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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) {}
namespace {
struct X86OutgoingValueAssigner : public CallLowering::OutgoingValueAssigner {
private:
uint64_t StackSize = 0;
unsigned NumXMMRegs = 0;
public:
uint64_t getStackSize() { return StackSize; }
unsigned getNumXmmRegs() { return NumXMMRegs; }
X86OutgoingValueAssigner(CCAssignFn *AssignFn_)
: CallLowering::OutgoingValueAssigner(AssignFn_) {}
bool assignArg(unsigned ValNo, EVT OrigVT, MVT ValVT, MVT LocVT,
CCValAssign::LocInfo LocInfo,
const CallLowering::ArgInfo &Info, ISD::ArgFlagsTy Flags,
CCState &State) override {
bool Res = AssignFn(ValNo, ValVT, LocVT, LocInfo, 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;
}
};
struct X86OutgoingValueHandler : public CallLowering::OutgoingValueHandler {
X86OutgoingValueHandler(MachineIRBuilder &MIRBuilder,
MachineRegisterInfo &MRI, MachineInstrBuilder &MIB)
: OutgoingValueHandler(MIRBuilder, MRI), MIB(MIB),
DL(MIRBuilder.getMF().getDataLayout()),
STI(MIRBuilder.getMF().getSubtarget<X86Subtarget>()) {}
Register getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO,
ISD::ArgFlagsTy Flags) override {
LLT p0 = LLT::pointer(0, DL.getPointerSizeInBits(0));
LLT SType = LLT::scalar(DL.getPointerSizeInBits(0));
auto SPReg =
MIRBuilder.buildCopy(p0, STI.getRegisterInfo()->getStackRegister());
auto OffsetReg = MIRBuilder.buildConstant(SType, 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 {
MIB.addUse(PhysReg, RegState::Implicit);
Register ExtReg = extendRegister(ValVReg, VA);
MIRBuilder.buildCopy(PhysReg, ExtReg);
}
void assignValueToAddress(Register ValVReg, Register Addr, LLT MemTy,
MachinePointerInfo &MPO, CCValAssign &VA) override {
MachineFunction &MF = MIRBuilder.getMF();
Register ExtReg = extendRegister(ValVReg, VA);
auto *MMO = MF.getMachineMemOperand(MPO, MachineMemOperand::MOStore, MemTy,
inferAlignFromPtrInfo(MF, MPO));
MIRBuilder.buildStore(ExtReg, Addr, *MMO);
}
protected:
MachineInstrBuilder &MIB;
const DataLayout &DL;
const X86Subtarget &STI;
};
} // end anonymous namespace
bool X86CallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
const Value *Val, ArrayRef<Register> VRegs,
FunctionLoweringInfo &FLI) 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();
const DataLayout &DL = MF.getDataLayout();
ArgInfo OrigRetInfo(VRegs, Val->getType(), 0);
setArgFlags(OrigRetInfo, AttributeList::ReturnIndex, DL, F);
SmallVector<ArgInfo, 4> SplitRetInfos;
splitToValueTypes(OrigRetInfo, SplitRetInfos, DL, F.getCallingConv());
X86OutgoingValueAssigner Assigner(RetCC_X86);
X86OutgoingValueHandler Handler(MIRBuilder, MRI, MIB);
if (!determineAndHandleAssignments(Handler, Assigner, SplitRetInfos,
MIRBuilder, F.getCallingConv(),
F.isVarArg()))
return false;
}
MIRBuilder.insertInstr(MIB);
return true;
}
namespace {
struct X86IncomingValueHandler : public CallLowering::IncomingValueHandler {
X86IncomingValueHandler(MachineIRBuilder &MIRBuilder,
MachineRegisterInfo &MRI)
: IncomingValueHandler(MIRBuilder, MRI),
DL(MIRBuilder.getMF().getDataLayout()) {}
Register getStackAddress(uint64_t Size, int64_t Offset,
MachinePointerInfo &MPO,
ISD::ArgFlagsTy Flags) override {
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(0, DL.getPointerSizeInBits(0)), FI)
.getReg(0);
}
void assignValueToAddress(Register ValVReg, Register Addr, LLT MemTy,
MachinePointerInfo &MPO, CCValAssign &VA) override {
MachineFunction &MF = MIRBuilder.getMF();
auto *MMO = MF.getMachineMemOperand(
MPO, MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant, MemTy,
inferAlignFromPtrInfo(MF, MPO));
MIRBuilder.buildLoad(ValVReg, Addr, *MMO);
}
void assignValueToReg(Register ValVReg, Register PhysReg,
CCValAssign &VA) override {
markPhysRegUsed(PhysReg);
IncomingValueHandler::assignValueToReg(ValVReg, PhysReg, VA);
}
/// 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 X86IncomingValueHandler {
FormalArgHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI)
: X86IncomingValueHandler(MIRBuilder, MRI) {}
void markPhysRegUsed(unsigned PhysReg) override {
MIRBuilder.getMRI()->addLiveIn(PhysReg);
MIRBuilder.getMBB().addLiveIn(PhysReg);
}
};
struct CallReturnHandler : public X86IncomingValueHandler {
CallReturnHandler(MachineIRBuilder &MIRBuilder, MachineRegisterInfo &MRI,
MachineInstrBuilder &MIB)
: X86IncomingValueHandler(MIRBuilder, MRI), 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<ArrayRef<Register>> VRegs,
FunctionLoweringInfo &FLI) 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 (const 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) || VRegs[Idx].size() > 1)
return false;
ArgInfo OrigArg(VRegs[Idx], Arg.getType(), Idx);
setArgFlags(OrigArg, Idx + AttributeList::FirstArgIndex, DL, F);
splitToValueTypes(OrigArg, SplitArgs, DL, F.getCallingConv());
Idx++;
}
MachineBasicBlock &MBB = MIRBuilder.getMBB();
if (!MBB.empty())
MIRBuilder.setInstr(*MBB.begin());
X86OutgoingValueAssigner Assigner(CC_X86);
FormalArgHandler Handler(MIRBuilder, MRI);
if (!determineAndHandleAssignments(Handler, Assigner, SplitArgs, MIRBuilder,
F.getCallingConv(), F.isVarArg()))
return false;
// Move back to the end of the basic block.
