llvm/lib/Analysis/ReplayInlineAdvisor.cpp

   1 //===- ReplayInlineAdvisor.cpp - Replay InlineAdvisor ---------------------===//
   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 // This file implements ReplayInlineAdvisor that replays inline decisions based
  10 // on previous inline remarks from optimization remark log. This is a best
  11 // effort approach useful for testing compiler/source changes while holding
  12 // inlining steady.
  13 //
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "llvm/Analysis/ReplayInlineAdvisor.h"
  17 #include "llvm/IR/DebugInfoMetadata.h"
  18 #include "llvm/IR/Instructions.h"
  19 #include "llvm/Support/LineIterator.h"
  20
  21 using namespace llvm;
  22
  23 #define DEBUG_TYPE "inline-replay"
  24
  25 ReplayInlineAdvisor::ReplayInlineAdvisor(
  26     Module &M, FunctionAnalysisManager &FAM, LLVMContext &Context,
  27     std::unique_ptr<InlineAdvisor> OriginalAdvisor, StringRef RemarksFile,
  28     bool EmitRemarks)
  29     : InlineAdvisor(M, FAM), OriginalAdvisor(std::move(OriginalAdvisor)),
  30       HasReplayRemarks(false), EmitRemarks(EmitRemarks) {
  31   auto BufferOrErr = MemoryBuffer::getFileOrSTDIN(RemarksFile);
  32   std::error_code EC = BufferOrErr.getError();
  33   if (EC) {
  34     Context.emitError("Could not open remarks file: " + EC.message());
  35     return;
  36   }
  37
  38   // Example for inline remarks to parse:
  39   //   main:3:1.1: '_Z3subii' inlined into 'main' at callsite sum:1 @ main:3:1.1
  40   // We use the callsite string after `at callsite` to replay inlining.
  41   line_iterator LineIt(*BufferOrErr.get(), /*SkipBlanks=*/true);
  42   for (; !LineIt.is_at_eof(); ++LineIt) {
  43     StringRef Line = *LineIt;
  44     auto Pair = Line.split(" at callsite ");
  45
  46     StringRef Callee = Pair.first.split(" inlined into")
  47                            .first.rsplit(": '")
  48                            .second.drop_back();
  49     auto CallSite = Pair.second.split(";").first;
  50
  51     if (Callee.empty() || CallSite.empty())
  52       continue;
  53
  54     std::string Combined = (Callee + CallSite).str();
  55     InlineSitesFromRemarks.insert(Combined);
  56   }
  57
  58   HasReplayRemarks = true;
  59 }
  60
  61 std::unique_ptr<InlineAdvice> ReplayInlineAdvisor::getAdviceImpl(CallBase &CB) {
  62   assert(HasReplayRemarks);
  63
  64   Function &Caller = *CB.getCaller();
  65   auto &ORE = FAM.getResult<OptimizationRemarkEmitterAnalysis>(Caller);
  66
  67   if (InlineSitesFromRemarks.empty())
  68     return std::make_unique<DefaultInlineAdvice>(this, CB, None, ORE,
  69                                                  EmitRemarks);
  70
  71   std::string CallSiteLoc = getCallSiteLocation(CB.getDebugLoc());
  72   StringRef Callee = CB.getCalledFunction()->getName();
  73   std::string Combined = (Callee + CallSiteLoc).str();
  74   auto Iter = InlineSitesFromRemarks.find(Combined);
  75
  76   Optional<InlineCost> InlineRecommended = None;
  77   if (Iter != InlineSitesFromRemarks.end()) {
  78     InlineRecommended = llvm::InlineCost::getAlways("found in replay");
  79   }
  80
  81   return std::make_unique<DefaultInlineAdvice>(this, CB, InlineRecommended, ORE,
  82                                                EmitRemarks);
  83 }