llvm/llvm/lib/Target/AArch64/AArch64CleanupLocalDynamicTLSPass.cpp

//===-- AArch64CleanupLocalDynamicTLSPass.cpp ---------------------*- C++ -*-=//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// Local-dynamic access to thread-local variables proceeds in three stages.
//
// 1. The offset of this Module's thread-local area from TPIDR_EL0 is calculated
//    in much the same way as a general-dynamic TLS-descriptor access against
//    the special symbol _TLS_MODULE_BASE.
// 2. The variable's offset from _TLS_MODULE_BASE_ is calculated using
//    instructions with "dtprel" modifiers.
// 3. These two are added, together with TPIDR_EL0, to obtain the variable's
//    true address.
//
// This is only better than general-dynamic access to the variable if two or
// more of the first stage TLS-descriptor calculations can be combined. This
// pass looks through a function and performs such combinations.
//
//===----------------------------------------------------------------------===//
#include "AArch64.h"
#include "AArch64InstrInfo.h"
#include "AArch64MachineFunctionInfo.h"
#include "llvm/CodeGen/MachineDominators.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
usingnamespacellvm;

#define TLSCLEANUP_PASS_NAME …

namespace {
struct LDTLSCleanup : public MachineFunctionPass { … };
}

INITIALIZE_PASS(…)

char LDTLSCleanup::ID = …;
FunctionPass *llvm::createAArch64CleanupLocalDynamicTLSPass() { … }