[turbofan] Add general support for sp-based frame access

src/compiler/frame.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_FRAME_H_
 #define V8_COMPILER_FRAME_H_
 
 #include "src/bit-vector.h"
 #include "src/frames.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
+class CallDescriptor;
+
 // Collects the spill slot and other frame slot requirements for a compiled
 // function. Frames are usually populated by the register allocator and are used
-// by Linkage to generate code for the prologue and epilogue to compiled code.
+// by Linkage to generate code for the prologue and epilogue to compiled
+// code. Frame objects must be considered immutable once they've been
+// instantiated and the basic information about the frame has been collected
+// into them. Mutable state associated with the frame is stored separately in
+// FrameAccessState.
 //
-// Frames are divided up into four regions.
+// Frames are divided up into three regions.
 // - The first is the fixed header, which always has a constant size and can be
 //   predicted before code generation begins depending on the type of code being
 //   generated.
 // - The second is the region for spill slots, which is immediately below the
 //   fixed header and grows as the register allocator needs to spill to the
 //   stack and asks the frame for more space.
 // - The third region, which contains the callee-saved registers must be
 //   reserved after register allocation, since its size can only be precisely
 //   determined after register allocation once the number of used callee-saved
 //   register is certain.
-// - The fourth region is used to pass arguments to other functions. It should
-//   be empty except when a call is being prepared.
 //
 // Every pointer in a frame has a slot id. On 32-bit platforms, doubles consume
 // two slots.
 //
 // Stack slot indices >= 0 access the callee stack with slot 0 corresponding to
 // the callee's saved return address and 1 corresponding to the saved frame
 // pointer. Some frames have additional information stored in the fixed header,
 // for example JSFunctions store the function context and marker in the fixed
 // header, with slot index 2 corresponding to the current function context and 3
 // corresponding to the frame marker/JSFunction. The frame region immediately
@@ skipping 29 matching lines @@
 //   4   |    spill 1      |   ^                      Callee
 //       |- - - - - - - - -|   |                   frame slots
 //  ...  |      ...        | Spill slots           (slot >= 0)
 //       |- - - - - - - - -|   |                        |
 //  m+4  |    spill m      |   v                        |
 //       +-----------------+----                        |
 //  m+5  |  callee-saved 1 |   ^                        |
 //       |- - - - - - - - -|   |                        |
 //       |      ...        | Callee-saved               |
 //       |- - - - - - - - -|   |                        |
-// m+r+4 |  callee-saved r |   v                        |
-//       +-----------------+----                        |
-//       |   parameter 0   |   ^                        |
-//       |- - - - - - - - -|   |                        |
-//       |      ...        | Outgoing parameters        |
-//       |- - - - - - - - -|   |  (for function calls)  |
-//       |   parameter p   |   v                        v
+// m+r+4 |  callee-saved r |   v                        v
 //  -----+-----------------+----- <-- stack ptr -------------
 //
 class Frame : public ZoneObject {
  public:
-  explicit Frame(int fixed_frame_size_in_slots);
+  explicit Frame(int fixed_frame_size_in_slots,
+                 const CallDescriptor* descriptor);
+
+  static int FPOffsetToSlot(int frame_offset) {
+    return StandardFrameConstants::kFixedSlotCountAboveFp - 1 -
+           frame_offset / kPointerSize;
+  }
+
+  static int SlotToFPOffset(int slot) {
+    return (StandardFrameConstants::kFixedSlotCountAboveFp - 1 - slot) *
+           kPointerSize;
+  }
+
+  inline bool needs_frame() const { return needs_frame_; }
+  inline void MarkNeedsFrame() { needs_frame_ = true; }
 
   inline int GetTotalFrameSlotCount() const { return frame_slot_count_; }
 
   inline int GetSpToFpSlotCount() const {
     return GetTotalFrameSlotCount() -
            StandardFrameConstants::kFixedSlotCountAboveFp;
   }
-  inline int GetOutgoingParameterSlotCount() const {
-    return outgoing_parameter_slot_count_;
-  }
   inline int GetSavedCalleeRegisterSlotCount() const {
     return callee_saved_slot_count_;
   }
   inline int GetSpillSlotCount() const { return spill_slot_count_; }
 
   inline void SetElidedFrameSizeInSlots(int slots) {
     DCHECK_EQ(0, callee_saved_slot_count_);
     DCHECK_EQ(0, spill_slot_count_);
     frame_slot_count_ = slots;
   }
 
   void SetAllocatedRegisters(BitVector* regs) {
     DCHECK(allocated_registers_ == NULL);
     allocated_registers_ = regs;
   }
 
   void SetAllocatedDoubleRegisters(BitVector* regs) {
     DCHECK(allocated_double_registers_ == NULL);
     allocated_double_registers_ = regs;
   }
 
   bool DidAllocateDoubleRegisters() const {
     return !allocated_double_registers_->IsEmpty();
   }
 
