| blob | 640a6ece44e6ca88ae985e55d0e2ffbca67d0853 |
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). */
4319 /* If the number of bits in the reference is the same as the bitsize of
4320 the outer type, then the outer type gives the signedness. Otherwise
4321 (in case of a small bitfield) the signedness is unchanged. */
4325 /* Compute the mask to access the bitfield. */
4334 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4342 }
4344 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4345 bit positions and MASK is SIGNED. */
4347 static int
4349 {
4353 /* If this function returns true when the type of the mask is
4354 UNSIGNED, then there will be errors. In particular see
4355 gcc.c-torture/execute/990326-1.c. There does not appear to be
4356 any documentation paper trail as to why this is so. But the pre
4357 wide-int worked with that restriction and it has been preserved
4358 here. */
4363 }
4365 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4366 represents the sign bit of EXP's type. If EXP represents a sign
4367 or zero extension, also test VAL against the unextended type.
4368 The return value is the (sub)expression whose sign bit is VAL,
4369 or NULL_TREE otherwise. */
4371 tree
4373 {
4375 tree t;
4377 /* Tree EXP must have an integral type. */
4382 /* Tree VAL must be an integer constant. */
4391 /* Handle extension from a narrower type. */
4397 }
4399 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4400 to be evaluated unconditionally. */
4402 static int
4404 {
4405 /* Strip any conversions that don't change the machine mode. */
4414 /* Don't regard global variables as simple. They may be
4415 allocated in ways unknown to the compiler (shared memory,
4416 #pragma weak, etc). */
4419 /* Weakrefs are not safe to be read, since they can be NULL.
4420 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4421 have DECL_WEAK flag set. */
4423 /* Loading a static variable is unduly expensive, but global
4424 registers aren't expensive. */
4426 }
4428 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4429 to be evaluated unconditionally.
4430 I addition to simple_operand_p, we assume that comparisons, conversions,
4431 and logic-not operations are simple, if their operands are simple, too. */
4433 static bool
4435 {
4455 }
4457 \f
4458 /* The following functions are subroutines to fold_range_test and allow it to
4459 try to change a logical combination of comparisons into a range test.
4461 For example, both
4462 X == 2 || X == 3 || X == 4 || X == 5
4463 and
4464 X >= 2 && X <= 5
4465 are converted to
4466 (unsigned) (X - 2) <= 3
4468 We describe each set of comparisons as being either inside or outside
4469 a range, using a variable named like IN_P, and then describe the
4470 range with a lower and upper bound. If one of the bounds is omitted,
4471 it represents either the highest or lowest value of the type.
4473 In the comments below, we represent a range by two numbers in brackets
4474 preceded by a "+" to designate being inside that range, or a "-" to
4475 designate being outside that range, so the condition can be inverted by
4476 flipping the prefix. An omitted bound is represented by a "-". For
4477 example, "- [-, 10]" means being outside the range starting at the lowest
4478 possible value and ending at 10, in other words, being greater than 10.
4479 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4480 always false.
4482 We set up things so that the missing bounds are handled in a consistent
4483 manner so neither a missing bound nor "true" and "false" need to be
4484 handled using a special case. */
4486 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4487 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4488 and UPPER1_P are nonzero if the respective argument is an upper bound
4489 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4490 must be specified for a comparison. ARG1 will be converted to ARG0's
4491 type if both are specified. */
4493 static tree
4496 {
4497 tree tem;
4501 /* If neither arg represents infinity, do the normal operation.
4502 Else, if not a comparison, return infinity. Else handle the special
4503 comparison rules. Note that most of the cases below won't occur, but
4504 are handled for consistency. */
4507 {
4512 }
4517 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4518 for neither. In real maths, we cannot assume open ended ranges are
4519 the same. But, this is computer arithmetic, where numbers are finite.
4520 We can therefore make the transformation of any unbounded range with
4521 the value Z, Z being greater than any representable number. This permits
4522 us to treat unbounded ranges as equal. */
4526 {
4547 }
4550 }
4551 \f
4552 /* Helper routine for make_range. Perform one step for it, return
4553 new expression if the loop should continue or NULL_TREE if it should
4554 stop. */
4556 tree
4560 {
4566 {
4568 /* We can only do something if the range is testing for zero. */
4577 /* We can only do something if the range is testing for zero
4578 and if the second operand is an integer constant. Note that
4579 saying something is "in" the range we make is done by
4580 complementing IN_P since it will set in the initial case of
4581 being not equal to zero; "out" is leaving it alone. */
4588 {
4609 }
4611 /* If this is an unsigned comparison, we also know that EXP is
4612 greater than or equal to zero. We base the range tests we make
4613 on that fact, so we record it here so we can parse existing
4614 range tests. We test arg0_type since often the return type
4615 of, e.g. EQ_EXPR, is boolean. */
4617 {
4621 NULL_TREE))
4626 /* If the high bound is missing, but we have a nonzero low
4627 bound, reverse the range so it goes from zero to the low bound
4628 minus 1. */
4630 {
4635 }
4636 }
4644 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4645 low and high are non-NULL, then normalize will DTRT. */
4648 {
4653 }
4655 /* (-x) IN [a,b] -> x in [-b, -a] */
4667 /* ~ X -> -X - 1 */
4676 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4677 move a constant to the other side. */
4682 /* If EXP is signed, any overflow in the computation is undefined,
4683 so we don't worry about it so long as our computations on
4684 the bounds don't overflow. For unsigned, overflow is defined
4685 and this is exactly the right thing. */
4697 normalize:
4698 /* Check for an unsigned range which has wrapped around the maximum
4699 value thus making n_high < n_low, and normalize it. */
4701 {
4707 /* If the range is of the form +/- [ x+1, x ], we won't
4708 be able to normalize it. But then, it represents the
4709 whole range or the empty set, so make it
4710 +/- [ -, - ]. */
4714 else
4716 }
4717 else
4725 CASE_CONVERT:
4743 /* If we're converting arg0 from an unsigned type, to exp,
4744 a signed type, we will be doing the comparison as unsigned.
4745 The tests above have already verified that LOW and HIGH
4746 are both positive.
4748 So we have to ensure that we will handle large unsigned
4749 values the same way that the current signed bounds treat
4750 negative values. */
4753 {
4754 tree high_positive;
4755 tree equiv_type;
4756 /* For fixed-point modes, we need to pass the saturating flag
4757 as the 2nd parameter. */
4759 equiv_type
4762 else
4763 equiv_type
4766 /* A range without an upper bound is, naturally, unbounded.
4767 Since convert would have cropped a very large value, use
4768 the max value for the destination type. */
4769 high_positive
4776 high_positive),
4779 /* If the low bound is specified, "and" the range with the
4780 range for which the original unsigned value will be
4781 positive. */
4783 {
4786 integer_zero_node),
4787 high_positive))
4791 }
4792 else
4793 {
4794 /* Otherwise, "or" the range with the range of the input
4795 that will be interpreted as negative. */
4798 integer_zero_node),
4799 high_positive))
4803 }
4804 }
4813 }
4814 }
4816 /* Given EXP, a logical expression, set the range it is testing into
4817 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4818 actually being tested. *PLOW and *PHIGH will be made of the same
4819 type as the returned expression. If EXP is not a comparison, we
4820 will most likely not be returning a useful value and range. Set
4821 *STRICT_OVERFLOW_P to true if the return value is only valid
4822 because signed overflow is undefined; otherwise, do not change
4823 *STRICT_OVERFLOW_P. */
4825 tree
4828 {
4836 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4837 and see if we can refine the range. Some of the cases below may not
4838 happen, but it doesn't seem worth worrying about this. We "continue"
4839 the outer loop when we've changed something; otherwise we "break"
4840 the switch, which will "break" the while. */
4846 {
4852 {
4860 }
4869 }
4871 /* If EXP is a constant, we can evaluate whether this is true or false. */
4873 {
4880 }
4884 }
4886 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4887 a bitwise check i.e. when
4888 LOW == 0xXX...X00...0
4889 HIGH == 0xXX...X11...1
4890 Return corresponding mask in MASK and stem in VALUE. */
4892 static bool
4895 {
4918 }
4919 \f
4920 /* Helper routine for build_range_check and match.pd. Return the type to
4921 perform the check or NULL if it shouldn't be optimized. */
4923 tree
4925 {
4926 /* First make sure that arithmetics in this type is valid, then make sure
4927 that it wraps around. */
4933 {
4936 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4937 for the type in question, as we rely on this here. */
4947 else
4949 }
4951 }
4953 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4954 type, TYPE, return an expression to test if EXP is in (or out of, depending
4955 on IN_P) the range. Return 0 if the test couldn't be created. */
4957 tree
4960 {
4963 /* Disable this optimization for function pointer expressions
4964 on targets that require function pointer canonicalization. */
4971 {
4977 }
4999 value);
5002 {
5004 {
5008 }
5010 }
5012 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5014 {
5018 {
5020 {
5023 etype
5025 else
5028 }
5031 }
5032 }
5034 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5035 This requires wrap-around arithmetics for the type of the expression. */
5055 }
5056 \f
5057 /* Return the predecessor of VAL in its type, handling the infinite case. */
5059 static tree
5061 {
5067 else
5070 }
5072 /* Return the successor of VAL in its type, handling the infinite case. */
5074 static tree
5076 {
5082 else
5085 }
5087 /* Given two ranges, see if we can merge them into one. Return 1 if we
5088 can, 0 if we can't. Set the output range into the specified parameters. */
5090 bool
5093 {
5097 tree tem;
5107 /* Make range 0 be the range that starts first, or ends last if they
5108 start at the same value. Swap them if it isn't. */
5111 || (lowequal
5114 {
5118 }
5120 /* If the second range is != high1 where high1 is the type maximum of
5121 the type, try first merging with < high1 range. */
5123 && high1
5130 {
5135 /* Similarly for the second range != low1 where low1 is the type minimum
5136 of the type, try first merging with > low1 range. */
5141 }
5143 /* Now flag two cases, whether the ranges are disjoint or whether the
5144 second range is totally subsumed in the first. Note that the tests
5145 below are simplified by the ones above. */
5151 /* We now have four cases, depending on whether we are including or
5152 excluding the two ranges. */
5154 {
5155 /* If they don't overlap, the result is false. If the second range
5156 is a subset it is the result. Otherwise, the range is from the start
5157 of the second to the end of the first. */
5162 else
5164 }
5167 {
5168 /* If they don't overlap, the result is the first range. If they are
5169 equal, the result is false. If the second range is a subset of the
5170 first, and the ranges begin at the same place, we go from just after
5171 the end of the second range to the end of the first. If the second
5172 range is not a subset of the first, or if it is a subset and both
5173 ranges end at the same place, the range starts at the start of the
5174 first range and ends just before the second range.
5175 Otherwise, we can't describe this as a single range. */
5181 {
5186 {
5187 /* We are in the weird situation where high0 > high1 but
5188 high1 has no successor. Punt. */
5190 }
5191 }
5193 {
5198 {
5199 /* low0 < low1 but low1 has no predecessor. Punt. */
5201 }
5202 }
5203 else
5205 }
5208 {
5209 /* If they don't overlap, the result is the second range. If the second
5210 is a subset of the first, the result is false. Otherwise,
5211 the range starts just after the first range and ends at the
5212 end of the second. */
5217 else
5218 {
5223 {
5224 /* high1 > high0 but high0 has no successor. Punt. */
5226 }
5227 }
5228 }
5230 else
5231 {
5232 /* The case where we are excluding both ranges. Here the complex case
5233 is if they don't overlap. In that case, the only time we have a
5234 range is if they are adjacent. If the second is a subset of the
5235 first, the result is the first. Otherwise, the range to exclude
5236 starts at the beginning of the first range and ends at the end of the
5237 second. */
5239 {
5244 else
5245 {
5246 /* Canonicalize - [min, x] into - [-, x]. */
5249 {
5252 GET_MODE_BITSIZE
5255 /* FALLTHROUGH */
5268 }
5270 /* Canonicalize - [x, max] into - [x, -]. */
5273 {
5276 GET_MODE_BITSIZE
5279 /* FALLTHROUGH */
5295 }
5297 /* The ranges might be also adjacent between the maximum and
5298 minimum values of the given type. For
5299 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5300 return + [x + 1, y - 1]. */
5302 {
5309 }
5310 else
5312 }
5313 }
5316 else
5318 }
5322 }
5323 \f
5325 /* Subroutine of fold, looking inside expressions of the form
5326 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5327 of the COND_EXPR. This function is being used also to optimize
5328 A op B ? C : A, by reversing the comparison first.
5330 Return a folded expression whose code is not a COND_EXPR
5331 anymore, or NULL_TREE if no folding opportunity is found. */
5333 static tree
5336 {
5341 tree tem;
5346 /* If we have A op 0 ? A : -A, consider applying the following
5347 transformations:
5349 A == 0? A : -A same as -A
5350 A != 0? A : -A same as A
5351 A >= 0? A : -A same as abs (A)
5352 A > 0? A : -A same as abs (A)
5353 A <= 0? A : -A same as -abs (A)
5354 A < 0? A : -A same as -abs (A)
5356 None of these transformations work for modes with signed
5357 zeros. If A is +/-0, the first two transformations will
5358 change the sign of the result (from +0 to -0, or vice
5359 versa). The last four will fix the sign of the result,
5360 even though the original expressions could be positive or
5361 negative, depending on the sign of A.
