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llvm-mirror/lib/Target/ARM/ARMCallLowering.cpp
Amara Emerson 84bc10b28f [GlobalISel][CallLowering] Add support for splitting types according to calling conventions. 
On AArch64, s128 types have to be split into s64 GPRs when passed as arguments.
This change adds the generic support in call lowering for dealing with multiple
registers, for incoming and outgoing args.

Support for splitting for return types not yet implemented.

Differential Revision: https://reviews.llvm.org/D66180

llvm-svn: 370822
2019-09-03 21:42:28 +00:00

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//===- llvm/lib/Target/ARM/ARMCallLowering.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 the lowering of LLVM calls to machine code calls for
/// GlobalISel.
//
//===----------------------------------------------------------------------===//
#include "ARMCallLowering.h"
#include "ARMBaseInstrInfo.h"
#include "ARMISelLowering.h"
#include "ARMSubtarget.h"
#include "Utils/ARMBaseInfo.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/CallingConvLower.h"
#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
#include "llvm/CodeGen/GlobalISel/Utils.h"
#include "llvm/CodeGen/LowLevelType.h"
#include "llvm/CodeGen/MachineBasicBlock.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/LowLevelTypeImpl.h"
#include "llvm/Support/MachineValueType.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <utility>
using namespace llvm;
ARMCallLowering::ARMCallLowering(const ARMTargetLowering &TLI)
: CallLowering(&TLI) {}
static bool isSupportedType(const DataLayout &DL, const ARMTargetLowering &TLI,
Type *T) {
if (T->isArrayTy())
return isSupportedType(DL, TLI, T->getArrayElementType());
if (T->isStructTy()) {
// For now we only allow homogeneous structs that we can manipulate with
// G_MERGE_VALUES and G_UNMERGE_VALUES
auto StructT = cast<StructType>(T);
for (unsigned i = 1, e = StructT->getNumElements(); i != e; ++i)
if (StructT->getElementType(i) != StructT->getElementType(0))
return false;
return isSupportedType(DL, TLI, StructT->getElementType(0));
}
EVT VT = TLI.getValueType(DL, T, true);
if (!VT.isSimple() || VT.isVector() ||
!(VT.isInteger() || VT.isFloatingPoint()))
return false;
unsigned VTSize = VT.getSimpleVT().getSizeInBits();
if (VTSize == 64)
// FIXME: Support i64 too
return VT.isFloatingPoint();
return VTSize == 1 || VTSize == 8 || VTSize == 16 || VTSize == 32;
}
namespace {
/// Helper class for values going out through an ABI boundary (used for handling
/// function return values and call parameters).
struct OutgoingValueHandler : public CallLowering::ValueHandler {
OutgoingValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder &MIB, CCAssignFn *AssignFn)
: ValueHandler(MIRBuilder, MRI, AssignFn), MIB(MIB) {}
Register getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO) override {
assert((Size == 1 || Size == 2 || Size == 4 || Size == 8) &&
"Unsupported size");
LLT p0 = LLT::pointer(0, 32);
LLT s32 = LLT::scalar(32);
Register SPReg = MRI.createGenericVirtualRegister(p0);
MIRBuilder.buildCopy(SPReg, Register(ARM::SP));
Register OffsetReg = MRI.createGenericVirtualRegister(s32);
MIRBuilder.buildConstant(OffsetReg, Offset);
Register AddrReg = MRI.createGenericVirtualRegister(p0);
MIRBuilder.buildGEP(AddrReg, SPReg, OffsetReg);
MPO = MachinePointerInfo::getStack(MIRBuilder.getMF(), Offset);
return AddrReg;
}
void assignValueToReg(Register ValVReg, Register PhysReg,
CCValAssign &VA) override {
assert(VA.isRegLoc() && "Value shouldn't be assigned to reg");
assert(VA.getLocReg() == PhysReg && "Assigning to the wrong reg?");
