Remove some dead code.

src/arm/virtual-frame-arm.h

-// Copyright 2009 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
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#ifndef V8_ARM_VIRTUAL_FRAME_ARM_H_
-#define V8_ARM_VIRTUAL_FRAME_ARM_H_
-
-#include "register-allocator.h"
-
-namespace v8 {
-namespace internal {
-
-// This dummy class is only used to create invalid virtual frames.
-extern class InvalidVirtualFrameInitializer {}* kInvalidVirtualFrameInitializer;
-
-
-// -------------------------------------------------------------------------
-// Virtual frames
-//
-// The virtual frame is an abstraction of the physical stack frame.  It
-// encapsulates the parameters, frame-allocated locals, and the expression
-// stack.  It supports push/pop operations on the expression stack, as well
-// as random access to the expression stack elements, locals, and
-// parameters.
-
-class VirtualFrame : public ZoneObject {
- public:
-  class RegisterAllocationScope;
-  // A utility class to introduce a scope where the virtual frame is
-  // expected to remain spilled.  The constructor spills the code
-  // generator's current frame, and keeps it spilled.
-  class SpilledScope BASE_EMBEDDED {
-   public:
-    explicit SpilledScope(VirtualFrame* frame)
-      : old_is_spilled_(
-          Isolate::Current()->is_virtual_frame_in_spilled_scope()) {
-      if (frame != NULL) {
-        if (!old_is_spilled_) {
-          frame->SpillAll();
-        } else {
-          frame->AssertIsSpilled();
-        }
-      }
-      Isolate::Current()->set_is_virtual_frame_in_spilled_scope(true);
-    }
-    ~SpilledScope() {
-      Isolate::Current()->set_is_virtual_frame_in_spilled_scope(
-          old_is_spilled_);
-    }
-    static bool is_spilled() {
-      return Isolate::Current()->is_virtual_frame_in_spilled_scope();
-    }
-
-   private:
-    int old_is_spilled_;
-
-    SpilledScope() { }
-
-    friend class RegisterAllocationScope;
-  };
-
-  class RegisterAllocationScope BASE_EMBEDDED {
-   public:
-    // A utility class to introduce a scope where the virtual frame
-    // is not spilled, ie. where register allocation occurs.  Eventually
-    // when RegisterAllocationScope is ubiquitous it can be removed
-    // along with the (by then unused) SpilledScope class.
-    inline explicit RegisterAllocationScope(CodeGenerator* cgen);
-    inline ~RegisterAllocationScope();
-
-   private:
-    CodeGenerator* cgen_;
-    bool old_is_spilled_;
-
-    RegisterAllocationScope() { }
-  };
-
-  // An illegal index into the virtual frame.
-  static const int kIllegalIndex = -1;
-
-  // Construct an initial virtual frame on entry to a JS function.
-  inline VirtualFrame();
-
-  // Construct an invalid virtual frame, used by JumpTargets.
-  inline VirtualFrame(InvalidVirtualFrameInitializer* dummy);
-
-  // Construct a virtual frame as a clone of an existing one.
-  explicit inline VirtualFrame(VirtualFrame* original);
-
-  inline CodeGenerator* cgen() const;
-  inline MacroAssembler* masm();
-
-  // The number of elements on the virtual frame.
-  int element_count() const { return element_count_; }
-
-  // The height of the virtual expression stack.
-  inline int height() const;
-
-  bool is_used(int num) {
-    switch (num) {
-      case 0: {  // r0.
-        return kR0InUse[top_of_stack_state_];
-      }
-      case 1: {  // r1.
-        return kR1InUse[top_of_stack_state_];
-      }
-      case 2:
-      case 3:
-      case 4:
-      case 5:
-      case 6: {  // r2 to r6.
-        ASSERT(num - kFirstAllocatedRegister < kNumberOfAllocatedRegisters);
-        ASSERT(num >= kFirstAllocatedRegister);
-        if ((register_allocation_map_ &
-             (1 << (num - kFirstAllocatedRegister))) == 0) {
-          return false;
-        } else {
-          return true;
-        }
-      }
-      default: {
-        ASSERT(num < kFirstAllocatedRegister ||
-               num >= kFirstAllocatedRegister + kNumberOfAllocatedRegisters);
-        return false;
-      }
-    }
-  }
-
-  // Add extra in-memory elements to the top of the frame to match an actual
-  // frame (eg, the frame after an exception handler is pushed).  No code is
-  // emitted.
-  void Adjust(int count);
-
-  // Forget elements from the top of the frame to match an actual frame (eg,
-  // the frame after a runtime call).  No code is emitted except to bring the
-  // frame to a spilled state.
