lib/Target/Sparc/InstSelectSimple.cpp

//===-- InstSelectSimple.cpp - A simple instruction selector for SparcV8 --===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
// 
//===----------------------------------------------------------------------===//
//
// This file defines a simple peephole instruction selector for the V8 target
//
//===----------------------------------------------------------------------===//

#include "SparcV8.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicLowering.h"
#include "llvm/Pass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/GetElementPtrTypeIterator.h"
#include "llvm/Support/InstVisitor.h"
#include "llvm/Support/CFG.h"
using namespace llvm;

namespace {
  struct V8ISel : public FunctionPass, public InstVisitor<V8ISel> {
    TargetMachine &TM;
    MachineFunction *F;                 // The function we are compiling into
    MachineBasicBlock *BB;              // The current MBB we are compiling

    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;

    V8ISel(TargetMachine &tm) : TM(tm), F(0), BB(0) {}

    /// runOnFunction - Top level implementation of instruction selection for
    /// the entire function.
    ///
    bool runOnFunction(Function &Fn);

    virtual const char *getPassName() const {
      return "SparcV8 Simple Instruction Selection";
    }

    /// visitBasicBlock - This method is called when we are visiting a new basic
    /// block.  This simply creates a new MachineBasicBlock to emit code into
    /// and adds it to the current MachineFunction.  Subsequent visit* for
    /// instructions will be invoked for all instructions in the basic block.
    ///
    void visitBasicBlock(BasicBlock &LLVM_BB) {
      BB = MBBMap[&LLVM_BB];
    }

    void visitReturnInst(ReturnInst &RI);

    void visitInstruction(Instruction &I) {
      std::cerr << "Unhandled instruction: " << I;
      abort();
    }

    /// LowerUnknownIntrinsicFunctionCalls - This performs a prepass over the
    /// function, lowering any calls to unknown intrinsic functions into the
    /// equivalent LLVM code.
    void LowerUnknownIntrinsicFunctionCalls(Function &F);


    void visitIntrinsicCall(Intrinsic::ID ID, CallInst &CI);

  };
}

FunctionPass *llvm::createSparcV8SimpleInstructionSelector(TargetMachine &TM) {
  return new V8ISel(TM);
}


bool V8ISel::runOnFunction(Function &Fn) {
  // First pass over the function, lower any unknown intrinsic functions
  // with the IntrinsicLowering class.
  LowerUnknownIntrinsicFunctionCalls(Fn);
  
  F = &MachineFunction::construct(&Fn, TM);
  
  // Create all of the machine basic blocks for the function...
  for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
    F->getBasicBlockList().push_back(MBBMap[I] = new MachineBasicBlock(I));
  
  BB = &F->front();
  
  // Set up a frame object for the return address.  This is used by the
  // llvm.returnaddress & llvm.frameaddress intrinisics.
  //ReturnAddressIndex = F->getFrameInfo()->CreateFixedObject(4, -4);
  
  // Copy incoming arguments off of the stack and out of fixed registers.
  //LoadArgumentsToVirtualRegs(Fn);
  
  // Instruction select everything except PHI nodes
  visit(Fn);
  
  // Select the PHI nodes
  //SelectPHINodes();
  
  RegMap.clear();
  MBBMap.clear();
  F = 0;
  // We always build a machine code representation for the function
  return true;
}


void V8ISel::visitReturnInst(ReturnInst &I) {
  if (I.getNumOperands() == 0) {
    // Just emit a 'ret' instruction
    BuildMI(BB, V8::JMPLi, 2, V8::G0).addZImm(8).addReg(V8::I7);
    return;
  }
  visitInstruction(I);
}


/// LowerUnknownIntrinsicFunctionCalls - This performs a prepass over the
/// function, lowering any calls to unknown intrinsic functions into the
/// equivalent LLVM code.
void V8ISel::LowerUnknownIntrinsicFunctionCalls(Function &F) {
  for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
    for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; )
      if (CallInst *CI = dyn_cast<CallInst>(I++))
        if (Function *F = CI->getCalledFunction())
          switch (F->getIntrinsicID()) {
          case Intrinsic::not_intrinsic: break;
          default:
            // All other intrinsic calls we must lower.
            Instruction *Before = CI->getPrev();
            TM.getIntrinsicLowering().LowerIntrinsicCall(CI);
            if (Before) {        // Move iterator to instruction after call
              I = Before;  ++I;
            } else {
              I = BB->begin();
            }
          }
}


void V8ISel::visitIntrinsicCall(Intrinsic::ID ID, CallInst &CI) {
  unsigned TmpReg1, TmpReg2;
  switch (ID) {
  default: assert(0 && "Intrinsic not supported!");
  }
}