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llvm-project/llvm/lib/Target/ARM/ARMCallLowering.cpp

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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 ARMOutgoingValueHandler : public CallLowering::OutgoingValueHandler {
ARMOutgoingValueHandler(MachineIRBuilder &MIRBuilder,
MachineRegisterInfo &MRI, MachineInstrBuilder &MIB)
: OutgoingValueHandler(MIRBuilder, MRI), MIB(MIB) {}
Register getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO,
ISD::ArgFlagsTy Flags) override {
assert((Size == 1 || Size == 2 || Size == 4 || Size == 8) &&
"Unsupported size");
LLT p0 = LLT::pointer(0, 32);
LLT s32 = LLT::scalar(32);
auto SPReg = MIRBuilder.buildCopy(p0, Register(ARM::SP));
auto OffsetReg = MIRBuilder.buildConstant(s32, Offset);
auto AddrReg = MIRBuilder.buildPtrAdd(p0, SPReg, OffsetReg);
MPO = MachinePointerInfo::getStack(MIRBuilder.getMF(), Offset);
return AddrReg.getReg(0);
}
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, LLT MemTy,
MachinePointerInfo &MPO, CCValAssign &VA) override {
Register ExtReg = extendRegister(ValVReg, VA);
auto MMO = MIRBuilder.getMF().getMachineMemOperand(
MPO, MachineMemOperand::MOStore, MemTy, Align(1));
MIRBuilder.buildStore(ExtReg, Addr, *MMO);
}
unsigned assignCustomValue(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");
// Custom lowering for other types, such as f16, is currently not supported
if (VA.getValVT() != MVT::f64)
return 0;
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;
}
MachineInstrBuilder MIB;
};
} // end anonymous namespace
/// 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();
const auto &DL = MF.getDataLayout();
auto &TLI = *getTLI<ARMTargetLowering>();
if (!isSupportedType(DL, TLI, Val->getType()))
return false;
ArgInfo OrigRetInfo(VRegs, Val->getType(), 0);
setArgFlags(OrigRetInfo, AttributeList::ReturnIndex, DL, F);
SmallVector<ArgInfo, 4> SplitRetInfos;
splitToValueTypes(OrigRetInfo, SplitRetInfos, DL, F.getCallingConv());
CCAssignFn *AssignFn =
TLI.CCAssignFnForReturn(F.getCallingConv(), F.isVarArg());
OutgoingValueAssigner RetAssigner(AssignFn);
ARMOutgoingValueHandler RetHandler(MIRBuilder, MF.getRegInfo(), Ret);
return determineAndHandleAssignments(RetHandler, RetAssigner, SplitRetInfos,
MIRBuilder, F.getCallingConv(),
F.isVarArg());
}
bool ARMCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
const Value *Val, ArrayRef<Register> VRegs,
FunctionLoweringInfo &FLI) 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 ARMIncomingValueHandler : public CallLowering::IncomingValueHandler {
ARMIncomingValueHandler(MachineIRBuilder &MIRBuilder,
MachineRegisterInfo &MRI)
: IncomingValueHandler(MIRBuilder, MRI) {}
Register getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO,
ISD::ArgFlagsTy Flags) override {
assert((Size == 1 || Size == 2 || Size == 4 || Size == 8) &&
"Unsupported size");
auto &MFI = MIRBuilder.getMF().getFrameInfo();
// Byval is assumed to be writable memory, but other stack passed arguments
// are not.
const bool IsImmutable = !Flags.isByVal();
int FI = MFI.CreateFixedObject(Size, Offset, IsImmutable);
MPO = MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);
return MIRBuilder.buildFrameIndex(LLT::pointer(MPO.getAddrSpace(), 32), FI)
.getReg(0);
}
void assignValueToAddress(Register ValVReg, Register Addr, LLT MemTy,
MachinePointerInfo &MPO, CCValAssign &VA) override {
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.
