| blob | 5399288dfc5fcdca07d67b2c6ff644119f200afd |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 /*@@ This file should be rewritten to use an arbitrary precision
21 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
22 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
23 @@ The routines that translate from the ap rep should
24 @@ warn if precision et. al. is lost.
25 @@ This would also make life easier when this technology is used
26 @@ for cross-compilers. */
28 /* The entry points in this file are fold, size_int_wide and size_binop.
30 fold takes a tree as argument and returns a simplified tree.
32 size_binop takes a tree code for an arithmetic operation
33 and two operands that are trees, and produces a tree for the
34 result, assuming the type comes from `sizetype'.
36 size_int takes an integer value, and creates a tree constant
37 with type from `sizetype'.
39 Note: Since the folders get called on non-gimple code as well as
40 gimple code, we need to handle GIMPLE tuples as well as their
41 corresponding tree equivalents. */
87 /* Nonzero if we are folding constants inside an initializer; zero
88 otherwise. */
91 /* The following constants represent a bit based encoding of GCC's
92 comparison operators. This encoding simplifies transformations
93 on relational comparison operators, such as AND and OR. */
111 };
144 /* Return EXPR_LOCATION of T if it is not UNKNOWN_LOCATION.
145 Otherwise, return LOC. */
147 static location_t
149 {
152 }
154 /* Similar to protected_set_expr_location, but never modify x in place,
155 if location can and needs to be set, unshare it. */
159 {
165 {
168 }
170 }
171 \f
172 /* If ARG2 divides ARG1 with zero remainder, carries out the exact
173 division and returns the quotient. Otherwise returns
174 NULL_TREE. */
176 tree
178 {
179 widest_int quo;
186 }
187 \f
188 /* This is nonzero if we should defer warnings about undefined
189 overflow. This facility exists because these warnings are a
190 special case. The code to estimate loop iterations does not want
191 to issue any warnings, since it works with expressions which do not
192 occur in user code. Various bits of cleanup code call fold(), but
193 only use the result if it has certain characteristics (e.g., is a
194 constant); that code only wants to issue a warning if the result is
195 used. */
199 /* If a warning about undefined overflow is deferred, this is the
200 warning. Note that this may cause us to turn two warnings into
201 one, but that is fine since it is sufficient to only give one
202 warning per expression. */
206 /* If a warning about undefined overflow is deferred, this is the
207 level at which the warning should be emitted. */
211 /* Start deferring overflow warnings. We could use a stack here to
212 permit nested calls, but at present it is not necessary. */
214 void
216 {
218 }
220 /* Stop deferring overflow warnings. If there is a pending warning,
221 and ISSUE is true, then issue the warning if appropriate. STMT is
222 the statement with which the warning should be associated (used for
223 location information); STMT may be NULL. CODE is the level of the
224 warning--a warn_strict_overflow_code value. This function will use
225 the smaller of CODE and the deferred code when deciding whether to
226 issue the warning. CODE may be zero to mean to always use the
227 deferred code. */
229 void
231 {
233 location_t locus;
238 {
244 }
255 /* Use the smallest code level when deciding to issue the
256 warning. */
265 else
268 }
270 /* Stop deferring overflow warnings, ignoring any deferred
271 warnings. */
273 void
275 {
277 }
279 /* Whether we are deferring overflow warnings. */
281 bool
283 {
285 }
287 /* This is called when we fold something based on the fact that signed
288 overflow is undefined. */
290 void
292 {
294 {
297 {
300 }
301 }
304 }
305 \f
306 /* Return true if the built-in mathematical function specified by CODE
307 is odd, i.e. -f(x) == f(-x). */
309 bool
311 {
313 {
314 CASE_CFN_ASIN:
315 CASE_CFN_ASINH:
316 CASE_CFN_ATAN:
317 CASE_CFN_ATANH:
318 CASE_CFN_CASIN:
319 CASE_CFN_CASINH:
320 CASE_CFN_CATAN:
321 CASE_CFN_CATANH:
322 CASE_CFN_CBRT:
323 CASE_CFN_CPROJ:
324 CASE_CFN_CSIN:
325 CASE_CFN_CSINH:
326 CASE_CFN_CTAN:
327 CASE_CFN_CTANH:
328 CASE_CFN_ERF:
329 CASE_CFN_LLROUND:
330 CASE_CFN_LROUND:
331 CASE_CFN_ROUND:
332 CASE_CFN_SIN:
333 CASE_CFN_SINH:
334 CASE_CFN_TAN:
335 CASE_CFN_TANH:
336 CASE_CFN_TRUNC:
339 CASE_CFN_LLRINT:
340 CASE_CFN_LRINT:
341 CASE_CFN_NEARBYINT:
342 CASE_CFN_RINT:
347 }
349 }
351 /* Check whether we may negate an integer constant T without causing
352 overflow. */
354 bool
356 {
357 tree type;
366 }
368 /* Determine whether an expression T can be cheaply negated using
369 the function negate_expr without introducing undefined overflow. */
371 static bool
373 {
374 tree type;
383 {
388 /* Check that -CST will not overflow type. */
401 /* We want to canonicalize to positive real constants. Pretend
402 that only negative ones can be easily negated. */
410 {
414 /* Steps don't prevent negation. */
421 }
436 /* -(A + B) -> (-B) - A. */
439 /* -(A + B) -> (-A) - B. */
443 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
452 /* INT_MIN/n * n doesn't overflow while negating one operand it does
453 if n is a (negative) power of two. */
464 /* Fall through. */
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 can not be
739 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
740 return NULL_TREE. */
742 static tree
744 {
746 location_t loc;
759 }
760 \f
761 /* Split a tree IN into a constant, literal and variable parts that could be
762 combined with CODE to make IN. "constant" means an expression with
763 TREE_CONSTANT but that isn't an actual constant. CODE must be a
764 commutative arithmetic operation. Store the constant part into *CONP,
765 the literal in *LITP and return the variable part. If a part isn't
766 present, set it to null. If the tree does not decompose in this way,
767 return the entire tree as the variable part and the other parts as null.
769 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
770 case, we negate an operand that was subtracted. Except if it is a
771 literal for which we use *MINUS_LITP instead.
773 If NEGATE_P is true, we are negating all of IN, again except a literal
774 for which we use *MINUS_LITP instead. If a variable part is of pointer
775 type, it is negated after converting to TYPE. This prevents us from
776 generating illegal MINUS pointer expression. LOC is the location of
777 the converted variable part.
779 If IN is itself a literal or constant, return it as appropriate.
781 Note that we do not guarantee that any of the three values will be the
782 same type as IN, but they will have the same signedness and mode. */
784 static tree
788 {
796 /* Strip any conversions that don't change the machine mode or signedness. */
805 /* We can associate addition and subtraction together (even
806 though the C standard doesn't say so) for integers because
807 the value is not affected. For reals, the value might be
808 affected, so we can't. */
814 {
820 /* First see if either of the operands is a literal, then a constant. */
833 /* If we haven't dealt with either operand, this is not a case we can
834 decompose. Otherwise, VAR is either of the ones remaining, if any. */
839 else
842 /* Now do any needed negations. */
849 }
854 {
855 /* -1 - X is folded to ~X, undo that here. Do _not_ do this
856 when IN is constant. */
859 }
860 else
864 {
877 }
887 }
889 /* Re-associate trees split by the above function. T1 and T2 are
890 either expressions to associate or null. Return the new
891 expression, if any. LOC is the location of the new expression. If
892 we build an operation, do it in TYPE and with CODE. */
894 static tree
896 {
898 {
901 }
905 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
906 try to fold this since we will have infinite recursion. But do
907 deal with any NEGATE_EXPRs. */
911 {
913 {
926 }
928 {
931 }
935 }
939 }
940 \f
941 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
942 for use in int_const_binop, size_binop and size_diffop. */
944 static bool
946 {
953 {
962 }
967 }
969 /* Combine two wide ints ARG1 and ARG2 under operation CODE to produce
970 a new constant in RES. Return FALSE if we don't know how to
971 evaluate CODE at compile-time. */
973 bool
977 {
978 wide_int tmp;
981 {
997 {
1001 else
1003 }
1004 else
1008 /* It's unclear from the C standard whether shifts can overflow.
1009 The following code ignores overflow; perhaps a C standard
1010 interpretation ruling is needed. */
1012 else
1019 {
1023 else
1025 }
1026 else
1031 else
1110 }
1112 }
1114 /* Combine two poly int's ARG1 and ARG2 under operation CODE to
1115 produce a new constant in RES. Return FALSE if we don't know how
1116 to evaluate CODE at compile-time. */
1118 static bool
1122 {
1126 {
1144 else
1151 else
1164 }
1166 }
1168 /* Combine two integer constants ARG1 and ARG2 under operation CODE to
1169 produce a new constant. Return NULL_TREE if we don't know how to
1170 evaluate CODE at compile-time. */
1172 tree
1175 {
1177 poly_wide_int poly_res;
1183 {
1188 }
1197 }
1199 /* Return true if binary operation OP distributes over addition in operand
1200 OPNO, with the other operand being held constant. OPNO counts from 1. */
1202 static bool
1204 {
1206 {
1217 }
1218 }
1220 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1221 constant. We assume ARG1 and ARG2 have the same data type, or at least
1222 are the same kind of constant and the same machine mode. Return zero if
1223 combining the constants is not allowed in the current operating mode. */
1225 static tree
1227 {
1228 /* Sanity check for the recursive cases. */
1236 {
1242 }
1245 {
1246 machine_mode mode;
1247 REAL_VALUE_TYPE d1;
1248 REAL_VALUE_TYPE d2;
1249 REAL_VALUE_TYPE value;
1250 REAL_VALUE_TYPE result;
1254 /* The following codes are handled by real_arithmetic. */
1256 {
1267 }
1275 /* Don't perform operation if we honor signaling NaNs and
1276 either operand is a signaling NaN. */
1282 /* Don't perform operation if it would raise a division
1283 by zero exception. */
1289 /* If either operand is a NaN, just return it. Otherwise, set up
1290 for floating-point trap; we return an overflow. */
1292 {
1293 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1294 is off. */
1298 }
1300 {
1301 /* Make resulting NaN value to be qNaN when flag_signaling_nans
1302 is off. */
1306 }
1311 /* Don't constant fold this floating point operation if
1312 the result has overflowed and flag_trapping_math. */
1320 /* Don't constant fold this floating point operation if the
1321 result may dependent upon the run-time rounding mode and
1322 flag_rounding_math is set, or if GCC's software emulation
1323 is unable to accurately represent the result. */
1333 }
1336 {
1337 FIXED_VALUE_TYPE f1;
1338 FIXED_VALUE_TYPE f2;
1339 FIXED_VALUE_TYPE result;
1344 /* The following codes are handled by fixed_arithmetic. */
1346 {
1358 {
1365 }
1370 }
1377 /* Propagate overflow flags. */
1381 }
1384 {
1393 {
1404 mpc_mul);
1418 mpc_div);
1419 /* Fallthru. */
1425 {
1426 /* Keep this algorithm in sync with
1427 tree-complex.c:expand_complex_div_straight().
1429 Expand complex division to scalars, straightforward algorithm.
1430 a / b = ((ar*br + ai*bi)/t) + i((ai*br - ar*bi)/t)
1431 t = br*br + bi*bi
1432 */
1433 tree magsquared
1437 tree t1
1441 tree t2
1448 }
1449 else
1450 {
1451 /* Keep this algorithm in sync with
1452 tree-complex.c:expand_complex_div_wide().
1454 Expand complex division to scalars, modified algorithm to minimize
1455 overflow with wide input ranges. */
1461 {
1462 /* In the TRUE branch, we compute
1463 ratio = br/bi;
1464 div = (br * ratio) + bi;
1465 tr = (ar * ratio) + ai;
1466 ti = (ai * ratio) - ar;
1467 tr = tr / div;
1468 ti = ti / div; */
1479 }
1480 else
1481 {
1482 /* In the FALSE branch, we compute
1483 ratio = d/c;
1484 divisor = (d * ratio) + c;
1485 tr = (b * ratio) + a;
1486 ti = b - (a * ratio);
1487 tr = tr / div;
1488 ti = ti / div; */
1500 }
1501 }
1506 }
1510 }
1516 {
1521 /* We can operate directly on the encoding if:
1523 a3 - a2 == a2 - a1 && b3 - b2 == b2 - b1
1524 implies
1525 (a3 op b3) - (a2 op b2) == (a2 op b2) - (a1 op b1)
1527 Addition and subtraction are the supported operators
1528 for which this is true. */
1531 /* We can operate directly on stepped encodings if:
1533 a3 - a2 == a2 - a1
1534 implies:
1535 (a3 op c) - (a2 op c) == (a2 op c) - (a1 op c)
1537 which is true if (x -> x op c) distributes over addition. */
1539 else
1540 /* Similarly in reverse. */
1542 tree_vector_builder elts;
1547 {
1553 /* It is possible that const_binop cannot handle the given
1554 code and return NULL_TREE */
1558 }
1561 }
1563 /* Shifts allow a scalar offset for a vector. */
1566 {
1569 tree_vector_builder elts;
1574 {
1579 /* It is possible that const_binop cannot handle the given
1580 code and return NULL_TREE. */
1584 }
1587 }
1589 }
1591 /* Overload that adds a TYPE parameter to be able to dispatch
1592 to fold_relational_const. */
1594 tree
1596 {
1600 /* ??? Until we make the const_binop worker take the type of the
1601 result as argument put those cases that need it here. */
1603 {
1620 {
1625 }
1631 {
1647 {
1652 ? NOP_EXPR
1659 }
1662 }
1668 {
1691 {
1704 }
1707 }
1710 }
1715 /* Make sure type and arg0 have the same saturating flag. */
1720 }
1722 /* Compute CODE ARG1 with resulting type TYPE with ARG1 being constant.
1723 Return zero if computing the constants is not possible. */
1725 tree
1727 {
1728 /* Don't perform the operation, other than NEGATE and ABS, if
1729 flag_signaling_nans is on and the operand is a signaling NaN. */
1739 {
1740 CASE_CONVERT:
1747 /* If the source address is 0, and the source address space
1748 cannot have a valid object at 0, fold to dest type null. */
1759 {
1760 /* Can't call fold_negate_const directly here as that doesn't
1761 handle all cases and we might not be able to negate some
1762 constants. */
1767 }
1777 {
1781 }
1789 /* Perform BIT_NOT_EXPR on each element individually. */
1791 {
1792 tree elem;
1794 /* This can cope with stepped encodings because ~x == -1 - x. */
1795 tree_vector_builder elements;
1799 {
1805 }
1808 }
1832 {
1855 else
1860 {
1866 }
1869 }
1878 }
1881 }
1883 /* Create a sizetype INT_CST node with NUMBER sign extended. KIND
1884 indicates which particular sizetype to create. */
1886 tree
1888 {
1890 }
1891 \f
1892 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1893 is a tree code. The type of the result is taken from the operands.
1894 Both must be equivalent integer types, ala int_binop_types_match_p.
1895 If the operands are constant, so is the result. */
1897 tree
1899 {
1908 /* Handle the special case of two poly_int constants faster. */
1910 {
1911 /* And some specific cases even faster than that. */
1913 {
1918 }
1920 {
1923 }
1925 {
1928 }
1930 /* Handle general case of two integer constants. For sizetype
1931 constant calculations we always want to know about overflow,
1932 even in the unsigned case. */
1936 }
1939 }
1941 /* Given two values, either both of sizetype or both of bitsizetype,
1942 compute the difference between the two values. Return the value
1943 in signed type corresponding to the type of the operands. */
1945 tree
1947 {
1949 tree ctype;
1954 /* If the type is already signed, just do the simple thing. */
1962 else
1965 /* If either operand is not a constant, do the conversions to the signed
1966 type and subtract. The hardware will do the right thing with any
1967 overflow in the subtraction. */
1973 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1974 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1975 overflow) and negate (which can't either). Special-case a result
1976 of zero while we're here. */
1982 else
1986 MINUS_EXPR,
1988 }
1989 \f
1990 /* A subroutine of fold_convert_const handling conversions of an
1991 INTEGER_CST to another integer type. */
1993 static tree
1995 {
1996 /* Given an integer constant, make new constant with new type,
1997 appropriately sign-extended or truncated. Use widest_int
1998 so that any extension is done according ARG1's type. */
2002 }
2004 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2005 to an integer type. */
2007 static tree
2009 {
2011 tree t;
2013 /* The following code implements the floating point to integer
2014 conversion rules required by the Java Language Specification,
2015 that IEEE NaNs are mapped to zero and values that overflow
2016 the target precision saturate, i.e. values greater than
2017 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2018 are mapped to INT_MIN. These semantics are allowed by the
2019 C and C++ standards that simply state that the behavior of
2020 FP-to-integer conversion is unspecified upon overflow. */
2022 wide_int val;
2023 REAL_VALUE_TYPE r;
2027 {
2034 }
2036 /* If R is NaN, return zero and show we have an overflow. */
2038 {
2041 }
2043 /* See if R is less than the lower bound or greater than the
2044 upper bound. */
2047 {
2051 {
2054 }
2055 }
2058 {
2061 {
2064 {
2067 }
2068 }
2069 }
2076 }
2078 /* A subroutine of fold_convert_const handling conversions of a
2079 FIXED_CST to an integer type. */
2081 static tree
2083 {
2084 tree t;
2086 scalar_mode mode;
2088 /* Right shift FIXED_CST to temp by fbit. */
2092 {
2094 HOST_BITS_PER_DOUBLE_INT,
2097 /* Left shift temp to temp_trunc by fbit. */
2099 HOST_BITS_PER_DOUBLE_INT,
2101 }
2102 else
2103 {
2106 }
2108 /* If FIXED_CST is negative, we need to round the value toward 0.
