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>
29using namespace llvm;
30
31static cl::opt<std::string>
32OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
33               cl::init("-"));
34
35static cl::opt<std::string>
36DependFilename("d",
37               cl::desc("Dependency filename"),
38               cl::value_desc("filename"),
39               cl::init(""));
40
41static cl::opt<std::string>
42InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
43
44static cl::list<std::string>
45IncludeDirs("I", cl::desc("Directory of include files"),
46            cl::value_desc("directory"), cl::Prefix);
47
48static cl::list<std::string>
49MacroNames("D", cl::desc("Name of the macro to be defined"),
50            cl::value_desc("macro name"), cl::Prefix);
51
52static cl::opt<bool>
53WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed"));
54
55static int reportError(const char *ProgName, Twine Msg) {
56  errs() << ProgName << ": " << Msg;
57  errs().flush();
58  return 1;
59}
60
61/// Create a dependency file for `-d` option.
62///
63/// This functionality is really only for the benefit of the build system.
64/// It is similar to GCC's `-M*` family of options.
65static int createDependencyFile(const TGParser &Parser, const char *argv0) {
66  if (OutputFilename == "-")
67    return reportError(argv0, "the option -d must be used together with -o\n");
68
69  std::error_code EC;
70  ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_None);
71  if (EC)
72    return reportError(argv0, "error opening " + DependFilename + ":" +
73                                  EC.message() + "\n");
74  DepOut.os() << OutputFilename << ":";
75  for (const auto &Dep : Parser.getDependencies()) {
76    DepOut.os() << ' ' << Dep;
77  }
78  DepOut.os() << "\n";
79  DepOut.keep();
80  return 0;
81}
82
83int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) {
84  RecordKeeper Records;
85
86  // Parse the input file.
87  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
88      MemoryBuffer::getFileOrSTDIN(InputFilename);
89  if (std::error_code EC = FileOrErr.getError())
90    return reportError(argv0, "Could not open input file '" + InputFilename +
91                                  "': " + EC.message() + "\n");
92
93  // Tell SrcMgr about this buffer, which is what TGParser will pick up.
94  SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
95
96  // Record the location of the include directory so that the lexer can find
97  // it later.
98  SrcMgr.setIncludeDirs(IncludeDirs);
99
100  TGParser Parser(SrcMgr, MacroNames, Records);
101
102  if (Parser.ParseFile())
103    return 1;
104
105  // Write output to memory.
106  std::string OutString;
107  raw_string_ostream Out(OutString);
108  if (MainFn(Out, Records))
109    return 1;
110
111  // Always write the depfile, even if the main output hasn't changed.
112  // If it's missing, Ninja considers the output dirty.  If this was below
113  // the early exit below and someone deleted the .inc.d file but not the .inc
114  // file, tablegen would never write the depfile.
115  if (!DependFilename.empty()) {
116    if (int Ret = createDependencyFile(Parser, argv0))
117      return Ret;
118  }
119
120  if (WriteIfChanged) {
121    // Only updates the real output file if there are any differences.
122    // This prevents recompilation of all the files depending on it if there
123    // aren't any.
124    if (auto ExistingOrErr = MemoryBuffer::getFile(OutputFilename))
125      if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
126        return 0;
127  }
128
129  std::error_code EC;
130  ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_None);
131  if (EC)
132    return reportError(argv0, "error opening " + OutputFilename + ":" +
133                                  EC.message() + "\n");
134  OutFile.os() << Out.str();
135
136  if (ErrorsPrinted > 0)
137    return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
138
139  // Declare success.
140  OutFile.keep();
141  return 0;
142}
143