llvm/llvm/lib/Target/SystemZ/SystemZLDCleanup.cpp

//===-- SystemZLDCleanup.cpp - Clean up local-dynamic TLS accesses --------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This pass combines multiple accesses to local-dynamic TLS variables so that
// the TLS base address for the module is only fetched once per execution path
// through the function.
//
//===----------------------------------------------------------------------===//

#include "SystemZMachineFunctionInfo.h"
#include "SystemZTargetMachine.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/TargetInstrInfo.h"
#include "llvm/CodeGen/TargetRegisterInfo.h"
#include "llvm/Target/TargetMachine.h"

usingnamespacellvm;

namespace {

class SystemZLDCleanup : public MachineFunctionPass { … };

char SystemZLDCleanup::ID = …;

} // end anonymous namespace

INITIALIZE_PASS(…)

FunctionPass *llvm::createSystemZLDCleanupPass(SystemZTargetMachine &TM) { … }

void SystemZLDCleanup::getAnalysisUsage(AnalysisUsage &AU) const { … }

bool SystemZLDCleanup::runOnMachineFunction(MachineFunction &F) { … }

// Visit the dominator subtree rooted at Node in pre-order.
// If TLSBaseAddrReg is non-null, then use that to replace any
// TLS_LDCALL instructions. Otherwise, create the register
// when the first such instruction is seen, and then use it
// as we encounter more instructions.
bool SystemZLDCleanup::VisitNode(MachineDomTreeNode *Node,
                                 unsigned TLSBaseAddrReg) { … }

// Replace the TLS_LDCALL instruction I with a copy from TLSBaseAddrReg,
// returning the new instruction.
MachineInstr *SystemZLDCleanup::ReplaceTLSCall(MachineInstr *I,
                                               unsigned TLSBaseAddrReg) { … }

// Create a virtual register in *TLSBaseAddrReg, and populate it by
// inserting a copy instruction after I. Returns the new instruction.
MachineInstr *SystemZLDCleanup::SetRegister(MachineInstr *I,
                                            unsigned *TLSBaseAddrReg) { … }