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
reportError(const char * ProgName,Twine Msg)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.
createDependencyFile(const TGParser & Parser,const char * argv0)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
TableGenMain(const char * argv0,std::function<TableGenMainFn> MainFn)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 }
183