| blob | 571566aa6bca91e20153d7bfa4d6cfcd897cd97b |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2019 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
414 /* Steps don't prevent negation. */
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a (negative) power of two. */
464 /* Fall through. */
477 /* In general we can't negate A in A / B, because if A is INT_MIN and
478 B is not 1 we change the sign of the result. */
482 /* In general we can't negate B in A / B, because if A is INT_MIN and
483 B is 1, we may turn this into INT_MIN / -1 which is undefined
484 and actually traps on some architectures. */
493 /* Negate -((double)float) as (double)(-float). */
495 {
499 }
503 /* Negate -f(x) as f(-x). */
509 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
511 {
515 }
520 }
522 }
524 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
525 simplification is possible.
526 If negate_expr_p would return true for T, NULL_TREE will never be
527 returned. */
529 static tree
531 {
533 tree tem;
536 {
537 /* Convert - (~A) to A + 1. */
561 {
566 }
570 {
571 tree_vector_builder elts;
575 {
580 }
583 }
606 {
607 /* -(A + B) -> (-B) - A. */
609 {
613 }
615 /* -(A + B) -> (-A) - B. */
617 {
621 }
622 }
626 /* - (A - B) -> B - A */
637 /* Fall through. */
641 {
650 }
658 /* In general we can't negate A in A / B, because if A is INT_MIN and
659 B is not 1 we change the sign of the result. */
665 /* In general we can't negate B in A / B, because if A is INT_MIN and
666 B is 1, we may turn this into INT_MIN / -1 which is undefined
667 and actually traps on some architectures. */
679 /* Convert -((double)float) into (double)(-float). */
681 {
685 }
689 /* Negate -f(x) as f(-x). */
692 {
698 }
702 /* Optimize -((int)x >> 31) into (unsigned)x >> 31 for int. */
704 {
707 {
714 }
715 }
720 }
723 }
725 /* A wrapper for fold_negate_expr_1. */
727 static tree
729 {
736 }
738 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T cannot be
739 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
740 return NULL_TREE. */
742 static tree
744 {
746 location_t loc;
759 }
760 \f
761 /* Split a tree IN into a constant, literal and variable parts that could be
762 combined with CODE to make IN. "constant" means an expression with
763 TREE_CONSTANT but that isn't an actual constant. CODE must be a
764 commutative arithmetic operation. Store the constant part into *CONP,
765 the literal in *LITP and return the variable part. If a part isn't
766 present, set it to null. If the tree does not decompose in this way,
767 return the entire tree as the variable part and the other parts as null.
769 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
770 case, we negate an operand that was subtracted. Except if it is a
771 literal for which we use *MINUS_LITP instead.
773 If NEGATE_P is true, we are negating all of IN, again except a literal
774 for which we use *MINUS_LITP instead. If a variable part is of pointer
775 type, it is negated after converting to TYPE. This prevents us from
776 generating illegal MINUS pointer expression. LOC is the location of
777 the converted variable part.
779 If IN is itself a literal or constant, return it as appropriate.
781 Note that we do not guarantee that any of the three values will be the
782 same type as IN, but they will have the same signedness and mode. */
784 static tree
788 {
796 /* Strip any conversions that don't change the machine mode or signedness. */
805 /* We can associate addition and subtraction together (even
806 though the C standard doesn't say so) for integers because
807 the value is not affected. For reals, the value might be
808 affected, so we can't. */
814 {
820 /* First see if either of the operands is a literal, then a constant. */
833 /* If we haven't dealt with either operand, this is not a case we can
834 decompose. Otherwise, VAR is either of the ones remaining, if any. */
839 else
842 /* Now do any needed negations. */
849 }
854 {
855 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
856 when IN is constant. */
859 }
860 else
864 {
877 }
887 }
889 /* Re-associate trees split by the above function. T1 and T2 are
890 either expressions to associate or null. Return the new
891 expression, if any. LOC is the location of the new expression. If
892 we build an operation, do it in TYPE and with CODE. */
894 static tree
896 {
898 {
901 }
905 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
906 try to fold this since we will have infinite recursion. But do
907 deal with any NEGATE_EXPRs. */
911 {
913 {
926 }
928 {
931 }
935 }
939 }
940 \f
941 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
942 for use in int_const_binop, size_binop and size_diffop. */
944 static bool
946 {
953 {
962 }
967 }
969 /* Combine two wide ints ARG1 and ARG2 under operation CODE to produce
970 a new constant in RES. Return FALSE if we don't know how to
971 evaluate CODE at compile-time. */
973 bool
977 {
978 wide_int tmp;
981 {
997 {
1001 else
1003 }
1004 else
1008 /* It's unclear from the C standard whether shifts can overflow.
1009 The following code ignores overflow; perhaps a C standard
1010 interpretation ruling is needed. */
1012 else
1019 {
1023 else
1025 }
1026 else
1031 else
1110 }
1112 }
1114 /* Combine two poly int's ARG1 and ARG2 under operation CODE to
1115 produce a new constant in RES. Return FALSE if we don't know how
1116 to evaluate CODE at compile-time. */
1118 static bool
1122 {
1126 {
1144 else
1151 else
1164 }
1166 }
1168 /* Combine two integer constants ARG1 and ARG2 under operation CODE to
1169 produce a new constant. Return NULL_TREE if we don't know how to
1170 evaluate CODE at compile-time. */
1172 tree
1175 {
1177 poly_wide_int poly_res;
1183 {
1188 }
1197 }
1199 /* Return true if binary operation OP distributes over addition in operand
1200 OPNO, with the other operand being held constant. OPNO counts from 1. */
1202 static bool
1204 {
1206 {
1217 }
1218 }
1220 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1221 constant. We assume ARG1 and ARG2 have the same data type, or at least
1222 are the same kind of constant and the same machine mode. Return zero if
1223 combining the constants is not allowed in the current operating mode. */
1225 static tree
1227 {
1228 /* Sanity check for the recursive cases. */
1236 {
1242 }
1245 {
1246 machine_mode mode;
1247 REAL_VALUE_TYPE d1;
1248 REAL_VALUE_TYPE d2;
1249 REAL_VALUE_TYPE value;
1250 REAL_VALUE_TYPE result;
1254 /* The following codes are handled by real_arithmetic. */
1256 {
1267 }
1275 /* Don't perform operation if we honor signaling NaNs and
1276 either operand is a signaling NaN. */
1282 /* Don't perform operation if it would raise a division
1283 by zero exception. */
1289 /* If either operand is a NaN, just return it. Otherwise, set up
1290 for floating-point trap; we return an overflow. */
1292 {
1293 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1294 is off. */
1298 }
1300 {
1301 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1302 is off. */
1306 }
1311 /* Don't constant fold this floating point operation if
1312 the result has overflowed and flag_trapping_math. */
1320 /* Don't constant fold this floating point operation if the
1321 result may dependent upon the run-time rounding mode and
1322 flag_rounding_math is set, or if GCC's software emulation
1323 is unable to accurately represent the result. */
1333 }
1336 {
1337 FIXED_VALUE_TYPE f1;
1338 FIXED_VALUE_TYPE f2;
1339 FIXED_VALUE_TYPE result;
1344 /* The following codes are handled by fixed_arithmetic. */
1346 {
1358 {
1365 }
1370 }
1377 /* Propagate overflow flags. */
1381 }
1384 {
1393 {
1404 mpc_mul);
1418 mpc_div);
1419 /* Fallthru. */
1425 {
1426 /* Keep this algorithm in sync with
1427 tree-complex.c:expand_complex_div_straight().
1429 Expand complex division to scalars, straightforward algorithm.
1430 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1431 t = br*br + bi*bi
1432 */
1433 tree magsquared
1437 tree t1
1441 tree t2
1448 }
1449 else
1450 {
1451 /* Keep this algorithm in sync with
1452 tree-complex.c:expand_complex_div_wide().
1454 Expand complex division to scalars, modified algorithm to minimize
1455 overflow with wide input ranges. */
1461 {
1462 /* In the TRUE branch, we compute
1463 ratio = br/bi;
1464 div = (br * ratio) + bi;
1465 tr = (ar * ratio) + ai;
1466 ti = (ai * ratio) - ar;
1467 tr = tr / div;
1468 ti = ti / div; */
1479 }
1480 else
1481 {
1482 /* In the FALSE branch, we compute
1483 ratio = d/c;
1484 divisor = (d * ratio) + c;
1485 tr = (b * ratio) + a;
1486 ti = b - (a * ratio);
1487 tr = tr / div;
1488 ti = ti / div; */
1500 }
1501 }
1506 }
1510 }
1516 {
1521 /* We can operate directly on the encoding if:
1523 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1524 implies
1525 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1527 Addition and subtraction are the supported operators
1528 for which this is true. */
1531 /* We can operate directly on stepped encodings if:
1533 a3 - a2 == a2 - a1
1534 implies:
1535 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1537 which is true if (x -> x op c) distributes over addition. */
1539 else
1540 /* Similarly in reverse. */
1542 tree_vector_builder elts;
1547 {
1553 /* It is possible that const_binop cannot handle the given
1554 code and return NULL_TREE */
1558 }
1561 }
1563 /* Shifts allow a scalar offset for a vector. */
1566 {
1569 tree_vector_builder elts;
1574 {
1579 /* It is possible that const_binop cannot handle the given
1580 code and return NULL_TREE. */
1584 }
1587 }
1589 }
1591 /* Overload that adds a TYPE parameter to be able to dispatch
1592 to fold_relational_const. */
1594 tree
1596 {
1600 /* ??? Until we make the const_binop worker take the type of the
1601 result as argument put those cases that need it here. */
1603 {
1620 {
1625 }
1631 {
1647 {
1652 ? NOP_EXPR
1659 }
1662 }
1668 {
1691 {
1704 }
1707 }
1710 }
1715 /* Make sure type and arg0 have the same saturating flag. */
1720 }
1722 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1723 Return zero if computing the constants is not possible. */
1725 tree
1727 {
1728 /* Don't perform the operation, other than NEGATE and ABS, if
1729 flag_signaling_nans is on and the operand is a signaling NaN. */
1739 {
1740 CASE_CONVERT:
1747 /* If the source address is 0, and the source address space
1748 cannot have a valid object at 0, fold to dest type null. */
1759 {
1760 /* Can't call fold_negate_const directly here as that doesn't
1761 handle all cases and we might not be able to negate some
1762 constants. */
1767 }
1777 {
1781 }
1789 /* Perform BIT_NOT_EXPR on each element individually. */
1791 {
1792 tree elem;
1794 /* This can cope with stepped encodings because ~x == -1 - x. */
1795 tree_vector_builder elements;
1799 {
1805 }
1808 }
1832 {
1855 else
1860 {
1866 }
1869 }
1878 }
1881 }
1883 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1884 indicates which particular sizetype to create. */
1886 tree
1888 {
1890 }
1891 \f
1892 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1893 is a tree code. The type of the result is taken from the operands.
1894 Both must be equivalent integer types, ala int_binop_types_match_p.
1895 If the operands are constant, so is the result. */
1897 tree
1899 {
1908 /* Handle the special case of two poly_int constants faster. */
1910 {
1911 /* And some specific cases even faster than that. */
1913 {
1920 }
1922 {
1926 }
1928 {
1932 }
1934 /* Handle general case of two integer constants. For sizetype
1935 constant calculations we always want to know about overflow,
1936 even in the unsigned case. */
1940 }
1943 }
1945 /* Given two values, either both of sizetype or both of bitsizetype,
1946 compute the difference between the two values. Return the value
1947 in signed type corresponding to the type of the operands. */
1949 tree
1951 {
1953 tree ctype;
1958 /* If the type is already signed, just do the simple thing. */
1966 else
1969 /* If either operand is not a constant, do the conversions to the signed
1970 type and subtract. The hardware will do the right thing with any
1971 overflow in the subtraction. */
1977 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1978 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1979 overflow) and negate (which can't either). Special-case a result
1980 of zero while we're here. */
1986 else
1990 MINUS_EXPR,
1992 }
1993 \f
1994 /* A subroutine of fold_convert_const handling conversions of an
1995 INTEGER_CST to another integer type. */
1997 static tree
1999 {
2000 /* Given an integer constant, make new constant with new type,
2001 appropriately sign-extended or truncated. Use widest_int
2002 so that any extension is done according ARG1's type. */
2006 }
2008 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2009 to an integer type. */
2011 static tree
2013 {
2015 tree t;
2017 /* The following code implements the floating point to integer
2018 conversion rules required by the Java Language Specification,
2019 that IEEE NaNs are mapped to zero and values that overflow
2020 the target precision saturate, i.e. values greater than
2021 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2022 are mapped to INT_MIN. These semantics are allowed by the
2023 C and C++ standards that simply state that the behavior of
2024 FP-to-integer conversion is unspecified upon overflow. */
2026 wide_int val;
2027 REAL_VALUE_TYPE r;
2031 {
2038 }
2040 /* If R is NaN, return zero and show we have an overflow. */
2042 {
2045 }
2047 /* See if R is less than the lower bound or greater than the
2048 upper bound. */
2051 {
2055 {
2058 }
2059 }
2062 {
2065 {
2068 {
2071 }
2072 }
2073 }
2080 }
2082 /* A subroutine of fold_convert_const handling conversions of a
2083 FIXED_CST to an integer type. */
2085 static tree
2087 {
2088 tree t;
2090 scalar_mode mode;
2092 /* Right shift FIXED_CST to temp by fbit. */
2096 {
2098 HOST_BITS_PER_DOUBLE_INT,
2101 /* Left shift temp to temp_trunc by fbit. */
2103 HOST_BITS_PER_DOUBLE_INT,
2105 }
2106 else
2107 {
2110 }
2112 /* If FIXED_CST is negative, we need to round the value toward 0.
2113 By checking if the fractional bits are not zero to add 1 to temp. */
2119 /* Given a fixed-point constant, make new constant with new type,
2120 appropriately sign-extended or truncated. */
2128 }
2130 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2131 to another floating point type. */
2133 static tree
2135 {
2136 REAL_VALUE_TYPE value;
2137 tree t;
2139 /* Don't perform the operation if flag_signaling_nans is on
2140 and the operand is a signaling NaN. */
2148 /* If converting an infinity or NAN to a representation that doesn't
2149 have one, set the overflow bit so that we can produce some kind of
2150 error message at the appropriate point if necessary. It's not the
2151 most user-friendly message, but it's better than nothing. */
2158 /* Regular overflow, conversion produced an infinity in a mode that
2159 can't represent them. */
2164 else
2167 }
2169 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2170 to a floating point type. */
2172 static tree
2174 {
2175 REAL_VALUE_TYPE value;
2176 tree t;
2184 }
2186 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2187 to another fixed-point type. */
2189 static tree
2191 {
2192 FIXED_VALUE_TYPE value;
2193 tree t;
2200 /* Propagate overflow flags. */
2204 }
2206 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2207 to a fixed-point type. */
2209 static tree
2211 {
2212 FIXED_VALUE_TYPE value;
2213 tree t;
2215 double_int di;
2222 else
2230 /* Propagate overflow flags. */
2234 }
2236 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2237 to a fixed-point type. */
2239 static tree
2241 {
2242 FIXED_VALUE_TYPE value;
2243 tree t;
2251 /* Propagate overflow flags. */
2255 }
2257 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2258 type TYPE. If no simplification can be done return NULL_TREE. */
2260 static tree
2262 {
2267 /* We can't widen types, since the runtime value could overflow the
2268 original type before being extended to the new type. */
2279 {
2286 }
2288 {
2295 }
2297 {
2304 }
2306 {
2309 {
2312 /* We can't handle steps directly when extending, since the
2313 values need to wrap at the original precision first. */
2314 bool step_ok_p
2318 tree_vector_builder v;
2323 {
2329 }
2331 }
2332 }
2334 }
2336 /* Construct a vector of zero elements of vector type TYPE. */
2338 static tree
2340 {
2341 tree t;
2345 }
2347 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2349 bool
2351 {
2366 {
2383 }
2384 }
2386 /* Convert expression ARG to type TYPE. Used by the middle-end for
2387 simple conversions in preference to calling the front-end's convert. */
2389 tree
2391 {
2393 tree tem;
2404 {
2407 /* Handle conversions between pointers to different address spaces. */
2412 /* fall through */
2417 {
2421 }
2435 {
2439 }
2441 {
2445 }
2447 {
2451 }
2454 {
2472 }
2477 {
2481 }
2484 {
2498 }
2502 {
2511 integer_zero_node));
2513 {
2517 {
2523 }
2531 }
2535 }
2553 }
2554 fold_convert_exit:
2557 }
2558 \f
2559 /* Return false if expr can be assumed not to be an lvalue, true
2560 otherwise. */
2562 static bool
2564 {
2565 /* We only need to wrap lvalue tree codes. */
2567 {
2598 /* Assume the worst for front-end tree codes. */
2602 }
2605 }
2607 /* Return an expr equal to X but certainly not valid as an lvalue. */
2609 tree
2611 {
2612 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2613 us. */
2620 }
2622 /* When pedantic, return an expr equal to X but certainly not valid as a
2623 pedantic lvalue. Otherwise, return X. */
2625 static tree
2627 {
2629 }
2630 \f
2631 /* Given a tree comparison code, return the code that is the logical inverse.
