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 int reportError(const char *ProgName, Twine Msg) { 59 errs() << ProgName << ": " << Msg; 60 errs().flush(); 61 return 1; 62 } 63 64 /// Create a dependency file for `-d` option. 65 /// 66 /// This functionality is really only for the benefit of the build system. 67 /// It is similar to GCC's `-M*` family of options. 68 static int createDependencyFile(const TGParser &Parser, const char *argv0) { 69 if (OutputFilename == "-") 70 return reportError(argv0, "the option -d must be used together with -o\n"); 71 72 std::error_code EC; 73 ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_Text); 74 if (EC) 75 return reportError(argv0, "error opening " + DependFilename + ":" + 76 EC.message() + "\n"); 77 DepOut.os() << OutputFilename << ":"; 78 for (const auto &Dep : Parser.getDependencies()) { 79 DepOut.os() << ' ' << Dep; 80 } 81 DepOut.os() << "\n"; 82 DepOut.keep(); 83 return 0; 84 } 85 86 int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) { 87 RecordKeeper Records; 88 89 if (TimePhases) 90 Records.startPhaseTiming(); 91 92 // Parse the input file. 93 94 Records.startTimer("Parse, build records"); 95 ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr = 96 MemoryBuffer::getFileOrSTDIN(InputFilename, /*IsText=*/true); 97 if (std::error_code EC = FileOrErr.getError()) 98 return reportError(argv0, "Could not open input file '" + InputFilename + 99 "': " + EC.message() + "\n"); 100 101 Records.saveInputFilename(InputFilename); 102 103 // Tell SrcMgr about this buffer, which is what TGParser will pick up. 104 SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc()); 105 106 // Record the location of the include directory so that the lexer can find 107 // it later. 108 SrcMgr.setIncludeDirs(IncludeDirs); 109 110 TGParser Parser(SrcMgr, MacroNames, Records); 111 112 if (Parser.ParseFile()) 113 return 1; 114 Records.stopTimer(); 115 116 // Write output to memory. 117 Records.startBackendTimer("Backend overall"); 118 std::string OutString; 119 raw_string_ostream Out(OutString); 120 unsigned status = MainFn(Out, Records); 121 Records.stopBackendTimer(); 122 if (status) 123 return 1; 124 125 // Always write the depfile, even if the main output hasn't changed. 126 // If it's missing, Ninja considers the output dirty. If this was below 127 // the early exit below and someone deleted the .inc.d file but not the .inc 128 // file, tablegen would never write the depfile. 129 if (!DependFilename.empty()) { 130 if (int Ret = createDependencyFile(Parser, argv0)) 131 return Ret; 132 } 133 134 Records.startTimer("Write output"); 135 bool WriteFile = true; 136 if (WriteIfChanged) { 137 // Only updates the real output file if there are any differences. 138 // This prevents recompilation of all the files depending on it if there 139 // aren't any. 140 if (auto ExistingOrErr = 141 MemoryBuffer::getFile(OutputFilename, /*IsText=*/true)) 142 if (std::move(ExistingOrErr.get())->getBuffer() == Out.str()) 143 WriteFile = false; 144 } 145 if (WriteFile) { 146 std::error_code EC; 147 ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_Text); 148 if (EC) 149 return reportError(argv0, "error opening " + OutputFilename + ": " + 150 EC.message() + "\n"); 151 OutFile.os() << Out.str(); 152 if (ErrorsPrinted == 0) 153 OutFile.keep(); 154 } 155 156 Records.stopTimer(); 157 Records.stopPhaseTiming(); 158 159 if (ErrorsPrinted > 0) 160 return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n"); 161 return 0; 162 } 163