lib/TableGen/Main.cpp

   1 //===- Main.cpp - Top-Level TableGen implementation -----------------------===//
   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 // TableGen is a tool which can be used to build up a description of something,
  10 // then invoke one or more "tablegen backends" to emit information about the
  11 // description in some predefined format.  In practice, this is used by the LLVM
  12 // code generators to automate generation of a code generator through a
  13 // high-level description of the target.
  14 //
  15 //===----------------------------------------------------------------------===//
  16
  17 #include "llvm/TableGen/Main.h"
  18 #include "TGParser.h"
  19 #include "llvm/ADT/StringExtras.h"
  20 #include "llvm/Support/CommandLine.h"
  21 #include "llvm/Support/FileSystem.h"
  22 #include "llvm/Support/MemoryBuffer.h"
  23 #include "llvm/Support/ToolOutputFile.h"
  24 #include "llvm/TableGen/Error.h"
  25 #include "llvm/TableGen/Record.h"
  26 #include <algorithm>
  27 #include <cstdio>
  28 #include <system_error>
  29 using namespace llvm;
  30
  31 static cl::opt<std::string>
  32 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
  33                cl::init("-"));
  34
  35 static cl::opt<std::string>
  36 DependFilename("d",
  37                cl::desc("Dependency filename"),
  38                cl::value_desc("filename"),
  39                cl::init(""));
  40
  41 static cl::opt<std::string>
  42 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
  43
  44 static cl::list<std::string>
  45 IncludeDirs("I", cl::desc("Directory of include files"),
  46             cl::value_desc("directory"), cl::Prefix);
  47
  48 static cl::list<std::string>
  49 MacroNames("D", cl::desc("Name of the macro to be defined"),
  50             cl::value_desc("macro name"), cl::Prefix);
  51
  52 static cl::opt<bool>
  53 WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed"));
  54
  55 static int reportError(const char *ProgName, Twine Msg) {
  56   errs() << ProgName << ": " << Msg;
  57   errs().flush();
  58   return 1;
  59 }
  60
  61 /// Create a dependency file for `-d` option.
  62 ///
  63 /// This functionality is really only for the benefit of the build system.
  64 /// It is similar to GCC's `-M*` family of options.
  65 static int createDependencyFile(const TGParser &Parser, const char *argv0) {
  66   if (OutputFilename == "-")
  67     return reportError(argv0, "the option -d must be used together with -o\n");
  68
  69   std::error_code EC;
  70   ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_None);
  71   if (EC)
  72     return reportError(argv0, "error opening " + DependFilename + ":" +
  73                                   EC.message() + "\n");
  74   DepOut.os() << OutputFilename << ":";
  75   for (const auto &Dep : Parser.getDependencies()) {
  76     DepOut.os() << ' ' << Dep.first;
  77   }
  78   DepOut.os() << "\n";
  79   DepOut.keep();
  80   return 0;
  81 }
  82
  83 int llvm::TableGenMain(char *argv0, TableGenMainFn *MainFn) {
  84   RecordKeeper Records;
  85
  86   // Parse the input file.
  87   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
  88       MemoryBuffer::getFileOrSTDIN(InputFilename);
  89   if (std::error_code EC = FileOrErr.getError())
  90     return reportError(argv0, "Could not open input file '" + InputFilename +
  91                                   "': " + EC.message() + "\n");
  92
  93   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
  94   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
  95
  96   // Record the location of the include directory so that the lexer can find
  97   // it later.
  98   SrcMgr.setIncludeDirs(IncludeDirs);
  99
 100   TGParser Parser(SrcMgr, MacroNames, Records);
 101
 102   if (Parser.ParseFile())
 103     return 1;
 104
 105   // Write output to memory.
 106   std::string OutString;
 107   raw_string_ostream Out(OutString);
 108   if (MainFn(Out, Records))
 109     return 1;
 110
 111   // Always write the depfile, even if the main output hasn't changed.
 112   // If it's missing, Ninja considers the output dirty.  If this was below
 113   // the early exit below and someone deleted the .inc.d file but not the .inc
 114   // file, tablegen would never write the depfile.
 115   if (!DependFilename.empty()) {
 116     if (int Ret = createDependencyFile(Parser, argv0))
 117       return Ret;
 118   }
 119
 120   if (WriteIfChanged) {
 121     // Only updates the real output file if there are any differences.
 122     // This prevents recompilation of all the files depending on it if there
 123     // aren't any.
 124     if (auto ExistingOrErr = MemoryBuffer::getFile(OutputFilename))
 125       if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
 126         return 0;
 127   }
 128
 129   std::error_code EC;
 130   ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_None);
 131   if (EC)
 132     return reportError(argv0, "error opening " + OutputFilename + ":" +
 133                                   EC.message() + "\n");
 134   OutFile.os() << Out.str();
 135
 136   if (ErrorsPrinted > 0)
 137     return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
 138
 139   // Declare success.
 140   OutFile.keep();
 141   return 0;
 142 }