2109 By checking if the fractional bits are not zero to add 1 to temp. */
2115 /* Given a fixed-point constant, make new constant with new type,
2116 appropriately sign-extended or truncated. */
2124 }
2126 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2127 to another floating point type. */
2129 static tree
2131 {
2132 REAL_VALUE_TYPE value;
2133 tree t;
2135 /* Don't perform the operation if flag_signaling_nans is on
2136 and the operand is a signaling NaN. */
2144 /* If converting an infinity or NAN to a representation that doesn't
2145 have one, set the overflow bit so that we can produce some kind of
2146 error message at the appropriate point if necessary. It's not the
2147 most user-friendly message, but it's better than nothing. */
2154 /* Regular overflow, conversion produced an infinity in a mode that
2155 can't represent them. */
2160 else
2163 }
2165 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2166 to a floating point type. */
2168 static tree
2170 {
2171 REAL_VALUE_TYPE value;
2172 tree t;
2180 }
2182 /* A subroutine of fold_convert_const handling conversions a FIXED_CST
2183 to another fixed-point type. */
2185 static tree
2187 {
2188 FIXED_VALUE_TYPE value;
2189 tree t;
2196 /* Propagate overflow flags. */
2200 }
2202 /* A subroutine of fold_convert_const handling conversions an INTEGER_CST
2203 to a fixed-point type. */
2205 static tree
2207 {
2208 FIXED_VALUE_TYPE value;
2209 tree t;
2211 double_int di;
2218 else
2226 /* Propagate overflow flags. */
2230 }
2232 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2233 to a fixed-point type. */
2235 static tree
2237 {
2238 FIXED_VALUE_TYPE value;
2239 tree t;
2247 /* Propagate overflow flags. */
2251 }
2253 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2254 type TYPE. If no simplification can be done return NULL_TREE. */
2256 static tree
2258 {
2263 /* We can't widen types, since the runtime value could overflow the
2264 original type before being extended to the new type. */
2275 {
2282 }
2284 {
2291 }
2293 {
2300 }
2302 {
2305 {
2308 /* We can't handle steps directly when extending, since the
2309 values need to wrap at the original precision first. */
2310 bool step_ok_p
2314 tree_vector_builder v;
2319 {
2325 }
2327 }
2328 }
2330 }
2332 /* Construct a vector of zero elements of vector type TYPE. */
2334 static tree
2336 {
2337 tree t;
2341 }
2343 /* Returns true, if ARG is convertible to TYPE using a NOP_EXPR. */
2345 bool
2347 {
2362 {
2379 }
2380 }
2382 /* Convert expression ARG to type TYPE. Used by the middle-end for
2383 simple conversions in preference to calling the front-end's convert. */
2385 tree
2387 {
2389 tree tem;
2400 {
2403 /* Handle conversions between pointers to different address spaces. */
2408 /* fall through */
2413 {
2417 }
2431 {
2435 }
2437 {
2441 }
2443 {
2447 }
2450 {
2468 }
2473 {
2477 }
2480 {
2494 }
2498 {
2507 integer_zero_node));
2509 {
2513 {
2519 }
2527 }
2531 }
2549 }
2550 fold_convert_exit:
2553 }
2554 \f
2555 /* Return false if expr can be assumed not to be an lvalue, true
2556 otherwise. */
2558 static bool
2560 {
2561 /* We only need to wrap lvalue tree codes. */
2563 {
2594 /* Assume the worst for front-end tree codes. */
2598 }
2601 }
2603 /* Return an expr equal to X but certainly not valid as an lvalue. */
2605 tree
2607 {
2608 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2609 us. */
2616 }
2618 /* When pedantic, return an expr equal to X but certainly not valid as a
2619 pedantic lvalue. Otherwise, return X. */
2621 static tree
2623 {
2625 }
2626 \f
2627 /* Given a tree comparison code, return the code that is the logical inverse.
2628 It is generally not safe to do this for floating-point comparisons, except
2629 for EQ_EXPR, NE_EXPR, ORDERED_EXPR and UNORDERED_EXPR, so we return
2630 ERROR_MARK in this case. */
2632 enum tree_code
2634 {
2640 {
2671 }
2672 }
2674 /* Similar, but return the comparison that results if the operands are
2675 swapped. This is safe for floating-point. */
2677 enum tree_code
2679 {
2681 {
2707 }
2708 }
2711 /* Convert a comparison tree code from an enum tree_code representation
2712 into a compcode bit-based encoding. This function is the inverse of
2713 compcode_to_comparison. */
2715 static enum comparison_code
2717 {
2719 {
2750 }
2751 }
2753 /* Convert a compcode bit-based encoding of a comparison operator back
2754 to GCC's enum tree_code representation. This function is the
2755 inverse of comparison_to_compcode. */
2757 static enum tree_code
2759 {
2761 {
2792 }
2793 }
2795 /* Return true if COND1 tests the opposite condition of COND2. */
2797 bool
2799 {
2802 && (invert_tree_comparison
2809 }
2811 /* Return a tree for the comparison which is the combination of
2812 doing the AND or OR (depending on CODE) of the two operations LCODE
2813 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2814 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2815 if this makes the transformation invalid. */
2817 tree
2822 {
2829 {
2840 }
2843 {
2844 /* Eliminate unordered comparisons, as well as LTGT and ORD
2845 which are not used unless the mode has NaNs. */
2851 }
2853 {
2854 /* Check that the original operation and the optimized ones will trap
2855 under the same condition. */
2866 /* In a short-circuited boolean expression the LHS might be
2867 such that the RHS, if evaluated, will never trap. For
2868 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2869 if neither x nor y is NaN. (This is a mixed blessing: for
2870 example, the expression above will never trap, hence
2871 optimizing it to x < y would be invalid). */
2876 /* If the comparison was short-circuited, and only the RHS
2877 trapped, we may now generate a spurious trap. */
2882 /* If we changed the conditions that cause a trap, we lose. */
2885 }
2891 else
2892 {
2897 }
2898 }
2899 \f
2900 /* Return nonzero if two operands (typically of the same tree node)
2901 are necessarily equal. FLAGS modifies behavior as follows:
2903 If OEP_ONLY_CONST is set, only return nonzero for constants.
2904 This function tests whether the operands are indistinguishable;
2905 it does not test whether they are equal using C's == operation.
2906 The distinction is important for IEEE floating point, because
2907 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2908 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2910 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2911 even though it may hold multiple values during a function.
2912 This is because a GCC tree node guarantees that nothing else is
2913 executed between the evaluation of its "operands" (which may often
2914 be evaluated in arbitrary order). Hence if the operands themselves
2915 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2916 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2917 unset means assuming isochronic (or instantaneous) tree equivalence.
2918 Unless comparing arbitrary expression trees, such as from different
2919 statements, this flag can usually be left unset.
2921 If OEP_PURE_SAME is set, then pure functions with identical arguments
2922 are considered the same. It is used when the caller has other ways
2923 to ensure that global memory is unchanged in between.
2925 If OEP_ADDRESS_OF is set, we are actually comparing addresses of objects,
2926 not values of expressions.
2928 If OEP_LEXICOGRAPHIC is set, then also handle expressions with side-effects
2929 such as MODIFY_EXPR, RETURN_EXPR, as well as STATEMENT_LISTs.
2931 Unless OEP_MATCH_SIDE_EFFECTS is set, the function returns false on
2932 any operand with side effect. This is unnecesarily conservative in the
2933 case we know that arg0 and arg1 are in disjoint code paths (such as in
2934 ?: operator). In addition OEP_MATCH_SIDE_EFFECTS is used when comparing
2935 addresses with TREE_CONSTANT flag set so we know that &var == &var
2936 even if var is volatile. */
2938 int
2940 {
2941 /* When checking, verify at the outermost operand_equal_p call that
2942 if operand_equal_p returns non-zero then ARG0 and ARG1 has the same
2943 hash value. */
2945 {
2947 {
2949 {
2956 }
2958 }
2959 else
2961 }
2963 /* If either is ERROR_MARK, they aren't equal. */
2969 /* Similar, if either does not have a type (like a released SSA name),
2970 they aren't equal. */
2974 /* We cannot consider pointers to different address space equal. */
2981 /* Check equality of integer constants before bailing out due to
2982 precision differences. */
2984 {
2985 /* Address of INTEGER_CST is not defined; check that we did not forget
2986 to drop the OEP_ADDRESS_OF flags. */
2989 }
2992 {
2993 /* If both types don't have the same signedness, then we can't consider
2994 them equal. We must check this before the STRIP_NOPS calls
2995 because they may change the signedness of the arguments. As pointers
2996 strictly don't have a signedness, require either two pointers or
2997 two non-pointers as well. */
3003 /* If both types don't have the same precision, then it is not safe
3004 to strip NOPs. */
3011 }
3012 #if 0
3013 /* FIXME: Fortran FE currently produce ADDR_EXPR of NOP_EXPR. Enable the
3014 sanity check once the issue is solved. */
3015 else
3016 /* Addresses of conversions and SSA_NAMEs (and many other things)
3017 are not defined. Check that we did not forget to drop the
3018 OEP_ADDRESS_OF/OEP_CONSTANT_ADDRESS_OF flags. */
3021 #endif
3023 /* In case both args are comparisons but with different comparison
3024 code, try to swap the comparison operands of one arg to produce
3025 a match and compare that variant. */
3029 {
3037 }
3040 {
3041 /* NOP_EXPR and CONVERT_EXPR are considered equal. */
3043 ;
3045 {
3046 /* If we are interested in comparing addresses ignore
3047 MEM_REF wrappings of the base that can appear just for
3048 TBAA reasons. */
3062 }
3063 else
3065 }
3067 /* When not checking adddresses, this is needed for conversions and for
3068 COMPONENT_REF. Might as well play it safe and always test this. */
3075 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
3076 We don't care about side effects in that case because the SAVE_EXPR
3077 takes care of that for us. In all other cases, two expressions are
3078 equal if they have no side effects. If we have two identical
3079 expressions with side effects that should be treated the same due
3080 to the only side effects being identical SAVE_EXPR's, that will
3081 be detected in the recursive calls below.
3082 If we are taking an invariant address of two identical objects
3083 they are necessarily equal as well. */
3090 /* Next handle constant cases, those for which we can return 1 even
3091 if ONLY_CONST is set. */
3094 {
3108 {
3109 /* If we do not distinguish between signed and unsigned zero,
3110 consider them equal. */
3113 }
3117 {
3132 }
3136 flags)
3138 flags));
3149 flags | OEP_ADDRESS_OF
3152 /* In GIMPLE empty constructors are allowed in initializers of
3153 aggregates. */
3157 }
3162 /* Define macros to test an operand from arg0 and arg1 for equality and a
3163 variant that allows null and views null as being different from any
3164 non-null value. In the latter case, if either is null, the both
3165 must be; otherwise, do the normal comparison. */
3166 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
3167 TREE_OPERAND (arg1, N), flags)
3169 #define OP_SAME_WITH_NULL(N) \
3170 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
3171 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
3174 {
3176 /* Two conversions are equal only if signedness and modes match. */
3178 {
3179 CASE_CONVERT:
3187 }
3197 /* For commutative ops, allow the other order. */
3205 /* If either of the pointer (or reference) expressions we are
3206 dereferencing contain a side effect, these cannot be equal,
3207 but their addresses can be. */
3214 {
3224 /* Require the same offset. */
3230 /* Fallthru. */
3238 {
3239 /* Require equal access sizes */
3245 flags)))
3247 /* Verify that access happens in similar types. */
3250 /* Verify that accesses are TBAA compatible. */
3259 /* Verify that alignment is compatible. */
3263 }
3266 /* TARGET_MEM_REF require equal extra operands. */
3277 /* Compare the array index by value if it is constant first as we
3278 may have different types but same value here. */
3284 /* Compare low bound and element size as with OEP_ADDRESS_OF
3285 we have to account for the offset of the ref. */
3290 array_ref_low_bound
3294 array_ref_element_size
3296 flags))));
3299 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
3300 may be NULL when we're called to compare MEM_EXPRs. */
3315 }
3319 {
3321 /* Be sure we pass right ADDRESS_OF flag. */
3338 /* The multiplcation operands are commutative. */
3339 /* FALLTHRU */
3347 /* Otherwise take into account this is a commutative operation. */
3360 /* BIT_INSERT_EXPR has an implict operand as the type precision
3361 of op1. Need to check to make sure they are the same. */
3367 /* FALLTHRU */
3393 }
3397 {
3401 /* If not both CALL_EXPRs are either internal or normal function
3402 functions, then they are not equal. */
3405 {
3406 /* If the CALL_EXPRs call different internal functions, then they
3407 are not equal. */
3410 }
3411 else
3412 {
3413 /* If the CALL_EXPRs call different functions, then they are not
3414 equal. */
3416 flags))
3418 }
3420 /* FIXME: We could skip this test for OEP_MATCH_SIDE_EFFECTS. */
3421 {
3425 else
3429 }
3431 /* Now see if all the arguments are the same. */
3432 {
3443 /* If we get here and both argument lists are exhausted
3444 then the CALL_EXPRs are equal. */
3446 }
3449 }
3452 /* Consider __builtin_sqrt equal to sqrt. */
3460 {
3461 /* In GIMPLE constructors are used only to build vectors from
3462 elements. Individual elements in the constructor must be
3463 indexed in increasing order and form an initial sequence.
3465 We make no effort to compare constructors in generic.
3466 (see sem_variable::equals in ipa-icf which can do so for
3467 constants). */
3472 /* Be sure that vectors constructed have the same representation.
3473 We only tested element precision and modes to match.
3474 Vectors may be BLKmode and thus also check that the number of
3475 parts match. */
3488 {
3493 /* In GIMPLE the indexes can be either NULL or matching i.
3494 Double check this so we won't get false
3495 positives for GENERIC. */
3503 }
3505 }
3508 {
3509 /* Compare the STATEMENT_LISTs. */
3515 {
3516 /* The lists don't have the same number of statements. */
3522 flags & (OEP_LEXICOGRAPHIC
3525 }
3526 }
3531 {
3542 }
3546 }
3548 #undef OP_SAME
3549 #undef OP_SAME_WITH_NULL
3550 }
3551 \f
3552 /* Similar to operand_equal_p, but see if ARG0 might be a variant of ARG1
3553 with a different signedness or a narrower precision. */
3555 static bool
3557 {
3565 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3566 and see if the inner values are the same. This removes any
3567 signedness comparison, which doesn't matter here. */
3575 /* Discard a single widening conversion from ARG1 and see if the inner
3576 value is the same as ARG0. */
3585 }
3586 \f
3587 /* See if ARG is an expression that is either a comparison or is performing
3588 arithmetic on comparisons. The comparisons must only be comparing
3589 two different values, which will be stored in *CVAL1 and *CVAL2; if
3590 they are nonzero it means that some operands have already been found.
3591 No variables may be used anywhere else in the expression except in the
3592 comparisons.
3594 If this is true, return 1. Otherwise, return zero. */
3596 static int
3598 {
3602 /* We can handle some of the tcc_expression cases here. */
3611 {
3630 /* First see if we can handle the first operand, then the second. For
3631 the second operand, we know *CVAL1 can't be zero. It must be that
3632 one side of the comparison is each of the values; test for the
3633 case where this isn't true by failing if the two operands
3634 are the same. */
3643 ;
3647 ;
3648 else
3652 ;
3656 ;
3657 else
3664 }
3665 }
3666 \f
3667 /* ARG is a tree that is known to contain just arithmetic operations and
3668 comparisons. Evaluate the operations in the tree substituting NEW0 for
3669 any occurrence of OLD0 as an operand of a comparison and likewise for
3670 NEW1 and OLD1. */
3672 static tree
3675 {
3680 /* We can handle some of the tcc_expression cases here. */
3688 {
3703 {
3722 }
3723 /* Fall through - ??? */
3726 {
3730 /* We need to check both for exact equality and tree equality. The
3731 former will be true if the operand has a side-effect. In that
3732 case, we know the operand occurred exactly once. */
3745 }
3749 }
3750 }
3751 \f
3752 /* Return a tree for the case when the result of an expression is RESULT
3753 converted to TYPE and OMITTED was previously an operand of the expression
3754 but is now not needed (e.g., we folded OMITTED * 0).
3756 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3757 the conversion of RESULT to TYPE. */
3759 tree
3761 {
3764 /* If the resulting operand is an empty statement, just return the omitted
3765 statement casted to void. */
3775 }
3777 /* Return a tree for the case when the result of an expression is RESULT
3778 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3779 of the expression but are now not needed.
3781 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3782 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3783 evaluated before OMITTED2. Otherwise, if neither has side effects,
3784 just do the conversion of RESULT to TYPE. */
3786 tree
3789 {
3798 }
3800 \f
3801 /* Return a simplified tree node for the truth-negation of ARG. This
3802 never alters ARG itself. We assume that ARG is an operation that
3803 returns a truth value (0 or 1).
3805 FIXME: one would think we would fold the result, but it causes
3806 problems with the dominator optimizer. */
3808 static tree
3810 {
3815 /* If this is a comparison, we can simply invert it, except for
3816 floating-point non-equality comparisons, in which case we just
3817 enclose a TRUTH_NOT_EXPR around what we have. */
3820 {
3823 && flag_trapping_math
3837 }
3840 {
3859 /* Here we can invert either operand. We invert the first operand
3860 unless the second operand is a TRUTH_NOT_EXPR in which case our
3861 result is the XOR of the first operand with the inside of the
3862 negation of the second operand. */
3867 else
3890 {
3897 /* A COND_EXPR may have a throw as one operand, which
3898 then has void type. Just leave void operands
3899 as they are. */
3905 }
3917 CASE_CONVERT:
3921 /* fall through */
3943 }
3944 }
3946 /* Fold the truth-negation of ARG. This never alters ARG itself. We
3947 assume that ARG is an operation that returns a truth value (0 or 1
3948 for scalars, 0 or -1 for vectors). Return the folded expression if
3949 folding is successful. Otherwise, return NULL_TREE. */
3951 static tree
3953 {
3956 ? BIT_NOT_EXPR
3959 }
3961 /* Return a simplified tree node for the truth-negation of ARG. This
3962 never alters ARG itself. We assume that ARG is an operation that
3963 returns a truth value (0 or 1 for scalars, 0 or -1 for vectors). */
3965 tree
3967 {
3973 ? BIT_NOT_EXPR
3976 }
3977 \f
3978 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3979 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero
3980 and uses reverse storage order if REVERSEP is nonzero. ORIG_INNER
3981 is the original memory reference used to preserve the alias set of
3982 the access. */
3984 static tree
3988 {
3991 /* Attempt not to lose the access path if possible. */
3993 {
3995 machine_mode nmode;
3997 tree noffset;
4005 && !reversep
4006 && !nreversep
4008 {
4011 }
4012 }
4021 {
4028 }
4043 }
4045 /* Optimize a bit-field compare.
4047 There are two cases: First is a compare against a constant and the
4048 second is a comparison of two items where the fields are at the same
4049 bit position relative to the start of a chunk (byte, halfword, word)
4050 large enough to contain it. In these cases we can avoid the shift
4051 implicit in bitfield extractions.
