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

src/compiler/instruction-codes.h

Index: src/compiler/instruction-codes.h
diff --git a/src/compiler/instruction-codes.h b/src/compiler/instruction-codes.h
index 00b3f70b2746151b039243f81269481d00f03c7f..dca29d8b500f174d7d5618127896cd50a8152472 100644
--- a/src/compiler/instruction-codes.h
+++ b/src/compiler/instruction-codes.h
@@ -33,6 +33,12 @@ namespace v8 {
 namespace internal {
 namespace compiler {
 
+// Modes for ArchRecordWrite below.
+enum class RecordWriteMode { kValueIsMap, kValueIsPointer, kValueIsAny };
+
+std::ostream& operator<<(std::ostream&, RecordWriteMode);
+
+
 // Target-specific opcodes that specify which assembly sequence to emit.
 // Most opcodes specify a single instruction.
 #define ARCH_OPCODE_LIST(V)   \
@@ -52,6 +58,7 @@ namespace compiler {
   V(ArchStackPointer)         \
   V(ArchFramePointer)         \
   V(ArchTruncateDoubleToI)    \
+  V(ArchRecordWrite)          \
   V(CheckedLoadInt8)          \
   V(CheckedLoadUint8)         \
   V(CheckedLoadInt16)         \