-  void AllocateOutgoingParameterSlots(int count) {
-    outgoing_parameter_slot_count_ += count;
-    frame_slot_count_ += count;
-  }
-
-  void ClearOutgoingParameterSlots() {
-    frame_slot_count_ -= outgoing_parameter_slot_count_;
-    outgoing_parameter_slot_count_ = 0;
-  }
-
   int AlignSavedCalleeRegisterSlots() {
     DCHECK_EQ(0, callee_saved_slot_count_);
+    needs_frame_ = true;
     int delta = frame_slot_count_ & 1;
     frame_slot_count_ += delta;
     return delta;
   }
 
   void AllocateSavedCalleeRegisterSlots(int count) {
-    DCHECK_EQ(0, outgoing_parameter_slot_count_);
+    needs_frame_ = true;
     frame_slot_count_ += count;
     callee_saved_slot_count_ += count;
   }
 
   int AllocateSpillSlot(int width) {
-    DCHECK_EQ(0, outgoing_parameter_slot_count_);
     DCHECK_EQ(0, callee_saved_slot_count_);
+    needs_frame_ = true;
     int frame_slot_count_before = frame_slot_count_;
     int slot = AllocateAlignedFrameSlot(width);
     spill_slot_count_ += (frame_slot_count_ - frame_slot_count_before);
     return slot;
   }
 
   int ReserveSpillSlots(size_t slot_count) {
-    DCHECK_EQ(0, outgoing_parameter_slot_count_);
     DCHECK_EQ(0, callee_saved_slot_count_);
     DCHECK_EQ(0, spill_slot_count_);
+    needs_frame_ = true;
     spill_slot_count_ += static_cast<int>(slot_count);
     frame_slot_count_ += static_cast<int>(slot_count);
     return frame_slot_count_ - 1;
   }
 
   static const int kContextSlot = 2 + StandardFrameConstants::kCPSlotCount;
   static const int kJSFunctionSlot = 3 + StandardFrameConstants::kCPSlotCount;
 
  private:
   int AllocateAlignedFrameSlot(int width) {
     DCHECK(width == 4 || width == 8);
     // Skip one slot if necessary.
     if (width > kPointerSize) {
       DCHECK(width == kPointerSize * 2);
       frame_slot_count_++;
       frame_slot_count_ |= 1;
     }
     return frame_slot_count_++;
   }
 
  private:
+  bool needs_frame_;
   int frame_slot_count_;
-  int outgoing_parameter_slot_count_;
   int callee_saved_slot_count_;
   int spill_slot_count_;
   BitVector* allocated_registers_;
   BitVector* allocated_double_registers_;
 
   DISALLOW_COPY_AND_ASSIGN(Frame);
 };
 
 
 // Represents an offset from either the stack pointer or frame pointer.
@@ skipping 14 matching lines @@
   }
 
  private:
   explicit FrameOffset(int offset) : offset_(offset) {}
 
   int offset_;  // Encodes SP or FP in the low order bit.
 
   static const int kFromSp = 1;
   static const int kFromFp = 0;
 };
+
+// Encapsulates the mutable state maintained during code generation about the
+// current function's frame.
+class FrameAccessState : public ZoneObject {
+ public:
+  explicit FrameAccessState(Frame* const frame)
+      : frame_(frame), access_frame_with_fp_(false), sp_delta_(0) {
+    SetFrameAccessToDefault();
+  }
+
+  Frame* const frame() const { return frame_; }
+
+  int sp_delta() const { return sp_delta_; }
+  void ClearSPDelta() { sp_delta_ = 0; }
+  void IncreaseSPDelta(int amount) { sp_delta_ += amount; }
+
+  bool access_frame_with_fp() const { return access_frame_with_fp_; }
+  void SetFrameAccessToDefault();
+  void SetFrameAccessToFP() { access_frame_with_fp_ = true; }
+  void SetFrameAccessToSP() { access_frame_with_fp_ = false; }
+
+  // Get the frame offset for a given spill slot. The location depends on the
+  // calling convention and the specific frame layout, and may thus be
+  // architecture-specific. Negative spill slots indicate arguments on the
+  // caller's frame.
+  FrameOffset GetFrameOffset(int spill_slot) const;
+
+ private:
+  Frame* const frame_;
+  bool access_frame_with_fp_;
+  int sp_delta_;
+};
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_FRAME_H_