| blob | b318fc7705fe50e50d415c89598810203b6c45a6 |
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 or signedness mismatch occurs
6013 between the left and right sides. */
6015 {
6018 /* Make sure the two fields on the right
6019 correspond to the left without being swapped. */
6036 {
6039 }
6048 /* Make a mask that corresponds to both fields being compared.
6049 Do this for both items being compared. If the operands are the
6050 same size and the bits being compared are in the same position
6051 then we can do this by masking both and comparing the masked
6052 results. */
6059 {
6073 }
6075 /* There is still another way we can do something: If both pairs of
6076 fields being compared are adjacent, we may be able to make a wider
6077 field containing them both.
6079 Note that we still must mask the lhs/rhs expressions. Furthermore,
6080 the mask must be shifted to account for the shift done by
6081 make_bit_field_ref. */
6090 {
6091 tree type;
6107 /* Convert to the smaller type before masking out unwanted bits. */
6110 {
6112 {
6116 }
6118 {
6122 }
6123 }
6132 }
6135 }
6137 /* Handle the case of comparisons with constants. If there is something in
6138 common between the masks, those bits of the constants must be the same.
6139 If not, the condition is always false. Test for this to avoid generating
6140 incorrect code below. */
6145 {
6147 {
6150 }
6151 else
6152 {
6155 }
6156 }
6161 /* Construct the expression we will return. First get the component
6162 reference we will make. Unless the mask is all ones the width of
6163 that field, perform the mask operation. Then compare with the
6164 merged constant. */
6175 }
6176 \f
6177 /* T is an integer expression that is being multiplied, divided, or taken a
6178 modulus (CODE says which and what kind of divide or modulus) by a
6179 constant C. See if we can eliminate that operation by folding it with
6180 other operations already in T. WIDE_TYPE, if non-null, is a type that
6181 should be used for the computation if wider than our type.
6183 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
6184 (X * 2) + (Y * 4). We must, however, be assured that either the original
6185 expression would not overflow or that overflow is undefined for the type
6186 in the language in question.
6188 If we return a non-null expression, it is an equivalent form of the
6189 original computation, but need not be in the original type.
6191 We set *STRICT_OVERFLOW_P to true if the return values depends on
6192 signed overflow being undefined. Otherwise we do not change
6193 *STRICT_OVERFLOW_P. */
6195 static tree
6198 {
6199 /* To avoid exponential search depth, refuse to allow recursion past
6200 three levels. Beyond that (1) it's highly unlikely that we'll find
6201 something interesting and (2) we've probably processed it before
6202 when we built the inner expression. */
6205 tree ret;
6210 depth++;
6212 depth--;
6215 }
6217 static tree
6220 {
6232 /* Don't deal with constants of zero here; they confuse the code below. */
6242 /* Note that we need not handle conditional operations here since fold
6243 already handles those cases. So just do arithmetic here. */
6245 {
6247 /* For a constant, we can always simplify if we are a multiply
6248 or (for divide and modulus) if it is a multiple of our constant. */
6252 {
6255 /* If the multiplication overflowed, we lost information on it.
6256 See PR68142 and PR69845. */
6260 }
6264 /* If op0 is an expression ... */
6270 /* ... and has wrapping overflow, and its type is smaller
6271 than ctype, then we cannot pass through as widening. */
6276 /* ... or this is a truncation (t is narrower than op0),
6277 then we cannot pass through this narrowing. */
6280 /* ... or signedness changes for division or modulus,
6281 then we cannot pass through this conversion. */
6285 /* ... or has undefined overflow while the converted to
6286 type has not, we cannot do the operation in the inner type
6287 as that would introduce undefined overflow. */
6293 /* Pass the constant down and see if we can make a simplification. If
6294 we can, replace this expression with the inner simplification for
6295 possible later conversion to our or some other type. */
6306 /* If widening the type changes it from signed to unsigned, then we
6307 must avoid building ABS_EXPR itself as unsigned. */
6309 {
6313 {
6316 }
6318 }
6319 /* If the constant is negative, we cannot simplify this. */
6322 /* FALLTHROUGH */
6324 /* For division and modulus, type can't be unsigned, as e.g.
6325 (-(x / 2U)) / 2U isn't equal to -((x / 2U) / 2U) for x >= 2.
6326 For signed types, even with wrapping overflow, this is fine. */
6335 /* If widening the type changes the signedness, then we can't perform
6336 this optimization as that changes the result. */
6340 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
6346 {
6353 }
6357 /* If the second operand is constant, this is a multiplication
6358 or floor division, by a power of two, so we can treat it that
6359 way unless the multiplier or divisor overflows. Signed
6360 left-shift overflow is implementation-defined rather than
6361 undefined in C90, so do not convert signed left shift into
6362 multiplication. */
6365 /* const_binop may not detect overflow correctly,
6366 so check for it explicitly here. */
6375 ctype,
6377 t1),
6382 /* See if we can eliminate the operation on both sides. If we can, we
6383 can return a new PLUS or MINUS. If we can't, the only remaining
6384 cases where we can do anything are if the second operand is a
6385 constant. */
6392 /* If not multiplication, we can only do this if both operands
6393 are divisible by c. */
6396 {
6401 }
6403 /* If this was a subtraction, negate OP1 and set it to be an addition.
6404 This simplifies the logic below. */
6406 {
6408 /* If OP1 was not easily negatable, the constant may be OP0. */
6410 {
6413 }
6414 }
6419 /* If either OP1 or C are negative, this optimization is not safe for
6420 some of the division and remainder types while for others we need
6421 to change the code. */
6423 {
6431 }
6433 /* If it's a multiply or a division/modulus operation of a multiple
6434 of our constant, do the operation and verify it doesn't overflow. */
6438 {
6441 /* We allow the constant to overflow with wrapping semantics. */
6445 }
6446 else
6449 /* If we have an unsigned type, we cannot widen the operation since it
6450 will change the result if the original computation overflowed. */
6454 /* The last case is if we are a multiply. In that case, we can
6455 apply the distributive law to commute the multiply and addition
6456 if the multiplication of the constants doesn't overflow
6457 and overflow is defined. With undefined overflow
6458 op0 * c might overflow, while (op0 + orig_op1) * c doesn't. */
6464 op1);
6469 /* We have a special case here if we are doing something like
6470 (C * 8) % 4 since we know that's zero. */
6473 /* If the multiplication can overflow we cannot optimize this. */
6478 {
6481 }
6483 /* ... fall through ... */
6487 /* If we can extract our operation from the LHS, do so and return a
6488 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
6489 do something only if the second operand is a constant. */
6505 /* If these are the same operation types, we can associate them
6506 assuming no overflow. */
6508 {
6523 }
6525 /* If these operations "cancel" each other, we have the main
6526 optimizations of this pass, which occur when either constant is a
6527 multiple of the other, in which case we replace this with either an
6528 operation or CODE or TCODE.
6530 If we have an unsigned type, we cannot do this since it will change
6531 the result if the original computation overflowed. */
6538 {
6541 {
6548 }
6551 {
6558 }
6559 }
6564 }
6567 }
6568 \f
6569 /* Return a node which has the indicated constant VALUE (either 0 or
6570 1 for scalars or {-1,-1,..} or {0,0,...} for vectors),
6571 and is of the indicated TYPE. */
6573 tree
6575 {
6584 else
6586 }
6589 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6590 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6591 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6592 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6593 COND is the first argument to CODE; otherwise (as in the example
6594 given here), it is the second argument. TYPE is the type of the
6595 original expression. Return NULL_TREE if no simplification is
6596 possible. */
6598 static tree
6603 {
6611 /* Do not move possibly trapping operations into the conditional as this
6612 pessimizes code and causes gimplification issues when applied late. */
6620 {
6624 /* If this operand throws an expression, then it does not make
6625 sense to try to perform a logical or arithmetic operation
6626 involving it. */
6631 }
6634 {
6639 }
6640 else
6641 /* Detect the case of mixing vector and scalar types - bail out. */
6647 /* This transformation is only worthwhile if we don't have to wrap ARG
6648 in a SAVE_EXPR and the operation can be simplified without recursing
6649 on at least one of the branches once its pushed inside the COND_EXPR. */
6658 {
6662 else
6664 }
6666 {
6670 else
6672 }
6674 /* Check that we have simplified at least one of the branches. */
6679 }
6681 \f
6682 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6684 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6685 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6686 ADDEND is the same as X.
6688 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6689 and finite. The problematic cases are when X is zero, and its mode
6690 has signed zeros. In the case of rounding towards -infinity,
6691 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6692 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6694 bool
6696 {
6700 /* Don't allow the fold with -fsignaling-nans. */
6704 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6708 /* In a vector or complex, we would need to check the sign of all zeros. */
6712 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6716 /* The mode has signed zeros, and we have to honor their sign.
6717 In this situation, there is only one case we can return true for.
6718 X - 0 is the same as X unless rounding towards -infinity is
6719 supported. */
6721 }
6723 /* Subroutine of match.pd that optimizes comparisons of a division by
6724 a nonzero integer constant against an integer constant, i.e.
6725 X/C1 op C2.
6727 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6728 GE_EXPR or LE_EXPR. ARG01 and ARG1 must be a INTEGER_CST. */
6730 enum tree_code
6733 {
6738 /* We have to do this the hard way to detect unsigned overflow.
6739 prod = int_const_binop (MULT_EXPR, c1, c2); */
6745 {
6749 /* Likewise *hi = int_const_binop (PLUS_EXPR, prod, tmp). */
6752 }
6754 {
6757 {
6776 }
6777 }
6778 else
6779 {
6780 /* A negative divisor reverses the relational operators. */
6785 {
6804 }
6805 }
6818 }
6821 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6822 equality/inequality test, then return a simplified form of the test
6823 using a sign testing. Otherwise return NULL. TYPE is the desired
6824 result type. */
6826 static tree
6829 tree result_type)
6830 {
6831 /* If this is testing a single bit, we can optimize the test. */
6835 {
6836 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6837 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6841 /* This is only a win if casting to a signed type is cheap,
6842 i.e. when arg00's type is not a partial mode. */
6844 {
6847 result_type,
6850 }
6851 }
6854 }
6856 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6857 equality/inequality test, then return a simplified form of
6858 the test using shifts and logical operations. Otherwise return
6859 NULL. TYPE is the desired result type. */
6861 tree
6864 {
6865 /* If this is testing a single bit, we can optimize the test. */
6869 {
6878 /* First, see if we can fold the single bit test into a sign-bit
6879 test. */
6881 result_type);
6885 /* Otherwise we have (A & C) != 0 where C is a single bit,
6886 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6887 Similarly for (A & C) == 0. */
6889 /* If INNER is a right shift of a constant and it plus BITNUM does
6890 not overflow, adjust BITNUM and INNER. */
6896 {
6899 }
6901 /* If we are going to be able to omit the AND below, we must do our
6902 operations as unsigned. If we must use the AND, we have a choice.
6903 Normally unsigned is faster, but for some machines signed is. */
6921 /* Put the AND last so it can combine with more things. */
6924 /* Make sure to return the proper type. */
6928 }
6930 }
6932 /* Test whether it is preferable two swap two operands, ARG0 and
6933 ARG1, for example because ARG0 is an integer constant and ARG1
6934 isn't. */
6936 bool
6938 {
6952 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6953 for commutative and comparison operators. Ensuring a canonical
6954 form allows the optimizers to find additional redundancies without
6955 having to explicitly check for both orderings. */
6961 /* Put SSA_NAMEs last. */
6967 /* Put variables last. */
6974 }
6977 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6978 means A >= Y && A != MAX, but in this case we know that
6979 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6981 static tree
6983 {
6990 else
6999 {
7002 }
7004 {
7007 }
7008 else
7015 {
7016 /* Convert the pointer types into integer before taking the difference. */
7020 }
7021 else
7028 }
7030 /* Fold a sum or difference of at least one multiplication.
