llvm/llvm/lib/Target/NVPTX/NVPTXCtorDtorLowering.cpp

//===-- NVPTXCtorDtorLowering.cpp - Handle global ctors and dtors --------===//
//
// 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 pass creates a unified init and fini kernel with the required metadata
//===----------------------------------------------------------------------===//

#include "NVPTXCtorDtorLowering.h"
#include "MCTargetDesc/NVPTXBaseInfo.h"
#include "NVPTX.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalVariable.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Value.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MD5.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"

usingnamespacellvm;

#define DEBUG_TYPE …

static cl::opt<std::string>
    GlobalStr("nvptx-lower-global-ctor-dtor-id",
              cl::desc("Override unique ID of ctor/dtor globals."),
              cl::init(""), cl::Hidden);

static cl::opt<bool>
    CreateKernels("nvptx-emit-init-fini-kernel",
                  cl::desc("Emit kernels to call ctor/dtor globals."),
                  cl::init(true), cl::Hidden);

namespace {

static std::string getHash(StringRef Str) { … }

static void addKernelMetadata(Module &M, GlobalValue *GV) { … }

static Function *createInitOrFiniKernelFunction(Module &M, bool IsCtor) { … }

// We create the IR required to call each callback in this section. This is
// equivalent to the following code. Normally, the linker would provide us with
// the definitions of the init and fini array sections. The 'nvlink' linker does
// not do this so initializing these values is done by the runtime.
//
// extern "C" void **__init_array_start = nullptr;
// extern "C" void **__init_array_end = nullptr;
// extern "C" void **__fini_array_start = nullptr;
// extern "C" void **__fini_array_end = nullptr;
//
// using InitCallback = void();
// using FiniCallback = void();
//
// void call_init_array_callbacks() {
//   for (auto start = __init_array_start; start != __init_array_end; ++start)
//     reinterpret_cast<InitCallback *>(*start)();
// }
//
// void call_init_array_callbacks() {
//   size_t fini_array_size = __fini_array_end - __fini_array_start;
//   for (size_t i = fini_array_size; i > 0; --i)
//     reinterpret_cast<FiniCallback *>(__fini_array_start[i - 1])();
// }
static void createInitOrFiniCalls(Function &F, bool IsCtor) { … }

static bool createInitOrFiniGlobals(Module &M, GlobalVariable *GV,
                                    bool IsCtor) { … }

static bool createInitOrFiniKernel(Module &M, StringRef GlobalName,
                                   bool IsCtor) { … }

static bool lowerCtorsAndDtors(Module &M) { … }

class NVPTXCtorDtorLoweringLegacy final : public ModulePass { … };

} // End anonymous namespace

PreservedAnalyses NVPTXCtorDtorLoweringPass::run(Module &M,
                                                 ModuleAnalysisManager &AM) { … }

char NVPTXCtorDtorLoweringLegacy::ID = …;
char &llvm::NVPTXCtorDtorLoweringLegacyPassID = …;
INITIALIZE_PASS(…)

ModulePass *llvm::createNVPTXCtorDtorLoweringLegacyPass() { … }