| blob | c4c6edce9f77e6348893562fdd3d3f6e701f1c9c |
1 /* Fold a constant sub-tree into a single node for C-compiler
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
3 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 2, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING. If not, write to the Free
20 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
21 02110-1301, USA. */
23 /*@@ This file should be rewritten to use an arbitrary precision
24 @@ representation for "struct tree_int_cst" and "struct tree_real_cst".
25 @@ Perhaps the routines could also be used for bc/dc, and made a lib.
26 @@ The routines that translate from the ap rep should
27 @@ warn if precision et. al. is lost.
28 @@ This would also make life easier when this technology is used
29 @@ for cross-compilers. */
31 /* The entry points in this file are fold, size_int_wide, size_binop
32 and force_fit_type_double.
34 fold takes a tree as argument and returns a simplified tree.
36 size_binop takes a tree code for an arithmetic operation
37 and two operands that are trees, and produces a tree for the
38 result, assuming the type comes from `sizetype'.
40 size_int takes an integer value, and creates a tree constant
41 with type from `sizetype'.
43 force_fit_type_double takes a constant, an overflowable flag and a
44 prior overflow indicator. It forces the value to fit the type and
45 sets TREE_OVERFLOW.
47 Note: Since the folders get called on non-gimple code as well as
48 gimple code, we need to handle GIMPLE tuples as well as their
49 corresponding tree equivalents. */
68 /* Non-zero if we are folding constants inside an initializer; zero
69 otherwise. */
72 /* The following constants represent a bit based encoding of GCC's
73 comparison operators. This encoding simplifies transformations
74 on relational comparison operators, such as AND and OR. */
92 };
126 tree);
148 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
149 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
150 and SUM1. Then this yields nonzero if overflow occurred during the
151 addition.
153 Overflow occurs if A and B have the same sign, but A and SUM differ in
154 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
155 sign. */
156 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
157 \f
158 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
159 We do that by representing the two-word integer in 4 words, with only
160 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
161 number. The value of the word is LOWPART + HIGHPART * BASE. */
163 #define LOWPART(x) \
164 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
165 #define HIGHPART(x) \
166 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
167 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
169 /* Unpack a two-word integer into 4 words.
170 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
171 WORDS points to the array of HOST_WIDE_INTs. */
173 static void
175 {
180 }
182 /* Pack an array of 4 words into a two-word integer.
183 WORDS points to the array of words.
184 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
186 static void
189 {
192 }
193 \f
194 /* Force the double-word integer L1, H1 to be within the range of the
195 integer type TYPE. Stores the properly truncated and sign-extended
196 double-word integer in *LV, *HV. Returns true if the operation
197 overflows, that is, argument and result are different. */
199 int
202 {
211 else
214 /* Size types *are* sign extended. */
219 /* First clear all bits that are beyond the type's precision. */
221 ;
224 else
225 {
229 }
231 /* Then do sign extension if necessary. */
237 {
238 /* Sign extend top half? */
242 }
244 {
247 }
248 else
249 {
250 /* Sign extend bottom half? */
252 {
255 }
256 }
261 /* If the value didn't fit, signal overflow. */
263 }
265 /* We force the double-int HIGH:LOW to the range of the type TYPE by
266 sign or zero extending it.
267 OVERFLOWABLE indicates if we are interested
268 in overflow of the value, when >0 we are only interested in signed
269 overflow, for <0 we are interested in any overflow. OVERFLOWED
270 indicates whether overflow has already occurred. CONST_OVERFLOWED
271 indicates whether constant overflow has already occurred. We force
272 T's value to be within range of T's type (by setting to 0 or 1 all
273 the bits outside the type's range). We set TREE_OVERFLOWED if,
274 OVERFLOWED is nonzero,
275 or OVERFLOWABLE is >0 and signed overflow occurs
276 or OVERFLOWABLE is <0 and any overflow occurs
277 We return a new tree node for the extended double-int. The node
278 is shared if no overflow flags are set. */
280 tree
284 {
288 /* Size types *are* sign extended. */
295 /* If we need to set overflow flags, return a new unshared node. */
297 {
301 {
308 }
309 }
311 /* Else build a shared node. */
313 }
314 \f
315 /* Add two doubleword integers with doubleword result.
316 Return nonzero if the operation overflows according to UNSIGNED_P.
317 Each argument is given as two `HOST_WIDE_INT' pieces.
318 One argument is L1 and H1; the other, L2 and H2.
319 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
321 int
326 {
328 HOST_WIDE_INT h;
338 else
340 }
342 /* Negate a doubleword integer with doubleword result.
343 Return nonzero if the operation overflows, assuming it's signed.
344 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
345 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
347 int
350 {
352 {
356 }
357 else
358 {
362 }
363 }
364 \f
365 /* Multiply two doubleword integers with doubleword result.
366 Return nonzero if the operation overflows according to UNSIGNED_P.
367 Each argument is given as two `HOST_WIDE_INT' pieces.
368 One argument is L1 and H1; the other, L2 and H2.
369 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
371 int
376 {
391 {
394 {
396 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
398 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
402 }
404 }
409 /* Unsigned overflow is immediate. */
413 /* Check for signed overflow by calculating the signed representation of the
414 top half of the result; it should agree with the low half's sign bit. */
416 {
419 }
421 {
424 }
426 }
427 \f
428 /* Shift the doubleword integer in L1, H1 left by COUNT places
429 keeping only PREC bits of result.
430 Shift right if COUNT is negative.
431 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
432 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
434 void
438 {
442 {
445 }
451 {
452 /* Shifting by the host word size is undefined according to the
453 ANSI standard, so we must handle this as a special case. */
456 }
458 {
461 }
462 else
463 {
467 }
469 /* Sign extend all bits that are beyond the precision. */
477 ;
479 {
482 }
483 else
484 {
488 }
489 }
491 /* Shift the doubleword integer in L1, H1 right by COUNT places
492 keeping only PREC bits of result. COUNT must be positive.
493 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
494 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
496 void
501 {
504 signmask = (arith
512 {
513 /* Shifting by the host word size is undefined according to the
514 ANSI standard, so we must handle this as a special case. */
517 }
519 {
522 }
523 else
524 {
528 }
530 /* Zero / sign extend all bits that are beyond the precision. */
533 {
536 }
538 ;
540 {
543 }
544 else
545 {
549 }
550 }
551 \f
552 /* Rotate the doubleword integer in L1, H1 left by COUNT places
553 keeping only PREC bits of result.
554 Rotate right if COUNT is negative.
555 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
557 void
561 {
573 }
575 /* Rotate the doubleword integer in L1, H1 left by COUNT places
576 keeping only PREC bits of result. COUNT must be positive.
577 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
579 void
583 {
595 }
596 \f
597 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
598 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
599 CODE is a tree code for a kind of division, one of
600 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
601 or EXACT_DIV_EXPR
602 It controls how the quotient is rounded to an integer.
603 Return nonzero if the operation overflows.
604 UNS nonzero says do unsigned division. */
606 int
609 HOST_WIDE_INT hnum_orig,
611 HOST_WIDE_INT hden_orig,
615 {
631 /* Calculate quotient sign and convert operands to unsigned. */
633 {
635 {
637 /* (minimum integer) / (-1) is the only overflow case. */
641 }
643 {
646 }
647 }
652 /* This unsigned division rounds toward zero. */
655 }
659 /* hden != 0 already checked. */
664 }
674 /* Special code for when the divisor < BASE. */
676 {
677 /* hnum != 0 already checked. */
679 {
683 }
684 }
685 else
686 {
687 /* Full double precision division,
688 with thanks to Don Knuth's "Seminumerical Algorithms". */
692 /* Find the highest nonzero divisor digit. */
695 {
698 }
700 /* Insure that the first digit of the divisor is at least BASE/2.
701 This is required by the quotient digit estimation algorithm. */
708 {
712 }
717 {
722 }
723 }
727 /* Main loop */
729 {
730 /* Guess the next quotient digit, quo_est, by dividing the first
731 two remaining dividend digits by the high order quotient digit.
732 quo_est is never low and is at most 2 high. */
739 else
742 /* Refine quo_est so it's usually correct, and at most one high. */
747 quo_est--;
749 /* Try QUO_EST as the quotient digit, by multiplying the
750 divisor by QUO_EST and subtracting from the remaining dividend.
751 Keep in mind that QUO_EST is the I - 1st digit. */
755 {
761 }
763 /* If quo_est was high by one, then num[i] went negative and
764 we need to correct things. */
766 {
767 quo_est--;
770 {
774 }
777 }
779 /* Store the quotient digit. */
781 }
782 }
786 finish_up:
787 /* If result is negative, make it so. */
791 /* Compute trial remainder: rem = num - (quo * den) */
797 {
806 {
807 /* quo = quo - 1; */
810 }
811 else
818 {
821 }
822 else
828 {
834 /* Get absolute values. */
840 /* If (2 * abs (lrem) >= abs (lden)) */
849 {
851 /* quo = quo - 1; */
854 else
855 /* quo = quo + 1; */
858 }
859 else
861 }
866 }
868 /* Compute true remainder: rem = num - (quo * den) */
873 }
875 /* If ARG2 divides ARG1 with zero remainder, carries out the division
876 of type CODE and returns the quotient.
877 Otherwise returns NULL_TREE. */
879 static tree
881 {
891 /* &obj[0] + -128 really should be compiled as &obj[-8] rahter than
892 &obj[some_exotic_number]. */
894 {
898 type);
899 }
900 else
911 }
912 \f
913 /* This is non-zero if we should defer warnings about undefined
914 overflow. This facility exists because these warnings are a
915 special case. The code to estimate loop iterations does not want
916 to issue any warnings, since it works with expressions which do not
917 occur in user code. Various bits of cleanup code call fold(), but
918 only use the result if it has certain characteristics (e.g., is a
919 constant); that code only wants to issue a warning if the result is
920 used. */
924 /* If a warning about undefined overflow is deferred, this is the
925 warning. Note that this may cause us to turn two warnings into
926 one, but that is fine since it is sufficient to only give one
927 warning per expression. */
931 /* If a warning about undefined overflow is deferred, this is the
932 level at which the warning should be emitted. */
936 /* Start deferring overflow warnings. We could use a stack here to
937 permit nested calls, but at present it is not necessary. */
939 void
941 {
943 }
945 /* Stop deferring overflow warnings. If there is a pending warning,
946 and ISSUE is true, then issue the warning if appropriate. STMT is
947 the statement with which the warning should be associated (used for
948 location information); STMT may be NULL. CODE is the level of the
949 warning--a warn_strict_overflow_code value. This function will use
950 the smaller of CODE and the deferred code when deciding whether to
951 issue the warning. CODE may be zero to mean to always use the
952 deferred code. */
954 void
956 {
958 location_t locus;
963 {
969 }
977 /* Use the smallest code level when deciding to issue the
978 warning. */
987 else
990 }
992 /* Stop deferring overflow warnings, ignoring any deferred
993 warnings. */
995 void
997 {
999 }
1001 /* Whether we are deferring overflow warnings. */
1003 bool
1005 {
1007 }
1009 /* This is called when we fold something based on the fact that signed
1010 overflow is undefined. */
1012 static void
1014 {
1017 {
1020 {
1023 }
1024 }
1027 }
1028 \f
1029 /* Return true if the built-in mathematical function specified by CODE
1030 is odd, i.e. -f(x) == f(-x). */
1032 static bool
1034 {
1036 {
1070 }
1072 }
1074 /* Check whether we may negate an integer constant T without causing
1075 overflow. */
1077 bool
1079 {
1082 tree type;
1092 {
1097 }
1098 else
1103 }
1105 /* Determine whether an expression T can be cheaply negated using
1106 the function negate_expr without introducing undefined overflow. */
1108 static bool
1110 {
1111 tree type;
1120 {
1125 /* Check that -CST will not overflow type. */
1150 /* -(A + B) -> (-B) - A. */
1155 /* -(A + B) -> (-A) - B. */
1159 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1169 /* Fall through. */
1182 /* In general we can't negate A / B, because if A is INT_MIN and
1183 B is 1, we may turn this into INT_MIN / -1 which is undefined
1184 and actually traps on some architectures. But if overflow is
1185 undefined, we can negate, because - (INT_MIN / 1) is an
1186 overflow. */
1194 /* Negate -((double)float) as (double)(-float). */
1196 {
1200 }
1204 /* Negate -f(x) as f(-x). */
1210 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1212 {
1218 }
1223 }
1225 }
1227 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1228 simplification is possible.
1229 If negate_expr_p would return true for T, NULL_TREE will never be
1230 returned. */
1232 static tree
1234 {
1236 tree tem;
1239 {
1240 /* Convert - (~A) to A + 1. */
1256 /* Two's complement FP formats, such as c4x, may overflow. */
1262 {
1271 }
1293 {
1294 /* -(A + B) -> (-B) - A. */
1298 {
1302 }
1304 /* -(A + B) -> (-A) - B. */
1306 {
1310 }
1311 }
1315 /* - (A - B) -> B - A */
1327 /* Fall through. */
1331 {
1340 }
1348 /* In general we can't negate A / B, because if A is INT_MIN and
1349 B is 1, we may turn this into INT_MIN / -1 which is undefined
1350 and actually traps on some architectures. But if overflow is
1351 undefined, we can negate, because - (INT_MIN / 1) is an
1352 overflow. */
1354 {
1359 {
1366 }
1369 {
1376 }
1377 }
1381 /* Convert -((double)float) into (double)(-float). */
1383 {
1387 }
1391 /* Negate -f(x) as f(-x). */
1394 {
1400 }
1404 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1406 {
1411 {
1418 }
1419 }
1424 }
1427 }
1429 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1430 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1431 return NULL_TREE. */
1433 static tree
1435 {
1448 }
1449 \f
1450 /* Split a tree IN into a constant, literal and variable parts that could be
1451 combined with CODE to make IN. "constant" means an expression with
1452 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1453 commutative arithmetic operation. Store the constant part into *CONP,
1454 the literal in *LITP and return the variable part. If a part isn't
1455 present, set it to null. If the tree does not decompose in this way,
1456 return the entire tree as the variable part and the other parts as null.
1458 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1459 case, we negate an operand that was subtracted. Except if it is a
1460 literal for which we use *MINUS_LITP instead.
1462 If NEGATE_P is true, we are negating all of IN, again except a literal
1463 for which we use *MINUS_LITP instead.
1465 If IN is itself a literal or constant, return it as appropriate.
1467 Note that we do not guarantee that any of the three values will be the
1468 same type as IN, but they will have the same signedness and mode. */
1470 static tree
1473 {
1480 /* Strip any conversions that don't change the machine mode or signedness. */
1487 /* We can associate addition and subtraction together (even
1488 though the C standard doesn't say so) for integers because
1489 the value is not affected. For reals, the value might be
1490 affected, so we can't. */
1493 {
1499 /* First see if either of the operands is a literal, then a constant. */
1510 /* If we haven't dealt with either operand, this is not a case we can
1511 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1516 else
1519 /* Now do any needed negations. */
1526 }
1529 else
1533 {
1540 }
1543 }
1545 /* Re-associate trees split by the above function. T1 and T2 are either
1546 expressions to associate or null. Return the new expression, if any. If
1547 we build an operation, do it in TYPE and with CODE. */
1549 static tree
1551 {
1557 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1558 try to fold this since we will have infinite recursion. But do
1559 deal with any NEGATE_EXPRs. */
1562 {
1564 {
1573 }
1575 {
1578 }
1582 }
1586 }
1587 \f
1588 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1589 for use in int_const_binop, size_binop and size_diffop. */
1591 static bool
1593 {
1600 {
1609 }
1614 }
1617 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1618 to produce a new constant. Return NULL_TREE if we don't know how
1619 to evaluate CODE at compile-time.
1621 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1623 tree
1625 {
1629 HOST_WIDE_INT hi;
1631 HOST_WIDE_INT garbageh;
1632 tree t;
1635 int is_sizetype
1645 {
1661 /* It's unclear from the C standard whether shifts can overflow.
1662 The following code ignores overflow; perhaps a C standard
1663 interpretation ruling is needed. */
1692 /* This is a shortcut for a common special case. */
1697 {
1703 }
1705 /* ... fall through ... */
1711 {
1714 }
1717 {
1720 }
1727 /* This is a shortcut for a common special case. */
1732 {
1737 }
1739 /* ... fall through ... */
1757 else
1763 else
1769 }
1772 {
1775 /* Propagate overflow flags ourselves. */
1778 {
1781 }
1782 }
1783 else
1789 }
1791 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1792 constant. We assume ARG1 and ARG2 have the same data type, or at least
1793 are the same kind of constant and the same machine mode. Return zero if
1794 combining the constants is not allowed in the current operating mode.
1796 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1798 static tree
1800 {
1801 /* Sanity check for the recursive cases. */
1812 {
1814 REAL_VALUE_TYPE d1;
1815 REAL_VALUE_TYPE d2;
1816 REAL_VALUE_TYPE value;
1817 REAL_VALUE_TYPE result;
1821 /* The following codes are handled by real_arithmetic. */
1823 {
1834 }
1842 /* Don't perform operation if we honor signaling NaNs and
1843 either operand is a NaN. */
1848 /* Don't perform operation if it would raise a division
1849 by zero exception. */
1855 /* If either operand is a NaN, just return it. Otherwise, set up
1856 for floating-point trap; we return an overflow. */
1865 /* Don't constant fold this floating point operation if
1866 the result has overflowed and flag_trapping_math. */
1874 /* Don't constant fold this floating point operation if the
1875 result may dependent upon the run-time rounding mode and
1876 flag_rounding_math is set, or if GCC's software emulation
1877 is unable to accurately represent the result. */
1888 }
1891 {
1900 {
1911 notrunc);
1915 notrunc);
1919 {
1920 tree magsquared
1924 notrunc);
1925 tree t1
1929 notrunc);
1930 tree t2
1934 notrunc);
1941 }
1946 }
1950 }
1953 }
1955 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1956 indicates which particular sizetype to create. */
1958 tree
1960 {
1962 }
1963 \f
1964 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1965 is a tree code. The type of the result is taken from the operands.