-  void Forget(int count);
-
-  // Spill all values from the frame to memory.
-  void SpillAll();
-
-  void AssertIsSpilled() const {
-    ASSERT(top_of_stack_state_ == NO_TOS_REGISTERS);
-    ASSERT(register_allocation_map_ == 0);
-  }
-
-  void AssertIsNotSpilled() {
-    ASSERT(!SpilledScope::is_spilled());
-  }
-
-  // Spill all occurrences of a specific register from the frame.
-  void Spill(Register reg) {
-    UNIMPLEMENTED();
-  }
-
-  // Spill all occurrences of an arbitrary register if possible.  Return the
-  // register spilled or no_reg if it was not possible to free any register
-  // (ie, they all have frame-external references).  Unimplemented.
-  Register SpillAnyRegister();
-
-  // Make this virtual frame have a state identical to an expected virtual
-  // frame.  As a side effect, code may be emitted to make this frame match
-  // the expected one.
-  void MergeTo(VirtualFrame* expected, Condition cond = al);
-  void MergeTo(const VirtualFrame* expected, Condition cond = al);
-
-  // Checks whether this frame can be branched to by the other frame.
-  bool IsCompatibleWith(const VirtualFrame* other) const {
-    return (tos_known_smi_map_ & (~other->tos_known_smi_map_)) == 0;
-  }
-
-  inline void ForgetTypeInfo() {
-    tos_known_smi_map_ = 0;
-  }
-
-  // Detach a frame from its code generator, perhaps temporarily.  This
-  // tells the register allocator that it is free to use frame-internal
-  // registers.  Used when the code generator's frame is switched from this
-  // one to NULL by an unconditional jump.
-  void DetachFromCodeGenerator() {
-  }
-
-  // (Re)attach a frame to its code generator.  This informs the register
-  // allocator that the frame-internal register references are active again.
-  // Used when a code generator's frame is switched from NULL to this one by
-  // binding a label.
-  void AttachToCodeGenerator() {
-  }
-
-  // Emit code for the physical JS entry and exit frame sequences.  After
-  // calling Enter, the virtual frame is ready for use; and after calling
-  // Exit it should not be used.  Note that Enter does not allocate space in
-  // the physical frame for storing frame-allocated locals.
-  void Enter();
-  void Exit();
-
-  // Prepare for returning from the frame by elements in the virtual frame. This
-  // avoids generating unnecessary merge code when jumping to the
-  // shared return site. No spill code emitted. Value to return should be in r0.
-  inline void PrepareForReturn();
-
-  // Number of local variables after when we use a loop for allocating.
-  static const int kLocalVarBound = 5;
-
-  // Allocate and initialize the frame-allocated locals.
-  void AllocateStackSlots();
-
-  // The current top of the expression stack as an assembly operand.
-  MemOperand Top() {
-    AssertIsSpilled();
-    return MemOperand(sp, 0);
-  }
-
-  // An element of the expression stack as an assembly operand.
-  MemOperand ElementAt(int index) {
-    int adjusted_index = index - kVirtualElements[top_of_stack_state_];
-    ASSERT(adjusted_index >= 0);
-    return MemOperand(sp, adjusted_index * kPointerSize);
-  }
-
-  bool KnownSmiAt(int index) {
-    if (index >= kTOSKnownSmiMapSize) return false;
-    return (tos_known_smi_map_ & (1 << index)) != 0;
-  }
-
-  // A frame-allocated local as an assembly operand.
-  inline MemOperand LocalAt(int index);
-
-  // Push the address of the receiver slot on the frame.
-  void PushReceiverSlotAddress();
-
-  // The function frame slot.
-  MemOperand Function() { return MemOperand(fp, kFunctionOffset); }
-
-  // The context frame slot.
-  MemOperand Context() { return MemOperand(fp, kContextOffset); }
-
-  // A parameter as an assembly operand.
-  inline MemOperand ParameterAt(int index);
-
-  // The receiver frame slot.
-  inline MemOperand Receiver();
-
-  // Push a try-catch or try-finally handler on top of the virtual frame.
-  void PushTryHandler(HandlerType type);
-
-  // Call stub given the number of arguments it expects on (and
-  // removes from) the stack.
-  inline void CallStub(CodeStub* stub, int arg_count);
-
-  // Call JS function from top of the stack with arguments
-  // taken from the stack.
-  void CallJSFunction(int arg_count);
-
-  // Call runtime given the number of arguments expected on (and
-  // removed from) the stack.
-  void CallRuntime(const Runtime::Function* f, int arg_count);
-  void CallRuntime(Runtime::FunctionId id, int arg_count);
-
-#ifdef ENABLE_DEBUGGER_SUPPORT
-  void DebugBreak();
-#endif
-
-  // Invoke builtin given the number of arguments it expects on (and
-  // removes from) the stack.
