. */
5885 {
5887 {
5888 /* Make the left operand unsigned, since we are only interested
5889 in the value of one bit. Otherwise we are doing the wrong
5890 thing below. */
5893 }
5894 else
5896 }
5898 /* This is analogous to the code for l_const above. */
5900 {
5902 {
5905 }
5906 else
5908 }
5910 /* See if we can find a mode that contains both fields being compared on
5911 the left. If we can't, fail. Otherwise, update all constants and masks
5912 to be relative to a field of that size. */
5926 {
5929 }
5937 {
5944 {
5948 }
5949 }
5951 {
5958 {
5962 }
5963 }
5965 /* If the right sides are not constant, do the same for it. Also,
5966 disallow this optimization if a size or signedness mismatch occurs
5967 between the left and right sides. */
5969 {
5972 /* Make sure the two fields on the right
5973 correspond to the left without being swapped. */
5990 {
5993 }
6002 /* Make a mask that corresponds to both fields being compared.
6003 Do this for both items being compared. If the operands are the
6004 same size and the bits being compared are in the same position
6005 then we can do this by masking both and comparing the masked
6006 results. */
6013 {
6027 }
6029 /* There is still another way we can do something: If both pairs of
6030 fields being compared are adjacent, we may be able to make a wider
6031 field containing them both.
6033 Note that we still must mask the lhs/rhs expressions. Furthermore,
6034 the mask must be shifted to account for the shift done by
6035 make_bit_field_ref. */
6044 {
6045 tree type;
6061 /* Convert to the smaller type before masking out unwanted bits. */
6064 {
6066 {
6070 }
6072 {
6076 }
6077 }
6086 }
6089 }
6091 /* Handle the case of comparisons with constants. If there is something in
6092 common between the masks, those bits of the constants must be the same.
6093 If not, the condition is always false. Test for this to avoid generating
6094 incorrect code below. */
6099 {
6101 {
6104 }
6105 else
6106 {
6109 }
6110 }
6115 /* Construct the expression we will return. First get the component
6116 reference we will make. Unless the mask is all ones the width of
6117 that field, perform the mask operation. Then compare with the
6118 merged constant. */
6129 }
6130 \f
6131 /* T is an integer expression that is being multiplied, divided, or taken a
6132 modulus (CODE says which and what kind of divide or modulus) by a
6133 constant C. See if we can eliminate that operation by folding it with
6134 other operations already in T. WIDE_TYPE, if non-null, is a type that
6135 should be used for the computation if wider than our type.
6137 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6138 (X * 2) + (Y * 4). We must, however, be assured that either the original
6139 expression would not overflow or that overflow is undefined for the type
6140 in the language in question.
6142 If we return a non-null expression, it is an equivalent form of the
6143 original computation, but need not be in the original type.
6145 We set *STRICT_OVERFLOW_P to true if the return values depends on
6146 signed overflow being undefined. Otherwise we do not change
6147 *STRICT_OVERFLOW_P. */
6149 static tree
6152 {
6153 /* To avoid exponential search depth, refuse to allow recursion past
6154 three levels. Beyond that (1) it's highly unlikely that we'll find
6155 something interesting and (2) we've probably processed it before
6156 when we built the inner expression. */
6159 tree ret;
6164 depth++;
6166 depth--;
6169 }
6171 static tree
6174 {
6186 /* Don't deal with constants of zero here; they confuse the code below. */
6196 /* Note that we need not handle conditional operations here since fold
6197 already handles those cases. So just do arithmetic here. */
6199 {
6201 /* For a constant, we can always simplify if we are a multiply
6202 or (for divide and modulus) if it is a multiple of our constant. */
6206 {
6209 /* If the multiplication overflowed, we lost information on it.
6210 See PR68142 and PR69845. */
6214 }
6218 /* If op0 is an expression ... */
6224 /* ... and has wrapping overflow, and its type is smaller
6225 than ctype, then we cannot pass through as widening. */
6230 /* ... or this is a truncation (t is narrower than op0),
6231 then we cannot pass through this narrowing. */
6234 /* ... or signedness changes for division or modulus,
6235 then we cannot pass through this conversion. */
6239 /* ... or has undefined overflow while the converted to
6240 type has not, we cannot do the operation in the inner type
6241 as that would introduce undefined overflow. */
6247 /* Pass the constant down and see if we can make a simplification. If
6248 we can, replace this expression with the inner simplification for
6249 possible later conversion to our or some other type. */
6260 /* If widening the type changes it from signed to unsigned, then we
6261 must avoid building ABS_EXPR itself as unsigned. */
6263 {
6267 {
6270 }
6272 }
6273 /* If the constant is negative, we cannot simplify this. */
6276 /* FALLTHROUGH */
6278 /* For division and modulus, type can't be unsigned, as e.g.
6279 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6280 For signed types, even with wrapping overflow, this is fine. */
6289 /* If widening the type changes the signedness, then we can't perform
6290 this optimization as that changes the result. */
6294 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6300 {
6307 }
6311 /* If the second operand is constant, this is a multiplication
6312 or floor division, by a power of two, so we can treat it that
6313 way unless the multiplier or divisor overflows. Signed
6314 left-shift overflow is implementation-defined rather than
6315 undefined in C90, so do not convert signed left shift into
6316 multiplication. */
6319 /* const_binop may not detect overflow correctly,
6320 so check for it explicitly here. */
6329 ctype,
6331 t1),
6336 /* See if we can eliminate the operation on both sides. If we can, we
6337 can return a new PLUS or MINUS. If we can't, the only remaining
6338 cases where we can do anything are if the second operand is a
6339 constant. */
6346 /* If not multiplication, we can only do this if both operands
6347 are divisible by c. */
6350 {
6355 }
6357 /* If this was a subtraction, negate OP1 and set it to be an addition.
6358 This simplifies the logic below. */
6360 {
6362 /* If OP1 was not easily negatable, the constant may be OP0. */
6364 {
6367 }
6368 }
6373 /* If either OP1 or C are negative, this optimization is not safe for
6374 some of the division and remainder types while for others we need
6375 to change the code. */
6377 {
6385 }
6387 /* If it's a multiply or a division/modulus operation of a multiple
6388 of our constant, do the operation and verify it doesn't overflow. */
6392 {
6395 /* We allow the constant to overflow with wrapping semantics. */
6399 }
6400 else
6403 /* If we have an unsigned type, we cannot widen the operation since it
6404 will change the result if the original computation overflowed. */
6408 /* The last case is if we are a multiply. In that case, we can
6409 apply the distributive law to commute the multiply and addition
6410 if the multiplication of the constants doesn't overflow
6411 and overflow is defined. With undefined overflow
6412 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6418 op1);
6423 /* We have a special case here if we are doing something like
6424 (C * 8) % 4 since we know that's zero. */
6427 /* If the multiplication can overflow we cannot optimize this. */
6432 {
6435 }
6437 /* ... fall through ... */
6441 /* If we can extract our operation from the LHS, do so and return a
6442 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6443 do something only if the second operand is a constant. */
6459 /* If these are the same operation types, we can associate them
6460 assuming no overflow. */
6462 {
6477 }
6479 /* If these operations "cancel" each other, we have the main
6480 optimizations of this pass, which occur when either constant is a
6481 multiple of the other, in which case we replace this with either an
6482 operation or CODE or TCODE.
6484 If we have an unsigned type, we cannot do this since it will change
6485 the result if the original computation overflowed. */
6492 {
6495 {
6502 }
6505 {
6512 }
6513 }
6518 }
6521 }
6522 \f
6523 /* Return a node which has the indicated constant VALUE (either 0 or
6524 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6525 and is of the indicated TYPE. */
6527 tree
6529 {
6538 else
6540 }
6543 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6544 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6545 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6546 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6547 COND is the first argument to CODE; otherwise (as in the example
6548 given here), it is the second argument. TYPE is the type of the
6549 original expression. Return NULL_TREE if no simplification is
6550 possible. */
6552 static tree
6557 {
6567 {
6571 /* If this operand throws an expression, then it does not make
6572 sense to try to perform a logical or arithmetic operation
6573 involving it. */
6578 }
6581 {
6586 }
6587 else
6588 /* Detect the case of mixing vector and scalar types - bail out. */
6594 /* This transformation is only worthwhile if we don't have to wrap ARG
6595 in a SAVE_EXPR and the operation can be simplified without recursing
6596 on at least one of the branches once its pushed inside the COND_EXPR. */
6605 {
6609 else
6611 }
6613 {
6617 else
6619 }
6621 /* Check that we have simplified at least one of the branches. */
6626 }
6628 \f
6629 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6631 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6632 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6633 ADDEND is the same as X.
6635 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6636 and finite. The problematic cases are when X is zero, and its mode
6637 has signed zeros. In the case of rounding towards -infinity,
6638 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6639 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6641 bool
6643 {
6647 /* Don't allow the fold with -fsignaling-nans. */
6651 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6655 /* In a vector or complex, we would need to check the sign of all zeros. */
6659 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6663 /* The mode has signed zeros, and we have to honor their sign.
6664 In this situation, there is only one case we can return true for.
6665 X - 0 is the same as X unless rounding towards -infinity is
6666 supported. */
6668 }
6670 /* Subroutine of match.pd that optimizes comparisons of a division by
6671 a nonzero integer constant against an integer constant, i.e.
6672 X/C1 op C2.
6674 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6675 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6677 enum tree_code
6680 {
6685 /* We have to do this the hard way to detect unsigned overflow.
6686 prod = int_const_binop (MULT_EXPR, c1, c2); */
6692 {
6696 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6699 }
6701 {
6704 {
6723 }
6724 }
6725 else
6726 {
6727 /* A negative divisor reverses the relational operators. */
6732 {
6751 }
6752 }
6765 }
6768 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6769 equality/inequality test, then return a simplified form of the test
6770 using a sign testing. Otherwise return NULL. TYPE is the desired
6771 result type. */
6773 static tree
6776 tree result_type)
6777 {
6778 /* If this is testing a single bit, we can optimize the test. */
6782 {
6783 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6784 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6788 /* This is only a win if casting to a signed type is cheap,
6789 i.e. when arg00's type is not a partial mode. */
6791 {
6794 result_type,
6797 }
6798 }
6801 }
6803 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6804 equality/inequality test, then return a simplified form of
6805 the test using shifts and logical operations. Otherwise return
6806 NULL. TYPE is the desired result type. */
6808 tree
6811 {
6812 /* If this is testing a single bit, we can optimize the test. */
6816 {
6825 /* First, see if we can fold the single bit test into a sign-bit
6826 test. */
6828 result_type);
6832 /* Otherwise we have (A & C) != 0 where C is a single bit,
6833 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6834 Similarly for (A & C) == 0. */
6836 /* If INNER is a right shift of a constant and it plus BITNUM does
6837 not overflow, adjust BITNUM and INNER. */
6843 {
6846 }
6848 /* If we are going to be able to omit the AND below, we must do our
6849 operations as unsigned. If we must use the AND, we have a choice.