1966 Both must be equivalent integer types, ala int_binop_types_match_p.
1967 If the operands are constant, so is the result. */
1969 tree
1971 {
1980 /* Handle the special case of two integer constants faster. */
1982 {
1983 /* And some specific cases even faster than that. */
1985 {
1990 }
1992 {
1995 }
1997 {
2000 }
2002 /* Handle general case of two integer constants. */
2004 }
2007 }
2009 /* Given two values, either both of sizetype or both of bitsizetype,
2010 compute the difference between the two values. Return the value
2011 in signed type corresponding to the type of the operands. */
2013 tree
2015 {
2017 tree ctype;
2022 /* If the type is already signed, just do the simple thing. */
2030 else
2033 /* If either operand is not a constant, do the conversions to the signed
2034 type and subtract. The hardware will do the right thing with any
2035 overflow in the subtraction. */
2040 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
2041 Otherwise, subtract the other way, convert to CTYPE (we know that can't
2042 overflow) and negate (which can't either). Special-case a result
2043 of zero while we're here. */
2048 else
2052 }
2053 \f
2054 /* A subroutine of fold_convert_const handling conversions of an
2055 INTEGER_CST to another integer type. */
2057 static tree
2059 {
2060 tree t;
2062 /* Given an integer constant, make new constant with new type,
2063 appropriately sign-extended or truncated. */
2066 /* Don't set the overflow when
2067 converting a pointer */
2075 }
2077 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2078 to an integer type. */
2080 static tree
2082 {
2084 tree t;
2086 /* The following code implements the floating point to integer
2087 conversion rules required by the Java Language Specification,
2088 that IEEE NaNs are mapped to zero and values that overflow
2089 the target precision saturate, i.e. values greater than
2090 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
2091 are mapped to INT_MIN. These semantics are allowed by the
2092 C and C++ standards that simply state that the behavior of
2093 FP-to-integer conversion is unspecified upon overflow. */
2096 REAL_VALUE_TYPE r;
2100 {
2107 }
2109 /* If R is NaN, return zero and show we have an overflow. */
2111 {
2115 }
2117 /* See if R is less than the lower bound or greater than the
2118 upper bound. */
2121 {
2125 {
2129 }
2130 }
2133 {
2136 {
2139 {
2143 }
2144 }
2145 }
2153 }
2155 /* A subroutine of fold_convert_const handling conversions a REAL_CST
2156 to another floating point type. */
2158 static tree
2160 {
2161 REAL_VALUE_TYPE value;
2162 tree t;
2169 }
2171 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2172 type TYPE. If no simplification can be done return NULL_TREE. */
2174 static tree
2176 {
2181 {
2186 }
2188 {
2193 }
2195 }
2197 /* Construct a vector of zero elements of vector type TYPE. */
2199 static tree
2201 {
2212 }
2214 /* Convert expression ARG to type TYPE. Used by the middle-end for
2215 simple conversions in preference to calling the front-end's convert. */
2217 tree
2219 {
2221 tree tem;
2237 {
2242 {
2246 }
2251 {
2254 }
2261 {
2265 }
2267 {
2271 }
2274 {
2289 }
2293 {
2302 {
2306 {
2310 }
2318 }
2322 }
2340 }
2341 }
2342 \f
2343 /* Return false if expr can be assumed not to be an lvalue, true
2344 otherwise. */
2346 static bool
2348 {
2349 /* We only need to wrap lvalue tree codes. */
2351 {
2386 /* Assume the worst for front-end tree codes. */
2390 }
2393 }
2395 /* Return an expr equal to X but certainly not valid as an lvalue. */
2397 tree
2399 {
2400 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2401 us. */
2408 }
2410 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2411 Zero means allow extended lvalues. */
2415 /* When pedantic, return an expr equal to X but certainly not valid as a
2416 pedantic lvalue. Otherwise, return X. */
2418 static tree
2420 {
2423 else
2425 }
2426 \f
2427 /* Given a tree comparison code, return the code that is the logical inverse
2428 of the given code. It is not safe to do this for floating-point
2429 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2430 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2432 enum tree_code
2434 {
2439 {
2470 }
2471 }
2473 /* Similar, but return the comparison that results if the operands are
2474 swapped. This is safe for floating-point. */
2476 enum tree_code
2478 {
2480 {
2506 }
2507 }
2510 /* Convert a comparison tree code from an enum tree_code representation
2511 into a compcode bit-based encoding. This function is the inverse of
2512 compcode_to_comparison. */
2514 static enum comparison_code
2516 {
2518 {
2549 }
2550 }
2552 /* Convert a compcode bit-based encoding of a comparison operator back
2553 to GCC's enum tree_code representation. This function is the
2554 inverse of comparison_to_compcode. */
2556 static enum tree_code
2558 {
2560 {
2591 }
2592 }
2594 /* Return a tree for the comparison which is the combination of
2595 doing the AND or OR (depending on CODE) of the two operations LCODE
2596 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2597 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2598 if this makes the transformation invalid. */
2600 tree
2604 {
2611 {
2622 }
2625 {
2626 /* Eliminate unordered comparisons, as well as LTGT and ORD
2627 which are not used unless the mode has NaNs. */
2633 }
2635 {
2636 /* Check that the original operation and the optimized ones will trap
2637 under the same condition. */
2648 /* In a short-circuited boolean expression the LHS might be
2649 such that the RHS, if evaluated, will never trap. For
2650 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2651 if neither x nor y is NaN. (This is a mixed blessing: for
2652 example, the expression above will never trap, hence
2653 optimizing it to x < y would be invalid). */
2658 /* If the comparison was short-circuited, and only the RHS
2659 trapped, we may now generate a spurious trap. */
2664 /* If we changed the conditions that cause a trap, we lose. */
2667 }
2673 else
2676 }
2678 /* Return nonzero if CODE is a tree code that represents a truth value. */
2680 static int
2682 {
2687 }
2688 \f
2689 /* Return nonzero if two operands (typically of the same tree node)
2690 are necessarily equal. If either argument has side-effects this
2691 function returns zero. FLAGS modifies behavior as follows:
2693 If OEP_ONLY_CONST is set, only return nonzero for constants.
2694 This function tests whether the operands are indistinguishable;
2695 it does not test whether they are equal using C's == operation.
2696 The distinction is important for IEEE floating point, because
2697 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2698 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2700 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2701 even though it may hold multiple values during a function.
2702 This is because a GCC tree node guarantees that nothing else is
2703 executed between the evaluation of its "operands" (which may often
2704 be evaluated in arbitrary order). Hence if the operands themselves
2705 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2706 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2707 unset means assuming isochronic (or instantaneous) tree equivalence.
2708 Unless comparing arbitrary expression trees, such as from different
2709 statements, this flag can usually be left unset.
2711 If OEP_PURE_SAME is set, then pure functions with identical arguments
2712 are considered the same. It is used when the caller has other ways
2713 to ensure that global memory is unchanged in between. */
2715 int
2717 {
2718 /* If either is ERROR_MARK, they aren't equal. */
2722 /* If both types don't have the same signedness, then we can't consider
2723 them equal. We must check this before the STRIP_NOPS calls
2724 because they may change the signedness of the arguments. */
2728 /* If both types don't have the same precision, then it is not safe
2729 to strip NOPs. */
2736 /* In case both args are comparisons but with different comparison
2737 code, try to swap the comparison operands of one arg to produce
2738 a match and compare that variant. */
2742 {
2750 }
2753 /* This is needed for conversions and for COMPONENT_REF.
2754 Might as well play it safe and always test this. */
2760 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2761 We don't care about side effects in that case because the SAVE_EXPR
2762 takes care of that for us. In all other cases, two expressions are
2763 equal if they have no side effects. If we have two identical
2764 expressions with side effects that should be treated the same due
2765 to the only side effects being identical SAVE_EXPR's, that will
2766 be detected in the recursive calls below. */
2772 /* Next handle constant cases, those for which we can return 1 even
2773 if ONLY_CONST is set. */
2776 {
2787 {
2788 /* If we do not distinguish between signed and unsigned zero,
2789 consider them equal. */
2792 }
2796 {
2802 {
2804 flags))
2808 }
2811 }
2815 flags)
2817 flags));
2830 }
2835 /* Define macros to test an operand from arg0 and arg1 for equality and a
2836 variant that allows null and views null as being different from any
2837 non-null value. In the latter case, if either is null, the both
2838 must be; otherwise, do the normal comparison. */
2839 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2840 TREE_OPERAND (arg1, N), flags)
2842 #define OP_SAME_WITH_NULL(N) \
2843 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2844 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2847 {
2849 /* Two conversions are equal only if signedness and modes match. */
2851 {
2861 }
2871 /* For commutative ops, allow the other order. */
2879 /* If either of the pointer (or reference) expressions we are
2880 dereferencing contain a side effect, these cannot be equal. */
2886 {
2896 /* Operands 2 and 3 may be null.
2897 Compare the array index by value if it is constant first as we
2898 may have different types but same value here. */
2907 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2908 may be NULL when we're called to compare MEM_EXPRs. */
2918 }
2922 {
2937 /* Otherwise take into account this is a commutative operation. */
2945 }
2949 {
2951 /* If the CALL_EXPRs call different functions, then they
2952 clearly can not be equal. */
2954 flags))
2957 {
2961 else
2965 }
2967 /* Now see if all the arguments are the same. */
2968 {
2979 /* If we get here and both argument lists are exhausted
2980 then the CALL_EXPRs are equal. */
2982 }
2985 }
2988 /* Consider __builtin_sqrt equal to sqrt. */
2996 }
2998 #undef OP_SAME
2999 #undef OP_SAME_WITH_NULL
3000 }
3001 \f
3002 /* Similar to operand_equal_p, but see if ARG0 might have been made by
3003 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
3005 When in doubt, return 0. */
3007 static int
3009 {
3021 /* Discard any conversions that don't change the modes of ARG0 and ARG1
3022 and see if the inner values are the same. This removes any
3023 signedness comparison, which doesn't matter here. */
3030 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
3031 actual comparison operand, ARG0.
3033 First throw away any conversions to wider types
3034 already present in the operands. */
3043 {
3046 /* Make sure shorter operand is extended the right way
3047 to match the longer operand. */
3053 }
3056 }
3057 \f
3058 /* See if ARG is an expression that is either a comparison or is performing
3059 arithmetic on comparisons. The comparisons must only be comparing
3060 two different values, which will be stored in *CVAL1 and *CVAL2; if
3061 they are nonzero it means that some operands have already been found.
3062 No variables may be used anywhere else in the expression except in the
3063 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
3064 the expression and save_expr needs to be called with CVAL1 and CVAL2.
3066 If this is true, return 1. Otherwise, return zero. */
3068 static int
3070 {
3074 /* We can handle some of the tcc_expression cases here. */
3084 {
3085 /* If we've already found a CVAL1 or CVAL2, this expression is
3086 two complex to handle. */
3092 }
3095 {
3118 /* First see if we can handle the first operand, then the second. For
3119 the second operand, we know *CVAL1 can't be zero. It must be that
3120 one side of the comparison is each of the values; test for the
3121 case where this isn't true by failing if the two operands
3122 are the same. */
3131 ;
3135 ;
3136 else
3140 ;
3144 ;
3145 else
3152 }
3153 }
3154 \f
3155 /* ARG is a tree that is known to contain just arithmetic operations and
3156 comparisons. Evaluate the operations in the tree substituting NEW0 for
3157 any occurrence of OLD0 as an operand of a comparison and likewise for
3158 NEW1 and OLD1. */
3160 static tree
3162 {
3167 /* We can handle some of the tcc_expression cases here. */
3175 {
3190 {
3207 }
3208 /* Fall through - ??? */
3211 {
3215 /* We need to check both for exact equality and tree equality. The
3216 former will be true if the operand has a side-effect. In that
3217 case, we know the operand occurred exactly once. */
3230 }
3234 }
3235 }
3236 \f
3237 /* Return a tree for the case when the result of an expression is RESULT
3238 converted to TYPE and OMITTED was previously an operand of the expression
3239 but is now not needed (e.g., we folded OMITTED * 0).
3241 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3242 the conversion of RESULT to TYPE. */
3244 tree
3246 {
3253 }
3255 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3257 static tree
3259 {
3266 }
3268 /* Return a tree for the case when the result of an expression is RESULT
3269 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3270 of the expression but are now not needed.
3272 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3273 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3274 evaluated before OMITTED2. Otherwise, if neither has side effects,
3275 just do the conversion of RESULT to TYPE. */
3277 tree
3279 {
3288 }
3290 \f
3291 /* Return a simplified tree node for the truth-negation of ARG. This
3292 never alters ARG itself. We assume that ARG is an operation that
3293 returns a truth value (0 or 1).
3295 FIXME: one would think we would fold the result, but it causes
3296 problems with the dominator optimizer. */
3298 tree
3300 {
3304 /* If this is a comparison, we can simply invert it, except for
3305 floating-point non-equality comparisons, in which case we just
3306 enclose a TRUTH_NOT_EXPR around what we have. */
3309 {
3312 && flag_trapping_math
3316 else
3317 {
3322 else
3325 }
3326 }
3329 {
3344 /* Here we can invert either operand. We invert the first operand
3345 unless the second operand is a TRUTH_NOT_EXPR in which case our
3346 result is the XOR of the first operand with the inside of the
3347 negation of the second operand. */
3352 else
3371 {
3374 /* A COND_EXPR may have a throw as one operand, which
3375 then has void type. Just leave void operands
3376 as they are. */
3382 }
3415 }
3418 }
3420 /* Return a simplified tree node for the truth-negation of ARG. This
3421 never alters ARG itself. We assume that ARG is an operation that
3422 returns a truth value (0 or 1).
3424 FIXME: one would think we would fold the result, but it causes
3425 problems with the dominator optimizer. */
3427 tree
3429 {
3430 tree tem;
3440 }
3442 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3443 operands are another bit-wise operation with a common input. If so,
3444 distribute the bit operations to save an operation and possibly two if
3445 constants are involved. For example, convert
3446 (A | B) & (A | C) into A | (B & C)
3447 Further simplification will occur if B and C are constants.
3449 If this optimization cannot be done, 0 will be returned. */
3451 static tree
3453 {
3454 tree common;
3464 {
3468 }
3470 {
3474 }
3476 {
3480 }
3482 {
3486 }
3487 else
3492 }
3494 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3495 with code CODE. This optimization is unsafe. */
3496 static tree
3498 {
3502 /* (A / C) +- (B / C) -> (A +- B) / C. */
3512 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3517 {
3529 }
3532 }
3533 \f
3534 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3535 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3537 static tree
3540 {
3541 tree result;
3544 {
3551 }
3559 }
3561 /* Optimize a bit-field compare.
3563 There are two cases: First is a compare against a constant and the
3564 second is a comparison of two items where the fields are at the same
3565 bit position relative to the start of a chunk (byte, halfword, word)
3566 large enough to contain it. In these cases we can avoid the shift
3567 implicit in bitfield extractions.
3569 For constants, we emit a compare of the shifted constant with the
3570 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3571 compared. For two fields at the same position, we do the ANDs with the
3572 similar mask and compare the result of the ANDs.
3574 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3575 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3576 are the left and right operands of the comparison, respectively.
3578 If the optimization described above can be done, we return the resulting
3579 tree. Otherwise we return zero. */
3581 static tree
3584 {
3593 tree mask;
3594 tree offset;
3596 /* Get all the information about the extractions being done. If the bit size
3597 if the same as the size of the underlying object, we aren't doing an
3598 extraction at all and so can do nothing. We also don't want to
3599 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3600 then will no longer be able to replace it. */
3608 {
3609 /* If this is not a constant, we can only do something if bit positions,
3610 sizes, and signedness are the same. */
3618 }
3620 /* See if we can find a mode to refer to this field. We should be able to,
3621 but fail if we can't. */
3630 /* Set signed and unsigned types of the precision of this mode for the
3631 shifts below. */
3635 /* Compute the bit position and size for the new reference and our offset
3636 within it. If the new reference is the same size as the original, we
3637 won't optimize anything, so return zero. */
3647 /* Make the mask to be used against the extracted field. */
3654 /* If not comparing with constant, just rework the comparison
3655 and return. */
3659 unsigned_type,
3662 mask),
3665 unsigned_type,
3668 mask));
3670 /* Otherwise, we are handling the constant case. See if the constant is too
3671 big for the field. Warn and return a tree of for 0 (false) if so. We do
3672 this not only for its own sake, but to avoid having to test for this
3673 error case below. If we didn't, we might generate wrong code.
3675 For unsigned fields, the constant shifted right by the field length should
3676 be all zero. For signed fields, the high-order bits should agree with
3677 the sign bit. */
3680 {
3684 {
3688 }
3689 }
3690 else
3691 {
3695 {
3699 }
3700 }
3702 /* Single-bit compares should always be against zero. */
3704 {
3707 }
3709 /* Make a new bitfield reference, shift the constant over the
3710 appropriate number of bits and mask it with the computed mask
3711 (in case this was a signed field). If we changed it, make a new one. */
3714 {
3717 }
3727 rhs);
3728 }
3729 \f
3730 /* Subroutine for fold_truthop: decode a field reference.
3732 If EXP is a comparison reference, we return the innermost reference.
3734 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3735 set to the starting bit number.
3737 If the innermost field can be completely contained in a mode-sized
3738 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3740 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3741 otherwise it is not changed.
3743 *PUNSIGNEDP is set to the signedness of the field.
3745 *PMASK is set to the mask used. This is either contained in a
3746 BIT_AND_EXPR or derived from the width of the field.
3748 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3750 Return 0 if this is not a component reference or is one that we can't
3751 do anything with. */
3753 static tree
3758 {
3762 tree unsigned_type;
3765 /* All the optimizations using this function assume integer fields.