2632 It is generally not safe to do this for floating-point comparisons, except
2633 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2634 ERROR_MARK in this case. */
2636 enum tree_code
2638 {
2644 {
2675 }
2676 }
2678 /* Similar, but return the comparison that results if the operands are
2679 swapped. This is safe for floating-point. */
2681 enum tree_code
2683 {
2685 {
2711 }
2712 }
2715 /* Convert a comparison tree code from an enum tree_code representation
2716 into a compcode bit-based encoding. This function is the inverse of
2717 compcode_to_comparison. */
2719 static enum comparison_code
2721 {
2723 {
2754 }
2755 }
2757 /* Convert a compcode bit-based encoding of a comparison operator back
2758 to GCC's enum tree_code representation. This function is the
2759 inverse of comparison_to_compcode. */
2761 static enum tree_code
2763 {
2765 {
2796 }
2797 }
2799 /* Return true if COND1 tests the opposite condition of COND2. */
2801 bool
2803 {
2806 && (invert_tree_comparison
2813 }
2815 /* Return a tree for the comparison which is the combination of
2816 doing the AND or OR (depending on CODE) of the two operations LCODE
2817 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2818 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2819 if this makes the transformation invalid. */
2821 tree
2826 {
2833 {
2844 }
2847 {
2848 /* Eliminate unordered comparisons, as well as LTGT and ORD
2849 which are not used unless the mode has NaNs. */
2855 }
2857 {
2858 /* Check that the original operation and the optimized ones will trap
2859 under the same condition. */
2870 /* In a short-circuited boolean expression the LHS might be
2871 such that the RHS, if evaluated, will never trap. For
2872 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2873 if neither x nor y is NaN. (This is a mixed blessing: for
2874 example, the expression above will never trap, hence
2875 optimizing it to x < y would be invalid). */
2880 /* If the comparison was short-circuited, and only the RHS
2881 trapped, we may now generate a spurious trap. */
2886 /* If we changed the conditions that cause a trap, we lose. */
2889 }
2895 else
2896 {
2901 }
2902 }
2903 \f
2904 /* Return nonzero if two operands (typically of the same tree node)
2905 are necessarily equal. FLAGS modifies behavior as follows:
2907 If OEP_ONLY_CONST is set, only return nonzero for constants.
2908 This function tests whether the operands are indistinguishable;
2909 it does not test whether they are equal using C's == operation.
2910 The distinction is important for IEEE floating point, because
2911 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2912 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2914 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2915 even though it may hold multiple values during a function.
2916 This is because a GCC tree node guarantees that nothing else is
2917 executed between the evaluation of its "operands" (which may often
2918 be evaluated in arbitrary order). Hence if the operands themselves
2919 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2920 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2921 unset means assuming isochronic (or instantaneous) tree equivalence.
2922 Unless comparing arbitrary expression trees, such as from different
2923 statements, this flag can usually be left unset.
2925 If OEP_PURE_SAME is set, then pure functions with identical arguments
2926 are considered the same. It is used when the caller has other ways
2927 to ensure that global memory is unchanged in between.
2929 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2930 not values of expressions.
2932 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2933 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2935 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2936 any operand with side effect. This is unnecesarily conservative in the
2937 case we know that arg0 and arg1 are in disjoint code paths (such as in
2938 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2939 addresses with TREE_CONSTANT flag set so we know that &var == &var
2940 even if var is volatile. */
2942 int
2944 {
2948 /* When checking, verify at the outermost operand_equal_p call that
2949 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2950 hash value. */
2952 {
2954 {
2956 {
2963 }
2965 }
2966 else
2968 }
2970 /* If either is ERROR_MARK, they aren't equal. */
2976 /* Similar, if either does not have a type (like a released SSA name),
2977 they aren't equal. */
2981 /* We cannot consider pointers to different address space equal. */
2988 /* Check equality of integer constants before bailing out due to
2989 precision differences. */
2991 {
2992 /* Address of INTEGER_CST is not defined; check that we did not forget
2993 to drop the OEP_ADDRESS_OF flags. */
2996 }
2999 {
3000 /* If both types don't have the same signedness, then we can't consider
3001 them equal. We must check this before the STRIP_NOPS calls
3002 because they may change the signedness of the arguments. As pointers
3003 strictly don't have a signedness, require either two pointers or
3004 two non-pointers as well. */
3010 /* If both types don't have the same precision, then it is not safe
3011 to strip NOPs. */
3018 }
3019 #if 0
3020 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
3021 sanity check once the issue is solved. */
3022 else
3023 /* Addresses of conversions and SSA_NAMEs (and many other things)
3024 are not defined. Check that we did not forget to drop the
3025 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3028 #endif
3030 /* In case both args are comparisons but with different comparison
3031 code, try to swap the comparison operands of one arg to produce
3032 a match and compare that variant. */
3036 {
3044 }
3047 {
3048 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3050 ;
3052 {
3053 /* If we are interested in comparing addresses ignore
3054 MEM_REF wrappings of the base that can appear just for
3055 TBAA reasons. */
3069 }
3070 else
3072 }
3074 /* When not checking adddresses, this is needed for conversions and for
3075 COMPONENT_REF. Might as well play it safe and always test this. */
3082 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3083 We don't care about side effects in that case because the SAVE_EXPR
3084 takes care of that for us. In all other cases, two expressions are
3085 equal if they have no side effects. If we have two identical
3086 expressions with side effects that should be treated the same due
3087 to the only side effects being identical SAVE_EXPR's, that will
3088 be detected in the recursive calls below.
3089 If we are taking an invariant address of two identical objects
3090 they are necessarily equal as well. */
3097 /* Next handle constant cases, those for which we can return 1 even
3098 if ONLY_CONST is set. */
3101 {
3115 {
3116 /* If we do not distinguish between signed and unsigned zero,
3117 consider them equal. */
3120 }
3124 {
3139 }
3143 flags)
3145 flags));
3156 flags | OEP_ADDRESS_OF
3159 /* In GIMPLE empty constructors are allowed in initializers of
3160 aggregates. */
3164 }
3169 /* Define macros to test an operand from arg0 and arg1 for equality and a
3170 variant that allows null and views null as being different from any
3171 non-null value. In the latter case, if either is null, the both
3172 must be; otherwise, do the normal comparison. */
3173 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3174 TREE_OPERAND (arg1, N), flags)
3176 #define OP_SAME_WITH_NULL(N) \
3177 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3178 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3181 {
3183 /* Two conversions are equal only if signedness and modes match. */
3185 {
3186 CASE_CONVERT:
3194 }
3204 /* For commutative ops, allow the other order. */
3212 /* If either of the pointer (or reference) expressions we are
3213 dereferencing contain a side effect, these cannot be equal,
3214 but their addresses can be. */
3221 {
3231 /* Require the same offset. */
3237 /* Fallthru. */
3245 {
3246 /* Require equal access sizes */
3252 flags)))
3254 /* Verify that access happens in similar types. */
3257 /* Verify that accesses are TBAA compatible. */
3266 /* Verify that alignment is compatible. */
3270 }
3273 /* TARGET_MEM_REF require equal extra operands. */
3284 /* Compare the array index by value if it is constant first as we
3285 may have different types but same value here. */
3291 /* Compare low bound and element size as with OEP_ADDRESS_OF
3292 we have to account for the offset of the ref. */
3297 array_ref_low_bound
3301 array_ref_element_size
3303 flags))));
3306 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3307 may be NULL when we're called to compare MEM_EXPRs. */
3322 }
3326 {
3328 /* Be sure we pass right ADDRESS_OF flag. */
3345 /* The multiplcation operands are commutative. */
3346 /* FALLTHRU */
3354 /* Otherwise take into account this is a commutative operation. */
3367 /* BIT_INSERT_EXPR has an implict operand as the type precision
3368 of op1. Need to check to make sure they are the same. */
3374 /* FALLTHRU */
3400 }
3404 {
3408 /* If not both CALL_EXPRs are either internal or normal function
3409 functions, then they are not equal. */
3412 {
3413 /* If the CALL_EXPRs call different internal functions, then they
3414 are not equal. */
3417 }
3418 else
3419 {
3420 /* If the CALL_EXPRs call different functions, then they are not
3421 equal. */
3423 flags))
3425 }
3427 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3428 {
3432 else
3436 }
3438 /* Now see if all the arguments are the same. */
3439 {
3450 /* If we get here and both argument lists are exhausted
3451 then the CALL_EXPRs are equal. */
3453 }
3456 }
3459 /* Consider __builtin_sqrt equal to sqrt. */
3467 {
3468 /* In GIMPLE constructors are used only to build vectors from
3469 elements. Individual elements in the constructor must be
3470 indexed in increasing order and form an initial sequence.
3472 We make no effort to compare constructors in generic.
3473 (see sem_variable::equals in ipa-icf which can do so for
3474 constants). */
3479 /* Be sure that vectors constructed have the same representation.
3480 We only tested element precision and modes to match.
3481 Vectors may be BLKmode and thus also check that the number of
3482 parts match. */
3495 {
3500 /* In GIMPLE the indexes can be either NULL or matching i.
3501 Double check this so we won't get false
3502 positives for GENERIC. */
3510 }
3512 }
3515 {
3516 /* Compare the STATEMENT_LISTs. */
3522 {
3523 /* The lists don't have the same number of statements. */
3529 flags & (OEP_LEXICOGRAPHIC
3532 }
3533 }
3538 {
3549 }
3553 }
3555 #undef OP_SAME
3556 #undef OP_SAME_WITH_NULL
3557 }
3558 \f
3559 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3560 with a different signedness or a narrower precision. */
3562 static bool
3564 {
3572 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3573 and see if the inner values are the same. This removes any
3574 signedness comparison, which doesn't matter here. */
3582 /* Discard a single widening conversion from ARG1 and see if the inner
3583 value is the same as ARG0. */
3592 }
3593 \f
3594 /* See if ARG is an expression that is either a comparison or is performing
3595 arithmetic on comparisons. The comparisons must only be comparing
3596 two different values, which will be stored in *CVAL1 and *CVAL2; if
3597 they are nonzero it means that some operands have already been found.
3598 No variables may be used anywhere else in the expression except in the
3599 comparisons.
3601 If this is true, return 1. Otherwise, return zero. */
3603 static int
3605 {
3609 /* We can handle some of the tcc_expression cases here. */
3618 {
3637 /* First see if we can handle the first operand, then the second. For
3638 the second operand, we know *CVAL1 can't be zero. It must be that
3639 one side of the comparison is each of the values; test for the
3640 case where this isn't true by failing if the two operands
3641 are the same. */
3650 ;
3654 ;
3655 else
3659 ;
3663 ;
3664 else
3671 }
3672 }
3673 \f
3674 /* ARG is a tree that is known to contain just arithmetic operations and
3675 comparisons. Evaluate the operations in the tree substituting NEW0 for
3676 any occurrence of OLD0 as an operand of a comparison and likewise for
3677 NEW1 and OLD1. */
3679 static tree
3682 {
3687 /* We can handle some of the tcc_expression cases here. */
3695 {
3710 {
3729 }
3730 /* Fall through - ??? */
3733 {
3737 /* We need to check both for exact equality and tree equality. The
3738 former will be true if the operand has a side-effect. In that
3739 case, we know the operand occurred exactly once. */
3752 }
3756 }
3757 }
3758 \f
3759 /* Return a tree for the case when the result of an expression is RESULT
3760 converted to TYPE and OMITTED was previously an operand of the expression
3761 but is now not needed (e.g., we folded OMITTED * 0).
3763 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3764 the conversion of RESULT to TYPE. */
3766 tree
3768 {
3771 /* If the resulting operand is an empty statement, just return the omitted
3772 statement casted to void. */
3782 }
3784 /* Return a tree for the case when the result of an expression is RESULT
3785 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3786 of the expression but are now not needed.
3788 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3789 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3790 evaluated before OMITTED2. Otherwise, if neither has side effects,
3791 just do the conversion of RESULT to TYPE. */
3793 tree
3796 {
3805 }
3807 \f
3808 /* Return a simplified tree node for the truth-negation of ARG. This
3809 never alters ARG itself. We assume that ARG is an operation that
3810 returns a truth value (0 or 1).
3812 FIXME: one would think we would fold the result, but it causes
3813 problems with the dominator optimizer. */
3815 static tree
3817 {
3822 /* If this is a comparison, we can simply invert it, except for
3823 floating-point non-equality comparisons, in which case we just
3824 enclose a TRUTH_NOT_EXPR around what we have. */
3827 {
3830 && flag_trapping_math
3844 }
3847 {
3866 /* Here we can invert either operand. We invert the first operand
3867 unless the second operand is a TRUTH_NOT_EXPR in which case our
3868 result is the XOR of the first operand with the inside of the
3869 negation of the second operand. */
3874 else
3897 {
3904 /* A COND_EXPR may have a throw as one operand, which
3905 then has void type. Just leave void operands
3906 as they are. */
3912 }
3924 CASE_CONVERT:
3928 /* fall through */
3950 }
3951 }
3953 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3954 assume that ARG is an operation that returns a truth value (0 or 1
3955 for scalars, 0 or -1 for vectors). Return the folded expression if
3956 folding is successful. Otherwise, return NULL_TREE. */
3958 static tree
3960 {
3963 ? BIT_NOT_EXPR
3966 }
3968 /* Return a simplified tree node for the truth-negation of ARG. This
3969 never alters ARG itself. We assume that ARG is an operation that
3970 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3972 tree
3974 {
3980 ? BIT_NOT_EXPR
3983 }
3984 \f
3985 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3986 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3987 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3988 is the original memory reference used to preserve the alias set of
3989 the access. */
3991 static tree
3995 {
3998 /* Attempt not to lose the access path if possible. */
4000 {
4002 machine_mode nmode;
4004 tree noffset;
4012 && !reversep
4013 && !nreversep
4015 {
4018 }
4019 }
4028 {
4035 }
4050 }
4052 /* Optimize a bit-field compare.
4054 There are two cases: First is a compare against a constant and the
4055 second is a comparison of two items where the fields are at the same
4056 bit position relative to the start of a chunk (byte, halfword, word)
4057 large enough to contain it. In these cases we can avoid the shift
4058 implicit in bitfield extractions.
4060 For constants, we emit a compare of the shifted constant with the
4061 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4062 compared. For two fields at the same position, we do the ANDs with the
4063 similar mask and compare the result of the ANDs.
4065 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4066 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4067 are the left and right operands of the comparison, respectively.
4069 If the optimization described above can be done, we return the resulting
4070 tree. Otherwise we return zero. */
4072 static tree
4075 {
4079 tree unsigned_type;
4082 scalar_int_mode nmode;
4087 tree mask;
4088 tree offset;
4090 /* Get all the information about the extractions being done. If the bit size
4091 is the same as the size of the underlying object, we aren't doing an
4092 extraction at all and so can do nothing. We also don't want to
4093 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4094 then will no longer be able to replace it. */
4109 else
4110 {
4111 /* If this is not a constant, we can only do something if bit positions,
4112 sizes, signedness and storage order are the same. */
4113 rinner
4126 }
4128 /* Honor the C++ memory model and mimic what RTL expansion does. */
4132 {
4136 }
4138 /* See if we can find a mode to refer to this field. We should be able to,
4139 but fail if we can't. */
4147 /* Set signed and unsigned types of the precision of this mode for the
4148 shifts below. */
4151 /* Compute the bit position and size for the new reference and our offset
4152 within it. If the new reference is the same size as the original, we
4153 won't optimize anything, so return zero. */
4163 /* Make the mask to be used against the extracted field. */
4170 {
4174 /* If not comparing with constant, just rework the comparison
4175 and return. */
4183 }
4185 /* Otherwise, we are handling the constant case. See if the constant is too
4186 big for the field. Warn and return a tree for 0 (false) if so. We do
4187 this not only for its own sake, but to avoid having to test for this
4188 error case below. If we didn't, we might generate wrong code.
4190 For unsigned fields, the constant shifted right by the field length should
4191 be all zero. For signed fields, the high-order bits should agree with
4192 the sign bit. */
4195 {
4197 {
4201 }
4202 }
4203 else
4204 {
4207 {
4211 }
4212 }
4217 /* Single-bit compares should always be against zero. */
4219 {
4222 }
4224 /* Make a new bitfield reference, shift the constant over the
4225 appropriate number of bits and mask it with the computed mask
4226 (in case this was a signed field). If we changed it, make a new one. */
4234 mask);
4239 }
4240 \f
4241 /* Subroutine for fold_truth_andor_1: decode a field reference.
4243 If EXP is a comparison reference, we return the innermost reference.
4245 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4246 set to the starting bit number.
4248 If the innermost field can be completely contained in a mode-sized
4249 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4251 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4252 otherwise it is not changed.
4254 *PUNSIGNEDP is set to the signedness of the field.
4256 *PREVERSEP is set to the storage order of the field.
4258 *PMASK is set to the mask used. This is either contained in a
4259 BIT_AND_EXPR or derived from the width of the field.
4261 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4263 Return 0 if this is not a component reference or is one that we can't
4264 do anything with. */
4266 static tree
4271 {
4276 tree unsigned_type;
4279 /* All the optimizations using this function assume integer fields.
4280 There are problems with FP fields since the type_for_size call
4281 below can fail for, e.g., XFmode. */
4285 /* We are interested in the bare arrangement of bits, so strip everything
4286 that doesn't affect the machine mode. However, record the type of the
4287 outermost expression if it may matter below. */
4294 {
4300 }
4311 /* Reject out-of-bound accesses (PR79731). */
4323 /* If the number of bits in the reference is the same as the bitsize of
4324 the outer type, then the outer type gives the signedness. Otherwise
4325 (in case of a small bitfield) the signedness is unchanged. */
4329 /* Compute the mask to access the bitfield. */
4337 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4345 }
4347 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4348 bit positions and MASK is SIGNED. */
4350 static int
4352 {
4356 /* If this function returns true when the type of the mask is
4357 UNSIGNED, then there will be errors. In particular see
4358 gcc.c-torture/execute/990326-1.c. There does not appear to be
4359 any documentation paper trail as to why this is so. But the pre
4360 wide-int worked with that restriction and it has been preserved
4361 here. */
4366 }
4368 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4369 represents the sign bit of EXP's type. If EXP represents a sign
4370 or zero extension, also test VAL against the unextended type.
