llvm/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 cl::opt<bool>
  56 TimePhases("time-phases", cl::desc("Time phases of parser and backend"));
  57
  58 static int reportError(const char *ProgName, Twine Msg) {
  59   errs() << ProgName << ": " << Msg;
  60   errs().flush();
  61   return 1;
  62 }
  63
  64 /// Create a dependency file for `-d` option.
  65 ///
  66 /// This functionality is really only for the benefit of the build system.
  67 /// It is similar to GCC's `-M*` family of options.
  68 static int createDependencyFile(const TGParser &Parser, const char *argv0) {
  69   if (OutputFilename == "-")
  70     return reportError(argv0, "the option -d must be used together with -o\n");
  71
  72   std::error_code EC;
  73   ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text);
  74   if (EC)
  75     return reportError(argv0, "error opening " + DependFilename + ":" +
  76                                   EC.message() + "\n");
  77   DepOut.os() << OutputFilename << ":";
  78   for (const auto &Dep : Parser.getDependencies()) {
  79     DepOut.os() << ' ' << Dep;
  80   }
  81   DepOut.os() << "\n";
  82   DepOut.keep();
  83   return 0;
  84 }
  85
  86 int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) {
  87   RecordKeeper Records;
  88
  89   if (TimePhases)
  90     Records.startPhaseTiming();
  91
  92   // Parse the input file.
  93
  94   Records.startTimer("Parse, build records");
  95   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
  96       MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
  97   if (std::error_code EC = FileOrErr.getError())
  98     return reportError(argv0, "Could not open input file '" + InputFilename +
  99                                   "': " + EC.message() + "\n");
 100
 101   Records.saveInputFilename(InputFilename);
 102
 103   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
 104   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
 105
 106   // Record the location of the include directory so that the lexer can find
 107   // it later.
 108   SrcMgr.setIncludeDirs(IncludeDirs);
 109
 110   TGParser Parser(SrcMgr, MacroNames, Records);
 111
 112   if (Parser.ParseFile())
 113     return 1;
 114   Records.stopTimer();
 115
 116   // Write output to memory.
 117   Records.startBackendTimer("Backend overall");
 118   std::string OutString;
 119   raw_string_ostream Out(OutString);
 120   unsigned status = MainFn(Out, Records);
 121   Records.stopBackendTimer();
 122   if (status)
 123     return 1;
 124
 125   // Always write the depfile, even if the main output hasn't changed.
 126   // If it's missing, Ninja considers the output dirty.  If this was below
 127   // the early exit below and someone deleted the .inc.d file but not the .inc
 128   // file, tablegen would never write the depfile.
 129   if (!DependFilename.empty()) {
 130     if (int Ret = createDependencyFile(Parser, argv0))
 131       return Ret;
 132   }
 133
 134   Records.startTimer("Write output");
 135   bool WriteFile = true;
 136   if (WriteIfChanged) {
 137     // Only updates the real output file if there are any differences.
 138     // This prevents recompilation of all the files depending on it if there
 139     // aren't any.
 140     if (auto ExistingOrErr =
 141             MemoryBuffer::getFile(OutputFilename, /*IsText=*/true))
 142       if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
 143         WriteFile = false;
 144   }
 145   if (WriteFile) {
 146     std::error_code EC;
 147     ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text);
 148     if (EC)
 149       return reportError(argv0, "error opening " + OutputFilename + ": " +
 150                                     EC.message() + "\n");
 151     OutFile.os() << Out.str();
 152     if (ErrorsPrinted == 0)
 153       OutFile.keep();
 154   }
 155
 156   Records.stopTimer();
 157   Records.stopPhaseTiming();
 158
 159   if (ErrorsPrinted > 0)
 160     return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
 161   return 0;
 162 }