ARM64: Optimize AllocateHeapNumber to use STP.

src/arm64/macro-assembler-arm64-inl.h

Index: src/arm64/macro-assembler-arm64-inl.h
diff --git a/src/arm64/macro-assembler-arm64-inl.h b/src/arm64/macro-assembler-arm64-inl.h
index d660d360161f766b35a78cacc2c56690b6e87348..4fd6d76c89f8186a9ce26edea1dbf1b9073a52c5 100644
--- a/src/arm64/macro-assembler-arm64-inl.h
+++ b/src/arm64/macro-assembler-arm64-inl.h
@@ -1409,6 +1409,30 @@ void MacroAssembler::JumpIfBothNotSmi(Register value1,
 }
 
 
+void MacroAssembler::ObjectTag(Register tagged_obj, Register obj) {
+  STATIC_ASSERT(kHeapObjectTag == 1);
+  if (emit_debug_code()) {
+    Label ok;
+    Tbz(obj, 0, &ok);
+    Abort(kObjectTagged);
+    Bind(&ok);
+  }
+  Orr(tagged_obj, obj, kHeapObjectTag);
+}
+
+
+void MacroAssembler::ObjectUntag(Register untagged_obj, Register obj) {
+  STATIC_ASSERT(kHeapObjectTag == 1);
+  if (emit_debug_code()) {
+    Label ok;
+    Tbnz(obj, 0, &ok);
+    Abort(kObjectNotTagged);
+    Bind(&ok);
+  }
+  Bic(untagged_obj, obj, kHeapObjectTag);
+}
+
+
 void MacroAssembler::IsObjectNameType(Register object,
                                       Register type,
                                       Label* fail) {