[turbofan] Implement tail calls with differing stack parameter counts

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"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Collects the spill slot requirements and the allocated general and double
 // registers 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.
 class Frame : public ZoneObject {
  public:
-  Frame()
-      : register_save_area_size_(0),
+  explicit Frame(bool needs_frame)
+      : needs_frame_(needs_frame),
+        register_save_area_size_(0),
         spill_slot_count_(0),
+        max_tail_call_stack_delta_(0),
         osr_stack_slot_count_(0),
         allocated_registers_(NULL),
         allocated_double_registers_(NULL) {}
 
-  inline int GetSpillSlotCount() { return spill_slot_count_; }
+  inline int GetSpillSlotCount() const { return spill_slot_count_; }
+
+  inline int GetFrameSlotCount() const {
+    if (needs_frame_ || spill_slot_count_ > 0) {
+      return std::max(spill_slot_count_, max_tail_call_stack_delta_);
+    }
+    return 0;
+  }
+
+  inline void MarkNeedsFrame() { needs_frame_ = true; }
+  inline bool NeedsFrame() const { return needs_frame_; }
 
   void SetAllocatedRegisters(BitVector* regs) {
     DCHECK(allocated_registers_ == NULL);
     allocated_registers_ = regs;
   }
 
   void SetAllocatedDoubleRegisters(BitVector* regs) {
     DCHECK(allocated_double_registers_ == NULL);
     allocated_double_registers_ = regs;
   }
@@ skipping 12 matching lines @@
   // OSR stack slots, including locals and expression stack slots.
   void SetOsrStackSlotCount(int slots) {
     DCHECK(slots >= 0);
     osr_stack_slot_count_ = slots;
   }
 
   int GetOsrStackSlotCount() { return osr_stack_slot_count_; }
 
   int AllocateSpillSlot(int width) {
     DCHECK(width == 4 || width == 8);
+    needs_frame_ = true;
     // Skip one slot if necessary.
     if (width > kPointerSize) {
       DCHECK(width == kPointerSize * 2);
       spill_slot_count_++;
       spill_slot_count_ |= 1;
     }
     return spill_slot_count_++;
   }
 
   void ReserveSpillSlots(size_t slot_count) {
     DCHECK_EQ(0, spill_slot_count_);  // can only reserve before allocation.
+    needs_frame_ = true;
     spill_slot_count_ = static_cast<int>(slot_count);
   }
 
+  void UpdateMaxTailCallStackDelta(int stack_delta) {
+    if (stack_delta > max_tail_call_stack_delta_) {
+      max_tail_call_stack_delta_ = stack_delta;
+    }
+  }
+  int max_tail_call_stack_delta() { return max_tail_call_stack_delta_; }
+
  private:
+  bool needs_frame_;
   int register_save_area_size_;
   int spill_slot_count_;
+  int max_tail_call_stack_delta_;
   int osr_stack_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.
 class FrameOffset {
@@ skipping 18 matching lines @@
   int offset_;  // Encodes SP or FP in the low order bit.
 
   static const int kFromSp = 1;
   static const int kFromFp = 0;
 };
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_COMPILER_FRAME_H_