4371 The return value is the (sub)expression whose sign bit is VAL,
4372 or NULL_TREE otherwise. */
4374 tree
4376 {
4378 tree t;
4380 /* Tree EXP must have an integral type. */
4385 /* Tree VAL must be an integer constant. */
4394 /* Handle extension from a narrower type. */
4400 }
4402 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4403 to be evaluated unconditionally. */
4405 static int
4407 {
4408 /* Strip any conversions that don't change the machine mode. */
4417 /* Don't regard global variables as simple. They may be
4418 allocated in ways unknown to the compiler (shared memory,
4419 #pragma weak, etc). */
4422 /* Weakrefs are not safe to be read, since they can be NULL.
4423 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4424 have DECL_WEAK flag set. */
4426 /* Loading a static variable is unduly expensive, but global
4427 registers aren't expensive. */
4429 }
4431 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4432 to be evaluated unconditionally.
4433 I addition to simple_operand_p, we assume that comparisons, conversions,
4434 and logic-not operations are simple, if their operands are simple, too. */
4436 static bool
4438 {
4458 }
4460 \f
4461 /* The following functions are subroutines to fold_range_test and allow it to
4462 try to change a logical combination of comparisons into a range test.
4464 For example, both
4465 X == 2 || X == 3 || X == 4 || X == 5
4466 and
4467 X >= 2 && X <= 5
4468 are converted to
4469 (unsigned) (X - 2) <= 3
4471 We describe each set of comparisons as being either inside or outside
4472 a range, using a variable named like IN_P, and then describe the
4473 range with a lower and upper bound. If one of the bounds is omitted,
4474 it represents either the highest or lowest value of the type.
4476 In the comments below, we represent a range by two numbers in brackets
4477 preceded by a "+" to designate being inside that range, or a "-" to
4478 designate being outside that range, so the condition can be inverted by
4479 flipping the prefix. An omitted bound is represented by a "-". For
4480 example, "- [-, 10]" means being outside the range starting at the lowest
4481 possible value and ending at 10, in other words, being greater than 10.
4482 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4483 always false.
4485 We set up things so that the missing bounds are handled in a consistent
4486 manner so neither a missing bound nor "true" and "false" need to be
4487 handled using a special case. */
4489 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4490 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4491 and UPPER1_P are nonzero if the respective argument is an upper bound
4492 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4493 must be specified for a comparison. ARG1 will be converted to ARG0's
4494 type if both are specified. */
4496 static tree
4499 {
4500 tree tem;
4504 /* If neither arg represents infinity, do the normal operation.
4505 Else, if not a comparison, return infinity. Else handle the special
4506 comparison rules. Note that most of the cases below won't occur, but
4507 are handled for consistency. */
4510 {
4515 }
4520 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4521 for neither. In real maths, we cannot assume open ended ranges are
4522 the same. But, this is computer arithmetic, where numbers are finite.
4523 We can therefore make the transformation of any unbounded range with
4524 the value Z, Z being greater than any representable number. This permits
4525 us to treat unbounded ranges as equal. */
4529 {
4550 }
4553 }
4554 \f
4555 /* Helper routine for make_range. Perform one step for it, return
4556 new expression if the loop should continue or NULL_TREE if it should
4557 stop. */
4559 tree
4563 {
4569 {
4571 /* We can only do something if the range is testing for zero. */
4580 /* We can only do something if the range is testing for zero
4581 and if the second operand is an integer constant. Note that
4582 saying something is "in" the range we make is done by
4583 complementing IN_P since it will set in the initial case of
4584 being not equal to zero; "out" is leaving it alone. */
4591 {
4612 }
4614 /* If this is an unsigned comparison, we also know that EXP is
4615 greater than or equal to zero. We base the range tests we make
4616 on that fact, so we record it here so we can parse existing
4617 range tests. We test arg0_type since often the return type
4618 of, e.g. EQ_EXPR, is boolean. */
4620 {
4624 NULL_TREE))
4629 /* If the high bound is missing, but we have a nonzero low
4630 bound, reverse the range so it goes from zero to the low bound
4631 minus 1. */
4633 {
4638 }
4639 }
4647 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4648 low and high are non-NULL, then normalize will DTRT. */
4651 {
4656 }
4658 /* (-x) IN [a,b] -> x in [-b, -a] */
4670 /* ~ X -> -X - 1 */
4679 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4680 move a constant to the other side. */
4685 /* If EXP is signed, any overflow in the computation is undefined,
4686 so we don't worry about it so long as our computations on
4687 the bounds don't overflow. For unsigned, overflow is defined
4688 and this is exactly the right thing. */
4700 normalize:
4701 /* Check for an unsigned range which has wrapped around the maximum
4702 value thus making n_high < n_low, and normalize it. */
4704 {
4710 /* If the range is of the form +/- [ x+1, x ], we won't
4711 be able to normalize it. But then, it represents the
4712 whole range or the empty set, so make it
4713 +/- [ -, - ]. */
4717 else
4719 }
4720 else
4728 CASE_CONVERT:
4746 /* If we're converting arg0 from an unsigned type, to exp,
4747 a signed type, we will be doing the comparison as unsigned.
4748 The tests above have already verified that LOW and HIGH
4749 are both positive.
4751 So we have to ensure that we will handle large unsigned
4752 values the same way that the current signed bounds treat
4753 negative values. */
4756 {
4757 tree high_positive;
4758 tree equiv_type;
4759 /* For fixed-point modes, we need to pass the saturating flag
4760 as the 2nd parameter. */
4762 equiv_type
4765 else
4766 equiv_type
4769 /* A range without an upper bound is, naturally, unbounded.
4770 Since convert would have cropped a very large value, use
4771 the max value for the destination type. */
4772 high_positive
4779 high_positive),
4782 /* If the low bound is specified, "and" the range with the
4783 range for which the original unsigned value will be
4784 positive. */
4786 {
4789 integer_zero_node),
4790 high_positive))
4794 }
4795 else
4796 {
4797 /* Otherwise, "or" the range with the range of the input
4798 that will be interpreted as negative. */
4801 integer_zero_node),
4802 high_positive))
4806 }
4807 }
4816 }
4817 }
4819 /* Given EXP, a logical expression, set the range it is testing into
4820 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4821 actually being tested. *PLOW and *PHIGH will be made of the same
4822 type as the returned expression. If EXP is not a comparison, we
4823 will most likely not be returning a useful value and range. Set
4824 *STRICT_OVERFLOW_P to true if the return value is only valid
4825 because signed overflow is undefined; otherwise, do not change
4826 *STRICT_OVERFLOW_P. */
4828 tree
4831 {
4839 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4840 and see if we can refine the range. Some of the cases below may not
4841 happen, but it doesn't seem worth worrying about this. We "continue"
4842 the outer loop when we've changed something; otherwise we "break"
4843 the switch, which will "break" the while. */
4849 {
4855 {
4863 }
4872 }
4874 /* If EXP is a constant, we can evaluate whether this is true or false. */
4876 {
4883 }
4887 }
4889 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4890 a bitwise check i.e. when
4891 LOW == 0xXX...X00...0
4892 HIGH == 0xXX...X11...1
4893 Return corresponding mask in MASK and stem in VALUE. */
4895 static bool
4898 {
4921 }
4922 \f
4923 /* Helper routine for build_range_check and match.pd. Return the type to
4924 perform the check or NULL if it shouldn't be optimized. */
4926 tree
4928 {
4929 /* First make sure that arithmetics in this type is valid, then make sure
4930 that it wraps around. */
4936 {
4939 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4940 for the type in question, as we rely on this here. */
4950 else
4952 }
4954 }
4956 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4957 type, TYPE, return an expression to test if EXP is in (or out of, depending
4958 on IN_P) the range. Return 0 if the test couldn't be created. */
4960 tree
4963 {
4966 /* Disable this optimization for function pointer expressions
4967 on targets that require function pointer canonicalization. */
4974 {
4980 }
5002 value);
5005 {
5007 {
5011 }
5013 }
5015 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5017 {
5021 {
5023 {
5026 etype
5028 else
5031 }
5034 }
5035 }
5037 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5038 This requires wrap-around arithmetics for the type of the expression. */
5058 }
5059 \f
5060 /* Return the predecessor of VAL in its type, handling the infinite case. */
5062 static tree
5064 {
5070 else
5073 }
5075 /* Return the successor of VAL in its type, handling the infinite case. */
5077 static tree
5079 {
5085 else
5088 }
5090 /* Given two ranges, see if we can merge them into one. Return 1 if we
5091 can, 0 if we can't. Set the output range into the specified parameters. */
5093 bool
5096 {
5100 tree tem;
5110 /* Make range 0 be the range that starts first, or ends last if they
5111 start at the same value. Swap them if it isn't. */
5114 || (lowequal
5117 {
5121 }
5123 /* If the second range is != high1 where high1 is the type maximum of
5124 the type, try first merging with < high1 range. */
5126 && high1
5133 {
5138 /* Similarly for the second range != low1 where low1 is the type minimum
5139 of the type, try first merging with > low1 range. */
5144 }
5146 /* Now flag two cases, whether the ranges are disjoint or whether the
5147 second range is totally subsumed in the first. Note that the tests
5148 below are simplified by the ones above. */
5154 /* We now have four cases, depending on whether we are including or
5155 excluding the two ranges. */
5157 {
5158 /* If they don't overlap, the result is false. If the second range
5159 is a subset it is the result. Otherwise, the range is from the start
5160 of the second to the end of the first. */
5165 else
5167 }
5170 {
5171 /* If they don't overlap, the result is the first range. If they are
5172 equal, the result is false. If the second range is a subset of the
5173 first, and the ranges begin at the same place, we go from just after
5174 the end of the second range to the end of the first. If the second
5175 range is not a subset of the first, or if it is a subset and both
5176 ranges end at the same place, the range starts at the start of the
5177 first range and ends just before the second range.
5178 Otherwise, we can't describe this as a single range. */
5184 {
5189 {
5190 /* We are in the weird situation where high0 > high1 but
5191 high1 has no successor. Punt. */
5193 }
5194 }
5196 {
5201 {
5202 /* low0 < low1 but low1 has no predecessor. Punt. */
5204 }
5205 }
5206 else
5208 }
5211 {
5212 /* If they don't overlap, the result is the second range. If the second
5213 is a subset of the first, the result is false. Otherwise,
5214 the range starts just after the first range and ends at the
5215 end of the second. */
5220 else
5221 {
5226 {
5227 /* high1 > high0 but high0 has no successor. Punt. */
5229 }
5230 }
5231 }
5233 else
5234 {
5235 /* The case where we are excluding both ranges. Here the complex case
5236 is if they don't overlap. In that case, the only time we have a
5237 range is if they are adjacent. If the second is a subset of the
5238 first, the result is the first. Otherwise, the range to exclude
5239 starts at the beginning of the first range and ends at the end of the
5240 second. */
5242 {
5247 else
5248 {
5249 /* Canonicalize - [min, x] into - [-, x]. */
5252 {
5255 GET_MODE_BITSIZE
5258 /* FALLTHROUGH */
5271 }
5273 /* Canonicalize - [x, max] into - [x, -]. */
5276 {
5279 GET_MODE_BITSIZE
5282 /* FALLTHROUGH */
5298 }
5300 /* The ranges might be also adjacent between the maximum and
5301 minimum values of the given type. For
5302 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5303 return + [x + 1, y - 1]. */
5305 {
5312 }
5313 else
5315 }
5316 }
5319 else
5321 }
5325 }
5326 \f
5328 /* Subroutine of fold, looking inside expressions of the form
5329 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5330 of the COND_EXPR. This function is being used also to optimize
5331 A op B ? C : A, by reversing the comparison first.
5333 Return a folded expression whose code is not a COND_EXPR
5334 anymore, or NULL_TREE if no folding opportunity is found. */
5336 static tree
5339 {
5344 tree tem;
5349 /* If we have A op 0 ? A : -A, consider applying the following
5350 transformations:
5352 A == 0? A : -A same as -A
5353 A != 0? A : -A same as A
5354 A >= 0? A : -A same as abs (A)
5355 A > 0? A : -A same as abs (A)
5356 A <= 0? A : -A same as -abs (A)
5357 A < 0? A : -A same as -abs (A)
5359 None of these transformations work for modes with signed
5360 zeros. If A is +/-0, the first two transformations will
5361 change the sign of the result (from +0 to -0, or vice
5362 versa). The last four will fix the sign of the result,
5363 even though the original expressions could be positive or
5364 negative, depending on the sign of A.
5366 Note that all these transformations are correct if A is
5367 NaN, since the two alternatives (A and -A) are also NaNs. */
5374 /* In the case that A is of the form X-Y, '-A' (arg2) may
5375 have already been folded to Y-X, check for that. */
5383 {
5395 /* Fall through. */
5406 /* FALLTHRU */
5416 }
5418 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5419 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5420 both transformations are correct when A is NaN: A != 0
5421 is then true, and A == 0 is false. */
5425 {
5430 }
5432 /* Try some transformations of A op B ? A : B.
5434 A == B? A : B same as B
5435 A != B? A : B same as A
5436 A >= B? A : B same as max (A, B)
5437 A > B? A : B same as max (B, A)
5438 A <= B? A : B same as min (A, B)
5439 A < B? A : B same as min (B, A)
5441 As above, these transformations don't work in the presence
5442 of signed zeros. For example, if A and B are zeros of
5443 opposite sign, the first two transformations will change
5444 the sign of the result. In the last four, the original
5445 expressions give different results for (A=+0, B=-0) and
5446 (A=-0, B=+0), but the transformed expressions do not.
5448 The first two transformations are correct if either A or B
5449 is a NaN. In the first transformation, the condition will
5450 be false, and B will indeed be chosen. In the case of the
5451 second transformation, the condition A != B will be true,
5452 and A will be chosen.
5454 The conversions to max() and min() are not correct if B is
5455 a number and A is not. The conditions in the original
5456 expressions will be false, so all four give B. The min()
5457 and max() versions would give a NaN instead. */
5460 /* Avoid these transformations if the COND_EXPR may be used
5461 as an lvalue in the C++ front-end. PR c++/19199. */
5462 && (in_gimple_form
5468 {
5474 {
5483 /* In C++ a ?: expression can be an lvalue, so put the
5484 operand which will be used if they are equal first
5485 so that we can convert this back to the
5486 corresponding COND_EXPR. */
5488 {
5496 }
5503 {
5511 }
5524 }
5525 }
5528 }
5531 \f
5532 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5533 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5534 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5535 false) >= 2)
5536 #endif
5538 /* EXP is some logical combination of boolean tests. See if we can
5539 merge it into some range test. Return the new tree if so. */
5541 static tree
5544 {
5560 /* If this is an OR operation, invert both sides; we will invert
5561 again at the end. */
5565 /* If both expressions are the same, if we can merge the ranges, and we
5566 can build the range test, return it or it inverted. If one of the
5567 ranges is always true or always false, consider it to be the same
5568 expression as the other. */
5576 {
5580 }
5582 /* On machines where the branch cost is expensive, if this is a
5583 short-circuited branch and the underlying object on both sides
5584 is the same, make a non-short-circuit operation. */
5587 logical_op_non_short_circuit
5590 && !flag_sanitize_coverage
5594 {
5595 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5596 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5597 which cases we can't do this. */
5605 {
5614 {
5617 WARN_STRICT_OVERFLOW_COMPARISON);
5621 }
5622 }
5623 }
5626 }
5627 \f
5628 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5629 bit value. Arrange things so the extra bits will be set to zero if and
5630 only if C is signed-extended to its full width. If MASK is nonzero,
5631 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5633 static tree
5635 {
5638 tree temp;
5643 /* We work by getting just the sign bit into the low-order bit, then
5644 into the high-order bit, then sign-extend. We then XOR that value
5645 with C. */
5649 /* We must use a signed type in order to get an arithmetic right shift.
5650 However, we must also avoid introducing accidental overflows, so that
5651 a subsequent call to integer_zerop will work. Hence we must
5652 do the type conversion here. At this point, the constant is either
5653 zero or one, and the conversion to a signed type can never overflow.
5654 We could get an overflow if this conversion is done anywhere else. */
5663 /* If necessary, convert the type back to match the type of C. */
5668 }
5669 \f
5670 /* For an expression that has the form
5671 (A && B) || ~B
5672 or
5673 (A || B) && ~B,
5674 we can drop one of the inner expressions and simplify to
5675 A || ~B
5676 or
5677 A && ~B
5678 LOC is the location of the resulting expression. OP is the inner
5679 logical operation; the left-hand side in the examples above, while CMPOP
5680 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5681 removing a condition that guards another, as in
5682 (A != NULL && A->...) || A == NULL
5683 which we must not transform. If RHS_ONLY is true, only eliminate the
5684 right-most operand of the inner logical operation. */
5686 static tree
5689 {
5707 {
5710 {
5713 }
5714 }
5716 {
5719 {
5722 }
5723 }
5738 }
5740 /* Find ways of folding logical expressions of LHS and RHS:
5741 Try to merge two comparisons to the same innermost item.
5742 Look for range tests like "ch >= '0' && ch <= '9'".
5743 Look for combinations of simple terms on machines with expensive branches
5744 and evaluate the RHS unconditionally.
5746 For example, if we have p->a == 2 && p->b == 4 and we can make an
5747 object large enough to span both A and B, we can do this with a comparison
5748 against the object ANDed with the a mask.
5750 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5751 operations to do this with one comparison.
5753 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5754 function and the one above.
5756 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5757 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5759 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5760 two operands.
