[compiler] Introduce code stubs for string relational comparisons.

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index 147881f7cf9fabeff5e4d0c8873c0ff6f4391341..ca9f4b90d0c9e96ebf9c93bcd269633a59f6a371 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -3468,43 +3468,6 @@ void StringHelper::GenerateOneByteCharsCompareLoop(
 }
 
 
-void StringCompareStub::Generate(MacroAssembler* masm) {
-  // ----------- S t a t e -------------
-  //  -- x1    : left
-  //  -- x0    : right
-  //  -- lr    : return address
-  // -----------------------------------
-  __ AssertString(x1);
-  __ AssertString(x0);
-
-  Label not_same;
-  __ Cmp(x0, x1);
-  __ B(ne, &not_same);
-  __ Mov(x0, Smi::FromInt(EQUAL));
-  __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, x3,
-                      x4);
-  __ Ret();
-
-  __ Bind(&not_same);
-
-  // Check that both objects are sequential one-byte strings.
-  Label runtime;
-  __ JumpIfEitherIsNotSequentialOneByteStrings(x1, x0, x12, x13, &runtime);
-
-  // Compare flat one-byte strings natively.
-  __ IncrementCounter(isolate()->counters()->string_compare_native(), 1, x3,
-                      x4);
-  StringHelper::GenerateCompareFlatOneByteStrings(masm, x1, x0, x12, x13, x14,
-                                                  x15);
-
-  // Call the runtime.
-  // Returns -1 (less), 0 (equal), or 1 (greater) tagged as a small integer.
-  __ Bind(&runtime);
-  __ Push(x1, x0);
-  __ TailCallRuntime(Runtime::kStringCompare);
-}
-
-
 void BinaryOpICWithAllocationSiteStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- x1    : left