Remove some dead code.

src/ia32/virtual-frame-ia32.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_IA32_VIRTUAL_FRAME_IA32_H_
-#define V8_IA32_VIRTUAL_FRAME_IA32_H_
-
-#include "codegen.h"
-#include "register-allocator.h"
-#include "scopes.h"
-#include "type-info.h"
-
-namespace v8 {
-namespace internal {
-
-// -------------------------------------------------------------------------
-// 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:
-  // 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, but no attempt is made to require it
-  // to stay spilled.  It is intended as documentation while the code
-  // generator is being transformed.
-  class SpilledScope BASE_EMBEDDED {
-   public:
-    SpilledScope() : previous_state_(cgen()->in_spilled_code()) {
-      ASSERT(cgen()->has_valid_frame());
-      cgen()->frame()->SpillAll();
-      cgen()->set_in_spilled_code(true);
-    }
-
-    ~SpilledScope() {
-      cgen()->set_in_spilled_code(previous_state_);
-    }
-
-   private:
-    bool previous_state_;
-
-    CodeGenerator* cgen() {
-      return CodeGeneratorScope::Current(Isolate::Current());
-    }
-  };
-
-  // 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 a virtual frame as a clone of an existing one.
-  explicit inline VirtualFrame(VirtualFrame* original);
-
-  CodeGenerator* cgen() {
-    return CodeGeneratorScope::Current(Isolate::Current());
-  }
-
-  MacroAssembler* masm() { return cgen()->masm(); }
-
-  // Create a duplicate of an existing valid frame element.
-  FrameElement CopyElementAt(int index,
-    TypeInfo info = TypeInfo::Uninitialized());
-
-  // The number of elements on the virtual frame.
-  int element_count() { return elements_.length(); }
-
-  // The height of the virtual expression stack.
-  int height() { return element_count() - expression_base_index(); }
-
-  int register_location(int num) {
-    ASSERT(num >= 0 && num < RegisterAllocator::kNumRegisters);
-    return register_locations_[num];
-  }
-
-  inline int register_location(Register reg);
-
-  inline void set_register_location(Register reg, int index);
-
-  bool is_used(int num) {
-    ASSERT(num >= 0 && num < RegisterAllocator::kNumRegisters);
-    return register_locations_[num] != kIllegalIndex;
-  }
-
-  inline bool is_used(Register reg);
-
-  // 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 count elements from the top of the frame all in-memory
-  // (including synced) and adjust the stack pointer downward, to
-  // match an external frame effect (examples include a call removing
-  // its arguments, and exiting a try/catch removing an exception
-  // handler).  No code will be emitted.
-  void Forget(int count) {
-    ASSERT(count >= 0);
-    ASSERT(stack_pointer_ == element_count() - 1);
-    stack_pointer_ -= count;
-    ForgetElements(count);
-  }
-
-  // Forget count elements from the top of the frame without adjusting
-  // the stack pointer downward.  This is used, for example, before
-  // merging frames at break, continue, and return targets.
-  void ForgetElements(int count);
-
-  // Spill all values from the frame to memory.
-  inline void SpillAll();
-
-  // Spill all occurrences of a specific register from the frame.
-  void Spill(Register reg) {
-    if (is_used(reg)) SpillElementAt(register_location(reg));
-  }
-
-  // Make the two registers distinct and spill them.  Returns the second
-  // register.  If the registers were not distinct then it returns the new
-  // second register.
-  Result MakeDistinctAndSpilled(Result* left, Result* right) {
-    Spill(left->reg());
-    Spill(right->reg());
-    if (left->reg().is(right->reg())) {
-      RegisterAllocator* allocator = cgen()->allocator();
-      Result fresh = allocator->Allocate();
-      ASSERT(fresh.is_valid());
-      masm()->mov(fresh.reg(), right->reg());
-      return fresh;
-    }
-    return *right;
-  }
-
-  // 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).
-  Register SpillAnyRegister();
-
-  // Spill the top element of the frame.