6850 Normally unsigned is faster, but for some machines signed is. */
6868 /* Put the AND last so it can combine with more things. */
6871 /* Make sure to return the proper type. */
6875 }
6877 }
6879 /* Test whether it is preferable two swap two operands, ARG0 and
6880 ARG1, for example because ARG0 is an integer constant and ARG1
6881 isn't. */
6883 bool
6885 {
6899 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6900 for commutative and comparison operators. Ensuring a canonical
6901 form allows the optimizers to find additional redundancies without
6902 having to explicitly check for both orderings. */
6908 /* Put SSA_NAMEs last. */
6914 /* Put variables last. */
6921 }
6924 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6925 means A >= Y && A != MAX, but in this case we know that
6926 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6928 static tree
6930 {
6937 else
6946 {
6949 }
6951 {
6954 }
6955 else
6962 {
6963 /* Convert the pointer types into integer before taking the difference. */
6967 }
6968 else
6975 }
6977 /* Fold a sum or difference of at least one multiplication.
6978 Returns the folded tree or NULL if no simplification could be made. */
6980 static tree
6983 {
6987 /* (A * C) +- (B * C) -> (A+-B) * C.
6988 (A * C) +- A -> A * (C+-1).
6989 We are most concerned about the case where C is a constant,
6990 but other combinations show up during loop reduction. Since
6991 it is not difficult, try all four possibilities. */
6994 {
6997 }
6999 {
7002 }
7003 else
7004 {
7005 /* We cannot generate constant 1 for fract. */
7010 }
7012 {
7015 }
7017 {
7019 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7020 the purpose of this canonicalization. */
7024 {
7027 }
7028 else
7030 }
7031 else
7032 {
7033 /* We cannot generate constant 1 for fract. */
7038 }
7041 /* Prefer factoring a common non-constant. */
7051 /* No identical multiplicands; see if we can find a common
7052 power-of-two factor in non-power-of-two multiplies. This
7053 can help in multi-dimensional array access. */
7056 {
7059 tree maybe_same;
7063 /* Move min of absolute values to int11. */
7065 {
7070 }
7071 else
7075 /* The remainder should not be a constant, otherwise we
7076 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7077 increased the number of multiplications necessary. */
7079 {
7087 }
7088 }
7095 /* We are neither factoring zero nor minus one. */
7103 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7104 same may be minus one and thus the multiplication may overflow. Perform
7105 the sum operation in an unsigned type. */
7110 /* If the sum evaluated to a constant that is not -INF the multiplication
7111 cannot overflow. */
7118 /* Do not resort to unsigned multiplication because
7119 we lose the no-overflow property of the expression. */
7121 }
7123 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7124 specified by EXPR into the buffer PTR of length LEN bytes.
7125 Return the number of bytes placed in the buffer, or zero
7126 upon failure. */
7128 static int
7130 {
7142 /* Dry run. */
7148 {
7150 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7151 number of bytes. */
7155 {
7162 else
7164 }
7165 else
7169 }
7171 }
7174 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7175 specified by EXPR into the buffer PTR of length LEN bytes.
7176 Return the number of bytes placed in the buffer, or zero
7177 upon failure. */
7179 static int
7181 {
7185 FIXED_VALUE_TYPE value;
7200 }
7203 /* Subroutine of native_encode_expr. Encode the REAL_CST
7204 specified by EXPR into the buffer PTR of length LEN bytes.
7205 Return the number of bytes placed in the buffer, or zero
7206 upon failure. */
7208 static int
7210 {
7216 /* There are always 32 bits in each long, no matter the size of
7217 the hosts long. We handle floating point representations with
7218 up to 192 bits. */
7227 /* Dry run. */
7236 {
7241 {
7248 else
7250 }
7251 else
7252 {
7255 {
7256 /* Reverse bytes within each long, or within the entire float
7257 if it's smaller than a long (for HFmode). */
7260 }
7261 }
7266 }
7268 }
7270 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7271 specified by EXPR into the buffer PTR of length LEN bytes.
7272 Return the number of bytes placed in the buffer, or zero
7273 upon failure. */
7275 static int
7277 {
7279 tree part;
7293 }
7296 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7297 specified by EXPR into the buffer PTR of length LEN bytes.
7298 Return the number of bytes placed in the buffer, or zero
7299 upon failure. */
7301 static int
7303 {
7314 {
7316 {
7319 }
7330 }
7332 }
7335 /* Subroutine of native_encode_expr. Encode the STRING_CST
7336 specified by EXPR into the buffer PTR of length LEN bytes.
7337 Return the number of bytes placed in the buffer, or zero
7338 upon failure. */
7340 static int
7342 {
7345 /* Wide-char strings are encoded in target byte-order so native
7346 encoding them is trivial. */
7361 {
7364 {
7367 }
7370 }
7371 else
7374 }
7377 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7378 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7379 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7380 anything, just do a dry run. If OFF is not -1 then start
7381 the encoding at byte offset OFF and encode at most LEN bytes.
7382 Return the number of bytes placed in the buffer, or zero upon failure. */
7384 int
7386 {
7387 /* We don't support starting at negative offset and -1 is special. */
7392 {
7413 }
7414 }
7417 /* Subroutine of native_interpret_expr. Interpret the contents of
7418 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7419 If the buffer cannot be interpreted, return NULL_TREE. */
7421 static tree
7423 {
7433 }
7436 /* Subroutine of native_interpret_expr. Interpret the contents of
7437 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7438 If the buffer cannot be interpreted, return NULL_TREE. */
7440 static tree
7442 {
7445 double_int result;
7446 FIXED_VALUE_TYPE fixed_value;
7456 }
7459 /* Subroutine of native_interpret_expr. Interpret the contents of
7460 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7461 If the buffer cannot be interpreted, return NULL_TREE. */
7463 static tree
7465 {
7469 /* There are always 32 bits in each long, no matter the size of
7470 the hosts long. We handle floating point representations with
7471 up to 192 bits. */
7472 REAL_VALUE_TYPE r;
7482 {
7483 /* Both OFFSET and BYTE index within a long;
7484 bitpos indexes the whole float. */
7487 {
7494 else
7496 }
7497 else
7498 {
7501 {
7502 /* Reverse bytes within each long, or within the entire float
7503 if it's smaller than a long (for HFmode). */
7506 }
7507 }
7511 }
7515 }
7518 /* Subroutine of native_interpret_expr. Interpret the contents of
7519 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7520 If the buffer cannot be interpreted, return NULL_TREE. */
7522 static tree
7524 {
7539 }
7542 /* Subroutine of native_interpret_expr. Interpret the contents of
7543 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7544 If the buffer cannot be interpreted, return NULL_TREE. */
7546 static tree
7548 {
7561 {
7566 }
7568 }
7571 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7572 the buffer PTR of length LEN as a constant of type TYPE. For
7573 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7574 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7575 return NULL_TREE. */
7577 tree
7579 {
7581 {
7603 }
7604 }
7606 /* Returns true if we can interpret the contents of a native encoding
7607 as TYPE. */
7609 static bool
7611 {
7613 {
7626 }
7627 }
7630 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7631 TYPE at compile-time. If we're unable to perform the conversion
7632 return NULL_TREE. */
7634 static tree
7636 {
7637 /* We support up to 512-bit values (for V8DFmode). */
7641 /* Check that the host and target are sane. */
7650 }
7652 /* Build an expression for the address of T. Folds away INDIRECT_REF
7653 to avoid confusing the gimplify process. */
7655 tree
7657 {
7658 /* The size of the object is not relevant when talking about its address. */
7663 {
7668 }
7678 {
7683 }
7684 else
7688 }
7690 /* Build an expression for the address of T. */
7692 tree
7694 {
7698 }
7700 /* Fold a unary expression of code CODE and type TYPE with operand
7701 OP0. Return the folded expression if folding is successful.
7702 Otherwise, return NULL_TREE. */
7704 tree
7706 {
7707 tree tem;
7708 tree arg0;
7716 {
7719 {
7720 /* Don't use STRIP_NOPS, because signedness of argument type
7721 matters. */
7723 }
7724 else
7725 {
7726 /* Strip any conversions that don't change the mode. This
7727 is safe for every expression, except for a comparison
7728 expression because its signedness is derived from its
7729 operands.
7731 Note that this is done as an internal manipulation within
7732 the constant folder, in order to find the simplest
7733 representation of the arguments so that their form can be
7734 studied. In any cases, the appropriate type conversions
7735 should be put back in the tree that will get out of the
7736 constant folder. */
7738 }
7741 {
7744 {
7748 }
7749 }
7750 }
7757 {
7764 {
7778 /* If this was a conversion, and all we did was to move into
7779 inside the COND_EXPR, bring it back out. But leave it if
7780 it is a conversion from integer to integer and the
7781 result precision is no wider than a word since such a
7782 conversion is cheap and may be optimized away by combine,
7783 while it couldn't if it were outside the COND_EXPR. Then return
7784 so we don't get into an infinite recursion loop taking the
7785 conversion out and then back in. */
7797 && (INTEGRAL_TYPE_P
7810 }
7811 }
7814 {
7820 CASE_CONVERT:
7824 {
7825 /* If we have (type) (a CMP b) and type is an integral type, return
7826 new expression involving the new type. Canonicalize
7827 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7828 non-integral type.
7829 Do not fold the result as that would not simplify further, also
7830 folding again results in recursions. */
7840 }
7842 /* Handle (T *)&A.B.C for A being of type T and B and C
7843 living at offset zero. This occurs frequently in
7844 C++ upcasting and then accessing the base. */
7848 {
7850 tree offset;
7851 machine_mode mode;
7853 tree base
7857 /* If the reference was to a (constant) zero offset, we can use
7858 the address of the base if it has the same base type
7859 as the result type and the pointer type is unqualified. */
7867 }
7871 /* Detect assigning a bitfield. */
7873 && DECL_BIT_FIELD
7875 {
7876 /* Don't leave an assignment inside a conversion
7877 unless assigning a bitfield. */
7879 /* First do the assignment, then return converted constant. */
7884 }
7886 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7887 constants (if x has signed type, the sign bit cannot be set
7888 in c). This folds extension into the BIT_AND_EXPR.
7889 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7890 very likely don't have maximal range for their precision and this
7891 transformation effectively doesn't preserve non-maximal ranges. */
7895 {
7906 <= HOST_BITS_PER_WIDE_INT
7908 {
7912 cst &= HOST_WIDE_INT_M1U
7916 && !flag_syntax_only
7919 {
7923 }
7924 }
7926 {
7931 }
7932 }
7934 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7935 cast (T1)X will fold away. We assume that this happens when X itself
7936 is a cast. */
7940 {
7944 return fold_build_pointer_plus_loc
7946 }
7948 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7949 of the same precision, and X is an integer type not narrower than
7950 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7956 {
7962 }
7964 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
7965 type of X and Y (integer types only). */
7970 {
7971 /* Be careful not to introduce new overflows. */
7972 tree mult_type;
7975 else
7979 {
7986 }
7987 }
7993 {
8000 }
8011 /* Convert fabs((double)float) into (double)fabsf(float). */
8014 {
8020 targ0));
8021 }
8025 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8044 /* Note that the operand of this must be an int
8045 and its values must be 0 or 1.