3766 There are problems with FP fields since the type_for_size call
3767 below can fail for, e.g., XFmode. */
3771 /* We are interested in the bare arrangement of bits, so strip everything
3772 that doesn't affect the machine mode. However, record the type of the
3773 outermost expression if it may matter below. */
3781 {
3787 }
3796 /* If the number of bits in the reference is the same as the bitsize of
3797 the outer type, then the outer type gives the signedness. Otherwise
3798 (in case of a small bitfield) the signedness is unchanged. */
3802 /* Compute the mask to access the bitfield. */
3811 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3819 }
3821 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3822 bit positions. */
3824 static int
3826 {
3829 tree tmask;
3833 return
3840 }
3842 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3843 represents the sign bit of EXP's type. If EXP represents a sign
3844 or zero extension, also test VAL against the unextended type.
3845 The return value is the (sub)expression whose sign bit is VAL,
3846 or NULL_TREE otherwise. */
3848 static tree
3850 {
3854 tree t;
3856 /* Tree EXP must have an integral type. */
3861 /* Tree VAL must be an integer constant. */
3868 {
3875 }
3876 else
3877 {
3884 }
3886 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3887 treat VAL as if it were unsigned. */
3892 /* Handle extension from a narrower type. */
3898 }
3900 /* Subroutine for fold_truthop: determine if an operand is simple enough
3901 to be evaluated unconditionally. */
3903 static int
3905 {
3906 /* Strip any conversions that don't change the machine mode. */
3915 /* Don't regard global variables as simple. They may be
3916 allocated in ways unknown to the compiler (shared memory,
3917 #pragma weak, etc). */
3920 /* Loading a static variable is unduly expensive, but global
3921 registers aren't expensive. */
3923 }
3924 \f
3925 /* The following functions are subroutines to fold_range_test and allow it to
3926 try to change a logical combination of comparisons into a range test.
3928 For example, both
3929 X == 2 || X == 3 || X == 4 || X == 5
3930 and
3931 X >= 2 && X <= 5
3932 are converted to
3933 (unsigned) (X - 2) <= 3
3935 We describe each set of comparisons as being either inside or outside
3936 a range, using a variable named like IN_P, and then describe the
3937 range with a lower and upper bound. If one of the bounds is omitted,
3938 it represents either the highest or lowest value of the type.
3940 In the comments below, we represent a range by two numbers in brackets
3941 preceded by a "+" to designate being inside that range, or a "-" to
3942 designate being outside that range, so the condition can be inverted by
3943 flipping the prefix. An omitted bound is represented by a "-". For
3944 example, "- [-, 10]" means being outside the range starting at the lowest
3945 possible value and ending at 10, in other words, being greater than 10.
3946 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3947 always false.
3949 We set up things so that the missing bounds are handled in a consistent
3950 manner so neither a missing bound nor "true" and "false" need to be
3951 handled using a special case. */
3953 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3954 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3955 and UPPER1_P are nonzero if the respective argument is an upper bound
3956 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3957 must be specified for a comparison. ARG1 will be converted to ARG0's
3958 type if both are specified. */
3960 static tree
3963 {
3964 tree tem;
3968 /* If neither arg represents infinity, do the normal operation.
3969 Else, if not a comparison, return infinity. Else handle the special
3970 comparison rules. Note that most of the cases below won't occur, but
3971 are handled for consistency. */
3974 {
3979 }
3984 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3985 for neither. In real maths, we cannot assume open ended ranges are
3986 the same. But, this is computer arithmetic, where numbers are finite.
3987 We can therefore make the transformation of any unbounded range with
3988 the value Z, Z being greater than any representable number. This permits
3989 us to treat unbounded ranges as equal. */
3993 {
4014 }
4017 }
4018 \f
4019 /* Given EXP, a logical expression, set the range it is testing into
4020 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
4021 actually being tested. *PLOW and *PHIGH will be made of the same
4022 type as the returned expression. If EXP is not a comparison, we
4023 will most likely not be returning a useful value and range. Set
4024 *STRICT_OVERFLOW_P to true if the return value is only valid
4025 because signed overflow is undefined; otherwise, do not change
4026 *STRICT_OVERFLOW_P. */
4028 static tree
4031 {
4038 /* Start with simply saying "EXP != 0" and then look at the code of EXP
4039 and see if we can refine the range. Some of the cases below may not
4040 happen, but it doesn't seem worth worrying about this. We "continue"
4041 the outer loop when we've changed something; otherwise we "break"
4042 the switch, which will "break" the while. */
4048 {
4053 {
4065 }
4068 {
4075 /* We can only do something if the range is testing for zero
4076 and if the second operand is an integer constant. Note that
4077 saying something is "in" the range we make is done by
4078 complementing IN_P since it will set in the initial case of
4079 being not equal to zero; "out" is leaving it alone. */
4086 {
4107 }
4109 /* If this is an unsigned comparison, we also know that EXP is
4110 greater than or equal to zero. We base the range tests we make
4111 on that fact, so we record it here so we can parse existing
4112 range tests. We test arg0_type since often the return type
4113 of, e.g. EQ_EXPR, is boolean. */
4115 {
4119 NULL_TREE))
4124 /* If the high bound is missing, but we have a nonzero low
4125 bound, reverse the range so it goes from zero to the low bound
4126 minus 1. */
4128 {
4133 }
4134 }
4140 /* (-x) IN [a,b] -> x in [-b, -a] */
4152 /* ~ X -> -X - 1 */
4161 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
4162 move a constant to the other side. */
4167 /* If EXP is signed, any overflow in the computation is undefined,
4168 so we don't worry about it so long as our computations on
4169 the bounds don't overflow. For unsigned, overflow is defined
4170 and this is exactly the right thing. */
4182 /* Check for an unsigned range which has wrapped around the maximum
4183 value thus making n_high < n_low, and normalize it. */
4185 {
4191 /* If the range is of the form +/- [ x+1, x ], we won't
4192 be able to normalize it. But then, it represents the
4193 whole range or the empty set, so make it
4194 +/- [ -, - ]. */
4198 else
4200 }
4201 else
4225 /* If we're converting arg0 from an unsigned type, to exp,
4226 a signed type, we will be doing the comparison as unsigned.
4227 The tests above have already verified that LOW and HIGH
4228 are both positive.
4230 So we have to ensure that we will handle large unsigned
4231 values the same way that the current signed bounds treat
4232 negative values. */
4235 {
4236 tree high_positive;
4240 /* A range without an upper bound is, naturally, unbounded.
4241 Since convert would have cropped a very large value, use
4242 the max value for the destination type. */
4243 high_positive
4250 high_positive),
4253 /* If the low bound is specified, "and" the range with the
4254 range for which the original unsigned value will be
4255 positive. */
4257 {
4261 integer_zero_node),
4262 high_positive))
4266 }
4267 else
4268 {
4269 /* Otherwise, "or" the range with the range of the input
4270 that will be interpreted as negative. */
4274 integer_zero_node),
4275 high_positive))
4279 }
4280 }
4288 }
4291 }
4293 /* If EXP is a constant, we can evaluate whether this is true or false. */
4295 {
4302 }
4306 }
4307 \f
4308 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4309 type, TYPE, return an expression to test if EXP is in (or out of, depending
4310 on IN_P) the range. Return 0 if the test couldn't be created. */
4312 static tree
4314 {
4316 tree value;
4318 #ifdef HAVE_canonicalize_funcptr_for_compare
4319 /* Disable this optimization for function pointer expressions
4320 on targets that require function pointer canonicalization. */
4325 #endif
4328 {
4334 }
4352 {
4354 {
4358 }
4360 }
4362 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4364 {
4366 HOST_WIDE_INT hi;
4371 {
4374 }
4375 else
4376 {
4379 }
4382 {
4384 {
4387 }
4390 }
4391 }
4393 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4394 This requires wrap-around arithmetics for the type of the expression. */
4396 {
4398 /* There is no requirement that LOW be within the range of ETYPE
4399 if the latter is a subtype. It must, however, be within the base
4400 type of ETYPE. So be sure we do the subtraction in that type. */
4413 }
4415 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4418 {
4421 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4422 for the type in question, as we rely on this here. */
4432 else
4434 }
4448 }
4449 \f
4450 /* Return the predecessor of VAL in its type, handling the infinite case. */
4452 static tree
4454 {
4460 else
4462 }
4464 /* Return the successor of VAL in its type, handling the infinite case. */
4466 static tree
4468 {
4474 else
4476 }
4478 /* Given two ranges, see if we can merge them into one. Return 1 if we
4479 can, 0 if we can't. Set the output range into the specified parameters. */
4481 static int
4484 {
4488 tree tem;
4498 /* Make range 0 be the range that starts first, or ends last if they
4499 start at the same value. Swap them if it isn't. */
4502 || (lowequal
4505 {
4509 }
4511 /* Now flag two cases, whether the ranges are disjoint or whether the
4512 second range is totally subsumed in the first. Note that the tests
4513 below are simplified by the ones above. */
4519 /* We now have four cases, depending on whether we are including or
4520 excluding the two ranges. */
4522 {
4523 /* If they don't overlap, the result is false. If the second range
4524 is a subset it is the result. Otherwise, the range is from the start
4525 of the second to the end of the first. */
4530 else
4532 }
4535 {
4536 /* If they don't overlap, the result is the first range. If they are
4537 equal, the result is false. If the second range is a subset of the
4538 first, and the ranges begin at the same place, we go from just after
4539 the end of the second range to the end of the first. If the second
4540 range is not a subset of the first, or if it is a subset and both
4541 ranges end at the same place, the range starts at the start of the
4542 first range and ends just before the second range.
4543 Otherwise, we can't describe this as a single range. */
4549 {
4553 }
4555 {
4559 }
4560 else
4562 }
4565 {
4566 /* If they don't overlap, the result is the second range. If the second
4567 is a subset of the first, the result is false. Otherwise,
4568 the range starts just after the first range and ends at the
4569 end of the second. */
4574 else
4575 {
4579 }
4580 }
4582 else
4583 {
4584 /* The case where we are excluding both ranges. Here the complex case
4585 is if they don't overlap. In that case, the only time we have a
4586 range is if they are adjacent. If the second is a subset of the
4587 first, the result is the first. Otherwise, the range to exclude
4588 starts at the beginning of the first range and ends at the end of the
4589 second. */
4591 {
4596 else
4597 {
4598 /* Canonicalize - [min, x] into - [-, x]. */
4601 {
4606 /* FALLTHROUGH */
4619 }
4621 /* Canonicalize - [x, max] into - [x, -]. */
4624 {
4629 /* FALLTHROUGH */
4644 }
4646 /* The ranges might be also adjacent between the maximum and
4647 minimum values of the given type. For
4648 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4649 return + [x + 1, y - 1]. */
4651 {
4658 }
4659 else
4661 }
4662 }
4665 else
4667 }
4671 }
4672 \f
4674 /* Subroutine of fold, looking inside expressions of the form
4675 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4676 of the COND_EXPR. This function is being used also to optimize
4677 A op B ? C : A, by reversing the comparison first.
4679 Return a folded expression whose code is not a COND_EXPR
4680 anymore, or NULL_TREE if no folding opportunity is found. */
4682 static tree
4684 {
4689 tree tem;
4694 /* If we have A op 0 ? A : -A, consider applying the following
4695 transformations:
4697 A == 0? A : -A same as -A
4698 A != 0? A : -A same as A
4699 A >= 0? A : -A same as abs (A)
4700 A > 0? A : -A same as abs (A)
4701 A <= 0? A : -A same as -abs (A)
4702 A < 0? A : -A same as -abs (A)
4704 None of these transformations work for modes with signed
4705 zeros. If A is +/-0, the first two transformations will
4706 change the sign of the result (from +0 to -0, or vice
4707 versa). The last four will fix the sign of the result,
4708 even though the original expressions could be positive or
4709 negative, depending on the sign of A.
4711 Note that all these transformations are correct if A is
4712 NaN, since the two alternatives (A and -A) are also NaNs. */
4718 /* In the case that A is of the form X-Y, '-A' (arg2) may
4719 have already been folded to Y-X, check for that. */
4727 {
4739 /* Fall through. */
4761 }
4763 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4764 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4765 both transformations are correct when A is NaN: A != 0
4766 is then true, and A == 0 is false. */
4769 {
4774 }
4776 /* Try some transformations of A op B ? A : B.
4778 A == B? A : B same as B
4779 A != B? A : B same as A
4780 A >= B? A : B same as max (A, B)
4781 A > B? A : B same as max (B, A)
4782 A <= B? A : B same as min (A, B)
4783 A < B? A : B same as min (B, A)
4785 As above, these transformations don't work in the presence
4786 of signed zeros. For example, if A and B are zeros of
4787 opposite sign, the first two transformations will change
4788 the sign of the result. In the last four, the original
4789 expressions give different results for (A=+0, B=-0) and
4790 (A=-0, B=+0), but the transformed expressions do not.
4792 The first two transformations are correct if either A or B
4793 is a NaN. In the first transformation, the condition will
4794 be false, and B will indeed be chosen. In the case of the
4795 second transformation, the condition A != B will be true,
4796 and A will be chosen.
4798 The conversions to max() and min() are not correct if B is
4799 a number and A is not. The conditions in the original
4800 expressions will be false, so all four give B. The min()
4801 and max() versions would give a NaN instead. */
4803 /* Avoid these transformations if the COND_EXPR may be used
4804 as an lvalue in the C++ front-end. PR c++/19199. */
4805 && (in_gimple_form
4810 {
4815 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4817 {
4821 }
4824 {
4833 /* In C++ a ?: expression can be an lvalue, so put the
4834 operand which will be used if they are equal first
4835 so that we can convert this back to the
4836 corresponding COND_EXPR. */
4838 {
4845 }
4852 {
4859 }
4872 }
4873 }
4875 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4876 we might still be able to simplify this. For example,
4877 if C1 is one less or one more than C2, this might have started
4878 out as a MIN or MAX and been transformed by this function.
4879 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4885 {
4887 /* We can replace A with C1 in this case. */
4892 /* If C1 is C2 + 1, this is min(A, C2). */
4894 OEP_ONLY_CONST)
4898 OEP_ONLY_CONST))
4904 /* If C1 is C2 - 1, this is min(A, C2). */
4906 OEP_ONLY_CONST)
4910 OEP_ONLY_CONST))
4916 /* If C1 is C2 - 1, this is max(A, C2). */
4918 OEP_ONLY_CONST)
4922 OEP_ONLY_CONST))
4928 /* If C1 is C2 + 1, this is max(A, C2). */
4930 OEP_ONLY_CONST)
4934 OEP_ONLY_CONST))
4942 }
4945 }
4948 \f
4949 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4950 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4951 #endif
4953 /* EXP is some logical combination of boolean tests. See if we can
4954 merge it into some range test. Return the new tree if so. */
4956 static tree
4958 {
4966 tree tem;
4970 /* If this is an OR operation, invert both sides; we will invert
4971 again at the end. */
4975 /* If both expressions are the same, if we can merge the ranges, and we
4976 can build the range test, return it or it inverted. If one of the
4977 ranges is always true or always false, consider it to be the same
4978 expression as the other. */
4986 {
4990 }
4992 /* On machines where the branch cost is expensive, if this is a
4993 short-circuited branch and the underlying object on both sides
4994 is the same, make a non-short-circuit operation. */
5000 {
5001 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
5002 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
5003 which cases we can't do this. */
5011 {
5020 {
5023 WARN_STRICT_OVERFLOW_COMPARISON);
5027 }
5028 }
5029 }
5032 }
5033 \f
5034 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
5035 bit value. Arrange things so the extra bits will be set to zero if and
5036 only if C is signed-extended to its full width. If MASK is nonzero,
5037 it is an INTEGER_CST that should be AND'ed with the extra bits. */
5039 static tree
5041 {
5044 tree temp;
5049 /* We work by getting just the sign bit into the low-order bit, then
5050 into the high-order bit, then sign-extend. We then XOR that value
5051 with C. */
5055 /* We must use a signed type in order to get an arithmetic right shift.
5056 However, we must also avoid introducing accidental overflows, so that
5057 a subsequent call to integer_zerop will work. Hence we must
5058 do the type conversion here. At this point, the constant is either
5059 zero or one, and the conversion to a signed type can never overflow.
5060 We could get an overflow if this conversion is done anywhere else. */
5069 /* If necessary, convert the type back to match the type of C. */
5074 }
5075 \f
5076 /* Find ways of folding logical expressions of LHS and RHS:
5077 Try to merge two comparisons to the same innermost item.
5078 Look for range tests like "ch >= '0' && ch <= '9'".
5079 Look for combinations of simple terms on machines with expensive branches
5080 and evaluate the RHS unconditionally.
5082 For example, if we have p->a == 2 && p->b == 4 and we can make an
5083 object large enough to span both A and B, we can do this with a comparison
5084 against the object ANDed with the a mask.
5086 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
5087 operations to do this with one comparison.
5089 We check for both normal comparisons and the BIT_AND_EXPRs made this by
5090 function and the one above.
5092 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
5093 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
5095 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
5096 two operands.
5098 We return the simplified tree or 0 if no optimization is possible. */
5100 static tree
5102 {
5103 /* If this is the "or" of two comparisons, we can do something if
5104 the comparisons are NE_EXPR. If this is the "and", we can do something
5105 if the comparisons are EQ_EXPR. I.e.,
5106 (a->b == 2 && a->c == 4) can become (a->new == NEW).
5108 WANTED_CODE is this operation code. For single bit fields, we can
5109 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
5110 comparison for one-bit fields. */
5132 /* Start by getting the comparison codes. Fail if anything is volatile.