4053 For constants, we emit a compare of the shifted constant with the
4054 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
4055 compared. For two fields at the same position, we do the ANDs with the
4056 similar mask and compare the result of the ANDs.
4058 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
4059 COMPARE_TYPE is the type of the comparison, and LHS and RHS
4060 are the left and right operands of the comparison, respectively.
4062 If the optimization described above can be done, we return the resulting
4063 tree. Otherwise we return zero. */
4065 static tree
4068 {
4072 tree unsigned_type;
4075 scalar_int_mode nmode;
4080 tree mask;
4081 tree offset;
4083 /* Get all the information about the extractions being done. If the bit size
4084 is the same as the size of the underlying object, we aren't doing an
4085 extraction at all and so can do nothing. We also don't want to
4086 do anything if the inner expression is a PLACEHOLDER_EXPR since we
4087 then will no longer be able to replace it. */
4102 else
4103 {
4104 /* If this is not a constant, we can only do something if bit positions,
4105 sizes, signedness and storage order are the same. */
4106 rinner
4119 }
4121 /* Honor the C++ memory model and mimic what RTL expansion does. */
4125 {
4129 }
4131 /* See if we can find a mode to refer to this field. We should be able to,
4132 but fail if we can't. */
4140 /* Set signed and unsigned types of the precision of this mode for the
4141 shifts below. */
4144 /* Compute the bit position and size for the new reference and our offset
4145 within it. If the new reference is the same size as the original, we
4146 won't optimize anything, so return zero. */
4156 /* Make the mask to be used against the extracted field. */
4163 {
4167 /* If not comparing with constant, just rework the comparison
4168 and return. */
4176 }
4178 /* Otherwise, we are handling the constant case. See if the constant is too
4179 big for the field. Warn and return a tree for 0 (false) if so. We do
4180 this not only for its own sake, but to avoid having to test for this
4181 error case below. If we didn't, we might generate wrong code.
4183 For unsigned fields, the constant shifted right by the field length should
4184 be all zero. For signed fields, the high-order bits should agree with
4185 the sign bit. */
4188 {
4190 {
4194 }
4195 }
4196 else
4197 {
4200 {
4204 }
4205 }
4210 /* Single-bit compares should always be against zero. */
4212 {
4215 }
4217 /* Make a new bitfield reference, shift the constant over the
4218 appropriate number of bits and mask it with the computed mask
4219 (in case this was a signed field). If we changed it, make a new one. */
4227 mask);
4232 }
4233 \f
4234 /* Subroutine for fold_truth_andor_1: decode a field reference.
4236 If EXP is a comparison reference, we return the innermost reference.
4238 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
4239 set to the starting bit number.
4241 If the innermost field can be completely contained in a mode-sized
4242 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
4244 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
4245 otherwise it is not changed.
4247 *PUNSIGNEDP is set to the signedness of the field.
4249 *PREVERSEP is set to the storage order of the field.
4251 *PMASK is set to the mask used. This is either contained in a
4252 BIT_AND_EXPR or derived from the width of the field.
4254 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
4256 Return 0 if this is not a component reference or is one that we can't
4257 do anything with. */
4259 static tree
4264 {
4269 tree unsigned_type;
4272 /* All the optimizations using this function assume integer fields.
4273 There are problems with FP fields since the type_for_size call
4274 below can fail for, e.g., XFmode. */
4278 /* We are interested in the bare arrangement of bits, so strip everything
4279 that doesn't affect the machine mode. However, record the type of the
4280 outermost expression if it may matter below. */
4287 {
4293 }
4304 /* Reject out-of-bound accesses (PR79731). */
4312 /* If the number of bits in the reference is the same as the bitsize of
4313 the outer type, then the outer type gives the signedness. Otherwise
4314 (in case of a small bitfield) the signedness is unchanged. */
4318 /* Compute the mask to access the bitfield. */
4327 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
4335 }
4337 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
4338 bit positions and MASK is SIGNED. */
4340 static int
4342 {
4346 /* If this function returns true when the type of the mask is
4347 UNSIGNED, then there will be errors. In particular see
4348 gcc.c-torture/execute/990326-1.c. There does not appear to be
4349 any documentation paper trail as to why this is so. But the pre
4350 wide-int worked with that restriction and it has been preserved
4351 here. */
4356 }
4358 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
4359 represents the sign bit of EXP's type. If EXP represents a sign
4360 or zero extension, also test VAL against the unextended type.
4361 The return value is the (sub)expression whose sign bit is VAL,
4362 or NULL_TREE otherwise. */
4364 tree
4366 {
4368 tree t;
4370 /* Tree EXP must have an integral type. */
4375 /* Tree VAL must be an integer constant. */
4384 /* Handle extension from a narrower type. */
4390 }
4392 /* Subroutine for fold_truth_andor_1: determine if an operand is simple enough
4393 to be evaluated unconditionally. */
4395 static int
4397 {
4398 /* Strip any conversions that don't change the machine mode. */
4407 /* Don't regard global variables as simple. They may be
4408 allocated in ways unknown to the compiler (shared memory,
4409 #pragma weak, etc). */
4412 /* Weakrefs are not safe to be read, since they can be NULL.
4413 They are !TREE_PUBLIC && !DECL_EXTERNAL but still
4414 have DECL_WEAK flag set. */
4416 /* Loading a static variable is unduly expensive, but global
4417 registers aren't expensive. */
4419 }
4421 /* Subroutine for fold_truth_andor: determine if an operand is simple enough
4422 to be evaluated unconditionally.
4423 I addition to simple_operand_p, we assume that comparisons, conversions,
4424 and logic-not operations are simple, if their operands are simple, too. */
4426 static bool
4428 {
4448 }
4450 \f
4451 /* The following functions are subroutines to fold_range_test and allow it to
4452 try to change a logical combination of comparisons into a range test.
4454 For example, both
4455 X == 2 || X == 3 || X == 4 || X == 5
4456 and
4457 X >= 2 && X <= 5
4458 are converted to
4459 (unsigned) (X - 2) <= 3
4461 We describe each set of comparisons as being either inside or outside
4462 a range, using a variable named like IN_P, and then describe the
4463 range with a lower and upper bound. If one of the bounds is omitted,
4464 it represents either the highest or lowest value of the type.
4466 In the comments below, we represent a range by two numbers in brackets
4467 preceded by a "+" to designate being inside that range, or a "-" to
4468 designate being outside that range, so the condition can be inverted by
4469 flipping the prefix. An omitted bound is represented by a "-". For
4470 example, "- [-, 10]" means being outside the range starting at the lowest
4471 possible value and ending at 10, in other words, being greater than 10.
4472 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
4473 always false.
4475 We set up things so that the missing bounds are handled in a consistent
4476 manner so neither a missing bound nor "true" and "false" need to be
4477 handled using a special case. */
4479 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
4480 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
4481 and UPPER1_P are nonzero if the respective argument is an upper bound
4482 and zero for a lower. TYPE, if nonzero, is the type of the result; it
4483 must be specified for a comparison. ARG1 will be converted to ARG0's
4484 type if both are specified. */
4486 static tree
4489 {
4490 tree tem;
4494 /* If neither arg represents infinity, do the normal operation.
4495 Else, if not a comparison, return infinity. Else handle the special
4496 comparison rules. Note that most of the cases below won't occur, but
4497 are handled for consistency. */
4500 {
4505 }
4510 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
4511 for neither. In real maths, we cannot assume open ended ranges are
4512 the same. But, this is computer arithmetic, where numbers are finite.
4513 We can therefore make the transformation of any unbounded range with
4514 the value Z, Z being greater than any representable number. This permits
4515 us to treat unbounded ranges as equal. */
4519 {
4540 }
4543 }
4544 \f
4545 /* Helper routine for make_range. Perform one step for it, return
4546 new expression if the loop should continue or NULL_TREE if it should
4547 stop. */
4549 tree
4553 {
4559 {
4561 /* We can only do something if the range is testing for zero. */
4570 /* We can only do something if the range is testing for zero
4571 and if the second operand is an integer constant. Note that
4572 saying something is "in" the range we make is done by
4573 complementing IN_P since it will set in the initial case of
4574 being not equal to zero; "out" is leaving it alone. */
4581 {
4602 }
4604 /* If this is an unsigned comparison, we also know that EXP is
4605 greater than or equal to zero. We base the range tests we make
4606 on that fact, so we record it here so we can parse existing
4607 range tests. We test arg0_type since often the return type
4608 of, e.g. EQ_EXPR, is boolean. */
4610 {
4614 NULL_TREE))
4619 /* If the high bound is missing, but we have a nonzero low
4620 bound, reverse the range so it goes from zero to the low bound
4621 minus 1. */
4623 {
4628 }
4629 }
4637 /* If flag_wrapv and ARG0_TYPE is signed, make sure
4638 low and high are non-NULL, then normalize will DTRT. */
4641 {
4646 }
4648 /* (-x) IN [a,b] -> x in [-b, -a] */
4660 /* ~ X -> -X - 1 */
4669 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4670 move a constant to the other side. */
4675 /* If EXP is signed, any overflow in the computation is undefined,
4676 so we don't worry about it so long as our computations on
4677 the bounds don't overflow. For unsigned, overflow is defined
4678 and this is exactly the right thing. */
4690 normalize:
4691 /* Check for an unsigned range which has wrapped around the maximum
4692 value thus making n_high < n_low, and normalize it. */
4694 {
4700 /* If the range is of the form +/- [ x+1, x ], we won't
4701 be able to normalize it. But then, it represents the
4702 whole range or the empty set, so make it
4703 +/- [ -, - ]. */
4707 else
4709 }
4710 else
4718 CASE_CONVERT:
4736 /* If we're converting arg0 from an unsigned type, to exp,
4737 a signed type, we will be doing the comparison as unsigned.
4738 The tests above have already verified that LOW and HIGH
4739 are both positive.
4741 So we have to ensure that we will handle large unsigned
4742 values the same way that the current signed bounds treat
4743 negative values. */
4746 {
4747 tree high_positive;
4748 tree equiv_type;
4749 /* For fixed-point modes, we need to pass the saturating flag
4750 as the 2nd parameter. */
4752 equiv_type
4755 else
4756 equiv_type
4759 /* A range without an upper bound is, naturally, unbounded.
4760 Since convert would have cropped a very large value, use
4761 the max value for the destination type. */
4762 high_positive
4769 high_positive),
4772 /* If the low bound is specified, "and" the range with the
4773 range for which the original unsigned value will be
4774 positive. */
4776 {
4779 integer_zero_node),
4780 high_positive))
4784 }
4785 else
4786 {
4787 /* Otherwise, "or" the range with the range of the input
4788 that will be interpreted as negative. */
4791 integer_zero_node),
4792 high_positive))
4796 }
4797 }
4806 }
4807 }
4809 /* Given EXP, a logical expression, set the range it is testing into
4810 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4811 actually being tested. *PLOW and *PHIGH will be made of the same
4812 type as the returned expression. If EXP is not a comparison, we
4813 will most likely not be returning a useful value and range. Set
4814 *STRICT_OVERFLOW_P to true if the return value is only valid
4815 because signed overflow is undefined; otherwise, do not change
4816 *STRICT_OVERFLOW_P. */
4818 tree
4821 {
4829 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4830 and see if we can refine the range. Some of the cases below may not
4831 happen, but it doesn't seem worth worrying about this. We "continue"
4832 the outer loop when we've changed something; otherwise we "break"
4833 the switch, which will "break" the while. */
4839 {
4845 {
4853 }
4862 }
4864 /* If EXP is a constant, we can evaluate whether this is true or false. */
4866 {
4873 }
4877 }
4879 /* Returns TRUE if [LOW, HIGH] range check can be optimized to
4880 a bitwise check i.e. when
4881 LOW == 0xXX...X00...0
4882 HIGH == 0xXX...X11...1
4883 Return corresponding mask in MASK and stem in VALUE. */
4885 static bool
4888 {
4911 }
4912 \f
4913 /* Helper routine for build_range_check and match.pd. Return the type to
4914 perform the check or NULL if it shouldn't be optimized. */
4916 tree
4918 {
4919 /* First make sure that arithmetics in this type is valid, then make sure
4920 that it wraps around. */
4926 {
4929 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4930 for the type in question, as we rely on this here. */
4940 else
4942 }
4944 }
4946 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4947 type, TYPE, return an expression to test if EXP is in (or out of, depending
4948 on IN_P) the range. Return 0 if the test couldn't be created. */
4950 tree
4953 {
4956 /* Disable this optimization for function pointer expressions
4957 on targets that require function pointer canonicalization. */
4964 {
4970 }
4992 value);
4995 {
4997 {
5001 }
5003 }
5005 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
5007 {
5011 {
5013 {
5016 etype
5018 else
5021 }
5024 }
5025 }
5027 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
5028 This requires wrap-around arithmetics for the type of the expression. */
5048 }
5049 \f
5050 /* Return the predecessor of VAL in its type, handling the infinite case. */
5052 static tree
5054 {
5060 else
5063 }
5065 /* Return the successor of VAL in its type, handling the infinite case. */
5067 static tree
5069 {
5075 else
5078 }
5080 /* Given two ranges, see if we can merge them into one. Return 1 if we
5081 can, 0 if we can't. Set the output range into the specified parameters. */
5083 bool
5086 {
5090 tree tem;
5100 /* Make range 0 be the range that starts first, or ends last if they
5101 start at the same value. Swap them if it isn't. */
5104 || (lowequal
5107 {
5111 }
5113 /* If the second range is != high1 where high1 is the type maximum of
5114 the type, try first merging with < high1 range. */
5116 && high1
5123 {
5128 /* Similarly for the second range != low1 where low1 is the type minimum
5129 of the type, try first merging with > low1 range. */
5134 }
5136 /* Now flag two cases, whether the ranges are disjoint or whether the
5137 second range is totally subsumed in the first. Note that the tests
5138 below are simplified by the ones above. */
5144 /* We now have four cases, depending on whether we are including or
5145 excluding the two ranges. */
5147 {
5148 /* If they don't overlap, the result is false. If the second range
5149 is a subset it is the result. Otherwise, the range is from the start
5150 of the second to the end of the first. */
5155 else
5157 }
5160 {
5161 /* If they don't overlap, the result is the first range. If they are
5162 equal, the result is false. If the second range is a subset of the
5163 first, and the ranges begin at the same place, we go from just after
5164 the end of the second range to the end of the first. If the second
5165 range is not a subset of the first, or if it is a subset and both
5166 ranges end at the same place, the range starts at the start of the
5167 first range and ends just before the second range.
5168 Otherwise, we can't describe this as a single range. */
5174 {
5179 {
5180 /* We are in the weird situation where high0 > high1 but
5181 high1 has no successor. Punt. */
5183 }
5184 }
5186 {
5191 {
5192 /* low0 < low1 but low1 has no predecessor. Punt. */
5194 }
5195 }
5196 else
5198 }
5201 {
5202 /* If they don't overlap, the result is the second range. If the second
5203 is a subset of the first, the result is false. Otherwise,
5204 the range starts just after the first range and ends at the
5205 end of the second. */
5210 else
5211 {
5216 {
5217 /* high1 > high0 but high0 has no successor. Punt. */
5219 }
5220 }
5221 }
5223 else
5224 {
5225 /* The case where we are excluding both ranges. Here the complex case
5226 is if they don't overlap. In that case, the only time we have a
5227 range is if they are adjacent. If the second is a subset of the
5228 first, the result is the first. Otherwise, the range to exclude
5229 starts at the beginning of the first range and ends at the end of the
5230 second. */
5232 {
5237 else
5238 {
5239 /* Canonicalize - [min, x] into - [-, x]. */
5242 {
5245 GET_MODE_BITSIZE
5248 /* FALLTHROUGH */
5261 }
5263 /* Canonicalize - [x, max] into - [x, -]. */
5266 {
5269 GET_MODE_BITSIZE
5272 /* FALLTHROUGH */
5288 }
5290 /* The ranges might be also adjacent between the maximum and
5291 minimum values of the given type. For
5292 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
5293 return + [x + 1, y - 1]. */
5295 {
5302 }
5303 else
5305 }
5306 }
5309 else
5311 }
5315 }
5316 \f
5318 /* Subroutine of fold, looking inside expressions of the form
5319 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
5320 of the COND_EXPR. This function is being used also to optimize
5321 A op B ? C : A, by reversing the comparison first.
5323 Return a folded expression whose code is not a COND_EXPR
5324 anymore, or NULL_TREE if no folding opportunity is found. */
5326 static tree
5329 {
5334 tree tem;
5339 /* If we have A op 0 ? A : -A, consider applying the following
5340 transformations:
5342 A == 0? A : -A same as -A
5343 A != 0? A : -A same as A
5344 A >= 0? A : -A same as abs (A)
5345 A > 0? A : -A same as abs (A)
5346 A <= 0? A : -A same as -abs (A)
5347 A < 0? A : -A same as -abs (A)
5349 None of these transformations work for modes with signed
5350 zeros. If A is +/-0, the first two transformations will
5351 change the sign of the result (from +0 to -0, or vice
5352 versa). The last four will fix the sign of the result,
5353 even though the original expressions could be positive or
5354 negative, depending on the sign of A.
5356 Note that all these transformations are correct if A is
5357 NaN, since the two alternatives (A and -A) are also NaNs. */
5364 /* In the case that A is of the form X-Y, '-A' (arg2) may
5365 have already been folded to Y-X, check for that. */
5373 {
5385 /* Fall through. */
5396 /* FALLTHRU */
5406 }
5408 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
5409 A == 0 ? A : 0 is always 0 unless A is -0. Note that
5410 both transformations are correct when A is NaN: A != 0
5411 is then true, and A == 0 is false. */
5415 {
5420 }
5422 /* Try some transformations of A op B ? A : B.
5424 A == B? A : B same as B
5425 A != B? A : B same as A
5426 A >= B? A : B same as max (A, B)
5427 A > B? A : B same as max (B, A)
5428 A <= B? A : B same as min (A, B)
5429 A < B? A : B same as min (B, A)
5431 As above, these transformations don't work in the presence
5432 of signed zeros. For example, if A and B are zeros of
5433 opposite sign, the first two transformations will change
5434 the sign of the result. In the last four, the original
5435 expressions give different results for (A=+0, B=-0) and
5436 (A=-0, B=+0), but the transformed expressions do not.
5438 The first two transformations are correct if either A or B
5439 is a NaN. In the first transformation, the condition will
5440 be false, and B will indeed be chosen. In the case of the
5441 second transformation, the condition A != B will be true,
5442 and A will be chosen.
