X64: Optimize access to external references.

src/x64/macro-assembler-x64.h

 // Copyright 2011 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 58 matching lines @@
         scale(scale) {}
   Register reg;
   ScaleFactor scale;
 };
 
 // MacroAssembler implements a collection of frequently used macros.
 class MacroAssembler: public Assembler {
  public:
   MacroAssembler(void* buffer, int size);
 
+  // Prevent the use of the RootArray during the lifetime of this
+  // scope object.
+  class NoRootArrayScope BASE_EMBEDDED {
+   public:
+    explicit NoRootArrayScope(MacroAssembler* assembler)
+        : variable_(&assembler->root_array_available_),
+          old_value_(assembler->root_array_available_) {
+      assembler->root_array_available_ = false;
+    }
+    ~NoRootArrayScope() {
+      *variable_ = old_value_;
+    }
+   private:
+    bool* variable_;
+    bool old_value_;
+  };
+
+  // Operand pointing to an external reference.
+  // May emit code to set up the scratch register. The operand is
+  // only guaranteed to be correct as long as the scratch register
+  // isn't changed.
+  // If the operand is used more than once, use a scratch register
+  // that is guaranteed not to be clobbered.
+  Operand ExternalOperand(ExternalReference reference,
+                          Register scratch = kScratchRegister);
+  // Loads and stores the value of an external reference.
+  // Special case code for load and store to take advantage of
+  // load_rax/store_rax if possible/necessary.
+  // For other operations, just use:
+  //   Operand operand = ExternalOperand(extref);
+  //   operation(operand, ..);
+  void Load(Register destination, ExternalReference source);
+  void Store(ExternalReference destination, Register source);
+  // Loads the address of the external reference into the destination
+  // register.
+  void LoadAddress(Register destination, ExternalReference source);
+  // Returns the size of the code generated by LoadAddress.
+  // Used by CallSize(ExternalReference) to find the size of a call.
+  int LoadAddressSize(ExternalReference source);
+
+  // Operations on roots in the root-array.
   void LoadRoot(Register destination, Heap::RootListIndex index);
+  void StoreRoot(Register source, Heap::RootListIndex index);
   // Load a root value where the index (or part of it) is variable.
   // The variable_offset register is added to the fixed_offset value
   // to get the index into the root-array.
   void LoadRootIndexed(Register destination,
                        Register variable_offset,
                        int fixed_offset);
   void CompareRoot(Register with, Heap::RootListIndex index);
   void CompareRoot(const Operand& with, Heap::RootListIndex index);
   void PushRoot(Heap::RootListIndex index);
-  void StoreRoot(Register source, Heap::RootListIndex index);
 
   // ---------------------------------------------------------------------------
   // GC Support
 
   // For page containing |object| mark region covering |addr| dirty.
   // RecordWriteHelper only works if the object is not in new
   // space.
   void RecordWriteHelper(Register object,
                          Register addr,
                          Register scratch);
@@ skipping 527 matching lines @@
   void Jump(Handle<Code> code_object, RelocInfo::Mode rmode);
 
   void Call(Address destination, RelocInfo::Mode rmode);
   void Call(ExternalReference ext);
   void Call(Handle<Code> code_object, RelocInfo::Mode rmode);
 
   // The size of the code generated for different call instructions.
   int CallSize(Address destination, RelocInfo::Mode rmode) {
     return kCallInstructionLength;
   }
-  int CallSize(ExternalReference ext) {
-    return kCallInstructionLength;
-  }
+  int CallSize(ExternalReference ext);
   int CallSize(Handle<Code> code_object) {
     // Code calls use 32-bit relative addressing.
     return kShortCallInstructionLength;
   }
   int CallSize(Register target) {
     // Opcode: REX_opt FF /2 m64
     return (target.high_bit() != 0) ? 3 : 2;
   }
   int CallSize(const Operand& target) {
     // Opcode: REX_opt FF /2 m64
@@ skipping 367 matching lines @@
   bool allow_stub_calls() { return allow_stub_calls_; }
 
  private:
   // Order general registers are pushed by Pushad.
   // rax, rcx, rdx, rbx, rsi, rdi, r8, r9, r11, r14, r15.
   static int kSafepointPushRegisterIndices[Register::kNumRegisters];
   static const int kNumSafepointSavedRegisters = 11;
 
   bool generating_stub_;
   bool allow_stub_calls_;
+  bool root_array_available_;
 
   // Returns a register holding the smi value. The register MUST NOT be
   // modified. It may be the "smi 1 constant" register.
   Register GetSmiConstant(Smi* value);
 
   // Moves the smi value to the destination register.
   void LoadSmiConstant(Register dst, Smi* value);
 
   // This handle will be patched with the code object on installation.
   Handle<Object> code_object_;
@@ skipping 852 matching lines @@
       Jump(adaptor, RelocInfo::CODE_TARGET);
     }
     bind(&invoke);
   }
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_X64_MACRO_ASSEMBLER_X64_H_