assert(VA.getValVT().getSizeInBits() <= 64 && "Unsupported value size");
assert(VA.getLocVT().getSizeInBits() <= 64 && "Unsupported location size");
Register ExtReg = extendRegister(ValVReg, VA);
MIRBuilder.buildCopy(PhysReg, ExtReg);
MIB.addUse(PhysReg, RegState::Implicit);
}
void assignValueToAddress(Register ValVReg, Register Addr, uint64_t Size,
MachinePointerInfo &MPO, CCValAssign &VA) override {
assert((Size == 1 || Size == 2 || Size == 4 || Size == 8) &&
"Unsupported size");
Register ExtReg = extendRegister(ValVReg, VA);
auto MMO = MIRBuilder.getMF().getMachineMemOperand(
MPO, MachineMemOperand::MOStore, VA.getLocVT().getStoreSize(),
/* Alignment */ 1);
MIRBuilder.buildStore(ExtReg, Addr, *MMO);
}
unsigned assignCustomValue(const CallLowering::ArgInfo &Arg,
ArrayRef<CCValAssign> VAs) override {
assert(Arg.Regs.size() == 1 && "Can't handle multple regs yet");
CCValAssign VA = VAs[0];
assert(VA.needsCustom() && "Value doesn't need custom handling");
assert(VA.getValVT() == MVT::f64 && "Unsupported type");
CCValAssign NextVA = VAs[1];
assert(NextVA.needsCustom() && "Value doesn't need custom handling");
assert(NextVA.getValVT() == MVT::f64 && "Unsupported type");
assert(VA.getValNo() == NextVA.getValNo() &&
"Values belong to different arguments");
assert(VA.isRegLoc() && "Value should be in reg");
assert(NextVA.isRegLoc() && "Value should be in reg");
Register NewRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
MRI.createGenericVirtualRegister(LLT::scalar(32))};
MIRBuilder.buildUnmerge(NewRegs, Arg.Regs[0]);
bool IsLittle = MIRBuilder.getMF().getSubtarget<ARMSubtarget>().isLittle();
if (!IsLittle)
std::swap(NewRegs[0], NewRegs[1]);
assignValueToReg(NewRegs[0], VA.getLocReg(), VA);
assignValueToReg(NewRegs[1], NextVA.getLocReg(), NextVA);
return 1;
}
bool assignArg(unsigned ValNo, MVT ValVT, MVT LocVT,
CCValAssign::LocInfo LocInfo,
const CallLowering::ArgInfo &Info, ISD::ArgFlagsTy Flags,
CCState &State) override {
if (AssignFn(ValNo, ValVT, LocVT, LocInfo, Flags, State))
return true;
StackSize =
std::max(StackSize, static_cast<uint64_t>(State.getNextStackOffset()));
return false;
}
MachineInstrBuilder &MIB;
uint64_t StackSize = 0;
};
} // end anonymous namespace
void ARMCallLowering::splitToValueTypes(const ArgInfo &OrigArg,
SmallVectorImpl<ArgInfo> &SplitArgs,
MachineFunction &MF) const {
const ARMTargetLowering &TLI = *getTLI<ARMTargetLowering>();
LLVMContext &Ctx = OrigArg.Ty->getContext();
const DataLayout &DL = MF.getDataLayout();
const Function &F = MF.getFunction();
SmallVector<EVT, 4> SplitVTs;
ComputeValueVTs(TLI, DL, OrigArg.Ty, SplitVTs, nullptr, nullptr, 0);
assert(OrigArg.Regs.size() == SplitVTs.size() && "Regs / types mismatch");
if (SplitVTs.size() == 1) {
// Even if there is no splitting to do, we still want to replace the
// original type (e.g. pointer type -> integer).
auto Flags = OrigArg.Flags[0];
unsigned OriginalAlignment = DL.getABITypeAlignment(OrigArg.Ty);
Flags.setOrigAlign(OriginalAlignment);
SplitArgs.emplace_back(OrigArg.Regs[0], SplitVTs[0].getTypeForEVT(Ctx),
Flags, OrigArg.IsFixed);
return;
}
// Create one ArgInfo for each virtual register.
for (unsigned i = 0, e = SplitVTs.size(); i != e; ++i) {
EVT SplitVT = SplitVTs[i];
Type *SplitTy = SplitVT.getTypeForEVT(Ctx);
auto Flags = OrigArg.Flags[0];
unsigned OriginalAlignment = DL.getABITypeAlignment(SplitTy);
Flags.setOrigAlign(OriginalAlignment);
bool NeedsConsecutiveRegisters =
TLI.functionArgumentNeedsConsecutiveRegisters(
SplitTy, F.getCallingConv(), F.isVarArg());
if (NeedsConsecutiveRegisters) {
Flags.setInConsecutiveRegs();
if (i == e - 1)
Flags.setInConsecutiveRegsLast();
}
// FIXME: We also want to split SplitTy further.
