Write barrier for storing a code entry, and usage in CompileLazy builtin.

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index eda1867e096360ce489da2c5fdb57c2cfcb38fe3..848ec7d1bf6d178ca2156563a2312290b58c4264 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -651,6 +651,69 @@ void MacroAssembler::RecordWrite(
   }
 }
 
+void MacroAssembler::RecordWriteCodeEntryField(Register js_function,
+                                               Register code_entry,
+                                               Register scratch) {
+  const int offset = JSFunction::kCodeEntryOffset;
+
+  // Since a code entry (value) is always in old space, we don't need to update
+  // remembered set. If incremental marking is off, there is nothing for us to
+  // do.
+  if (!FLAG_incremental_marking) return;
+
+  DCHECK(js_function.is(r1));
+  DCHECK(code_entry.is(r4));
+  DCHECK(scratch.is(r5));
+  AssertNotSmi(js_function);
+
+  if (emit_debug_code()) {
+    add(scratch, js_function, Operand(offset - kHeapObjectTag));
+    ldr(ip, MemOperand(scratch));
+    cmp(ip, code_entry);
+    Check(eq, kWrongAddressOrValuePassedToRecordWrite);
+  }
+
+  // First, check if a write barrier is even needed. The tests below
+  // catch stores of Smis and stores into young gen.
+  Label done;
+
+  CheckPageFlag(code_entry, scratch,
+                MemoryChunk::kPointersToHereAreInterestingMask, eq, &done);
+  CheckPageFlag(js_function, scratch,
+                MemoryChunk::kPointersFromHereAreInterestingMask, eq, &done);
+
+  const Register dst = scratch;
+  add(dst, js_function, Operand(offset - kHeapObjectTag));
+
+  push(code_entry);
+
+  // Save caller-saved registers, which includes js_function.
+  DCHECK((kCallerSaved & js_function.bit()) != 0);
+  DCHECK_EQ(kCallerSaved & code_entry.bit(), 0);
+  stm(db_w, sp, (kCallerSaved | lr.bit()));
+
+  int argument_count = 3;
+  PrepareCallCFunction(argument_count, code_entry);
+
+  mov(r0, js_function);
+  mov(r1, dst);
+  mov(r2, Operand(ExternalReference::isolate_address(isolate())));
+
+  {
+    AllowExternalCallThatCantCauseGC scope(this);
+    CallCFunction(
+        ExternalReference::incremental_marking_record_write_code_entry_function(
+            isolate()),
+        argument_count);
+  }
+
+  // Restore caller-saved registers (including js_function and code_entry).
+  ldm(ia_w, sp, (kCallerSaved | lr.bit()));
+
+  pop(code_entry);
+
+  bind(&done);
+}
 
 void MacroAssembler::RememberedSetHelper(Register object,  // For debug tests.
                                          Register address,