diff options
Diffstat (limited to 'gcc/tree-vrp.c')
| -rw-r--r-- | gcc/tree-vrp.c | 24 |
1 files changed, 23 insertions, 1 deletions
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index 9309264..47c68d8 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -2066,7 +2066,8 @@ extract_range_from_multiplicative_op_1 (value_range_t *vr, || code == CEIL_DIV_EXPR || code == EXACT_DIV_EXPR || code == ROUND_DIV_EXPR - || code == RSHIFT_EXPR); + || code == RSHIFT_EXPR + || code == LSHIFT_EXPR); gcc_assert ((vr0->type == VR_RANGE || (code == MULT_EXPR && vr0->type == VR_ANTI_RANGE)) && vr0->type == vr1->type); @@ -2762,6 +2763,27 @@ extract_range_from_binary_expr_1 (value_range_t *vr, flag_wrapv = saved_flag_wrapv; return; } + else if (code == LSHIFT_EXPR + && range_int_cst_p (&vr0)) + { + int overflow_pos = TYPE_PRECISION (expr_type); + int bound_shift; + double_int bound; + + if (!TYPE_UNSIGNED (expr_type)) + overflow_pos -= 1; + + bound_shift = overflow_pos - TREE_INT_CST_LOW (vr1.max); + bound = double_int_one.llshift (bound_shift, + TYPE_PRECISION (expr_type)); + if (tree_to_double_int (vr0.max).ult (bound)) + { + /* In the absense of overflow, (a << b) is equivalent + to (a * 2^b). */ + extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1); + return; + } + } } set_value_range_to_varying (vr); return; |