llvm/lib/ProfileData/PGOCtxProfWriter.cpp

   1 //===- PGOCtxProfWriter.cpp - Contextual Instrumentation profile writer ---===//
   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-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // Write a contextual profile to bitstream.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/ProfileData/PGOCtxProfWriter.h"
  14 #include "llvm/Bitstream/BitCodeEnums.h"
  15
  16 using namespace llvm;
  17 using namespace llvm::ctx_profile;
  18
  19 void PGOCtxProfileWriter::writeCounters(const ContextNode &Node) {
  20   Writer.EmitCode(bitc::UNABBREV_RECORD);
  21   Writer.EmitVBR(PGOCtxProfileRecords::Counters, VBREncodingBits);
  22   Writer.EmitVBR(Node.counters_size(), VBREncodingBits);
  23   for (uint32_t I = 0U; I < Node.counters_size(); ++I)
  24     Writer.EmitVBR64(Node.counters()[I], VBREncodingBits);
  25 }
  26
  27 // recursively write all the subcontexts. We do need to traverse depth first to
  28 // model the context->subcontext implicitly, and since this captures call
  29 // stacks, we don't really need to be worried about stack overflow and we can
  30 // keep the implementation simple.
  31 void PGOCtxProfileWriter::writeImpl(std::optional<uint32_t> CallerIndex,
  32                                     const ContextNode &Node) {
  33   Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextNodeBlockID, CodeLen);
  34   Writer.EmitRecord(PGOCtxProfileRecords::Guid,
  35                     SmallVector<uint64_t, 1>{Node.guid()});
  36   if (CallerIndex)
  37     Writer.EmitRecord(PGOCtxProfileRecords::CalleeIndex,
  38                       SmallVector<uint64_t, 1>{*CallerIndex});
  39   writeCounters(Node);
  40   for (uint32_t I = 0U; I < Node.callsites_size(); ++I)
  41     for (const auto *Subcontext = Node.subContexts()[I]; Subcontext;
  42          Subcontext = Subcontext->next())
  43       writeImpl(I, *Subcontext);
  44   Writer.ExitBlock();
  45 }
  46
  47 void PGOCtxProfileWriter::write(const ContextNode &RootNode) {
  48   writeImpl(std::nullopt, RootNode);
  49 }