Improve performance of arguments object allocation by taking...

src/codegen-arm.cc

 // Copyright 2006-2008 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 569 matching lines @@
     }
 
     // Store the arguments object.
     // This must happen after context initialization because
     // the arguments array may be stored in the context!
     if (scope->arguments() != NULL) {
       ASSERT(scope->arguments_shadow() != NULL);
       Comment cmnt(masm_, "[ allocate arguments object");
       { Reference shadow_ref(this, scope->arguments_shadow());
         { Reference arguments_ref(this, scope->arguments());
-          __ ldr(r0, FunctionOperand());
-          __ push(r0);
-          __ CallRuntime(Runtime::kNewArguments, 1);
+          ArgumentsAccessStub stub(ArgumentsAccessStub::NEW_OBJECT);
+          __ ldr(r2, FunctionOperand());
+          __ add(r1, fp, Operand((2 + scope->num_parameters()) * kPointerSize));

[Mads Ager (chromium), 2008/10/06 06:05:59]

Could you add a comment to say what the constant 2 is used to skip? 

+          __ mov(r0, Operand(Smi::FromInt(scope->num_parameters())));
+          __ stm(db_w, sp, r0.bit() | r1.bit() | r2.bit());
+          __ CallStub(&stub);
           __ push(r0);
           SetValue(&arguments_ref);
         }
         SetValue(&shadow_ref);
       }
       __ pop(r0);  // Value is no longer needed.
     }
 
     // Generate code to 'execute' declarations and initialize
     // functions (source elements). In case of an illegal
@@ skipping 353 matching lines @@
 #ifdef DEBUG
   void Print() {
     PrintF("InvokeBuiltinStub (kind %d, argc, %d)\n",
            static_cast<int>(kind_),
            argc_);
   }
 #endif
 };
 
 
-class ArgumentsAccessStub: public CodeStub {
- public:
-  explicit ArgumentsAccessStub(bool is_length) : is_length_(is_length) { }
-
- private:
-  bool is_length_;
-
-  Major MajorKey() { return ArgumentsAccess; }
-  int MinorKey() { return is_length_ ? 1 : 0; }
-  void Generate(MacroAssembler* masm);
-
-  const char* GetName() { return "ArgumentsAccessStub"; }
-
-#ifdef DEBUG
-  void Print() {
-    PrintF("ArgumentsAccessStub (is_length %s)\n",
-           is_length_ ? "true" : "false");
-  }
-#endif
-};
-
-
 void ArmCodeGenerator::GetReferenceProperty(Expression* key) {
   ASSERT(!ref()->is_illegal());
   Reference::Type type = ref()->type();
 
   // TODO(1241834): Make sure that this it is safe to ignore the distinction
   // between access types LOAD and LOAD_TYPEOF_EXPR. If there is a chance
   // that reference errors can be thrown below, we must distinguish between
   // the two kinds of loads (typeof expression loads must not throw a
   // reference error).
   if (type == Reference::NAMED) {
@@ skipping 1852 matching lines @@
 
 
 void ArmCodeGenerator::GenerateArgumentsLength(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 0);
 
   // Seed the result with the formal parameters count, which will be used
   // in case no arguments adaptor frame is found below the current frame.
   __ mov(r0, Operand(Smi::FromInt(scope_->num_parameters())));
 
   // Call the shared stub to get to the arguments.length.
-  ArgumentsAccessStub stub(true);
+  ArgumentsAccessStub stub(ArgumentsAccessStub::READ_LENGTH);
   __ CallStub(&stub);
   __ push(r0);
 }
 
 
 void ArmCodeGenerator::GenerateArgumentsAccess(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 1);
 
   // Satisfy contract with ArgumentsAccessStub:
   // Load the key into r1 and the formal parameters count into r0.
   Load(args->at(0));
   __ pop(r1);
   __ mov(r0, Operand(Smi::FromInt(scope_->num_parameters())));
 
   // Call the shared stub to get to arguments[key].
-  ArgumentsAccessStub stub(false);
+  ArgumentsAccessStub stub(ArgumentsAccessStub::READ_ELEMENT);
   __ CallStub(&stub);
   __ push(r0);
 }
 
 
 void ArmCodeGenerator::GenerateObjectEquals(ZoneList<Expression*>* args) {
   ASSERT(args->length() == 2);
 
   // Load the two objects into registers and perform the comparison.
   Load(args->at(0));
@@ skipping 1532 matching lines @@
 }
 
 
 void ArgumentsAccessStub::Generate(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  -- r0: formal number of parameters for the calling function
   //  -- r1: key (if value access)
   //  -- lr: return address
   // -----------------------------------
 
