lib/CodeGen/GlobalISel/CallLowering.cpp - llvm - Git at Google

 //===-- lib/CodeGen/GlobalISel/CallLowering.cpp - Call lowering -----------===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// This file implements some simple delegations needed for call lowering.
 ///
 //===----------------------------------------------------------------------===//

 #include "llvm/CodeGen/GlobalISel/CallLowering.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
 #include "llvm/CodeGen/MachineOperand.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"

 #define DEBUG_TYPE "call-lowering"

 using namespace llvm;

 void CallLowering::anchor() {}

 bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, ImmutableCallSite CS,
                              ArrayRef<Register> ResRegs,
                              ArrayRef<ArrayRef<Register>> ArgRegs,
                              Register SwiftErrorVReg,
                              std::function<unsigned()> GetCalleeReg) const {
   CallLoweringInfo Info;
   auto &DL = CS.getParent()->getParent()->getParent()->getDataLayout();

   // First step is to marshall all the function's parameters into the correct
   // physregs and memory locations. Gather the sequence of argument types that
   // we'll pass to the assigner function.
   unsigned i = 0;
   unsigned NumFixedArgs = CS.getFunctionType()->getNumParams();
   for (auto &Arg : CS.args()) {
     ArgInfo OrigArg{ArgRegs[i], Arg->getType(), ISD::ArgFlagsTy{},
                     i < NumFixedArgs};
     setArgFlags(OrigArg, i + AttributeList::FirstArgIndex, DL, CS);
     Info.OrigArgs.push_back(OrigArg);
     ++i;
   }

   if (const Function *F = CS.getCalledFunction())
     Info.Callee = MachineOperand::CreateGA(F, 0);
   else
     Info.Callee = MachineOperand::CreateReg(GetCalleeReg(), false);

   Info.OrigRet = ArgInfo{ResRegs, CS.getType(), ISD::ArgFlagsTy{}};
   if (!Info.OrigRet.Ty->isVoidTy())
     setArgFlags(Info.OrigRet, AttributeList::ReturnIndex, DL, CS);

   Info.KnownCallees =
       CS.getInstruction()->getMetadata(LLVMContext::MD_callees);
   Info.CallConv = CS.getCallingConv();
   Info.SwiftErrorVReg = SwiftErrorVReg;

   return lowerCall(MIRBuilder, Info);
 }

 template <typename FuncInfoTy>
 void CallLowering::setArgFlags(CallLowering::ArgInfo &Arg, unsigned OpIdx,
                                const DataLayout &DL,
                                const FuncInfoTy &FuncInfo) const {
   const AttributeList &Attrs = FuncInfo.getAttributes();
   if (Attrs.hasAttribute(OpIdx, Attribute::ZExt))
     Arg.Flags.setZExt();
   if (Attrs.hasAttribute(OpIdx, Attribute::SExt))
     Arg.Flags.setSExt();
   if (Attrs.hasAttribute(OpIdx, Attribute::InReg))
     Arg.Flags.setInReg();
   if (Attrs.hasAttribute(OpIdx, Attribute::StructRet))
     Arg.Flags.setSRet();
   if (Attrs.hasAttribute(OpIdx, Attribute::SwiftSelf))
     Arg.Flags.setSwiftSelf();
   if (Attrs.hasAttribute(OpIdx, Attribute::SwiftError))
     Arg.Flags.setSwiftError();
   if (Attrs.hasAttribute(OpIdx, Attribute::ByVal))
     Arg.Flags.setByVal();
   if (Attrs.hasAttribute(OpIdx, Attribute::InAlloca))
     Arg.Flags.setInAlloca();

   if (Arg.Flags.isByVal() || Arg.Flags.isInAlloca()) {
     Type *ElementTy = cast<PointerType>(Arg.Ty)->getElementType();

     auto Ty = Attrs.getAttribute(OpIdx, Attribute::ByVal).getValueAsType();
     Arg.Flags.setByValSize(DL.getTypeAllocSize(Ty ? Ty : ElementTy));

