| blob | c147efafb68bbf4d19b9681944fe6384d4190d7e |
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. */
67 /* Non-zero if we are folding constants inside an initializer; zero
68 otherwise. */
71 /* The following constants represent a bit based encoding of GCC's
72 comparison operators. This encoding simplifies transformations
73 on relational comparison operators, such as AND and OR. */
91 };
125 tree);
150 /* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
151 overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
152 and SUM1. Then this yields nonzero if overflow occurred during the
153 addition.
155 Overflow occurs if A and B have the same sign, but A and SUM differ in
156 sign. Use `^' to test whether signs differ, and `< 0' to isolate the
157 sign. */
158 #define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
159 \f
160 /* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
161 We do that by representing the two-word integer in 4 words, with only
162 HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
163 number. The value of the word is LOWPART + HIGHPART * BASE. */
165 #define LOWPART(x) \
166 ((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
167 #define HIGHPART(x) \
168 ((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
169 #define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
171 /* Unpack a two-word integer into 4 words.
172 LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
173 WORDS points to the array of HOST_WIDE_INTs. */
175 static void
177 {
182 }
184 /* Pack an array of 4 words into a two-word integer.
185 WORDS points to the array of words.
186 The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
188 static void
191 {
194 }
195 \f
196 /* Force the double-word integer L1, H1 to be within the range of the
197 integer type TYPE. Stores the properly truncated and sign-extended
198 double-word integer in *LV, *HV. Returns true if the operation
199 overflows, that is, argument and result are different. */
201 int
204 {
213 else
216 /* Size types *are* sign extended. */
221 /* First clear all bits that are beyond the type's precision. */
223 ;
226 else
227 {
231 }
233 /* Then do sign extension if necessary. */
239 {
240 /* Sign extend top half? */
244 }
246 {
249 }
250 else
251 {
252 /* Sign extend bottom half? */
254 {
257 }
258 }
263 /* If the value didn't fit, signal overflow. */
265 }
267 /* We force the double-int HIGH:LOW to the range of the type TYPE by
268 sign or zero extending it.
269 OVERFLOWABLE indicates if we are interested
270 in overflow of the value, when >0 we are only interested in signed
271 overflow, for <0 we are interested in any overflow. OVERFLOWED
272 indicates whether overflow has already occurred. CONST_OVERFLOWED
273 indicates whether constant overflow has already occurred. We force
274 T's value to be within range of T's type (by setting to 0 or 1 all
275 the bits outside the type's range). We set TREE_OVERFLOWED if,
276 OVERFLOWED is nonzero,
277 or OVERFLOWABLE is >0 and signed overflow occurs
278 or OVERFLOWABLE is <0 and any overflow occurs
279 We return a new tree node for the extended double-int. The node
280 is shared if no overflow flags are set. */
282 tree
286 {
290 /* Size types *are* sign extended. */
297 /* If we need to set overflow flags, return a new unshared node. */
299 {
303 {
310 }
311 }
313 /* Else build a shared node. */
315 }
316 \f
317 /* Add two doubleword integers with doubleword result.
318 Return nonzero if the operation overflows according to UNSIGNED_P.
319 Each argument is given as two `HOST_WIDE_INT' pieces.
320 One argument is L1 and H1; the other, L2 and H2.
321 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
323 int
328 {
330 HOST_WIDE_INT h;
340 else
342 }
344 /* Negate a doubleword integer with doubleword result.
345 Return nonzero if the operation overflows, assuming it's signed.
346 The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
347 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
349 int
352 {
354 {
358 }
359 else
360 {
364 }
365 }
366 \f
367 /* Multiply two doubleword integers with doubleword result.
368 Return nonzero if the operation overflows according to UNSIGNED_P.
369 Each argument is given as two `HOST_WIDE_INT' pieces.
370 One argument is L1 and H1; the other, L2 and H2.
371 The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
373 int
378 {
393 {
396 {
398 /* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
400 /* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
404 }
406 }
411 /* Unsigned overflow is immediate. */
415 /* Check for signed overflow by calculating the signed representation of the
416 top half of the result; it should agree with the low half's sign bit. */
418 {
421 }
423 {
426 }
428 }
429 \f
430 /* Shift the doubleword integer in L1, H1 left by COUNT places
431 keeping only PREC bits of result.
432 Shift right if COUNT is negative.
433 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
434 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
436 void
440 {
444 {
447 }
453 {
454 /* Shifting by the host word size is undefined according to the
455 ANSI standard, so we must handle this as a special case. */
458 }
460 {
463 }
464 else
465 {
469 }
471 /* Sign extend all bits that are beyond the precision. */
479 ;
481 {
484 }
485 else
486 {
490 }
491 }
493 /* Shift the doubleword integer in L1, H1 right by COUNT places
494 keeping only PREC bits of result. COUNT must be positive.
495 ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
496 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
498 void
503 {
506 signmask = (arith
514 {
515 /* Shifting by the host word size is undefined according to the
516 ANSI standard, so we must handle this as a special case. */
519 }
521 {
524 }
525 else
526 {
530 }
532 /* Zero / sign extend all bits that are beyond the precision. */
535 {
538 }
540 ;
542 {
545 }
546 else
547 {
551 }
552 }
553 \f
554 /* Rotate the doubleword integer in L1, H1 left by COUNT places
555 keeping only PREC bits of result.
556 Rotate right if COUNT is negative.
557 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
559 void
563 {
575 }
577 /* Rotate the doubleword integer in L1, H1 left by COUNT places
578 keeping only PREC bits of result. COUNT must be positive.
579 Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
581 void
585 {
597 }
598 \f
599 /* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
600 for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
601 CODE is a tree code for a kind of division, one of
602 TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
603 or EXACT_DIV_EXPR
604 It controls how the quotient is rounded to an integer.
605 Return nonzero if the operation overflows.
606 UNS nonzero says do unsigned division. */
608 int
611 HOST_WIDE_INT hnum_orig,
613 HOST_WIDE_INT hden_orig,
617 {
633 /* Calculate quotient sign and convert operands to unsigned. */
635 {
637 {
639 /* (minimum integer) / (-1) is the only overflow case. */
643 }
645 {
648 }
649 }
654 /* This unsigned division rounds toward zero. */
657 }
661 /* hden != 0 already checked. */
666 }
676 /* Special code for when the divisor < BASE. */
678 {
679 /* hnum != 0 already checked. */
681 {
685 }
686 }
687 else
688 {
689 /* Full double precision division,
690 with thanks to Don Knuth's "Seminumerical Algorithms". */
694 /* Find the highest nonzero divisor digit. */
697 {
700 }
702 /* Insure that the first digit of the divisor is at least BASE/2.
703 This is required by the quotient digit estimation algorithm. */
710 {
714 }
719 {
724 }
725 }
729 /* Main loop */
731 {
732 /* Guess the next quotient digit, quo_est, by dividing the first
733 two remaining dividend digits by the high order quotient digit.
734 quo_est is never low and is at most 2 high. */
741 else
744 /* Refine quo_est so it's usually correct, and at most one high. */
749 quo_est--;
751 /* Try QUO_EST as the quotient digit, by multiplying the
752 divisor by QUO_EST and subtracting from the remaining dividend.
753 Keep in mind that QUO_EST is the I - 1st digit. */
757 {
763 }
765 /* If quo_est was high by one, then num[i] went negative and
766 we need to correct things. */
768 {
769 quo_est--;
772 {
776 }
779 }
781 /* Store the quotient digit. */
783 }
784 }
788 finish_up:
789 /* If result is negative, make it so. */
793 /* Compute trial remainder: rem = num - (quo * den) */
799 {
808 {
809 /* quo = quo - 1; */
812 }
813 else
820 {
823 }
824 else
830 {
836 /* Get absolute values. */
842 /* If (2 * abs (lrem) >= abs (lden)) */
851 {
853 /* quo = quo - 1; */
856 else
857 /* quo = quo + 1; */
860 }
861 else
863 }
868 }
870 /* Compute true remainder: rem = num - (quo * den) */
875 }
877 /* If ARG2 divides ARG1 with zero remainder, carries out the division
878 of type CODE and returns the quotient.
879 Otherwise returns NULL_TREE. */
881 static tree
883 {
902 }
903 \f
904 /* Return true if the built-in mathematical function specified by CODE
905 is odd, i.e. -f(x) == f(-x). */
907 static bool
909 {
911 {
945 }
947 }
949 /* Check whether we may negate an integer constant T without causing
950 overflow. */
952 bool
954 {
957 tree type;
967 {
972 }
973 else
978 }
980 /* Determine whether an expression T can be cheaply negated using
981 the function negate_expr without introducing undefined overflow. */
983 static bool
985 {
986 tree type;
995 {
1000 /* Check that -CST will not overflow type. */
1022 /* -(A + B) -> (-B) - A. */
1027 /* -(A + B) -> (-A) - B. */
1031 /* We can't turn -(A-B) into B-A when we honor signed zeros. */
1041 /* Fall through. */
1061 /* Negate -((double)float) as (double)(-float). */
1063 {
1067 }
1071 /* Negate -f(x) as f(-x). */
1077 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1079 {
1085 }
1090 }
1092 }
1094 /* Given T, an expression, return a folded tree for -T or NULL_TREE, if no
1095 simplification is possible.
1096 If negate_expr_p would return true for T, NULL_TREE will never be
1097 returned. */
1099 static tree
1101 {
1103 tree tem;
1106 {
1107 /* Convert - (~A) to A + 1. */
1123 /* Two's complement FP formats, such as c4x, may overflow. */
1129 {
1138 }
1154 {
1155 /* -(A + B) -> (-B) - A. */
1159 {
1163 }
1165 /* -(A + B) -> (-A) - B. */
1167 {
1171 }
1172 }
1176 /* - (A - B) -> B - A */
1188 /* Fall through. */
1192 {
1201 }
1210 {
1219 }
1223 /* Convert -((double)float) into (double)(-float). */
1225 {
1229 }
1233 /* Negate -f(x) as f(-x). */
1236 {
1243 }
1247 /* Optimize -((int)x >> 31) into (unsigned)x >> 31. */
1249 {
1254 {
1261 }
1262 }
1267 }
1270 }
1272 /* Like fold_negate_expr, but return a NEGATE_EXPR tree, if T can not be
1273 negated in a simpler way. Also allow for T to be NULL_TREE, in which case
1274 return NULL_TREE. */
1276 static tree
1278 {
1291 }
1292 \f
1293 /* Split a tree IN into a constant, literal and variable parts that could be
1294 combined with CODE to make IN. "constant" means an expression with
1295 TREE_CONSTANT but that isn't an actual constant. CODE must be a
1296 commutative arithmetic operation. Store the constant part into *CONP,
1297 the literal in *LITP and return the variable part. If a part isn't
1298 present, set it to null. If the tree does not decompose in this way,
1299 return the entire tree as the variable part and the other parts as null.
1301 If CODE is PLUS_EXPR we also split trees that use MINUS_EXPR. In that
1302 case, we negate an operand that was subtracted. Except if it is a
1303 literal for which we use *MINUS_LITP instead.
1305 If NEGATE_P is true, we are negating all of IN, again except a literal
1306 for which we use *MINUS_LITP instead.
1308 If IN is itself a literal or constant, return it as appropriate.
1310 Note that we do not guarantee that any of the three values will be the
1311 same type as IN, but they will have the same signedness and mode. */
1313 static tree
1316 {
1323 /* Strip any conversions that don't change the machine mode or signedness. */
1330 /* We can associate addition and subtraction together (even
1331 though the C standard doesn't say so) for integers because
1332 the value is not affected. For reals, the value might be
1333 affected, so we can't. */
1336 {
1342 /* First see if either of the operands is a literal, then a constant. */
1353 /* If we haven't dealt with either operand, this is not a case we can
1354 decompose. Otherwise, VAR is either of the ones remaining, if any. */
1359 else
1362 /* Now do any needed negations. */
1369 }
1372 else
1376 {
1383 }
1386 }
1388 /* Re-associate trees split by the above function. T1 and T2 are either
1389 expressions to associate or null. Return the new expression, if any. If
1390 we build an operation, do it in TYPE and with CODE. */
1392 static tree
1394 {
1400 /* If either input is CODE, a PLUS_EXPR, or a MINUS_EXPR, don't
1401 try to fold this since we will have infinite recursion. But do
1402 deal with any NEGATE_EXPRs. */
1405 {
1407 {
1416 }
1418 {
1421 }
1425 }
1429 }
1430 \f
1431 /* Check whether TYPE1 and TYPE2 are equivalent integer types, suitable
1432 for use in int_const_binop, size_binop and size_diffop. */
1434 static bool
1436 {
1443 {
1452 }
1457 }
1460 /* Combine two integer constants ARG1 and ARG2 under operation CODE
1461 to produce a new constant. Return NULL_TREE if we don't know how
1462 to evaluate CODE at compile-time.
1464 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1466 tree
1468 {
1472 HOST_WIDE_INT hi;
1474 HOST_WIDE_INT garbageh;
1475 tree t;
1478 int is_sizetype
1488 {
1504 /* It's unclear from the C standard whether shifts can overflow.
1505 The following code ignores overflow; perhaps a C standard
1506 interpretation ruling is needed. */
1535 /* This is a shortcut for a common special case. */
1540 {
1546 }
1548 /* ... fall through ... */
1554 {
1557 }
1560 {
1563 }
1570 /* This is a shortcut for a common special case. */
1575 {
1580 }
1582 /* ... fall through ... */
1600 else
1606 else
1612 }
1615 {
1618 /* Propagate overflow flags ourselves. */
1621 {
1624 }
1625 }
1626 else
1632 }
1634 /* Combine two constants ARG1 and ARG2 under operation CODE to produce a new
1635 constant. We assume ARG1 and ARG2 have the same data type, or at least
1636 are the same kind of constant and the same machine mode. Return zero if
1637 combining the constants is not allowed in the current operating mode.
1639 If NOTRUNC is nonzero, do not truncate the result to fit the data type. */
1641 static tree
1643 {
1644 /* Sanity check for the recursive cases. */
1655 {
1657 REAL_VALUE_TYPE d1;
1658 REAL_VALUE_TYPE d2;
1659 REAL_VALUE_TYPE value;
1660 REAL_VALUE_TYPE result;
1664 /* The following codes are handled by real_arithmetic. */
1666 {
1677 }
1685 /* Don't perform operation if we honor signaling NaNs and
1686 either operand is a NaN. */
1691 /* Don't perform operation if it would raise a division
1692 by zero exception. */
1698 /* If either operand is a NaN, just return it. Otherwise, set up
1699 for floating-point trap; we return an overflow. */
1708 /* Don't constant fold this floating point operation if
1709 the result has overflowed and flag_trapping_math. */
1717 /* Don't constant fold this floating point operation if the
1718 result may dependent upon the run-time rounding mode and
1719 flag_rounding_math is set, or if GCC's software emulation
1720 is unable to accurately represent the result. */
1731 }
1734 {
1743 {
1754 notrunc);
1758 notrunc);
1762 {
1763 tree magsquared
1767 notrunc);
1768 tree t1
1772 notrunc);
1773 tree t2
1777 notrunc);
1784 }
1789 }
1793 }
1796 }
1798 /* Create a size type INT_CST node with NUMBER sign extended. KIND
1799 indicates which particular sizetype to create. */
1801 tree
1803 {
1805 }
1806 \f
1807 /* Combine operands OP1 and OP2 with arithmetic operation CODE. CODE
1808 is a tree code. The type of the result is taken from the operands.
1809 Both must be equivalent integer types, ala int_binop_types_match_p.
1810 If the operands are constant, so is the result. */
1812 tree
1814 {
1823 /* Handle the special case of two integer constants faster. */
1825 {
1826 /* And some specific cases even faster than that. */
1828 {
1833 }
1835 {
1838 }
1840 {
1843 }
1845 /* Handle general case of two integer constants. */
1847 }
1850 }
1852 /* Given two values, either both of sizetype or both of bitsizetype,
1853 compute the difference between the two values. Return the value
1854 in signed type corresponding to the type of the operands. */
1856 tree
1858 {
1860 tree ctype;
1865 /* If the type is already signed, just do the simple thing. */
1873 else
1876 /* If either operand is not a constant, do the conversions to the signed
1877 type and subtract. The hardware will do the right thing with any
1878 overflow in the subtraction. */
1883 /* If ARG0 is larger than ARG1, subtract and return the result in CTYPE.
1884 Otherwise, subtract the other way, convert to CTYPE (we know that can't
1885 overflow) and negate (which can't either). Special-case a result
1886 of zero while we're here. */
1891 else
1895 }
1896 \f
1897 /* A subroutine of fold_convert_const handling conversions of an
1898 INTEGER_CST to another integer type. */
1900 static tree
1902 {
1903 tree t;
1905 /* Given an integer constant, make new constant with new type,
1906 appropriately sign-extended or truncated. */
1909 /* Don't set the overflow when
1910 converting a pointer */
1918 }
1920 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1921 to an integer type. */
1923 static tree
1925 {
1927 tree t;
1929 /* The following code implements the floating point to integer
1930 conversion rules required by the Java Language Specification,
1931 that IEEE NaNs are mapped to zero and values that overflow
1932 the target precision saturate, i.e. values greater than
1933 INT_MAX are mapped to INT_MAX, and values less than INT_MIN
1934 are mapped to INT_MIN. These semantics are allowed by the
1935 C and C++ standards that simply state that the behavior of
1936 FP-to-integer conversion is unspecified upon overflow. */
1939 REAL_VALUE_TYPE r;
1943 {
1950 }
1952 /* If R is NaN, return zero and show we have an overflow. */
1954 {
1958 }
1960 /* See if R is less than the lower bound or greater than the
1961 upper bound. */
1964 {
1968 {
1972 }
1973 }
1976 {
1979 {
1982 {
1986 }
1987 }
1988 }
1996 }
1998 /* A subroutine of fold_convert_const handling conversions a REAL_CST
1999 to another floating point type. */
2001 static tree
2003 {
2004 REAL_VALUE_TYPE value;
2005 tree t;
2012 }
2014 /* Attempt to fold type conversion operation CODE of expression ARG1 to
2015 type TYPE. If no simplification can be done return NULL_TREE. */
2017 static tree
2019 {
2024 {
2029 }
2031 {
2036 }
2038 }
2040 /* Construct a vector of zero elements of vector type TYPE. */
2042 static tree
2044 {
2055 }
2057 /* Convert expression ARG to type TYPE. Used by the middle-end for
2058 simple conversions in preference to calling the front-end's convert. */
2060 tree
2062 {
2064 tree tem;
2080 {
2085 {
2089 }
2094 {
2097 }
2104 {
2108 }
2110 {
2114 }
2117 {
2132 }
2136 {
2145 {
2149 {
2153 }
2161 }
2165 }
2183 }
2184 }
2185 \f
2186 /* Return false if expr can be assumed not to be an lvalue, true
2187 otherwise. */
2189 static bool
2191 {
2192 /* We only need to wrap lvalue tree codes. */
2194 {
2229 /* Assume the worst for front-end tree codes. */
2233 }
2236 }
2238 /* Return an expr equal to X but certainly not valid as an lvalue. */
2240 tree
2242 {
2243 /* While we are in GIMPLE, NON_LVALUE_EXPR doesn't mean anything to
2244 us. */
2251 }
2253 /* Nonzero means lvalues are limited to those valid in pedantic ANSI C.
