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llvm-6502/lib/Target/R600/SIISelLowering.cpp
Christian Konig d3b5509b80 R600/SI: add post ISel folding for SI v2 
Include immediate folding and SGPR limit handling for VOP3 instructions.

v2: remove leftover hasExtraSrcRegAllocReq

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Tom Stellard <thomas.stellard@amd.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176101 91177308-0d34-0410-b5e6-96231b3b80d8
2013-02-26 17:52:23 +00:00

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//===-- 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.
//
//===----------------------------------------------------------------------===//
//
/// \file
/// \brief Custom DAG lowering for SI
//
//===----------------------------------------------------------------------===//
#include "SIISelLowering.h"
#include "AMDIL.h"
#include "AMDILIntrinsicInfo.h"
#include "SIInstrInfo.h"
#include "SIMachineFunctionInfo.h"
#include "SIRegisterInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/SelectionDAG.h"
using namespace llvm;
SITargetLowering::SITargetLowering(TargetMachine &TM) :
AMDGPUTargetLowering(TM),
TII(static_cast<const SIInstrInfo*>(TM.getInstrInfo())),
TRI(TM.getRegisterInfo()) {
addRegisterClass(MVT::v4f32, &AMDGPU::VReg_128RegClass);
addRegisterClass(MVT::f32, &AMDGPU::VReg_32RegClass);
addRegisterClass(MVT::i32, &AMDGPU::VReg_32RegClass);
addRegisterClass(MVT::i64, &AMDGPU::SReg_64RegClass);
addRegisterClass(MVT::i1, &AMDGPU::SReg_64RegClass);
addRegisterClass(MVT::v1i32, &AMDGPU::VReg_32RegClass);
addRegisterClass(MVT::v2i32, &AMDGPU::VReg_64RegClass);
addRegisterClass(MVT::v4i32, &AMDGPU::VReg_128RegClass);
addRegisterClass(MVT::v8i32, &AMDGPU::VReg_256RegClass);
addRegisterClass(MVT::v16i32, &AMDGPU::VReg_512RegClass);
computeRegisterProperties();
setOperationAction(ISD::ADD, MVT::i64, Legal);
setOperationAction(ISD::ADD, MVT::i32, Legal);
setOperationAction(ISD::INTRINSIC_WO_CHAIN, MVT::Other, Custom);
// We need to custom lower loads from the USER_SGPR address space, so we can
// add the SGPRs as livein registers.
setOperationAction(ISD::LOAD, MVT::i32, Custom);
setOperationAction(ISD::LOAD, MVT::i64, 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 {
MachineRegisterInfo & MRI = BB->getParent()->getRegInfo();
MachineBasicBlock::iterator I = MI;
switch (MI->getOpcode()) {
default:
return AMDGPUTargetLowering::EmitInstrWithCustomInserter(MI, BB);
case AMDGPU::BRANCH: return BB;
case AMDGPU::SHADER_TYPE:
BB->getParent()->getInfo<SIMachineFunctionInfo>()->ShaderType =
MI->getOperand(0).getImm();
MI->eraseFromParent();
break;
case AMDGPU::SI_INTERP:
LowerSI_INTERP(MI, *BB, I, MRI);
break;
case AMDGPU::SI_WQM:
LowerSI_WQM(MI, *BB, I, MRI);
break;
}
return BB;
}
void SITargetLowering::LowerSI_WQM(MachineInstr *MI, MachineBasicBlock &BB,
MachineBasicBlock::iterator I, MachineRegisterInfo & MRI) const {
BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::S_WQM_B64), AMDGPU::EXEC)
.addReg(AMDGPU::EXEC);
MI->eraseFromParent();
}
void SITargetLowering::LowerSI_INTERP(MachineInstr *MI, MachineBasicBlock &BB,
MachineBasicBlock::iterator I, MachineRegisterInfo & MRI) const {
unsigned tmp = MRI.createVirtualRegister(&AMDGPU::VReg_32RegClass);
unsigned M0 = MRI.createVirtualRegister(&AMDGPU::M0RegRegClass);
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), M0)
.addOperand(params);
BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_INTERP_P1_F32), tmp)
.addOperand(iReg)
.addOperand(attr_chan)
.addOperand(attr)
.addReg(M0);
BuildMI(BB, I, BB.findDebugLoc(I), TII->get(AMDGPU::V_INTERP_P2_F32))
