| blob | 0ca472d422fd3f9b778c3cace51135eae74fb2fc |
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 {
1176 poly_wide_int poly_res;
1182 {
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 {
2945 /* When checking, verify at the outermost operand_equal_p call that
2946 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2947 hash value. */
2949 {
2951 {
2953 {
2960 }
2962 }
2963 else
2965 }
2970 /* If either is ERROR_MARK, they aren't equal. */
2976 /* Similar, if either does not have a type (like a template id),
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 {
3224 {
3228 /* Verify that the access types are compatible. */
3232 }
3237 /* Require the same offset. */
3243 /* Fallthru. */
3251 {
3252 /* Require equal access sizes */
3258 flags)))
3260 /* Verify that access happens in similar types. */
3263 /* Verify that accesses are TBAA compatible. */
3272 /* Verify that alignment is compatible. */
3276 }
3279 /* TARGET_MEM_REF require equal extra operands. */
3290 /* Compare the array index by value if it is constant first as we
3291 may have different types but same value here. */
3297 /* Compare low bound and element size as with OEP_ADDRESS_OF
3298 we have to account for the offset of the ref. */
3303 array_ref_low_bound
3307 array_ref_element_size
3309 flags))));
3312 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3313 may be NULL when we're called to compare MEM_EXPRs. */
3328 }
3332 {
3334 /* Be sure we pass right ADDRESS_OF flag. */
3351 /* The multiplcation operands are commutative. */
3352 /* FALLTHRU */
3360 /* Otherwise take into account this is a commutative operation. */
3373 /* BIT_INSERT_EXPR has an implict operand as the type precision
3374 of op1. Need to check to make sure they are the same. */
3380 /* FALLTHRU */
3406 }
3410 {
3414 /* If not both CALL_EXPRs are either internal or normal function
3415 functions, then they are not equal. */
3418 {
3419 /* If the CALL_EXPRs call different internal functions, then they
3420 are not equal. */
3423 }
3424 else
3425 {
3426 /* If the CALL_EXPRs call different functions, then they are not
3427 equal. */
3429 flags))
3431 }
3433 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3434 {
3438 else
3442 }
3444 /* Now see if all the arguments are the same. */
3445 {
3456 /* If we get here and both argument lists are exhausted
3457 then the CALL_EXPRs are equal. */
3459 }
3462 }
3465 /* Consider __builtin_sqrt equal to sqrt. */
3473 {
3474 /* In GIMPLE constructors are used only to build vectors from
3475 elements. Individual elements in the constructor must be
3476 indexed in increasing order and form an initial sequence.
3478 We make no effort to compare constructors in generic.
3479 (see sem_variable::equals in ipa-icf which can do so for
3480 constants). */
3485 /* Be sure that vectors constructed have the same representation.
3486 We only tested element precision and modes to match.
3487 Vectors may be BLKmode and thus also check that the number of
3488 parts match. */
3501 {
3506 /* In GIMPLE the indexes can be either NULL or matching i.
3507 Double check this so we won't get false
3508 positives for GENERIC. */
3516 }
3518 }
3521 {
3522 /* Compare the STATEMENT_LISTs. */
3528 {
3529 /* The lists don't have the same number of statements. */
3535 flags & (OEP_LEXICOGRAPHIC
3538 }
3539 }
3544 {
3555 }
3559 }
3561 #undef OP_SAME
3562 #undef OP_SAME_WITH_NULL
3563 }
3564 \f
3565 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3566 with a different signedness or a narrower precision. */
3568 static bool
3570 {
3578 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3579 and see if the inner values are the same. This removes any
3580 signedness comparison, which doesn't matter here. */
3588 /* Discard a single widening conversion from ARG1 and see if the inner
3589 value is the same as ARG0. */
3598 }
3599 \f
3600 /* See if ARG is an expression that is either a comparison or is performing
3601 arithmetic on comparisons. The comparisons must only be comparing
3602 two different values, which will be stored in *CVAL1 and *CVAL2; if
3603 they are nonzero it means that some operands have already been found.
3604 No variables may be used anywhere else in the expression except in the
3605 comparisons.
3607 If this is true, return 1. Otherwise, return zero. */
3609 static int
3611 {
3615 /* We can handle some of the tcc_expression cases here. */
3624 {
3643 /* First see if we can handle the first operand, then the second. For
3644 the second operand, we know *CVAL1 can't be zero. It must be that
3645 one side of the comparison is each of the values; test for the
3646 case where this isn't true by failing if the two operands
3647 are the same. */
3656 ;
3660 ;
3661 else
3665 ;
3669 ;
3670 else
3677 }
3678 }
3679 \f
3680 /* ARG is a tree that is known to contain just arithmetic operations and
3681 comparisons. Evaluate the operations in the tree substituting NEW0 for
3682 any occurrence of OLD0 as an operand of a comparison and likewise for
3683 NEW1 and OLD1. */
3685 static tree
3688 {
3693 /* We can handle some of the tcc_expression cases here. */
3701 {
3716 {
3735 }
3736 /* Fall through - ??? */
3739 {
3743 /* We need to check both for exact equality and tree equality. The
3744 former will be true if the operand has a side-effect. In that
3745 case, we know the operand occurred exactly once. */
3758 }
3762 }
3763 }
3764 \f
3765 /* Return a tree for the case when the result of an expression is RESULT
3766 converted to TYPE and OMITTED was previously an operand of the expression
3767 but is now not needed (e.g., we folded OMITTED * 0).
3769 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3770 the conversion of RESULT to TYPE. */
3772 tree
3774 {
3777 /* If the resulting operand is an empty statement, just return the omitted
3778 statement casted to void. */
3788 }
3790 /* Return a tree for the case when the result of an expression is RESULT
3791 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3792 of the expression but are now not needed.
3794 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3795 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3796 evaluated before OMITTED2. Otherwise, if neither has side effects,
3797 just do the conversion of RESULT to TYPE. */
3799 tree
3802 {
3811 }
3813 \f
3814 /* Return a simplified tree node for the truth-negation of ARG. This
3815 never alters ARG itself. We assume that ARG is an operation that
3816 returns a truth value (0 or 1).
3818 FIXME: one would think we would fold the result, but it causes
3819 problems with the dominator optimizer. */
3821 static tree
3823 {
3828 /* If this is a comparison, we can simply invert it, except for
3829 floating-point non-equality comparisons, in which case we just
3830 enclose a TRUTH_NOT_EXPR around what we have. */
3833 {
3836 && flag_trapping_math
3850 }
3853 {
3872 /* Here we can invert either operand. We invert the first operand
3873 unless the second operand is a TRUTH_NOT_EXPR in which case our
3874 result is the XOR of the first operand with the inside of the
3875 negation of the second operand. */
3880 else
3903 {
3910 /* A COND_EXPR may have a throw as one operand, which
3911 then has void type. Just leave void operands
3912 as they are. */
3918 }
3930 CASE_CONVERT:
3934 /* fall through */
3956 }
3957 }
3959 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3960 assume that ARG is an operation that returns a truth value (0 or 1
3961 for scalars, 0 or -1 for vectors). Return the folded expression if
3962 folding is successful. Otherwise, return NULL_TREE. */
3964 static tree
3966 {
3969 ? BIT_NOT_EXPR
3972 }
3974 /* Return a simplified tree node for the truth-negation of ARG. This
3975 never alters ARG itself. We assume that ARG is an operation that
3976 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3978 tree
3980 {
3986 ? BIT_NOT_EXPR
3989 }
3990 \f
3991 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3992 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3993 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3994 is the original memory reference used to preserve the alias set of
3995 the access. */
3997 static tree
4001 {
4004 /* Attempt not to lose the access path if possible. */
4006 {
4008 machine_mode nmode;
4010 tree noffset;
4018 && !reversep
4019 && !nreversep
4021 {
4024 }
4025 }
4034 {
4041 }
4056 }
4058 /* Optimize a bit-field compare.
4060 There are two cases: First is a compare against a constant and the
4061 second is a comparison of two items where the fields are at the same
4062 bit position relative to the start of a chunk (byte, halfword, word)
4063 large enough to contain it. In these cases we can avoid the shift
4064 implicit in bitfield extractions.
4066 For constants, we emit a compare of the shifted constant with the
4067 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4068 compared. For two fields at the same position, we do the ANDs with the
4069 similar mask and compare the result of the ANDs.
4071 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4072 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4073 are the left and right operands of the comparison, respectively.
4075 If the optimization described above can be done, we return the resulting
4076 tree. Otherwise we return zero. */
4078 static tree
4081 {
4085 tree unsigned_type;
4088 scalar_int_mode nmode;
4093 tree mask;
4094 tree offset;
4096 /* Get all the information about the extractions being done. If the bit size
4097 is the same as the size of the underlying object, we aren't doing an
4098 extraction at all and so can do nothing. We also don't want to
4099 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4100 then will no longer be able to replace it. */
4115 else
4116 {
4117 /* If this is not a constant, we can only do something if bit positions,
4118 sizes, signedness and storage order are the same. */
4119 rinner
4132 }
4134 /* Honor the C++ memory model and mimic what RTL expansion does. */
4138 {
4142 }
4144 /* See if we can find a mode to refer to this field. We should be able to,
4145 but fail if we can't. */
4153 /* Set signed and unsigned types of the precision of this mode for the
4154 shifts below. */
4157 /* Compute the bit position and size for the new reference and our offset
4158 within it. If the new reference is the same size as the original, we
4159 won't optimize anything, so return zero. */
4169 /* Make the mask to be used against the extracted field. */
4176 {
4180 /* If not comparing with constant, just rework the comparison
4181 and return. */
4189 }
4191 /* Otherwise, we are handling the constant case. See if the constant is too
4192 big for the field. Warn and return a tree for 0 (false) if so. We do
4193 this not only for its own sake, but to avoid having to test for this
4194 error case below. If we didn't, we might generate wrong code.
4196 For unsigned fields, the constant shifted right by the field length should
4197 be all zero. For signed fields, the high-order bits should agree with
4198 the sign bit. */
4201 {
4203 {
4207 }
4208 }
4209 else
4210 {
4213 {
4217 }
4218 }
4223 /* Single-bit compares should always be against zero. */
4225 {
4228 }
4230 /* Make a new bitfield reference, shift the constant over the
4231 appropriate number of bits and mask it with the computed mask
4232 (in case this was a signed field). If we changed it, make a new one. */
4240 mask);
4245 }
4246 \f
4247 /* Subroutine for fold_truth_andor_1: decode a field reference.
4249 If EXP is a comparison reference, we return the innermost reference.
4251 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4252 set to the starting bit number.
4254 If the innermost field can be completely contained in a mode-sized
4255 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4257 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4258 otherwise it is not changed.
4260 *PUNSIGNEDP is set to the signedness of the field.
4262 *PREVERSEP is set to the storage order of the field.
4264 *PMASK is set to the mask used. This is either contained in a
4265 BIT_AND_EXPR or derived from the width of the field.
4267 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4269 Return 0 if this is not a component reference or is one that we can't
4270 do anything with. */
4272 static tree
4277 {
4282 tree unsigned_type;
4285 /* All the optimizations using this function assume integer fields.
4286 There are problems with FP fields since the type_for_size call
4287 below can fail for, e.g., XFmode. */
4291 /* We are interested in the bare arrangement of bits, so strip everything
4292 that doesn't affect the machine mode. However, record the type of the
4293 outermost expression if it may matter below. */
4300 {
4306 }
4317 /* Reject out-of-bound accesses (PR79731). */
4329 /* If the number of bits in the reference is the same as the bitsize of
4330 the outer type, then the outer type gives the signedness. Otherwise
4331 (in case of a small bitfield) the signedness is unchanged. */
4335 /* Compute the mask to access the bitfield. */
4343 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4351 }
4353 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4354 bit positions and MASK is SIGNED. */
4356 static int
4358 {
4362 /* If this function returns true when the type of the mask is
4363 UNSIGNED, then there will be errors. In particular see
4364 gcc.c-torture/execute/990326-1.c. There does not appear to be
4365 any documentation paper trail as to why this is so. But the pre
4366 wide-int worked with that restriction and it has been preserved
4367 here. */
4372 }
4374 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4375 represents the sign bit of EXP's type. If EXP represents a sign
4376 or zero extension, also test VAL against the unextended type.
4377 The return value is the (sub)expression whose sign bit is VAL,
4378 or NULL_TREE otherwise. */
4380 tree
4382 {
4384 tree t;
4386 /* Tree EXP must have an integral type. */
4391 /* Tree VAL must be an integer constant. */
4400 /* Handle extension from a narrower type. */
4406 }
4408 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4409 to be evaluated unconditionally. */
4411 static int
4413 {
4414 /* Strip any conversions that don't change the machine mode. */
4423 /* Don't regard global variables as simple. They may be
4424 allocated in ways unknown to the compiler (shared memory,
4425 #pragma weak, etc). */
4428 /* Weakrefs are not safe to be read, since they can be NULL.
4429 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4430 have DECL_WEAK flag set. */
4432 /* Loading a static variable is unduly expensive, but global
4433 registers aren't expensive. */
4435 }
4437 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4438 to be evaluated unconditionally.
4439 I addition to simple_operand_p, we assume that comparisons, conversions,
4440 and logic-not operations are simple, if their operands are simple, too. */
4442 static bool
4444 {
4464 }
4466 \f
4467 /* The following functions are subroutines to fold_range_test and allow it to
4468 try to change a logical combination of comparisons into a range test.
4470 For example, both
4471 X == 2 || X == 3 || X == 4 || X == 5
4472 and
4473 X >= 2 && X <= 5
4474 are converted to
4475 (unsigned) (X - 2) <= 3
4477 We describe each set of comparisons as being either inside or outside
4478 a range, using a variable named like IN_P, and then describe the
4479 range with a lower and upper bound. If one of the bounds is omitted,
4480 it represents either the highest or lowest value of the type.
4482 In the comments below, we represent a range by two numbers in brackets
4483 preceded by a "+" to designate being inside that range, or a "-" to
4484 designate being outside that range, so the condition can be inverted by
4485 flipping the prefix. An omitted bound is represented by a "-". For
4486 example, "- [-, 10]" means being outside the range starting at the lowest
4487 possible value and ending at 10, in other words, being greater than 10.
4488 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4489 always false.
4491 We set up things so that the missing bounds are handled in a consistent
4492 manner so neither a missing bound nor "true" and "false" need to be
4493 handled using a special case. */
4495 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4496 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4497 and UPPER1_P are nonzero if the respective argument is an upper bound
4498 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4499 must be specified for a comparison. ARG1 will be converted to ARG0's
4500 type if both are specified. */
4502 static tree
4505 {
4506 tree tem;
4510 /* If neither arg represents infinity, do the normal operation.
