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 int reportError(const char *ProgName, Twine Msg) { 56 errs() << ProgName << ": " << Msg; 57 errs().flush(); 58 return 1; 59 } 60 61 /// Create a dependency file for `-d` option. 62 /// 63 /// This functionality is really only for the benefit of the build system. 64 /// It is similar to GCC's `-M*` family of options. 65 static int createDependencyFile(const TGParser &Parser, const char *argv0) { 66 if (OutputFilename == "-") 67 return reportError(argv0, "the option -d must be used together with -o\n"); 68 69 std::error_code EC; 70 ToolOutputFile DepOut(DependFilename, EC, sys::fs::OF_None); 71 if (EC) 72 return reportError(argv0, "error opening " + DependFilename + ":" + 73 EC.message() + "\n"); 74 DepOut.os() << OutputFilename << ":"; 75 for (const auto &Dep : Parser.getDependencies()) { 76 DepOut.os() << ' ' << Dep; 77 } 78 DepOut.os() << "\n"; 79 DepOut.keep(); 80 return 0; 81 } 82 83 int llvm::TableGenMain(const char *argv0, TableGenMainFn *MainFn) { 84 RecordKeeper Records; 85 86 // Parse the input file. 87 ErrorOr<std::unique_ptr<MemoryBuffer>> FileOrErr = 88 MemoryBuffer::getFileOrSTDIN(InputFilename); 89 if (std::error_code EC = FileOrErr.getError()) 90 return reportError(argv0, "Could not open input file '" + InputFilename + 91 "': " + EC.message() + "\n"); 92 93 // Tell SrcMgr about this buffer, which is what TGParser will pick up. 94 SrcMgr.AddNewSourceBuffer(std::move(*FileOrErr), SMLoc()); 95 96 // Record the location of the include directory so that the lexer can find 97 // it later. 98 SrcMgr.setIncludeDirs(IncludeDirs); 99 100 TGParser Parser(SrcMgr, MacroNames, Records); 101 102 if (Parser.ParseFile()) 103 return 1; 104 105 // Write output to memory. 106 std::string OutString; 107 raw_string_ostream Out(OutString); 108 if (MainFn(Out, Records)) 109 return 1; 110 111 // Always write the depfile, even if the main output hasn't changed. 112 // If it's missing, Ninja considers the output dirty. If this was below 113 // the early exit below and someone deleted the .inc.d file but not the .inc 114 // file, tablegen would never write the depfile. 115 if (!DependFilename.empty()) { 116 if (int Ret = createDependencyFile(Parser, argv0)) 117 return Ret; 118 } 119 120 if (WriteIfChanged) { 121 // Only updates the real output file if there are any differences. 122 // This prevents recompilation of all the files depending on it if there 123 // aren't any. 124 if (auto ExistingOrErr = MemoryBuffer::getFile(OutputFilename)) 125 if (std::move(ExistingOrErr.get())->getBuffer() == Out.str()) 126 return 0; 127 } 128 129 std::error_code EC; 130 ToolOutputFile OutFile(OutputFilename, EC, sys::fs::OF_None); 131 if (EC) 132 return reportError(argv0, "error opening " + OutputFilename + ":" + 133 EC.message() + "\n"); 134 OutFile.os() << Out.str(); 135 136 if (ErrorsPrinted > 0) 137 return reportError(argv0, Twine(ErrorsPrinted) + " errors.\n"); 138 139 // Declare success. 140 OutFile.keep(); 141 return 0; 142 } 143