-  void SpillTop() { SpillElementAt(element_count() - 1); }
-
-  // Sync the range of elements in [begin, end] with memory.
-  void SyncRange(int begin, int end);
-
-  // Make this frame so that an arbitrary frame of the same height can
-  // be merged to it.  Copies and constants are removed from the frame.
-  void MakeMergable();
-
-  // Prepare this virtual frame for merging to an expected frame by
-  // performing some state changes that do not require generating
-  // code.  It is guaranteed that no code will be generated.
-  void PrepareMergeTo(VirtualFrame* expected);
-
-  // 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);
-
-  // 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() {
-    RegisterAllocator* cgen_allocator = cgen()->allocator();
-    for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
-      if (is_used(i)) cgen_allocator->Unuse(i);
-    }
-  }
-
-  // (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() {
-    RegisterAllocator* cgen_allocator = cgen()->allocator();
-    for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) {
-      if (is_used(i)) cgen_allocator->Use(i);
-    }
-  }
-
-  // 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 spilling locals.  This
-  // avoids generating unnecessary merge code when jumping to the
-  // shared return site.  Emits code for spills.
-  inline void PrepareForReturn();
-
-  // Number of local variables after when we use a loop for allocating.
-  static const int kLocalVarBound = 10;
-
-  // Allocate and initialize the frame-allocated locals.
-  void AllocateStackSlots();
-
-  // An element of the expression stack as an assembly operand.
-  Operand ElementAt(int index) const {
-    return Operand(esp, index * kPointerSize);
-  }
-
-  // Random-access store to a frame-top relative frame element.  The result
-  // becomes owned by the frame and is invalidated.
-  void SetElementAt(int index, Result* value);
-
-  // Set a frame element to a constant.  The index is frame-top relative.
-  inline void SetElementAt(int index, Handle<Object> value);
-
-  void PushElementAt(int index) {
-    PushFrameSlotAt(element_count() - index - 1);
-  }
-
-  void StoreToElementAt(int index) {
-    StoreToFrameSlotAt(element_count() - index - 1);
-  }
-
-  // A frame-allocated local as an assembly operand.
-  Operand LocalAt(int index) {
-    ASSERT(0 <= index);
-    ASSERT(index < local_count());
-    return Operand(ebp, kLocal0Offset - index * kPointerSize);
-  }
-
-  // Push a copy of the value of a local frame slot on top of the frame.
-  void PushLocalAt(int index) {
-    PushFrameSlotAt(local0_index() + index);
-  }
-
-  // Push a copy of the value of a local frame slot on top of the frame.
-  void UntaggedPushLocalAt(int index) {
-    UntaggedPushFrameSlotAt(local0_index() + index);
-  }
-
-  // Push the value of a local frame slot on top of the frame and invalidate
-  // the local slot.  The slot should be written to before trying to read
-  // from it again.
-  void TakeLocalAt(int index) {
-    TakeFrameSlotAt(local0_index() + index);
-  }
-
-  // Store the top value on the virtual frame into a local frame slot.  The
-  // value is left in place on top of the frame.
-  void StoreToLocalAt(int index) {
-    StoreToFrameSlotAt(local0_index() + index);
-  }
-
-  // Push the address of the receiver slot on the frame.
-  void PushReceiverSlotAddress();
-
-  // Push the function on top of the frame.
-  void PushFunction() {
-    PushFrameSlotAt(function_index());
-  }
-
-  // Save the value of the esi register to the context frame slot.
-  void SaveContextRegister();
-
-  // Restore the esi register from the value of the context frame
-  // slot.
-  void RestoreContextRegister();
-
-  // A parameter as an assembly operand.
-  Operand ParameterAt(int index) {
-    ASSERT(-1 <= index);  // -1 is the receiver.
-    ASSERT(index < parameter_count());
-    return Operand(ebp, (1 + parameter_count() - index) * kPointerSize);
-  }
-
-  // Push a copy of the value of a parameter frame slot on top of the frame.