4511 Else, if not a comparison, return infinity. Else handle the special
4512 comparison rules. Note that most of the cases below won't occur, but
4513 are handled for consistency. */
4516 {
4521 }
4526 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4527 for neither. In real maths, we cannot assume open ended ranges are
4528 the same. But, this is computer arithmetic, where numbers are finite.
4529 We can therefore make the transformation of any unbounded range with
4530 the value Z, Z being greater than any representable number. This permits
4531 us to treat unbounded ranges as equal. */
4535 {
4556 }
4559 }
4560 \f
4561 /* Helper routine for make_range. Perform one step for it, return
4562 new expression if the loop should continue or NULL_TREE if it should
4563 stop. */
4565 tree
4569 {
4575 {
4577 /* We can only do something if the range is testing for zero. */
4586 /* We can only do something if the range is testing for zero
4587 and if the second operand is an integer constant. Note that
4588 saying something is "in" the range we make is done by
4589 complementing IN_P since it will set in the initial case of
4590 being not equal to zero; "out" is leaving it alone. */
4597 {
4618 }
4620 /* If this is an unsigned comparison, we also know that EXP is
4621 greater than or equal to zero. We base the range tests we make
4622 on that fact, so we record it here so we can parse existing
4623 range tests. We test arg0_type since often the return type
4624 of, e.g. EQ_EXPR, is boolean. */
4626 {
4630 NULL_TREE))
4635 /* If the high bound is missing, but we have a nonzero low
4636 bound, reverse the range so it goes from zero to the low bound
4637 minus 1. */
4639 {
4644 }
4645 }
4653 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4654 low and high are non-NULL, then normalize will DTRT. */
4657 {
4662 }
4664 /* (-x) IN [a,b] -> x in [-b, -a] */
4676 /* ~ X -> -X - 1 */
4685 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4686 move a constant to the other side. */
4691 /* If EXP is signed, any overflow in the computation is undefined,
4692 so we don't worry about it so long as our computations on
4693 the bounds don't overflow. For unsigned, overflow is defined
4694 and this is exactly the right thing. */
4706 normalize:
4707 /* Check for an unsigned range which has wrapped around the maximum
4708 value thus making n_high < n_low, and normalize it. */
4710 {
4716 /* If the range is of the form +/- [ x+1, x ], we won't
4717 be able to normalize it. But then, it represents the
4718 whole range or the empty set, so make it
4719 +/- [ -, - ]. */
4723 else
4725 }
4726 else
4734 CASE_CONVERT:
4752 /* If we're converting arg0 from an unsigned type, to exp,
4753 a signed type, we will be doing the comparison as unsigned.
4754 The tests above have already verified that LOW and HIGH
4755 are both positive.
4757 So we have to ensure that we will handle large unsigned
4758 values the same way that the current signed bounds treat
4759 negative values. */
4762 {
4763 tree high_positive;
4764 tree equiv_type;
4765 /* For fixed-point modes, we need to pass the saturating flag
4766 as the 2nd parameter. */
4768 equiv_type
4771 else
4772 equiv_type
4775 /* A range without an upper bound is, naturally, unbounded.
4776 Since convert would have cropped a very large value, use
4777 the max value for the destination type. */
4778 high_positive
4785 high_positive),
4788 /* If the low bound is specified, "and" the range with the
4789 range for which the original unsigned value will be
4790 positive. */
4792 {
4795 integer_zero_node),
4796 high_positive))
4800 }
4801 else
4802 {
4803 /* Otherwise, "or" the range with the range of the input
4804 that will be interpreted as negative. */
4807 integer_zero_node),
4808 high_positive))
4812 }
4813 }
4822 }
4823 }
4825 /* Given EXP, a logical expression, set the range it is testing into
4826 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4827 actually being tested. *PLOW and *PHIGH will be made of the same
4828 type as the returned expression. If EXP is not a comparison, we
4829 will most likely not be returning a useful value and range. Set
4830 *STRICT_OVERFLOW_P to true if the return value is only valid
4831 because signed overflow is undefined; otherwise, do not change
4832 *STRICT_OVERFLOW_P. */
4834 tree
4837 {
4845 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4846 and see if we can refine the range. Some of the cases below may not
4847 happen, but it doesn't seem worth worrying about this. We "continue"
4848 the outer loop when we've changed something; otherwise we "break"
4849 the switch, which will "break" the while. */
4855 {
4861 {
4869 }
4878 }
4880 /* If EXP is a constant, we can evaluate whether this is true or false. */
4882 {
4889 }
4893 }
4895 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4896 a bitwise check i.e. when
4897 LOW == 0xXX...X00...0
4898 HIGH == 0xXX...X11...1
4899 Return corresponding mask in MASK and stem in VALUE. */
4901 static bool
4904 {
4927 }
4928 \f
4929 /* Helper routine for build_range_check and match.pd. Return the type to
4930 perform the check or NULL if it shouldn't be optimized. */
4932 tree
4934 {
4935 /* First make sure that arithmetics in this type is valid, then make sure
4936 that it wraps around. */
4942 {
4945 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4946 for the type in question, as we rely on this here. */
4956 else
4958 }
4960 }
4962 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4963 type, TYPE, return an expression to test if EXP is in (or out of, depending
4964 on IN_P) the range. Return 0 if the test couldn't be created. */
4966 tree
4969 {
4972 /* Disable this optimization for function pointer expressions
4973 on targets that require function pointer canonicalization. */
4980 {
4986 }
5008 value);
5011 {
5013 {
5017 }
5019 }
5021 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5023 {
5027 {
5029 {
5032 etype
5034 else
5037 }
5040 }
5041 }
5043 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5044 This requires wrap-around arithmetics for the type of the expression. */
5064 }
5065 \f
5066 /* Return the predecessor of VAL in its type, handling the infinite case. */
5068 static tree
5070 {
5076 else
5079 }
5081 /* Return the successor of VAL in its type, handling the infinite case. */
5083 static tree
5085 {
5091 else
5094 }
5096 /* Given two ranges, see if we can merge them into one. Return 1 if we
5097 can, 0 if we can't. Set the output range into the specified parameters. */
5099 bool
5102 {
5106 tree tem;
5116 /* Make range 0 be the range that starts first, or ends last if they
5117 start at the same value. Swap them if it isn't. */
5120 || (lowequal
5123 {
5127 }
5129 /* If the second range is != high1 where high1 is the type maximum of
5130 the type, try first merging with < high1 range. */
5132 && high1
5139 {
5144 /* Similarly for the second range != low1 where low1 is the type minimum
5145 of the type, try first merging with > low1 range. */
5150 }
5152 /* Now flag two cases, whether the ranges are disjoint or whether the
5153 second range is totally subsumed in the first. Note that the tests
5154 below are simplified by the ones above. */
5160 /* We now have four cases, depending on whether we are including or
5161 excluding the two ranges. */
5163 {
5164 /* If they don't overlap, the result is false. If the second range
5165 is a subset it is the result. Otherwise, the range is from the start
5166 of the second to the end of the first. */
5171 else
5173 }
5176 {
5177 /* If they don't overlap, the result is the first range. If they are
5178 equal, the result is false. If the second range is a subset of the
5179 first, and the ranges begin at the same place, we go from just after
5180 the end of the second range to the end of the first. If the second
5181 range is not a subset of the first, or if it is a subset and both
5182 ranges end at the same place, the range starts at the start of the
5183 first range and ends just before the second range.
5184 Otherwise, we can't describe this as a single range. */
5190 {
5195 {
5196 /* We are in the weird situation where high0 > high1 but
5197 high1 has no successor. Punt. */
5199 }
5200 }
5202 {
5207 {
5208 /* low0 < low1 but low1 has no predecessor. Punt. */
5210 }
5211 }
5212 else
5214 }
5217 {
5218 /* If they don't overlap, the result is the second range. If the second
5219 is a subset of the first, the result is false. Otherwise,
5220 the range starts just after the first range and ends at the
5221 end of the second. */
5226 else
5227 {
5232 {
5233 /* high1 > high0 but high0 has no successor. Punt. */
5235 }
5236 }
5237 }
5239 else
5240 {
5241 /* The case where we are excluding both ranges. Here the complex case
5242 is if they don't overlap. In that case, the only time we have a
5243 range is if they are adjacent. If the second is a subset of the
5244 first, the result is the first. Otherwise, the range to exclude
5245 starts at the beginning of the first range and ends at the end of the
5246 second. */
5248 {
5253 else
5254 {
5255 /* Canonicalize - [min, x] into - [-, x]. */
5258 {
5261 GET_MODE_BITSIZE
5264 /* FALLTHROUGH */
5277 }
5279 /* Canonicalize - [x, max] into - [x, -]. */
5282 {
5285 GET_MODE_BITSIZE
5288 /* FALLTHROUGH */
5304 }
5306 /* The ranges might be also adjacent between the maximum and
5307 minimum values of the given type. For
5308 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5309 return + [x + 1, y - 1]. */
5311 {
5318 }
5319 else
5321 }
5322 }
5325 else
5327 }
5331 }
5332 \f
5334 /* Subroutine of fold, looking inside expressions of the form
5335 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5336 of the COND_EXPR. This function is being used also to optimize
5337 A op B ? C : A, by reversing the comparison first.
5339 Return a folded expression whose code is not a COND_EXPR
5340 anymore, or NULL_TREE if no folding opportunity is found. */
5342 static tree
5345 {
5350 tree tem;
5355 /* If we have A op 0 ? A : -A, consider applying the following
5356 transformations:
5358 A == 0? A : -A same as -A
5359 A != 0? A : -A same as A
5360 A >= 0? A : -A same as abs (A)
5361 A > 0? A : -A same as abs (A)
5362 A <= 0? A : -A same as -abs (A)
5363 A < 0? A : -A same as -abs (A)
5365 None of these transformations work for modes with signed
5366 zeros. If A is +/-0, the first two transformations will
5367 change the sign of the result (from +0 to -0, or vice
5368 versa). The last four will fix the sign of the result,
5369 even though the original expressions could be positive or
5370 negative, depending on the sign of A.
5372 Note that all these transformations are correct if A is
5373 NaN, since the two alternatives (A and -A) are also NaNs. */
5380 /* In the case that A is of the form X-Y, '-A' (arg2) may
5381 have already been folded to Y-X, check for that. */
5389 {
5401 /* Fall through. */
5412 /* FALLTHRU */
5422 }
5424 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5425 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5426 both transformations are correct when A is NaN: A != 0
5427 is then true, and A == 0 is false. */
5431 {
5436 }
5438 /* Try some transformations of A op B ? A : B.
5440 A == B? A : B same as B
5441 A != B? A : B same as A
5442 A >= B? A : B same as max (A, B)
5443 A > B? A : B same as max (B, A)
5444 A <= B? A : B same as min (A, B)
5445 A < B? A : B same as min (B, A)
5447 As above, these transformations don't work in the presence
5448 of signed zeros. For example, if A and B are zeros of
5449 opposite sign, the first two transformations will change
5450 the sign of the result. In the last four, the original
5451 expressions give different results for (A=+0, B=-0) and
5452 (A=-0, B=+0), but the transformed expressions do not.
5454 The first two transformations are correct if either A or B
5455 is a NaN. In the first transformation, the condition will
5456 be false, and B will indeed be chosen. In the case of the
5457 second transformation, the condition A != B will be true,
5458 and A will be chosen.
5460 The conversions to max() and min() are not correct if B is
5461 a number and A is not. The conditions in the original
5462 expressions will be false, so all four give B. The min()
5463 and max() versions would give a NaN instead. */
5466 /* Avoid these transformations if the COND_EXPR may be used
5467 as an lvalue in the C++ front-end. PR c++/19199. */
5468 && (in_gimple_form
5474 {
5480 {
5489 /* In C++ a ?: expression can be an lvalue, so put the
5490 operand which will be used if they are equal first
5491 so that we can convert this back to the
5492 corresponding COND_EXPR. */
5494 {
5502 }
5509 {
5517 }
5530 }
5531 }
5534 }
5537 \f
5538 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5539 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5540 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5541 false) >= 2)
5542 #endif
5544 /* EXP is some logical combination of boolean tests. See if we can
5545 merge it into some range test. Return the new tree if so. */
5547 static tree
5550 {
5566 /* If this is an OR operation, invert both sides; we will invert
5567 again at the end. */
5571 /* If both expressions are the same, if we can merge the ranges, and we
5572 can build the range test, return it or it inverted. If one of the
5573 ranges is always true or always false, consider it to be the same
5574 expression as the other. */
5582 {
5586 }
5588 /* On machines where the branch cost is expensive, if this is a
5589 short-circuited branch and the underlying object on both sides
5590 is the same, make a non-short-circuit operation. */
5593 logical_op_non_short_circuit
5596 && !flag_sanitize_coverage
5600 {
5601 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5602 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5603 which cases we can't do this. */
5611 {
5620 {
5623 WARN_STRICT_OVERFLOW_COMPARISON);
5627 }
5628 }
5629 }
5632 }
5633 \f
5634 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5635 bit value. Arrange things so the extra bits will be set to zero if and
5636 only if C is signed-extended to its full width. If MASK is nonzero,
5637 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5639 static tree
5641 {
5644 tree temp;
5649 /* We work by getting just the sign bit into the low-order bit, then
5650 into the high-order bit, then sign-extend. We then XOR that value
5651 with C. */
5655 /* We must use a signed type in order to get an arithmetic right shift.
5656 However, we must also avoid introducing accidental overflows, so that
5657 a subsequent call to integer_zerop will work. Hence we must
5658 do the type conversion here. At this point, the constant is either
5659 zero or one, and the conversion to a signed type can never overflow.
5660 We could get an overflow if this conversion is done anywhere else. */
5669 /* If necessary, convert the type back to match the type of C. */
5674 }
5675 \f
5676 /* For an expression that has the form
5677 (A && B) || ~B
5678 or
5679 (A || B) && ~B,
5680 we can drop one of the inner expressions and simplify to
5681 A || ~B
5682 or
5683 A && ~B
5684 LOC is the location of the resulting expression. OP is the inner
5685 logical operation; the left-hand side in the examples above, while CMPOP
5686 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5687 removing a condition that guards another, as in
5688 (A != NULL && A->...) || A == NULL
5689 which we must not transform. If RHS_ONLY is true, only eliminate the
5690 right-most operand of the inner logical operation. */
5692 static tree
5695 {
5713 {
5716 {
5719 }
5720 }
5722 {
5725 {
5728 }
5729 }
5744 }
5746 /* Find ways of folding logical expressions of LHS and RHS:
5747 Try to merge two comparisons to the same innermost item.
5748 Look for range tests like "ch >= '0' && ch <= '9'".
5749 Look for combinations of simple terms on machines with expensive branches
5750 and evaluate the RHS unconditionally.
5752 For example, if we have p->a == 2 && p->b == 4 and we can make an
5753 object large enough to span both A and B, we can do this with a comparison
5754 against the object ANDed with the a mask.
