//===- StackSlots.cpp  - Specialize LLVM code for target machine ---------===//
//
// This pass adds 2 empty slots at the top of function stack.  These two slots
// are later used during code reoptimization for spilling the register values
// when rewriting branches.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/StackSlots.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/MachineInstrInfo.h"
#include "llvm/Constant.h"
#include "llvm/Function.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/MachineCodeForMethod.h"

class StackSlots : public FunctionPass {
  const TargetMachine &Target;
public:
  StackSlots (const TargetMachine &T) : Target(T) {}

  const char *getPassName() const {
    return "Stack Slot Insertion for profiling code";
  }

  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
    AU.setPreservesCFG();
  }

  bool runOnFunction(Function &F) {
    const Type *PtrInt = PointerType::get(Type::IntTy);
    unsigned Size = Target.DataLayout.getTypeSize(PtrInt);

    MachineCodeForMethod &mcInfo = MachineCodeForMethod::get(&F);
    Value *V = Constant::getNullValue(Type::IntTy);
    mcInfo.allocateLocalVar(Target, V, 2*Size);
    return true;
  }
};

Pass *createStackSlotsPass(const TargetMachine &Target) {
  return new StackSlots(Target);
}