.addOperand(dst)
.addReg(tmp)
.addOperand(jReg)
.addOperand(attr_chan)
.addOperand(attr)
.addReg(M0);
MI->eraseFromParent();
}
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::BRCOND: return LowerBRCOND(Op, DAG);
case ISD::LOAD: return LowerLOAD(Op, DAG);
case ISD::SELECT_CC: return LowerSELECT_CC(Op, DAG);
case ISD::INTRINSIC_WO_CHAIN: {
unsigned IntrinsicID =
cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
EVT VT = Op.getValueType();
switch (IntrinsicID) {
case AMDGPUIntrinsic::SI_vs_load_buffer_index:
return CreateLiveInRegister(DAG, &AMDGPU::VReg_32RegClass,
AMDGPU::VGPR0, VT);
default: return AMDGPUTargetLowering::LowerOperation(Op, DAG);
}
break;
}
}
return SDValue();
}
/// \brief Helper function for LowerBRCOND
static SDNode *findUser(SDValue Value, unsigned Opcode) {
SDNode *Parent = Value.getNode();
for (SDNode::use_iterator I = Parent->use_begin(), E = Parent->use_end();
I != E; ++I) {
if (I.getUse().get() != Value)
continue;
if (I->getOpcode() == Opcode)
return *I;
}
return 0;
}
/// This transforms the control flow intrinsics to get the branch destination as
/// last parameter, also switches branch target with BR if the need arise
SDValue SITargetLowering::LowerBRCOND(SDValue BRCOND,
SelectionDAG &DAG) const {
DebugLoc DL = BRCOND.getDebugLoc();
SDNode *Intr = BRCOND.getOperand(1).getNode();
SDValue Target = BRCOND.getOperand(2);
SDNode *BR = 0;
if (Intr->getOpcode() == ISD::SETCC) {
// As long as we negate the condition everything is fine
SDNode *SetCC = Intr;
assert(SetCC->getConstantOperandVal(1) == 1);
assert(cast<CondCodeSDNode>(SetCC->getOperand(2).getNode())->get() ==
ISD::SETNE);
Intr = SetCC->getOperand(0).getNode();
} else {
// Get the target from BR if we don't negate the condition
BR = findUser(BRCOND, ISD::BR);
Target = BR->getOperand(1);
}
assert(Intr->getOpcode() == ISD::INTRINSIC_W_CHAIN);
// Build the result and
SmallVector<EVT, 4> Res;
for (unsigned i = 1, e = Intr->getNumValues(); i != e; ++i)
Res.push_back(Intr->getValueType(i));
// operands of the new intrinsic call
SmallVector<SDValue, 4> Ops;
Ops.push_back(BRCOND.getOperand(0));
for (unsigned i = 1, e = Intr->getNumOperands(); i != e; ++i)
Ops.push_back(Intr->getOperand(i));
Ops.push_back(Target);
// build the new intrinsic call
SDNode *Result = DAG.getNode(
Res.size() > 1 ? ISD::INTRINSIC_W_CHAIN : ISD::INTRINSIC_VOID, DL,
DAG.getVTList(Res.data(), Res.size()), Ops.data(), Ops.size()).getNode();
if (BR) {
// Give the branch instruction our target
SDValue Ops[] = {
BR->getOperand(0),
BRCOND.getOperand(2)
};
DAG.MorphNodeTo(BR, ISD::BR, BR->getVTList(), Ops, 2);
}
SDValue Chain = SDValue(Result, Result->getNumValues() - 1);
// Copy the intrinsic results to registers
for (unsigned i = 1, e = Intr->getNumValues() - 1; i != e; ++i) {
SDNode *CopyToReg = findUser(SDValue(Intr, i), ISD::CopyToReg);
if (!CopyToReg)
continue;
Chain = DAG.getCopyToReg(
Chain, DL,
CopyToReg->getOperand(1),
SDValue(Result, i - 1),
SDValue());
DAG.ReplaceAllUsesWith(SDValue(CopyToReg, 0), CopyToReg->getOperand(0));
}
// Remove the old intrinsic from the chain
DAG.ReplaceAllUsesOfValueWith(
SDValue(Intr, Intr->getNumValues() - 1),
Intr->getOperand(0));
return Chain;
}
SDValue SITargetLowering::LowerLOAD(SDValue Op, SelectionDAG &DAG) const {
EVT VT = Op.getValueType();
LoadSDNode *Ptr = dyn_cast<LoadSDNode>(Op);
assert(Ptr);
unsigned AddrSpace = Ptr->getPointerInfo().getAddrSpace();
// We only need to lower USER_SGPR address space loads
if (AddrSpace != AMDGPUAS::USER_SGPR_ADDRESS) {
return SDValue();
}
// Loads from the USER_SGPR address space can only have constant value
// pointers.