Register PartReg = OrigArg.Regs[i];
SplitArgs.emplace_back(PartReg, SplitTy, Flags, OrigArg.IsFixed);
}
}
/// Lower the return value for the already existing \p Ret. This assumes that
/// \p MIRBuilder's insertion point is correct.
bool ARMCallLowering::lowerReturnVal(MachineIRBuilder &MIRBuilder,
const Value *Val, ArrayRef<Register> VRegs,
MachineInstrBuilder &Ret) const {
if (!Val)
// Nothing to do here.
return true;
auto &MF = MIRBuilder.getMF();
const auto &F = MF.getFunction();
auto DL = MF.getDataLayout();
auto &TLI = *getTLI<ARMTargetLowering>();
if (!isSupportedType(DL, TLI, Val->getType()))
return false;
ArgInfo OrigRetInfo(VRegs, Val->getType());
setArgFlags(OrigRetInfo, AttributeList::ReturnIndex, DL, F);
SmallVector<ArgInfo, 4> SplitRetInfos;
splitToValueTypes(OrigRetInfo, SplitRetInfos, MF);
CCAssignFn *AssignFn =
TLI.CCAssignFnForReturn(F.getCallingConv(), F.isVarArg());
OutgoingValueHandler RetHandler(MIRBuilder, MF.getRegInfo(), Ret, AssignFn);
return handleAssignments(MIRBuilder, SplitRetInfos, RetHandler);
}
bool ARMCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
const Value *Val,
ArrayRef<Register> VRegs) const {
assert(!Val == VRegs.empty() && "Return value without a vreg");
auto const &ST = MIRBuilder.getMF().getSubtarget<ARMSubtarget>();
unsigned Opcode = ST.getReturnOpcode();
auto Ret = MIRBuilder.buildInstrNoInsert(Opcode).add(predOps(ARMCC::AL));
if (!lowerReturnVal(MIRBuilder, Val, VRegs, Ret))
return false;
MIRBuilder.insertInstr(Ret);
return true;
}
namespace {
/// Helper class for values coming in through an ABI boundary (used for handling
/// formal arguments and call return values).
struct IncomingValueHandler : public CallLowering::ValueHandler {
IncomingValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn AssignFn)
: ValueHandler(MIRBuilder, MRI, AssignFn) {}
bool isIncomingArgumentHandler() const override { return true; }
Register getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO) override {
assert((Size == 1 || Size == 2 || Size == 4 || Size == 8) &&
"Unsupported size");
auto &MFI = MIRBuilder.getMF().getFrameInfo();
int FI = MFI.CreateFixedObject(Size, Offset, true);
MPO = MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);
Register AddrReg =
MRI.createGenericVirtualRegister(LLT::pointer(MPO.getAddrSpace(), 32));
MIRBuilder.buildFrameIndex(AddrReg, FI);
return AddrReg;
}
void assignValueToAddress(Register ValVReg, Register Addr, uint64_t Size,
MachinePointerInfo &MPO, CCValAssign &VA) override {
assert((Size == 1 || Size == 2 || Size == 4 || Size == 8) &&
"Unsupported size");
if (VA.getLocInfo() == CCValAssign::SExt ||
VA.getLocInfo() == CCValAssign::ZExt) {
// If the value is zero- or sign-extended, its size becomes 4 bytes, so
// that's what we should load.
Size = 4;
assert(MRI.getType(ValVReg).isScalar() && "Only scalars supported atm");
auto LoadVReg = MRI.createGenericVirtualRegister(LLT::scalar(32));
buildLoad(LoadVReg, Addr, Size, /* Alignment */ 1, MPO);
MIRBuilder.buildTrunc(ValVReg, LoadVReg);
} else {
// If the value is not extended, a simple load will suffice.
buildLoad(ValVReg, Addr, Size, /* Alignment */ 1, MPO);
}
}
void buildLoad(Register Val, Register Addr, uint64_t Size, unsigned Alignment,
MachinePointerInfo &MPO) {
auto MMO = MIRBuilder.getMF().getMachineMemOperand(
MPO, MachineMemOperand::MOLoad, Size, Alignment);
MIRBuilder.buildLoad(Val, Addr, *MMO);
}
void assignValueToReg(Register ValVReg, Register PhysReg,
CCValAssign &VA) override {
assert(VA.isRegLoc() && "Value shouldn't be assigned to reg");
assert(VA.getLocReg() == PhysReg && "Assigning to the wrong reg?");
auto ValSize = VA.getValVT().getSizeInBits();
auto LocSize = VA.getLocVT().getSizeInBits();
assert(ValSize <= 64 && "Unsupported value size");
assert(LocSize <= 64 && "Unsupported location size");
markPhysRegUsed(PhysReg);
if (ValSize == LocSize) {
MIRBuilder.buildCopy(ValVReg, PhysReg);
} else {
assert(ValSize < LocSize && "Extensions not supported");
// We cannot create a truncating copy, nor a trunc of a physical register.