-  void PushParameterAt(int index) {
-    PushFrameSlotAt(param0_index() + index);
-  }
-
-  // Push a copy of the value of a parameter frame slot on top of the frame.
-  void UntaggedPushParameterAt(int index) {
-    UntaggedPushFrameSlotAt(param0_index() + index);
-  }
-
-  // Push the value of a paramter frame slot on top of the frame and
-  // invalidate the parameter slot.  The slot should be written to before
-  // trying to read from it again.
-  void TakeParameterAt(int index) {
-    TakeFrameSlotAt(param0_index() + index);
-  }
-
-  // Store the top value on the virtual frame into a parameter frame slot.
-  // The value is left in place on top of the frame.
-  void StoreToParameterAt(int index) {
-    StoreToFrameSlotAt(param0_index() + index);
-  }
-
-  // The receiver frame slot.
-  Operand Receiver() {
-    return ParameterAt(-1);
-  }
-
-  // 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 Result CallStub(CodeStub* stub, int arg_count);
-
-  // Call stub that takes a single argument passed in eax.  The
-  // argument is given as a result which does not have to be eax or
-  // even a register.  The argument is consumed by the call.
-  Result CallStub(CodeStub* stub, Result* arg);
-
-  // Call stub that takes a pair of arguments passed in edx (arg0) and
-  // eax (arg1).  The arguments are given as results which do not have
-  // to be in the proper registers or even in registers.  The
-  // arguments are consumed by the call.
-  Result CallStub(CodeStub* stub, Result* arg0, Result* arg1);
-
-  // Call JS function from top of the stack with arguments
-  // taken from the stack.
-  Result CallJSFunction(int arg_count);
-
-  // Call runtime given the number of arguments expected on (and
-  // removed from) the stack.
-  Result CallRuntime(const Runtime::Function* f, int arg_count);
-  Result 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.
-  Result InvokeBuiltin(Builtins::JavaScript id, InvokeFlag flag, int arg_count);
-
-  // Call load IC.  Name and receiver are found on top of the frame.
-  // Both are dropped.
-  Result CallLoadIC(RelocInfo::Mode mode);
-
-  // Call keyed load IC.  Key and receiver are found on top of the
-  // frame.  Both are dropped.
-  Result CallKeyedLoadIC(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 dropped.
-  Result CallStoreIC(Handle<String> name, bool is_contextual,
-                     StrictModeFlag strict_mode);
-
-  // Call keyed store IC.  Value, key, and receiver are found on top
-  // of the frame.  All three are dropped.
-  Result CallKeyedStoreIC(StrictModeFlag strict_mode);
-
-  // Call call IC.  Function name, arguments, and receiver are found on top
-  // of the frame and dropped by the call.  The argument count does not
-  // include the receiver.
-  Result CallCallIC(RelocInfo::Mode mode, int arg_count, int loop_nesting);
-
-  // Call keyed call IC.  Same calling convention as CallCallIC.
-  Result CallKeyedCallIC(RelocInfo::Mode mode, int arg_count, int loop_nesting);
-
-  // Allocate and call JS function as constructor.  Arguments,
-  // receiver (global object), and function are found on top of the
-  // frame.  Function is not dropped.  The argument count does not
-  // include the receiver.
-  Result CallConstructor(int arg_count);
-
-  // 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);
-  }
-
-  // Duplicate the top element of the frame.
-  void Dup() {
-    PushFrameSlotAt(element_count() - 1);
-  }
-
-  // Pop an element from the top of the expression stack.  Returns a
-  // Result, which may be a constant or a register.
-  Result Pop();
-
-  // Pop and save an element from the top of the expression stack and
-  // emit a corresponding pop instruction.
-  void EmitPop(Register reg);
-  void EmitPop(Operand operand);
-
-  // Push an element on top of the expression stack and emit a
-  // corresponding push instruction.
