//===------- VmkitGC.cpp - GC for JIT-generated functions -----------------===//
//
//                     The VMKit project
//
// This file is distributed under the University of Illinois Open Source 
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//


#include "llvm/CodeGen/GCs.h"
#include "llvm/CodeGen/GCStrategy.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/MC/MCContext.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Target/TargetInstrInfo.h"

#include "vmkit/JIT.h"

using namespace llvm;

namespace {
  class VmkitGC : public GCStrategy {
  public:
    VmkitGC();
    bool findCustomSafePoints(GCFunctionInfo& FI, MachineFunction &MF);
  };
}

namespace vmkit {
  void linkVmkitGC() { }
}

static GCRegistry::Add<VmkitGC>
X("vmkit", "VMKit GC for JIT-generated functions");

VmkitGC::VmkitGC() {
  CustomSafePoints = true;
}

static MCSymbol *InsertLabel(MachineBasicBlock &MBB, 
                             MachineBasicBlock::iterator MI,
                             DebugLoc DL) {
  const TargetInstrInfo* TII = MBB.getParent()->getTarget().getInstrInfo();
  MCSymbol *Label = MBB.getParent()->getContext().CreateTempSymbol();
  BuildMI(MBB, MI, DL, TII->get(TargetOpcode::GC_LABEL)).addSym(Label);
  return Label;
}


bool VmkitGC::findCustomSafePoints(GCFunctionInfo& FI, MachineFunction &MF) {
  for (MachineFunction::iterator BBI = MF.begin(),
                                 BBE = MF.end(); BBI != BBE; ++BBI) {
    for (MachineBasicBlock::iterator MI = BBI->begin(),
                                     ME = BBI->end(); MI != ME; ++MI) {
      if (MI->getDesc().isCall()) {
        MachineBasicBlock::iterator RAI = MI; ++RAI;                                
        MCSymbol* Label = InsertLabel(*MI->getParent(), RAI, MI->getDebugLoc());
        FI.addSafePoint(GC::PostCall, Label, MI->getDebugLoc());
      } else if (MI->getDebugLoc().getCol() == 1) {
        MCSymbol* Label = InsertLabel(*MI->getParent(), MI, MI->getDebugLoc());
        FI.addSafePoint(GC::Loop, Label, MI->getDebugLoc());
      }
    }
  }
  return false;
}