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> 27 using namespace llvm; 28 29 static cl::opt<std::string> 30 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"), 31 cl::init("-")); 32 33 static cl::opt<std::string> 34 DependFilename("d", 35 cl::desc("Dependency filename"), 36 cl::value_desc("filename"), 37 cl::init("")); 38 39 static cl::opt<std::string> 40 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-")); 41 42 static cl::list<std::string> 43 IncludeDirs("I", cl::desc("Directory of include files"), 44 cl::value_desc("directory"), cl::Prefix); 45 46 static cl::list<std::string> 47 MacroNames("D", cl::desc("Name of the macro to be defined"), 48 cl::value_desc("macro name"), cl::Prefix); 49 50 static cl::opt<bool> 51 WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed")); 52 53 static cl::opt<bool> 54 TimePhases("time-phases", cl::desc("Time phases of parser and backend")); 55 56 static cl::opt<bool> NoWarnOnUnusedTemplateArgs( 57 "no-warn-on-unused-template-args", 58 cl::desc("Disable unused template argument warnings.")); 59 60 static 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. 70 static 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 88 int 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