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llvm-mirror/lib/Target/AArch64/AArch64CallLowering.cpp
Chandler Carruth ae65e281f3 Update the file headers across all of the LLVM projects in the monorepo 
to reflect the new license.

We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.

Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.

llvm-svn: 351636
2019-01-19 08:50:56 +00:00

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//===--- AArch64CallLowering.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 "AArch64CallLowering.h"
#include "AArch64ISelLowering.h"
#include "AArch64MachineFunctionInfo.h"
#include "AArch64Subtarget.h"
#include "llvm/ADT/ArrayRef.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/Argument.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/Support/MachineValueType.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <iterator>
using namespace llvm;
AArch64CallLowering::AArch64CallLowering(const AArch64TargetLowering &TLI)
: CallLowering(&TLI) {}
namespace {
struct IncomingArgHandler : public CallLowering::ValueHandler {
IncomingArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn *AssignFn)
: ValueHandler(MIRBuilder, MRI, AssignFn), StackUsed(0) {}
unsigned getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO) override {
auto &MFI = MIRBuilder.getMF().getFrameInfo();
int FI = MFI.CreateFixedObject(Size, Offset, true);
MPO = MachinePointerInfo::getFixedStack(MIRBuilder.getMF(), FI);
unsigned AddrReg = MRI.createGenericVirtualRegister(LLT::pointer(0, 64));
MIRBuilder.buildFrameIndex(AddrReg, FI);
StackUsed = std::max(StackUsed, Size + Offset);
return AddrReg;
}
void assignValueToReg(unsigned ValVReg, unsigned PhysReg,
CCValAssign &VA) override {
markPhysRegUsed(PhysReg);
switch (VA.getLocInfo()) {
default:
MIRBuilder.buildCopy(ValVReg, PhysReg);
break;
case CCValAssign::LocInfo::SExt:
case CCValAssign::LocInfo::ZExt:
case CCValAssign::LocInfo::AExt: {
auto Copy = MIRBuilder.buildCopy(LLT{VA.getLocVT()}, PhysReg);
MIRBuilder.buildTrunc(ValVReg, Copy);
break;
}
}
}
void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
MachinePointerInfo &MPO, CCValAssign &VA) override {
auto MMO = MIRBuilder.getMF().getMachineMemOperand(
MPO, MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant, Size,
0);
MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
}
/// How the physical register gets marked varies between formal
/// parameters (it's a basic-block live-in), and a call instruction
/// (it's an implicit-def of the BL).
virtual void markPhysRegUsed(unsigned PhysReg) = 0;
uint64_t StackUsed;
};
struct FormalArgHandler : public IncomingArgHandler {
FormalArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn *AssignFn)
: IncomingArgHandler(MIRBuilder, MRI, AssignFn) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIRBuilder.getMBB().addLiveIn(PhysReg);
}
};
struct CallReturnHandler : public IncomingArgHandler {
CallReturnHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder MIB, CCAssignFn *AssignFn)
: IncomingArgHandler(MIRBuilder, MRI, AssignFn), MIB(MIB) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIB.addDef(PhysReg, RegState::Implicit);
}
MachineInstrBuilder MIB;
};
struct OutgoingArgHandler : public CallLowering::ValueHandler {
OutgoingArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder MIB, CCAssignFn *AssignFn,
CCAssignFn *AssignFnVarArg)
: ValueHandler(MIRBuilder, MRI, AssignFn), MIB(MIB),
AssignFnVarArg(AssignFnVarArg), StackSize(0) {}
unsigned getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO) override {
LLT p0 = LLT::pointer(0, 64);
LLT s64 = LLT::scalar(64);
unsigned SPReg = MRI.createGenericVirtualRegister(p0);