7031 Returns the folded tree or NULL if no simplification could be made. */
7033 static tree
7036 {
7040 /* (A * C) +- (B * C) -> (A+-B) * C.
7041 (A * C) +- A -> A * (C+-1).
7042 We are most concerned about the case where C is a constant,
7043 but other combinations show up during loop reduction. Since
7044 it is not difficult, try all four possibilities. */
7047 {
7050 }
7052 {
7055 }
7056 else
7057 {
7058 /* We cannot generate constant 1 for fract. */
7063 }
7065 {
7068 }
7070 {
7072 /* As we canonicalize A - 2 to A + -2 get rid of that sign for
7073 the purpose of this canonicalization. */
7077 {
7080 }
7081 else
7083 }
7084 else
7085 {
7086 /* We cannot generate constant 1 for fract. */
7091 }
7094 /* Prefer factoring a common non-constant. */
7104 /* No identical multiplicands; see if we can find a common
7105 power-of-two factor in non-power-of-two multiplies. This
7106 can help in multi-dimensional array access. */
7109 {
7112 tree maybe_same;
7116 /* Move min of absolute values to int11. */
7118 {
7123 }
7124 else
7128 /* The remainder should not be a constant, otherwise we
7129 end up folding i * 4 + 2 to (i * 2 + 1) * 2 which has
7130 increased the number of multiplications necessary. */
7132 {
7140 }
7141 }
7148 /* We are neither factoring zero nor minus one. */
7156 /* Same may be zero and thus the operation 'code' may overflow. Likewise
7157 same may be minus one and thus the multiplication may overflow. Perform
7158 the sum operation in an unsigned type. */
7163 /* If the sum evaluated to a constant that is not -INF the multiplication
7164 cannot overflow. */
7171 /* Do not resort to unsigned multiplication because
7172 we lose the no-overflow property of the expression. */
7174 }
7176 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7177 specified by EXPR into the buffer PTR of length LEN bytes.
7178 Return the number of bytes placed in the buffer, or zero
7179 upon failure. */
7181 static int
7183 {
7195 /* Dry run. */
7201 {
7203 /* Extend EXPR according to TYPE_SIGN if the precision isn't a whole
7204 number of bytes. */
7208 {
7215 else
7217 }
7218 else
7222 }
7224 }
7227 /* Subroutine of native_encode_expr. Encode the FIXED_CST
7228 specified by EXPR into the buffer PTR of length LEN bytes.
7229 Return the number of bytes placed in the buffer, or zero
7230 upon failure. */
7232 static int
7234 {
7238 FIXED_VALUE_TYPE value;
7253 }
7256 /* Subroutine of native_encode_expr. Encode the REAL_CST
7257 specified by EXPR into the buffer PTR of length LEN bytes.
7258 Return the number of bytes placed in the buffer, or zero
7259 upon failure. */
7261 static int
7263 {
7269 /* There are always 32 bits in each long, no matter the size of
7270 the hosts long. We handle floating point representations with
7271 up to 192 bits. */
7280 /* Dry run. */
7289 {
7294 {
7301 else
7303 }
7304 else
7305 {
7308 {
7309 /* Reverse bytes within each long, or within the entire float
7310 if it's smaller than a long (for HFmode). */
7313 }
7314 }
7319 }
7321 }
7323 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7324 specified by EXPR into the buffer PTR of length LEN bytes.
7325 Return the number of bytes placed in the buffer, or zero
7326 upon failure. */
7328 static int
7330 {
7332 tree part;
7346 }
7349 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7350 specified by EXPR into the buffer PTR of length LEN bytes.
7351 Return the number of bytes placed in the buffer, or zero
7352 upon failure. */
7354 static int
7356 {
7367 {
7369 {
7372 }
7383 }
7385 }
7388 /* Subroutine of native_encode_expr. Encode the STRING_CST
7389 specified by EXPR into the buffer PTR of length LEN bytes.
7390 Return the number of bytes placed in the buffer, or zero
7391 upon failure. */
7393 static int
7395 {
7398 /* Wide-char strings are encoded in target byte-order so native
7399 encoding them is trivial. */
7414 {
7417 {
7420 }
7423 }
7424 else
7427 }
7430 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7431 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7432 buffer PTR of length LEN bytes. If PTR is NULL, don't actually store
7433 anything, just do a dry run. If OFF is not -1 then start
7434 the encoding at byte offset OFF and encode at most LEN bytes.
7435 Return the number of bytes placed in the buffer, or zero upon failure. */
7437 int
7439 {
7440 /* We don't support starting at negative offset and -1 is special. */
7445 {
7466 }
7467 }
7470 /* Subroutine of native_interpret_expr. Interpret the contents of
7471 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7472 If the buffer cannot be interpreted, return NULL_TREE. */
7474 static tree
7476 {
7486 }
7489 /* Subroutine of native_interpret_expr. Interpret the contents of
7490 the buffer PTR of length LEN as a FIXED_CST of type TYPE.
7491 If the buffer cannot be interpreted, return NULL_TREE. */
7493 static tree
7495 {
7498 double_int result;
7499 FIXED_VALUE_TYPE fixed_value;
7509 }
7512 /* Subroutine of native_interpret_expr. Interpret the contents of
7513 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7514 If the buffer cannot be interpreted, return NULL_TREE. */
7516 static tree
7518 {
7522 /* There are always 32 bits in each long, no matter the size of
7523 the hosts long. We handle floating point representations with
7524 up to 192 bits. */
7525 REAL_VALUE_TYPE r;
7535 {
7536 /* Both OFFSET and BYTE index within a long;
7537 bitpos indexes the whole float. */
7540 {
7547 else
7549 }
7550 else
7551 {
7554 {
7555 /* Reverse bytes within each long, or within the entire float
7556 if it's smaller than a long (for HFmode). */
7559 }
7560 }
7564 }
7568 }
7571 /* Subroutine of native_interpret_expr. Interpret the contents of
7572 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7573 If the buffer cannot be interpreted, return NULL_TREE. */
7575 static tree
7577 {
7592 }
7595 /* Subroutine of native_interpret_expr. Interpret the contents of
7596 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7597 If the buffer cannot be interpreted, return NULL_TREE. */
7599 static tree
7601 {
7614 {
7619 }
7621 }
7624 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7625 the buffer PTR of length LEN as a constant of type TYPE. For
7626 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7627 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7628 return NULL_TREE. */
7630 tree
7632 {
7634 {
7656 }
7657 }
7659 /* Returns true if we can interpret the contents of a native encoding
7660 as TYPE. */
7662 static bool
7664 {
7666 {
7679 }
7680 }
7683 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7684 TYPE at compile-time. If we're unable to perform the conversion
7685 return NULL_TREE. */
7687 static tree
7689 {
7690 /* We support up to 512-bit values (for V8DFmode). */
7694 /* Check that the host and target are sane. */
7703 }
7705 /* Build an expression for the address of T. Folds away INDIRECT_REF
7706 to avoid confusing the gimplify process. */
7708 tree
7710 {
7711 /* The size of the object is not relevant when talking about its address. */
7716 {
7721 }
7731 {
7736 }
7737 else
7741 }
7743 /* Build an expression for the address of T. */
7745 tree
7747 {
7751 }
7753 /* Fold a unary expression of code CODE and type TYPE with operand
7754 OP0. Return the folded expression if folding is successful.
7755 Otherwise, return NULL_TREE. */
7757 tree
7759 {
7760 tree tem;
7761 tree arg0;
7769 {
7772 {
7773 /* Don't use STRIP_NOPS, because signedness of argument type
7774 matters. */
7776 }
7777 else
7778 {
7779 /* Strip any conversions that don't change the mode. This
7780 is safe for every expression, except for a comparison
7781 expression because its signedness is derived from its
7782 operands.
7784 Note that this is done as an internal manipulation within
7785 the constant folder, in order to find the simplest
7786 representation of the arguments so that their form can be
7787 studied. In any cases, the appropriate type conversions
7788 should be put back in the tree that will get out of the
7789 constant folder. */
7791 }
7794 {
7797 {
7801 }
7802 }
7803 }
7810 {
7817 {
7831 /* If this was a conversion, and all we did was to move into
7832 inside the COND_EXPR, bring it back out. But leave it if
7833 it is a conversion from integer to integer and the
7834 result precision is no wider than a word since such a
7835 conversion is cheap and may be optimized away by combine,
7836 while it couldn't if it were outside the COND_EXPR. Then return
7837 so we don't get into an infinite recursion loop taking the
7838 conversion out and then back in. */
7850 && (INTEGRAL_TYPE_P
7863 }
7864 }
7867 {
7873 CASE_CONVERT:
7877 {
7878 /* If we have (type) (a CMP b) and type is an integral type, return
7879 new expression involving the new type. Canonicalize
7880 (type) (a CMP b) to (a CMP b) ? (type) true : (type) false for
7881 non-integral type.
7882 Do not fold the result as that would not simplify further, also
7883 folding again results in recursions. */
7893 }
7895 /* Handle (T *)&A.B.C for A being of type T and B and C
7896 living at offset zero. This occurs frequently in
7897 C++ upcasting and then accessing the base. */
7901 {
7903 tree offset;
7904 machine_mode mode;
7906 tree base
7910 /* If the reference was to a (constant) zero offset, we can use
7911 the address of the base if it has the same base type
7912 as the result type and the pointer type is unqualified. */
7920 }
7924 /* Detect assigning a bitfield. */
7926 && DECL_BIT_FIELD
7928 {
7929 /* Don't leave an assignment inside a conversion
7930 unless assigning a bitfield. */
7932 /* First do the assignment, then return converted constant. */
7937 }
7939 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7940 constants (if x has signed type, the sign bit cannot be set
7941 in c). This folds extension into the BIT_AND_EXPR.
7942 ??? We don't do it for BOOLEAN_TYPE or ENUMERAL_TYPE because they
7943 very likely don't have maximal range for their precision and this
7944 transformation effectively doesn't preserve non-maximal ranges. */
7948 {
7959 <= HOST_BITS_PER_WIDE_INT
7961 {
7965 cst &= HOST_WIDE_INT_M1U
7969 && !flag_syntax_only
7972 {
7976 }
7977 }
7979 {
7984 }
7985 }
7987 /* Convert (T1)(X p+ Y) into ((T1)X p+ Y), for pointer type, when the new
7988 cast (T1)X will fold away. We assume that this happens when X itself
7989 is a cast. */
7993 {
7997 return fold_build_pointer_plus_loc
7999 }
8001 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
8002 of the same precision, and X is an integer type not narrower than
8003 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
8009 {
8015 }
8017 /* Convert (T1)(X * Y) into (T1)X * (T1)Y if T1 is narrower than the
8018 type of X and Y (integer types only). */
8023 {
8024 /* Be careful not to introduce new overflows. */
8025 tree mult_type;
8028 else
8032 {
8039 }
8040 }
8046 {
8053 }
8064 /* Convert fabs((double)float) into (double)fabsf(float). */
8067 {
8073 targ0));
8074 }
8078 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
8097 /* Note that the operand of this must be an int
8098 and its values must be 0 or 1.
8099 ("true" is a fixed value perhaps depending on the language,
8100 but we don't handle values other than 1 correctly yet.) */
8107 /* Fold *&X to X if X is an lvalue. */
8109 {
8116 }
8122 }
8125 /* If the operation was a conversion do _not_ mark a resulting constant
8126 with TREE_OVERFLOW if the original constant was not. These conversions
8127 have implementation defined behavior and retaining the TREE_OVERFLOW
8128 flag here would confuse later passes such as VRP. */
8129 tree
8132 {
8141 }
8143 /* Fold a binary bitwise/truth expression of code CODE and type TYPE with
8144 operands OP0 and OP1. LOC is the location of the resulting expression.
