120 lines · cpp
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-exception6//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 21uint64_t DXContainerObjectWriter::writeObject() {22 auto &Asm = *this->Asm;23 // Start the file size as the header plus the size of the part offsets.24 // Presently DXContainer files usually contain 7-10 parts. Reserving space for25 // 16 part offsets gives us a little room for growth.26 llvm::SmallVector<uint64_t, 16> PartOffsets;27 uint64_t PartOffset = 0;28 for (const MCSection &Sec : Asm) {29 uint64_t SectionSize = Asm.getSectionAddressSize(Sec);30 // Skip empty sections.31 if (SectionSize == 0)32 continue;33 34 assert(SectionSize < std::numeric_limits<uint32_t>::max() &&35 "Section size too large for DXContainer");36 37 PartOffsets.push_back(PartOffset);38 PartOffset += sizeof(dxbc::PartHeader) + SectionSize;39 PartOffset = alignTo(PartOffset, Align(4ul));40 // The DXIL part also writes a program header, so we need to include its41 // size when computing the offset for a part after the DXIL part.42 if (Sec.getName() == "DXIL")43 PartOffset += sizeof(dxbc::ProgramHeader);44 }45 assert(PartOffset < std::numeric_limits<uint32_t>::max() &&46 "Part data too large for DXContainer");47 48 uint64_t PartStart =49 sizeof(dxbc::Header) + (PartOffsets.size() * sizeof(uint32_t));50 uint64_t FileSize = PartStart + PartOffset;51 assert(FileSize < std::numeric_limits<uint32_t>::max() &&52 "File size too large for DXContainer");53 54 // Write the header.55 W.write<char>({'D', 'X', 'B', 'C'});56 // Write 16-bytes of 0's for the hash.57 W.OS.write_zeros(16);58 // Write 1.0 for file format version.59 W.write<uint16_t>(1u);60 W.write<uint16_t>(0u);61 // Write the file size.62 W.write<uint32_t>(static_cast<uint32_t>(FileSize));63 // Write the number of parts.64 W.write<uint32_t>(static_cast<uint32_t>(PartOffsets.size()));65 // Write the offsets for the part headers for each part.66 for (uint64_t Offset : PartOffsets)67 W.write<uint32_t>(static_cast<uint32_t>(PartStart + Offset));68 69 for (const MCSection &Sec : Asm) {70 uint64_t SectionSize = Asm.getSectionAddressSize(Sec);71 // Skip empty sections.72 if (SectionSize == 0)73 continue;74 75 unsigned Start = W.OS.tell();76 // Write section header.77 W.write<char>(ArrayRef<char>(Sec.getName().data(), 4));78 79 uint64_t PartSize = SectionSize;80 81 if (Sec.getName() == "DXIL")82 PartSize += sizeof(dxbc::ProgramHeader);83 // DXContainer parts should be 4-byte aligned.84 PartSize = alignTo(PartSize, Align(4));85 W.write<uint32_t>(static_cast<uint32_t>(PartSize));86 if (Sec.getName() == "DXIL") {87 dxbc::ProgramHeader Header;88 memset(reinterpret_cast<void *>(&Header), 0, sizeof(dxbc::ProgramHeader));89 90 const Triple &TT = getContext().getTargetTriple();91 VersionTuple Version = TT.getOSVersion();92 uint8_t MajorVersion = static_cast<uint8_t>(Version.getMajor());93 uint8_t MinorVersion =94 static_cast<uint8_t>(Version.getMinor().value_or(0));95 Header.Version =96 dxbc::ProgramHeader::getVersion(MajorVersion, MinorVersion);97 if (TT.hasEnvironment())98 Header.ShaderKind =99 static_cast<uint16_t>(TT.getEnvironment() - Triple::Pixel);100 101 // The program header's size field is in 32-bit words.102 Header.Size = (SectionSize + sizeof(dxbc::ProgramHeader) + 3) / 4;103 memcpy(Header.Bitcode.Magic, "DXIL", 4);104 VersionTuple DXILVersion = TT.getDXILVersion();105 Header.Bitcode.MajorVersion = DXILVersion.getMajor();106 Header.Bitcode.MinorVersion = DXILVersion.getMinor().value_or(0);107 Header.Bitcode.Offset = sizeof(dxbc::BitcodeHeader);108 Header.Bitcode.Size = SectionSize;109 if (sys::IsBigEndianHost)110 Header.swapBytes();111 W.write<char>(ArrayRef<char>(reinterpret_cast<char *>(&Header),112 sizeof(dxbc::ProgramHeader)));113 }114 Asm.writeSectionData(W.OS, &Sec);115 unsigned Size = W.OS.tell() - Start;116 W.OS.write_zeros(offsetToAlignment(Size, Align(4)));117 }118 return 0;119}120