2254 Zero means allow extended lvalues. */
2258 /* When pedantic, return an expr equal to X but certainly not valid as a
2259 pedantic lvalue. Otherwise, return X. */
2261 static tree
2263 {
2266 else
2268 }
2269 \f
2270 /* Given a tree comparison code, return the code that is the logical inverse
2271 of the given code. It is not safe to do this for floating-point
2272 comparisons, except for NE_EXPR and EQ_EXPR, so we receive a machine mode
2273 as well: if reversing the comparison is unsafe, return ERROR_MARK. */
2275 enum tree_code
2277 {
2282 {
2313 }
2314 }
2316 /* Similar, but return the comparison that results if the operands are
2317 swapped. This is safe for floating-point. */
2319 enum tree_code
2321 {
2323 {
2349 }
2350 }
2353 /* Convert a comparison tree code from an enum tree_code representation
2354 into a compcode bit-based encoding. This function is the inverse of
2355 compcode_to_comparison. */
2357 static enum comparison_code
2359 {
2361 {
2392 }
2393 }
2395 /* Convert a compcode bit-based encoding of a comparison operator back
2396 to GCC's enum tree_code representation. This function is the
2397 inverse of comparison_to_compcode. */
2399 static enum tree_code
2401 {
2403 {
2434 }
2435 }
2437 /* Return a tree for the comparison which is the combination of
2438 doing the AND or OR (depending on CODE) of the two operations LCODE
2439 and RCODE on the identical operands LL_ARG and LR_ARG. Take into account
2440 the possibility of trapping if the mode has NaNs, and return NULL_TREE
2441 if this makes the transformation invalid. */
2443 tree
2447 {
2454 {
2465 }
2468 {
2469 /* Eliminate unordered comparisons, as well as LTGT and ORD
2470 which are not used unless the mode has NaNs. */
2476 }
2478 {
2479 /* Check that the original operation and the optimized ones will trap
2480 under the same condition. */
2491 /* In a short-circuited boolean expression the LHS might be
2492 such that the RHS, if evaluated, will never trap. For
2493 example, in ORD (x, y) && (x < y), we evaluate the RHS only
2494 if neither x nor y is NaN. (This is a mixed blessing: for
2495 example, the expression above will never trap, hence
2496 optimizing it to x < y would be invalid). */
2501 /* If the comparison was short-circuited, and only the RHS
2502 trapped, we may now generate a spurious trap. */
2507 /* If we changed the conditions that cause a trap, we lose. */
2510 }
2516 else
2519 }
2521 /* Return nonzero if CODE is a tree code that represents a truth value. */
2523 static int
2525 {
2530 }
2531 \f
2532 /* Return nonzero if two operands (typically of the same tree node)
2533 are necessarily equal. If either argument has side-effects this
2534 function returns zero. FLAGS modifies behavior as follows:
2536 If OEP_ONLY_CONST is set, only return nonzero for constants.
2537 This function tests whether the operands are indistinguishable;
2538 it does not test whether they are equal using C's == operation.
2539 The distinction is important for IEEE floating point, because
2540 (1) -0.0 and 0.0 are distinguishable, but -0.0==0.0, and
2541 (2) two NaNs may be indistinguishable, but NaN!=NaN.
2543 If OEP_ONLY_CONST is unset, a VAR_DECL is considered equal to itself
2544 even though it may hold multiple values during a function.
2545 This is because a GCC tree node guarantees that nothing else is
2546 executed between the evaluation of its "operands" (which may often
2547 be evaluated in arbitrary order). Hence if the operands themselves
2548 don't side-effect, the VAR_DECLs, PARM_DECLs etc... must hold the
2549 same value in each operand/subexpression. Hence leaving OEP_ONLY_CONST
2550 unset means assuming isochronic (or instantaneous) tree equivalence.
2551 Unless comparing arbitrary expression trees, such as from different
2552 statements, this flag can usually be left unset.
2554 If OEP_PURE_SAME is set, then pure functions with identical arguments
2555 are considered the same. It is used when the caller has other ways
2556 to ensure that global memory is unchanged in between. */
2558 int
2560 {
2561 /* If either is ERROR_MARK, they aren't equal. */
2565 /* If both types don't have the same signedness, then we can't consider
2566 them equal. We must check this before the STRIP_NOPS calls
2567 because they may change the signedness of the arguments. */
2571 /* If both types don't have the same precision, then it is not safe
2572 to strip NOPs. */
2579 /* In case both args are comparisons but with different comparison
2580 code, try to swap the comparison operands of one arg to produce
2581 a match and compare that variant. */
2585 {
2593 }
2596 /* This is needed for conversions and for COMPONENT_REF.
2597 Might as well play it safe and always test this. */
2603 /* If ARG0 and ARG1 are the same SAVE_EXPR, they are necessarily equal.
2604 We don't care about side effects in that case because the SAVE_EXPR
2605 takes care of that for us. In all other cases, two expressions are
2606 equal if they have no side effects. If we have two identical
2607 expressions with side effects that should be treated the same due
2608 to the only side effects being identical SAVE_EXPR's, that will
2609 be detected in the recursive calls below. */
2615 /* Next handle constant cases, those for which we can return 1 even
2616 if ONLY_CONST is set. */
2619 {
2630 {
2631 /* If we do not distinguish between signed and unsigned zero,
2632 consider them equal. */
2635 }
2639 {
2645 {
2647 flags))
2651 }
2654 }
2658 flags)
2660 flags));
2673 }
2678 /* Define macros to test an operand from arg0 and arg1 for equality and a
2679 variant that allows null and views null as being different from any
2680 non-null value. In the latter case, if either is null, the both
2681 must be; otherwise, do the normal comparison. */
2682 #define OP_SAME(N) operand_equal_p (TREE_OPERAND (arg0, N), \
2683 TREE_OPERAND (arg1, N), flags)
2685 #define OP_SAME_WITH_NULL(N) \
2686 ((!TREE_OPERAND (arg0, N) || !TREE_OPERAND (arg1, N)) \
2687 ? TREE_OPERAND (arg0, N) == TREE_OPERAND (arg1, N) : OP_SAME (N))
2690 {
2692 /* Two conversions are equal only if signedness and modes match. */
2694 {
2704 }
2714 /* For commutative ops, allow the other order. */
2722 /* If either of the pointer (or reference) expressions we are
2723 dereferencing contain a side effect, these cannot be equal. */
2729 {
2739 /* Operands 2 and 3 may be null. */
2746 /* Handle operand 2 the same as for ARRAY_REF. Operand 0
2747 may be NULL when we're called to compare MEM_EXPRs. */
2757 }
2761 {
2776 /* Otherwise take into account this is a commutative operation. */
2783 /* If the CALL_EXPRs call different functions, then they
2784 clearly can not be equal. */
2788 {
2792 else
2796 }
2798 /* Now see if all the arguments are the same. operand_equal_p
2799 does not handle TREE_LIST, so we walk the operands here
2800 feeding them to operand_equal_p. */
2804 {
2806 flags))
2811 }
2813 /* If we get here and both argument lists are exhausted
2814 then the CALL_EXPRs are equal. */
2819 }
2822 /* Consider __builtin_sqrt equal to sqrt. */
2830 }
2832 #undef OP_SAME
2833 #undef OP_SAME_WITH_NULL
2834 }
2835 \f
2836 /* Similar to operand_equal_p, but see if ARG0 might have been made by
2837 shorten_compare from ARG1 when ARG1 was being compared with OTHER.
2839 When in doubt, return 0. */
2841 static int
2843 {
2855 /* Discard any conversions that don't change the modes of ARG0 and ARG1
2856 and see if the inner values are the same. This removes any
2857 signedness comparison, which doesn't matter here. */
2864 /* Duplicate what shorten_compare does to ARG1 and see if that gives the
2865 actual comparison operand, ARG0.
2867 First throw away any conversions to wider types
2868 already present in the operands. */
2877 {
2880 /* Make sure shorter operand is extended the right way
2881 to match the longer operand. */
2887 }
2890 }
2891 \f
2892 /* See if ARG is an expression that is either a comparison or is performing
2893 arithmetic on comparisons. The comparisons must only be comparing
2894 two different values, which will be stored in *CVAL1 and *CVAL2; if
2895 they are nonzero it means that some operands have already been found.
2896 No variables may be used anywhere else in the expression except in the
2897 comparisons. If SAVE_P is true it means we removed a SAVE_EXPR around
2898 the expression and save_expr needs to be called with CVAL1 and CVAL2.
2900 If this is true, return 1. Otherwise, return zero. */
2902 static int
2904 {
2908 /* We can handle some of the tcc_expression cases here. */
2918 {
2919 /* If we've already found a CVAL1 or CVAL2, this expression is
2920 two complex to handle. */
2926 }
2929 {
2952 /* First see if we can handle the first operand, then the second. For
2953 the second operand, we know *CVAL1 can't be zero. It must be that
2954 one side of the comparison is each of the values; test for the
2955 case where this isn't true by failing if the two operands
2956 are the same. */
2965 ;
2969 ;
2970 else
2974 ;
2978 ;
2979 else
2986 }
2987 }
2988 \f
2989 /* ARG is a tree that is known to contain just arithmetic operations and
2990 comparisons. Evaluate the operations in the tree substituting NEW0 for
2991 any occurrence of OLD0 as an operand of a comparison and likewise for
2992 NEW1 and OLD1. */
2994 static tree
2996 {
3001 /* We can handle some of the tcc_expression cases here. */
3009 {
3024 {
3041 }
3042 /* Fall through - ??? */
3045 {
3049 /* We need to check both for exact equality and tree equality. The
3050 former will be true if the operand has a side-effect. In that
3051 case, we know the operand occurred exactly once. */
3064 }
3068 }
3069 }
3070 \f
3071 /* Return a tree for the case when the result of an expression is RESULT
3072 converted to TYPE and OMITTED was previously an operand of the expression
3073 but is now not needed (e.g., we folded OMITTED * 0).
3075 If OMITTED has side effects, we must evaluate it. Otherwise, just do
3076 the conversion of RESULT to TYPE. */
3078 tree
3080 {
3087 }
3089 /* Similar, but call pedantic_non_lvalue instead of non_lvalue. */
3091 static tree
3093 {
3100 }
3102 /* Return a tree for the case when the result of an expression is RESULT
3103 converted to TYPE and OMITTED1 and OMITTED2 were previously operands
3104 of the expression but are now not needed.
3106 If OMITTED1 or OMITTED2 has side effects, they must be evaluated.
3107 If both OMITTED1 and OMITTED2 have side effects, OMITTED1 is
3108 evaluated before OMITTED2. Otherwise, if neither has side effects,
3109 just do the conversion of RESULT to TYPE. */
3111 tree
3113 {
3122 }
3124 \f
3125 /* Return a simplified tree node for the truth-negation of ARG. This
3126 never alters ARG itself. We assume that ARG is an operation that
3127 returns a truth value (0 or 1).
3129 FIXME: one would think we would fold the result, but it causes
3130 problems with the dominator optimizer. */
3132 tree
3134 {
3138 /* If this is a comparison, we can simply invert it, except for
3139 floating-point non-equality comparisons, in which case we just
3140 enclose a TRUTH_NOT_EXPR around what we have. */
3143 {
3146 && flag_trapping_math
3150 else
3151 {
3156 else
3159 }
3160 }
3163 {
3178 /* Here we can invert either operand. We invert the first operand
3179 unless the second operand is a TRUTH_NOT_EXPR in which case our
3180 result is the XOR of the first operand with the inside of the
3181 negation of the second operand. */
3186 else
3205 {
3208 /* A COND_EXPR may have a throw as one operand, which
3209 then has void type. Just leave void operands
3210 as they are. */
3216 }
3249 }
3252 }
3254 /* Return a simplified tree node for the truth-negation of ARG. This
3255 never alters ARG itself. We assume that ARG is an operation that
3256 returns a truth value (0 or 1).
3258 FIXME: one would think we would fold the result, but it causes
3259 problems with the dominator optimizer. */
3261 tree
3263 {
3264 tree tem;
3274 }
3276 /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both
3277 operands are another bit-wise operation with a common input. If so,
3278 distribute the bit operations to save an operation and possibly two if
3279 constants are involved. For example, convert
3280 (A | B) & (A | C) into A | (B & C)
3281 Further simplification will occur if B and C are constants.
3283 If this optimization cannot be done, 0 will be returned. */
3285 static tree
3287 {
3288 tree common;
3298 {
3302 }
3304 {
3308 }
3310 {
3314 }
3316 {
3320 }
3321 else
3326 }
3328 /* Knowing that ARG0 and ARG1 are both RDIV_EXPRs, simplify a binary operation
3329 with code CODE. This optimization is unsafe. */
3330 static tree
3332 {
3336 /* (A / C) +- (B / C) -> (A +- B) / C. */
3346 /* (A / C1) +- (A / C2) -> A * (1 / C1 +- 1 / C2). */
3351 {
3363 }
3366 }
3367 \f
3368 /* Return a BIT_FIELD_REF of type TYPE to refer to BITSIZE bits of INNER
3369 starting at BITPOS. The field is unsigned if UNSIGNEDP is nonzero. */
3371 static tree
3374 {
3375 tree result;
3378 {
3385 }
3393 }
3395 /* Optimize a bit-field compare.
3397 There are two cases: First is a compare against a constant and the
3398 second is a comparison of two items where the fields are at the same
3399 bit position relative to the start of a chunk (byte, halfword, word)
3400 large enough to contain it. In these cases we can avoid the shift
3401 implicit in bitfield extractions.
3403 For constants, we emit a compare of the shifted constant with the
3404 BIT_AND_EXPR of a mask and a byte, halfword, or word of the operand being
3405 compared. For two fields at the same position, we do the ANDs with the
3406 similar mask and compare the result of the ANDs.
3408 CODE is the comparison code, known to be either NE_EXPR or EQ_EXPR.
3409 COMPARE_TYPE is the type of the comparison, and LHS and RHS
3410 are the left and right operands of the comparison, respectively.
3412 If the optimization described above can be done, we return the resulting
3413 tree. Otherwise we return zero. */
3415 static tree
3418 {
3427 tree mask;
3428 tree offset;
3430 /* Get all the information about the extractions being done. If the bit size
3431 if the same as the size of the underlying object, we aren't doing an
3432 extraction at all and so can do nothing. We also don't want to
3433 do anything if the inner expression is a PLACEHOLDER_EXPR since we
3434 then will no longer be able to replace it. */
3442 {
3443 /* If this is not a constant, we can only do something if bit positions,
3444 sizes, and signedness are the same. */
3452 }
3454 /* See if we can find a mode to refer to this field. We should be able to,
3455 but fail if we can't. */
3464 /* Set signed and unsigned types of the precision of this mode for the
3465 shifts below. */
3469 /* Compute the bit position and size for the new reference and our offset
3470 within it. If the new reference is the same size as the original, we
3471 won't optimize anything, so return zero. */
3481 /* Make the mask to be used against the extracted field. */
3488 /* If not comparing with constant, just rework the comparison
3489 and return. */
3493 unsigned_type,
3496 mask),
3499 unsigned_type,
3502 mask));
3504 /* Otherwise, we are handling the constant case. See if the constant is too
3505 big for the field. Warn and return a tree of for 0 (false) if so. We do
3506 this not only for its own sake, but to avoid having to test for this
3507 error case below. If we didn't, we might generate wrong code.
3509 For unsigned fields, the constant shifted right by the field length should
3510 be all zero. For signed fields, the high-order bits should agree with
3511 the sign bit. */
3514 {
3518 {
3522 }
3523 }
3524 else
3525 {
3529 {
3533 }
3534 }
3536 /* Single-bit compares should always be against zero. */
3538 {
3541 }
3543 /* Make a new bitfield reference, shift the constant over the
3544 appropriate number of bits and mask it with the computed mask
3545 (in case this was a signed field). If we changed it, make a new one. */
3548 {
3551 }
3561 rhs);
3562 }
3563 \f
3564 /* Subroutine for fold_truthop: decode a field reference.
3566 If EXP is a comparison reference, we return the innermost reference.
3568 *PBITSIZE is set to the number of bits in the reference, *PBITPOS is
3569 set to the starting bit number.
3571 If the innermost field can be completely contained in a mode-sized
3572 unit, *PMODE is set to that mode. Otherwise, it is set to VOIDmode.
3574 *PVOLATILEP is set to 1 if the any expression encountered is volatile;
3575 otherwise it is not changed.
3577 *PUNSIGNEDP is set to the signedness of the field.
3579 *PMASK is set to the mask used. This is either contained in a
3580 BIT_AND_EXPR or derived from the width of the field.
3582 *PAND_MASK is set to the mask found in a BIT_AND_EXPR, if any.
3584 Return 0 if this is not a component reference or is one that we can't
3585 do anything with. */
3587 static tree
3592 {
3596 tree unsigned_type;
3599 /* All the optimizations using this function assume integer fields.
3600 There are problems with FP fields since the type_for_size call
3601 below can fail for, e.g., XFmode. */
3605 /* We are interested in the bare arrangement of bits, so strip everything
3606 that doesn't affect the machine mode. However, record the type of the
3607 outermost expression if it may matter below. */
3615 {
3621 }
3630 /* If the number of bits in the reference is the same as the bitsize of
3631 the outer type, then the outer type gives the signedness. Otherwise
3632 (in case of a small bitfield) the signedness is unchanged. */
3636 /* Compute the mask to access the bitfield. */
3645 /* Merge it with the mask we found in the BIT_AND_EXPR, if any. */
3653 }
3655 /* Return nonzero if MASK represents a mask of SIZE ones in the low-order
3656 bit positions. */
3658 static int
3660 {
3663 tree tmask;
3667 return
3674 }
3676 /* Subroutine for fold: determine if VAL is the INTEGER_CONST that
3677 represents the sign bit of EXP's type. If EXP represents a sign
3678 or zero extension, also test VAL against the unextended type.
3679 The return value is the (sub)expression whose sign bit is VAL,
3680 or NULL_TREE otherwise. */
3682 static tree
3684 {
3688 tree t;
3690 /* Tree EXP must have an integral type. */
3695 /* Tree VAL must be an integer constant. */
3702 {
3709 }
3710 else
3711 {
3718 }
3720 /* We mask off those bits beyond TREE_TYPE (exp) so that we can
3721 treat VAL as if it were unsigned. */
3726 /* Handle extension from a narrower type. */
3732 }
3734 /* Subroutine for fold_truthop: determine if an operand is simple enough
3735 to be evaluated unconditionally. */
3737 static int
3739 {
3740 /* Strip any conversions that don't change the machine mode. */
3749 /* Don't regard global variables as simple. They may be
3750 allocated in ways unknown to the compiler (shared memory,
3751 #pragma weak, etc). */
3754 /* Loading a static variable is unduly expensive, but global
3755 registers aren't expensive. */
3757 }
3758 \f
3759 /* The following functions are subroutines to fold_range_test and allow it to
3760 try to change a logical combination of comparisons into a range test.