5133 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
5134 it were surrounded with a NE_EXPR. */
5143 {
5147 }
5150 {
5154 }
5165 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
5168 {
5169 tree result;
5172 {
5177 }
5180 {
5186 }
5187 }
5192 /* If the RHS can be evaluated unconditionally and its operands are
5193 simple, it wins to evaluate the RHS unconditionally on machines
5194 with expensive branches. In this case, this isn't a comparison
5195 that can be merged. Avoid doing this if the RHS is a floating-point
5196 comparison since those can trap. */
5202 {
5203 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5213 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5224 {
5228 }
5229 }
5231 /* See if the comparisons can be merged. Then get all the parameters for
5232 each side. */
5256 /* It must be true that the inner operation on the lhs of each
5257 comparison must be the same if we are to be able to do anything.
5258 Then see if we have constants. If not, the same must be true for
5259 the rhs's. */
5270 else
5273 /* If either comparison code is not correct for our logical operation,
5274 fail. However, we can convert a one-bit comparison against zero into
5275 the opposite comparison against that bit being set in the field. */
5279 {
5281 {
5282 /* Make the left operand unsigned, since we are only interested
5283 in the value of one bit. Otherwise we are doing the wrong
5284 thing below. */
5287 }
5288 else
5290 }
5292 /* This is analogous to the code for l_const above. */
5294 {
5296 {
5299 }
5300 else
5302 }
5304 /* See if we can find a mode that contains both fields being compared on
5305 the left. If we can't, fail. Otherwise, update all constants and masks
5306 to be relative to a field of that size. */
5311 volatilep);
5321 {
5324 }
5332 {
5340 {
5344 }
5345 }
5347 {
5355 {
5359 }
5360 }
5362 /* If the right sides are not constant, do the same for it. Also,
5363 disallow this optimization if a size or signedness mismatch occurs
5364 between the left and right sides. */
5366 {
5369 /* Make sure the two fields on the right
5370 correspond to the left without being swapped. */
5378 volatilep);
5388 {
5391 }
5398 /* Make a mask that corresponds to both fields being compared.
5399 Do this for both items being compared. If the operands are the
5400 same size and the bits being compared are in the same position
5401 then we can do this by masking both and comparing the masked
5402 results. */
5406 {
5418 }
5420 /* There is still another way we can do something: If both pairs of
5421 fields being compared are adjacent, we may be able to make a wider
5422 field containing them both.
5424 Note that we still must mask the lhs/rhs expressions. Furthermore,
5425 the mask must be shifted to account for the shift done by
5426 make_bit_field_ref. */
5431 {
5432 tree type;
5444 /* Convert to the smaller type before masking out unwanted bits. */
5447 {
5449 {
5453 }
5455 {
5459 }
5460 }
5469 }
5472 }
5474 /* Handle the case of comparisons with constants. If there is something in
5475 common between the masks, those bits of the constants must be the same.
5476 If not, the condition is always false. Test for this to avoid generating
5477 incorrect code below. */
5482 {
5484 {
5487 }
5488 else
5489 {
5492 }
5493 }
5495 /* Construct the expression we will return. First get the component
5496 reference we will make. Unless the mask is all ones the width of
5497 that field, perform the mask operation. Then compare with the
5498 merged constant. */
5508 }
5509 \f
5510 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5511 constant. */
5513 static tree
5515 {
5519 tree minmax_const;
5521 tree inner;
5531 /* If something does not permit us to optimize, return the original tree. */
5539 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5540 and GT_EXPR, doing the rest with recursive calls using logical
5541 simplifications. */
5543 {
5545 {
5551 }
5554 return
5556 optimize_minmax_comparison
5558 optimize_minmax_comparison
5563 /* MAX (X, 0) == 0 -> X <= 0 */
5567 /* MAX (X, 0) == 5 -> X == 5 */
5571 /* MAX (X, 0) == -1 -> false */
5575 /* MIN (X, 0) == 0 -> X >= 0 */
5579 /* MIN (X, 0) == 5 -> false */
5582 else
5583 /* MIN (X, 0) == -1 -> X == -1 */
5588 /* MAX (X, 0) > 0 -> X > 0
5589 MAX (X, 0) > 5 -> X > 5 */
5593 /* MAX (X, 0) > -1 -> true */
5597 /* MIN (X, 0) > 0 -> false
5598 MIN (X, 0) > 5 -> false */
5601 else
5602 /* MIN (X, 0) > -1 -> X > -1 */
5607 }
5608 }
5609 \f
5610 /* T is an integer expression that is being multiplied, divided, or taken a
5611 modulus (CODE says which and what kind of divide or modulus) by a
5612 constant C. See if we can eliminate that operation by folding it with
5613 other operations already in T. WIDE_TYPE, if non-null, is a type that
5614 should be used for the computation if wider than our type.
5616 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5617 (X * 2) + (Y * 4). We must, however, be assured that either the original
5618 expression would not overflow or that overflow is undefined for the type
5619 in the language in question.
5621 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5622 the machine has a multiply-accumulate insn or that this is part of an
5623 addressing calculation.
5625 If we return a non-null expression, it is an equivalent form of the
5626 original computation, but need not be in the original type.
5628 We set *STRICT_OVERFLOW_P to true if the return values depends on
5629 signed overflow being undefined. Otherwise we do not change
5630 *STRICT_OVERFLOW_P. */
5632 static tree
5635 {
5636 /* To avoid exponential search depth, refuse to allow recursion past
5637 three levels. Beyond that (1) it's highly unlikely that we'll find
5638 something interesting and (2) we've probably processed it before
5639 when we built the inner expression. */
5642 tree ret;
5647 depth++;
5649 depth--;
5652 }
5654 static tree
5657 {
5668 /* Don't deal with constants of zero here; they confuse the code below. */
5678 /* Note that we need not handle conditional operations here since fold
5679 already handles those cases. So just do arithmetic here. */
5681 {
5683 /* For a constant, we can always simplify if we are a multiply
5684 or (for divide and modulus) if it is a multiple of our constant. */
5692 /* If op0 is an expression ... */
5698 /* ... and is unsigned, and its type is smaller than ctype,
5699 then we cannot pass through as widening. */
5705 /* ... or this is a truncation (t is narrower than op0),
5706 then we cannot pass through this narrowing. */
5709 /* ... or signedness changes for division or modulus,
5710 then we cannot pass through this conversion. */
5716 /* Pass the constant down and see if we can make a simplification. If
5717 we can, replace this expression with the inner simplification for
5718 possible later conversion to our or some other type. */
5723 code == MULT_EXPR
5725 strict_overflow_p))))
5730 /* If widening the type changes it from signed to unsigned, then we
5731 must avoid building ABS_EXPR itself as unsigned. */
5733 {
5737 {
5740 }
5742 }
5743 /* FALLTHROUGH */
5751 /* If widening the type changes the signedness, then we can't perform
5752 this optimization as that changes the result. */
5756 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5762 {
5769 }
5773 /* If the second operand is constant, this is a multiplication
5774 or floor division, by a power of two, so we can treat it that
5775 way unless the multiplier or divisor overflows. Signed
5776 left-shift overflow is implementation-defined rather than
5777 undefined in C90, so do not convert signed left shift into
5778 multiplication. */
5781 /* const_binop may not detect overflow correctly,
5782 so check for it explicitly here. */
5787 size_one_node,
5797 /* See if we can eliminate the operation on both sides. If we can, we
5798 can return a new PLUS or MINUS. If we can't, the only remaining
5799 cases where we can do anything are if the second operand is a
5800 constant. */
5806 /* If not multiplication, we can only do this if both operands
5807 are divisible by c. */
5810 {
5815 }
5817 /* If this was a subtraction, negate OP1 and set it to be an addition.
5818 This simplifies the logic below. */
5825 /* If either OP1 or C are negative, this optimization is not safe for
5826 some of the division and remainder types while for others we need
5827 to change the code. */
5829 {
5837 }
5839 /* If it's a multiply or a division/modulus operation of a multiple
5840 of our constant, do the operation and verify it doesn't overflow. */
5843 {
5846 /* We allow the constant to overflow with wrapping semantics. */
5850 }
5851 else
5854 /* If we have an unsigned type is not a sizetype, we cannot widen
5855 the operation since it will change the result if the original
5856 computation overflowed. */
5862 /* If we were able to eliminate our operation from the first side,
5863 apply our operation to the second side and reform the PLUS. */
5867 /* The last case is if we are a multiply. In that case, we can
5868 apply the distributive law to commute the multiply and addition
5869 if the multiplication of the constants doesn't overflow. */
5875 op1);
5880 /* We have a special case here if we are doing something like
5881 (C * 8) % 4 since we know that's zero. */
5888 /* ... fall through ... */
5892 /* If we can extract our operation from the LHS, do so and return a
5893 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5894 do something only if the second operand is a constant. */
5908 /* If these are the same operation types, we can associate them
5909 assuming no overflow. */
5916 /* If these operations "cancel" each other, we have the main
5917 optimizations of this pass, which occur when either constant is a
5918 multiple of the other, in which case we replace this with either an
5919 operation or CODE or TCODE.
5921 If we have an unsigned type that is not a sizetype, we cannot do
5922 this since it will change the result if the original computation
5923 overflowed. */
5930 {
5932 {
5939 }
5941 {
5948 }
5949 }
5954 }
5957 }
5958 \f
5959 /* Return a node which has the indicated constant VALUE (either 0 or
5960 1), and is of the indicated TYPE. */
5962 tree
5964 {
5969 else
5971 }
5974 /* Return true if expr looks like an ARRAY_REF and set base and
5975 offset to the appropriate trees. If there is no offset,
5976 offset is set to NULL_TREE. Base will be canonicalized to
5977 something you can get the element type from using
5978 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5979 in bytes to the base. */
5981 static bool
5983 {
5984 /* One canonical form is a PLUS_EXPR with the first
5985 argument being an ADDR_EXPR with a possible NOP_EXPR
5986 attached. */
5988 {
5991 /* Strip NOP_EXPRs here because the C frontends and/or
5992 folders present us (int *)&x.a + 4B possibly. */
5995 {
5999 else
6003 }
6004 }
6005 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
6006 which we transform into an ADDR_EXPR with appropriate
6007 offset. For other arguments to the ADDR_EXPR we assume
6008 zero offset and as such do not care about the ADDR_EXPR
6009 type and strip possible nops from it. */
6011 {
6014 {
6019 }
6020 else
6021 {
6022 /* Handle array-to-pointer decay as &a. */
6025 else
6028 }
6030 }
6031 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
6034 {
6038 }
6041 }
6044 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
6045 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
6046 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
6047 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
6048 COND is the first argument to CODE; otherwise (as in the example
6049 given here), it is the second argument. TYPE is the type of the
6050 original expression. Return NULL_TREE if no simplification is
6051 possible. */
6053 static tree
6057 {
6064 /* This transformation is only worthwhile if we don't have to wrap
6065 arg in a SAVE_EXPR, and the operation can be simplified on at least
6066 one of the branches once its pushed inside the COND_EXPR. */
6071 {
6075 /* If this operand throws an expression, then it does not make
6076 sense to try to perform a logical or arithmetic operation
6077 involving it. */
6082 }
6083 else
6084 {
6089 }
6093 {
6097 else
6099 }
6101 {
6105 else
6107 }
6111 }
6113 \f
6114 /* Subroutine of fold() that checks for the addition of +/- 0.0.
6116 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
6117 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
6118 ADDEND is the same as X.
6120 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
6121 and finite. The problematic cases are when X is zero, and its mode
6122 has signed zeros. In the case of rounding towards -infinity,
6123 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
6124 modes, X + 0 is not the same as X because -0 + 0 is 0. */
6126 static bool
6128 {
6132 /* Don't allow the fold with -fsignaling-nans. */
6136 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
6140 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
6145 /* The mode has signed zeros, and we have to honor their sign.
6146 In this situation, there is only one case we can return true for.
6147 X - 0 is the same as X unless rounding towards -infinity is
6148 supported. */
6150 }
6152 /* Subroutine of fold() that checks comparisons of built-in math
6153 functions against real constants.
6155 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
6156 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
6157 is the type of the result and ARG0 and ARG1 are the operands of the
6158 comparison. ARG1 must be a TREE_REAL_CST.
6160 The function returns the constant folded tree if a simplification
6161 can be made, and NULL_TREE otherwise. */
6163 static tree
6166 {
6167 REAL_VALUE_TYPE c;
6170 {
6176 {
6177 /* sqrt(x) < y is always false, if y is negative. */
6181 /* sqrt(x) > y is always true, if y is negative and we
6182 don't care about NaNs, i.e. negative values of x. */
6186 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
6189 }
6191 {
6192 REAL_VALUE_TYPE c2;
6198 {
6199 /* sqrt(x) > y is x == +Inf, when y is very large. */
6204 /* sqrt(x) > y is always false, when y is very large
6205 and we don't care about infinities. */
6207 }
6209 /* sqrt(x) > c is the same as x > c*c. */
6212 }
6214 {
6215 REAL_VALUE_TYPE c2;
6221 {
6222 /* sqrt(x) < y is always true, when y is a very large
6223 value and we don't care about NaNs or Infinities. */
6227 /* sqrt(x) < y is x != +Inf when y is very large and we
6228 don't care about NaNs. */
6233 /* sqrt(x) < y is x >= 0 when y is very large and we
6234 don't care about Infinities. */
6239 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6248 dconst0)),
6251 c2)));
6252 }
6254 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6259 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6262 {
6267 dconst0)),
6270 c2)));
6271 }
6272 }
6273 }
6276 }
6278 /* Subroutine of fold() that optimizes comparisons against Infinities,
6279 either +Inf or -Inf.
6281 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6282 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6283 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6285 The function returns the constant folded tree if a simplification
6286 can be made, and NULL_TREE otherwise. */
6288 static tree
6290 {
6292 REAL_VALUE_TYPE max;
6293 tree temp;
6298 /* For negative infinity swap the sense of the comparison. */
6304 {
6306 /* x > +Inf is always false, if with ignore sNANs. */
6312 /* x <= +Inf is always true, if we don't case about NaNs. */
6316 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6319 {
6322 }
6327 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6333 /* x < +Inf is always equal to x <= DBL_MAX. */
6339 /* x != +Inf is always equal to !(x > DBL_MAX). */
6351 }
6354 }
6356 /* Subroutine of fold() that optimizes comparisons of a division by
6357 a nonzero integer constant against an integer constant, i.e.
6358 X/C1 op C2.
6360 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6361 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6362 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6364 The function returns the constant folded tree if a simplification
6365 can be made, and NULL_TREE otherwise. */
6367 static tree
6369 {
6374 HOST_WIDE_INT hpart;
6379 /* We have to do this the hard way to detect unsigned overflow.
6380 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6391 {
6396 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6404 }
6406 {
6410 {
6429 }
6430 }
6431 else
6432 {
6433 /* A negative divisor reverses the relational operators. */
6439 {
6458 }
6459 }
6462 {
6483 {
6486 }
6491 {
6494 }
6499 {
6502 }
6507 {
6510 }
6515 }
6518 }
6521 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6522 equality/inequality test, then return a simplified form of the test
6523 using a sign testing. Otherwise return NULL. TYPE is the desired
6524 result type. */
6526 static tree
6528 tree result_type)
6529 {
6530 /* If this is testing a single bit, we can optimize the test. */
6534 {
6535 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6536 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6540 /* This is only a win if casting to a signed type is cheap,
6541 i.e. when arg00's type is not a partial mode. */
6544 {
6549 }
6550 }
6553 }
6555 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6556 equality/inequality test, then return a simplified form of
6557 the test using shifts and logical operations. Otherwise return
6558 NULL. TYPE is the desired result type. */
6560 tree
6562 tree result_type)
6563 {
6564 /* If this is testing a single bit, we can optimize the test. */
6568 {
6577 /* First, see if we can fold the single bit test into a sign-bit
6578 test. */
6580 result_type);
6584 /* Otherwise we have (A & C) != 0 where C is a single bit,
6585 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6586 Similarly for (A & C) == 0. */
6588 /* If INNER is a right shift of a constant and it plus BITNUM does
6589 not overflow, adjust BITNUM and INNER. */
6596 {
6599 }
6601 /* If we are going to be able to omit the AND below, we must do our
6602 operations as unsigned. If we must use the AND, we have a choice.
6603 Normally unsigned is faster, but for some machines signed is. */
6604 #ifdef LOAD_EXTEND_OP
6607 #else
6609 #endif
6625 /* Put the AND last so it can combine with more things. */
6628 /* Make sure to return the proper type. */
6632 }
6634 }
6636 /* Check whether we are allowed to reorder operands arg0 and arg1,
6637 such that the evaluation of arg1 occurs before arg0. */
6639 static bool
6641 {
6648 }
6650 /* Test whether it is preferable two swap two operands, ARG0 and
6651 ARG1, for example because ARG0 is an integer constant and ARG1
6652 isn't. If REORDER is true, only recommend swapping if we can
6653 evaluate the operands in reverse order. */
6655 bool
6657 {
6688 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6689 for commutative and comparison operators. Ensuring a canonical
6690 form allows the optimizers to find additional redundancies without
6691 having to explicitly check for both orderings. */
6697 /* Put SSA_NAMEs last. */
6703 /* Put variables last. */
6710 }
6712 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6713 ARG0 is extended to a wider type. */
6715 static tree
6717 {
6719 tree arg1_unw;
6728 #ifdef HAVE_canonicalize_funcptr_for_compare
6729 /* Disable this optimization if we're casting a function pointer
6730 type on targets that require function pointer canonicalization. */
6735 #endif
6742 /* If possible, express the comparison in the shorter mode. */
6758 /* If we are comparing with the integer that does not fit into the range
6759 of the shorter type, the result is known. */
6770 {
6797 }
6800 }
6802 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6803 ARG0 just the signedness is changed. */
6805 static tree
6808 {
6809 tree arg0_inner;
6820 #ifdef HAVE_canonicalize_funcptr_for_compare
6821 /* Disable this optimization if we're casting a function pointer
6822 type on targets that require function pointer canonicalization. */
6827 #endif
6847 else
6851 }
6853 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6854 step of the array. Reconstructs s and delta in the case of s * delta
6855 being an integer constant (and thus already folded).
