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//===- llvm/MC/MCDXContainerWriter.cpp - DXContainer Writer -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "llvm/MC/MCDXContainerWriter.h"
#include "llvm/BinaryFormat/DXContainer.h"
#include "llvm/MC/MCAssembler.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCSection.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Support/Alignment.h"
using namespace llvm;
MCDXContainerTargetWriter::~MCDXContainerTargetWriter() {}
uint64_t DXContainerObjectWriter::writeObject() {
auto &Asm = *this->Asm;
// Start the file size as the header plus the size of the part offsets.
// Presently DXContainer files usually contain 7-10 parts. Reserving space for
// 16 part offsets gives us a little room for growth.
llvm::SmallVector<uint64_t, 16> PartOffsets;
uint64_t PartOffset = 0;
for (const MCSection &Sec : Asm) {
uint64_t SectionSize = Asm.getSectionAddressSize(Sec);
// Skip empty sections.
if (SectionSize == 0)
continue;
assert(SectionSize < std::numeric_limits<uint32_t>::max() &&
"Section size too large for DXContainer");
PartOffsets.push_back(PartOffset);
PartOffset += sizeof(dxbc::PartHeader) + SectionSize;
PartOffset = alignTo(PartOffset, Align(4ul));
// The DXIL part also writes a program header, so we need to include its
// size when computing the offset for a part after the DXIL part.
if (Sec.getName() == "DXIL")
PartOffset += sizeof(dxbc::ProgramHeader);
}
assert(PartOffset < std::numeric_limits<uint32_t>::max() &&
"Part data too large for DXContainer");
uint64_t PartStart =
sizeof(dxbc::Header) + (PartOffsets.size() * sizeof(uint32_t));
uint64_t FileSize = PartStart + PartOffset;
assert(FileSize < std::numeric_limits<uint32_t>::max() &&
"File size too large for DXContainer");
// Write the header.
W.write<char>({'D', 'X', 'B', 'C'});
// Write 16-bytes of 0's for the hash.
W.OS.write_zeros(16);
// Write 1.0 for file format version.
W.write<uint16_t>(1u);
W.write<uint16_t>(0u);
// Write the file size.
W.write<uint32_t>(static_cast<uint32_t>(FileSize));
// Write the number of parts.
W.write<uint32_t>(static_cast<uint32_t>(PartOffsets.size()));
// Write the offsets for the part headers for each part.
for (uint64_t Offset : PartOffsets)
W.write<uint32_t>(static_cast<uint32_t>(PartStart + Offset));
for (const MCSection &Sec : Asm) {
uint64_t SectionSize = Asm.getSectionAddressSize(Sec);
// Skip empty sections.
if (SectionSize == 0)
continue;
unsigned Start = W.OS.tell();
// Write section header.
W.write<char>(ArrayRef<char>(Sec.getName().data(), 4));
uint64_t PartSize = SectionSize;
if (Sec.getName() == "DXIL")
PartSize += sizeof(dxbc::ProgramHeader);
// DXContainer parts should be 4-byte aligned.
PartSize = alignTo(PartSize, Align(4));
W.write<uint32_t>(static_cast<uint32_t>(PartSize));
if (Sec.getName() == "DXIL") {
dxbc::ProgramHeader Header;
memset(reinterpret_cast<void *>(&Header), 0, sizeof(dxbc::ProgramHeader));
const Triple &TT = getContext().getTargetTriple();
VersionTuple Version = TT.getOSVersion();
uint8_t MajorVersion = static_cast<uint8_t>(Version.getMajor());
uint8_t MinorVersion =
static_cast<uint8_t>(Version.getMinor().value_or(0));
Header.Version =
dxbc::ProgramHeader::getVersion(MajorVersion, MinorVersion);
if (TT.hasEnvironment())
Header.ShaderKind =
static_cast<uint16_t>(TT.getEnvironment() - Triple::Pixel);
// The program header's size field is in 32-bit words.
Header.Size = (SectionSize + sizeof(dxbc::ProgramHeader) + 3) / 4;
memcpy(Header.Bitcode.Magic, "DXIL", 4);
VersionTuple DXILVersion = TT.getDXILVersion();
Header.Bitcode.MajorVersion = DXILVersion.getMajor();
Header.Bitcode.MinorVersion = DXILVersion.getMinor().value_or(0);
Header.Bitcode.Offset = sizeof(dxbc::BitcodeHeader);
Header.Bitcode.Size = SectionSize;
if (sys::IsBigEndianHost)
Header.swapBytes();
W.write<char>(ArrayRef<char>(reinterpret_cast<char *>(&Header),
sizeof(dxbc::ProgramHeader)));
}
Asm.writeSectionData(W.OS, &Sec);
unsigned Size = W.OS.tell() - Start;
W.OS.write_zeros(offsetToAlignment(Size, Align(4)));
}
return 0;
}
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