// Therefore, we need to copy the content of the physical register into a
// virtual one and then truncate that.
auto PhysRegToVReg =
MRI.createGenericVirtualRegister(LLT::scalar(LocSize));
MIRBuilder.buildCopy(PhysRegToVReg, PhysReg);
MIRBuilder.buildTrunc(ValVReg, PhysRegToVReg);
}
}
unsigned assignCustomValue(const ARMCallLowering::ArgInfo &Arg,
ArrayRef<CCValAssign> VAs) override {
assert(Arg.Regs.size() == 1 && "Can't handle multple regs yet");
CCValAssign VA = VAs[0];
assert(VA.needsCustom() && "Value doesn't need custom handling");
assert(VA.getValVT() == MVT::f64 && "Unsupported type");
CCValAssign NextVA = VAs[1];
assert(NextVA.needsCustom() && "Value doesn't need custom handling");
assert(NextVA.getValVT() == MVT::f64 && "Unsupported type");
assert(VA.getValNo() == NextVA.getValNo() &&
"Values belong to different arguments");
assert(VA.isRegLoc() && "Value should be in reg");
assert(NextVA.isRegLoc() && "Value should be in reg");
Register NewRegs[] = {MRI.createGenericVirtualRegister(LLT::scalar(32)),
MRI.createGenericVirtualRegister(LLT::scalar(32))};
assignValueToReg(NewRegs[0], VA.getLocReg(), VA);
assignValueToReg(NewRegs[1], NextVA.getLocReg(), NextVA);
bool IsLittle = MIRBuilder.getMF().getSubtarget<ARMSubtarget>().isLittle();
if (!IsLittle)
std::swap(NewRegs[0], NewRegs[1]);
MIRBuilder.buildMerge(Arg.Regs[0], NewRegs);
return 1;
}
/// Marking a physical register as used is different between formal
/// parameters, where it's a basic block live-in, and call returns, where it's
/// an implicit-def of the call instruction.
virtual void markPhysRegUsed(unsigned PhysReg) = 0;
};
struct FormalArgHandler : public IncomingValueHandler {
FormalArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn AssignFn)
: IncomingValueHandler(MIRBuilder, MRI, AssignFn) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIRBuilder.getMRI()->addLiveIn(PhysReg);
MIRBuilder.getMBB().addLiveIn(PhysReg);
}
};
} // end anonymous namespace
bool ARMCallLowering::lowerFormalArguments(
MachineIRBuilder &MIRBuilder, const Function &F,
ArrayRef<ArrayRef<Register>> VRegs) const {
auto &TLI = *getTLI<ARMTargetLowering>();
auto Subtarget = TLI.getSubtarget();
if (Subtarget->isThumb1Only())
return false;
// Quick exit if there aren't any args
if (F.arg_empty())
return true;
if (F.isVarArg())
return false;
auto &MF = MIRBuilder.getMF();
auto &MBB = MIRBuilder.getMBB();
auto DL = MF.getDataLayout();
for (auto &Arg : F.args()) {
if (!isSupportedType(DL, TLI, Arg.getType()))
return false;
if (Arg.hasByValOrInAllocaAttr())
return false;
}
CCAssignFn *AssignFn =
TLI.CCAssignFnForCall(F.getCallingConv(), F.isVarArg());
FormalArgHandler ArgHandler(MIRBuilder, MIRBuilder.getMF().getRegInfo(),
AssignFn);
SmallVector<ArgInfo, 8> SplitArgInfos;
unsigned Idx = 0;
for (auto &Arg : F.args()) {
ArgInfo OrigArgInfo(VRegs[Idx], Arg.getType());
setArgFlags(OrigArgInfo, Idx + AttributeList::FirstArgIndex, DL, F);
splitToValueTypes(OrigArgInfo, SplitArgInfos, MF);
Idx++;
}
if (!MBB.empty())
MIRBuilder.setInstr(*MBB.begin());
if (!handleAssignments(MIRBuilder, SplitArgInfos, ArgHandler))
return false;
// Move back to the end of the basic block.