8145 ARG0 and ARG1 are the NOP_STRIPed results of OP0 and OP1.
8146 Return the folded expression if folding is successful. Otherwise,
8147 return NULL_TREE. */
8148 static tree
8151 {
8152 tree tem;
8154 /* We only do these simplifications if we are optimizing. */
8158 /* Check for things like (A || B) && (A || C). We can convert this
8159 to A || (B && C). Note that either operator can be any of the four
8160 truth and/or operations and the transformation will still be
8161 valid. Also note that we only care about order for the
8162 ANDIF and ORIF operators. If B contains side effects, this
8163 might change the truth-value of A. */
8170 {
8190 /* This case if tricky because we must either have commutative
8191 operators or else A10 must not have side-effects. */
8197 a01);
8198 }
8200 /* See if we can build a range comparison. */
8206 {
8210 }
8214 {
8218 }
8220 /* Check for the possibility of merging component references. If our
8221 lhs is another similar operation, try to merge its rhs with our
8222 rhs. Then try to merge our lhs and rhs. */
8232 && !flag_sanitize_coverage
8237 {
8244 /* Transform ((A AND-IF B) AND[-IF] C) into (A AND-IF (B AND C)),
8245 or ((A OR-IF B) OR[-IF] C) into (A OR-IF (B OR C))
8246 We don't want to pack more than two leafs to a non-IF AND/OR
8247 expression.
8248 If tree-code of left-hand operand isn't an AND/OR-IF code and not
8249 equal to IF-CODE, then we don't want to add right-hand operand.
8250 If the inner right-hand side of left-hand operand has
8251 side-effects, or isn't simple, then we can't add to it,
8252 as otherwise we might destroy if-sequence. */
8255 /* Needed for sequence points to handle trappings, and
8256 side-effects. */
8258 {
8260 arg1);
8262 tem);
8263 }
8264 /* Same as above but for (A AND[-IF] (B AND-IF C)) -> ((A AND B) AND-IF C),
8265 or (A OR[-IF] (B OR-IF C) -> ((A OR B) OR-IF C). */
8268 /* Needed for sequence points to handle trappings, and
8269 side-effects. */
8271 {
8276 }
8277 /* Transform (A AND-IF B) into (A AND B), or (A OR-IF B)
8278 into (A OR B).
8279 For sequence point consistancy, we need to check for trapping,
8280 and side-effects. */
8284 }
8287 }
8289 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8290 by changing CODE to reduce the magnitude of constants involved in
8291 ARG0 of the comparison.
8292 Returns a canonicalized comparison tree if a simplification was
8293 possible, otherwise returns NULL_TREE.
8294 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8295 valid if signed overflow is undefined. */
8297 static tree
8301 {
8306 /* Match A +- CST code arg1. We can change this only if overflow
8307 is undefined. */
8310 /* In principle pointers also have undefined overflow behavior,
8311 but that causes problems elsewhere. */
8318 /* Identify the constant in arg0 and its sign. */
8322 /* Overflowed constants and zero will cause problems. */
8327 /* See if we can reduce the magnitude of the constant in
8328 arg0 by changing the comparison code. */
8329 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8333 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8337 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8341 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8345 else
8349 /* Now build the constant reduced in magnitude. But not if that
8350 would produce one outside of its types range. */
8366 }
8368 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8369 overflow further. Try to decrease the magnitude of constants involved
8370 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8371 and put sole constants at the second argument position.
8372 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8374 static tree
8377 {
8378 tree t;
8383 /* Try canonicalization by simplifying arg0. */
8388 {
8392 }
8394 /* Try canonicalization by simplifying arg1 using the swapped
8395 comparison. */
8403 }
8405 /* Return whether BASE + OFFSET + BITPOS may wrap around the address
8406 space. This is used to avoid issuing overflow warnings for
8407 expressions like &p->x which can not wrap. */
8409 static bool
8411 {
8418 poly_wide_int wi_offset;
8424 else
8429 precision);
8444 /* We can do slightly better for SIZE if we have an ADDR_EXPR of an
8445 array. */
8454 }
8456 /* Return a positive integer when the symbol DECL is known to have
8457 a nonzero address, zero when it's known not to (e.g., it's a weak
8458 symbol), and a negative integer when the symbol is not yet in the
8459 symbol table and so whether or not its address is zero is unknown.
8460 For function local objects always return positive integer. */
8461 static int
8463 {
8468 /* Function local objects are never NULL. */
8476 }
8478 /* Subroutine of fold_binary. This routine performs all of the
8479 transformations that are common to the equality/inequality
8480 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8481 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8482 fold_binary should call fold_binary. Fold a comparison with
8483 tree code CODE and type TYPE with operands OP0 and OP1. Return
8484 the folded comparison or NULL_TREE. */
8486 static tree
8489 {
8499 /* For comparisons of pointers we can decompose it to a compile time
8500 comparison of the base objects and the offsets into the object.
8501 This requires at least one operand being an ADDR_EXPR or a
8502 POINTER_PLUS_EXPR to do more than the operand_equal_p test below. */
8508 {
8511 machine_mode mode;
8515 /* Get base and offset for the access. Strip ADDR_EXPR for
8516 get_inner_reference, but put it back by stripping INDIRECT_REF
8517 off the base object if possible. indirect_baseN will be true
8518 if baseN is not an address but refers to the object itself. */
8521 {
8522 base0
8528 else
8530 }
8532 {
8536 {
8537 base0
8543 else
8545 }
8548 else
8552 {
8559 }
8560 }
8564 {
8565 base1
8571 else
8573 }
8575 {
8579 {
8580 base1
8586 else
8588 }
8591 else
8595 {
8602 }
8603 }
8605 /* If we have equivalent bases we might be able to simplify. */
8609 {
8610 /* We can fold this expression to a constant if the non-constant
8611 offset parts are equal. */
8615 && (equality_code
8616 || (indirect_base0
8619 {
8625 "occur when comparing P +- C1 with "
8627 WARN_STRICT_OVERFLOW_CONDITIONAL);
8630 {
8668 }
8669 }
8670 /* We can simplify the comparison to a comparison of the variable
8671 offset parts if the constant offset parts are equal.
8672 Be careful to use signed sizetype here because otherwise we
8673 mess with array offsets in the wrong way. This is possible
8674 because pointer arithmetic is restricted to retain within an
8675 object and overflow on pointer differences is undefined as of
8676 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8678 && (equality_code
8679 || (indirect_base0
8682 {
8683 /* By converting to signed sizetype we cover middle-end pointer
8684 arithmetic which operates on unsigned pointer types of size
8685 type size and ARRAY_REF offsets which are properly sign or
8686 zero extended from their type in case it is narrower than
8687 sizetype. */
8690 else
8694 else
8701 "occur when comparing P +- C1 with "
8703 WARN_STRICT_OVERFLOW_COMPARISON);
8706 }
8707 }
8708 /* For equal offsets we can simplify to a comparison of the
8709 base addresses. */
8711 && (indirect_base0
8713 && (indirect_base1
8718 {
8724 }
8725 /* Comparison between an ordinary (non-weak) symbol and a null
8726 pointer can be eliminated since such symbols must have a non
8727 null address. In C, relational expressions between pointers
8728 to objects and null pointers are undefined. The results
8729 below follow the C++ rules with the additional property that
8730 every object pointer compares greater than a null pointer.
8731 */
8734 /* Avoid folding references to struct members at offset 0 to
8735 prevent tests like '&ptr->firstmember == 0' from getting
8736 eliminated. When ptr is null, although the -> expression
8737 is strictly speaking invalid, GCC retains it as a matter
8738 of QoI. See PR c/44555. */
8741 && indirect_base0
8742 /* The caller guarantees that when one of the arguments is
8743 constant (i.e., null in this case) it is second. */
8745 {
8747 {
8758 }
8759 }
8760 }
8762 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8763 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8764 the resulting offset is smaller in absolute value than the
8765 original one and has the same sign. */
8774 {
8779 tree cst;
8781 "occur when combining constants around "
8784 /* Put the constant on the side where it doesn't overflow and is
8785 of lower absolute value and of same sign than before. */
8792 {
8795 variable1,
8799 }
8807 {
8813 variable2);
8814 }
8815 }
8821 /* If we are comparing an expression that just has comparisons
8822 of two integer values, arithmetic expressions of those comparisons,
8823 and constants, we can simplify it. There are only three cases
8824 to check: the two values can either be equal, the first can be
8825 greater, or the second can be greater. Fold the expression for
8826 those three values. Since each value must be 0 or 1, we have
8827 eight possibilities, each of which corresponds to the constant 0
8828 or 1 or one of the six possible comparisons.
8830 This handles common cases like (a > b) == 0 but also handles
8831 expressions like ((x > y) - (y > x)) > 0, which supposedly
8832 occur in macroized code. */
8835 {
8839 /* Don't handle degenerate cases here; they should already
8840 have been handled anyway. */
8849 {
8853 /* We can't just pass T to eval_subst in case cval1 or cval2
8854 was the same as ARG1. */
8856 tree high_result
8860 arg1);
8861 tree equal_result
8865 arg1);
8866 tree low_result
8870 arg1);
8872 /* All three of these results should be 0 or 1. Confirm they are.
8873 Then use those values to select the proper code to use. */
8878 {
8879 /* Make a 3-bit mask with the high-order bit being the
8880 value for `>', the next for '=', and the low for '<'. */
8884 {
8886 /* Always false. */
8907 /* Always true. */
8909 }
8912 }
8913 }
8914 }
8917 }
8920 /* Subroutine of fold_binary. Optimize complex multiplications of the
8921 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8922 argument EXPR represents the expression "z" of type TYPE. */
8924 static tree
8926 {
8931 {
8934 }
8936 {
8939 }
8940 else
8941 {
8945 }
8954 }
8957 /* Helper function for fold_vec_perm. Store elements of VECTOR_CST or
8958 CONSTRUCTOR ARG into array ELTS, which has NELTS elements, and return
8959 true if successful. */
8961 static bool
8963 {
8968 {
8971 }
8973 {
8979 else
8981 }
8982 else
8988 }
8990 /* Attempt to fold vector permutation of ARG0 and ARG1 vectors using SEL
8991 selector. Return the folded VECTOR_CST or CONSTRUCTOR if successful,
8992 NULL_TREE otherwise. */
8994 static tree
8996 {
9017 {
9018 HOST_WIDE_INT index;
9024 }
9027 {
9033 }
9034 else
9036 }
9038 /* Try to fold a pointer difference of type TYPE two address expressions of
9039 array references AREF0 and AREF1 using location LOC. Return a
9040 simplified expression for the difference or NULL_TREE. */
9042 static tree
9046 {
9051 /* If the bases are array references as well, recurse. If the bases
9052 are pointer indirections compute the difference of the pointers.
9053 If the bases are equal, we are set. */
9056 && (base_offset
9058 use_pointer_diff)))
9061 && (base_offset
9062 = use_pointer_diff
9072 {
9078 base_offset,
9081 }
9083 }
9085 /* If the real or vector real constant CST of type TYPE has an exact
9086 inverse, return it, else return NULL. */
9088 tree
9090 {
9091 REAL_VALUE_TYPE r;
9092 tree unit_type;
9093 machine_mode mode;
9096 {
9106 {
9110 tree_vector_builder elts;
9115 {
9120 }
9123 }
9127 }
9128 }
9130 /* Mask out the tz least significant bits of X of type TYPE where
9131 tz is the number of trailing zeroes in Y. */
9132 static wide_int
9134 {
9139 }
9141 /* Return true when T is an address and is known to be nonzero.
