diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 33 |
1 files changed, 32 insertions, 1 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index a7556f438e5..f707dfa55b8 100644 --- a/gcc/fold-const.c +++ b/gcc/fold-const.c @@ -102,6 +102,7 @@ static tree unextend PARAMS ((tree, int, int, tree)); static tree fold_truthop PARAMS ((enum tree_code, tree, tree, tree)); static tree optimize_minmax_comparison PARAMS ((tree)); static tree extract_muldiv PARAMS ((tree, tree, enum tree_code, tree)); +static tree extract_muldiv_1 PARAMS ((tree, tree, enum tree_code, tree)); static tree strip_compound_expr PARAMS ((tree, tree)); static int multiple_of_p PARAMS ((tree, tree, tree)); static tree constant_boolean_node PARAMS ((int, tree)); @@ -4044,6 +4045,31 @@ extract_muldiv (t, c, code, wide_type) enum tree_code code; tree wide_type; { + /* To avoid exponential search depth, refuse to allow recursion past + three levels. Beyond that (1) it's highly unlikely that we'll find + something interesting and (2) we've probably processed it before + when we built the inner expression. */ + + static int depth; + tree ret; + + if (depth > 3) + return NULL; + + depth++; + ret = extract_muldiv_1 (t, c, code, wide_type); + depth--; + + return ret; +} + +static tree +extract_muldiv_1 (t, c, code, wide_type) + tree t; + tree c; + enum tree_code code; + tree wide_type; +{ tree type = TREE_TYPE (t); enum tree_code tcode = TREE_CODE (t); tree ctype = (wide_type != 0 && (GET_MODE_SIZE (TYPE_MODE (wide_type)) @@ -4091,7 +4117,12 @@ extract_muldiv (t, c, code, wide_type) /* ... 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)))))) + < GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (op0)))) + /* ... or signedness changes for division or modulus, + then we cannot pass through this conversion. */ + || (code != MULT_EXPR + && (TREE_UNSIGNED (ctype) + != TREE_UNSIGNED (TREE_TYPE (op0)))))) break; /* Pass the constant down and see if we can make a simplification. If |