[optimizing] Fix a bug in moving the null check to the user.

When taking the decision to move a null check to the user we did not
verify if the next instruction checks the same object.

Change-Id: I2f4533a4bb18aa4b0b6d5e419f37dcccd60354d2

1 files changed, 4 insertions, 2 deletions

diff --git a/compiler/optimizing/code_generator.cc b/compiler/optimizing/code_generator.cc
index 8ab759d393..b14b69ba39 100644
--- a/compiler/optimizing/code_generator.cc
+++ b/compiler/optimizing/code_generator.cc
@@ -827,7 +827,9 @@ void CodeGenerator::RecordPcInfo(HInstruction* instruction,
 
 bool CodeGenerator::CanMoveNullCheckToUser(HNullCheck* null_check) {
   HInstruction* first_next_not_move = null_check->GetNextDisregardingMoves();
-  return (first_next_not_move != nullptr) && first_next_not_move->CanDoImplicitNullCheck();
+
+  return (first_next_not_move != nullptr)
+      && first_next_not_move->CanDoImplicitNullCheckOn(null_check->InputAt(0));
 }
 
 void CodeGenerator::MaybeRecordImplicitNullCheck(HInstruction* instr) {
@@ -842,7 +844,7 @@ void CodeGenerator::MaybeRecordImplicitNullCheck(HInstruction* instr) {
     return;
   }
 
-  if (!instr->CanDoImplicitNullCheck()) {
+  if (!instr->CanDoImplicitNullCheckOn(instr->InputAt(0))) {
     return;
   }