5363 Note that all these transformations are correct if A is
5364 NaN, since the two alternatives (A and -A) are also NaNs. */
5371 /* In the case that A is of the form X-Y, '-A' (arg2) may
5372 have already been folded to Y-X, check for that. */
5380 {
5392 /* Fall through. */
5403 /* FALLTHRU */
5413 }
5415 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5416 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5417 both transformations are correct when A is NaN: A != 0
5418 is then true, and A == 0 is false. */
5422 {
5427 }
5429 /* Try some transformations of A op B ? A : B.
5431 A == B? A : B same as B
5432 A != B? A : B same as A
5433 A >= B? A : B same as max (A, B)
5434 A > B? A : B same as max (B, A)
5435 A <= B? A : B same as min (A, B)
5436 A < B? A : B same as min (B, A)
5438 As above, these transformations don't work in the presence
5439 of signed zeros. For example, if A and B are zeros of
5440 opposite sign, the first two transformations will change
5441 the sign of the result. In the last four, the original
5442 expressions give different results for (A=+0, B=-0) and
5443 (A=-0, B=+0), but the transformed expressions do not.
5445 The first two transformations are correct if either A or B
5446 is a NaN. In the first transformation, the condition will
5447 be false, and B will indeed be chosen. In the case of the
5448 second transformation, the condition A != B will be true,
5449 and A will be chosen.
5451 The conversions to max() and min() are not correct if B is
5452 a number and A is not. The conditions in the original
5453 expressions will be false, so all four give B. The min()
5454 and max() versions would give a NaN instead. */
5457 /* Avoid these transformations if the COND_EXPR may be used
5458 as an lvalue in the C++ front-end. PR c++/19199. */
5459 && (in_gimple_form
5465 {
5471 {
5480 /* In C++ a ?: expression can be an lvalue, so put the
5481 operand which will be used if they are equal first
5482 so that we can convert this back to the
5483 corresponding COND_EXPR. */
5485 {
5493 }
5500 {
5508 }
5521 }
5522 }
5525 }
5528 \f
5529 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5530 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5531 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5532 false) >= 2)
5533 #endif
5535 /* EXP is some logical combination of boolean tests. See if we can
5536 merge it into some range test. Return the new tree if so. */
5538 static tree
5541 {
5557 /* If this is an OR operation, invert both sides; we will invert
5558 again at the end. */
5562 /* If both expressions are the same, if we can merge the ranges, and we
5563 can build the range test, return it or it inverted. If one of the
5564 ranges is always true or always false, consider it to be the same
5565 expression as the other. */
5573 {
5577 }
5579 /* On machines where the branch cost is expensive, if this is a
5580 short-circuited branch and the underlying object on both sides
5581 is the same, make a non-short-circuit operation. */
5584 logical_op_non_short_circuit
5587 && !flag_sanitize_coverage
5591 {
5592 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5593 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5594 which cases we can't do this. */
5602 {
5611 {
5614 WARN_STRICT_OVERFLOW_COMPARISON);
5618 }
5619 }
5620 }
5623 }
5624 \f
5625 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5626 bit value. Arrange things so the extra bits will be set to zero if and
5627 only if C is signed-extended to its full width. If MASK is nonzero,
5628 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5630 static tree
5632 {
5635 tree temp;
5640 /* We work by getting just the sign bit into the low-order bit, then
5641 into the high-order bit, then sign-extend. We then XOR that value
5642 with C. */
5646 /* We must use a signed type in order to get an arithmetic right shift.
5647 However, we must also avoid introducing accidental overflows, so that
5648 a subsequent call to integer_zerop will work. Hence we must
5649 do the type conversion here. At this point, the constant is either
5650 zero or one, and the conversion to a signed type can never overflow.
5651 We could get an overflow if this conversion is done anywhere else. */
5660 /* If necessary, convert the type back to match the type of C. */
5665 }
5666 \f
5667 /* For an expression that has the form
5668 (A && B) || ~B
5669 or
5670 (A || B) && ~B,
5671 we can drop one of the inner expressions and simplify to
5672 A || ~B
5673 or
5674 A && ~B
5675 LOC is the location of the resulting expression. OP is the inner
5676 logical operation; the left-hand side in the examples above, while CMPOP
5677 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5678 removing a condition that guards another, as in
5679 (A != NULL && A->...) || A == NULL
5680 which we must not transform. If RHS_ONLY is true, only eliminate the
5681 right-most operand of the inner logical operation. */
5683 static tree
5686 {
5704 {
5707 {
5710 }
5711 }
5713 {
5716 {
5719 }
5720 }
5735 }
5737 /* Find ways of folding logical expressions of LHS and RHS:
5738 Try to merge two comparisons to the same innermost item.
5739 Look for range tests like "ch >= '0' && ch <= '9'".
5740 Look for combinations of simple terms on machines with expensive branches
5741 and evaluate the RHS unconditionally.
5743 For example, if we have p->a == 2 && p->b == 4 and we can make an
5744 object large enough to span both A and B, we can do this with a comparison
5745 against the object ANDed with the a mask.
5747 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5748 operations to do this with one comparison.
5750 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5751 function and the one above.
5753 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5754 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5756 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5757 two operands.
5759 We return the simplified tree or 0 if no optimization is possible. */
5761 static tree
5764 {
5765 /* If this is the "or" of two comparisons, we can do something if
5766 the comparisons are NE_EXPR. If this is the "and", we can do something
5767 if the comparisons are EQ_EXPR. I.e.,
5768 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5770 WANTED_CODE is this operation code. For single bit fields, we can
5771 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5772 comparison for one-bit fields. */
5793 /* Start by getting the comparison codes. Fail if anything is volatile.
5794 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5795 it were surrounded with a NE_EXPR. */
5804 {
5808 }
5811 {
5815 }
5826 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5829 {
5832 {
5837 }
5840 {
5846 }
5847 }
5852 /* If the RHS can be evaluated unconditionally and its operands are
5853 simple, it wins to evaluate the RHS unconditionally on machines
5854 with expensive branches. In this case, this isn't a comparison
5855 that can be merged. */
5862 {
5863 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5874 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5884 }
5886 /* See if the comparisons can be merged. Then get all the parameters for
5887 each side. */
5912 /* It must be true that the inner operation on the lhs of each
5913 comparison must be the same if we are to be able to do anything.
5914 Then see if we have constants. If not, the same must be true for
5915 the rhs's. */
5924 {
5927 }
5932 else
5935 /* If either comparison code is not correct for our logical operation,
5936 fail. However, we can convert a one-bit comparison against zero into
5937 the opposite comparison against that bit being set in the field. */
5941 {
5943 {
5944 /* Make the left operand unsigned, since we are only interested
5945 in the value of one bit. Otherwise we are doing the wrong
5946 thing below. */
5949 }
5950 else
5952 }
5954 /* This is analogous to the code for l_const above. */
5956 {
5958 {
5961 }
5962 else
5964 }
5966 /* See if we can find a mode that contains both fields being compared on
5967 the left. If we can't, fail. Otherwise, update all constants and masks
5968 to be relative to a field of that size. */
5982 {
5985 }
5993 {
6000 {
6004 }
6005 }
6007 {
6014 {
6018 }
6019 }
6021 /* If the right sides are not constant, do the same for it. Also,
6022 disallow this optimization if a size, signedness or storage order
6023 mismatch occurs between the left and right sides. */
6025 {
6029 /* Make sure the two fields on the right
6030 correspond to the left without being swapped. */
6047 {
6050 }
6059 /* Make a mask that corresponds to both fields being compared.
6060 Do this for both items being compared. If the operands are the
6061 same size and the bits being compared are in the same position
6062 then we can do this by masking both and comparing the masked
6063 results. */
6070 {
6084 }
6086 /* There is still another way we can do something: If both pairs of
6087 fields being compared are adjacent, we may be able to make a wider
6088 field containing them both.
6090 Note that we still must mask the lhs/rhs expressions. Furthermore,
6091 the mask must be shifted to account for the shift done by
6092 make_bit_field_ref. */
6101 {
6102 tree type;
6118 /* Convert to the smaller type before masking out unwanted bits. */
6121 {
6123 {
6127 }
6129 {
6133 }
6134 }
6143 }
6146 }
6148 /* Handle the case of comparisons with constants. If there is something in
6149 common between the masks, those bits of the constants must be the same.
6150 If not, the condition is always false. Test for this to avoid generating
6151 incorrect code below. */
6156 {
6158 {
6161 }
6162 else
6163 {
6166 }
6167 }
6172 /* Construct the expression we will return. First get the component
6173 reference we will make. Unless the mask is all ones the width of
6174 that field, perform the mask operation. Then compare with the
6175 merged constant. */
6186 }
6187 \f
6188 /* T is an integer expression that is being multiplied, divided, or taken a
6189 modulus (CODE says which and what kind of divide or modulus) by a
6190 constant C. See if we can eliminate that operation by folding it with
6191 other operations already in T. WIDE_TYPE, if non-null, is a type that
6192 should be used for the computation if wider than our type.
6194 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6195 (X * 2) + (Y * 4). We must, however, be assured that either the original
6196 expression would not overflow or that overflow is undefined for the type
6197 in the language in question.
6199 If we return a non-null expression, it is an equivalent form of the
6200 original computation, but need not be in the original type.
6202 We set *STRICT_OVERFLOW_P to true if the return values depends on
6203 signed overflow being undefined. Otherwise we do not change
6204 *STRICT_OVERFLOW_P. */
6206 static tree
6209 {
6210 /* To avoid exponential search depth, refuse to allow recursion past
6211 three levels. Beyond that (1) it's highly unlikely that we'll find
6212 something interesting and (2) we've probably processed it before
6213 when we built the inner expression. */
6216 tree ret;
6221 depth++;
6223 depth--;
6226 }
6228 static tree
6231 {
6243 /* Don't deal with constants of zero here; they confuse the code below. */
6253 /* Note that we need not handle conditional operations here since fold
6254 already handles those cases. So just do arithmetic here. */
6256 {
6258 /* For a constant, we can always simplify if we are a multiply
6259 or (for divide and modulus) if it is a multiple of our constant. */
6263 {
6266 /* If the multiplication overflowed, we lost information on it.
6267 See PR68142 and PR69845. */
6271 }
6275 /* If op0 is an expression ... */
6281 /* ... and has wrapping overflow, and its type is smaller
6282 than ctype, then we cannot pass through as widening. */
6287 /* ... or this is a truncation (t is narrower than op0),
6288 then we cannot pass through this narrowing. */
6291 /* ... or signedness changes for division or modulus,
6292 then we cannot pass through this conversion. */
6296 /* ... or has undefined overflow while the converted to
6297 type has not, we cannot do the operation in the inner type
6298 as that would introduce undefined overflow. */
6304 /* Pass the constant down and see if we can make a simplification. If
6305 we can, replace this expression with the inner simplification for
6306 possible later conversion to our or some other type. */
6317 /* If widening the type changes it from signed to unsigned, then we
6318 must avoid building ABS_EXPR itself as unsigned. */
6320 {
6324 {
6327 }
6329 }
6330 /* If the constant is negative, we cannot simplify this. */
6333 /* FALLTHROUGH */
6335 /* For division and modulus, type can't be unsigned, as e.g.
6336 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6337 For signed types, even with wrapping overflow, this is fine. */
6346 /* If widening the type changes the signedness, then we can't perform
6347 this optimization as that changes the result. */
6351 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6357 {
6364 }
6368 /* If the second operand is constant, this is a multiplication
6369 or floor division, by a power of two, so we can treat it that
6370 way unless the multiplier or divisor overflows. Signed
6371 left-shift overflow is implementation-defined rather than
6372 undefined in C90, so do not convert signed left shift into
6373 multiplication. */
6376 /* const_binop may not detect overflow correctly,
6377 so check for it explicitly here. */
6386 ctype,
6388 t1),
6393 /* See if we can eliminate the operation on both sides. If we can, we
6394 can return a new PLUS or MINUS. If we can't, the only remaining
6395 cases where we can do anything are if the second operand is a
6396 constant. */
6403 /* If not multiplication, we can only do this if both operands
6404 are divisible by c. */
6407 {
6412 }
6414 /* If this was a subtraction, negate OP1 and set it to be an addition.
6415 This simplifies the logic below. */
6417 {
6419 /* If OP1 was not easily negatable, the constant may be OP0. */
6421 {
6424 }
6425 }
6430 /* If either OP1 or C are negative, this optimization is not safe for
6431 some of the division and remainder types while for others we need
6432 to change the code. */
6434 {
6442 }
6444 /* If it's a multiply or a division/modulus operation of a multiple
6445 of our constant, do the operation and verify it doesn't overflow. */
6449 {
6452 /* We allow the constant to overflow with wrapping semantics. */
6456 }
6457 else
6460 /* If we have an unsigned type, we cannot widen the operation since it
6461 will change the result if the original computation overflowed. */
6465 /* The last case is if we are a multiply. In that case, we can
6466 apply the distributive law to commute the multiply and addition
6467 if the multiplication of the constants doesn't overflow
6468 and overflow is defined. With undefined overflow
6469 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6475 op1);
6480 /* We have a special case here if we are doing something like
6481 (C * 8) % 4 since we know that's zero. */
6484 /* If the multiplication can overflow we cannot optimize this. */
6489 {
6492 }
6494 /* ... fall through ... */
6498 /* If we can extract our operation from the LHS, do so and return a
6499 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6500 do something only if the second operand is a constant. */
6516 /* If these are the same operation types, we can associate them
6517 assuming no overflow. */
6519 {
6534 }
6536 /* If these operations "cancel" each other, we have the main
6537 optimizations of this pass, which occur when either constant is a
6538 multiple of the other, in which case we replace this with either an
6539 operation or CODE or TCODE.
