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 cl::opt<bool> NoWarnOnUnusedTemplateArgs(
  59     "no-warn-on-unused-template-args",
  60     cl::desc("Disable unused template argument warnings."));
  61
  62 static int reportError(const char *ProgName, Twine Msg) {
  63   errs() << ProgName << ": " << Msg;
  64   errs().flush();
  65   return 1;
  66 }
  67
  68 /// Create a dependency file for `-d` option.
  69 ///
  70 /// This functionality is really only for the benefit of the build system.
  71 /// It is similar to GCC's `-M*` family of options.
  72 static int createDependencyFile(const TGParser &Parser, const char *argv0) {
  73   if (OutputFilename == "-")
  74     return reportError(argv0, "the option -d must be used together with -o\n");
  75
  76   std::error_code EC;
  77   ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text);
  78   if (EC)
  79     return reportError(argv0, "error opening " + DependFilename + ":" +
  80                                   EC.message() + "\n");
  81   DepOut.os() << OutputFilename << ":";
  82   for (const auto &Dep : Parser.getDependencies()) {
  83     DepOut.os() << ' ' << Dep;
  84   }
  85   DepOut.os() << "\n";
  86   DepOut.keep();
  87   return 0;
  88 }
  89
  90 int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) {
  91   RecordKeeper Records;
  92
  93   if (TimePhases)
  94     Records.startPhaseTiming();
  95
  96   // Parse the input file.
  97
  98   Records.startTimer("Parse, build records");
  99   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
 100       MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
 101   if (std::error_code EC = FileOrErr.getError())
 102     return reportError(argv0, "Could not open input file '" + InputFilename +
 103                                   "': " + EC.message() + "\n");
 104
 105   Records.saveInputFilename(InputFilename);
 106
 107   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
 108   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
 109
 110   // Record the location of the include directory so that the lexer can find
 111   // it later.
 112   SrcMgr.setIncludeDirs(IncludeDirs);
 113
 114   TGParser Parser(SrcMgr, MacroNames, Records, NoWarnOnUnusedTemplateArgs);
 115
 116   if (Parser.ParseFile())
 117     return 1;
 118   Records.stopTimer();
 119
 120   // Write output to memory.
 121   Records.startBackendTimer("Backend overall");
 122   std::string OutString;
 123   raw_string_ostream Out(OutString);
 124   unsigned status = MainFn(Out, Records);
 125   Records.stopBackendTimer();
 126   if (status)
 127     return 1;
 128
 129   // Always write the depfile, even if the main output hasn't changed.
 130   // If it's missing, Ninja considers the output dirty.  If this was below
 131   // the early exit below and someone deleted the .inc.d file but not the .inc
 132   // file, tablegen would never write the depfile.
 133   if (!DependFilename.empty()) {
 134     if (int Ret = createDependencyFile(Parser, argv0))
 135       return Ret;
 136   }
 137
 138   Records.startTimer("Write output");
 139   bool WriteFile = true;
 140   if (WriteIfChanged) {
 141     // Only updates the real output file if there are any differences.
 142     // This prevents recompilation of all the files depending on it if there
 143     // aren't any.
 144     if (auto ExistingOrErr =
 145             MemoryBuffer::getFile(OutputFilename, /*IsText=*/true))
 146       if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
 147         WriteFile = false;
 148   }
 149   if (WriteFile) {
 150     std::error_code EC;
 151     ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text);
 152     if (EC)
 153       return reportError(argv0, "error opening " + OutputFilename + ": " +
 154                                     EC.message() + "\n");
 155     OutFile.os() << Out.str();
 156     if (ErrorsPrinted == 0)
 157       OutFile.keep();
 158   }
 159
 160   Records.stopTimer();
 161   Records.stopPhaseTiming();
 162
 163   if (ErrorsPrinted > 0)
 164     return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
 165   return 0;
 166 }