path: root/src/gallium/drivers/radeon/SIISelLowering.cpp

//===-- SIISelLowering.cpp - SI DAG Lowering Implementation ---------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Most of the DAG lowering is handled in AMDGPUISelLowering.cpp.  This file is
// mostly EmitInstrWithCustomInserter().
//
//===----------------------------------------------------------------------===//

#include "SIISelLowering.h"
#include "SIInstrInfo.h"
#include "SIRegisterInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"

using namespace llvm;

SITargetLowering::SITargetLowering(TargetMachine &TM) :
    AMDGPUTargetLowering(TM),
    TII(static_cast<const SIInstrInfo*>(TM.getInstrInfo()))
{
  addRegisterClass(MVT::v4f32, &AMDGPU::VReg_128RegClass);
  addRegisterClass(MVT::f32, &AMDGPU::VReg_32RegClass);
  addRegisterClass(MVT::i32, &AMDGPU::VReg_32RegClass);
  addRegisterClass(MVT::i64, &AMDGPU::VReg_64RegClass);
  addRegisterClass(MVT::i1, &AMDGPU::SCCRegRegClass);
  addRegisterClass(MVT::i1, &AMDGPU::VCCRegRegClass);

  addRegisterClass(MVT::v4i32, &AMDGPU::SReg_128RegClass);
  addRegisterClass(MVT::v8i32, &AMDGPU::SReg_256RegClass);

  computeRegisterProperties();

  setOperationAction(ISD::AND, MVT::i1, Custom);

  setOperationAction(ISD::ADD, MVT::i64, Legal);
  setOperationAction(ISD::ADD, MVT::i32, Legal);

  setOperationAction(ISD::BR_CC, MVT::i32, Custom);

  setOperationAction(ISD::SELECT_CC, MVT::f32, Custom);
  setOperationAction(ISD::SELECT_CC, MVT::i32, Custom);

  setOperationAction(ISD::SELECT_CC, MVT::Other, Expand);
  setTargetDAGCombine(ISD::SELECT_CC);

  setTargetDAGCombine(ISD::SETCC);
}

MachineBasicBlock * SITargetLowering::EmitInstrWithCustomInserter(
    MachineInstr * MI, MachineBasicBlock * BB) const
{
  const TargetInstrInfo * TII = getTargetMachine().getInstrInfo();
  MachineRegisterInfo & MRI = BB->getParent()->getRegInfo();
  MachineBasicBlock::iterator I = MI;

  if (TII->get(MI->getOpcode()).TSFlags & SIInstrFlags::NEED_WAIT) {
    AppendS_WAITCNT(MI, *BB, llvm::next(I));
    return BB;
  }

  switch (MI->getOpcode()) {
  default:
    return AMDGPUTargetLowering::EmitInstrWithCustomInserter(MI, BB);

  case AMDGPU::CLAMP_SI:
    BuildMI(*BB, I, BB->findDebugLoc(I), TII->get(AMDGPU::V_MOV_B32_e64))
           .addOperand(MI->getOperand(0))
           .addOperand(MI->getOperand(1))
           // VSRC1-2 are unused, but we still need to fill all the
           // operand slots, so we just reuse the VSRC0 operand
           .addOperand(MI->getOperand(1))
           .addOperand(MI->getOperand(1))
           .addImm(0) // ABS
           .addImm(1) // CLAMP
           .addImm(0) // OMOD
           .addImm(0); // NEG
    MI->eraseFromParent();
    break;

  case AMDGPU::FABS_SI:
    BuildMI(*BB, I, BB->findDebugLoc(I), TII->get(AMDGPU::V_MOV_B32_e64))
                 .addOperand(MI->getOperand(0))
                 .addOperand(MI->getOperand(1))
                 // VSRC1-2 are unused, but we still need to fill all the
                 // operand slots, so we just reuse the VSRC0 operand
                 .addOperand(MI->getOperand(1))
                 .addOperand(MI->getOperand(1))
                 .addImm(1) // ABS
                 .addImm(0) // CLAMP
                 .addImm(0) // OMOD
                 .addImm(0); // NEG
    MI->eraseFromParent();
    break;

  case AMDGPU::SI_INTERP:
    LowerSI_INTERP(MI, *BB, I, MRI);
    break;
  case AMDGPU::SI_INTERP_CONST:
    LowerSI_INTERP_CONST(MI, *BB, I);
    break;
  case AMDGPU::SI_V_CNDLT:
    LowerSI_V_CNDLT(MI, *BB, I, MRI);
    break;
  case AMDGPU::USE_SGPR_32:
  case AMDGPU::USE_SGPR_64:
    lowerUSE_SGPR(MI, BB->getParent(), MRI);
    MI->eraseFromParent();
    break;
  case AMDGPU::VS_LOAD_BUFFER_INDEX:
    addLiveIn(MI, BB->getParent(), MRI, TII, AMDGPU::VGPR0);
    MI->eraseFromParent();
    break;
  }
  return BB;
}