3762 For example, both
3763 X == 2 || X == 3 || X == 4 || X == 5
3764 and
3765 X >= 2 && X <= 5
3766 are converted to
3767 (unsigned) (X - 2) <= 3
3769 We describe each set of comparisons as being either inside or outside
3770 a range, using a variable named like IN_P, and then describe the
3771 range with a lower and upper bound. If one of the bounds is omitted,
3772 it represents either the highest or lowest value of the type.
3774 In the comments below, we represent a range by two numbers in brackets
3775 preceded by a "+" to designate being inside that range, or a "-" to
3776 designate being outside that range, so the condition can be inverted by
3777 flipping the prefix. An omitted bound is represented by a "-". For
3778 example, "- [-, 10]" means being outside the range starting at the lowest
3779 possible value and ending at 10, in other words, being greater than 10.
3780 The range "+ [-, -]" is always true and hence the range "- [-, -]" is
3781 always false.
3783 We set up things so that the missing bounds are handled in a consistent
3784 manner so neither a missing bound nor "true" and "false" need to be
3785 handled using a special case. */
3787 /* Return the result of applying CODE to ARG0 and ARG1, but handle the case
3788 of ARG0 and/or ARG1 being omitted, meaning an unlimited range. UPPER0_P
3789 and UPPER1_P are nonzero if the respective argument is an upper bound
3790 and zero for a lower. TYPE, if nonzero, is the type of the result; it
3791 must be specified for a comparison. ARG1 will be converted to ARG0's
3792 type if both are specified. */
3794 static tree
3797 {
3798 tree tem;
3802 /* If neither arg represents infinity, do the normal operation.
3803 Else, if not a comparison, return infinity. Else handle the special
3804 comparison rules. Note that most of the cases below won't occur, but
3805 are handled for consistency. */
3808 {
3813 }
3818 /* Set SGN[01] to -1 if ARG[01] is a lower bound, 1 for upper, and 0
3819 for neither. In real maths, we cannot assume open ended ranges are
3820 the same. But, this is computer arithmetic, where numbers are finite.
3821 We can therefore make the transformation of any unbounded range with
3822 the value Z, Z being greater than any representable number. This permits
3823 us to treat unbounded ranges as equal. */
3827 {
3848 }
3851 }
3852 \f
3853 /* Given EXP, a logical expression, set the range it is testing into
3854 variables denoted by PIN_P, PLOW, and PHIGH. Return the expression
3855 actually being tested. *PLOW and *PHIGH will be made of the same type
3856 as the returned expression. If EXP is not a comparison, we will most
3857 likely not be returning a useful value and range. */
3859 static tree
3861 {
3868 /* Start with simply saying "EXP != 0" and then look at the code of EXP
3869 and see if we can refine the range. Some of the cases below may not
3870 happen, but it doesn't seem worth worrying about this. We "continue"
3871 the outer loop when we've changed something; otherwise we "break"
3872 the switch, which will "break" the while. */
3878 {
3883 {
3895 }
3898 {
3905 /* We can only do something if the range is testing for zero
3906 and if the second operand is an integer constant. Note that
3907 saying something is "in" the range we make is done by
3908 complementing IN_P since it will set in the initial case of
3909 being not equal to zero; "out" is leaving it alone. */
3916 {
3937 }
3939 /* If this is an unsigned comparison, we also know that EXP is
3940 greater than or equal to zero. We base the range tests we make
3941 on that fact, so we record it here so we can parse existing
3942 range tests. We test arg0_type since often the return type
3943 of, e.g. EQ_EXPR, is boolean. */
3945 {
3949 NULL_TREE))
3954 /* If the high bound is missing, but we have a nonzero low
3955 bound, reverse the range so it goes from zero to the low bound
3956 minus 1. */
3958 {
3963 }
3964 }
3970 /* (-x) IN [a,b] -> x in [-b, -a] */
3982 /* ~ X -> -X - 1 */
3991 /* If flag_wrapv and ARG0_TYPE is signed, then we cannot
3992 move a constant to the other side. */
3997 /* If EXP is signed, any overflow in the computation is undefined,
3998 so we don't worry about it so long as our computations on
3999 the bounds don't overflow. For unsigned, overflow is defined
4000 and this is exactly the right thing. */
4009 /* Check for an unsigned range which has wrapped around the maximum
4010 value thus making n_high < n_low, and normalize it. */
4012 {
4018 /* If the range is of the form +/- [ x+1, x ], we won't
4019 be able to normalize it. But then, it represents the
4020 whole range or the empty set, so make it
4021 +/- [ -, - ]. */
4025 else
4027 }
4028 else
4052 /* If we're converting arg0 from an unsigned type, to exp,
4053 a signed type, we will be doing the comparison as unsigned.
4054 The tests above have already verified that LOW and HIGH
4055 are both positive.
4057 So we have to ensure that we will handle large unsigned
4058 values the same way that the current signed bounds treat
4059 negative values. */
4062 {
4063 tree high_positive;
4067 /* A range without an upper bound is, naturally, unbounded.
4068 Since convert would have cropped a very large value, use
4069 the max value for the destination type. */
4070 high_positive
4077 high_positive),
4080 /* If the low bound is specified, "and" the range with the
4081 range for which the original unsigned value will be
4082 positive. */
4084 {
4088 integer_zero_node),
4089 high_positive))
4093 }
4094 else
4095 {
4096 /* Otherwise, "or" the range with the range of the input
4097 that will be interpreted as negative. */
4101 integer_zero_node),
4102 high_positive))
4106 }
4107 }
4115 }
4118 }
4120 /* If EXP is a constant, we can evaluate whether this is true or false. */
4122 {
4129 }
4133 }
4134 \f
4135 /* Given a range, LOW, HIGH, and IN_P, an expression, EXP, and a result
4136 type, TYPE, return an expression to test if EXP is in (or out of, depending
4137 on IN_P) the range. Return 0 if the test couldn't be created. */
4139 static tree
4141 {
4143 tree value;
4145 #ifdef HAVE_canonicalize_funcptr_for_compare
4146 /* Disable this optimization for function pointer expressions
4147 on targets that require function pointer canonicalization. */
4152 #endif
4155 {
4161 }
4179 {
4181 {
4185 }
4187 }
4189 /* Optimize (c>=1) && (c<=127) into (signed char)c > 0. */
4191 {
4193 HOST_WIDE_INT hi;
4198 {
4201 }
4202 else
4203 {
4206 }
4209 {
4211 {
4214 }
4217 }
4218 }
4220 /* Optimize (c>=low) && (c<=high) into (c-low>=0) && (c-low<=high-low).
4221 This requires wrap-around arithmetics for the type of the expression. */
4223 {
4225 /* There is no requirement that LOW be within the range of ETYPE
4226 if the latter is a subtype. It must, however, be within the base
4227 type of ETYPE. So be sure we do the subtraction in that type. */
4240 }
4242 /* If we don't have wrap-around arithmetics upfront, try to force it. */
4245 {
4248 /* Check if (unsigned) INT_MAX + 1 == (unsigned) INT_MIN
4249 for the type in question, as we rely on this here. */
4259 else
4261 }
4275 }
4276 \f
4277 /* Return the predecessor of VAL in its type, handling the infinite case. */
4279 static tree
4281 {
4287 else
4289 }
4291 /* Return the successor of VAL in its type, handling the infinite case. */
4293 static tree
4295 {
4301 else
4303 }
4305 /* Given two ranges, see if we can merge them into one. Return 1 if we
4306 can, 0 if we can't. Set the output range into the specified parameters. */
4308 static int
4311 {
4315 tree tem;
4325 /* Make range 0 be the range that starts first, or ends last if they
4326 start at the same value. Swap them if it isn't. */
4329 || (lowequal
4332 {
4336 }
4338 /* Now flag two cases, whether the ranges are disjoint or whether the
4339 second range is totally subsumed in the first. Note that the tests
4340 below are simplified by the ones above. */
4346 /* We now have four cases, depending on whether we are including or
4347 excluding the two ranges. */
4349 {
4350 /* If they don't overlap, the result is false. If the second range
4351 is a subset it is the result. Otherwise, the range is from the start
4352 of the second to the end of the first. */
4357 else
4359 }
4362 {
4363 /* If they don't overlap, the result is the first range. If they are
4364 equal, the result is false. If the second range is a subset of the
4365 first, and the ranges begin at the same place, we go from just after
4366 the end of the second range to the end of the first. If the second
4367 range is not a subset of the first, or if it is a subset and both
4368 ranges end at the same place, the range starts at the start of the
4369 first range and ends just before the second range.
4370 Otherwise, we can't describe this as a single range. */
4376 {
4380 }
4382 {
4386 }
4387 else
4389 }
4392 {
4393 /* If they don't overlap, the result is the second range. If the second
4394 is a subset of the first, the result is false. Otherwise,
4395 the range starts just after the first range and ends at the
4396 end of the second. */
4401 else
4402 {
4406 }
4407 }
4409 else
4410 {
4411 /* The case where we are excluding both ranges. Here the complex case
4412 is if they don't overlap. In that case, the only time we have a
4413 range is if they are adjacent. If the second is a subset of the
4414 first, the result is the first. Otherwise, the range to exclude
4415 starts at the beginning of the first range and ends at the end of the
4416 second. */
4418 {
4423 else
4424 {
4425 /* Canonicalize - [min, x] into - [-, x]. */
4428 {
4433 /* FALLTHROUGH */
4446 }
4448 /* Canonicalize - [x, max] into - [x, -]. */
4451 {
4456 /* FALLTHROUGH */
4471 }
4473 /* The ranges might be also adjacent between the maximum and
4474 minimum values of the given type. For
4475 - [{min,-}, x] and - [y, {max,-}] ranges where x + 1 < y
4476 return + [x + 1, y - 1]. */
4478 {
4485 }
4486 else
4488 }
4489 }
4492 else
4494 }
4498 }
4499 \f
4501 /* Subroutine of fold, looking inside expressions of the form
4502 A op B ? A : C, where ARG0, ARG1 and ARG2 are the three operands
4503 of the COND_EXPR. This function is being used also to optimize
4504 A op B ? C : A, by reversing the comparison first.
4506 Return a folded expression whose code is not a COND_EXPR
4507 anymore, or NULL_TREE if no folding opportunity is found. */
4509 static tree
4511 {
4516 tree tem;
4521 /* If we have A op 0 ? A : -A, consider applying the following
4522 transformations:
4524 A == 0? A : -A same as -A
4525 A != 0? A : -A same as A
4526 A >= 0? A : -A same as abs (A)
4527 A > 0? A : -A same as abs (A)
4528 A <= 0? A : -A same as -abs (A)
4529 A < 0? A : -A same as -abs (A)
4531 None of these transformations work for modes with signed
4532 zeros. If A is +/-0, the first two transformations will
4533 change the sign of the result (from +0 to -0, or vice
4534 versa). The last four will fix the sign of the result,
4535 even though the original expressions could be positive or
4536 negative, depending on the sign of A.
4538 Note that all these transformations are correct if A is
4539 NaN, since the two alternatives (A and -A) are also NaNs. */
4545 /* In the case that A is of the form X-Y, '-A' (arg2) may
4546 have already been folded to Y-X, check for that. */
4554 {
4566 /* Fall through. */
4588 }
4590 /* A != 0 ? A : 0 is simply A, unless A is -0. Likewise
4591 A == 0 ? A : 0 is always 0 unless A is -0. Note that
4592 both transformations are correct when A is NaN: A != 0
4593 is then true, and A == 0 is false. */
4596 {
4601 }
4603 /* Try some transformations of A op B ? A : B.
4605 A == B? A : B same as B
4606 A != B? A : B same as A
4607 A >= B? A : B same as max (A, B)
4608 A > B? A : B same as max (B, A)
4609 A <= B? A : B same as min (A, B)
4610 A < B? A : B same as min (B, A)
4612 As above, these transformations don't work in the presence
4613 of signed zeros. For example, if A and B are zeros of
4614 opposite sign, the first two transformations will change
4615 the sign of the result. In the last four, the original
4616 expressions give different results for (A=+0, B=-0) and
4617 (A=-0, B=+0), but the transformed expressions do not.
4619 The first two transformations are correct if either A or B
4620 is a NaN. In the first transformation, the condition will
4621 be false, and B will indeed be chosen. In the case of the
4622 second transformation, the condition A != B will be true,
4623 and A will be chosen.
4625 The conversions to max() and min() are not correct if B is
4626 a number and A is not. The conditions in the original
4627 expressions will be false, so all four give B. The min()
4628 and max() versions would give a NaN instead. */
4630 /* Avoid these transformations if the COND_EXPR may be used
4631 as an lvalue in the C++ front-end. PR c++/19199. */
4632 && (in_gimple_form
4637 {
4642 /* Avoid adding NOP_EXPRs in case this is an lvalue. */
4644 {
4648 }
4651 {
4660 /* In C++ a ?: expression can be an lvalue, so put the
4661 operand which will be used if they are equal first
4662 so that we can convert this back to the
4663 corresponding COND_EXPR. */
4665 {
4672 }
4679 {
4686 }
4699 }
4700 }
4702 /* If this is A op C1 ? A : C2 with C1 and C2 constant integers,
4703 we might still be able to simplify this. For example,
4704 if C1 is one less or one more than C2, this might have started
4705 out as a MIN or MAX and been transformed by this function.
4706 Only good for INTEGER_TYPEs, because we need TYPE_MAX_VALUE. */
4712 {
4714 /* We can replace A with C1 in this case. */
4719 /* If C1 is C2 + 1, this is min(A, C2). */
4721 OEP_ONLY_CONST)
4725 OEP_ONLY_CONST))
4731 /* If C1 is C2 - 1, this is min(A, C2). */
4733 OEP_ONLY_CONST)
4737 OEP_ONLY_CONST))
4743 /* If C1 is C2 - 1, this is max(A, C2). */
4745 OEP_ONLY_CONST)
4749 OEP_ONLY_CONST))
4755 /* If C1 is C2 + 1, this is max(A, C2). */
4757 OEP_ONLY_CONST)
4761 OEP_ONLY_CONST))
4769 }
4772 }
4775 \f
4776 #ifndef LOGICAL_OP_NON_SHORT_CIRCUIT
4777 #define LOGICAL_OP_NON_SHORT_CIRCUIT (BRANCH_COST >= 2)
4778 #endif
4780 /* EXP is some logical combination of boolean tests. See if we can
4781 merge it into some range test. Return the new tree if so. */
4783 static tree
4785 {
4792 tree tem;
4794 /* If this is an OR operation, invert both sides; we will invert
4795 again at the end. */
4799 /* If both expressions are the same, if we can merge the ranges, and we
4800 can build the range test, return it or it inverted. If one of the
4801 ranges is always true or always false, consider it to be the same
4802 expression as the other. */
4812 /* On machines where the branch cost is expensive, if this is a
4813 short-circuited branch and the underlying object on both sides
4814 is the same, make a non-short-circuit operation. */
4820 {
4821 /* If simple enough, just rewrite. Otherwise, make a SAVE_EXPR
4822 unless we are at top level or LHS contains a PLACEHOLDER_EXPR, in
4823 which cases we can't do this. */
4831 {
4843 }
4844 }
4847 }
4848 \f
4849 /* Subroutine for fold_truthop: C is an INTEGER_CST interpreted as a P
4850 bit value. Arrange things so the extra bits will be set to zero if and
4851 only if C is signed-extended to its full width. If MASK is nonzero,
4852 it is an INTEGER_CST that should be AND'ed with the extra bits. */
4854 static tree
4856 {
4859 tree temp;
4864 /* We work by getting just the sign bit into the low-order bit, then
4865 into the high-order bit, then sign-extend. We then XOR that value
4866 with C. */
4870 /* We must use a signed type in order to get an arithmetic right shift.
4871 However, we must also avoid introducing accidental overflows, so that
4872 a subsequent call to integer_zerop will work. Hence we must
4873 do the type conversion here. At this point, the constant is either
4874 zero or one, and the conversion to a signed type can never overflow.
4875 We could get an overflow if this conversion is done anywhere else. */
4884 /* If necessary, convert the type back to match the type of C. */
4889 }
4890 \f
4891 /* Find ways of folding logical expressions of LHS and RHS:
4892 Try to merge two comparisons to the same innermost item.
4893 Look for range tests like "ch >= '0' && ch <= '9'".
4894 Look for combinations of simple terms on machines with expensive branches
4895 and evaluate the RHS unconditionally.
4897 For example, if we have p->a == 2 && p->b == 4 and we can make an
4898 object large enough to span both A and B, we can do this with a comparison
4899 against the object ANDed with the a mask.
4901 If we have p->a == q->a && p->b == q->b, we may be able to use bit masking
4902 operations to do this with one comparison.
4904 We check for both normal comparisons and the BIT_AND_EXPRs made this by
4905 function and the one above.
4907 CODE is the logical operation being done. It can be TRUTH_ANDIF_EXPR,
4908 TRUTH_AND_EXPR, TRUTH_ORIF_EXPR, or TRUTH_OR_EXPR.
4910 TRUTH_TYPE is the type of the logical operand and LHS and RHS are its
4911 two operands.
4913 We return the simplified tree or 0 if no optimization is possible. */
4915 static tree
4917 {
4918 /* If this is the "or" of two comparisons, we can do something if
4919 the comparisons are NE_EXPR. If this is the "and", we can do something
4920 if the comparisons are EQ_EXPR. I.e.,
4921 (a->b == 2 && a->c == 4) can become (a->new == NEW).
4923 WANTED_CODE is this operation code. For single bit fields, we can
4924 convert EQ_EXPR to NE_EXPR so we need not reject the "wrong"
4925 comparison for one-bit fields. */
4947 /* Start by getting the comparison codes. Fail if anything is volatile.
4948 If one operand is a BIT_AND_EXPR with the constant one, treat it as if
4949 it were surrounded with a NE_EXPR. */
4958 {
4962 }
4965 {
4969 }
4980 /* Simplify (x<y) && (x==y) into (x<=y) and related optimizations. */
4983 {
4984 tree result;
4987 {
4992 }
4995 {
5001 }
5002 }
5007 /* If the RHS can be evaluated unconditionally and its operands are
5008 simple, it wins to evaluate the RHS unconditionally on machines
5009 with expensive branches. In this case, this isn't a comparison
5010 that can be merged. Avoid doing this if the RHS is a floating-point
5011 comparison since those can trap. */
5017 {
5018 /* Convert (a != 0) || (b != 0) into (a | b) != 0. */
5028 /* Convert (a == 0) && (b == 0) into (a | b) == 0. */
5039 {
5043 }
5044 }
5046 /* See if the comparisons can be merged. Then get all the parameters for
5047 each side. */
5071 /* It must be true that the inner operation on the lhs of each
5072 comparison must be the same if we are to be able to do anything.
5073 Then see if we have constants. If not, the same must be true for
5074 the rhs's. */
5085 else
5088 /* If either comparison code is not correct for our logical operation,
5089 fail. However, we can convert a one-bit comparison against zero into
5090 the opposite comparison against that bit being set in the field. */
5094 {
5096 {
5097 /* Make the left operand unsigned, since we are only interested
5098 in the value of one bit. Otherwise we are doing the wrong
5099 thing below. */
5102 }
5103 else
5105 }
5107 /* This is analogous to the code for l_const above. */
5109 {
5111 {
5114 }
5115 else
5117 }
5119 /* See if we can find a mode that contains both fields being compared on
5120 the left. If we can't, fail. Otherwise, update all constants and masks
5121 to be relative to a field of that size. */
5126 volatilep);
5136 {
5139 }
5147 {
5155 {
5159 }
5160 }
5162 {
5170 {
5174 }
5175 }
5177 /* If the right sides are not constant, do the same for it. Also,
5178 disallow this optimization if a size or signedness mismatch occurs
5179 between the left and right sides. */
5181 {
5184 /* Make sure the two fields on the right
5185 correspond to the left without being swapped. */
5193 volatilep);
5203 {
5206 }
5213 /* Make a mask that corresponds to both fields being compared.
