//===-- Nios2ISelLowering.cpp - Nios2 DAG Lowering Implementation ---------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the interfaces that Nios2 uses to lower LLVM code into a
// selection DAG.
//
//===----------------------------------------------------------------------===//
#include "Nios2ISelLowering.h"
#include "Nios2MachineFunction.h"
#include "Nios2TargetMachine.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
using namespace llvm;
//===----------------------------------------------------------------------===//
// Calling Convention Implementation
//===----------------------------------------------------------------------===//
#include "Nios2GenCallingConv.inc"
SDValue
Nios2TargetLowering::LowerReturn(SDValue Chain, CallingConv::ID CallConv,
bool IsVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
const SmallVectorImpl<SDValue> &OutVals,
const SDLoc &DL, SelectionDAG &DAG) const {
// CCValAssign - represent the assignment of
// the return value to a location
SmallVector<CCValAssign, 16> RVLocs;
MachineFunction &MF = DAG.getMachineFunction();
// CCState - Info about the registers and stack slot.
CCState CCInfo(CallConv, IsVarArg, MF, RVLocs, *DAG.getContext());
// Analyze return values.
CCInfo.CheckReturn(Outs, RetCC_Nios2EABI);
SDValue Flag;
SmallVector<SDValue, 4> RetOps(1, Chain);
// Copy the result values into the output registers.
for (unsigned i = 0; i != RVLocs.size(); ++i) {
SDValue Val = OutVals[i];
CCValAssign &VA = RVLocs[i];
assert(VA.isRegLoc() && "Can only return in registers!");
if (RVLocs[i].getValVT() != RVLocs[i].getLocVT())
Val = DAG.getNode(ISD::BITCAST, DL, RVLocs[i].getLocVT(), Val);
Chain = DAG.getCopyToReg(Chain, DL, VA.getLocReg(), Val, Flag);
// Guarantee that all emitted copies are stuck together with flags.
Flag = Chain.getValue(1);
RetOps.push_back(DAG.getRegister(VA.getLocReg(), VA.getLocVT()));
}
if (Flag.getNode())
RetOps.push_back(Flag);
return DAG.getNode(Nios2ISD::Ret, DL, MVT::Other, RetOps);
}
// addLiveIn - This helper function adds the specified physical register to the
// MachineFunction as a live in value. It also creates a corresponding
// virtual register for it.
static unsigned addLiveIn(MachineFunction &MF, unsigned PReg,
const TargetRegisterClass *RC) {
unsigned VReg = MF.getRegInfo().createVirtualRegister(RC);
MF.getRegInfo().addLiveIn(PReg, VReg);
return VReg;
}
//===----------------------------------------------------------------------===//
// Formal Arguments Calling Convention Implementation
//===----------------------------------------------------------------------===//
// LowerFormalArguments - transform physical registers into virtual registers
// and generate load operations for arguments places on the stack.
SDValue Nios2TargetLowering::LowerFormalArguments(
SDValue Chain, CallingConv::ID CallConv, bool IsVarArg,
const SmallVectorImpl<ISD::InputArg> &Ins, const SDLoc &DL,
SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals) const {
MachineFunction &MF = DAG.getMachineFunction();
MachineFrameInfo &MFI = MF.getFrameInfo();
// Assign locations to all of the incoming arguments.
SmallVector<CCValAssign, 16> ArgLocs;
CCState CCInfo(CallConv, IsVarArg, DAG.getMachineFunction(), ArgLocs,
*DAG.getContext());
CCInfo.AnalyzeFormalArguments(Ins, CC_Nios2);
// Used with vargs to acumulate store chains.
std::vector<SDValue> OutChains;
for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
CCValAssign &VA = ArgLocs[i];
EVT ValVT = VA.getValVT();
// Arguments stored on registers
if (VA.isRegLoc()) {
MVT RegVT = VA.getLocVT();
unsigned ArgReg = VA.getLocReg();
const TargetRegisterClass *RC = getRegClassFor(RegVT);
// Transform the arguments stored on
// physical registers into virtual ones
unsigned Reg = addLiveIn(MF, ArgReg, RC);
SDValue ArgValue = DAG.getCopyFromReg(Chain, DL, Reg, RegVT);
// If this is an 8 or 16-bit value, it has been passed promoted
// to 32 bits. Insert an assert[sz]ext to capture this, then
// truncate to the right size.
if (VA.getLocInfo() != CCValAssign::Full) {
unsigned Opcode = 0;
if (VA.getLocInfo() == CCValAssign::SExt)
Opcode = ISD::AssertSext;
else if (VA.getLocInfo() == CCValAssign::ZExt)
Opcode = ISD::AssertZext;
if (Opcode)
ArgValue =
DAG.getNode(Opcode, DL, RegVT, ArgValue, DAG.getValueType(ValVT));
ArgValue = DAG.getNode(ISD::TRUNCATE, DL, ValVT, ArgValue);
}
// Handle floating point arguments passed in integer registers.
if ((RegVT == MVT::i32 && ValVT == MVT::f32) ||
(RegVT == MVT::i64 && ValVT == MVT::f64))
ArgValue = DAG.getNode(ISD::BITCAST, DL, ValVT, ArgValue);
InVals.push_back(ArgValue);
} else { // VA.isRegLoc()
MVT LocVT = VA.getLocVT();
// sanity check
assert(VA.isMemLoc());
// The stack pointer offset is relative to the caller stack frame.
int FI = MFI.CreateFixedObject(ValVT.getSizeInBits() / 8,
VA.getLocMemOffset(), true);
// Create load nodes to retrieve arguments from the stack
SDValue FIN = DAG.getFrameIndex(FI, getPointerTy(DAG.getDataLayout()));
SDValue Load = DAG.getLoad(
LocVT, DL, Chain, FIN,
MachinePointerInfo::getFixedStack(DAG.getMachineFunction(), FI));
InVals.push_back(Load);
OutChains.push_back(Load.getValue(1));
}
}
if (!OutChains.empty()) {
OutChains.push_back(Chain);
Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, OutChains);
}
return Chain;
}
//===----------------------------------------------------------------------===//
// TargetLowering Implementation
//===----------------------------------------------------------------------===//
Nios2TargetLowering::Nios2TargetLowering(const TargetMachine &TM,
const Nios2Subtarget &STI)
: TargetLowering(TM), Subtarget(&STI) {
addRegisterClass(MVT::i32, &Nios2::CPURegsRegClass);
computeRegisterProperties(Subtarget->getRegisterInfo());
}
const char *Nios2TargetLowering::getTargetNodeName(unsigned Opcode) const {
switch (Opcode) {
case Nios2ISD::Hi:
return "Nios2ISD::Hi";
case Nios2ISD::Lo:
return "Nios2ISD::Lo";
case Nios2ISD::Ret:
return "Nios2ISD::Ret";
}
return nullptr;
}