8046 ("true" is a fixed value perhaps depending on the language,
8047 but we don't handle values other than 1 correctly yet.) */
8054 /* Fold *&X to X if X is an lvalue. */
8056 {
8063 }
8069 }
8072 /* If the operation was a conversion do _not_ mark a resulting constant
8073 with TREE_OVERFLOW if the original constant was not. These conversions
8074 have implementation defined behavior and retaining the TREE_OVERFLOW
8075 flag here would confuse later passes such as VRP. */
8076 tree
8079 {
8088 }
8090 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8091 operands OP0 and OP1. LOC is the location of the resulting expression.
8092 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8093 Return the folded expression if folding is successful. Otherwise,
8094 return NULL_TREE. */
8095 static tree
8098 {
8099 tree tem;
8101 /* We only do these simplifications if we are optimizing. */
8105 /* Check for things like (A || B) && (A || C). We can convert this
8106 to A || (B && C). Note that either operator can be any of the four
8107 truth and/or operations and the transformation will still be
8108 valid. Also note that we only care about order for the
8109 ANDIF and ORIF operators. If B contains side effects, this
8110 might change the truth-value of A. */
8117 {
8137 /* This case if tricky because we must either have commutative
8138 operators or else A10 must not have side-effects. */
8144 a01);
8145 }
8147 /* See if we can build a range comparison. */
8153 {
8157 }
8161 {
8165 }
8167 /* Check for the possibility of merging component references. If our
8168 lhs is another similar operation, try to merge its rhs with our
8169 rhs. Then try to merge our lhs and rhs. */
8179 && !flag_sanitize_coverage
8184 {
8191 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8192 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8193 We don't want to pack more than two leafs to a non-IF AND/OR
8194 expression.
8195 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8196 equal to IF-CODE, then we don't want to add right-hand operand.
8197 If the inner right-hand side of left-hand operand has
8198 side-effects, or isn't simple, then we can't add to it,
8199 as otherwise we might destroy if-sequence. */
8202 /* Needed for sequence points to handle trappings, and
8203 side-effects. */
8205 {
8207 arg1);
8209 tem);
8210 }
8211 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8212 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8215 /* Needed for sequence points to handle trappings, and
8216 side-effects. */
8218 {
8223 }
8224 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8225 into (A OR B).
8226 For sequence point consistancy, we need to check for trapping,
8227 and side-effects. */
8231 }
8234 }
8236 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8237 by changing CODE to reduce the magnitude of constants involved in
8238 ARG0 of the comparison.
8239 Returns a canonicalized comparison tree if a simplification was
8240 possible, otherwise returns NULL_TREE.
8241 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8242 valid if signed overflow is undefined. */
8244 static tree
8248 {
8253 /* Match A +- CST code arg1. We can change this only if overflow
8254 is undefined. */
8257 /* In principle pointers also have undefined overflow behavior,
8258 but that causes problems elsewhere. */
8265 /* Identify the constant in arg0 and its sign. */
8269 /* Overflowed constants and zero will cause problems. */
8274 /* See if we can reduce the magnitude of the constant in
8275 arg0 by changing the comparison code. */
8276 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8280 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8284 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8288 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8292 else
8296 /* Now build the constant reduced in magnitude. But not if that
8297 would produce one outside of its types range. */
8313 }
8315 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8316 overflow further. Try to decrease the magnitude of constants involved
8317 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8318 and put sole constants at the second argument position.
8319 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8321 static tree
8324 {
8325 tree t;
8330 /* Try canonicalization by simplifying arg0. */
8335 {
8339 }
8341 /* Try canonicalization by simplifying arg1 using the swapped
8342 comparison. */
8350 }
8352 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8353 space. This is used to avoid issuing overflow warnings for
8354 expressions like &p->x which can not wrap. */
8356 static bool
8358 {
8365 poly_wide_int wi_offset;
8371 else
8376 precision);
8391 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8392 array. */
8401 }
8403 /* Return a positive integer when the symbol DECL is known to have
8404 a nonzero address, zero when it's known not to (e.g., it's a weak
8405 symbol), and a negative integer when the symbol is not yet in the
8406 symbol table and so whether or not its address is zero is unknown.
8407 For function local objects always return positive integer. */
8408 static int
8410 {
8415 /* Function local objects are never NULL. */
8423 }
8425 /* Subroutine of fold_binary. This routine performs all of the
8426 transformations that are common to the equality/inequality
8427 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8428 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8429 fold_binary should call fold_binary. Fold a comparison with
8430 tree code CODE and type TYPE with operands OP0 and OP1. Return
8431 the folded comparison or NULL_TREE. */
8433 static tree
8436 {
8446 /* For comparisons of pointers we can decompose it to a compile time
8447 comparison of the base objects and the offsets into the object.
8448 This requires at least one operand being an ADDR_EXPR or a
8449 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8455 {
8458 machine_mode mode;
8462 /* Get base and offset for the access. Strip ADDR_EXPR for
8463 get_inner_reference, but put it back by stripping INDIRECT_REF
8464 off the base object if possible. indirect_baseN will be true
8465 if baseN is not an address but refers to the object itself. */
8468 {
8469 base0
8475 else
8477 }
8479 {
8483 {
8484 base0
8490 else
8492 }
8495 else
8499 {
8506 }
8507 }
8511 {
8512 base1
8518 else
8520 }
8522 {
8526 {
8527 base1
8533 else
8535 }
8538 else
8542 {
8549 }
8550 }
8552 /* If we have equivalent bases we might be able to simplify. */
8556 {
8557 /* We can fold this expression to a constant if the non-constant
8558 offset parts are equal. */
8562 && (equality_code
8563 || (indirect_base0
8566 {
8572 "occur when comparing P +- C1 with "
8574 WARN_STRICT_OVERFLOW_CONDITIONAL);
8577 {
8615 }
8616 }
8617 /* We can simplify the comparison to a comparison of the variable
8618 offset parts if the constant offset parts are equal.
8619 Be careful to use signed sizetype here because otherwise we
8620 mess with array offsets in the wrong way. This is possible
8621 because pointer arithmetic is restricted to retain within an
8622 object and overflow on pointer differences is undefined as of
8623 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8625 && (equality_code
8626 || (indirect_base0
8629 {
8630 /* By converting to signed sizetype we cover middle-end pointer
8631 arithmetic which operates on unsigned pointer types of size
8632 type size and ARRAY_REF offsets which are properly sign or
8633 zero extended from their type in case it is narrower than
8634 sizetype. */
8637 else
8641 else
8648 "occur when comparing P +- C1 with "
8650 WARN_STRICT_OVERFLOW_COMPARISON);
8653 }
8654 }
8655 /* For equal offsets we can simplify to a comparison of the
8656 base addresses. */
8658 && (indirect_base0
8660 && (indirect_base1
8665 {
8671 }
8672 /* Comparison between an ordinary (non-weak) symbol and a null
8673 pointer can be eliminated since such symbols must have a non
8674 null address. In C, relational expressions between pointers
8675 to objects and null pointers are undefined. The results
8676 below follow the C++ rules with the additional property that
8677 every object pointer compares greater than a null pointer.
8678 */
8681 /* Avoid folding references to struct members at offset 0 to
8682 prevent tests like '&ptr->firstmember == 0' from getting
8683 eliminated. When ptr is null, although the -> expression
8684 is strictly speaking invalid, GCC retains it as a matter
8685 of QoI. See PR c/44555. */
8688 && indirect_base0
8689 /* The caller guarantees that when one of the arguments is
8690 constant (i.e., null in this case) it is second. */
8692 {
8694 {
8705 }
8706 }
8707 }
8709 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8710 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8711 the resulting offset is smaller in absolute value than the
8712 original one and has the same sign. */
8721 {
8726 tree cst;
8728 "occur when combining constants around "
8731 /* Put the constant on the side where it doesn't overflow and is
8732 of lower absolute value and of same sign than before. */
8739 {
8742 variable1,
8746 }
8754 {
8760 variable2);
8761 }
8762 }
8768 /* If we are comparing an expression that just has comparisons
8769 of two integer values, arithmetic expressions of those comparisons,
8770 and constants, we can simplify it. There are only three cases
8771 to check: the two values can either be equal, the first can be
8772 greater, or the second can be greater. Fold the expression for
8773 those three values. Since each value must be 0 or 1, we have
8774 eight possibilities, each of which corresponds to the constant 0
8775 or 1 or one of the six possible comparisons.
8777 This handles common cases like (a > b) == 0 but also handles
8778 expressions like ((x > y) - (y > x)) > 0, which supposedly
8779 occur in macroized code. */
8782 {
8787 /* Don't handle degenerate cases here; they should already
8788 have been handled anyway. */
8797 {
8801 /* We can't just pass T to eval_subst in case cval1 or cval2
8802 was the same as ARG1. */
8804 tree high_result
8808 arg1);
8809 tree equal_result
8813 arg1);
8814 tree low_result
8818 arg1);
8820 /* All three of these results should be 0 or 1. Confirm they are.
8821 Then use those values to select the proper code to use. */
8826 {
8827 /* Make a 3-bit mask with the high-order bit being the
8828 value for `>', the next for '=', and the low for '<'. */
8832 {
8834 /* Always false. */
8855 /* Always true. */
8857 }
8860 {
8864 }
8866 }
8867 }
8868 }
8871 }
8874 /* Subroutine of fold_binary. Optimize complex multiplications of the
8875 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8876 argument EXPR represents the expression "z" of type TYPE. */
8878 static tree
8880 {
8885 {
8888 }
8890 {
8893 }
8894 else
8895 {
8899 }
8908 }
8911 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8912 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8913 true if successful. */
8915 static bool
8917 {
8922 {
8925 }
8927 {
8933 else
8935 }
8936 else
8942 }
8944 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8945 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8946 NULL_TREE otherwise. */
8948 static tree
8950 {
8971 {
8972 HOST_WIDE_INT index;
8978 }
8981 {
8987 }
8988 else
8990 }
8992 /* Try to fold a pointer difference of type TYPE two address expressions of
8993 array references AREF0 and AREF1 using location LOC. Return a
8994 simplified expression for the difference or NULL_TREE. */
8996 static tree
9000 {
9005 /* If the bases are array references as well, recurse. If the bases
9006 are pointer indirections compute the difference of the pointers.