-  void EmitPush(Register reg,
-                TypeInfo info = TypeInfo::Unknown());
-  void EmitPush(Operand operand,
-                TypeInfo info = TypeInfo::Unknown());
-  void EmitPush(Immediate immediate,
-                TypeInfo info = TypeInfo::Unknown());
-
-  inline bool ConstantPoolOverflowed();
-
-  // Push an element on the virtual frame.
-  void Push(Handle<Object> value);
-  inline void Push(Register reg, TypeInfo info = TypeInfo::Unknown());
-  inline void Push(Smi* value);
-
-  void PushUntaggedElement(Handle<Object> value);
-
-  // Pushing a result invalidates it (its contents become owned by the
-  // frame).
-  void Push(Result* result) {
-    // This assert will trigger if you try to push the same value twice.
-    ASSERT(result->is_valid());
-    if (result->is_register()) {
-      Push(result->reg(), result->type_info());
-    } else {
-      ASSERT(result->is_constant());
-      Push(result->handle());
-    }
-    if (cgen()->in_safe_int32_mode()) {
-      ASSERT(result->is_untagged_int32());
-      elements_[element_count() - 1].set_untagged_int32(true);
-    }
-    result->Unuse();
-  }
-
-  // Pushing an expression expects that the expression is trivial (according
-  // to Expression::IsTrivial).
-  void Push(Expression* expr);
-
-  // Nip removes zero or more elements from immediately below the top
-  // of the frame, leaving the previous top-of-frame value on top of
-  // the frame.  Nip(k) is equivalent to x = Pop(), Drop(k), Push(x).
-  inline void Nip(int num_dropped);
-
-  // Check that the frame has no elements containing untagged int32 elements.
-  bool HasNoUntaggedInt32Elements() {
-    for (int i = 0; i < element_count(); ++i) {
-      if (elements_[i].is_untagged_int32()) return false;
-    }
-    return true;
-  }
-
-  // Update the type information of a variable frame element directly.
-  inline void SetTypeForLocalAt(int index, TypeInfo info);
-  inline void SetTypeForParamAt(int index, TypeInfo info);
-
- 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.
-
-  ZoneList<FrameElement> elements_;
-
-  // The index of the element that is at the processor's stack pointer
-  // (the esp register).
-  int stack_pointer_;
-
-  // The index of the register frame element using each register, or
-  // kIllegalIndex if a register is not on the frame.
-  int register_locations_[RegisterAllocator::kNumRegisters];
-
-  // The number of frame-allocated locals and parameters respectively.
-  inline int parameter_count();
-
-  inline int local_count();
-
-  // The index of the element that is at the processor's frame pointer
-  // (the ebp register).  The parameters, receiver, and return address
-  // are below the frame pointer.
-  int frame_pointer() {
-    return parameter_count() + 2;
-  }
-
-  // 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
-  // above the frame pointer.
-  int context_index() {
-    return frame_pointer() + 1;
-  }
-
-  // The index of the function slot in the frame.  It is above the frame
-  // pointer and the context slot.
-  int function_index() {
-    return frame_pointer() + 2;
-  }
-
-  // The index of the first local.  Between the frame pointer and the
-  // locals lie the context and the function.
-  int local0_index() {
-    return frame_pointer() + 3;
-  }
-
-  // The index of the base of the expression stack.
-  int expression_base_index() {
-    return local0_index() + local_count();
-  }
-
-  // Convert a frame index into a frame pointer relative offset into the
-  // actual stack.
-  int fp_relative(int index) {
-    ASSERT(index < element_count());
-    ASSERT(frame_pointer() < element_count());  // FP is on the frame.
-    return (frame_pointer() - index) * kPointerSize;
-  }
-
-  // Record an occurrence of a register in the virtual frame.  This has the
-  // effect of incrementing the register's external reference count and
-  // of updating the index of the register's location in the frame.
