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| author | Eric Botcazou <ebotcazou@multimania.com> | 2002-06-15 00:40:49 +0000 |
|---|---|---|
| committer | Richard Henderson <rth@gcc.gnu.org> | 2002-06-14 17:40:49 -0700 |
| commit | 43e4a9d87010344f9ba60c22983b6d378736fca3 (patch) | |
| tree | fd51ff69789e0093e1ae97e5bbca49e30ec16d37 /gcc/convert.c | |
| parent | fa4a5557dd8f2e4a57bd30bfdf55115c302fc189 (diff) | |
| download | gcc-43e4a9d87010344f9ba60c22983b6d378736fca3.zip gcc-43e4a9d87010344f9ba60c22983b6d378736fca3.tar.gz gcc-43e4a9d87010344f9ba60c22983b6d378736fca3.tar.bz2 | |
convert.c (convert_to_integer): Don't pass the truncation down when the target type is signed.
* convert.c (convert_to_integer) [LSHIFT_EXPR]: Don't pass
the truncation down when the target type is signed.
[trunc1]: Use unsigned arithmetic for LSHIFT_EXPR.
* fold-const.c (extract_muldiv) [NOP_EXPR]: Don't pass through
the conversion if the target type is a smaller type.
From-SVN: r54627
Diffstat (limited to 'gcc/convert.c')
| -rw-r--r-- | gcc/convert.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/gcc/convert.c b/gcc/convert.c index 970b05c..e90ce4c 100644 --- a/gcc/convert.c +++ b/gcc/convert.c @@ -229,9 +229,11 @@ convert_to_integer (type, expr) case LSHIFT_EXPR: /* We can pass truncation down through left shifting - when the shift count is a nonnegative constant. */ + when the shift count is a nonnegative constant and + the target type is unsigned. */ if (TREE_CODE (TREE_OPERAND (expr, 1)) == INTEGER_CST && tree_int_cst_sgn (TREE_OPERAND (expr, 1)) >= 0 + && TREE_UNSIGNED (type) && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST) { /* If shift count is less than the width of the truncated type, @@ -313,12 +315,22 @@ convert_to_integer (type, expr) /* Don't do unsigned arithmetic where signed was wanted, or vice versa. Exception: if both of the original operands were - unsigned then can safely do the work as unsigned. + unsigned then we can safely do the work as unsigned. + Exception: shift operations take their type solely + from the first argument. + Exception: the LSHIFT_EXPR case above requires that + we perform this operation unsigned lest we produce + signed-overflow undefinedness. And we may need to do it as unsigned if we truncate to the original size. */ if (TREE_UNSIGNED (TREE_TYPE (expr)) || (TREE_UNSIGNED (TREE_TYPE (arg0)) - && TREE_UNSIGNED (TREE_TYPE (arg1)))) + && (TREE_UNSIGNED (TREE_TYPE (arg1)) + || ex_form == LSHIFT_EXPR + || ex_form == RSHIFT_EXPR + || ex_form == LROTATE_EXPR + || ex_form == RROTATE_EXPR)) + || ex_form == LSHIFT_EXPR) typex = (*lang_hooks.types.unsigned_type) (typex); else typex = (*lang_hooks.types.signed_type) (typex); |