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//===--- llvm-as.cpp - The low-level LLVM assembler -----------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
// This utility may be invoked in the following manner:
// llvm-as --help - Output information about command line switches
// llvm-as [options] - Read LLVM asm from stdin, write bitcode to stdout
// llvm-as [options] x.ll - Read LLVM asm from the x.ll file, write bitcode
// to the x.bc file.
#include "llvm/AsmParser/Parser.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/ModuleSummaryIndex.h"
#include "llvm/IR/Verifier.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/InitLLVM.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/ToolOutputFile.h"
#include <memory>
using namespace llvm;
cl::OptionCategory AsCat("llvm-as Options");
static cl::opt<std::string> InputFilename(cl::Positional,
cl::desc("<input .llvm file>"),
static cl::opt<std::string> OutputFilename("o",
cl::desc("Override output filename"),
static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"),
static cl::opt<bool> DisableOutput("disable-output", cl::desc("Disable output"),
cl::init(false), cl::cat(AsCat));
static cl::opt<bool> EmitModuleHash("module-hash", cl::desc("Emit module hash"),
cl::init(false), cl::cat(AsCat));
static cl::opt<bool> DumpAsm("d", cl::desc("Print assembly as parsed"),
cl::Hidden, cl::cat(AsCat));
static cl::opt<bool>
DisableVerify("disable-verify", cl::Hidden,
cl::desc("Do not run verifier on input LLVM (dangerous!)"),
static cl::opt<bool> PreserveBitcodeUseListOrder(
cl::desc("Preserve use-list order when writing LLVM bitcode."),
cl::init(true), cl::Hidden, cl::cat(AsCat));
static cl::opt<std::string> ClDataLayout("data-layout",
cl::desc("data layout string to use"),
cl::init(""), cl::cat(AsCat));
static void WriteOutputFile(const Module *M, const ModuleSummaryIndex *Index) {
// Infer the output filename if needed.
if (OutputFilename.empty()) {
if (InputFilename == "-") {
OutputFilename = "-";
} else {
StringRef IFN = InputFilename;
OutputFilename = (IFN.endswith(".ll") ? IFN.drop_back(3) : IFN).str();
OutputFilename += ".bc";
std::error_code EC;
std::unique_ptr<ToolOutputFile> Out(
new ToolOutputFile(OutputFilename, EC, sys::fs::OF_None));
if (EC) {
errs() << EC.message() << '\n';
if (Force || !CheckBitcodeOutputToConsole(Out->os())) {
const ModuleSummaryIndex *IndexToWrite = nullptr;
// Don't attempt to write a summary index unless it contains any entries or
// has non-zero flags. The latter is used to assemble dummy index files for
// skipping modules by distributed ThinLTO backends. Otherwise we get an empty
// summary section.
if (Index && (Index->begin() != Index->end() || Index->getFlags()))
IndexToWrite = Index;
if (!IndexToWrite || (M && (!M->empty() || !M->global_empty())))
// If we have a non-empty Module, then we write the Module plus
// any non-null Index along with it as a per-module Index.
// If both are empty, this will give an empty module block, which is
// the expected behavior.
WriteBitcodeToFile(*M, Out->os(), PreserveBitcodeUseListOrder,
IndexToWrite, EmitModuleHash);
// Otherwise, with an empty Module but non-empty Index, we write a
// combined index.
WriteIndexToFile(*IndexToWrite, Out->os());
// Declare success.
int main(int argc, char **argv) {
InitLLVM X(argc, argv);
cl::ParseCommandLineOptions(argc, argv, "llvm .ll -> .bc assembler\n");
LLVMContext Context;
// Parse the file now...
SMDiagnostic Err;
auto SetDataLayout = [](StringRef) -> Optional<std::string> {
if (ClDataLayout.empty())
return None;
return ClDataLayout;
ParsedModuleAndIndex ModuleAndIndex;
if (DisableVerify) {
ModuleAndIndex = parseAssemblyFileWithIndexNoUpgradeDebugInfo(
InputFilename, Err, Context, nullptr, SetDataLayout);
} else {
ModuleAndIndex = parseAssemblyFileWithIndex(InputFilename, Err, Context,
nullptr, SetDataLayout);
std::unique_ptr<Module> M = std::move(ModuleAndIndex.Mod);
if (!M.get()) {
Err.print(argv[0], errs());
return 1;
std::unique_ptr<ModuleSummaryIndex> Index = std::move(ModuleAndIndex.Index);
if (!DisableVerify) {
std::string ErrorStr;
raw_string_ostream OS(ErrorStr);
if (verifyModule(*M.get(), &OS)) {
errs() << argv[0]
<< ": assembly parsed, but does not verify as correct!\n";
errs() << OS.str();
return 1;
// TODO: Implement and call summary index verifier.
if (DumpAsm) {
errs() << "Here's the assembly:\n" << *M.get();
if (Index.get() && Index->begin() != Index->end())
if (!DisableOutput)
WriteOutputFile(M.get(), Index.get());
return 0;