-  void Use(Register reg, int index) {
-    ASSERT(!is_used(reg));
-    set_register_location(reg, index);
-    cgen()->allocator()->Use(reg);
-  }
-
-  // Record that a register reference has been dropped from the frame.  This
-  // decrements the register's external reference count and invalidates the
-  // index of the register's location in the frame.
-  void Unuse(Register reg) {
-    ASSERT(is_used(reg));
-    set_register_location(reg, kIllegalIndex);
-    cgen()->allocator()->Unuse(reg);
-  }
-
-  // Spill the element at a particular index---write it to memory if
-  // necessary, free any associated register, and forget its value if
-  // constant.
-  void SpillElementAt(int index);
-
-  // Sync the element at a particular index.  If it is a register or
-  // constant that disagrees with the value on the stack, write it to memory.
-  // Keep the element type as register or constant, and clear the dirty bit.
-  void SyncElementAt(int index);
-
-  // Sync a single unsynced element that lies beneath or at the stack pointer.
-  void SyncElementBelowStackPointer(int index);
-
-  // Sync a single unsynced element that lies just above the stack pointer.
-  void SyncElementByPushing(int index);
-
-  // Push a copy of a frame slot (typically a local or parameter) on top of
-  // the frame.
-  inline void PushFrameSlotAt(int index);
-
-  // Push a copy of a frame slot (typically a local or parameter) on top of
-  // the frame, at an untagged int32 value.  Bails out if the value is not
-  // an int32.
-  void UntaggedPushFrameSlotAt(int index);
-
-  // Push a the value of a frame slot (typically a local or parameter) on
-  // top of the frame and invalidate the slot.
-  void TakeFrameSlotAt(int index);
-
-  // Store the value on top of the frame to a frame slot (typically a local
-  // or parameter).
-  void StoreToFrameSlotAt(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);
-
-  // Move frame elements currently in registers or constants, that
-  // should be in memory in the expected frame, to memory.
-  void MergeMoveRegistersToMemory(VirtualFrame* expected);
-
-  // Make the register-to-register moves necessary to
-  // merge this frame with the expected frame.
-  // Register to memory moves must already have been made,
-  // and memory to register moves must follow this call.
-  // This is because some new memory-to-register moves are
-  // created in order to break cycles of register moves.
-  // Used in the implementation of MergeTo().
-  void MergeMoveRegistersToRegisters(VirtualFrame* expected);
-
-  // Make the memory-to-register and constant-to-register moves
-  // needed to make this frame equal the expected frame.
-  // Called after all register-to-memory and register-to-register
-  // moves have been made.  After this function returns, the frames
-  // should be equal.
-  void MergeMoveMemoryToRegisters(VirtualFrame* expected);
-
-  // Invalidates a frame slot (puts an invalid frame element in it).
-  // Copies on the frame are correctly handled, and if this slot was
-  // the backing store of copies, the index of the new backing store
-  // is returned.  Otherwise, returns kIllegalIndex.
-  // Register counts are correctly updated.
-  int InvalidateFrameSlotAt(int index);
-
-  // This function assumes that a and b are the only results that could be in
-  // the registers a_reg or b_reg.  Other results can be live, but must not
-  //  be in the registers a_reg or b_reg.  The results a and b are invalidated.
-  void MoveResultsToRegisters(Result* a,
-                              Result* b,
-                              Register a_reg,
-                              Register b_reg);
-
-  // Call a code stub that has already been prepared for calling (via
-  // PrepareForCall).
-  Result RawCallStub(CodeStub* stub);
-
-  // Calls a code object which has already been prepared for calling
-  // (via PrepareForCall).
-  Result RawCallCodeObject(Handle<Code> code, RelocInfo::Mode rmode);
-
-  inline bool Equals(VirtualFrame* other);
-
-  // Classes that need raw access to the elements_ array.
-  friend class FrameRegisterState;
-  friend class JumpTarget;
-};
-
-} }  // namespace v8::internal
-
-#endif  // V8_IA32_VIRTUAL_FRAME_IA32_H_