9142 For floating point we further ensure that T is not denormal.
9143 Similar logic is present in nonzero_address in rtlanal.h.
9145 If the return value is based on the assumption that signed overflow
9146 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
9147 change *STRICT_OVERFLOW_P. */
9149 static bool
9151 {
9155 /* Doing something useful for floating point would need more work. */
9161 {
9164 strict_overflow_p);
9170 strict_overflow_p);
9178 }
9181 {
9184 strict_overflow_p);
9192 strict_overflow_p);
9207 strict_overflow_p);
9211 strict_overflow_p);
9214 {
9226 }
9230 }
9232 }
9234 /* Return true when T is an address and is known to be nonzero.
9235 Handle warnings about undefined signed overflow. */
9237 bool
9239 {
9246 "determining that expression is always "
9248 WARN_STRICT_OVERFLOW_MISC);
9250 }
9252 /* Return true if T is known not to be equal to an integer W. */
9254 bool
9256 {
9258 value_range_type rtype;
9260 {
9269 {
9274 }
9279 /* If T has some known zero bits and W has any of those bits set,
9280 then T is known not to be equal to W. */
9288 }
9289 }
9291 /* Fold a binary expression of code CODE and type TYPE with operands
9292 OP0 and OP1. LOC is the location of the resulting expression.
9293 Return the folded expression if folding is successful. Otherwise,
9294 return NULL_TREE. */
9296 tree
9299 {
9314 /* Strip any conversions that don't change the mode. This is
9315 safe for every expression, except for a comparison expression
9316 because its signedness is derived from its operands. So, in
9317 the latter case, only strip conversions that don't change the
9318 signedness. MIN_EXPR/MAX_EXPR also need signedness of arguments
9319 preserved.
9321 Note that this is done as an internal manipulation within the
9322 constant folder, in order to find the simplest representation
9323 of the arguments so that their form can be studied. In any
9324 cases, the appropriate type conversions should be put back in
9325 the tree that will get out of the constant folder. */
9328 {
9331 }
9332 else
9333 {
9336 }
9338 /* Note that TREE_CONSTANT isn't enough: static var addresses are
9339 constant but we can't do arithmetic on them. */
9341 {
9344 {
9348 }
9349 }
9351 /* If this is a commutative operation, and ARG0 is a constant, move it
9352 to ARG1 to reduce the number of tests below. */
9357 /* Likewise if this is a comparison, and ARG0 is a constant, move it
9358 to ARG1 to reduce the number of tests below. */
9367 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
9369 First check for cases where an arithmetic operation is applied to a
9370 compound, conditional, or comparison operation. Push the arithmetic
9371 operation inside the compound or conditional to see if any folding
9372 can then be done. Convert comparison to conditional for this purpose.
9373 The also optimizes non-constant cases that used to be done in
9374 expand_expr.
9376 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
9377 one of the operands is a comparison and the other is a comparison, a
9378 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
9379 code below would make the expression more complex. Change it to a
9380 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
9381 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9394 {
9398 boolean_type_node,
9406 }
9410 {
9412 {
9417 tem);
9418 }
9420 {
9425 tem);
9426 }
9431 {
9437 }
9442 {
9448 }
9449 }
9452 {
9454 /* MEM[&MEM[p, CST1], CST2] -> MEM[p, CST1 + CST2]. */
9457 {
9463 }
9465 /* MEM[&a.b, CST2] -> MEM[&a, offsetof (a, b) + CST2]. */
9468 {
9469 tree base;
9470 poly_int64 coffset;
9479 }
9484 /* INT +p INT -> (PTR)(INT + INT). Stripping types allows for this. */
9490 arg1),
9492 arg0)));
9498 {
9499 /* X + (X / CST) * -CST is X % CST. */
9504 {
9513 cst0));
9514 }
9515 }
9517 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the same or
9518 one. Make sure the type is not saturating and has the signedness of
9519 the stripped operands, as fold_plusminus_mult_expr will re-associate.
9520 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
9527 {
9531 }
9534 {
9535 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9536 (plus (plus (mult) (mult)) (foo)) so that we can
9537 take advantage of the factoring cases below. */
9546 {
9552 else
9565 parg0),
9567 marg)),
9571 return
9577 parg1)));
9578 }
9579 }
9580 else
9581 {
9582 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9583 to __complex__ ( x, y ). This is not the same for SNaNs or
9584 if signed zeros are involved. */
9588 {
9595 {
9599 {
9605 }
9607 {
9613 }
9614 }
9615 }
9617 /* Convert a + (b*c + d*e) into (a + b*c) + d*e.
9618 We associate floats only if the user has specified
9619 -fassociative-math. */
9623 {
9628 {
9629 tree tree0;
9632 }
9633 }
9634 /* Convert (b*c + d*e) + a into b*c + (d*e +a).
9635 We associate floats only if the user has specified
9636 -fassociative-math. */
9640 {
9645 {
9646 tree tree0;
9649 }
9650 }
9651 }
9653 bit_rotate:
9654 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9655 is a rotate of A by C1 bits. */
9656 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9657 is a rotate of A by B bits.
9658 Similarly for (A << B) | (A >> (-B & C3)) where C3 is Z-1,
9659 though in this case CODE must be | and not + or ^, otherwise
9660 it doesn't return A when B is 0. */
9661 {
9663 tree rtype;
9672 /* Only create rotates in complete modes. Other cases are not
9673 expanded properly. */
9676 {
9689 {
9694 }
9699 {
9702 code0 == LSHIFT_EXPR
9705 }
9707 {
9717 {
9721 orig_tree01);
9723 }
9724 }
9728 {
9739 {
9743 orig_tree01);
9745 }
9746 }
9747 }
9748 }
9750 associate:
9751 /* In most languages, can't associate operations on floats through
9752 parentheses. Rather than remember where the parentheses were, we
9753 don't associate floats at all, unless the user has specified
9754 -fassociative-math.
9755 And, we need to make sure type is not saturating. */
9759 {
9765 /* Split both trees into variables, constants, and literals. Then
9766 associate each group together, the constants with literals,
9767 then the result with variables. This increases the chances of
9768 literals being recombined later and of generating relocatable
9769 expressions for the sum of a constant and literal. */
9777 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9781 /* With undefined overflow prefer doing association in a type
9782 which wraps on overflow, if that is one of the operand types. */
9785 {
9793 }
9795 /* With undefined overflow we can only associate constants with one
9796 variable, and constants whose association doesn't overflow. */
9799 {
9801 {
9802 /* ??? If split_tree would handle NEGATE_EXPR we could
9803 simply reject these cases and the allowed cases would
9804 be the var0/minus_var1 ones. */
9810 {
9813 }
9820 {
9823 }
9829 /* The only case we can still associate with two variables
9830 is if they cancel out. */
9834 }
9840 }
9842 /* Only do something if we found more than two objects. Otherwise,
9843 nothing has changed and we risk infinite recursion. */
9851 {
9863 {
9867 }
9869 {
9873 }
9875 /* Preserve the MINUS_EXPR if the negative part of the literal is
9876 greater than the positive part. Otherwise, the multiplicative
9877 folding code (i.e extract_muldiv) may be fooled in case
9878 unsigned constants are subtracted, like in the following
9879 example: ((X*2 + 4) - 8U)/2. */
9881 {
9885 /* But avoid ending up with only negated parts. */
9887 {
9891 }
9892 else
9893 {
9897 }
9898 }
9900 /* Don't introduce overflows through reassociation. */
9905 /* Eliminate lit0 and minus_lit0 to con0 and minus_con0. */
9912 /* Eliminate minus_con0. */
9914 {
9921 else
9924 }
9926 /* Eliminate minus_var0. */
9928 {
9932 else
9935 }
9937 return
9940 }
9941 }
9947 /* Fold &a[i] - &a[j] to i-j. */
9952 {
9956 code
9960 }
9962 /* Further transformations are not for pointers. */
9966 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9969 /* If arg0 is e.g. unsigned int and type is int, then this could
9970 introduce UB, because if A is INT_MIN at runtime, the original
9971 expression can be well defined while the latter is not.
9972 See PR83269. */
9981 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9982 __complex__ ( x, -y ). This is not the same for SNaNs or if
9983 signed zeros are involved. */
9987 {
9994 {
9998 {
10000 arg1r ? arg1r
10005 }
10007 {
10011 arg1i ? arg1i
10014 }
10015 }
10016 }
10018 /* A - B -> A + (-B) if B is easily negatable. */
10022 /* Avoid this transformation if B is a positive REAL_CST. */
10030 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the same or
10031 one. Make sure the type is not saturating and has the signedness of
10032 the stripped operands, as fold_plusminus_mult_expr will re-associate.
10033 ??? The latter condition should use TYPE_OVERFLOW_* flags instead. */
10040 {
10044 }
10050 {
10051 /* Transform x * -C into -x * C if x is easily negatable. */
10066 {
10069 "occur when simplifying "
10071 WARN_STRICT_OVERFLOW_MISC);
10073 }
10075 /* Optimize z * conj(z) for integer complex numbers. */
10082 }
10083 else
10084 {
10085 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
10086 This is not the same for NaNs or if signed zeros are
10087 involved. */
10093 {
10096 return
10102 return
10107 }
10109 /* Optimize z * conj(z) for floating point complex numbers.
10110 Guarded by flag_unsafe_math_optimizations as non-finite
10111 imaginary components don't produce scalar results. */
10120 }
10124 /* Canonicalize (X & C1) | C2. */
10128 {
10133 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
10141 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
10143 {
10146 }
10148 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2,
10149 unless (C1 & ~C2) | (C2 & C3) for some C3 is a mask of some
10150 mode which allows further optimizations. */
10155 {
10160 {
10163 }
10164 }
10167 {
10172 }
10173 }
10175 /* See if this can be simplified into a rotate first. If that
10176 is unsuccessful continue in the association code. */
10180 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10188 /* See if this can be simplified into a rotate first. If that
10189 is unsuccessful continue in the association code. */
10193 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10198 {
10199 tree tem2;
10206 }
10207 /* Fold ~X & 1 as (X & 1) == 0. */
10211 {
10212 tree tem2;
10219 }
10220 /* Fold !X & 1 as X == 0. */
10223 {
10227 }
10229 /* Fold (X * Y) & -(1 << CST) to X * Y if Y is a constant
10230 multiple of 1 << CST. */
10232 {
10239 }
10241 /* Fold (X * CST1) & CST2 to zero if we can, or drop known zero
10242 bits from CST2. */
10246 {
10248 wide_int masked
10255 {
10256 /* Avoid the transform if arg1 is a mask of some
10257 mode which allows further optimizations. */
10264 }
10265 }
10267 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10270 {
10275 return
10277 }
10282 /* Don't touch a floating-point divide by zero unless the mode
10283 of the constant can represent infinity. */
10289 /* (-A) / (-B) -> A / B */
10301 /* Fall through */
10304 /* Simplify A / (B << N) where A and B are positive and B is
10305 a power of 2, to A >> (N + log2(B)). */
10310 {
10313 {
10321 WARN_STRICT_OVERFLOW_MISC);
10327 }
10328 }
10330 /* Fall through */
10338 /* Convert -A / -B to A / B when the type is signed and overflow is
10339 undefined. */
10343 {
10346 "when distributing negation across "
10348 WARN_STRICT_OVERFLOW_MISC);
10353 }
10357 {
10360 "when distributing negation across "
10362 WARN_STRICT_OVERFLOW_MISC);
10367 }
10369 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10370 operation, EXACT_DIV_EXPR.