     // For ByVal, alignment should be passed from FE.  BE will guess if
     // this info is not there but there are cases it cannot get right.
     unsigned FrameAlign;
     if (FuncInfo.getParamAlignment(OpIdx - 2))
       FrameAlign = FuncInfo.getParamAlignment(OpIdx - 2);
     else
       FrameAlign = getTLI()->getByValTypeAlignment(ElementTy, DL);
     Arg.Flags.setByValAlign(FrameAlign);
   }
   if (Attrs.hasAttribute(OpIdx, Attribute::Nest))
     Arg.Flags.setNest();
   Arg.Flags.setOrigAlign(DL.getABITypeAlignment(Arg.Ty));
 }

 template void
 CallLowering::setArgFlags<Function>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
                                     const DataLayout &DL,
                                     const Function &FuncInfo) const;

 template void
 CallLowering::setArgFlags<CallInst>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
                                     const DataLayout &DL,
                                     const CallInst &FuncInfo) const;

 Register CallLowering::packRegs(ArrayRef<Register> SrcRegs, Type *PackedTy,
                                 MachineIRBuilder &MIRBuilder) const {
   assert(SrcRegs.size() > 1 && "Nothing to pack");

   const DataLayout &DL = MIRBuilder.getMF().getDataLayout();
   MachineRegisterInfo *MRI = MIRBuilder.getMRI();

   LLT PackedLLT = getLLTForType(*PackedTy, DL);

   SmallVector<LLT, 8> LLTs;
   SmallVector<uint64_t, 8> Offsets;
   computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
   assert(LLTs.size() == SrcRegs.size() && "Regs / types mismatch");

   Register Dst = MRI->createGenericVirtualRegister(PackedLLT);
   MIRBuilder.buildUndef(Dst);
   for (unsigned i = 0; i < SrcRegs.size(); ++i) {
     Register NewDst = MRI->createGenericVirtualRegister(PackedLLT);
     MIRBuilder.buildInsert(NewDst, Dst, SrcRegs[i], Offsets[i]);
     Dst = NewDst;
   }

   return Dst;
 }

 void CallLowering::unpackRegs(ArrayRef<Register> DstRegs, Register SrcReg,
                               Type *PackedTy,
                               MachineIRBuilder &MIRBuilder) const {
   assert(DstRegs.size() > 1 && "Nothing to unpack");

   const DataLayout &DL = MIRBuilder.getMF().getDataLayout();

   SmallVector<LLT, 8> LLTs;
   SmallVector<uint64_t, 8> Offsets;
   computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
   assert(LLTs.size() == DstRegs.size() && "Regs / types mismatch");

   for (unsigned i = 0; i < DstRegs.size(); ++i)
     MIRBuilder.buildExtract(DstRegs[i], SrcReg, Offsets[i]);
 }

 bool CallLowering::handleAssignments(MachineIRBuilder &MIRBuilder,
                                      ArrayRef<ArgInfo> Args,
                                      ValueHandler &Handler) const {
   MachineFunction &MF = MIRBuilder.getMF();
   const Function &F = MF.getFunction();
   SmallVector<CCValAssign, 16> ArgLocs;
   CCState CCInfo(F.getCallingConv(), F.isVarArg(), MF, ArgLocs, F.getContext());
   return handleAssignments(CCInfo, ArgLocs, MIRBuilder, Args, Handler);
 }

 bool CallLowering::handleAssignments(CCState &CCInfo,
                                      SmallVectorImpl<CCValAssign> &ArgLocs,
                                      MachineIRBuilder &MIRBuilder,
                                      ArrayRef<ArgInfo> Args,
                                      ValueHandler &Handler) const {
   MachineFunction &MF = MIRBuilder.getMF();
   const Function &F = MF.getFunction();
   const DataLayout &DL = F.getParent()->getDataLayout();

   unsigned NumArgs = Args.size();
   for (unsigned i = 0; i != NumArgs; ++i) {
     MVT CurVT = MVT::getVT(Args[i].Ty);
     if (Handler.assignArg(i, CurVT, CurVT, CCValAssign::Full, Args[i], CCInfo)) {
       // Try to use the register type if we couldn't assign the VT.
       if (!Handler.isIncomingArgumentHandler() || !CurVT.isValid())
         return false;
       CurVT = TLI->getRegisterTypeForCallingConv(
           F.getContext(), F.getCallingConv(), EVT(CurVT));
       if (Handler.assignArg(i, CurVT, CurVT, CCValAssign::Full, Args[i], CCInfo))
         return false;
     }
   }

   for (unsigned i = 0, e = Args.size(), j = 0; i != e; ++i, ++j) {
     assert(j < ArgLocs.size() && "Skipped too many arg locs");

