Remove %_SwapElements. This inlined runtime contained an optimization that was dangerous in the pr…

src/x64/full-codegen-x64.cc

 // Copyright 2012 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 3342 matching lines @@
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT(args->length() == 3);
   VisitForStackValue(args->at(0));
   VisitForStackValue(args->at(1));
   VisitForStackValue(args->at(2));
   __ CallStub(&stub);
   context()->Plug(rax);
 }
 
 
-void FullCodeGenerator::EmitSwapElements(CallRuntime* expr) {
-  ZoneList<Expression*>* args = expr->arguments();
-  ASSERT(args->length() == 3);
-  VisitForStackValue(args->at(0));
-  VisitForStackValue(args->at(1));
-  VisitForStackValue(args->at(2));
-  Label done;
-  Label slow_case;
-  Register object = rax;
-  Register index_1 = rbx;
-  Register index_2 = rcx;
-  Register elements = rdi;
-  Register temp = rdx;
-  __ movq(object, Operand(rsp, 2 * kPointerSize));
-  // Fetch the map and check if array is in fast case.
-  // Check that object doesn't require security checks and
-  // has no indexed interceptor.
-  __ CmpObjectType(object, JS_ARRAY_TYPE, temp);
-  __ j(not_equal, &slow_case);
-  __ testb(FieldOperand(temp, Map::kBitFieldOffset),
-           Immediate(KeyedLoadIC::kSlowCaseBitFieldMask));
-  __ j(not_zero, &slow_case);
-
-  // Check the object's elements are in fast case and writable.
-  __ movq(elements, FieldOperand(object, JSObject::kElementsOffset));
-  __ CompareRoot(FieldOperand(elements, HeapObject::kMapOffset),
-                 Heap::kFixedArrayMapRootIndex);
-  __ j(not_equal, &slow_case);
-
-  // Check that both indices are smis.
-  __ movq(index_1, Operand(rsp, 1 * kPointerSize));
-  __ movq(index_2, Operand(rsp, 0 * kPointerSize));
-  __ JumpIfNotBothSmi(index_1, index_2, &slow_case);
-
-  // Check that both indices are valid.
-  // The JSArray length field is a smi since the array is in fast case mode.
-  __ movq(temp, FieldOperand(object, JSArray::kLengthOffset));
-  __ SmiCompare(temp, index_1);
-  __ j(below_equal, &slow_case);
-  __ SmiCompare(temp, index_2);
-  __ j(below_equal, &slow_case);
-
-  __ SmiToInteger32(index_1, index_1);
-  __ SmiToInteger32(index_2, index_2);
-  // Bring addresses into index1 and index2.
-  __ lea(index_1, FieldOperand(elements, index_1, times_pointer_size,
-                               FixedArray::kHeaderSize));
-  __ lea(index_2, FieldOperand(elements, index_2, times_pointer_size,
-                               FixedArray::kHeaderSize));
-
-  // Swap elements.  Use object and temp as scratch registers.
-  __ movq(object, Operand(index_1, 0));
-  __ movq(temp,   Operand(index_2, 0));
-  __ movq(Operand(index_2, 0), object);
-  __ movq(Operand(index_1, 0), temp);
-
-  Label no_remembered_set;
-  __ CheckPageFlag(elements,
-                   temp,
-                   1 << MemoryChunk::SCAN_ON_SCAVENGE,
-                   not_zero,
-                   &no_remembered_set,
-                   Label::kNear);
-  // Possible optimization: do a check that both values are Smis
-  // (or them and test against Smi mask.)
-
-  // We are swapping two objects in an array and the incremental marker never
-  // pauses in the middle of scanning a single object.  Therefore the
-  // incremental marker is not disturbed, so we don't need to call the
-  // RecordWrite stub that notifies the incremental marker.
-  __ RememberedSetHelper(elements,
-                         index_1,
-                         temp,
-                         kDontSaveFPRegs,
-                         MacroAssembler::kFallThroughAtEnd);
-  __ RememberedSetHelper(elements,
-                         index_2,
-                         temp,
-                         kDontSaveFPRegs,
-                         MacroAssembler::kFallThroughAtEnd);
-
-  __ bind(&no_remembered_set);
-
-  // We are done. Drop elements from the stack, and return undefined.
-  __ addq(rsp, Immediate(3 * kPointerSize));
-  __ LoadRoot(rax, Heap::kUndefinedValueRootIndex);
-  __ jmp(&done);
-
-  __ bind(&slow_case);
-  __ CallRuntime(Runtime::kSwapElements, 3);
-
-  __ bind(&done);
-  context()->Plug(rax);
-}
-
-
 void FullCodeGenerator::EmitGetFromCache(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   ASSERT_EQ(2, args->length());
 
   ASSERT_NE(NULL, args->at(0)->AsLiteral());
   int cache_id = Smi::cast(*(args->at(0)->AsLiteral()->handle()))->value();
 
   Handle<FixedArray> jsfunction_result_caches(
       isolate()->global_context()->jsfunction_result_caches());
   if (jsfunction_result_caches->length() <= cache_id) {
@@ skipping 1130 matching lines @@
   *context_length = 0;
   return previous_;
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64