10372 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10373 At one time others generated faster code, it's not clear if they do
10374 after the last round to changes to the DIV code in expmed.c. */
10385 {
10389 WARN_STRICT_OVERFLOW_MISC);
10391 }
10403 {
10407 WARN_STRICT_OVERFLOW_MISC);
10409 }
10417 /* Since negative shift count is not well-defined,
10418 don't try to compute it in the compiler. */
10424 /* If we have a rotate of a bit operation with the rotate count and
10425 the second operand of the bit operation both constant,
10426 permute the two operations. */
10432 {
10440 }
10442 /* Two consecutive rotates adding up to the some integer
10443 multiple of the precision of the type can be ignored. */
10459 /* Note that the operands of this must be ints
10460 and their values must be 0 or 1.
10461 ("true" is a fixed value perhaps depending on the language.) */
10462 /* If first arg is constant zero, return it. */
10465 /* FALLTHRU */
10467 /* If either arg is constant true, drop it. */
10471 /* Preserve sequence points. */
10474 /* If second arg is constant zero, result is zero, but first arg
10475 must be evaluated. */
10478 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10479 case will be handled here. */
10483 /* !X && X is always false. */
10487 /* X && !X is always false. */
10492 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10493 means A >= Y && A != MAX, but in this case we know that
10494 A < X <= MAX. */
10498 {
10506 }
10515 /* Note that the operands of this must be ints
10516 and their values must be 0 or true.
10517 ("true" is a fixed value perhaps depending on the language.) */
10518 /* If first arg is constant true, return it. */
10521 /* FALLTHRU */
10523 /* If either arg is constant zero, drop it. */
10527 /* Preserve sequence points. */
10530 /* If second arg is constant true, result is true, but we must
10531 evaluate first arg. */
10534 /* Likewise for first arg, but note this only occurs here for
10535 TRUTH_OR_EXPR. */
10539 /* !X || X is always true. */
10543 /* X || !X is always true. */
10548 /* (X && !Y) || (!X && Y) is X ^ Y */
10551 {
10568 }
10577 /* If the second arg is constant zero, drop it. */
10580 /* If the second arg is constant true, this is a logical inversion. */
10582 {
10585 }
10586 /* Identical arguments cancel to zero. */
10590 /* !X ^ X is always true. */
10595 /* X ^ !X is always true. */
10611 /* bool_var != 1 becomes !bool_var. */
10618 /* bool_var == 0 becomes !bool_var. */
10625 /* !exp != 0 becomes !exp */
10630 /* If this is an EQ or NE comparison with zero and ARG0 is
10631 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10632 two operations, but the latter can be done in one less insn
10633 on machines that have only two-operand insns or on which a
10634 constant cannot be the first operand. */
10637 {
10642 {
10649 arg1);
10650 }
10653 {
10660 arg1);
10661 }
10662 }
10664 /* If this is an NE or EQ comparison of zero against the result of a
10665 signed MOD operation whose second operand is a power of 2, make
10666 the MOD operation unsigned since it is simpler and equivalent. */
10674 {
10684 }
10686 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10687 C1 is a valid shift constant, and C2 is a power of two, i.e.
10688 a single bit. */
10692 == INTEGER_CST
10695 {
10700 /* Check for a valid shift count. */
10702 {
10706 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10707 can be rewritten as (X & (C2 << C1)) != 0. */
10709 {
10714 }
10715 /* Otherwise, for signed (arithmetic) shifts,
10716 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10717 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10721 /* Otherwise, of unsigned (logical) shifts,
10722 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10723 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10724 else
10728 arg000);
10729 }
10730 }
10732 /* If this is a comparison of a field, we may be able to simplify it. */
10735 /* Handle the constant case even without -O
10736 to make sure the warnings are given. */
10738 {
10742 }
10744 /* Optimize comparisons of strlen vs zero to a compare of the
10745 first character of the string vs zero. To wit,
10746 strlen(ptr) == 0 => *ptr == 0
10747 strlen(ptr) != 0 => *ptr != 0
10748 Other cases should reduce to one of these two (or a constant)
10749 due to the return value of strlen being unsigned. */
10752 {
10760 {
10765 }
10766 }
10768 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
10769 of X. Similarly fold (X >> C) == 0 into X >= 0. */
10773 {
10778 {
10780 {
10783 }
10786 }
10787 }
10789 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
10790 (X & C) == 0 when C is a single bit. */
10795 {
10802 arg1));
10803 }
10805 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
10806 constant C is a power of two, i.e. a single bit. */
10813 {
10817 }
10819 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
10820 when is C is a power of two, i.e. a single bit. */
10827 {
10833 }
10837 {
10840 }
10842 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
10845 {
10853 {
10859 }
10861 {
10867 }
10869 {
10875 }
10877 {
10883 }
10884 }
10888 {
10895 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
10896 operand_equal_p guarantees no side-effects so we don't need
10897 to use omit_one_operand on Z. */
10901 arg10));
10905 arg11));
10909 arg10));
10913 arg11));
10915 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
10918 {
10924 }
10925 }
10927 /* Attempt to simplify equality/inequality comparisons of complex
10928 values. Only lower the comparison if the result is known or
10929 can be simplified to a single scalar comparison. */
10934 {
10939 {
10942 }
10943 else
10944 {
10947 }
10950 {
10953 }
10954 else
10955 {
10958 }
10962 {
10964 {
10969 }
10970 else
10971 {
10976 }
10977 }
10981 {
10983 {
10988 }
10989 else
10990 {
10995 }
10996 }
10997 }
11009 /* Transform comparisons of the form X +- C CMP X. */
11014 {
11019 /* (X - c) > X becomes false. */
11025 /* Likewise (X + c) < X becomes false. */
11031 /* Convert (X - c) <= X to true. */
11038 /* Convert (X + c) >= X to true. */
11044 }
11046 /* If we are comparing an ABS_EXPR with a constant, we can
11047 convert all the cases into explicit comparisons, but they may
11048 well not be faster than doing the ABS and one comparison.
11049 But ABS (X) <= C is a range comparison, which becomes a subtraction
11050 and a comparison, and is probably faster. */
11064 /* Convert ABS_EXPR<x> >= 0 to true. */
11071 {
11074 "when simplifying comparison of "
11076 WARN_STRICT_OVERFLOW_CONDITIONAL);
11079 arg0);
11080 }
11082 /* Convert ABS_EXPR<x> < 0 to false. */
11087 {
11090 "when simplifying comparison of "
11092 WARN_STRICT_OVERFLOW_CONDITIONAL);
11095 arg0);
11096 }
11098 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11099 and similarly for >= into !=. */
11109 /* Similarly for X < (cast) (1 << Y). But cast can't be narrowing,
11110 otherwise Y might be >= # of bits in X's type and thus e.g.
11111 (unsigned char) (1 << Y) for Y 15 might be 0.
11112 If the cast is widening, then 1 << Y should have unsigned type,
11113 otherwise if Y is number of bits in the signed shift type minus 1,
11114 we can't optimize this. E.g. (unsigned long long) (1 << Y) for Y
11115 31 might be 0xffffffff80000000. */
11126 {
11132 }
11144 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11145 {
11157 }
11162 /* When pedantic, a compound expression can be neither an lvalue
11163 nor an integer constant expression. */
11166 /* Don't let (0, 0) be null pointer constant. */
11172 /* An ASSERT_EXPR should never be passed to fold_binary. */
11178 }
11180 /* For constants M and N, if M == (1LL << cst) - 1 && (N & M) == M,
11181 ((A & N) + B) & M -> (A + B) & M
11182 Similarly if (N & M) == 0,
11183 ((A | N) + B) & M -> (A + B) & M
11184 and for - instead of + (or unary - instead of +)
11185 and/or ^ instead of |.
11186 If B is constant and (B & M) == 0, fold into A & M.
11188 This function is a helper for match.pd patterns. Return non-NULL
11189 type in which the simplified operation should be performed only
11190 if any optimization is possible.
11192 ARG1 is M above, ARG00 is left operand of +/-, if CODE00 is BIT_*_EXPR,
11193 then ARG00{0,1} are operands of that bitop, otherwise CODE00 is ERROR_MARK.
11194 Similarly for ARG01, CODE01 and ARG01{0,1}, just for the right operand of
11195 +/-. */
11196 tree
11201 {
11216 wide_int cst0;
11218 /* Now we know that arg0 is (C + D) or (C - D) or -C and
11219 arg1 (M) is == (1LL << cst) - 1.
11220 Store C into PMOP[0] and D into PMOP[1]. */
11227 {
11234 {
11237 }
11240 /* If C or D is of the form (A & N) where
11241 (N & M) == M, or of the form (A | N) or
11242 (A ^ N) where (N & M) == 0, replace it with A. */
11248 /* If C or D is a N where (N & M) == 0, it can be
11249 omitted (replaced with 0). */
11254 /* Similarly, with C - N where (-N & M) == 0. */
11262 }
11264 /* Only build anything new if we optimized one or both arguments above. */
11270 else
11272 }
11274 /* Used by contains_label_[p1]. */
11276 struct contains_label_data
11277 {
11280 };
11282 /* Callback for walk_tree, looking for LABEL_EXPR. Return *TP if it is
11283 a LABEL_EXPR or CASE_LABEL_EXPR not inside of another SWITCH_EXPR; otherwise
11284 return NULL_TREE. Do not check the subtrees of GOTO_EXPR. */
11286 static tree
11288 {
11291 {
11302 {
11310 }
11319 }
11320 }
11322 /* Return whether the sub-tree ST contains a label which is accessible from
11323 outside the sub-tree. */
11325 static bool
11327 {
11331 }
11333 /* Fold a ternary expression of code CODE and type TYPE with operands
11334 OP0, OP1, and OP2. Return the folded expression if folding is
11335 successful. Otherwise, return NULL_TREE. */
11337 tree
11340 {
11341 tree tem;
11348 /* If this is a commutative operation, and OP0 is a constant, move it
11349 to OP1 to reduce the number of tests below. */
11358 /* Strip any conversions that don't change the mode. This is safe
11359 for every expression, except for a comparison expression because
11360 its signedness is derived from its operands. So, in the latter
11361 case, only strip conversions that don't change the signedness.
11363 Note that this is done as an internal manipulation within the
11364 constant folder, in order to find the simplest representation of
11365 the arguments so that their form can be studied. In any cases,
11366 the appropriate type conversions should be put back in the tree
11367 that will get out of the constant folder. */
11369 {
11372 }
11375 {
11378 }
11381 {
11384 }
11387 {
11391 {
11397 }
11402 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11403 so all simple results must be passed through pedantic_non_lvalue. */
11405 {
11408 /* Only optimize constant conditions when the selected branch
11409 has the same type as the COND_EXPR. This avoids optimizing
11410 away "c ? x : throw", where the throw has a void type.
11411 Avoid throwing away that operand which contains label. */
11418 }
11420 {
11427 {
11430 {
11438 }
11443 }
11444 }
11446 /* If we have A op B ? A : C, we may be able to convert this to a
11447 simpler expression, depending on the operation and the values
11448 of B and C. Signed zeros prevent all of these transformations,
11449 for reasons given above each one.
11451 Also try swapping the arguments and inverting the conditional. */
11455 {
11459 }
11464 {
11468 {
11472 }
11473 }
11475 /* If the second operand is simpler than the third, swap them
11476 since that produces better jump optimization results. */
11479 {
11481 /* See if this can be inverted. If it can't, possibly because
11482 it was a floating-point inequality comparison, don't do
11483 anything. */
11487 }
11489 /* Convert A ? 1 : 0 to simply A. */
11494 /* If we try to convert OP0 to our type, the
11495 call to fold will try to move the conversion inside
11496 a COND, which will recurse. In that case, the COND_EXPR
11497 is probably the best choice, so leave it alone. */
11501 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11502 over COND_EXPR in cases such as floating point comparisons. */
11511 arg0)));
11513 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11518 {
11519 /* sign_bit_p looks through both zero and sign extensions,
11520 but for this optimization only sign extensions are
11521 usable. */
11524 {
11527 {
11530 }
11532 }
11533 /* sign_bit_p only checks ARG1 bits within A's precision.
