1//===- llvm/MC/MCDXContainerWriter.cpp - DXContainer Writer -----*- 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#include "llvm/MC/MCDXContainerWriter.h"
10#include "llvm/BinaryFormat/DXContainer.h"
11#include "llvm/MC/MCAssembler.h"
12#include "llvm/MC/MCContext.h"
13#include "llvm/MC/MCSection.h"
14#include "llvm/MC/MCValue.h"
15#include "llvm/Support/Alignment.h"
16
17using namespace llvm;
18
19MCDXContainerTargetWriter::~MCDXContainerTargetWriter() = default;
20
21MCDXContainerBaseWriter::~MCDXContainerBaseWriter() = default;
22
23bool MCDXContainerBaseWriter::shouldSkipSection(StringRef SectionName,
24 size_t SectionSize) {
25 // Skip empty and auxiliary sections.
26 return SectionSize == 0 || SectionName == PdbFileNameSectionName ||
27 SectionName == ModuleHashSectionName;
28}
29
30void MCDXContainerBaseWriter::write(raw_ostream &OS, const Triple &TT) {
31 ArrayRef<MCDXContainerPart> Parts = collectParts();
32
33 support::endian::Writer W(OS, llvm::endianness::little);
34
35 // Start the file size as the header plus the size of the part offsets.
36 // Presently DXContainer files usually contain 7-10 parts. Reserving space for
37 // 16 part offsets gives us a little room for growth.
38 llvm::SmallVector<uint64_t, 16> PartOffsets;
39 uint64_t PartOffset = 0;
40 bool HasPrivate = false;
41 for (const MCDXContainerPart &Part : Parts) {
42 if (HasPrivate)
43 reportFatalInternalError(
44 reason: "PRIV must be the last section in a DXContainer");
45 if (Part.Name == "PRIV")
46 HasPrivate = true;
47
48 uint64_t SectionSize = Part.Data.size();
49 assert(SectionSize < std::numeric_limits<uint32_t>::max() &&
50 "Section size too large for DXContainer");
51
52 PartOffsets.push_back(Elt: PartOffset);
53 PartOffset += sizeof(dxbc::PartHeader) + SectionSize;
54 if (!HasPrivate)
55 PartOffset = alignTo(Size: PartOffset, A: Align(4ul));
56 // The DXIL part also writes a program header, so we need to include its
57 // size when computing the offset for a part after the DXIL part.
58 if (dxbc::isProgramPart(PartName: Part.Name))
59 PartOffset += sizeof(dxbc::ProgramHeader);
60 }
61 assert(PartOffset < std::numeric_limits<uint32_t>::max() &&
62 "Part data too large for DXContainer");
63
64 uint64_t PartStart =
65 sizeof(dxbc::Header) + (PartOffsets.size() * sizeof(uint32_t));
66 uint64_t FileSize = PartStart + PartOffset;
67 assert(FileSize < std::numeric_limits<uint32_t>::max() &&
68 "File size too large for DXContainer");
69
70 // Write the header.
71 W.write<char>(Val: {'D', 'X', 'B', 'C'});
72 // Write 16-bytes of 0's for the hash.
73 W.OS.write_zeros(NumZeros: 16);
74 // Write 1.0 for file format version.
75 W.write<uint16_t>(Val: 1u);
76 W.write<uint16_t>(Val: 0u);
77 // Write the file size.
78 W.write<uint32_t>(Val: static_cast<uint32_t>(FileSize));
79 // Write the number of parts.
80 W.write<uint32_t>(Val: static_cast<uint32_t>(PartOffsets.size()));
81 // Write the offsets for the part headers for each part.
82 for (uint64_t Offset : PartOffsets)
83 W.write<uint32_t>(Val: static_cast<uint32_t>(PartStart + Offset));
84
85 for (const MCDXContainerPart &Part : Parts) {
86 uint64_t SectionSize = Part.Data.size();
87 unsigned Start = W.OS.tell();
88 // Write section header.