6856 ADDR is the address. MULT is the multiplicative expression.
6857 If the function succeeds, the new address expression is returned. Otherwise
6858 NULL_TREE is returned. */
6860 static tree
6862 {
6866 tree itype;
6869 /* Canonicalize op1 into a possibly non-constant delta
6870 and an INTEGER_CST s. */
6872 {
6879 {
6882 }
6884 {
6887 }
6888 else
6890 }
6892 {
6895 }
6896 else
6897 {
6898 /* Simulate we are delta * 1. */
6901 }
6904 {
6906 {
6907 /* Remember if this was a multi-dimensional array. */
6920 {
6923 }
6924 else
6925 {
6926 /* Try if delta is a multiple of step. */
6931 }
6933 /* Only fold here if we can verify we do not overflow one
6934 dimension of a multi-dimensional array. */
6936 {
6937 tree tmp;
6953 }
6956 }
6957 else
6962 }
6964 /* We found the suitable array reference. So copy everything up to it,
6965 and replace the index. */
6972 {
6976 }
6984 }
6987 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6988 means A >= Y && A != MAX, but in this case we know that
6989 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6991 static tree
6993 {
7000 else
7009 {
7012 }
7014 {
7017 }
7018 else
7029 }
7031 /* Fold a sum or difference of at least one multiplication.
7032 Returns the folded tree or NULL if no simplification could be made. */
7034 static tree
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 }
7051 else
7052 {
7055 }
7057 {
7060 }
7061 else
7062 {
7065 }
7077 /* No identical multiplicands; see if we can find a common
7078 power-of-two factor in non-power-of-two multiplies. This
7079 can help in multi-dimensional array access. */
7082 {
7085 tree maybe_same;
7089 /* Move min of absolute values to int11. */
7092 {
7097 }
7098 else
7102 {
7110 }
7111 }
7121 }
7123 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
7124 specified by EXPR into the buffer PTR of length LEN bytes.
7125 Return the number of bytes placed in the buffer, or zero
7126 upon failure. */
7128 static int
7130 {
7141 {
7145 else
7150 {
7157 else
7159 }
7160 else
7163 }
7165 }
7168 /* Subroutine of native_encode_expr. Encode the REAL_CST
7169 specified by EXPR into the buffer PTR of length LEN bytes.
7170 Return the number of bytes placed in the buffer, or zero
7171 upon failure. */
7173 static int
7175 {
7181 /* There are always 32 bits in each long, no matter the size of
7182 the hosts long. We handle floating point representations with
7183 up to 192 bits. */
7194 {
7199 {
7206 else
7208 }
7209 else
7212 }
7214 }
7216 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
7217 specified by EXPR into the buffer PTR of length LEN bytes.
7218 Return the number of bytes placed in the buffer, or zero
7219 upon failure. */
7221 static int
7223 {
7225 tree part;
7236 }
7239 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7240 specified by EXPR into the buffer PTR of length LEN bytes.
7241 Return the number of bytes placed in the buffer, or zero
7242 upon failure. */
7244 static int
7246 {
7256 {
7258 {
7261 }
7262 else
7266 {
7269 }
7270 else
7271 {
7275 }
7277 }
7279 }
7282 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7283 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7284 buffer PTR of length LEN bytes. Return the number of bytes
7285 placed in the buffer, or zero upon failure. */
7287 int
7289 {
7291 {
7306 }
7307 }
7310 /* Subroutine of native_interpret_expr. Interpret the contents of
7311 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7312 If the buffer cannot be interpreted, return NULL_TREE. */
7314 static tree
7316 {
7330 {
7333 {
7340 else
7342 }
7343 else
7349 else
7352 }
7355 }
7358 /* Subroutine of native_interpret_expr. Interpret the contents of
7359 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7360 If the buffer cannot be interpreted, return NULL_TREE. */
7362 static tree
7364 {
7369 /* There are always 32 bits in each long, no matter the size of
7370 the hosts long. We handle floating point representations with
7371 up to 192 bits. */
7372 REAL_VALUE_TYPE r;
7383 {
7386 {
7393 else
7395 }
7396 else
7401 }
7405 }
7408 /* Subroutine of native_interpret_expr. Interpret the contents of
7409 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7410 If the buffer cannot be interpreted, return NULL_TREE. */
7412 static tree
7414 {
7429 }
7432 /* Subroutine of native_interpret_expr. Interpret the contents of
7433 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7434 If the buffer cannot be interpreted, return NULL_TREE. */
7436 static tree
7438 {
7450 {
7455 }
7457 }
7460 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7461 the buffer PTR of length LEN as a constant of type TYPE. For
7462 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7463 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7464 return NULL_TREE. */
7466 tree
7468 {
7470 {
7487 }
7488 }
7491 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7492 TYPE at compile-time. If we're unable to perform the conversion
7493 return NULL_TREE. */
7495 static tree
7497 {
7498 /* We support up to 512-bit values (for V8DFmode). */
7502 /* Check that the host and target are sane. */
7511 }
7514 /* Fold a unary expression of code CODE and type TYPE with operand
7515 OP0. Return the folded expression if folding is successful.
7516 Otherwise, return NULL_TREE. */
7518 tree
7520 {
7521 tree tem;
7522 tree arg0;
7530 {
7533 {
7534 /* Don't use STRIP_NOPS, because signedness of argument type
7535 matters. */
7537 }
7538 else
7539 {
7540 /* Strip any conversions that don't change the mode. This
7541 is safe for every expression, except for a comparison
7542 expression because its signedness is derived from its
7543 operands.
7545 Note that this is done as an internal manipulation within
7546 the constant folder, in order to find the simplest
7547 representation of the arguments so that their form can be
7548 studied. In any cases, the appropriate type conversions
7549 should be put back in the tree that will get out of the
7550 constant folder. */
7552 }
7553 }
7556 {
7561 {
7571 /* If this was a conversion, and all we did was to move into
7572 inside the COND_EXPR, bring it back out. But leave it if
7573 it is a conversion from integer to integer and the
7574 result precision is no wider than a word since such a
7575 conversion is cheap and may be optimized away by combine,
7576 while it couldn't if it were outside the COND_EXPR. Then return
7577 so we don't get into an infinite recursion loop taking the
7578 conversion out and then back in. */
7590 && (INTEGRAL_TYPE_P
7602 }
7604 {
7606 {
7610 }
7614 integer_one_node),
7616 integer_zero_node));
7617 }
7618 }
7621 {
7629 /* If we have (type) (a CMP b) and type is an integral type, return
7630 new expression involving the new type. */
7635 /* Handle cases of two conversions in a row. */
7638 {
7660 /* In addition to the cases of two conversions in a row
7661 handled below, if we are converting something to its own
7662 type via an object of identical or wider precision, neither
7663 conversion is needed. */
7670 /* Likewise, if the intermediate and final types are either both
7671 float or both integer, we don't need the middle conversion if
7672 it is wider than the final type and doesn't change the signedness
7673 (for integers). Avoid this if the final type is a pointer
7674 since then we sometimes need the inner conversion. Likewise if
7675 the outer has a precision not equal to the size of its mode. */
7684 && ! final_ptr
7688 /* If we have a sign-extension of a zero-extended value, we can
7689 replace that by a single zero-extension. */
7695 /* Two conversions in a row are not needed unless:
7696 - some conversion is floating-point (overstrict for now), or
7697 - some conversion is a vector (overstrict for now), or
7698 - the intermediate type is narrower than both initial and
7699 final, or
7700 - the intermediate type and innermost type differ in signedness,
7701 and the outermost type is wider than the intermediate, or
7702 - the initial type is a pointer type and the precisions of the
7703 intermediate and final types differ, or
7704 - the final type is a pointer type and the precisions of the
7705 initial and intermediate types differ.
7706 - the final type is a pointer type and the initial type not
7707 - the initial type is a pointer to an array and the final type
7708 not. */
7722 && ! (inside_ptr
7726 }
7728 /* Handle (T *)&A.B.C for A being of type T and B and C
7729 living at offset zero. This occurs frequently in
7730 C++ upcasting and then accessing the base. */
7734 {
7736 tree offset;
7742 /* If the reference was to a (constant) zero offset, we can use
7743 the address of the base if it has the same base type
7744 as the result type. */
7749 }
7754 /* Detect assigning a bitfield. */
7756 && DECL_BIT_FIELD
7758 {
7759 /* Don't leave an assignment inside a conversion
7760 unless assigning a bitfield. */
7762 /* First do the assignment, then return converted constant. */
7767 }
7769 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7770 constants (if x has signed type, the sign bit cannot be set
7771 in c). This folds extension into the BIT_AND_EXPR. */
7776 {
7786 <= HOST_BITS_PER_WIDE_INT
7788 {
7795 #ifdef LOAD_EXTEND_OP
7797 && !flag_syntax_only
7800 {
7804 }
7805 #endif
7806 }
7808 {
7814 }
7815 }
7817 /* Convert (T1)(X op Y) into ((T1)X op (T1)Y), for pointer type,
7818 when one of the new casts will fold away. Conservatively we assume
7819 that this happens when X or Y is NOP_EXPR or Y is INTEGER_CST. */
7825 {
7831 }
7833 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7834 of the same precision, and X is a integer type not narrower than
7835 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7842 {
7847 }
7870 /* Convert fabs((double)float) into (double)fabsf(float). */
7873 {
7878 targ0));
7879 }
7880 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7886 /* Strip sign ops from argument. */
7888 {
7892 }
7899 {
7904 }
7906 {
7911 }
7921 /* Convert ~ (-A) to A - 1. */
7925 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7932 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7949 /* The argument to invert_truthvalue must have Boolean type. */
7953 /* Note that the operand of this must be an int
7954 and its values must be 0 or 1.
7955 ("true" is a fixed value perhaps depending on the language,
7956 but we don't handle values other than 1 correctly yet.) */
7971 {
7979 }
7981 {
7985 }
7987 {
7991 {
8000 }
8001 }
8013 {
8021 }
8023 {
8027 }
8029 {
8033 {
8042 }
8043 }
8049 }
8051 /* Fold a binary expression of code CODE and type TYPE with operands
8052 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
8053 Return the folded expression if folding is successful. Otherwise,
8054 return NULL_TREE. */
8056 static tree
8058 {
8065 else
8068 /* MIN (MAX (a, b), b) == b. */
8073 /* MIN (MAX (b, a), b) == b. */
8079 /* MIN (a, MAX (a, b)) == a. */
8085 /* MIN (a, MAX (b, a)) == a. */
8092 }
8094 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
8095 by changing CODE to reduce the magnitude of constants involved in
8096 ARG0 of the comparison.
8097 Returns a canonicalized comparison tree if a simplification was
8098 possible, otherwise returns NULL_TREE.
8099 Set *STRICT_OVERFLOW_P to true if the canonicalization is only
8100 valid if signed overflow is undefined. */
8102 static tree
8106 {
8112 /* Match A +- CST code arg1 and CST code arg1. */
8119 /* Identify the constant in arg0 and its sign. */
8122 else
8126 /* Overflowed constants and zero will cause problems. */
8131 /* See if we can reduce the magnitude of the constant in
8132 arg0 by changing the comparison code. */
8134 {
8135 /* CST <= arg1 -> CST-1 < arg1. */
8138 /* -CST < arg1 -> -CST-1 <= arg1. */
8141 /* CST > arg1 -> CST-1 >= arg1. */
8144 /* -CST >= arg1 -> -CST-1 > arg1. */
8147 else
8149 /* arg1 code' CST' might be more canonical. */
8151 }
8152 else
8153 {
8154 /* A - CST < arg1 -> A - CST-1 <= arg1. */
8158 /* A + CST > arg1 -> A + CST-1 >= arg1. */
8162 /* A + CST <= arg1 -> A + CST-1 < arg1. */
8166 /* A - CST >= arg1 -> A - CST-1 > arg1. */
8170 else
8173 }
8175 /* Now build the constant reduced in magnitude. */
8181 /* If swapping might yield to a more canonical form, do so. */
8184 else
8186 }
8188 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
8189 overflow further. Try to decrease the magnitude of constants involved
8190 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
8191 and put sole constants at the second argument position.
8192 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
8194 static tree
8197 {
8198 tree t;
8203 /* In principle pointers also have undefined overflow behavior,
8204 but that causes problems elsewhere. */
8209 /* Try canonicalization by simplifying arg0. */
8214 {
8218 }
8220 /* Try canonicalization by simplifying arg1 using the swapped
8221 comparison. */
8229 }
8231 /* Subroutine of fold_binary. This routine performs all of the
8232 transformations that are common to the equality/inequality
8233 operators (EQ_EXPR and NE_EXPR) and the ordering operators
8234 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
8235 fold_binary should call fold_binary. Fold a comparison with
8236 tree code CODE and type TYPE with operands OP0 and OP1. Return
8237 the folded comparison or NULL_TREE. */
8239 static tree
8241 {
8254 /* If one arg is a real or integer constant, put it last. */
8258 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8265 {
8269 tree lhs;
8276 /* If the constant operation overflowed this can be
8277 simplified as a comparison against INT_MAX/INT_MIN. */
8280 {
8284 /* Get the sign of the constant on the lhs if the
8285 operation were VARIABLE + CONST1. */
8289 /* The sign of the constant determines if we overflowed
8290 INT_MAX (const1_sgn == -1) or INT_MIN (const1_sgn == 1).
8291 Canonicalize to the INT_MIN overflow by swapping the comparison
8292 if necessary. */
8296 /* We now can look at the canonicalized case
8297 VARIABLE + 1 CODE2 INT_MIN
8298 and decide on the result. */
8307 }
8312 {
8314 "when changing X +- C1 cmp C2 to "
8316 WARN_STRICT_OVERFLOW_COMPARISON);
8318 }
8319 }
8321 /* For comparisons of pointers we can decompose it to a compile time
8322 comparison of the base objects and the offsets into the object.
8323 This requires at least one operand being an ADDR_EXPR to do more
8324 than the operand_equal_p test below. */
8328 {
8335 /* Get base and offset for the access. Strip ADDR_EXPR for
8336 get_inner_reference, but put it back by stripping INDIRECT_REF
8337 off the base object if possible. */
8340 {
8346 else
8348 }
8352 {
8356 /* We have to make sure to have an indirect/non-indirect base1
8357 just the same as we did for base0. */
8363 }
8367 /* If we have equivalent bases we might be able to simplify. */
8370 {
8371 /* We can fold this expression to a constant if the non-constant
8372 offset parts are equal. */
8376 {
8378 {
8392 }
8393 }
8394 /* We can simplify the comparison to a comparison of the variable
8395 offset parts if the constant offset parts are equal.
8396 Be careful to use signed size type here because otherwise we
8397 mess with array offsets in the wrong way. This is possible
8398 because pointer arithmetic is restricted to retain within an
8399 object and overflow on pointer differences is undefined as of
8400 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8402 {
8403 tree signed_size_type_node;
8406 /* By converting to signed size type we cover middle-end pointer
8407 arithmetic which operates on unsigned pointer types of size
8408 type size and ARRAY_REF offsets which are properly sign or
8409 zero extended from their type in case it is narrower than
8410 size type. */
8413 else
8417 else
8421 }
8422 }
8423 }
8425 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8426 same object, then we can fold this to a comparison of the two offsets in
8427 signed size type. This is possible because pointer arithmetic is
8428 restricted to retain within an object and overflow on pointer differences
8429 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8431 We check flag_wrapv directly because pointers types are unsigned,
8432 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8433 normally what we want to avoid certain odd overflow cases, but
8434 not here. */
8436 && !flag_wrapv
8438 {
8444 {
8445 tree signed_size_type_node;
8448 /* By converting to signed size type we cover middle-end pointer
8449 arithmetic which operates on unsigned pointer types of size
8450 type size and ARRAY_REF offsets which are properly sign or
8451 zero extended from their type in case it is narrower than
8452 size type. */
8455 else
8459 else
8463 }
8464 }
8466 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8467 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8468 the resulting offset is smaller in absolute value than the
8469 original one. */
8477 {
8482 tree cst;
8484 "occur when combining constants around "
8487 /* Put the constant on the side where it doesn't overflow and is
8488 of lower absolute value than before. */
8494 {
8497 variable1,
8500 }
8507 {
8512 variable2);
8513 }
8514 }
8516 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8517 signed arithmetic case. That form is created by the compiler
8518 often enough for folding it to be of value. One example is in
8519 computing loop trip counts after Operator Strength Reduction. */
8525 {
8534 "eliminating multiplication in comparison "
8536 WARN_STRICT_OVERFLOW_COMPARISON);
8538 /* If const1 is negative we swap the sense of the comparison. */
8543 }
8550 {
8558 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8563 /* (-a) CMP (-b) -> b CMP a */
8570 {
8571 REAL_VALUE_TYPE cst;
8574 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8581 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8582 /* a CMP (-0) -> a CMP 0 */
8587 /* x != NaN is always true, other ops are always false. */
8590 {
8593 }
8595 /* Fold comparisons against infinity. */
8597 {
8601 }
8602 }
8604 /* If this is a comparison of a real constant with a PLUS_EXPR
8605 or a MINUS_EXPR of a real constant, we can convert it into a
8606 comparison with a revised real constant as long as no overflow
8607 occurs when unsafe_math_optimizations are enabled. */
8619 /* Likewise, we can simplify a comparison of a real constant with
8620 a MINUS_EXPR whose first operand is also a real constant, i.e.