5762 We return the simplified tree or 0 if no optimization is possible. */
5764 static tree
5767 {
5768 /* If this is the "or" of two comparisons, we can do something if
5769 the comparisons are NE_EXPR. If this is the "and", we can do something
5770 if the comparisons are EQ_EXPR. I.e.,
5771 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5773 WANTED_CODE is this operation code. For single bit fields, we can
5774 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5775 comparison for one-bit fields. */
5796 /* Start by getting the comparison codes. Fail if anything is volatile.
5797 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5798 it were surrounded with a NE_EXPR. */
5807 {
5811 }
5814 {
5818 }
5829 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5832 {
5835 {
5840 }
5843 {
5849 }
5850 }
5855 /* If the RHS can be evaluated unconditionally and its operands are
5856 simple, it wins to evaluate the RHS unconditionally on machines
5857 with expensive branches. In this case, this isn't a comparison
5858 that can be merged. */
5865 {
5866 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5877 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5887 }
5889 /* See if the comparisons can be merged. Then get all the parameters for
5890 each side. */
5915 /* It must be true that the inner operation on the lhs of each
5916 comparison must be the same if we are to be able to do anything.
5917 Then see if we have constants. If not, the same must be true for
5918 the rhs's. */
5927 {
5930 }
5935 else
5938 /* If either comparison code is not correct for our logical operation,
5939 fail. However, we can convert a one-bit comparison against zero into
5940 the opposite comparison against that bit being set in the field. */
5944 {
5946 {
5947 /* Make the left operand unsigned, since we are only interested
5948 in the value of one bit. Otherwise we are doing the wrong
5949 thing below. */
5952 }
5953 else
5955 }
5957 /* This is analogous to the code for l_const above. */
5959 {
5961 {
5964 }
5965 else
5967 }
5969 /* See if we can find a mode that contains both fields being compared on
5970 the left. If we can't, fail. Otherwise, update all constants and masks
5971 to be relative to a field of that size. */
5985 {
5988 }
5996 {
6003 {
6007 }
6008 }
6010 {
6017 {
6021 }
6022 }
6024 /* If the right sides are not constant, do the same for it. Also,
6025 disallow this optimization if a size, signedness or storage order
6026 mismatch occurs between the left and right sides. */
6028 {
6032 /* Make sure the two fields on the right
6033 correspond to the left without being swapped. */
6050 {
6053 }
6062 /* Make a mask that corresponds to both fields being compared.
6063 Do this for both items being compared. If the operands are the
6064 same size and the bits being compared are in the same position
6065 then we can do this by masking both and comparing the masked
6066 results. */
6073 {
6087 }
6089 /* There is still another way we can do something: If both pairs of
6090 fields being compared are adjacent, we may be able to make a wider
6091 field containing them both.
6093 Note that we still must mask the lhs/rhs expressions. Furthermore,
6094 the mask must be shifted to account for the shift done by
6095 make_bit_field_ref. */
6104 {
6105 tree type;
6121 /* Convert to the smaller type before masking out unwanted bits. */
6124 {
6126 {
6130 }
6132 {
6136 }
6137 }
6146 }
6149 }
6151 /* Handle the case of comparisons with constants. If there is something in
6152 common between the masks, those bits of the constants must be the same.
6153 If not, the condition is always false. Test for this to avoid generating
6154 incorrect code below. */
6159 {
6161 {
6164 }
6165 else
6166 {
6169 }
6170 }
6175 /* Construct the expression we will return. First get the component
6176 reference we will make. Unless the mask is all ones the width of
6177 that field, perform the mask operation. Then compare with the
6178 merged constant. */
6189 }
6190 \f
6191 /* T is an integer expression that is being multiplied, divided, or taken a
6192 modulus (CODE says which and what kind of divide or modulus) by a
6193 constant C. See if we can eliminate that operation by folding it with
6194 other operations already in T. WIDE_TYPE, if non-null, is a type that
6195 should be used for the computation if wider than our type.
6197 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6198 (X * 2) + (Y * 4). We must, however, be assured that either the original
6199 expression would not overflow or that overflow is undefined for the type
6200 in the language in question.
6202 If we return a non-null expression, it is an equivalent form of the
6203 original computation, but need not be in the original type.
6205 We set *STRICT_OVERFLOW_P to true if the return values depends on
6206 signed overflow being undefined. Otherwise we do not change
6207 *STRICT_OVERFLOW_P. */
6209 static tree
6212 {
6213 /* To avoid exponential search depth, refuse to allow recursion past
6214 three levels. Beyond that (1) it's highly unlikely that we'll find
6215 something interesting and (2) we've probably processed it before
6216 when we built the inner expression. */
6219 tree ret;
6224 depth++;
6226 depth--;
6229 }
6231 static tree
6234 {
6246 /* Don't deal with constants of zero here; they confuse the code below. */
6256 /* Note that we need not handle conditional operations here since fold
6257 already handles those cases. So just do arithmetic here. */
6259 {
6261 /* For a constant, we can always simplify if we are a multiply
6262 or (for divide and modulus) if it is a multiple of our constant. */
6266 {
6269 /* If the multiplication overflowed, we lost information on it.
6270 See PR68142 and PR69845. */
6274 }
6278 /* If op0 is an expression ... */
6284 /* ... and has wrapping overflow, and its type is smaller
6285 than ctype, then we cannot pass through as widening. */
6290 /* ... or this is a truncation (t is narrower than op0),
6291 then we cannot pass through this narrowing. */
6294 /* ... or signedness changes for division or modulus,
6295 then we cannot pass through this conversion. */
6299 /* ... or has undefined overflow while the converted to
6300 type has not, we cannot do the operation in the inner type
6301 as that would introduce undefined overflow. */
6307 /* Pass the constant down and see if we can make a simplification. If
6308 we can, replace this expression with the inner simplification for
6309 possible later conversion to our or some other type. */
6320 /* If widening the type changes it from signed to unsigned, then we
6321 must avoid building ABS_EXPR itself as unsigned. */
6323 {
6327 {
6330 }
6332 }
6333 /* If the constant is negative, we cannot simplify this. */
6336 /* FALLTHROUGH */
6338 /* For division and modulus, type can't be unsigned, as e.g.
6339 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6340 For signed types, even with wrapping overflow, this is fine. */
6349 /* If widening the type changes the signedness, then we can't perform
6350 this optimization as that changes the result. */
6354 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6360 {
6367 }
6371 /* If the second operand is constant, this is a multiplication
6372 or floor division, by a power of two, so we can treat it that
6373 way unless the multiplier or divisor overflows. Signed
6374 left-shift overflow is implementation-defined rather than
6375 undefined in C90, so do not convert signed left shift into
6376 multiplication. */
6379 /* const_binop may not detect overflow correctly,
6380 so check for it explicitly here. */
6389 ctype,
6391 t1),
6396 /* See if we can eliminate the operation on both sides. If we can, we
6397 can return a new PLUS or MINUS. If we can't, the only remaining
6398 cases where we can do anything are if the second operand is a
6399 constant. */
6406 /* If not multiplication, we can only do this if both operands
6407 are divisible by c. */
6410 {
6415 }
6417 /* If this was a subtraction, negate OP1 and set it to be an addition.
6418 This simplifies the logic below. */
6420 {
6422 /* If OP1 was not easily negatable, the constant may be OP0. */
6424 {
6427 }
6428 }
6433 /* If either OP1 or C are negative, this optimization is not safe for
6434 some of the division and remainder types while for others we need
6435 to change the code. */
6437 {
6445 }
6447 /* If it's a multiply or a division/modulus operation of a multiple
6448 of our constant, do the operation and verify it doesn't overflow. */
6452 {
6455 /* We allow the constant to overflow with wrapping semantics. */
6459 }
6460 else
6463 /* If we have an unsigned type, we cannot widen the operation since it
6464 will change the result if the original computation overflowed. */
6468 /* The last case is if we are a multiply. In that case, we can
6469 apply the distributive law to commute the multiply and addition
6470 if the multiplication of the constants doesn't overflow
6471 and overflow is defined. With undefined overflow
6472 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6478 op1);
6483 /* We have a special case here if we are doing something like
6484 (C * 8) % 4 since we know that's zero. */
6487 /* If the multiplication can overflow we cannot optimize this. */
6492 {
6495 }
6497 /* ... fall through ... */
6501 /* If we can extract our operation from the LHS, do so and return a
6502 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6503 do something only if the second operand is a constant. */
6519 /* If these are the same operation types, we can associate them
6520 assuming no overflow. */
6522 {
6537 }
6539 /* If these operations "cancel" each other, we have the main
6540 optimizations of this pass, which occur when either constant is a
6541 multiple of the other, in which case we replace this with either an
6542 operation or CODE or TCODE.
6544 If we have an unsigned type, we cannot do this since it will change
6545 the result if the original computation overflowed. */
6552 {
6555 {
6562 }
6565 {
6572 }
6573 }
6578 }
6581 }
6582 \f
6583 /* Return a node which has the indicated constant VALUE (either 0 or
6584 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6585 and is of the indicated TYPE. */
6587 tree
6589 {
6598 else
6600 }
6603 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6604 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6605 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6606 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6607 COND is the first argument to CODE; otherwise (as in the example
6608 given here), it is the second argument. TYPE is the type of the
6609 original expression. Return NULL_TREE if no simplification is
6610 possible. */
6612 static tree
6617 {
6625 /* Do not move possibly trapping operations into the conditional as this
6626 pessimizes code and causes gimplification issues when applied late. */
6634 {
6638 /* If this operand throws an expression, then it does not make
6639 sense to try to perform a logical or arithmetic operation
6640 involving it. */
6645 }
6648 {
6653 }
6654 else
6655 /* Detect the case of mixing vector and scalar types - bail out. */
6661 /* This transformation is only worthwhile if we don't have to wrap ARG
6662 in a SAVE_EXPR and the operation can be simplified without recursing
6663 on at least one of the branches once its pushed inside the COND_EXPR. */
6672 {
6676 else
6678 }
6680 {
6684 else
6686 }
6688 /* Check that we have simplified at least one of the branches. */
6693 }
6695 \f
6696 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6698 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6699 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6700 ADDEND is the same as X.
6702 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6703 and finite. The problematic cases are when X is zero, and its mode
6704 has signed zeros. In the case of rounding towards -infinity,
6705 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6706 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6708 bool
6710 {
6714 /* Don't allow the fold with -fsignaling-nans. */
6718 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6722 /* In a vector or complex, we would need to check the sign of all zeros. */
6726 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6730 /* The mode has signed zeros, and we have to honor their sign.
6731 In this situation, there is only one case we can return true for.
6732 X - 0 is the same as X unless rounding towards -infinity is
6733 supported. */
6735 }
6737 /* Subroutine of match.pd that optimizes comparisons of a division by
6738 a nonzero integer constant against an integer constant, i.e.
6739 X/C1 op C2.
6741 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6742 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6744 enum tree_code
6747 {
6752 /* We have to do this the hard way to detect unsigned overflow.
6753 prod = int_const_binop (MULT_EXPR, c1, c2); */
6759 {
6763 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6766 }
6768 {
6771 {
6790 }
6791 }
6792 else
6793 {
6794 /* A negative divisor reverses the relational operators. */
6799 {
6818 }
6819 }
6832 }
6835 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6836 equality/inequality test, then return a simplified form of the test
6837 using a sign testing. Otherwise return NULL. TYPE is the desired
6838 result type. */
6840 static tree
6843 tree result_type)
6844 {
6845 /* If this is testing a single bit, we can optimize the test. */
6849 {
6850 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6851 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6855 /* This is only a win if casting to a signed type is cheap,
6856 i.e. when arg00's type is not a partial mode. */
6858 {
6861 result_type,
6864 }
6865 }
6868 }
6870 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6871 equality/inequality test, then return a simplified form of
6872 the test using shifts and logical operations. Otherwise return
6873 NULL. TYPE is the desired result type. */
6875 tree
6878 {
6879 /* If this is testing a single bit, we can optimize the test. */
6883 {
6892 /* First, see if we can fold the single bit test into a sign-bit
6893 test. */
6895 result_type);
6899 /* Otherwise we have (A & C) != 0 where C is a single bit,
6900 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6901 Similarly for (A & C) == 0. */
6903 /* If INNER is a right shift of a constant and it plus BITNUM does
6904 not overflow, adjust BITNUM and INNER. */
6910 {
6913 }
6915 /* If we are going to be able to omit the AND below, we must do our
6916 operations as unsigned. If we must use the AND, we have a choice.
6917 Normally unsigned is faster, but for some machines signed is. */
6935 /* Put the AND last so it can combine with more things. */
6938 /* Make sure to return the proper type. */
6942 }
6944 }
6946 /* Test whether it is preferable two swap two operands, ARG0 and
6947 ARG1, for example because ARG0 is an integer constant and ARG1
6948 isn't. */
6950 bool
6952 {
6966 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6967 for commutative and comparison operators. Ensuring a canonical
6968 form allows the optimizers to find additional redundancies without
6969 having to explicitly check for both orderings. */
6975 /* Put SSA_NAMEs last. */
6981 /* Put variables last. */
6988 }
6991 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6992 means A >= Y && A != MAX, but in this case we know that
6993 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6995 static tree
6997 {
7004 else
7013 {
7016 }
7018 {
7021 }
7022 else
7029 {
7030 /* Convert the pointer types into integer before taking the difference. */
7034 }
7035 else
7042 }
7044 /* Fold a sum or difference of at least one multiplication.
7045 Returns the folded tree or NULL if no simplification could be made. */
7047 static tree
7050 {
7054 /* (A * C) +- (B * C) -> (A+-B) * C.
7055 (A * C) +- A -> A * (C+-1).
7056 We are most concerned about the case where C is a constant,
7057 but other combinations show up during loop reduction. Since
7058 it is not difficult, try all four possibilities. */
7061 {
7064 }
7066 {
7069 }
7070 else
7071 {
7072 /* We cannot generate constant 1 for fract. */
7077 }
7079 {
7082 }
7084 {
7086 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7087 the purpose of this canonicalization. */
7091 {
7094 }
7095 else
7097 }
7098 else
7099 {
7100 /* We cannot generate constant 1 for fract. */
7105 }
7108 /* Prefer factoring a common non-constant. */
7118 /* No identical multiplicands; see if we can find a common
7119 power-of-two factor in non-power-of-two multiplies. This
7120 can help in multi-dimensional array access. */
7123 {
7126 tree maybe_same;
7130 /* Move min of absolute values to int11. */
7132 {
7137 }
7138 else
7142 /* The remainder should not be a constant, otherwise we
7143 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7144 increased the number of multiplications necessary. */
7146 {
7154 }
7155 }
7162 /* We are neither factoring zero nor minus one. */
7170 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7171 same may be minus one and thus the multiplication may overflow. Perform
7172 the sum operation in an unsigned type. */
7177 /* If the sum evaluated to a constant that is not -INF the multiplication
7178 cannot overflow. */
7185 /* Do not resort to unsigned multiplication because
7186 we lose the no-overflow property of the expression. */
7188 }
7190 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7191 specified by EXPR into the buffer PTR of length LEN bytes.
7192 Return the number of bytes placed in the buffer, or zero
7193 upon failure. */
7195 static int
7197 {
7209 /* Dry run. */
7215 {
7217 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7218 number of bytes. */
7222 {
7229 else
7231 }
7232 else
7236 }
7238 }
7241 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7242 specified by EXPR into the buffer PTR of length LEN bytes.
7243 Return the number of bytes placed in the buffer, or zero
7244 upon failure. */
7246 static int
7248 {
7252 FIXED_VALUE_TYPE value;
7267 }
7270 /* Subroutine of native_encode_expr. Encode the REAL_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 {
7283 /* There are always 32 bits in each long, no matter the size of
7284 the hosts long. We handle floating point representations with
7285 up to 192 bits. */
7294 /* Dry run. */
7303 {
7308 {
7315 else
7317 }
7318 else
7319 {
7322 {
7323 /* Reverse bytes within each long, or within the entire float
7324 if it's smaller than a long (for HFmode). */
7327 }
7328 }
7333 }
7335 }
7337 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7338 specified by EXPR into the buffer PTR of length LEN bytes.
7339 Return the number of bytes placed in the buffer, or zero
7340 upon failure. */
7342 static int
7344 {
7346 tree part;
7360 }
7363 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7364 specified by EXPR into the buffer PTR of length LEN bytes.
7365 Return the number of bytes placed in the buffer, or zero
7366 upon failure. */
7368 static int
7370 {
7381 {
7383 {
7386 }
7397 }
7399 }
7402 /* Subroutine of native_encode_expr. Encode the STRING_CST
7403 specified by EXPR into the buffer PTR of length LEN bytes.
7404 Return the number of bytes placed in the buffer, or zero
7405 upon failure. */
7407 static int
7409 {
7412 /* Wide-char strings are encoded in target byte-order so native
7413 encoding them is trivial. */
7428 {
7431 {
7434 }
7437 }
7438 else
7441 }
7444 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7445 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7446 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7447 anything, just do a dry run. If OFF is not -1 then start
7448 the encoding at byte offset OFF and encode at most LEN bytes.
