llvm/llvm/include/llvm/ProfileData/PGOCtxProfWriter.h

//===- PGOCtxProfWriter.h - Contextual Profile 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
//
//===----------------------------------------------------------------------===//
//
// This file declares a utility for writing a contextual profile to bitstream.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_PROFILEDATA_PGOCTXPROFWRITER_H_
#define LLVM_PROFILEDATA_PGOCTXPROFWRITER_H_

#include "llvm/ADT/StringExtras.h"
#include "llvm/Bitstream/BitCodeEnums.h"
#include "llvm/Bitstream/BitstreamWriter.h"
#include "llvm/ProfileData/CtxInstrContextNode.h"

namespace llvm {
enum PGOCtxProfileRecords { … };

enum PGOCtxProfileBlockIDs { … };

/// Write one or more ContextNodes to the provided raw_fd_stream.
/// The caller must destroy the PGOCtxProfileWriter object before closing the
/// stream.
/// The design allows serializing a bunch of contexts embedded in some other
/// file. The overall format is:
///
///  [... other data written to the stream...]
///  SubBlock(ProfileMetadataBlockID)
///   Version
///   SubBlock(ContextNodeBlockID)
///     [RECORDS]
///     SubBlock(ContextNodeBlockID)
///       [RECORDS]
///       [... more SubBlocks]
///     EndBlock
///   EndBlock
///
/// The "RECORDS" are bitsream records. The IDs are in CtxProfileCodes (except)
/// for Version, which is just for metadata). All contexts will have Guid and
/// Counters, and all but the roots have CalleeIndex. The order in which the
/// records appear does not matter, but they must precede any subcontexts,
/// because that helps keep the reader code simpler.
///
/// Subblock containment captures the context->subcontext relationship. The
/// "next()" relationship in the raw profile, between call targets of indirect
/// calls, are just modeled as peer subblocks where the callee index is the
/// same.
///
/// Versioning: the writer may produce additional records not known by the
/// reader. The version number indicates a more structural change.
/// The current version, in particular, is set up to expect optional extensions
/// like value profiling - which would appear as additional records. For
/// example, value profiling would produce a new record with a new record ID,
/// containing the profiled values (much like the counters)
class PGOCtxProfileWriter final { … };

Error createCtxProfFromJSON(StringRef Profile, raw_ostream &Out);
} // namespace llvm
#endif