     CCValAssign &VA = ArgLocs[j];
     assert(VA.getValNo() == i && "Location doesn't correspond to current arg");

     if (VA.needsCustom()) {
       j += Handler.assignCustomValue(Args[i], makeArrayRef(ArgLocs).slice(j));
       continue;
     }

     assert(Args[i].Regs.size() == 1 &&
            "Can't handle multiple virtual regs yet");

     // FIXME: Pack registers if we have more than one.
     Register ArgReg = Args[i].Regs[0];

     if (VA.isRegLoc()) {
       MVT OrigVT = MVT::getVT(Args[i].Ty);
       MVT VAVT = VA.getValVT();
       if (Handler.isIncomingArgumentHandler() && VAVT != OrigVT) {
         if (VAVT.getSizeInBits() < OrigVT.getSizeInBits())
           return false; // Can't handle this type of arg yet.
         const LLT VATy(VAVT);
         Register NewReg =
             MIRBuilder.getMRI()->createGenericVirtualRegister(VATy);
         Handler.assignValueToReg(NewReg, VA.getLocReg(), VA);
         // If it's a vector type, we either need to truncate the elements
         // or do an unmerge to get the lower block of elements.
         if (VATy.isVector() &&
             VATy.getNumElements() > OrigVT.getVectorNumElements()) {
           const LLT OrigTy(OrigVT);
           // Just handle the case where the VA type is 2 * original type.
           if (VATy.getNumElements() != OrigVT.getVectorNumElements() * 2) {
             LLVM_DEBUG(dbgs()
                        << "Incoming promoted vector arg has too many elts");
             return false;
           }
           auto Unmerge = MIRBuilder.buildUnmerge({OrigTy, OrigTy}, {NewReg});
           MIRBuilder.buildCopy(ArgReg, Unmerge.getReg(0));
         } else {
           MIRBuilder.buildTrunc(ArgReg, {NewReg}).getReg(0);
         }
       } else {
         Handler.assignValueToReg(ArgReg, VA.getLocReg(), VA);
       }
     } else if (VA.isMemLoc()) {
       MVT VT = MVT::getVT(Args[i].Ty);
       unsigned Size = VT == MVT::iPTR ? DL.getPointerSize()
                                       : alignTo(VT.getSizeInBits(), 8) / 8;
       unsigned Offset = VA.getLocMemOffset();
       MachinePointerInfo MPO;
       Register StackAddr = Handler.getStackAddress(Size, Offset, MPO);
       Handler.assignValueToAddress(ArgReg, StackAddr, Size, MPO, VA);
     } else {
       // FIXME: Support byvals and other weirdness
       return false;
     }
   }
   return true;
 }

 Register CallLowering::ValueHandler::extendRegister(Register ValReg,
                                                     CCValAssign &VA) {
   LLT LocTy{VA.getLocVT()};
   if (LocTy.getSizeInBits() == MRI.getType(ValReg).getSizeInBits())
     return ValReg;
   switch (VA.getLocInfo()) {
   default: break;
   case CCValAssign::Full:
   case CCValAssign::BCvt:
     // FIXME: bitconverting between vector types may or may not be a
     // nop in big-endian situations.
     return ValReg;
   case CCValAssign::AExt: {
     auto MIB = MIRBuilder.buildAnyExt(LocTy, ValReg);
     return MIB->getOperand(0).getReg();
   }
   case CCValAssign::SExt: {
     Register NewReg = MRI.createGenericVirtualRegister(LocTy);
     MIRBuilder.buildSExt(NewReg, ValReg);
     return NewReg;
   }
   case CCValAssign::ZExt: {
     Register NewReg = MRI.createGenericVirtualRegister(LocTy);
     MIRBuilder.buildZExt(NewReg, ValReg);
     return NewReg;
   }
   }
   llvm_unreachable("unable to extend register");
 }

 void CallLowering::ValueHandler::anchor() {}
	//===-- lib/CodeGen/GlobalISel/CallLowering.cpp - Call lowering -----------===//
	//
	// 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
	//
	//===----------------------------------------------------------------------===//
	///
	/// \file
	/// This file implements some simple delegations needed for call lowering.
	///
	//===----------------------------------------------------------------------===//