6541 If we have an unsigned type, we cannot do this since it will change
6542 the result if the original computation overflowed. */
6549 {
6552 {
6559 }
6562 {
6569 }
6570 }
6575 }
6578 }
6579 \f
6580 /* Return a node which has the indicated constant VALUE (either 0 or
6581 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6582 and is of the indicated TYPE. */
6584 tree
6586 {
6595 else
6597 }
6600 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6601 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6602 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6603 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6604 COND is the first argument to CODE; otherwise (as in the example
6605 given here), it is the second argument. TYPE is the type of the
6606 original expression. Return NULL_TREE if no simplification is
6607 possible. */
6609 static tree
6614 {
6622 /* Do not move possibly trapping operations into the conditional as this
6623 pessimizes code and causes gimplification issues when applied late. */
6631 {
6635 /* If this operand throws an expression, then it does not make
6636 sense to try to perform a logical or arithmetic operation
6637 involving it. */
6642 }
6645 {
6650 }
6651 else
6652 /* Detect the case of mixing vector and scalar types - bail out. */
6658 /* This transformation is only worthwhile if we don't have to wrap ARG
6659 in a SAVE_EXPR and the operation can be simplified without recursing
6660 on at least one of the branches once its pushed inside the COND_EXPR. */
6669 {
6673 else
6675 }
6677 {
6681 else
6683 }
6685 /* Check that we have simplified at least one of the branches. */
6690 }
6692 \f
6693 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6695 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6696 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6697 ADDEND is the same as X.
6699 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6700 and finite. The problematic cases are when X is zero, and its mode
6701 has signed zeros. In the case of rounding towards -infinity,
6702 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6703 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6705 bool
6707 {
6711 /* Don't allow the fold with -fsignaling-nans. */
6715 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6719 /* In a vector or complex, we would need to check the sign of all zeros. */
6723 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6727 /* The mode has signed zeros, and we have to honor their sign.
6728 In this situation, there is only one case we can return true for.
6729 X - 0 is the same as X unless rounding towards -infinity is
6730 supported. */
6732 }
6734 /* Subroutine of match.pd that optimizes comparisons of a division by
6735 a nonzero integer constant against an integer constant, i.e.
6736 X/C1 op C2.
6738 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6739 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6741 enum tree_code
6744 {
6749 /* We have to do this the hard way to detect unsigned overflow.
6750 prod = int_const_binop (MULT_EXPR, c1, c2); */
6756 {
6760 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6763 }
6765 {
6768 {
6787 }
6788 }
6789 else
6790 {
6791 /* A negative divisor reverses the relational operators. */
6796 {
6815 }
6816 }
6829 }
6832 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6833 equality/inequality test, then return a simplified form of the test
6834 using a sign testing. Otherwise return NULL. TYPE is the desired
6835 result type. */
6837 static tree
6840 tree result_type)
6841 {
6842 /* If this is testing a single bit, we can optimize the test. */
6846 {
6847 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6848 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6852 /* This is only a win if casting to a signed type is cheap,
6853 i.e. when arg00's type is not a partial mode. */
6855 {
6858 result_type,
6861 }
6862 }
6865 }
6867 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6868 equality/inequality test, then return a simplified form of
6869 the test using shifts and logical operations. Otherwise return
6870 NULL. TYPE is the desired result type. */
6872 tree
6875 {
6876 /* If this is testing a single bit, we can optimize the test. */
6880 {
6889 /* First, see if we can fold the single bit test into a sign-bit
6890 test. */
6892 result_type);
6896 /* Otherwise we have (A & C) != 0 where C is a single bit,
6897 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6898 Similarly for (A & C) == 0. */
6900 /* If INNER is a right shift of a constant and it plus BITNUM does
6901 not overflow, adjust BITNUM and INNER. */
6907 {
6910 }
6912 /* If we are going to be able to omit the AND below, we must do our
6913 operations as unsigned. If we must use the AND, we have a choice.
6914 Normally unsigned is faster, but for some machines signed is. */
6932 /* Put the AND last so it can combine with more things. */
6935 /* Make sure to return the proper type. */
6939 }
6941 }
6943 /* Test whether it is preferable two swap two operands, ARG0 and
6944 ARG1, for example because ARG0 is an integer constant and ARG1
6945 isn't. */
6947 bool
6949 {
6963 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6964 for commutative and comparison operators. Ensuring a canonical
6965 form allows the optimizers to find additional redundancies without
6966 having to explicitly check for both orderings. */
6972 /* Put SSA_NAMEs last. */
6978 /* Put variables last. */
6985 }
6988 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6989 means A >= Y && A != MAX, but in this case we know that
6990 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6992 static tree
6994 {
7001 else
7010 {
7013 }
7015 {
7018 }
7019 else
7026 {
7027 /* Convert the pointer types into integer before taking the difference. */
7031 }
7032 else
7039 }
7041 /* Fold a sum or difference of at least one multiplication.
7042 Returns the folded tree or NULL if no simplification could be made. */
7044 static tree
7047 {
7051 /* (A * C) +- (B * C) -> (A+-B) * C.
7052 (A * C) +- A -> A * (C+-1).
7053 We are most concerned about the case where C is a constant,
7054 but other combinations show up during loop reduction. Since
7055 it is not difficult, try all four possibilities. */
7058 {
7061 }
7063 {
7066 }
7067 else
7068 {
7069 /* We cannot generate constant 1 for fract. */
7074 }
7076 {
7079 }
7081 {
7083 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7084 the purpose of this canonicalization. */
7088 {
7091 }
7092 else
7094 }
7095 else
7096 {
7097 /* We cannot generate constant 1 for fract. */
7102 }
7105 /* Prefer factoring a common non-constant. */
7115 /* No identical multiplicands; see if we can find a common
7116 power-of-two factor in non-power-of-two multiplies. This
7117 can help in multi-dimensional array access. */
7120 {
7123 tree maybe_same;
7127 /* Move min of absolute values to int11. */
7129 {
7134 }
7135 else
7139 /* The remainder should not be a constant, otherwise we
7140 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7141 increased the number of multiplications necessary. */
7143 {
7151 }
7152 }
7159 /* We are neither factoring zero nor minus one. */
7167 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7168 same may be minus one and thus the multiplication may overflow. Perform
7169 the sum operation in an unsigned type. */
7174 /* If the sum evaluated to a constant that is not -INF the multiplication
7175 cannot overflow. */
7182 /* Do not resort to unsigned multiplication because
7183 we lose the no-overflow property of the expression. */
7185 }
7187 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7188 specified by EXPR into the buffer PTR of length LEN bytes.
7189 Return the number of bytes placed in the buffer, or zero
7190 upon failure. */
7192 static int
7194 {
7206 /* Dry run. */
7212 {
7214 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7215 number of bytes. */
7219 {
7226 else
7228 }
7229 else
7233 }
7235 }
7238 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7239 specified by EXPR into the buffer PTR of length LEN bytes.
7240 Return the number of bytes placed in the buffer, or zero
7241 upon failure. */
7243 static int
7245 {
7249 FIXED_VALUE_TYPE value;
7264 }
7267 /* Subroutine of native_encode_expr. Encode the REAL_CST
7268 specified by EXPR into the buffer PTR of length LEN bytes.
7269 Return the number of bytes placed in the buffer, or zero
7270 upon failure. */
7272 static int
7274 {
7280 /* There are always 32 bits in each long, no matter the size of
7281 the hosts long. We handle floating point representations with
7282 up to 192 bits. */
7291 /* Dry run. */
7300 {
7305 {
7312 else
7314 }
7315 else
7316 {
7319 {
7320 /* Reverse bytes within each long, or within the entire float
7321 if it's smaller than a long (for HFmode). */
7324 }
7325 }
7330 }
7332 }
7334 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7335 specified by EXPR into the buffer PTR of length LEN bytes.
7336 Return the number of bytes placed in the buffer, or zero
7337 upon failure. */
7339 static int
7341 {
7343 tree part;
7357 }
7360 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7361 specified by EXPR into the buffer PTR of length LEN bytes.
7362 Return the number of bytes placed in the buffer, or zero
7363 upon failure. */
7365 static int
7367 {
7378 {
7380 {
7383 }
7394 }
7396 }
7399 /* Subroutine of native_encode_expr. Encode the STRING_CST
7400 specified by EXPR into the buffer PTR of length LEN bytes.
7401 Return the number of bytes placed in the buffer, or zero
7402 upon failure. */
7404 static int
7406 {
7409 /* Wide-char strings are encoded in target byte-order so native
7410 encoding them is trivial. */
7425 {
7428 {
7431 }
7434 }
7435 else
7438 }
7441 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7442 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7443 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7444 anything, just do a dry run. If OFF is not -1 then start
7445 the encoding at byte offset OFF and encode at most LEN bytes.
7446 Return the number of bytes placed in the buffer, or zero upon failure. */
7448 int
7450 {
7451 /* We don't support starting at negative offset and -1 is special. */
7456 {
7477 }
7478 }
7481 /* Subroutine of native_interpret_expr. Interpret the contents of
7482 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7483 If the buffer cannot be interpreted, return NULL_TREE. */
7485 static tree
7487 {
7497 }
7500 /* Subroutine of native_interpret_expr. Interpret the contents of
7501 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7502 If the buffer cannot be interpreted, return NULL_TREE. */
7504 static tree
7506 {
7509 double_int result;
7510 FIXED_VALUE_TYPE fixed_value;
7520 }
7523 /* Subroutine of native_interpret_expr. Interpret the contents of
7524 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7525 If the buffer cannot be interpreted, return NULL_TREE. */
7527 static tree
7529 {
7533 /* There are always 32 bits in each long, no matter the size of
7534 the hosts long. We handle floating point representations with
7535 up to 192 bits. */
7536 REAL_VALUE_TYPE r;
7546 {
7547 /* Both OFFSET and BYTE index within a long;
7548 bitpos indexes the whole float. */
7551 {
7558 else
7560 }
7561 else
7562 {
7565 {
7566 /* Reverse bytes within each long, or within the entire float
7567 if it's smaller than a long (for HFmode). */
7570 }
7571 }
7575 }
7579 }
7582 /* Subroutine of native_interpret_expr. Interpret the contents of
7583 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7584 If the buffer cannot be interpreted, return NULL_TREE. */
7586 static tree
7588 {
7603 }
7606 /* Subroutine of native_interpret_expr. Interpret the contents of
7607 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7608 If the buffer cannot be interpreted, return NULL_TREE. */
7610 static tree
7612 {
7625 {
7630 }
7632 }
7635 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7636 the buffer PTR of length LEN as a constant of type TYPE. For
7637 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7638 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7639 return NULL_TREE. */
7641 tree
7643 {
7645 {
7667 }
7668 }
7670 /* Returns true if we can interpret the contents of a native encoding
7671 as TYPE. */
7673 static bool
7675 {
7677 {
7690 }
7691 }
7694 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7695 TYPE at compile-time. If we're unable to perform the conversion
7696 return NULL_TREE. */
7698 static tree
7700 {
7701 /* We support up to 512-bit values (for V8DFmode). */
7705 /* Check that the host and target are sane. */
7714 }
7716 /* Build an expression for the address of T. Folds away INDIRECT_REF
7717 to avoid confusing the gimplify process. */
7719 tree
7721 {
7722 /* The size of the object is not relevant when talking about its address. */
7727 {
7732 }
7742 {
7747 }
7748 else
7752 }
7754 /* Build an expression for the address of T. */
7756 tree
7758 {
7762 }
7764 /* Fold a unary expression of code CODE and type TYPE with operand
7765 OP0. Return the folded expression if folding is successful.
7766 Otherwise, return NULL_TREE. */
7768 tree
7770 {
7771 tree tem;
7772 tree arg0;
7780 {
7783 {
7784 /* Don't use STRIP_NOPS, because signedness of argument type
7785 matters. */
7787 }
7788 else
7789 {
7790 /* Strip any conversions that don't change the mode. This
7791 is safe for every expression, except for a comparison
7792 expression because its signedness is derived from its
7793 operands.
7795 Note that this is done as an internal manipulation within
7796 the constant folder, in order to find the simplest
7797 representation of the arguments so that their form can be
7798 studied. In any cases, the appropriate type conversions
7799 should be put back in the tree that will get out of the
7800 constant folder. */
7802 }
7805 {
7808 {
7812 }
7813 }
7814 }
7821 {
7828 {
7842 /* If this was a conversion, and all we did was to move into
7843 inside the COND_EXPR, bring it back out. But leave it if
7844 it is a conversion from integer to integer and the
7845 result precision is no wider than a word since such a
7846 conversion is cheap and may be optimized away by combine,
7847 while it couldn't if it were outside the COND_EXPR. Then return
7848 so we don't get into an infinite recursion loop taking the
7849 conversion out and then back in. */
7861 && (INTEGRAL_TYPE_P
7874 }
7875 }
7878 {
7884 CASE_CONVERT:
7888 {
7889 /* If we have (type) (a CMP b) and type is an integral type, return
7890 new expression involving the new type. Canonicalize
7891 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7892 non-integral type.