5214 Do this for both items being compared. If the operands are the
5215 same size and the bits being compared are in the same position
5216 then we can do this by masking both and comparing the masked
5217 results. */
5221 {
5233 }
5235 /* There is still another way we can do something: If both pairs of
5236 fields being compared are adjacent, we may be able to make a wider
5237 field containing them both.
5239 Note that we still must mask the lhs/rhs expressions. Furthermore,
5240 the mask must be shifted to account for the shift done by
5241 make_bit_field_ref. */
5246 {
5247 tree type;
5259 /* Convert to the smaller type before masking out unwanted bits. */
5262 {
5264 {
5268 }
5270 {
5274 }
5275 }
5284 }
5287 }
5289 /* Handle the case of comparisons with constants. If there is something in
5290 common between the masks, those bits of the constants must be the same.
5291 If not, the condition is always false. Test for this to avoid generating
5292 incorrect code below. */
5297 {
5299 {
5302 }
5303 else
5304 {
5307 }
5308 }
5310 /* Construct the expression we will return. First get the component
5311 reference we will make. Unless the mask is all ones the width of
5312 that field, perform the mask operation. Then compare with the
5313 merged constant. */
5323 }
5324 \f
5325 /* Optimize T, which is a comparison of a MIN_EXPR or MAX_EXPR with a
5326 constant. */
5328 static tree
5330 {
5334 tree minmax_const;
5336 tree inner;
5346 /* If something does not permit us to optimize, return the original tree. */
5354 /* Now handle all the various comparison codes. We only handle EQ_EXPR
5355 and GT_EXPR, doing the rest with recursive calls using logical
5356 simplifications. */
5358 {
5360 {
5366 }
5369 return
5371 optimize_minmax_comparison
5373 optimize_minmax_comparison
5378 /* MAX (X, 0) == 0 -> X <= 0 */
5382 /* MAX (X, 0) == 5 -> X == 5 */
5386 /* MAX (X, 0) == -1 -> false */
5390 /* MIN (X, 0) == 0 -> X >= 0 */
5394 /* MIN (X, 0) == 5 -> false */
5397 else
5398 /* MIN (X, 0) == -1 -> X == -1 */
5403 /* MAX (X, 0) > 0 -> X > 0
5404 MAX (X, 0) > 5 -> X > 5 */
5408 /* MAX (X, 0) > -1 -> true */
5412 /* MIN (X, 0) > 0 -> false
5413 MIN (X, 0) > 5 -> false */
5416 else
5417 /* MIN (X, 0) > -1 -> X > -1 */
5422 }
5423 }
5424 \f
5425 /* T is an integer expression that is being multiplied, divided, or taken a
5426 modulus (CODE says which and what kind of divide or modulus) by a
5427 constant C. See if we can eliminate that operation by folding it with
5428 other operations already in T. WIDE_TYPE, if non-null, is a type that
5429 should be used for the computation if wider than our type.
5431 For example, if we are dividing (X * 8) + (Y * 16) by 4, we can return
5432 (X * 2) + (Y * 4). We must, however, be assured that either the original
5433 expression would not overflow or that overflow is undefined for the type
5434 in the language in question.
5436 We also canonicalize (X + 7) * 4 into X * 4 + 28 in the hope that either
5437 the machine has a multiply-accumulate insn or that this is part of an
5438 addressing calculation.
5440 If we return a non-null expression, it is an equivalent form of the
5441 original computation, but need not be in the original type. */
5443 static tree
5445 {
5446 /* To avoid exponential search depth, refuse to allow recursion past
5447 three levels. Beyond that (1) it's highly unlikely that we'll find
5448 something interesting and (2) we've probably processed it before
5449 when we built the inner expression. */
5452 tree ret;
5457 depth++;
5459 depth--;
5462 }
5464 static tree
5466 {
5476 /* Don't deal with constants of zero here; they confuse the code below. */
5486 /* Note that we need not handle conditional operations here since fold
5487 already handles those cases. So just do arithmetic here. */
5489 {
5491 /* For a constant, we can always simplify if we are a multiply
5492 or (for divide and modulus) if it is a multiple of our constant. */
5500 /* If op0 is an expression ... */
5505 /* ... and is unsigned, and its type is smaller than ctype,
5506 then we cannot pass through as widening. */
5512 /* ... or this is a truncation (t is narrower than op0),
5513 then we cannot pass through this narrowing. */
5516 /* ... or signedness changes for division or modulus,
5517 then we cannot pass through this conversion. */
5523 /* Pass the constant down and see if we can make a simplification. If
5524 we can, replace this expression with the inner simplification for
5525 possible later conversion to our or some other type. */
5530 code == MULT_EXPR
5536 /* If widening the type changes it from signed to unsigned, then we
5537 must avoid building ABS_EXPR itself as unsigned. */
5539 {
5542 {
5545 }
5547 }
5548 /* FALLTHROUGH */
5555 /* If widening the type changes the signedness, then we can't perform
5556 this optimization as that changes the result. */
5560 /* MIN (a, b) / 5 -> MIN (a / 5, b / 5) */
5563 {
5569 }
5573 /* If the second operand is constant, this is a multiplication
5574 or floor division, by a power of two, so we can treat it that
5575 way unless the multiplier or divisor overflows. Signed
5576 left-shift overflow is implementation-defined rather than
5577 undefined in C90, so do not convert signed left shift into
5578 multiplication. */
5581 /* const_binop may not detect overflow correctly,
5582 so check for it explicitly here. */
5587 size_one_node,
5597 /* See if we can eliminate the operation on both sides. If we can, we
5598 can return a new PLUS or MINUS. If we can't, the only remaining
5599 cases where we can do anything are if the second operand is a
5600 constant. */
5605 /* If not multiplication, we can only do this if both operands
5606 are divisible by c. */
5612 /* If this was a subtraction, negate OP1 and set it to be an addition.
5613 This simplifies the logic below. */
5620 /* If either OP1 or C are negative, this optimization is not safe for
5621 some of the division and remainder types while for others we need
5622 to change the code. */
5624 {
5632 }
5634 /* If it's a multiply or a division/modulus operation of a multiple
5635 of our constant, do the operation and verify it doesn't overflow. */
5638 {
5641 /* We allow the constant to overflow with wrapping semantics. */
5645 }
5646 else
5649 /* If we have an unsigned type is not a sizetype, we cannot widen
5650 the operation since it will change the result if the original
5651 computation overflowed. */
5657 /* If we were able to eliminate our operation from the first side,
5658 apply our operation to the second side and reform the PLUS. */
5662 /* The last case is if we are a multiply. In that case, we can
5663 apply the distributive law to commute the multiply and addition
5664 if the multiplication of the constants doesn't overflow. */
5670 op1);
5675 /* We have a special case here if we are doing something like
5676 (C * 8) % 4 since we know that's zero. */
5683 /* ... fall through ... */
5687 /* If we can extract our operation from the LHS, do so and return a
5688 new operation. Likewise for the RHS from a MULT_EXPR. Otherwise,
5689 do something only if the second operand is a constant. */
5701 /* If these are the same operation types, we can associate them
5702 assuming no overflow. */
5709 /* If these operations "cancel" each other, we have the main
5710 optimizations of this pass, which occur when either constant is a
5711 multiple of the other, in which case we replace this with either an
5712 operation or CODE or TCODE.
5714 If we have an unsigned type that is not a sizetype, we cannot do
5715 this since it will change the result if the original computation
5716 overflowed. */
5723 {
5734 }
5739 }
5742 }
5743 \f
5744 /* Return a node which has the indicated constant VALUE (either 0 or
5745 1), and is of the indicated TYPE. */
5747 tree
5749 {
5754 else
5756 }
5759 /* Return true if expr looks like an ARRAY_REF and set base and
5760 offset to the appropriate trees. If there is no offset,
5761 offset is set to NULL_TREE. Base will be canonicalized to
5762 something you can get the element type from using
5763 TREE_TYPE (TREE_TYPE (base)). Offset will be the offset
5764 in bytes to the base. */
5766 static bool
5768 {
5769 /* One canonical form is a PLUS_EXPR with the first
5770 argument being an ADDR_EXPR with a possible NOP_EXPR
5771 attached. */
5773 {
5776 /* Strip NOP_EXPRs here because the C frontends and/or
5777 folders present us (int *)&x.a + 4B possibly. */
5780 {
5784 else
5788 }
5789 }
5790 /* Other canonical form is an ADDR_EXPR of an ARRAY_REF,
5791 which we transform into an ADDR_EXPR with appropriate
5792 offset. For other arguments to the ADDR_EXPR we assume
5793 zero offset and as such do not care about the ADDR_EXPR
5794 type and strip possible nops from it. */
5796 {
5799 {
5804 }
5805 else
5806 {
5807 /* Handle array-to-pointer decay as &a. */
5810 else
5813 }
5815 }
5816 /* The next canonical form is a VAR_DECL with POINTER_TYPE. */
5819 {
5823 }
5826 }
5829 /* Transform `a + (b ? x : y)' into `b ? (a + x) : (a + y)'.
5830 Transform, `a + (x < y)' into `(x < y) ? (a + 1) : (a + 0)'. Here
5831 CODE corresponds to the `+', COND to the `(b ? x : y)' or `(x < y)'
5832 expression, and ARG to `a'. If COND_FIRST_P is nonzero, then the
5833 COND is the first argument to CODE; otherwise (as in the example
5834 given here), it is the second argument. TYPE is the type of the
5835 original expression. Return NULL_TREE if no simplification is
5836 possible. */
5838 static tree
5842 {
5849 /* This transformation is only worthwhile if we don't have to wrap
5850 arg in a SAVE_EXPR, and the operation can be simplified on at least
5851 one of the branches once its pushed inside the COND_EXPR. */
5856 {
5860 /* If this operand throws an expression, then it does not make
5861 sense to try to perform a logical or arithmetic operation
5862 involving it. */
5867 }
5868 else
5869 {
5874 }
5878 {
5882 else
5884 }
5886 {
5890 else
5892 }
5896 }
5898 \f
5899 /* Subroutine of fold() that checks for the addition of +/- 0.0.
5901 If !NEGATE, return true if ADDEND is +/-0.0 and, for all X of type
5902 TYPE, X + ADDEND is the same as X. If NEGATE, return true if X -
5903 ADDEND is the same as X.
5905 X + 0 and X - 0 both give X when X is NaN, infinite, or nonzero
5906 and finite. The problematic cases are when X is zero, and its mode
5907 has signed zeros. In the case of rounding towards -infinity,
5908 X - 0 is not the same as X because 0 - 0 is -0. In other rounding
5909 modes, X + 0 is not the same as X because -0 + 0 is 0. */
5911 static bool
5913 {
5917 /* Don't allow the fold with -fsignaling-nans. */
5921 /* Allow the fold if zeros aren't signed, or their sign isn't important. */
5925 /* Treat x + -0 as x - 0 and x - -0 as x + 0. */
5930 /* The mode has signed zeros, and we have to honor their sign.
5931 In this situation, there is only one case we can return true for.
5932 X - 0 is the same as X unless rounding towards -infinity is
5933 supported. */
5935 }
5937 /* Subroutine of fold() that checks comparisons of built-in math
5938 functions against real constants.
5940 FCODE is the DECL_FUNCTION_CODE of the built-in, CODE is the comparison
5941 operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR, GE_EXPR or LE_EXPR. TYPE
5942 is the type of the result and ARG0 and ARG1 are the operands of the
5943 comparison. ARG1 must be a TREE_REAL_CST.
5945 The function returns the constant folded tree if a simplification
5946 can be made, and NULL_TREE otherwise. */
5948 static tree
5951 {
5952 REAL_VALUE_TYPE c;
5955 {
5961 {
5962 /* sqrt(x) < y is always false, if y is negative. */
5966 /* sqrt(x) > y is always true, if y is negative and we
5967 don't care about NaNs, i.e. negative values of x. */
5971 /* sqrt(x) > y is the same as x >= 0, if y is negative. */
5974 }
5976 {
5977 REAL_VALUE_TYPE c2;
5983 {
5984 /* sqrt(x) > y is x == +Inf, when y is very large. */
5989 /* sqrt(x) > y is always false, when y is very large
5990 and we don't care about infinities. */
5992 }
5994 /* sqrt(x) > c is the same as x > c*c. */
5997 }
5999 {
6000 REAL_VALUE_TYPE c2;
6006 {
6007 /* sqrt(x) < y is always true, when y is a very large
6008 value and we don't care about NaNs or Infinities. */
6012 /* sqrt(x) < y is x != +Inf when y is very large and we
6013 don't care about NaNs. */
6018 /* sqrt(x) < y is x >= 0 when y is very large and we
6019 don't care about Infinities. */
6024 /* sqrt(x) < y is x >= 0 && x != +Inf, when y is large. */
6033 dconst0)),
6036 c2)));
6037 }
6039 /* sqrt(x) < c is the same as x < c*c, if we ignore NaNs. */
6044 /* sqrt(x) < c is the same as x >= 0 && x < c*c. */
6047 {
6052 dconst0)),
6055 c2)));
6056 }
6057 }
6058 }
6061 }
6063 /* Subroutine of fold() that optimizes comparisons against Infinities,
6064 either +Inf or -Inf.
6066 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6067 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6068 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6070 The function returns the constant folded tree if a simplification
6071 can be made, and NULL_TREE otherwise. */
6073 static tree
6075 {
6077 REAL_VALUE_TYPE max;
6078 tree temp;
6083 /* For negative infinity swap the sense of the comparison. */
6089 {
6091 /* x > +Inf is always false, if with ignore sNANs. */
6097 /* x <= +Inf is always true, if we don't case about NaNs. */
6101 /* x <= +Inf is the same as x == x, i.e. isfinite(x). */
6104 {
6107 }
6112 /* x == +Inf and x >= +Inf are always equal to x > DBL_MAX. */
6118 /* x < +Inf is always equal to x <= DBL_MAX. */
6124 /* x != +Inf is always equal to !(x > DBL_MAX). */
6136 }
6139 }
6141 /* Subroutine of fold() that optimizes comparisons of a division by
6142 a nonzero integer constant against an integer constant, i.e.
6143 X/C1 op C2.
6145 CODE is the comparison operator: EQ_EXPR, NE_EXPR, GT_EXPR, LT_EXPR,
6146 GE_EXPR or LE_EXPR. TYPE is the type of the result and ARG0 and ARG1
6147 are the operands of the comparison. ARG1 must be a TREE_REAL_CST.
6149 The function returns the constant folded tree if a simplification
6150 can be made, and NULL_TREE otherwise. */
6152 static tree
6154 {
6159 HOST_WIDE_INT hpart;
6164 /* We have to do this the hard way to detect unsigned overflow.
6165 prod = int_const_binop (MULT_EXPR, arg01, arg1, 0); */
6176 {
6181 /* Likewise hi = int_const_binop (PLUS_EXPR, prod, tmp, 0). */
6189 }
6191 {
6195 {
6214 }
6215 }
6216 else
6217 {
6218 /* A negative divisor reverses the relational operators. */
6224 {
6243 }
6244 }
6247 {
6268 {
6271 }
6276 {
6279 }
6284 {
6287 }
6292 {
6295 }
6300 }
6303 }
6306 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6307 equality/inequality test, then return a simplified form of the test
6308 using a sign testing. Otherwise return NULL. TYPE is the desired
6309 result type. */
6311 static tree
6313 tree result_type)
6314 {
6315 /* If this is testing a single bit, we can optimize the test. */
6319 {
6320 /* If we have (A & C) != 0 where C is the sign bit of A, convert
6321 this into A < 0. Similarly for (A & C) == 0 into A >= 0. */
6325 /* This is only a win if casting to a signed type is cheap,
6326 i.e. when arg00's type is not a partial mode. */
6329 {
6334 }
6335 }
6338 }
6340 /* If CODE with arguments ARG0 and ARG1 represents a single bit
6341 equality/inequality test, then return a simplified form of
6342 the test using shifts and logical operations. Otherwise return
6343 NULL. TYPE is the desired result type. */
6345 tree
6347 tree result_type)
6348 {
6349 /* If this is testing a single bit, we can optimize the test. */
6353 {
6362 /* First, see if we can fold the single bit test into a sign-bit
6363 test. */
6365 result_type);
6369 /* Otherwise we have (A & C) != 0 where C is a single bit,
6370 convert that into ((A >> C2) & 1). Where C2 = log2(C).
6371 Similarly for (A & C) == 0. */
6373 /* If INNER is a right shift of a constant and it plus BITNUM does
6374 not overflow, adjust BITNUM and INNER. */
6381 {
6384 }
6386 /* If we are going to be able to omit the AND below, we must do our
6387 operations as unsigned. If we must use the AND, we have a choice.
6388 Normally unsigned is faster, but for some machines signed is. */
6389 #ifdef LOAD_EXTEND_OP
6392 #else
6394 #endif
6410 /* Put the AND last so it can combine with more things. */
6413 /* Make sure to return the proper type. */
6417 }
6419 }
6421 /* Check whether we are allowed to reorder operands arg0 and arg1,
6422 such that the evaluation of arg1 occurs before arg0. */
6424 static bool
6426 {
6433 }
6435 /* Test whether it is preferable two swap two operands, ARG0 and
6436 ARG1, for example because ARG0 is an integer constant and ARG1
6437 isn't. If REORDER is true, only recommend swapping if we can
6438 evaluate the operands in reverse order. */
6440 bool
6442 {
6478 /* It is preferable to swap two SSA_NAME to ensure a canonical form
6479 for commutative and comparison operators. Ensuring a canonical
6480 form allows the optimizers to find additional redundancies without
6481 having to explicitly check for both orderings. */
6488 }
6490 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where
6491 ARG0 is extended to a wider type. */
6493 static tree
6495 {
6497 tree arg1_unw;
6506 #ifdef HAVE_canonicalize_funcptr_for_compare
6507 /* Disable this optimization if we're casting a function pointer
6508 type on targets that require function pointer canonicalization. */
6513 #endif
6520 /* If possible, express the comparison in the shorter mode. */
6536 /* If we are comparing with the integer that does not fit into the range
6537 of the shorter type, the result is known. */
6548 {
6575 }
6578 }
6580 /* Fold comparison ARG0 CODE ARG1 (with result in TYPE), where for
6581 ARG0 just the signedness is changed. */
6583 static tree
6586 {
6587 tree arg0_inner;
6598 #ifdef HAVE_canonicalize_funcptr_for_compare
6599 /* Disable this optimization if we're casting a function pointer
6600 type on targets that require function pointer canonicalization. */
6605 #endif
6625 else
6629 }
6631 /* Tries to replace &a[idx] CODE s * delta with &a[idx CODE delta], if s is
6632 step of the array. Reconstructs s and delta in the case of s * delta
6633 being an integer constant (and thus already folded).