-  void InvokeBuiltin(Builtins::JavaScript id,
-                     InvokeJSFlags flag,
-                     int arg_count);
-
-  // Call load IC. Receiver is on the stack and is consumed. Result is returned
-  // in r0.
-  void CallLoadIC(Handle<String> name, RelocInfo::Mode mode);
-
-  // Call store IC. If the load is contextual, value is found on top of the
-  // frame. If not, value and receiver are on the frame. Both are consumed.
-  // Result is returned in r0.
-  void CallStoreIC(Handle<String> name, bool is_contextual,
-                   StrictModeFlag strict_mode);
-
-  // Call keyed load IC. Key and receiver are on the stack. Both are consumed.
-  // Result is returned in r0.
-  void CallKeyedLoadIC();
-
-  // Call keyed store IC. Value, key and receiver are on the stack. All three
-  // are consumed. Result is returned in r0.
-  void CallKeyedStoreIC(StrictModeFlag strict_mode);
-
-  // Call into an IC stub given the number of arguments it removes
-  // from the stack.  Register arguments to the IC stub are implicit,
-  // and depend on the type of IC stub.
-  void CallCodeObject(Handle<Code> ic,
-                      RelocInfo::Mode rmode,
-                      int dropped_args);
-
-  // Drop a number of elements from the top of the expression stack.  May
-  // emit code to affect the physical frame.  Does not clobber any registers
-  // excepting possibly the stack pointer.
-  void Drop(int count);
-
-  // Drop one element.
-  void Drop() { Drop(1); }
-
-  // Pop an element from the top of the expression stack.  Discards
-  // the result.
-  void Pop();
-
-  // Pop an element from the top of the expression stack.  The register
-  // will be one normally used for the top of stack register allocation
-  // so you can't hold on to it if you push on the stack.
-  Register PopToRegister(Register but_not_to_this_one = no_reg);
-
-  // Look at the top of the stack.  The register returned is aliased and
-  // must be copied to a scratch register before modification.
-  Register Peek();
-
-  // Look at the value beneath the top of the stack.  The register returned is
-  // aliased and must be copied to a scratch register before modification.
-  Register Peek2();
-
-  // Duplicate the top of stack.
-  void Dup();
-
-  // Duplicate the two elements on top of stack.
-  void Dup2();
-
-  // Flushes all registers, but it puts a copy of the top-of-stack in r0.
-  void SpillAllButCopyTOSToR0();
-
-  // Flushes all registers, but it puts a copy of the top-of-stack in r1.
-  void SpillAllButCopyTOSToR1();
-
-  // Flushes all registers, but it puts a copy of the top-of-stack in r1
-  // and the next value on the stack in r0.
-  void SpillAllButCopyTOSToR1R0();
-
-  // Pop and save an element from the top of the expression stack and
-  // emit a corresponding pop instruction.
-  void EmitPop(Register reg);
-
-  // Takes the top two elements and puts them in r0 (top element) and r1
-  // (second element).
-  void PopToR1R0();
-
-  // Takes the top element and puts it in r1.
-  void PopToR1();
-
-  // Takes the top element and puts it in r0.
-  void PopToR0();
-
-  // Push an element on top of the expression stack and emit a
-  // corresponding push instruction.
-  void EmitPush(Register reg, TypeInfo type_info = TypeInfo::Unknown());
-  void EmitPush(Operand operand, TypeInfo type_info = TypeInfo::Unknown());
-  void EmitPush(MemOperand operand, TypeInfo type_info = TypeInfo::Unknown());
-  void EmitPushRoot(Heap::RootListIndex index);
-
-  // Overwrite the nth thing on the stack.  If the nth position is in a
-  // register then this turns into a mov, otherwise an str.  Afterwards
-  // you can still use the register even if it is a register that can be
-  // used for TOS (r0 or r1).
-  void SetElementAt(Register reg, int this_far_down);
-
-  // Get a register which is free and which must be immediately used to
-  // push on the top of the stack.
-  Register GetTOSRegister();
-
-  // Push multiple registers on the stack and the virtual frame
-  // Register are selected by setting bit in src_regs and
-  // are pushed in decreasing order: r15 .. r0.
-  void EmitPushMultiple(int count, int src_regs);
-
-  static Register scratch0() { return r7; }
-  static Register scratch1() { return r9; }
-
- private:
-  static const int kLocal0Offset = JavaScriptFrameConstants::kLocal0Offset;
-  static const int kFunctionOffset = JavaScriptFrameConstants::kFunctionOffset;
-  static const int kContextOffset = StandardFrameConstants::kContextOffset;
-
-  static const int kHandlerSize = StackHandlerConstants::kSize / kPointerSize;
-  static const int kPreallocatedElements = 5 + 8;  // 8 expression stack slots.