8621 (c1 - x) < c2 becomes x > c1-c2. */
8632 /* Fold comparisons against built-in math functions. */
8634 && flag_unsafe_math_optimizations
8636 {
8640 {
8644 }
8645 }
8646 }
8651 {
8652 /* If we are widening one operand of an integer comparison,
8653 see if the other operand is similarly being widened. Perhaps we
8654 can do the comparison in the narrower type. */
8659 /* Or if we are changing signedness. */
8663 }
8665 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8666 constant, we can simplify it. */
8671 {
8675 }
8677 /* Simplify comparison of something with itself. (For IEEE
8678 floating-point, we can only do some of these simplifications.) */
8680 {
8682 {
8697 /* For NE, we can only do this simplification if integer
8698 or we don't honor IEEE floating point NaNs. */
8702 /* ... fall through ... */
8708 }
8709 }
8711 /* If we are comparing an expression that just has comparisons
8712 of two integer values, arithmetic expressions of those comparisons,
8713 and constants, we can simplify it. There are only three cases
8714 to check: the two values can either be equal, the first can be
8715 greater, or the second can be greater. Fold the expression for
8716 those three values. Since each value must be 0 or 1, we have
8717 eight possibilities, each of which corresponds to the constant 0
8718 or 1 or one of the six possible comparisons.
8720 This handles common cases like (a > b) == 0 but also handles
8721 expressions like ((x > y) - (y > x)) > 0, which supposedly
8722 occur in macroized code. */
8725 {
8730 /* Don't handle degenerate cases here; they should already
8731 have been handled anyway. */
8740 {
8744 /* We can't just pass T to eval_subst in case cval1 or cval2
8745 was the same as ARG1. */
8747 tree high_result
8751 arg1);
8752 tree equal_result
8756 arg1);
8757 tree low_result
8761 arg1);
8763 /* All three of these results should be 0 or 1. Confirm they are.
8764 Then use those values to select the proper code to use. */
8769 {
8770 /* Make a 3-bit mask with the high-order bit being the
8771 value for `>', the next for '=', and the low for '<'. */
8775 {
8777 /* Always false. */
8798 /* Always true. */
8800 }
8805 }
8806 }
8807 }
8809 /* Fold a comparison of the address of COMPONENT_REFs with the same
8810 type and component to a comparison of the address of the base
8811 object. In short, &x->a OP &y->a to x OP y and
8812 &x->a OP &y.a to x OP &y */
8817 {
8821 {
8827 }
8828 }
8830 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8831 into a single range test. */
8839 {
8843 }
8845 /* Fold ~X op ~Y as Y op X. */
8848 {
8853 }
8855 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
8858 {
8864 }
8867 }
8870 /* Subroutine of fold_binary. Optimize complex multiplications of the
8871 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8872 argument EXPR represents the expression "z" of type TYPE. */
8874 static tree
8876 {
8881 {
8884 }
8886 {
8889 }
8890 else
8891 {
8895 }
8904 }
8907 /* Fold a binary expression of code CODE and type TYPE with operands
8908 OP0 and OP1. Return the folded expression if folding is
8909 successful. Otherwise, return NULL_TREE. */
8911 tree
8913 {
8928 /* Strip any conversions that don't change the mode. This is
8929 safe for every expression, except for a comparison expression
8930 because its signedness is derived from its operands. So, in
8931 the latter case, only strip conversions that don't change the
8932 signedness.
8934 Note that this is done as an internal manipulation within the
8935 constant folder, in order to find the simplest representation
8936 of the arguments so that their form can be studied. In any
8937 cases, the appropriate type conversions should be put back in
8938 the tree that will get out of the constant folder. */
8941 {
8944 }
8945 else
8946 {
8949 }
8951 /* Note that TREE_CONSTANT isn't enough: static var addresses are
8952 constant but we can't do arithmetic on them. */
8957 {
8962 else
8966 {
8970 }
8971 }
8973 /* If this is a commutative operation, and ARG0 is a constant, move it
8974 to ARG1 to reduce the number of tests below. */
8979 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
8981 First check for cases where an arithmetic operation is applied to a
8982 compound, conditional, or comparison operation. Push the arithmetic
8983 operation inside the compound or conditional to see if any folding
8984 can then be done. Convert comparison to conditional for this purpose.
8985 The also optimizes non-constant cases that used to be done in
8986 expand_expr.
8988 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
8989 one of the operands is a comparison and the other is a comparison, a
8990 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
8991 code below would make the expression more complex. Change it to a
8992 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
8993 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
9005 {
9009 boolean_type_node,
9017 }
9021 {
9033 {
9039 }
9042 {
9048 }
9049 }
9052 {
9054 /* A + (-B) -> A - B */
9059 /* (-A) + B -> B - A */
9065 /* Convert ~A + 1 to -A. */
9071 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
9072 same or one. */
9076 {
9080 }
9083 {
9087 /* ~X + X is -1. */
9091 {
9094 }
9096 /* X + ~X is -1. */
9100 {
9103 }
9105 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
9106 with a constant, and the two constants have no bits in common,
9107 we should treat this as a BIT_IOR_EXPR since this may produce more
9108 simplifications. */
9116 {
9119 }
9121 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
9122 (plus (plus (mult) (mult)) (foo)) so that we can
9123 take advantage of the factoring cases below. */
9130 {
9136 else
9158 parg1)));
9159 }
9161 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
9162 of the array. Loop optimizer sometimes produce this type of
9163 expressions. */
9165 {
9169 }
9171 {
9175 }
9176 }
9177 else
9178 {
9179 /* See if ARG1 is zero and X + ARG1 reduces to X. */
9183 /* Likewise if the operands are reversed. */
9187 /* Convert X + -C into X - C. */
9190 {
9196 }
9198 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
9199 to __complex__ ( x, y ). This is not the same for SNaNs or
9200 if signed zeros are involved. */
9204 {
9211 {
9215 {
9221 }
9223 {
9229 }
9230 }
9231 }
9239 /* Convert x+x into x*2.0. */
9245 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
9249 {
9254 {
9255 tree tree0;
9258 }
9259 }
9260 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
9264 {
9269 {
9270 tree tree0;
9273 }
9274 }
9275 }
9277 bit_rotate:
9278 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9279 is a rotate of A by C1 bits. */
9280 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9281 is a rotate of A by B bits. */
9282 {
9291 {
9310 {
9318 TYPE_PRECISION
9323 ? LROTATE_EXPR
9326 }
9328 {
9336 TYPE_PRECISION
9341 ? LROTATE_EXPR
9344 }
9345 }
9346 }
9348 associate:
9349 /* In most languages, can't associate operations on floats through
9350 parentheses. Rather than remember where the parentheses were, we
9351 don't associate floats at all, unless the user has specified
9352 -funsafe-math-optimizations. */
9355 {
9360 /* Split both trees into variables, constants, and literals. Then
9361 associate each group together, the constants with literals,
9362 then the result with variables. This increases the chances of
9363 literals being recombined later and of generating relocatable
9364 expressions for the sum of a constant and literal. */
9369 /* With undefined overflow we can only associate constants
9370 with one variable. */
9374 {
9382 /* The only case we can still associate with two variables
9383 is if they are the same, modulo negation. */
9386 }
9388 /* Only do something if we found more than two objects. Otherwise,
9389 nothing has changed and we risk infinite recursion. */
9395 {
9396 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9405 /* Preserve the MINUS_EXPR if the negative part of the literal is
9406 greater than the positive part. Otherwise, the multiplicative
9407 folding code (i.e extract_muldiv) may be fooled in case
9408 unsigned constants are subtracted, like in the following
9409 example: ((X*2 + 4) - 8U)/2. */
9411 {
9415 {
9419 }
9420 else
9421 {
9425 }
9426 }
9428 {
9433 else
9434 {
9440 }
9441 }
9446 }
9447 }
9452 /* A - (-B) -> A + B */
9455 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9463 /* Convert -A - 1 to ~A. */
9471 /* Convert -1 - A to ~A. */
9477 {
9483 /* Fold A - (A & B) into ~B & A. */
9486 {
9491 arg0);
9496 arg0);
9497 }
9499 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9500 any power of 2 minus 1. */
9505 {
9511 {
9515 }
9516 }
9517 }
9519 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9523 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9524 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9525 (-ARG1 + ARG0) reduces to -ARG1. */
9529 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9530 __complex__ ( x, -y ). This is not the same for SNaNs or if
9531 signed zeros are involved. */
9535 {
9542 {
9546 {
9548 arg1r ? arg1r
9553 }
9555 {
9559 arg1i ? arg1i
9562 }
9563 }
9564 }
9566 /* Fold &x - &x. This can happen from &x.foo - &x.
9567 This is unsafe for certain floats even in non-IEEE formats.
9568 In IEEE, it is unsafe because it does wrong for NaNs.
9569 Also note that operand_equal_p is always false if an operand
9570 is volatile. */
9576 /* A - B -> A + (-B) if B is easily negatable. */
9579 /* Avoid this transformation if B is a positive REAL_CST. */
9587 /* Try folding difference of addresses. */
9588 {
9589 HOST_WIDE_INT diff;
9595 }
9597 /* Fold &a[i] - &a[j] to i-j. */
9602 {
9607 {
9615 }
9616 }
9618 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9619 of the array. Loop optimizer sometimes produce this type of
9620 expressions. */
9622 {
9626 }
9634 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9635 same or one. */
9639 {
9643 }
9648 /* (-A) * (-B) -> A * B */
9659 {
9664 /* Transform x * -1 into -x. */
9667 /* Transform x * -C into -x * C if x is easily negatable. */
9676 /* (a * (1 << b)) is (a << b) */
9692 {
9695 "occur when simplifying "
9697 WARN_STRICT_OVERFLOW_MISC);
9699 }
9701 /* Optimize z * conj(z) for integer complex numbers. */
9708 }
9709 else
9710 {
9711 /* Maybe fold x * 0 to 0. The expressions aren't the same
9712 when x is NaN, since x * 0 is also NaN. Nor are they the
9713 same in modes with signed zeros, since multiplying a
9714 negative value by 0 gives -0, not +0. */
9719 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9724 /* Transform x * -1.0 into -x. */
9729 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9734 {
9740 }
9742 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9744 {
9747 {
9750 }
9751 }
9753 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9754 This is not the same for NaNs or if signed zeros are
9755 involved. */
9761 {
9773 }
9775 /* Optimize z * conj(z) for floating point complex numbers.
9776 Guarded by flag_unsafe_math_optimizations as non-finite
9777 imaginary components don't produce scalar results. */
9788 {
9792 /* Optimizations of root(...)*root(...). */
9794 {
9799 /* Optimize sqrt(x)*sqrt(x) as x. */
9805 /* Optimize root(x)*root(y) as root(x*y). */
9809 }
9811 /* Optimize expN(x)*expN(y) as expN(x+y). */
9813 {
9819 }
9821 /* Optimizations of pow(...)*pow(...). */
9825 {
9831 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9833 {
9837 }
9839 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9841 {
9845 }
9846 }
9848 /* Optimize tan(x)*cos(x) as sin(x). */
9857 {
9862 }
9864 /* Optimize x*pow(x,c) as pow(x,c+1). */
9868 {
9874 {
9876 REAL_VALUE_TYPE c;
9877 tree arg;
9883 }
9884 }
9886 /* Optimize pow(x,c)*x as pow(x,c+1). */
9890 {
9896 {
9898 REAL_VALUE_TYPE c;
9899 tree arg;
9905 }
9906 }
9908 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9911 {
9915 {
9918 }
9919 }
9920 }
9921 }
9925 bit_ior:
9933 /* ~X | X is -1. */
9936 {
9939 }
9941 /* X | ~X is -1. */
9944 {
9947 }
9949 /* Canonicalize (X & C1) | C2. */
9953 {
9961 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9966 {
9970 }
9971 else
9972 {
9976 }
9978 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9983 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
9993 arg1);
9994 }
9996 /* (X & Y) | Y is (X, Y). */
10000 /* (X & Y) | X is (Y, X). */
10005 /* X | (X & Y) is (Y, X). */
10010 /* X | (Y & X) is (Y, X). */
10020 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
10022 This results in more efficient code for machines without a NAND
10023 instruction. Combine will canonicalize to the first form
10024 which will allow use of NAND instructions provided by the
10025 backend if they exist. */
10028 {
10033 }
10035 /* See if this can be simplified into a rotate first. If that
10036 is unsuccessful continue in the association code. */
10047 /* ~X ^ X is -1. */
10050 {
10053 }
10055 /* X ^ ~X is -1. */
10058 {
10061 }
10063 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
10064 with a constant, and the two constants have no bits in common,
10065 we should treat this as a BIT_IOR_EXPR since this may produce more
10066 simplifications. */
10074 {
10077 }
10079 /* (X | Y) ^ X -> Y & ~ X*/
10082 {
10085 arg1);
10089 }
10091 /* (Y | X) ^ X -> Y & ~ X*/
10094 {
10097 arg1);
10101 }
10103 /* X ^ (X | Y) -> Y & ~ X*/
10106 {
10109 arg0);
10113 }
10115 /* X ^ (Y | X) -> Y & ~ X*/
10118 {
10121 arg0);
10125 }
10127 /* Convert ~X ^ ~Y to X ^ Y. */
10134 /* Convert ~X ^ C to X ^ ~C. */
10141 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
10148 /* Fold (X & Y) ^ Y as ~X & Y. */
10151 {
10156 }
10157 /* Fold (X & Y) ^ X as ~Y & X. */
10161 {
10166 }
10167 /* Fold X ^ (X & Y) as X & ~Y. */
10170 {
10175 }
10176 /* Fold X ^ (Y & X) as ~Y & X. */
10180 {
10185 }
10187 /* See if this can be simplified into a rotate first. If that
10188 is unsuccessful continue in the association code. */
10199 /* ~X & X is always zero. */
10204 /* X & ~X is always zero. */
10209 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
10219 /* (X | Y) & Y is (X, Y). */
10223 /* (X | Y) & X is (Y, X). */
10228 /* X & (X | Y) is (Y, X). */
10233 /* X & (Y | X) is (Y, X). */
10239 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
10243 {
10249 }
10250 /* Fold ~X & 1 as (X & 1) == 0. */
10253 {
10259 }
10261 /* Fold (X ^ Y) & Y as ~X & Y. */
10264 {
10269 }
10270 /* Fold (X ^ Y) & X as ~Y & X. */
10274 {
10279 }
10280 /* Fold X & (X ^ Y) as X & ~Y. */
10283 {
10288 }
10289 /* Fold X & (Y ^ X) as ~Y & X. */
10293 {
10298 }
10303 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10306 {
10307 unsigned int prec
10314 }
10316 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10318 This results in more efficient code for machines without a NOR
10319 instruction. Combine will canonicalize to the first form
10320 which will allow use of NOR instructions provided by the
10321 backend if they exist. */
10324 {
10329 }
10334 /* Don't touch a floating-point divide by zero unless the mode
10335 of the constant can represent infinity. */
10341 /* Optimize A / A to 1.0 if we don't care about
10342 NaNs or Infinities. Skip the transformation
10343 for non-real operands. */
10348 {
10352 }
10354 /* The complex version of the above A / A optimization. */
10357 {
10361 {
10363 /* omit_two_operands will call fold_convert for us. */
10365 }
10366 }
10368 /* (-A) / (-B) -> A / B */
10378 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
10383 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
10388 /* If ARG1 is a constant, we can convert this to a multiply by the
10389 reciprocal. This does not have the same rounding properties,
10390 so only do this if -funsafe-math-optimizations. We can actually
10391 always safely do it if ARG1 is a power of two, but it's hard to
10392 tell if it is or not in a portable manner. */
10394 {
10399 /* Find the reciprocal if optimizing and the result is exact. */
10401 {
10402 REAL_VALUE_TYPE r;
10405 {
10409 }
10410 }
10411 }
10412 /* Convert A/B/C to A/(B*C). */
10419 /* Convert A/(B/C) to (A/B)*C. */
10427 /* Convert C1/(X*C2) into (C1/C2)/X. */
10432 {
10438 }
10441 {
10445 /* Optimize sin(x)/cos(x) as tan(x). */
10451 {
10456 }
10458 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10464 {
10468 {
10472 }
10473 }
10475 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10476 NaNs or Infinities. */
10480 {
10487 {
10492 }
10493 }
10495 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10496 NaNs or Infinities. */
10500 {
10507 {
10511 {
10515 tmp);
10516 }
10517 }
10518 }
10520 /* Optimize pow(x,c)/x as pow(x,c-1). */
10524 {
10530 {
10532 REAL_VALUE_TYPE c;
10533 tree arg;
10539 }
10540 }
10542 /* Optimize x/expN(y) into x*expN(-y). */
10544 {
10549 }
10551 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10555 {
10562 }
10563 }
10568 /* Simplify A / (B << N) where A and B are positive and B is
10569 a power of 2, to A >> (N + log2(B)). */
10574 {
10577 {
10584 WARN_STRICT_OVERFLOW_MISC);
10590 }
10591 }
10592 /* Fall thru */
10601 /* X / -1 is -X. */
10608 /* Convert -A / -B to A / B when the type is signed and overflow is
10609 undefined. */
10613 {
10616 "when distributing negation across "
10618 WARN_STRICT_OVERFLOW_MISC);
10621 }
10625 {
10628 "when distributing negation across "
10630 WARN_STRICT_OVERFLOW_MISC);
10633 }
10635 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10636 operation, EXACT_DIV_EXPR.
