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llvm-project/llvm/lib/Target/X86/X86CallLowering.cpp

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//===- llvm/lib/Target/X86/X86CallLowering.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 "X86CallLowering.h"
#include "X86CallingConv.h"
#include "X86ISelLowering.h"
#include "X86InstrInfo.h"
#include "X86RegisterInfo.h"
#include "X86Subtarget.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/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/CodeGen/ValueTypes.h"
#include "llvm/IR/Attributes.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Value.h"
#include "llvm/MC/MCRegisterInfo.h"
#include "llvm/Support/LowLevelTypeImpl.h"
#include "llvm/Support/MachineValueType.h"
#include <cassert>
#include <cstdint>
using namespace llvm;
X86CallLowering::X86CallLowering(const X86TargetLowering &TLI)
: CallLowering(&TLI) {}
bool X86CallLowering::splitToValueTypes(const ArgInfo &OrigArg,
SmallVectorImpl<ArgInfo> &SplitArgs,
const DataLayout &DL,
MachineRegisterInfo &MRI,
SplitArgTy PerformArgSplit) const {
const X86TargetLowering &TLI = *getTLI<X86TargetLowering>();
LLVMContext &Context = OrigArg.Ty->getContext();
SmallVector<EVT, 4> SplitVTs;
SmallVector<uint64_t, 4> Offsets;
ComputeValueVTs(TLI, DL, OrigArg.Ty, SplitVTs, &Offsets, 0);
if (OrigArg.Ty->isVoidTy())
return true;
EVT VT = SplitVTs[0];
unsigned NumParts = TLI.getNumRegisters(Context, VT);
if (NumParts == 1) {
// replace the original type ( pointer -> GPR ).
SplitArgs.emplace_back(OrigArg.Reg, VT.getTypeForEVT(Context),
OrigArg.Flags, OrigArg.IsFixed);
return true;
}
SmallVector<unsigned, 8> SplitRegs;
EVT PartVT = TLI.getRegisterType(Context, VT);
Type *PartTy = PartVT.getTypeForEVT(Context);
for (unsigned i = 0; i < NumParts; ++i) {
ArgInfo Info =
ArgInfo{MRI.createGenericVirtualRegister(getLLTForType(*PartTy, DL)),
PartTy, OrigArg.Flags};
SplitArgs.push_back(Info);
SplitRegs.push_back(Info.Reg);
}
PerformArgSplit(SplitRegs);
return true;
}
namespace {
struct OutgoingValueHandler : public CallLowering::ValueHandler {
OutgoingValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder &MIB, CCAssignFn *AssignFn)
: ValueHandler(MIRBuilder, MRI, AssignFn), MIB(MIB),
DL(MIRBuilder.getMF().getDataLayout()),
STI(MIRBuilder.getMF().getSubtarget<X86Subtarget>()) {}
unsigned getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO) override {
LLT p0 = LLT::pointer(0, DL.getPointerSizeInBits(0));
LLT SType = LLT::scalar(DL.getPointerSizeInBits(0));
unsigned SPReg = MRI.createGenericVirtualRegister(p0);
MIRBuilder.buildCopy(SPReg, STI.getRegisterInfo()->getStackRegister());
unsigned OffsetReg = MRI.createGenericVirtualRegister(SType);
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;
// If we are copying the value to a physical register with the
// size larger than the size of the value itself - build AnyExt
// to the size of the register first and only then do the copy.
// The example of that would be copying from s32 to xmm0, for which
// case ValVT == LocVT == MVT::f32. If LocSize and ValSize are not equal
// we expect normal extendRegister mechanism to work.