9007 If the bases are equal, we are set. */
9010 && (base_offset
9012 use_pointer_diff)))
9015 && (base_offset
9016 = use_pointer_diff
9026 {
9032 base_offset,
9035 }
9037 }
9039 /* If the real or vector real constant CST of type TYPE has an exact
9040 inverse, return it, else return NULL. */
9042 tree
9044 {
9045 REAL_VALUE_TYPE r;
9046 tree unit_type;
9047 machine_mode mode;
9050 {
9060 {
9064 tree_vector_builder elts;
9069 {
9074 }
9077 }
9081 }
9082 }
9084 /* Mask out the tz least significant bits of X of type TYPE where
9085 tz is the number of trailing zeroes in Y. */
9086 static wide_int
9088 {
9093 }
9095 /* Return true when T is an address and is known to be nonzero.
9096 For floating point we further ensure that T is not denormal.
9097 Similar logic is present in nonzero_address in rtlanal.h.
9099 If the return value is based on the assumption that signed overflow
9100 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9101 change *STRICT_OVERFLOW_P. */
9103 static bool
9105 {
9109 /* Doing something useful for floating point would need more work. */
9115 {
9118 strict_overflow_p);
9124 strict_overflow_p);
9132 }
9135 {
9138 strict_overflow_p);
9146 strict_overflow_p);
9161 strict_overflow_p);
9165 strict_overflow_p);
9168 {
9180 }
9184 }
9186 }
9188 /* Return true when T is an address and is known to be nonzero.
9189 Handle warnings about undefined signed overflow. */
9191 bool
9193 {
9200 "determining that expression is always "
9202 WARN_STRICT_OVERFLOW_MISC);
9204 }
9206 /* Return true if T is known not to be equal to an integer W. */
9208 bool
9210 {
9212 value_range_type rtype;
9214 {
9223 {
9228 }
9233 /* If T has some known zero bits and W has any of those bits set,
9234 then T is known not to be equal to W. */
9242 }
9243 }
9245 /* Fold a binary expression of code CODE and type TYPE with operands
9246 OP0 and OP1. LOC is the location of the resulting expression.
9247 Return the folded expression if folding is successful. Otherwise,
9248 return NULL_TREE. */
9250 tree
9253 {
9268 /* Strip any conversions that don't change the mode. This is
9269 safe for every expression, except for a comparison expression
9270 because its signedness is derived from its operands. So, in
9271 the latter case, only strip conversions that don't change the
9272 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9273 preserved.
9275 Note that this is done as an internal manipulation within the
9276 constant folder, in order to find the simplest representation
9277 of the arguments so that their form can be studied. In any
9278 cases, the appropriate type conversions should be put back in
9279 the tree that will get out of the constant folder. */
9282 {
9285 }
9286 else
9287 {
9290 }
9292 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9293 constant but we can't do arithmetic on them. */
9295 {
9298 {
9302 }
9303 }
9305 /* If this is a commutative operation, and ARG0 is a constant, move it
9306 to ARG1 to reduce the number of tests below. */
9311 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9312 to ARG1 to reduce the number of tests below. */
9321 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9323 First check for cases where an arithmetic operation is applied to a
9324 compound, conditional, or comparison operation. Push the arithmetic
9325 operation inside the compound or conditional to see if any folding
9326 can then be done. Convert comparison to conditional for this purpose.
9327 The also optimizes non-constant cases that used to be done in
9328 expand_expr.
9330 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9331 one of the operands is a comparison and the other is a comparison, a
9332 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9333 code below would make the expression more complex. Change it to a
9334 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9335 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9348 {
9352 boolean_type_node,
9360 }
9364 {
9366 {
9371 tem);
9372 }
9374 {
9379 tem);
9380 }
9385 {
9391 }
9396 {
9402 }
9403 }
9406 {
9408 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9411 {
9417 }
9419 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9422 {
9423 tree base;
9424 poly_int64 coffset;
9433 }
9438 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9444 arg1),
9446 arg0)));
9452 {
9453 /* X + (X / CST) * -CST is X % CST. */
9458 {
9467 cst0));
9468 }
9469 }
9471 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9472 one. Make sure the type is not saturating and has the signedness of
9473 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9474 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9481 {
9485 }
9488 {
9489 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9490 (plus (plus (mult) (mult)) (foo)) so that we can
9491 take advantage of the factoring cases below. */
9500 {
9506 else
9519 parg0),
9521 marg)),
9525 return
9531 parg1)));
9532 }
9533 }
9534 else
9535 {
9536 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9537 to __complex__ ( x, y ). This is not the same for SNaNs or
9538 if signed zeros are involved. */
9542 {
9549 {
9553 {
9559 }
9561 {
9567 }
9568 }
9569 }
9571 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9572 We associate floats only if the user has specified
9573 -fassociative-math. */
9577 {
9582 {
9583 tree tree0;
9586 }
9587 }
9588 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9589 We associate floats only if the user has specified
9590 -fassociative-math. */
9594 {
9599 {
9600 tree tree0;
9603 }
9604 }
9605 }
9607 bit_rotate:
9608 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9609 is a rotate of A by C1 bits. */
9610 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9611 is a rotate of A by B bits.
9612 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9613 though in this case CODE must be | and not + or ^, otherwise
9614 it doesn't return A when B is 0. */
9615 {
9617 tree rtype;
9626 /* Only create rotates in complete modes. Other cases are not
9627 expanded properly. */
9630 {
9643 {
9648 }
9653 {
9656 code0 == LSHIFT_EXPR
9659 }
9661 {
9671 {
9675 orig_tree01);
9677 }
9678 }
9682 {
9693 {
9697 orig_tree01);
9699 }
9700 }
9701 }
9702 }
9704 associate:
9705 /* In most languages, can't associate operations on floats through
9706 parentheses. Rather than remember where the parentheses were, we
9707 don't associate floats at all, unless the user has specified
9708 -fassociative-math.
9709 And, we need to make sure type is not saturating. */
9713 {
9719 /* Split both trees into variables, constants, and literals. Then
9720 associate each group together, the constants with literals,
9721 then the result with variables. This increases the chances of
9722 literals being recombined later and of generating relocatable
9723 expressions for the sum of a constant and literal. */
9731 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9735 /* With undefined overflow prefer doing association in a type
9736 which wraps on overflow, if that is one of the operand types. */
9739 {
9747 }
9749 /* With undefined overflow we can only associate constants with one
9750 variable, and constants whose association doesn't overflow. */
9753 {
9755 {
9756 /* ??? If split_tree would handle NEGATE_EXPR we could
9757 simply reject these cases and the allowed cases would
9758 be the var0/minus_var1 ones. */
9764 {
9767 }
9774 {
9777 }
9783 /* The only case we can still associate with two variables
9784 is if they cancel out. */
9788 }
9794 }
9796 /* Only do something if we found more than two objects. Otherwise,
9797 nothing has changed and we risk infinite recursion. */
9805 {
9817 {
9821 }
9823 {
9827 }
9829 /* Preserve the MINUS_EXPR if the negative part of the literal is
9830 greater than the positive part. Otherwise, the multiplicative
9831 folding code (i.e extract_muldiv) may be fooled in case
9832 unsigned constants are subtracted, like in the following
9833 example: ((X*2 + 4) - 8U)/2. */
9835 {
9839 /* But avoid ending up with only negated parts. */
9841 {
9845 }
9846 else
9847 {
9851 }
9852 }
9854 /* Don't introduce overflows through reassociation. */
9859 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9866 /* Eliminate minus_con0. */
9868 {
9875 else
9878 }
9880 /* Eliminate minus_var0. */
9882 {
9886 else
9889 }
9891 return
9894 }
9895 }
9901 /* Fold &a[i] - &a[j] to i-j. */
9906 {
9910 code
9914 }
9916 /* Further transformations are not for pointers. */
9920 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9923 /* If arg0 is e.g. unsigned int and type is int, then this could
9924 introduce UB, because if A is INT_MIN at runtime, the original
9925 expression can be well defined while the latter is not.
9926 See PR83269. */
9935 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9936 __complex__ ( x, -y ). This is not the same for SNaNs or if
9937 signed zeros are involved. */
9941 {
9948 {
9952 {
9954 arg1r ? arg1r
9959 }
9961 {
9965 arg1i ? arg1i
9968 }
9969 }
9970 }
9972 /* A - B -> A + (-B) if B is easily negatable. */
9976 /* Avoid this transformation if B is a positive REAL_CST. */
9984 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
9985 one. Make sure the type is not saturating and has the signedness of
9986 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9987 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9994 {
9998 }
10004 {
10005 /* Transform x * -C into -x * C if x is easily negatable. */
10020 {
10023 "occur when simplifying "
10025 WARN_STRICT_OVERFLOW_MISC);
10027 }
10029 /* Optimize z * conj(z) for integer complex numbers. */
10036 }
10037 else
10038 {
10039 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10040 This is not the same for NaNs or if signed zeros are
10041 involved. */
10047 {
10050 return
10056 return
10061 }
10063 /* Optimize z * conj(z) for floating point complex numbers.
10064 Guarded by flag_unsafe_math_optimizations as non-finite
10065 imaginary components don't produce scalar results. */
10074 }
10078 /* Canonicalize (X & C1) | C2. */
10082 {
10087 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10095 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10097 {
10100 }
10102 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10103 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10104 mode which allows further optimizations. */
10109 {
10114 {
10117 }
10118 }
10121 {
10126 }
10127 }
10129 /* See if this can be simplified into a rotate first. If that
10130 is unsuccessful continue in the association code. */
10134 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10142 /* See if this can be simplified into a rotate first. If that
10143 is unsuccessful continue in the association code. */
10147 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10152 {
10153 tree tem2;
10160 }
10161 /* Fold ~X & 1 as (X & 1) == 0. */
10165 {
10166 tree tem2;
10173 }
10174 /* Fold !X & 1 as X == 0. */
10177 {
10181 }
10183 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10184 multiple of 1 << CST. */
10186 {
10193 }
10195 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10196 bits from CST2. */
10200 {
10202 wide_int masked
10209 {
10210 /* Avoid the transform if arg1 is a mask of some
10211 mode which allows further optimizations. */
10218 }
10219 }
10221 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
10222 ((A & N) + B) & M -> (A + B) & M
10223 Similarly if (N & M) == 0,
10224 ((A | N) + B) & M -> (A + B) & M
10225 and for - instead of + (or unary - instead of +)
10226 and/or ^ instead of |.
10227 If B is constant and (B & M) == 0, fold into A & M. */
10229 {
10238 {
10241 wide_int cst0;
10243 /* Now we know that arg0 is (C + D) or (C - D) or
10244 -C and arg1 (M) is == (1LL << cst) - 1.