ConstantSDNode *BasePtr = dyn_cast<ConstantSDNode>(Ptr->getBasePtr());
assert(BasePtr);
unsigned TypeDwordWidth = VT.getSizeInBits() / 32;
const TargetRegisterClass * dstClass;
switch (TypeDwordWidth) {
default:
assert(!"USER_SGPR value size not implemented");
return SDValue();
case 1:
dstClass = &AMDGPU::SReg_32RegClass;
break;
case 2:
dstClass = &AMDGPU::SReg_64RegClass;
break;
}
uint64_t Index = BasePtr->getZExtValue();
assert(Index % TypeDwordWidth == 0 && "USER_SGPR not properly aligned");
unsigned SGPRIndex = Index / TypeDwordWidth;
unsigned Reg = dstClass->getRegister(SGPRIndex);
DAG.ReplaceAllUsesOfValueWith(Op, CreateLiveInRegister(DAG, dstClass, Reg,
VT));
return SDValue();
}
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();
// Possible Min/Max pattern
SDValue MinMax = LowerMinMax(Op, DAG);
if (MinMax.getNode()) {
return MinMax;
}
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();
}
/// \brief Test if RegClass is one of the VSrc classes
static bool isVSrc(unsigned RegClass) {
return AMDGPU::VSrc_32RegClassID == RegClass ||
AMDGPU::VSrc_64RegClassID == RegClass;
}
/// \brief Test if RegClass is one of the SSrc classes
static bool isSSrc(unsigned RegClass) {
return AMDGPU::SSrc_32RegClassID == RegClass ||
AMDGPU::SSrc_64RegClassID == RegClass;
}
/// \brief Analyze the possible immediate value Op
///
/// Returns -1 if it isn't an immediate, 0 if it's and inline immediate
/// and the immediate value if it's a literal immediate
int32_t SITargetLowering::analyzeImmediate(const SDNode *N) const {
union {
int32_t I;
float F;
} Imm;
if (const ConstantSDNode *Node = dyn_cast<ConstantSDNode>(N))
Imm.I = Node->getSExtValue();
else if (const ConstantFPSDNode *Node = dyn_cast<ConstantFPSDNode>(N))
Imm.F = Node->getValueAPF().convertToFloat();
else
return -1; // It isn't an immediate
if ((Imm.I >= -16 && Imm.I <= 64) ||
Imm.F == 0.5f || Imm.F == -0.5f ||
Imm.F == 1.0f || Imm.F == -1.0f ||
Imm.F == 2.0f || Imm.F == -2.0f ||
Imm.F == 4.0f || Imm.F == -4.0f)
return 0; // It's an inline immediate
return Imm.I; // It's a literal immediate
}
/// \brief Try to fold an immediate directly into an instruction
bool SITargetLowering::foldImm(SDValue &Operand, int32_t &Immediate,
bool &ScalarSlotUsed) const {
MachineSDNode *Mov = dyn_cast<MachineSDNode>(Operand);
if (Mov == 0 || !TII->isMov(Mov->getMachineOpcode()))
return false;
const SDValue &Op = Mov->getOperand(0);
int32_t Value = analyzeImmediate(Op.getNode());
if (Value == -1) {
// Not an immediate at all
return false;
} else if (Value == 0) {
// Inline immediates can always be fold
Operand = Op;
return true;
} else if (Value == Immediate) {
// Already fold literal immediate
Operand = Op;
return true;
} else if (!ScalarSlotUsed && !Immediate) {
// Fold this literal immediate
ScalarSlotUsed = true;
Immediate = Value;
Operand = Op;
return true;
}
return false;
}
/// \brief Does "Op" fit into register class "RegClass" ?
