commit 8909bafa5d64e12eb53f3d37b984f53e7a632224
author Guillaume "Vermeille" Sanchez <guillaumesa@google.com> Thu Apr 23 21:35:11 2015 +0100
committer Guillaume "Vermeille" Sanchez <guillaumesa@google.com> Mon May 18 17:58:21 2015 +0100
tree 6bac613ed796914ec4937a64d40d44b1888d4878
parent 06675720cc274eb9d91a4ecd3fb1eef94a2d88f0

Mark CheckCast's and InstanceOf's input as !CanBeNull if used before in a NullCheck

Change-Id: Ied0412a01922b40a3f5d89bed49707498582abc1

compiler/optimizing/instruction_simplifier.cc

diff --git a/compiler/optimizing/instruction_simplifier.cc b/compiler/optimizing/instruction_simplifier.cc
index 46fad17..86c4a98 100644
--- a/compiler/optimizing/instruction_simplifier.cc
+++ b/compiler/optimizing/instruction_simplifier.cc
@@ -63,6 +63,7 @@
   void VisitUShr(HUShr* instruction) OVERRIDE;
   void VisitXor(HXor* instruction) OVERRIDE;
   void VisitInstanceOf(HInstanceOf* instruction) OVERRIDE;
+  bool IsDominatedByInputNullCheck(HInstruction* instr);
 
   OptimizingCompilerStats* stats_;
   bool simplification_occurred_ = false;
@@ -170,9 +171,20 @@
   }
 }
 
+bool InstructionSimplifierVisitor::IsDominatedByInputNullCheck(HInstruction* instr) {
+  HInstruction* input = instr->InputAt(0);
+  for (HUseIterator<HInstruction*> it(input->GetUses()); !it.Done(); it.Advance()) {
+    HInstruction* use = it.Current()->GetUser();
+    if (use->IsNullCheck() && use->StrictlyDominates(instr)) {
+      return true;
+    }
+  }
+  return false;
+}
+
 void InstructionSimplifierVisitor::VisitCheckCast(HCheckCast* check_cast) {
   HLoadClass* load_class = check_cast->InputAt(1)->AsLoadClass();
-  if (!check_cast->InputAt(0)->CanBeNull()) {
+  if (!check_cast->InputAt(0)->CanBeNull() || IsDominatedByInputNullCheck(check_cast)) {
     check_cast->ClearMustDoNullCheck();
   }
 
@@ -194,7 +206,7 @@
 }
 
 void InstructionSimplifierVisitor::VisitInstanceOf(HInstanceOf* instruction) {
-  if (!instruction->InputAt(0)->CanBeNull()) {
+  if (!instruction->InputAt(0)->CanBeNull() || IsDominatedByInputNullCheck(instruction)) {
     instruction->ClearMustDoNullCheck();
   }
 }

compiler/optimizing/nodes.h

diff --git a/compiler/optimizing/nodes.h b/compiler/optimizing/nodes.h
index cb2e5cc..801563d 100644
--- a/compiler/optimizing/nodes.h
+++ b/compiler/optimizing/nodes.h
@@ -3895,7 +3895,9 @@
       }
       for (size_t i = 0, e = moves_.Size(); i < e; ++i) {
         DCHECK(!destination.OverlapsWith(moves_.Get(i).GetDestination()))
-            << "Overlapped destination for two moves in a parallel move.";
+            << "Overlapped destination for two moves in a parallel move: "
+            << moves_.Get(i).GetSource() << " ==> " << moves_.Get(i).GetDestination() << " and "
+            << source << " ==> " << destination;
       }
     }
     moves_.Add(MoveOperands(source, destination, type, instruction));

compiler/optimizing/ssa_builder.cc

diff --git a/compiler/optimizing/ssa_builder.cc b/compiler/optimizing/ssa_builder.cc
index 59a2852..aac5211 100644
--- a/compiler/optimizing/ssa_builder.cc
+++ b/compiler/optimizing/ssa_builder.cc
@@ -504,7 +504,7 @@
     // typed and the value in a dex register will not be used for both floating point and
     // non-floating point operations. So the only reason an instruction would want a floating
     // point equivalent is for an unused phi that will be removed by the dead phi elimination phase.
-    DCHECK(user->IsPhi());
+    DCHECK(user->IsPhi()) << "is actually " << user->DebugName() << " (" << user->GetId() << ")";
     return value;
   }
 }