void SITargetLowering::AppendS_WAITCNT(MachineInstr *MI, MachineBasicBlock &BB,
    MachineBasicBlock::iterator I) const
{
  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::S_WAITCNT))
          .addImm(0);
}

void SITargetLowering::LowerSI_INTERP(MachineInstr *MI, MachineBasicBlock &BB,
    MachineBasicBlock::iterator I, MachineRegisterInfo & MRI) const
{
  unsigned tmp = MRI.createVirtualRegister(&AMDGPU::VReg_32RegClass);
  MachineOperand dst = MI->getOperand(0);
  MachineOperand iReg = MI->getOperand(1);
  MachineOperand jReg = MI->getOperand(2);
  MachineOperand attr_chan = MI->getOperand(3);
  MachineOperand attr = MI->getOperand(4);
  MachineOperand params = MI->getOperand(5);

  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::S_MOV_B32))
          .addReg(AMDGPU::M0)
          .addOperand(params);

  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_INTERP_P1_F32), tmp)
          .addOperand(iReg)
          .addOperand(attr_chan)
          .addOperand(attr);

  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_INTERP_P2_F32))
          .addOperand(dst)
          .addReg(tmp)
          .addOperand(jReg)
          .addOperand(attr_chan)
          .addOperand(attr);

  MI->eraseFromParent();
}

void SITargetLowering::LowerSI_INTERP_CONST(MachineInstr *MI,
    MachineBasicBlock &BB, MachineBasicBlock::iterator I) const
{
  MachineOperand dst = MI->getOperand(0);
  MachineOperand attr_chan = MI->getOperand(1);
  MachineOperand attr = MI->getOperand(2);
  MachineOperand params = MI->getOperand(3);

  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::S_MOV_B32))
          .addReg(AMDGPU::M0)
          .addOperand(params);

  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_INTERP_MOV_F32))
          .addOperand(dst)
          .addOperand(attr_chan)
          .addOperand(attr);

  MI->eraseFromParent();
}

void SITargetLowering::LowerSI_V_CNDLT(MachineInstr *MI, MachineBasicBlock &BB,
    MachineBasicBlock::iterator I, MachineRegisterInfo & MRI) const
{
  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_CMP_LT_F32_e32))
          .addOperand(MI->getOperand(1))
          .addReg(AMDGPU::SREG_LIT_0);

  BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_CNDMASK_B32))
          .addOperand(MI->getOperand(0))
          .addOperand(MI->getOperand(2))
          .addOperand(MI->getOperand(3));

  MI->eraseFromParent();
}

void SITargetLowering::lowerUSE_SGPR(MachineInstr *MI,
    MachineFunction * MF, MachineRegisterInfo & MRI) const
{
  const TargetInstrInfo * TII = getTargetMachine().getInstrInfo();
  unsigned dstReg = MI->getOperand(0).getReg();
  int64_t newIndex = MI->getOperand(1).getImm();
  const TargetRegisterClass * dstClass = MRI.getRegClass(dstReg);
  unsigned DwordWidth = dstClass->getSize() / 4;
  assert(newIndex % DwordWidth == 0 && "USER_SGPR not properly aligned");
  newIndex = newIndex / DwordWidth;

  unsigned newReg = dstClass->getRegister(newIndex);
  addLiveIn(MI, MF, MRI, TII, newReg); 
}

EVT SITargetLowering::getSetCCResultType(EVT VT) const
{
  return MVT::i1;
}

//===----------------------------------------------------------------------===//
// Custom DAG Lowering Operations
//===----------------------------------------------------------------------===//

SDValue SITargetLowering::LowerOperation(SDValue Op, SelectionDAG &DAG) const
{
  switch (Op.getOpcode()) {
  default: return AMDGPUTargetLowering::LowerOperation(Op, DAG);
  case ISD::BR_CC: return LowerBR_CC(Op, DAG);
  case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
  case ISD::AND: return Loweri1ContextSwitch(Op, DAG, ISD::AND);
  }
}