10245 Store C into PMOP[0] and D into PMOP[1]. */
10249 {
10252 }
10259 {
10268 {
10271 }
10274 /* If C or D is of the form (A & N) where
10275 (N & M) == M, or of the form (A | N) or
10276 (A ^ N) where (N & M) == 0, replace it with A. */
10280 /* If C or D is a N where (N & M) == 0, it can be
10281 omitted (assumed 0). */
10289 }
10291 /* Only build anything new if we optimized one or both arguments
10292 above. */
10296 {
10299 {
10300 /* Perform the operations in a type that has defined
10301 overflow behavior. */
10307 }
10312 {
10320 else
10322 }
10325 else
10328 /* TEM is now the new binary +, - or unary - replacement. */
10332 }
10333 }
10334 }
10336 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10339 {
10344 return
10346 }
10351 /* Don't touch a floating-point divide by zero unless the mode
10352 of the constant can represent infinity. */
10358 /* (-A) / (-B) -> A / B */
10370 /* Fall through */
10373 /* Simplify A / (B << N) where A and B are positive and B is
10374 a power of 2, to A >> (N + log2(B)). */
10379 {
10382 {
10390 WARN_STRICT_OVERFLOW_MISC);
10396 }
10397 }
10399 /* Fall through */
10407 /* Convert -A / -B to A / B when the type is signed and overflow is
10408 undefined. */
10412 {
10415 "when distributing negation across "
10417 WARN_STRICT_OVERFLOW_MISC);
10422 }
10426 {
10429 "when distributing negation across "
10431 WARN_STRICT_OVERFLOW_MISC);
10436 }
10438 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10439 operation, EXACT_DIV_EXPR.
10441 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10442 At one time others generated faster code, it's not clear if they do
10443 after the last round to changes to the DIV code in expmed.c. */
10454 {
10458 WARN_STRICT_OVERFLOW_MISC);
10460 }
10472 {
10476 WARN_STRICT_OVERFLOW_MISC);
10478 }
10486 /* Since negative shift count is not well-defined,
10487 don't try to compute it in the compiler. */
10493 /* If we have a rotate of a bit operation with the rotate count and
10494 the second operand of the bit operation both constant,
10495 permute the two operations. */
10501 {
10509 }
10511 /* Two consecutive rotates adding up to the some integer
10512 multiple of the precision of the type can be ignored. */
10528 /* Note that the operands of this must be ints
10529 and their values must be 0 or 1.
10530 ("true" is a fixed value perhaps depending on the language.) */
10531 /* If first arg is constant zero, return it. */
10534 /* FALLTHRU */
10536 /* If either arg is constant true, drop it. */
10540 /* Preserve sequence points. */
10543 /* If second arg is constant zero, result is zero, but first arg
10544 must be evaluated. */
10547 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10548 case will be handled here. */
10552 /* !X && X is always false. */
10556 /* X && !X is always false. */
10561 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10562 means A >= Y && A != MAX, but in this case we know that
10563 A < X <= MAX. */
10567 {
10575 }
10584 /* Note that the operands of this must be ints
10585 and their values must be 0 or true.
10586 ("true" is a fixed value perhaps depending on the language.) */
10587 /* If first arg is constant true, return it. */
10590 /* FALLTHRU */
10592 /* If either arg is constant zero, drop it. */
10596 /* Preserve sequence points. */
10599 /* If second arg is constant true, result is true, but we must
10600 evaluate first arg. */
10603 /* Likewise for first arg, but note this only occurs here for
10604 TRUTH_OR_EXPR. */
10608 /* !X || X is always true. */
10612 /* X || !X is always true. */
10617 /* (X && !Y) || (!X && Y) is X ^ Y */
10620 {
10637 }
10646 /* If the second arg is constant zero, drop it. */
10649 /* If the second arg is constant true, this is a logical inversion. */
10651 {
10654 }
10655 /* Identical arguments cancel to zero. */
10659 /* !X ^ X is always true. */
10664 /* X ^ !X is always true. */
10680 /* bool_var != 1 becomes !bool_var. */
10687 /* bool_var == 0 becomes !bool_var. */
10694 /* !exp != 0 becomes !exp */
10699 /* If this is an EQ or NE comparison with zero and ARG0 is
10700 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10701 two operations, but the latter can be done in one less insn
10702 on machines that have only two-operand insns or on which a
10703 constant cannot be the first operand. */
10706 {
10711 {
10718 arg1);
10719 }
10722 {
10729 arg1);
10730 }
10731 }
10733 /* If this is an NE or EQ comparison of zero against the result of a
10734 signed MOD operation whose second operand is a power of 2, make
10735 the MOD operation unsigned since it is simpler and equivalent. */
10743 {
10753 }
10755 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10756 C1 is a valid shift constant, and C2 is a power of two, i.e.
10757 a single bit. */
10761 == INTEGER_CST
10764 {
10769 /* Check for a valid shift count. */
10771 {
10775 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10776 can be rewritten as (X & (C2 << C1)) != 0. */
10778 {
10783 }
10784 /* Otherwise, for signed (arithmetic) shifts,
10785 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10786 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10790 /* Otherwise, of unsigned (logical) shifts,
10791 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10792 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10793 else
10797 arg000);
10798 }
10799 }
10801 /* If this is a comparison of a field, we may be able to simplify it. */
10804 /* Handle the constant case even without -O
10805 to make sure the warnings are given. */
10807 {
10811 }
10813 /* Optimize comparisons of strlen vs zero to a compare of the
10814 first character of the string vs zero. To wit,
10815 strlen(ptr) == 0 => *ptr == 0
10816 strlen(ptr) != 0 => *ptr != 0
10817 Other cases should reduce to one of these two (or a constant)
10818 due to the return value of strlen being unsigned. */
10821 {
10829 {
10834 }
10835 }
10837 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10838 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10842 {
10847 {
10849 {
10852 }
10855 }
10856 }
10858 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10859 (X & C) == 0 when C is a single bit. */
10864 {
10871 arg1));
10872 }
10874 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10875 constant C is a power of two, i.e. a single bit. */
10882 {
10886 }
10888 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10889 when is C is a power of two, i.e. a single bit. */
10896 {
10902 }
10906 {
10909 }
10911 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10914 {
10922 {
10928 }
10930 {
10936 }
10938 {
10944 }
10946 {
10952 }
10953 }
10957 {
10964 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10965 operand_equal_p guarantees no side-effects so we don't need
10966 to use omit_one_operand on Z. */
10970 arg10));
10974 arg11));
10978 arg10));
10982 arg11));
10984 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10987 {
10993 }
10994 }
10996 /* Attempt to simplify equality/inequality comparisons of complex
10997 values. Only lower the comparison if the result is known or
10998 can be simplified to a single scalar comparison. */
11003 {
11008 {
11011 }
11012 else
11013 {
11016 }
11019 {
11022 }
11023 else
11024 {
11027 }
11031 {
11033 {
11038 }
11039 else
11040 {
11045 }
11046 }
11050 {
11052 {
11057 }
11058 else
11059 {
11064 }
11065 }
11066 }
11078 /* Transform comparisons of the form X +- C CMP X. */
11083 {
11088 /* (X - c) > X becomes false. */
11094 /* Likewise (X + c) < X becomes false. */
11100 /* Convert (X - c) <= X to true. */
11107 /* Convert (X + c) >= X to true. */
11113 }
11115 /* If we are comparing an ABS_EXPR with a constant, we can
11116 convert all the cases into explicit comparisons, but they may
11117 well not be faster than doing the ABS and one comparison.
11118 But ABS (X) <= C is a range comparison, which becomes a subtraction
11119 and a comparison, and is probably faster. */
11133 /* Convert ABS_EXPR<x> >= 0 to true. */
11140 {
11143 "when simplifying comparison of "
11145 WARN_STRICT_OVERFLOW_CONDITIONAL);
11148 arg0);
11149 }
11151 /* Convert ABS_EXPR<x> < 0 to false. */
11156 {
11159 "when simplifying comparison of "
11161 WARN_STRICT_OVERFLOW_CONDITIONAL);
11164 arg0);
11165 }
11167 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11168 and similarly for >= into !=. */
11178 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11179 otherwise Y might be >= # of bits in X's type and thus e.g.
11180 (unsigned char) (1 << Y) for Y 15 might be 0.
11181 If the cast is widening, then 1 << Y should have unsigned type,
11182 otherwise if Y is number of bits in the signed shift type minus 1,
11183 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11184 31 might be 0xffffffff80000000. */
11195 {
11201 }
11213 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11214 {
11226 }
11231 /* When pedantic, a compound expression can be neither an lvalue
11232 nor an integer constant expression. */
11235 /* Don't let (0, 0) be null pointer constant. */
11241 /* An ASSERT_EXPR should never be passed to fold_binary. */
11247 }
11249 /* Used by contains_label_[p1]. */
11251 struct contains_label_data
11252 {
11255 };
11257 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11258 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11259 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11261 static tree
11263 {
11266 {
11277 {
11285 }
11294 }
11295 }
11297 /* Return whether the sub-tree ST contains a label which is accessible from
11298 outside the sub-tree. */
11300 static bool
11302 {
11306 }
11308 /* Fold a ternary expression of code CODE and type TYPE with operands
11309 OP0, OP1, and OP2. Return the folded expression if folding is
11310 successful. Otherwise, return NULL_TREE. */
11312 tree
11315 {
11316 tree tem;
11323 /* If this is a commutative operation, and OP0 is a constant, move it
11324 to OP1 to reduce the number of tests below. */
11333 /* Strip any conversions that don't change the mode. This is safe
11334 for every expression, except for a comparison expression because
11335 its signedness is derived from its operands. So, in the latter
11336 case, only strip conversions that don't change the signedness.
11338 Note that this is done as an internal manipulation within the
11339 constant folder, in order to find the simplest representation of
11340 the arguments so that their form can be studied. In any cases,
11341 the appropriate type conversions should be put back in the tree
11342 that will get out of the constant folder. */
11344 {
11347 }
11350 {
11353 }
11356 {
11359 }
11362 {
11366 {
11372 }
11377 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11378 so all simple results must be passed through pedantic_non_lvalue. */
11380 {
11383 /* Only optimize constant conditions when the selected branch
11384 has the same type as the COND_EXPR. This avoids optimizing
11385 away "c ? x : throw", where the throw has a void type.
11386 Avoid throwing away that operand which contains label. */
11393 }
11395 {
11402 {
11405 {
11413 }
11418 }
11419 }
11421 /* If we have A op B ? A : C, we may be able to convert this to a
11422 simpler expression, depending on the operation and the values
11423 of B and C. Signed zeros prevent all of these transformations,
11424 for reasons given above each one.
