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 using namespace llvm;
  38
  39 static cl::opt<std::string>
  40 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
  41                cl::init("-"));
  42
  43 static cl::opt<std::string>
  44 DependFilename("d",
  45                cl::desc("Dependency filename"),
  46                cl::value_desc("filename"),
  47                cl::init(""));
  48
  49 static cl::opt<std::string>
  50 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
  51
  52 static cl::list<std::string>
  53 IncludeDirs("I", cl::desc("Directory of include files"),
  54             cl::value_desc("directory"), cl::Prefix);
  55
  56 static cl::list<std::string>
  57 MacroNames("D", cl::desc("Name of the macro to be defined"),
  58             cl::value_desc("macro name"), cl::Prefix);
  59
  60 static cl::opt<bool>
  61 WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed"));
  62
  63 static cl::opt<bool>
  64 TimePhases("time-phases", cl::desc("Time phases of parser and backend"));
  65
  66 static cl::opt<bool> NoWarnOnUnusedTemplateArgs(
  67     "no-warn-on-unused-template-args",
  68     cl::desc("Disable unused template argument warnings."));
  69
  70 static int reportError(const char *ProgName, Twine Msg) {
  71   errs() << ProgName << ": " << Msg;
  72   errs().flush();
  73   return 1;
  74 }
  75
  76 /// Create a dependency file for `-d` option.
  77 ///
  78 /// This functionality is really only for the benefit of the build system.
  79 /// It is similar to GCC's `-M*` family of options.
  80 static int createDependencyFile(const TGParser &Parser, const char *argv0) {
  81   if (OutputFilename == "-")
  82     return reportError(argv0, "the option -d must be used together with -o\n");
  83
  84   std::error_code EC;
  85   ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text);
  86   if (EC)
  87     return reportError(argv0, "error opening " + DependFilename + ":" +
  88                                   EC.message() + "\n");
  89   DepOut.os() << OutputFilename << ":";
  90   for (const auto &Dep : Parser.getDependencies()) {
  91     DepOut.os() << ' ' << Dep;
  92   }
  93   DepOut.os() << "\n";
  94   DepOut.keep();
  95   return 0;
  96 }
  97
  98 int llvm::TableGenMain(const char *argv0,
  99                        std::function<TableGenMainFn> MainFn) {
 100   RecordKeeper Records;
 101
 102   if (TimePhases)
 103     Records.startPhaseTiming();
 104
 105   // Parse the input file.
 106
 107   Records.startTimer("Parse, build records");
 108   ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
 109       MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
 110   if (std::error_code EC = FileOrErr.getError())
 111     return reportError(argv0, "Could not open input file '" + InputFilename +
 112                                   "': " + EC.message() + "\n");
 113
 114   Records.saveInputFilename(InputFilename);
 115
 116   // Tell SrcMgr about this buffer, which is what TGParser will pick up.
 117   SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
 118
 119   // Record the location of the include directory so that the lexer can find
 120   // it later.
 121   SrcMgr.setIncludeDirs(IncludeDirs);
 122
 123   TGParser Parser(SrcMgr, MacroNames, Records, NoWarnOnUnusedTemplateArgs);
 124
 125   if (Parser.ParseFile())
 126     return 1;
 127   Records.stopTimer();
 128
 129   // Write output to memory.
 130   Records.startBackendTimer("Backend overall");
 131   std::string OutString;
 132   raw_string_ostream Out(OutString);
 133   unsigned status = 0;
 134   TableGen::Emitter::FnT ActionFn = TableGen::Emitter::Action->getValue();
 135   if (ActionFn)
 136     ActionFn(Records, Out);
 137   else if (MainFn)
 138     status = MainFn(Out, Records);
 139   else
 140     return 1;
 141   Records.stopBackendTimer();
 142   if (status)
 143     return 1;
 144
 145   // Always write the depfile, even if the main output hasn't changed.
 146   // If it's missing, Ninja considers the output dirty.  If this was below
 147   // the early exit below and someone deleted the .inc.d file but not the .inc
 148   // file, tablegen would never write the depfile.
 149   if (!DependFilename.empty()) {
 150     if (int Ret = createDependencyFile(Parser, argv0))
 151       return Ret;
 152   }
 153
 154   Records.startTimer("Write output");
 155   bool WriteFile = true;
 156   if (WriteIfChanged) {
 157     // Only updates the real output file if there are any differences.
 158     // This prevents recompilation of all the files depending on it if there
 159     // aren't any.
 160     if (auto ExistingOrErr =
 161             MemoryBuffer::getFile(OutputFilename, /*IsText=*/true))
 162       if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
 163         WriteFile = false;
 164   }
 165   if (WriteFile) {
 166     std::error_code EC;
 167     ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text);
 168     if (EC)
 169       return reportError(argv0, "error opening " + OutputFilename + ": " +
 170                                     EC.message() + "\n");
 171     OutFile.os() << Out.str();
 172     if (ErrorsPrinted == 0)
 173       OutFile.keep();
 174   }
 175
 176   Records.stopTimer();
 177   Records.stopPhaseTiming();
 178
 179   if (ErrorsPrinted > 0)
 180     return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
 181   return 0;
 182 }