Fix another case of live_in at irreducible loop entry.

GVN was implicitly extending the liveness of an instruction across
an irreducible loop.

Fix this problem by clearing the value set at loop entries that contain
an irreducible loop.

bug:28252896

(cherry picked from commit 77ce6430af2709432b22344ed656edd8ec80581b)

Change-Id: Ie0121e83b2dfe47bcd184b90a69c0194d13fce54

1 files changed, 3 insertions, 1 deletions

diff --git a/compiler/optimizing/register_allocator.cc b/compiler/optimizing/register_allocator.cc
index b1f9cbcdfa..4405b803e0 100644
--- a/compiler/optimizing/register_allocator.cc
+++ b/compiler/optimizing/register_allocator.cc
@@ -1773,7 +1773,9 @@ void RegisterAllocator::ConnectSplitSiblings(LiveInterval* interval,
     // therefore will not have a location for that instruction for `to`.
     // Because the instruction is a constant or the ArtMethod, we don't need to
     // do anything: it will be materialized in the irreducible loop.
-    DCHECK(IsMaterializableEntryBlockInstructionOfGraphWithIrreducibleLoop(defined_by));
+    DCHECK(IsMaterializableEntryBlockInstructionOfGraphWithIrreducibleLoop(defined_by))
+        << defined_by->DebugName() << ":" << defined_by->GetId()
+        << " " << from->GetBlockId() << " -> " << to->GetBlockId();
     return;
   }