11426 Also try swapping the arguments and inverting the conditional. */
11430 {
11434 }
11439 {
11443 {
11447 }
11448 }
11450 /* If the second operand is simpler than the third, swap them
11451 since that produces better jump optimization results. */
11454 {
11456 /* See if this can be inverted. If it can't, possibly because
11457 it was a floating-point inequality comparison, don't do
11458 anything. */
11462 }
11464 /* Convert A ? 1 : 0 to simply A. */
11469 /* If we try to convert OP0 to our type, the
11470 call to fold will try to move the conversion inside
11471 a COND, which will recurse. In that case, the COND_EXPR
11472 is probably the best choice, so leave it alone. */
11476 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11477 over COND_EXPR in cases such as floating point comparisons. */
11486 arg0)));
11488 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11493 {
11494 /* sign_bit_p looks through both zero and sign extensions,
11495 but for this optimization only sign extensions are
11496 usable. */
11499 {
11502 {
11505 }
11507 }
11508 /* sign_bit_p only checks ARG1 bits within A's precision.
11509 If <sign bit of A> has wider type than A, bits outside
11510 of A's precision in <sign bit of A> need to be checked.
11511 If they are all 0, this optimization needs to be done
11512 in unsigned A's type, if they are all 1 in signed A's type,
11513 otherwise this can't be done. */
11519 {
11521 tree tem_type;
11534 {
11537 }
11539 {
11542 }
11543 else
11545 }
11548 return
11554 arg1)));
11555 }
11557 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11558 already handled above. */
11563 {
11573 op1);
11574 }
11576 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11577 is probably obsolete because the first operand should be a
11578 truth value (that's why we have the two cases above), but let's
11579 leave it in until we can confirm this for all front-ends. */
11591 /* Disable the transformations below for vectors, since
11592 fold_binary_op_with_conditional_arg may undo them immediately,
11593 yielding an infinite loop. */
11597 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11606 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11611 {
11613 /* Only perform transformation if ARG0 is easily inverted. */
11617 ? BIT_IOR_EXPR
11620 op1);
11621 }
11623 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11628 {
11630 /* Only perform transformation if ARG0 is easily inverted. */
11636 op2);
11637 }
11639 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11651 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11652 of fold_ternary on them. */
11662 {
11673 {
11678 {
11686 }
11687 }
11688 }
11690 /* On constants we can use native encode/interpret to constant
11691 fold (nearly) all BIT_FIELD_REFs. */
11697 {
11700 /* Limit us to a reasonable amount of work. To relax the
11701 other limitations we need bit-shifting of the buffer
11702 and rounding up the size. */
11706 {
11708 unsigned HOST_WIDE_INT len
11713 {
11718 }
11719 }
11720 }
11725 /* For integers we can decompose the FMA if possible. */
11737 {
11738 /* Build a vector of integers from the tree mask. */
11739 vec_perm_builder builder;
11743 /* Create a vec_perm_indices for the integer vector. */
11748 /* Check for cases that fold to OP0 or OP1 in their original
11749 element order. */
11756 {
11760 {
11763 }
11764 }
11770 {
11774 }
11778 /* Generate a canonical form of the selector. */
11780 {
11781 /* Some targets are deficient and fail to expand a single
11782 argument permutation while still allowing an equivalent
11783 2-argument version. */
11787 else
11788 {
11792 else
11793 /* Not directly supported with either encoding,
11794 so use the preferred form. */
11796 }
11798 }
11802 }
11806 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11809 {
11815 wide_int tem2
11819 }
11824 {
11826 unsigned HOST_WIDE_INT elsize
11829 {
11835 {
11841 }
11842 }
11843 }
11849 }
11851 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11852 of an array (or vector). */
11854 tree
11856 {
11861 {
11864 {
11865 /* Static constructors for variably sized objects makes no sense. */
11869 }
11870 }
11881 offset_int max_index;
11886 {
11887 /* Array constructor might explicitly set index, or specify a range,
11888 or leave index NULL meaning that it is next index after previous
11889 one. */
11891 {
11894 else
11895 {
11899 }
11900 }
11901 else
11902 {
11908 }
11910 /* Do we have match? */
11914 }
11916 }
11918 /* Perform constant folding and related simplification of EXPR.
11919 The related simplifications include x*1 => x, x*0 => 0, etc.,
11920 and application of the associative law.
11921 NOP_EXPR conversions may be removed freely (as long as we
11922 are careful not to change the type of the overall expression).
11923 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11924 but we can constant-fold them if they have constant operands. */
11926 #ifdef ENABLE_FOLD_CHECKING
11927 # define fold(x) fold_1 (x)
11929 static
11930 #endif
11931 tree
11933 {
11937 tree tem;
11940 /* Return right away if a constant. */
11944 /* CALL_EXPR-like objects with variable numbers of operands are
11945 treated specially. */
11947 {
11949 {
11952 }
11954 }
11957 {
11962 {
11980 }
11981 }
11984 {
11986 {
11993 {
11998 }
12001 }
12003 /* Return a VECTOR_CST if possible. */
12005 {
12011 tree val;
12017 }
12025 }
12027 #ifdef ENABLE_FOLD_CHECKING
12028 #undef fold
12035 /* When --enable-checking=fold, compute a digest of expr before
12036 and after actual fold call to see if fold did not accidentally
12037 change original expr. */
12039 tree
12041 {
12042 tree ret;
12062 }
12064 void
12066 {
12077 }
12079 static void
12081 {
12083 }
12085 static void
12088 {
12094 recursive_label:
12104 {
12105 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12110 }
12118 {
12119 /* Allow these fields to be modified. */
12120 tree tmp;
12129 {
12132 }
12133 }
12144 {
12147 {
12163 }
12167 {
12180 }
12197 {
12203 }
12206 {
12208 {
12211 }
12213 }
12224 {
12227 }
12237 }
12238 }
12240 /* Helper function for outputting the checksum of a tree T. When
12241 debugging with gdb, you can "define mynext" to be "next" followed
12242 by "call debug_fold_checksum (op0)", then just trace down till the
12243 outputs differ. */
12245 DEBUG_FUNCTION void
12247 {
12262 }
12264 #endif
12266 /* Fold a unary tree expression with code CODE of type TYPE with an
12267 operand OP0. LOC is the location of the resulting expression.
12268 Return a folded expression if successful. Otherwise, return a tree
12269 expression with code CODE of type TYPE with an operand OP0. */
12271 tree
12274 {
12275 tree tem;
12276 #ifdef ENABLE_FOLD_CHECKING
12285 #endif
12291 #ifdef ENABLE_FOLD_CHECKING
12298 #endif
12300 }
12302 /* Fold a binary tree expression with code CODE of type TYPE with
12303 operands OP0 and OP1. LOC is the location of the resulting
12304 expression. Return a folded expression if successful. Otherwise,
12305 return a tree expression with code CODE of type TYPE with operands
12306 OP0 and OP1. */
12308 tree
12311 MEM_STAT_DECL)
12312 {
12313 tree tem;
12314 #ifdef ENABLE_FOLD_CHECKING
12331 #endif
12337 #ifdef ENABLE_FOLD_CHECKING
12352 #endif
12354 }
12356 /* Fold a ternary tree expression with code CODE of type TYPE with
12357 operands OP0, OP1, and OP2. Return a folded expression if
12358 successful. Otherwise, return a tree expression with code CODE of
12359 type TYPE with operands OP0, OP1, and OP2. */
12361 tree
12364 {
12365 tree tem;
12366 #ifdef ENABLE_FOLD_CHECKING
12390 #endif
12397 #ifdef ENABLE_FOLD_CHECKING
12420 #endif
12422 }
12424 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12425 arguments in ARGARRAY, and a null static chain.
12426 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12427 of type TYPE from the given operands as constructed by build_call_array. */
12429 tree
12432 {
12433 tree tem;
12434 #ifdef ENABLE_FOLD_CHECKING
12453 #endif
12459 #ifdef ENABLE_FOLD_CHECKING
12475 #endif
12477 }
12479 /* Perform constant folding and related simplification of initializer
12480 expression EXPR. These behave identically to "fold_buildN" but ignore
12481 potential run-time traps and exceptions that fold must preserve. */
12483 #define START_FOLD_INIT \
12484 int saved_signaling_nans = flag_signaling_nans;\
12485 int saved_trapping_math = flag_trapping_math;\
12486 int saved_rounding_math = flag_rounding_math;\
12487 int saved_trapv = flag_trapv;\
12488 int saved_folding_initializer = folding_initializer;\
12489 flag_signaling_nans = 0;\
12490 flag_trapping_math = 0;\
12491 flag_rounding_math = 0;\
12492 flag_trapv = 0;\
12493 folding_initializer = 1;
12495 #define END_FOLD_INIT \
12496 flag_signaling_nans = saved_signaling_nans;\
12497 flag_trapping_math = saved_trapping_math;\
12498 flag_rounding_math = saved_rounding_math;\
12499 flag_trapv = saved_trapv;\
12500 folding_initializer = saved_folding_initializer;
12502 tree
12505 {
12506 tree result;
12507 START_FOLD_INIT;
12511 END_FOLD_INIT;
12513 }
12515 tree
12518 {
12519 tree result;
12520 START_FOLD_INIT;
12524 END_FOLD_INIT;
12526 }
12528 tree
12531 {
12532 tree result;
12533 START_FOLD_INIT;
12537 END_FOLD_INIT;
12539 }
12541 #undef START_FOLD_INIT
12542 #undef END_FOLD_INIT
12544 /* Determine if first argument is a multiple of second argument. Return 0 if
12545 it is not, or we cannot easily determined it to be.
12547 An example of the sort of thing we care about (at this point; this routine
12548 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12549 fold cases do now) is discovering that
12551 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12553 is a multiple of
12555 SAVE_EXPR (J * 8)
12557 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12559 This code also handles discovering that
12561 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12563 is a multiple of 8 so we don't have to worry about dealing with a
12564 possible remainder.
