llvm/tools/llvm-as/llvm-as.cpp

   1 //===--- llvm-as.cpp - The low-level LLVM assembler -----------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 //  This utility may be invoked in the following manner:
  10 //   llvm-as --help         - Output information about command line switches
  11 //   llvm-as [options]      - Read LLVM asm from stdin, write bitcode to stdout
  12 //   llvm-as [options] x.ll - Read LLVM asm from the x.ll file, write bitcode
  13 //                            to the x.bc file.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/AsmParser/Parser.h"
  18 #include "llvm/Bitcode/BitcodeWriter.h"
  19 #include "llvm/IR/LLVMContext.h"
  20 #include "llvm/IR/Module.h"
  21 #include "llvm/IR/ModuleSummaryIndex.h"
  22 #include "llvm/IR/Verifier.h"
  23 #include "llvm/Support/CommandLine.h"
  24 #include "llvm/Support/FileSystem.h"
  25 #include "llvm/Support/InitLLVM.h"
  26 #include "llvm/Support/SourceMgr.h"
  27 #include "llvm/Support/SystemUtils.h"
  28 #include "llvm/Support/ToolOutputFile.h"
  29 #include <memory>
  30 #include <optional>
  31 using namespace llvm;
  32
  33 cl::OptionCategory AsCat("llvm-as Options");
  34
  35 static cl::opt<std::string> InputFilename(cl::Positional,
  36                                           cl::desc("<input .llvm file>"),
  37                                           cl::init("-"));
  38
  39 static cl::opt<std::string> OutputFilename("o",
  40                                            cl::desc("Override output filename"),
  41                                            cl::value_desc("filename"),
  42                                            cl::cat(AsCat));
  43
  44 static cl::opt<bool> Force("f", cl::desc("Enable binary output on terminals"),
  45                            cl::cat(AsCat));
  46
  47 static cl::opt<bool> DisableOutput("disable-output", cl::desc("Disable output"),
  48                                    cl::init(false), cl::cat(AsCat));
  49
  50 static cl::opt<bool> EmitModuleHash("module-hash", cl::desc("Emit module hash"),
  51                                     cl::init(false), cl::cat(AsCat));
  52
  53 static cl::opt<bool> DumpAsm("d", cl::desc("Print assembly as parsed"),
  54                              cl::Hidden, cl::cat(AsCat));
  55
  56 static cl::opt<bool>
  57     DisableVerify("disable-verify", cl::Hidden,
  58                   cl::desc("Do not run verifier on input LLVM (dangerous!)"),
  59                   cl::cat(AsCat));
  60
  61 static cl::opt<bool> PreserveBitcodeUseListOrder(
  62     "preserve-bc-uselistorder",
  63     cl::desc("Preserve use-list order when writing LLVM bitcode."),
  64     cl::init(true), cl::Hidden, cl::cat(AsCat));
  65
  66 static cl::opt<std::string> ClDataLayout("data-layout",
  67                                          cl::desc("data layout string to use"),
  68                                          cl::value_desc("layout-string"),
  69                                          cl::init(""), cl::cat(AsCat));
  70
  71 static void WriteOutputFile(const Module *M, const ModuleSummaryIndex *Index) {
  72   // Infer the output filename if needed.
  73   if (OutputFilename.empty()) {
  74     if (InputFilename == "-") {
  75       OutputFilename = "-";
  76     } else {
  77       StringRef IFN = InputFilename;
  78       OutputFilename = (IFN.endswith(".ll") ? IFN.drop_back(3) : IFN).str();
  79       OutputFilename += ".bc";
  80     }
  81   }
  82
  83   std::error_code EC;
  84   std::unique_ptr<ToolOutputFile> Out(
  85       new ToolOutputFile(OutputFilename, EC, sys::fs::OF_None));
  86   if (EC) {
  87     errs() << EC.message() << '\n';
  88     exit(1);
  89   }
  90
  91   if (Force || !CheckBitcodeOutputToConsole(Out->os())) {
  92     const ModuleSummaryIndex *IndexToWrite = nullptr;
  93     // Don't attempt to write a summary index unless it contains any entries or
  94     // has non-zero flags. The latter is used to assemble dummy index files for
  95     // skipping modules by distributed ThinLTO backends. Otherwise we get an empty
  96     // summary section.
  97     if (Index && (Index->begin() != Index->end() || Index->getFlags()))
  98       IndexToWrite = Index;
  99     if (!IndexToWrite || (M && (!M->empty() || !M->global_empty())))
 100       // If we have a non-empty Module, then we write the Module plus
 101       // any non-null Index along with it as a per-module Index.
 102       // If both are empty, this will give an empty module block, which is
 103       // the expected behavior.
 104       WriteBitcodeToFile(*M, Out->os(), PreserveBitcodeUseListOrder,
 105                          IndexToWrite, EmitModuleHash);
 106     else
 107       // Otherwise, with an empty Module but non-empty Index, we write a
 108       // combined index.
 109       writeIndexToFile(*IndexToWrite, Out->os());
 110   }
 111
 112   // Declare success.
 113   Out->keep();
 114 }
 115
 116 int main(int argc, char **argv) {
 117   InitLLVM X(argc, argv);
 118   cl::HideUnrelatedOptions(AsCat);
 119   cl::ParseCommandLineOptions(argc, argv, "llvm .ll -> .bc assembler\n");
 120   LLVMContext Context;
 121
 122   // Parse the file now...
 123   SMDiagnostic Err;
 124   auto SetDataLayout = [](StringRef, StringRef) -> std::optional<std::string> {
 125     if (ClDataLayout.empty())
 126       return std::nullopt;
 127     return ClDataLayout;
 128   };
 129   ParsedModuleAndIndex ModuleAndIndex;
 130   if (DisableVerify) {
 131     ModuleAndIndex = parseAssemblyFileWithIndexNoUpgradeDebugInfo(
 132         InputFilename, Err, Context, nullptr, SetDataLayout);
 133   } else {
 134     ModuleAndIndex = parseAssemblyFileWithIndex(InputFilename, Err, Context,
 135                                                 nullptr, SetDataLayout);
 136   }
 137   std::unique_ptr<Module> M = std::move(ModuleAndIndex.Mod);
 138   if (!M.get()) {
 139     Err.print(argv[0], errs());
 140     return 1;
 141   }
 142   std::unique_ptr<ModuleSummaryIndex> Index = std::move(ModuleAndIndex.Index);
 143
 144   if (!DisableVerify) {
 145     std::string ErrorStr;
 146     raw_string_ostream OS(ErrorStr);
 147     if (verifyModule(*M.get(), &OS)) {
 148       errs() << argv[0]
 149              << ": assembly parsed, but does not verify as correct!\n";
 150       errs() << OS.str();
 151       return 1;
 152     }
 153     // TODO: Implement and call summary index verifier.
 154   }
 155
 156   if (DumpAsm) {
 157     errs() << "Here's the assembly:\n" << *M.get();
 158     if (Index.get() && Index->begin() != Index->end())
 159       Index->print(errs());
 160   }
 161
 162   if (!DisableOutput)
 163     WriteOutputFile(M.get(), Index.get());
 164
 165   return 0;
 166 }