Remove some dead code.

src/jump-target-heavy.h

-// Copyright 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
-//       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_JUMP_TARGET_HEAVY_H_
-#define V8_JUMP_TARGET_HEAVY_H_
-
-#include "macro-assembler.h"
-#include "zone-inl.h"
-
-namespace v8 {
-namespace internal {
-
-// Forward declarations.
-class FrameElement;
-class Result;
-class VirtualFrame;
-
-// -------------------------------------------------------------------------
-// Jump targets
-//
-// A jump target is an abstraction of a basic-block entry in generated
-// code.  It collects all the virtual frames reaching the block by
-// forward jumps and pairs them with labels for the merge code along
-// all forward-reaching paths.  When bound, an expected frame for the
-// block is determined and code is generated to merge to the expected
-// frame.  For backward jumps, the merge code is generated at the edge
-// leaving the predecessor block.
-//
-// A jump target must have been reached via control flow (either by
-// jumping, branching, or falling through) at the time it is bound.
-// In particular, this means that at least one of the control-flow
-// graph edges reaching the target must be a forward edge.
-
-class JumpTarget : public ZoneObject {  // Shadows are dynamically allocated.
- public:
-  // Forward-only jump targets can only be reached by forward CFG edges.
-  enum Directionality { FORWARD_ONLY, BIDIRECTIONAL };
-
-  // Construct a jump target used to generate code and to provide
-  // access to a current frame.
-  explicit JumpTarget(Directionality direction)
-      : direction_(direction),
-        reaching_frames_(0),
-        merge_labels_(0),
-        entry_frame_(NULL) {
-  }
-
-  // Construct a jump target.
-  JumpTarget()
-      : direction_(FORWARD_ONLY),
-        reaching_frames_(0),
-        merge_labels_(0),
-        entry_frame_(NULL) {
-  }
-
-  virtual ~JumpTarget() {}
-
-  // Set the direction of the jump target.
-  virtual void set_direction(Directionality direction) {
-    direction_ = direction;
-  }
-
-  // Treat the jump target as a fresh one.  The state is reset.
-  void Unuse();
-
-  inline CodeGenerator* cgen();
-
-  Label* entry_label() { return &entry_label_; }
-
-  VirtualFrame* entry_frame() const { return entry_frame_; }
-  void set_entry_frame(VirtualFrame* frame) {
-    entry_frame_ = frame;
-  }
-
-  // Predicates testing the state of the encapsulated label.
-  bool is_bound() const { return entry_label_.is_bound(); }
-  bool is_linked() const {
-    return !is_bound() && !reaching_frames_.is_empty();
-  }
-  bool is_unused() const {
-    // This is !is_bound() && !is_linked().
-    return !is_bound() && reaching_frames_.is_empty();
-  }
-
-  // Emit a jump to the target.  There must be a current frame at the
-  // jump and there will be no current frame after the jump.
-  virtual void Jump();
-  virtual void Jump(Result* arg);
-
-  // Emit a conditional branch to the target.  There must be a current
-  // frame at the branch.  The current frame will fall through to the
-  // code after the branch.  The arg is a result that is live both at
-  // the target and the fall-through.
-  virtual void Branch(Condition cc, Hint hint = no_hint);
-  virtual void Branch(Condition cc, Result* arg, Hint hint = no_hint);
-  void Branch(Condition cc,
-              Result* arg0,
-              Result* arg1,
-              Hint hint = no_hint);
-
-  // Bind a jump target.  If there is no current frame at the binding
-  // site, there must be at least one frame reaching via a forward
-  // jump.
-  virtual void Bind();
-  virtual void Bind(Result* arg);
-  void Bind(Result* arg0, Result* arg1);
-
-  // Emit a call to a jump target.  There must be a current frame at
-  // the call.  The frame at the target is the same as the current
-  // frame except for an extra return address on top of it.  The frame
-  // after the call is the same as the frame before the call.
-  void Call();
-
- protected:
-  // Directionality flag set at initialization time.
-  Directionality direction_;
-
-  // A list of frames reaching this block via forward jumps.
-  ZoneList<VirtualFrame*> reaching_frames_;
-
-  // A parallel list of labels for merge code.
-  ZoneList<Label> merge_labels_;
-
-  // The frame used on entry to the block and expected at backward
-  // jumps to the block.  Set when the jump target is bound, but may
-  // or may not be set for forward-only blocks.
-  VirtualFrame* entry_frame_;
-
-  // The actual entry label of the block.
-  Label entry_label_;
-
-  // Implementations of Jump, Branch, and Bind with all arguments and
-  // return values using the virtual frame.
-  void DoJump();
-  void DoBranch(Condition cc, Hint hint);
-  void DoBind();
-
- private:
-  // Add a virtual frame reaching this labeled block via a forward jump,
-  // and a corresponding merge code label.
-  void AddReachingFrame(VirtualFrame* frame);
-
-  // Perform initialization required during entry frame computation
-  // after setting the virtual frame element at index in frame to be
-  // target.
-  inline void InitializeEntryElement(int index, FrameElement* target);
-
-  // Compute a frame to use for entry to this block.
-  void ComputeEntryFrame();
-
-  DISALLOW_COPY_AND_ASSIGN(JumpTarget);
-};
-
-
-// -------------------------------------------------------------------------
-// Break targets
-//
-// A break target is a jump target that can be used to break out of a
-// statement that keeps extra state on the stack (eg, for/in or
-// try/finally).  They know the expected stack height at the target
-// and will drop state from nested statements as part of merging.
-//
-// Break targets are used for return, break, and continue targets.
-
-class BreakTarget : public JumpTarget {
- public:
-  // Construct a break target.
-  BreakTarget() {}
-  explicit BreakTarget(JumpTarget::Directionality direction)
-    : JumpTarget(direction) { }
-
-  virtual ~BreakTarget() {}
-
-  // Set the direction of the break target.
-  virtual void set_direction(Directionality direction);
-
-  // Copy the state of this break target to the destination.  The
-  // lists of forward-reaching frames and merge-point labels are
-  // copied.  All virtual frame pointers are copied, not the
-  // pointed-to frames.  The previous state of the destination is
-  // overwritten, without deallocating pointed-to virtual frames.
-  void CopyTo(BreakTarget* destination);
-
-  // Emit a jump to the target.  There must be a current frame at the
-  // jump and there will be no current frame after the jump.
-  virtual void Jump();
-  virtual void Jump(Result* arg);
-
-  // Emit a conditional branch to the target.  There must be a current
-  // frame at the branch.  The current frame will fall through to the
-  // code after the branch.
-  virtual void Branch(Condition cc, Hint hint = no_hint);
-  virtual void Branch(Condition cc, Result* arg, Hint hint = no_hint);
-
-  // Bind a break target.  If there is no current frame at the binding
-  // site, there must be at least one frame reaching via a forward
-  // jump.
-  virtual void Bind();
-  virtual void Bind(Result* arg);
-
-  // Setter for expected height.
-  void set_expected_height(int expected) { expected_height_ = expected; }
-
- private:
-  // The expected height of the expression stack where the target will
-  // be bound, statically known at initialization time.
-  int expected_height_;
-
-  DISALLOW_COPY_AND_ASSIGN(BreakTarget);
-};
-
-} }  // namespace v8::internal
-
-#endif  // V8_JUMP_TARGET_HEAVY_H_