7449 Return the number of bytes placed in the buffer, or zero upon failure. */
7451 int
7453 {
7454 /* We don't support starting at negative offset and -1 is special. */
7459 {
7480 }
7481 }
7484 /* Subroutine of native_interpret_expr. Interpret the contents of
7485 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7486 If the buffer cannot be interpreted, return NULL_TREE. */
7488 static tree
7490 {
7500 }
7503 /* Subroutine of native_interpret_expr. Interpret the contents of
7504 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7505 If the buffer cannot be interpreted, return NULL_TREE. */
7507 static tree
7509 {
7512 double_int result;
7513 FIXED_VALUE_TYPE fixed_value;
7523 }
7526 /* Subroutine of native_interpret_expr. Interpret the contents of
7527 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7528 If the buffer cannot be interpreted, return NULL_TREE. */
7530 static tree
7532 {
7536 /* There are always 32 bits in each long, no matter the size of
7537 the hosts long. We handle floating point representations with
7538 up to 192 bits. */
7539 REAL_VALUE_TYPE r;
7549 {
7550 /* Both OFFSET and BYTE index within a long;
7551 bitpos indexes the whole float. */
7554 {
7561 else
7563 }
7564 else
7565 {
7568 {
7569 /* Reverse bytes within each long, or within the entire float
7570 if it's smaller than a long (for HFmode). */
7573 }
7574 }
7578 }
7582 }
7585 /* Subroutine of native_interpret_expr. Interpret the contents of
7586 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7587 If the buffer cannot be interpreted, return NULL_TREE. */
7589 static tree
7591 {
7606 }
7609 /* Subroutine of native_interpret_expr. Interpret the contents of
7610 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7611 If the buffer cannot be interpreted, return NULL_TREE. */
7613 static tree
7615 {
7628 {
7633 }
7635 }
7638 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7639 the buffer PTR of length LEN as a constant of type TYPE. For
7640 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7641 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7642 return NULL_TREE. */
7644 tree
7646 {
7648 {
7670 }
7671 }
7673 /* Returns true if we can interpret the contents of a native encoding
7674 as TYPE. */
7676 static bool
7678 {
7680 {
7693 }
7694 }
7697 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7698 TYPE at compile-time. If we're unable to perform the conversion
7699 return NULL_TREE. */
7701 static tree
7703 {
7704 /* We support up to 512-bit values (for V8DFmode). */
7708 /* Check that the host and target are sane. */
7717 }
7719 /* Build an expression for the address of T. Folds away INDIRECT_REF
7720 to avoid confusing the gimplify process. */
7722 tree
7724 {
7725 /* The size of the object is not relevant when talking about its address. */
7730 {
7735 }
7745 {
7750 }
7751 else
7755 }
7757 /* Build an expression for the address of T. */
7759 tree
7761 {
7765 }
7767 /* Fold a unary expression of code CODE and type TYPE with operand
7768 OP0. Return the folded expression if folding is successful.
7769 Otherwise, return NULL_TREE. */
7771 tree
7773 {
7774 tree tem;
7775 tree arg0;
7783 {
7786 {
7787 /* Don't use STRIP_NOPS, because signedness of argument type
7788 matters. */
7790 }
7791 else
7792 {
7793 /* Strip any conversions that don't change the mode. This
7794 is safe for every expression, except for a comparison
7795 expression because its signedness is derived from its
7796 operands.
7798 Note that this is done as an internal manipulation within
7799 the constant folder, in order to find the simplest
7800 representation of the arguments so that their form can be
7801 studied. In any cases, the appropriate type conversions
7802 should be put back in the tree that will get out of the
7803 constant folder. */
7805 }
7808 {
7811 {
7815 }
7816 }
7817 }
7824 {
7831 {
7845 /* If this was a conversion, and all we did was to move into
7846 inside the COND_EXPR, bring it back out. But leave it if
7847 it is a conversion from integer to integer and the
7848 result precision is no wider than a word since such a
7849 conversion is cheap and may be optimized away by combine,
7850 while it couldn't if it were outside the COND_EXPR. Then return
7851 so we don't get into an infinite recursion loop taking the
7852 conversion out and then back in. */
7864 && (INTEGRAL_TYPE_P
7877 }
7878 }
7881 {
7887 CASE_CONVERT:
7891 {
7892 /* If we have (type) (a CMP b) and type is an integral type, return
7893 new expression involving the new type. Canonicalize
7894 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7895 non-integral type.
7896 Do not fold the result as that would not simplify further, also
7897 folding again results in recursions. */
7907 }
7909 /* Handle (T *)&A.B.C for A being of type T and B and C
7910 living at offset zero. This occurs frequently in
7911 C++ upcasting and then accessing the base. */
7915 {
7917 tree offset;
7918 machine_mode mode;
7920 tree base
7924 /* If the reference was to a (constant) zero offset, we can use
7925 the address of the base if it has the same base type
7926 as the result type and the pointer type is unqualified. */
7934 }
7938 /* Detect assigning a bitfield. */
7940 && DECL_BIT_FIELD
7942 {
7943 /* Don't leave an assignment inside a conversion
7944 unless assigning a bitfield. */
7946 /* First do the assignment, then return converted constant. */
7951 }
7953 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7954 constants (if x has signed type, the sign bit cannot be set
7955 in c). This folds extension into the BIT_AND_EXPR.
7956 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7957 very likely don't have maximal range for their precision and this
7958 transformation effectively doesn't preserve non-maximal ranges. */
7962 {
7973 <= HOST_BITS_PER_WIDE_INT
7975 {
7979 cst &= HOST_WIDE_INT_M1U
7983 && !flag_syntax_only
7986 {
7990 }
7991 }
7993 {
7998 }
7999 }
8001 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
8002 cast (T1)X will fold away. We assume that this happens when X itself
8003 is a cast. */
8007 {
8011 return fold_build_pointer_plus_loc
8013 }
8015 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8016 of the same precision, and X is an integer type not narrower than
8017 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8023 {
8029 }
8031 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8032 type of X and Y (integer types only). */
8037 {
8038 /* Be careful not to introduce new overflows. */
8039 tree mult_type;
8042 else
8046 {
8053 }
8054 }
8060 {
8067 }
8078 /* Convert fabs((double)float) into (double)fabsf(float). */
8081 {
8087 targ0));
8088 }
8092 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8111 /* Note that the operand of this must be an int
8112 and its values must be 0 or 1.
8113 ("true" is a fixed value perhaps depending on the language,
8114 but we don't handle values other than 1 correctly yet.) */
8121 /* Fold *&X to X if X is an lvalue. */
8123 {
8130 }
8136 }
8139 /* If the operation was a conversion do _not_ mark a resulting constant
8140 with TREE_OVERFLOW if the original constant was not. These conversions
8141 have implementation defined behavior and retaining the TREE_OVERFLOW
8142 flag here would confuse later passes such as VRP. */
8143 tree
8146 {
8155 }
8157 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8158 operands OP0 and OP1. LOC is the location of the resulting expression.
8159 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8160 Return the folded expression if folding is successful. Otherwise,
8161 return NULL_TREE. */
8162 static tree
8165 {
8166 tree tem;
8168 /* We only do these simplifications if we are optimizing. */
8172 /* Check for things like (A || B) && (A || C). We can convert this
8173 to A || (B && C). Note that either operator can be any of the four
8174 truth and/or operations and the transformation will still be
8175 valid. Also note that we only care about order for the
8176 ANDIF and ORIF operators. If B contains side effects, this
8177 might change the truth-value of A. */
8184 {
8204 /* This case if tricky because we must either have commutative
8205 operators or else A10 must not have side-effects. */
8211 a01);
8212 }
8214 /* See if we can build a range comparison. */
8220 {
8224 }
8228 {
8232 }
8234 /* Check for the possibility of merging component references. If our
8235 lhs is another similar operation, try to merge its rhs with our
8236 rhs. Then try to merge our lhs and rhs. */
8247 logical_op_non_short_circuit
8250 && !flag_sanitize_coverage
8255 {
8262 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8263 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8264 We don't want to pack more than two leafs to a non-IF AND/OR
8265 expression.
8266 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8267 equal to IF-CODE, then we don't want to add right-hand operand.
8268 If the inner right-hand side of left-hand operand has
8269 side-effects, or isn't simple, then we can't add to it,
8270 as otherwise we might destroy if-sequence. */
8273 /* Needed for sequence points to handle trappings, and
8274 side-effects. */
8276 {
8278 arg1);
8280 tem);
8281 }
8282 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8283 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8286 /* Needed for sequence points to handle trappings, and
8287 side-effects. */
8289 {
8294 }
8295 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8296 into (A OR B).
8297 For sequence point consistancy, we need to check for trapping,
8298 and side-effects. */
8302 }
8305 }
8307 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8308 by changing CODE to reduce the magnitude of constants involved in
8309 ARG0 of the comparison.
8310 Returns a canonicalized comparison tree if a simplification was
8311 possible, otherwise returns NULL_TREE.
8312 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8313 valid if signed overflow is undefined. */
8315 static tree
8319 {
8324 /* Match A +- CST code arg1. We can change this only if overflow
8325 is undefined. */
8328 /* In principle pointers also have undefined overflow behavior,
8329 but that causes problems elsewhere. */
8336 /* Identify the constant in arg0 and its sign. */
8340 /* Overflowed constants and zero will cause problems. */
8345 /* See if we can reduce the magnitude of the constant in
8346 arg0 by changing the comparison code. */
8347 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8351 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8355 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8359 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8363 else
8367 /* Now build the constant reduced in magnitude. But not if that
8368 would produce one outside of its types range. */
8384 }
8386 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8387 overflow further. Try to decrease the magnitude of constants involved
8388 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8389 and put sole constants at the second argument position.
8390 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8392 static tree
8395 {
8396 tree t;
8401 /* Try canonicalization by simplifying arg0. */
8406 {
8410 }
8412 /* Try canonicalization by simplifying arg1 using the swapped
8413 comparison. */
8421 }
8423 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8424 space. This is used to avoid issuing overflow warnings for
8425 expressions like &p->x which cannot wrap. */
8427 static bool
8429 {
8436 poly_wide_int wi_offset;
8442 else
8447 precision);
8462 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8463 array. */
8472 }
8474 /* Return a positive integer when the symbol DECL is known to have
8475 a nonzero address, zero when it's known not to (e.g., it's a weak
8476 symbol), and a negative integer when the symbol is not yet in the
8477 symbol table and so whether or not its address is zero is unknown.
8478 For function local objects always return positive integer. */
8479 static int
8481 {
8486 /* Function local objects are never NULL. */
8494 }
8496 /* Subroutine of fold_binary. This routine performs all of the
8497 transformations that are common to the equality/inequality
8498 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8499 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8500 fold_binary should call fold_binary. Fold a comparison with
8501 tree code CODE and type TYPE with operands OP0 and OP1. Return
8502 the folded comparison or NULL_TREE. */
8504 static tree
8507 {
8517 /* For comparisons of pointers we can decompose it to a compile time
8518 comparison of the base objects and the offsets into the object.
8519 This requires at least one operand being an ADDR_EXPR or a
8520 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8526 {
8529 machine_mode mode;
8533 /* Get base and offset for the access. Strip ADDR_EXPR for
8534 get_inner_reference, but put it back by stripping INDIRECT_REF
8535 off the base object if possible. indirect_baseN will be true
8536 if baseN is not an address but refers to the object itself. */
8539 {
8540 base0
8546 else
8548 }
8550 {
8554 {
8555 base0
8561 else
8563 }
8566 else
8570 {
8577 }
8578 }
8582 {
8583 base1
8589 else
8591 }
8593 {
8597 {
8598 base1
8604 else
8606 }
8609 else
8613 {
8620 }
8621 }
8623 /* If we have equivalent bases we might be able to simplify. */
8627 {
8628 /* We can fold this expression to a constant if the non-constant
8629 offset parts are equal. */
8633 && (equality_code
8634 || (indirect_base0
8637 {
8643 "occur when comparing P +- C1 with "
8645 WARN_STRICT_OVERFLOW_CONDITIONAL);
8648 {
8686 }
8687 }
8688 /* We can simplify the comparison to a comparison of the variable
8689 offset parts if the constant offset parts are equal.
8690 Be careful to use signed sizetype here because otherwise we
8691 mess with array offsets in the wrong way. This is possible
8692 because pointer arithmetic is restricted to retain within an
8693 object and overflow on pointer differences is undefined as of
8694 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8696 && (equality_code
8697 || (indirect_base0
8700 {
8701 /* By converting to signed sizetype we cover middle-end pointer
8702 arithmetic which operates on unsigned pointer types of size
8703 type size and ARRAY_REF offsets which are properly sign or
8704 zero extended from their type in case it is narrower than
8705 sizetype. */
8708 else
8712 else
8719 "occur when comparing P +- C1 with "
8721 WARN_STRICT_OVERFLOW_COMPARISON);
8724 }
8725 }
8726 /* For equal offsets we can simplify to a comparison of the
8727 base addresses. */
8729 && (indirect_base0
8731 && (indirect_base1
8736 {
8742 }
8743 /* Comparison between an ordinary (non-weak) symbol and a null
8744 pointer can be eliminated since such symbols must have a non
8745 null address. In C, relational expressions between pointers
8746 to objects and null pointers are undefined. The results
8747 below follow the C++ rules with the additional property that
8748 every object pointer compares greater than a null pointer.
8749 */
8752 /* Avoid folding references to struct members at offset 0 to
8753 prevent tests like '&ptr->firstmember == 0' from getting
8754 eliminated. When ptr is null, although the -> expression
8755 is strictly speaking invalid, GCC retains it as a matter
8756 of QoI. See PR c/44555. */
8759 && indirect_base0
8760 /* The caller guarantees that when one of the arguments is
8761 constant (i.e., null in this case) it is second. */
8763 {
8765 {
8776 }
8777 }
8778 }
8780 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8781 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8782 the resulting offset is smaller in absolute value than the
8783 original one and has the same sign. */
8792 {
8797 tree cst;
8799 "occur when combining constants around "
8802 /* Put the constant on the side where it doesn't overflow and is
8803 of lower absolute value and of same sign than before. */
8810 {
8813 variable1,
8817 }
8825 {
8831 variable2);
8832 }
8833 }
8839 /* If we are comparing an expression that just has comparisons
8840 of two integer values, arithmetic expressions of those comparisons,
8841 and constants, we can simplify it. There are only three cases
8842 to check: the two values can either be equal, the first can be
8843 greater, or the second can be greater. Fold the expression for
8844 those three values. Since each value must be 0 or 1, we have
8845 eight possibilities, each of which corresponds to the constant 0
8846 or 1 or one of the six possible comparisons.
8848 This handles common cases like (a > b) == 0 but also handles
8849 expressions like ((x > y) - (y > x)) > 0, which supposedly
8850 occur in macroized code. */
8853 {
8857 /* Don't handle degenerate cases here; they should already
8858 have been handled anyway. */
8867 {
8871 /* We can't just pass T to eval_subst in case cval1 or cval2
8872 was the same as ARG1. */
8874 tree high_result
8878 arg1);
8879 tree equal_result
8883 arg1);
8884 tree low_result
8888 arg1);
8890 /* All three of these results should be 0 or 1. Confirm they are.
8891 Then use those values to select the proper code to use. */
8896 {
8897 /* Make a 3-bit mask with the high-order bit being the
8898 value for `>', the next for '=', and the low for '<'. */
8902 {
8904 /* Always false. */
8925 /* Always true. */
8927 }
8930 }
8931 }
8932 }
8935 }
8938 /* Subroutine of fold_binary. Optimize complex multiplications of the
8939 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8940 argument EXPR represents the expression "z" of type TYPE. */
8942 static tree
8944 {
8949 {
8952 }
8954 {
8957 }
8958 else
8959 {
8963 }
8972 }
8975 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8976 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8977 true if successful. */
8979 static bool
8981 {
8986 {
8989 }
8991 {
8997 else
8999 }
9000 else
9006 }
9008 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9009 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9010 NULL_TREE otherwise. */
9012 static tree
9014 {
9035 {
9036 HOST_WIDE_INT index;
9042 }
9045 {
9051 }
9052 else
9054 }
9056 /* Try to fold a pointer difference of type TYPE two address expressions of
9057 array references AREF0 and AREF1 using location LOC. Return a
9058 simplified expression for the difference or NULL_TREE. */
9060 static tree
9064 {
9069 /* If the bases are array references as well, recurse. If the bases
9070 are pointer indirections compute the difference of the pointers.
9071 If the bases are equal, we are set. */
9074 && (base_offset
9076 use_pointer_diff)))
9079 && (base_offset
9080 = use_pointer_diff
9090 {
9096 base_offset,
9099 }
9101 }
9103 /* If the real or vector real constant CST of type TYPE has an exact
9104 inverse, return it, else return NULL. */
9106 tree
9108 {
9109 REAL_VALUE_TYPE r;
9110 tree unit_type;
9111 machine_mode mode;
9114 {
9124 {
9128 tree_vector_builder elts;
9133 {
9138 }
9141 }
9145 }
9146 }
9148 /* Mask out the tz least significant bits of X of type TYPE where
9149 tz is the number of trailing zeroes in Y. */
9150 static wide_int
9152 {
9157 }
9159 /* Return true when T is an address and is known to be nonzero.
9160 For floating point we further ensure that T is not denormal.
9161 Similar logic is present in nonzero_address in rtlanal.h.
9163 If the return value is based on the assumption that signed overflow
9164 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9165 change *STRICT_OVERFLOW_P. */
9167 static bool
9169 {
9173 /* Doing something useful for floating point would need more work. */
9179 {
9182 strict_overflow_p);
9188 strict_overflow_p);
9196 }
9199 {
9202 strict_overflow_p);
9210 strict_overflow_p);
9225 strict_overflow_p);
9229 strict_overflow_p);
9232 {
9244 }
9248 }
9250 }
9252 /* Return true when T is an address and is known to be nonzero.