12566 Note that we *look* inside a SAVE_EXPR only to determine how it was
12567 calculated; it is not safe for fold to do much of anything else with the
12568 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12569 at run time. For example, the latter example above *cannot* be implemented
12570 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12571 evaluation time of the original SAVE_EXPR is not necessarily the same at
12572 the time the new expression is evaluated. The only optimization of this
12573 sort that would be valid is changing
12575 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12577 divided by 8 to
12579 SAVE_EXPR (I) * SAVE_EXPR (J)
12581 (where the same SAVE_EXPR (J) is used in the original and the
12582 transformed version). */
12584 int
12586 {
12597 {
12599 /* Bitwise and provides a power of two multiple. If the mask is
12600 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12608 {
12614 {
12617 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12619 {
12623 {
12626 }
12627 }
12629 }
12630 }
12635 /* It is impossible to prove if op0 - op1 is multiple of bottom
12636 precisely, so be conservative here checking if both op0 and op1
12637 are multiple of bottom. Note we check the second operand first
12638 since it's usually simpler. */
12643 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12644 as op0 - 3 if the expression has unsigned type. For example,
12645 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12655 {
12657 /* const_binop may not detect overflow correctly,
12658 so check for it explicitly here. */
12666 }
12670 /* Can't handle conversions from non-integral or wider integral type. */
12676 /* fall through */
12693 SIGNED);
12699 {
12702 /* Check for special cases to see if top is defined as multiple
12703 of bottom:
12705 top = (X & ~(bottom - 1) ; bottom is power of 2
12707 or
12709 Y = X % bottom
12710 top = X - Y. */
12729 }
12731 /* fall through */
12739 }
12740 }
12742 #define tree_expr_nonnegative_warnv_p(X, Y) \
12745 #define RECURSE(X) \
12746 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12748 /* Return true if CODE or TYPE is known to be non-negative. */
12750 static bool
12752 {
12755 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12756 have a signed:1 type (where the value is -1 and 0). */
12759 }
12761 /* Return true if (CODE OP0) is known to be non-negative. If the return
12762 value is based on the assumption that signed overflow is undefined,
12763 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12764 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12766 bool
12769 {
12774 {
12776 /* We can't return 1 if flag_wrapv is set because
12777 ABS_EXPR<INT_MIN> = INT_MIN. */
12781 {
12784 }
12792 CASE_CONVERT:
12793 {
12798 {
12802 {
12806 }
12807 }
12809 {
12815 }
12816 }
12821 }
12823 /* We don't know sign of `t', so be conservative and return false. */
12825 }
12827 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12828 value is based on the assumption that signed overflow is undefined,
12829 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12830 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12832 bool
12836 {
12841 {
12847 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12848 both unsigned and at least 2 bits shorter than the result. */
12852 {
12857 {
12861 }
12862 }
12867 {
12868 /* x * x is always non-negative for floating point x
12869 or without overflow. */
12872 {
12877 }
12878 }
12880 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12881 both unsigned and their total bits is shorter than the result. */
12885 {
12904 {
12914 }
12915 }
12942 }
12944 /* We don't know sign of `t', so be conservative and return false. */
12946 }
12948 /* Return true if T is known to be non-negative. If the return
12949 value is based on the assumption that signed overflow is undefined,
12950 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12951 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12953 bool
12955 {
12960 {
12974 /* Limit the depth of recursion to avoid quadratic behavior.
12975 This is expected to catch almost all occurrences in practice.
12976 If this code misses important cases that unbounded recursion
12977 would not, passes that need this information could be revised
12978 to provide it through dataflow propagation. */
12986 }
12987 }
12989 /* Return true if T is known to be non-negative. If the return
12990 value is based on the assumption that signed overflow is undefined,
12991 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12992 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12994 bool
12997 {
12999 {
13000 CASE_CFN_ACOS:
13001 CASE_CFN_ACOSH:
13002 CASE_CFN_CABS:
13003 CASE_CFN_COSH:
13004 CASE_CFN_ERFC:
13005 CASE_CFN_EXP:
13006 CASE_CFN_EXP10:
13007 CASE_CFN_EXP2:
13008 CASE_CFN_FABS:
13009 CASE_CFN_FDIM:
13010 CASE_CFN_HYPOT:
13011 CASE_CFN_POW10:
13012 CASE_CFN_FFS:
13013 CASE_CFN_PARITY:
13014 CASE_CFN_POPCOUNT:
13015 CASE_CFN_CLZ:
13016 CASE_CFN_CLRSB:
13019 /* Always true. */
13022 CASE_CFN_SQRT:
13023 CASE_CFN_SQRT_FN:
13024 /* sqrt(-0.0) is -0.0. */
13029 CASE_CFN_ASINH:
13030 CASE_CFN_ATAN:
13031 CASE_CFN_ATANH:
13032 CASE_CFN_CBRT:
13033 CASE_CFN_CEIL:
13034 CASE_CFN_CEIL_FN:
13035 CASE_CFN_ERF:
13036 CASE_CFN_EXPM1:
13037 CASE_CFN_FLOOR:
13038 CASE_CFN_FLOOR_FN:
13039 CASE_CFN_FMOD:
13040 CASE_CFN_FREXP:
13041 CASE_CFN_ICEIL:
13042 CASE_CFN_IFLOOR:
13043 CASE_CFN_IRINT:
13044 CASE_CFN_IROUND:
13045 CASE_CFN_LCEIL:
13046 CASE_CFN_LDEXP:
13047 CASE_CFN_LFLOOR:
13048 CASE_CFN_LLCEIL:
13049 CASE_CFN_LLFLOOR:
13050 CASE_CFN_LLRINT:
13051 CASE_CFN_LLROUND:
13052 CASE_CFN_LRINT:
13053 CASE_CFN_LROUND:
13054 CASE_CFN_MODF:
13055 CASE_CFN_NEARBYINT:
13056 CASE_CFN_NEARBYINT_FN:
13057 CASE_CFN_RINT:
13058 CASE_CFN_RINT_FN:
13059 CASE_CFN_ROUND:
13060 CASE_CFN_ROUND_FN:
13061 CASE_CFN_SCALB:
13062 CASE_CFN_SCALBLN:
13063 CASE_CFN_SCALBN:
13064 CASE_CFN_SIGNBIT:
13065 CASE_CFN_SIGNIFICAND:
13066 CASE_CFN_SINH:
13067 CASE_CFN_TANH:
13068 CASE_CFN_TRUNC:
13069 CASE_CFN_TRUNC_FN:
13070 /* True if the 1st argument is nonnegative. */
13073 CASE_CFN_FMAX:
13074 CASE_CFN_FMAX_FN:
13075 /* True if the 1st OR 2nd arguments are nonnegative. */
13078 CASE_CFN_FMIN:
13079 CASE_CFN_FMIN_FN:
13080 /* True if the 1st AND 2nd arguments are nonnegative. */
13083 CASE_CFN_COPYSIGN:
13084 CASE_CFN_COPYSIGN_FN:
13085 /* True if the 2nd argument is nonnegative. */
13088 CASE_CFN_POWI:
13089 /* True if the 1st argument is nonnegative or the second
13090 argument is an even integer. */
13096 CASE_CFN_POW:
13097 /* True if the 1st argument is nonnegative or the second
13098 argument is an even integer valued real. */
13100 {
13101 REAL_VALUE_TYPE c;
13102 HOST_WIDE_INT n;
13107 {
13108 REAL_VALUE_TYPE cint;
13112 }
13113 }
13118 }
13120 }
13122 /* Return true if T is known to be non-negative. If the return
13123 value is based on the assumption that signed overflow is undefined,
13124 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13125 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13127 static bool
13129 {
13135 {
13137 {
13141 /* If the initializer is non-void, then it's a normal expression
13142 that will be assigned to the slot. */
13146 /* Otherwise, the initializer sets the slot in some way. One common
13147 way is an assignment statement at the end of the initializer. */
13149 {
13157 else
13159 }
13165 }
13168 {
13174 arg0,
13175 arg1,
13177 }
13190 }
13191 }
13193 #undef RECURSE
13194 #undef tree_expr_nonnegative_warnv_p
13196 /* Return true if T is known to be non-negative. If the return
13197 value is based on the assumption that signed overflow is undefined,
13198 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13199 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13201 bool
13203 {
13210 {
13232 }
13235 {
13261 }
13262 }
13264 /* Return true if `t' is known to be non-negative. Handle warnings
13265 about undefined signed overflow. */
13267 bool
13269 {
13276 "determining that expression is always "
13278 WARN_STRICT_OVERFLOW_MISC);
13280 }
13283 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13284 For floating point we further ensure that T is not denormal.
13285 Similar logic is present in nonzero_address in rtlanal.h.
13287 If the return value is based on the assumption that signed overflow
13288 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13289 change *STRICT_OVERFLOW_P. */
13291 bool
13294 {
13296 {
13299 strict_overflow_p);
13302 {
13308 strict_overflow_p));
13309 }
13314 strict_overflow_p);
13318 }
13321 }
13323 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13324 For floating point we further ensure that T is not denormal.
13325 Similar logic is present in nonzero_address in rtlanal.h.
13327 If the return value is based on the assumption that signed overflow
13328 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13329 change *STRICT_OVERFLOW_P. */
13331 bool
13333 tree type,
13334 tree op0,
13336 {
13339 {
13343 {
13344 /* With the presence of negative values it is hard
13345 to say something. */
13352 /* One of operands must be positive and the other non-negative. */
13353 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13354 overflows, on a twos-complement machine the sum of two
13355 nonnegative numbers can never be zero. */
13357 strict_overflow_p)
13359 strict_overflow_p));
13360 }
13365 {
13367 strict_overflow_p)
13369 strict_overflow_p))
13370 {
13373 }
13374 }
13383 {
13386 }
13393 {
13397 /* When both operands are nonzero, then MAX must be too. */
13399 strict_overflow_p))
13402 /* MAX where operand 0 is positive is positive. */
13404 strict_overflow_p);
13405 }
13406 /* MAX where operand 1 is positive is positive. */
13411 {
13415 }
13420 strict_overflow_p)
13422 strict_overflow_p));
13426 }
13429 }
13431 /* Return true when T is an address and is known to be nonzero.
13432 For floating point we further ensure that T is not denormal.
13433 Similar logic is present in nonzero_address in rtlanal.h.
13435 If the return value is based on the assumption that signed overflow
13436 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13437 change *STRICT_OVERFLOW_P. */
13439 bool
13441 {
13444 {
13449 {
13461 /* For objects in symbol table check if we know they are non-zero.
13462 Don't do anything for variables and functions before symtab is built;
13463 it is quite possible that they will be declared weak later. */
13468 /* Constants are never weak. */
13473 }
13481 {
13485 }
13495 }
13497 }
13499 #define integer_valued_real_p(X) \
13502 #define RECURSE(X) \
13503 ((integer_valued_real_p) (X, depth + 1))
13505 /* Return true if the floating point result of (CODE OP0) has an
13506 integer value. We also allow +Inf, -Inf and NaN to be considered
13507 integer values. Return false for signaling NaN.
13509 DEPTH is the current nesting depth of the query. */
13511 bool
13513 {
13515 {
13522 CASE_CONVERT:
13523 {
13530 }
13534 }
13536 }
13538 /* Return true if the floating point result of (CODE OP0 OP1) has an
13539 integer value. We also allow +Inf, -Inf and NaN to be considered
13540 integer values. Return false for signaling NaN.
13542 DEPTH is the current nesting depth of the query. */
13544 bool
13546 {
13548 {
13558 }
13560 }
13562 /* Return true if the floating point result of calling FNDECL with arguments
13563 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13564 considered integer values. Return false for signaling NaN. If FNDECL
13565 takes fewer than 2 arguments, the remaining ARGn are null.