5756 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5757 operations to do this with one comparison.
5759 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5760 function and the one above.
5762 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5763 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5765 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5766 two operands.
5768 We return the simplified tree or 0 if no optimization is possible. */
5770 static tree
5773 {
5774 /* If this is the "or" of two comparisons, we can do something if
5775 the comparisons are NE_EXPR. If this is the "and", we can do something
5776 if the comparisons are EQ_EXPR. I.e.,
5777 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5779 WANTED_CODE is this operation code. For single bit fields, we can
5780 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5781 comparison for one-bit fields. */
5802 /* Start by getting the comparison codes. Fail if anything is volatile.
5803 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5804 it were surrounded with a NE_EXPR. */
5813 {
5817 }
5820 {
5824 }
5835 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5838 {
5841 {
5846 }
5849 {
5855 }
5856 }
5861 /* If the RHS can be evaluated unconditionally and its operands are
5862 simple, it wins to evaluate the RHS unconditionally on machines
5863 with expensive branches. In this case, this isn't a comparison
5864 that can be merged. */
5871 {
5872 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5883 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5893 }
5895 /* See if the comparisons can be merged. Then get all the parameters for
5896 each side. */
5921 /* It must be true that the inner operation on the lhs of each
5922 comparison must be the same if we are to be able to do anything.
5923 Then see if we have constants. If not, the same must be true for
5924 the rhs's. */
5933 {
5936 }
5941 else
5944 /* If either comparison code is not correct for our logical operation,
5945 fail. However, we can convert a one-bit comparison against zero into
5946 the opposite comparison against that bit being set in the field. */
5950 {
5952 {
5953 /* Make the left operand unsigned, since we are only interested
5954 in the value of one bit. Otherwise we are doing the wrong
5955 thing below. */
5958 }
5959 else
5961 }
5963 /* This is analogous to the code for l_const above. */
5965 {
5967 {
5970 }
5971 else
5973 }
5975 /* See if we can find a mode that contains both fields being compared on
5976 the left. If we can't, fail. Otherwise, update all constants and masks
5977 to be relative to a field of that size. */
5991 {
5994 }
6002 {
6009 {
6013 }
6014 }
6016 {
6023 {
6027 }
6028 }
6030 /* If the right sides are not constant, do the same for it. Also,
6031 disallow this optimization if a size, signedness or storage order
6032 mismatch occurs between the left and right sides. */
6034 {
6038 /* Make sure the two fields on the right
6039 correspond to the left without being swapped. */
6056 {
6059 }
6068 /* Make a mask that corresponds to both fields being compared.
6069 Do this for both items being compared. If the operands are the
6070 same size and the bits being compared are in the same position
6071 then we can do this by masking both and comparing the masked
6072 results. */
6079 {
6093 }
6095 /* There is still another way we can do something: If both pairs of
6096 fields being compared are adjacent, we may be able to make a wider
6097 field containing them both.
6099 Note that we still must mask the lhs/rhs expressions. Furthermore,
6100 the mask must be shifted to account for the shift done by
6101 make_bit_field_ref. */
6110 {
6111 tree type;
6127 /* Convert to the smaller type before masking out unwanted bits. */
6130 {
6132 {
6136 }
6138 {
6142 }
6143 }
6152 }
6155 }
6157 /* Handle the case of comparisons with constants. If there is something in
6158 common between the masks, those bits of the constants must be the same.
6159 If not, the condition is always false. Test for this to avoid generating
6160 incorrect code below. */
6165 {
6167 {
6170 }
6171 else
6172 {
6175 }
6176 }
6181 /* Construct the expression we will return. First get the component
6182 reference we will make. Unless the mask is all ones the width of
6183 that field, perform the mask operation. Then compare with the
6184 merged constant. */
6195 }
6196 \f
6197 /* T is an integer expression that is being multiplied, divided, or taken a
6198 modulus (CODE says which and what kind of divide or modulus) by a
6199 constant C. See if we can eliminate that operation by folding it with
6200 other operations already in T. WIDE_TYPE, if non-null, is a type that
6201 should be used for the computation if wider than our type.
6203 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6204 (X * 2) + (Y * 4). We must, however, be assured that either the original
6205 expression would not overflow or that overflow is undefined for the type
6206 in the language in question.
6208 If we return a non-null expression, it is an equivalent form of the
6209 original computation, but need not be in the original type.
6211 We set *STRICT_OVERFLOW_P to true if the return values depends on
6212 signed overflow being undefined. Otherwise we do not change
6213 *STRICT_OVERFLOW_P. */
6215 static tree
6218 {
6219 /* To avoid exponential search depth, refuse to allow recursion past
6220 three levels. Beyond that (1) it's highly unlikely that we'll find
6221 something interesting and (2) we've probably processed it before
6222 when we built the inner expression. */
6225 tree ret;
6230 depth++;
6232 depth--;
6235 }
6237 static tree
6240 {
6252 /* Don't deal with constants of zero here; they confuse the code below. */
6262 /* Note that we need not handle conditional operations here since fold
6263 already handles those cases. So just do arithmetic here. */
6265 {
6267 /* For a constant, we can always simplify if we are a multiply
6268 or (for divide and modulus) if it is a multiple of our constant. */
6272 {
6275 /* If the multiplication overflowed, we lost information on it.
6276 See PR68142 and PR69845. */
6280 }
6284 /* If op0 is an expression ... */
6290 /* ... and has wrapping overflow, and its type is smaller
6291 than ctype, then we cannot pass through as widening. */
6296 /* ... or this is a truncation (t is narrower than op0),
6297 then we cannot pass through this narrowing. */
6300 /* ... or signedness changes for division or modulus,
6301 then we cannot pass through this conversion. */
6305 /* ... or has undefined overflow while the converted to
6306 type has not, we cannot do the operation in the inner type
6307 as that would introduce undefined overflow. */
6313 /* Pass the constant down and see if we can make a simplification. If
6314 we can, replace this expression with the inner simplification for
6315 possible later conversion to our or some other type. */
6326 /* If widening the type changes it from signed to unsigned, then we
6327 must avoid building ABS_EXPR itself as unsigned. */
6329 {
6333 {
6336 }
6338 }
6339 /* If the constant is negative, we cannot simplify this. */
6342 /* FALLTHROUGH */
6344 /* For division and modulus, type can't be unsigned, as e.g.
6345 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6346 For signed types, even with wrapping overflow, this is fine. */
6355 /* If widening the type changes the signedness, then we can't perform
6356 this optimization as that changes the result. */
6360 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6366 {
6373 }
6377 /* If the second operand is constant, this is a multiplication
6378 or floor division, by a power of two, so we can treat it that
6379 way unless the multiplier or divisor overflows. Signed
6380 left-shift overflow is implementation-defined rather than
6381 undefined in C90, so do not convert signed left shift into
6382 multiplication. */
6385 /* const_binop may not detect overflow correctly,
6386 so check for it explicitly here. */
6395 ctype,
6397 t1),
6402 /* See if we can eliminate the operation on both sides. If we can, we
6403 can return a new PLUS or MINUS. If we can't, the only remaining
6404 cases where we can do anything are if the second operand is a
6405 constant. */
6412 /* If not multiplication, we can only do this if both operands
6413 are divisible by c. */
6416 {
6421 }
6423 /* If this was a subtraction, negate OP1 and set it to be an addition.
6424 This simplifies the logic below. */
6426 {
6428 /* If OP1 was not easily negatable, the constant may be OP0. */
6430 {
6433 }
6434 }
6439 /* If either OP1 or C are negative, this optimization is not safe for
6440 some of the division and remainder types while for others we need
6441 to change the code. */
6443 {
6451 }
6453 /* If it's a multiply or a division/modulus operation of a multiple
6454 of our constant, do the operation and verify it doesn't overflow. */
6458 {
6461 /* We allow the constant to overflow with wrapping semantics. */
6465 }
6466 else
6469 /* If we have an unsigned type, we cannot widen the operation since it
6470 will change the result if the original computation overflowed. */
6474 /* The last case is if we are a multiply. In that case, we can
6475 apply the distributive law to commute the multiply and addition
6476 if the multiplication of the constants doesn't overflow
6477 and overflow is defined. With undefined overflow
6478 op0 * c might overflow, while (op0 + orig_op1) * c doesn't.
6479 But fold_plusminus_mult_expr would factor back any power-of-two
6480 value so do not distribute in the first place in this case. */
6488 op1);
6493 /* We have a special case here if we are doing something like
6494 (C * 8) % 4 since we know that's zero. */
6497 /* If the multiplication can overflow we cannot optimize this. */
6502 {
6505 }
6507 /* ... fall through ... */
6511 /* If we can extract our operation from the LHS, do so and return a
6512 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6513 do something only if the second operand is a constant. */
6529 /* If these are the same operation types, we can associate them
6530 assuming no overflow. */
6532 {
6547 }
6549 /* If these operations "cancel" each other, we have the main
6550 optimizations of this pass, which occur when either constant is a
6551 multiple of the other, in which case we replace this with either an
6552 operation or CODE or TCODE.
6554 If we have an unsigned type, we cannot do this since it will change
6555 the result if the original computation overflowed. */
6562 {
6565 {
6572 }
6575 {
6582 }
6583 }
6588 }
6591 }
6592 \f
6593 /* Return a node which has the indicated constant VALUE (either 0 or
6594 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6595 and is of the indicated TYPE. */
6597 tree
6599 {
6608 else
6610 }
6613 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6614 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6615 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6616 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6617 COND is the first argument to CODE; otherwise (as in the example
6618 given here), it is the second argument. TYPE is the type of the
6619 original expression. Return NULL_TREE if no simplification is
6620 possible. */
6622 static tree
6627 {
6635 /* Do not move possibly trapping operations into the conditional as this
6636 pessimizes code and causes gimplification issues when applied late. */
6644 {
6648 /* If this operand throws an expression, then it does not make
6649 sense to try to perform a logical or arithmetic operation
6650 involving it. */
6655 }
6658 {
6663 }
6664 else
6665 /* Detect the case of mixing vector and scalar types - bail out. */
6671 /* This transformation is only worthwhile if we don't have to wrap ARG
6672 in a SAVE_EXPR and the operation can be simplified without recursing
6673 on at least one of the branches once its pushed inside the COND_EXPR. */
6682 {
6686 else
6688 }
6690 {
6694 else
6696 }
6698 /* Check that we have simplified at least one of the branches. */
6703 }
6705 \f
6706 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6708 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6709 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6710 ADDEND is the same as X.
6712 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6713 and finite. The problematic cases are when X is zero, and its mode
6714 has signed zeros. In the case of rounding towards -infinity,
6715 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6716 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6718 bool
6720 {
6724 /* Don't allow the fold with -fsignaling-nans. */
6728 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6732 /* There is no case that is safe for all rounding modes. */
6736 /* In a vector or complex, we would need to check the sign of all zeros. */
6742 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6746 /* The mode has signed zeros, and we have to honor their sign.
6747 In this situation, there is only one case we can return true for.
6748 X - 0 is the same as X with default rounding. */
6750 }
6752 /* Subroutine of match.pd that optimizes comparisons of a division by
6753 a nonzero integer constant against an integer constant, i.e.
6754 X/C1 op C2.
6756 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6757 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6759 enum tree_code
6762 {
6767 /* We have to do this the hard way to detect unsigned overflow.
6768 prod = int_const_binop (MULT_EXPR, c1, c2); */
6774 {
6778 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6781 }
6783 {
6786 {
6805 }
6806 }
6807 else
6808 {
6809 /* A negative divisor reverses the relational operators. */
6814 {
6833 }
6834 }
6847 }
6850 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6851 equality/inequality test, then return a simplified form of the test
6852 using a sign testing. Otherwise return NULL. TYPE is the desired
6853 result type. */
6855 static tree
6858 tree result_type)
6859 {
6860 /* If this is testing a single bit, we can optimize the test. */
6864 {
6865 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6866 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6870 /* This is only a win if casting to a signed type is cheap,
6871 i.e. when arg00's type is not a partial mode. */
6873 {
6876 result_type,
6879 }
6880 }
6883 }
6885 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6886 equality/inequality test, then return a simplified form of
6887 the test using shifts and logical operations. Otherwise return
6888 NULL. TYPE is the desired result type. */
6890 tree
6893 {
6894 /* If this is testing a single bit, we can optimize the test. */
6898 {
6907 /* First, see if we can fold the single bit test into a sign-bit
6908 test. */
6910 result_type);
6914 /* Otherwise we have (A & C) != 0 where C is a single bit,
6915 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6916 Similarly for (A & C) == 0. */
6918 /* If INNER is a right shift of a constant and it plus BITNUM does
6919 not overflow, adjust BITNUM and INNER. */
6925 {
6928 }
6930 /* If we are going to be able to omit the AND below, we must do our
6931 operations as unsigned. If we must use the AND, we have a choice.
6932 Normally unsigned is faster, but for some machines signed is. */
6950 /* Put the AND last so it can combine with more things. */
6953 /* Make sure to return the proper type. */
6957 }
6959 }
6961 /* Test whether it is preferable two swap two operands, ARG0 and
6962 ARG1, for example because ARG0 is an integer constant and ARG1
6963 isn't. */
6965 bool
6967 {
6981 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6982 for commutative and comparison operators. Ensuring a canonical
6983 form allows the optimizers to find additional redundancies without
6984 having to explicitly check for both orderings. */
6990 /* Put SSA_NAMEs last. */
6996 /* Put variables last. */
7003 }
7006 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
7007 means A >= Y && A != MAX, but in this case we know that
7008 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
7010 static tree
7012 {
7019 else
7028 {
7031 }
7033 {
7036 }
7037 else
7044 {
7045 /* Convert the pointer types into integer before taking the difference. */
7049 }
7050 else
7057 }
7059 /* Fold a sum or difference of at least one multiplication.
7060 Returns the folded tree or NULL if no simplification could be made. */
7062 static tree
7065 {
7069 /* (A * C) +- (B * C) -> (A+-B) * C.
7070 (A * C) +- A -> A * (C+-1).
7071 We are most concerned about the case where C is a constant,
7072 but other combinations show up during loop reduction. Since
7073 it is not difficult, try all four possibilities. */
7076 {
7079 }
7081 {
7084 }
7085 else
7086 {
7087 /* We cannot generate constant 1 for fract. */
7092 }
7094 {
7097 }
7099 {
7101 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7102 the purpose of this canonicalization. */
7106 {
7109 }
7110 else
7112 }
7113 else
7114 {
7115 /* We cannot generate constant 1 for fract. */
7120 }
7123 /* Prefer factoring a common non-constant. */
7133 /* No identical multiplicands; see if we can find a common
7134 power-of-two factor in non-power-of-two multiplies. This
7135 can help in multi-dimensional array access. */
7137 {
7140 HOST_WIDE_INT tmp;
7142 tree maybe_same;
7144 /* Move min of absolute values to int11. */
7146 {
7151 }
7152 else
7159 /* The remainder should not be a constant, otherwise we
7160 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7161 increased the number of multiplications necessary. */
7163 {
7171 }
7172 }
7179 /* We are neither factoring zero nor minus one. */
7187 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7188 same may be minus one and thus the multiplication may overflow. Perform
7189 the sum operation in an unsigned type. */
7194 /* If the sum evaluated to a constant that is not -INF the multiplication
7195 cannot overflow. */
7202 /* Do not resort to unsigned multiplication because
7203 we lose the no-overflow property of the expression. */
7205 }
7207 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7208 specified by EXPR into the buffer PTR of length LEN bytes.
