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      1 //===--- llvm-as.cpp - The low-level LLVM assembler -----------------------===//
      2 //
      3 //                     The LLVM Compiler Infrastructure
      4 //
      5 // This file is distributed under the University of Illinois Open Source
      6 // License. See LICENSE.TXT for details.
      7 //
      8 //===----------------------------------------------------------------------===//
      9 //
     10 //  This utility may be invoked in the following manner:
     11 //   llvm-as --help         - Output information about command line switches
     12 //   llvm-as [options]      - Read LLVM asm from stdin, write bitcode to stdout
     13 //   llvm-as [options] x.ll - Read LLVM asm from the x.ll file, write bitcode
     14 //                            to the x.bc file.
     15 //
     16 //===----------------------------------------------------------------------===//
     17 
     18 #include "llvm/IR/LLVMContext.h"
     19 #include "llvm/AsmParser/Parser.h"
     20 #include "llvm/Bitcode/ReaderWriter.h"
     21 #include "llvm/IR/Module.h"
     22 #include "llvm/IR/Verifier.h"
     23 #include "llvm/Support/CommandLine.h"
     24 #include "llvm/Support/FileSystem.h"
     25 #include "llvm/Support/ManagedStatic.h"
     26 #include "llvm/Support/PrettyStackTrace.h"
     27 #include "llvm/Support/Signals.h"
     28 #include "llvm/Support/SourceMgr.h"
     29 #include "llvm/Support/SystemUtils.h"
     30 #include "llvm/Support/ToolOutputFile.h"
     31 #include <memory>
     32 using namespace llvm;
     33 
     34 static cl::opt<std::string>
     35 InputFilename(cl::Positional, cl::desc("<input .llvm file>"), cl::init("-"));
     36 
     37 static cl::opt<std::string>
     38 OutputFilename("o", cl::desc("Override output filename"),
     39                cl::value_desc("filename"));
     40 
     41 static cl::opt<bool>
     42 Force("f", cl::desc("Enable binary output on terminals"));
     43 
     44 static cl::opt<bool>
     45 DisableOutput("disable-output", cl::desc("Disable output"), cl::init(false));
     46 
     47 static cl::opt<bool>
     48 EmitFunctionSummary("function-summary", cl::desc("Emit function summary index"),
     49                     cl::init(false));
     50 
     51 static cl::opt<bool>
     52 DumpAsm("d", cl::desc("Print assembly as parsed"), cl::Hidden);
     53 
     54 static cl::opt<bool>
     55 DisableVerify("disable-verify", cl::Hidden,
     56               cl::desc("Do not run verifier on input LLVM (dangerous!)"));
     57 
     58 static cl::opt<bool> PreserveBitcodeUseListOrder(
     59     "preserve-bc-uselistorder",
     60     cl::desc("Preserve use-list order when writing LLVM bitcode."),
     61     cl::init(true), cl::Hidden);
     62 
     63 static void WriteOutputFile(const Module *M) {
     64   // Infer the output filename if needed.
     65   if (OutputFilename.empty()) {
     66     if (InputFilename == "-") {
     67       OutputFilename = "-";
     68     } else {
     69       StringRef IFN = InputFilename;
     70       OutputFilename = (IFN.endswith(".ll") ? IFN.drop_back(3) : IFN).str();
     71       OutputFilename += ".bc";
     72     }
     73   }
     74 
     75   std::error_code EC;
     76   std::unique_ptr<tool_output_file> Out(
     77       new tool_output_file(OutputFilename, EC, sys::fs::F_None));
     78   if (EC) {
     79     errs() << EC.message() << '\n';
     80     exit(1);
     81   }
     82 
     83   if (Force || !CheckBitcodeOutputToConsole(Out->os(), true))
     84     WriteBitcodeToFile(M, Out->os(), PreserveBitcodeUseListOrder,
     85                        EmitFunctionSummary);
     86 
     87   // Declare success.
     88   Out->keep();
     89 }
     90 
     91 int main(int argc, char **argv) {
     92   // Print a stack trace if we signal out.
     93   sys::PrintStackTraceOnErrorSignal();
     94   PrettyStackTraceProgram X(argc, argv);
     95   LLVMContext &Context = getGlobalContext();
     96   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
     97   cl::ParseCommandLineOptions(argc, argv, "llvm .ll -> .bc assembler\n");
     98 
     99   // Parse the file now...
    100   SMDiagnostic Err;
    101   std::unique_ptr<Module> M = parseAssemblyFile(InputFilename, Err, Context);
    102   if (!M.get()) {
    103     Err.print(argv[0], errs());
    104     return 1;
    105   }
    106 
    107   if (!DisableVerify) {
    108     std::string ErrorStr;
    109     raw_string_ostream OS(ErrorStr);
    110     if (verifyModule(*M.get(), &OS)) {
    111       errs() << argv[0]
    112              << ": assembly parsed, but does not verify as correct!\n";
    113       errs() << OS.str();
    114       return 1;
    115     }
    116   }
    117 
    118   if (DumpAsm) errs() << "Here's the assembly:\n" << *M.get();
    119 
    120   if (!DisableOutput)
    121     WriteOutputFile(M.get());
    122 
    123   return 0;
    124 }
    125