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 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. 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 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