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

src/ia32/ic-ia32.cc

 // Copyright 2010 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 501 matching lines @@
   __ test(hash, Immediate(String::kContainsCachedArrayIndexMask));
   __ j(zero, index_string, not_taken);
 
   // Is the string a symbol?
   ASSERT(kSymbolTag != 0);
   __ test_b(FieldOperand(map, Map::kInstanceTypeOffset), kIsSymbolMask);
   __ j(zero, not_symbol, not_taken);
 }
 
 
-// Picks out an array index from the hash field.
-static void GenerateIndexFromHash(MacroAssembler* masm,
-                                  Register key,
-                                  Register hash) {
-  // Register use:
-  //   key - holds the overwritten key on exit.
-  //   hash - holds the key's hash. Clobbered.
-
-  // 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.
-  ASSERT(String::kHashShift >= kSmiTagSize);
-  __ and_(hash, String::kArrayIndexValueMask);
-  __ shr(hash, String::kHashShift - kSmiTagSize);
-  // Here we actually clobber the key which will be used if calling into
-  // runtime later. However as the new key is the numeric value of a string key
-  // there is no difference in using either key.
-  __ mov(key, hash);
-}
-
-
 void KeyedLoadIC::GenerateGeneric(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- eax    : key
   //  -- edx    : receiver
   //  -- esp[0] : return address
   // -----------------------------------
   Label slow, check_string, index_smi, index_string, property_array_property;
   Label check_pixel_array, probe_dictionary, check_number_dictionary;
 
   // Check that the key is a smi.
@@ skipping 140 matching lines @@
 
   __ mov(ecx, FieldOperand(edx, JSObject::kMapOffset));
   __ movzx_b(ecx, FieldOperand(ecx, Map::kInstanceTypeOffset));
   GenerateGlobalInstanceTypeCheck(masm, ecx, &slow);
 
   GenerateDictionaryLoad(masm, &slow, ebx, eax, ecx, edi, eax);
   __ IncrementCounter(&Counters::keyed_load_generic_symbol, 1);
   __ ret(0);
 
   __ bind(&index_string);
-  GenerateIndexFromHash(masm, eax, ebx);
+  __ IndexFromHash(ebx, eax);
   // Now jump to the place where smi keys are handled.
   __ jmp(&index_smi);
 }
 
 
 void KeyedLoadIC::GenerateString(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- eax    : key (index)
   //  -- edx    : receiver
   //  -- esp[0] : return address
@@ skipping 840 matching lines @@
   // This branch is taken if:
   // - the receiver requires boxing or access check,
   // - the key is neither smi nor symbol,
   // - the value loaded is not a function,
   // - there is hope that the runtime will create a monomorphic call stub
   //   that will get fetched next time.
   __ IncrementCounter(&Counters::keyed_call_generic_slow, 1);
   GenerateMiss(masm, argc);
 
   __ bind(&index_string);
-  GenerateIndexFromHash(masm, ecx, ebx);
+  __ IndexFromHash(ebx, ecx);
   // Now jump to the place where smi keys are handled.
   __ jmp(&index_smi);
 }
 
 
 void KeyedCallIC::GenerateNormal(MacroAssembler* masm, int argc) {
   // ----------- S t a t e -------------
   //  -- ecx                 : name
   //  -- esp[0]              : return address
   //  -- esp[(argc - n) * 4] : arg[n] (zero-based)
@@ skipping 399 matching lines @@
   ExternalReference ref = ExternalReference(IC_Utility(kKeyedStoreIC_Miss));
   __ TailCallExternalReference(ref, 3, 1);
 }
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32