6634 ADDR is the address. MULT is the multiplicative expression.
6635 If the function succeeds, the new address expression is returned. Otherwise
6636 NULL_TREE is returned. */
6638 static tree
6640 {
6644 tree itype;
6647 /* Canonicalize op1 into a possibly non-constant delta
6648 and an INTEGER_CST s. */
6650 {
6657 {
6660 }
6662 {
6665 }
6666 else
6668 }
6670 {
6673 }
6674 else
6675 {
6676 /* Simulate we are delta * 1. */
6679 }
6682 {
6684 {
6685 /* Remember if this was a multi-dimensional array. */
6698 {
6701 }
6702 else
6703 {
6704 /* Try if delta is a multiple of step. */
6709 }
6711 /* Only fold here if we can verify we do not overflow one
6712 dimension of a multi-dimensional array. */
6714 {
6715 tree tmp;
6731 }
6734 }
6735 else
6740 }
6742 /* We found the suitable array reference. So copy everything up to it,
6743 and replace the index. */
6750 {
6754 }
6762 }
6765 /* Fold A < X && A + 1 > Y to A < X && A >= Y. Normally A + 1 > Y
6766 means A >= Y && A != MAX, but in this case we know that
6767 A < X <= MAX. INEQ is A + 1 > Y, BOUND is A < X. */
6769 static tree
6771 {
6778 else
6787 {
6790 }
6792 {
6795 }
6796 else
6807 }
6809 /* Fold a sum or difference of at least one multiplication.
6810 Returns the folded tree or NULL if no simplification could be made. */
6812 static tree
6814 {
6818 /* (A * C) +- (B * C) -> (A+-B) * C.
6819 (A * C) +- A -> A * (C+-1).
6820 We are most concerned about the case where C is a constant,
6821 but other combinations show up during loop reduction. Since
6822 it is not difficult, try all four possibilities. */
6825 {
6828 }
6829 else
6830 {
6833 }
6835 {
6838 }
6839 else
6840 {
6843 }
6855 /* No identical multiplicands; see if we can find a common
6856 power-of-two factor in non-power-of-two multiplies. This
6857 can help in multi-dimensional array access. */
6860 {
6863 tree maybe_same;
6867 /* Move min of absolute values to int11. */
6870 {
6875 }
6876 else
6880 {
6888 }
6889 }
6899 }
6901 /* Subroutine of native_encode_expr. Encode the INTEGER_CST
6902 specified by EXPR into the buffer PTR of length LEN bytes.
6903 Return the number of bytes placed in the buffer, or zero
6904 upon failure. */
6906 static int
6908 {
6919 {
6923 else
6928 {
6935 else
6937 }
6938 else
6941 }
6943 }
6946 /* Subroutine of native_encode_expr. Encode the REAL_CST
6947 specified by EXPR into the buffer PTR of length LEN bytes.
6948 Return the number of bytes placed in the buffer, or zero
6949 upon failure. */
6951 static int
6953 {
6959 /* There are always 32 bits in each long, no matter the size of
6960 the hosts long. We handle floating point representations with
6961 up to 192 bits. */
6971 {
6976 {
6983 else
6985 }
6986 else
6989 }
6991 }
6993 /* Subroutine of native_encode_expr. Encode the COMPLEX_CST
6994 specified by EXPR into the buffer PTR of length LEN bytes.
6995 Return the number of bytes placed in the buffer, or zero
6996 upon failure. */
6998 static int
7000 {
7002 tree part;
7013 }
7016 /* Subroutine of native_encode_expr. Encode the VECTOR_CST
7017 specified by EXPR into the buffer PTR of length LEN bytes.
7018 Return the number of bytes placed in the buffer, or zero
7019 upon failure. */
7021 static int
7023 {
7033 {
7035 {
7038 }
7039 else
7043 {
7046 }
7047 else
7048 {
7052 }
7054 }
7056 }
7059 /* Subroutine of fold_view_convert_expr. Encode the INTEGER_CST,
7060 REAL_CST, COMPLEX_CST or VECTOR_CST specified by EXPR into the
7061 buffer PTR of length LEN bytes. Return the number of bytes
7062 placed in the buffer, or zero upon failure. */
7064 static int
7066 {
7068 {
7083 }
7084 }
7087 /* Subroutine of native_interpret_expr. Interpret the contents of
7088 the buffer PTR of length LEN as an INTEGER_CST of type TYPE.
7089 If the buffer cannot be interpreted, return NULL_TREE. */
7091 static tree
7093 {
7107 {
7110 {
7117 else
7119 }
7120 else
7126 else
7129 }
7132 }
7135 /* Subroutine of native_interpret_expr. Interpret the contents of
7136 the buffer PTR of length LEN as a REAL_CST of type TYPE.
7137 If the buffer cannot be interpreted, return NULL_TREE. */
7139 static tree
7141 {
7146 /* There are always 32 bits in each long, no matter the size of
7147 the hosts long. We handle floating point representations with
7148 up to 192 bits. */
7149 REAL_VALUE_TYPE r;
7159 {
7162 {
7169 else
7171 }
7172 else
7177 }
7181 }
7184 /* Subroutine of native_interpret_expr. Interpret the contents of
7185 the buffer PTR of length LEN as a COMPLEX_CST of type TYPE.
7186 If the buffer cannot be interpreted, return NULL_TREE. */
7188 static tree
7190 {
7205 }
7208 /* Subroutine of native_interpret_expr. Interpret the contents of
7209 the buffer PTR of length LEN as a VECTOR_CST of type TYPE.
7210 If the buffer cannot be interpreted, return NULL_TREE. */
7212 static tree
7214 {
7226 {
7231 }
7233 }
7236 /* Subroutine of fold_view_convert_expr. Interpret the contents of
7237 the buffer PTR of length LEN as a constant of type TYPE. For
7238 INTEGRAL_TYPE_P we return an INTEGER_CST, for SCALAR_FLOAT_TYPE_P
7239 we return a REAL_CST, etc... If the buffer cannot be interpreted,
7240 return NULL_TREE. */
7242 static tree
7244 {
7246 {
7263 }
7264 }
7267 /* Fold a VIEW_CONVERT_EXPR of a constant expression EXPR to type
7268 TYPE at compile-time. If we're unable to perform the conversion
7269 return NULL_TREE. */
7271 static tree
7273 {
7274 /* We support up to 512-bit values (for V8DFmode). */
7278 /* Check that the host and target are sane. */
7287 }
7290 /* Fold a unary expression of code CODE and type TYPE with operand
7291 OP0. Return the folded expression if folding is successful.
7292 Otherwise, return NULL_TREE. */
7294 tree
7296 {
7297 tree tem;
7298 tree arg0;
7306 {
7309 {
7310 /* Don't use STRIP_NOPS, because signedness of argument type
7311 matters. */
7313 }
7314 else
7315 {
7316 /* Strip any conversions that don't change the mode. This
7317 is safe for every expression, except for a comparison
7318 expression because its signedness is derived from its
7319 operands.
7321 Note that this is done as an internal manipulation within
7322 the constant folder, in order to find the simplest
7323 representation of the arguments so that their form can be
7324 studied. In any cases, the appropriate type conversions
7325 should be put back in the tree that will get out of the
7326 constant folder. */
7328 }
7329 }
7332 {
7337 {
7347 /* If this was a conversion, and all we did was to move into
7348 inside the COND_EXPR, bring it back out. But leave it if
7349 it is a conversion from integer to integer and the
7350 result precision is no wider than a word since such a
7351 conversion is cheap and may be optimized away by combine,
7352 while it couldn't if it were outside the COND_EXPR. Then return
7353 so we don't get into an infinite recursion loop taking the
7354 conversion out and then back in. */
7366 && (INTEGRAL_TYPE_P
7378 }
7380 {
7382 {
7386 }
7390 integer_one_node),
7392 integer_zero_node));
7393 }
7394 }
7397 {
7405 /* If we have (type) (a CMP b) and type is an integral type, return
7406 new expression involving the new type. */
7411 /* Handle cases of two conversions in a row. */
7414 {
7436 /* In addition to the cases of two conversions in a row
7437 handled below, if we are converting something to its own
7438 type via an object of identical or wider precision, neither
7439 conversion is needed. */
7446 /* Likewise, if the intermediate and final types are either both
7447 float or both integer, we don't need the middle conversion if
7448 it is wider than the final type and doesn't change the signedness
7449 (for integers). Avoid this if the final type is a pointer
7450 since then we sometimes need the inner conversion. Likewise if
7451 the outer has a precision not equal to the size of its mode. */
7460 && ! final_ptr
7464 /* If we have a sign-extension of a zero-extended value, we can
7465 replace that by a single zero-extension. */
7471 /* Two conversions in a row are not needed unless:
7472 - some conversion is floating-point (overstrict for now), or
7473 - some conversion is a vector (overstrict for now), or
7474 - the intermediate type is narrower than both initial and
7475 final, or
7476 - the intermediate type and innermost type differ in signedness,
7477 and the outermost type is wider than the intermediate, or
7478 - the initial type is a pointer type and the precisions of the
7479 intermediate and final types differ, or
7480 - the final type is a pointer type and the precisions of the
7481 initial and intermediate types differ.
7482 - the final type is a pointer type and the initial type not
7483 - the initial type is a pointer to an array and the final type
7484 not. */
7498 && ! (inside_ptr
7502 }
7504 /* Handle (T *)&A.B.C for A being of type T and B and C
7505 living at offset zero. This occurs frequently in
7506 C++ upcasting and then accessing the base. */
7510 {
7512 tree offset;
7518 /* If the reference was to a (constant) zero offset, we can use
7519 the address of the base if it has the same base type
7520 as the result type. */
7525 }
7530 /* Detect assigning a bitfield. */
7532 && DECL_BIT_FIELD
7534 {
7535 /* Don't leave an assignment inside a conversion
7536 unless assigning a bitfield. */
7538 /* First do the assignment, then return converted constant. */
7543 }
7545 /* Convert (T)(x & c) into (T)x & (T)c, if c is an integer
7546 constants (if x has signed type, the sign bit cannot be set
7547 in c). This folds extension into the BIT_AND_EXPR. */
7552 {
7562 <= HOST_BITS_PER_WIDE_INT
7564 {
7571 #ifdef LOAD_EXTEND_OP
7573 && !flag_syntax_only
7576 {
7580 }
7581 #endif
7582 }
7584 {
7590 }
7591 }
7593 /* Convert (T1)((T2)X op Y) into (T1)X op Y, for pointer types T1 and
7594 T2 being pointers to types of the same size. */
7599 {
7611 }
7613 /* Convert (T1)(~(T2)X) into ~(T1)X if T1 and T2 are integral types
7614 of the same precision, and X is a integer type not narrower than
7615 types T1 or T2, i.e. the cast (T2)X isn't an extension. */
7622 {
7627 }
7650 /* Convert fabs((double)float) into (double)fabsf(float). */
7653 {
7658 targ0));
7659 }
7660 /* ABS_EXPR<ABS_EXPR<x>> = ABS_EXPR<x> even if flag_wrapv is on. */
7664 /* Strip sign ops from argument. */
7666 {
7670 }
7677 {
7682 }
7684 {
7689 }
7699 /* Convert ~ (-A) to A - 1. */
7703 /* Convert ~ (A - 1) or ~ (A + -1) to -A. */
7710 /* Convert ~(X ^ Y) to ~X ^ Y or X ^ ~Y if ~X or ~Y simplify. */
7727 /* The argument to invert_truthvalue must have Boolean type. */
7731 /* Note that the operand of this must be an int
7732 and its values must be 0 or 1.
7733 ("true" is a fixed value perhaps depending on the language,
7734 but we don't handle values other than 1 correctly yet.) */
7749 {
7757 }
7759 {
7763 }
7765 {
7769 {
7779 }
7780 }
7792 {
7800 }
7802 {
7806 }
7808 {
7812 {
7822 }
7823 }
7829 }
7831 /* Fold a binary expression of code CODE and type TYPE with operands
7832 OP0 and OP1, containing either a MIN-MAX or a MAX-MIN combination.
7833 Return the folded expression if folding is successful. Otherwise,
7834 return NULL_TREE. */
7836 static tree
7838 {
7845 else
7848 /* MIN (MAX (a, b), b) == b. */
7853 /* MIN (MAX (b, a), b) == b. */
7859 /* MIN (a, MAX (a, b)) == a. */
7865 /* MIN (a, MAX (b, a)) == a. */
7872 }
7874 /* Helper that tries to canonicalize the comparison ARG0 CODE ARG1
7875 by changing CODE to reduce the magnitude of constants involved in
7876 ARG0 of the comparison.
7877 Returns a canonicalized comparison tree if a simplification was
7878 possible, otherwise returns NULL_TREE. */
7880 static tree
7883 {
7889 /* Match A +- CST code arg1 and CST code arg1. */
7896 /* Identify the constant in arg0 and its sign. */
7899 else
7903 /* Overflowed constants and zero will cause problems. */
7908 /* See if we can reduce the magnitude of the constant in
7909 arg0 by changing the comparison code. */
7911 {
7912 /* CST <= arg1 -> CST-1 < arg1. */
7915 /* -CST < arg1 -> -CST-1 <= arg1. */
7918 /* CST > arg1 -> CST-1 >= arg1. */
7921 /* -CST >= arg1 -> -CST-1 > arg1. */
7924 else
7926 /* arg1 code' CST' might be more canonical. */
7928 }
7929 else
7930 {
7931 /* A - CST < arg1 -> A - CST-1 <= arg1. */
7935 /* A + CST > arg1 -> A + CST-1 >= arg1. */
7939 /* A + CST <= arg1 -> A + CST-1 < arg1. */
7943 /* A - CST >= arg1 -> A - CST-1 > arg1. */
7947 else
7949 }
7951 /* Now build the constant reduced in magnitude. */
7957 /* If swapping might yield to a more canonical form, do so. */
7960 else
7962 }
7964 /* Canonicalize the comparison ARG0 CODE ARG1 with type TYPE with undefined
7965 overflow further. Try to decrease the magnitude of constants involved
7966 by changing LE_EXPR and GE_EXPR to LT_EXPR and GT_EXPR or vice versa
7967 and put sole constants at the second argument position.
7968 Returns the canonicalized tree if changed, otherwise NULL_TREE. */
7970 static tree
7973 {
7974 tree t;
7976 /* In principle pointers also have undefined overflow behavior,
7977 but that causes problems elsewhere. */
7982 /* Try canonicalization by simplifying arg0. */
7987 /* Try canonicalization by simplifying arg1 using the swapped
7988 comparison. */
7991 }
7993 /* Subroutine of fold_binary. This routine performs all of the
7994 transformations that are common to the equality/inequality
7995 operators (EQ_EXPR and NE_EXPR) and the ordering operators
7996 (LT_EXPR, LE_EXPR, GE_EXPR and GT_EXPR). Callers other than
7997 fold_binary should call fold_binary. Fold a comparison with
7998 tree code CODE and type TYPE with operands OP0 and OP1. Return
7999 the folded comparison or NULL_TREE. */
8001 static tree
8003 {
8016 /* If one arg is a real or integer constant, put it last. */
8020 /* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
8027 {
8031 tree lhs;
8041 }
8043 /* For comparisons of pointers we can decompose it to a compile time
8044 comparison of the base objects and the offsets into the object.
8045 This requires at least one operand being an ADDR_EXPR to do more
8046 than the operand_equal_p test below. */
8050 {
8057 /* Get base and offset for the access. Strip ADDR_EXPR for
8058 get_inner_reference, but put it back by stripping INDIRECT_REF
8059 off the base object if possible. */
8062 {
8068 else
8070 }
8074 {
8078 /* We have to make sure to have an indirect/non-indirect base1
8079 just the same as we did for base0. */
8085 }
8089 /* If we have equivalent bases we might be able to simplify. */
8092 {
8093 /* We can fold this expression to a constant if the non-constant
8094 offset parts are equal. */
8098 {
8100 {
8114 }
8115 }
8116 /* We can simplify the comparison to a comparison of the variable
8117 offset parts if the constant offset parts are equal.
8118 Be careful to use signed size type here because otherwise we
8119 mess with array offsets in the wrong way. This is possible
8120 because pointer arithmetic is restricted to retain within an
8121 object and overflow on pointer differences is undefined as of
8122 6.5.6/8 and /9 with respect to the signed ptrdiff_t. */
8124 {
8125 tree signed_size_type_node;
8128 /* By converting to signed size type we cover middle-end pointer
8129 arithmetic which operates on unsigned pointer types of size
8130 type size and ARRAY_REF offsets which are properly sign or
8131 zero extended from their type in case it is narrower than
8132 size type. */
8135 else
8139 else
8143 }
8144 }
8145 }
8147 /* If this is a comparison of two exprs that look like an ARRAY_REF of the
8148 same object, then we can fold this to a comparison of the two offsets in
8149 signed size type. This is possible because pointer arithmetic is
8150 restricted to retain within an object and overflow on pointer differences
8151 is undefined as of 6.5.6/8 and /9 with respect to the signed ptrdiff_t.
8153 We check flag_wrapv directly because pointers types are unsigned,
8154 and therefore TYPE_OVERFLOW_WRAPS returns true for them. That is
8155 normally what we want to avoid certain odd overflow cases, but
8156 not here. */
8158 && !flag_wrapv
8160 {
8166 {
8167 tree signed_size_type_node;
8170 /* By converting to signed size type we cover middle-end pointer
8171 arithmetic which operates on unsigned pointer types of size
8172 type size and ARRAY_REF offsets which are properly sign or
8173 zero extended from their type in case it is narrower than
8174 size type. */
8177 else
8181 else
8185 }
8186 }
8188 /* Transform comparisons of the form X +- C1 CMP Y +- C2 to
8189 X CMP Y +- C2 +- C1 for signed X, Y. This is valid if
8190 the resulting offset is smaller in absolute value than the
8191 original one. */
8199 {
8204 tree cst;
8206 /* Put the constant on the side where it doesn't overflow and is
8207 of lower absolute value than before. */
8214 variable1,
8226 variable2);
8227 }
8229 /* Transform comparisons of the form X * C1 CMP 0 to X CMP 0 in the
8230 signed arithmetic case. That form is created by the compiler
8231 often enough for folding it to be of value. One example is in
8232 computing loop trip counts after Operator Strength Reduction. */
8238 {
8246 /* If const1 is negative we swap the sense of the comparison. */
8251 }
8258 {
8266 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
8271 /* (-a) CMP (-b) -> b CMP a */
8278 {
8279 REAL_VALUE_TYPE cst;
8282 /* (-a) CMP CST -> a swap(CMP) (-CST) */
8289 /* IEEE doesn't distinguish +0 and -0 in comparisons. */
8290 /* a CMP (-0) -> a CMP 0 */
8295 /* x != NaN is always true, other ops are always false. */
8298 {
8301 }
8303 /* Fold comparisons against infinity. */
8305 {
8309 }
8310 }
8312 /* If this is a comparison of a real constant with a PLUS_EXPR
8313 or a MINUS_EXPR of a real constant, we can convert it into a
8314 comparison with a revised real constant as long as no overflow
8315 occurs when unsafe_math_optimizations are enabled. */
8327 /* Likewise, we can simplify a comparison of a real constant with
8328 a MINUS_EXPR whose first operand is also a real constant, i.e.
