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

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index c240156f00386237ab99cd63fbc80772e9dd5e8a..448c7e608a7b98e9049dab37d46db6ff2ca8264f 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -255,6 +255,48 @@ class OutOfLineLoadZero 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) {
+      __ CheckPageFlagClear(value_, scratch0_,
+                            MemoryChunk::kPointersToHereAreInterestingMask,
+                            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:
@@ -529,6 +571,23 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kArchTruncateDoubleToI:
       __ TruncateDoubleToI(i.OutputRegister(), i.InputDoubleRegister(0));
       break;
+    case kArchStoreWithWriteBarrier: {
+      RecordWriteMode mode =
+          static_cast<RecordWriteMode>(MiscField::decode(instr->opcode()));
+      Register object = i.InputRegister(0);
+      Register index = i.InputRegister(1);
+      Register value = i.InputRegister(2);
+      Register scratch0 = i.TempRegister(0);
+      Register scratch1 = i.TempRegister(1);
+      auto ool = new (zone()) OutOfLineRecordWrite(this, object, index, value,
+                                                   scratch0, scratch1, mode);
+      __ Str(value, MemOperand(object, index));
+      __ CheckPageFlagSet(object, scratch0,
+                          MemoryChunk::kPointersFromHereAreInterestingMask,
+                          ool->entry());
+      __ Bind(ool->exit());
+      break;
+    }
     case kArm64Float64RoundDown:
       __ Frintm(i.OutputDoubleRegister(), i.InputDoubleRegister(0));
       break;
@@ -995,29 +1054,6 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
     case kArm64StrD:
       __ Str(i.InputDoubleRegister(2), i.MemoryOperand());
       break;
-    case kArm64StoreWriteBarrier: {
-      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;
-      // TODO(dcarney): we shouldn't test write barriers from c calls.
-      LinkRegisterStatus lr_status = kLRHasNotBeenSaved;
-      UseScratchRegisterScope scope(masm());
-      Register temp = no_reg;
-      if (csp.is(masm()->StackPointer())) {
-        temp = scope.AcquireX();
-        lr_status = kLRHasBeenSaved;
-        __ Push(lr, temp);  // Need to push a pair
-      }
-      __ RecordWrite(object, index, value, lr_status, mode);
-      if (csp.is(masm()->StackPointer())) {
-        __ Pop(temp, lr);
-      }
-      break;
-    }
     case kCheckedLoadInt8:
       ASSEMBLE_CHECKED_LOAD_INTEGER(Ldrsb);
       break;