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/Support/CommandLine.h"
20#include "llvm/Support/FileSystem.h"
21#include "llvm/Support/MemoryBuffer.h"
22#include "llvm/Support/ToolOutputFile.h"
23#include "llvm/TableGen/Error.h"
24#include "llvm/TableGen/Record.h"
25#include <algorithm>
26#include <system_error>
27using namespace llvm;
28
29static cl::opt<std::string>
30OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"),
31               cl::init("-"));
32
33static cl::opt<std::string>
34DependFilename("d",
35               cl::desc("Dependency filename"),
36               cl::value_desc("filename"),
37               cl::init(""));
38
39static cl::opt<std::string>
40InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-"));
41
42static cl::list<std::string>
43IncludeDirs("I", cl::desc("Directory of include files"),
44            cl::value_desc("directory"), cl::Prefix);
45
46static cl::list<std::string>
47MacroNames("D", cl::desc("Name of the macro to be defined"),
48            cl::value_desc("macro name"), cl::Prefix);
49
50static cl::opt<bool>
51WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed"));
52
53static cl::opt<bool>
54TimePhases("time-phases", cl::desc("Time phases of parser and backend"));
55
56static cl::opt<bool> NoWarnOnUnusedTemplateArgs(
57    "no-warn-on-unused-template-args",
58    cl::desc("Disable unused template argument warnings."));
59
60static int reportError(const char *ProgName, Twine Msg) {
61  errs() << ProgName << ": " << Msg;
62  errs().flush();
63  return 1;
64}
65
66/// Create a dependency file for `-d` option.
67///
68/// This functionality is really only for the benefit of the build system.
69/// It is similar to GCC's `-M*` family of options.
70static int createDependencyFile(const TGParser &Parser, const char *argv0) {
71  if (OutputFilename == "-")
72    return reportError(argv0, "the option -d must be used together with -o\n");
73
74  std::error_code EC;
75  ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text);
76  if (EC)
77    return reportError(argv0, "error opening " + DependFilename + ":" +
78                                  EC.message() + "\n");
79  DepOut.os() << OutputFilename << ":";
80  for (const auto &Dep : Parser.getDependencies()) {
81    DepOut.os() << ' ' << Dep;
82  }
83  DepOut.os() << "\n";
84  DepOut.keep();
85  return 0;
86}
87
88int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) {
89  RecordKeeper Records;
90
91  if (TimePhases)
92    Records.startPhaseTiming();
93
94  // Parse the input file.
95
96  Records.startTimer("Parse, build records");
97  ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr =
98      MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true);
99  if (std::error_code EC = FileOrErr.getError())
100    return reportError(argv0, "Could not open input file '" + InputFilename +
101                                  "': " + EC.message() + "\n");
102
103  Records.saveInputFilename(InputFilename);
104
105  // Tell SrcMgr about this buffer, which is what TGParser will pick up.
106  SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc());
107
108  // Record the location of the include directory so that the lexer can find
109  // it later.
110  SrcMgr.setIncludeDirs(IncludeDirs);
111
112  TGParser Parser(SrcMgr, MacroNames, Records, NoWarnOnUnusedTemplateArgs);
113
114  if (Parser.ParseFile())
115    return 1;
116  Records.stopTimer();
117
118  // Write output to memory.
119  Records.startBackendTimer("Backend overall");
120  std::string OutString;
121  raw_string_ostream Out(OutString);
122  unsigned status = MainFn(Out, Records);
123  Records.stopBackendTimer();
124  if (status)
125    return 1;
126
127  // Always write the depfile, even if the main output hasn't changed.
128  // If it's missing, Ninja considers the output dirty.  If this was below
129  // the early exit below and someone deleted the .inc.d file but not the .inc
130  // file, tablegen would never write the depfile.
131  if (!DependFilename.empty()) {
132    if (int Ret = createDependencyFile(Parser, argv0))
133      return Ret;
134  }
135
136  Records.startTimer("Write output");
137  bool WriteFile = true;
138  if (WriteIfChanged) {
139    // Only updates the real output file if there are any differences.
140    // This prevents recompilation of all the files depending on it if there
141    // aren't any.
142    if (auto ExistingOrErr =
143            MemoryBuffer::getFile(OutputFilename, /*IsText=*/true))
144      if (std::move(ExistingOrErr.get())->getBuffer() == Out.str())
145        WriteFile = false;
146  }
147  if (WriteFile) {
148    std::error_code EC;
149    ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text);
150    if (EC)
151      return reportError(argv0, "error opening " + OutputFilename + ": " +
152                                    EC.message() + "\n");
153    OutFile.os() << Out.str();
154    if (ErrorsPrinted == 0)
155      OutFile.keep();
156  }
157
158  Records.stopTimer();
159  Records.stopPhaseTiming();
160
161  if (ErrorsPrinted > 0)
162    return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n");
163  return 0;
164}
165