7893 Do not fold the result as that would not simplify further, also
7894 folding again results in recursions. */
7904 }
7906 /* Handle (T *)&A.B.C for A being of type T and B and C
7907 living at offset zero. This occurs frequently in
7908 C++ upcasting and then accessing the base. */
7912 {
7914 tree offset;
7915 machine_mode mode;
7917 tree base
7921 /* If the reference was to a (constant) zero offset, we can use
7922 the address of the base if it has the same base type
7923 as the result type and the pointer type is unqualified. */
7931 }
7935 /* Detect assigning a bitfield. */
7937 && DECL_BIT_FIELD
7939 {
7940 /* Don't leave an assignment inside a conversion
7941 unless assigning a bitfield. */
7943 /* First do the assignment, then return converted constant. */
7948 }
7950 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7951 constants (if x has signed type, the sign bit cannot be set
7952 in c). This folds extension into the BIT_AND_EXPR.
7953 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7954 very likely don't have maximal range for their precision and this
7955 transformation effectively doesn't preserve non-maximal ranges. */
7959 {
7970 <= HOST_BITS_PER_WIDE_INT
7972 {
7976 cst &= HOST_WIDE_INT_M1U
7980 && !flag_syntax_only
7983 {
7987 }
7988 }
7990 {
7995 }
7996 }
7998 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7999 cast (T1)X will fold away. We assume that this happens when X itself
8000 is a cast. */
8004 {
8008 return fold_build_pointer_plus_loc
8010 }
8012 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8013 of the same precision, and X is an integer type not narrower than
8014 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8020 {
8026 }
8028 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8029 type of X and Y (integer types only). */
8034 {
8035 /* Be careful not to introduce new overflows. */
8036 tree mult_type;
8039 else
8043 {
8050 }
8051 }
8057 {
8064 }
8075 /* Convert fabs((double)float) into (double)fabsf(float). */
8078 {
8084 targ0));
8085 }
8089 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8108 /* Note that the operand of this must be an int
8109 and its values must be 0 or 1.
8110 ("true" is a fixed value perhaps depending on the language,
8111 but we don't handle values other than 1 correctly yet.) */
8118 /* Fold *&X to X if X is an lvalue. */
8120 {
8127 }
8133 }
8136 /* If the operation was a conversion do _not_ mark a resulting constant
8137 with TREE_OVERFLOW if the original constant was not. These conversions
8138 have implementation defined behavior and retaining the TREE_OVERFLOW
8139 flag here would confuse later passes such as VRP. */
8140 tree
8143 {
8152 }
8154 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8155 operands OP0 and OP1. LOC is the location of the resulting expression.
8156 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8157 Return the folded expression if folding is successful. Otherwise,
8158 return NULL_TREE. */
8159 static tree
8162 {
8163 tree tem;
8165 /* We only do these simplifications if we are optimizing. */
8169 /* Check for things like (A || B) && (A || C). We can convert this
8170 to A || (B && C). Note that either operator can be any of the four
8171 truth and/or operations and the transformation will still be
8172 valid. Also note that we only care about order for the
8173 ANDIF and ORIF operators. If B contains side effects, this
8174 might change the truth-value of A. */
8181 {
8201 /* This case if tricky because we must either have commutative
8202 operators or else A10 must not have side-effects. */
8208 a01);
8209 }
8211 /* See if we can build a range comparison. */
8217 {
8221 }
8225 {
8229 }
8231 /* Check for the possibility of merging component references. If our
8232 lhs is another similar operation, try to merge its rhs with our
8233 rhs. Then try to merge our lhs and rhs. */
8244 logical_op_non_short_circuit
8247 && !flag_sanitize_coverage
8252 {
8259 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8260 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8261 We don't want to pack more than two leafs to a non-IF AND/OR
8262 expression.
8263 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8264 equal to IF-CODE, then we don't want to add right-hand operand.
8265 If the inner right-hand side of left-hand operand has
8266 side-effects, or isn't simple, then we can't add to it,
8267 as otherwise we might destroy if-sequence. */
8270 /* Needed for sequence points to handle trappings, and
8271 side-effects. */
8273 {
8275 arg1);
8277 tem);
8278 }
8279 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8280 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8283 /* Needed for sequence points to handle trappings, and
8284 side-effects. */
8286 {
8291 }
8292 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8293 into (A OR B).
8294 For sequence point consistancy, we need to check for trapping,
8295 and side-effects. */
8299 }
8302 }
8304 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8305 by changing CODE to reduce the magnitude of constants involved in
8306 ARG0 of the comparison.
8307 Returns a canonicalized comparison tree if a simplification was
8308 possible, otherwise returns NULL_TREE.
8309 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8310 valid if signed overflow is undefined. */
8312 static tree
8316 {
8321 /* Match A +- CST code arg1. We can change this only if overflow
8322 is undefined. */
8325 /* In principle pointers also have undefined overflow behavior,
8326 but that causes problems elsewhere. */
8333 /* Identify the constant in arg0 and its sign. */
8337 /* Overflowed constants and zero will cause problems. */
8342 /* See if we can reduce the magnitude of the constant in
8343 arg0 by changing the comparison code. */
8344 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8348 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8352 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8356 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8360 else
8364 /* Now build the constant reduced in magnitude. But not if that
8365 would produce one outside of its types range. */
8381 }
8383 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8384 overflow further. Try to decrease the magnitude of constants involved
8385 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8386 and put sole constants at the second argument position.
8387 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8389 static tree
8392 {
8393 tree t;
8398 /* Try canonicalization by simplifying arg0. */
8403 {
8407 }
8409 /* Try canonicalization by simplifying arg1 using the swapped
8410 comparison. */
8418 }
8420 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8421 space. This is used to avoid issuing overflow warnings for
8422 expressions like &p->x which cannot wrap. */
8424 static bool
8426 {
8433 poly_wide_int wi_offset;
8439 else
8444 precision);
8459 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8460 array. */
8469 }
8471 /* Return a positive integer when the symbol DECL is known to have
8472 a nonzero address, zero when it's known not to (e.g., it's a weak
8473 symbol), and a negative integer when the symbol is not yet in the
8474 symbol table and so whether or not its address is zero is unknown.
8475 For function local objects always return positive integer. */
8476 static int
8478 {
8483 /* Function local objects are never NULL. */
8491 }
8493 /* Subroutine of fold_binary. This routine performs all of the
8494 transformations that are common to the equality/inequality
8495 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8496 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8497 fold_binary should call fold_binary. Fold a comparison with
8498 tree code CODE and type TYPE with operands OP0 and OP1. Return
8499 the folded comparison or NULL_TREE. */
8501 static tree
8504 {
8514 /* For comparisons of pointers we can decompose it to a compile time
8515 comparison of the base objects and the offsets into the object.
8516 This requires at least one operand being an ADDR_EXPR or a
8517 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8523 {
8526 machine_mode mode;
8530 /* Get base and offset for the access. Strip ADDR_EXPR for
8531 get_inner_reference, but put it back by stripping INDIRECT_REF
8532 off the base object if possible. indirect_baseN will be true
8533 if baseN is not an address but refers to the object itself. */
8536 {
8537 base0
8543 else
8545 }
8547 {
8551 {
8552 base0
8558 else
8560 }
8563 else
8567 {
8574 }
8575 }
8579 {
8580 base1
8586 else
8588 }
8590 {
8594 {
8595 base1
8601 else
8603 }
8606 else
8610 {
8617 }
8618 }
8620 /* If we have equivalent bases we might be able to simplify. */
8624 {
8625 /* We can fold this expression to a constant if the non-constant
8626 offset parts are equal. */
8630 && (equality_code
8631 || (indirect_base0
8634 {
8640 "occur when comparing P +- C1 with "
8642 WARN_STRICT_OVERFLOW_CONDITIONAL);
8645 {
8683 }
8684 }
8685 /* We can simplify the comparison to a comparison of the variable
8686 offset parts if the constant offset parts are equal.
8687 Be careful to use signed sizetype here because otherwise we
8688 mess with array offsets in the wrong way. This is possible
8689 because pointer arithmetic is restricted to retain within an
8690 object and overflow on pointer differences is undefined as of
8691 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8693 && (equality_code
8694 || (indirect_base0
8697 {
8698 /* By converting to signed sizetype we cover middle-end pointer
8699 arithmetic which operates on unsigned pointer types of size
8700 type size and ARRAY_REF offsets which are properly sign or
8701 zero extended from their type in case it is narrower than
8702 sizetype. */
8705 else
8709 else
8716 "occur when comparing P +- C1 with "
8718 WARN_STRICT_OVERFLOW_COMPARISON);
8721 }
8722 }
8723 /* For equal offsets we can simplify to a comparison of the
8724 base addresses. */
8726 && (indirect_base0
8728 && (indirect_base1
8733 {
8739 }
8740 /* Comparison between an ordinary (non-weak) symbol and a null
8741 pointer can be eliminated since such symbols must have a non
8742 null address. In C, relational expressions between pointers
8743 to objects and null pointers are undefined. The results
8744 below follow the C++ rules with the additional property that
8745 every object pointer compares greater than a null pointer.
8746 */
8749 /* Avoid folding references to struct members at offset 0 to
8750 prevent tests like '&ptr->firstmember == 0' from getting
8751 eliminated. When ptr is null, although the -> expression
8752 is strictly speaking invalid, GCC retains it as a matter
8753 of QoI. See PR c/44555. */
8756 && indirect_base0
8757 /* The caller guarantees that when one of the arguments is
8758 constant (i.e., null in this case) it is second. */
8760 {
8762 {
8773 }
8774 }
8775 }
8777 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8778 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8779 the resulting offset is smaller in absolute value than the
8780 original one and has the same sign. */
8789 {
8794 tree cst;
8796 "occur when combining constants around "
8799 /* Put the constant on the side where it doesn't overflow and is
8800 of lower absolute value and of same sign than before. */
8807 {
8810 variable1,
8814 }
8822 {
8828 variable2);
8829 }
8830 }
8836 /* If we are comparing an expression that just has comparisons
8837 of two integer values, arithmetic expressions of those comparisons,
8838 and constants, we can simplify it. There are only three cases
8839 to check: the two values can either be equal, the first can be
8840 greater, or the second can be greater. Fold the expression for
8841 those three values. Since each value must be 0 or 1, we have
8842 eight possibilities, each of which corresponds to the constant 0
8843 or 1 or one of the six possible comparisons.
8845 This handles common cases like (a > b) == 0 but also handles
8846 expressions like ((x > y) - (y > x)) > 0, which supposedly
8847 occur in macroized code. */
8850 {
8854 /* Don't handle degenerate cases here; they should already
8855 have been handled anyway. */
8864 {
8868 /* We can't just pass T to eval_subst in case cval1 or cval2
8869 was the same as ARG1. */
8871 tree high_result
8875 arg1);
8876 tree equal_result
8880 arg1);
8881 tree low_result
8885 arg1);
8887 /* All three of these results should be 0 or 1. Confirm they are.
8888 Then use those values to select the proper code to use. */
8893 {
8894 /* Make a 3-bit mask with the high-order bit being the
8895 value for `>', the next for '=', and the low for '<'. */
8899 {
8901 /* Always false. */
8922 /* Always true. */
8924 }
8927 }
8928 }
8929 }
8932 }
8935 /* Subroutine of fold_binary. Optimize complex multiplications of the
8936 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8937 argument EXPR represents the expression "z" of type TYPE. */
8939 static tree
8941 {
8946 {
8949 }
8951 {
8954 }
8955 else
8956 {
8960 }
8969 }
8972 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8973 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8974 true if successful. */
8976 static bool
8978 {
8983 {
8986 }
8988 {
8994 else
8996 }
8997 else
9003 }
9005 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9006 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9007 NULL_TREE otherwise. */
9009 static tree
9011 {
9032 {
9033 HOST_WIDE_INT index;
9039 }
9042 {
9048 }
9049 else
9051 }
9053 /* Try to fold a pointer difference of type TYPE two address expressions of
9054 array references AREF0 and AREF1 using location LOC. Return a
9055 simplified expression for the difference or NULL_TREE. */
9057 static tree
9061 {
9066 /* If the bases are array references as well, recurse. If the bases
9067 are pointer indirections compute the difference of the pointers.
9068 If the bases are equal, we are set. */
9071 && (base_offset
9073 use_pointer_diff)))
9076 && (base_offset
9077 = use_pointer_diff
9087 {
9093 base_offset,
9096 }
9098 }
9100 /* If the real or vector real constant CST of type TYPE has an exact
9101 inverse, return it, else return NULL. */
9103 tree
9105 {
9106 REAL_VALUE_TYPE r;
9107 tree unit_type;
9108 machine_mode mode;
9111 {
9121 {
9125 tree_vector_builder elts;
9130 {
9135 }
9138 }
9142 }
9143 }
9145 /* Mask out the tz least significant bits of X of type TYPE where
9146 tz is the number of trailing zeroes in Y. */
9147 static wide_int
9149 {
9154 }
9156 /* Return true when T is an address and is known to be nonzero.
9157 For floating point we further ensure that T is not denormal.
9158 Similar logic is present in nonzero_address in rtlanal.h.
9160 If the return value is based on the assumption that signed overflow
9161 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9162 change *STRICT_OVERFLOW_P. */
9164 static bool
9166 {
9170 /* Doing something useful for floating point would need more work. */
9176 {
9179 strict_overflow_p);
9185 strict_overflow_p);
9193 }
9196 {
9199 strict_overflow_p);
9207 strict_overflow_p);
9222 strict_overflow_p);
9226 strict_overflow_p);
9229 {
9241 }
9245 }
9247 }
9249 /* Return true when T is an address and is known to be nonzero.