11534 If <sign bit of A> has wider type than A, bits outside
11535 of A's precision in <sign bit of A> need to be checked.
11536 If they are all 0, this optimization needs to be done
11537 in unsigned A's type, if they are all 1 in signed A's type,
11538 otherwise this can't be done. */
11544 {
11546 tree tem_type;
11559 {
11562 }
11564 {
11567 }
11568 else
11570 }
11573 return
11579 arg1)));
11580 }
11582 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11583 already handled above. */
11588 {
11598 op1);
11599 }
11601 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11602 is probably obsolete because the first operand should be a
11603 truth value (that's why we have the two cases above), but let's
11604 leave it in until we can confirm this for all front-ends. */
11616 /* Disable the transformations below for vectors, since
11617 fold_binary_op_with_conditional_arg may undo them immediately,
11618 yielding an infinite loop. */
11622 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11631 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11636 {
11638 /* Only perform transformation if ARG0 is easily inverted. */
11642 ? BIT_IOR_EXPR
11645 op1);
11646 }
11648 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11653 {
11655 /* Only perform transformation if ARG0 is easily inverted. */
11661 op2);
11662 }
11664 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11676 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
11677 of fold_ternary on them. */
11687 {
11698 {
11703 {
11705 {
11710 }
11716 }
11717 }
11718 }
11720 /* On constants we can use native encode/interpret to constant
11721 fold (nearly) all BIT_FIELD_REFs. */
11727 {
11730 /* Limit us to a reasonable amount of work. To relax the
11731 other limitations we need bit-shifting of the buffer
11732 and rounding up the size. */
11736 {
11738 unsigned HOST_WIDE_INT len
11743 {
11748 }
11749 }
11750 }
11756 {
11757 /* Build a vector of integers from the tree mask. */
11758 vec_perm_builder builder;
11762 /* Create a vec_perm_indices for the integer vector. */
11767 /* Check for cases that fold to OP0 or OP1 in their original
11768 element order. */
11775 {
11779 {
11782 }
11783 }
11789 {
11793 }
11797 /* Generate a canonical form of the selector. */
11799 {
11800 /* Some targets are deficient and fail to expand a single
11801 argument permutation while still allowing an equivalent
11802 2-argument version. */
11806 else
11807 {
11811 else
11812 /* Not directly supported with either encoding,
11813 so use the preferred form. */
11815 }
11817 }
11821 }
11825 /* Perform (partial) constant folding of BIT_INSERT_EXPR. */
11828 {
11834 wide_int tem2
11838 }
11843 {
11845 unsigned HOST_WIDE_INT elsize
11848 {
11854 {
11860 }
11861 }
11862 }
11868 }
11870 /* Gets the element ACCESS_INDEX from CTOR, which must be a CONSTRUCTOR
11871 of an array (or vector). */
11873 tree
11875 {
11880 {
11883 {
11884 /* Static constructors for variably sized objects makes no sense. */
11888 }
11889 }
11900 offset_int max_index;
11905 {
11906 /* Array constructor might explicitly set index, or specify a range,
11907 or leave index NULL meaning that it is next index after previous
11908 one. */
11910 {
11913 else
11914 {
11918 }
11919 }
11920 else
11921 {
11927 }
11929 /* Do we have match? */
11933 }
11935 }
11937 /* Perform constant folding and related simplification of EXPR.
11938 The related simplifications include x*1 => x, x*0 => 0, etc.,
11939 and application of the associative law.
11940 NOP_EXPR conversions may be removed freely (as long as we
11941 are careful not to change the type of the overall expression).
11942 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
11943 but we can constant-fold them if they have constant operands. */
11945 #ifdef ENABLE_FOLD_CHECKING
11946 # define fold(x) fold_1 (x)
11948 static
11949 #endif
11950 tree
11952 {
11956 tree tem;
11959 /* Return right away if a constant. */
11963 /* CALL_EXPR-like objects with variable numbers of operands are
11964 treated specially. */
11966 {
11968 {
11971 }
11973 }
11976 {
11981 {
11999 }
12000 }
12003 {
12005 {
12012 {
12017 }
12020 }
12022 /* Return a VECTOR_CST if possible. */
12024 {
12030 tree val;
12036 }
12044 }
12046 #ifdef ENABLE_FOLD_CHECKING
12047 #undef fold
12054 /* When --enable-checking=fold, compute a digest of expr before
12055 and after actual fold call to see if fold did not accidentally
12056 change original expr. */
12058 tree
12060 {
12061 tree ret;
12081 }
12083 void
12085 {
12096 }
12098 static void
12100 {
12102 }
12104 static void
12107 {
12113 recursive_label:
12123 {
12124 /* Allow DECL_ASSEMBLER_NAME and symtab_node to be modified. */
12129 }
12137 {
12138 /* Allow these fields to be modified. */
12139 tree tmp;
12148 {
12151 }
12152 }
12163 {
12166 {
12182 }
12186 {
12199 }
12216 {
12222 }
12225 {
12227 {
12230 }
12232 }
12243 {
12246 }
12256 }
12257 }
12259 /* Helper function for outputting the checksum of a tree T. When
12260 debugging with gdb, you can "define mynext" to be "next" followed
12261 by "call debug_fold_checksum (op0)", then just trace down till the
12262 outputs differ. */
12264 DEBUG_FUNCTION void
12266 {
12281 }
12283 #endif
12285 /* Fold a unary tree expression with code CODE of type TYPE with an
12286 operand OP0. LOC is the location of the resulting expression.
12287 Return a folded expression if successful. Otherwise, return a tree
12288 expression with code CODE of type TYPE with an operand OP0. */
12290 tree
12293 {
12294 tree tem;
12295 #ifdef ENABLE_FOLD_CHECKING
12304 #endif
12310 #ifdef ENABLE_FOLD_CHECKING
12317 #endif
12319 }
12321 /* Fold a binary tree expression with code CODE of type TYPE with
12322 operands OP0 and OP1. LOC is the location of the resulting
12323 expression. Return a folded expression if successful. Otherwise,
12324 return a tree expression with code CODE of type TYPE with operands
12325 OP0 and OP1. */
12327 tree
12330 MEM_STAT_DECL)
12331 {
12332 tree tem;
12333 #ifdef ENABLE_FOLD_CHECKING
12350 #endif
12356 #ifdef ENABLE_FOLD_CHECKING
12371 #endif
12373 }
12375 /* Fold a ternary tree expression with code CODE of type TYPE with
12376 operands OP0, OP1, and OP2. Return a folded expression if
12377 successful. Otherwise, return a tree expression with code CODE of
12378 type TYPE with operands OP0, OP1, and OP2. */
12380 tree
12383 {
12384 tree tem;
12385 #ifdef ENABLE_FOLD_CHECKING
12409 #endif
12416 #ifdef ENABLE_FOLD_CHECKING
12439 #endif
12441 }
12443 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12444 arguments in ARGARRAY, and a null static chain.
12445 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12446 of type TYPE from the given operands as constructed by build_call_array. */
12448 tree
12451 {
12452 tree tem;
12453 #ifdef ENABLE_FOLD_CHECKING
12472 #endif
12478 #ifdef ENABLE_FOLD_CHECKING
12494 #endif
12496 }
12498 /* Perform constant folding and related simplification of initializer
12499 expression EXPR. These behave identically to "fold_buildN" but ignore
12500 potential run-time traps and exceptions that fold must preserve. */
12502 #define START_FOLD_INIT \
12503 int saved_signaling_nans = flag_signaling_nans;\
12504 int saved_trapping_math = flag_trapping_math;\
12505 int saved_rounding_math = flag_rounding_math;\
12506 int saved_trapv = flag_trapv;\
12507 int saved_folding_initializer = folding_initializer;\
12508 flag_signaling_nans = 0;\
12509 flag_trapping_math = 0;\
12510 flag_rounding_math = 0;\
12511 flag_trapv = 0;\
12512 folding_initializer = 1;
12514 #define END_FOLD_INIT \
12515 flag_signaling_nans = saved_signaling_nans;\
12516 flag_trapping_math = saved_trapping_math;\
12517 flag_rounding_math = saved_rounding_math;\
12518 flag_trapv = saved_trapv;\
12519 folding_initializer = saved_folding_initializer;
12521 tree
12524 {
12525 tree result;
12526 START_FOLD_INIT;
12530 END_FOLD_INIT;
12532 }
12534 tree
12537 {
12538 tree result;
12539 START_FOLD_INIT;
12543 END_FOLD_INIT;
12545 }
12547 tree
12550 {
12551 tree result;
12552 START_FOLD_INIT;
12556 END_FOLD_INIT;
12558 }
12560 #undef START_FOLD_INIT
12561 #undef END_FOLD_INIT
12563 /* Determine if first argument is a multiple of second argument. Return 0 if
12564 it is not, or we cannot easily determined it to be.
12566 An example of the sort of thing we care about (at this point; this routine
12567 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12568 fold cases do now) is discovering that
12570 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12572 is a multiple of
12574 SAVE_EXPR (J * 8)
12576 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12578 This code also handles discovering that
12580 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12582 is a multiple of 8 so we don't have to worry about dealing with a
12583 possible remainder.
12585 Note that we *look* inside a SAVE_EXPR only to determine how it was
12586 calculated; it is not safe for fold to do much of anything else with the
12587 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12588 at run time. For example, the latter example above *cannot* be implemented
12589 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12590 evaluation time of the original SAVE_EXPR is not necessarily the same at
12591 the time the new expression is evaluated. The only optimization of this
12592 sort that would be valid is changing
12594 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12596 divided by 8 to
12598 SAVE_EXPR (I) * SAVE_EXPR (J)
12600 (where the same SAVE_EXPR (J) is used in the original and the
12601 transformed version). */
12603 int
12605 {
12616 {
12618 /* Bitwise and provides a power of two multiple. If the mask is
12619 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12627 {
12633 {
12636 /* Handle multiple_of_p ((x * 2 + 2) * 4, 8). */
12638 {
12642 {
12645 }
12646 }
12648 }
12649 }
12654 /* It is impossible to prove if op0 - op1 is multiple of bottom
12655 precisely, so be conservative here checking if both op0 and op1
12656 are multiple of bottom. Note we check the second operand first
12657 since it's usually simpler. */
12662 /* The same as MINUS_EXPR, but handle cases like op0 + 0xfffffffd
12663 as op0 - 3 if the expression has unsigned type. For example,
12664 (X / 3) + 0xfffffffd is multiple of 3, but 0xfffffffd is not. */
12674 {
12676 /* const_binop may not detect overflow correctly,
12677 so check for it explicitly here. */
12685 }
12689 /* Can't handle conversions from non-integral or wider integral type. */
12695 /* fall through */
12712 SIGNED);
12718 {
12721 /* Check for special cases to see if top is defined as multiple
12722 of bottom:
12724 top = (X & ~(bottom - 1) ; bottom is power of 2
12726 or
12728 Y = X % bottom
12729 top = X - Y. */
12748 }
12750 /* fall through */
12758 }
12759 }
12761 #define tree_expr_nonnegative_warnv_p(X, Y) \
12764 #define RECURSE(X) \
12765 ((tree_expr_nonnegative_warnv_p) (X, strict_overflow_p, depth + 1))
12767 /* Return true if CODE or TYPE is known to be non-negative. */
12769 static bool
12771 {
12774 /* Truth values evaluate to 0 or 1, which is nonnegative unless we
12775 have a signed:1 type (where the value is -1 and 0). */
12778 }
12780 /* Return true if (CODE OP0) is known to be non-negative. If the return
12781 value is based on the assumption that signed overflow is undefined,
12782 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12783 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12785 bool
12788 {
12793 {
12795 /* We can't return 1 if flag_wrapv is set because
12796 ABS_EXPR<INT_MIN> = INT_MIN. */
12800 {
12803 }
12811 CASE_CONVERT:
12812 {
12817 {
12821 {
12825 }
12826 }
12828 {
12834 }
12835 }
12840 }
12842 /* We don't know sign of `t', so be conservative and return false. */
12844 }
12846 /* Return true if (CODE OP0 OP1) is known to be non-negative. If the return
12847 value is based on the assumption that signed overflow is undefined,
12848 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12849 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12851 bool
12855 {
12860 {
12866 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12867 both unsigned and at least 2 bits shorter than the result. */
12871 {
12876 {
12880 }
12881 }
12886 {
12887 /* x * x is always non-negative for floating point x
12888 or without overflow. */
12891 {
12896 }
12897 }
12899 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12900 both unsigned and their total bits is shorter than the result. */
12904 {
12923 {
12933 }
12934 }
12961 }
12963 /* We don't know sign of `t', so be conservative and return false. */
12965 }
12967 /* Return true if T is known to be non-negative. If the return
12968 value is based on the assumption that signed overflow is undefined,
12969 set *STRICT_OVERFLOW_P to true; otherwise, don't change
12970 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
12972 bool
12974 {
12979 {
12993 /* Limit the depth of recursion to avoid quadratic behavior.