-  // Check that the key is a smi for non-length accesses.
+  // If we're reading an element we need to check that the key is a smi.
   Label slow;
-  if (!is_length_) {
+  if (type_ == READ_ELEMENT) {
     __ tst(r1, Operand(kSmiTagMask));
     __ b(ne, &slow);
   }
 
   // Check if the calling frame is an arguments adaptor frame.
   // r0: formal number of parameters
   // r1: key (if access)
   Label adaptor;
   __ ldr(r2, MemOperand(fp, StandardFrameConstants::kCallerFPOffset));
   __ ldr(r3, MemOperand(r2, StandardFrameConstants::kContextOffset));
   __ cmp(r3, Operand(ArgumentsAdaptorFrame::SENTINEL));
-  __ b(eq, &adaptor);
+  if (type_ == NEW_OBJECT) {
+    __ b(ne, &slow);
+  } else {
+    __ b(eq, &adaptor);
+  }
 
   static const int kParamDisplacement =
       StandardFrameConstants::kCallerSPOffset - kPointerSize;
 
-  if (is_length_) {
-    // Nothing to do: the formal length of parameters has been passed in r0
-    // by the calling function.
-  } else {
+  if (type_ == READ_LENGTH) {
+    // Nothing to do: The formal number of parameters has already been
+    // passed in register r0 by calling function. Just return it.
+    __ mov(pc, lr);
+  } else if (type_ == READ_ELEMENT) {
     // Check index against formal parameter count. Use unsigned comparison to
     // get the negative check for free.
     // r0: formal number of parameters
     // r1: index
     __ cmp(r1, r0);
     __ b(cs, &slow);
 
-    // Read the argument from the current frame.
+    // Read the argument from the current frame and return it.
     __ sub(r3, r0, r1);
     __ add(r3, fp, Operand(r3, LSL, kPointerSizeLog2 - kSmiTagSize));
     __ ldr(r0, MemOperand(r3, kParamDisplacement));
+    __ mov(pc, lr);
+  } else {
+    ASSERT(type_ == NEW_OBJECT);
+    // Do nothing here.
   }
 
-  // Return to the calling function.
-  __ mov(pc, lr);
-
   // An arguments adaptor frame is present. Find the length or the actual
   // argument in the calling frame.
   // r0: formal number of parameters
   // r1: key
   // r2: adaptor frame pointer
   __ bind(&adaptor);
   // Read the arguments length from the adaptor frame. This is the result if
   // only accessing the length, otherwise it is used in accessing the value
   __ ldr(r0, MemOperand(r2, ArgumentsAdaptorFrameConstants::kLengthOffset));
 
-  if (!is_length_) {
+  if (type_ == READ_LENGTH) {
+    // Return the length in r0.
+    __ mov(pc, lr);
+  } else if (type_ == READ_ELEMENT) {
     // Check index against actual arguments count. Use unsigned comparison to
     // get the negative check for free.
     // r0: actual number of parameter
     // r1: index
     // r2: adaptor frame point
     __ cmp(r1, r0);
     __ b(cs, &slow);
 
-    // Read the argument from the adaptor frame.
+    // Read the argument from the adaptor frame and return it.
     __ sub(r3, r0, r1);
     __ add(r3, r2, Operand(r3, LSL, kPointerSizeLog2 - kSmiTagSize));
     __ ldr(r0, MemOperand(r3, kParamDisplacement));
+    __ mov(pc, lr);
+  } else {
+    ASSERT(type_ == NEW_OBJECT);
+    // Patch the arguments.length and the parameters pointer.
+    __ str(r0, MemOperand(sp, 0 * kPointerSize));
+    __ add(r3, r2, Operand(r0, LSL, kPointerSizeLog2 - kSmiTagSize));
+    __ add(r3, r3, Operand(kParamDisplacement + 1 * kPointerSize));
+    __ str(r3, MemOperand(sp, 1 * kPointerSize));
+    __ bind(&slow);
+    __ TailCallRuntime(ExternalReference(Runtime::kNewArgumentsFast), 3);
   }
 
   // Return to the calling function.
-  __ mov(pc, lr);
-
-  if (!is_length_) {
+  if (type_ == READ_ELEMENT) {
     __ bind(&slow);
     __ push(r1);
     __ TailCallRuntime(ExternalReference(Runtime::kGetArgumentsProperty), 1);
   }
 }
 
 
 void ArmCodeGenerator::SetReferenceProperty(CodeGenerator* cgen,
                                             Reference* ref,
                                             Expression* key) {
@@ skipping 65 matching lines @@
                                      bool is_eval) {
   Handle<Code> code = ArmCodeGenerator::MakeCode(fun, script, is_eval);
   if (!code.is_null()) {
     Counters::total_compiled_code_size.Increment(code->instruction_size());
   }
   return code;
 }
 
 
 } }  // namespace v8::internal