[turbofan] CodeGenerator: Frame setup refactoring

src/compiler/frame.h

Index: src/compiler/frame.h
diff --git a/src/compiler/frame.h b/src/compiler/frame.h
index da371c3067d41ce79abb8f72c0ea7ddc8283c393..de2ae1a3c23f57c32c3430a7e274ab0187f2f01a 100644
--- a/src/compiler/frame.h
+++ b/src/compiler/frame.h
@@ -82,9 +82,6 @@ class Frame : public ZoneObject {
 
   inline int GetTotalFrameSlotCount() const { return frame_slot_count_; }
 
-  inline int GetSavedCalleeRegisterSlotCount() const {
-    return callee_saved_slot_count_;
-  }
   inline int GetSpillSlotCount() const { return spill_slot_count_; }
 
   void SetAllocatedRegisters(BitVector* regs) {
@@ -101,23 +98,20 @@ class Frame : public ZoneObject {
     return !allocated_double_registers_->IsEmpty();
   }
 
-  int AlignSavedCalleeRegisterSlots(int alignment = kDoubleSize) {
-    DCHECK_EQ(0, callee_saved_slot_count_);
+  void AlignSavedCalleeRegisterSlots(int alignment = kDoubleSize) {
     int alignment_slots = alignment / kPointerSize;
     int delta = alignment_slots - (frame_slot_count_ & (alignment_slots - 1));
     if (delta != alignment_slots) {
       frame_slot_count_ += delta;
     }
-    return delta;
+    spill_slot_count_ += delta;

[Mircea Trofin, 2016/04/16 04:25:10]

Note to reviewers: I am not very happy with this. On one hand, aligning here
does change the layout of the
frame, and in a sense, it does this by adding unused spill slots. On the other
hand, I would prefer the 
number of actual spill slots be remembered. I'm concerned with potential access
by the runtime into these
padding slots.

Thoughts?

[Mircea Trofin, 2016/04/16 15:25:43]

FWIW, I see we do the same in AlignFrame. Still, is there any merit to my
concern?

   }
 
   void AllocateSavedCalleeRegisterSlots(int count) {
     frame_slot_count_ += count;
-    callee_saved_slot_count_ += count;
   }
 
   int AllocateSpillSlot(int width) {
-    DCHECK_EQ(0, callee_saved_slot_count_);
     int frame_slot_count_before = frame_slot_count_;
     int slot = AllocateAlignedFrameSlot(width);
     spill_slot_count_ += (frame_slot_count_ - frame_slot_count_before);
@@ -127,7 +121,6 @@ class Frame : public ZoneObject {
   int AlignFrame(int alignment = kDoubleSize);
 
   int ReserveSpillSlots(size_t 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);
@@ -151,7 +144,6 @@ class Frame : public ZoneObject {
 
  private:
   int frame_slot_count_;
-  int callee_saved_slot_count_;
   int spill_slot_count_;
   BitVector* allocated_registers_;
   BitVector* allocated_double_registers_;
@@ -190,13 +182,13 @@ class FrameOffset {
 // current function's frame.
 class FrameAccessState : public ZoneObject {
  public:
-  explicit FrameAccessState(Frame* const frame)
+  explicit FrameAccessState(const Frame* const frame)
       : frame_(frame),
         access_frame_with_fp_(false),
         sp_delta_(0),
         has_frame_(false) {}
 
-  Frame* frame() const { return frame_; }
+  const Frame* frame() const { return frame_; }
   void MarkHasFrame(bool state);
 
   int sp_delta() const { return sp_delta_; }
@@ -228,7 +220,7 @@ class FrameAccessState : public ZoneObject {
   FrameOffset GetFrameOffset(int spill_slot) const;
 
  private:
-  Frame* const frame_;
+  const Frame* const frame_;
   bool access_frame_with_fp_;
   int sp_delta_;
   bool has_frame_;