10638 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10639 At one time others generated faster code, it's not clear if they do
10640 after the last round to changes to the DIV code in expmed.c. */
10649 {
10653 WARN_STRICT_OVERFLOW_MISC);
10655 }
10663 /* X % 1 is always zero, but be sure to preserve any side
10664 effects in X. */
10668 /* X % 0, return X % 0 unchanged so that we can get the
10669 proper warnings and errors. */
10673 /* 0 % X is always zero, but be sure to preserve any side
10674 effects in X. Place this after checking for X == 0. */
10678 /* X % -1 is zero. */
10685 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10686 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10691 {
10693 /* Also optimize A % (C << N) where C is a power of 2,
10694 to A & ((C << N) - 1). */
10699 {
10704 "occur when simplifying "
10706 WARN_STRICT_OVERFLOW_MISC);
10710 }
10711 }
10713 /* X % -C is the same as X % C. */
10720 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10725 /* X % -Y is the same as X % Y. */
10736 {
10740 WARN_STRICT_OVERFLOW_MISC);
10742 }
10753 /* Optimize -1 >> x for arithmetic right shifts. */
10756 /* ... fall through ... */
10759 shift:
10765 /* Since negative shift count is not well-defined,
10766 don't try to compute it in the compiler. */
10770 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10775 {
10779 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10780 being well defined. */
10782 {
10787 else
10789 }
10793 }
10795 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10796 into x & ((unsigned)-1 >> c) for unsigned types. */
10804 {
10807 tree lshift;
10808 tree arg00;
10811 {
10818 }
10819 }
10821 /* Rewrite an LROTATE_EXPR by a constant into an
10822 RROTATE_EXPR by a new constant. */
10824 {
10829 }
10831 /* If we have a rotate of a bit operation with the rotate count and
10832 the second operand of the bit operation both constant,
10833 permute the two operations. */
10845 /* Two consecutive rotates adding up to the width of the mode can
10846 be ignored. */
10883 /* Note that the operands of this must be ints
10884 and their values must be 0 or 1.
10885 ("true" is a fixed value perhaps depending on the language.) */
10886 /* If first arg is constant zero, return it. */
10890 /* If either arg is constant true, drop it. */
10894 /* Preserve sequence points. */
10897 /* If second arg is constant zero, result is zero, but first arg
10898 must be evaluated. */
10901 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10902 case will be handled here. */
10906 /* !X && X is always false. */
10910 /* X && !X is always false. */
10915 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10916 means A >= Y && A != MAX, but in this case we know that
10917 A < X <= MAX. */
10921 {
10929 }
10931 truth_andor:
10932 /* We only do these simplifications if we are optimizing. */
10936 /* Check for things like (A || B) && (A || C). We can convert this
10937 to A || (B && C). Note that either operator can be any of the four
10938 truth and/or operations and the transformation will still be
10939 valid. Also note that we only care about order for the
10940 ANDIF and ORIF operators. If B contains side effects, this
10941 might change the truth-value of A. */
10948 {
10968 /* This case if tricky because we must either have commutative
10969 operators or else A10 must not have side-effects. */
10975 a01);
10976 }
10978 /* See if we can build a range comparison. */
10982 /* Check for the possibility of merging component references. If our
10983 lhs is another similar operation, try to merge its rhs with our
10984 rhs. Then try to merge our lhs and rhs. */
10996 /* Note that the operands of this must be ints
10997 and their values must be 0 or true.
10998 ("true" is a fixed value perhaps depending on the language.) */
10999 /* If first arg is constant true, return it. */
11003 /* If either arg is constant zero, drop it. */
11007 /* Preserve sequence points. */
11010 /* If second arg is constant true, result is true, but we must
11011 evaluate first arg. */
11014 /* Likewise for first arg, but note this only occurs here for
11015 TRUTH_OR_EXPR. */
11019 /* !X || X is always true. */
11023 /* X || !X is always true. */
11031 /* If the second arg is constant zero, drop it. */
11034 /* If the second arg is constant true, this is a logical inversion. */
11036 {
11037 /* Only call invert_truthvalue if operand is a truth value. */
11040 else
11043 }
11044 /* Identical arguments cancel to zero. */
11048 /* !X ^ X is always true. */
11053 /* X ^ !X is always true. */
11066 /* bool_var != 0 becomes bool_var. */
11071 /* bool_var == 1 becomes bool_var. */
11076 /* bool_var != 1 becomes !bool_var. */
11081 /* bool_var == 0 becomes !bool_var. */
11086 /* If this is an equality comparison of the address of two non-weak,
11087 unaliased symbols neither of which are extern (since we do not
11088 have access to attributes for externs), then we know the result. */
11101 {
11102 /* We know that we're looking at the address of two
11103 non-weak, unaliased, static _DECL nodes.
11105 It is both wasteful and incorrect to call operand_equal_p
11106 to compare the two ADDR_EXPR nodes. It is wasteful in that
11107 all we need to do is test pointer equality for the arguments
11108 to the two ADDR_EXPR nodes. It is incorrect to use
11109 operand_equal_p as that function is NOT equivalent to a
11110 C equality test. It can in fact return false for two
11111 objects which would test as equal using the C equality
11112 operator. */
11116 type);
11117 }
11119 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
11120 a MINUS_EXPR of a constant, we can convert it into a comparison with
11121 a revised constant as long as no overflow occurs. */
11133 /* Similarly for a NEGATE_EXPR. */
11141 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
11150 /* Transform comparisons of the form X +- C CMP X. */
11156 {
11163 else
11166 }
11168 /* If we have X - Y == 0, we can convert that to X == Y and similarly
11169 for !=. Don't do this for ordered comparisons due to overflow. */
11175 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
11180 /* If this is an EQ or NE comparison with zero and ARG0 is
11181 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
11182 two operations, but the latter can be done in one less insn
11183 on machines that have only two-operand insns or on which a
11184 constant cannot be the first operand. */
11187 {
11192 return
11198 integer_one_node)),
11199 arg1);
11202 return
11208 integer_one_node)),
11209 arg1);
11210 }
11212 /* If this is an NE or EQ comparison of zero against the result of a
11213 signed MOD operation whose second operand is a power of 2, make
11214 the MOD operation unsigned since it is simpler and equivalent. */
11222 {
11232 }
11234 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
11235 C1 is a valid shift constant, and C2 is a power of two, i.e.
11236 a single bit. */
11240 == INTEGER_CST
11243 {
11248 /* Check for a valid shift count. */
11251 {
11255 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
11256 can be rewritten as (X & (C2 << C1)) != 0. */
11258 {
11262 }
11263 /* Otherwise, for signed (arithmetic) shifts,
11264 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
11265 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
11269 /* Otherwise, of unsigned (logical) shifts,
11270 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
11271 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
11272 else
11276 arg000);
11277 }
11278 }
11280 /* If this is an NE comparison of zero with an AND of one, remove the
11281 comparison since the AND will give the correct value. */
11288 /* If we have (A & C) == C where C is a power of 2, convert this into
11289 (A & C) != 0. Similarly for NE_EXPR. */
11295 integer_zero_node));
11297 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11298 bit, then fold the expression into A < 0 or A >= 0. */
11303 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11304 Similarly for NE_EXPR. */
11308 {
11317 }
11319 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11320 Similarly for NE_EXPR. */
11324 {
11331 }
11333 /* If this is a comparison of a field, we may be able to simplify it. */
11336 /* Handle the constant case even without -O
11337 to make sure the warnings are given. */
11339 {
11343 }
11345 /* Optimize comparisons of strlen vs zero to a compare of the
11346 first character of the string vs zero. To wit,
11347 strlen(ptr) == 0 => *ptr == 0
11348 strlen(ptr) != 0 => *ptr != 0
11349 Other cases should reduce to one of these two (or a constant)
11350 due to the return value of strlen being unsigned. */
11353 {
11361 {
11365 }
11366 }
11368 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11369 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11373 {
11380 {
11382 {
11385 }
11388 }
11389 }
11391 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
11397 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
11402 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
11409 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
11417 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11418 (X & C) == 0 when C is a single bit. */
11423 {
11429 }
11431 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11432 constant C is a power of two, i.e. a single bit. */
11439 {
11443 }
11445 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11446 when is C is a power of two, i.e. a single bit. */
11453 {
11459 }
11463 {
11466 }
11468 /* Fold -X op -Y as X op Y, where op is eq/ne. */
11475 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11478 {
11490 arg01),
11498 arg01),
11506 arg00),
11514 arg00),
11516 }
11520 {
11527 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11528 operand_equal_p guarantees no side-effects so we don't need
11529 to use omit_one_operand on Z. */
11539 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11546 arg10);
11547 }
11549 /* Attempt to simplify equality/inequality comparisons of complex
11550 values. Only lower the comparison if the result is known or
11551 can be simplified to a single scalar comparison. */
11556 {
11561 {
11564 }
11565 else
11566 {
11569 }
11572 {
11575 }
11576 else
11577 {
11580 }
11584 {
11586 {
11591 }
11592 else
11593 {
11598 }
11599 }
11603 {
11605 {
11610 }
11611 else
11612 {
11617 }
11618 }
11619 }
11631 /* Transform comparisons of the form X +- C CMP X. */
11638 {
11645 else
11648 /* (X - c) > X becomes false. */
11652 {
11656 "occur when assuming that (X - c) > X "
11658 WARN_STRICT_OVERFLOW_ALL);
11660 }
11662 /* Likewise (X + c) < X becomes false. */
11666 {
11670 "occur when assuming that "
11672 WARN_STRICT_OVERFLOW_ALL);
11674 }
11676 /* Convert (X - c) <= X to true. */
11681 {
11685 "occur when assuming that "
11687 WARN_STRICT_OVERFLOW_ALL);
11689 }
11691 /* Convert (X + c) >= X to true. */
11696 {
11700 "occur when assuming that "
11702 WARN_STRICT_OVERFLOW_ALL);
11704 }
11707 {
11708 /* Convert X + c > X and X - c < X to true for integers. */
11712 {
11715 "not occur when assuming that "
11717 WARN_STRICT_OVERFLOW_ALL);
11719 }
11724 {
11727 "not occur when assuming that "
11729 WARN_STRICT_OVERFLOW_ALL);
11731 }
11733 /* Convert X + c <= X and X - c >= X to false for integers. */
11737 {
11740 "not occur when assuming that "
11742 WARN_STRICT_OVERFLOW_ALL);
11744 }
11749 {
11752 "not occur when assuming that "
11754 WARN_STRICT_OVERFLOW_ALL);
11756 }
11757 }
11758 }
11760 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11761 This transformation affects the cases which are handled in later
11762 optimizations involving comparisons with non-negative constants. */
11766 {
11768 {
11773 }
11775 {
11780 }
11781 }
11783 /* Comparisons with the highest or lowest possible integer of
11784 the specified precision will have known values. */
11785 {
11793 {
11794 HOST_WIDE_INT signed_max_hi;
11799 {
11806 {
11810 }
11811 else
11812 {
11816 }
11817 }
11818 else
11819 {
11828 {
11831 }
11832 else
11833 {
11836 }
11837 }
11842 {
11855 /* The GE_EXPR and LT_EXPR cases above are not normally
11856 reached because of previous transformations. */
11860 }
11862 == max_hi
11865 {
11871 arg1);
11877 arg1);
11880 }
11882 == min_hi
11885 {
11900 }
11902 == min_hi
11905 {
11910 arg1);
11915 arg1);
11918 }
11923 /* We will flip the signedness of the comparison operator
11924 associated with the mode of arg1, so the sign bit is
11925 specified by this mode. Check that arg1 is the signed
11926 max associated with this sign bit. */
11928 /* signed_type does not work on pointer types. */
11930 {
11931 /* The following case also applies to X < signed_max+1
11932 and X >= signed_max+1 because previous transformations. */
11934 {
11935 tree st;
11940 }
11941 }
11942 }
11943 }
11945 /* If we are comparing an ABS_EXPR with a constant, we can
11946 convert all the cases into explicit comparisons, but they may
11947 well not be faster than doing the ABS and one comparison.
11948 But ABS (X) <= C is a range comparison, which becomes a subtraction
11949 and a comparison, and is probably faster. */
11963 /* Convert ABS_EXPR<x> >= 0 to true. */
11970 {
11973 "when simplifying comparison of "
11975 WARN_STRICT_OVERFLOW_CONDITIONAL);
11977 }
11979 /* Convert ABS_EXPR<x> < 0 to false. */
11984 {
11987 "when simplifying comparison of "
11989 WARN_STRICT_OVERFLOW_CONDITIONAL);
11991 }
11993 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11994 and similarly for >= into !=. */
12010 return
12029 {
12033 }
12035 /* If the first operand is NaN, the result is constant. */
12039 {
12041 ? integer_zero_node
12044 }
12046 /* If the second operand is NaN, the result is constant. */
12050 {
12052 ? integer_zero_node
12055 }
12057 /* Simplify unordered comparison of something with itself. */
12063 && !flag_trapping_math
12067 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
12068 {
12079 }
12084 /* When pedantic, a compound expression can be neither an lvalue
12085 nor an integer constant expression. */
12088 /* Don't let (0, 0) be null pointer constant. */
12102 /* An ASSERT_EXPR should never be passed to fold_binary. */
12108 }
12110 /* Callback for walk_tree, looking for LABEL_EXPR.
12111 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
12112 Do not check the sub-tree of GOTO_EXPR. */
12114 static tree
12118 {
12120 {
12125 /* no break */
12128 }
12129 }
12131 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
12132 accessible from outside the sub-tree. Returns NULL_TREE if no
12133 addressable label is found. */
12135 static bool
12137 {
12139 }
12141 /* Fold a ternary expression of code CODE and type TYPE with operands
12142 OP0, OP1, and OP2. Return the folded expression if folding is
12143 successful. Otherwise, return NULL_TREE. */
12145 tree
12147 {
12148 tree tem;
12155 /* Strip any conversions that don't change the mode. This is safe
12156 for every expression, except for a comparison expression because
12157 its signedness is derived from its operands. So, in the latter
12158 case, only strip conversions that don't change the signedness.
12160 Note that this is done as an internal manipulation within the
12161 constant folder, in order to find the simplest representation of
12162 the arguments so that their form can be studied. In any cases,
12163 the appropriate type conversions should be put back in the tree
12164 that will get out of the constant folder. */
12166 {
12169 }
12172 {
12175 }
12178 {
12182 {
12188 }
12192 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
12193 so all simple results must be passed through pedantic_non_lvalue. */
12195 {
12198 /* Only optimize constant conditions when the selected branch
12199 has the same type as the COND_EXPR. This avoids optimizing
12200 away "c ? x : throw", where the throw has a void type.
12201 Avoid throwing away that operand which contains label. */
12208 }
12212 /* If we have A op B ? A : C, we may be able to convert this to a
12213 simpler expression, depending on the operation and the values
12214 of B and C. Signed zeros prevent all of these transformations,
12215 for reasons given above each one.
12217 Also try swapping the arguments and inverting the conditional. */
12222 {
12226 }
12230 op2,
12233 {
12236 {
12240 }
12241 }
12243 /* If the second operand is simpler than the third, swap them
12244 since that produces better jump optimization results. */
12247 {
12248 /* See if this can be inverted. If it can't, possibly because
12249 it was a floating-point inequality comparison, don't do
12250 anything. */
12254 }
12256 /* Convert A ? 1 : 0 to simply A. */
12259 /* If we try to convert OP0 to our type, the
12260 call to fold will try to move the conversion inside
12261 a COND, which will recurse. In that case, the COND_EXPR
12262 is probably the best choice, so leave it alone. */
12266 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
12267 over COND_EXPR in cases such as floating point comparisons. */
12274 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
12279 {
12280 /* sign_bit_p only checks ARG1 bits within A's precision.
12281 If <sign bit of A> has wider type than A, bits outside
12282 of A's precision in <sign bit of A> need to be checked.
12283 If they are all 0, this optimization needs to be done
12284 in unsigned A's type, if they are all 1 in signed A's type,
12285 otherwise this can't be done. */
12290 {
12292 HOST_WIDE_INT mask_hi;
12294 tree tem_type;
12302 {
12306 }
12307 else
12308 {
12312 }
12314 {
12318 }
12319 else
12325 {
12328 }
12331 {
12334 }
12335 else
12337 }
12344 arg1)));
12345 }
12347 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
12348 already handled above. */
12353 {
12362 }
12364 /* A & N ? N : 0 is simply A & N if N is a power of two. This
12365 is probably obsolete because the first operand should be a
12366 truth value (that's why we have the two cases above), but let's
12367 leave it in until we can confirm this for all front-ends. */
12378 /* Convert A ? B : 0 into A && B if A and B are truth values. */
12384 arg1);
12386 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
12390 {
12391 /* Only perform transformation if ARG0 is easily inverted. */
12396 arg1);
12397 }
12399 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
12403 {
12404 /* Only perform transformation if ARG0 is easily inverted. */
12409 op2);
12410 }
12412 /* Convert A ? 1 : B into A || B if A and B are truth values. */
12418 op2);
12423 /* CALL_EXPRs used to be ternary exprs. Catch any mistaken uses
12424 of fold_ternary on them. */
12433 {
12442 {
12447 else
12448 {
12450 tree value;
12454 }
12459 else
12461 }
12462 }
12468 }
12470 /* Perform constant folding and related simplification of EXPR.
12471 The related simplifications include x*1 => x, x*0 => 0, etc.,
12472 and application of the associative law.
12473 NOP_EXPR conversions may be removed freely (as long as we
12474 are careful not to change the type of the overall expression).
12475 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12476 but we can constant-fold them if they have constant operands. */
12478 #ifdef ENABLE_FOLD_CHECKING
12479 # define fold(x) fold_1 (x)
12481 static
12482 #endif
12483 tree
12485 {
12489 tree tem;
12491 /* Return right away if a constant. */
12495 /* CALL_EXPR-like objects with variable numbers of operands are
12496 treated specially. */
12498 {
12500 {
12503 }
12505 }
12509 {
12514 {
12532 }
12533 }
12536 {
12543 }
12545 #ifdef ENABLE_FOLD_CHECKING
12546 #undef fold
12552 /* When --enable-checking=fold, compute a digest of expr before
12553 and after actual fold call to see if fold did not accidentally
12554 change original expr. */
12556 tree
12558 {
12559 tree ret;
12562 htab_t ht;
12581 }
12583 void
12585 {
12588 htab_t ht;
12598 }
12600 static void
12602 {
12604 }
12606 static void
12608 {
12614 recursive_label:
12628 {
12629 /* Allow DECL_ASSEMBLER_NAME to be modified. */
12633 }
12638 {
12639 /* Allow these fields to be modified. */
12646 {
12649 }
12650 }
12658 {
12661 {
12675 }
12679 {
12692 }
12709 {
12715 }
12720 {
12724 }
12735 {
12738 }
12748 }
12749 }
12751 #endif
12753 /* Fold a unary tree expression with code CODE of type TYPE with an
12754 operand OP0. Return a folded expression if successful. Otherwise,
12755 return a tree expression with code CODE of type TYPE with an
12756 operand OP0. */
12758 tree
12760 {
12761 tree tem;
12762 #ifdef ENABLE_FOLD_CHECKING
12765 htab_t ht;
12772 #endif
12778 #ifdef ENABLE_FOLD_CHECKING
12786 #endif
12788 }
12790 /* Fold a binary tree expression with code CODE of type TYPE with
12791 operands OP0 and OP1. Return a folded expression if successful.