MIRBuilder.buildCopy(SPReg, AArch64::SP);
unsigned OffsetReg = MRI.createGenericVirtualRegister(s64);
MIRBuilder.buildConstant(OffsetReg, Offset);
unsigned AddrReg = MRI.createGenericVirtualRegister(p0);
MIRBuilder.buildGEP(AddrReg, SPReg, OffsetReg);
MPO = MachinePointerInfo::getStack(MIRBuilder.getMF(), Offset);
return AddrReg;
}
void assignValueToReg(unsigned ValVReg, unsigned PhysReg,
CCValAssign &VA) override {
MIB.addUse(PhysReg, RegState::Implicit);
unsigned ExtReg = extendRegister(ValVReg, VA);
MIRBuilder.buildCopy(PhysReg, ExtReg);
}
void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
MachinePointerInfo &MPO, CCValAssign &VA) override {
if (VA.getLocInfo() == CCValAssign::LocInfo::AExt) {
Size = VA.getLocVT().getSizeInBits() / 8;
ValVReg = MIRBuilder.buildAnyExt(LLT::scalar(Size * 8), ValVReg)
->getOperand(0)
.getReg();
}
auto MMO = MIRBuilder.getMF().getMachineMemOperand(
MPO, MachineMemOperand::MOStore, Size, 0);
MIRBuilder.buildStore(ValVReg, Addr, *MMO);
}
bool assignArg(unsigned ValNo, MVT ValVT, MVT LocVT,
CCValAssign::LocInfo LocInfo,
const CallLowering::ArgInfo &Info,
CCState &State) override {
bool Res;
if (Info.IsFixed)
Res = AssignFn(ValNo, ValVT, LocVT, LocInfo, Info.Flags, State);
else
Res = AssignFnVarArg(ValNo, ValVT, LocVT, LocInfo, Info.Flags, State);
StackSize = State.getNextStackOffset();
return Res;
}
MachineInstrBuilder MIB;
CCAssignFn *AssignFnVarArg;
uint64_t StackSize;
};
} // namespace
void AArch64CallLowering::splitToValueTypes(
const ArgInfo &OrigArg, SmallVectorImpl<ArgInfo> &SplitArgs,
const DataLayout &DL, MachineRegisterInfo &MRI, CallingConv::ID CallConv,
const SplitArgTy &PerformArgSplit) const {
const AArch64TargetLowering &TLI = *getTLI<AArch64TargetLowering>();
LLVMContext &Ctx = OrigArg.Ty->getContext();
if (OrigArg.Ty->isVoidTy())
return;
SmallVector<EVT, 4> SplitVTs;
SmallVector<uint64_t, 4> Offsets;
ComputeValueVTs(TLI, DL, OrigArg.Ty, SplitVTs, &Offsets, 0);
if (SplitVTs.size() == 1) {
// No splitting to do, but we want to replace the original type (e.g. [1 x
// double] -> double).
SplitArgs.emplace_back(OrigArg.Reg, SplitVTs[0].getTypeForEVT(Ctx),
OrigArg.Flags, OrigArg.IsFixed);
return;
}
unsigned FirstRegIdx = SplitArgs.size();
bool NeedsRegBlock = TLI.functionArgumentNeedsConsecutiveRegisters(
OrigArg.Ty, CallConv, false);
for (auto SplitVT : SplitVTs) {
Type *SplitTy = SplitVT.getTypeForEVT(Ctx);
SplitArgs.push_back(
ArgInfo{MRI.createGenericVirtualRegister(getLLTForType(*SplitTy, DL)),
SplitTy, OrigArg.Flags, OrigArg.IsFixed});
if (NeedsRegBlock)
SplitArgs.back().Flags.setInConsecutiveRegs();
}
SplitArgs.back().Flags.setInConsecutiveRegsLast();
for (unsigned i = 0; i < Offsets.size(); ++i)
PerformArgSplit(SplitArgs[FirstRegIdx + i].Reg, Offsets[i] * 8);
}
bool AArch64CallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
const Value *Val,
ArrayRef<unsigned> VRegs) const {
auto MIB = MIRBuilder.buildInstrNoInsert(AArch64::RET_ReallyLR);
assert(((Val && !VRegs.empty()) || (!Val && VRegs.empty())) &&
"Return value without a vreg");
bool Success = true;
if (!VRegs.empty()) {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
MachineRegisterInfo &MRI = MF.getRegInfo();
const AArch64TargetLowering &TLI = *getTLI<AArch64TargetLowering>();
CCAssignFn *AssignFn = TLI.CCAssignFnForReturn(F.getCallingConv());
auto &DL = F.getParent()->getDataLayout();
LLVMContext &Ctx = Val->getType()->getContext();
SmallVector<EVT, 4> SplitEVTs;
ComputeValueVTs(TLI, DL, Val->getType(), SplitEVTs);
assert(VRegs.size() == SplitEVTs.size() &&
"For each split Type there should be exactly one VReg.");
SmallVector<ArgInfo, 8> SplitArgs;
for (unsigned i = 0; i < SplitEVTs.size(); ++i) {
// We zero-extend i1s to i8.