7209 Return the number of bytes placed in the buffer, or zero
7210 upon failure. */
7212 static int
7214 {
7226 /* Dry run. */
7232 {
7234 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7235 number of bytes. */
7239 {
7246 else
7248 }
7249 else
7253 }
7255 }
7258 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7259 specified by EXPR into the buffer PTR of length LEN bytes.
7260 Return the number of bytes placed in the buffer, or zero
7261 upon failure. */
7263 static int
7265 {
7269 FIXED_VALUE_TYPE value;
7284 }
7287 /* Subroutine of native_encode_expr. Encode the REAL_CST
7288 specified by EXPR into the buffer PTR of length LEN bytes.
7289 Return the number of bytes placed in the buffer, or zero
7290 upon failure. */
7292 static int
7294 {
7300 /* There are always 32 bits in each long, no matter the size of
7301 the hosts long. We handle floating point representations with
7302 up to 192 bits. */
7311 /* Dry run. */
7320 {
7325 {
7332 else
7334 }
7335 else
7336 {
7339 {
7340 /* Reverse bytes within each long, or within the entire float
7341 if it's smaller than a long (for HFmode). */
7344 }
7345 }
7350 }
7352 }
7354 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7355 specified by EXPR into the buffer PTR of length LEN bytes.
7356 Return the number of bytes placed in the buffer, or zero
7357 upon failure. */
7359 static int
7361 {
7363 tree part;
7377 }
7380 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7381 specified by EXPR into the buffer PTR of length LEN bytes.
7382 Return the number of bytes placed in the buffer, or zero
7383 upon failure. */
7385 static int
7387 {
7398 {
7400 {
7403 }
7414 }
7416 }
7419 /* Subroutine of native_encode_expr. Encode the STRING_CST
7420 specified by EXPR into the buffer PTR of length LEN bytes.
7421 Return the number of bytes placed in the buffer, or zero
7422 upon failure. */
7424 static int
7426 {
7429 /* Wide-char strings are encoded in target byte-order so native
7430 encoding them is trivial. */
7445 {
7448 {
7451 }
7454 }
7455 else
7458 }
7461 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7462 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7463 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7464 anything, just do a dry run. If OFF is not -1 then start
7465 the encoding at byte offset OFF and encode at most LEN bytes.
7466 Return the number of bytes placed in the buffer, or zero upon failure. */
7468 int
7470 {
7471 /* We don't support starting at negative offset and -1 is special. */
7476 {
7497 }
7498 }
7501 /* Subroutine of native_interpret_expr. Interpret the contents of
7502 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7503 If the buffer cannot be interpreted, return NULL_TREE. */
7505 static tree
7507 {
7517 }
7520 /* Subroutine of native_interpret_expr. Interpret the contents of
7521 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7522 If the buffer cannot be interpreted, return NULL_TREE. */
7524 static tree
7526 {
7529 double_int result;
7530 FIXED_VALUE_TYPE fixed_value;
7540 }
7543 /* Subroutine of native_interpret_expr. Interpret the contents of
7544 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7545 If the buffer cannot be interpreted, return NULL_TREE. */
7547 static tree
7549 {
7553 /* There are always 32 bits in each long, no matter the size of
7554 the hosts long. We handle floating point representations with
7555 up to 192 bits. */
7556 REAL_VALUE_TYPE r;
7566 {
7567 /* Both OFFSET and BYTE index within a long;
7568 bitpos indexes the whole float. */
7571 {
7578 else
7580 }
7581 else
7582 {
7585 {
7586 /* Reverse bytes within each long, or within the entire float
7587 if it's smaller than a long (for HFmode). */
7590 }
7591 }
7595 }
7599 }
7602 /* Subroutine of native_interpret_expr. Interpret the contents of
7603 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7604 If the buffer cannot be interpreted, return NULL_TREE. */
7606 static tree
7608 {
7623 }
7626 /* Subroutine of native_interpret_expr. Interpret the contents of
7627 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7628 If the buffer cannot be interpreted, return NULL_TREE. */
7630 static tree
7632 {
7645 {
7650 }
7652 }
7655 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7656 the buffer PTR of length LEN as a constant of type TYPE. For
7657 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7658 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7659 return NULL_TREE. */
7661 tree
7663 {
7665 {
7687 }
7688 }
7690 /* Returns true if we can interpret the contents of a native encoding
7691 as TYPE. */
7693 static bool
7695 {
7697 {
7710 }
7711 }
7714 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7715 TYPE at compile-time. If we're unable to perform the conversion
7716 return NULL_TREE. */
7718 static tree
7720 {
7721 /* We support up to 512-bit values (for V8DFmode). */
7725 /* Check that the host and target are sane. */
7734 }
7736 /* Build an expression for the address of T. Folds away INDIRECT_REF
7737 to avoid confusing the gimplify process. */
7739 tree
7741 {
7742 /* The size of the object is not relevant when talking about its address. */
7747 {
7752 }
7762 {
7767 }
7768 else
7772 }
7774 /* Build an expression for the address of T. */
7776 tree
7778 {
7782 }
7784 /* Fold a unary expression of code CODE and type TYPE with operand
7785 OP0. Return the folded expression if folding is successful.
7786 Otherwise, return NULL_TREE. */
7788 tree
7790 {
7791 tree tem;
7792 tree arg0;
7800 {
7803 {
7804 /* Don't use STRIP_NOPS, because signedness of argument type
7805 matters. */
7807 }
7808 else
7809 {
7810 /* Strip any conversions that don't change the mode. This
7811 is safe for every expression, except for a comparison
7812 expression because its signedness is derived from its
7813 operands.
7815 Note that this is done as an internal manipulation within
7816 the constant folder, in order to find the simplest
7817 representation of the arguments so that their form can be
7818 studied. In any cases, the appropriate type conversions
7819 should be put back in the tree that will get out of the
7820 constant folder. */
7822 }
7825 {
7828 {
7832 }
7833 }
7834 }
7841 {
7848 {
7862 /* If this was a conversion, and all we did was to move into
7863 inside the COND_EXPR, bring it back out. But leave it if
7864 it is a conversion from integer to integer and the
7865 result precision is no wider than a word since such a
7866 conversion is cheap and may be optimized away by combine,
7867 while it couldn't if it were outside the COND_EXPR. Then return
7868 so we don't get into an infinite recursion loop taking the
7869 conversion out and then back in. */
7881 && (INTEGRAL_TYPE_P
7894 }
7895 }
7898 {
7904 CASE_CONVERT:
7908 {
7909 /* If we have (type) (a CMP b) and type is an integral type, return
7910 new expression involving the new type. Canonicalize
7911 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7912 non-integral type.
7913 Do not fold the result as that would not simplify further, also
7914 folding again results in recursions. */
7924 }
7926 /* Handle (T *)&A.B.C for A being of type T and B and C
7927 living at offset zero. This occurs frequently in
7928 C++ upcasting and then accessing the base. */
7932 {
7934 tree offset;
7935 machine_mode mode;
7937 tree base
7941 /* If the reference was to a (constant) zero offset, we can use
7942 the address of the base if it has the same base type
7943 as the result type and the pointer type is unqualified. */
7951 }
7955 /* Detect assigning a bitfield. */
7957 && DECL_BIT_FIELD
7959 {
7960 /* Don't leave an assignment inside a conversion
7961 unless assigning a bitfield. */
7963 /* First do the assignment, then return converted constant. */
7968 }
7970 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7971 constants (if x has signed type, the sign bit cannot be set
7972 in c). This folds extension into the BIT_AND_EXPR.
7973 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7974 very likely don't have maximal range for their precision and this
7975 transformation effectively doesn't preserve non-maximal ranges. */
7979 {
7990 <= HOST_BITS_PER_WIDE_INT
7992 {
7996 cst &= HOST_WIDE_INT_M1U
8000 && !flag_syntax_only
8003 {
8007 }
8008 }
8010 {
8015 }
8016 }
8018 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
8019 cast (T1)X will fold away. We assume that this happens when X itself
8020 is a cast. */
8024 {
8028 return fold_build_pointer_plus_loc
8030 }
8032 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8033 of the same precision, and X is an integer type not narrower than
8034 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8040 {
8046 }
8048 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8049 type of X and Y (integer types only). */
8054 {
8055 /* Be careful not to introduce new overflows. */
8056 tree mult_type;
8059 else
8063 {
8070 }
8071 }
8077 {
8084 }
8095 /* Convert fabs((double)float) into (double)fabsf(float). */
8098 {
8104 targ0));
8105 }
8109 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8128 /* Note that the operand of this must be an int
8129 and its values must be 0 or 1.
8130 ("true" is a fixed value perhaps depending on the language,
8131 but we don't handle values other than 1 correctly yet.) */
8138 /* Fold *&X to X if X is an lvalue. */
8140 {
8147 }
8153 }
8156 /* If the operation was a conversion do _not_ mark a resulting constant
8157 with TREE_OVERFLOW if the original constant was not. These conversions
8158 have implementation defined behavior and retaining the TREE_OVERFLOW
8159 flag here would confuse later passes such as VRP. */
8160 tree
8163 {
8172 }
8174 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8175 operands OP0 and OP1. LOC is the location of the resulting expression.
8176 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8177 Return the folded expression if folding is successful. Otherwise,
8178 return NULL_TREE. */
8179 static tree
8182 {
8183 tree tem;
8185 /* We only do these simplifications if we are optimizing. */
8189 /* Check for things like (A || B) && (A || C). We can convert this
8190 to A || (B && C). Note that either operator can be any of the four
8191 truth and/or operations and the transformation will still be
8192 valid. Also note that we only care about order for the
8193 ANDIF and ORIF operators. If B contains side effects, this
8194 might change the truth-value of A. */
8201 {
8221 /* This case if tricky because we must either have commutative
8222 operators or else A10 must not have side-effects. */
8228 a01);
8229 }
8231 /* See if we can build a range comparison. */
8237 {
8241 }
8245 {
8249 }
8251 /* Check for the possibility of merging component references. If our
8252 lhs is another similar operation, try to merge its rhs with our
8253 rhs. Then try to merge our lhs and rhs. */
8264 logical_op_non_short_circuit
8267 && !flag_sanitize_coverage
8272 {
8279 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8280 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8281 We don't want to pack more than two leafs to a non-IF AND/OR
8282 expression.
8283 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8284 equal to IF-CODE, then we don't want to add right-hand operand.
8285 If the inner right-hand side of left-hand operand has
8286 side-effects, or isn't simple, then we can't add to it,
8287 as otherwise we might destroy if-sequence. */
8290 /* Needed for sequence points to handle trappings, and
8291 side-effects. */
8293 {
8295 arg1);
8297 tem);
8298 }
8299 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8300 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8303 /* Needed for sequence points to handle trappings, and
8304 side-effects. */
8306 {
8311 }
8312 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8313 into (A OR B).
8314 For sequence point consistancy, we need to check for trapping,
8315 and side-effects. */
8319 }
8322 }
8324 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8325 by changing CODE to reduce the magnitude of constants involved in
8326 ARG0 of the comparison.
8327 Returns a canonicalized comparison tree if a simplification was
8328 possible, otherwise returns NULL_TREE.
8329 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8330 valid if signed overflow is undefined. */
8332 static tree
8336 {
8341 /* Match A +- CST code arg1. We can change this only if overflow
8342 is undefined. */
8345 /* In principle pointers also have undefined overflow behavior,
8346 but that causes problems elsewhere. */
8353 /* Identify the constant in arg0 and its sign. */
8357 /* Overflowed constants and zero will cause problems. */
8362 /* See if we can reduce the magnitude of the constant in
8363 arg0 by changing the comparison code. */
8364 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8368 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8372 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8376 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8380 else
8384 /* Now build the constant reduced in magnitude. But not if that
8385 would produce one outside of its types range. */
8401 }
8403 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8404 overflow further. Try to decrease the magnitude of constants involved
8405 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8406 and put sole constants at the second argument position.
8407 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8409 static tree
8412 {
8413 tree t;
8418 /* Try canonicalization by simplifying arg0. */
8423 {
8427 }
8429 /* Try canonicalization by simplifying arg1 using the swapped
8430 comparison. */
8438 }
8440 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8441 space. This is used to avoid issuing overflow warnings for
8442 expressions like &p->x which cannot wrap. */
8444 static bool
8446 {
8453 poly_wide_int wi_offset;
8459 else
8464 precision);
8479 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8480 array. */
8489 }
8491 /* Return a positive integer when the symbol DECL is known to have
8492 a nonzero address, zero when it's known not to (e.g., it's a weak
8493 symbol), and a negative integer when the symbol is not yet in the
8494 symbol table and so whether or not its address is zero is unknown.
8495 For function local objects always return positive integer. */
8496 static int
8498 {
8503 /* Function local objects are never NULL. */
8511 }
8513 /* Subroutine of fold_binary. This routine performs all of the
8514 transformations that are common to the equality/inequality
8515 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8516 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8517 fold_binary should call fold_binary. Fold a comparison with
8518 tree code CODE and type TYPE with operands OP0 and OP1. Return
8519 the folded comparison or NULL_TREE. */
8521 static tree
8524 {
8534 /* For comparisons of pointers we can decompose it to a compile time
8535 comparison of the base objects and the offsets into the object.
8536 This requires at least one operand being an ADDR_EXPR or a
8537 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8543 {
8546 machine_mode mode;
8550 /* Get base and offset for the access. Strip ADDR_EXPR for
8551 get_inner_reference, but put it back by stripping INDIRECT_REF
8552 off the base object if possible. indirect_baseN will be true
8553 if baseN is not an address but refers to the object itself. */
8556 {
8557 base0
8563 else
8565 }
8567 {
8571 {
8572 base0
8578 else
8580 }
8583 else
8587 {
8594 }
8595 }
8599 {
8600 base1
8606 else
8608 }
8610 {
8614 {
8615 base1
8621 else
8623 }
8626 else
8630 {
8637 }
8638 }
8640 /* If we have equivalent bases we might be able to simplify. */
8644 {
8645 /* We can fold this expression to a constant if the non-constant
8646 offset parts are equal. */
8650 && (equality_code
8651 || (indirect_base0
8654 {
8660 "occur when comparing P +- C1 with "
8662 WARN_STRICT_OVERFLOW_CONDITIONAL);
8665 {
8703 }
8704 }
8705 /* We can simplify the comparison to a comparison of the variable
8706 offset parts if the constant offset parts are equal.