89 W.write<char>(Val: ArrayRef<char>(Part.Name.data(), 4));
90
91 uint64_t PartSize = SectionSize;
92
93 if (dxbc::isProgramPart(PartName: Part.Name))
94 PartSize += sizeof(dxbc::ProgramHeader);
95 // DXContainer part should be 4-byte aligned, unless it is PRIV part.
96 bool IsPrivate = Part.Name == "PRIV";
97 if (!IsPrivate)
98 PartSize = alignTo(Size: PartSize, A: Align(4));
99 W.write<uint32_t>(Val: static_cast<uint32_t>(PartSize));
100 if (dxbc::isProgramPart(PartName: Part.Name)) {
101 dxbc::ProgramHeader Header;
102 memset(s: reinterpret_cast<void *>(&Header), c: 0, n: sizeof(dxbc::ProgramHeader));
103
104 VersionTuple Version = TT.getOSVersion();
105 uint8_t MajorVersion = static_cast<uint8_t>(Version.getMajor());
106 uint8_t MinorVersion =
107 static_cast<uint8_t>(Version.getMinor().value_or(u: 0));
108 Header.Version =
109 dxbc::ProgramHeader::getVersion(Major: MajorVersion, Minor: MinorVersion);
110 if (TT.hasEnvironment())
111 Header.ShaderKind =
112 static_cast<uint16_t>(TT.getEnvironment() - Triple::Pixel);
113
114 // The program header's size field is in 32-bit words.
115 Header.Size = (SectionSize + sizeof(dxbc::ProgramHeader) + 3) / 4;
116 memcpy(dest: Header.Bitcode.Magic, src: "DXIL", n: 4);
117 VersionTuple DXILVersion = TT.getDXILVersion();
118 Header.Bitcode.MajorVersion = DXILVersion.getMajor();
119 Header.Bitcode.MinorVersion = DXILVersion.getMinor().value_or(u: 0);
120 Header.Bitcode.Offset = sizeof(dxbc::BitcodeHeader);
121 Header.Bitcode.Size = SectionSize;
122 if (sys::IsBigEndianHost)
123 Header.swapBytes();
124 W.write<char>(Val: ArrayRef<char>(reinterpret_cast<char *>(&Header),
125 sizeof(dxbc::ProgramHeader)));
126 }
127 W.write<char>(Val: Part.Data);
128 if (!IsPrivate) {
129 unsigned Size = W.OS.tell() - Start;
130 W.OS.write_zeros(NumZeros: offsetToAlignment(Value: Size, Alignment: Align(4)));
131 }
132 }
133}
134
135void DXContainerObjectWriter::clearParts() {
136 Parts.clear();
137 SectionBuffers.clear();
138}
139
140ArrayRef<MCDXContainerPart> DXContainerObjectWriter::collectParts() {
141 clearParts();
142 for (const MCSection &Sec : *Asm) {
143 if (shouldSkipSection(SectionName: Sec.getName(), SectionSize: Asm->getSectionAddressSize(Sec)))
144 continue;
145
146 SectionBuffers.emplace_back();
147 raw_svector_ostream OS(SectionBuffers.back());
148 Asm->writeSectionData(OS, Section: &Sec);
149 Parts.push_back(Elt: {.Name: Sec.getName(), .Data: StringRef(SectionBuffers.back())});
150 }
151 return Parts;
152}
153
154bool DXContainerObjectWriter::shouldSkipSection(StringRef SectionName,
155 size_t SectionSize) {
156 if (TargetObjectWriter->shouldSkipSection(SectionName))
157 return true;
158 if (SectionName == "SRCI")
159 return true;
160 return MCDXContainerBaseWriter::shouldSkipSection(SectionName, SectionSize);
161}
162
163uint64_t DXContainerObjectWriter::writeObject() {
164 write(OS&: W.OS, TT: getContext().getTargetTriple());
165 clearParts();
166
167 return 0;
168}
169