diff options
| -rw-r--r-- | gcc/ChangeLog | 8 | ||||
| -rw-r--r-- | gcc/convert.c | 18 | ||||
| -rw-r--r-- | gcc/fold-const.c | 19 |
3 files changed, 35 insertions, 10 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 197ac51..30640c7 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,11 @@ +2002-06-14 Eric Botcazou <ebotcazou@multimania.com> + + * 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. + 2002-06-14 Richard Henderson <rth@redhat.com> * fold-const.c (fold) [compare ops]: Move X>=C / X<C transfomation 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); diff --git a/gcc/fold-const.c b/gcc/fold-const.c index 31bcddb..5c04d78 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -3969,17 +3969,22 @@ extract_muldiv (t, c, code, wide_type) break; case CONVERT_EXPR: case NON_LVALUE_EXPR: case NOP_EXPR: - /* If op0 is an expression, and is unsigned, and the type is - smaller than ctype, then we cannot widen the expression. */ + /* If op0 is an expression ... */ if ((TREE_CODE_CLASS (TREE_CODE (op0)) == '<' || TREE_CODE_CLASS (TREE_CODE (op0)) == '1' || TREE_CODE_CLASS (TREE_CODE (op0)) == '2' || TREE_CODE_CLASS (TREE_CODE (op0)) == 'e') - && TREE_UNSIGNED (TREE_TYPE (op0)) - && ! (TREE_CODE (TREE_TYPE (op0)) == INTEGER_TYPE - && TYPE_IS_SIZETYPE (TREE_TYPE (op0))) - && (GET_MODE_SIZE (TYPE_MODE (ctype)) - > GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0))))) + /* ... and is unsigned, and its type is smaller than ctype, + then we cannot pass through as widening. */ + && ((TREE_UNSIGNED (TREE_TYPE (op0)) + && ! (TREE_CODE (TREE_TYPE (op0)) == INTEGER_TYPE + && TYPE_IS_SIZETYPE (TREE_TYPE (op0))) + && (GET_MODE_SIZE (TYPE_MODE (ctype)) + > GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0))))) + /* ... or its type is larger than ctype, + then we cannot pass through this truncation. */ + || (GET_MODE_SIZE (TYPE_MODE (ctype)) + < GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0)))))) break; /* Pass the constant down and see if we can make a simplification. If |