9250 Handle warnings about undefined signed overflow. */
9252 bool
9254 {
9261 "determining that expression is always "
9263 WARN_STRICT_OVERFLOW_MISC);
9265 }
9267 /* Return true if T is known not to be equal to an integer W. */
9269 bool
9271 {
9273 value_range_kind rtype;
9275 {
9284 {
9289 }
9294 /* If T has some known zero bits and W has any of those bits set,
9295 then T is known not to be equal to W. */
9303 }
9304 }
9306 /* Fold a binary expression of code CODE and type TYPE with operands
9307 OP0 and OP1. LOC is the location of the resulting expression.
9308 Return the folded expression if folding is successful. Otherwise,
9309 return NULL_TREE. */
9311 tree
9314 {
9329 /* Strip any conversions that don't change the mode. This is
9330 safe for every expression, except for a comparison expression
9331 because its signedness is derived from its operands. So, in
9332 the latter case, only strip conversions that don't change the
9333 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9334 preserved.
9336 Note that this is done as an internal manipulation within the
9337 constant folder, in order to find the simplest representation
9338 of the arguments so that their form can be studied. In any
9339 cases, the appropriate type conversions should be put back in
9340 the tree that will get out of the constant folder. */
9343 {
9346 }
9347 else
9348 {
9351 }
9353 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9354 constant but we can't do arithmetic on them. */
9356 {
9359 {
9363 }
9364 }
9366 /* If this is a commutative operation, and ARG0 is a constant, move it
9367 to ARG1 to reduce the number of tests below. */
9372 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9373 to ARG1 to reduce the number of tests below. */
9382 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9384 First check for cases where an arithmetic operation is applied to a
9385 compound, conditional, or comparison operation. Push the arithmetic
9386 operation inside the compound or conditional to see if any folding
9387 can then be done. Convert comparison to conditional for this purpose.
9388 The also optimizes non-constant cases that used to be done in
9389 expand_expr.
9391 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9392 one of the operands is a comparison and the other is a comparison, a
9393 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9394 code below would make the expression more complex. Change it to a
9395 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9396 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9409 {
9413 boolean_type_node,
9421 }
9425 {
9427 {
9432 tem);
9433 }
9435 {
9440 tem);
9441 }
9446 {
9452 }
9457 {
9463 }
9464 }
9467 {
9469 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9472 {
9478 }
9480 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9483 {
9484 tree base;
9485 poly_int64 coffset;
9494 }
9499 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9505 arg1),
9507 arg0)));
9513 {
9514 /* X + (X / CST) * -CST is X % CST. */
9519 {
9528 cst0));
9529 }
9530 }
9532 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9533 one. Make sure the type is not saturating and has the signedness of
9534 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9535 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9542 {
9546 }
9549 {
9550 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9551 (plus (plus (mult) (mult)) (foo)) so that we can
9552 take advantage of the factoring cases below. */
9561 {
9567 else
9580 parg0),
9582 marg)),
9586 return
9592 parg1)));
9593 }
9594 }
9595 else
9596 {
9597 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9598 to __complex__ ( x, y ). This is not the same for SNaNs or
9599 if signed zeros are involved. */
9603 {
9610 {
9614 {
9620 }
9622 {
9628 }
9629 }
9630 }
9632 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9633 We associate floats only if the user has specified
9634 -fassociative-math. */
9638 {
9643 {
9644 tree tree0;
9647 }
9648 }
9649 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9650 We associate floats only if the user has specified
9651 -fassociative-math. */
9655 {
9660 {
9661 tree tree0;
9664 }
9665 }
9666 }
9668 bit_rotate:
9669 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9670 is a rotate of A by C1 bits. */
9671 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9672 is a rotate of A by B bits.
9673 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9674 though in this case CODE must be | and not + or ^, otherwise
9675 it doesn't return A when B is 0. */
9676 {
9678 tree rtype;
9687 /* Only create rotates in complete modes. Other cases are not
9688 expanded properly. */
9691 {
9704 {
9709 }
9714 {
9717 code0 == LSHIFT_EXPR
9720 }
9722 {
9732 {
9736 orig_tree01);
9738 }
9739 }
9743 {
9754 {
9758 orig_tree01);
9760 }
9761 }
9762 }
9763 }
9765 associate:
9766 /* In most languages, can't associate operations on floats through
9767 parentheses. Rather than remember where the parentheses were, we
9768 don't associate floats at all, unless the user has specified
9769 -fassociative-math.
9770 And, we need to make sure type is not saturating. */
9774 {
9780 /* Split both trees into variables, constants, and literals. Then
9781 associate each group together, the constants with literals,
9782 then the result with variables. This increases the chances of
9783 literals being recombined later and of generating relocatable
9784 expressions for the sum of a constant and literal. */
9792 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9796 /* With undefined overflow prefer doing association in a type
9797 which wraps on overflow, if that is one of the operand types. */
9800 {
9808 }
9810 /* With undefined overflow we can only associate constants with one
9811 variable, and constants whose association doesn't overflow. */
9814 {
9816 {
9817 /* ??? If split_tree would handle NEGATE_EXPR we could
9818 simply reject these cases and the allowed cases would
9819 be the var0/minus_var1 ones. */
9825 {
9828 }
9835 {
9838 }
9844 /* The only case we can still associate with two variables
9845 is if they cancel out. */
9849 }
9855 }
9857 /* Only do something if we found more than two objects. Otherwise,
9858 nothing has changed and we risk infinite recursion. */
9866 {
9878 {
9882 }
9884 {
9888 }
9890 /* Preserve the MINUS_EXPR if the negative part of the literal is
9891 greater than the positive part. Otherwise, the multiplicative
9892 folding code (i.e extract_muldiv) may be fooled in case
9893 unsigned constants are subtracted, like in the following
9894 example: ((X*2 + 4) - 8U)/2. */
9896 {
9900 /* But avoid ending up with only negated parts. */
9902 {
9906 }
9907 else
9908 {
9912 }
9913 }
9915 /* Don't introduce overflows through reassociation. */
9920 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9927 /* Eliminate minus_con0. */
9929 {
9936 else
9939 }
9941 /* Eliminate minus_var0. */
9943 {
9947 else
9950 }
9952 return
9955 }
9956 }
9962 /* Fold &a[i] - &a[j] to i-j. */
9967 {
9971 code
9975 }
9977 /* Further transformations are not for pointers. */
9981 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9984 /* If arg0 is e.g. unsigned int and type is int, then this could
9985 introduce UB, because if A is INT_MIN at runtime, the original
9986 expression can be well defined while the latter is not.
9987 See PR83269. */
9996 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9997 __complex__ ( x, -y ). This is not the same for SNaNs or if
9998 signed zeros are involved. */
10002 {
10009 {
10013 {
10015 arg1r ? arg1r
10020 }
10022 {
10026 arg1i ? arg1i
10029 }
10030 }
10031 }
10033 /* A - B -> A + (-B) if B is easily negatable. */
10037 /* Avoid this transformation if B is a positive REAL_CST. */
10045 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10046 one. Make sure the type is not saturating and has the signedness of
10047 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10048 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10055 {
10059 }
10065 {
10066 /* Transform x * -C into -x * C if x is easily negatable. */
10081 {
10084 "occur when simplifying "
10086 WARN_STRICT_OVERFLOW_MISC);
10088 }
10090 /* Optimize z * conj(z) for integer complex numbers. */
10097 }
10098 else
10099 {
10100 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10101 This is not the same for NaNs or if signed zeros are
10102 involved. */
10108 {
10111 return
10117 return
10122 }
10124 /* Optimize z * conj(z) for floating point complex numbers.
10125 Guarded by flag_unsafe_math_optimizations as non-finite
10126 imaginary components don't produce scalar results. */
10135 }
10139 /* Canonicalize (X & C1) | C2. */
10143 {
10148 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10156 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10158 {
10161 }
10163 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10164 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10165 mode which allows further optimizations. */
10170 {
10175 {
10178 }
10179 }
10182 {
10187 }
10188 }
10190 /* See if this can be simplified into a rotate first. If that
10191 is unsuccessful continue in the association code. */
10195 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10203 /* See if this can be simplified into a rotate first. If that
10204 is unsuccessful continue in the association code. */
10208 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10213 {
10214 tree tem2;
10221 }
10222 /* Fold ~X & 1 as (X & 1) == 0. */
10226 {
10227 tree tem2;
10234 }
10235 /* Fold !X & 1 as X == 0. */
10238 {
10242 }
10244 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10245 multiple of 1 << CST. */
10247 {
10254 }
10256 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10257 bits from CST2. */
10261 {
10263 wide_int masked
10270 {
10271 /* Avoid the transform if arg1 is a mask of some
10272 mode which allows further optimizations. */
10279 }
10280 }
10282 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10285 {
10290 return
10292 }
10297 /* Don't touch a floating-point divide by zero unless the mode
10298 of the constant can represent infinity. */
10304 /* (-A) / (-B) -> A / B */
10316 /* Fall through */
10319 /* Simplify A / (B << N) where A and B are positive and B is
10320 a power of 2, to A >> (N + log2(B)). */
10325 {
10328 {
10336 WARN_STRICT_OVERFLOW_MISC);
10342 }
10343 }
10345 /* Fall through */
10353 /* Convert -A / -B to A / B when the type is signed and overflow is
10354 undefined. */
10358 {
10361 "when distributing negation across "
10363 WARN_STRICT_OVERFLOW_MISC);
10368 }
10372 {
10375 "when distributing negation across "
10377 WARN_STRICT_OVERFLOW_MISC);
10382 }
10384 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10385 operation, EXACT_DIV_EXPR.
10387 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10388 At one time others generated faster code, it's not clear if they do
10389 after the last round to changes to the DIV code in expmed.c. */
10400 {
10404 WARN_STRICT_OVERFLOW_MISC);
10406 }
10418 {
10422 WARN_STRICT_OVERFLOW_MISC);
10424 }
10432 /* Since negative shift count is not well-defined,
10433 don't try to compute it in the compiler. */
10439 /* If we have a rotate of a bit operation with the rotate count and
10440 the second operand of the bit operation both constant,
10441 permute the two operations. */
10447 {
10455 }
10457 /* Two consecutive rotates adding up to the some integer
10458 multiple of the precision of the type can be ignored. */
10474 /* Note that the operands of this must be ints
10475 and their values must be 0 or 1.
10476 ("true" is a fixed value perhaps depending on the language.) */
10477 /* If first arg is constant zero, return it. */
10480 /* FALLTHRU */
10482 /* If either arg is constant true, drop it. */
10486 /* Preserve sequence points. */
10489 /* If second arg is constant zero, result is zero, but first arg
10490 must be evaluated. */
10493 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10494 case will be handled here. */
10498 /* !X && X is always false. */
10502 /* X && !X is always false. */
10507 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10508 means A >= Y && A != MAX, but in this case we know that
10509 A < X <= MAX. */
10513 {
10521 }
10530 /* Note that the operands of this must be ints
10531 and their values must be 0 or true.
10532 ("true" is a fixed value perhaps depending on the language.) */
10533 /* If first arg is constant true, return it. */
10536 /* FALLTHRU */
10538 /* If either arg is constant zero, drop it. */
10542 /* Preserve sequence points. */
10545 /* If second arg is constant true, result is true, but we must
10546 evaluate first arg. */
10549 /* Likewise for first arg, but note this only occurs here for
10550 TRUTH_OR_EXPR. */
10554 /* !X || X is always true. */
10558 /* X || !X is always true. */
10563 /* (X && !Y) || (!X && Y) is X ^ Y */
10566 {
10583 }
10592 /* If the second arg is constant zero, drop it. */
10595 /* If the second arg is constant true, this is a logical inversion. */
10597 {
10600 }
10601 /* Identical arguments cancel to zero. */
10605 /* !X ^ X is always true. */
10610 /* X ^ !X is always true. */
10626 /* bool_var != 1 becomes !bool_var. */
10633 /* bool_var == 0 becomes !bool_var. */
10640 /* !exp != 0 becomes !exp */
10645 /* If this is an EQ or NE comparison with zero and ARG0 is
10646 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10647 two operations, but the latter can be done in one less insn
10648 on machines that have only two-operand insns or on which a
10649 constant cannot be the first operand. */
10652 {
10657 {
10664 arg1);
10665 }
10668 {
10675 arg1);
10676 }
10677 }
10679 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10680 C1 is a valid shift constant, and C2 is a power of two, i.e.