MIRBuilder.setMBB(MBB);
return true;
}
bool X86CallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
CallLoweringInfo &Info) const {
MachineFunction &MF = MIRBuilder.getMF();
const Function &F = MF.getFunction();
MachineRegisterInfo &MRI = MF.getRegInfo();
const DataLayout &DL = F.getParent()->getDataLayout();
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
const TargetInstrInfo &TII = *STI.getInstrInfo();
const X86RegisterInfo *TRI = STI.getRegisterInfo();
// Handle only Linux C, X86_64_SysV calling conventions for now.
if (!STI.isTargetLinux() || !(Info.CallConv == CallingConv::C ||
Info.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 = Info.Callee.isReg()
? (Is64Bit ? X86::CALL64r : X86::CALL32r)
: (Is64Bit ? X86::CALL64pcrel32 : X86::CALLpcrel32);
auto MIB = MIRBuilder.buildInstrNoInsert(CallOpc)
.add(Info.Callee)
.addRegMask(TRI->getCallPreservedMask(MF, Info.CallConv));
SmallVector<ArgInfo, 8> SplitArgs;
for (const auto &OrigArg : Info.OrigArgs) {
// TODO: handle not simple cases.
if (OrigArg.Flags[0].isByVal())
return false;
if (OrigArg.Regs.size() > 1)
return false;
splitToValueTypes(OrigArg, SplitArgs, DL, Info.CallConv);
}
// Do the actual argument marshalling.
X86OutgoingValueAssigner Assigner(CC_X86);
X86OutgoingValueHandler Handler(MIRBuilder, MRI, MIB);
if (!determineAndHandleAssignments(Handler, Assigner, SplitArgs, MIRBuilder,
Info.CallConv, Info.IsVarArg))
return false;
bool IsFixed = Info.OrigArgs.empty() ? true : Info.OrigArgs.back().IsFixed;
if (STI.is64Bit() && !IsFixed && !STI.isCallingConvWin64(Info.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(Assigner.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 (Info.Callee.isReg())
MIB->getOperand(0).setReg(constrainOperandRegClass(
MF, *TRI, MRI, *MF.getSubtarget().getInstrInfo(),
*MF.getSubtarget().getRegBankInfo(), *MIB, MIB->getDesc(), Info.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 (!Info.OrigRet.Ty->isVoidTy()) {
if (Info.OrigRet.Regs.size() > 1)
return false;
SplitArgs.clear();
SmallVector<Register, 8> NewRegs;
splitToValueTypes(Info.OrigRet, SplitArgs, DL, Info.CallConv);
X86OutgoingValueAssigner Assigner(RetCC_X86);
CallReturnHandler Handler(MIRBuilder, MRI, MIB);
if (!determineAndHandleAssignments(Handler, Assigner, SplitArgs, MIRBuilder,
Info.CallConv, Info.IsVarArg))
return false;
if (!NewRegs.empty())
MIRBuilder.buildMerge(Info.OrigRet.Regs[0], NewRegs);
}
CallSeqStart.addImm(Assigner.getStackSize())
.addImm(0 /* see getFrameTotalSize */)
.addImm(0 /* see getFrameAdjustment */);
unsigned AdjStackUp = TII.getCallFrameDestroyOpcode();
MIRBuilder.buildInstr(AdjStackUp)
.addImm(Assigner.getStackSize())
.addImm(0 /* NumBytesForCalleeToPop */);
return true;
}
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