12994 This is expected to catch almost all occurrences in practice.
12995 If this code misses important cases that unbounded recursion
12996 would not, passes that need this information could be revised
12997 to provide it through dataflow propagation. */
13005 }
13006 }
13008 /* Return true if T is known to be non-negative. If the return
13009 value is based on the assumption that signed overflow is undefined,
13010 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13011 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13013 bool
13016 {
13018 {
13019 CASE_CFN_ACOS:
13020 CASE_CFN_ACOSH:
13021 CASE_CFN_CABS:
13022 CASE_CFN_COSH:
13023 CASE_CFN_ERFC:
13024 CASE_CFN_EXP:
13025 CASE_CFN_EXP10:
13026 CASE_CFN_EXP2:
13027 CASE_CFN_FABS:
13028 CASE_CFN_FDIM:
13029 CASE_CFN_HYPOT:
13030 CASE_CFN_POW10:
13031 CASE_CFN_FFS:
13032 CASE_CFN_PARITY:
13033 CASE_CFN_POPCOUNT:
13034 CASE_CFN_CLZ:
13035 CASE_CFN_CLRSB:
13038 /* Always true. */
13041 CASE_CFN_SQRT:
13042 CASE_CFN_SQRT_FN:
13043 /* sqrt(-0.0) is -0.0. */
13048 CASE_CFN_ASINH:
13049 CASE_CFN_ATAN:
13050 CASE_CFN_ATANH:
13051 CASE_CFN_CBRT:
13052 CASE_CFN_CEIL:
13053 CASE_CFN_CEIL_FN:
13054 CASE_CFN_ERF:
13055 CASE_CFN_EXPM1:
13056 CASE_CFN_FLOOR:
13057 CASE_CFN_FLOOR_FN:
13058 CASE_CFN_FMOD:
13059 CASE_CFN_FREXP:
13060 CASE_CFN_ICEIL:
13061 CASE_CFN_IFLOOR:
13062 CASE_CFN_IRINT:
13063 CASE_CFN_IROUND:
13064 CASE_CFN_LCEIL:
13065 CASE_CFN_LDEXP:
13066 CASE_CFN_LFLOOR:
13067 CASE_CFN_LLCEIL:
13068 CASE_CFN_LLFLOOR:
13069 CASE_CFN_LLRINT:
13070 CASE_CFN_LLROUND:
13071 CASE_CFN_LRINT:
13072 CASE_CFN_LROUND:
13073 CASE_CFN_MODF:
13074 CASE_CFN_NEARBYINT:
13075 CASE_CFN_NEARBYINT_FN:
13076 CASE_CFN_RINT:
13077 CASE_CFN_RINT_FN:
13078 CASE_CFN_ROUND:
13079 CASE_CFN_ROUND_FN:
13080 CASE_CFN_SCALB:
13081 CASE_CFN_SCALBLN:
13082 CASE_CFN_SCALBN:
13083 CASE_CFN_SIGNBIT:
13084 CASE_CFN_SIGNIFICAND:
13085 CASE_CFN_SINH:
13086 CASE_CFN_TANH:
13087 CASE_CFN_TRUNC:
13088 CASE_CFN_TRUNC_FN:
13089 /* True if the 1st argument is nonnegative. */
13092 CASE_CFN_FMAX:
13093 CASE_CFN_FMAX_FN:
13094 /* True if the 1st OR 2nd arguments are nonnegative. */
13097 CASE_CFN_FMIN:
13098 CASE_CFN_FMIN_FN:
13099 /* True if the 1st AND 2nd arguments are nonnegative. */
13102 CASE_CFN_COPYSIGN:
13103 CASE_CFN_COPYSIGN_FN:
13104 /* True if the 2nd argument is nonnegative. */
13107 CASE_CFN_POWI:
13108 /* True if the 1st argument is nonnegative or the second
13109 argument is an even integer. */
13115 CASE_CFN_POW:
13116 /* True if the 1st argument is nonnegative or the second
13117 argument is an even integer valued real. */
13119 {
13120 REAL_VALUE_TYPE c;
13121 HOST_WIDE_INT n;
13126 {
13127 REAL_VALUE_TYPE cint;
13131 }
13132 }
13137 }
13139 }
13141 /* Return true if T is known to be non-negative. If the return
13142 value is based on the assumption that signed overflow is undefined,
13143 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13144 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13146 static bool
13148 {
13154 {
13156 {
13160 /* If the initializer is non-void, then it's a normal expression
13161 that will be assigned to the slot. */
13165 /* Otherwise, the initializer sets the slot in some way. One common
13166 way is an assignment statement at the end of the initializer. */
13168 {
13176 else
13178 }
13184 }
13187 {
13193 arg0,
13194 arg1,
13196 }
13209 }
13210 }
13212 #undef RECURSE
13213 #undef tree_expr_nonnegative_warnv_p
13215 /* Return true if T is known to be non-negative. If the return
13216 value is based on the assumption that signed overflow is undefined,
13217 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13218 *STRICT_OVERFLOW_P. DEPTH is the current nesting depth of the query. */
13220 bool
13222 {
13229 {
13251 }
13254 {
13280 }
13281 }
13283 /* Return true if `t' is known to be non-negative. Handle warnings
13284 about undefined signed overflow. */
13286 bool
13288 {
13295 "determining that expression is always "
13297 WARN_STRICT_OVERFLOW_MISC);
13299 }
13302 /* Return true when (CODE OP0) is an address and is known to be nonzero.
13303 For floating point we further ensure that T is not denormal.
13304 Similar logic is present in nonzero_address in rtlanal.h.
13306 If the return value is based on the assumption that signed overflow
13307 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13308 change *STRICT_OVERFLOW_P. */
13310 bool
13313 {
13315 {
13318 strict_overflow_p);
13321 {
13327 strict_overflow_p));
13328 }
13333 strict_overflow_p);
13337 }
13340 }
13342 /* Return true when (CODE OP0 OP1) is an address and is known to be nonzero.
13343 For floating point we further ensure that T is not denormal.
13344 Similar logic is present in nonzero_address in rtlanal.h.
13346 If the return value is based on the assumption that signed overflow
13347 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13348 change *STRICT_OVERFLOW_P. */
13350 bool
13352 tree type,
13353 tree op0,
13355 {
13358 {
13362 {
13363 /* With the presence of negative values it is hard
13364 to say something. */
13371 /* One of operands must be positive and the other non-negative. */
13372 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13373 overflows, on a twos-complement machine the sum of two
13374 nonnegative numbers can never be zero. */
13376 strict_overflow_p)
13378 strict_overflow_p));
13379 }
13384 {
13386 strict_overflow_p)
13388 strict_overflow_p))
13389 {
13392 }
13393 }
13402 {
13405 }
13412 {
13416 /* When both operands are nonzero, then MAX must be too. */
13418 strict_overflow_p))
13421 /* MAX where operand 0 is positive is positive. */
13423 strict_overflow_p);
13424 }
13425 /* MAX where operand 1 is positive is positive. */
13430 {
13434 }
13439 strict_overflow_p)
13441 strict_overflow_p));
13445 }
13448 }
13450 /* Return true when T is an address and is known to be nonzero.
13451 For floating point we further ensure that T is not denormal.
13452 Similar logic is present in nonzero_address in rtlanal.h.
13454 If the return value is based on the assumption that signed overflow
13455 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13456 change *STRICT_OVERFLOW_P. */
13458 bool
13460 {
13463 {
13468 {
13480 /* For objects in symbol table check if we know they are non-zero.
13481 Don't do anything for variables and functions before symtab is built;
13482 it is quite possible that they will be declared weak later. */
13487 /* Constants are never weak. */
13492 }
13500 {
13504 }
13514 }
13516 }
13518 #define integer_valued_real_p(X) \
13521 #define RECURSE(X) \
13522 ((integer_valued_real_p) (X, depth + 1))
13524 /* Return true if the floating point result of (CODE OP0) has an
13525 integer value. We also allow +Inf, -Inf and NaN to be considered
13526 integer values. Return false for signaling NaN.
13528 DEPTH is the current nesting depth of the query. */
13530 bool
13532 {
13534 {
13541 CASE_CONVERT:
13542 {
13549 }
13553 }
13555 }
13557 /* Return true if the floating point result of (CODE OP0 OP1) has an
13558 integer value. We also allow +Inf, -Inf and NaN to be considered
13559 integer values. Return false for signaling NaN.
13561 DEPTH is the current nesting depth of the query. */
13563 bool
13565 {
13567 {
13577 }
13579 }
13581 /* Return true if the floating point result of calling FNDECL with arguments
13582 ARG0 and ARG1 has an integer value. We also allow +Inf, -Inf and NaN to be
13583 considered integer values. Return false for signaling NaN. If FNDECL
13584 takes fewer than 2 arguments, the remaining ARGn are null.
13586 DEPTH is the current nesting depth of the query. */
13588 bool
13590 {
13592 {
13593 CASE_CFN_CEIL:
13594 CASE_CFN_CEIL_FN:
13595 CASE_CFN_FLOOR:
13596 CASE_CFN_FLOOR_FN:
13597 CASE_CFN_NEARBYINT:
13598 CASE_CFN_NEARBYINT_FN:
13599 CASE_CFN_RINT:
13600 CASE_CFN_RINT_FN:
13601 CASE_CFN_ROUND:
13602 CASE_CFN_ROUND_FN:
13603 CASE_CFN_TRUNC:
13604 CASE_CFN_TRUNC_FN:
13607 CASE_CFN_FMIN:
13608 CASE_CFN_FMIN_FN:
13609 CASE_CFN_FMAX:
13610 CASE_CFN_FMAX_FN:
13615 }
13617 }
13619 /* Return true if the floating point expression T (a GIMPLE_SINGLE_RHS)
13620 has an integer value. We also allow +Inf, -Inf and NaN to be
13621 considered integer values. Return false for signaling NaN.
13623 DEPTH is the current nesting depth of the query. */
13625 bool
13627 {
13629 {
13637 /* Limit the depth of recursion to avoid quadratic behavior.
13638 This is expected to catch almost all occurrences in practice.
13639 If this code misses important cases that unbounded recursion
13640 would not, passes that need this information could be revised
13641 to provide it through dataflow propagation. */
13645 depth));
13649 }
13651 }
13653 /* Return true if the floating point expression T (a GIMPLE_INVALID_RHS)
13654 has an integer value. We also allow +Inf, -Inf and NaN to be
13655 considered integer values. Return false for signaling NaN.