9253 Handle warnings about undefined signed overflow. */
9255 bool
9257 {
9264 "determining that expression is always "
9266 WARN_STRICT_OVERFLOW_MISC);
9268 }
9270 /* Return true if T is known not to be equal to an integer W. */
9272 bool
9274 {
9276 value_range_kind rtype;
9278 {
9287 {
9292 }
9297 /* If T has some known zero bits and W has any of those bits set,
9298 then T is known not to be equal to W. */
9306 }
9307 }
9309 /* Fold a binary expression of code CODE and type TYPE with operands
9310 OP0 and OP1. LOC is the location of the resulting expression.
9311 Return the folded expression if folding is successful. Otherwise,
9312 return NULL_TREE. */
9314 tree
9317 {
9332 /* Strip any conversions that don't change the mode. This is
9333 safe for every expression, except for a comparison expression
9334 because its signedness is derived from its operands. So, in
9335 the latter case, only strip conversions that don't change the
9336 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9337 preserved.
9339 Note that this is done as an internal manipulation within the
9340 constant folder, in order to find the simplest representation
9341 of the arguments so that their form can be studied. In any
9342 cases, the appropriate type conversions should be put back in
9343 the tree that will get out of the constant folder. */
9346 {
9349 }
9350 else
9351 {
9354 }
9356 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9357 constant but we can't do arithmetic on them. */
9359 {
9362 {
9366 }
9367 }
9369 /* If this is a commutative operation, and ARG0 is a constant, move it
9370 to ARG1 to reduce the number of tests below. */
9375 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9376 to ARG1 to reduce the number of tests below. */
9385 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9387 First check for cases where an arithmetic operation is applied to a
9388 compound, conditional, or comparison operation. Push the arithmetic
9389 operation inside the compound or conditional to see if any folding
9390 can then be done. Convert comparison to conditional for this purpose.
9391 The also optimizes non-constant cases that used to be done in
9392 expand_expr.
9394 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9395 one of the operands is a comparison and the other is a comparison, a
9396 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9397 code below would make the expression more complex. Change it to a
9398 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9399 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9412 {
9416 boolean_type_node,
9424 }
9428 {
9430 {
9435 tem);
9436 }
9438 {
9443 tem);
9444 }
9449 {
9455 }
9460 {
9466 }
9467 }
9470 {
9472 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9475 {
9481 }
9483 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9486 {
9487 tree base;
9488 poly_int64 coffset;
9497 }
9502 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9508 arg1),
9510 arg0)));
9516 {
9517 /* X + (X / CST) * -CST is X % CST. */
9522 {
9531 cst0));
9532 }
9533 }
9535 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9536 one. Make sure the type is not saturating and has the signedness of
9537 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9538 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9545 {
9549 }
9552 {
9553 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9554 (plus (plus (mult) (mult)) (foo)) so that we can
9555 take advantage of the factoring cases below. */
9564 {
9570 else
9583 parg0),
9585 marg)),
9589 return
9595 parg1)));
9596 }
9597 }
9598 else
9599 {
9600 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9601 to __complex__ ( x, y ). This is not the same for SNaNs or
9602 if signed zeros are involved. */
9606 {
9613 {
9617 {
9623 }
9625 {
9631 }
9632 }
9633 }
9635 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9636 We associate floats only if the user has specified
9637 -fassociative-math. */
9641 {
9646 {
9647 tree tree0;
9650 }
9651 }
9652 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9653 We associate floats only if the user has specified
9654 -fassociative-math. */
9658 {
9663 {
9664 tree tree0;
9667 }
9668 }
9669 }
9671 bit_rotate:
9672 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9673 is a rotate of A by C1 bits. */
9674 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9675 is a rotate of A by B bits.
9676 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9677 though in this case CODE must be | and not + or ^, otherwise
9678 it doesn't return A when B is 0. */
9679 {
9681 tree rtype;
9690 /* Only create rotates in complete modes. Other cases are not
9691 expanded properly. */
9694 {
9707 {
9712 }
9717 {
9720 code0 == LSHIFT_EXPR
9723 }
9725 {
9735 {
9739 orig_tree01);
9741 }
9742 }
9746 {
9757 {
9761 orig_tree01);
9763 }
9764 }
9765 }
9766 }
9768 associate:
9769 /* In most languages, can't associate operations on floats through
9770 parentheses. Rather than remember where the parentheses were, we
9771 don't associate floats at all, unless the user has specified
9772 -fassociative-math.
9773 And, we need to make sure type is not saturating. */
9777 {
9783 /* Split both trees into variables, constants, and literals. Then
9784 associate each group together, the constants with literals,
9785 then the result with variables. This increases the chances of
9786 literals being recombined later and of generating relocatable
9787 expressions for the sum of a constant and literal. */
9795 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9799 /* With undefined overflow prefer doing association in a type
9800 which wraps on overflow, if that is one of the operand types. */
9803 {
9811 }
9813 /* With undefined overflow we can only associate constants with one
9814 variable, and constants whose association doesn't overflow. */
9817 {
9819 {
9820 /* ??? If split_tree would handle NEGATE_EXPR we could
9821 simply reject these cases and the allowed cases would
9822 be the var0/minus_var1 ones. */
9828 {
9831 }
9838 {
9841 }
9847 /* The only case we can still associate with two variables
9848 is if they cancel out. */
9852 }
9858 }
9860 /* Only do something if we found more than two objects. Otherwise,
9861 nothing has changed and we risk infinite recursion. */
9869 {
9881 {
9885 }
9887 {
9891 }
9893 /* Preserve the MINUS_EXPR if the negative part of the literal is
9894 greater than the positive part. Otherwise, the multiplicative
9895 folding code (i.e extract_muldiv) may be fooled in case
9896 unsigned constants are subtracted, like in the following
9897 example: ((X*2 + 4) - 8U)/2. */
9899 {
9903 /* But avoid ending up with only negated parts. */
9905 {
9909 }
9910 else
9911 {
9915 }
9916 }
9918 /* Don't introduce overflows through reassociation. */
9923 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9930 /* Eliminate minus_con0. */
9932 {
9939 else
9942 }
9944 /* Eliminate minus_var0. */
9946 {
9950 else
9953 }
9955 return
9958 }
9959 }
9965 /* Fold &a[i] - &a[j] to i-j. */
9970 {
9974 code
9978 }
9980 /* Further transformations are not for pointers. */
9984 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9987 /* If arg0 is e.g. unsigned int and type is int, then this could
9988 introduce UB, because if A is INT_MIN at runtime, the original
9989 expression can be well defined while the latter is not.
9990 See PR83269. */
9999 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10000 __complex__ ( x, -y ). This is not the same for SNaNs or if
10001 signed zeros are involved. */
10005 {
10012 {
10016 {
10018 arg1r ? arg1r
10023 }
10025 {
10029 arg1i ? arg1i
10032 }
10033 }
10034 }
10036 /* A - B -> A + (-B) if B is easily negatable. */
10040 /* Avoid this transformation if B is a positive REAL_CST. */
10048 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10049 one. Make sure the type is not saturating and has the signedness of
10050 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10051 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10058 {
10062 }
10068 {
10069 /* Transform x * -C into -x * C if x is easily negatable. */
10084 {
10087 "occur when simplifying "
10089 WARN_STRICT_OVERFLOW_MISC);
10091 }
10093 /* Optimize z * conj(z) for integer complex numbers. */
10100 }
10101 else
10102 {
10103 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10104 This is not the same for NaNs or if signed zeros are
10105 involved. */
10111 {
10114 return
10120 return
10125 }
10127 /* Optimize z * conj(z) for floating point complex numbers.
10128 Guarded by flag_unsafe_math_optimizations as non-finite
10129 imaginary components don't produce scalar results. */
10138 }
10142 /* Canonicalize (X & C1) | C2. */
10146 {
10151 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10159 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10161 {
10164 }
10166 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10167 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10168 mode which allows further optimizations. */
10173 {
10178 {
10181 }
10182 }
10185 {
10190 }
10191 }
10193 /* See if this can be simplified into a rotate first. If that
10194 is unsuccessful continue in the association code. */
10198 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10206 /* See if this can be simplified into a rotate first. If that
10207 is unsuccessful continue in the association code. */
10211 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10216 {
10217 tree tem2;
10224 }
10225 /* Fold ~X & 1 as (X & 1) == 0. */
10229 {
10230 tree tem2;
10237 }
10238 /* Fold !X & 1 as X == 0. */
10241 {
10245 }
10247 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10248 multiple of 1 << CST. */
10250 {
10257 }
10259 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10260 bits from CST2. */
10264 {
10266 wide_int masked
10273 {
10274 /* Avoid the transform if arg1 is a mask of some
10275 mode which allows further optimizations. */
10282 }
10283 }
10285 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10288 {
10293 return
10295 }
10300 /* Don't touch a floating-point divide by zero unless the mode
10301 of the constant can represent infinity. */
10307 /* (-A) / (-B) -> A / B */
10319 /* Fall through */
10322 /* Simplify A / (B << N) where A and B are positive and B is
10323 a power of 2, to A >> (N + log2(B)). */
10328 {
10331 {
10339 WARN_STRICT_OVERFLOW_MISC);
10345 }
10346 }
10348 /* Fall through */
10356 /* Convert -A / -B to A / B when the type is signed and overflow is
10357 undefined. */
10361 {
10364 "when distributing negation across "
10366 WARN_STRICT_OVERFLOW_MISC);
10371 }
10375 {
10378 "when distributing negation across "
10380 WARN_STRICT_OVERFLOW_MISC);
10385 }
10387 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10388 operation, EXACT_DIV_EXPR.
10390 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10391 At one time others generated faster code, it's not clear if they do
10392 after the last round to changes to the DIV code in expmed.c. */
10403 {
10407 WARN_STRICT_OVERFLOW_MISC);
10409 }
10421 {
10425 WARN_STRICT_OVERFLOW_MISC);
10427 }
10435 /* Since negative shift count is not well-defined,
10436 don't try to compute it in the compiler. */
10442 /* If we have a rotate of a bit operation with the rotate count and
10443 the second operand of the bit operation both constant,
10444 permute the two operations. */
10450 {
10458 }
10460 /* Two consecutive rotates adding up to the some integer
10461 multiple of the precision of the type can be ignored. */
10477 /* Note that the operands of this must be ints
10478 and their values must be 0 or 1.
10479 ("true" is a fixed value perhaps depending on the language.) */
10480 /* If first arg is constant zero, return it. */
10483 /* FALLTHRU */
10485 /* If either arg is constant true, drop it. */
10489 /* Preserve sequence points. */
10492 /* If second arg is constant zero, result is zero, but first arg
10493 must be evaluated. */
10496 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10497 case will be handled here. */
10501 /* !X && X is always false. */
10505 /* X && !X is always false. */
10510 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10511 means A >= Y && A != MAX, but in this case we know that
10512 A < X <= MAX. */
10516 {
10524 }
10533 /* Note that the operands of this must be ints
10534 and their values must be 0 or true.
10535 ("true" is a fixed value perhaps depending on the language.) */
10536 /* If first arg is constant true, return it. */
10539 /* FALLTHRU */
10541 /* If either arg is constant zero, drop it. */
10545 /* Preserve sequence points. */
10548 /* If second arg is constant true, result is true, but we must
10549 evaluate first arg. */
10552 /* Likewise for first arg, but note this only occurs here for
10553 TRUTH_OR_EXPR. */
10557 /* !X || X is always true. */
10561 /* X || !X is always true. */
10566 /* (X && !Y) || (!X && Y) is X ^ Y */
10569 {
10586 }
10595 /* If the second arg is constant zero, drop it. */
10598 /* If the second arg is constant true, this is a logical inversion. */
10600 {
10603 }
10604 /* Identical arguments cancel to zero. */
10608 /* !X ^ X is always true. */
10613 /* X ^ !X is always true. */
10629 /* bool_var != 1 becomes !bool_var. */
10636 /* bool_var == 0 becomes !bool_var. */
10643 /* !exp != 0 becomes !exp */
10648 /* If this is an EQ or NE comparison with zero and ARG0 is
10649 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10650 two operations, but the latter can be done in one less insn
10651 on machines that have only two-operand insns or on which a
10652 constant cannot be the first operand. */
10655 {
10660 {
10667 arg1);
10668 }
10671 {
10678 arg1);
10679 }
10680 }
10682 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10683 C1 is a valid shift constant, and C2 is a power of two, i.e.
10684 a single bit. */
10688 == INTEGER_CST
10691 {
10696 /* Check for a valid shift count. */
10698 {
10702 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10703 can be rewritten as (X & (C2 << C1)) != 0. */
10705 {
10710 }
10711 /* Otherwise, for signed (arithmetic) shifts,
10712 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10713 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10717 /* Otherwise, of unsigned (logical) shifts,
10718 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10719 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10720 else
10724 arg000);
10725 }
10726 }
10728 /* If this is a comparison of a field, we may be able to simplify it. */
10731 /* Handle the constant case even without -O
10732 to make sure the warnings are given. */
10734 {
10738 }
10740 /* Optimize comparisons of strlen vs zero to a compare of the
10741 first character of the string vs zero. To wit,
10742 strlen(ptr) == 0 => *ptr == 0
10743 strlen(ptr) != 0 => *ptr != 0
10744 Other cases should reduce to one of these two (or a constant)
10745 due to the return value of strlen being unsigned. */
10747 {
10755 {
10756 tree ptrtype
10758 TYPE_QUAL_CONST));
10764 }
10765 }
10767 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10768 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10772 {
10777 {
10779 {
10782 }
10785 }
10786 }
10788 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10789 (X & C) == 0 when C is a single bit. */
10794 {
10801 arg1));
10802 }
10804 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10805 constant C is a power of two, i.e. a single bit. */
10812 {
10816 }
10818 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10819 when is C is a power of two, i.e. a single bit. */
10826 {
10832 }
10836 {
10839 }
10841 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10844 {
10852 {
10858 }
10860 {
10866 }
10868 {
10874 }
10876 {
10882 }
10883 }
10887 {
10894 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10895 operand_equal_p guarantees no side-effects so we don't need
10896 to use omit_one_operand on Z. */
10900 arg10));
10904 arg11));
10908 arg10));
10912 arg11));
10914 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10917 {
10923 }
10924 }
10926 /* Attempt to simplify equality/inequality comparisons of complex
10927 values. Only lower the comparison if the result is known or
10928 can be simplified to a single scalar comparison. */
10933 {
10938 {
10941 }
10942 else
10943 {
10946 }
10949 {
10952 }
10953 else
10954 {
10957 }
10961 {
10963 {
10968 }
10969 else
10970 {
10975 }
10976 }
10980 {
10982 {
10987 }
10988 else
10989 {
10994 }
10995 }
10996 }
11008 /* Transform comparisons of the form X +- C CMP X. */
11013 {
11018 /* (X - c) > X becomes false. */
11024 /* Likewise (X + c) < X becomes false. */
11030 /* Convert (X - c) <= X to true. */
11037 /* Convert (X + c) >= X to true. */
11043 }
11045 /* If we are comparing an ABS_EXPR with a constant, we can
11046 convert all the cases into explicit comparisons, but they may
11047 well not be faster than doing the ABS and one comparison.
11048 But ABS (X) <= C is a range comparison, which becomes a subtraction
11049 and a comparison, and is probably faster. */
11063 /* Convert ABS_EXPR<x> >= 0 to true. */
11070 {
11073 "when simplifying comparison of "
11075 WARN_STRICT_OVERFLOW_CONDITIONAL);
11078 arg0);
11079 }
11081 /* Convert ABS_EXPR<x> < 0 to false. */
11086 {
11089 "when simplifying comparison of "
11091 WARN_STRICT_OVERFLOW_CONDITIONAL);
11094 arg0);
11095 }
11097 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11098 and similarly for >= into !=. */
11108 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11109 otherwise Y might be >= # of bits in X's type and thus e.g.
11110 (unsigned char) (1 << Y) for Y 15 might be 0.
11111 If the cast is widening, then 1 << Y should have unsigned type,
11112 otherwise if Y is number of bits in the signed shift type minus 1,
11113 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11114 31 might be 0xffffffff80000000. */
11125 {
11131 }
11143 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11144 {
11156 }
11161 /* When pedantic, a compound expression can be neither an lvalue
11162 nor an integer constant expression. */
11165 /* Don't let (0, 0) be null pointer constant. */
11171 /* An ASSERT_EXPR should never be passed to fold_binary. */
11177 }
11179 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11180 ((A & N) + B) & M -> (A + B) & M
11181 Similarly if (N & M) == 0,
11182 ((A | N) + B) & M -> (A + B) & M
11183 and for - instead of + (or unary - instead of +)
11184 and/or ^ instead of |.
11185 If B is constant and (B & M) == 0, fold into A & M.
11187 This function is a helper for match.pd patterns. Return non-NULL
11188 type in which the simplified operation should be performed only
11189 if any optimization is possible.
11191 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11192 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11193 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11194 +/-. */
11195 tree
11200 {
11215 wide_int cst0;
11217 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11218 arg1 (M) is == (1LL << cst) - 1.
11219 Store C into PMOP[0] and D into PMOP[1]. */
11226 {
11233 {
11236 }
11239 /* If C or D is of the form (A & N) where
11240 (N & M) == M, or of the form (A | N) or
11241 (A ^ N) where (N & M) == 0, replace it with A. */
11247 /* If C or D is a N where (N & M) == 0, it can be
11248 omitted (replaced with 0). */
11253 /* Similarly, with C - N where (-N & M) == 0. */
11261 }
11263 /* Only build anything new if we optimized one or both arguments above. */
11269 else
11271 }
11273 /* Used by contains_label_[p1]. */
11275 struct contains_label_data
11276 {
11279 };
11281 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11282 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11283 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11285 static tree
11287 {
11290 {
11301 {
11309 }
11318 }
11319 }
11321 /* Return whether the sub-tree ST contains a label which is accessible from
11322 outside the sub-tree. */
11324 static bool
11326 {
11330 }
11332 /* Fold a ternary expression of code CODE and type TYPE with operands
11333 OP0, OP1, and OP2. Return the folded expression if folding is
11334 successful. Otherwise, return NULL_TREE. */
11336 tree
11339 {
11340 tree tem;
11347 /* If this is a commutative operation, and OP0 is a constant, move it
11348 to OP1 to reduce the number of tests below. */
11357 /* Strip any conversions that don't change the mode. This is safe
11358 for every expression, except for a comparison expression because
11359 its signedness is derived from its operands. So, in the latter
11360 case, only strip conversions that don't change the signedness.