-
-  // 5 states for the top of stack, which can be in memory or in r0 and r1.
-  enum TopOfStack {
-    NO_TOS_REGISTERS,
-    R0_TOS,
-    R1_TOS,
-    R1_R0_TOS,
-    R0_R1_TOS,
-    TOS_STATES
-  };
-
-  static const int kMaxTOSRegisters = 2;
-
-  static const bool kR0InUse[TOS_STATES];
-  static const bool kR1InUse[TOS_STATES];
-  static const int kVirtualElements[TOS_STATES];
-  static const TopOfStack kStateAfterPop[TOS_STATES];
-  static const TopOfStack kStateAfterPush[TOS_STATES];
-  static const Register kTopRegister[TOS_STATES];
-  static const Register kBottomRegister[TOS_STATES];
-
-  // We allocate up to 5 locals in registers.
-  static const int kNumberOfAllocatedRegisters = 5;
-  // r2 to r6 are allocated to locals.
-  static const int kFirstAllocatedRegister = 2;
-
-  static const Register kAllocatedRegisters[kNumberOfAllocatedRegisters];
-
-  static Register AllocatedRegister(int r) {
-    ASSERT(r >= 0 && r < kNumberOfAllocatedRegisters);
-    return kAllocatedRegisters[r];
-  }
-
-  // The number of elements on the stack frame.
-  int element_count_;
-  TopOfStack top_of_stack_state_:3;
-  int register_allocation_map_:kNumberOfAllocatedRegisters;
-  static const int kTOSKnownSmiMapSize = 4;
-  unsigned tos_known_smi_map_:kTOSKnownSmiMapSize;
-
-  // The index of the element that is at the processor's stack pointer
-  // (the sp register).  For now since everything is in memory it is given
-  // by the number of elements on the not-very-virtual stack frame.
-  int stack_pointer() { return element_count_ - 1; }
-
-  // The number of frame-allocated locals and parameters respectively.
-  inline int parameter_count() const;
-  inline int local_count() const;
-
-  // The index of the element that is at the processor's frame pointer
-  // (the fp register).  The parameters, receiver, function, and context
-  // are below the frame pointer.
-  inline int frame_pointer() const;
-
-  // The index of the first parameter.  The receiver lies below the first
-  // parameter.
-  int param0_index() { return 1; }
-
-  // The index of the context slot in the frame.  It is immediately
-  // below the frame pointer.
-  inline int context_index();
-
-  // The index of the function slot in the frame.  It is below the frame
-  // pointer and context slot.
-  inline int function_index();
-
-  // The index of the first local.  Between the frame pointer and the
-  // locals lies the return address.
-  inline int local0_index() const;
-
-  // The index of the base of the expression stack.
-  inline int expression_base_index() const;
-
-  // Convert a frame index into a frame pointer relative offset into the
-  // actual stack.
-  inline int fp_relative(int index);
-
-  // Spill all elements in registers. Spill the top spilled_args elements
-  // on the frame.  Sync all other frame elements.
-  // Then drop dropped_args elements from the virtual frame, to match
-  // the effect of an upcoming call that will drop them from the stack.
-  void PrepareForCall(int spilled_args, int dropped_args);
-
-  // If all top-of-stack registers are in use then the lowest one is pushed
-  // onto the physical stack and made free.
-  void EnsureOneFreeTOSRegister();
-
-  // Emit instructions to get the top of stack state from where we are to where
-  // we want to be.
-  void MergeTOSTo(TopOfStack expected_state, Condition cond = al);
-
-  inline bool Equals(const VirtualFrame* other);
-
-  inline void LowerHeight(int count) {
-    element_count_ -= count;
-    if (count >= kTOSKnownSmiMapSize) {
-      tos_known_smi_map_ = 0;
-    } else {
-      tos_known_smi_map_ >>= count;
-    }
-  }
-
-  inline void RaiseHeight(int count, unsigned known_smi_map = 0) {
-    ASSERT(count >= 32 || known_smi_map < (1u << count));
-    element_count_ += count;
-    if (count >= kTOSKnownSmiMapSize) {
-      tos_known_smi_map_ = known_smi_map;
-    } else {
-      tos_known_smi_map_ = ((tos_known_smi_map_ << count) | known_smi_map);
-    }
-  }
-
-  friend class JumpTarget;
-};
-
-
-} }  // namespace v8::internal
-
-#endif  // V8_ARM_VIRTUAL_FRAME_ARM_H_