MemTy = LLT::scalar(32);
assert(MRI.getType(ValVReg).isScalar() && "Only scalars supported atm");
auto LoadVReg = buildLoad(LLT::scalar(32), Addr, MemTy, MPO);
MIRBuilder.buildTrunc(ValVReg, LoadVReg);
} else {
// If the value is not extended, a simple load will suffice.
buildLoad(ValVReg, Addr, MemTy, MPO);
}
}
MachineInstrBuilder buildLoad(const DstOp &Res, Register Addr, LLT MemTy,
MachinePointerInfo &MPO) {
MachineFunction &MF = MIRBuilder.getMF();
auto MMO = MF.getMachineMemOperand(MPO, MachineMemOperand::MOLoad, MemTy,
inferAlignFromPtrInfo(MF, MPO));
return MIRBuilder.buildLoad(Res, 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?");
uint64_t ValSize = VA.getValVT().getFixedSizeInBits();
uint64_t LocSize = VA.getLocVT().getFixedSizeInBits();
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 = MIRBuilder.buildCopy(LLT::scalar(LocSize), PhysReg);
MIRBuilder.buildTrunc(ValVReg, PhysRegToVReg);
}
}
unsigned assignCustomValue(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");
// Custom lowering for other types, such as f16, is currently not supported
if (VA.getValVT() != MVT::f64)
return 0;
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 ARMIncomingValueHandler {
FormalArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI)
: ARMIncomingValueHandler(MIRBuilder, MRI) {}
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,
FunctionLoweringInfo &FLI) 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();
const auto &DL = MF.getDataLayout();
for (auto &Arg : F.args()) {
if (!isSupportedType(DL, TLI, Arg.getType()))
return false;
if (Arg.hasPassPointeeByValueCopyAttr())
return false;
}
CCAssignFn *AssignFn =
TLI.CCAssignFnForCall(F.getCallingConv(), F.isVarArg());
OutgoingValueAssigner ArgAssigner(AssignFn);
FormalArgHandler ArgHandler(MIRBuilder, MIRBuilder.getMF().getRegInfo());
SmallVector<ArgInfo, 8> SplitArgInfos;
unsigned Idx = 0;
for (auto &Arg : F.args()) {
ArgInfo OrigArgInfo(VRegs[Idx], Arg.getType(), Idx);
setArgFlags(OrigArgInfo, Idx + AttributeList::FirstArgIndex, DL, F);
splitToValueTypes(OrigArgInfo, SplitArgInfos, DL, F.getCallingConv());
Idx++;
}
if (!MBB.empty())
MIRBuilder.setInstr(*MBB.begin());
if (!determineAndHandleAssignments(ArgHandler, ArgAssigner, SplitArgInfos,
MIRBuilder, F.getCallingConv(),
F.isVarArg()))
return false;
// Move back to the end of the basic block.
MIRBuilder.setMBB(MBB);
return true;
}
namespace {
struct CallReturnHandler : public ARMIncomingValueHandler {
CallReturnHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder MIB)
: ARMIncomingValueHandler(MIRBuilder, MRI), 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 MachineFunction &MF, const ARMSubtarget &STI,
bool isDirect) {
if (isDirect)
return STI.isThumb() ? ARM::tBL : ARM::BL;
if (STI.isThumb())
return gettBLXrOpcode(MF);
if (STI.hasV5TOps())
return getBLXOpcode(MF);
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(MF, 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));
SmallVector<ArgInfo, 8> ArgInfos;
for (auto Arg : Info.OrigArgs) {
if (!isSupportedType(DL, TLI, Arg.Ty))
return false;
if (Arg.Flags[0].isByVal())
return false;
splitToValueTypes(Arg, ArgInfos, DL, Info.CallConv);
}
auto ArgAssignFn = TLI.CCAssignFnForCall(Info.CallConv, Info.IsVarArg);
OutgoingValueAssigner ArgAssigner(ArgAssignFn);
ARMOutgoingValueHandler ArgHandler(MIRBuilder, MRI, MIB);
if (!determineAndHandleAssignments(ArgHandler, ArgAssigner, ArgInfos,
MIRBuilder, Info.CallConv, Info.IsVarArg))
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, DL, Info.CallConv);
auto RetAssignFn = TLI.CCAssignFnForReturn(Info.CallConv, Info.IsVarArg);
OutgoingValueAssigner Assigner(RetAssignFn);
CallReturnHandler RetHandler(MIRBuilder, MRI, MIB);
if (!determineAndHandleAssignments(RetHandler, Assigner, ArgInfos,
MIRBuilder, Info.CallConv,
Info.IsVarArg))
return false;
}
// We now know the size of the stack - update the ADJCALLSTACKDOWN
// accordingly.
CallSeqStart.addImm(ArgAssigner.StackOffset)
.addImm(0)
.add(predOps(ARMCC::AL));
MIRBuilder.buildInstr(ARM::ADJCALLSTACKUP)
.addImm(ArgAssigner.StackOffset)
.addImm(0)
.add(predOps(ARMCC::AL));
return true;
}
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