	#include "llvm/CodeGen/GlobalISel/CallLowering.h"
	#include "llvm/CodeGen/Analysis.h"
	#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
	#include "llvm/CodeGen/MachineOperand.h"
	#include "llvm/CodeGen/MachineRegisterInfo.h"
	#include "llvm/CodeGen/TargetLowering.h"
	#include "llvm/IR/DataLayout.h"
	#include "llvm/IR/Instructions.h"
	#include "llvm/IR/LLVMContext.h"
	#include "llvm/IR/Module.h"

	#define DEBUG_TYPE "call-lowering"

	using namespace llvm;

	void CallLowering::anchor() {}

	bool CallLowering::lowerCall(MachineIRBuilder &MIRBuilder, ImmutableCallSite CS,
	ArrayRef<Register> ResRegs,
	ArrayRef<ArrayRef<Register>> ArgRegs,
	Register SwiftErrorVReg,
	std::function<unsigned()> GetCalleeReg) const {
	CallLoweringInfo Info;
	auto &DL = CS.getParent()->getParent()->getParent()->getDataLayout();

	// First step is to marshall all the function's parameters into the correct
	// physregs and memory locations. Gather the sequence of argument types that
	// we'll pass to the assigner function.
	unsigned i = 0;
	unsigned NumFixedArgs = CS.getFunctionType()->getNumParams();
	for (auto &Arg : CS.args()) {
	ArgInfo OrigArg{ArgRegs[i], Arg->getType(), ISD::ArgFlagsTy{},
	i < NumFixedArgs};
	setArgFlags(OrigArg, i + AttributeList::FirstArgIndex, DL, CS);
	Info.OrigArgs.push_back(OrigArg);
	++i;
	}

	if (const Function *F = CS.getCalledFunction())
	Info.Callee = MachineOperand::CreateGA(F, 0);
	else
	Info.Callee = MachineOperand::CreateReg(GetCalleeReg(), false);

	Info.OrigRet = ArgInfo{ResRegs, CS.getType(), ISD::ArgFlagsTy{}};
	if (!Info.OrigRet.Ty->isVoidTy())
	setArgFlags(Info.OrigRet, AttributeList::ReturnIndex, DL, CS);

	Info.KnownCallees =
	CS.getInstruction()->getMetadata(LLVMContext::MD_callees);
	Info.CallConv = CS.getCallingConv();
	Info.SwiftErrorVReg = SwiftErrorVReg;

	return lowerCall(MIRBuilder, Info);
	}

	template <typename FuncInfoTy>
	void CallLowering::setArgFlags(CallLowering::ArgInfo &Arg, unsigned OpIdx,
	const DataLayout &DL,
	const FuncInfoTy &FuncInfo) const {
	const AttributeList &Attrs = FuncInfo.getAttributes();
	if (Attrs.hasAttribute(OpIdx, Attribute::ZExt))
	Arg.Flags.setZExt();
	if (Attrs.hasAttribute(OpIdx, Attribute::SExt))
	Arg.Flags.setSExt();
	if (Attrs.hasAttribute(OpIdx, Attribute::InReg))
	Arg.Flags.setInReg();
	if (Attrs.hasAttribute(OpIdx, Attribute::StructRet))
	Arg.Flags.setSRet();
	if (Attrs.hasAttribute(OpIdx, Attribute::SwiftSelf))
	Arg.Flags.setSwiftSelf();
	if (Attrs.hasAttribute(OpIdx, Attribute::SwiftError))
	Arg.Flags.setSwiftError();
	if (Attrs.hasAttribute(OpIdx, Attribute::ByVal))
	Arg.Flags.setByVal();
	if (Attrs.hasAttribute(OpIdx, Attribute::InAlloca))
	Arg.Flags.setInAlloca();

	if (Arg.Flags.isByVal() \|\| Arg.Flags.isInAlloca()) {
	Type *ElementTy = cast<PointerType>(Arg.Ty)->getElementType();

	auto Ty = Attrs.getAttribute(OpIdx, Attribute::ByVal).getValueAsType();
	Arg.Flags.setByValSize(DL.getTypeAllocSize(Ty ? Ty : ElementTy));