13657 DEPTH is the current nesting depth of the query. */
13659 static bool
13661 {
13663 {
13674 }
13676 }
13678 #undef RECURSE
13679 #undef integer_valued_real_p
13681 /* Return true if the floating point expression T has an integer value.
13682 We also allow +Inf, -Inf and NaN to be considered integer values.
13683 Return false for signaling NaN.
13685 DEPTH is the current nesting depth of the query. */
13687 bool
13689 {
13695 {
13711 }
13714 {
13720 {
13729 }
13733 }
13734 }
13736 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13737 attempt to fold the expression to a constant without modifying TYPE,
13738 OP0 or OP1.
13740 If the expression could be simplified to a constant, then return
13741 the constant. If the expression would not be simplified to a
13742 constant, then return NULL_TREE. */
13744 tree
13746 {
13749 }
13751 /* Given the components of a unary expression CODE, TYPE and OP0,
13752 attempt to fold the expression to a constant without modifying
13753 TYPE or OP0.
13755 If the expression could be simplified to a constant, then return
13756 the constant. If the expression would not be simplified to a
13757 constant, then return NULL_TREE. */
13759 tree
13761 {
13764 }
13766 /* If EXP represents referencing an element in a constant string
13767 (either via pointer arithmetic or array indexing), return the
13768 tree representing the value accessed, otherwise return NULL. */
13770 tree
13772 {
13776 {
13778 tree index;
13779 tree string;
13784 else
13785 {
13789 /* Optimize the special-case of a zero lower bound.
13791 We convert the low_bound to sizetype to avoid some problems
13792 with constant folding. (E.g. suppose the lower bound is 1,
13793 and its mode is QI. Without the conversion,l (ARRAY
13794 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13795 +INDEX), which becomes (ARRAY+255+INDEX). Oops!) */
13801 }
13803 scalar_int_mode char_mode;
13815 }
13817 }
13819 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13820 an integer constant, real, or fixed-point constant.
13822 TYPE is the type of the result. */
13824 static tree
13826 {
13830 {
13836 {
13837 FIXED_VALUE_TYPE f;
13842 /* Propagate overflow flags. */
13846 }
13850 {
13857 }
13860 }
13863 }
13865 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13866 an integer constant or real constant.
13868 TYPE is the type of the result. */
13870 tree
13872 {
13876 {
13878 {
13879 /* If the value is unsigned or non-negative, then the absolute value
13880 is the same as the ordinary value. */
13884 ;
13886 /* If the value is negative, then the absolute value is
13887 its negation. */
13888 else
13891 /* Force to the destination type, set TREE_OVERFLOW for signed
13892 TYPE only. */
13894 }
13900 else
13906 }
13909 }
13911 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13912 constant. TYPE is the type of the result. */
13914 static tree
13916 {
13920 }
13922 /* Given CODE, a relational operator, the target type, TYPE and two
13923 constant operands OP0 and OP1, return the result of the
13924 relational operation. If the result is not a compile time
13925 constant, then return NULL_TREE. */
13927 static tree
13929 {
13932 /* From here on, the only cases we handle are when the result is
13933 known to be a constant. */
13936 {
13940 /* Handle the cases where either operand is a NaN. */
13942 {
13944 {
13972 }
13975 }
13978 }
13981 {
13985 }
13987 /* Handle equality/inequality of complex constants. */
13989 {
14000 else
14002 }
14005 {
14007 {
14008 /* Have vector comparison with scalar boolean result. */
14016 {
14024 }
14026 }
14027 tree_vector_builder elts;
14032 {
14045 }
14048 }
14050 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
14052 To compute GT, swap the arguments and do LT.
14053 To compute GE, do LT and invert the result.
14054 To compute LE, swap the arguments, do LT and invert the result.
14055 To compute NE, do EQ and invert the result.
14057 Therefore, the code below must handle only EQ and LT. */
14060 {
14063 }
14065 /* Note that it is safe to invert for real values here because we
14066 have already handled the one case that it matters. */
14070 {
14073 }
14075 /* Compute a result for LT or EQ if args permit;
14076 Otherwise return T. */
14078 {
14081 else
14083 }
14084 else
14090 }
14092 /* If necessary, return a CLEANUP_POINT_EXPR for EXPR with the
14093 indicated TYPE. If no CLEANUP_POINT_EXPR is necessary, return EXPR
14094 itself. */
14096 tree
14098 {
14099 /* If the expression does not have side effects then we don't have to wrap
14100 it with a cleanup point expression. */
14104 /* If the expression is a return, check to see if the expression inside the
14105 return has no side effects or the right hand side of the modify expression
14106 inside the return. If either don't have side effects set we don't need to
14107 wrap the expression in a cleanup point expression. Note we don't check the
14108 left hand side of the modify because it should always be a return decl. */
14110 {
14117 }
14120 }
14122 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14123 of an indirection through OP0, or NULL_TREE if no simplification is
14124 possible. */
14126 tree
14128 {
14130 tree subtype;
14131 poly_uint64 const_op01;
14140 {
14144 /* *&CONST_DECL -> to the value of the const decl. */
14147 /* *&p => p; make sure to handle *&"str"[cst] here. */
14149 {
14153 else
14155 }
14156 /* *(foo *)&fooarray => fooarray[0] */
14159 && (!in_gimple_form
14161 {
14171 }
14172 /* *(foo *)&complexfoo => __real__ complexfoo */
14176 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14179 {
14183 index);
14184 }
14185 }
14189 {
14195 {
14196 tree op00type;
14200 /* ((foo*)&vectorfoo)[1] => BIT_FIELD_REF<vectorfoo,...> */
14203 /* POINTER_PLUS_EXPR second operand is sizetype, unsigned,
14204 but we want to treat offsets with MSB set as negative.
14205 For the code below negative offsets are invalid and
14206 TYPE_SIZE of the element is something unsigned, so
14207 check whether op01 fits into poly_int64, which implies
14208 it is from 0 to INTTYPE_MAXIMUM (HOST_WIDE_INT), and
14209 then just use poly_uint64 because we want to treat the
14210 value as unsigned. */
14212 {
14214 poly_uint64 max_offset
14218 {
14223 }
14224 }
14225 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14228 {
14230 const_op01))
14232 }
14233 /* ((foo *)&fooarray)[1] => fooarray[1] */
14236 {
14245 {
14250 }
14251 }
14252 }
14253 }
14255 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14258 && (!in_gimple_form
14260 {
14261 tree type_domain;
14271 NULL_TREE);
14272 }
14275 }
14277 /* Builds an expression for an indirection through T, simplifying some
14278 cases. */
14280 tree
14282 {
14290 }
14292 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14294 tree
14296 {
14301 else
14303 }
14305 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14306 whose result is ignored. The type of the returned tree need not be
14307 the same as the original expression. */
14309 tree
14311 {
14317 {
14328 else
14334 {
14350 }
14355 }
14356 }
14358 /* Return the value of VALUE, rounded up to a multiple of DIVISOR. */
14360 tree
14362 {
14368 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14369 have to do anything. Only do this when we are not given a const,
14370 because in that case, this check is more expensive than just
14371 doing it. */
14373 {
14378 }
14380 /* If divisor is a power of two, simplify this to bit manipulation. */
14382 {
14384 {
14398 }
14399 else
14400 {
14401 tree t;
14407 }
14408 }
14409 else
14410 {
14415 }
14418 }
14420 /* Likewise, but round down. */
14422 tree
14424 {
14431 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14432 have to do anything. Only do this when we are not given a const,
14433 because in that case, this check is more expensive than just
14434 doing it. */
14436 {
14441 }
14443 /* If divisor is a power of two, simplify this to bit manipulation. */
14445 {
14446 tree t;
14450 }
14451 else
14452 {
14457 }
14460 }
14462 /* Returns the pointer to the base of the object addressed by EXP and
14463 extracts the information about the offset of the access, storing it
14464 to PBITPOS and POFFSET. */
14466 static tree
14469 {
14470 tree core;
14471 machine_mode mode;
14473 poly_int64 bitsize;
14477 {
14482 }
14484 {
14490 {
14491 poly_offset_int tem
14497 }
14498 }
14499 else
14500 {
14504 }
14507 }
14509 /* Returns true if addresses of E1 and E2 differ by a constant, false
14510 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14512 bool
14514 {
14529 {
14539 }
14541 {
14542 /* If only one of the offsets is non-constant, the difference cannot
14543 be a constant. */
14545 }
14546 else
14551 }
14553 /* Return OFF converted to a pointer offset type suitable as offset for
14554 POINTER_PLUS_EXPR. Use location LOC for this conversion. */
14555 tree
14557 {
14559 }
14561 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14562 tree
14564 {
14567 }
14569 /* Build and fold a POINTER_PLUS_EXPR at LOC offsetting PTR by OFF. */
14570 tree
14572 {
14575 }
14577 /* Return a pointer P to a NUL-terminated string representing the sequence
14578 of constant characters referred to by SRC (or a subsequence of such
14579 characters within it if SRC is a reference to a string plus some
14580 constant offset). If STRLEN is non-null, store stgrlen(P) in *STRLEN.
14581 If STRSIZE is non-null, store in *STRSIZE the size of the array
14582 the string is stored in; in that case, even though P points to a NUL
14583 terminated string, SRC need not refer to one. This can happen when
14584 SRC refers to a constant character array initialized to all non-NUL
14585 values, as in the C declaration: char a[4] = "1234"; */
14590 {
14591 tree offset_node;
14602 {
14605 else
14607 }
14609 /* STRING_LENGTH is the size of the string literal, including any
14610 embedded NULs. STRING_SIZE is the size of the array the string
14611 literal is stored in. */
14620 {
14621 /* Compute and store the length of the substring at OFFSET.
14622 All offsets past the initial length refer to null strings. */
14625 else
14627 }
14636 {
14637 /* Support even constant character arrays that aren't proper
14638 NUL-terminated strings. */
14640 }
14642 {
14643 /* Support only properly NUL-terminated strings but handle
14644 consecutive strings within the same array, such as the six
14645 substrings in "1\0002\0003". */
14647 }
14650 }
14652 /* Given a tree T, compute which bits in T may be nonzero. */
14654 wide_int
14656 {
14658 {
14676 CASE_CONVERT:
14682 {
14687 }
14691 {
14699 }
14703 {
14711 }
14715 }
14718 }
14720 #if CHECKING_P
14724 /* Helper functions for writing tests of folding trees. */
14726 /* Verify that the binary op (LHS CODE RHS) folds to CONSTANT. */
14728 static void
14730 tree constant)
14731 {
14733 }
14735 /* Verify that the binary op (LHS CODE RHS) folds to an NON_LVALUE_EXPR
14736 wrapping WRAPPED_EXPR. */
14738 static void
14740 tree wrapped_expr)
14741 {
14746 }
14748 /* Verify that various arithmetic binary operations are folded
14749 correctly. */
14751 static void
14753 {
14759 /* Addition. */
14760 /* 1 <-- (0 + 1) */
14762 one);
14764 one);
14766 /* (nonlvalue)x <-- (x + 0) */
14768 x);
14770 /* Subtraction. */
14771 /* 0 <-- (x - x) */
14773 zero);
14775 x);
14777 /* Multiplication. */
14778 /* 0 <-- (x * 0) */
14780 zero);
14782 /* (nonlvalue)x <-- (x * 1) */
14784 x);
14785 }
14787 /* Verify that various binary operations on vectors are folded
14788 correctly. */
14790 static void
14792 {
14798 /* Verify equality tests that return a scalar boolean result. */
14804 }
14806 /* Verify folding of VEC_DUPLICATE_EXPRs. */
14808 static void
14810 {
14813 /* This will be 1 if VEC_MODE isn't a vector mode. */
14820 }
14822 /* Run all of the selftests within this file. */
14824 void
14826 {
14830 }