8707 Be careful to use signed sizetype here because otherwise we
8708 mess with array offsets in the wrong way. This is possible
8709 because pointer arithmetic is restricted to retain within an
8710 object and overflow on pointer differences is undefined as of
8711 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8713 && (equality_code
8714 || (indirect_base0
8717 {
8718 /* By converting to signed sizetype we cover middle-end pointer
8719 arithmetic which operates on unsigned pointer types of size
8720 type size and ARRAY_REF offsets which are properly sign or
8721 zero extended from their type in case it is narrower than
8722 sizetype. */
8725 else
8729 else
8736 "occur when comparing P +- C1 with "
8738 WARN_STRICT_OVERFLOW_COMPARISON);
8741 }
8742 }
8743 /* For equal offsets we can simplify to a comparison of the
8744 base addresses. */
8746 && (indirect_base0
8748 && (indirect_base1
8753 {
8759 }
8760 /* Comparison between an ordinary (non-weak) symbol and a null
8761 pointer can be eliminated since such symbols must have a non
8762 null address. In C, relational expressions between pointers
8763 to objects and null pointers are undefined. The results
8764 below follow the C++ rules with the additional property that
8765 every object pointer compares greater than a null pointer.
8766 */
8769 /* Avoid folding references to struct members at offset 0 to
8770 prevent tests like '&ptr->firstmember == 0' from getting
8771 eliminated. When ptr is null, although the -> expression
8772 is strictly speaking invalid, GCC retains it as a matter
8773 of QoI. See PR c/44555. */
8776 && indirect_base0
8777 /* The caller guarantees that when one of the arguments is
8778 constant (i.e., null in this case) it is second. */
8780 {
8782 {
8793 }
8794 }
8795 }
8797 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8798 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8799 the resulting offset is smaller in absolute value than the
8800 original one and has the same sign. */
8809 {
8814 tree cst;
8816 "occur when combining constants around "
8819 /* Put the constant on the side where it doesn't overflow and is
8820 of lower absolute value and of same sign than before. */
8827 {
8830 variable1,
8834 }
8842 {
8848 variable2);
8849 }
8850 }
8856 /* If we are comparing an expression that just has comparisons
8857 of two integer values, arithmetic expressions of those comparisons,
8858 and constants, we can simplify it. There are only three cases
8859 to check: the two values can either be equal, the first can be
8860 greater, or the second can be greater. Fold the expression for
8861 those three values. Since each value must be 0 or 1, we have
8862 eight possibilities, each of which corresponds to the constant 0
8863 or 1 or one of the six possible comparisons.
8865 This handles common cases like (a > b) == 0 but also handles
8866 expressions like ((x > y) - (y > x)) > 0, which supposedly
8867 occur in macroized code. */
8870 {
8874 /* Don't handle degenerate cases here; they should already
8875 have been handled anyway. */
8884 {
8888 /* We can't just pass T to eval_subst in case cval1 or cval2
8889 was the same as ARG1. */
8891 tree high_result
8895 arg1);
8896 tree equal_result
8900 arg1);
8901 tree low_result
8905 arg1);
8907 /* All three of these results should be 0 or 1. Confirm they are.
8908 Then use those values to select the proper code to use. */
8913 {
8914 /* Make a 3-bit mask with the high-order bit being the
8915 value for `>', the next for '=', and the low for '<'. */
8919 {
8921 /* Always false. */
8942 /* Always true. */
8944 }
8947 }
8948 }
8949 }
8952 }
8955 /* Subroutine of fold_binary. Optimize complex multiplications of the
8956 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8957 argument EXPR represents the expression "z" of type TYPE. */
8959 static tree
8961 {
8966 {
8969 }
8971 {
8974 }
8975 else
8976 {
8980 }
8989 }
8992 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8993 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8994 true if successful. */
8996 static bool
8998 {
9003 {
9006 }
9008 {
9014 else
9016 }
9017 else
9023 }
9025 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
9026 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
9027 NULL_TREE otherwise. */
9029 tree
9031 {
9052 {
9053 HOST_WIDE_INT index;
9059 }
9062 {
9068 }
9069 else
9071 }
9073 /* Try to fold a pointer difference of type TYPE two address expressions of
9074 array references AREF0 and AREF1 using location LOC. Return a
9075 simplified expression for the difference or NULL_TREE. */
9077 static tree
9081 {
9086 /* If the bases are array references as well, recurse. If the bases
9087 are pointer indirections compute the difference of the pointers.
9088 If the bases are equal, we are set. */
9091 && (base_offset
9093 use_pointer_diff)))
9096 && (base_offset
9097 = use_pointer_diff
9107 {
9113 base_offset,
9116 }
9118 }
9120 /* If the real or vector real constant CST of type TYPE has an exact
9121 inverse, return it, else return NULL. */
9123 tree
9125 {
9126 REAL_VALUE_TYPE r;
9127 tree unit_type;
9128 machine_mode mode;
9131 {
9141 {
9145 tree_vector_builder elts;
9150 {
9155 }
9158 }
9162 }
9163 }
9165 /* Mask out the tz least significant bits of X of type TYPE where
9166 tz is the number of trailing zeroes in Y. */
9167 static wide_int
9169 {
9174 }
9176 /* Return true when T is an address and is known to be nonzero.
9177 For floating point we further ensure that T is not denormal.
9178 Similar logic is present in nonzero_address in rtlanal.h.
9180 If the return value is based on the assumption that signed overflow
9181 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9182 change *STRICT_OVERFLOW_P. */
9184 static bool
9186 {
9190 /* Doing something useful for floating point would need more work. */
9196 {
9199 strict_overflow_p);
9205 strict_overflow_p);
9213 }
9216 {
9219 strict_overflow_p);
9227 strict_overflow_p);
9242 strict_overflow_p);
9246 strict_overflow_p);
9249 {
9261 }
9265 }
9267 }
9269 /* Return true when T is an address and is known to be nonzero.
9270 Handle warnings about undefined signed overflow. */
9272 bool
9274 {
9281 "determining that expression is always "
9283 WARN_STRICT_OVERFLOW_MISC);
9285 }
9287 /* Return true if T is known not to be equal to an integer W. */
9289 bool
9291 {
9293 value_range_kind rtype;
9295 {
9304 {
9309 }
9314 /* If T has some known zero bits and W has any of those bits set,
9315 then T is known not to be equal to W. */
9323 }
9324 }
9326 /* Fold a binary expression of code CODE and type TYPE with operands
9327 OP0 and OP1. LOC is the location of the resulting expression.
9328 Return the folded expression if folding is successful. Otherwise,
9329 return NULL_TREE. */
9331 tree
9334 {
9349 /* Strip any conversions that don't change the mode. This is
9350 safe for every expression, except for a comparison expression
9351 because its signedness is derived from its operands. So, in
9352 the latter case, only strip conversions that don't change the
9353 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9354 preserved.
9356 Note that this is done as an internal manipulation within the
9357 constant folder, in order to find the simplest representation
9358 of the arguments so that their form can be studied. In any
9359 cases, the appropriate type conversions should be put back in
9360 the tree that will get out of the constant folder. */
9363 {
9366 }
9367 else
9368 {
9371 }
9373 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9374 constant but we can't do arithmetic on them. */
9376 {
9379 {
9383 }
9384 }
9386 /* If this is a commutative operation, and ARG0 is a constant, move it
9387 to ARG1 to reduce the number of tests below. */
9392 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9393 to ARG1 to reduce the number of tests below. */
9402 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9404 First check for cases where an arithmetic operation is applied to a
9405 compound, conditional, or comparison operation. Push the arithmetic
9406 operation inside the compound or conditional to see if any folding
9407 can then be done. Convert comparison to conditional for this purpose.
9408 The also optimizes non-constant cases that used to be done in
9409 expand_expr.
9411 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9412 one of the operands is a comparison and the other is a comparison, a
9413 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9414 code below would make the expression more complex. Change it to a
9415 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9416 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9429 {
9433 boolean_type_node,
9441 }
9445 {
9447 {
9452 tem);
9453 }
9455 {
9460 tem);
9461 }
9466 {
9472 }
9477 {
9483 }
9484 }
9487 {
9489 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9492 {
9498 }
9500 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9503 {
9504 tree base;
9505 poly_int64 coffset;
9514 }
9519 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9525 arg1),
9527 arg0)));
9533 {
9534 /* X + (X / CST) * -CST is X % CST. */
9539 {
9548 cst0));
9549 }
9550 }
9552 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9553 one. Make sure the type is not saturating and has the signedness of
9554 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9555 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9562 {
9566 }
9569 {
9570 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9571 (plus (plus (mult) (mult)) (foo)) so that we can
9572 take advantage of the factoring cases below. */
9581 {
9587 else
9600 parg0),
9602 marg)),
9606 return
9612 parg1)));
9613 }
9614 }
9615 else
9616 {
9617 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9618 to __complex__ ( x, y ). This is not the same for SNaNs or
9619 if signed zeros are involved. */
9623 {
9630 {
9634 {
9640 }
9642 {
9648 }
9649 }
9650 }
9652 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9653 We associate floats only if the user has specified
9654 -fassociative-math. */
9658 {
9663 {
9664 tree tree0;
9667 }
9668 }
9669 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9670 We associate floats only if the user has specified
9671 -fassociative-math. */
9675 {
9680 {
9681 tree tree0;
9684 }
9685 }
9686 }
9688 bit_rotate:
9689 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9690 is a rotate of A by C1 bits. */
9691 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9692 is a rotate of A by B bits.
9693 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9694 though in this case CODE must be | and not + or ^, otherwise
9695 it doesn't return A when B is 0. */
9696 {
9698 tree rtype;
9707 /* Only create rotates in complete modes. Other cases are not
9708 expanded properly. */
9711 {
9724 {
9729 }
9734 {
9737 code0 == LSHIFT_EXPR
9740 }
9742 {
9752 {
9756 orig_tree01);
9758 }
9759 }
9763 {
9774 {
9778 orig_tree01);
9780 }
9781 }
9782 }
9783 }
9785 associate:
9786 /* In most languages, can't associate operations on floats through
9787 parentheses. Rather than remember where the parentheses were, we
9788 don't associate floats at all, unless the user has specified
9789 -fassociative-math.
9790 And, we need to make sure type is not saturating. */
9794 {
9800 /* Split both trees into variables, constants, and literals. Then
9801 associate each group together, the constants with literals,
9802 then the result with variables. This increases the chances of
9803 literals being recombined later and of generating relocatable
9804 expressions for the sum of a constant and literal. */
9812 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9816 /* With undefined overflow prefer doing association in a type
9817 which wraps on overflow, if that is one of the operand types. */
9820 {
9828 }
9830 /* With undefined overflow we can only associate constants with one
9831 variable, and constants whose association doesn't overflow. */
9834 {
9836 {
9837 /* ??? If split_tree would handle NEGATE_EXPR we could
9838 simply reject these cases and the allowed cases would
9839 be the var0/minus_var1 ones. */
9845 {
9848 }
9855 {
9858 }
9864 /* The only case we can still associate with two variables
9865 is if they cancel out. */
9869 }
9875 }
9877 /* Only do something if we found more than two objects. Otherwise,
9878 nothing has changed and we risk infinite recursion. */
9886 {
9898 {
9902 }
9904 {
9908 }
9910 /* Preserve the MINUS_EXPR if the negative part of the literal is
9911 greater than the positive part. Otherwise, the multiplicative
9912 folding code (i.e extract_muldiv) may be fooled in case
9913 unsigned constants are subtracted, like in the following
9914 example: ((X*2 + 4) - 8U)/2. */
9916 {
9920 /* But avoid ending up with only negated parts. */
9922 {
9926 }
9927 else
9928 {
9932 }
9933 }
9935 /* Don't introduce overflows through reassociation. */
9940 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9947 /* Eliminate minus_con0. */
9949 {
9956 else
9959 }
9961 /* Eliminate minus_var0. */
9963 {
9967 else
9970 }
9972 return
9975 }
9976 }
9982 /* Fold &a[i] - &a[j] to i-j. */
9987 {
9991 code
9995 }
9997 /* Further transformations are not for pointers. */
10001 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
10004 /* If arg0 is e.g. unsigned int and type is int, then this could
10005 introduce UB, because if A is INT_MIN at runtime, the original
10006 expression can be well defined while the latter is not.
10007 See PR83269. */
10016 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
10017 __complex__ ( x, -y ). This is not the same for SNaNs or if
10018 signed zeros are involved. */
10022 {
10029 {
10033 {
10035 arg1r ? arg1r
10040 }
10042 {
10046 arg1i ? arg1i
10049 }
10050 }
10051 }
10053 /* A - B -> A + (-B) if B is easily negatable. */
10057 /* Avoid this transformation if B is a positive REAL_CST. */
10065 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10066 one. Make sure the type is not saturating and has the signedness of
10067 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10068 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10075 {
10079 }
10085 {
10086 /* Transform x * -C into -x * C if x is easily negatable. */
10101 {
10104 "occur when simplifying "
10106 WARN_STRICT_OVERFLOW_MISC);
10108 }
10110 /* Optimize z * conj(z) for integer complex numbers. */
10117 }
10118 else
10119 {
10120 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10121 This is not the same for NaNs or if signed zeros are
10122 involved. */
10128 {
10131 return
10137 return
10142 }
10144 /* Optimize z * conj(z) for floating point complex numbers.
10145 Guarded by flag_unsafe_math_optimizations as non-finite
10146 imaginary components don't produce scalar results. */
10155 }
10159 /* Canonicalize (X & C1) | C2. */
10163 {
10168 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10176 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10178 {
10181 }
10183 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10184 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10185 mode which allows further optimizations. */
10190 {
10195 {
10198 }
10199 }
10202 {
10207 }
10208 }
10210 /* See if this can be simplified into a rotate first. If that
10211 is unsuccessful continue in the association code. */
10215 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10223 /* See if this can be simplified into a rotate first. If that
10224 is unsuccessful continue in the association code. */
10228 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10233 {
10234 tree tem2;
10241 }
10242 /* Fold ~X & 1 as (X & 1) == 0. */
10246 {
10247 tree tem2;
10254 }
10255 /* Fold !X & 1 as X == 0. */
10258 {
10262 }
10264 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10265 multiple of 1 << CST. */
10267 {
10274 }
10276 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10277 bits from CST2. */
10281 {
10283 wide_int masked
10290 {
10291 /* Avoid the transform if arg1 is a mask of some
10292 mode which allows further optimizations. */
10299 }
10300 }
10302 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10305 {
10310 return
10312 }
10317 /* Don't touch a floating-point divide by zero unless the mode
10318 of the constant can represent infinity. */
10324 /* (-A) / (-B) -> A / B */
10336 /* Fall through */
10339 /* Simplify A / (B << N) where A and B are positive and B is
10340 a power of 2, to A >> (N + log2(B)). */
10345 {
10348 {
10356 WARN_STRICT_OVERFLOW_MISC);
10362 }
10363 }
10365 /* Fall through */
10373 /* Convert -A / -B to A / B when the type is signed and overflow is
10374 undefined. */
10378 {
10381 "when distributing negation across "
10383 WARN_STRICT_OVERFLOW_MISC);
10388 }
10392 {
10395 "when distributing negation across "
10397 WARN_STRICT_OVERFLOW_MISC);
10402 }
10404 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10405 operation, EXACT_DIV_EXPR.
