6024e5c395
clang 20.0.0 (based on r547379) from build 12806354. Bug: http://b/379133546 Test: N/A Change-Id: I2eb8938af55d809de674be63cb30cf27e801862b Upstream-Commit: ad834e67b1105d15ef907f6255d4c96e8e733f57
86 lines
3.3 KiB
C++
86 lines
3.3 KiB
C++
//===- PGOCtxProfWriter.h - Contextual Profile Writer -----------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file declares a utility for writing a contextual profile to bitstream.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_PROFILEDATA_PGOCTXPROFWRITER_H_
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#define LLVM_PROFILEDATA_PGOCTXPROFWRITER_H_
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/Bitstream/BitCodeEnums.h"
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#include "llvm/Bitstream/BitstreamWriter.h"
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#include "llvm/ProfileData/CtxInstrContextNode.h"
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namespace llvm {
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enum PGOCtxProfileRecords { Invalid = 0, Version, Guid, CalleeIndex, Counters };
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enum PGOCtxProfileBlockIDs {
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ProfileMetadataBlockID = bitc::FIRST_APPLICATION_BLOCKID,
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ContextNodeBlockID = ProfileMetadataBlockID + 1
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};
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/// Write one or more ContextNodes to the provided raw_fd_stream.
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/// The caller must destroy the PGOCtxProfileWriter object before closing the
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/// stream.
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/// The design allows serializing a bunch of contexts embedded in some other
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/// file. The overall format is:
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///
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/// [... other data written to the stream...]
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/// SubBlock(ProfileMetadataBlockID)
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/// Version
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/// SubBlock(ContextNodeBlockID)
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/// [RECORDS]
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/// SubBlock(ContextNodeBlockID)
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/// [RECORDS]
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/// [... more SubBlocks]
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/// EndBlock
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/// EndBlock
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///
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/// The "RECORDS" are bitsream records. The IDs are in CtxProfileCodes (except)
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/// for Version, which is just for metadata). All contexts will have Guid and
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/// Counters, and all but the roots have CalleeIndex. The order in which the
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/// records appear does not matter, but they must precede any subcontexts,
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/// because that helps keep the reader code simpler.
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///
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/// Subblock containment captures the context->subcontext relationship. The
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/// "next()" relationship in the raw profile, between call targets of indirect
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/// calls, are just modeled as peer subblocks where the callee index is the
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/// same.
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///
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/// Versioning: the writer may produce additional records not known by the
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/// reader. The version number indicates a more structural change.
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/// The current version, in particular, is set up to expect optional extensions
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/// like value profiling - which would appear as additional records. For
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/// example, value profiling would produce a new record with a new record ID,
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/// containing the profiled values (much like the counters)
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class PGOCtxProfileWriter final {
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BitstreamWriter Writer;
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void writeCounters(const ctx_profile::ContextNode &Node);
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void writeImpl(std::optional<uint32_t> CallerIndex,
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const ctx_profile::ContextNode &Node);
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public:
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PGOCtxProfileWriter(raw_ostream &Out,
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std::optional<unsigned> VersionOverride = std::nullopt);
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~PGOCtxProfileWriter() { Writer.ExitBlock(); }
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void write(const ctx_profile::ContextNode &);
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// constants used in writing which a reader may find useful.
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static constexpr unsigned CodeLen = 2;
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static constexpr uint32_t CurrentVersion = 1;
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static constexpr unsigned VBREncodingBits = 6;
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static constexpr StringRef ContainerMagic = "CTXP";
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};
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} // namespace llvm
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#endif
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