unsigned PhysRegSize =
MRI.getTargetRegisterInfo()->getRegSizeInBits(PhysReg, MRI);
unsigned ValSize = VA.getValVT().getSizeInBits();
unsigned LocSize = VA.getLocVT().getSizeInBits();
if (PhysRegSize > ValSize && LocSize == ValSize) {
assert((PhysRegSize == 128 || PhysRegSize == 80) && "We expect that to be 128 bit");
auto MIB = MIRBuilder.buildAnyExt(LLT::scalar(PhysRegSize), ValVReg);
ExtReg = MIB->getOperand(0).getReg();
} else
ExtReg = extendRegister(ValVReg, VA);
MIRBuilder.buildCopy(PhysReg, ExtReg);
}
void assignValueToAddress(unsigned ValVReg, unsigned Addr, uint64_t Size,
MachinePointerInfo &MPO, CCValAssign &VA) override {
unsigned ExtReg = extendRegister(ValVReg, VA);
auto MMO = MIRBuilder.getMF().getMachineMemOperand(
MPO, MachineMemOperand::MOStore, VA.getLocVT().getStoreSize(),
/* Alignment */ 1);
MIRBuilder.buildStore(ExtReg, Addr, *MMO);
}
bool assignArg(unsigned ValNo, MVT ValVT, MVT LocVT,
CCValAssign::LocInfo LocInfo,
const CallLowering::ArgInfo &Info, CCState &State) override {
bool Res = AssignFn(ValNo, ValVT, LocVT, LocInfo, Info.Flags, State);
StackSize = State.getNextStackOffset();
static const MCPhysReg XMMArgRegs[] = {X86::XMM0, X86::XMM1, X86::XMM2,
X86::XMM3, X86::XMM4, X86::XMM5,
X86::XMM6, X86::XMM7};
if (!Info.IsFixed)
NumXMMRegs = State.getFirstUnallocated(XMMArgRegs);
return Res;
}
uint64_t getStackSize() { return StackSize; }
uint64_t getNumXmmRegs() { return NumXMMRegs; }
protected:
MachineInstrBuilder &MIB;
uint64_t StackSize = 0;
const DataLayout &DL;
const X86Subtarget &STI;
unsigned NumXMMRegs = 0;
};
} // end anonymous namespace
bool X86CallLowering::lowerReturn(
MachineIRBuilder &MIRBuilder, const Value *Val,
ArrayRef<unsigned> VRegs) const {
assert(((Val && !VRegs.empty()) || (!Val && VRegs.empty())) &&
"Return value without a vreg");
auto MIB = MIRBuilder.buildInstrNoInsert(X86::RET).addImm(0);
if (!VRegs.empty()) {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
MachineRegisterInfo &MRI = MF.getRegInfo();
auto &DL = MF.getDataLayout();
LLVMContext &Ctx = Val->getType()->getContext();
const X86TargetLowering &TLI = *getTLI<X86TargetLowering>();
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) {
ArgInfo CurArgInfo = ArgInfo{VRegs[i], SplitEVTs[i].getTypeForEVT(Ctx)};
setArgFlags(CurArgInfo, AttributeList::ReturnIndex, DL, F);
if (!splitToValueTypes(CurArgInfo, SplitArgs, DL, MRI,
[&](ArrayRef<unsigned> Regs) {
MIRBuilder.buildUnmerge(Regs, VRegs[i]);
}))
return false;
}
OutgoingValueHandler Handler(MIRBuilder, MRI, MIB, RetCC_X86);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
}
MIRBuilder.insertInstr(MIB);
return true;
}
namespace {
struct IncomingValueHandler : public CallLowering::ValueHandler {
IncomingValueHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn *AssignFn)
: ValueHandler(MIRBuilder, MRI, AssignFn),
DL(MIRBuilder.getMF().getDataLayout()) {}
bool isArgumentHandler() const override { return true; }
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, DL.getPointerSizeInBits(0)));
MIRBuilder.buildFrameIndex(AddrReg, FI);
return AddrReg;
}
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,
1);
MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
}
void assignValueToReg(unsigned ValVReg, unsigned PhysReg,
CCValAssign &VA) override {
markPhysRegUsed(PhysReg);
switch (VA.getLocInfo()) {
default: {
// If we are copying the value from a physical register with the
// size larger than the size of the value itself - build the copy
// of the phys reg first and then build the truncation of that copy.
// The example of that would be copying from xmm0 to s32, for which
// case ValVT == LocVT == MVT::f32. If LocSize and ValSize are not equal
// we expect this to be handled in SExt/ZExt/AExt case.
unsigned PhysRegSize =
MRI.getTargetRegisterInfo()->getRegSizeInBits(PhysReg, MRI);
unsigned ValSize = VA.getValVT().getSizeInBits();
unsigned LocSize = VA.getLocVT().getSizeInBits();
if (PhysRegSize > ValSize && LocSize == ValSize) {
auto Copy = MIRBuilder.buildCopy(LLT::scalar(PhysRegSize), PhysReg);
MIRBuilder.buildTrunc(ValVReg, Copy);
return;
}
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;
}
}
}
/// 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;
protected:
const DataLayout &DL;
};
struct FormalArgHandler : public IncomingValueHandler {
FormalArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn *AssignFn)
: IncomingValueHandler(MIRBuilder, MRI, AssignFn) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIRBuilder.getMBB().addLiveIn(PhysReg);
}
};
struct CallReturnHandler : public IncomingValueHandler {
CallReturnHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
CCAssignFn *AssignFn, MachineInstrBuilder &MIB)
: IncomingValueHandler(MIRBuilder, MRI, AssignFn), MIB(MIB) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIB.addDef(PhysReg, RegState::Implicit);
}
protected:
MachineInstrBuilder &MIB;
};
} // end anonymous namespace
bool X86CallLowering::lowerFormalArguments(MachineIRBuilder &MIRBuilder,
const Function &F,
ArrayRef<unsigned> VRegs) const {
if (F.arg_empty())
return true;
// TODO: handle variadic function
if (F.isVarArg())
return false;
MachineFunction &MF = MIRBuilder.getMF();
MachineRegisterInfo &MRI = MF.getRegInfo();
auto DL = MF.getDataLayout();
SmallVector<ArgInfo, 8> SplitArgs;
unsigned Idx = 0;
for (auto &Arg : F.args()) {
// TODO: handle not simple cases.