5444 The conversions to max() and min() are not correct if B is
5445 a number and A is not. The conditions in the original
5446 expressions will be false, so all four give B. The min()
5447 and max() versions would give a NaN instead. */
5450 /* Avoid these transformations if the COND_EXPR may be used
5451 as an lvalue in the C++ front-end. PR c++/19199. */
5452 && (in_gimple_form
5458 {
5464 {
5473 /* In C++ a ?: expression can be an lvalue, so put the
5474 operand which will be used if they are equal first
5475 so that we can convert this back to the
5476 corresponding COND_EXPR. */
5478 {
5486 }
5493 {
5501 }
5514 }
5515 }
5518 }
5521 \f
5522 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
5523 #define LOGICAL_OP_NON_SHORT_CIRCUIT \
5524 (BRANCH_COST (optimize_function_for_speed_p (cfun), \
5525 false) >= 2)
5526 #endif
5528 /* EXP is some logical combination of boolean tests. See if we can
5529 merge it into some range test. Return the new tree if so. */
5531 static tree
5534 {
5550 /* If this is an OR operation, invert both sides; we will invert
5551 again at the end. */
5555 /* If both expressions are the same, if we can merge the ranges, and we
5556 can build the range test, return it or it inverted. If one of the
5557 ranges is always true or always false, consider it to be the same
5558 expression as the other. */
5566 {
5570 }
5572 /* On machines where the branch cost is expensive, if this is a
5573 short-circuited branch and the underlying object on both sides
5574 is the same, make a non-short-circuit operation. */
5576 && !flag_sanitize_coverage
5581 {
5582 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5583 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5584 which cases we can't do this. */
5592 {
5601 {
5604 WARN_STRICT_OVERFLOW_COMPARISON);
5608 }
5609 }
5610 }
5613 }
5614 \f
5615 /* Subroutine for fold_truth_andor_1: C is an INTEGER_CST interpreted as a P
5616 bit value. Arrange things so the extra bits will be set to zero if and
5617 only if C is signed-extended to its full width. If MASK is nonzero,
5618 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5620 static tree
5622 {
5625 tree temp;
5630 /* We work by getting just the sign bit into the low-order bit, then
5631 into the high-order bit, then sign-extend. We then XOR that value
5632 with C. */
5636 /* We must use a signed type in order to get an arithmetic right shift.
5637 However, we must also avoid introducing accidental overflows, so that
5638 a subsequent call to integer_zerop will work. Hence we must
5639 do the type conversion here. At this point, the constant is either
5640 zero or one, and the conversion to a signed type can never overflow.
5641 We could get an overflow if this conversion is done anywhere else. */
5650 /* If necessary, convert the type back to match the type of C. */
5655 }
5656 \f
5657 /* For an expression that has the form
5658 (A && B) || ~B
5659 or
5660 (A || B) && ~B,
5661 we can drop one of the inner expressions and simplify to
5662 A || ~B
5663 or
5664 A && ~B
5665 LOC is the location of the resulting expression. OP is the inner
5666 logical operation; the left-hand side in the examples above, while CMPOP
5667 is the right-hand side. RHS_ONLY is used to prevent us from accidentally
5668 removing a condition that guards another, as in
5669 (A != NULL && A->...) || A == NULL
5670 which we must not transform. If RHS_ONLY is true, only eliminate the
5671 right-most operand of the inner logical operation. */
5673 static tree
5676 {
5694 {
5697 {
5700 }
5701 }
5703 {
5706 {
5709 }
5710 }
5725 }
5727 /* Find ways of folding logical expressions of LHS and RHS:
5728 Try to merge two comparisons to the same innermost item.
5729 Look for range tests like "ch >= '0' && ch <= '9'".
5730 Look for combinations of simple terms on machines with expensive branches
5731 and evaluate the RHS unconditionally.
5733 For example, if we have p->a == 2 && p->b == 4 and we can make an
5734 object large enough to span both A and B, we can do this with a comparison
5735 against the object ANDed with the a mask.
5737 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5738 operations to do this with one comparison.
5740 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5741 function and the one above.
5743 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5744 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5746 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5747 two operands.
5749 We return the simplified tree or 0 if no optimization is possible. */
5751 static tree
5754 {
5755 /* If this is the "or" of two comparisons, we can do something if
5756 the comparisons are NE_EXPR. If this is the "and", we can do something
5757 if the comparisons are EQ_EXPR. I.e.,
5758 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5760 WANTED_CODE is this operation code. For single bit fields, we can
5761 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5762 comparison for one-bit fields. */
5783 /* Start by getting the comparison codes. Fail if anything is volatile.
5784 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5785 it were surrounded with a NE_EXPR. */
5794 {
5798 }
5801 {
5805 }
5816 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5819 {
5822 {
5827 }
5830 {
5836 }
5837 }
5842 /* If the RHS can be evaluated unconditionally and its operands are
5843 simple, it wins to evaluate the RHS unconditionally on machines
5844 with expensive branches. In this case, this isn't a comparison
5845 that can be merged. */
5852 {
5853 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5864 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5874 }
5876 /* See if the comparisons can be merged. Then get all the parameters for
5877 each side. */
5902 /* It must be true that the inner operation on the lhs of each
5903 comparison must be the same if we are to be able to do anything.
5904 Then see if we have constants. If not, the same must be true for
5905 the rhs's. */
5914 {
5917 }
5922 else
5925 /* If either comparison code is not correct for our logical operation,
5926 fail. However, we can convert a one-bit comparison against zero into
5927 the opposite comparison against that bit being set in the field. */
5931 {
5933 {
5934 /* Make the left operand unsigned, since we are only interested
5935 in the value of one bit. Otherwise we are doing the wrong
5936 thing below. */
5939 }
5940 else
5942 }
5944 /* This is analogous to the code for l_const above. */
5946 {
5948 {
5951 }
5952 else
5954 }
5956 /* See if we can find a mode that contains both fields being compared on
5957 the left. If we can't, fail. Otherwise, update all constants and masks
5958 to be relative to a field of that size. */
5972 {
5975 }
5983 {
5990 {
5994 }
5995 }
5997 {
6004 {
6008 }
6009 }
6011 /* If the right sides are not constant, do the same for it. Also,
6012 disallow this optimization if a size, signedness or storage order
6013 mismatch occurs between the left and right sides. */
6015 {
6019 /* Make sure the two fields on the right
6020 correspond to the left without being swapped. */
6037 {
6040 }
6049 /* Make a mask that corresponds to both fields being compared.
6050 Do this for both items being compared. If the operands are the
6051 same size and the bits being compared are in the same position
6052 then we can do this by masking both and comparing the masked
6053 results. */
6060 {
6074 }
6076 /* There is still another way we can do something: If both pairs of
6077 fields being compared are adjacent, we may be able to make a wider
6078 field containing them both.
6080 Note that we still must mask the lhs/rhs expressions. Furthermore,
6081 the mask must be shifted to account for the shift done by
6082 make_bit_field_ref. */
6091 {
6092 tree type;
6108 /* Convert to the smaller type before masking out unwanted bits. */
6111 {
6113 {
6117 }
6119 {
6123 }
6124 }
6133 }
6136 }
6138 /* Handle the case of comparisons with constants. If there is something in
6139 common between the masks, those bits of the constants must be the same.
6140 If not, the condition is always false. Test for this to avoid generating
6141 incorrect code below. */
6146 {
6148 {
6151 }
6152 else
6153 {
6156 }
6157 }
6162 /* Construct the expression we will return. First get the component
6163 reference we will make. Unless the mask is all ones the width of
6164 that field, perform the mask operation. Then compare with the
6165 merged constant. */
6176 }
6177 \f
6178 /* T is an integer expression that is being multiplied, divided, or taken a
6179 modulus (CODE says which and what kind of divide or modulus) by a
6180 constant C. See if we can eliminate that operation by folding it with
6181 other operations already in T. WIDE_TYPE, if non-null, is a type that
6182 should be used for the computation if wider than our type.
6184 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6185 (X * 2) + (Y * 4). We must, however, be assured that either the original
6186 expression would not overflow or that overflow is undefined for the type
6187 in the language in question.
6189 If we return a non-null expression, it is an equivalent form of the
6190 original computation, but need not be in the original type.
6192 We set *STRICT_OVERFLOW_P to true if the return values depends on
6193 signed overflow being undefined. Otherwise we do not change
6194 *STRICT_OVERFLOW_P. */
6196 static tree
6199 {
6200 /* To avoid exponential search depth, refuse to allow recursion past
6201 three levels. Beyond that (1) it's highly unlikely that we'll find
6202 something interesting and (2) we've probably processed it before
6203 when we built the inner expression. */
6206 tree ret;
6211 depth++;
6213 depth--;
6216 }
6218 static tree
6221 {
6233 /* Don't deal with constants of zero here; they confuse the code below. */
6243 /* Note that we need not handle conditional operations here since fold
6244 already handles those cases. So just do arithmetic here. */
6246 {
6248 /* For a constant, we can always simplify if we are a multiply
6249 or (for divide and modulus) if it is a multiple of our constant. */
6253 {
6256 /* If the multiplication overflowed, we lost information on it.
6257 See PR68142 and PR69845. */
6261 }
6265 /* If op0 is an expression ... */
6271 /* ... and has wrapping overflow, and its type is smaller
6272 than ctype, then we cannot pass through as widening. */
6277 /* ... or this is a truncation (t is narrower than op0),
6278 then we cannot pass through this narrowing. */
6281 /* ... or signedness changes for division or modulus,
6282 then we cannot pass through this conversion. */
6286 /* ... or has undefined overflow while the converted to
6287 type has not, we cannot do the operation in the inner type
6288 as that would introduce undefined overflow. */
6294 /* Pass the constant down and see if we can make a simplification. If
6295 we can, replace this expression with the inner simplification for
6296 possible later conversion to our or some other type. */
6307 /* If widening the type changes it from signed to unsigned, then we
6308 must avoid building ABS_EXPR itself as unsigned. */
6310 {
6314 {
6317 }
6319 }
6320 /* If the constant is negative, we cannot simplify this. */
6323 /* FALLTHROUGH */
6325 /* For division and modulus, type can't be unsigned, as e.g.
6326 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6327 For signed types, even with wrapping overflow, this is fine. */
6336 /* If widening the type changes the signedness, then we can't perform
6337 this optimization as that changes the result. */
6341 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6347 {
6354 }
6358 /* If the second operand is constant, this is a multiplication
6359 or floor division, by a power of two, so we can treat it that
6360 way unless the multiplier or divisor overflows. Signed
6361 left-shift overflow is implementation-defined rather than
6362 undefined in C90, so do not convert signed left shift into
6363 multiplication. */
6366 /* const_binop may not detect overflow correctly,
6367 so check for it explicitly here. */
6376 ctype,
6378 t1),
6383 /* See if we can eliminate the operation on both sides. If we can, we
6384 can return a new PLUS or MINUS. If we can't, the only remaining
6385 cases where we can do anything are if the second operand is a
6386 constant. */
6393 /* If not multiplication, we can only do this if both operands
6394 are divisible by c. */
6397 {
6402 }
6404 /* If this was a subtraction, negate OP1 and set it to be an addition.
6405 This simplifies the logic below. */
6407 {
6409 /* If OP1 was not easily negatable, the constant may be OP0. */
6411 {
6414 }
6415 }
6420 /* If either OP1 or C are negative, this optimization is not safe for
6421 some of the division and remainder types while for others we need
6422 to change the code. */
6424 {
6432 }
6434 /* If it's a multiply or a division/modulus operation of a multiple
6435 of our constant, do the operation and verify it doesn't overflow. */
6439 {
6442 /* We allow the constant to overflow with wrapping semantics. */
6446 }
6447 else
6450 /* If we have an unsigned type, we cannot widen the operation since it
6451 will change the result if the original computation overflowed. */
6455 /* The last case is if we are a multiply. In that case, we can
6456 apply the distributive law to commute the multiply and addition
6457 if the multiplication of the constants doesn't overflow
6458 and overflow is defined. With undefined overflow
6459 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6465 op1);
6470 /* We have a special case here if we are doing something like
6471 (C * 8) % 4 since we know that's zero. */
6474 /* If the multiplication can overflow we cannot optimize this. */
6479 {
6482 }
6484 /* ... fall through ... */
6488 /* If we can extract our operation from the LHS, do so and return a
6489 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6490 do something only if the second operand is a constant. */
6506 /* If these are the same operation types, we can associate them
6507 assuming no overflow. */
6509 {
6524 }
6526 /* If these operations "cancel" each other, we have the main
6527 optimizations of this pass, which occur when either constant is a
6528 multiple of the other, in which case we replace this with either an
6529 operation or CODE or TCODE.
6531 If we have an unsigned type, we cannot do this since it will change
6532 the result if the original computation overflowed. */
6539 {
6542 {
6549 }
6552 {
6559 }
6560 }
6565 }
6568 }
6569 \f
6570 /* Return a node which has the indicated constant VALUE (either 0 or
6571 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6572 and is of the indicated TYPE. */
6574 tree
6576 {
6585 else
6587 }
6590 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6591 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6592 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6593 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6594 COND is the first argument to CODE; otherwise (as in the example
6595 given here), it is the second argument. TYPE is the type of the
6596 original expression. Return NULL_TREE if no simplification is
6597 possible. */
6599 static tree
6604 {
6612 /* Do not move possibly trapping operations into the conditional as this
6613 pessimizes code and causes gimplification issues when applied late. */
6621 {
6625 /* If this operand throws an expression, then it does not make
6626 sense to try to perform a logical or arithmetic operation
6627 involving it. */
6632 }
6635 {
6640 }
6641 else
6642 /* Detect the case of mixing vector and scalar types - bail out. */
6648 /* This transformation is only worthwhile if we don't have to wrap ARG
6649 in a SAVE_EXPR and the operation can be simplified without recursing
6650 on at least one of the branches once its pushed inside the COND_EXPR. */
6659 {
6663 else
6665 }
6667 {
6671 else
6673 }
6675 /* Check that we have simplified at least one of the branches. */
6680 }
6682 \f
6683 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6685 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6686 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6687 ADDEND is the same as X.
6689 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6690 and finite. The problematic cases are when X is zero, and its mode
6691 has signed zeros. In the case of rounding towards -infinity,
6692 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6693 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6695 bool
6697 {
6701 /* Don't allow the fold with -fsignaling-nans. */
6705 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6709 /* In a vector or complex, we would need to check the sign of all zeros. */
6713 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6717 /* The mode has signed zeros, and we have to honor their sign.
6718 In this situation, there is only one case we can return true for.
6719 X - 0 is the same as X unless rounding towards -infinity is
6720 supported. */
6722 }
6724 /* Subroutine of match.pd that optimizes comparisons of a division by
6725 a nonzero integer constant against an integer constant, i.e.
6726 X/C1 op C2.
6728 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6729 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6731 enum tree_code
6734 {
6739 /* We have to do this the hard way to detect unsigned overflow.
6740 prod = int_const_binop (MULT_EXPR, c1, c2); */
6746 {
6750 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6753 }
6755 {
6758 {
6777 }
6778 }
6779 else
6780 {
6781 /* A negative divisor reverses the relational operators. */
6786 {
6805 }
6806 }
6819 }
6822 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6823 equality/inequality test, then return a simplified form of the test
6824 using a sign testing. Otherwise return NULL. TYPE is the desired
6825 result type. */
6827 static tree
6830 tree result_type)
6831 {
6832 /* If this is testing a single bit, we can optimize the test. */
6836 {
6837 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6838 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6842 /* This is only a win if casting to a signed type is cheap,
6843 i.e. when arg00's type is not a partial mode. */
6845 {
6848 result_type,
6851 }
6852 }
6855 }
6857 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6858 equality/inequality test, then return a simplified form of
6859 the test using shifts and logical operations. Otherwise return
6860 NULL. TYPE is the desired result type. */
6862 tree
6865 {
6866 /* If this is testing a single bit, we can optimize the test. */
6870 {
6879 /* First, see if we can fold the single bit test into a sign-bit
6880 test. */
6882 result_type);
6886 /* Otherwise we have (A & C) != 0 where C is a single bit,
6887 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6888 Similarly for (A & C) == 0. */
6890 /* If INNER is a right shift of a constant and it plus BITNUM does
6891 not overflow, adjust BITNUM and INNER. */
6897 {
6900 }
6902 /* If we are going to be able to omit the AND below, we must do our
6903 operations as unsigned. If we must use the AND, we have a choice.
6904 Normally unsigned is faster, but for some machines signed is. */
6922 /* Put the AND last so it can combine with more things. */
6925 /* Make sure to return the proper type. */
6929 }
6931 }
6933 /* Test whether it is preferable two swap two operands, ARG0 and
6934 ARG1, for example because ARG0 is an integer constant and ARG1
6935 isn't. */
6937 bool
6939 {
6953 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6954 for commutative and comparison operators. Ensuring a canonical
6955 form allows the optimizers to find additional redundancies without
6956 having to explicitly check for both orderings. */
6962 /* Put SSA_NAMEs last. */
6968 /* Put variables last. */
6975 }
6978 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6979 means A >= Y && A != MAX, but in this case we know that
6980 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6982 static tree
6984 {
6991 else
7000 {
7003 }
7005 {
7008 }
7009 else
7016 {
7017 /* Convert the pointer types into integer before taking the difference. */
7021 }
7022 else
7029 }
7031 /* Fold a sum or difference of at least one multiplication.
7032 Returns the folded tree or NULL if no simplification could be made. */
7034 static tree
7037 {
7041 /* (A * C) +- (B * C) -> (A+-B) * C.
7042 (A * C) +- A -> A * (C+-1).
7043 We are most concerned about the case where C is a constant,
7044 but other combinations show up during loop reduction. Since
7045 it is not difficult, try all four possibilities. */
7048 {
7051 }
7053 {
7056 }
7057 else
7058 {
7059 /* We cannot generate constant 1 for fract. */
7064 }
7066 {
7069 }
7071 {
7073 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7074 the purpose of this canonicalization. */
7078 {
7081 }
7082 else
7084 }
7085 else
7086 {
7087 /* We cannot generate constant 1 for fract. */
7092 }
7095 /* Prefer factoring a common non-constant. */
7105 /* No identical multiplicands; see if we can find a common
7106 power-of-two factor in non-power-of-two multiplies. This
7107 can help in multi-dimensional array access. */
7110 {
7113 tree maybe_same;
7117 /* Move min of absolute values to int11. */
7119 {
7124 }
7125 else
7129 /* The remainder should not be a constant, otherwise we
7130 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7131 increased the number of multiplications necessary. */
7133 {
7141 }
7142 }
7149 /* We are neither factoring zero nor minus one. */
7157 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7158 same may be minus one and thus the multiplication may overflow. Perform
7159 the sum operation in an unsigned type. */
7164 /* If the sum evaluated to a constant that is not -INF the multiplication
7165 cannot overflow. */
7172 /* Do not resort to unsigned multiplication because
7173 we lose the no-overflow property of the expression. */
7175 }
7177 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7178 specified by EXPR into the buffer PTR of length LEN bytes.
