[arm64] Use SP-offset rather than FP-offset.

src/compiler/frame.h

Index: src/compiler/frame.h
diff --git a/src/compiler/frame.h b/src/compiler/frame.h
index 9764b261efc48383dc6a6964c906718f87453973..e63619b9acdb5c3e8de0baf156fabe80879f01d3 100644
--- a/src/compiler/frame.h
+++ b/src/compiler/frame.h
@@ -16,15 +16,19 @@ namespace compiler {
 // 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.
 //
-// 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.
+// Frames are divided up into four 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.
@@ -35,10 +39,10 @@ namespace compiler {
 // 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
-// below the fixed header contains spill slots starting a 4 for JsFunctions. The
-// callee-saved frame region below that starts at 4+spilled_slot_count. Callee
-// stack slots corresponding to parameters are accessible through negative slot
-// ids.
+// below the fixed header contains spill slots starting at 4 for JsFunctions.
+// The callee-saved frame region below that starts at 4+spill_slot_count_.
+// Callee stack slots corresponding to parameters are accessible through
+// negative slot ids.
 //
 // Every slot of a caller or callee frame is accessible by the register
 // allocator and gap resolver with a SpillSlotOperand containing its
@@ -47,50 +51,63 @@ namespace compiler {
 // Below an example JSFunction Frame with slot ids, frame regions and contents:
 //
 //  slot      JS frame
-//       +-----------------+----------------------------
-//  -n-1 |   parameter 0   |                        ^
-//       |- - - - - - - - -|                        |
-//  -n   |                 |                      Caller
-//  ...  |       ...       |                   frame slots
-//  -2   |  parameter n-1  |                   (slot < 0)
-//       |- - - - - - - - -|                        |
-//  -1   |   parameter n   |                        v
-//  -----+-----------------+----------------------------
-//   0   |   return addr   |   ^                    ^
-//       |- - - - - - - - -|   |                    |
-//   1   | saved frame ptr | Fixed                  |
-//       |- - - - - - - - -| Header <-- frame ptr   |
-//   2   |     Context     |   |                    |
-//       |- - - - - - - - -|   |                    |
-//   3   |JSFunction/Marker|   v                    |
-//       +-----------------+----                    |
-//   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                    v
-//  -----+-----------------+----- <-- stack ptr ---------
+//       +-----------------+--------------------------------
+//  -n-1 |   parameter 0   |                            ^
+//       |- - - - - - - - -|                            |
+//  -n   |                 |                          Caller
+//  ...  |       ...       |                       frame slots
+//  -2   |  parameter n-1  |                       (slot < 0)
+//       |- - - - - - - - -|                            |
+//  -1   |   parameter n   |                            v
+//  -----+-----------------+--------------------------------
+//   0   |   return addr   |   ^                        ^
+//       |- - - - - - - - -|   |                        |
+//   1   | saved frame ptr | Fixed                      |
+//       |- - - - - - - - -| Header <-- frame ptr       |
+//   2   |     Context     |   |                        |
+//       |- - - - - - - - -|   |                        |
+//   3   |JSFunction/Marker|   v                        |
+//       +-----------------+----                        |
+//   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
+//  -----+-----------------+----- <-- stack ptr -------------
 //
 class Frame : public ZoneObject {
  public:
   explicit Frame(int fixed_frame_size_in_slots);
 
-  inline int GetTotalFrameSlotCount() { return frame_slot_count_; }
+  inline int GetTotalFrameSlotCount() const { return frame_slot_count_; }
 
-  inline int GetSavedCalleeRegisterSlotCount() {
-    return spilled_callee_register_slot_count_;
+  inline int GetSpToFpSlotCount() const {
+    return GetTotalFrameSlotCount() -
+           StandardFrameConstants::kFixedSlotCountAboveFp;
   }
-  inline int GetSpillSlotCount() { return stack_slot_count_; }
+  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, spilled_callee_register_slot_count_);
-    DCHECK_EQ(0, stack_slot_count_);
+    DCHECK_EQ(0, callee_saved_slot_count_);
+    DCHECK_EQ(0, spill_slot_count_);
     frame_slot_count_ = slots;
   }
 
@@ -104,34 +121,47 @@ class Frame : public ZoneObject {
     allocated_double_registers_ = regs;
   }
 
-  bool DidAllocateDoubleRegisters() {
+  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, spilled_callee_register_slot_count_);
+    DCHECK_EQ(0, callee_saved_slot_count_);
     int delta = frame_slot_count_ & 1;
     frame_slot_count_ += delta;
     return delta;
   }
 
   void AllocateSavedCalleeRegisterSlots(int count) {
+    DCHECK_EQ(0, outgoing_parameter_slot_count_);
     frame_slot_count_ += count;
-    spilled_callee_register_slot_count_ += count;
+    callee_saved_slot_count_ += count;
   }
 
   int AllocateSpillSlot(int width) {
-    DCHECK_EQ(0, spilled_callee_register_slot_count_);
+    DCHECK_EQ(0, outgoing_parameter_slot_count_);
+    DCHECK_EQ(0, callee_saved_slot_count_);
     int frame_slot_count_before = frame_slot_count_;
     int slot = AllocateAlignedFrameSlot(width);
-    stack_slot_count_ += (frame_slot_count_ - frame_slot_count_before);
+    spill_slot_count_ += (frame_slot_count_ - frame_slot_count_before);
     return slot;
   }
 
   int ReserveSpillSlots(size_t slot_count) {
-    DCHECK_EQ(0, spilled_callee_register_slot_count_);
-    DCHECK_EQ(0, stack_slot_count_);
-    stack_slot_count_ += static_cast<int>(slot_count);
+    DCHECK_EQ(0, outgoing_parameter_slot_count_);
+    DCHECK_EQ(0, callee_saved_slot_count_);
+    DCHECK_EQ(0, spill_slot_count_);
+    spill_slot_count_ += static_cast<int>(slot_count);
     frame_slot_count_ += static_cast<int>(slot_count);
     return frame_slot_count_ - 1;
   }
@@ -150,8 +180,9 @@ class Frame : public ZoneObject {
 
  private:
   int frame_slot_count_;
-  int spilled_callee_register_slot_count_;
-  int stack_slot_count_;
+  int outgoing_parameter_slot_count_;
+  int callee_saved_slot_count_;
+  int spill_slot_count_;
   BitVector* allocated_registers_;
   BitVector* allocated_double_registers_;