/// Loweri1ContextSwitch - The function is for lowering i1 operations on the
/// VCC register.  In the VALU context, VCC is a one bit register, but in the
/// SALU context the VCC is a 64-bit register (1-bit per thread).  Since only
/// the SALU can perform operations on the VCC register, we need to promote
/// the operand types from i1 to i64 in order for tablegen to be able to match
/// this operation to the correct SALU instruction.  We do this promotion by
/// wrapping the operands in a CopyToReg node.
///
SDValue SITargetLowering::Loweri1ContextSwitch(SDValue Op,
                                               SelectionDAG &DAG,
                                               unsigned VCCNode) const
{
  DebugLoc DL = Op.getDebugLoc();

  SDValue OpNode = DAG.getNode(VCCNode, DL, MVT::i64,
                               DAG.getNode(SIISD::VCC_BITCAST, DL, MVT::i64,
                                           Op.getOperand(0)),
                               DAG.getNode(SIISD::VCC_BITCAST, DL, MVT::i64,
                                           Op.getOperand(1)));

  return DAG.getNode(SIISD::VCC_BITCAST, DL, MVT::i1, OpNode);
}

SDValue SITargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) const
{
  SDValue Chain = Op.getOperand(0);
  SDValue CC = Op.getOperand(1);
  SDValue LHS   = Op.getOperand(2);
  SDValue RHS   = Op.getOperand(3);
  SDValue JumpT  = Op.getOperand(4);
  SDValue CmpValue;
  SDValue Result;
  CmpValue = DAG.getNode(
      ISD::SETCC,
      Op.getDebugLoc(),
      MVT::i1,
      LHS, RHS,
      CC);

  Result = DAG.getNode(
      AMDILISD::BRANCH_COND,
      CmpValue.getDebugLoc(),
      MVT::Other, Chain,
      JumpT, CmpValue);
  return Result;
}

SDValue SITargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const
{
  SDValue LHS = Op.getOperand(0);
  SDValue RHS = Op.getOperand(1);
  SDValue True = Op.getOperand(2);
  SDValue False = Op.getOperand(3);
  SDValue CC = Op.getOperand(4);
  EVT VT = Op.getValueType();
  DebugLoc DL = Op.getDebugLoc();

  SDValue Cond = DAG.getNode(ISD::SETCC, DL, MVT::i1, LHS, RHS, CC);
  return DAG.getNode(ISD::SELECT, DL, VT, Cond, True, False);
}

//===----------------------------------------------------------------------===//
// Custom DAG optimizations
//===----------------------------------------------------------------------===//

SDValue SITargetLowering::PerformDAGCombine(SDNode *N,
                                            DAGCombinerInfo &DCI) const {
  SelectionDAG &DAG = DCI.DAG;
  DebugLoc DL = N->getDebugLoc();
  EVT VT = N->getValueType(0);

  switch (N->getOpcode()) {
    default: break;
    case ISD::SELECT_CC: {
      N->dump();
      ConstantSDNode *True, *False;
      // i1 selectcc(l, r, -1, 0, cc) -> i1 setcc(l, r, cc)
      if ((True = dyn_cast<ConstantSDNode>(N->getOperand(2)))
          && (False = dyn_cast<ConstantSDNode>(N->getOperand(3)))
          && True->isAllOnesValue()
          && False->isNullValue()
          && VT == MVT::i1) {
        return DAG.getNode(ISD::SETCC, DL, VT, N->getOperand(0),
                           N->getOperand(1), N->getOperand(4));

      }
      break;
    }
    case ISD::SETCC: {
      SDValue Arg0 = N->getOperand(0);
      SDValue Arg1 = N->getOperand(1);
      SDValue CC = N->getOperand(2);
      ConstantSDNode * C = NULL;
      ISD::CondCode CCOp = dyn_cast<CondCodeSDNode>(CC)->get();

      // i1 setcc (sext(i1), 0, setne) -> i1 setcc(i1, 0, setne)
      if (VT == MVT::i1
          && Arg0.getOpcode() == ISD::SIGN_EXTEND
          && Arg0.getOperand(0).getValueType() == MVT::i1
          && (C = dyn_cast<ConstantSDNode>(Arg1))
          && C->isNullValue()
          && CCOp == ISD::SETNE) {
        return SimplifySetCC(VT, Arg0.getOperand(0),
                             DAG.getConstant(0, MVT::i1), CCOp, true, DCI, DL);
      }
      break;
    }
  }
  return SDValue();
}

#define NODE_NAME_CASE(node) case SIISD::node: return #node;

const char* SITargetLowering::getTargetNodeName(unsigned Opcode) const
{
  switch (Opcode) {
  default: return AMDGPUTargetLowering::getTargetNodeName(Opcode);
  NODE_NAME_CASE(VCC_AND)
  NODE_NAME_CASE(VCC_BITCAST)
  }
}