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//===- CodeGenDataReader.cpp ----------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains support for reading codegen data.
//
//===----------------------------------------------------------------------===//
#include "llvm/CGData/CodeGenDataReader.h"
#include "llvm/CGData/OutlinedHashTreeRecord.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MemoryBuffer.h"
#define DEBUG_TYPE "cg-data-reader"
using namespace llvm;
static cl::opt<bool> IndexedCodeGenDataReadFunctionMapNames(
"indexed-codegen-data-read-function-map-names", cl::init(true), cl::Hidden,
cl::desc("Read function map names in indexed CodeGenData. Can be "
"disabled to save memory and time for final consumption of the "
"indexed CodeGenData in production."));
namespace llvm {
static Expected<std::unique_ptr<MemoryBuffer>>
setupMemoryBuffer(const Twine &Filename, vfs::FileSystem &FS) {
auto BufferOrErr = Filename.str() == "-" ? MemoryBuffer::getSTDIN()
: FS.getBufferForFile(Filename);
if (std::error_code EC = BufferOrErr.getError())
return errorCodeToError(EC);
return std::move(BufferOrErr.get());
}
Error CodeGenDataReader::mergeFromObjectFile(
const object::ObjectFile *Obj, OutlinedHashTreeRecord &GlobalOutlineRecord,
StableFunctionMapRecord &GlobalFunctionMapRecord,
stable_hash *CombinedHash) {
Triple TT = Obj->makeTriple();
auto CGOutlineName =
getCodeGenDataSectionName(CG_outline, TT.getObjectFormat(), false);
auto CGMergeName =
getCodeGenDataSectionName(CG_merge, TT.getObjectFormat(), false);
auto processSectionContents = [&](const StringRef &Name,
const StringRef &Contents) {
if (Name != CGOutlineName && Name != CGMergeName)
return;
if (CombinedHash)
*CombinedHash = stable_hash_combine(*CombinedHash, xxh3_64bits(Contents));
auto *Data = reinterpret_cast<const unsigned char *>(Contents.data());
auto *EndData = Data + Contents.size();
// In case dealing with an executable that has concatenated cgdata,
// we want to merge them into a single cgdata.
// Although it's not a typical workflow, we support this scenario
// by looping over all data in the sections.
if (Name == CGOutlineName) {
while (Data != EndData) {
OutlinedHashTreeRecord LocalOutlineRecord;
LocalOutlineRecord.deserialize(Data);
GlobalOutlineRecord.merge(LocalOutlineRecord);
}
} else if (Name == CGMergeName) {
while (Data != EndData) {
StableFunctionMapRecord LocalFunctionMapRecord;
LocalFunctionMapRecord.deserialize(Data);
GlobalFunctionMapRecord.merge(LocalFunctionMapRecord);
}
}
};
for (auto &Section : Obj->sections()) {
Expected<StringRef> NameOrErr = Section.getName();
if (!NameOrErr)
return NameOrErr.takeError();
Expected<StringRef> ContentsOrErr = Section.getContents();
if (!ContentsOrErr)
return ContentsOrErr.takeError();
processSectionContents(*NameOrErr, *ContentsOrErr);
}
return Error::success();
}
Error IndexedCodeGenDataReader::read() {
using namespace support;
// The smallest header with the version 1 is 24 bytes.
// Do not update this value even with the new version of the header.