13567 DEPTH is the current nesting depth of the query. */
13569 bool
13571 {
13573 {
13574 CASE_CFN_CEIL:
13575 CASE_CFN_CEIL_FN:
13576 CASE_CFN_FLOOR:
13577 CASE_CFN_FLOOR_FN:
13578 CASE_CFN_NEARBYINT:
13579 CASE_CFN_NEARBYINT_FN:
13580 CASE_CFN_RINT:
13581 CASE_CFN_RINT_FN:
13582 CASE_CFN_ROUND:
13583 CASE_CFN_ROUND_FN:
13584 CASE_CFN_TRUNC:
13585 CASE_CFN_TRUNC_FN:
13588 CASE_CFN_FMIN:
13589 CASE_CFN_FMIN_FN:
13590 CASE_CFN_FMAX:
13591 CASE_CFN_FMAX_FN:
13596 }
13598 }
13600 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13601 has an integer value. We also allow +Inf, -Inf and NaN to be
13602 considered integer values. Return false for signaling NaN.
13604 DEPTH is the current nesting depth of the query. */
13606 bool
13608 {
13610 {
13618 /* Limit the depth of recursion to avoid quadratic behavior.
13619 This is expected to catch almost all occurrences in practice.
13620 If this code misses important cases that unbounded recursion
13621 would not, passes that need this information could be revised
13622 to provide it through dataflow propagation. */
13626 depth));
13630 }
13632 }
13634 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13635 has an integer value. We also allow +Inf, -Inf and NaN to be
13636 considered integer values. Return false for signaling NaN.
13638 DEPTH is the current nesting depth of the query. */
13640 static bool
13642 {
13644 {
13655 }
13657 }
13659 #undef RECURSE
13660 #undef integer_valued_real_p
13662 /* Return true if the floating point expression T has an integer value.
13663 We also allow +Inf, -Inf and NaN to be considered integer values.
13664 Return false for signaling NaN.
13666 DEPTH is the current nesting depth of the query. */
13668 bool
13670 {
13676 {
13692 }
13695 {
13701 {
13710 }
13714 }
13715 }
13717 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13718 attempt to fold the expression to a constant without modifying TYPE,
13719 OP0 or OP1.
13721 If the expression could be simplified to a constant, then return
13722 the constant. If the expression would not be simplified to a
13723 constant, then return NULL_TREE. */
13725 tree
13727 {
13730 }
13732 /* Given the components of a unary expression CODE, TYPE and OP0,
13733 attempt to fold the expression to a constant without modifying
13734 TYPE or OP0.
13736 If the expression could be simplified to a constant, then return
13737 the constant. If the expression would not be simplified to a
13738 constant, then return NULL_TREE. */
13740 tree
13742 {
13745 }
13747 /* If EXP represents referencing an element in a constant string
13748 (either via pointer arithmetic or array indexing), return the
13749 tree representing the value accessed, otherwise return NULL. */
13751 tree
13753 {
13757 {
13759 tree index;
13760 tree string;
13765 else
13766 {
13770 /* Optimize the special-case of a zero lower bound.
13772 We convert the low_bound to sizetype to avoid some problems
13773 with constant folding. (E.g. suppose the lower bound is 1,
13774 and its mode is QI. Without the conversion,l (ARRAY
13775 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13776 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13782 }
13784 scalar_int_mode char_mode;
13796 }
13798 }
13800 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13801 an integer constant, real, or fixed-point constant.
13803 TYPE is the type of the result. */
13805 static tree
13807 {
13811 {
13817 {
13818 FIXED_VALUE_TYPE f;
13823 /* Propagate overflow flags. */
13827 }
13831 {
13838 }
13841 }
13844 }
13846 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13847 an integer constant or real constant.
13849 TYPE is the type of the result. */
13851 tree
13853 {
13857 {
13859 {
13860 /* If the value is unsigned or non-negative, then the absolute value
13861 is the same as the ordinary value. */
13865 /* If the value is negative, then the absolute value is
13866 its negation. */
13867 else
13868 {
13873 }
13874 }
13880 else
13886 }
13889 }
13891 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13892 constant. TYPE is the type of the result. */
13894 static tree
13896 {
13900 }
13902 /* Given CODE, a relational operator, the target type, TYPE and two
13903 constant operands OP0 and OP1, return the result of the
13904 relational operation. If the result is not a compile time
13905 constant, then return NULL_TREE. */
13907 static tree
13909 {
13912 /* From here on, the only cases we handle are when the result is
13913 known to be a constant. */
13916 {
13920 /* Handle the cases where either operand is a NaN. */
13922 {
13924 {
13952 }
13955 }
13958 }
13961 {
13965 }
13967 /* Handle equality/inequality of complex constants. */
13969 {
13980 else
13982 }
13985 {
13987 {
13988 /* Have vector comparison with scalar boolean result. */
13996 {
14004 }
14006 }
14007 tree_vector_builder elts;
14012 {
14025 }
14028 }
14030 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14032 To compute GT, swap the arguments and do LT.
14033 To compute GE, do LT and invert the result.
14034 To compute LE, swap the arguments, do LT and invert the result.
14035 To compute NE, do EQ and invert the result.
14037 Therefore, the code below must handle only EQ and LT. */
14040 {
14043 }
14045 /* Note that it is safe to invert for real values here because we
14046 have already handled the one case that it matters. */
14050 {
14053 }
14055 /* Compute a result for LT or EQ if args permit;
14056 Otherwise return T. */
14058 {
14061 else
14063 }
14064 else
14070 }
14072 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14073 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14074 itself. */
14076 tree
14078 {
14079 /* If the expression does not have side effects then we don't have to wrap
14080 it with a cleanup point expression. */
14084 /* If the expression is a return, check to see if the expression inside the
14085 return has no side effects or the right hand side of the modify expression
14086 inside the return. If either don't have side effects set we don't need to
14087 wrap the expression in a cleanup point expression. Note we don't check the
14088 left hand side of the modify because it should always be a return decl. */
14090 {
14097 }
14100 }
14102 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14103 of an indirection through OP0, or NULL_TREE if no simplification is
14104 possible. */
14106 tree
14108 {
14110 tree subtype;
14111 poly_uint64 const_op01;
14120 {
14124 /* *&CONST_DECL -> to the value of the const decl. */
14127 /* *&p => p; make sure to handle *&"str"[cst] here. */
14129 {
14133 else
14135 }
14136 /* *(foo *)&fooarray => fooarray[0] */
14139 && (!in_gimple_form
14141 {
14151 }
14152 /* *(foo *)&complexfoo => __real__ complexfoo */
14156 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14159 {
14163 index);
14164 }
14165 }
14169 {
14175 {
14176 tree op00type;
14180 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14183 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14184 but we want to treat offsets with MSB set as negative.
14185 For the code below negative offsets are invalid and
14186 TYPE_SIZE of the element is something unsigned, so
14187 check whether op01 fits into poly_int64, which implies
14188 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14189 then just use poly_uint64 because we want to treat the
14190 value as unsigned. */
14192 {
14194 poly_uint64 max_offset
14198 {
14203 }
14204 }
14205 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14208 {
14210 const_op01))
14212 }
14213 /* ((foo *)&fooarray)[1] => fooarray[1] */
14216 {
14223 offset_int remainder;
14226 {
14231 }
14232 }
14233 }
14234 }
14236 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14239 && (!in_gimple_form
14241 {
14242 tree type_domain;
14252 NULL_TREE);
14253 }
14256 }
14258 /* Builds an expression for an indirection through T, simplifying some
14259 cases. */
14261 tree
14263 {
14271 }
14273 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14275 tree
14277 {
14282 else
14284 }
14286 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14287 whose result is ignored. The type of the returned tree need not be
14288 the same as the original expression. */
14290 tree
14292 {
14298 {
14309 else
14315 {
14331 }
14336 }
14337 }
14339 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14341 tree
14343 {
14349 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14350 have to do anything. Only do this when we are not given a const,
14351 because in that case, this check is more expensive than just
14352 doing it. */
14354 {
14359 }
14361 /* If divisor is a power of two, simplify this to bit manipulation. */
14363 {
14365 {
14379 }
14380 else
14381 {
14382 tree t;
14388 }
14389 }
14390 else
14391 {
14396 }
14399 }
14401 /* Likewise, but round down. */
14403 tree
14405 {
14412 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14413 have to do anything. Only do this when we are not given a const,
14414 because in that case, this check is more expensive than just
14415 doing it. */
14417 {
14422 }
14424 /* If divisor is a power of two, simplify this to bit manipulation. */
14426 {
14427 tree t;
14431 }
14432 else
14433 {
14438 }
14441 }
14443 /* Returns the pointer to the base of the object addressed by EXP and
14444 extracts the information about the offset of the access, storing it
14445 to PBITPOS and POFFSET. */
14447 static tree
14450 {
14451 tree core;
14452 machine_mode mode;
14454 poly_int64 bitsize;
14458 {
14463 }
14465 {
14471 {
14472 poly_offset_int tem
14478 }
14479 }
14480 else
14481 {
14485 }
14488 }
14490 /* Returns true if addresses of E1 and E2 differ by a constant, false
14491 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14493 bool
14495 {
14510 {
14520 }
14522 {
14523 /* If only one of the offsets is non-constant, the difference cannot
14524 be a constant. */
14526 }
14527 else
14532 }
14534 /* Return OFF converted to a pointer offset type suitable as offset for
14535 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14536 tree
14538 {
14540 }
14542 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14543 tree
14545 {
14548 }
14550 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14551 tree
14553 {
14556 }
14558 /* Return a char pointer for a C string if it is a string constant
14559 or sum of string constant and integer constant. We only support
14560 string constants properly terminated with '\0' character.
14561 If STRLEN is a valid pointer, length (including terminating character)
14562 of returned string is stored to the argument. */
14566 {
14567 tree offset_node;
14578 {
14581 else
14583 }
14588 /* Support only properly null-terminated strings. */
14597 }
14599 #if CHECKING_P
14603 /* Helper functions for writing tests of folding trees. */
14605 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14607 static void
14609 tree constant)
14610 {
14612 }
14614 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14615 wrapping WRAPPED_EXPR. */
14617 static void
14619 tree wrapped_expr)
14620 {
14625 }
14627 /* Verify that various arithmetic binary operations are folded
14628 correctly. */
14630 static void
14632 {
14638 /* Addition. */
14639 /* 1 <-- (0 + 1) */
14641 one);
14643 one);
14645 /* (nonlvalue)x <-- (x + 0) */
14647 x);
14649 /* Subtraction. */
14650 /* 0 <-- (x - x) */
14652 zero);
14654 x);
14656 /* Multiplication. */
14657 /* 0 <-- (x * 0) */
14659 zero);
14661 /* (nonlvalue)x <-- (x * 1) */
14663 x);
14664 }
14666 /* Verify that various binary operations on vectors are folded
14667 correctly. */
14669 static void
14671 {
14677 /* Verify equality tests that return a scalar boolean result. */
14683 }
14685 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14687 static void
14689 {
14692 /* This will be 1 if VEC_MODE isn't a vector mode. */
14699 }
14701 /* Run all of the selftests within this file. */
14703 void
14705 {
14709 }