10407 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10408 At one time others generated faster code, it's not clear if they do
10409 after the last round to changes to the DIV code in expmed.c. */
10420 {
10424 WARN_STRICT_OVERFLOW_MISC);
10426 }
10438 {
10442 WARN_STRICT_OVERFLOW_MISC);
10444 }
10452 /* Since negative shift count is not well-defined,
10453 don't try to compute it in the compiler. */
10459 /* If we have a rotate of a bit operation with the rotate count and
10460 the second operand of the bit operation both constant,
10461 permute the two operations. */
10467 {
10475 }
10477 /* Two consecutive rotates adding up to the some integer
10478 multiple of the precision of the type can be ignored. */
10494 /* Note that the operands of this must be ints
10495 and their values must be 0 or 1.
10496 ("true" is a fixed value perhaps depending on the language.) */
10497 /* If first arg is constant zero, return it. */
10500 /* FALLTHRU */
10502 /* If either arg is constant true, drop it. */
10506 /* Preserve sequence points. */
10509 /* If second arg is constant zero, result is zero, but first arg
10510 must be evaluated. */
10513 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10514 case will be handled here. */
10518 /* !X && X is always false. */
10522 /* X && !X is always false. */
10527 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10528 means A >= Y && A != MAX, but in this case we know that
10529 A < X <= MAX. */
10533 {
10541 }
10550 /* Note that the operands of this must be ints
10551 and their values must be 0 or true.
10552 ("true" is a fixed value perhaps depending on the language.) */
10553 /* If first arg is constant true, return it. */
10556 /* FALLTHRU */
10558 /* If either arg is constant zero, drop it. */
10562 /* Preserve sequence points. */
10565 /* If second arg is constant true, result is true, but we must
10566 evaluate first arg. */
10569 /* Likewise for first arg, but note this only occurs here for
10570 TRUTH_OR_EXPR. */
10574 /* !X || X is always true. */
10578 /* X || !X is always true. */
10583 /* (X && !Y) || (!X && Y) is X ^ Y */
10586 {
10603 }
10612 /* If the second arg is constant zero, drop it. */
10615 /* If the second arg is constant true, this is a logical inversion. */
10617 {
10620 }
10621 /* Identical arguments cancel to zero. */
10625 /* !X ^ X is always true. */
10630 /* X ^ !X is always true. */
10646 /* bool_var != 1 becomes !bool_var. */
10653 /* bool_var == 0 becomes !bool_var. */
10660 /* !exp != 0 becomes !exp */
10665 /* If this is an EQ or NE comparison with zero and ARG0 is
10666 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10667 two operations, but the latter can be done in one less insn
10668 on machines that have only two-operand insns or on which a
10669 constant cannot be the first operand. */
10672 {
10677 {
10684 arg1);
10685 }
10688 {
10695 arg1);
10696 }
10697 }
10699 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10700 C1 is a valid shift constant, and C2 is a power of two, i.e.
10701 a single bit. */
10705 == INTEGER_CST
10708 {
10713 /* Check for a valid shift count. */
10715 {
10719 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10720 can be rewritten as (X & (C2 << C1)) != 0. */
10722 {
10727 }
10728 /* Otherwise, for signed (arithmetic) shifts,
10729 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10730 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10734 /* Otherwise, of unsigned (logical) shifts,
10735 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10736 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10737 else
10741 arg000);
10742 }
10743 }
10745 /* If this is a comparison of a field, we may be able to simplify it. */
10748 /* Handle the constant case even without -O
10749 to make sure the warnings are given. */
10751 {
10755 }
10757 /* Optimize comparisons of strlen vs zero to a compare of the
10758 first character of the string vs zero. To wit,
10759 strlen(ptr) == 0 => *ptr == 0
10760 strlen(ptr) != 0 => *ptr != 0
10761 Other cases should reduce to one of these two (or a constant)
10762 due to the return value of strlen being unsigned. */
10764 {
10772 {
10773 tree ptrtype
10775 TYPE_QUAL_CONST));
10781 }
10782 }
10784 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10785 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10789 {
10794 {
10796 {
10799 }
10802 }
10803 }
10805 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10806 (X & C) == 0 when C is a single bit. */
10811 {
10818 arg1));
10819 }
10821 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10822 constant C is a power of two, i.e. a single bit. */
10829 {
10833 }
10835 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10836 when is C is a power of two, i.e. a single bit. */
10843 {
10849 }
10853 {
10856 }
10858 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10861 {
10869 {
10875 }
10877 {
10883 }
10885 {
10891 }
10893 {
10899 }
10900 }
10904 {
10911 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10912 operand_equal_p guarantees no side-effects so we don't need
10913 to use omit_one_operand on Z. */
10917 arg10));
10921 arg11));
10925 arg10));
10929 arg11));
10931 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10934 {
10940 }
10941 }
10943 /* Attempt to simplify equality/inequality comparisons of complex
10944 values. Only lower the comparison if the result is known or
10945 can be simplified to a single scalar comparison. */
10950 {
10955 {
10958 }
10959 else
10960 {
10963 }
10966 {
10969 }
10970 else
10971 {
10974 }
10978 {
10980 {
10985 }
10986 else
10987 {
10992 }
10993 }
10997 {
10999 {
11004 }
11005 else
11006 {
11011 }
11012 }
11013 }
11025 /* Transform comparisons of the form X +- C CMP X. */
11030 {
11035 /* (X - c) > X becomes false. */
11041 /* Likewise (X + c) < X becomes false. */
11047 /* Convert (X - c) <= X to true. */
11054 /* Convert (X + c) >= X to true. */
11060 }
11062 /* If we are comparing an ABS_EXPR with a constant, we can
11063 convert all the cases into explicit comparisons, but they may
11064 well not be faster than doing the ABS and one comparison.
11065 But ABS (X) <= C is a range comparison, which becomes a subtraction
11066 and a comparison, and is probably faster. */
11080 /* Convert ABS_EXPR<x> >= 0 to true. */
11087 {
11090 "when simplifying comparison of "
11092 WARN_STRICT_OVERFLOW_CONDITIONAL);
11095 arg0);
11096 }
11098 /* Convert ABS_EXPR<x> < 0 to false. */
11103 {
11106 "when simplifying comparison of "
11108 WARN_STRICT_OVERFLOW_CONDITIONAL);
11111 arg0);
11112 }
11114 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11115 and similarly for >= into !=. */
11125 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11126 otherwise Y might be >= # of bits in X's type and thus e.g.
11127 (unsigned char) (1 << Y) for Y 15 might be 0.
11128 If the cast is widening, then 1 << Y should have unsigned type,
11129 otherwise if Y is number of bits in the signed shift type minus 1,
11130 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11131 31 might be 0xffffffff80000000. */
11142 {
11148 }
11160 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11161 {
11173 }
11178 /* When pedantic, a compound expression can be neither an lvalue
11179 nor an integer constant expression. */
11182 /* Don't let (0, 0) be null pointer constant. */
11188 /* An ASSERT_EXPR should never be passed to fold_binary. */
11194 }
11196 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11197 ((A & N) + B) & M -> (A + B) & M
11198 Similarly if (N & M) == 0,
11199 ((A | N) + B) & M -> (A + B) & M
11200 and for - instead of + (or unary - instead of +)
11201 and/or ^ instead of |.
11202 If B is constant and (B & M) == 0, fold into A & M.
11204 This function is a helper for match.pd patterns. Return non-NULL
11205 type in which the simplified operation should be performed only
11206 if any optimization is possible.
11208 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11209 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11210 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11211 +/-. */
11212 tree
11217 {
11232 wide_int cst0;
11234 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11235 arg1 (M) is == (1LL << cst) - 1.
11236 Store C into PMOP[0] and D into PMOP[1]. */
11243 {
11250 {
11253 }
11256 /* If C or D is of the form (A & N) where
11257 (N & M) == M, or of the form (A | N) or
11258 (A ^ N) where (N & M) == 0, replace it with A. */
11264 /* If C or D is a N where (N & M) == 0, it can be
11265 omitted (replaced with 0). */
11270 /* Similarly, with C - N where (-N & M) == 0. */
11278 }
11280 /* Only build anything new if we optimized one or both arguments above. */
11286 else
11288 }
11290 /* Used by contains_label_[p1]. */
11292 struct contains_label_data
11293 {
11296 };
11298 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11299 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11300 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11302 static tree
11304 {
11307 {
11318 {
11326 }
11335 }
11336 }
11338 /* Return whether the sub-tree ST contains a label which is accessible from
11339 outside the sub-tree. */
11341 static bool
11343 {
11347 }
11349 /* Fold a ternary expression of code CODE and type TYPE with operands
11350 OP0, OP1, and OP2. Return the folded expression if folding is
11351 successful. Otherwise, return NULL_TREE. */
11353 tree
11356 {
11357 tree tem;
11364 /* If this is a commutative operation, and OP0 is a constant, move it
11365 to OP1 to reduce the number of tests below. */
11374 /* Strip any conversions that don't change the mode. This is safe
11375 for every expression, except for a comparison expression because
11376 its signedness is derived from its operands. So, in the latter
11377 case, only strip conversions that don't change the signedness.
11379 Note that this is done as an internal manipulation within the
11380 constant folder, in order to find the simplest representation of
11381 the arguments so that their form can be studied. In any cases,
11382 the appropriate type conversions should be put back in the tree
11383 that will get out of the constant folder. */
11385 {
11388 }
11391 {
11394 }
11397 {
11400 }
11403 {
11407 {
11413 }
11418 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11419 so all simple results must be passed through pedantic_non_lvalue. */
11421 {
11424 /* Only optimize constant conditions when the selected branch
11425 has the same type as the COND_EXPR. This avoids optimizing
11426 away "c ? x : throw", where the throw has a void type.
11427 Avoid throwing away that operand which contains label. */
11434 }
11436 {
11443 {
11446 {
11454 }
11459 }
11460 }
11462 /* If we have A op B ? A : C, we may be able to convert this to a
11463 simpler expression, depending on the operation and the values
11464 of B and C. Signed zeros prevent all of these transformations,
11465 for reasons given above each one.
11467 Also try swapping the arguments and inverting the conditional. */
11471 {
11475 }
11480 {
11484 {
11488 }
11489 }
11491 /* If the second operand is simpler than the third, swap them
11492 since that produces better jump optimization results. */
11495 {
11497 /* See if this can be inverted. If it can't, possibly because
11498 it was a floating-point inequality comparison, don't do
11499 anything. */
11503 }
11505 /* Convert A ? 1 : 0 to simply A. */
11510 /* If we try to convert OP0 to our type, the
11511 call to fold will try to move the conversion inside
11512 a COND, which will recurse. In that case, the COND_EXPR
11513 is probably the best choice, so leave it alone. */
11517 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11518 over COND_EXPR in cases such as floating point comparisons. */
11527 arg0)));
11529 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11534 {
11535 /* sign_bit_p looks through both zero and sign extensions,
11536 but for this optimization only sign extensions are
11537 usable. */
11540 {
11543 {
11546 }
11548 }
11549 /* sign_bit_p only checks ARG1 bits within A's precision.
11550 If <sign bit of A> has wider type than A, bits outside
11551 of A's precision in <sign bit of A> need to be checked.
11552 If they are all 0, this optimization needs to be done
11553 in unsigned A's type, if they are all 1 in signed A's type,
11554 otherwise this can't be done. */
11560 {
11562 tree tem_type;
11575 {
11578 }
11580 {
11583 }
11584 else
11586 }
11589 return
11595 arg1)));
11596 }
11598 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11599 already handled above. */
11604 {
11614 op1);
11615 }
11617 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11618 is probably obsolete because the first operand should be a
11619 truth value (that's why we have the two cases above), but let's
11620 leave it in until we can confirm this for all front-ends. */
11628 /* operand_equal_p compares just value, not precision, so e.g.
11629 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
11630 second operand 32-bit -128, which is not a power of two (or vice
11631 versa. */
11638 /* Disable the transformations below for vectors, since
11639 fold_binary_op_with_conditional_arg may undo them immediately,
11640 yielding an infinite loop. */
11644 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11653 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11658 {
11660 /* Only perform transformation if ARG0 is easily inverted. */
11664 ? BIT_IOR_EXPR
11667 op1);
11668 }
11670 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11675 {
11677 /* Only perform transformation if ARG0 is easily inverted. */
11683 op2);
11684 }
11686 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11698 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11699 of fold_ternary on them. */
11709 {
11720 {
11725 {
11727 {
11732 }
11738 }
11739 }
11740 }
11742 /* On constants we can use native encode/interpret to constant
11743 fold (nearly) all BIT_FIELD_REFs. */
11749 {
11752 /* Limit us to a reasonable amount of work. To relax the
11753 other limitations we need bit-shifting of the buffer
11754 and rounding up the size. */
11758 {
11760 unsigned HOST_WIDE_INT len
11765 {
11770 }
11771 }
11772 }
11777 /* Perform constant folding of BIT_INSERT_EXPR. */
11781 {
11782 /* Build a vector of integers from the tree mask. */
11783 vec_perm_builder builder;
11787 /* Create a vec_perm_indices for the integer vector. */
11792 }
11796 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11799 {
11805 wide_int tem2
11809 }
11814 {
11816 unsigned HOST_WIDE_INT elsize
11819 {
11825 {
11831 }
11832 }
11833 }
11839 }
11841 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11842 of an array (or vector). */
11844 tree
11846 {
11851 {
11854 {
11855 /* Static constructors for variably sized objects makes no sense. */
11859 }
11860 }
11871 offset_int max_index;
11876 {
11877 /* Array constructor might explicitly set index, or specify a range,
11878 or leave index NULL meaning that it is next index after previous
11879 one. */
11881 {
11884 else
11885 {
11889 }
11890 }
11891 else
11892 {
11898 }
11900 /* Do we have match? */
11904 }
11906 }
11908 /* Perform constant folding and related simplification of EXPR.
11909 The related simplifications include x*1 => x, x*0 => 0, etc.,
11910 and application of the associative law.
11911 NOP_EXPR conversions may be removed freely (as long as we
11912 are careful not to change the type of the overall expression).