const unsigned MinHeaderSize = 24;
if (DataBuffer->getBufferSize() < MinHeaderSize)
return error(cgdata_error::bad_header);
auto *Start =
reinterpret_cast<const unsigned char *>(DataBuffer->getBufferStart());
auto *End =
reinterpret_cast<const unsigned char *>(DataBuffer->getBufferEnd());
if (auto E = IndexedCGData::Header::readFromBuffer(Start).moveInto(Header))
return E;
if (hasOutlinedHashTree()) {
const unsigned char *Ptr = Start + Header.OutlinedHashTreeOffset;
if (Ptr >= End)
return error(cgdata_error::eof);
HashTreeRecord.deserialize(Ptr);
}
if (hasStableFunctionMap()) {
const unsigned char *Ptr = Start + Header.StableFunctionMapOffset;
if (Ptr >= End)
return error(cgdata_error::eof);
FunctionMapRecord.deserialize(Ptr, IndexedCodeGenDataReadFunctionMapNames);
}
return success();
}
Expected<std::unique_ptr<CodeGenDataReader>>
CodeGenDataReader::create(const Twine &Path, vfs::FileSystem &FS) {
// Set up the buffer to read.
auto BufferOrError = setupMemoryBuffer(Path, FS);
if (Error E = BufferOrError.takeError())
return std::move(E);
return CodeGenDataReader::create(std::move(BufferOrError.get()));
}
Expected<std::unique_ptr<CodeGenDataReader>>
CodeGenDataReader::create(std::unique_ptr<MemoryBuffer> Buffer) {
if (Buffer->getBufferSize() == 0)
return make_error<CGDataError>(cgdata_error::empty_cgdata);
std::unique_ptr<CodeGenDataReader> Reader;
// Create the reader.
if (IndexedCodeGenDataReader::hasFormat(*Buffer))
Reader = std::make_unique<IndexedCodeGenDataReader>(std::move(Buffer));
else if (TextCodeGenDataReader::hasFormat(*Buffer))
Reader = std::make_unique<TextCodeGenDataReader>(std::move(Buffer));
else
return make_error<CGDataError>(cgdata_error::malformed);
// Initialize the reader and return the result.
if (Error E = Reader->read())
return std::move(E);
return std::move(Reader);
}
bool IndexedCodeGenDataReader::hasFormat(const MemoryBuffer &DataBuffer) {
using namespace support;
if (DataBuffer.getBufferSize() < sizeof(IndexedCGData::Magic))
return false;
uint64_t Magic = endian::read<uint64_t, llvm::endianness::little, aligned>(
DataBuffer.getBufferStart());
// Verify that it's magical.
return Magic == IndexedCGData::Magic;
}
bool TextCodeGenDataReader::hasFormat(const MemoryBuffer &Buffer) {
// Verify that this really looks like plain ASCII text by checking a
// 'reasonable' number of characters (up to the magic size).
StringRef Prefix = Buffer.getBuffer().take_front(sizeof(uint64_t));
return llvm::all_of(Prefix, [](char c) { return isPrint(c) || isSpace(c); });
}
Error TextCodeGenDataReader::read() {
using namespace support;
// Parse the custom header line by line.
for (; !Line.is_at_eof(); ++Line) {
// Skip empty or whitespace-only lines
if (Line->trim().empty())
continue;
if (!Line->starts_with(":"))
break;
StringRef Str = Line->drop_front().rtrim();
if (Str.equals_insensitive("outlined_hash_tree"))
DataKind |= CGDataKind::FunctionOutlinedHashTree;
else if (Str.equals_insensitive("stable_function_map"))
DataKind |= CGDataKind::StableFunctionMergingMap;
else
return error(cgdata_error::bad_header);
}
// We treat an empty header (that is a comment # only) as a valid header.
if (Line.is_at_eof()) {
if (DataKind == CGDataKind::Unknown)
return Error::success();
return error(cgdata_error::bad_header);
}
// The YAML docs follow after the header.
const char *Pos = Line->data();
size_t Size = reinterpret_cast<size_t>(DataBuffer->getBufferEnd()) -
reinterpret_cast<size_t>(Pos);
yaml::Input YOS(StringRef(Pos, Size));
if (hasOutlinedHashTree())
HashTreeRecord.deserializeYAML(YOS);
if (hasStableFunctionMap())
FunctionMapRecord.deserializeYAML(YOS);
return Error::success();
}
} // end namespace llvm
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