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

src/x64/ic-x64.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 554 matching lines @@
   __ j(zero, index_string);  // The value in hash is used at jump target.
 
   // Is the string a symbol?
   ASSERT(kSymbolTag != 0);
   __ testb(FieldOperand(map, Map::kInstanceTypeOffset),
            Immediate(kIsSymbolMask));
   __ j(zero, not_symbol);
 }
 
 
-// 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. Even if we subsequently go to
-  // the slow case, converting the key to a smi is always valid.
-  // key: string key
-  // hash: key's hash field, including its array index value.
-  __ and_(hash, Immediate(String::kArrayIndexValueMask));
-  __ shr(hash, Immediate(String::kHashShift));
-  // 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.
-  __ Integer32ToSmi(key, hash);
-}
-
 
 void KeyedLoadIC::GenerateGeneric(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
   //  -- rsp[0] : return address
   // -----------------------------------
   Label slow, check_string, index_smi, index_string, property_array_property;
   Label check_pixel_array, probe_dictionary, check_number_dictionary;
 
@@ skipping 126 matching lines @@
 
   __ movq(rcx, FieldOperand(rdx, JSObject::kMapOffset));
   __ movb(rcx, FieldOperand(rcx, Map::kInstanceTypeOffset));
   GenerateGlobalInstanceTypeCheck(masm, rcx, &slow);
 
   GenerateDictionaryLoad(masm, &slow, rbx, rax, rcx, rdi, rax);
   __ IncrementCounter(&Counters::keyed_load_generic_symbol, 1);
   __ ret(0);
 
   __ bind(&index_string);
-  GenerateIndexFromHash(masm, rax, rbx);
+  __ IndexFromHash(rbx, rax);
   __ jmp(&index_smi);
 }
 
 
 void KeyedLoadIC::GenerateString(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rax    : key
   //  -- rdx    : receiver
   //  -- rsp[0] : return address
   // -----------------------------------
@@ skipping 835 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, rcx, rbx);
+  __ IndexFromHash(rbx, rcx);
   // 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 -------------
   // rcx                      : function name
   // rsp[0]                   : return address
   // rsp[8]                   : argument argc
@@ skipping 305 matching lines @@
   GenerateMiss(masm);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64