11362 Note that this is done as an internal manipulation within the
11363 constant folder, in order to find the simplest representation of
11364 the arguments so that their form can be studied. In any cases,
11365 the appropriate type conversions should be put back in the tree
11366 that will get out of the constant folder. */
11368 {
11371 }
11374 {
11377 }
11380 {
11383 }
11386 {
11390 {
11396 }
11401 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11402 so all simple results must be passed through pedantic_non_lvalue. */
11404 {
11407 /* Only optimize constant conditions when the selected branch
11408 has the same type as the COND_EXPR. This avoids optimizing
11409 away "c ? x : throw", where the throw has a void type.
11410 Avoid throwing away that operand which contains label. */
11417 }
11419 {
11426 {
11429 {
11437 }
11442 }
11443 }
11445 /* If we have A op B ? A : C, we may be able to convert this to a
11446 simpler expression, depending on the operation and the values
11447 of B and C. Signed zeros prevent all of these transformations,
11448 for reasons given above each one.
11450 Also try swapping the arguments and inverting the conditional. */
11454 {
11458 }
11463 {
11467 {
11471 }
11472 }
11474 /* If the second operand is simpler than the third, swap them
11475 since that produces better jump optimization results. */
11478 {
11480 /* See if this can be inverted. If it can't, possibly because
11481 it was a floating-point inequality comparison, don't do
11482 anything. */
11486 }
11488 /* Convert A ? 1 : 0 to simply A. */
11493 /* If we try to convert OP0 to our type, the
11494 call to fold will try to move the conversion inside
11495 a COND, which will recurse. In that case, the COND_EXPR
11496 is probably the best choice, so leave it alone. */
11500 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11501 over COND_EXPR in cases such as floating point comparisons. */
11510 arg0)));
11512 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11517 {
11518 /* sign_bit_p looks through both zero and sign extensions,
11519 but for this optimization only sign extensions are
11520 usable. */
11523 {
11526 {
11529 }
11531 }
11532 /* sign_bit_p only checks ARG1 bits within A's precision.
11533 If <sign bit of A> has wider type than A, bits outside
11534 of A's precision in <sign bit of A> need to be checked.
11535 If they are all 0, this optimization needs to be done
11536 in unsigned A's type, if they are all 1 in signed A's type,
11537 otherwise this can't be done. */
11543 {
11545 tree tem_type;
11558 {
11561 }
11563 {
11566 }
11567 else
11569 }
11572 return
11578 arg1)));
11579 }
11581 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11582 already handled above. */
11587 {
11597 op1);
11598 }
11600 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11601 is probably obsolete because the first operand should be a
11602 truth value (that's why we have the two cases above), but let's
11603 leave it in until we can confirm this for all front-ends. */
11611 /* operand_equal_p compares just value, not precision, so e.g.
11612 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
11613 second operand 32-bit -128, which is not a power of two (or vice
11614 versa. */
11621 /* Disable the transformations below for vectors, since
11622 fold_binary_op_with_conditional_arg may undo them immediately,
11623 yielding an infinite loop. */
11627 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11636 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11641 {
11643 /* Only perform transformation if ARG0 is easily inverted. */
11647 ? BIT_IOR_EXPR
11650 op1);
11651 }
11653 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11658 {
11660 /* Only perform transformation if ARG0 is easily inverted. */
11666 op2);
11667 }
11669 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11681 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11682 of fold_ternary on them. */
11692 {
11703 {
11708 {
11710 {
11715 }
11721 }
11722 }
11723 }
11725 /* On constants we can use native encode/interpret to constant
11726 fold (nearly) all BIT_FIELD_REFs. */
11732 {
11735 /* Limit us to a reasonable amount of work. To relax the
11736 other limitations we need bit-shifting of the buffer
11737 and rounding up the size. */
11741 {
11743 unsigned HOST_WIDE_INT len
11748 {
11753 }
11754 }
11755 }
11761 {
11762 /* Build a vector of integers from the tree mask. */
11763 vec_perm_builder builder;
11767 /* Create a vec_perm_indices for the integer vector. */
11772 /* Check for cases that fold to OP0 or OP1 in their original
11773 element order. */
11780 {
11784 {
11787 }
11788 }
11794 {
11798 }
11802 /* Generate a canonical form of the selector. */
11804 {
11805 /* Some targets are deficient and fail to expand a single
11806 argument permutation while still allowing an equivalent
11807 2-argument version. */
11811 else
11812 {
11816 else
11817 /* Not directly supported with either encoding,
11818 so use the preferred form. */
11820 }
11822 }
11826 }
11830 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11833 {
11839 wide_int tem2
11843 }
11848 {
11850 unsigned HOST_WIDE_INT elsize
11853 {
11859 {
11865 }
11866 }
11867 }
11873 }
11875 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11876 of an array (or vector). */
11878 tree
11880 {
11885 {
11888 {
11889 /* Static constructors for variably sized objects makes no sense. */
11893 }
11894 }
11905 offset_int max_index;
11910 {
11911 /* Array constructor might explicitly set index, or specify a range,
11912 or leave index NULL meaning that it is next index after previous
11913 one. */
11915 {
11918 else
11919 {
11923 }
11924 }
11925 else
11926 {
11932 }
11934 /* Do we have match? */
11938 }
11940 }
11942 /* Perform constant folding and related simplification of EXPR.
11943 The related simplifications include x*1 => x, x*0 => 0, etc.,
11944 and application of the associative law.
11945 NOP_EXPR conversions may be removed freely (as long as we
11946 are careful not to change the type of the overall expression).
11947 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11948 but we can constant-fold them if they have constant operands. */
11950 #ifdef ENABLE_FOLD_CHECKING
11951 # define fold(x) fold_1 (x)
11953 static
11954 #endif
11955 tree
11957 {
11961 tree tem;
11964 /* Return right away if a constant. */
11968 /* CALL_EXPR-like objects with variable numbers of operands are
11969 treated specially. */
11971 {
11973 {
11976 }
11978 }
11981 {
11986 {
12004 }
12005 }
12008 {
12010 {
12017 {
12022 }
12025 }
12027 /* Return a VECTOR_CST if possible. */
12029 {
12035 tree val;
12041 }
12049 }
12051 #ifdef ENABLE_FOLD_CHECKING
12052 #undef fold
12059 /* When --enable-checking=fold, compute a digest of expr before
12060 and after actual fold call to see if fold did not accidentally
12061 change original expr. */
12063 tree
12065 {
12066 tree ret;
12086 }
12088 void
12090 {
12101 }
12103 static void
12105 {
12107 }
12109 static void
12112 {
12118 recursive_label:
12128 {
12129 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12137 }
12145 {
12146 /* Allow these fields to be modified. */
12147 tree tmp;
12158 {
12161 }
12162 }
12164 {
12165 /* Allow TREE_NO_WARNING to be set. Perhaps we shouldn't allow that
12166 and change builtins.c etc. instead - see PR89543. */
12172 }
12183 {
12186 {
12202 }
12206 {
12219 }
12236 {
12242 }
12245 {
12247 {
12250 }
12252 }
12263 {
12266 }
12276 }
12277 }
12279 /* Helper function for outputting the checksum of a tree T. When
12280 debugging with gdb, you can "define mynext" to be "next" followed
12281 by "call debug_fold_checksum (op0)", then just trace down till the
12282 outputs differ. */
12284 DEBUG_FUNCTION void
12286 {
12301 }
12303 #endif
12305 /* Fold a unary tree expression with code CODE of type TYPE with an
12306 operand OP0. LOC is the location of the resulting expression.
12307 Return a folded expression if successful. Otherwise, return a tree
12308 expression with code CODE of type TYPE with an operand OP0. */
12310 tree
12313 {
12314 tree tem;
12315 #ifdef ENABLE_FOLD_CHECKING
12324 #endif
12330 #ifdef ENABLE_FOLD_CHECKING
12337 #endif
12339 }
12341 /* Fold a binary tree expression with code CODE of type TYPE with
12342 operands OP0 and OP1. LOC is the location of the resulting
12343 expression. Return a folded expression if successful. Otherwise,
12344 return a tree expression with code CODE of type TYPE with operands
12345 OP0 and OP1. */
12347 tree
12350 MEM_STAT_DECL)
12351 {
12352 tree tem;
12353 #ifdef ENABLE_FOLD_CHECKING
12370 #endif
12376 #ifdef ENABLE_FOLD_CHECKING
12391 #endif
12393 }
12395 /* Fold a ternary tree expression with code CODE of type TYPE with
12396 operands OP0, OP1, and OP2. Return a folded expression if
12397 successful. Otherwise, return a tree expression with code CODE of
12398 type TYPE with operands OP0, OP1, and OP2. */
12400 tree
12403 {
12404 tree tem;
12405 #ifdef ENABLE_FOLD_CHECKING
12429 #endif
12436 #ifdef ENABLE_FOLD_CHECKING
12459 #endif
12461 }
12463 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12464 arguments in ARGARRAY, and a null static chain.
12465 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12466 of type TYPE from the given operands as constructed by build_call_array. */
12468 tree
12471 {
12472 tree tem;
12473 #ifdef ENABLE_FOLD_CHECKING
12492 #endif
12498 #ifdef ENABLE_FOLD_CHECKING
12514 #endif
12516 }
12518 /* Perform constant folding and related simplification of initializer
12519 expression EXPR. These behave identically to "fold_buildN" but ignore
12520 potential run-time traps and exceptions that fold must preserve. */
12522 #define START_FOLD_INIT \
12523 int saved_signaling_nans = flag_signaling_nans;\
12524 int saved_trapping_math = flag_trapping_math;\
12525 int saved_rounding_math = flag_rounding_math;\
12526 int saved_trapv = flag_trapv;\
12527 int saved_folding_initializer = folding_initializer;\
12528 flag_signaling_nans = 0;\
12529 flag_trapping_math = 0;\
12530 flag_rounding_math = 0;\
12531 flag_trapv = 0;\
12532 folding_initializer = 1;
12534 #define END_FOLD_INIT \
12535 flag_signaling_nans = saved_signaling_nans;\
12536 flag_trapping_math = saved_trapping_math;\
12537 flag_rounding_math = saved_rounding_math;\
12538 flag_trapv = saved_trapv;\
12539 folding_initializer = saved_folding_initializer;
12541 tree
12544 {
12545 tree result;
12546 START_FOLD_INIT;
12550 END_FOLD_INIT;
12552 }
12554 tree
12557 {
12558 tree result;
12559 START_FOLD_INIT;
12563 END_FOLD_INIT;
12565 }
12567 tree
12570 {
12571 tree result;
12572 START_FOLD_INIT;
12576 END_FOLD_INIT;
12578 }
12580 #undef START_FOLD_INIT
12581 #undef END_FOLD_INIT
12583 /* Determine if first argument is a multiple of second argument. Return 0 if
12584 it is not, or we cannot easily determined it to be.
12586 An example of the sort of thing we care about (at this point; this routine
12587 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12588 fold cases do now) is discovering that
12590 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12592 is a multiple of
12594 SAVE_EXPR (J * 8)
12596 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12598 This code also handles discovering that
12600 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12602 is a multiple of 8 so we don't have to worry about dealing with a
12603 possible remainder.
12605 Note that we *look* inside a SAVE_EXPR only to determine how it was
12606 calculated; it is not safe for fold to do much of anything else with the
12607 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12608 at run time. For example, the latter example above *cannot* be implemented
12609 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12610 evaluation time of the original SAVE_EXPR is not necessarily the same at
12611 the time the new expression is evaluated. The only optimization of this
12612 sort that would be valid is changing
12614 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12616 divided by 8 to
12618 SAVE_EXPR (I) * SAVE_EXPR (J)
12620 (where the same SAVE_EXPR (J) is used in the original and the
12621 transformed version). */
12623 int
12625 {
12636 {
12638 /* Bitwise and provides a power of two multiple. If the mask is
12639 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12647 {
12653 {
12656 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12658 {
12662 {
12665 }
12666 }
12668 }
12669 }
12674 /* It is impossible to prove if op0 - op1 is multiple of bottom
12675 precisely, so be conservative here checking if both op0 and op1
12676 are multiple of bottom. Note we check the second operand first
12677 since it's usually simpler. */
12682 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12683 as op0 - 3 if the expression has unsigned type. For example,
12684 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12694 {
12696 /* const_binop may not detect overflow correctly,
12697 so check for it explicitly here. */
12705 }
12709 /* Can't handle conversions from non-integral or wider integral type. */
12715 /* fall through */
12732 SIGNED);
12738 {
12741 /* Check for special cases to see if top is defined as multiple
12742 of bottom:
12744 top = (X & ~(bottom - 1) ; bottom is power of 2
12746 or
12748 Y = X % bottom
12749 top = X - Y. */
12768 }
12770 /* fall through */
12778 }
12779 }
12781 #define tree_expr_nonnegative_warnv_p(X, Y) \
12784 #define RECURSE(X) \
12785 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12787 /* Return true if CODE or TYPE is known to be non-negative. */
12789 static bool
12791 {
12794 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12795 have a signed:1 type (where the value is -1 and 0). */
12798 }
12800 /* Return true if (CODE OP0) is known to be non-negative. If the return
12801 value is based on the assumption that signed overflow is undefined,
12802 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12803 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12805 bool
12808 {
12813 {
12815 /* We can't return 1 if flag_wrapv is set because
12816 ABS_EXPR<INT_MIN> = INT_MIN. */
12820 {
12823 }
12831 CASE_CONVERT:
12832 {
12837 {
12841 {
12845 }
12846 }
12848 {
12854 }
12855 }
12860 }
12862 /* We don't know sign of `t', so be conservative and return false. */
12864 }
12866 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12867 value is based on the assumption that signed overflow is undefined,
12868 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12869 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12871 bool
12875 {
12880 {
12886 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12887 both unsigned and at least 2 bits shorter than the result. */
12891 {
12896 {
12900 }
12901 }
12906 {
12907 /* x * x is always non-negative for floating point x
12908 or without overflow. */
12911 {
12916 }
12917 }
12919 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12920 both unsigned and their total bits is shorter than the result. */
12924 {
12943 {
12953 }
12954 }
12981 }
12983 /* We don't know sign of `t', so be conservative and return false. */
12985 }
12987 /* Return true if T is known to be non-negative. If the return
12988 value is based on the assumption that signed overflow is undefined,
12989 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12990 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12992 bool
12994 {
12999 {
13013 /* Limit the depth of recursion to avoid quadratic behavior.
13014 This is expected to catch almost all occurrences in practice.
13015 If this code misses important cases that unbounded recursion
13016 would not, passes that need this information could be revised
13017 to provide it through dataflow propagation. */
13025 }
13026 }
13028 /* Return true if T is known to be non-negative. If the return
13029 value is based on the assumption that signed overflow is undefined,
13030 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13031 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13033 bool
13036 {
13038 {
13039 CASE_CFN_ACOS:
13040 CASE_CFN_ACOSH:
13041 CASE_CFN_CABS:
13042 CASE_CFN_COSH:
13043 CASE_CFN_ERFC:
13044 CASE_CFN_EXP:
13045 CASE_CFN_EXP10:
13046 CASE_CFN_EXP2:
13047 CASE_CFN_FABS:
13048 CASE_CFN_FDIM:
13049 CASE_CFN_HYPOT:
13050 CASE_CFN_POW10:
13051 CASE_CFN_FFS:
13052 CASE_CFN_PARITY:
13053 CASE_CFN_POPCOUNT:
13054 CASE_CFN_CLZ:
13055 CASE_CFN_CLRSB:
13058 /* Always true. */
13061 CASE_CFN_SQRT:
13062 CASE_CFN_SQRT_FN:
13063 /* sqrt(-0.0) is -0.0. */
13068 CASE_CFN_ASINH:
13069 CASE_CFN_ATAN:
13070 CASE_CFN_ATANH:
13071 CASE_CFN_CBRT:
13072 CASE_CFN_CEIL:
13073 CASE_CFN_CEIL_FN:
13074 CASE_CFN_ERF:
13075 CASE_CFN_EXPM1:
13076 CASE_CFN_FLOOR:
13077 CASE_CFN_FLOOR_FN:
13078 CASE_CFN_FMOD:
13079 CASE_CFN_FREXP:
13080 CASE_CFN_ICEIL:
13081 CASE_CFN_IFLOOR:
13082 CASE_CFN_IRINT:
13083 CASE_CFN_IROUND:
13084 CASE_CFN_LCEIL:
13085 CASE_CFN_LDEXP:
13086 CASE_CFN_LFLOOR:
13087 CASE_CFN_LLCEIL:
13088 CASE_CFN_LLFLOOR:
13089 CASE_CFN_LLRINT:
13090 CASE_CFN_LLROUND:
13091 CASE_CFN_LRINT:
13092 CASE_CFN_LROUND:
13093 CASE_CFN_MODF:
13094 CASE_CFN_NEARBYINT:
13095 CASE_CFN_NEARBYINT_FN:
13096 CASE_CFN_RINT:
13097 CASE_CFN_RINT_FN:
13098 CASE_CFN_ROUND:
13099 CASE_CFN_ROUND_FN:
13100 CASE_CFN_SCALB:
13101 CASE_CFN_SCALBLN:
13102 CASE_CFN_SCALBN:
13103 CASE_CFN_SIGNBIT:
13104 CASE_CFN_SIGNIFICAND:
13105 CASE_CFN_SINH:
13106 CASE_CFN_TANH:
13107 CASE_CFN_TRUNC:
13108 CASE_CFN_TRUNC_FN:
13109 /* True if the 1st argument is nonnegative. */
13112 CASE_CFN_FMAX:
13113 CASE_CFN_FMAX_FN:
13114 /* True if the 1st OR 2nd arguments are nonnegative. */
13117 CASE_CFN_FMIN:
13118 CASE_CFN_FMIN_FN:
13119 /* True if the 1st AND 2nd arguments are nonnegative. */
13122 CASE_CFN_COPYSIGN:
13123 CASE_CFN_COPYSIGN_FN:
13124 /* True if the 2nd argument is nonnegative. */
13127 CASE_CFN_POWI:
13128 /* True if the 1st argument is nonnegative or the second
13129 argument is an even integer. */
13135 CASE_CFN_POW:
13136 /* True if the 1st argument is nonnegative or the second
13137 argument is an even integer valued real. */
13139 {
13140 REAL_VALUE_TYPE c;
13141 HOST_WIDE_INT n;
13146 {
13147 REAL_VALUE_TYPE cint;
13151 }
13152 }
13157 }
13159 }
13161 /* Return true if T is known to be non-negative. If the return
13162 value is based on the assumption that signed overflow is undefined,
13163 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13164 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13166 static bool
13168 {
13174 {
13176 {
13180 /* If the initializer is non-void, then it's a normal expression
13181 that will be assigned to the slot. */
13185 /* Otherwise, the initializer sets the slot in some way. One common
13186 way is an assignment statement at the end of the initializer. */
13188 {
13196 else
13198 }
13204 }
13207 {
13213 arg0,
13214 arg1,
13216 }
13229 }
13230 }
13232 #undef RECURSE
13233 #undef tree_expr_nonnegative_warnv_p
13235 /* Return true if T is known to be non-negative. If the return
13236 value is based on the assumption that signed overflow is undefined,
13237 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13238 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13240 bool
13242 {
13249 {
13271 }
13274 {
13300 }
13301 }
13303 /* Return true if `t' is known to be non-negative. Handle warnings
13304 about undefined signed overflow. */
13306 bool
13308 {
13315 "determining that expression is always "
13317 WARN_STRICT_OVERFLOW_MISC);
13319 }
13322 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13323 For floating point we further ensure that T is not denormal.