	// For ByVal, alignment should be passed from FE. BE will guess if
	// this info is not there but there are cases it cannot get right.
	unsigned FrameAlign;
	if (FuncInfo.getParamAlignment(OpIdx - 2))
	FrameAlign = FuncInfo.getParamAlignment(OpIdx - 2);
	else
	FrameAlign = getTLI()->getByValTypeAlignment(ElementTy, DL);
	Arg.Flags.setByValAlign(FrameAlign);
	}
	if (Attrs.hasAttribute(OpIdx, Attribute::Nest))
	Arg.Flags.setNest();
	Arg.Flags.setOrigAlign(DL.getABITypeAlignment(Arg.Ty));
	}

	template void
	CallLowering::setArgFlags<Function>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
	const DataLayout &DL,
	const Function &FuncInfo) const;

	template void
	CallLowering::setArgFlags<CallInst>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
	const DataLayout &DL,
	const CallInst &FuncInfo) const;

	Register CallLowering::packRegs(ArrayRef<Register> SrcRegs, Type *PackedTy,
	MachineIRBuilder &MIRBuilder) const {
	assert(SrcRegs.size() > 1 && "Nothing to pack");

	const DataLayout &DL = MIRBuilder.getMF().getDataLayout();
	MachineRegisterInfo *MRI = MIRBuilder.getMRI();

	LLT PackedLLT = getLLTForType(*PackedTy, DL);

	SmallVector<LLT, 8> LLTs;
	SmallVector<uint64_t, 8> Offsets;
	computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
	assert(LLTs.size() == SrcRegs.size() && "Regs / types mismatch");

	Register Dst = MRI->createGenericVirtualRegister(PackedLLT);
	MIRBuilder.buildUndef(Dst);
	for (unsigned i = 0; i < SrcRegs.size(); ++i) {
	Register NewDst = MRI->createGenericVirtualRegister(PackedLLT);
	MIRBuilder.buildInsert(NewDst, Dst, SrcRegs[i], Offsets[i]);
	Dst = NewDst;
	}

	return Dst;
	}

	void CallLowering::unpackRegs(ArrayRef<Register> DstRegs, Register SrcReg,
	Type *PackedTy,
	MachineIRBuilder &MIRBuilder) const {
	assert(DstRegs.size() > 1 && "Nothing to unpack");

	const DataLayout &DL = MIRBuilder.getMF().getDataLayout();

	SmallVector<LLT, 8> LLTs;
	SmallVector<uint64_t, 8> Offsets;
	computeValueLLTs(DL, *PackedTy, LLTs, &Offsets);
	assert(LLTs.size() == DstRegs.size() && "Regs / types mismatch");

	for (unsigned i = 0; i < DstRegs.size(); ++i)
	MIRBuilder.buildExtract(DstRegs[i], SrcReg, Offsets[i]);
	}

	bool CallLowering::handleAssignments(MachineIRBuilder &MIRBuilder,
	ArrayRef<ArgInfo> Args,
	ValueHandler &Handler) const {
	MachineFunction &MF = MIRBuilder.getMF();
	const Function &F = MF.getFunction();
	SmallVector<CCValAssign, 16> ArgLocs;
	CCState CCInfo(F.getCallingConv(), F.isVarArg(), MF, ArgLocs, F.getContext());
	return handleAssignments(CCInfo, ArgLocs, MIRBuilder, Args, Handler);
	}

	bool CallLowering::handleAssignments(CCState &CCInfo,
	SmallVectorImpl<CCValAssign> &ArgLocs,
	MachineIRBuilder &MIRBuilder,
	ArrayRef<ArgInfo> Args,
	ValueHandler &Handler) const {
	MachineFunction &MF = MIRBuilder.getMF();
	const Function &F = MF.getFunction();
	const DataLayout &DL = F.getParent()->getDataLayout();

	unsigned NumArgs = Args.size();
	for (unsigned i = 0; i != NumArgs; ++i) {
	MVT CurVT = MVT::getVT(Args[i].Ty);
	if (Handler.assignArg(i, CurVT, CurVT, CCValAssign::Full, Args[i], CCInfo)) {
	// Try to use the register type if we couldn't assign the VT.
	if (!Handler.isIncomingArgumentHandler() \|\| !CurVT.isValid())
	return false;
	CurVT = TLI->getRegisterTypeForCallingConv(
	F.getContext(), F.getCallingConv(), EVT(CurVT));
	if (Handler.assignArg(i, CurVT, CurVT, CCValAssign::Full, Args[i], CCInfo))
	return false;
	}
	}

	for (unsigned i = 0, e = Args.size(), j = 0; i != e; ++i, ++j) {
	assert(j < ArgLocs.size() && "Skipped too many arg locs");