12792 Otherwise, return a tree expression with code CODE of type TYPE
12793 with operands OP0 and OP1. */
12795 tree
12797 MEM_STAT_DECL)
12798 {
12799 tree tem;
12800 #ifdef ENABLE_FOLD_CHECKING
12806 htab_t ht;
12818 #endif
12824 #ifdef ENABLE_FOLD_CHECKING
12840 #endif
12842 }
12844 /* Fold a ternary tree expression with code CODE of type TYPE with
12845 operands OP0, OP1, and OP2. Return a folded expression if
12846 successful. Otherwise, return a tree expression with code CODE of
12847 type TYPE with operands OP0, OP1, and OP2. */
12849 tree
12851 MEM_STAT_DECL)
12852 {
12853 tree tem;
12854 #ifdef ENABLE_FOLD_CHECKING
12862 htab_t ht;
12879 #endif
12886 #ifdef ENABLE_FOLD_CHECKING
12910 #endif
12912 }
12914 /* Fold a CALL_EXPR expression of type TYPE with operands FN and NARGS
12915 arguments in ARGARRAY, and a null static chain.
12916 Return a folded expression if successful. Otherwise, return a CALL_EXPR
12917 of type TYPE from the given operands as constructed by build_call_array. */
12919 tree
12921 {
12922 tree tem;
12923 #ifdef ENABLE_FOLD_CHECKING
12929 htab_t ht;
12943 #endif
12947 #ifdef ENABLE_FOLD_CHECKING
12964 #endif
12966 }
12968 /* Perform constant folding and related simplification of initializer
12969 expression EXPR. These behave identically to "fold_buildN" but ignore
12970 potential run-time traps and exceptions that fold must preserve. */
12972 #define START_FOLD_INIT \
12973 int saved_signaling_nans = flag_signaling_nans;\
12974 int saved_trapping_math = flag_trapping_math;\
12975 int saved_rounding_math = flag_rounding_math;\
12976 int saved_trapv = flag_trapv;\
12977 int saved_folding_initializer = folding_initializer;\
12978 flag_signaling_nans = 0;\
12979 flag_trapping_math = 0;\
12980 flag_rounding_math = 0;\
12981 flag_trapv = 0;\
12982 folding_initializer = 1;
12984 #define END_FOLD_INIT \
12985 flag_signaling_nans = saved_signaling_nans;\
12986 flag_trapping_math = saved_trapping_math;\
12987 flag_rounding_math = saved_rounding_math;\
12988 flag_trapv = saved_trapv;\
12989 folding_initializer = saved_folding_initializer;
12991 tree
12993 {
12994 tree result;
12995 START_FOLD_INIT;
12999 END_FOLD_INIT;
13001 }
13003 tree
13005 {
13006 tree result;
13007 START_FOLD_INIT;
13011 END_FOLD_INIT;
13013 }
13015 tree
13017 tree op2)
13018 {
13019 tree result;
13020 START_FOLD_INIT;
13024 END_FOLD_INIT;
13026 }
13028 tree
13031 {
13032 tree result;
13033 START_FOLD_INIT;
13037 END_FOLD_INIT;
13039 }
13041 #undef START_FOLD_INIT
13042 #undef END_FOLD_INIT
13044 /* Determine if first argument is a multiple of second argument. Return 0 if
13045 it is not, or we cannot easily determined it to be.
13047 An example of the sort of thing we care about (at this point; this routine
13048 could surely be made more general, and expanded to do what the *_DIV_EXPR's
13049 fold cases do now) is discovering that
13051 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13053 is a multiple of
13055 SAVE_EXPR (J * 8)
13057 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
13059 This code also handles discovering that
13061 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
13063 is a multiple of 8 so we don't have to worry about dealing with a
13064 possible remainder.
13066 Note that we *look* inside a SAVE_EXPR only to determine how it was
13067 calculated; it is not safe for fold to do much of anything else with the
13068 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
13069 at run time. For example, the latter example above *cannot* be implemented
13070 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
13071 evaluation time of the original SAVE_EXPR is not necessarily the same at
13072 the time the new expression is evaluated. The only optimization of this
13073 sort that would be valid is changing
13075 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
13077 divided by 8 to
13079 SAVE_EXPR (I) * SAVE_EXPR (J)
13081 (where the same SAVE_EXPR (J) is used in the original and the
13082 transformed version). */
13084 int
13086 {
13094 {
13096 /* Bitwise and provides a power of two multiple. If the mask is
13097 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
13100 /* FALLTHRU */
13113 {
13117 /* const_binop may not detect overflow correctly,
13118 so check for it explicitly here. */
13124 size_one_node,
13128 }
13132 /* Can't handle conversions from non-integral or wider integral type. */
13138 /* .. fall through ... */
13155 }
13156 }
13158 /* Return true if `t' is known to be non-negative. If the return
13159 value is based on the assumption that signed overflow is undefined,
13160 set *STRICT_OVERFLOW_P to true; otherwise, don't change
13161 *STRICT_OVERFLOW_P. */
13163 bool
13165 {
13173 {
13175 /* Query VRP to see if it has recorded any information about
13176 the range of this object. */
13180 /* We can't return 1 if flag_wrapv is set because
13181 ABS_EXPR<INT_MIN> = INT_MIN. */
13185 {
13188 }
13200 strict_overflow_p)
13202 strict_overflow_p));
13204 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
13205 both unsigned and at least 2 bits shorter than the result. */
13209 {
13214 {
13218 }
13219 }
13224 {
13225 /* x * x for floating point x is always non-negative. */
13229 strict_overflow_p)
13231 strict_overflow_p));
13232 }
13234 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
13235 both unsigned and their total bits is shorter than the result. */
13239 {
13246 }
13252 strict_overflow_p)
13254 strict_overflow_p));
13265 strict_overflow_p)
13267 strict_overflow_p));
13278 strict_overflow_p);
13284 strict_overflow_p);
13288 strict_overflow_p);
13292 strict_overflow_p)
13294 strict_overflow_p));
13297 {
13302 {
13305 strict_overflow_p);
13307 {
13311 strict_overflow_p);
13312 }
13313 }
13315 {
13318 strict_overflow_p);
13322 }
13323 }
13327 {
13331 /* If the initializer is non-void, then it's a normal expression
13332 that will be assigned to the slot. */
13336 /* Otherwise, the initializer sets the slot in some way. One common
13337 way is an assignment statement at the end of the initializer. */
13339 {
13347 else
13349 }
13354 strict_overflow_p);
13357 }
13360 {
13364 {
13382 /* Always true. */
13386 /* sqrt(-0.0) is -0.0. */
13390 strict_overflow_p);
13423 /* True if the 1st argument is nonnegative. */
13425 strict_overflow_p);
13428 /* True if the 1st OR 2nd arguments are nonnegative. */
13430 strict_overflow_p)
13432 strict_overflow_p)));
13435 /* True if the 1st AND 2nd arguments are nonnegative. */
13437 strict_overflow_p)
13439 strict_overflow_p)));
13442 /* True if the 2nd argument is nonnegative. */
13444 strict_overflow_p);
13447 /* True if the 1st argument is nonnegative or the second
13448 argument is an even integer. */
13450 {
13454 }
13456 strict_overflow_p);
13459 /* True if the 1st argument is nonnegative or the second
13460 argument is an even integer valued real. */
13462 {
13463 REAL_VALUE_TYPE c;
13464 HOST_WIDE_INT n;
13469 {
13470 REAL_VALUE_TYPE cint;
13475 }
13476 }
13478 strict_overflow_p);
13482 }
13483 }
13485 /* ... fall through ... */
13489 /* Truth values evaluate to 0 or 1, which is nonnegative. */
13491 }
13493 /* We don't know sign of `t', so be conservative and return false. */
13495 }
13497 /* Return true if `t' is known to be non-negative. Handle warnings
13498 about undefined signed overflow. */
13500 bool
13502 {
13509 "determining that expression is always "
13511 WARN_STRICT_OVERFLOW_MISC);
13513 }
13515 /* Return true when T is an address and is known to be nonzero.
13516 For floating point we further ensure that T is not denormal.
13517 Similar logic is present in nonzero_address in rtlanal.h.
13519 If the return value is based on the assumption that signed overflow
13520 is undefined, set *STRICT_OVERFLOW_P to true; otherwise, don't
13521 change *STRICT_OVERFLOW_P. */
13523 bool
13525 {
13529 /* Doing something useful for floating point would need more work. */
13534 {
13536 /* Query VRP to see if it has recorded any information about
13537 the range of this object. */
13542 strict_overflow_p);
13549 {
13550 /* With the presence of negative values it is hard
13551 to say something. */
13558 /* One of operands must be positive and the other non-negative. */
13559 /* We don't set *STRICT_OVERFLOW_P here: even if this value
13560 overflows, on a twos-complement machine the sum of two
13561 nonnegative numbers can never be zero. */
13563 strict_overflow_p)
13565 strict_overflow_p));
13566 }
13571 {
13573 strict_overflow_p)
13575 strict_overflow_p))
13576 {
13579 }
13580 }
13584 {
13590 strict_overflow_p));
13591 }
13595 {
13601 /* Weak declarations may link to NULL. */
13605 /* Constants are never weak. */
13610 }
13618 {
13622 }
13631 {
13634 }
13641 {
13645 /* When both operands are nonzero, then MAX must be too. */
13647 strict_overflow_p))
13650 /* MAX where operand 0 is positive is positive. */
13652 strict_overflow_p);
13653 }
13654 /* MAX where operand 1 is positive is positive. */
13659 {
13663 }
13671 strict_overflow_p);
13676 strict_overflow_p);
13680 strict_overflow_p)
13682 strict_overflow_p));
13689 }
13691 }
13693 /* Return true when T is an address and is known to be nonzero.
13694 Handle warnings about undefined signed overflow. */
13696 bool
13698 {
13705 "determining that expression is always "
13707 WARN_STRICT_OVERFLOW_MISC);
13709 }
13711 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13712 attempt to fold the expression to a constant without modifying TYPE,
13713 OP0 or OP1.
13715 If the expression could be simplified to a constant, then return
13716 the constant. If the expression would not be simplified to a
13717 constant, then return NULL_TREE. */
13719 tree
13721 {
13724 }
13726 /* Given the components of a unary expression CODE, TYPE and OP0,
13727 attempt to fold the expression to a constant without modifying
13728 TYPE or OP0.
13730 If the expression could be simplified to a constant, then return
13731 the constant. If the expression would not be simplified to a
13732 constant, then return NULL_TREE. */
13734 tree
13736 {
13739 }
13741 /* If EXP represents referencing an element in a constant string
13742 (either via pointer arithmetic or array indexing), return the
13743 tree representing the value accessed, otherwise return NULL. */
13745 tree
13747 {
13751 {
13753 tree index;
13754 tree string;
13758 else
13759 {
13763 /* Optimize the special-case of a zero lower bound.
13765 We convert the low_bound to sizetype to avoid some problems
13766 with constant folding. (E.g. suppose the lower bound is 1,
13767 and its mode is QI. Without the conversion,l (ARRAY
13768 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13769 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
13774 }
13788 }
13790 }
13792 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13793 an integer constant or real constant.
13795 TYPE is the type of the result. */
13797 static tree
13799 {
13803 {
13805 {
13807 HOST_WIDE_INT high;
13815 }
13823 }
13826 }
13828 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13829 an integer constant or real constant.
13831 TYPE is the type of the result. */
13833 tree
13835 {
13839 {
13841 /* If the value is unsigned, then the absolute value is
13842 the same as the ordinary value. */
13845 /* Similarly, if the value is non-negative. */
13848 /* If the value is negative, then the absolute value is
13849 its negation. */
13850 else
13851 {
13853 HOST_WIDE_INT high;
13859 }
13865 else
13871 }
13874 }
13876 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13877 constant. TYPE is the type of the result. */
13879 static tree
13881 {
13891 }
13893 /* Given CODE, a relational operator, the target type, TYPE and two
13894 constant operands OP0 and OP1, return the result of the
13895 relational operation. If the result is not a compile time
13896 constant, then return NULL_TREE. */
13898 static tree
13900 {
13903 /* From here on, the only cases we handle are when the result is
13904 known to be a constant. */
13907 {
13911 /* Handle the cases where either operand is a NaN. */
13913 {
13915 {
13943 }
13946 }
13949 }
13951 /* Handle equality/inequality of complex constants. */
13953 {
13964 else
13966 }
13968 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13970 To compute GT, swap the arguments and do LT.
13971 To compute GE, do LT and invert the result.
13972 To compute LE, swap the arguments, do LT and invert the result.
13973 To compute NE, do EQ and invert the result.
13975 Therefore, the code below must handle only EQ and LT. */
13978 {
13983 }
13985 /* Note that it is safe to invert for real values here because we
13986 have already handled the one case that it matters. */
13990 {
13993 }
13995 /* Compute a result for LT or EQ if args permit;
13996 Otherwise return T. */
13998 {
14003 else
14005 }
14006 else
14012 }
14014 /* Build an expression for the a clean point containing EXPR with type TYPE.
14015 Don't build a cleanup point expression for EXPR which don't have side
14016 effects. */
14018 tree
14020 {
14021 /* If the expression does not have side effects then we don't have to wrap
14022 it with a cleanup point expression. */
14026 /* If the expression is a return, check to see if the expression inside the
14027 return has no side effects or the right hand side of the modify expression
14028 inside the return. If either don't have side effects set we don't need to
14029 wrap the expression in a cleanup point expression. Note we don't check the
14030 left hand side of the modify because it should always be a return decl. */
14032 {
14039 }
14042 }
14044 /* Build an expression for the address of T. Folds away INDIRECT_REF to
14045 avoid confusing the gimplify process. */
14047 tree
14049 {
14050 /* The size of the object is not relevant when talking about its address. */
14054 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
14057 {
14061 }
14062 else
14063 {
14072 }
14075 }
14077 tree
14079 {
14081 }
14083 /* Given a pointer value OP0 and a type TYPE, return a simplified version
14084 of an indirection through OP0, or NULL_TREE if no simplification is
14085 possible. */
14087 tree
14089 {
14091 tree subtype;
14099 {
14102 /* *&CONST_DECL -> to the value of the const decl. */
14105 /* *&p => p; make sure to handle *&"str"[cst] here. */
14107 {
14111 else
14113 }
14114 /* *(foo *)&fooarray => fooarray[0] */
14117 {
14123 }
14124 /* *(foo *)&complexfoo => __real__ complexfoo */
14128 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
14131 {
14135 }
14136 }
14138 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
14141 {
14144 tree op00type;
14151 {
14155 }
14156 }
14158 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
14161 {
14162 tree type_domain;
14169 }
14172 }
14174 /* Builds an expression for an indirection through T, simplifying some
14175 cases. */
14177 tree
14179 {
14185 else
14187 }
14189 /* Given an INDIRECT_REF T, return either T or a simplified version. */
14191 tree
14193 {
14198 else
14200 }
14202 /* Strip non-trapping, non-side-effecting tree nodes from an expression
14203 whose result is ignored. The type of the returned tree need not be
14204 the same as the original expression. */
14206 tree
14208 {
14214 {
14225 else
14231 {
14247 }
14252 }
14253 }
14255 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
14256 This can only be applied to objects of a sizetype. */
14258 tree
14260 {
14267 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14268 have to do anything. Only do this when we are not given a const,
14269 because in that case, this check is more expensive than just
14270 doing it. */
14272 {
14277 }
14279 /* If divisor is a power of two, simplify this to bit manipulation. */
14281 {
14283 {
14296 {
14297 high++;
14300 }
14304 }
14305 else
14306 {
14307 tree t;
14313 }
14314 }
14315 else
14316 {
14321 }
14324 }
14326 /* Likewise, but round down. */
14328 tree
14330 {
14337 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
14338 have to do anything. Only do this when we are not given a const,
14339 because in that case, this check is more expensive than just
14340 doing it. */
14342 {
14347 }
14349 /* If divisor is a power of two, simplify this to bit manipulation. */
14351 {
14352 tree t;
14356 }
14357 else
14358 {
14363 }
14366 }
14368 /* Returns the pointer to the base of the object addressed by EXP and
14369 extracts the information about the offset of the access, storing it
14370 to PBITPOS and POFFSET. */
14372 static tree
14375 {
14376 tree core;
14379 HOST_WIDE_INT bitsize;
14382 {
14387 }
14388 else
14389 {
14393 }
14396 }
14398 /* Returns true if addresses of E1 and E2 differ by a constant, false
14399 otherwise. If they do, E1 - E2 is stored in *DIFF. */
14401 bool
14403 {
14417 {
14427 }
14429 {
14430 /* If only one of the offsets is non-constant, the difference cannot
14431 be a constant. */
14433 }
14434 else
14439 }
14441 /* Simplify the floating point expression EXP when the sign of the
14442 result is not significant. Return NULL_TREE if no simplification
14443 is possible. */
14445 tree
14447 {
14451 {
14486 {
14489 {
14491 /* Strip copysign function call, return the 1st argument. */
14497 /* Strip sign ops from the argument of "odd" math functions. */
14499 {
14503 }
14505 }
14506 }
14511 }
14513 }