13324 Similar logic is present in nonzero_address in rtlanal.h.
13326 If the return value is based on the assumption that signed overflow
13327 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13328 change *STRICT_OVERFLOW_P. */
13330 bool
13333 {
13335 {
13338 strict_overflow_p);
13341 {
13347 strict_overflow_p));
13348 }
13353 strict_overflow_p);
13357 }
13360 }
13362 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13363 For floating point we further ensure that T is not denormal.
13364 Similar logic is present in nonzero_address in rtlanal.h.
13366 If the return value is based on the assumption that signed overflow
13367 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13368 change *STRICT_OVERFLOW_P. */
13370 bool
13372 tree type,
13373 tree op0,
13375 {
13378 {
13382 {
13383 /* With the presence of negative values it is hard
13384 to say something. */
13391 /* One of operands must be positive and the other non-negative. */
13392 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13393 overflows, on a twos-complement machine the sum of two
13394 nonnegative numbers can never be zero. */
13396 strict_overflow_p)
13398 strict_overflow_p));
13399 }
13404 {
13406 strict_overflow_p)
13408 strict_overflow_p))
13409 {
13412 }
13413 }
13422 {
13425 }
13432 {
13436 /* When both operands are nonzero, then MAX must be too. */
13438 strict_overflow_p))
13441 /* MAX where operand 0 is positive is positive. */
13443 strict_overflow_p);
13444 }
13445 /* MAX where operand 1 is positive is positive. */
13450 {
13454 }
13459 strict_overflow_p)
13461 strict_overflow_p));
13465 }
13468 }
13470 /* Return true when T is an address and is known to be nonzero.
13471 For floating point we further ensure that T is not denormal.
13472 Similar logic is present in nonzero_address in rtlanal.h.
13474 If the return value is based on the assumption that signed overflow
13475 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13476 change *STRICT_OVERFLOW_P. */
13478 bool
13480 {
13483 {
13488 {
13500 /* For objects in symbol table check if we know they are non-zero.
13501 Don't do anything for variables and functions before symtab is built;
13502 it is quite possible that they will be declared weak later. */
13507 /* Constants are never weak. */
13512 }
13520 {
13524 }
13534 }
13536 }
13538 #define integer_valued_real_p(X) \
13541 #define RECURSE(X) \
13542 ((integer_valued_real_p) (X, depth + 1))
13544 /* Return true if the floating point result of (CODE OP0) has an
13545 integer value. We also allow +Inf, -Inf and NaN to be considered
13546 integer values. Return false for signaling NaN.
13548 DEPTH is the current nesting depth of the query. */
13550 bool
13552 {
13554 {
13561 CASE_CONVERT:
13562 {
13569 }
13573 }
13575 }
13577 /* Return true if the floating point result of (CODE OP0 OP1) has an
13578 integer value. We also allow +Inf, -Inf and NaN to be considered
13579 integer values. Return false for signaling NaN.
13581 DEPTH is the current nesting depth of the query. */
13583 bool
13585 {
13587 {
13597 }
13599 }
13601 /* Return true if the floating point result of calling FNDECL with arguments
13602 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13603 considered integer values. Return false for signaling NaN. If FNDECL
13604 takes fewer than 2 arguments, the remaining ARGn are null.
13606 DEPTH is the current nesting depth of the query. */
13608 bool
13610 {
13612 {
13613 CASE_CFN_CEIL:
13614 CASE_CFN_CEIL_FN:
13615 CASE_CFN_FLOOR:
13616 CASE_CFN_FLOOR_FN:
13617 CASE_CFN_NEARBYINT:
13618 CASE_CFN_NEARBYINT_FN:
13619 CASE_CFN_RINT:
13620 CASE_CFN_RINT_FN:
13621 CASE_CFN_ROUND:
13622 CASE_CFN_ROUND_FN:
13623 CASE_CFN_TRUNC:
13624 CASE_CFN_TRUNC_FN:
13627 CASE_CFN_FMIN:
13628 CASE_CFN_FMIN_FN:
13629 CASE_CFN_FMAX:
13630 CASE_CFN_FMAX_FN:
13635 }
13637 }
13639 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13640 has an integer value. We also allow +Inf, -Inf and NaN to be
13641 considered integer values. Return false for signaling NaN.
13643 DEPTH is the current nesting depth of the query. */
13645 bool
13647 {
13649 {
13657 /* Limit the depth of recursion to avoid quadratic behavior.
13658 This is expected to catch almost all occurrences in practice.
13659 If this code misses important cases that unbounded recursion
13660 would not, passes that need this information could be revised
13661 to provide it through dataflow propagation. */
13665 depth));
13669 }
13671 }
13673 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13674 has an integer value. We also allow +Inf, -Inf and NaN to be
13675 considered integer values. Return false for signaling NaN.
13677 DEPTH is the current nesting depth of the query. */
13679 static bool
13681 {
13683 {
13694 }
13696 }
13698 #undef RECURSE
13699 #undef integer_valued_real_p
13701 /* Return true if the floating point expression T has an integer value.
13702 We also allow +Inf, -Inf and NaN to be considered integer values.
13703 Return false for signaling NaN.
13705 DEPTH is the current nesting depth of the query. */
13707 bool
13709 {
13717 {
13733 }
13736 {
13742 {
13751 }
13755 }
13756 }
13758 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13759 attempt to fold the expression to a constant without modifying TYPE,
13760 OP0 or OP1.
13762 If the expression could be simplified to a constant, then return
13763 the constant. If the expression would not be simplified to a
13764 constant, then return NULL_TREE. */
13766 tree
13768 {
13771 }
13773 /* Given the components of a unary expression CODE, TYPE and OP0,
13774 attempt to fold the expression to a constant without modifying
13775 TYPE or OP0.
13777 If the expression could be simplified to a constant, then return
13778 the constant. If the expression would not be simplified to a
13779 constant, then return NULL_TREE. */
13781 tree
13783 {
13786 }
13788 /* If EXP represents referencing an element in a constant string
13789 (either via pointer arithmetic or array indexing), return the
13790 tree representing the value accessed, otherwise return NULL. */
13792 tree
13794 {
13798 {
13800 tree index;
13801 tree string;
13806 else
13807 {
13811 /* Optimize the special-case of a zero lower bound.
13813 We convert the low_bound to sizetype to avoid some problems
13814 with constant folding. (E.g. suppose the lower bound is 1,
13815 and its mode is QI. Without the conversion,l (ARRAY
13816 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13817 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13823 }
13825 scalar_int_mode char_mode;
13837 }
13839 }
13841 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13842 an integer constant, real, or fixed-point constant.
13844 TYPE is the type of the result. */
13846 static tree
13848 {
13852 {
13858 {
13859 FIXED_VALUE_TYPE f;
13864 /* Propagate overflow flags. */
13868 }
13872 {
13879 }
13882 }
13885 }
13887 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13888 an integer constant or real constant.
13890 TYPE is the type of the result. */
13892 tree
13894 {
13898 {
13900 {
13901 /* If the value is unsigned or non-negative, then the absolute value
13902 is the same as the ordinary value. */
13906 ;
13908 /* If the value is negative, then the absolute value is
13909 its negation. */
13910 else
13913 /* Force to the destination type, set TREE_OVERFLOW for signed
13914 TYPE only. */
13916 }
13922 else
13928 }
13931 }
13933 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13934 constant. TYPE is the type of the result. */
13936 static tree
13938 {
13942 }
13944 /* Given CODE, a relational operator, the target type, TYPE and two
13945 constant operands OP0 and OP1, return the result of the
13946 relational operation. If the result is not a compile time
13947 constant, then return NULL_TREE. */
13949 static tree
13951 {
13954 /* From here on, the only cases we handle are when the result is
13955 known to be a constant. */
13958 {
13962 /* Handle the cases where either operand is a NaN. */
13964 {
13966 {
13994 }
13997 }
14000 }
14003 {
14007 }
14009 /* Handle equality/inequality of complex constants. */
14011 {
14022 else
14024 }
14027 {
14029 {
14030 /* Have vector comparison with scalar boolean result. */
14038 {
14046 }
14048 }
14049 tree_vector_builder elts;
14054 {
14067 }
14070 }
14072 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14074 To compute GT, swap the arguments and do LT.
14075 To compute GE, do LT and invert the result.
14076 To compute LE, swap the arguments, do LT and invert the result.
14077 To compute NE, do EQ and invert the result.
14079 Therefore, the code below must handle only EQ and LT. */
14082 {
14085 }
14087 /* Note that it is safe to invert for real values here because we
14088 have already handled the one case that it matters. */
14092 {
14095 }
14097 /* Compute a result for LT or EQ if args permit;
14098 Otherwise return T. */
14100 {
14103 else
14105 }
14106 else
14112 }
14114 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14115 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14116 itself. */
14118 tree
14120 {
14121 /* If the expression does not have side effects then we don't have to wrap
14122 it with a cleanup point expression. */
14126 /* If the expression is a return, check to see if the expression inside the
14127 return has no side effects or the right hand side of the modify expression
14128 inside the return. If either don't have side effects set we don't need to
14129 wrap the expression in a cleanup point expression. Note we don't check the
14130 left hand side of the modify because it should always be a return decl. */
14132 {
14139 }
14142 }
14144 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14145 of an indirection through OP0, or NULL_TREE if no simplification is
14146 possible. */
14148 tree
14150 {
14152 tree subtype;
14153 poly_uint64 const_op01;
14162 {
14166 /* *&CONST_DECL -> to the value of the const decl. */
14169 /* *&p => p; make sure to handle *&"str"[cst] here. */
14171 {
14175 else
14177 }
14178 /* *(foo *)&fooarray => fooarray[0] */
14181 && (!in_gimple_form
14183 {
14193 }
14194 /* *(foo *)&complexfoo => __real__ complexfoo */
14198 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14201 {
14205 index);
14206 }
14207 }
14211 {
14217 {
14218 tree op00type;
14222 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14225 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14226 but we want to treat offsets with MSB set as negative.
14227 For the code below negative offsets are invalid and
14228 TYPE_SIZE of the element is something unsigned, so
14229 check whether op01 fits into poly_int64, which implies
14230 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14231 then just use poly_uint64 because we want to treat the
14232 value as unsigned. */
14234 {
14236 poly_uint64 max_offset
14240 {
14245 }
14246 }
14247 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14250 {
14252 const_op01))
14254 }
14255 /* ((foo *)&fooarray)[1] => fooarray[1] */
14258 {
14267 {
14272 }
14273 }
14274 }
14275 }
14277 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14280 && (!in_gimple_form
14282 {
14283 tree type_domain;
14293 NULL_TREE);
14294 }
14297 }
14299 /* Builds an expression for an indirection through T, simplifying some
14300 cases. */
14302 tree
14304 {
14312 }
14314 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14316 tree
14318 {
14323 else
14325 }
14327 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14328 whose result is ignored. The type of the returned tree need not be
14329 the same as the original expression. */
14331 tree
14333 {
14339 {
14350 else
14356 {
14372 }
14377 }
14378 }
14380 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14382 tree
14384 {
14390 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14391 have to do anything. Only do this when we are not given a const,
14392 because in that case, this check is more expensive than just
14393 doing it. */
14395 {
14400 }
14402 /* If divisor is a power of two, simplify this to bit manipulation. */
14404 {
14406 {
14420 }
14421 else
14422 {
14423 tree t;
14429 }
14430 }
14431 else
14432 {
14437 }
14440 }
14442 /* Likewise, but round down. */
14444 tree
14446 {
14453 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14454 have to do anything. Only do this when we are not given a const,
14455 because in that case, this check is more expensive than just
14456 doing it. */
14458 {
14463 }
14465 /* If divisor is a power of two, simplify this to bit manipulation. */
14467 {
14468 tree t;
14472 }
14473 else
14474 {
14479 }
14482 }
14484 /* Returns the pointer to the base of the object addressed by EXP and
14485 extracts the information about the offset of the access, storing it
14486 to PBITPOS and POFFSET. */
14488 static tree
14491 {
14492 tree core;
14493 machine_mode mode;
14495 poly_int64 bitsize;
14499 {
14504 }
14506 {
14512 {
14513 poly_offset_int tem
14519 }
14520 }
14521 else
14522 {
14526 }
14529 }
14531 /* Returns true if addresses of E1 and E2 differ by a constant, false
14532 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14534 bool
14536 {
14551 {
14561 }
14563 {
14564 /* If only one of the offsets is non-constant, the difference cannot
14565 be a constant. */
14567 }
14568 else
14573 }
14575 /* Return OFF converted to a pointer offset type suitable as offset for
14576 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14577 tree
14579 {
14581 }
14583 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14584 tree
14586 {
14589 }
14591 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14592 tree
14594 {
14597 }
14599 /* Return a pointer P to a NUL-terminated string representing the sequence
14600 of constant characters referred to by SRC (or a subsequence of such
14601 characters within it if SRC is a reference to a string plus some
14602 constant offset). If STRLEN is non-null, store the number of bytes
14603 in the string constant including the terminating NUL char. *STRLEN is
14604 typically strlen(P) + 1 in the absence of embedded NUL characters. */
14608 {
14609 tree offset_node;
14610 tree mem_size;
14621 {
14624 else
14626 }
14631 /* STRING_LENGTH is the size of the string literal, including any
14632 embedded NULs. STRING_SIZE is the size of the array the string
14633 literal is stored in. */
14637 /* Ideally this would turn into a gcc_checking_assert over time. */
14643 /* Ideally this would turn into a gcc_checking_assert over time. */
14652 {
14653 /* Compute and store the length of the substring at OFFSET.
14654 All offsets past the initial length refer to null strings. */
14657 else
14659 }
14660 else
14661 {
14663 /* Support only properly NUL-terminated single byte strings. */
14668 }
14671 }
14673 /* Given a tree T, compute which bits in T may be nonzero. */
14675 wide_int
14677 {
14679 {
14697 CASE_CONVERT:
14703 {
14708 }
14712 {
14720 }
14724 {
14732 }
14736 }
14739 }
14741 #if CHECKING_P
14745 /* Helper functions for writing tests of folding trees. */
14747 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14749 static void
14751 tree constant)
14752 {
14754 }
14756 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14757 wrapping WRAPPED_EXPR. */
14759 static void
14761 tree wrapped_expr)
14762 {
14767 }
14769 /* Verify that various arithmetic binary operations are folded
14770 correctly. */
14772 static void
14774 {
14780 /* Addition. */
14781 /* 1 <-- (0 + 1) */
14783 one);
14785 one);
14787 /* (nonlvalue)x <-- (x + 0) */
14789 x);
14791 /* Subtraction. */
14792 /* 0 <-- (x - x) */
14794 zero);
14796 x);
14798 /* Multiplication. */
14799 /* 0 <-- (x * 0) */
14801 zero);
14803 /* (nonlvalue)x <-- (x * 1) */
14805 x);
14806 }
14808 /* Verify that various binary operations on vectors are folded
14809 correctly. */
14811 static void
14813 {
14819 /* Verify equality tests that return a scalar boolean result. */
14825 }
14827 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14829 static void
14831 {
14834 /* This will be 1 if VEC_MODE isn't a vector mode. */
14841 }
14843 /* Run all of the selftests within this file. */
14845 void
14847 {
14851 }