path: root/lib/Target/X86/InstSelectSimple.cpp

//===-- InstSelectSimple.cpp - A simple instruction selector for x86 ------===//
//
// This file defines a simple peephole instruction selector for the x86 platform
//
//===----------------------------------------------------------------------===//

#include "X86.h"
#include "X86InstrInfo.h"
#include "X86InstrBuilder.h"
#include "llvm/Function.h"
#include "llvm/iTerminators.h"
#include "llvm/iOperators.h"
#include "llvm/iOther.h"
#include "llvm/iPHINode.h"
#include "llvm/iMemory.h"
#include "llvm/Type.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Constants.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Target/MRegisterInfo.h"
#include <map>

using namespace MOTy;  // Get Use, Def, UseAndDef


/// BMI - A special BuildMI variant that takes an iterator to insert the
/// instruction at as well as a basic block.
/// this is the version for when you have a destination register in mind.
inline static MachineInstrBuilder BMI(MachineBasicBlock *MBB,
                                      MachineBasicBlock::iterator &I,
                                      MachineOpCode Opcode,
                                      unsigned NumOperands,
                                      unsigned DestReg) {
  assert(I >= MBB->begin() && I <= MBB->end() && "Bad iterator!");
  MachineInstr *MI = new MachineInstr(Opcode, NumOperands+1, true, true);
  I = ++MBB->insert(I, MI);
  return MachineInstrBuilder(MI).addReg(DestReg, MOTy::Def);
}

/// BMI - A special BuildMI variant that takes an iterator to insert the
/// instruction at as well as a basic block.
inline static MachineInstrBuilder BMI(MachineBasicBlock *MBB,
                                      MachineBasicBlock::iterator &I,
                                      MachineOpCode Opcode,
                                      unsigned NumOperands) {
  assert(I > MBB->begin() && I <= MBB->end() && "Bad iterator!");
  MachineInstr *MI = new MachineInstr(Opcode, NumOperands, true, true);
  I = ++MBB->insert(I, MI);
  return MachineInstrBuilder(MI);
}


namespace {
  struct ISel : public FunctionPass, InstVisitor<ISel> {
    TargetMachine &TM;
    MachineFunction *F;                    // The function we are compiling into
    MachineBasicBlock *BB;                 // The current MBB we are compiling

    unsigned CurReg;
    std::map<Value*, unsigned> RegMap;  // Mapping between Val's and SSA Regs

    // MBBMap - Mapping between LLVM BB -> Machine BB
    std::map<const BasicBlock*, MachineBasicBlock*> MBBMap;

    ISel(TargetMachine &tm)
      : TM(tm), F(0), BB(0), CurReg(MRegisterInfo::FirstVirtualRegister) {}

    /// runOnFunction - Top level implementation of instruction selection for
    /// the entire function.
    ///
    bool runOnFunction(Function &Fn) {
      F = &MachineFunction::construct(&Fn, TM);

      for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
        F->getBasicBlockList().push_back(MBBMap[I] = new MachineBasicBlock(I));

      // Emit instructions to load the arguments...  The function's arguments
      // look like this:
      //
      // [EBP]     -- copy of old EBP
      // [EBP + 4] -- return address
      // [EBP + 8] -- first argument (leftmost lexically)
      //
      // So we want to start with counter = 2.
      //
      BB = &F->front();
      unsigned ArgOffset = 8;
      for (Function::aiterator I = Fn.abegin(), E = Fn.aend(); I != E;
           ++I, ArgOffset += 4