8329 (c1 - x) < c2 becomes x > c1-c2. */
8340 /* Fold comparisons against built-in math functions. */
8342 && flag_unsafe_math_optimizations
8344 {
8348 {
8352 }
8353 }
8354 }
8356 /* Convert foo++ == CONST into ++foo == CONST + INCR. */
8360 /* This optimization is invalid for ordered comparisons
8361 if CONST+INCR overflows or if foo+incr might overflow.
8362 This optimization is invalid for floating point due to rounding.
8363 For pointer types we assume overflow doesn't happen. */
8367 {
8371 {
8377 }
8378 else
8379 {
8385 }
8388 /* If VAROP is a reference to a bitfield, we must mask
8389 the constant by the width of the field. */
8394 {
8399 /* First check whether the comparison would come out
8400 always the same. If we don't do that we would
8401 change the meaning with the masking. */
8414 }
8417 }
8422 {
8423 /* If we are widening one operand of an integer comparison,
8424 see if the other operand is similarly being widened. Perhaps we
8425 can do the comparison in the narrower type. */
8430 /* Or if we are changing signedness. */
8434 }
8436 /* If this is comparing a constant with a MIN_EXPR or a MAX_EXPR of a
8437 constant, we can simplify it. */
8442 {
8446 }
8448 /* Simplify comparison of something with itself. (For IEEE
8449 floating-point, we can only do some of these simplifications.) */
8451 {
8453 {
8468 /* For NE, we can only do this simplification if integer
8469 or we don't honor IEEE floating point NaNs. */
8473 /* ... fall through ... */
8479 }
8480 }
8482 /* If we are comparing an expression that just has comparisons
8483 of two integer values, arithmetic expressions of those comparisons,
8484 and constants, we can simplify it. There are only three cases
8485 to check: the two values can either be equal, the first can be
8486 greater, or the second can be greater. Fold the expression for
8487 those three values. Since each value must be 0 or 1, we have
8488 eight possibilities, each of which corresponds to the constant 0
8489 or 1 or one of the six possible comparisons.
8491 This handles common cases like (a > b) == 0 but also handles
8492 expressions like ((x > y) - (y > x)) > 0, which supposedly
8493 occur in macroized code. */
8496 {
8501 /* Don't handle degenerate cases here; they should already
8502 have been handled anyway. */
8511 {
8515 /* We can't just pass T to eval_subst in case cval1 or cval2
8516 was the same as ARG1. */
8518 tree high_result
8522 arg1);
8523 tree equal_result
8527 arg1);
8528 tree low_result
8532 arg1);
8534 /* All three of these results should be 0 or 1. Confirm they are.
8535 Then use those values to select the proper code to use. */
8540 {
8541 /* Make a 3-bit mask with the high-order bit being the
8542 value for `>', the next for '=', and the low for '<'. */
8546 {
8548 /* Always false. */
8569 /* Always true. */
8571 }
8576 }
8577 }
8578 }
8580 /* Fold a comparison of the address of COMPONENT_REFs with the same
8581 type and component to a comparison of the address of the base
8582 object. In short, &x->a OP &y->a to x OP y and
8583 &x->a OP &y.a to x OP &y */
8588 {
8592 {
8598 }
8599 }
8601 /* We can fold X/C1 op C2 where C1 and C2 are integer constants
8602 into a single range test. */
8610 {
8614 }
8616 /* Fold ~X op ~Y as Y op X. */
8623 /* Fold ~X op C as X op' ~C, where op' is the swapped comparison. */
8631 }
8634 /* Subroutine of fold_binary. Optimize complex multiplications of the
8635 form z * conj(z), as pow(realpart(z),2) + pow(imagpart(z),2). The
8636 argument EXPR represents the expression "z" of type TYPE. */
8638 static tree
8640 {
8645 {
8648 }
8650 {
8653 }
8654 else
8655 {
8659 }
8668 }
8671 /* Fold a binary expression of code CODE and type TYPE with operands
8672 OP0 and OP1. Return the folded expression if folding is
8673 successful. Otherwise, return NULL_TREE. */
8675 tree
8677 {
8691 /* Strip any conversions that don't change the mode. This is
8692 safe for every expression, except for a comparison expression
8693 because its signedness is derived from its operands. So, in
8694 the latter case, only strip conversions that don't change the
8695 signedness.
8697 Note that this is done as an internal manipulation within the
8698 constant folder, in order to find the simplest representation
8699 of the arguments so that their form can be studied. In any
8700 cases, the appropriate type conversions should be put back in
8701 the tree that will get out of the constant folder. */
8704 {
8707 }
8708 else
8709 {
8712 }
8714 /* Note that TREE_CONSTANT isn't enough: static var addresses are
8715 constant but we can't do arithmetic on them. */
8720 {
8725 else
8729 {
8733 }
8734 }
8736 /* If this is a commutative operation, and ARG0 is a constant, move it
8737 to ARG1 to reduce the number of tests below. */
8742 /* ARG0 is the first operand of EXPR, and ARG1 is the second operand.
8744 First check for cases where an arithmetic operation is applied to a
8745 compound, conditional, or comparison operation. Push the arithmetic
8746 operation inside the compound or conditional to see if any folding
8747 can then be done. Convert comparison to conditional for this purpose.
8748 The also optimizes non-constant cases that used to be done in
8749 expand_expr.
8751 Before we do that, see if this is a BIT_AND_EXPR or a BIT_IOR_EXPR,
8752 one of the operands is a comparison and the other is a comparison, a
8753 BIT_AND_EXPR with the constant 1, or a truth value. In that case, the
8754 code below would make the expression more complex. Change it to a
8755 TRUTH_{AND,OR}_EXPR. Likewise, convert a similar NE_EXPR to
8756 TRUTH_XOR_EXPR and an EQ_EXPR to the inversion of a TRUTH_XOR_EXPR. */
8768 {
8772 boolean_type_node,
8780 }
8784 {
8796 {
8802 }
8805 {
8811 }
8812 }
8815 {
8817 /* A + (-B) -> A - B */
8822 /* (-A) + B -> B - A */
8828 /* Convert ~A + 1 to -A. */
8834 /* Handle (A1 * C1) + (A2 * C2) with A1, A2 or C1, C2 being the
8835 same or one. */
8839 {
8843 }
8846 {
8850 /* ~X + X is -1. */
8854 {
8857 }
8859 /* X + ~X is -1. */
8863 {
8866 }
8868 /* If we are adding two BIT_AND_EXPR's, both of which are and'ing
8869 with a constant, and the two constants have no bits in common,
8870 we should treat this as a BIT_IOR_EXPR since this may produce more
8871 simplifications. */
8879 {
8882 }
8884 /* Reassociate (plus (plus (mult) (foo)) (mult)) as
8885 (plus (plus (mult) (mult)) (foo)) so that we can
8886 take advantage of the factoring cases below. */
8893 {
8899 else
8921 parg1)));
8922 }
8924 /* Try replacing &a[i1] + c * i2 with &a[i1 + i2], if c is step
8925 of the array. Loop optimizer sometimes produce this type of
8926 expressions. */
8928 {
8932 }
8934 {
8938 }
8939 }
8940 else
8941 {
8942 /* See if ARG1 is zero and X + ARG1 reduces to X. */
8946 /* Likewise if the operands are reversed. */
8950 /* Convert X + -C into X - C. */
8953 {
8959 }
8961 /* Fold __complex__ ( x, 0 ) + __complex__ ( 0, y )
8962 to __complex__ ( x, y ). This is not the same for SNaNs or
8963 if signed zeros are involved. */
8967 {
8974 {
8978 {
8984 }
8986 {
8992 }
8993 }
8994 }
9002 /* Convert x+x into x*2.0. */
9008 /* Convert a + (b*c + d*e) into (a + b*c) + d*e. */
9012 {
9017 {
9018 tree tree0;
9021 }
9022 }
9023 /* Convert (b*c + d*e) + a into b*c + (d*e +a). */
9027 {
9032 {
9033 tree tree0;
9036 }
9037 }
9038 }
9040 bit_rotate:
9041 /* (A << C1) + (A >> C2) if A is unsigned and C1+C2 is the size of A
9042 is a rotate of A by C1 bits. */
9043 /* (A << B) + (A >> (Z - B)) if A is unsigned and Z is the size of A
9044 is a rotate of A by B bits. */
9045 {
9054 {
9073 {
9081 TYPE_PRECISION
9086 ? LROTATE_EXPR
9089 }
9091 {
9099 TYPE_PRECISION
9104 ? LROTATE_EXPR
9107 }
9108 }
9109 }
9111 associate:
9112 /* In most languages, can't associate operations on floats through
9113 parentheses. Rather than remember where the parentheses were, we
9114 don't associate floats at all, unless the user has specified
9115 -funsafe-math-optimizations. */
9118 {
9122 /* Split both trees into variables, constants, and literals. Then
9123 associate each group together, the constants with literals,
9124 then the result with variables. This increases the chances of
9125 literals being recombined later and of generating relocatable
9126 expressions for the sum of a constant and literal. */
9131 /* Only do something if we found more than two objects. Otherwise,
9132 nothing has changed and we risk infinite recursion. */
9137 {
9138 /* Recombine MINUS_EXPR operands by using PLUS_EXPR. */
9147 /* Preserve the MINUS_EXPR if the negative part of the literal is
9148 greater than the positive part. Otherwise, the multiplicative
9149 folding code (i.e extract_muldiv) may be fooled in case
9150 unsigned constants are subtracted, like in the following
9151 example: ((X*2 + 4) - 8U)/2. */
9153 {
9157 {
9161 }
9162 else
9163 {
9167 }
9168 }
9170 {
9175 else
9176 {
9182 }
9183 }
9188 }
9189 }
9194 /* A - (-B) -> A + B */
9197 /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
9205 /* Convert -A - 1 to ~A. */
9213 /* Convert -1 - A to ~A. */
9219 {
9225 /* Fold A - (A & B) into ~B & A. */
9228 {
9233 arg0);
9238 arg0);
9239 }
9241 /* Fold (A & ~B) - (A & B) into (A ^ B) - B, where B is
9242 any power of 2 minus 1. */
9247 {
9253 {
9257 }
9258 }
9259 }
9261 /* See if ARG1 is zero and X - ARG1 reduces to X. */
9265 /* (ARG0 - ARG1) is the same as (-ARG1 + ARG0). So check whether
9266 ARG0 is zero and X + ARG0 reduces to X, since that would mean
9267 (-ARG1 + ARG0) reduces to -ARG1. */
9271 /* Fold __complex__ ( x, 0 ) - __complex__ ( 0, y ) to
9272 __complex__ ( x, -y ). This is not the same for SNaNs or if
9273 signed zeros are involved. */
9277 {
9284 {
9288 {
9290 arg1r ? arg1r
9295 }
9297 {
9301 arg1i ? arg1i
9304 }
9305 }
9306 }
9308 /* Fold &x - &x. This can happen from &x.foo - &x.
9309 This is unsafe for certain floats even in non-IEEE formats.
9310 In IEEE, it is unsafe because it does wrong for NaNs.
9311 Also note that operand_equal_p is always false if an operand
9312 is volatile. */
9318 /* A - B -> A + (-B) if B is easily negatable. */
9321 /* Avoid this transformation if B is a positive REAL_CST. */
9329 /* Try folding difference of addresses. */
9330 {
9331 HOST_WIDE_INT diff;
9337 }
9339 /* Fold &a[i] - &a[j] to i-j. */
9344 {
9349 {
9357 }
9358 }
9360 /* Try replacing &a[i1] - c * i2 with &a[i1 - i2], if c is step
9361 of the array. Loop optimizer sometimes produce this type of
9362 expressions. */
9364 {
9368 }
9376 /* Handle (A1 * C1) - (A2 * C2) with A1, A2 or C1, C2 being the
9377 same or one. */
9381 {
9385 }
9390 /* (-A) * (-B) -> A * B */
9401 {
9406 /* Transform x * -1 into -x. */
9409 /* Transform x * -C into -x * C if x is easily negatable. */
9418 /* (a * (1 << b)) is (a << b) */
9434 /* Optimize z * conj(z) for integer complex numbers. */
9441 }
9442 else
9443 {
9444 /* Maybe fold x * 0 to 0. The expressions aren't the same
9445 when x is NaN, since x * 0 is also NaN. Nor are they the
9446 same in modes with signed zeros, since multiplying a
9447 negative value by 0 gives -0, not +0. */
9452 /* In IEEE floating point, x*1 is not equivalent to x for snans. */
9457 /* Transform x * -1.0 into -x. */
9462 /* Convert (C1/X)*C2 into (C1*C2)/X. */
9467 {
9473 }
9475 /* Strip sign operations from X in X*X, i.e. -Y*-Y -> Y*Y. */
9477 {
9480 {
9483 }
9484 }
9486 /* Fold z * +-I to __complex__ (-+__imag z, +-__real z).
9487 This is not the same for NaNs or if signed zeros are
9488 involved. */
9494 {
9506 }
9508 /* Optimize z * conj(z) for floating point complex numbers.
9509 Guarded by flag_unsafe_math_optimizations as non-finite
9510 imaginary components don't produce scalar results. */
9521 {
9525 /* Optimizations of root(...)*root(...). */
9527 {
9532 /* Optimize sqrt(x)*sqrt(x) as x. */
9538 /* Optimize root(x)*root(y) as root(x*y). */
9543 }
9545 /* Optimize expN(x)*expN(y) as expN(x+y). */
9547 {
9554 }
9556 /* Optimizations of pow(...)*pow(...). */
9560 {
9568 /* Optimize pow(x,y)*pow(z,y) as pow(x*z,y). */
9570 {
9575 arg01));
9577 }
9579 /* Optimize pow(x,y)*pow(x,z) as pow(x,y+z). */
9581 {
9586 arg));
9588 }
9589 }
9591 /* Optimize tan(x)*cos(x) as sin(x). */
9600 {
9606 }
9608 /* Optimize x*pow(x,c) as pow(x,c+1). */
9612 {
9619 {
9621 REAL_VALUE_TYPE c;
9630 }
9631 }
9633 /* Optimize pow(x,c)*x as pow(x,c+1). */
9637 {
9644 {
9646 REAL_VALUE_TYPE c;
9655 }
9656 }
9658 /* Optimize x*x as pow(x,2.0), which is expanded as x*x. */
9661 {
9665 {
9670 }
9671 }
9672 }
9673 }
9677 bit_ior:
9685 /* ~X | X is -1. */
9688 {
9691 }
9693 /* X | ~X is -1. */
9696 {
9699 }
9701 /* Canonicalize (X & C1) | C2. */
9705 {
9713 /* If (C1&C2) == C1, then (X&C1)|C2 becomes (X,C2). */
9718 {
9722 }
9723 else
9724 {
9728 }
9730 /* If (C1|C2) == ~0 then (X&C1)|C2 becomes X|C2. */
9735 /* Minimize the number of bits set in C1, i.e. C1 := C1 & ~C2. */
9745 arg1);
9746 }
9748 /* (X & Y) | Y is (X, Y). */
9752 /* (X & Y) | X is (Y, X). */
9757 /* X | (X & Y) is (Y, X). */
9762 /* X | (Y & X) is (Y, X). */
9772 /* Convert (or (not arg0) (not arg1)) to (not (and (arg0) (arg1))).
9774 This results in more efficient code for machines without a NAND
9775 instruction. Combine will canonicalize to the first form
9776 which will allow use of NAND instructions provided by the
9777 backend if they exist. */
9780 {
9785 }
9787 /* See if this can be simplified into a rotate first. If that
9788 is unsuccessful continue in the association code. */
9799 /* ~X ^ X is -1. */
9802 {
9805 }
9807 /* X ^ ~X is -1. */
9810 {
9813 }
9815 /* If we are XORing two BIT_AND_EXPR's, both of which are and'ing
9816 with a constant, and the two constants have no bits in common,
9817 we should treat this as a BIT_IOR_EXPR since this may produce more
9818 simplifications. */
9826 {
9829 }
9831 /* (X | Y) ^ X -> Y & ~ X*/
9834 {
9837 arg1);
9841 }
9843 /* (Y | X) ^ X -> Y & ~ X*/
9846 {
9849 arg1);
9853 }
9855 /* X ^ (X | Y) -> Y & ~ X*/
9858 {
9861 arg0);
9865 }
9867 /* X ^ (Y | X) -> Y & ~ X*/
9870 {
9873 arg0);
9877 }
9879 /* Convert ~X ^ ~Y to X ^ Y. */
9886 /* Convert ~X ^ C to X ^ ~C. */
9893 /* Fold (X & 1) ^ 1 as (X & 1) == 0. */
9900 /* Fold (X & Y) ^ Y as ~X & Y. */
9903 {
9908 }
9909 /* Fold (X & Y) ^ X as ~Y & X. */
9913 {
9918 }
9919 /* Fold X ^ (X & Y) as X & ~Y. */
9922 {
9927 }
9928 /* Fold X ^ (Y & X) as ~Y & X. */
9932 {
9937 }
9939 /* See if this can be simplified into a rotate first. If that
9940 is unsuccessful continue in the association code. */
9951 /* ~X & X is always zero. */
9956 /* X & ~X is always zero. */
9961 /* Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2). */
9971 /* (X | Y) & Y is (X, Y). */
9975 /* (X | Y) & X is (Y, X). */
9980 /* X & (X | Y) is (Y, X). */
9985 /* X & (Y | X) is (Y, X). */
9991 /* Fold (X ^ 1) & 1 as (X & 1) == 0. */
9995 {
10001 }
10002 /* Fold ~X & 1 as (X & 1) == 0. */
10005 {
10011 }
10013 /* Fold (X ^ Y) & Y as ~X & Y. */
10016 {
10021 }
10022 /* Fold (X ^ Y) & X as ~Y & X. */
10026 {
10031 }
10032 /* Fold X & (X ^ Y) as X & ~Y. */
10035 {
10040 }
10041 /* Fold X & (Y ^ X) as ~Y & X. */
10045 {
10050 }
10055 /* Simplify ((int)c & 0377) into (int)c, if c is unsigned char. */
10058 {
10059 unsigned int prec
10066 }
10068 /* Convert (and (not arg0) (not arg1)) to (not (or (arg0) (arg1))).