unsigned CurVReg = VRegs[i];
if (MRI.getType(VRegs[i]).getSizeInBits() == 1) {
CurVReg = MIRBuilder.buildZExt(LLT::scalar(8), CurVReg)
->getOperand(0)
.getReg();
}
ArgInfo CurArgInfo = ArgInfo{CurVReg, SplitEVTs[i].getTypeForEVT(Ctx)};
setArgFlags(CurArgInfo, AttributeList::ReturnIndex, DL, F);
splitToValueTypes(CurArgInfo, SplitArgs, DL, MRI, F.getCallingConv(),
[&](unsigned Reg, uint64_t Offset) {
MIRBuilder.buildExtract(Reg, CurVReg, Offset);
});
}
OutgoingArgHandler Handler(MIRBuilder, MRI, MIB, AssignFn, AssignFn);
Success = handleAssignments(MIRBuilder, SplitArgs, Handler);
}
MIRBuilder.insertInstr(MIB);
return Success;
}
bool AArch64CallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
const Function &F,
ArrayRef<unsigned> VRegs) const {
MachineFunction &MF = MIRBuilder.getMF();
MachineBasicBlock &MBB = MIRBuilder.getMBB();
MachineRegisterInfo &MRI = MF.getRegInfo();
auto &DL = F.getParent()->getDataLayout();
SmallVector<ArgInfo, 8> SplitArgs;
unsigned i = 0;
for (auto &Arg : F.args()) {
if (DL.getTypeStoreSize(Arg.getType()) == 0)
continue;
ArgInfo OrigArg{VRegs[i], Arg.getType()};
setArgFlags(OrigArg, i + AttributeList::FirstArgIndex, DL, F);
bool Split = false;
LLT Ty = MRI.getType(VRegs[i]);
unsigned Dst = VRegs[i];
splitToValueTypes(OrigArg, SplitArgs, DL, MRI, F.getCallingConv(),
[&](unsigned Reg, uint64_t Offset) {
if (!Split) {
Split = true;
Dst = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildUndef(Dst);
}
unsigned Tmp = MRI.createGenericVirtualRegister(Ty);
MIRBuilder.buildInsert(Tmp, Dst, Reg, Offset);
Dst = Tmp;
});
if (Dst != VRegs[i])
MIRBuilder.buildCopy(VRegs[i], Dst);
++i;
}
if (!MBB.empty())
MIRBuilder.setInstr(*MBB.begin());
const AArch64TargetLowering &TLI = *getTLI<AArch64TargetLowering>();
CCAssignFn *AssignFn =
TLI.CCAssignFnForCall(F.getCallingConv(), /*IsVarArg=*/false);
FormalArgHandler Handler(MIRBuilder, MRI, AssignFn);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
if (F.isVarArg()) {
if (!MF.getSubtarget<AArch64Subtarget>().isTargetDarwin()) {
// FIXME: we need to reimplement saveVarArgsRegisters from
// AArch64ISelLowering.
return false;
}
// We currently pass all varargs at 8-byte alignment.
uint64_t StackOffset = alignTo(Handler.StackUsed, 8);
auto &MFI = MIRBuilder.getMF().getFrameInfo();
AArch64FunctionInfo *FuncInfo = MF.getInfo<AArch64FunctionInfo>();
FuncInfo->setVarArgsStackIndex(MFI.CreateFixedObject(4, StackOffset, true));
}
auto &Subtarget = MF.getSubtarget<AArch64Subtarget>();
if (Subtarget.hasCustomCallingConv())
Subtarget.getRegisterInfo()->UpdateCustomCalleeSavedRegs(MF);
// Move back to the end of the basic block.