MIRBuilder.setMBB(MBB);
return true;
}
namespace {
struct CallReturnHandler : public IncomingValueHandler {
CallReturnHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder MIB, CCAssignFn *AssignFn)
: IncomingValueHandler(MIRBuilder, MRI, AssignFn), MIB(MIB) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIB.addDef(PhysReg, RegState::Implicit);
}
MachineInstrBuilder MIB;
};
// FIXME: This should move to the ARMSubtarget when it supports all the opcodes.
unsigned getCallOpcode(const ARMSubtarget &STI, bool isDirect) {
if (isDirect)
return STI.isThumb() ? ARM::tBL : ARM::BL;
if (STI.isThumb())
return ARM::tBLXr;
if (STI.hasV5TOps())
return ARM::BLX;
if (STI.hasV4TOps())
return ARM::BX_CALL;
return ARM::BMOVPCRX_CALL;
}
} // end anonymous namespace
bool ARMCallLowering::lowerCall(MachineIRBuilder &MIRBuilder, CallLoweringInfo &Info) const {
MachineFunction &MF = MIRBuilder.getMF();
const auto &TLI = *getTLI<ARMTargetLowering>();
const auto &DL = MF.getDataLayout();
const auto &STI = MF.getSubtarget<ARMSubtarget>();
const TargetRegisterInfo *TRI = STI.getRegisterInfo();
MachineRegisterInfo &MRI = MF.getRegInfo();
if (STI.genLongCalls())
return false;
if (STI.isThumb1Only())
return false;
auto CallSeqStart = MIRBuilder.buildInstr(ARM::ADJCALLSTACKDOWN);
// Create the call instruction so we can add the implicit uses of arg
// registers, but don't insert it yet.
bool IsDirect = !Info.Callee.isReg();
auto CallOpcode = getCallOpcode(STI, IsDirect);
auto MIB = MIRBuilder.buildInstrNoInsert(CallOpcode);
bool IsThumb = STI.isThumb();
if (IsThumb)
MIB.add(predOps(ARMCC::AL));
MIB.add(Info.Callee);
if (!IsDirect) {
auto CalleeReg = Info.Callee.getReg();
if (CalleeReg && !Register::isPhysicalRegister(CalleeReg)) {
unsigned CalleeIdx = IsThumb ? 2 : 0;
MIB->getOperand(CalleeIdx).setReg(constrainOperandRegClass(
MF, *TRI, MRI, *STI.getInstrInfo(), *STI.getRegBankInfo(),
*MIB.getInstr(), MIB->getDesc(), Info.Callee, CalleeIdx));
}
}
MIB.addRegMask(TRI->getCallPreservedMask(MF, Info.CallConv));
bool IsVarArg = false;
SmallVector<ArgInfo, 8> ArgInfos;
for (auto Arg : Info.OrigArgs) {
if (!isSupportedType(DL, TLI, Arg.Ty))
return false;
if (!Arg.IsFixed)
IsVarArg = true;
if (Arg.Flags[0].isByVal())
return false;
splitToValueTypes(Arg, ArgInfos, MF);
}
auto ArgAssignFn = TLI.CCAssignFnForCall(Info.CallConv, IsVarArg);
OutgoingValueHandler ArgHandler(MIRBuilder, MRI, MIB, ArgAssignFn);
if (!handleAssignments(MIRBuilder, ArgInfos, ArgHandler))
return false;
// Now we can add the actual call instruction to the correct basic block.
MIRBuilder.insertInstr(MIB);
if (!Info.OrigRet.Ty->isVoidTy()) {
if (!isSupportedType(DL, TLI, Info.OrigRet.Ty))
return false;
ArgInfos.clear();
splitToValueTypes(Info.OrigRet, ArgInfos, MF);
auto RetAssignFn = TLI.CCAssignFnForReturn(Info.CallConv, IsVarArg);
CallReturnHandler RetHandler(MIRBuilder, MRI, MIB, RetAssignFn);
if (!handleAssignments(MIRBuilder, ArgInfos, RetHandler))
return false;
}
// We now know the size of the stack - update the ADJCALLSTACKDOWN
// accordingly.
CallSeqStart.addImm(ArgHandler.StackSize).addImm(0).add(predOps(ARMCC::AL));
MIRBuilder.buildInstr(ARM::ADJCALLSTACKUP)
.addImm(ArgHandler.StackSize)
.addImm(0)
.add(predOps(ARMCC::AL));
return true;
}
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