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| author | Roger Sayle <roger@eyesopen.com> | 2006-12-31 16:17:49 +0000 |
|---|---|---|
| committer | Roger Sayle <sayle@gcc.gnu.org> | 2006-12-31 16:17:49 +0000 |
| commit | 870aa1ebe0d3e05912f763ece1ed4491282d34e2 (patch) | |
| tree | b1cf895f653525f285670f935e58e7beff2a7eef /gcc | |
| parent | 7c2da05e604c27549afadf4df26c679aead5f414 (diff) | |
| download | gcc-870aa1ebe0d3e05912f763ece1ed4491282d34e2.zip gcc-870aa1ebe0d3e05912f763ece1ed4491282d34e2.tar.gz gcc-870aa1ebe0d3e05912f763ece1ed4491282d34e2.tar.bz2 | |
re PR middle-end/30322 (((-i-1) + i) +1) is turned into ~i + (i+1) and never into 0 on the tree level)
PR middle-end/30322
* fold-const.c (fold_binary): Fold X + ~X and ~X + X into -1 when
we don't care about trapping overflow. Only convert -A - 1 into ~A
when we don't care about trapping overflow.
* gcc.dg/fold-plusnot-1.c: New test case.
From-SVN: r120300
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 7 | ||||
| -rw-r--r-- | gcc/fold-const.c | 23 | ||||
| -rw-r--r-- | gcc/testsuite/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/fold-plusnot-1.c | 30 |
4 files changed, 64 insertions, 1 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 1e2601b..be1f4fb 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2006-12-31 Roger Sayle <roger@eyesopen.com> + + PR middle-end/30322 + * fold-const.c (fold_binary): Fold X + ~X and ~X + X into -1 when + we don't care about trapping overflow. Only convert -A - 1 into ~A + when we don't care about trapping overflow. + 2006-12-31 Richard Guenther <rguenther@suse.de> PR middle-end/30338 diff --git a/gcc/fold-const.c b/gcc/fold-const.c index dbdc9c2..da9579e 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -8662,6 +8662,26 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) if (integer_zerop (arg1)) return non_lvalue (fold_convert (type, arg0)); + /* ~X + X is -1. */ + if (TREE_CODE (arg0) == BIT_NOT_EXPR + && operand_equal_p (TREE_OPERAND (arg0, 0), arg1, 0) + && !TYPE_TRAP_SIGNED (type)) + { + t1 = build_int_cst (type, -1); + t1 = force_fit_type (t1, 0, false, false); + return omit_one_operand (type, t1, arg1); + } + + /* X + ~X is -1. */ + if (TREE_CODE (arg1) == BIT_NOT_EXPR + && operand_equal_p (arg0, TREE_OPERAND (arg1, 0), 0) + && !TYPE_TRAP_SIGNED (type)) + { + t1 = build_int_cst (type, -1); + t1 = force_fit_type (t1, 0, false, false); + return omit_one_operand (type, t1, arg0); + } + /* If we are adding two BIT_AND_EXPR's, both of which are and'ing with a constant, and the two constants have no bits in common, we should treat this as a BIT_IOR_EXPR since this may produce more @@ -9002,7 +9022,8 @@ fold_binary (enum tree_code code, tree type, tree op0, tree op1) /* Convert -A - 1 to ~A. */ if (INTEGRAL_TYPE_P (type) && TREE_CODE (arg0) == NEGATE_EXPR - && integer_onep (arg1)) + && integer_onep (arg1) + && !TYPE_TRAP_SIGNED (type)) return fold_build1 (BIT_NOT_EXPR, type, fold_convert (type, TREE_OPERAND (arg0, 0))); diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index df63017..30d25ea 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,3 +1,8 @@ +2006-12-31 Roger Sayle <roger@eyesopen.com> + + PR middle-end/30322 + * gcc.dg/fold-plusnot-1.c: New test case. + 2006-12-31 Simon Martin <simartin@users.sourceforge.net> PR c++/29731 diff --git a/gcc/testsuite/gcc.dg/fold-plusnot-1.c b/gcc/testsuite/gcc.dg/fold-plusnot-1.c new file mode 100644 index 0000000..81ddf46 --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-plusnot-1.c @@ -0,0 +1,30 @@ +/* PR middle-end/30322 */ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-original" } */ + +int test1(int a) +{ + return a + ~a; +} + +int test2(int b) +{ + return ~b + b; +} + +unsigned int test3(unsigned int c) +{ + return c + ~c; +} + +unsigned int test4(unsigned int d) +{ + return ~d + d; +} + +/* { dg-final { scan-tree-dump-times "\\+ a" 0 "original" } } */ +/* { dg-final { scan-tree-dump-times "\\+ b" 0 "original" } } */ +/* { dg-final { scan-tree-dump-times "\\+ c" 0 "original" } } */ +/* { dg-final { scan-tree-dump-times "\\+ d" 0 "original" } } */ +/* { dg-final { cleanup-tree-dump "original" } } */ + |