7179 Return the number of bytes placed in the buffer, or zero
7180 upon failure. */
7182 static int
7184 {
7196 /* Dry run. */
7202 {
7204 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7205 number of bytes. */
7209 {
7216 else
7218 }
7219 else
7223 }
7225 }
7228 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7229 specified by EXPR into the buffer PTR of length LEN bytes.
7230 Return the number of bytes placed in the buffer, or zero
7231 upon failure. */
7233 static int
7235 {
7239 FIXED_VALUE_TYPE value;
7254 }
7257 /* Subroutine of native_encode_expr. Encode the REAL_CST
7258 specified by EXPR into the buffer PTR of length LEN bytes.
7259 Return the number of bytes placed in the buffer, or zero
7260 upon failure. */
7262 static int
7264 {
7270 /* There are always 32 bits in each long, no matter the size of
7271 the hosts long. We handle floating point representations with
7272 up to 192 bits. */
7281 /* Dry run. */
7290 {
7295 {
7302 else
7304 }
7305 else
7306 {
7309 {
7310 /* Reverse bytes within each long, or within the entire float
7311 if it's smaller than a long (for HFmode). */
7314 }
7315 }
7320 }
7322 }
7324 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7325 specified by EXPR into the buffer PTR of length LEN bytes.
7326 Return the number of bytes placed in the buffer, or zero
7327 upon failure. */
7329 static int
7331 {
7333 tree part;
7347 }
7350 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7351 specified by EXPR into the buffer PTR of length LEN bytes.
7352 Return the number of bytes placed in the buffer, or zero
7353 upon failure. */
7355 static int
7357 {
7368 {
7370 {
7373 }
7384 }
7386 }
7389 /* Subroutine of native_encode_expr. Encode the STRING_CST
7390 specified by EXPR into the buffer PTR of length LEN bytes.
7391 Return the number of bytes placed in the buffer, or zero
7392 upon failure. */
7394 static int
7396 {
7399 /* Wide-char strings are encoded in target byte-order so native
7400 encoding them is trivial. */
7415 {
7418 {
7421 }
7424 }
7425 else
7428 }
7431 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7432 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7433 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7434 anything, just do a dry run. If OFF is not -1 then start
7435 the encoding at byte offset OFF and encode at most LEN bytes.
7436 Return the number of bytes placed in the buffer, or zero upon failure. */
7438 int
7440 {
7441 /* We don't support starting at negative offset and -1 is special. */
7446 {
7467 }
7468 }
7471 /* Subroutine of native_interpret_expr. Interpret the contents of
7472 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7473 If the buffer cannot be interpreted, return NULL_TREE. */
7475 static tree
7477 {
7487 }
7490 /* Subroutine of native_interpret_expr. Interpret the contents of
7491 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7492 If the buffer cannot be interpreted, return NULL_TREE. */
7494 static tree
7496 {
7499 double_int result;
7500 FIXED_VALUE_TYPE fixed_value;
7510 }
7513 /* Subroutine of native_interpret_expr. Interpret the contents of
7514 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7515 If the buffer cannot be interpreted, return NULL_TREE. */
7517 static tree
7519 {
7523 /* There are always 32 bits in each long, no matter the size of
7524 the hosts long. We handle floating point representations with
7525 up to 192 bits. */
7526 REAL_VALUE_TYPE r;
7536 {
7537 /* Both OFFSET and BYTE index within a long;
7538 bitpos indexes the whole float. */
7541 {
7548 else
7550 }
7551 else
7552 {
7555 {
7556 /* Reverse bytes within each long, or within the entire float
7557 if it's smaller than a long (for HFmode). */
7560 }
7561 }
7565 }
7569 }
7572 /* Subroutine of native_interpret_expr. Interpret the contents of
7573 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7574 If the buffer cannot be interpreted, return NULL_TREE. */
7576 static tree
7578 {
7593 }
7596 /* Subroutine of native_interpret_expr. Interpret the contents of
7597 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7598 If the buffer cannot be interpreted, return NULL_TREE. */
7600 static tree
7602 {
7615 {
7620 }
7622 }
7625 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7626 the buffer PTR of length LEN as a constant of type TYPE. For
7627 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7628 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7629 return NULL_TREE. */
7631 tree
7633 {
7635 {
7657 }
7658 }
7660 /* Returns true if we can interpret the contents of a native encoding
7661 as TYPE. */
7663 static bool
7665 {
7667 {
7680 }
7681 }
7684 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7685 TYPE at compile-time. If we're unable to perform the conversion
7686 return NULL_TREE. */
7688 static tree
7690 {
7691 /* We support up to 512-bit values (for V8DFmode). */
7695 /* Check that the host and target are sane. */
7704 }
7706 /* Build an expression for the address of T. Folds away INDIRECT_REF
7707 to avoid confusing the gimplify process. */
7709 tree
7711 {
7712 /* The size of the object is not relevant when talking about its address. */
7717 {
7722 }
7732 {
7737 }
7738 else
7742 }
7744 /* Build an expression for the address of T. */
7746 tree
7748 {
7752 }
7754 /* Fold a unary expression of code CODE and type TYPE with operand
7755 OP0. Return the folded expression if folding is successful.
7756 Otherwise, return NULL_TREE. */
7758 tree
7760 {
7761 tree tem;
7762 tree arg0;
7770 {
7773 {
7774 /* Don't use STRIP_NOPS, because signedness of argument type
7775 matters. */
7777 }
7778 else
7779 {
7780 /* Strip any conversions that don't change the mode. This
7781 is safe for every expression, except for a comparison
7782 expression because its signedness is derived from its
7783 operands.
7785 Note that this is done as an internal manipulation within
7786 the constant folder, in order to find the simplest
7787 representation of the arguments so that their form can be
7788 studied. In any cases, the appropriate type conversions
7789 should be put back in the tree that will get out of the
7790 constant folder. */
7792 }
7795 {
7798 {
7802 }
7803 }
7804 }
7811 {
7818 {
7832 /* If this was a conversion, and all we did was to move into
7833 inside the COND_EXPR, bring it back out. But leave it if
7834 it is a conversion from integer to integer and the
7835 result precision is no wider than a word since such a
7836 conversion is cheap and may be optimized away by combine,
7837 while it couldn't if it were outside the COND_EXPR. Then return
7838 so we don't get into an infinite recursion loop taking the
7839 conversion out and then back in. */
7851 && (INTEGRAL_TYPE_P
7864 }
7865 }
7868 {
7874 CASE_CONVERT:
7878 {
7879 /* If we have (type) (a CMP b) and type is an integral type, return
7880 new expression involving the new type. Canonicalize
7881 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7882 non-integral type.
7883 Do not fold the result as that would not simplify further, also
7884 folding again results in recursions. */
7894 }
7896 /* Handle (T *)&A.B.C for A being of type T and B and C
7897 living at offset zero. This occurs frequently in
7898 C++ upcasting and then accessing the base. */
7902 {
7904 tree offset;
7905 machine_mode mode;
7907 tree base
7911 /* If the reference was to a (constant) zero offset, we can use
7912 the address of the base if it has the same base type
7913 as the result type and the pointer type is unqualified. */
7921 }
7925 /* Detect assigning a bitfield. */
7927 && DECL_BIT_FIELD
7929 {
7930 /* Don't leave an assignment inside a conversion
7931 unless assigning a bitfield. */
7933 /* First do the assignment, then return converted constant. */
7938 }
7940 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7941 constants (if x has signed type, the sign bit cannot be set
7942 in c). This folds extension into the BIT_AND_EXPR.
7943 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7944 very likely don't have maximal range for their precision and this
7945 transformation effectively doesn't preserve non-maximal ranges. */
7949 {
7960 <= HOST_BITS_PER_WIDE_INT
7962 {
7966 cst &= HOST_WIDE_INT_M1U
7970 && !flag_syntax_only
7973 {
7977 }
7978 }
7980 {
7985 }
7986 }
7988 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7989 cast (T1)X will fold away. We assume that this happens when X itself
7990 is a cast. */
7994 {
7998 return fold_build_pointer_plus_loc
8000 }
8002 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8003 of the same precision, and X is an integer type not narrower than
8004 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8010 {
8016 }
8018 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8019 type of X and Y (integer types only). */
8024 {
8025 /* Be careful not to introduce new overflows. */
8026 tree mult_type;
8029 else
8033 {
8040 }
8041 }
8047 {
8054 }
8065 /* Convert fabs((double)float) into (double)fabsf(float). */
8068 {
8074 targ0));
8075 }
8079 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8098 /* Note that the operand of this must be an int
8099 and its values must be 0 or 1.
8100 ("true" is a fixed value perhaps depending on the language,
8101 but we don't handle values other than 1 correctly yet.) */
8108 /* Fold *&X to X if X is an lvalue. */
8110 {
8117 }
8123 }
8126 /* If the operation was a conversion do _not_ mark a resulting constant
8127 with TREE_OVERFLOW if the original constant was not. These conversions
8128 have implementation defined behavior and retaining the TREE_OVERFLOW
8129 flag here would confuse later passes such as VRP. */
8130 tree
8133 {
8142 }
8144 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8145 operands OP0 and OP1. LOC is the location of the resulting expression.
8146 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8147 Return the folded expression if folding is successful. Otherwise,
8148 return NULL_TREE. */
8149 static tree
8152 {
8153 tree tem;
8155 /* We only do these simplifications if we are optimizing. */
8159 /* Check for things like (A || B) && (A || C). We can convert this
8160 to A || (B && C). Note that either operator can be any of the four
8161 truth and/or operations and the transformation will still be
8162 valid. Also note that we only care about order for the
8163 ANDIF and ORIF operators. If B contains side effects, this
8164 might change the truth-value of A. */
8171 {
8191 /* This case if tricky because we must either have commutative
8192 operators or else A10 must not have side-effects. */
8198 a01);
8199 }
8201 /* See if we can build a range comparison. */
8207 {
8211 }
8215 {
8219 }
8221 /* Check for the possibility of merging component references. If our
8222 lhs is another similar operation, try to merge its rhs with our
8223 rhs. Then try to merge our lhs and rhs. */
8233 && !flag_sanitize_coverage
8238 {
8245 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8246 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8247 We don't want to pack more than two leafs to a non-IF AND/OR
8248 expression.
8249 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8250 equal to IF-CODE, then we don't want to add right-hand operand.
8251 If the inner right-hand side of left-hand operand has
8252 side-effects, or isn't simple, then we can't add to it,
8253 as otherwise we might destroy if-sequence. */
8256 /* Needed for sequence points to handle trappings, and
8257 side-effects. */
8259 {
8261 arg1);
8263 tem);
8264 }
8265 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8266 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8269 /* Needed for sequence points to handle trappings, and
8270 side-effects. */
8272 {
8277 }
8278 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8279 into (A OR B).
8280 For sequence point consistancy, we need to check for trapping,
8281 and side-effects. */
8285 }
8288 }
8290 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8291 by changing CODE to reduce the magnitude of constants involved in
8292 ARG0 of the comparison.
8293 Returns a canonicalized comparison tree if a simplification was
8294 possible, otherwise returns NULL_TREE.
8295 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8296 valid if signed overflow is undefined. */
8298 static tree
8302 {
8307 /* Match A +- CST code arg1. We can change this only if overflow
8308 is undefined. */
8311 /* In principle pointers also have undefined overflow behavior,
8312 but that causes problems elsewhere. */
8319 /* Identify the constant in arg0 and its sign. */
8323 /* Overflowed constants and zero will cause problems. */
8328 /* See if we can reduce the magnitude of the constant in
8329 arg0 by changing the comparison code. */
8330 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8334 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8338 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8342 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8346 else
8350 /* Now build the constant reduced in magnitude. But not if that
8351 would produce one outside of its types range. */
8367 }
8369 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8370 overflow further. Try to decrease the magnitude of constants involved
8371 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8372 and put sole constants at the second argument position.
8373 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8375 static tree
8378 {
8379 tree t;
8384 /* Try canonicalization by simplifying arg0. */
8389 {
8393 }
8395 /* Try canonicalization by simplifying arg1 using the swapped
8396 comparison. */
8404 }
8406 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8407 space. This is used to avoid issuing overflow warnings for
8408 expressions like &p->x which can not wrap. */
8410 static bool
8412 {
8419 poly_wide_int wi_offset;
8425 else
8430 precision);
8445 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8446 array. */
8455 }
8457 /* Return a positive integer when the symbol DECL is known to have
8458 a nonzero address, zero when it's known not to (e.g., it's a weak
8459 symbol), and a negative integer when the symbol is not yet in the
8460 symbol table and so whether or not its address is zero is unknown.
8461 For function local objects always return positive integer. */
8462 static int
8464 {
8469 /* Function local objects are never NULL. */
8477 }
8479 /* Subroutine of fold_binary. This routine performs all of the
8480 transformations that are common to the equality/inequality
8481 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8482 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8483 fold_binary should call fold_binary. Fold a comparison with
8484 tree code CODE and type TYPE with operands OP0 and OP1. Return
8485 the folded comparison or NULL_TREE. */
8487 static tree
8490 {
8500 /* For comparisons of pointers we can decompose it to a compile time
8501 comparison of the base objects and the offsets into the object.
8502 This requires at least one operand being an ADDR_EXPR or a
8503 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8509 {
8512 machine_mode mode;
8516 /* Get base and offset for the access. Strip ADDR_EXPR for
8517 get_inner_reference, but put it back by stripping INDIRECT_REF
8518 off the base object if possible. indirect_baseN will be true
8519 if baseN is not an address but refers to the object itself. */
8522 {
8523 base0
8529 else
8531 }
8533 {
8537 {
8538 base0
8544 else
8546 }
8549 else
8553 {
8560 }
8561 }
8565 {
8566 base1
8572 else
8574 }
8576 {
8580 {
8581 base1
8587 else
8589 }
8592 else
8596 {
8603 }
8604 }
8606 /* If we have equivalent bases we might be able to simplify. */
8610 {
8611 /* We can fold this expression to a constant if the non-constant
8612 offset parts are equal. */
8616 && (equality_code
8617 || (indirect_base0
8620 {
8626 "occur when comparing P +- C1 with "
8628 WARN_STRICT_OVERFLOW_CONDITIONAL);
8631 {
8669 }
8670 }
8671 /* We can simplify the comparison to a comparison of the variable
8672 offset parts if the constant offset parts are equal.
8673 Be careful to use signed sizetype here because otherwise we
8674 mess with array offsets in the wrong way. This is possible
8675 because pointer arithmetic is restricted to retain within an
8676 object and overflow on pointer differences is undefined as of
8677 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8679 && (equality_code
8680 || (indirect_base0
8683 {
8684 /* By converting to signed sizetype we cover middle-end pointer
8685 arithmetic which operates on unsigned pointer types of size
8686 type size and ARRAY_REF offsets which are properly sign or
8687 zero extended from their type in case it is narrower than
8688 sizetype. */
8691 else
8695 else
8702 "occur when comparing P +- C1 with "
8704 WARN_STRICT_OVERFLOW_COMPARISON);
8707 }
8708 }
8709 /* For equal offsets we can simplify to a comparison of the
8710 base addresses. */
8712 && (indirect_base0
8714 && (indirect_base1
8719 {
8725 }
8726 /* Comparison between an ordinary (non-weak) symbol and a null
8727 pointer can be eliminated since such symbols must have a non
8728 null address. In C, relational expressions between pointers
8729 to objects and null pointers are undefined. The results
8730 below follow the C++ rules with the additional property that
8731 every object pointer compares greater than a null pointer.
8732 */
8735 /* Avoid folding references to struct members at offset 0 to
8736 prevent tests like '&ptr->firstmember == 0' from getting
8737 eliminated. When ptr is null, although the -> expression
8738 is strictly speaking invalid, GCC retains it as a matter
8739 of QoI. See PR c/44555. */
8742 && indirect_base0
8743 /* The caller guarantees that when one of the arguments is
8744 constant (i.e., null in this case) it is second. */
8746 {
8748 {
8759 }
8760 }
8761 }
8763 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8764 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8765 the resulting offset is smaller in absolute value than the
8766 original one and has the same sign. */
8775 {
8780 tree cst;
8782 "occur when combining constants around "
8785 /* Put the constant on the side where it doesn't overflow and is
8786 of lower absolute value and of same sign than before. */
8793 {
8796 variable1,
8800 }
8808 {
8814 variable2);
8815 }
8816 }
8822 /* If we are comparing an expression that just has comparisons
8823 of two integer values, arithmetic expressions of those comparisons,
8824 and constants, we can simplify it. There are only three cases
8825 to check: the two values can either be equal, the first can be
8826 greater, or the second can be greater. Fold the expression for
8827 those three values. Since each value must be 0 or 1, we have
8828 eight possibilities, each of which corresponds to the constant 0
8829 or 1 or one of the six possible comparisons.
8831 This handles common cases like (a > b) == 0 but also handles
8832 expressions like ((x > y) - (y > x)) > 0, which supposedly
8833 occur in macroized code. */
8836 {
8840 /* Don't handle degenerate cases here; they should already
8841 have been handled anyway. */
8850 {
8854 /* We can't just pass T to eval_subst in case cval1 or cval2
8855 was the same as ARG1. */
8857 tree high_result
8861 arg1);
8862 tree equal_result
8866 arg1);
8867 tree low_result
8871 arg1);
8873 /* All three of these results should be 0 or 1. Confirm they are.
