fp-vrp: Simplify test when optimising Minus(x0...0).

It is sufficient to test, whether the zero bits equal the minimal value.
If they are all zero, the result is constant and this optimisation is unnecessary.

diff --git a/ir/opt/fp-vrp.c b/ir/opt/fp-vrp.c
index 5a06aa5..f365ec2 100644 (file)
--- a/ir/opt/fp-vrp.c
+++ b/ir/opt/fp-vrp.c
@@ -755,7 +755,7 @@ exchange_only:
                                bitinfo   const *const b   = get_bitinfo(op);
                                ir_tarval       *const min = get_mode_min(mode);
 
-                               if (tarval_is_all_one(tarval_or(min, tarval_not(b->z)))) {
+                               if (b->z == min) {
                                        DB((dbg, LEVEL_2, "%+F(%+F) is superfluous\n", irn, op));
                                        exchange(irn, op);
                                        env->modified = 1;