[compiler] Introduce initial StrictEqualStub.

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 9e8364feca34c4593ceffaa63d039f1092623c71..7be35447ce3132366d7669ebf3a43d09afa9e66b 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -3179,10 +3179,17 @@ void CompareICStub::GenerateStrings(MacroAssembler* masm) {
 
   // Handle more complex cases in runtime.
   __ bind(&runtime);
-  __ Push(left, right);
   if (equality) {
-    __ TailCallRuntime(Runtime::kStringEquals);
+    {
+      FrameAndConstantPoolScope scope(masm, StackFrame::INTERNAL);
+      __ Push(left, right);
+      __ CallRuntime(Runtime::kStringEqual);
+    }
+    __ LoadRoot(r1, Heap::kTrueValueRootIndex);
+    __ sub(r0, r0, r1);

[Yang, 2016/03/02 10:29:16]

Whoa, this is kind of hacky here. In the original Runtime_StringEqual we assert
that the result can only be a smi-0 or a smi-1. This here returns smi-0 on
equal, but definitely not smi-1 on unequality. Does the CompareIC only care
whether the result is 0 or not?

[Benedikt Meurer, 2016/03/02 11:27:04]

Yes, 0 is for EQUAL, everything else for NOT_EQUAL (CompareIC is weird).

+    __ Ret();
   } else {
+    __ Push(left, right);
     __ TailCallRuntime(Runtime::kStringCompare);
   }