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 "TGLexer.h"
  19 #include "TGParser.h"
  20 #include "llvm/ADT/StringRef.h"
  21 #include "llvm/ADT/Twine.h"
  22 #include "llvm/Support/CommandLine.h"
  23 #include "llvm/Support/ErrorOr.h"
  24 #include "llvm/Support/FileSystem.h"
  25 #include "llvm/Support/MemoryBuffer.h"
  26 #include "llvm/Support/SMLoc.h"
  27 #include "llvm/Support/SourceMgr.h"
  28 #include "llvm/Support/ToolOutputFile.h"
  29 #include "llvm/Support/raw_ostream.h"
  30 #include "llvm/TableGen/Error.h"
  31 #include "llvm/TableGen/Record.h"
  32 #include "llvm/TableGen/TGTimer.h"
  33 #include "llvm/TableGen/TableGenBackend.h"
  34 #include <memory>
  35 #include <string>
  36 #include <system_error>
  37 #include <utility>
  38 using namespace llvm;
  39
  40 static cl::opt<std::string>
  41 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
  42                cl::init("-"));
  43
  44 static cl::opt<std::string>
  45 DependFilename("d",
  46                cl::desc("Dependency filename"),
  47                cl::value_desc("filename"),
  48                cl::init(""));
  49
  50 static cl::opt<std::string>
  51 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
  52
  53 static cl::list<std::string>
  54 IncludeDirs("I", cl::desc("Directory of include files"),
  55             cl::value_desc("directory"), cl::Prefix);
  56
  57 static cl::list<std::string>
  58 MacroNames("D", cl::desc("Name of the macro to be defined"),
  59             cl::value_desc("macro name"), cl::Prefix);
  60
  61 static cl::opt<bool>
  62 WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed"));
  63
  64 static cl::opt<bool>
  65 TimePhases("time-phases", cl::desc("Time phases of parser and backend"));
  66
  67 static cl::opt<bool> NoWarnOnUnusedTemplateArgs(
  68     "no-warn-on-unused-template-args",
  69     cl::desc("Disable unused template argument warnings."));
  70
  71 static int reportError(const char *ProgName, Twine Msg) {
  72   errs() << ProgName << ": " << Msg;
  73   errs().flush();
  74   return 1;
  75 }
  76
  77 /// Create a dependency file for `-d` option.
  78 ///
  79 /// This functionality is really only for the benefit of the build system.
  80 /// It is similar to GCC's `-M*` family of options.
  81 static int createDependencyFile(const TGParser &Parser, const char *argv0) {
  82   if (OutputFilename == "-")
  83     return reportError(argv0, "the option -d must be used together with -o\n");
  84
  85   std::error_code EC;
  86   ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text);
  87   if (EC)
  88     return reportError(argv0, "error opening " + DependFilename + ":" +
  89                                   EC.message() + "\n");
  90   DepOut.os() << OutputFilename << ":";
  91   for (const auto &Dep : Parser.getDependencies()) {
  92     DepOut.os() << ' ' << Dep;
  93   }
  94   DepOut.os() << "\n";
  95   DepOut.keep();
  96   return 0;
  97 }
  98
  99 int llvm::TableGenMain(const char *argv0,
 100                        std::function<TableGenMainFn> MainFn) {
 101   RecordKeeper Records;
 102   TGTimer &Timer = Records.getTimer();
 103
 104   if (TimePhases)
 105     Timer.startPhaseTiming();
 106
 107   // Parse the input file.
 108
 109   Timer.startTimer("Parse, build records");
 110   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
 111       MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
 112   if (std::error_code EC = FileOrErr.getError())
 113     return reportError(argv0, "Could not open input file '" + InputFilename +
 114                                   "': " + EC.message() + "\n");
 115
 116   Records.saveInputFilename(InputFilename);
 117
 118   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
 119   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
 120
 121   // Record the location of the include directory so that the lexer can find
 122   // it later.
 123   SrcMgr.setIncludeDirs(IncludeDirs);
 124
 125   TGParser Parser(SrcMgr, MacroNames, Records, NoWarnOnUnusedTemplateArgs);
 126
 127   if (Parser.ParseFile())
 128     return 1;
 129   Timer.stopTimer();
 130
 131   // Write output to memory.
 132   Timer.startBackendTimer("Backend overall");
 133   std::string OutString;
 134   raw_string_ostream Out(OutString);
 135   unsigned status = 0;
 136   // ApplyCallback will return true if it did not apply any callback. In that
 137   // case, attempt to apply the MainFn.
 138   if (TableGen::Emitter::ApplyCallback(Records, Out))
 139     status = MainFn ? MainFn(Out, Records) : 1;
 140   Timer.stopBackendTimer();
 141   if (status)
 142     return 1;
 143
 144   // Always write the depfile, even if the main output hasn't changed.
 145   // If it's missing, Ninja considers the output dirty.  If this was below
 146   // the early exit below and someone deleted the .inc.d file but not the .inc
 147   // file, tablegen would never write the depfile.
 148   if (!DependFilename.empty()) {
 149     if (int Ret = createDependencyFile(Parser, argv0))
 150       return Ret;
 151   }
 152
 153   Timer.startTimer("Write output");
 154   bool WriteFile = true;
 155   if (WriteIfChanged) {
 156     // Only updates the real output file if there are any differences.
 157     // This prevents recompilation of all the files depending on it if there
 158     // aren't any.
 159     if (auto ExistingOrErr =
 160             MemoryBuffer::getFile(OutputFilename, /*IsText=*/true))
 161       if (std::move(ExistingOrErr.get())->getBuffer() == OutString)
 162         WriteFile = false;
 163   }
 164   if (WriteFile) {
 165     std::error_code EC;
 166     ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text);
 167     if (EC)
 168       return reportError(argv0, "error opening " + OutputFilename + ": " +
 169                                     EC.message() + "\n");
 170     OutFile.os() << OutString;
 171     if (ErrorsPrinted == 0)
 172       OutFile.keep();
 173   }
 174
 175   Timer.stopTimer();
 176   Timer.stopPhaseTiming();
 177
 178   if (ErrorsPrinted > 0)
 179     return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
 180   return 0;
 181 }