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
23using namespace llvm;
24using namespace TableGen::Emitter;
25
26const 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.
34template <> 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
45namespace {
46struct OptCreatorT {
47 static void *call() {
48 return new cl::opt<FnT>(cl::desc("Action to perform:"));
49 }
50};
51} // namespace
52
53static ManagedStatic<cl::opt<FnT>, OptCreatorT> CallbackFunction;
54
55Opt::Opt(StringRef Name, FnT CB, StringRef Desc, bool ByDefault) {
56 if (ByDefault)
57 CallbackFunction->setInitialValue(CB);
58 CallbackFunction->getParser().addLiteralOption(Name, V: CB, HelpStr: Desc);
59}
60
61/// Apply callback specified on the command line. Returns true if no callback
62/// was applied.
63bool 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
72static 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
84void llvm::emitSourceFileHeader(StringRef Desc, raw_ostream &OS,
85 const RecordKeeper &Record) {
86 printLine(OS, Prefix: "/*===- TableGen'erated file ", Fill: '-', Suffix: "*- C++ -*-===*\\");
87 StringRef Prefix("|* ");
88 StringRef Suffix(" *|");
89 printLine(OS, Prefix, Fill: ' ', 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(a: Desc.size() - Pos, b: MAX_LINE_LEN - PSLen);
95 printLine(OS, Prefix: Prefix + Desc.substr(Start: Pos, N: Length), Fill: ' ', Suffix);
96 Pos += Length;
97 } while (Pos < Desc.size());
98 printLine(OS, Prefix, Fill: ' ', Suffix);
99 printLine(OS, Prefix: Prefix + "Automatically generated file, do not edit!", Fill: ' ',
100 Suffix);
101
102 // Print the filename of source file.
103 if (!Record.getInputFilename().empty())
104 printLine(
105 OS, Prefix: Prefix + "From: " + sys::path::filename(path: Record.getInputFilename()),
106 Fill: ' ', Suffix);
107 printLine(OS, Prefix, Fill: ' ', Suffix);
108 printLine(OS, Prefix: "\\*===", Fill: '-', Suffix: "===*/");
109 OS << '\n';
110}
111