8874 Then use those values to select the proper code to use. */
8879 {
8880 /* Make a 3-bit mask with the high-order bit being the
8881 value for `>', the next for '=', and the low for '<'. */
8885 {
8887 /* Always false. */
8908 /* Always true. */
8910 }
8913 }
8914 }
8915 }
8918 }
8921 /* Subroutine of fold_binary. Optimize complex multiplications of the
8922 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8923 argument EXPR represents the expression "z" of type TYPE. */
8925 static tree
8927 {
8932 {
8935 }
8937 {
8940 }
8941 else
8942 {
8946 }
8955 }
8958 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8959 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8960 true if successful. */
8962 static bool
8964 {
8969 {
8972 }
8974 {
8980 else
8982 }
8983 else
8989 }
8991 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8992 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8993 NULL_TREE otherwise. */
8995 static tree
8997 {
9018 {
9019 HOST_WIDE_INT index;
9025 }
9028 {
9034 }
9035 else
9037 }
9039 /* Try to fold a pointer difference of type TYPE two address expressions of
9040 array references AREF0 and AREF1 using location LOC. Return a
9041 simplified expression for the difference or NULL_TREE. */
9043 static tree
9047 {
9052 /* If the bases are array references as well, recurse. If the bases
9053 are pointer indirections compute the difference of the pointers.
9054 If the bases are equal, we are set. */
9057 && (base_offset
9059 use_pointer_diff)))
9062 && (base_offset
9063 = use_pointer_diff
9073 {
9079 base_offset,
9082 }
9084 }
9086 /* If the real or vector real constant CST of type TYPE has an exact
9087 inverse, return it, else return NULL. */
9089 tree
9091 {
9092 REAL_VALUE_TYPE r;
9093 tree unit_type;
9094 machine_mode mode;
9097 {
9107 {
9111 tree_vector_builder elts;
9116 {
9121 }
9124 }
9128 }
9129 }
9131 /* Mask out the tz least significant bits of X of type TYPE where
9132 tz is the number of trailing zeroes in Y. */
9133 static wide_int
9135 {
9140 }
9142 /* Return true when T is an address and is known to be nonzero.
9143 For floating point we further ensure that T is not denormal.
9144 Similar logic is present in nonzero_address in rtlanal.h.
9146 If the return value is based on the assumption that signed overflow
9147 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9148 change *STRICT_OVERFLOW_P. */
9150 static bool
9152 {
9156 /* Doing something useful for floating point would need more work. */
9162 {
9165 strict_overflow_p);
9171 strict_overflow_p);
9179 }
9182 {
9185 strict_overflow_p);
9193 strict_overflow_p);
9208 strict_overflow_p);
9212 strict_overflow_p);
9215 {
9227 }
9231 }
9233 }
9235 /* Return true when T is an address and is known to be nonzero.
9236 Handle warnings about undefined signed overflow. */
9238 bool
9240 {
9247 "determining that expression is always "
9249 WARN_STRICT_OVERFLOW_MISC);
9251 }
9253 /* Return true if T is known not to be equal to an integer W. */
9255 bool
9257 {
9259 value_range_kind rtype;
9261 {
9270 {
9275 }
9280 /* If T has some known zero bits and W has any of those bits set,
9281 then T is known not to be equal to W. */
9289 }
9290 }
9292 /* Fold a binary expression of code CODE and type TYPE with operands
9293 OP0 and OP1. LOC is the location of the resulting expression.
9294 Return the folded expression if folding is successful. Otherwise,
9295 return NULL_TREE. */
9297 tree
9300 {
9315 /* Strip any conversions that don't change the mode. This is
9316 safe for every expression, except for a comparison expression
9317 because its signedness is derived from its operands. So, in
9318 the latter case, only strip conversions that don't change the
9319 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9320 preserved.
9322 Note that this is done as an internal manipulation within the
9323 constant folder, in order to find the simplest representation
9324 of the arguments so that their form can be studied. In any
9325 cases, the appropriate type conversions should be put back in
9326 the tree that will get out of the constant folder. */
9329 {
9332 }
9333 else
9334 {
9337 }
9339 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9340 constant but we can't do arithmetic on them. */
9342 {
9345 {
9349 }
9350 }
9352 /* If this is a commutative operation, and ARG0 is a constant, move it
9353 to ARG1 to reduce the number of tests below. */
9358 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9359 to ARG1 to reduce the number of tests below. */
9368 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9370 First check for cases where an arithmetic operation is applied to a
9371 compound, conditional, or comparison operation. Push the arithmetic
9372 operation inside the compound or conditional to see if any folding
9373 can then be done. Convert comparison to conditional for this purpose.
9374 The also optimizes non-constant cases that used to be done in
9375 expand_expr.
9377 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9378 one of the operands is a comparison and the other is a comparison, a
9379 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9380 code below would make the expression more complex. Change it to a
9381 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9382 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9395 {
9399 boolean_type_node,
9407 }
9411 {
9413 {
9418 tem);
9419 }
9421 {
9426 tem);
9427 }
9432 {
9438 }
9443 {
9449 }
9450 }
9453 {
9455 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9458 {
9464 }
9466 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9469 {
9470 tree base;
9471 poly_int64 coffset;
9480 }
9485 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9491 arg1),
9493 arg0)));
9499 {
9500 /* X + (X / CST) * -CST is X % CST. */
9505 {
9514 cst0));
9515 }
9516 }
9518 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9519 one. Make sure the type is not saturating and has the signedness of
9520 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9521 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9528 {
9532 }
9535 {
9536 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9537 (plus (plus (mult) (mult)) (foo)) so that we can
9538 take advantage of the factoring cases below. */
9547 {
9553 else
9566 parg0),
9568 marg)),
9572 return
9578 parg1)));
9579 }
9580 }
9581 else
9582 {
9583 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9584 to __complex__ ( x, y ). This is not the same for SNaNs or
9585 if signed zeros are involved. */
9589 {
9596 {
9600 {
9606 }
9608 {
9614 }
9615 }
9616 }
9618 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9619 We associate floats only if the user has specified
9620 -fassociative-math. */
9624 {
9629 {
9630 tree tree0;
9633 }
9634 }
9635 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9636 We associate floats only if the user has specified
9637 -fassociative-math. */
9641 {
9646 {
9647 tree tree0;
9650 }
9651 }
9652 }
9654 bit_rotate:
9655 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9656 is a rotate of A by C1 bits. */
9657 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9658 is a rotate of A by B bits.
9659 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9660 though in this case CODE must be | and not + or ^, otherwise
9661 it doesn't return A when B is 0. */
9662 {
9664 tree rtype;
9673 /* Only create rotates in complete modes. Other cases are not
9674 expanded properly. */
9677 {
9690 {
9695 }
9700 {
9703 code0 == LSHIFT_EXPR
9706 }
9708 {
9718 {
9722 orig_tree01);
9724 }
9725 }
9729 {
9740 {
9744 orig_tree01);
9746 }
9747 }
9748 }
9749 }
9751 associate:
9752 /* In most languages, can't associate operations on floats through
9753 parentheses. Rather than remember where the parentheses were, we
9754 don't associate floats at all, unless the user has specified
9755 -fassociative-math.
9756 And, we need to make sure type is not saturating. */
9760 {
9766 /* Split both trees into variables, constants, and literals. Then
9767 associate each group together, the constants with literals,
9768 then the result with variables. This increases the chances of
9769 literals being recombined later and of generating relocatable
9770 expressions for the sum of a constant and literal. */
9778 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9782 /* With undefined overflow prefer doing association in a type
9783 which wraps on overflow, if that is one of the operand types. */
9786 {
9794 }
9796 /* With undefined overflow we can only associate constants with one
9797 variable, and constants whose association doesn't overflow. */
9800 {
9802 {
9803 /* ??? If split_tree would handle NEGATE_EXPR we could
9804 simply reject these cases and the allowed cases would
9805 be the var0/minus_var1 ones. */
9811 {
9814 }
9821 {
9824 }
9830 /* The only case we can still associate with two variables
9831 is if they cancel out. */
9835 }
9841 }
9843 /* Only do something if we found more than two objects. Otherwise,
9844 nothing has changed and we risk infinite recursion. */
9852 {
9864 {
9868 }
9870 {
9874 }
9876 /* Preserve the MINUS_EXPR if the negative part of the literal is
9877 greater than the positive part. Otherwise, the multiplicative
9878 folding code (i.e extract_muldiv) may be fooled in case
9879 unsigned constants are subtracted, like in the following
9880 example: ((X*2 + 4) - 8U)/2. */
9882 {
9886 /* But avoid ending up with only negated parts. */
9888 {
9892 }
9893 else
9894 {
9898 }
9899 }
9901 /* Don't introduce overflows through reassociation. */
9906 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9913 /* Eliminate minus_con0. */
9915 {
9922 else
9925 }
9927 /* Eliminate minus_var0. */
9929 {
9933 else
9936 }
9938 return
9941 }
9942 }
9948 /* Fold &a[i] - &a[j] to i-j. */
9953 {
9957 code
9961 }
9963 /* Further transformations are not for pointers. */
9967 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9970 /* If arg0 is e.g. unsigned int and type is int, then this could
9971 introduce UB, because if A is INT_MIN at runtime, the original
9972 expression can be well defined while the latter is not.
9973 See PR83269. */
9982 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9983 __complex__ ( x, -y ). This is not the same for SNaNs or if
9984 signed zeros are involved. */
9988 {
9995 {
9999 {
10001 arg1r ? arg1r
10006 }
10008 {
10012 arg1i ? arg1i
10015 }
10016 }
10017 }
10019 /* A - B -> A + (-B) if B is easily negatable. */
10023 /* Avoid this transformation if B is a positive REAL_CST. */
10031 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10032 one. Make sure the type is not saturating and has the signedness of
10033 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10034 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10041 {
10045 }
10051 {
10052 /* Transform x * -C into -x * C if x is easily negatable. */
10067 {
10070 "occur when simplifying "
10072 WARN_STRICT_OVERFLOW_MISC);
10074 }
10076 /* Optimize z * conj(z) for integer complex numbers. */
10083 }
10084 else
10085 {
10086 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10087 This is not the same for NaNs or if signed zeros are
10088 involved. */
10094 {
10097 return
10103 return
10108 }
10110 /* Optimize z * conj(z) for floating point complex numbers.
10111 Guarded by flag_unsafe_math_optimizations as non-finite
10112 imaginary components don't produce scalar results. */
10121 }
10125 /* Canonicalize (X & C1) | C2. */
10129 {
10134 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10142 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10144 {
10147 }
10149 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10150 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10151 mode which allows further optimizations. */
10156 {
10161 {
10164 }
10165 }
10168 {
10173 }
10174 }
10176 /* See if this can be simplified into a rotate first. If that
10177 is unsuccessful continue in the association code. */
10181 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10189 /* See if this can be simplified into a rotate first. If that
10190 is unsuccessful continue in the association code. */
10194 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10199 {
10200 tree tem2;
10207 }
10208 /* Fold ~X & 1 as (X & 1) == 0. */
10212 {
10213 tree tem2;
10220 }
10221 /* Fold !X & 1 as X == 0. */
10224 {
10228 }
10230 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10231 multiple of 1 << CST. */
10233 {
10240 }
10242 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10243 bits from CST2. */
10247 {
10249 wide_int masked
10256 {
10257 /* Avoid the transform if arg1 is a mask of some
10258 mode which allows further optimizations. */
10265 }
10266 }
10268 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10271 {
10276 return
10278 }
10283 /* Don't touch a floating-point divide by zero unless the mode
10284 of the constant can represent infinity. */
10290 /* (-A) / (-B) -> A / B */
10302 /* Fall through */
10305 /* Simplify A / (B << N) where A and B are positive and B is
10306 a power of 2, to A >> (N + log2(B)). */
10311 {
10314 {
10322 WARN_STRICT_OVERFLOW_MISC);
10328 }
10329 }
10331 /* Fall through */
10339 /* Convert -A / -B to A / B when the type is signed and overflow is
10340 undefined. */
10344 {
10347 "when distributing negation across "
10349 WARN_STRICT_OVERFLOW_MISC);
10354 }
10358 {
10361 "when distributing negation across "
10363 WARN_STRICT_OVERFLOW_MISC);
10368 }
10370 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10371 operation, EXACT_DIV_EXPR.
10373 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10374 At one time others generated faster code, it's not clear if they do
10375 after the last round to changes to the DIV code in expmed.c. */
10386 {
10390 WARN_STRICT_OVERFLOW_MISC);
10392 }
10404 {
10408 WARN_STRICT_OVERFLOW_MISC);
10410 }
10418 /* Since negative shift count is not well-defined,
10419 don't try to compute it in the compiler. */
10425 /* If we have a rotate of a bit operation with the rotate count and
10426 the second operand of the bit operation both constant,
10427 permute the two operations. */
10433 {
10441 }
10443 /* Two consecutive rotates adding up to the some integer
10444 multiple of the precision of the type can be ignored. */
10460 /* Note that the operands of this must be ints
10461 and their values must be 0 or 1.
10462 ("true" is a fixed value perhaps depending on the language.) */
10463 /* If first arg is constant zero, return it. */
10466 /* FALLTHRU */
10468 /* If either arg is constant true, drop it. */
10472 /* Preserve sequence points. */
10475 /* If second arg is constant zero, result is zero, but first arg
10476 must be evaluated. */
10479 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10480 case will be handled here. */
10484 /* !X && X is always false. */
10488 /* X && !X is always false. */
10493 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10494 means A >= Y && A != MAX, but in this case we know that
10495 A < X <= MAX. */
10499 {
10507 }
10516 /* Note that the operands of this must be ints
10517 and their values must be 0 or true.
10518 ("true" is a fixed value perhaps depending on the language.) */
10519 /* If first arg is constant true, return it. */
10522 /* FALLTHRU */
10524 /* If either arg is constant zero, drop it. */
10528 /* Preserve sequence points. */
10531 /* If second arg is constant true, result is true, but we must
10532 evaluate first arg. */
10535 /* Likewise for first arg, but note this only occurs here for
10536 TRUTH_OR_EXPR. */
10540 /* !X || X is always true. */
10544 /* X || !X is always true. */
10549 /* (X && !Y) || (!X && Y) is X ^ Y */
10552 {
10569 }
10578 /* If the second arg is constant zero, drop it. */
10581 /* If the second arg is constant true, this is a logical inversion. */
10583 {
10586 }
10587 /* Identical arguments cancel to zero. */
10591 /* !X ^ X is always true. */
10596 /* X ^ !X is always true. */
10612 /* bool_var != 1 becomes !bool_var. */
10619 /* bool_var == 0 becomes !bool_var. */
10626 /* !exp != 0 becomes !exp */
10631 /* If this is an EQ or NE comparison with zero and ARG0 is
10632 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10633 two operations, but the latter can be done in one less insn
10634 on machines that have only two-operand insns or on which a
10635 constant cannot be the first operand. */
10638 {
10643 {
10650 arg1);
10651 }
10654 {
10661 arg1);
10662 }
10663 }
10665 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10666 C1 is a valid shift constant, and C2 is a power of two, i.e.
10667 a single bit. */
10671 == INTEGER_CST
10674 {
10679 /* Check for a valid shift count. */
10681 {
10685 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10686 can be rewritten as (X & (C2 << C1)) != 0. */
10688 {
10693 }
10694 /* Otherwise, for signed (arithmetic) shifts,
10695 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10696 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10700 /* Otherwise, of unsigned (logical) shifts,
10701 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10702 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10703 else
10707 arg000);
10708 }
10709 }
10711 /* If this is a comparison of a field, we may be able to simplify it. */
10714 /* Handle the constant case even without -O
10715 to make sure the warnings are given. */
10717 {
10721 }
10723 /* Optimize comparisons of strlen vs zero to a compare of the
10724 first character of the string vs zero. To wit,
10725 strlen(ptr) == 0 => *ptr == 0
10726 strlen(ptr) != 0 => *ptr != 0
10727 Other cases should reduce to one of these two (or a constant)
10728 due to the return value of strlen being unsigned. */
10731 {
10738 {
10743 }
10744 }
10746 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10747 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10751 {
10756 {
10758 {
10761 }
10764 }
10765 }
10767 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10768 (X & C) == 0 when C is a single bit. */
10773 {
10780 arg1));
10781 }
10783 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10784 constant C is a power of two, i.e. a single bit. */
10791 {
10795 }
10797 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10798 when is C is a power of two, i.e. a single bit. */
10805 {
10811 }
10815 {
10818 }
10820 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10823 {
10831 {
10837 }
10839 {
10845 }
10847 {
10853 }
10855 {
10861 }
10862 }
10866 {
10873 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10874 operand_equal_p guarantees no side-effects so we don't need
10875 to use omit_one_operand on Z. */
10879 arg10));
10883 arg11));
10887 arg10));
10891 arg11));
10893 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10896 {
10902 }
10903 }
10905 /* Attempt to simplify equality/inequality comparisons of complex
10906 values. Only lower the comparison if the result is known or
10907 can be simplified to a single scalar comparison. */
10912 {
10917 {
10920 }
10921 else
10922 {
10925 }
10928 {
10931 }
10932 else
10933 {
10936 }
10940 {
10942 {
10947 }
10948 else
10949 {
10954 }
10955 }
10959 {
10961 {
10966 }
10967 else
10968 {
10973 }
10974 }
10975 }
10987 /* Transform comparisons of the form X +- C CMP X. */
10992 {
10997 /* (X - c) > X becomes false. */
11003 /* Likewise (X + c) < X becomes false. */
11009 /* Convert (X - c) <= X to true. */
11016 /* Convert (X + c) >= X to true. */
11022 }
11024 /* If we are comparing an ABS_EXPR with a constant, we can
11025 convert all the cases into explicit comparisons, but they may
11026 well not be faster than doing the ABS and one comparison.
11027 But ABS (X) <= C is a range comparison, which becomes a subtraction
11028 and a comparison, and is probably faster. */
11042 /* Convert ABS_EXPR<x> >= 0 to true. */
11049 {
11052 "when simplifying comparison of "
11054 WARN_STRICT_OVERFLOW_CONDITIONAL);
11057 arg0);
11058 }
11060 /* Convert ABS_EXPR<x> < 0 to false. */
11065 {
11068 "when simplifying comparison of "
11070 WARN_STRICT_OVERFLOW_CONDITIONAL);
11073 arg0);
11074 }
11076 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11077 and similarly for >= into !=. */
11087 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11088 otherwise Y might be >= # of bits in X's type and thus e.g.
11089 (unsigned char) (1 << Y) for Y 15 might be 0.
11090 If the cast is widening, then 1 << Y should have unsigned type,
11091 otherwise if Y is number of bits in the signed shift type minus 1,
11092 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11093 31 might be 0xffffffff80000000. */
11104 {
11110 }
11122 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11123 {
11135 }
11140 /* When pedantic, a compound expression can be neither an lvalue
11141 nor an integer constant expression. */
11144 /* Don't let (0, 0) be null pointer constant. */
11150 /* An ASSERT_EXPR should never be passed to fold_binary. */
11156 }
11158 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11159 ((A & N) + B) & M -> (A + B) & M
11160 Similarly if (N & M) == 0,
11161 ((A | N) + B) & M -> (A + B) & M
11162 and for - instead of + (or unary - instead of +)
11163 and/or ^ instead of |.