11913 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11914 but we can constant-fold them if they have constant operands. */
11916 #ifdef ENABLE_FOLD_CHECKING
11917 # define fold(x) fold_1 (x)
11919 static
11920 #endif
11921 tree
11923 {
11927 tree tem;
11930 /* Return right away if a constant. */
11934 /* CALL_EXPR-like objects with variable numbers of operands are
11935 treated specially. */
11937 {
11939 {
11942 }
11944 }
11947 {
11952 {
11970 }
11971 }
11974 {
11976 {
11983 {
11988 }
11991 }
11993 /* Return a VECTOR_CST if possible. */
11995 {
12001 tree val;
12007 }
12015 }
12017 #ifdef ENABLE_FOLD_CHECKING
12018 #undef fold
12025 /* When --enable-checking=fold, compute a digest of expr before
12026 and after actual fold call to see if fold did not accidentally
12027 change original expr. */
12029 tree
12031 {
12032 tree ret;
12052 }
12054 void
12056 {
12067 }
12069 static void
12071 {
12073 }
12075 static void
12078 {
12084 recursive_label:
12094 {
12095 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12103 }
12111 {
12112 /* Allow these fields to be modified. */
12113 tree tmp;
12124 {
12127 }
12128 }
12130 {
12131 /* Allow TREE_NO_WARNING to be set. Perhaps we shouldn't allow that
12132 and change builtins.c etc. instead - see PR89543. */
12138 }
12149 {
12152 {
12168 }
12172 {
12185 }
12202 {
12208 }
12211 {
12213 {
12216 }
12218 }
12229 {
12232 }
12242 }
12243 }
12245 /* Helper function for outputting the checksum of a tree T. When
12246 debugging with gdb, you can "define mynext" to be "next" followed
12247 by "call debug_fold_checksum (op0)", then just trace down till the
12248 outputs differ. */
12250 DEBUG_FUNCTION void
12252 {
12267 }
12269 #endif
12271 /* Fold a unary tree expression with code CODE of type TYPE with an
12272 operand OP0. LOC is the location of the resulting expression.
12273 Return a folded expression if successful. Otherwise, return a tree
12274 expression with code CODE of type TYPE with an operand OP0. */
12276 tree
12279 {
12280 tree tem;
12281 #ifdef ENABLE_FOLD_CHECKING
12290 #endif
12296 #ifdef ENABLE_FOLD_CHECKING
12303 #endif
12305 }
12307 /* Fold a binary tree expression with code CODE of type TYPE with
12308 operands OP0 and OP1. LOC is the location of the resulting
12309 expression. Return a folded expression if successful. Otherwise,
12310 return a tree expression with code CODE of type TYPE with operands
12311 OP0 and OP1. */
12313 tree
12316 MEM_STAT_DECL)
12317 {
12318 tree tem;
12319 #ifdef ENABLE_FOLD_CHECKING
12336 #endif
12342 #ifdef ENABLE_FOLD_CHECKING
12357 #endif
12359 }
12361 /* Fold a ternary tree expression with code CODE of type TYPE with
12362 operands OP0, OP1, and OP2. Return a folded expression if
12363 successful. Otherwise, return a tree expression with code CODE of
12364 type TYPE with operands OP0, OP1, and OP2. */
12366 tree
12369 {
12370 tree tem;
12371 #ifdef ENABLE_FOLD_CHECKING
12395 #endif
12402 #ifdef ENABLE_FOLD_CHECKING
12425 #endif
12427 }
12429 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12430 arguments in ARGARRAY, and a null static chain.
12431 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12432 of type TYPE from the given operands as constructed by build_call_array. */
12434 tree
12437 {
12438 tree tem;
12439 #ifdef ENABLE_FOLD_CHECKING
12458 #endif
12464 #ifdef ENABLE_FOLD_CHECKING
12480 #endif
12482 }
12484 /* Perform constant folding and related simplification of initializer
12485 expression EXPR. These behave identically to "fold_buildN" but ignore
12486 potential run-time traps and exceptions that fold must preserve. */
12488 #define START_FOLD_INIT \
12489 int saved_signaling_nans = flag_signaling_nans;\
12490 int saved_trapping_math = flag_trapping_math;\
12491 int saved_rounding_math = flag_rounding_math;\
12492 int saved_trapv = flag_trapv;\
12493 int saved_folding_initializer = folding_initializer;\
12494 flag_signaling_nans = 0;\
12495 flag_trapping_math = 0;\
12496 flag_rounding_math = 0;\
12497 flag_trapv = 0;\
12498 folding_initializer = 1;
12500 #define END_FOLD_INIT \
12501 flag_signaling_nans = saved_signaling_nans;\
12502 flag_trapping_math = saved_trapping_math;\
12503 flag_rounding_math = saved_rounding_math;\
12504 flag_trapv = saved_trapv;\
12505 folding_initializer = saved_folding_initializer;
12507 tree
12510 {
12511 tree result;
12512 START_FOLD_INIT;
12516 END_FOLD_INIT;
12518 }
12520 tree
12523 {
12524 tree result;
12525 START_FOLD_INIT;
12529 END_FOLD_INIT;
12531 }
12533 tree
12536 {
12537 tree result;
12538 START_FOLD_INIT;
12542 END_FOLD_INIT;
12544 }
12546 #undef START_FOLD_INIT
12547 #undef END_FOLD_INIT
12549 /* Determine if first argument is a multiple of second argument. Return 0 if
12550 it is not, or we cannot easily determined it to be.
12552 An example of the sort of thing we care about (at this point; this routine
12553 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12554 fold cases do now) is discovering that
12556 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12558 is a multiple of
12560 SAVE_EXPR (J * 8)
12562 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12564 This code also handles discovering that
12566 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12568 is a multiple of 8 so we don't have to worry about dealing with a
12569 possible remainder.
12571 Note that we *look* inside a SAVE_EXPR only to determine how it was
12572 calculated; it is not safe for fold to do much of anything else with the
12573 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12574 at run time. For example, the latter example above *cannot* be implemented
12575 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12576 evaluation time of the original SAVE_EXPR is not necessarily the same at
12577 the time the new expression is evaluated. The only optimization of this
12578 sort that would be valid is changing
12580 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12582 divided by 8 to
12584 SAVE_EXPR (I) * SAVE_EXPR (J)
12586 (where the same SAVE_EXPR (J) is used in the original and the
12587 transformed version). */
12589 int
12591 {
12602 {
12604 /* Bitwise and provides a power of two multiple. If the mask is
12605 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12613 {
12619 {
12622 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12624 {
12628 {
12631 }
12632 }
12634 }
12635 }
12640 /* It is impossible to prove if op0 - op1 is multiple of bottom
12641 precisely, so be conservative here checking if both op0 and op1
12642 are multiple of bottom. Note we check the second operand first
12643 since it's usually simpler. */
12648 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12649 as op0 - 3 if the expression has unsigned type. For example,
12650 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12660 {
12662 /* const_binop may not detect overflow correctly,
12663 so check for it explicitly here. */
12671 }
12675 /* Can't handle conversions from non-integral or wider integral type. */
12681 /* fall through */
12698 SIGNED);
12704 {
12707 /* Check for special cases to see if top is defined as multiple
12708 of bottom:
12710 top = (X & ~(bottom - 1) ; bottom is power of 2
12712 or
12714 Y = X % bottom
12715 top = X - Y. */
12734 }
12736 /* fall through */
12744 }
12745 }
12747 #define tree_expr_nonnegative_warnv_p(X, Y) \
12750 #define RECURSE(X) \
12751 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12753 /* Return true if CODE or TYPE is known to be non-negative. */
12755 static bool
12757 {
12760 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12761 have a signed:1 type (where the value is -1 and 0). */
12764 }
12766 /* Return true if (CODE OP0) is known to be non-negative. If the return
12767 value is based on the assumption that signed overflow is undefined,
12768 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12769 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12771 bool
12774 {
12779 {
12781 /* We can't return 1 if flag_wrapv is set because
12782 ABS_EXPR<INT_MIN> = INT_MIN. */
12786 {
12789 }
12797 CASE_CONVERT:
12798 {
12803 {
12807 {
12811 }
12812 }
12814 {
12820 }
12821 }
12826 }
12828 /* We don't know sign of `t', so be conservative and return false. */
12830 }
12832 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12833 value is based on the assumption that signed overflow is undefined,
12834 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12835 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12837 bool
12841 {
12846 {
12852 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12853 both unsigned and at least 2 bits shorter than the result. */
12857 {
12862 {
12866 }
12867 }
12872 {
12873 /* x * x is always non-negative for floating point x
12874 or without overflow. */
12877 {
12882 }
12883 }
12885 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12886 both unsigned and their total bits is shorter than the result. */
12890 {
12909 {
12919 }
12920 }
12947 }
12949 /* We don't know sign of `t', so be conservative and return false. */
12951 }
12953 /* Return true if T is known to be non-negative. If the return
12954 value is based on the assumption that signed overflow is undefined,
12955 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12956 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12958 bool
12960 {
12965 {
12979 /* Limit the depth of recursion to avoid quadratic behavior.
12980 This is expected to catch almost all occurrences in practice.
12981 If this code misses important cases that unbounded recursion
12982 would not, passes that need this information could be revised
12983 to provide it through dataflow propagation. */
12991 }
12992 }
12994 /* Return true if T is known to be non-negative. If the return
12995 value is based on the assumption that signed overflow is undefined,
12996 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12997 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12999 bool
13002 {
13004 {
13005 CASE_CFN_ACOS:
13006 CASE_CFN_ACOSH:
13007 CASE_CFN_CABS:
13008 CASE_CFN_COSH:
13009 CASE_CFN_ERFC:
13010 CASE_CFN_EXP:
13011 CASE_CFN_EXP10:
13012 CASE_CFN_EXP2:
13013 CASE_CFN_FABS:
13014 CASE_CFN_FDIM:
13015 CASE_CFN_HYPOT:
13016 CASE_CFN_POW10:
13017 CASE_CFN_FFS:
13018 CASE_CFN_PARITY:
13019 CASE_CFN_POPCOUNT:
13020 CASE_CFN_CLZ:
13021 CASE_CFN_CLRSB:
13024 /* Always true. */
13027 CASE_CFN_SQRT:
13028 CASE_CFN_SQRT_FN:
13029 /* sqrt(-0.0) is -0.0. */
13034 CASE_CFN_ASINH:
13035 CASE_CFN_ATAN:
13036 CASE_CFN_ATANH:
13037 CASE_CFN_CBRT:
13038 CASE_CFN_CEIL:
13039 CASE_CFN_CEIL_FN:
13040 CASE_CFN_ERF:
13041 CASE_CFN_EXPM1:
13042 CASE_CFN_FLOOR:
13043 CASE_CFN_FLOOR_FN:
13044 CASE_CFN_FMOD:
13045 CASE_CFN_FREXP:
13046 CASE_CFN_ICEIL:
13047 CASE_CFN_IFLOOR:
13048 CASE_CFN_IRINT:
13049 CASE_CFN_IROUND:
13050 CASE_CFN_LCEIL:
13051 CASE_CFN_LDEXP:
13052 CASE_CFN_LFLOOR:
13053 CASE_CFN_LLCEIL:
13054 CASE_CFN_LLFLOOR:
13055 CASE_CFN_LLRINT:
13056 CASE_CFN_LLROUND:
13057 CASE_CFN_LRINT:
13058 CASE_CFN_LROUND:
13059 CASE_CFN_MODF:
13060 CASE_CFN_NEARBYINT:
13061 CASE_CFN_NEARBYINT_FN:
13062 CASE_CFN_RINT:
13063 CASE_CFN_RINT_FN:
13064 CASE_CFN_ROUND:
13065 CASE_CFN_ROUND_FN:
13066 CASE_CFN_SCALB:
13067 CASE_CFN_SCALBLN:
13068 CASE_CFN_SCALBN:
13069 CASE_CFN_SIGNBIT:
13070 CASE_CFN_SIGNIFICAND:
13071 CASE_CFN_SINH:
13072 CASE_CFN_TANH:
13073 CASE_CFN_TRUNC:
13074 CASE_CFN_TRUNC_FN:
13075 /* True if the 1st argument is nonnegative. */
13078 CASE_CFN_FMAX:
13079 CASE_CFN_FMAX_FN:
13080 /* True if the 1st OR 2nd arguments are nonnegative. */
13083 CASE_CFN_FMIN:
13084 CASE_CFN_FMIN_FN:
13085 /* True if the 1st AND 2nd arguments are nonnegative. */
13088 CASE_CFN_COPYSIGN:
13089 CASE_CFN_COPYSIGN_FN:
13090 /* True if the 2nd argument is nonnegative. */
13093 CASE_CFN_POWI:
13094 /* True if the 1st argument is nonnegative or the second
13095 argument is an even integer. */
13101 CASE_CFN_POW:
13102 /* True if the 1st argument is nonnegative or the second
13103 argument is an even integer valued real. */
13105 {
13106 REAL_VALUE_TYPE c;
13107 HOST_WIDE_INT n;
13112 {
13113 REAL_VALUE_TYPE cint;
13117 }
13118 }
13123 }
13125 }
13127 /* Return true if T is known to be non-negative. If the return
13128 value is based on the assumption that signed overflow is undefined,
13129 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13130 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13132 static bool
13134 {
13140 {
13142 {
13146 /* If the initializer is non-void, then it's a normal expression
13147 that will be assigned to the slot. */
13151 /* Otherwise, the initializer sets the slot in some way. One common
13152 way is an assignment statement at the end of the initializer. */
13154 {
13162 else
13164 }
13170 }
13173 {
13179 arg0,
13180 arg1,
13182 }
13195 }
13196 }
13198 #undef RECURSE
13199 #undef tree_expr_nonnegative_warnv_p
13201 /* Return true if T is known to be non-negative. If the return
13202 value is based on the assumption that signed overflow is undefined,
13203 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13204 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13206 bool
13208 {
13215 {
13237 }
13240 {
13266 }
13267 }
13269 /* Return true if `t' is known to be non-negative. Handle warnings
13270 about undefined signed overflow. */
13272 bool
13274 {
13281 "determining that expression is always "
13283 WARN_STRICT_OVERFLOW_MISC);
13285 }
13288 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13289 For floating point we further ensure that T is not denormal.
13290 Similar logic is present in nonzero_address in rtlanal.h.
13292 If the return value is based on the assumption that signed overflow
13293 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13294 change *STRICT_OVERFLOW_P. */
13296 bool
13299 {
13301 {
13304 strict_overflow_p);
13307 {
13313 strict_overflow_p));
13314 }
13319 strict_overflow_p);
13323 }
13326 }
13328 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13329 For floating point we further ensure that T is not denormal.