10070 This results in more efficient code for machines without a NOR
10071 instruction. Combine will canonicalize to the first form
10072 which will allow use of NOR instructions provided by the
10073 backend if they exist. */
10076 {
10081 }
10086 /* Don't touch a floating-point divide by zero unless the mode
10087 of the constant can represent infinity. */
10093 /* Optimize A / A to 1.0 if we don't care about
10094 NaNs or Infinities. Skip the transformation
10095 for non-real operands. */
10100 {
10104 }
10106 /* The complex version of the above A / A optimization. */
10109 {
10113 {
10115 /* omit_two_operands will call fold_convert for us. */
10117 }
10118 }
10120 /* (-A) / (-B) -> A / B */
10130 /* In IEEE floating point, x/1 is not equivalent to x for snans. */
10135 /* In IEEE floating point, x/-1 is not equivalent to -x for snans. */
10140 /* If ARG1 is a constant, we can convert this to a multiply by the
10141 reciprocal. This does not have the same rounding properties,
10142 so only do this if -funsafe-math-optimizations. We can actually
10143 always safely do it if ARG1 is a power of two, but it's hard to
10144 tell if it is or not in a portable manner. */
10146 {
10151 /* Find the reciprocal if optimizing and the result is exact. */
10153 {
10154 REAL_VALUE_TYPE r;
10157 {
10161 }
10162 }
10163 }
10164 /* Convert A/B/C to A/(B*C). */
10171 /* Convert A/(B/C) to (A/B)*C. */
10179 /* Convert C1/(X*C2) into (C1/C2)/X. */
10184 {
10190 }
10193 {
10197 /* Optimize sin(x)/cos(x) as tan(x). */
10203 {
10209 }
10211 /* Optimize cos(x)/sin(x) as 1.0/tan(x). */
10217 {
10221 {
10226 }
10227 }
10229 /* Optimize sin(x)/tan(x) as cos(x) if we don't care about
10230 NaNs or Infinities. */
10234 {
10241 {
10247 }
10248 }
10250 /* Optimize tan(x)/sin(x) as 1.0/cos(x) if we don't care about
10251 NaNs or Infinities. */
10255 {
10262 {
10266 {
10271 tmp);
10272 }
10273 }
10274 }
10276 /* Optimize pow(x,c)/x as pow(x,c-1). */
10280 {
10286 {
10288 REAL_VALUE_TYPE c;
10297 }
10298 }
10300 /* Optimize x/expN(y) into x*expN(-y). */
10302 {
10309 }
10311 /* Optimize x/pow(y,z) into x*pow(y,-z). */
10315 {
10324 }
10325 }
10330 /* Simplify A / (B << N) where A and B are positive and B is
10331 a power of 2, to A >> (N + log2(B)). */
10334 {
10337 {
10345 }
10346 }
10347 /* Fall thru */
10356 /* X / -1 is -X. */
10363 /* Convert -A / -B to A / B when the type is signed and overflow is
10364 undefined. */
10376 /* If arg0 is a multiple of arg1, then rewrite to the fastest div
10377 operation, EXACT_DIV_EXPR.
10379 Note that only CEIL_DIV_EXPR and FLOOR_DIV_EXPR are rewritten now.
10380 At one time others generated faster code, it's not clear if they do
10381 after the last round to changes to the DIV code in expmed.c. */
10396 /* X % 1 is always zero, but be sure to preserve any side
10397 effects in X. */
10401 /* X % 0, return X % 0 unchanged so that we can get the
10402 proper warnings and errors. */
10406 /* 0 % X is always zero, but be sure to preserve any side
10407 effects in X. Place this after checking for X == 0. */
10411 /* X % -1 is zero. */
10418 /* Optimize TRUNC_MOD_EXPR by a power of two into a BIT_AND_EXPR,
10419 i.e. "X % C" into "X & (C - 1)", if X and C are positive. */
10422 {
10424 /* Also optimize A % (C << N) where C is a power of 2,
10425 to A & ((C << N) - 1). */
10430 {
10436 }
10437 }
10439 /* X % -C is the same as X % C. */
10446 /* Avoid this transformation if C is INT_MIN, i.e. C == -C. */
10451 /* X % -Y is the same as X % Y. */
10472 /* Optimize -1 >> x for arithmetic right shifts. */
10475 /* ... fall through ... */
10478 shift:
10484 /* Since negative shift count is not well-defined,
10485 don't try to compute it in the compiler. */
10489 /* Turn (a OP c1) OP c2 into a OP (c1+c2). */
10494 {
10498 /* Deal with a OP (c1 + c2) being undefined but (a OP c1) OP c2
10499 being well defined. */
10501 {
10506 else
10508 }
10512 }
10514 /* Transform (x >> c) << c into x & (-1<<c), or transform (x << c) >> c
10515 into x & ((unsigned)-1 >> c) for unsigned types. */
10523 {
10526 tree lshift;
10527 tree arg00;
10530 {
10537 }
10538 }
10540 /* Rewrite an LROTATE_EXPR by a constant into an
10541 RROTATE_EXPR by a new constant. */
10543 {
10548 }
10550 /* If we have a rotate of a bit operation with the rotate count and
10551 the second operand of the bit operation both constant,
10552 permute the two operations. */
10564 /* Two consecutive rotates adding up to the width of the mode can
10565 be ignored. */
10602 /* Note that the operands of this must be ints
10603 and their values must be 0 or 1.
10604 ("true" is a fixed value perhaps depending on the language.) */
10605 /* If first arg is constant zero, return it. */
10609 /* If either arg is constant true, drop it. */
10613 /* Preserve sequence points. */
10616 /* If second arg is constant zero, result is zero, but first arg
10617 must be evaluated. */
10620 /* Likewise for first arg, but note that only the TRUTH_AND_EXPR
10621 case will be handled here. */
10625 /* !X && X is always false. */
10629 /* X && !X is always false. */
10634 /* A < X && A + 1 > Y ==> A < X && A >= Y. Normally A + 1 > Y
10635 means A >= Y && A != MAX, but in this case we know that
10636 A < X <= MAX. */
10640 {
10648 }
10650 truth_andor:
10651 /* We only do these simplifications if we are optimizing. */
10655 /* Check for things like (A || B) && (A || C). We can convert this
10656 to A || (B && C). Note that either operator can be any of the four
10657 truth and/or operations and the transformation will still be
10658 valid. Also note that we only care about order for the
10659 ANDIF and ORIF operators. If B contains side effects, this
10660 might change the truth-value of A. */
10667 {
10687 /* This case if tricky because we must either have commutative
10688 operators or else A10 must not have side-effects. */
10694 a01);
10695 }
10697 /* See if we can build a range comparison. */
10701 /* Check for the possibility of merging component references. If our
10702 lhs is another similar operation, try to merge its rhs with our
10703 rhs. Then try to merge our lhs and rhs. */
10715 /* Note that the operands of this must be ints
10716 and their values must be 0 or true.
10717 ("true" is a fixed value perhaps depending on the language.) */
10718 /* If first arg is constant true, return it. */
10722 /* If either arg is constant zero, drop it. */
10726 /* Preserve sequence points. */
10729 /* If second arg is constant true, result is true, but we must
10730 evaluate first arg. */
10733 /* Likewise for first arg, but note this only occurs here for
10734 TRUTH_OR_EXPR. */
10738 /* !X || X is always true. */
10742 /* X || !X is always true. */
10750 /* If the second arg is constant zero, drop it. */
10753 /* If the second arg is constant true, this is a logical inversion. */
10755 {
10756 /* Only call invert_truthvalue if operand is a truth value. */
10759 else
10762 }
10763 /* Identical arguments cancel to zero. */
10767 /* !X ^ X is always true. */
10772 /* X ^ !X is always true. */
10785 /* bool_var != 0 becomes bool_var. */
10790 /* bool_var == 1 becomes bool_var. */
10795 /* bool_var != 1 becomes !bool_var. */
10800 /* bool_var == 0 becomes !bool_var. */
10805 /* If this is an equality comparison of the address of a non-weak
10806 object against zero, then we know the result. */
10813 /* If this is an equality comparison of the address of two non-weak,
10814 unaliased symbols neither of which are extern (since we do not
10815 have access to attributes for externs), then we know the result. */
10828 {
10829 /* We know that we're looking at the address of two
10830 non-weak, unaliased, static _DECL nodes.
10832 It is both wasteful and incorrect to call operand_equal_p
10833 to compare the two ADDR_EXPR nodes. It is wasteful in that
10834 all we need to do is test pointer equality for the arguments
10835 to the two ADDR_EXPR nodes. It is incorrect to use
10836 operand_equal_p as that function is NOT equivalent to a
10837 C equality test. It can in fact return false for two
10838 objects which would test as equal using the C equality
10839 operator. */
10843 type);
10844 }
10846 /* If this is an EQ or NE comparison of a constant with a PLUS_EXPR or
10847 a MINUS_EXPR of a constant, we can convert it into a comparison with
10848 a revised constant as long as no overflow occurs. */
10860 /* Similarly for a NEGATE_EXPR. */
10868 /* Similarly for a BIT_XOR_EXPR; X ^ C1 == C2 is X == (C1 ^ C2). */
10877 /* If we have X - Y == 0, we can convert that to X == Y and similarly
10878 for !=. Don't do this for ordered comparisons due to overflow. */
10884 /* Convert ABS_EXPR<x> == 0 or ABS_EXPR<x> != 0 to x == 0 or x != 0. */
10889 /* If this is an EQ or NE comparison with zero and ARG0 is
10890 (1 << foo) & bar, convert it to (bar >> foo) & 1. Both require
10891 two operations, but the latter can be done in one less insn
10892 on machines that have only two-operand insns or on which a
10893 constant cannot be the first operand. */
10896 {
10901 return
10907 integer_one_node)),
10908 arg1);
10911 return
10917 integer_one_node)),
10918 arg1);
10919 }
10921 /* If this is an NE or EQ comparison of zero against the result of a
10922 signed MOD operation whose second operand is a power of 2, make
10923 the MOD operation unsigned since it is simpler and equivalent. */
10931 {
10941 }
10943 /* Fold ((X >> C1) & C2) == 0 and ((X >> C1) & C2) != 0 where
10944 C1 is a valid shift constant, and C2 is a power of two, i.e.
10945 a single bit. */
10949 == INTEGER_CST
10952 {
10957 /* Check for a valid shift count. */
10960 {
10964 /* If (C2 << C1) doesn't overflow, then ((X >> C1) & C2) != 0
10965 can be rewritten as (X & (C2 << C1)) != 0. */
10967 {
10971 }
10972 /* Otherwise, for signed (arithmetic) shifts,
10973 ((X >> C1) & C2) != 0 is rewritten as X < 0, and
10974 ((X >> C1) & C2) == 0 is rewritten as X >= 0. */
10978 /* Otherwise, of unsigned (logical) shifts,
10979 ((X >> C1) & C2) != 0 is rewritten as (X,false), and
10980 ((X >> C1) & C2) == 0 is rewritten as (X,true). */
10981 else
10985 arg000);
10986 }
10987 }
10989 /* If this is an NE comparison of zero with an AND of one, remove the
10990 comparison since the AND will give the correct value. */
10997 /* If we have (A & C) == C where C is a power of 2, convert this into
10998 (A & C) != 0. Similarly for NE_EXPR. */
11004 integer_zero_node));
11006 /* If we have (A & C) != 0 or (A & C) == 0 and C is the sign
11007 bit, then fold the expression into A < 0 or A >= 0. */
11012 /* If we have (A & C) == D where D & ~C != 0, convert this into 0.
11013 Similarly for NE_EXPR. */
11017 {
11026 }
11028 /* If we have (A | C) == D where C & ~D != 0, convert this into 0.
11029 Similarly for NE_EXPR. */
11033 {
11040 }
11042 /* If this is a comparison of a field, we may be able to simplify it. */
11045 /* Handle the constant case even without -O
11046 to make sure the warnings are given. */
11048 {
11052 }
11054 /* Optimize comparisons of strlen vs zero to a compare of the
11055 first character of the string vs zero. To wit,
11056 strlen(ptr) == 0 => *ptr == 0
11057 strlen(ptr) != 0 => *ptr != 0
11058 Other cases should reduce to one of these two (or a constant)
11059 due to the return value of strlen being unsigned. */
11062 {
11064 tree arglist;
11072 {
11076 }
11077 }
11079 /* Fold (X >> C) != 0 into X < 0 if C is one less than the width
11080 of X. Similarly fold (X >> C) == 0 into X >= 0. */
11084 {
11091 {
11093 {
11096 }
11099 }
11100 }
11102 /* (X ^ Y) == 0 becomes X == Y, and (X ^ Y) != 0 becomes X != Y. */
11108 /* (X ^ Y) == Y becomes X == 0. We know that Y has no side-effects. */
11113 /* Likewise (X ^ Y) == X becomes Y == 0. X has no side-effects. */
11120 /* (X ^ C1) op C2 can be rewritten as X op (C1 ^ C2). */
11128 /* Fold (~X & C) == 0 into (X & C) != 0 and (~X & C) != 0 into
11129 (X & C) == 0 when C is a single bit. */
11134 {
11140 }
11142 /* Fold ((X & C) ^ C) eq/ne 0 into (X & C) ne/eq 0, when the
11143 constant C is a power of two, i.e. a single bit. */
11150 {
11154 }
11156 /* Likewise, fold ((X ^ C) & C) eq/ne 0 into (X & C) ne/eq 0,
11157 when is C is a power of two, i.e. a single bit. */
11164 {
11170 }
11174 {
11177 }
11179 /* Fold -X op -Y as X op Y, where op is eq/ne. */
11186 /* Fold (X & C) op (Y & C) as (X ^ Y) & C op 0", and symmetries. */
11189 {
11201 arg01),
11209 arg01),
11217 arg00),
11225 arg00),
11227 }
11231 {
11238 /* Optimize (X ^ Z) op (Y ^ Z) as X op Y, and symmetries.
11239 operand_equal_p guarantees no side-effects so we don't need
11240 to use omit_one_operand on Z. */
11250 /* Optimize (X ^ C1) op (Y ^ C2) as (X ^ (C1 ^ C2)) op Y. */
11257 arg10);
11258 }
11269 /* Transform comparisons of the form X +- C CMP X. */
11276 {
11283 else
11286 /* (X - c) > X becomes false. */
11292 /* Likewise (X + c) < X becomes false. */
11298 /* Convert (X - c) <= X to true. */
11305 /* Convert (X + c) >= X to true. */
11313 {
11314 /* Convert X + c > X and X - c < X to true for integers. */
11325 /* Convert X + c <= X and X - c >= X to false for integers. */
11335 }
11336 }
11338 /* Change X >= C to X > (C - 1) and X < C to X <= (C - 1) if C > 0.
11339 This transformation affects the cases which are handled in later
11340 optimizations involving comparisons with non-negative constants. */
11344 {
11346 {
11351 }
11353 {
11358 }
11359 }
11361 /* Comparisons with the highest or lowest possible integer of
11362 the specified precision will have known values. */
11363 {
11371 {
11372 HOST_WIDE_INT signed_max_hi;
11377 {
11384 {
11388 }
11389 else
11390 {
11394 }
11395 }
11396 else
11397 {
11406 {
11409 }
11410 else
11411 {
11414 }
11415 }
11420 {
11433 /* The GE_EXPR and LT_EXPR cases above are not normally
11434 reached because of previous transformations. */
11438 }
11440 == max_hi
11443 {
11454 }
11456 == min_hi
11459 {
11474 }
11476 == min_hi
11479 {
11488 }
11493 /* We will flip the signedness of the comparison operator
11494 associated with the mode of arg1, so the sign bit is
11495 specified by this mode. Check that arg1 is the signed
11496 max associated with this sign bit. */
11498 /* signed_type does not work on pointer types. */
11500 {
11501 /* The following case also applies to X < signed_max+1
11502 and X >= signed_max+1 because previous transformations. */
11504 {
11511 }
11512 }
11513 }
11514 }
11516 /* If we are comparing an ABS_EXPR with a constant, we can
11517 convert all the cases into explicit comparisons, but they may
11518 well not be faster than doing the ABS and one comparison.
11519 But ABS (X) <= C is a range comparison, which becomes a subtraction
11520 and a comparison, and is probably faster. */
11534 /* Convert ABS_EXPR<x> >= 0 to true. */
11542 /* Convert ABS_EXPR<x> < 0 to false. */
11548 /* If X is unsigned, convert X < (1 << Y) into X >> Y == 0
11549 and similarly for >= into !=. */
11565 return
11584 {
11588 }
11590 /* If the first operand is NaN, the result is constant. */
11594 {
11596 ? integer_zero_node
11599 }
11601 /* If the second operand is NaN, the result is constant. */
11605 {
11607 ? integer_zero_node
11610 }
11612 /* Simplify unordered comparison of something with itself. */
11618 && !flag_trapping_math
11622 /* Fold (double)float1 CMP (double)float2 into float1 CMP float2. */
11623 {
11634 }
11639 /* When pedantic, a compound expression can be neither an lvalue
11640 nor an integer constant expression. */
11643 /* Don't let (0, 0) be null pointer constant. */
11657 /* An ASSERT_EXPR should never be passed to fold_binary. */
11663 }
11665 /* Callback for walk_tree, looking for LABEL_EXPR.
11666 Returns tree TP if it is LABEL_EXPR. Otherwise it returns NULL_TREE.
11667 Do not check the sub-tree of GOTO_EXPR. */
11669 static tree
11673 {
11675 {
11680 /* no break */
11683 }
11684 }
11686 /* Checks whether the sub-tree ST contains a label LABEL_EXPR which is
11687 accessible from outside the sub-tree. Returns NULL_TREE if no
11688 addressable label is found. */
11690 static bool
11692 {
11694 }
11696 /* Fold a ternary expression of code CODE and type TYPE with operands
11697 OP0, OP1, and OP2. Return the folded expression if folding is
11698 successful. Otherwise, return NULL_TREE. */
11700 tree
11702 {
11703 tree tem;
11710 /* Strip any conversions that don't change the mode. This is safe
11711 for every expression, except for a comparison expression because
11712 its signedness is derived from its operands. So, in the latter
11713 case, only strip conversions that don't change the signedness.
11715 Note that this is done as an internal manipulation within the
11716 constant folder, in order to find the simplest representation of
11717 the arguments so that their form can be studied. In any cases,
11718 the appropriate type conversions should be put back in the tree
11719 that will get out of the constant folder. */
11721 {
11724 }
11727 {
11730 }
11733 {
11737 {
11743 }
11747 /* Pedantic ANSI C says that a conditional expression is never an lvalue,
11748 so all simple results must be passed through pedantic_non_lvalue. */
11750 {
11753 /* Only optimize constant conditions when the selected branch
11754 has the same type as the COND_EXPR. This avoids optimizing
11755 away "c ? x : throw", where the throw has a void type.
11756 Avoid throwing away that operand which contains label. */
11763 }
11767 /* If we have A op B ? A : C, we may be able to convert this to a
11768 simpler expression, depending on the operation and the values
11769 of B and C. Signed zeros prevent all of these transformations,
11770 for reasons given above each one.
11772 Also try swapping the arguments and inverting the conditional. */
11777 {
11781 }
11785 op2,
11788 {
11791 {
11795 }
11796 }
11798 /* If the second operand is simpler than the third, swap them
11799 since that produces better jump optimization results. */
11802 {
11803 /* See if this can be inverted. If it can't, possibly because
11804 it was a floating-point inequality comparison, don't do
11805 anything. */
11809 }
11811 /* Convert A ? 1 : 0 to simply A. */
11814 /* If we try to convert OP0 to our type, the
11815 call to fold will try to move the conversion inside
11816 a COND, which will recurse. In that case, the COND_EXPR
11817 is probably the best choice, so leave it alone. */
11821 /* Convert A ? 0 : 1 to !A. This prefers the use of NOT_EXPR
11822 over COND_EXPR in cases such as floating point comparisons. */
11829 /* A < 0 ? <sign bit of A> : 0 is simply (A & <sign bit of A>). */
11834 {
11835 /* sign_bit_p only checks ARG1 bits within A's precision.
