commit 07276db28d654594e0e86e9e467cad393f752e6e
author Nicolas Geoffray <ngeoffray@google.com> Mon May 18 14:22:09 2015 +0100
committer Nicolas Geoffray <ngeoffray@google.com> Mon May 18 19:15:52 2015 +0100
tree 6450e07d64045f0c0949b3423501316b672641c7
parent 17f1bc531ea2f8c1a6fac3def13dee1b901949dd

Don't do a null test in MarkGCCard if the value cannot be null.

Change-Id: I45687f6d3505178e2fc3689eac9cb6ab1b2c1e29

compiler/optimizing/code_generator_x86.cc

diff --git a/compiler/optimizing/code_generator_x86.cc b/compiler/optimizing/code_generator_x86.cc
index 0212da1..a6f01da 100644
--- a/compiler/optimizing/code_generator_x86.cc
+++ b/compiler/optimizing/code_generator_x86.cc
@@ -3227,16 +3227,24 @@
   DCHECK(!IsLeafMethod());
 }
 
-void CodeGeneratorX86::MarkGCCard(Register temp, Register card, Register object, Register value) {
+void CodeGeneratorX86::MarkGCCard(Register temp,
+                                  Register card,
+                                  Register object,
+                                  Register value,
+                                  bool value_can_be_null) {
   Label is_null;
-  __ testl(value, value);
-  __ j(kEqual, &is_null);
+  if (value_can_be_null) {
+    __ testl(value, value);
+    __ j(kEqual, &is_null);
+  }
   __ fs()->movl(card, Address::Absolute(Thread::CardTableOffset<kX86WordSize>().Int32Value()));
   __ movl(temp, object);
   __ shrl(temp, Immediate(gc::accounting::CardTable::kCardShift));
   __ movb(Address(temp, card, TIMES_1, 0),
           X86ManagedRegister::FromCpuRegister(card).AsByteRegister());
-  __ Bind(&is_null);
+  if (value_can_be_null) {
+    __ Bind(&is_null);
+  }
 }
 
 void LocationsBuilderX86::HandleFieldGet(HInstruction* instruction, const FieldInfo& field_info) {
@@ -3381,7 +3389,8 @@
 }
 
 void InstructionCodeGeneratorX86::HandleFieldSet(HInstruction* instruction,
-                                                 const FieldInfo& field_info) {
+                                                 const FieldInfo& field_info,
+                                                 bool value_can_be_null) {
   DCHECK(instruction->IsInstanceFieldSet() || instruction->IsStaticFieldSet());
 
   LocationSummary* locations = instruction->GetLocations();
@@ -3454,7 +3463,7 @@
   if (CodeGenerator::StoreNeedsWriteBarrier(field_type, instruction->InputAt(1))) {
     Register temp = locations->GetTemp(0).AsRegister<Register>();
     Register card = locations->GetTemp(1).AsRegister<Register>();
-    codegen_->MarkGCCard(temp, card, base, value.AsRegister<Register>());
+    codegen_->MarkGCCard(temp, card, base, value.AsRegister<Register>(), value_can_be_null);
   }
 
   if (is_volatile) {
@@ -3475,7 +3484,7 @@
 }
 
 void InstructionCodeGeneratorX86::VisitStaticFieldSet(HStaticFieldSet* instruction) {
-  HandleFieldSet(instruction, instruction->GetFieldInfo());
+  HandleFieldSet(instruction, instruction->GetFieldInfo(), instruction->GetValueCanBeNull());
 }
 
 void LocationsBuilderX86::VisitInstanceFieldSet(HInstanceFieldSet* instruction) {
@@ -3483,7 +3492,7 @@
 }
 
 void InstructionCodeGeneratorX86::VisitInstanceFieldSet(HInstanceFieldSet* instruction) {
-  HandleFieldSet(instruction, instruction->GetFieldInfo());
+  HandleFieldSet(instruction, instruction->GetFieldInfo(), instruction->GetValueCanBeNull());
 }
 
 void LocationsBuilderX86::VisitInstanceFieldGet(HInstanceFieldGet* instruction) {
@@ -3817,7 +3826,8 @@
         if (needs_write_barrier) {
           Register temp = locations->GetTemp(0).AsRegister<Register>();
           Register card = locations->GetTemp(1).AsRegister<Register>();
-          codegen_->MarkGCCard(temp, card, obj, value.AsRegister<Register>());
+          codegen_->MarkGCCard(
+              temp, card, obj, value.AsRegister<Register>(), instruction->GetValueCanBeNull());
         }
       } else {
         DCHECK_EQ(value_type, Primitive::kPrimNot);