10681 a single bit. */
10685 == INTEGER_CST
10688 {
10693 /* Check for a valid shift count. */
10695 {
10699 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10700 can be rewritten as (X & (C2 << C1)) != 0. */
10702 {
10707 }
10708 /* Otherwise, for signed (arithmetic) shifts,
10709 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10710 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10714 /* Otherwise, of unsigned (logical) shifts,
10715 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10716 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10717 else
10721 arg000);
10722 }
10723 }
10725 /* If this is a comparison of a field, we may be able to simplify it. */
10728 /* Handle the constant case even without -O
10729 to make sure the warnings are given. */
10731 {
10735 }
10737 /* Optimize comparisons of strlen vs zero to a compare of the
10738 first character of the string vs zero. To wit,
10739 strlen(ptr) == 0 => *ptr == 0
10740 strlen(ptr) != 0 => *ptr != 0
10741 Other cases should reduce to one of these two (or a constant)
10742 due to the return value of strlen being unsigned. */
10745 {
10752 {
10757 }
10758 }
10760 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10761 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10765 {
10770 {
10772 {
10775 }
10778 }
10779 }
10781 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10782 (X & C) == 0 when C is a single bit. */
10787 {
10794 arg1));
10795 }
10797 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10798 constant C is a power of two, i.e. a single bit. */
10805 {
10809 }
10811 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10812 when is C is a power of two, i.e. a single bit. */
10819 {
10825 }
10829 {
10832 }
10834 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10837 {
10845 {
10851 }
10853 {
10859 }
10861 {
10867 }
10869 {
10875 }
10876 }
10880 {
10887 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10888 operand_equal_p guarantees no side-effects so we don't need
10889 to use omit_one_operand on Z. */
10893 arg10));
10897 arg11));
10901 arg10));
10905 arg11));
10907 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10910 {
10916 }
10917 }
10919 /* Attempt to simplify equality/inequality comparisons of complex
10920 values. Only lower the comparison if the result is known or
10921 can be simplified to a single scalar comparison. */
10926 {
10931 {
10934 }
10935 else
10936 {
10939 }
10942 {
10945 }
10946 else
10947 {
10950 }
10954 {
10956 {
10961 }
10962 else
10963 {
10968 }
10969 }
10973 {
10975 {
10980 }
10981 else
10982 {
10987 }
10988 }
10989 }
11001 /* Transform comparisons of the form X +- C CMP X. */
11006 {
11011 /* (X - c) > X becomes false. */
11017 /* Likewise (X + c) < X becomes false. */
11023 /* Convert (X - c) <= X to true. */
11030 /* Convert (X + c) >= X to true. */
11036 }
11038 /* If we are comparing an ABS_EXPR with a constant, we can
11039 convert all the cases into explicit comparisons, but they may
11040 well not be faster than doing the ABS and one comparison.
11041 But ABS (X) <= C is a range comparison, which becomes a subtraction
11042 and a comparison, and is probably faster. */
11056 /* Convert ABS_EXPR<x> >= 0 to true. */
11063 {
11066 "when simplifying comparison of "
11068 WARN_STRICT_OVERFLOW_CONDITIONAL);
11071 arg0);
11072 }
11074 /* Convert ABS_EXPR<x> < 0 to false. */
11079 {
11082 "when simplifying comparison of "
11084 WARN_STRICT_OVERFLOW_CONDITIONAL);
11087 arg0);
11088 }
11090 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11091 and similarly for >= into !=. */
11101 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11102 otherwise Y might be >= # of bits in X's type and thus e.g.
11103 (unsigned char) (1 << Y) for Y 15 might be 0.
11104 If the cast is widening, then 1 << Y should have unsigned type,
11105 otherwise if Y is number of bits in the signed shift type minus 1,
11106 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11107 31 might be 0xffffffff80000000. */
11118 {
11124 }
11136 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11137 {
11149 }
11154 /* When pedantic, a compound expression can be neither an lvalue
11155 nor an integer constant expression. */
11158 /* Don't let (0, 0) be null pointer constant. */
11164 /* An ASSERT_EXPR should never be passed to fold_binary. */
11170 }
11172 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11173 ((A & N) + B) & M -> (A + B) & M
11174 Similarly if (N & M) == 0,
11175 ((A | N) + B) & M -> (A + B) & M
11176 and for - instead of + (or unary - instead of +)
11177 and/or ^ instead of |.
11178 If B is constant and (B & M) == 0, fold into A & M.
11180 This function is a helper for match.pd patterns. Return non-NULL
11181 type in which the simplified operation should be performed only
11182 if any optimization is possible.
11184 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11185 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11186 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11187 +/-. */
11188 tree
11193 {
11208 wide_int cst0;
11210 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11211 arg1 (M) is == (1LL << cst) - 1.
11212 Store C into PMOP[0] and D into PMOP[1]. */
11219 {
11226 {
11229 }
11232 /* If C or D is of the form (A & N) where
11233 (N & M) == M, or of the form (A | N) or
11234 (A ^ N) where (N & M) == 0, replace it with A. */
11240 /* If C or D is a N where (N & M) == 0, it can be
11241 omitted (replaced with 0). */
11246 /* Similarly, with C - N where (-N & M) == 0. */
11254 }
11256 /* Only build anything new if we optimized one or both arguments above. */
11262 else
11264 }
11266 /* Used by contains_label_[p1]. */
11268 struct contains_label_data
11269 {
11272 };
11274 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11275 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11276 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11278 static tree
11280 {
11283 {
11294 {
11302 }
11311 }
11312 }
11314 /* Return whether the sub-tree ST contains a label which is accessible from
11315 outside the sub-tree. */
11317 static bool
11319 {
11323 }
11325 /* Fold a ternary expression of code CODE and type TYPE with operands
11326 OP0, OP1, and OP2. Return the folded expression if folding is
11327 successful. Otherwise, return NULL_TREE. */
11329 tree
11332 {
11333 tree tem;
11340 /* If this is a commutative operation, and OP0 is a constant, move it
11341 to OP1 to reduce the number of tests below. */
11350 /* Strip any conversions that don't change the mode. This is safe
11351 for every expression, except for a comparison expression because
11352 its signedness is derived from its operands. So, in the latter
11353 case, only strip conversions that don't change the signedness.
11355 Note that this is done as an internal manipulation within the
11356 constant folder, in order to find the simplest representation of
11357 the arguments so that their form can be studied. In any cases,
11358 the appropriate type conversions should be put back in the tree
11359 that will get out of the constant folder. */
11361 {
11364 }
11367 {
11370 }
11373 {
11376 }
11379 {
11383 {
11389 }
11394 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11395 so all simple results must be passed through pedantic_non_lvalue. */
11397 {
11400 /* Only optimize constant conditions when the selected branch
11401 has the same type as the COND_EXPR. This avoids optimizing
11402 away "c ? x : throw", where the throw has a void type.
11403 Avoid throwing away that operand which contains label. */
11410 }
11412 {
11419 {
11422 {
11430 }
11435 }
11436 }
11438 /* If we have A op B ? A : C, we may be able to convert this to a
11439 simpler expression, depending on the operation and the values
11440 of B and C. Signed zeros prevent all of these transformations,
11441 for reasons given above each one.
11443 Also try swapping the arguments and inverting the conditional. */
11447 {
11451 }
11456 {
11460 {
11464 }
11465 }
11467 /* If the second operand is simpler than the third, swap them
11468 since that produces better jump optimization results. */
11471 {
11473 /* See if this can be inverted. If it can't, possibly because
11474 it was a floating-point inequality comparison, don't do
11475 anything. */
11479 }
11481 /* Convert A ? 1 : 0 to simply A. */
11486 /* If we try to convert OP0 to our type, the
11487 call to fold will try to move the conversion inside
11488 a COND, which will recurse. In that case, the COND_EXPR
11489 is probably the best choice, so leave it alone. */
11493 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11494 over COND_EXPR in cases such as floating point comparisons. */
11503 arg0)));
11505 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11510 {
11511 /* sign_bit_p looks through both zero and sign extensions,
11512 but for this optimization only sign extensions are
11513 usable. */
11516 {
11519 {
11522 }
11524 }
11525 /* sign_bit_p only checks ARG1 bits within A's precision.
11526 If <sign bit of A> has wider type than A, bits outside
11527 of A's precision in <sign bit of A> need to be checked.
11528 If they are all 0, this optimization needs to be done
11529 in unsigned A's type, if they are all 1 in signed A's type,
11530 otherwise this can't be done. */
11536 {
11538 tree tem_type;
11551 {
11554 }
11556 {
11559 }
11560 else
11562 }
11565 return
11571 arg1)));
11572 }
11574 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11575 already handled above. */
11580 {
11590 op1);
11591 }
11593 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11594 is probably obsolete because the first operand should be a
11595 truth value (that's why we have the two cases above), but let's
11596 leave it in until we can confirm this for all front-ends. */
11604 /* operand_equal_p compares just value, not precision, so e.g.
11605 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
11606 second operand 32-bit -128, which is not a power of two (or vice
11607 versa. */
11614 /* Disable the transformations below for vectors, since
11615 fold_binary_op_with_conditional_arg may undo them immediately,
11616 yielding an infinite loop. */
11620 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11629 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11634 {
11636 /* Only perform transformation if ARG0 is easily inverted. */
11640 ? BIT_IOR_EXPR
11643 op1);
11644 }
11646 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11651 {
11653 /* Only perform transformation if ARG0 is easily inverted. */
11659 op2);
11660 }
11662 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11674 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11675 of fold_ternary on them. */
11685 {
11696 {
11701 {
11703 {
11708 }
11714 }
11715 }
11716 }
11718 /* On constants we can use native encode/interpret to constant
11719 fold (nearly) all BIT_FIELD_REFs. */
11725 {
11728 /* Limit us to a reasonable amount of work. To relax the
11729 other limitations we need bit-shifting of the buffer
11730 and rounding up the size. */
11734 {
11736 unsigned HOST_WIDE_INT len
11741 {
11746 }
11747 }
11748 }
11754 {
11755 /* Build a vector of integers from the tree mask. */
11756 vec_perm_builder builder;
11760 /* Create a vec_perm_indices for the integer vector. */
11765 /* Check for cases that fold to OP0 or OP1 in their original
11766 element order. */
11773 {
11777 {
11780 }
11781 }
11787 {
11791 }
11795 /* Generate a canonical form of the selector. */
11797 {
11798 /* Some targets are deficient and fail to expand a single
11799 argument permutation while still allowing an equivalent
11800 2-argument version. */
11804 else
11805 {
11809 else
11810 /* Not directly supported with either encoding,
11811 so use the preferred form. */
11813 }
11815 }
11819 }
11823 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11826 {
11832 wide_int tem2
11836 }
11841 {
11843 unsigned HOST_WIDE_INT elsize
11846 {
11852 {
11858 }
11859 }
11860 }
11866 }
11868 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11869 of an array (or vector). */
11871 tree
11873 {
11878 {
11881 {
11882 /* Static constructors for variably sized objects makes no sense. */
11886 }
11887 }
11898 offset_int max_index;
11903 {
11904 /* Array constructor might explicitly set index, or specify a range,
11905 or leave index NULL meaning that it is next index after previous
11906 one. */
11908 {
11911 else
11912 {
11916 }
11917 }
11918 else
11919 {
11925 }
11927 /* Do we have match? */
11931 }
11933 }
11935 /* Perform constant folding and related simplification of EXPR.
11936 The related simplifications include x*1 => x, x*0 => 0, etc.,
11937 and application of the associative law.
11938 NOP_EXPR conversions may be removed freely (as long as we
11939 are careful not to change the type of the overall expression).
11940 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11941 but we can constant-fold them if they have constant operands. */
11943 #ifdef ENABLE_FOLD_CHECKING
11944 # define fold(x) fold_1 (x)
11946 static
11947 #endif
11948 tree
11950 {
11954 tree tem;
11957 /* Return right away if a constant. */
11961 /* CALL_EXPR-like objects with variable numbers of operands are
11962 treated specially. */
11964 {
11966 {
11969 }
11971 }
11974 {
11979 {
11997 }
11998 }
12001 {
12003 {
12010 {
12015 }
12018 }
12020 /* Return a VECTOR_CST if possible. */
12022 {
12028 tree val;
12034 }
12042 }
12044 #ifdef ENABLE_FOLD_CHECKING
12045 #undef fold
12052 /* When --enable-checking=fold, compute a digest of expr before
12053 and after actual fold call to see if fold did not accidentally
12054 change original expr. */
12056 tree
12058 {
12059 tree ret;
12079 }
12081 void
12083 {
12094 }
12096 static void
12098 {
12100 }
12102 static void
12105 {
12111 recursive_label:
12121 {
12122 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12127 }
12135 {
12136 /* Allow these fields to be modified. */
12137 tree tmp;
12146 {
12149 }
12150 }
12161 {
12164 {
12180 }
12184 {
12197 }
12214 {
12220 }
12223 {
12225 {
12228 }
12230 }
12241 {
12244 }
12254 }
12255 }
12257 /* Helper function for outputting the checksum of a tree T. When
12258 debugging with gdb, you can "define mynext" to be "next" followed
12259 by "call debug_fold_checksum (op0)", then just trace down till the
12260 outputs differ. */
12262 DEBUG_FUNCTION void
12264 {
12279 }
12281 #endif
12283 /* Fold a unary tree expression with code CODE of type TYPE with an
12284 operand OP0. LOC is the location of the resulting expression.
12285 Return a folded expression if successful. Otherwise, return a tree
12286 expression with code CODE of type TYPE with an operand OP0. */
12288 tree
12291 {
12292 tree tem;
12293 #ifdef ENABLE_FOLD_CHECKING
12302 #endif
12308 #ifdef ENABLE_FOLD_CHECKING
12315 #endif
12317 }
12319 /* Fold a binary tree expression with code CODE of type TYPE with
12320 operands OP0 and OP1. LOC is the location of the resulting
12321 expression. Return a folded expression if successful. Otherwise,
12322 return a tree expression with code CODE of type TYPE with operands
12323 OP0 and OP1. */
12325 tree
12328 MEM_STAT_DECL)
12329 {
12330 tree tem;
12331 #ifdef ENABLE_FOLD_CHECKING
12348 #endif
12354 #ifdef ENABLE_FOLD_CHECKING
12369 #endif
12371 }
12373 /* Fold a ternary tree expression with code CODE of type TYPE with
12374 operands OP0, OP1, and OP2. Return a folded expression if
12375 successful. Otherwise, return a tree expression with code CODE of
12376 type TYPE with operands OP0, OP1, and OP2. */
12378 tree
12381 {
12382 tree tem;
12383 #ifdef ENABLE_FOLD_CHECKING
12407 #endif
12414 #ifdef ENABLE_FOLD_CHECKING
12437 #endif
12439 }
12441 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12442 arguments in ARGARRAY, and a null static chain.
