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//===-- CSKYISelDAGToDAG.cpp - A dag to dag inst selector for CSKY---------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines an instruction selector for the CSKY target.
//
//===----------------------------------------------------------------------===//
#include "CSKY.h"
#include "CSKYSubtarget.h"
#include "CSKYTargetMachine.h"
#include "MCTargetDesc/CSKYMCTargetDesc.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
using namespace llvm;
#define DEBUG_TYPE "csky-isel"
namespace {
class CSKYDAGToDAGISel : public SelectionDAGISel {
const CSKYSubtarget *Subtarget;
public:
explicit CSKYDAGToDAGISel(CSKYTargetMachine &TM) : SelectionDAGISel(TM) {}
StringRef getPassName() const override {
return "CSKY DAG->DAG Pattern Instruction Selection";
}
bool runOnMachineFunction(MachineFunction &MF) override {
// Reset the subtarget each time through.
Subtarget = &MF.getSubtarget<CSKYSubtarget>();
SelectionDAGISel::runOnMachineFunction(MF);
return true;
}
void Select(SDNode *N) override;
bool selectAddCarry(SDNode *N);
bool selectSubCarry(SDNode *N);
#include "CSKYGenDAGISel.inc"
};
} // namespace
void CSKYDAGToDAGISel::Select(SDNode *N) {
// If we have a custom node, we have already selected
if (N->isMachineOpcode()) {
LLVM_DEBUG(dbgs() << "== "; N->dump(CurDAG); dbgs() << "\n");
N->setNodeId(-1);
return;
}
SDLoc Dl(N);
unsigned Opcode = N->getOpcode();
bool IsSelected = false;
switch (Opcode) {
default:
break;
case ISD::ADDCARRY:
IsSelected = selectAddCarry(N);
break;
case ISD::SUBCARRY:
IsSelected = selectSubCarry(N);
break;
case ISD::GLOBAL_OFFSET_TABLE: {
Register GP = Subtarget->getInstrInfo()->getGlobalBaseReg(*MF);
ReplaceNode(N, CurDAG->getRegister(GP, N->getValueType(0)).getNode());
IsSelected = true;
break;
}
case ISD::FrameIndex: {
SDValue Imm = CurDAG->getTargetConstant(0, Dl, MVT::i32);
int FI = cast<FrameIndexSDNode>(N)->getIndex();
SDValue TFI = CurDAG->getTargetFrameIndex(FI, MVT::i32);
ReplaceNode(N, CurDAG->getMachineNode(Subtarget->hasE2() ? CSKY::ADDI32
: CSKY::ADDI16XZ,
Dl, MVT::i32, TFI, Imm));
IsSelected = true;
break;
}
}
if (IsSelected)
return;
// Select the default instruction.
SelectCode(N);
}
bool CSKYDAGToDAGISel::selectAddCarry(SDNode *N) {
MachineSDNode *NewNode = nullptr;
auto Type0 = N->getValueType(0);
auto Type1 = N->getValueType(1);
auto Op0 = N->getOperand(0);
auto Op1 = N->getOperand(1);
auto Op2 = N->getOperand(2);
SDLoc Dl(N);
if (isNullConstant(Op2)) {
auto *CA = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::CLRC32 : CSKY::CLRC16, Dl, Type1);
NewNode = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::ADDC32 : CSKY::ADDC16, Dl, {Type0, Type1},
{Op0, Op1, SDValue(CA, 0)});
} else if (isOneConstant(Op2)) {
auto *CA = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::SETC32 : CSKY::SETC16, Dl, Type1);
NewNode = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::ADDC32 : CSKY::ADDC16, Dl, {Type0, Type1},
{Op0, Op1, SDValue(CA, 0)});
} else {
NewNode = CurDAG->getMachineNode(Subtarget->has2E3() ? CSKY::ADDC32
: CSKY::ADDC16,
Dl, {Type0, Type1}, {Op0, Op1, Op2});
}
ReplaceNode(N, NewNode);
return true;
}
static SDValue InvertCarryFlag(const CSKYSubtarget *Subtarget,
SelectionDAG *DAG, SDLoc Dl, SDValue OldCarry) {
auto NewCarryReg =
DAG->getMachineNode(Subtarget->has2E3() ? CSKY::MVCV32 : CSKY::MVCV16, Dl,
MVT::i32, OldCarry);
auto NewCarry =
DAG->getMachineNode(Subtarget->hasE2() ? CSKY::BTSTI32 : CSKY::BTSTI16,
Dl, OldCarry.getValueType(), SDValue(NewCarryReg, 0),
DAG->getTargetConstant(0, Dl, MVT::i32));
return SDValue(NewCarry, 0);
}
bool CSKYDAGToDAGISel::selectSubCarry(SDNode *N) {
MachineSDNode *NewNode = nullptr;
auto Type0 = N->getValueType(0);
auto Type1 = N->getValueType(1);
auto Op0 = N->getOperand(0);
auto Op1 = N->getOperand(1);
auto Op2 = N->getOperand(2);
SDLoc Dl(N);
if (isNullConstant(Op2)) {
auto *CA = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::SETC32 : CSKY::SETC16, Dl, Type1);
NewNode = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::SUBC32 : CSKY::SUBC16, Dl, {Type0, Type1},
{Op0, Op1, SDValue(CA, 0)});
} else if (isOneConstant(Op2)) {
auto *CA = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::CLRC32 : CSKY::CLRC16, Dl, Type1);
NewNode = CurDAG->getMachineNode(
Subtarget->has2E3() ? CSKY::SUBC32 : CSKY::SUBC16, Dl, {Type0, Type1},
{Op0, Op1, SDValue(CA, 0)});
} else {
auto CarryIn = InvertCarryFlag(Subtarget, CurDAG, Dl, Op2);
NewNode = CurDAG->getMachineNode(Subtarget->has2E3() ? CSKY::SUBC32
: CSKY::SUBC16,
Dl, {Type0, Type1}, {Op0, Op1, CarryIn});
}
auto CarryOut = InvertCarryFlag(Subtarget, CurDAG, Dl, SDValue(NewNode, 1));
ReplaceUses(SDValue(N, 0), SDValue(NewNode, 0));
ReplaceUses(SDValue(N, 1), CarryOut);
CurDAG->RemoveDeadNode(N);
return true;
}
FunctionPass *llvm::createCSKYISelDag(CSKYTargetMachine &TM) {
return new CSKYDAGToDAGISel(TM);
}
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