if (Arg.hasAttribute(Attribute::ByVal) ||
Arg.hasAttribute(Attribute::InReg) ||
Arg.hasAttribute(Attribute::StructRet) ||
Arg.hasAttribute(Attribute::SwiftSelf) ||
Arg.hasAttribute(Attribute::SwiftError) ||
Arg.hasAttribute(Attribute::Nest))
return false;
ArgInfo OrigArg(VRegs[Idx], Arg.getType());
setArgFlags(OrigArg, Idx + AttributeList::FirstArgIndex, DL, F);
if (!splitToValueTypes(OrigArg, SplitArgs, DL, MRI,
[&](ArrayRef<unsigned> Regs) {
MIRBuilder.buildMerge(VRegs[Idx], Regs);
}))
return false;
Idx++;
}
MachineBasicBlock &MBB = MIRBuilder.getMBB();
if (!MBB.empty())
MIRBuilder.setInstr(*MBB.begin());
FormalArgHandler Handler(MIRBuilder, MRI, CC_X86);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
// Move back to the end of the basic block.
MIRBuilder.setMBB(MBB);
return true;
}
bool X86CallLowering::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();
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
const TargetInstrInfo &TII = *STI.getInstrInfo();
auto TRI = STI.getRegisterInfo();
// Handle only Linux C, X86_64_SysV calling conventions for now.
if (!STI.isTargetLinux() ||
!(CallConv == CallingConv::C || CallConv == CallingConv::X86_64_SysV))
return false;
unsigned AdjStackDown = TII.getCallFrameSetupOpcode();
auto CallSeqStart = MIRBuilder.buildInstr(AdjStackDown);
// Create a temporarily-floating call instruction so we can add the implicit
// uses of arg registers.
bool Is64Bit = STI.is64Bit();
unsigned CallOpc = Callee.isReg()
? (Is64Bit ? X86::CALL64r : X86::CALL32r)
: (Is64Bit ? X86::CALL64pcrel32 : X86::CALLpcrel32);
auto MIB = MIRBuilder.buildInstrNoInsert(CallOpc).add(Callee).addRegMask(
TRI->getCallPreservedMask(MF, CallConv));
SmallVector<ArgInfo, 8> SplitArgs;
for (const auto &OrigArg : OrigArgs) {
// TODO: handle not simple cases.
if (OrigArg.Flags.isByVal())
return false;
if (!splitToValueTypes(OrigArg, SplitArgs, DL, MRI,
[&](ArrayRef<unsigned> Regs) {
MIRBuilder.buildUnmerge(Regs, OrigArg.Reg);
}))
return false;
}
// Do the actual argument marshalling.
OutgoingValueHandler Handler(MIRBuilder, MRI, MIB, CC_X86);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
bool IsFixed = OrigArgs.empty() ? true : OrigArgs.back().IsFixed;
if (STI.is64Bit() && !IsFixed && !STI.isCallingConvWin64(CallConv)) {
// From AMD64 ABI document:
// For calls that may call functions that use varargs or stdargs
// (prototype-less calls or calls to functions containing ellipsis (...) in
// the declaration) %al is used as hidden argument to specify the number
// of SSE registers used. The contents of %al do not need to match exactly
// the number of registers, but must be an ubound on the number of SSE
// registers used and is in the range 0 - 8 inclusive.
MIRBuilder.buildInstr(X86::MOV8ri)
.addDef(X86::AL)
.addImm(Handler.getNumXmmRegs());
MIB.addUse(X86::AL, RegState::Implicit);
}
// 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 arguments, the physical register must be an
// implicit-define of the call instruction.
if (OrigRet.Reg) {
SplitArgs.clear();
SmallVector<unsigned, 8> NewRegs;
if (!splitToValueTypes(OrigRet, SplitArgs, DL, MRI,
[&](ArrayRef<unsigned> Regs) {
NewRegs.assign(Regs.begin(), Regs.end());
}))
return false;
CallReturnHandler Handler(MIRBuilder, MRI, RetCC_X86, MIB);
if (!handleAssignments(MIRBuilder, SplitArgs, Handler))
return false;
if (!NewRegs.empty())
MIRBuilder.buildMerge(OrigRet.Reg, NewRegs);
}
CallSeqStart.addImm(Handler.getStackSize())
.addImm(0 /* see getFrameTotalSize */)
.addImm(0 /* see getFrameAdjustment */);
unsigned AdjStackUp = TII.getCallFrameDestroyOpcode();
MIRBuilder.buildInstr(AdjStackUp)
.addImm(Handler.getStackSize())
.addImm(0 /* NumBytesForCalleeToPop */);
return true;
}
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