[stubs] Remove dead string copying code

src/mips64/code-stubs-mips64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_MIPS64
 
 #include "src/code-stubs.h"
 #include "src/api-arguments.h"
 #include "src/bootstrapper.h"
 #include "src/codegen.h"
@@ skipping 2192 matching lines @@
   __ push(code_);
   __ CallRuntime(Runtime::kStringCharFromCode);
   __ Move(result_, v0);
 
   call_helper.AfterCall(masm);
   __ Branch(&exit_);
 
   __ Abort(kUnexpectedFallthroughFromCharFromCodeSlowCase);
 }
 
-
-enum CopyCharactersFlags { COPY_ONE_BYTE = 1, DEST_ALWAYS_ALIGNED = 2 };
-
-
-void StringHelper::GenerateCopyCharacters(MacroAssembler* masm,
-                                          Register dest,
-                                          Register src,
-                                          Register count,
-                                          Register scratch,
-                                          String::Encoding encoding) {
-  if (FLAG_debug_code) {
-    // Check that destination is word aligned.
-    __ And(scratch, dest, Operand(kPointerAlignmentMask));
-    __ Check(eq,
-             kDestinationOfCopyNotAligned,
-             scratch,
-             Operand(zero_reg));
-  }
-
-  // Assumes word reads and writes are little endian.
-  // Nothing to do for zero characters.
-  Label done;
-
-  if (encoding == String::TWO_BYTE_ENCODING) {
-    __ Daddu(count, count, count);
-  }
-
-  Register limit = count;  // Read until dest equals this.
-  __ Daddu(limit, dest, Operand(count));
-
-  Label loop_entry, loop;
-  // Copy bytes from src to dest until dest hits limit.
-  __ Branch(&loop_entry);
-  __ bind(&loop);
-  __ lbu(scratch, MemOperand(src));
-  __ daddiu(src, src, 1);
-  __ sb(scratch, MemOperand(dest));
-  __ daddiu(dest, dest, 1);
-  __ bind(&loop_entry);
-  __ Branch(&loop, lt, dest, Operand(limit));
-
-  __ bind(&done);
-}
-
-
 void StringHelper::GenerateFlatOneByteStringEquals(
     MacroAssembler* masm, Register left, Register right, Register scratch1,
     Register scratch2, Register scratch3) {
   Register length = scratch1;
 
   // Compare lengths.
   Label strings_not_equal, check_zero_length;
   __ ld(length, FieldMemOperand(left, String::kLengthOffset));
   __ ld(scratch2, FieldMemOperand(right, String::kLengthOffset));
   __ Branch(&check_zero_length, eq, length, Operand(scratch2));
@@ skipping 2285 matching lines @@
                            kStackUnwindSpace, kInvalidStackOffset,
                            return_value_operand, NULL);
 }
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_MIPS64