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/TableGenBackend.h"
  33 #include <memory>
  34 #include <string>
  35 #include <system_error>
  36 #include <utility>
  37 #include <vector>
  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
 103   if (TimePhases)
 104     Records.startPhaseTiming();
 105
 106   // Parse the input file.
 107
 108   Records.startTimer("Parse, build records");
 109   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
 110       MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
 111   if (std::error_code EC = FileOrErr.getError())
 112     return reportError(argv0, "Could not open input file '" + InputFilename +
 113                                   "': " + EC.message() + "\n");
 114
 115   Records.saveInputFilename(InputFilename);
 116
 117   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
 118   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
 119
 120   // Record the location of the include directory so that the lexer can find
 121   // it later.
 122   SrcMgr.setIncludeDirs(IncludeDirs);
 123
 124   TGParser Parser(SrcMgr, MacroNames, Records, NoWarnOnUnusedTemplateArgs);
 125
 126   if (Parser.ParseFile())
 127     return 1;
 128   Records.stopTimer();
 129
 130   // Write output to memory.
 131   Records.startBackendTimer("Backend overall");
 132   std::string OutString;
 133   raw_string_ostream Out(OutString);
 134   unsigned status = 0;
 135   TableGen::Emitter::FnT ActionFn = TableGen::Emitter::Action->getValue();
 136   if (ActionFn)
 137     ActionFn(Records, Out);
 138   else if (MainFn)
 139     status = MainFn(Out, Records);
 140   else
 141     return 1;
 142   Records.stopBackendTimer();
 143   if (status)
 144     return 1;
 145
 146   // Always write the depfile, even if the main output hasn't changed.
 147   // If it's missing, Ninja considers the output dirty.  If this was below
 148   // the early exit below and someone deleted the .inc.d file but not the .inc
 149   // file, tablegen would never write the depfile.
 150   if (!DependFilename.empty()) {
 151     if (int Ret = createDependencyFile(Parser, argv0))
 152       return Ret;
 153   }
 154
 155   Records.startTimer("Write output");
 156   bool WriteFile = true;
 157   if (WriteIfChanged) {
 158     // Only updates the real output file if there are any differences.
 159     // This prevents recompilation of all the files depending on it if there
 160     // aren't any.
 161     if (auto ExistingOrErr =
 162             MemoryBuffer::getFile(OutputFilename, /*IsText=*/true))
 163       if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
 164         WriteFile = false;
 165   }
 166   if (WriteFile) {
 167     std::error_code EC;
 168     ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text);
 169     if (EC)
 170       return reportError(argv0, "error opening " + OutputFilename + ": " +
 171                                     EC.message() + "\n");
 172     OutFile.os() << Out.str();
 173     if (ErrorsPrinted == 0)
 174       OutFile.keep();
 175   }
 176
 177   Records.stopTimer();
 178   Records.stopPhaseTiming();
 179
 180   if (ErrorsPrinted > 0)
 181     return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
 182   return 0;
 183 }