llvm/lib/TableGen/TableGenBackend.cpp

   1 //===- TableGenBackend.cpp - Utilities for TableGen Backends ----*- C++ -*-===//
   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 // This file provides useful services for TableGen backends...
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/TableGen/TableGenBackend.h"
  14 #include "llvm/ADT/Twine.h"
  15 #include "llvm/Support/CommandLine.h"
  16 #include "llvm/Support/ManagedStatic.h"
  17 #include "llvm/Support/Path.h"
  18 #include "llvm/Support/raw_ostream.h"
  19 #include <algorithm>
  20 #include <cassert>
  21 #include <cstddef>
  22
  23 using namespace llvm;
  24 using namespace TableGen::Emitter;
  25
  26 const size_t MAX_LINE_LEN = 80U;
  27
  28 // CommandLine options of class type are not directly supported with some
  29 // specific exceptions like std::string which are safe to copy. In our case,
  30 // the `FnT` function_ref object is also safe to copy. So provide a
  31 // specialization of `OptionValue` for `FnT` type that stores it as a copy.
  32 // This is essentially similar to OptionValue<std::string> specialization for
  33 // strings.
  34 template <> struct cl::OptionValue<FnT> final : cl::OptionValueCopy<FnT> {
  35   OptionValue() = default;
  36
  37   OptionValue(const FnT &V) { this->setValue(V); }
  38
  39   OptionValue<FnT> &operator=(const FnT &V) {
  40     setValue(V);
  41     return *this;
  42   }
  43 };
  44
  45 namespace {
  46 struct OptCreatorT {
  47   static void *call() {
  48     return new cl::opt<FnT>(cl::desc("Action to perform:"));
  49   }
  50 };
  51 } // namespace
  52
  53 static ManagedStatic<cl::opt<FnT>, OptCreatorT> CallbackFunction;
  54
  55 Opt::Opt(StringRef Name, FnT CB, StringRef Desc, bool ByDefault) {
  56   if (ByDefault)
  57     CallbackFunction->setInitialValue(CB);
  58   CallbackFunction->getParser().addLiteralOption(Name, CB, Desc);
  59 }
  60
  61 /// Apply callback specified on the command line. Returns true if no callback
  62 /// was applied.
  63 bool llvm::TableGen::Emitter::ApplyCallback(const RecordKeeper &Records,
  64                                             raw_ostream &OS) {
  65   FnT Fn = CallbackFunction->getValue();
  66   if (!Fn)
  67     return true;
  68   Fn(Records, OS);
  69   return false;
  70 }
  71
  72 static void printLine(raw_ostream &OS, const Twine &Prefix, char Fill,
  73                       StringRef Suffix) {
  74   size_t Pos = (size_t)OS.tell();
  75   assert((Prefix.str().size() + Suffix.size() <= MAX_LINE_LEN) &&
  76          "header line exceeds max limit");
  77   OS << Prefix;
  78   for (size_t i = (size_t)OS.tell() - Pos, e = MAX_LINE_LEN - Suffix.size();
  79          i < e; ++i)
  80     OS << Fill;
  81   OS << Suffix << '\n';
  82 }
  83
  84 void llvm::emitSourceFileHeader(StringRef Desc, raw_ostream &OS,
  85                                 const RecordKeeper &Record) {
  86   printLine(OS, "/*===- TableGen'erated file ", '-', "*- C++ -*-===*\\");
  87   StringRef Prefix("|* ");
  88   StringRef Suffix(" *|");
  89   printLine(OS, Prefix, ' ', Suffix);
  90   size_t PSLen = Prefix.size() + Suffix.size();
  91   assert(PSLen < MAX_LINE_LEN);
  92   size_t Pos = 0U;
  93   do {
  94     size_t Length = std::min(Desc.size() - Pos, MAX_LINE_LEN - PSLen);
  95     printLine(OS, Prefix + Desc.substr(Pos, Length), ' ', Suffix);
  96     Pos += Length;
  97   } while (Pos < Desc.size());
  98   printLine(OS, Prefix, ' ', Suffix);
  99   printLine(OS, Prefix + "Automatically generated file, do not edit!", ' ',
 100             Suffix);
 101
 102   // Print the filename of source file.
 103   if (!Record.getInputFilename().empty())
 104     printLine(
 105         OS, Prefix + "From: " + sys::path::filename(Record.getInputFilename()),
 106         ' ', Suffix);
 107   printLine(OS, Prefix, ' ', Suffix);
 108   printLine(OS, "\\*===", '-', "===*/");
 109   OS << '\n';
 110 }