11836 If <sign bit of A> has wider type than A, bits outside
11837 of A's precision in <sign bit of A> need to be checked.
11838 If they are all 0, this optimization needs to be done
11839 in unsigned A's type, if they are all 1 in signed A's type,
11840 otherwise this can't be done. */
11845 {
11847 HOST_WIDE_INT mask_hi;
11849 tree tem_type;
11857 {
11861 }
11862 else
11863 {
11867 }
11869 {
11873 }
11874 else
11880 {
11883 }
11886 {
11889 }
11890 else
11892 }
11899 arg1)));
11900 }
11902 /* (A >> N) & 1 ? (1 << N) : 0 is simply A & (1 << N). A & 1 was
11903 already handled above. */
11908 {
11917 }
11919 /* A & N ? N : 0 is simply A & N if N is a power of two. This
11920 is probably obsolete because the first operand should be a
11921 truth value (that's why we have the two cases above), but let's
11922 leave it in until we can confirm this for all front-ends. */
11933 /* Convert A ? B : 0 into A && B if A and B are truth values. */
11939 arg1);
11941 /* Convert A ? B : 1 into !A || B if A and B are truth values. */
11945 {
11946 /* Only perform transformation if ARG0 is easily inverted. */
11951 arg1);
11952 }
11954 /* Convert A ? 0 : B into !A && B if A and B are truth values. */
11958 {
11959 /* Only perform transformation if ARG0 is easily inverted. */
11964 op2);
11965 }
11967 /* Convert A ? 1 : B into A || B if A and B are truth values. */
11973 op2);
11978 /* Check for a built-in function. */
11990 {
11999 {
12005 else
12007 }
12008 }
12014 }
12016 /* Perform constant folding and related simplification of EXPR.
12017 The related simplifications include x*1 => x, x*0 => 0, etc.,
12018 and application of the associative law.
12019 NOP_EXPR conversions may be removed freely (as long as we
12020 are careful not to change the type of the overall expression).
12021 We cannot simplify through a CONVERT_EXPR, FIX_EXPR or FLOAT_EXPR,
12022 but we can constant-fold them if they have constant operands. */
12024 #ifdef ENABLE_FOLD_CHECKING
12025 # define fold(x) fold_1 (x)
12027 static
12028 #endif
12029 tree
12031 {
12035 tree tem;
12037 /* Return right away if a constant. */
12043 {
12048 {
12066 }
12067 }
12070 {
12077 }
12079 #ifdef ENABLE_FOLD_CHECKING
12080 #undef fold
12086 /* When --enable-checking=fold, compute a digest of expr before
12087 and after actual fold call to see if fold did not accidentally
12088 change original expr. */
12090 tree
12092 {
12093 tree ret;
12096 htab_t ht;
12115 }
12117 void
12119 {
12122 htab_t ht;
12132 }
12134 static void
12136 {
12138 }
12140 static void
12142 {
12148 recursive_label:
12162 {
12163 /* Allow DECL_ASSEMBLER_NAME to be modified. */
12167 }
12172 {
12173 /* Allow these fields to be modified. */
12180 {
12183 }
12184 }
12192 {
12195 {
12209 }
12213 {
12226 }
12242 {
12248 }
12253 {
12257 }
12268 {
12271 }
12281 }
12282 }
12284 #endif
12286 /* Fold a unary tree expression with code CODE of type TYPE with an
12287 operand OP0. Return a folded expression if successful. Otherwise,
12288 return a tree expression with code CODE of type TYPE with an
12289 operand OP0. */
12291 tree
12293 {
12294 tree tem;
12295 #ifdef ENABLE_FOLD_CHECKING
12298 htab_t ht;
12305 #endif
12311 #ifdef ENABLE_FOLD_CHECKING
12319 #endif
12321 }
12323 /* Fold a binary tree expression with code CODE of type TYPE with
12324 operands OP0 and OP1. Return a folded expression if successful.
12325 Otherwise, return a tree expression with code CODE of type TYPE
12326 with operands OP0 and OP1. */
12328 tree
12330 MEM_STAT_DECL)
12331 {
12332 tree tem;
12333 #ifdef ENABLE_FOLD_CHECKING
12339 htab_t ht;
12351 #endif
12357 #ifdef ENABLE_FOLD_CHECKING
12373 #endif
12375 }
12377 /* Fold a ternary tree expression with code CODE of type TYPE with
12378 operands OP0, OP1, and OP2. Return a folded expression if
12379 successful. Otherwise, return a tree expression with code CODE of
12380 type TYPE with operands OP0, OP1, and OP2. */
12382 tree
12384 MEM_STAT_DECL)
12385 {
12386 tree tem;
12387 #ifdef ENABLE_FOLD_CHECKING
12395 htab_t ht;
12412 #endif
12418 #ifdef ENABLE_FOLD_CHECKING
12442 #endif
12444 }
12446 /* Perform constant folding and related simplification of initializer
12447 expression EXPR. These behave identically to "fold_buildN" but ignore
12448 potential run-time traps and exceptions that fold must preserve. */
12450 #define START_FOLD_INIT \
12451 int saved_signaling_nans = flag_signaling_nans;\
12452 int saved_trapping_math = flag_trapping_math;\
12453 int saved_rounding_math = flag_rounding_math;\
12454 int saved_trapv = flag_trapv;\
12455 int saved_folding_initializer = folding_initializer;\
12456 flag_signaling_nans = 0;\
12457 flag_trapping_math = 0;\
12458 flag_rounding_math = 0;\
12459 flag_trapv = 0;\
12460 folding_initializer = 1;
12462 #define END_FOLD_INIT \
12463 flag_signaling_nans = saved_signaling_nans;\
12464 flag_trapping_math = saved_trapping_math;\
12465 flag_rounding_math = saved_rounding_math;\
12466 flag_trapv = saved_trapv;\
12467 folding_initializer = saved_folding_initializer;
12469 tree
12471 {
12472 tree result;
12473 START_FOLD_INIT;
12477 END_FOLD_INIT;
12479 }
12481 tree
12483 {
12484 tree result;
12485 START_FOLD_INIT;
12489 END_FOLD_INIT;
12491 }
12493 tree
12495 tree op2)
12496 {
12497 tree result;
12498 START_FOLD_INIT;
12502 END_FOLD_INIT;
12504 }
12506 #undef START_FOLD_INIT
12507 #undef END_FOLD_INIT
12509 /* Determine if first argument is a multiple of second argument. Return 0 if
12510 it is not, or we cannot easily determined it to be.
12512 An example of the sort of thing we care about (at this point; this routine
12513 could surely be made more general, and expanded to do what the *_DIV_EXPR's
12514 fold cases do now) is discovering that
12516 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12518 is a multiple of
12520 SAVE_EXPR (J * 8)
12522 when we know that the two SAVE_EXPR (J * 8) nodes are the same node.
12524 This code also handles discovering that
12526 SAVE_EXPR (I) * SAVE_EXPR (J * 8)
12528 is a multiple of 8 so we don't have to worry about dealing with a
12529 possible remainder.
12531 Note that we *look* inside a SAVE_EXPR only to determine how it was
12532 calculated; it is not safe for fold to do much of anything else with the
12533 internals of a SAVE_EXPR, since it cannot know when it will be evaluated
12534 at run time. For example, the latter example above *cannot* be implemented
12535 as SAVE_EXPR (I) * J or any variant thereof, since the value of J at
12536 evaluation time of the original SAVE_EXPR is not necessarily the same at
12537 the time the new expression is evaluated. The only optimization of this
12538 sort that would be valid is changing
12540 SAVE_EXPR (I) * SAVE_EXPR (SAVE_EXPR (J) * 8)
12542 divided by 8 to
12544 SAVE_EXPR (I) * SAVE_EXPR (J)
12546 (where the same SAVE_EXPR (J) is used in the original and the
12547 transformed version). */
12549 static int
12551 {
12559 {
12561 /* Bitwise and provides a power of two multiple. If the mask is
12562 a multiple of BOTTOM then TOP is a multiple of BOTTOM. */
12565 /* FALLTHRU */
12578 {
12582 /* const_binop may not detect overflow correctly,
12583 so check for it explicitly here. */
12589 size_one_node,
12593 }
12597 /* Can't handle conversions from non-integral or wider integral type. */
12603 /* .. fall through ... */
12619 }
12620 }
12622 /* Return true if `t' is known to be non-negative. */
12624 bool
12626 {
12634 {
12636 /* Query VRP to see if it has recorded any information about
12637 the range of this object. */
12641 /* We can't return 1 if flag_wrapv is set because
12642 ABS_EXPR<INT_MIN> = INT_MIN. */
12660 /* zero_extend(x) + zero_extend(y) is non-negative if x and y are
12661 both unsigned and at least 2 bits shorter than the result. */
12665 {
12670 {
12674 }
12675 }
12680 {
12681 /* x * x for floating point x is always non-negative. */
12686 }
12688 /* zero_extend(x) * zero_extend(y) is non-negative if x and y are
12689 both unsigned and their total bits is shorter than the result. */
12693 {
12700 }
12741 {
12746 {
12750 {
12754 }
12755 }
12757 {
12763 }
12764 }
12768 {
12772 /* If the initializer is non-void, then it's a normal expression
12773 that will be assigned to the slot. */
12777 /* Otherwise, the initializer sets the slot in some way. One common
12778 way is an assignment statement at the end of the initializer. */
12780 {
12788 else
12790 }
12797 }
12800 {
12805 {
12823 /* Always true. */
12827 /* sqrt(-0.0) is -0.0. */
12859 /* True if the 1st argument is nonnegative. */
12863 /* True if the 1st OR 2nd arguments are nonnegative. */
12868 /* True if the 1st AND 2nd arguments are nonnegative. */
12873 /* True if the 2nd argument is nonnegative. */
12877 /* True if the 1st argument is nonnegative or the second
12878 argument is an even integer. */
12880 {
12884 }
12888 /* True if the 1st argument is nonnegative or the second
12889 argument is an even integer valued real. */
12891 {
12892 REAL_VALUE_TYPE c;
12893 HOST_WIDE_INT n;
12898 {
12899 REAL_VALUE_TYPE cint;
12904 }
12905 }
12910 }
12911 }
12913 /* ... fall through ... */
12917 /* Truth values evaluate to 0 or 1, which is nonnegative. */
12919 }
12921 /* We don't know sign of `t', so be conservative and return false. */
12923 }
12925 /* Return true when T is an address and is known to be nonzero.
12926 For floating point we further ensure that T is not denormal.
12927 Similar logic is present in nonzero_address in rtlanal.h. */
12929 bool
12931 {
12934 /* Doing something useful for floating point would need more work. */
12939 {
12941 /* Query VRP to see if it has recorded any information about
12942 the range of this object. */
12953 {
12954 /* With the presence of negative values it is hard
12955 to say something. */
12959 /* One of operands must be positive and the other non-negative. */
12962 }
12967 {
12970 }
12974 {
12980 }
12984 {
12990 /* Weak declarations may link to NULL. */
12994 /* Constants are never weak. */
12999 }
13011 {
13012 /* When both operands are nonzero, then MAX must be too. */
13016 /* MAX where operand 0 is positive is positive. */
13018 }
13019 /* MAX where operand 1 is positive is positive. */
13044 }
13046 }
13048 /* Given the components of a binary expression CODE, TYPE, OP0 and OP1,
13049 attempt to fold the expression to a constant without modifying TYPE,
13050 OP0 or OP1.
13052 If the expression could be simplified to a constant, then return
13053 the constant. If the expression would not be simplified to a
13054 constant, then return NULL_TREE. */
13056 tree
13058 {
13061 }
13063 /* Given the components of a unary expression CODE, TYPE and OP0,
13064 attempt to fold the expression to a constant without modifying
13065 TYPE or OP0.
13067 If the expression could be simplified to a constant, then return
13068 the constant. If the expression would not be simplified to a
13069 constant, then return NULL_TREE. */
13071 tree
13073 {
13076 }
13078 /* If EXP represents referencing an element in a constant string
13079 (either via pointer arithmetic or array indexing), return the
13080 tree representing the value accessed, otherwise return NULL. */
13082 tree
13084 {
13088 {
13090 tree index;
13091 tree string;
13095 else
13096 {
13100 /* Optimize the special-case of a zero lower bound.
13102 We convert the low_bound to sizetype to avoid some problems
13103 with constant folding. (E.g. suppose the lower bound is 1,
13104 and its mode is QI. Without the conversion,l (ARRAY
13105 +(INDEX-(unsigned char)1)) becomes ((ARRAY+(-(unsigned char)1))
13106 +INDEX), which becomes (ARRAY+255+INDEX). Opps!) */
13111 }
13125 }
13127 }
13129 /* Return the tree for neg (ARG0) when ARG0 is known to be either
13130 an integer constant or real constant.
13132 TYPE is the type of the result. */
13134 static tree
13136 {
13140 {
13142 {
13144 HOST_WIDE_INT high;
13152 }
13160 }
13163 }
13165 /* Return the tree for abs (ARG0) when ARG0 is known to be either
13166 an integer constant or real constant.
13168 TYPE is the type of the result. */
13170 tree
13172 {
13176 {
13178 /* If the value is unsigned, then the absolute value is
13179 the same as the ordinary value. */
13182 /* Similarly, if the value is non-negative. */
13185 /* If the value is negative, then the absolute value is
13186 its negation. */
13187 else
13188 {
13190 HOST_WIDE_INT high;
13196 }
13202 else
13208 }
13211 }
13213 /* Return the tree for not (ARG0) when ARG0 is known to be an integer
13214 constant. TYPE is the type of the result. */
13216 static tree
13218 {
13228 }
13230 /* Given CODE, a relational operator, the target type, TYPE and two
13231 constant operands OP0 and OP1, return the result of the
13232 relational operation. If the result is not a compile time
13233 constant, then return NULL_TREE. */
13235 static tree
13237 {
13240 /* From here on, the only cases we handle are when the result is
13241 known to be a constant. */
13244 {
13248 /* Handle the cases where either operand is a NaN. */
13250 {
13252 {
13280 }
13283 }
13286 }
13288 /* From here on we only handle LT, LE, GT, GE, EQ and NE.
13290 To compute GT, swap the arguments and do LT.
13291 To compute GE, do LT and invert the result.
13292 To compute LE, swap the arguments, do LT and invert the result.
13293 To compute NE, do EQ and invert the result.
13295 Therefore, the code below must handle only EQ and LT. */
13298 {
13303 }
13305 /* Note that it is safe to invert for real values here because we
13306 have already handled the one case that it matters. */
13310 {
13313 }
13315 /* Compute a result for LT or EQ if args permit;
13316 Otherwise return T. */
13318 {
13323 else
13325 }
13326 else
13332 }
13334 /* Build an expression for the a clean point containing EXPR with type TYPE.
13335 Don't build a cleanup point expression for EXPR which don't have side
13336 effects. */
13338 tree
13340 {
13341 /* If the expression does not have side effects then we don't have to wrap
13342 it with a cleanup point expression. */
13346 /* If the expression is a return, check to see if the expression inside the
13347 return has no side effects or the right hand side of the modify expression
13348 inside the return. If either don't have side effects set we don't need to
13349 wrap the expression in a cleanup point expression. Note we don't check the
13350 left hand side of the modify because it should always be a return decl. */
13352 {
13359 }
13362 }
13364 /* Build an expression for the address of T. Folds away INDIRECT_REF to
13365 avoid confusing the gimplify process. */
13367 tree
13369 {
13370 /* The size of the object is not relevant when talking about its address. */
13374 /* Note: doesn't apply to ALIGN_INDIRECT_REF */
13377 {
13381 }
13382 else
13383 {
13392 }
13395 }
13397 tree
13399 {
13401 }
13403 /* Given a pointer value OP0 and a type TYPE, return a simplified version
13404 of an indirection through OP0, or NULL_TREE if no simplification is
13405 possible. */
13407 tree
13409 {
13411 tree subtype;
13419 {
13422 /* *&CONST_DECL -> to the value of the const decl. */
13425 /* *&p => p; make sure to handle *&"str"[cst] here. */
13427 {
13431 else
13433 }
13434 /* *(foo *)&fooarray => fooarray[0] */
13437 {
13443 }
13444 /* *(foo *)&complexfoo => __real__ complexfoo */
13448 /* *(foo *)&vectorfoo => BIT_FIELD_REF<vectorfoo,...> */
13451 {
13455 }
13456 }
13458 /* ((foo*)&complexfoo)[1] => __imag__ complexfoo */
13461 {
13464 tree op00type;
13471 {
13475 }
13476 }
13478 /* *(foo *)fooarrptr => (*fooarrptr)[0] */
13481 {
13482 tree type_domain;
13489 }
13492 }
13494 /* Builds an expression for an indirection through T, simplifying some
13495 cases. */
13497 tree
13499 {
13505 else
13507 }
13509 /* Given an INDIRECT_REF T, return either T or a simplified version. */
13511 tree
13513 {
13518 else
13520 }
13522 /* Strip non-trapping, non-side-effecting tree nodes from an expression
13523 whose result is ignored. The type of the returned tree need not be
13524 the same as the original expression. */
13526 tree
13528 {
13534 {
13545 else
13551 {
13567 }
13572 }
13573 }
13575 /* Return the value of VALUE, rounded up to a multiple of DIVISOR.
13576 This can only be applied to objects of a sizetype. */
13578 tree
13580 {
13587 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
13588 have to do anything. Only do this when we are not given a const,
13589 because in that case, this check is more expensive than just
13590 doing it. */
13592 {
13597 }
13599 /* If divisor is a power of two, simplify this to bit manipulation. */
13601 {
13603 {
13616 {
13617 high++;
13620 }
13624 }
13625 else
13626 {
13627 tree t;
13633 }
13634 }
13635 else
13636 {
13641 }
13644 }
13646 /* Likewise, but round down. */
13648 tree
13650 {
13657 /* See if VALUE is already a multiple of DIVISOR. If so, we don't
13658 have to do anything. Only do this when we are not given a const,
13659 because in that case, this check is more expensive than just
13660 doing it. */
13662 {
13667 }
13669 /* If divisor is a power of two, simplify this to bit manipulation. */
13671 {
13672 tree t;
13676 }
13677 else
13678 {
13683 }
13686 }
13688 /* Returns the pointer to the base of the object addressed by EXP and
13689 extracts the information about the offset of the access, storing it
13690 to PBITPOS and POFFSET. */
13692 static tree
13695 {
13696 tree core;
13699 HOST_WIDE_INT bitsize;
13702 {
13707 }
13708 else
13709 {
13713 }
13716 }
13718 /* Returns true if addresses of E1 and E2 differ by a constant, false
13719 otherwise. If they do, E1 - E2 is stored in *DIFF. */
13721 bool
13723 {
13737 {
13747 }
13749 {
13750 /* If only one of the offsets is non-constant, the difference cannot
13751 be a constant. */
13753 }
13754 else
13759 }
13761 /* Simplify the floating point expression EXP when the sign of the
13762 result is not significant. Return NULL_TREE if no simplification
13763 is possible. */
13765 tree
13767 {
13771 {
13806 {
13809 {
13811 /* Strip copysign function call, return the 1st argument. */
13817 /* Strip sign ops from the argument of "odd" math functions. */
13819 {
13824 arg0));
13825 }
13827 }
13828 }
13833 }
13835 }