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| author | Roger Sayle <roger@eyesopen.com> | 2003-05-31 13:23:32 +0000 |
|---|---|---|
| committer | Roger Sayle <sayle@gcc.gnu.org> | 2003-05-31 13:23:32 +0000 |
| commit | 4fa26a60791ec314128a9683fd4d657b251d0268 (patch) | |
| tree | ae8dcbb261aaadbfa874d60f1fccd8dd93248b50 /gcc/fold-const.c | |
| parent | 82a2669ea738ba4bec4112408a16082e7356e7e1 (diff) | |
| download | gcc-4fa26a60791ec314128a9683fd4d657b251d0268.tar.gz | |
flags.h (flag_wrapv): New flag controlling overflow semantics.
* flags.h (flag_wrapv): New flag controlling overflow semantics.
* toplev.c (flag_wrapv): Declare the variable with default false.
(lang_independent_options): New option "-fwrapv" to set the above.
* fold-const.c (extract_muldiv_1): Disable optimization of (2*x)/2
as x, when signed arithmetic overflow wraps around.
(fold): Optimize "-A - B" as "-B - A" if overflow wraps around.
* loop.c (basic_induction_var): Ignore BIVs that rely on undefined
overflow when flag_wrapv is true.
* java/lang.c (java_init_options): Prescribe wrap-around two's
complement arithmetic overflow by setting flag_wrapv.
* doc/invoke.texi: Document new -fwrapv command line option.
* doc/c-tree.texi: Mention that the overflow semantics of
NEGATE_EXPR, PLUS_EXPR, MINUS_EXPR and MULT_EXPR is dependent
upon both flag_wrapv and flag_trapv.
* gcc.dg/fwrapv-1.c: New test case.
* gcc.dg/fwrapv-2.c: New test case.
* libjava.lang/Overflow.java: New test.
* libjava.lang/Overflow.out: New file.
From-SVN: r67270
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 381bc9cb959..e81e8090cf0 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -4381,6 +4381,7 @@ extract_muldiv_1 (t, c, code, wide_type) overflowed. */ if ((! TREE_UNSIGNED (ctype) || (TREE_CODE (ctype) == INTEGER_TYPE && TYPE_IS_SIZETYPE (ctype))) + && ! flag_wrapv && ((code == MULT_EXPR && tcode == EXACT_DIV_EXPR) || (tcode == MULT_EXPR && code != TRUNC_MOD_EXPR && code != CEIL_MOD_EXPR @@ -5765,7 +5766,8 @@ fold (expr) return fold (build (PLUS_EXPR, type, arg0, TREE_OPERAND (arg1, 0))); /* (-A) - B -> (-B) - A where B is easily negated and we can swap. */ if (TREE_CODE (arg0) == NEGATE_EXPR - && FLOAT_TYPE_P (type) + && (FLOAT_TYPE_P (type) + || (INTEGRAL_TYPE_P (type) && flag_wrapv && !flag_trapv)) && negate_expr_p (arg1) && (! TREE_SIDE_EFFECTS (arg0) || TREE_CONSTANT (arg1)) && (! TREE_SIDE_EFFECTS (arg1) || TREE_CONSTANT (arg0))) |