MIRBuilder.setMBB(MBB);
return true;
}
bool AArch64CallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
CallingConv::ID CallConv,
const MachineOperand &Callee,
const ArgInfo &OrigRet,
ArrayRef<ArgInfo> OrigArgs) const {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
MachineRegisterInfo &MRI = MF.getRegInfo();
auto &DL = F.getParent()->getDataLayout();
SmallVector<ArgInfo, 8> SplitArgs;
for (auto &OrigArg : OrigArgs) {
splitToValueTypes(OrigArg, SplitArgs, DL, MRI, CallConv,
[&](unsigned Reg, uint64_t Offset) {
MIRBuilder.buildExtract(Reg, OrigArg.Reg, Offset);
});
}
// Find out which ABI gets to decide where things go.
const AArch64TargetLowering &TLI = *getTLI<AArch64TargetLowering>();
CCAssignFn *AssignFnFixed =
TLI.CCAssignFnForCall(CallConv, /*IsVarArg=*/false);
CCAssignFn *AssignFnVarArg =
TLI.CCAssignFnForCall(CallConv, /*IsVarArg=*/true);
auto CallSeqStart = MIRBuilder.buildInstr(AArch64::ADJCALLSTACKDOWN);
// Create a temporarily-floating call instruction so we can add the implicit
// uses of arg registers.
auto MIB = MIRBuilder.buildInstrNoInsert(Callee.isReg() ? AArch64::BLR
: AArch64::BL);
MIB.add(Callee);
// Tell the call which registers are clobbered.
auto TRI = MF.getSubtarget<AArch64Subtarget>().getRegisterInfo();
const uint32_t *Mask = TRI->getCallPreservedMask(MF, F.getCallingConv());
if (MF.getSubtarget<AArch64Subtarget>().hasCustomCallingConv())
TRI->UpdateCustomCallPreservedMask(MF, &Mask);
MIB.addRegMask(Mask);
if (TRI->isAnyArgRegReserved(MF))
TRI->emitReservedArgRegCallError(MF);
// Do the actual argument marshalling.
SmallVector<unsigned, 8> PhysRegs;
OutgoingArgHandler Handler(MIRBuilder, MRI, MIB, AssignFnFixed,
AssignFnVarArg);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
// Now we can add the actual call instruction to the correct basic block.
MIRBuilder.insertInstr(MIB);
// If Callee is a reg, since it is used by a target specific
// instruction, it must have a register class matching the
// constraint of that instruction.
if (Callee.isReg())
MIB->getOperand(0).setReg(constrainOperandRegClass(
MF, *TRI, MRI, *MF.getSubtarget().getInstrInfo(),
*MF.getSubtarget().getRegBankInfo(), *MIB, MIB->getDesc(), Callee, 0));
// Finally we can copy the returned value back into its virtual-register. In
// symmetry with the arugments, the physical register must be an
// implicit-define of the call instruction.
CCAssignFn *RetAssignFn = TLI.CCAssignFnForReturn(F.getCallingConv());
if (OrigRet.Reg) {
SplitArgs.clear();
SmallVector<uint64_t, 8> RegOffsets;
SmallVector<unsigned, 8> SplitRegs;
splitToValueTypes(OrigRet, SplitArgs, DL, MRI, F.getCallingConv(),
[&](unsigned Reg, uint64_t Offset) {
RegOffsets.push_back(Offset);
SplitRegs.push_back(Reg);
});
CallReturnHandler Handler(MIRBuilder, MRI, MIB, RetAssignFn);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
if (!RegOffsets.empty())
MIRBuilder.buildSequence(OrigRet.Reg, SplitRegs, RegOffsets);
}
CallSeqStart.addImm(Handler.StackSize).addImm(0);
MIRBuilder.buildInstr(AArch64::ADJCALLSTACKUP)
.addImm(Handler.StackSize)
.addImm(0);
return true;
}
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