ARM: Add more logic to the generic keyed load stub...

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 335 matching lines @@
 }
 
 
 void KeyedLoadIC::GenerateGeneric(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rsp[0] : return address
   //  -- rsp[8] : name
   //  -- rsp[16] : receiver
   // -----------------------------------
   Label slow, check_string, index_smi, index_string;
-  Label check_pixel_array, probe_dictionary;
-  Label check_number_dictionary;
+  Label check_pixel_array, probe_dictionary, check_number_dictionary;
 
   // Load name and receiver.
   __ movq(rax, Operand(rsp, kPointerSize));
   __ movq(rcx, Operand(rsp, 2 * kPointerSize));
 
   // Check that the object isn't a smi.
   __ JumpIfSmi(rcx, &slow);
 
   // Check that the object is some kind of JS object EXCEPT JS Value type.
   // In the case that the object is a value-wrapper object,
   // we enter the runtime system to make sure that indexing
   // into string objects work as intended.
   ASSERT(JS_OBJECT_TYPE > JS_VALUE_TYPE);
   __ CmpObjectType(rcx, JS_OBJECT_TYPE, rdx);
   __ j(below, &slow);
 
   // Check bit field.
   __ testb(FieldOperand(rdx, Map::kBitFieldOffset),
            Immediate(kSlowCaseBitFieldMask));
   __ j(not_zero, &slow);
 
   // Check that the key is a smi.
   __ JumpIfNotSmi(rax, &check_string);
-
-  // Get the elements array of the object.
   __ bind(&index_smi);
+  // Now the key is known to be a smi. This place is also jumped to from below
+  // where a numeric string is converted to a smi.
   __ movq(rcx, FieldOperand(rcx, JSObject::kElementsOffset));
   // Check that the object is in fast mode (not dictionary).
   __ CompareRoot(FieldOperand(rcx, HeapObject::kMapOffset),
                  Heap::kFixedArrayMapRootIndex);
   __ j(not_equal, &check_pixel_array);
   // Check that the key (index) is within bounds.
   __ SmiCompare(rax, FieldOperand(rcx, FixedArray::kLengthOffset));
   __ j(above_equal, &slow);  // Unsigned comparison rejects negative indices.
   // Fast case: Do the load.
   SmiIndex index = masm->SmiToIndex(rax, rax, kPointerSizeLog2);
@@ skipping 41 matching lines @@
   __ bind(&check_string);
   // The key is not a smi.
   // Is it a string?
   __ CmpObjectType(rax, FIRST_NONSTRING_TYPE, rdx);
   __ j(above_equal, &slow);
   // Is the string an array index, with cached numeric value?
   __ movl(rbx, FieldOperand(rax, String::kHashFieldOffset));
   __ testl(rbx, Immediate(String::kIsArrayIndexMask));
 
   // Is the string a symbol?
+  // rcx: key map.
   __ j(not_zero, &index_string);  // The value in rbx is used at jump target.
   ASSERT(kSymbolTag != 0);
   __ testb(FieldOperand(rdx, Map::kInstanceTypeOffset),
            Immediate(kIsSymbolMask));
   __ j(zero, &slow);
 
   // If the receiver is a fast-case object, check the keyed lookup
   // cache. Otherwise probe the dictionary leaving result in rcx.
   __ movq(rbx, FieldOperand(rcx, JSObject::kPropertiesOffset));
   __ Cmp(FieldOperand(rbx, HeapObject::kMapOffset), Factory::hash_table_map());
@@ skipping 30 matching lines @@
   __ movl(rax, Operand(kScratchRegister, rdx, times_4, 0));
   __ movzxbq(rdx, FieldOperand(rbx, Map::kInObjectPropertiesOffset));
   __ cmpq(rax, rdx);
   __ j(above_equal, &slow);
 
   // Load in-object property.
   __ subq(rax, rdx);
   __ movzxbq(rdx, FieldOperand(rbx, Map::kInstanceSizeOffset));
   __ addq(rax, rdx);
   __ movq(rax, FieldOperand(rcx, rax, times_pointer_size, 0));
+  __ IncrementCounter(&Counters::keyed_load_generic_lookup_cache, 1);
   __ ret(0);
 
   // Do a quick inline probe of the receiver's dictionary, if it
   // exists.
   __ bind(&probe_dictionary);
   GenerateDictionaryLoad(masm,
                          &slow,
                          rbx,
                          rcx,
                          rdx,
                          rax,
                          rdi,
                          DICTIONARY_CHECK_DONE);
   __ movq(rax, rcx);
   __ IncrementCounter(&Counters::keyed_load_generic_symbol, 1);
   __ ret(0);
   // 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));
   __ bind(&index_string);
   // We want the smi-tagged index in rax.
+  // rax: key (string).
+  // rbx: hash field.
+  // rdx: receiver.
   __ and_(rbx, Immediate(String::kArrayIndexValueMask));
   __ shr(rbx, Immediate(String::kHashShift));
+  // Here we actually clobber the key (rax) 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(rax, rbx);
+  // Now jump to the place where smi keys are handled.
   __ jmp(&index_smi);
 }
 
 
 void KeyedLoadIC::GenerateString(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- rsp[0] : return address
   //  -- rsp[8] : name (index)
   //  -- rsp[16] : receiver
   // -----------------------------------
@@ skipping 1040 matching lines @@
   GenerateMiss(masm);
 }
 
 
 #undef __
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64