Using array index hash code for string-to-number conversion.

src/arm/macro-assembler-arm.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 1319 matching lines @@
 
 
 void MacroAssembler::IllegalOperation(int num_arguments) {
   if (num_arguments > 0) {
     add(sp, sp, Operand(num_arguments * kPointerSize));
   }
   LoadRoot(r0, Heap::kUndefinedValueRootIndex);
 }
 
 
+void MacroAssembler::IndexFromHash(Register hash, Register index) {
+  // If the hash field contains an array index pick it out. The assert checks
+  // that the constants for the maximum number of digits for an array index
+  // cached in the hash field and the number of bits reserved for it does not
+  // conflict.
+  ASSERT(TenToThe(String::kMaxCachedArrayIndexLength) <
+         (1 << String::kArrayIndexValueBits));
+  // We want the smi-tagged index in key.  kArrayIndexValueMask has zeros in
+  // the low kHashShift bits.
+  STATIC_ASSERT(kSmiTag == 0);
+  Ubfx(hash, hash, String::kHashShift, String::kArrayIndexValueBits);
+  mov(index, Operand(hash, LSL, kSmiTagSize));
+}
+
+
 void MacroAssembler::IntegerToDoubleConversionWithVFP3(Register inReg,
                                                        Register outHighReg,
                                                        Register outLowReg) {
   // ARMv7 VFP3 instructions to implement integer to double conversion.
   mov(r7, Operand(inReg, ASR, kSmiTagSize));
   vmov(s15, r7);
   vcvt_f64_s32(d7, s15);
   vmov(outLowReg, outHighReg, d7);
 }
 
@@ skipping 577 matching lines @@
 
 void CodePatcher::Emit(Address addr) {
   masm()->emit(reinterpret_cast<Instr>(addr));
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM