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 17 using namespace llvm; 18 19 MCDXContainerTargetWriter::~MCDXContainerTargetWriter() {} 20 21 uint64_t DXContainerObjectWriter::writeObject(MCAssembler &Asm) { 22 // Start the file size as the header plus the size of the part offsets. 23 // Presently DXContainer files usually contain 7-10 parts. Reserving space for 24 // 16 part offsets gives us a little room for growth. 25 llvm::SmallVector<uint64_t, 16> PartOffsets; 26 uint64_t PartOffset = 0; 27 for (const MCSection &Sec : Asm) { 28 uint64_t SectionSize = Asm.getSectionAddressSize(Sec); 29 // Skip empty sections. 30 if (SectionSize == 0) 31 continue; 32 33 assert(SectionSize < std::numeric_limits<uint32_t>::max() && 34 "Section size too large for DXContainer"); 35 36 PartOffsets.push_back(PartOffset); 37 PartOffset += sizeof(dxbc::PartHeader) + SectionSize; 38 PartOffset = alignTo(PartOffset, Align(4ul)); 39 // The DXIL part also writes a program header, so we need to include its 40 // size when computing the offset for a part after the DXIL part. 41 if (Sec.getName() == "DXIL") 42 PartOffset += sizeof(dxbc::ProgramHeader); 43 } 44 assert(PartOffset < std::numeric_limits<uint32_t>::max() && 45 "Part data too large for DXContainer"); 46 47 uint64_t PartStart = 48 sizeof(dxbc::Header) + (PartOffsets.size() * sizeof(uint32_t)); 49 uint64_t FileSize = PartStart + PartOffset; 50 assert(FileSize < std::numeric_limits<uint32_t>::max() && 51 "File size too large for DXContainer"); 52 53 // Write the header. 54 W.write<char>({'D', 'X', 'B', 'C'}); 55 // Write 16-bytes of 0's for the hash. 56 W.OS.write_zeros(16); 57 // Write 1.0 for file format version. 58 W.write<uint16_t>(1u); 59 W.write<uint16_t>(0u); 60 // Write the file size. 61 W.write<uint32_t>(static_cast<uint32_t>(FileSize)); 62 // Write the number of parts. 63 W.write<uint32_t>(static_cast<uint32_t>(PartOffsets.size())); 64 // Write the offsets for the part headers for each part. 65 for (uint64_t Offset : PartOffsets) 66 W.write<uint32_t>(static_cast<uint32_t>(PartStart + Offset)); 67 68 for (const MCSection &Sec : Asm) { 69 uint64_t SectionSize = Asm.getSectionAddressSize(Sec); 70 // Skip empty sections. 71 if (SectionSize == 0) 72 continue; 73 74 unsigned Start = W.OS.tell(); 75 // Write section header. 76 W.write<char>(ArrayRef<char>(Sec.getName().data(), 4)); 77 78 uint64_t PartSize = SectionSize; 79 80 if (Sec.getName() == "DXIL") 81 PartSize += sizeof(dxbc::ProgramHeader); 82 // DXContainer parts should be 4-byte aligned. 83 PartSize = alignTo(PartSize, Align(4)); 84 W.write<uint32_t>(static_cast<uint32_t>(PartSize)); 85 if (Sec.getName() == "DXIL") { 86 dxbc::ProgramHeader Header; 87 memset(reinterpret_cast<void *>(&Header), 0, sizeof(dxbc::ProgramHeader)); 88 89 const Triple &TT = Asm.getContext().getTargetTriple(); 90 VersionTuple Version = TT.getOSVersion(); 91 uint8_t MajorVersion = static_cast<uint8_t>(Version.getMajor()); 92 uint8_t MinorVersion = 93 static_cast<uint8_t>(Version.getMinor().value_or(0)); 94 Header.Version = 95 dxbc::ProgramHeader::getVersion(MajorVersion, MinorVersion); 96 if (TT.hasEnvironment()) 97 Header.ShaderKind = 98 static_cast<uint16_t>(TT.getEnvironment() - Triple::Pixel); 99 100 // The program header's size field is in 32-bit words. 101 Header.Size = (SectionSize + sizeof(dxbc::ProgramHeader) + 3) / 4; 102 memcpy(Header.Bitcode.Magic, "DXIL", 4); 103 VersionTuple DXILVersion = TT.getDXILVersion(); 104 Header.Bitcode.MajorVersion = DXILVersion.getMajor(); 105 Header.Bitcode.MinorVersion = DXILVersion.getMinor().value_or(0); 106 Header.Bitcode.Offset = sizeof(dxbc::BitcodeHeader); 107 Header.Bitcode.Size = SectionSize; 108 if (sys::IsBigEndianHost) 109 Header.swapBytes(); 110 W.write<char>(ArrayRef<char>(reinterpret_cast<char *>(&Header), 111 sizeof(dxbc::ProgramHeader))); 112 } 113 Asm.writeSectionData(W.OS, &Sec); 114 unsigned Size = W.OS.tell() - Start; 115 W.OS.write_zeros(offsetToAlignment(Size, Align(4))); 116 } 117 return 0; 118 } 119