	CCValAssign &VA = ArgLocs[j];
	assert(VA.getValNo() == i && "Location doesn't correspond to current arg");

	if (VA.needsCustom()) {
	j += Handler.assignCustomValue(Args[i], makeArrayRef(ArgLocs).slice(j));
	continue;
	}

	assert(Args[i].Regs.size() == 1 &&
	"Can't handle multiple virtual regs yet");

	// FIXME: Pack registers if we have more than one.
	Register ArgReg = Args[i].Regs[0];

	if (VA.isRegLoc()) {
	MVT OrigVT = MVT::getVT(Args[i].Ty);
	MVT VAVT = VA.getValVT();
	if (Handler.isIncomingArgumentHandler() && VAVT != OrigVT) {
	if (VAVT.getSizeInBits() < OrigVT.getSizeInBits())
	return false; // Can't handle this type of arg yet.
	const LLT VATy(VAVT);
	Register NewReg =
	MIRBuilder.getMRI()->createGenericVirtualRegister(VATy);
	Handler.assignValueToReg(NewReg, VA.getLocReg(), VA);
	// If it's a vector type, we either need to truncate the elements
	// or do an unmerge to get the lower block of elements.
	if (VATy.isVector() &&
	VATy.getNumElements() > OrigVT.getVectorNumElements()) {
	const LLT OrigTy(OrigVT);
	// Just handle the case where the VA type is 2 * original type.
	if (VATy.getNumElements() != OrigVT.getVectorNumElements() * 2) {
	LLVM_DEBUG(dbgs()
	<< "Incoming promoted vector arg has too many elts");
	return false;
	}
	auto Unmerge = MIRBuilder.buildUnmerge({OrigTy, OrigTy}, {NewReg});
	MIRBuilder.buildCopy(ArgReg, Unmerge.getReg(0));
	} else {
	MIRBuilder.buildTrunc(ArgReg, {NewReg}).getReg(0);
	}
	} else {
	Handler.assignValueToReg(ArgReg, VA.getLocReg(), VA);
	}
	} else if (VA.isMemLoc()) {
	MVT VT = MVT::getVT(Args[i].Ty);
	unsigned Size = VT == MVT::iPTR ? DL.getPointerSize()
	: alignTo(VT.getSizeInBits(), 8) / 8;
	unsigned Offset = VA.getLocMemOffset();
	MachinePointerInfo MPO;
	Register StackAddr = Handler.getStackAddress(Size, Offset, MPO);
	Handler.assignValueToAddress(ArgReg, StackAddr, Size, MPO, VA);
	} else {
	// FIXME: Support byvals and other weirdness
	return false;
	}
	}
	return true;
	}

	Register CallLowering::ValueHandler::extendRegister(Register ValReg,
	CCValAssign &VA) {
	LLT LocTy{VA.getLocVT()};
	if (LocTy.getSizeInBits() == MRI.getType(ValReg).getSizeInBits())
	return ValReg;
	switch (VA.getLocInfo()) {
	default: break;
	case CCValAssign::Full:
	case CCValAssign::BCvt:
	// FIXME: bitconverting between vector types may or may not be a
	// nop in big-endian situations.
	return ValReg;
	case CCValAssign::AExt: {
	auto MIB = MIRBuilder.buildAnyExt(LocTy, ValReg);
	return MIB->getOperand(0).getReg();
	}
	case CCValAssign::SExt: {
	Register NewReg = MRI.createGenericVirtualRegister(LocTy);
	MIRBuilder.buildSExt(NewReg, ValReg);
	return NewReg;
	}
	case CCValAssign::ZExt: {
	Register NewReg = MRI.createGenericVirtualRegister(LocTy);
	MIRBuilder.buildZExt(NewReg, ValReg);
	return NewReg;
	}
	}
	llvm_unreachable("unable to extend register");
	}

	void CallLowering::ValueHandler::anchor() {}