Quick: Finding upper half of kMirOpCheckPart2 should passthough empty blocks

Mir2Lir::InitReferenceVRegs trying to find throwing instruction for
kMirOpCheckPart2 should traverse possible empty blocks which compiler
optimizations could generate between them.

Change-Id: I2ab29dd36635fd4c4ef2dd81b51e571e206775e6
Signed-off-by: Pavel Vyssotski <pavel.n.vyssotski@intel.com>

1 files changed, 10 insertions, 5 deletions

diff --git a/compiler/dex/quick/codegen_util.cc b/compiler/dex/quick/codegen_util.cc
index bd479bef5b..df72830801 100644
--- a/compiler/dex/quick/codegen_util.cc
+++ b/compiler/dex/quick/codegen_util.cc
@@ -1378,11 +1378,16 @@ void Mir2Lir::InitReferenceVRegs(BasicBlock* bb, BitVector* references) {
     // In Mir2Lir::MethodBlockCodeGen() we have artificially moved the throwing
     // instruction to the previous block. However, the MIRGraph data used above
     // doesn't reflect that, so we still need to process that MIR insn here.
-    DCHECK_EQ(bb->predecessors.size(), 1u);
-    BasicBlock* pred_bb = mir_graph_->GetBasicBlock(bb->predecessors[0]);
-    DCHECK(pred_bb != nullptr);
-    DCHECK(pred_bb->last_mir_insn != nullptr);
-    UpdateReferenceVRegsLocal(nullptr, pred_bb->last_mir_insn, references);
+    MIR* mir = nullptr;
+    BasicBlock* pred_bb = bb;
+    // Traverse empty blocks.
+    while (mir == nullptr && pred_bb->predecessors.size() == 1u) {
+      pred_bb = mir_graph_->GetBasicBlock(bb->predecessors[0]);
+      DCHECK(pred_bb != nullptr);
+      mir = pred_bb->last_mir_insn;
+    }
+    DCHECK(mir != nullptr);
+    UpdateReferenceVRegsLocal(nullptr, mir, references);
   }
 }