11164 If B is constant and (B & M) == 0, fold into A & M.
11166 This function is a helper for match.pd patterns. Return non-NULL
11167 type in which the simplified operation should be performed only
11168 if any optimization is possible.
11170 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11171 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11172 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11173 +/-. */
11174 tree
11179 {
11194 wide_int cst0;
11196 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11197 arg1 (M) is == (1LL << cst) - 1.
11198 Store C into PMOP[0] and D into PMOP[1]. */
11205 {
11212 {
11215 }
11218 /* If C or D is of the form (A & N) where
11219 (N & M) == M, or of the form (A | N) or
11220 (A ^ N) where (N & M) == 0, replace it with A. */
11226 /* If C or D is a N where (N & M) == 0, it can be
11227 omitted (replaced with 0). */
11232 /* Similarly, with C - N where (-N & M) == 0. */
11240 }
11242 /* Only build anything new if we optimized one or both arguments above. */
11248 else
11250 }
11252 /* Used by contains_label_[p1]. */
11254 struct contains_label_data
11255 {
11258 };
11260 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11261 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11262 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11264 static tree
11266 {
11269 {
11280 {
11288 }
11297 }
11298 }
11300 /* Return whether the sub-tree ST contains a label which is accessible from
11301 outside the sub-tree. */
11303 static bool
11305 {
11309 }
11311 /* Fold a ternary expression of code CODE and type TYPE with operands
11312 OP0, OP1, and OP2. Return the folded expression if folding is
11313 successful. Otherwise, return NULL_TREE. */
11315 tree
11318 {
11319 tree tem;
11326 /* If this is a commutative operation, and OP0 is a constant, move it
11327 to OP1 to reduce the number of tests below. */
11336 /* Strip any conversions that don't change the mode. This is safe
11337 for every expression, except for a comparison expression because
11338 its signedness is derived from its operands. So, in the latter
11339 case, only strip conversions that don't change the signedness.
11341 Note that this is done as an internal manipulation within the
11342 constant folder, in order to find the simplest representation of
11343 the arguments so that their form can be studied. In any cases,
11344 the appropriate type conversions should be put back in the tree
11345 that will get out of the constant folder. */
11347 {
11350 }
11353 {
11356 }
11359 {
11362 }
11365 {
11369 {
11375 }
11380 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11381 so all simple results must be passed through pedantic_non_lvalue. */
11383 {
11386 /* Only optimize constant conditions when the selected branch
11387 has the same type as the COND_EXPR. This avoids optimizing
11388 away "c ? x : throw", where the throw has a void type.
11389 Avoid throwing away that operand which contains label. */
11396 }
11398 {
11405 {
11408 {
11416 }
11421 }
11422 }
11424 /* If we have A op B ? A : C, we may be able to convert this to a
11425 simpler expression, depending on the operation and the values
11426 of B and C. Signed zeros prevent all of these transformations,
11427 for reasons given above each one.
11429 Also try swapping the arguments and inverting the conditional. */
11433 {
11437 }
11442 {
11446 {
11450 }
11451 }
11453 /* If the second operand is simpler than the third, swap them
11454 since that produces better jump optimization results. */
11457 {
11459 /* See if this can be inverted. If it can't, possibly because
11460 it was a floating-point inequality comparison, don't do
11461 anything. */
11465 }
11467 /* Convert A ? 1 : 0 to simply A. */
11472 /* If we try to convert OP0 to our type, the
11473 call to fold will try to move the conversion inside
11474 a COND, which will recurse. In that case, the COND_EXPR
11475 is probably the best choice, so leave it alone. */
11479 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11480 over COND_EXPR in cases such as floating point comparisons. */
11489 arg0)));
11491 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11496 {
11497 /* sign_bit_p looks through both zero and sign extensions,
11498 but for this optimization only sign extensions are
11499 usable. */
11502 {
11505 {
11508 }
11510 }
11511 /* sign_bit_p only checks ARG1 bits within A's precision.
11512 If <sign bit of A> has wider type than A, bits outside
11513 of A's precision in <sign bit of A> need to be checked.
11514 If they are all 0, this optimization needs to be done
11515 in unsigned A's type, if they are all 1 in signed A's type,
11516 otherwise this can't be done. */
11522 {
11524 tree tem_type;
11537 {
11540 }
11542 {
11545 }
11546 else
11548 }
11551 return
11557 arg1)));
11558 }
11560 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11561 already handled above. */
11566 {
11576 op1);
11577 }
11579 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11580 is probably obsolete because the first operand should be a
11581 truth value (that's why we have the two cases above), but let's
11582 leave it in until we can confirm this for all front-ends. */
11590 /* operand_equal_p compares just value, not precision, so e.g.
11591 arg1 could be 8-bit -128 and be power of two, but BIT_AND_EXPR
11592 second operand 32-bit -128, which is not a power of two (or vice
11593 versa. */
11600 /* Disable the transformations below for vectors, since
11601 fold_binary_op_with_conditional_arg may undo them immediately,
11602 yielding an infinite loop. */
11606 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11615 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11620 {
11622 /* Only perform transformation if ARG0 is easily inverted. */
11626 ? BIT_IOR_EXPR
11629 op1);
11630 }
11632 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11637 {
11639 /* Only perform transformation if ARG0 is easily inverted. */
11645 op2);
11646 }
11648 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11660 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11661 of fold_ternary on them. */
11671 {
11682 {
11687 {
11689 {
11694 }
11700 }
11701 }
11702 }
11704 /* On constants we can use native encode/interpret to constant
11705 fold (nearly) all BIT_FIELD_REFs. */
11711 {
11714 /* Limit us to a reasonable amount of work. To relax the
11715 other limitations we need bit-shifting of the buffer
11716 and rounding up the size. */
11720 {
11722 unsigned HOST_WIDE_INT len
11727 {
11732 }
11733 }
11734 }
11740 {
11741 /* Build a vector of integers from the tree mask. */
11742 vec_perm_builder builder;
11746 /* Create a vec_perm_indices for the integer vector. */
11751 /* Check for cases that fold to OP0 or OP1 in their original
11752 element order. */
11759 {
11763 {
11766 }
11767 }
11773 {
11777 }
11781 /* Generate a canonical form of the selector. */
11783 {
11784 /* Some targets are deficient and fail to expand a single
11785 argument permutation while still allowing an equivalent
11786 2-argument version. */
11790 else
11791 {
11795 else
11796 /* Not directly supported with either encoding,
11797 so use the preferred form. */
11799 }
11801 }
11805 }
11809 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11812 {
11818 wide_int tem2
11822 }
11827 {
11829 unsigned HOST_WIDE_INT elsize
11832 {
11838 {
11844 }
11845 }
11846 }
11852 }
11854 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11855 of an array (or vector). */
11857 tree
11859 {
11864 {
11867 {
11868 /* Static constructors for variably sized objects makes no sense. */
11872 }
11873 }
11884 offset_int max_index;
11889 {
11890 /* Array constructor might explicitly set index, or specify a range,
11891 or leave index NULL meaning that it is next index after previous
11892 one. */
11894 {
11897 else
11898 {
11902 }
11903 }
11904 else
11905 {
11911 }
11913 /* Do we have match? */
11917 }
11919 }
11921 /* Perform constant folding and related simplification of EXPR.
11922 The related simplifications include x*1 => x, x*0 => 0, etc.,
11923 and application of the associative law.
11924 NOP_EXPR conversions may be removed freely (as long as we
11925 are careful not to change the type of the overall expression).
11926 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11927 but we can constant-fold them if they have constant operands. */
11929 #ifdef ENABLE_FOLD_CHECKING
11930 # define fold(x) fold_1 (x)
11932 static
11933 #endif
11934 tree
11936 {
11940 tree tem;
11943 /* Return right away if a constant. */
11947 /* CALL_EXPR-like objects with variable numbers of operands are
11948 treated specially. */
11950 {
11952 {
11955 }
11957 }
11960 {
11965 {
11983 }
11984 }
11987 {
11989 {
11996 {
12001 }
12004 }
12006 /* Return a VECTOR_CST if possible. */
12008 {
12014 tree val;
12020 }
12028 }
12030 #ifdef ENABLE_FOLD_CHECKING
12031 #undef fold
12038 /* When --enable-checking=fold, compute a digest of expr before
12039 and after actual fold call to see if fold did not accidentally
12040 change original expr. */
12042 tree
12044 {
12045 tree ret;
12065 }
12067 void
12069 {
12080 }
12082 static void
12084 {
12086 }
12088 static void
12091 {
12097 recursive_label:
12107 {
12108 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12113 }
12121 {
12122 /* Allow these fields to be modified. */
12123 tree tmp;
12132 {
12135 }
12136 }
12147 {
12150 {
12166 }
12170 {
12183 }
12200 {
12206 }
12209 {
12211 {
12214 }
12216 }
12227 {
12230 }
12240 }
12241 }
12243 /* Helper function for outputting the checksum of a tree T. When
12244 debugging with gdb, you can "define mynext" to be "next" followed
12245 by "call debug_fold_checksum (op0)", then just trace down till the
12246 outputs differ. */
12248 DEBUG_FUNCTION void
12250 {
12265 }
12267 #endif
12269 /* Fold a unary tree expression with code CODE of type TYPE with an
12270 operand OP0. LOC is the location of the resulting expression.
12271 Return a folded expression if successful. Otherwise, return a tree
12272 expression with code CODE of type TYPE with an operand OP0. */
12274 tree
12277 {
12278 tree tem;
12279 #ifdef ENABLE_FOLD_CHECKING
12288 #endif
12294 #ifdef ENABLE_FOLD_CHECKING
12301 #endif
12303 }
12305 /* Fold a binary tree expression with code CODE of type TYPE with
12306 operands OP0 and OP1. LOC is the location of the resulting
12307 expression. Return a folded expression if successful. Otherwise,
12308 return a tree expression with code CODE of type TYPE with operands
12309 OP0 and OP1. */
12311 tree
12314 MEM_STAT_DECL)
12315 {
12316 tree tem;
12317 #ifdef ENABLE_FOLD_CHECKING
12334 #endif
12340 #ifdef ENABLE_FOLD_CHECKING
12355 #endif
12357 }
12359 /* Fold a ternary tree expression with code CODE of type TYPE with
12360 operands OP0, OP1, and OP2. Return a folded expression if
12361 successful. Otherwise, return a tree expression with code CODE of
12362 type TYPE with operands OP0, OP1, and OP2. */
12364 tree
12367 {
12368 tree tem;
12369 #ifdef ENABLE_FOLD_CHECKING
12393 #endif
12400 #ifdef ENABLE_FOLD_CHECKING
12423 #endif
12425 }
12427 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12428 arguments in ARGARRAY, and a null static chain.
12429 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12430 of type TYPE from the given operands as constructed by build_call_array. */
12432 tree
12435 {
12436 tree tem;
12437 #ifdef ENABLE_FOLD_CHECKING
12456 #endif
12462 #ifdef ENABLE_FOLD_CHECKING
12478 #endif
12480 }
12482 /* Perform constant folding and related simplification of initializer
12483 expression EXPR. These behave identically to "fold_buildN" but ignore
12484 potential run-time traps and exceptions that fold must preserve. */
12486 #define START_FOLD_INIT \
12487 int saved_signaling_nans = flag_signaling_nans;\
12488 int saved_trapping_math = flag_trapping_math;\
12489 int saved_rounding_math = flag_rounding_math;\
12490 int saved_trapv = flag_trapv;\
12491 int saved_folding_initializer = folding_initializer;\
12492 flag_signaling_nans = 0;\
12493 flag_trapping_math = 0;\
12494 flag_rounding_math = 0;\
12495 flag_trapv = 0;\
12496 folding_initializer = 1;
12498 #define END_FOLD_INIT \
12499 flag_signaling_nans = saved_signaling_nans;\
12500 flag_trapping_math = saved_trapping_math;\
12501 flag_rounding_math = saved_rounding_math;\
12502 flag_trapv = saved_trapv;\
12503 folding_initializer = saved_folding_initializer;
12505 tree
12508 {
12509 tree result;
12510 START_FOLD_INIT;
12514 END_FOLD_INIT;
12516 }
12518 tree
12521 {
12522 tree result;
12523 START_FOLD_INIT;
12527 END_FOLD_INIT;
12529 }
12531 tree
12534 {
12535 tree result;
12536 START_FOLD_INIT;
12540 END_FOLD_INIT;
12542 }
12544 #undef START_FOLD_INIT
12545 #undef END_FOLD_INIT
12547 /* Determine if first argument is a multiple of second argument. Return 0 if
12548 it is not, or we cannot easily determined it to be.
12550 An example of the sort of thing we care about (at this point; this routine
12551 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12552 fold cases do now) is discovering that
12554 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12556 is a multiple of
12558 SAVE_EXPR (J * 8)
12560 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12562 This code also handles discovering that
12564 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12566 is a multiple of 8 so we don't have to worry about dealing with a
12567 possible remainder.
12569 Note that we *look* inside a SAVE_EXPR only to determine how it was
12570 calculated; it is not safe for fold to do much of anything else with the
12571 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12572 at run time. For example, the latter example above *cannot* be implemented
12573 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12574 evaluation time of the original SAVE_EXPR is not necessarily the same at
12575 the time the new expression is evaluated. The only optimization of this
12576 sort that would be valid is changing
12578 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12580 divided by 8 to
12582 SAVE_EXPR (I) * SAVE_EXPR (J)
12584 (where the same SAVE_EXPR (J) is used in the original and the
12585 transformed version). */
12587 int
12589 {
12600 {
12602 /* Bitwise and provides a power of two multiple. If the mask is
12603 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12611 {
12617 {
12620 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12622 {
12626 {
12629 }
12630 }
12632 }
12633 }
12638 /* It is impossible to prove if op0 - op1 is multiple of bottom
12639 precisely, so be conservative here checking if both op0 and op1
12640 are multiple of bottom. Note we check the second operand first
12641 since it's usually simpler. */
12646 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12647 as op0 - 3 if the expression has unsigned type. For example,
12648 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12658 {
12660 /* const_binop may not detect overflow correctly,
12661 so check for it explicitly here. */
12669 }
12673 /* Can't handle conversions from non-integral or wider integral type. */
12679 /* fall through */
12696 SIGNED);
12702 {
12705 /* Check for special cases to see if top is defined as multiple
12706 of bottom:
12708 top = (X & ~(bottom - 1) ; bottom is power of 2
12710 or
12712 Y = X % bottom
12713 top = X - Y. */
12732 }
12734 /* fall through */
12742 }
12743 }
12745 #define tree_expr_nonnegative_warnv_p(X, Y) \
12748 #define RECURSE(X) \
12749 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12751 /* Return true if CODE or TYPE is known to be non-negative. */
12753 static bool
12755 {
12758 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12759 have a signed:1 type (where the value is -1 and 0). */
12762 }
12764 /* Return true if (CODE OP0) is known to be non-negative. If the return
12765 value is based on the assumption that signed overflow is undefined,
12766 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12767 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12769 bool
12772 {
12777 {
12779 /* We can't return 1 if flag_wrapv is set because
12780 ABS_EXPR<INT_MIN> = INT_MIN. */
12784 {
12787 }
12795 CASE_CONVERT:
12796 {
12801 {
12805 {
12809 }
12810 }
12812 {
12818 }
12819 }
12824 }
12826 /* We don't know sign of `t', so be conservative and return false. */
12828 }
12830 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12831 value is based on the assumption that signed overflow is undefined,
12832 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12833 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12835 bool
12839 {
12844 {
12850 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12851 both unsigned and at least 2 bits shorter than the result. */
12855 {
12860 {
12864 }
12865 }
12870 {
12871 /* x * x is always non-negative for floating point x
12872 or without overflow. */
12875 {
12880 }
12881 }
12883 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12884 both unsigned and their total bits is shorter than the result. */
12888 {
12907 {
12917 }
12918 }
12945 }
12947 /* We don't know sign of `t', so be conservative and return false. */
12949 }
12951 /* Return true if T is known to be non-negative. If the return
12952 value is based on the assumption that signed overflow is undefined,
12953 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12954 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12956 bool
12958 {
12963 {
12977 /* Limit the depth of recursion to avoid quadratic behavior.
