git: openjdk/jdk: 8254369: Node::disconnect_inputs may skip precedences

[Vladimir Kozlov]

Changeset: bdda2058
Author:    Xin Liu <xliu at openjdk.org>
Committer: Vladimir Kozlov <kvn at openjdk.org>
Date:      2020-10-16 01:59:07 +0000
URL:       https://git.openjdk.java.net/jdk/commit/bdda2058

8254369: Node::disconnect_inputs may skip precedences

disconnect_inputs() needs to iterate precedences edges in reverse order because rm_prec(i) may backfill _in[i] with a value afterward.
also remove the predicate if (n != NULL) in set_prec because it's always true.

Reviewed-by: kvn, redestad

! src/hotspot/share/opto/node.cpp
! src/hotspot/share/opto/node.hpp