Record implicit null checks at the actual invoke time.

ImplicitNullChecks are recorded only for instructions directly (see NB
below) preceeded by NullChecks in the graph. This way we avoid recording
redundant safepoints and minimize the code size increase.

NB: ParallalelMoves might be inserted by the register allocator between
the NullChecks and their uses. These modify the environment and the
correct action would be to reverse their modification. This will be
addressed in a follow-up CL.

Change-Id: Ie50006e5a4bd22932dcf11348f5a655d253cd898

1 files changed, 18 insertions, 5 deletions

diff --git a/compiler/optimizing/nodes.cc b/compiler/optimizing/nodes.cc
index ade31380ec..39ec22bea1 100644
--- a/compiler/optimizing/nodes.cc
+++ b/compiler/optimizing/nodes.cc
@@ -15,6 +15,7 @@
  */
 
 #include "nodes.h"
+
 #include "ssa_builder.h"
 #include "utils/growable_array.h"
 
@@ -456,6 +457,22 @@ static void RemoveFromUseList(T* user,
   }
 }
 
+HInstruction* HInstruction::GetNextDisregardingMoves() const {
+  HInstruction* next = GetNext();
+  while (next != nullptr && next->IsParallelMove()) {
+    next = next->GetNext();
+  }
+  return next;
+}
+
+HInstruction* HInstruction::GetPreviousDisregardingMoves() const {
+  HInstruction* previous = GetPrevious();
+  while (previous != nullptr && previous->IsParallelMove()) {
+    previous = previous->GetPrevious();
+  }
+  return previous;
+}
+
 void HInstruction::RemoveUser(HInstruction* user, size_t input_index) {
   RemoveFromUseList(user, input_index, &uses_);
 }
@@ -654,11 +671,7 @@ HConstant* HBinaryOperation::TryStaticEvaluation() const {
 }
 
 bool HCondition::IsBeforeWhenDisregardMoves(HIf* if_) const {
-  HInstruction* previous = if_->GetPrevious();
-  while (previous != nullptr && previous->IsParallelMove()) {
-    previous = previous->GetPrevious();
-  }
-  return previous == this;
+  return this == if_->GetPreviousDisregardingMoves();
 }
 
 bool HInstruction::Equals(HInstruction* other) const {