[v8-dev] ARM: safepoints frame optimization

src/lithium-allocator.h

 // Copyright 2012 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
@@ skipping 443 matching lines @@
 #ifdef DEBUG
   void Verify() const;
 #endif
 
   BitVector* assigned_registers() {
     return assigned_registers_;
   }
   BitVector* assigned_double_registers() {
     return assigned_double_registers_;
   }
+  RegList modified_registers() {
+    return modified_registers_;
+  }
+  RegList modified_double_registers() {
+    return modified_double_registers_;
+  }
 
  private:
   void MeetRegisterConstraints();
   void ResolvePhis();
   void BuildLiveRanges();
   void AllocateGeneralRegisters();
   void AllocateDoubleRegisters();
   void ConnectRanges();
   void ResolveControlFlow();
   void PopulatePointerMaps();
@@ skipping 143 matching lines @@
   int next_virtual_register_;
   int first_artificial_register_;
   GrowableBitVector double_artificial_registers_;
 
   RegisterKind mode_;
   int num_registers_;
 
   BitVector* assigned_registers_;
   BitVector* assigned_double_registers_;
 
+  // modified_registers_ and modified_double_registers_ hold the registers
+  // which are really used by the function. assigned_registers_ and
+  // assigned_double_registers_ hold the registers which are used by the
+  // registers allocator. Each time a function is called, the register
+  // allocator tells that all the allocatable registers are used by this call.
+  // That means that, most of the time assigned_xxx are not relevant (they
+  // hold all the allocatable registers).
+  // TODO(all): check if we can use modified_xxx everywhere instead of
+  // assigned_xxx.
+  RegList modified_registers_;
+  RegList modified_double_registers_;
+
   HGraph* graph_;
 
   bool has_osr_entry_;
 
   // Indicates success or failure during register allocation.
   bool allocation_ok_;
 
 #ifdef DEBUG
   LifetimePosition allocation_finger_;
 #endif
@@ skipping 11 matching lines @@
   LAllocator* allocator_;
   unsigned allocator_zone_start_allocation_size_;
 
   DISALLOW_COPY_AND_ASSIGN(LAllocatorPhase);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_LITHIUM_ALLOCATOR_H_