12443 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12444 of type TYPE from the given operands as constructed by build_call_array. */
12446 tree
12449 {
12450 tree tem;
12451 #ifdef ENABLE_FOLD_CHECKING
12470 #endif
12476 #ifdef ENABLE_FOLD_CHECKING
12492 #endif
12494 }
12496 /* Perform constant folding and related simplification of initializer
12497 expression EXPR. These behave identically to "fold_buildN" but ignore
12498 potential run-time traps and exceptions that fold must preserve. */
12500 #define START_FOLD_INIT \
12501 int saved_signaling_nans = flag_signaling_nans;\
12502 int saved_trapping_math = flag_trapping_math;\
12503 int saved_rounding_math = flag_rounding_math;\
12504 int saved_trapv = flag_trapv;\
12505 int saved_folding_initializer = folding_initializer;\
12506 flag_signaling_nans = 0;\
12507 flag_trapping_math = 0;\
12508 flag_rounding_math = 0;\
12509 flag_trapv = 0;\
12510 folding_initializer = 1;
12512 #define END_FOLD_INIT \
12513 flag_signaling_nans = saved_signaling_nans;\
12514 flag_trapping_math = saved_trapping_math;\
12515 flag_rounding_math = saved_rounding_math;\
12516 flag_trapv = saved_trapv;\
12517 folding_initializer = saved_folding_initializer;
12519 tree
12522 {
12523 tree result;
12524 START_FOLD_INIT;
12528 END_FOLD_INIT;
12530 }
12532 tree
12535 {
12536 tree result;
12537 START_FOLD_INIT;
12541 END_FOLD_INIT;
12543 }
12545 tree
12548 {
12549 tree result;
12550 START_FOLD_INIT;
12554 END_FOLD_INIT;
12556 }
12558 #undef START_FOLD_INIT
12559 #undef END_FOLD_INIT
12561 /* Determine if first argument is a multiple of second argument. Return 0 if
12562 it is not, or we cannot easily determined it to be.
12564 An example of the sort of thing we care about (at this point; this routine
12565 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12566 fold cases do now) is discovering that
12568 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12570 is a multiple of
12572 SAVE_EXPR (J * 8)
12574 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12576 This code also handles discovering that
12578 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12580 is a multiple of 8 so we don't have to worry about dealing with a
12581 possible remainder.
12583 Note that we *look* inside a SAVE_EXPR only to determine how it was
12584 calculated; it is not safe for fold to do much of anything else with the
12585 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12586 at run time. For example, the latter example above *cannot* be implemented
12587 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12588 evaluation time of the original SAVE_EXPR is not necessarily the same at
12589 the time the new expression is evaluated. The only optimization of this
12590 sort that would be valid is changing
12592 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12594 divided by 8 to
12596 SAVE_EXPR (I) * SAVE_EXPR (J)
12598 (where the same SAVE_EXPR (J) is used in the original and the
12599 transformed version). */
12601 int
12603 {
12614 {
12616 /* Bitwise and provides a power of two multiple. If the mask is
12617 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12625 {
12631 {
12634 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12636 {
12640 {
12643 }
12644 }
12646 }
12647 }
12652 /* It is impossible to prove if op0 - op1 is multiple of bottom
12653 precisely, so be conservative here checking if both op0 and op1
12654 are multiple of bottom. Note we check the second operand first
12655 since it's usually simpler. */
12660 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12661 as op0 - 3 if the expression has unsigned type. For example,
12662 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12672 {
12674 /* const_binop may not detect overflow correctly,
12675 so check for it explicitly here. */
12683 }
12687 /* Can't handle conversions from non-integral or wider integral type. */
12693 /* fall through */
12710 SIGNED);
12716 {
12719 /* Check for special cases to see if top is defined as multiple
12720 of bottom:
12722 top = (X & ~(bottom - 1) ; bottom is power of 2
12724 or
12726 Y = X % bottom
12727 top = X - Y. */
12746 }
12748 /* fall through */
12756 }
12757 }
12759 #define tree_expr_nonnegative_warnv_p(X, Y) \
12762 #define RECURSE(X) \
12763 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12765 /* Return true if CODE or TYPE is known to be non-negative. */
12767 static bool
12769 {
12772 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12773 have a signed:1 type (where the value is -1 and 0). */
12776 }
12778 /* Return true if (CODE OP0) is known to be non-negative. If the return
12779 value is based on the assumption that signed overflow is undefined,
12780 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12781 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12783 bool
12786 {
12791 {
12793 /* We can't return 1 if flag_wrapv is set because
12794 ABS_EXPR<INT_MIN> = INT_MIN. */
12798 {
12801 }
12809 CASE_CONVERT:
12810 {
12815 {
12819 {
12823 }
12824 }
12826 {
12832 }
12833 }
12838 }
12840 /* We don't know sign of `t', so be conservative and return false. */
12842 }
12844 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12845 value is based on the assumption that signed overflow is undefined,
12846 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12847 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12849 bool
12853 {
12858 {
12864 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12865 both unsigned and at least 2 bits shorter than the result. */
12869 {
12874 {
12878 }
12879 }
12884 {
12885 /* x * x is always non-negative for floating point x
12886 or without overflow. */
12889 {
12894 }
12895 }
12897 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12898 both unsigned and their total bits is shorter than the result. */
12902 {
12921 {
12931 }
12932 }
12959 }
12961 /* We don't know sign of `t', so be conservative and return false. */
12963 }
12965 /* Return true if T is known to be non-negative. If the return
12966 value is based on the assumption that signed overflow is undefined,
12967 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12968 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12970 bool
12972 {
12977 {
12991 /* Limit the depth of recursion to avoid quadratic behavior.
12992 This is expected to catch almost all occurrences in practice.
12993 If this code misses important cases that unbounded recursion
12994 would not, passes that need this information could be revised
12995 to provide it through dataflow propagation. */
13003 }
13004 }
13006 /* Return true if T is known to be non-negative. If the return
13007 value is based on the assumption that signed overflow is undefined,
13008 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13009 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13011 bool
13014 {
13016 {
13017 CASE_CFN_ACOS:
13018 CASE_CFN_ACOSH:
13019 CASE_CFN_CABS:
13020 CASE_CFN_COSH:
13021 CASE_CFN_ERFC:
13022 CASE_CFN_EXP:
13023 CASE_CFN_EXP10:
13024 CASE_CFN_EXP2:
13025 CASE_CFN_FABS:
13026 CASE_CFN_FDIM:
13027 CASE_CFN_HYPOT:
13028 CASE_CFN_POW10:
13029 CASE_CFN_FFS:
13030 CASE_CFN_PARITY:
13031 CASE_CFN_POPCOUNT:
13032 CASE_CFN_CLZ:
13033 CASE_CFN_CLRSB:
13036 /* Always true. */
13039 CASE_CFN_SQRT:
13040 CASE_CFN_SQRT_FN:
13041 /* sqrt(-0.0) is -0.0. */
13046 CASE_CFN_ASINH:
13047 CASE_CFN_ATAN:
13048 CASE_CFN_ATANH:
13049 CASE_CFN_CBRT:
13050 CASE_CFN_CEIL:
13051 CASE_CFN_CEIL_FN:
13052 CASE_CFN_ERF:
13053 CASE_CFN_EXPM1:
13054 CASE_CFN_FLOOR:
13055 CASE_CFN_FLOOR_FN:
13056 CASE_CFN_FMOD:
13057 CASE_CFN_FREXP:
13058 CASE_CFN_ICEIL:
13059 CASE_CFN_IFLOOR:
13060 CASE_CFN_IRINT:
13061 CASE_CFN_IROUND:
13062 CASE_CFN_LCEIL:
13063 CASE_CFN_LDEXP:
13064 CASE_CFN_LFLOOR:
13065 CASE_CFN_LLCEIL:
13066 CASE_CFN_LLFLOOR:
13067 CASE_CFN_LLRINT:
13068 CASE_CFN_LLROUND:
13069 CASE_CFN_LRINT:
13070 CASE_CFN_LROUND:
13071 CASE_CFN_MODF:
13072 CASE_CFN_NEARBYINT:
13073 CASE_CFN_NEARBYINT_FN:
13074 CASE_CFN_RINT:
13075 CASE_CFN_RINT_FN:
13076 CASE_CFN_ROUND:
13077 CASE_CFN_ROUND_FN:
13078 CASE_CFN_SCALB:
13079 CASE_CFN_SCALBLN:
13080 CASE_CFN_SCALBN:
13081 CASE_CFN_SIGNBIT:
13082 CASE_CFN_SIGNIFICAND:
13083 CASE_CFN_SINH:
13084 CASE_CFN_TANH:
13085 CASE_CFN_TRUNC:
13086 CASE_CFN_TRUNC_FN:
13087 /* True if the 1st argument is nonnegative. */
13090 CASE_CFN_FMAX:
13091 CASE_CFN_FMAX_FN:
13092 /* True if the 1st OR 2nd arguments are nonnegative. */
13095 CASE_CFN_FMIN:
13096 CASE_CFN_FMIN_FN:
13097 /* True if the 1st AND 2nd arguments are nonnegative. */
13100 CASE_CFN_COPYSIGN:
13101 CASE_CFN_COPYSIGN_FN:
13102 /* True if the 2nd argument is nonnegative. */
13105 CASE_CFN_POWI:
13106 /* True if the 1st argument is nonnegative or the second
13107 argument is an even integer. */
13113 CASE_CFN_POW:
13114 /* True if the 1st argument is nonnegative or the second
13115 argument is an even integer valued real. */
13117 {
13118 REAL_VALUE_TYPE c;
13119 HOST_WIDE_INT n;
13124 {
13125 REAL_VALUE_TYPE cint;
13129 }
13130 }
13135 }
13137 }
13139 /* Return true if T is known to be non-negative. If the return
13140 value is based on the assumption that signed overflow is undefined,
13141 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13142 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13144 static bool
13146 {
13152 {
13154 {
13158 /* If the initializer is non-void, then it's a normal expression
13159 that will be assigned to the slot. */
13163 /* Otherwise, the initializer sets the slot in some way. One common
13164 way is an assignment statement at the end of the initializer. */
13166 {
13174 else
13176 }
13182 }
13185 {
13191 arg0,
13192 arg1,
13194 }
13207 }
13208 }
13210 #undef RECURSE
13211 #undef tree_expr_nonnegative_warnv_p
13213 /* Return true if T is known to be non-negative. If the return
13214 value is based on the assumption that signed overflow is undefined,
13215 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13216 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13218 bool
13220 {
13227 {
13249 }
13252 {
13278 }
13279 }
13281 /* Return true if `t' is known to be non-negative. Handle warnings
13282 about undefined signed overflow. */
13284 bool
13286 {
13293 "determining that expression is always "
13295 WARN_STRICT_OVERFLOW_MISC);
13297 }
13300 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13301 For floating point we further ensure that T is not denormal.
13302 Similar logic is present in nonzero_address in rtlanal.h.
13304 If the return value is based on the assumption that signed overflow
13305 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13306 change *STRICT_OVERFLOW_P. */
13308 bool
13311 {
13313 {
13316 strict_overflow_p);
13319 {
13325 strict_overflow_p));
13326 }
13331 strict_overflow_p);
13335 }
13338 }
13340 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13341 For floating point we further ensure that T is not denormal.
13342 Similar logic is present in nonzero_address in rtlanal.h.
13344 If the return value is based on the assumption that signed overflow
13345 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13346 change *STRICT_OVERFLOW_P. */
13348 bool
13350 tree type,
13351 tree op0,
13353 {
13356 {
13360 {
13361 /* With the presence of negative values it is hard
13362 to say something. */
13369 /* One of operands must be positive and the other non-negative. */
13370 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13371 overflows, on a twos-complement machine the sum of two
13372 nonnegative numbers can never be zero. */
13374 strict_overflow_p)
13376 strict_overflow_p));
13377 }
13382 {
13384 strict_overflow_p)
13386 strict_overflow_p))
13387 {
13390 }
13391 }
13400 {
13403 }
13410 {
13414 /* When both operands are nonzero, then MAX must be too. */
13416 strict_overflow_p))
13419 /* MAX where operand 0 is positive is positive. */
13421 strict_overflow_p);
13422 }
13423 /* MAX where operand 1 is positive is positive. */
13428 {
13432 }
13437 strict_overflow_p)
13439 strict_overflow_p));
13443 }
13446 }
13448 /* Return true when T is an address and is known to be nonzero.
13449 For floating point we further ensure that T is not denormal.
13450 Similar logic is present in nonzero_address in rtlanal.h.
13452 If the return value is based on the assumption that signed overflow
13453 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13454 change *STRICT_OVERFLOW_P. */
13456 bool
13458 {
13461 {
13466 {
13478 /* For objects in symbol table check if we know they are non-zero.
