diff options
Diffstat (limited to 'gcc/tree-vrp.c')
| -rw-r--r-- | gcc/tree-vrp.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/gcc/tree-vrp.c b/gcc/tree-vrp.c index bd238d57700..c49c9424885 100644 --- a/gcc/tree-vrp.c +++ b/gcc/tree-vrp.c @@ -2434,6 +2434,7 @@ extract_range_from_binary_expr_1 (value_range_t *vr, && code != MAX_EXPR && code != PLUS_EXPR && code != MINUS_EXPR + && code != RSHIFT_EXPR && (vr0.type == VR_VARYING || vr1.type == VR_VARYING || vr0.type != vr1.type @@ -2948,6 +2949,15 @@ extract_range_from_binary_expr_1 (value_range_t *vr, { if (code == RSHIFT_EXPR) { + /* Even if vr0 is VARYING or otherwise not usable, we can derive + useful ranges just from the shift count. E.g. + x >> 63 for signed 64-bit x is always [-1, 0]. */ + if (vr0.type != VR_RANGE || symbolic_range_p (&vr0)) + { + vr0.type = type = VR_RANGE; + vr0.min = vrp_val_min (expr_type); + vr0.max = vrp_val_max (expr_type); + } extract_range_from_multiplicative_op_1 (vr, code, &vr0, &vr1); return; } |