diff options
Diffstat (limited to 'gcc/fold-const.c')
| -rw-r--r-- | gcc/fold-const.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/gcc/fold-const.c b/gcc/fold-const.c index a7556f438e5..d3bcc98257b 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)) @@ -4252,6 +4278,14 @@ extract_muldiv (t, c, code, wide_type) && integer_zerop (const_binop (TRUNC_MOD_EXPR, op1, c, 0))) return omit_one_operand (type, integer_zero_node, op0); + /* Arrange for the code below to simplify two constants first. */ + if (TREE_CODE (op1) == INTEGER_CST && TREE_CODE (op0) != INTEGER_CST) + { + tree tmp = op0; + op0 = op1; + op1 = tmp; + } + /* ... fall through ... */ case TRUNC_DIV_EXPR: case CEIL_DIV_EXPR: case FLOOR_DIV_EXPR: |