1 //===-- llvm/CodeGen/ByteStreamer.h - ByteStreamer class --------*- C++ -*-===// 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 // This file contains a class that can take bytes that would normally be 10 // streamed via the AsmPrinter. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_LIB_CODEGEN_ASMPRINTER_BYTESTREAMER_H 15 #define LLVM_LIB_CODEGEN_ASMPRINTER_BYTESTREAMER_H 16 17 #include "DIEHash.h" 18 #include "llvm/CodeGen/AsmPrinter.h" 19 #include "llvm/MC/MCStreamer.h" 20 #include "llvm/Support/LEB128.h" 21 #include <string> 22 23 namespace llvm { 24 class ByteStreamer { 25 protected: 26 ~ByteStreamer() = default; 27 ByteStreamer(const ByteStreamer&) = default; 28 ByteStreamer() = default; 29 30 public: 31 // For now we're just handling the calls we need for dwarf emission/hashing. 32 virtual void emitInt8(uint8_t Byte, const Twine &Comment = "") = 0; 33 virtual void emitSLEB128(uint64_t DWord, const Twine &Comment = "") = 0; 34 virtual void emitULEB128(uint64_t DWord, const Twine &Comment = "", 35 unsigned PadTo = 0) = 0; 36 virtual unsigned emitDIERef(const DIE &D) = 0; 37 }; 38 39 class APByteStreamer final : public ByteStreamer { 40 private: 41 AsmPrinter &AP; 42 43 public: 44 APByteStreamer(AsmPrinter &Asm) : AP(Asm) {} 45 void emitInt8(uint8_t Byte, const Twine &Comment) override { 46 AP.OutStreamer->AddComment(Comment); 47 AP.emitInt8(Byte); 48 } 49 void emitSLEB128(uint64_t DWord, const Twine &Comment) override { 50 AP.OutStreamer->AddComment(Comment); 51 AP.emitSLEB128(DWord); 52 } 53 void emitULEB128(uint64_t DWord, const Twine &Comment, 54 unsigned PadTo) override { 55 AP.OutStreamer->AddComment(Comment); 56 AP.emitULEB128(DWord, nullptr, PadTo); 57 } 58 unsigned emitDIERef(const DIE &D) override { 59 uint64_t Offset = D.getOffset(); 60 static constexpr unsigned ULEB128PadSize = 4; 61 assert(Offset < (1ULL << (ULEB128PadSize * 7)) && "Offset wont fit"); 62 emitULEB128(Offset, "", ULEB128PadSize); 63 // Return how many comments to skip in DwarfDebug::emitDebugLocEntry to keep 64 // comments aligned with debug loc entries. 65 return ULEB128PadSize; 66 } 67 }; 68 69 class HashingByteStreamer final : public ByteStreamer { 70 private: 71 DIEHash &Hash; 72 public: 73 HashingByteStreamer(DIEHash &H) : Hash(H) {} 74 void emitInt8(uint8_t Byte, const Twine &Comment) override { 75 Hash.update(Byte); 76 } 77 void emitSLEB128(uint64_t DWord, const Twine &Comment) override { 78 Hash.addSLEB128(DWord); 79 } 80 void emitULEB128(uint64_t DWord, const Twine &Comment, 81 unsigned PadTo) override { 82 Hash.addULEB128(DWord); 83 } 84 unsigned emitDIERef(const DIE &D) override { 85 Hash.hashRawTypeReference(D); 86 return 0; // Only used together with the APByteStreamer. 87 } 88 }; 89 90 class BufferByteStreamer final : public ByteStreamer { 91 private: 92 SmallVectorImpl<char> &Buffer; 93 std::vector<std::string> &Comments; 94 95 public: 96 /// Only verbose textual output needs comments. This will be set to 97 /// true for that case, and false otherwise. If false, comments passed in to 98 /// the emit methods will be ignored. 99 const bool GenerateComments; 100 101 BufferByteStreamer(SmallVectorImpl<char> &Buffer, 102 std::vector<std::string> &Comments, bool GenerateComments) 103 : Buffer(Buffer), Comments(Comments), GenerateComments(GenerateComments) { 104 } 105 void emitInt8(uint8_t Byte, const Twine &Comment) override { 106 Buffer.push_back(Byte); 107 if (GenerateComments) 108 Comments.push_back(Comment.str()); 109 } 110 void emitSLEB128(uint64_t DWord, const Twine &Comment) override { 111 raw_svector_ostream OSE(Buffer); 112 unsigned Length = encodeSLEB128(DWord, OSE); 113 if (GenerateComments) { 114 Comments.push_back(Comment.str()); 115 // Add some empty comments to keep the Buffer and Comments vectors aligned 116 // with each other. 117 for (size_t i = 1; i < Length; ++i) 118 Comments.push_back(""); 119 120 } 121 } 122 void emitULEB128(uint64_t DWord, const Twine &Comment, 123 unsigned PadTo) override { 124 raw_svector_ostream OSE(Buffer); 125 unsigned Length = encodeULEB128(DWord, OSE, PadTo); 126 if (GenerateComments) { 127 Comments.push_back(Comment.str()); 128 // Add some empty comments to keep the Buffer and Comments vectors aligned 129 // with each other. 130 for (size_t i = 1; i < Length; ++i) 131 Comments.push_back(""); 132 } 133 } 134 unsigned emitDIERef(const DIE &D) override { 135 uint64_t Offset = D.getOffset(); 136 static constexpr unsigned ULEB128PadSize = 4; 137 assert(Offset < (1ULL << (ULEB128PadSize * 7)) && "Offset wont fit"); 138 emitULEB128(Offset, "", ULEB128PadSize); 139 return 0; // Only used together with the APByteStreamer. 140 } 141 }; 142 143 } 144 145 #endif 146