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
23namespace llvm {
24class 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
39class APByteStreamer final : public ByteStreamer {
40private:
41 AsmPrinter &AP;
42
43public:
44 APByteStreamer(AsmPrinter &Asm) : AP(Asm) {}
45 void emitInt8(uint8_t Byte, const Twine &Comment) override {
46 AP.OutStreamer->AddComment(T: Comment);
47 AP.emitInt8(Value: Byte);
48 }
49 void emitSLEB128(uint64_t DWord, const Twine &Comment) override {
50 AP.OutStreamer->AddComment(T: Comment);
51 AP.emitSLEB128(Value: DWord);
52 }
53 void emitULEB128(uint64_t DWord, const Twine &Comment,
54 unsigned PadTo) override {
55 AP.OutStreamer->AddComment(T: Comment);
56 AP.emitULEB128(Value: DWord, Desc: 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(DWord: Offset, Comment: "", PadTo: 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
69class 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(Value: Byte);
76 }
77 void emitSLEB128(uint64_t DWord, const Twine &Comment) override {
78 Hash.addSLEB128(Value: DWord);
79 }
80 void emitULEB128(uint64_t DWord, const Twine &Comment,
81 unsigned PadTo) override {
82 Hash.addULEB128(Value: DWord);
83 }
84 unsigned emitDIERef(const DIE &D) override {
85 Hash.hashRawTypeReference(Entry: D);
86 return 0; // Only used together with the APByteStreamer.
87 }
88};
89
90class BufferByteStreamer final : public ByteStreamer {
91private:
92 SmallVectorImpl<char> &Buffer;
93 std::vector<std::string> &Comments;
94
95public:
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(Elt: Byte);
107 if (GenerateComments)
108 Comments.push_back(x: Comment.str());
109 }
110 void emitSLEB128(uint64_t DWord, const Twine &Comment) override {
111 raw_svector_ostream OSE(Buffer);
112 unsigned Length = encodeSLEB128(Value: DWord, OS&: OSE);
113 if (GenerateComments) {
114 Comments.push_back(x: 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(x: "");
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(Value: DWord, OS&: OSE, PadTo);
126 if (GenerateComments) {
127 Comments.push_back(x: 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(x: "");
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(DWord: Offset, Comment: "", PadTo: ULEB128PadSize);
139 return 0; // Only used together with the APByteStreamer.
140 }
141};
142
143}
144
145#endif
146