bool SITargetLowering::fitsRegClass(SelectionDAG &DAG, SDValue &Op,
unsigned RegClass) const {
MachineRegisterInfo &MRI = DAG.getMachineFunction().getRegInfo();
SDNode *Node = Op.getNode();
int OpClass;
if (MachineSDNode *MN = dyn_cast<MachineSDNode>(Node)) {
const MCInstrDesc &Desc = TII->get(MN->getMachineOpcode());
OpClass = Desc.OpInfo[Op.getResNo()].RegClass;
} else if (Node->getOpcode() == ISD::CopyFromReg) {
RegisterSDNode *Reg = cast<RegisterSDNode>(Node->getOperand(1).getNode());
OpClass = MRI.getRegClass(Reg->getReg())->getID();
} else
return false;
if (OpClass == -1)
return false;
return TRI->getRegClass(RegClass)->hasSubClassEq(TRI->getRegClass(OpClass));
}
/// \brief Make sure that we don't exeed the number of allowed scalars
void SITargetLowering::ensureSRegLimit(SelectionDAG &DAG, SDValue &Operand,
unsigned RegClass,
bool &ScalarSlotUsed) const {
// First map the operands register class to a destination class
if (RegClass == AMDGPU::VSrc_32RegClassID)
RegClass = AMDGPU::VReg_32RegClassID;
else if (RegClass == AMDGPU::VSrc_64RegClassID)
RegClass = AMDGPU::VReg_64RegClassID;
else
return;
// Nothing todo if they fit naturaly
if (fitsRegClass(DAG, Operand, RegClass))
return;
// If the scalar slot isn't used yet use it now
if (!ScalarSlotUsed) {
ScalarSlotUsed = true;
return;
}
// This is a conservative aproach, it is possible that we can't determine
// the correct register class and copy too often, but better save than sorry.
SDValue RC = DAG.getTargetConstant(RegClass, MVT::i32);
SDNode *Node = DAG.getMachineNode(TargetOpcode::COPY_TO_REGCLASS, DebugLoc(),
Operand.getValueType(), Operand, RC);
Operand = SDValue(Node, 0);
}
SDNode *SITargetLowering::PostISelFolding(MachineSDNode *Node,
SelectionDAG &DAG) const {
// Original encoding (either e32 or e64)
int Opcode = Node->getMachineOpcode();
const MCInstrDesc *Desc = &TII->get(Opcode);
unsigned NumDefs = Desc->getNumDefs();
unsigned NumOps = Desc->getNumOperands();
int32_t Immediate = Desc->getSize() == 4 ? 0 : -1;
bool HaveVSrc = false, HaveSSrc = false;
// First figure out what we alread have in this instruction
for (unsigned i = 0, e = Node->getNumOperands(), Op = NumDefs;
i != e && Op < NumOps; ++i, ++Op) {
unsigned RegClass = Desc->OpInfo[Op].RegClass;
if (isVSrc(RegClass))
HaveVSrc = true;
else if (isSSrc(RegClass))
HaveSSrc = true;
else
continue;
int32_t Imm = analyzeImmediate(Node->getOperand(i).getNode());
if (Imm != -1 && Imm != 0) {
// Literal immediate
Immediate = Imm;
}
}
// If we neither have VSrc nor SSrc it makes no sense to continue
if (!HaveVSrc && !HaveSSrc)
return Node;
// No scalar allowed when we have both VSrc and SSrc
bool ScalarSlotUsed = HaveVSrc && HaveSSrc;
// Second go over the operands and try to fold them
std::vector<SDValue> Ops;
for (unsigned i = 0, e = Node->getNumOperands(), Op = NumDefs;
i != e && Op < NumOps; ++i, ++Op) {
const SDValue &Operand = Node->getOperand(i);
Ops.push_back(Operand);
// Already folded immediate ?
if (isa<ConstantSDNode>(Operand.getNode()) ||
isa<ConstantFPSDNode>(Operand.getNode()))
continue;
// Is this a VSrc or SSrc operand ?
unsigned RegClass = Desc->OpInfo[Op].RegClass;
if (!isVSrc(RegClass) && !isSSrc(RegClass))
continue;
// Try to fold the immediates
if (!foldImm(Ops[i], Immediate, ScalarSlotUsed)) {
// Folding didn't worked, make sure we don't hit the SReg limit
ensureSRegLimit(DAG, Ops[i], RegClass, ScalarSlotUsed);
}
}
// Add optional chain and glue
for (unsigned i = NumOps - NumDefs, e = Node->getNumOperands(); i < e; ++i)
Ops.push_back(Node->getOperand(i));
// Update the instruction parameters
return DAG.UpdateNodeOperands(Node, Ops.data(), Ops.size());
}
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