13479 Don't do anything for variables and functions before symtab is built;
13480 it is quite possible that they will be declared weak later. */
13485 /* Constants are never weak. */
13490 }
13498 {
13502 }
13512 }
13514 }
13516 #define integer_valued_real_p(X) \
13519 #define RECURSE(X) \
13520 ((integer_valued_real_p) (X, depth + 1))
13522 /* Return true if the floating point result of (CODE OP0) has an
13523 integer value. We also allow +Inf, -Inf and NaN to be considered
13524 integer values. Return false for signaling NaN.
13526 DEPTH is the current nesting depth of the query. */
13528 bool
13530 {
13532 {
13539 CASE_CONVERT:
13540 {
13547 }
13551 }
13553 }
13555 /* Return true if the floating point result of (CODE OP0 OP1) has an
13556 integer value. We also allow +Inf, -Inf and NaN to be considered
13557 integer values. Return false for signaling NaN.
13559 DEPTH is the current nesting depth of the query. */
13561 bool
13563 {
13565 {
13575 }
13577 }
13579 /* Return true if the floating point result of calling FNDECL with arguments
13580 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13581 considered integer values. Return false for signaling NaN. If FNDECL
13582 takes fewer than 2 arguments, the remaining ARGn are null.
13584 DEPTH is the current nesting depth of the query. */
13586 bool
13588 {
13590 {
13591 CASE_CFN_CEIL:
13592 CASE_CFN_CEIL_FN:
13593 CASE_CFN_FLOOR:
13594 CASE_CFN_FLOOR_FN:
13595 CASE_CFN_NEARBYINT:
13596 CASE_CFN_NEARBYINT_FN:
13597 CASE_CFN_RINT:
13598 CASE_CFN_RINT_FN:
13599 CASE_CFN_ROUND:
13600 CASE_CFN_ROUND_FN:
13601 CASE_CFN_TRUNC:
13602 CASE_CFN_TRUNC_FN:
13605 CASE_CFN_FMIN:
13606 CASE_CFN_FMIN_FN:
13607 CASE_CFN_FMAX:
13608 CASE_CFN_FMAX_FN:
13613 }
13615 }
13617 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13618 has an integer value. We also allow +Inf, -Inf and NaN to be
13619 considered integer values. Return false for signaling NaN.
13621 DEPTH is the current nesting depth of the query. */
13623 bool
13625 {
13627 {
13635 /* Limit the depth of recursion to avoid quadratic behavior.
13636 This is expected to catch almost all occurrences in practice.
13637 If this code misses important cases that unbounded recursion
13638 would not, passes that need this information could be revised
13639 to provide it through dataflow propagation. */
13643 depth));
13647 }
13649 }
13651 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13652 has an integer value. We also allow +Inf, -Inf and NaN to be
13653 considered integer values. Return false for signaling NaN.
13655 DEPTH is the current nesting depth of the query. */
13657 static bool
13659 {
13661 {
13672 }
13674 }
13676 #undef RECURSE
13677 #undef integer_valued_real_p
13679 /* Return true if the floating point expression T has an integer value.
13680 We also allow +Inf, -Inf and NaN to be considered integer values.
13681 Return false for signaling NaN.
13683 DEPTH is the current nesting depth of the query. */
13685 bool
13687 {
13695 {
13711 }
13714 {
13720 {
13729 }
13733 }
13734 }
13736 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13737 attempt to fold the expression to a constant without modifying TYPE,
13738 OP0 or OP1.
13740 If the expression could be simplified to a constant, then return
13741 the constant. If the expression would not be simplified to a
13742 constant, then return NULL_TREE. */
13744 tree
13746 {
13749 }
13751 /* Given the components of a unary expression CODE, TYPE and OP0,
13752 attempt to fold the expression to a constant without modifying
13753 TYPE or OP0.
13755 If the expression could be simplified to a constant, then return
13756 the constant. If the expression would not be simplified to a
13757 constant, then return NULL_TREE. */
13759 tree
13761 {
13764 }
13766 /* If EXP represents referencing an element in a constant string
13767 (either via pointer arithmetic or array indexing), return the
13768 tree representing the value accessed, otherwise return NULL. */
13770 tree
13772 {
13776 {
13778 tree index;
13779 tree string;
13784 else
13785 {
13789 /* Optimize the special-case of a zero lower bound.
13791 We convert the low_bound to sizetype to avoid some problems
13792 with constant folding. (E.g. suppose the lower bound is 1,
13793 and its mode is QI. Without the conversion,l (ARRAY
13794 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13795 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13801 }
13803 scalar_int_mode char_mode;
13815 }
13817 }
13819 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13820 an integer constant, real, or fixed-point constant.
13822 TYPE is the type of the result. */
13824 static tree
13826 {
13830 {
13836 {
13837 FIXED_VALUE_TYPE f;
13842 /* Propagate overflow flags. */
13846 }
13850 {
13857 }
13860 }
13863 }
13865 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13866 an integer constant or real constant.
13868 TYPE is the type of the result. */
13870 tree
13872 {
13876 {
13878 {
13879 /* If the value is unsigned or non-negative, then the absolute value
13880 is the same as the ordinary value. */
13884 ;
13886 /* If the value is negative, then the absolute value is
13887 its negation. */
13888 else
13891 /* Force to the destination type, set TREE_OVERFLOW for signed
13892 TYPE only. */
13894 }
13900 else
13906 }
13909 }
13911 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13912 constant. TYPE is the type of the result. */
13914 static tree
13916 {
13920 }
13922 /* Given CODE, a relational operator, the target type, TYPE and two
13923 constant operands OP0 and OP1, return the result of the
13924 relational operation. If the result is not a compile time
13925 constant, then return NULL_TREE. */
13927 static tree
13929 {
13932 /* From here on, the only cases we handle are when the result is
13933 known to be a constant. */
13936 {
13940 /* Handle the cases where either operand is a NaN. */
13942 {
13944 {
13972 }
13975 }
13978 }
13981 {
13985 }
13987 /* Handle equality/inequality of complex constants. */
13989 {
14000 else
14002 }
14005 {
14007 {
14008 /* Have vector comparison with scalar boolean result. */
14016 {
14024 }
14026 }
14027 tree_vector_builder elts;
14032 {
14045 }
14048 }
14050 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14052 To compute GT, swap the arguments and do LT.
14053 To compute GE, do LT and invert the result.
14054 To compute LE, swap the arguments, do LT and invert the result.
14055 To compute NE, do EQ and invert the result.
14057 Therefore, the code below must handle only EQ and LT. */
14060 {
14063 }
14065 /* Note that it is safe to invert for real values here because we
14066 have already handled the one case that it matters. */
14070 {
14073 }
14075 /* Compute a result for LT or EQ if args permit;
14076 Otherwise return T. */
14078 {
14081 else
14083 }
14084 else
14090 }
14092 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14093 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14094 itself. */
14096 tree
14098 {
14099 /* If the expression does not have side effects then we don't have to wrap
14100 it with a cleanup point expression. */
14104 /* If the expression is a return, check to see if the expression inside the
14105 return has no side effects or the right hand side of the modify expression
14106 inside the return. If either don't have side effects set we don't need to
14107 wrap the expression in a cleanup point expression. Note we don't check the
14108 left hand side of the modify because it should always be a return decl. */
14110 {
14117 }
14120 }
14122 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14123 of an indirection through OP0, or NULL_TREE if no simplification is
14124 possible. */
14126 tree
14128 {
14130 tree subtype;
14131 poly_uint64 const_op01;
14140 {
14144 /* *&CONST_DECL -> to the value of the const decl. */
14147 /* *&p => p; make sure to handle *&"str"[cst] here. */
14149 {
14153 else
14155 }
14156 /* *(foo *)&fooarray => fooarray[0] */
14159 && (!in_gimple_form
14161 {
14171 }
14172 /* *(foo *)&complexfoo => __real__ complexfoo */
14176 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14179 {
14183 index);
14184 }
14185 }
14189 {
14195 {
14196 tree op00type;
14200 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14203 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14204 but we want to treat offsets with MSB set as negative.
14205 For the code below negative offsets are invalid and
14206 TYPE_SIZE of the element is something unsigned, so
14207 check whether op01 fits into poly_int64, which implies
14208 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14209 then just use poly_uint64 because we want to treat the
14210 value as unsigned. */
14212 {
14214 poly_uint64 max_offset
14218 {
14223 }
14224 }
14225 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14228 {
14230 const_op01))
14232 }
14233 /* ((foo *)&fooarray)[1] => fooarray[1] */
14236 {
14245 {
14250 }
14251 }
14252 }
14253 }
14255 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14258 && (!in_gimple_form
14260 {
14261 tree type_domain;
14271 NULL_TREE);
14272 }
14275 }
14277 /* Builds an expression for an indirection through T, simplifying some
14278 cases. */
14280 tree
14282 {
14290 }
14292 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14294 tree
14296 {
14301 else
14303 }
14305 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14306 whose result is ignored. The type of the returned tree need not be
14307 the same as the original expression. */
14309 tree
14311 {
14317 {
14328 else
14334 {
14350 }
14355 }
14356 }
14358 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14360 tree
14362 {
14368 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14369 have to do anything. Only do this when we are not given a const,
14370 because in that case, this check is more expensive than just
14371 doing it. */
14373 {
14378 }
14380 /* If divisor is a power of two, simplify this to bit manipulation. */
14382 {
14384 {
14398 }
14399 else
14400 {
14401 tree t;
14407 }
14408 }
14409 else
14410 {
14415 }
14418 }
14420 /* Likewise, but round down. */
14422 tree
14424 {
14431 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14432 have to do anything. Only do this when we are not given a const,
14433 because in that case, this check is more expensive than just
14434 doing it. */
14436 {
14441 }
14443 /* If divisor is a power of two, simplify this to bit manipulation. */
14445 {
14446 tree t;
14450 }
14451 else
14452 {
14457 }
14460 }
14462 /* Returns the pointer to the base of the object addressed by EXP and
14463 extracts the information about the offset of the access, storing it
14464 to PBITPOS and POFFSET. */
14466 static tree
14469 {
14470 tree core;
14471 machine_mode mode;
14473 poly_int64 bitsize;
14477 {
14482 }
14484 {
14490 {
14491 poly_offset_int tem
14497 }
14498 }
14499 else
14500 {
14504 }
14507 }
14509 /* Returns true if addresses of E1 and E2 differ by a constant, false
14510 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14512 bool
14514 {
14529 {
14539 }
14541 {
14542 /* If only one of the offsets is non-constant, the difference cannot
14543 be a constant. */
14545 }
14546 else
14551 }
14553 /* Return OFF converted to a pointer offset type suitable as offset for
14554 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14555 tree
14557 {
14559 }
14561 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14562 tree
14564 {
14567 }
14569 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14570 tree
14572 {
14575 }
14577 /* Return a pointer P to a NUL-terminated string representing the sequence
14578 of constant characters referred to by SRC (or a subsequence of such
14579 characters within it if SRC is a reference to a string plus some
14580 constant offset). If STRLEN is non-null, store the number of bytes
14581 in the string constant including the terminating NUL char. *STRLEN is
14582 typically strlen(P) + 1 in the absence of embedded NUL characters. */
14586 {
14587 tree offset_node;
14588 tree mem_size;
14599 {
14602 else
14604 }
14609 /* STRING_LENGTH is the size of the string literal, including any
14610 embedded NULs. STRING_SIZE is the size of the array the string
14611 literal is stored in. */
14615 /* Ideally this would turn into a gcc_checking_assert over time. */
14621 /* Ideally this would turn into a gcc_checking_assert over time. */
14630 {
14631 /* Compute and store the length of the substring at OFFSET.
14632 All offsets past the initial length refer to null strings. */
14635 else
14637 }
14638 else
14639 {
14641 /* Support only properly NUL-terminated single byte strings. */
14646 }
14649 }
14651 /* Given a tree T, compute which bits in T may be nonzero. */
14653 wide_int
14655 {
14657 {
14675 CASE_CONVERT:
14681 {
14686 }
14690 {
14698 }
14702 {
14710 }
14714 }
14717 }
14719 #if CHECKING_P
14723 /* Helper functions for writing tests of folding trees. */
14725 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14727 static void
14729 tree constant)
14730 {
14732 }
14734 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14735 wrapping WRAPPED_EXPR. */
14737 static void
14739 tree wrapped_expr)
14740 {
14745 }
14747 /* Verify that various arithmetic binary operations are folded
14748 correctly. */
14750 static void
14752 {
14758 /* Addition. */
14759 /* 1 <-- (0 + 1) */
14761 one);
14763 one);
14765 /* (nonlvalue)x <-- (x + 0) */
14767 x);
14769 /* Subtraction. */
14770 /* 0 <-- (x - x) */
14772 zero);
14774 x);
14776 /* Multiplication. */
14777 /* 0 <-- (x * 0) */
14779 zero);
14781 /* (nonlvalue)x <-- (x * 1) */
14783 x);
14784 }
14786 /* Verify that various binary operations on vectors are folded
14787 correctly. */
14789 static void
14791 {
14797 /* Verify equality tests that return a scalar boolean result. */
14803 }
14805 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14807 static void
14809 {
14812 /* This will be 1 if VEC_MODE isn't a vector mode. */
14819 }
14821 /* Run all of the selftests within this file. */
14823 void
14825 {
14829 }