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> 29 using namespace llvm; 30 31 static cl::opt<std::string> 32 OutputFilename("o", cl::desc("Output filename"), cl::value_desc("filename"), 33 cl::init("-")); 34 35 static cl::opt<std::string> 36 DependFilename("d", 37 cl::desc("Dependency filename"), 38 cl::value_desc("filename"), 39 cl::init("")); 40 41 static cl::opt<std::string> 42 InputFilename(cl::Positional, cl::desc("<input file>"), cl::init("-")); 43 44 static cl::list<std::string> 45 IncludeDirs("I", cl::desc("Directory of include files"), 46 cl::value_desc("directory"), cl::Prefix); 47 48 static cl::list<std::string> 49 MacroNames("D", cl::desc("Name of the macro to be defined"), 50 cl::value_desc("macro name"), cl::Prefix); 51 52 static cl::opt<bool> 53 WriteIfChanged("write-if-changed", cl::desc("Only write output if it changed")); 54 55 static cl::opt<bool> 56 TimePhases("time-phases", cl::desc("Time phases of parser and backend")); 57 58 static cl::opt<bool> NoWarnOnUnusedTemplateArgs( 59 "no-warn-on-unused-template-args", 60 cl::desc("Disable unused template argument warnings.")); 61 62 static int reportError(const char *ProgName, Twine Msg) { 63 errs() << ProgName << ": " << Msg; 64 errs().flush(); 65 return 1; 66 } 67 68 /// Create a dependency file for `-d` option. 69 /// 70 /// This functionality is really only for the benefit of the build system. 71 /// It is similar to GCC's `-M*` family of options. 72 static int createDependencyFile(const TGParser &Parser, const char *argv0) { 73 if (OutputFilename == "-") 74 return reportError(argv0, "the option -d must be used together with -o\n"); 75 76 std::error_code EC; 77 ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text); 78 if (EC) 79 return reportError(argv0, "error opening " + DependFilename + ":" + 80 EC.message() + "\n"); 81 DepOut.os() << OutputFilename << ":"; 82 for (const auto &Dep : Parser.getDependencies()) { 83 DepOut.os() << ' ' << Dep; 84 } 85 DepOut.os() << "\n"; 86 DepOut.keep(); 87 return 0; 88 } 89 90 int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) { 91 RecordKeeper Records; 92 93 if (TimePhases) 94 Records.startPhaseTiming(); 95 96 // Parse the input file. 97 98 Records.startTimer("Parse, build records"); 99 ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr = 100 MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true); 101 if (std::error_code EC = FileOrErr.getError()) 102 return reportError(argv0, "Could not open input file '" + InputFilename + 103 "': " + EC.message() + "\n"); 104 105 Records.saveInputFilename(InputFilename); 106 107 // Tell SrcMgr about this buffer, which is what TGParser will pick up. 108 SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc()); 109 110 // Record the location of the include directory so that the lexer can find 111 // it later. 112 SrcMgr.setIncludeDirs(IncludeDirs); 113 114 TGParser Parser(SrcMgr, MacroNames, Records, NoWarnOnUnusedTemplateArgs); 115 116 if (Parser.ParseFile()) 117 return 1; 118 Records.stopTimer(); 119 120 // Write output to memory. 121 Records.startBackendTimer("Backend overall"); 122 std::string OutString; 123 raw_string_ostream Out(OutString); 124 unsigned status = MainFn(Out, Records); 125 Records.stopBackendTimer(); 126 if (status) 127 return 1; 128 129 // Always write the depfile, even if the main output hasn't changed. 130 // If it's missing, Ninja considers the output dirty. If this was below 131 // the early exit below and someone deleted the .inc.d file but not the .inc 132 // file, tablegen would never write the depfile. 133 if (!DependFilename.empty()) { 134 if (int Ret = createDependencyFile(Parser, argv0)) 135 return Ret; 136 } 137 138 Records.startTimer("Write output"); 139 bool WriteFile = true; 140 if (WriteIfChanged) { 141 // Only updates the real output file if there are any differences. 142 // This prevents recompilation of all the files depending on it if there 143 // aren't any. 144 if (auto ExistingOrErr = 145 MemoryBuffer::getFile(OutputFilename, /*IsText=*/true)) 146 if (std::move(ExistingOrErr.get())->getBuffer() == Out.str()) 147 WriteFile = false; 148 } 149 if (WriteFile) { 150 std::error_code EC; 151 ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text); 152 if (EC) 153 return reportError(argv0, "error opening " + OutputFilename + ": " + 154 EC.message() + "\n"); 155 OutFile.os() << Out.str(); 156 if (ErrorsPrinted == 0) 157 OutFile.keep(); 158 } 159 160 Records.stopTimer(); 161 Records.stopPhaseTiming(); 162 163 if (ErrorsPrinted > 0) 164 return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n"); 165 return 0; 166 } 167