[turbofan] Avoid unnecessary write barriers and improve code generation.

src/compiler/arm/code-generator-arm.cc

Index: src/compiler/arm/code-generator-arm.cc
diff --git a/src/compiler/arm/code-generator-arm.cc b/src/compiler/arm/code-generator-arm.cc
index fc5ad8d801d9d2f82b2d31e8406d7655d78d0cf4..4480abe21dd83008f3c457d701949d845e2e2c8d 100644
--- a/src/compiler/arm/code-generator-arm.cc
+++ b/src/compiler/arm/code-generator-arm.cc
@@ -198,6 +198,48 @@ class OutOfLineLoadInteger final : public OutOfLineCode {
 };
 
 
+class OutOfLineRecordWrite final : public OutOfLineCode {
+ public:
+  OutOfLineRecordWrite(CodeGenerator* gen, Register object, Register index,
+                       Register value, Register scratch0, Register scratch1,
+                       RecordWriteMode mode)
+      : OutOfLineCode(gen),
+        object_(object),
+        index_(index),
+        value_(value),
+        scratch0_(scratch0),
+        scratch1_(scratch1),
+        mode_(mode) {}
+
+  void Generate() final {
+    if (mode_ > RecordWriteMode::kValueIsPointer) {
+      __ JumpIfSmi(value_, exit());
+    }
+    if (mode_ > RecordWriteMode::kValueIsMap) {
+      __ CheckPageFlag(value_, scratch0_,
+                       MemoryChunk::kPointersToHereAreInterestingMask, eq,
+                       exit());
+    }
+    SaveFPRegsMode const save_fp_mode =
+        frame()->DidAllocateDoubleRegisters() ? kSaveFPRegs : kDontSaveFPRegs;
+    // TODO(turbofan): Once we get frame elision working, we need to save
+    // and restore lr properly here if the frame was elided.
+    RecordWriteStub stub(isolate(), object_, scratch0_, scratch1_,
+                         EMIT_REMEMBERED_SET, save_fp_mode);
+    __ add(scratch1_, object_, index_);
+    __ CallStub(&stub);
+  }
+
+ private:
+  Register const object_;
+  Register const index_;
+  Register const value_;
+  Register const scratch0_;
+  Register const scratch1_;
+  RecordWriteMode const mode_;
+};
+
+
 Condition FlagsConditionToCondition(FlagsCondition condition) {
   switch (condition) {
     case kEqual:
@@ -443,6 +485,23 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ TruncateDoubleToI(i.OutputRegister(), i.InputFloat64Register(0));
       DCHECK_EQ(LeaveCC, i.OutputSBit());
       break;
+    case kArchRecordWrite: {
+      RecordWriteMode mode =
+          static_cast<RecordWriteMode>(MiscField::decode(instr->opcode()));
+      Register object = i.InputRegister(0);
+      Register index = i.InputRegister(1);
+      Register value =
+          (mode > RecordWriteMode::kValueIsMap) ? i.InputRegister(2) : no_reg;
+      Register scratch0 = i.TempRegister(0);
+      Register scratch1 = i.TempRegister(1);
+      auto ool = new (zone()) OutOfLineRecordWrite(this, object, index, value,
+                                                   scratch0, scratch1, mode);
+      __ CheckPageFlag(object, scratch0,
+                       MemoryChunk::kPointersFromHereAreInterestingMask, ne,
+                       ool->entry());
+      __ bind(ool->exit());
+      break;
+    }
     case kArmAdd:
       __ add(i.OutputRegister(), i.InputRegister(0), i.InputOperand2(1),
              i.OutputSBit());
@@ -848,19 +907,6 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       DCHECK_EQ(LeaveCC, i.OutputSBit());
       break;
     }
-    case kArmStoreWriteBarrier: {
-      Register object = i.InputRegister(0);
-      Register index = i.InputRegister(1);
-      Register value = i.InputRegister(2);
-      __ add(index, object, index);
-      __ str(value, MemOperand(index));
-      SaveFPRegsMode mode =
-          frame()->DidAllocateDoubleRegisters() ? kSaveFPRegs : kDontSaveFPRegs;
-      LinkRegisterStatus lr_status = kLRHasNotBeenSaved;
-      __ RecordWrite(object, index, value, lr_status, mode);
-      DCHECK_EQ(LeaveCC, i.OutputSBit());
-      break;
-    }
     case kCheckedLoadInt8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(ldrsb);
       break;