Implement inline string compare on ARM.

src/ia32/macro-assembler-ia32.cc

 // Copyright 2006-2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1507 matching lines @@
 
   push(eax);
   push(Immediate(p0));
   push(Immediate(reinterpret_cast<intptr_t>(Smi::FromInt(p1 - p0))));
   CallRuntime(Runtime::kAbort, 2);
   // will not return here
   int3();
 }
 
 
+void MacroAssembler::JumpIfNotBothSequentialAsciiStrings(Register object1,
+                                                         Register object2,
+                                                         Register scratch1,
+                                                         Register scratch2,
+                                                         Label* failure) {
+  // Check that both objects are not smis.
+  ASSERT_EQ(0, kSmiTag);
+  mov(scratch1, Operand(object1));
+  and_(scratch1, Operand(object2));
+  test(scratch1, Immediate(kSmiTagMask));
+  j(zero, failure);
+
+  // Load instance type for both strings.
+  mov(scratch1, FieldOperand(object1, HeapObject::kMapOffset));
+  mov(scratch2, FieldOperand(object2, HeapObject::kMapOffset));
+  movzx_b(scratch1, FieldOperand(scratch1, Map::kInstanceTypeOffset));
+  movzx_b(scratch2, FieldOperand(scratch2, Map::kInstanceTypeOffset));
+
+  // Check that both are flat ascii strings.
+  const int kFlatAsciiStringMask =
+      kIsNotStringMask | kStringRepresentationMask | kStringEncodingMask;
+  const int kFlatAsciiStringTag = ASCII_STRING_TYPE;
+  // Interleave bits from both instance types and compare them in one check.
+  ASSERT_EQ(0, kFlatAsciiStringMask & (kFlatAsciiStringMask << 3));
+  and_(scratch1, kFlatAsciiStringMask);
+  and_(scratch2, kFlatAsciiStringMask);
+  lea(scratch1, Operand(scratch1, scratch2, times_8, 0));
+  cmp(scratch1, kFlatAsciiStringTag | (kFlatAsciiStringTag << 3));
+  j(not_equal, failure);
+}
+
+
 CodePatcher::CodePatcher(byte* address, int size)
     : address_(address), size_(size), masm_(address, size + Assembler::kGap) {
   // Create a new macro assembler pointing to the address of the code to patch.
   // The size is adjusted with kGap on order for the assembler to generate size
   // bytes of instructions without failing with buffer size constraints.
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 CodePatcher::~CodePatcher() {
   // Indicate that code has changed.
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 
 } }  // namespace v8::internal