12978 This is expected to catch almost all occurrences in practice.
12979 If this code misses important cases that unbounded recursion
12980 would not, passes that need this information could be revised
12981 to provide it through dataflow propagation. */
12989 }
12990 }
12992 /* Return true if T is known to be non-negative. If the return
12993 value is based on the assumption that signed overflow is undefined,
12994 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12995 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12997 bool
13000 {
13002 {
13003 CASE_CFN_ACOS:
13004 CASE_CFN_ACOSH:
13005 CASE_CFN_CABS:
13006 CASE_CFN_COSH:
13007 CASE_CFN_ERFC:
13008 CASE_CFN_EXP:
13009 CASE_CFN_EXP10:
13010 CASE_CFN_EXP2:
13011 CASE_CFN_FABS:
13012 CASE_CFN_FDIM:
13013 CASE_CFN_HYPOT:
13014 CASE_CFN_POW10:
13015 CASE_CFN_FFS:
13016 CASE_CFN_PARITY:
13017 CASE_CFN_POPCOUNT:
13018 CASE_CFN_CLZ:
13019 CASE_CFN_CLRSB:
13022 /* Always true. */
13025 CASE_CFN_SQRT:
13026 CASE_CFN_SQRT_FN:
13027 /* sqrt(-0.0) is -0.0. */
13032 CASE_CFN_ASINH:
13033 CASE_CFN_ATAN:
13034 CASE_CFN_ATANH:
13035 CASE_CFN_CBRT:
13036 CASE_CFN_CEIL:
13037 CASE_CFN_CEIL_FN:
13038 CASE_CFN_ERF:
13039 CASE_CFN_EXPM1:
13040 CASE_CFN_FLOOR:
13041 CASE_CFN_FLOOR_FN:
13042 CASE_CFN_FMOD:
13043 CASE_CFN_FREXP:
13044 CASE_CFN_ICEIL:
13045 CASE_CFN_IFLOOR:
13046 CASE_CFN_IRINT:
13047 CASE_CFN_IROUND:
13048 CASE_CFN_LCEIL:
13049 CASE_CFN_LDEXP:
13050 CASE_CFN_LFLOOR:
13051 CASE_CFN_LLCEIL:
13052 CASE_CFN_LLFLOOR:
13053 CASE_CFN_LLRINT:
13054 CASE_CFN_LLROUND:
13055 CASE_CFN_LRINT:
13056 CASE_CFN_LROUND:
13057 CASE_CFN_MODF:
13058 CASE_CFN_NEARBYINT:
13059 CASE_CFN_NEARBYINT_FN:
13060 CASE_CFN_RINT:
13061 CASE_CFN_RINT_FN:
13062 CASE_CFN_ROUND:
13063 CASE_CFN_ROUND_FN:
13064 CASE_CFN_SCALB:
13065 CASE_CFN_SCALBLN:
13066 CASE_CFN_SCALBN:
13067 CASE_CFN_SIGNBIT:
13068 CASE_CFN_SIGNIFICAND:
13069 CASE_CFN_SINH:
13070 CASE_CFN_TANH:
13071 CASE_CFN_TRUNC:
13072 CASE_CFN_TRUNC_FN:
13073 /* True if the 1st argument is nonnegative. */
13076 CASE_CFN_FMAX:
13077 CASE_CFN_FMAX_FN:
13078 /* True if the 1st OR 2nd arguments are nonnegative. */
13081 CASE_CFN_FMIN:
13082 CASE_CFN_FMIN_FN:
13083 /* True if the 1st AND 2nd arguments are nonnegative. */
13086 CASE_CFN_COPYSIGN:
13087 CASE_CFN_COPYSIGN_FN:
13088 /* True if the 2nd argument is nonnegative. */
13091 CASE_CFN_POWI:
13092 /* True if the 1st argument is nonnegative or the second
13093 argument is an even integer. */
13099 CASE_CFN_POW:
13100 /* True if the 1st argument is nonnegative or the second
13101 argument is an even integer valued real. */
13103 {
13104 REAL_VALUE_TYPE c;
13105 HOST_WIDE_INT n;
13110 {
13111 REAL_VALUE_TYPE cint;
13115 }
13116 }
13121 }
13123 }
13125 /* Return true if T is known to be non-negative. If the return
13126 value is based on the assumption that signed overflow is undefined,
13127 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13128 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13130 static bool
13132 {
13138 {
13140 {
13144 /* If the initializer is non-void, then it's a normal expression
13145 that will be assigned to the slot. */
13149 /* Otherwise, the initializer sets the slot in some way. One common
13150 way is an assignment statement at the end of the initializer. */
13152 {
13160 else
13162 }
13168 }
13171 {
13177 arg0,
13178 arg1,
13180 }
13193 }
13194 }
13196 #undef RECURSE
13197 #undef tree_expr_nonnegative_warnv_p
13199 /* Return true if T is known to be non-negative. If the return
13200 value is based on the assumption that signed overflow is undefined,
13201 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13202 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13204 bool
13206 {
13213 {
13235 }
13238 {
13264 }
13265 }
13267 /* Return true if `t' is known to be non-negative. Handle warnings
13268 about undefined signed overflow. */
13270 bool
13272 {
13279 "determining that expression is always "
13281 WARN_STRICT_OVERFLOW_MISC);
13283 }
13286 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13287 For floating point we further ensure that T is not denormal.
13288 Similar logic is present in nonzero_address in rtlanal.h.
13290 If the return value is based on the assumption that signed overflow
13291 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13292 change *STRICT_OVERFLOW_P. */
13294 bool
13297 {
13299 {
13302 strict_overflow_p);
13305 {
13311 strict_overflow_p));
13312 }
13317 strict_overflow_p);
13321 }
13324 }
13326 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13327 For floating point we further ensure that T is not denormal.
13328 Similar logic is present in nonzero_address in rtlanal.h.
13330 If the return value is based on the assumption that signed overflow
13331 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13332 change *STRICT_OVERFLOW_P. */
13334 bool
13336 tree type,
13337 tree op0,
13339 {
13342 {
13346 {
13347 /* With the presence of negative values it is hard
13348 to say something. */
13355 /* One of operands must be positive and the other non-negative. */
13356 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13357 overflows, on a twos-complement machine the sum of two
13358 nonnegative numbers can never be zero. */
13360 strict_overflow_p)
13362 strict_overflow_p));
13363 }
13368 {
13370 strict_overflow_p)
13372 strict_overflow_p))
13373 {
13376 }
13377 }
13386 {
13389 }
13396 {
13400 /* When both operands are nonzero, then MAX must be too. */
13402 strict_overflow_p))
13405 /* MAX where operand 0 is positive is positive. */
13407 strict_overflow_p);
13408 }
13409 /* MAX where operand 1 is positive is positive. */
13414 {
13418 }
13423 strict_overflow_p)
13425 strict_overflow_p));
13429 }
13432 }
13434 /* Return true when T is an address and is known to be nonzero.
13435 For floating point we further ensure that T is not denormal.
13436 Similar logic is present in nonzero_address in rtlanal.h.
13438 If the return value is based on the assumption that signed overflow
13439 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13440 change *STRICT_OVERFLOW_P. */
13442 bool
13444 {
13447 {
13452 {
13464 /* For objects in symbol table check if we know they are non-zero.
13465 Don't do anything for variables and functions before symtab is built;
13466 it is quite possible that they will be declared weak later. */
13471 /* Constants are never weak. */
13476 }
13484 {
13488 }
13498 }
13500 }
13502 #define integer_valued_real_p(X) \
13505 #define RECURSE(X) \
13506 ((integer_valued_real_p) (X, depth + 1))
13508 /* Return true if the floating point result of (CODE OP0) has an
13509 integer value. We also allow +Inf, -Inf and NaN to be considered
13510 integer values. Return false for signaling NaN.
13512 DEPTH is the current nesting depth of the query. */
13514 bool
13516 {
13518 {
13525 CASE_CONVERT:
13526 {
13533 }
13537 }
13539 }
13541 /* Return true if the floating point result of (CODE OP0 OP1) has an
13542 integer value. We also allow +Inf, -Inf and NaN to be considered
13543 integer values. Return false for signaling NaN.
13545 DEPTH is the current nesting depth of the query. */
13547 bool
13549 {
13551 {
13561 }
13563 }
13565 /* Return true if the floating point result of calling FNDECL with arguments
13566 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13567 considered integer values. Return false for signaling NaN. If FNDECL
13568 takes fewer than 2 arguments, the remaining ARGn are null.
13570 DEPTH is the current nesting depth of the query. */
13572 bool
13574 {
13576 {
13577 CASE_CFN_CEIL:
13578 CASE_CFN_CEIL_FN:
13579 CASE_CFN_FLOOR:
13580 CASE_CFN_FLOOR_FN:
13581 CASE_CFN_NEARBYINT:
13582 CASE_CFN_NEARBYINT_FN:
13583 CASE_CFN_RINT:
13584 CASE_CFN_RINT_FN:
13585 CASE_CFN_ROUND:
13586 CASE_CFN_ROUND_FN:
13587 CASE_CFN_TRUNC:
13588 CASE_CFN_TRUNC_FN:
13591 CASE_CFN_FMIN:
13592 CASE_CFN_FMIN_FN:
13593 CASE_CFN_FMAX:
13594 CASE_CFN_FMAX_FN:
13599 }
13601 }
13603 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13604 has an integer value. We also allow +Inf, -Inf and NaN to be
13605 considered integer values. Return false for signaling NaN.
13607 DEPTH is the current nesting depth of the query. */
13609 bool
13611 {
13613 {
13621 /* Limit the depth of recursion to avoid quadratic behavior.
13622 This is expected to catch almost all occurrences in practice.
13623 If this code misses important cases that unbounded recursion
13624 would not, passes that need this information could be revised
13625 to provide it through dataflow propagation. */
13629 depth));
13633 }
13635 }
13637 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13638 has an integer value. We also allow +Inf, -Inf and NaN to be
13639 considered integer values. Return false for signaling NaN.
13641 DEPTH is the current nesting depth of the query. */
13643 static bool
13645 {
13647 {
13658 }
13660 }
13662 #undef RECURSE
13663 #undef integer_valued_real_p
13665 /* Return true if the floating point expression T has an integer value.
13666 We also allow +Inf, -Inf and NaN to be considered integer values.
13667 Return false for signaling NaN.
13669 DEPTH is the current nesting depth of the query. */
13671 bool
13673 {
13679 {
13695 }
13698 {
13704 {
13713 }
13717 }
13718 }
13720 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13721 attempt to fold the expression to a constant without modifying TYPE,
13722 OP0 or OP1.
13724 If the expression could be simplified to a constant, then return
13725 the constant. If the expression would not be simplified to a
13726 constant, then return NULL_TREE. */
13728 tree
13730 {
13733 }
13735 /* Given the components of a unary expression CODE, TYPE and OP0,
13736 attempt to fold the expression to a constant without modifying
13737 TYPE or OP0.
13739 If the expression could be simplified to a constant, then return
13740 the constant. If the expression would not be simplified to a
13741 constant, then return NULL_TREE. */
13743 tree
13745 {
13748 }
13750 /* If EXP represents referencing an element in a constant string
13751 (either via pointer arithmetic or array indexing), return the
13752 tree representing the value accessed, otherwise return NULL. */
13754 tree
13756 {
13760 {
13762 tree index;
13763 tree string;
13768 else
13769 {
13773 /* Optimize the special-case of a zero lower bound.
13775 We convert the low_bound to sizetype to avoid some problems
13776 with constant folding. (E.g. suppose the lower bound is 1,
13777 and its mode is QI. Without the conversion,l (ARRAY
13778 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13779 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13785 }
13787 scalar_int_mode char_mode;
13799 }
13801 }
13803 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13804 an integer constant, real, or fixed-point constant.
13806 TYPE is the type of the result. */
13808 static tree
13810 {
13814 {
13820 {
13821 FIXED_VALUE_TYPE f;
13826 /* Propagate overflow flags. */
13830 }
13834 {
13841 }
13844 }
13847 }
13849 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13850 an integer constant or real constant.
13852 TYPE is the type of the result. */
13854 tree
13856 {
13860 {
13862 {
13863 /* If the value is unsigned or non-negative, then the absolute value
13864 is the same as the ordinary value. */
13868 ;
13870 /* If the value is negative, then the absolute value is
13871 its negation. */
13872 else
13875 /* Force to the destination type, set TREE_OVERFLOW for signed
13876 TYPE only. */
13878 }
13884 else
13890 }
13893 }
13895 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13896 constant. TYPE is the type of the result. */
13898 static tree
13900 {
13904 }
13906 /* Given CODE, a relational operator, the target type, TYPE and two
13907 constant operands OP0 and OP1, return the result of the
13908 relational operation. If the result is not a compile time
13909 constant, then return NULL_TREE. */
13911 static tree
13913 {
13916 /* From here on, the only cases we handle are when the result is
13917 known to be a constant. */
13920 {
13924 /* Handle the cases where either operand is a NaN. */
13926 {
13928 {
13956 }
13959 }
13962 }
13965 {
13969 }
13971 /* Handle equality/inequality of complex constants. */
13973 {
13984 else
13986 }
13989 {
13991 {
13992 /* Have vector comparison with scalar boolean result. */
14000 {
14008 }
14010 }
14011 tree_vector_builder elts;
14016 {
14029 }
14032 }
14034 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14036 To compute GT, swap the arguments and do LT.
14037 To compute GE, do LT and invert the result.
14038 To compute LE, swap the arguments, do LT and invert the result.
14039 To compute NE, do EQ and invert the result.
14041 Therefore, the code below must handle only EQ and LT. */
14044 {
14047 }
14049 /* Note that it is safe to invert for real values here because we
14050 have already handled the one case that it matters. */
14054 {
14057 }
14059 /* Compute a result for LT or EQ if args permit;
14060 Otherwise return T. */
14062 {
14065 else
14067 }
14068 else
14074 }
14076 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14077 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14078 itself. */
14080 tree
14082 {
14083 /* If the expression does not have side effects then we don't have to wrap
14084 it with a cleanup point expression. */
14088 /* If the expression is a return, check to see if the expression inside the
14089 return has no side effects or the right hand side of the modify expression
14090 inside the return. If either don't have side effects set we don't need to
14091 wrap the expression in a cleanup point expression. Note we don't check the
14092 left hand side of the modify because it should always be a return decl. */
14094 {
14101 }
14104 }
14106 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14107 of an indirection through OP0, or NULL_TREE if no simplification is
14108 possible. */
14110 tree
14112 {
14114 tree subtype;
14115 poly_uint64 const_op01;
14124 {
14128 /* *&CONST_DECL -> to the value of the const decl. */
14131 /* *&p => p; make sure to handle *&"str"[cst] here. */
14133 {
14137 else
14139 }
14140 /* *(foo *)&fooarray => fooarray[0] */
14143 && (!in_gimple_form
14145 {
14155 }
14156 /* *(foo *)&complexfoo => __real__ complexfoo */
14160 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14163 {
14167 index);
14168 }
14169 }
14173 {
14179 {
14180 tree op00type;
14184 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14187 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14188 but we want to treat offsets with MSB set as negative.
14189 For the code below negative offsets are invalid and
14190 TYPE_SIZE of the element is something unsigned, so
14191 check whether op01 fits into poly_int64, which implies
14192 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14193 then just use poly_uint64 because we want to treat the
14194 value as unsigned. */
14196 {
14198 poly_uint64 max_offset
14202 {
14207 }
14208 }
14209 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14212 {
14214 const_op01))
14216 }
14217 /* ((foo *)&fooarray)[1] => fooarray[1] */
14220 {
14229 {
14234 }
14235 }
14236 }
14237 }
14239 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14242 && (!in_gimple_form
14244 {
14245 tree type_domain;
14255 NULL_TREE);
14256 }
14259 }
14261 /* Builds an expression for an indirection through T, simplifying some
14262 cases. */
14264 tree
14266 {
14274 }
14276 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14278 tree
14280 {
14285 else
14287 }
14289 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14290 whose result is ignored. The type of the returned tree need not be
14291 the same as the original expression. */
14293 tree
14295 {
14301 {
14312 else
14318 {
14334 }
14339 }
14340 }
14342 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14344 tree
14346 {
14352 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14353 have to do anything. Only do this when we are not given a const,
14354 because in that case, this check is more expensive than just
14355 doing it. */
14357 {
14362 }
14364 /* If divisor is a power of two, simplify this to bit manipulation. */
14366 {
14368 {
14382 }
14383 else
14384 {
14385 tree t;
14391 }
14392 }
14393 else
14394 {
14399 }
14402 }
14404 /* Likewise, but round down. */
14406 tree
14408 {
14415 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14416 have to do anything. Only do this when we are not given a const,
14417 because in that case, this check is more expensive than just
14418 doing it. */
14420 {
14425 }
14427 /* If divisor is a power of two, simplify this to bit manipulation. */
14429 {
14430 tree t;
14434 }
14435 else
14436 {
14441 }
14444 }
14446 /* Returns the pointer to the base of the object addressed by EXP and
14447 extracts the information about the offset of the access, storing it
14448 to PBITPOS and POFFSET. */
14450 static tree
14453 {
14454 tree core;
14455 machine_mode mode;
14457 poly_int64 bitsize;
14461 {
14466 }
14468 {
14474 {
14475 poly_offset_int tem
14481 }
14482 }
14483 else
14484 {
14488 }
14491 }
14493 /* Returns true if addresses of E1 and E2 differ by a constant, false
14494 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14496 bool
14498 {
14513 {
14523 }
14525 {
14526 /* If only one of the offsets is non-constant, the difference cannot
14527 be a constant. */
14529 }
14530 else
14535 }
14537 /* Return OFF converted to a pointer offset type suitable as offset for
14538 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14539 tree
14541 {
14543 }
14545 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14546 tree
14548 {
14551 }
14553 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14554 tree
14556 {
14559 }
14561 /* Return a pointer P to a NUL-terminated string representing the sequence
14562 of constant characters referred to by SRC (or a subsequence of such
14563 characters within it if SRC is a reference to a string plus some
14564 constant offset). If STRLEN is non-null, store the number of bytes
14565 in the string constant including the terminating NUL char. *STRLEN is
14566 typically strlen(P) + 1 in the absence of embedded NUL characters. */
14570 {
14571 tree offset_node;
14572 tree mem_size;
14583 {
14586 else
14588 }
14593 /* STRING_LENGTH is the size of the string literal, including any
14594 embedded NULs. STRING_SIZE is the size of the array the string
14595 literal is stored in. */
14599 /* Ideally this would turn into a gcc_checking_assert over time. */
14605 /* Ideally this would turn into a gcc_checking_assert over time. */
14614 {
14615 /* Compute and store the length of the substring at OFFSET.
14616 All offsets past the initial length refer to null strings. */
14619 else
14621 }
14622 else
14623 {
14625 /* Support only properly NUL-terminated single byte strings. */
14630 }
14633 }
14635 /* Given a tree T, compute which bits in T may be nonzero. */
14637 wide_int
14639 {
14641 {
14659 CASE_CONVERT:
14665 {
14670 }
14674 {
14682 }
14686 {
14694 }
14698 }
14701 }
14703 #if CHECKING_P
14707 /* Helper functions for writing tests of folding trees. */
14709 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14711 static void
14713 tree constant)
14714 {
14716 }
14718 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14719 wrapping WRAPPED_EXPR. */
14721 static void
14723 tree wrapped_expr)
14724 {
14729 }
14731 /* Verify that various arithmetic binary operations are folded
14732 correctly. */
14734 static void
14736 {
14742 /* Addition. */
14743 /* 1 <-- (0 + 1) */
14745 one);
14747 one);
14749 /* (nonlvalue)x <-- (x + 0) */
14751 x);
14753 /* Subtraction. */
14754 /* 0 <-- (x - x) */
14756 zero);
14758 x);
14760 /* Multiplication. */
14761 /* 0 <-- (x * 0) */
14763 zero);
14765 /* (nonlvalue)x <-- (x * 1) */
14767 x);
14768 }
14770 /* Verify that various binary operations on vectors are folded
14771 correctly. */
14773 static void
14775 {
14781 /* Verify equality tests that return a scalar boolean result. */
14787 }
14789 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14791 static void
14793 {
14796 /* This will be 1 if VEC_MODE isn't a vector mode. */
14803 }
14805 /* Run all of the selftests within this file. */
14807 void
14809 {
14813 }