13330 Similar logic is present in nonzero_address in rtlanal.h.
13332 If the return value is based on the assumption that signed overflow
13333 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13334 change *STRICT_OVERFLOW_P. */
13336 bool
13338 tree type,
13339 tree op0,
13341 {
13344 {
13348 {
13349 /* With the presence of negative values it is hard
13350 to say something. */
13357 /* One of operands must be positive and the other non-negative. */
13358 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13359 overflows, on a twos-complement machine the sum of two
13360 nonnegative numbers can never be zero. */
13362 strict_overflow_p)
13364 strict_overflow_p));
13365 }
13370 {
13372 strict_overflow_p)
13374 strict_overflow_p))
13375 {
13378 }
13379 }
13388 {
13391 }
13398 {
13402 /* When both operands are nonzero, then MAX must be too. */
13404 strict_overflow_p))
13407 /* MAX where operand 0 is positive is positive. */
13409 strict_overflow_p);
13410 }
13411 /* MAX where operand 1 is positive is positive. */
13416 {
13420 }
13425 strict_overflow_p)
13427 strict_overflow_p));
13431 }
13434 }
13436 /* Return true when T is an address and is known to be nonzero.
13437 For floating point we further ensure that T is not denormal.
13438 Similar logic is present in nonzero_address in rtlanal.h.
13440 If the return value is based on the assumption that signed overflow
13441 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13442 change *STRICT_OVERFLOW_P. */
13444 bool
13446 {
13449 {
13454 {
13466 /* For objects in symbol table check if we know they are non-zero.
13467 Don't do anything for variables and functions before symtab is built;
13468 it is quite possible that they will be declared weak later. */
13473 /* Constants are never weak. */
13478 }
13486 {
13490 }
13500 }
13502 }
13504 #define integer_valued_real_p(X) \
13507 #define RECURSE(X) \
13508 ((integer_valued_real_p) (X, depth + 1))
13510 /* Return true if the floating point result of (CODE OP0) has an
13511 integer value. We also allow +Inf, -Inf and NaN to be considered
13512 integer values. Return false for signaling NaN.
13514 DEPTH is the current nesting depth of the query. */
13516 bool
13518 {
13520 {
13527 CASE_CONVERT:
13528 {
13535 }
13539 }
13541 }
13543 /* Return true if the floating point result of (CODE OP0 OP1) has an
13544 integer value. We also allow +Inf, -Inf and NaN to be considered
13545 integer values. Return false for signaling NaN.
13547 DEPTH is the current nesting depth of the query. */
13549 bool
13551 {
13553 {
13563 }
13565 }
13567 /* Return true if the floating point result of calling FNDECL with arguments
13568 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13569 considered integer values. Return false for signaling NaN. If FNDECL
13570 takes fewer than 2 arguments, the remaining ARGn are null.
13572 DEPTH is the current nesting depth of the query. */
13574 bool
13576 {
13578 {
13579 CASE_CFN_CEIL:
13580 CASE_CFN_CEIL_FN:
13581 CASE_CFN_FLOOR:
13582 CASE_CFN_FLOOR_FN:
13583 CASE_CFN_NEARBYINT:
13584 CASE_CFN_NEARBYINT_FN:
13585 CASE_CFN_RINT:
13586 CASE_CFN_RINT_FN:
13587 CASE_CFN_ROUND:
13588 CASE_CFN_ROUND_FN:
13589 CASE_CFN_TRUNC:
13590 CASE_CFN_TRUNC_FN:
13593 CASE_CFN_FMIN:
13594 CASE_CFN_FMIN_FN:
13595 CASE_CFN_FMAX:
13596 CASE_CFN_FMAX_FN:
13601 }
13603 }
13605 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13606 has an integer value. We also allow +Inf, -Inf and NaN to be
13607 considered integer values. Return false for signaling NaN.
13609 DEPTH is the current nesting depth of the query. */
13611 bool
13613 {
13615 {
13623 /* Limit the depth of recursion to avoid quadratic behavior.
13624 This is expected to catch almost all occurrences in practice.
13625 If this code misses important cases that unbounded recursion
13626 would not, passes that need this information could be revised
13627 to provide it through dataflow propagation. */
13631 depth));
13635 }
13637 }
13639 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13640 has an integer value. We also allow +Inf, -Inf and NaN to be
13641 considered integer values. Return false for signaling NaN.
13643 DEPTH is the current nesting depth of the query. */
13645 static bool
13647 {
13649 {
13660 }
13662 }
13664 #undef RECURSE
13665 #undef integer_valued_real_p
13667 /* Return true if the floating point expression T has an integer value.
13668 We also allow +Inf, -Inf and NaN to be considered integer values.
13669 Return false for signaling NaN.
13671 DEPTH is the current nesting depth of the query. */
13673 bool
13675 {
13683 {
13699 }
13702 {
13708 {
13717 }
13721 }
13722 }
13724 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13725 attempt to fold the expression to a constant without modifying TYPE,
13726 OP0 or OP1.
13728 If the expression could be simplified to a constant, then return
13729 the constant. If the expression would not be simplified to a
13730 constant, then return NULL_TREE. */
13732 tree
13734 {
13737 }
13739 /* Given the components of a unary expression CODE, TYPE and OP0,
13740 attempt to fold the expression to a constant without modifying
13741 TYPE or OP0.
13743 If the expression could be simplified to a constant, then return
13744 the constant. If the expression would not be simplified to a
13745 constant, then return NULL_TREE. */
13747 tree
13749 {
13752 }
13754 /* If EXP represents referencing an element in a constant string
13755 (either via pointer arithmetic or array indexing), return the
13756 tree representing the value accessed, otherwise return NULL. */
13758 tree
13760 {
13764 {
13766 tree index;
13767 tree string;
13772 else
13773 {
13777 /* Optimize the special-case of a zero lower bound.
13779 We convert the low_bound to sizetype to avoid some problems
13780 with constant folding. (E.g. suppose the lower bound is 1,
13781 and its mode is QI. Without the conversion,l (ARRAY
13782 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13783 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13789 }
13791 scalar_int_mode char_mode;
13803 }
13805 }
13807 /* Folds a read from vector element at IDX of vector ARG. */
13809 tree
13811 {
13816 {
13820 {
13824 }
13825 }
13827 }
13829 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13830 an integer constant, real, or fixed-point constant.
13832 TYPE is the type of the result. */
13834 static tree
13836 {
13840 {
13846 {
13847 FIXED_VALUE_TYPE f;
13852 /* Propagate overflow flags. */
13856 }
13860 {
13867 }
13870 }
13873 }
13875 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13876 an integer constant or real constant.
13878 TYPE is the type of the result. */
13880 tree
13882 {
13886 {
13888 {
13889 /* If the value is unsigned or non-negative, then the absolute value
13890 is the same as the ordinary value. */
13894 ;
13896 /* If the value is negative, then the absolute value is
13897 its negation. */
13898 else
13901 /* Force to the destination type, set TREE_OVERFLOW for signed
13902 TYPE only. */
13904 }
13910 else
13916 }
13919 }
13921 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13922 constant. TYPE is the type of the result. */
13924 static tree
13926 {
13930 }
13932 /* Given CODE, a relational operator, the target type, TYPE and two
13933 constant operands OP0 and OP1, return the result of the
13934 relational operation. If the result is not a compile time
13935 constant, then return NULL_TREE. */
13937 static tree
13939 {
13942 /* From here on, the only cases we handle are when the result is
13943 known to be a constant. */
13946 {
13950 /* Handle the cases where either operand is a NaN. */
13952 {
13954 {
13982 }
13985 }
13988 }
13991 {
13995 }
13997 /* Handle equality/inequality of complex constants. */
13999 {
14010 else
14012 }
14015 {
14017 {
14018 /* Have vector comparison with scalar boolean result. */
14026 {
14034 }
14036 }
14037 tree_vector_builder elts;
14042 {
14055 }
14058 }
14060 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14062 To compute GT, swap the arguments and do LT.
14063 To compute GE, do LT and invert the result.
14064 To compute LE, swap the arguments, do LT and invert the result.
14065 To compute NE, do EQ and invert the result.
14067 Therefore, the code below must handle only EQ and LT. */
14070 {
14073 }
14075 /* Note that it is safe to invert for real values here because we
14076 have already handled the one case that it matters. */
14080 {
14083 }
14085 /* Compute a result for LT or EQ if args permit;
14086 Otherwise return T. */
14088 {
14091 else
14093 }
14094 else
14100 }
14102 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14103 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14104 itself. */
14106 tree
14108 {
14109 /* If the expression does not have side effects then we don't have to wrap
14110 it with a cleanup point expression. */
14114 /* If the expression is a return, check to see if the expression inside the
14115 return has no side effects or the right hand side of the modify expression
14116 inside the return. If either don't have side effects set we don't need to
14117 wrap the expression in a cleanup point expression. Note we don't check the
14118 left hand side of the modify because it should always be a return decl. */
14120 {
14127 }
14130 }
14132 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14133 of an indirection through OP0, or NULL_TREE if no simplification is
14134 possible. */
14136 tree
14138 {
14140 tree subtype;
14141 poly_uint64 const_op01;
14150 {
14154 /* *&CONST_DECL -> to the value of the const decl. */
14157 /* *&p => p; make sure to handle *&"str"[cst] here. */
14159 {
14163 else
14165 }
14166 /* *(foo *)&fooarray => fooarray[0] */
14169 && (!in_gimple_form
14171 {
14181 }
14182 /* *(foo *)&complexfoo => __real__ complexfoo */
14186 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14189 {
14193 index);
14194 }
14195 }
14199 {
14205 {
14206 tree op00type;
14210 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14213 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14214 but we want to treat offsets with MSB set as negative.
14215 For the code below negative offsets are invalid and
14216 TYPE_SIZE of the element is something unsigned, so
14217 check whether op01 fits into poly_int64, which implies
14218 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14219 then just use poly_uint64 because we want to treat the
14220 value as unsigned. */
14222 {
14224 poly_uint64 max_offset
14228 {
14233 }
14234 }
14235 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14238 {
14240 const_op01))
14242 }
14243 /* ((foo *)&fooarray)[1] => fooarray[1] */
14246 {
14255 {
14260 }
14261 }
14262 }
14263 }
14265 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14268 && (!in_gimple_form
14270 {
14271 tree type_domain;
14281 NULL_TREE);
14282 }
14285 }
14287 /* Builds an expression for an indirection through T, simplifying some
14288 cases. */
14290 tree
14292 {
14300 }
14302 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14304 tree
14306 {
14311 else
14313 }
14315 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14316 whose result is ignored. The type of the returned tree need not be
14317 the same as the original expression. */
14319 tree
14321 {
14327 {
14338 else
14344 {
14360 }
14365 }
14366 }
14368 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14370 tree
14372 {
14378 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14379 have to do anything. Only do this when we are not given a const,
14380 because in that case, this check is more expensive than just
14381 doing it. */
14383 {
14388 }
14390 /* If divisor is a power of two, simplify this to bit manipulation. */
14392 {
14394 {
14408 }
14409 else
14410 {
14411 tree t;
14417 }
14418 }
14419 else
14420 {
14425 }
14428 }
14430 /* Likewise, but round down. */
14432 tree
14434 {
14441 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14442 have to do anything. Only do this when we are not given a const,
14443 because in that case, this check is more expensive than just
14444 doing it. */
14446 {
14451 }
14453 /* If divisor is a power of two, simplify this to bit manipulation. */
14455 {
14456 tree t;
14460 }
14461 else
14462 {
14467 }
14470 }
14472 /* Returns the pointer to the base of the object addressed by EXP and
14473 extracts the information about the offset of the access, storing it
14474 to PBITPOS and POFFSET. */
14476 static tree
14479 {
14480 tree core;
14481 machine_mode mode;
14483 poly_int64 bitsize;
14487 {
14492 }
14494 {
14500 {
14501 poly_offset_int tem
14507 }
14508 }
14509 else
14510 {
14514 }
14517 }
14519 /* Returns true if addresses of E1 and E2 differ by a constant, false
14520 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14522 bool
14524 {
14539 {
14549 }
14551 {
14552 /* If only one of the offsets is non-constant, the difference cannot
14553 be a constant. */
14555 }
14556 else
14561 }
14563 /* Return OFF converted to a pointer offset type suitable as offset for
14564 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14565 tree
14567 {
14569 }
14571 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14572 tree
14574 {
14577 }
14579 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14580 tree
14582 {
14585 }
14587 /* Return a pointer P to a NUL-terminated string representing the sequence
14588 of constant characters referred to by SRC (or a subsequence of such
14589 characters within it if SRC is a reference to a string plus some
14590 constant offset). If STRLEN is non-null, store the number of bytes
14591 in the string constant including the terminating NUL char. *STRLEN is
14592 typically strlen(P) + 1 in the absence of embedded NUL characters. */
14596 {
14597 tree offset_node;
14598 tree mem_size;
14609 {
14612 else
14614 }
14619 /* STRING_LENGTH is the size of the string literal, including any
14620 embedded NULs. STRING_SIZE is the size of the array the string
14621 literal is stored in. */
14625 /* Ideally this would turn into a gcc_checking_assert over time. */
14631 /* Ideally this would turn into a gcc_checking_assert over time. */
14640 {
14641 /* Compute and store the length of the substring at OFFSET.
14642 All offsets past the initial length refer to null strings. */
14645 else
14647 }
14648 else
14649 {
14651 /* Support only properly NUL-terminated single byte strings. */
14656 }
14659 }
14661 /* Given a tree T, compute which bits in T may be nonzero. */
14663 wide_int
14665 {
14667 {
14685 CASE_CONVERT:
14691 {
14696 }
14700 {
14708 }
14712 {
14720 }
14724 }
14727 }
14729 #if CHECKING_P
14733 /* Helper functions for writing tests of folding trees. */
14735 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14737 static void
14739 tree constant)
14740 {
14742 }
14744 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14745 wrapping WRAPPED_EXPR. */
14747 static void
14749 tree wrapped_expr)
14750 {
14755 }
14757 /* Verify that various arithmetic binary operations are folded
14758 correctly. */
14760 static void
14762 {
14768 /* Addition. */
14769 /* 1 <-- (0 + 1) */
14771 one);
14773 one);
14775 /* (nonlvalue)x <-- (x + 0) */
14777 x);
14779 /* Subtraction. */
14780 /* 0 <-- (x - x) */
14782 zero);
14784 x);
14786 /* Multiplication. */
14787 /* 0 <-- (x * 0) */
14789 zero);
14791 /* (nonlvalue)x <-- (x * 1) */
14793 x);
14794 }
14796 /* Verify that various binary operations on vectors are folded
14797 correctly. */
14799 static void
14801 {
14807 /* Verify equality tests that return a scalar boolean result. */
14813 }
14815 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14817 static void
14819 {
14822 /* This will be 1 if VEC_MODE isn't a vector mode. */
14829 }
14831 /* Run all of the selftests within this file. */
14833 void
14835 {
14839 }