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/Analysis/OptimizationRemarkEmitter.h" 18 #include "llvm/Support/LineIterator.h" 19 #include "llvm/Support/MemoryBuffer.h" 20 #include <memory> 21 22 using namespace llvm; 23 24 #define DEBUG_TYPE "replay-inline" 25 26 ReplayInlineAdvisor::ReplayInlineAdvisor( 27 Module &M, FunctionAnalysisManager &FAM, LLVMContext &Context, 28 std::unique_ptr<InlineAdvisor> OriginalAdvisor, 29 const ReplayInlinerSettings &ReplaySettings, bool EmitRemarks, 30 InlineContext IC) 31 : InlineAdvisor(M, FAM, IC), OriginalAdvisor(std::move(OriginalAdvisor)), 32 ReplaySettings(ReplaySettings), EmitRemarks(EmitRemarks) { 33 34 auto BufferOrErr = MemoryBuffer::getFileOrSTDIN(ReplaySettings.ReplayFile); 35 std::error_code EC = BufferOrErr.getError(); 36 if (EC) { 37 Context.emitError("Could not open remarks file: " + EC.message()); 38 return; 39 } 40 41 // Example for inline remarks to parse: 42 // main:3:1.1: '_Z3subii' inlined into 'main' at callsite sum:1 @ 43 // main:3:1.1; 44 // We use the callsite string after `at callsite` to replay inlining. 45 line_iterator LineIt(*BufferOrErr.get(), /*SkipBlanks=*/true); 46 const std::string PositiveRemark = "' inlined into '"; 47 const std::string NegativeRemark = "' will not be inlined into '"; 48 49 for (; !LineIt.is_at_eof(); ++LineIt) { 50 StringRef Line = *LineIt; 51 auto Pair = Line.split(" at callsite "); 52 53 bool IsPositiveRemark = true; 54 if (Pair.first.contains(NegativeRemark)) 55 IsPositiveRemark = false; 56 57 auto CalleeCaller = 58 Pair.first.split(IsPositiveRemark ? PositiveRemark : NegativeRemark); 59 60 StringRef Callee = CalleeCaller.first.rsplit(": '").second; 61 StringRef Caller = CalleeCaller.second.rsplit("'").first; 62 63 auto CallSite = Pair.second.split(";").first; 64 65 if (Callee.empty() || Caller.empty() || CallSite.empty()) { 66 Context.emitError("Invalid remark format: " + Line); 67 return; 68 } 69 70 std::string Combined = (Callee + CallSite).str(); 71 InlineSitesFromRemarks[Combined] = IsPositiveRemark; 72 if (ReplaySettings.ReplayScope == ReplayInlinerSettings::Scope::Function) 73 CallersToReplay.insert(Caller); 74 } 75 76 HasReplayRemarks = true; 77 } 78 79 std::unique_ptr<InlineAdvisor> 80 llvm::getReplayInlineAdvisor(Module &M, FunctionAnalysisManager &FAM, 81 LLVMContext &Context, 82 std::unique_ptr<InlineAdvisor> OriginalAdvisor, 83 const ReplayInlinerSettings &ReplaySettings, 84 bool EmitRemarks, InlineContext IC) { 85 auto Advisor = std::make_unique<ReplayInlineAdvisor>( 86 M, FAM, Context, std::move(OriginalAdvisor), ReplaySettings, EmitRemarks, 87 IC); 88 if (!Advisor->areReplayRemarksLoaded()) 89 Advisor.reset(); 90 return Advisor; 91 } 92 93 std::unique_ptr<InlineAdvice> ReplayInlineAdvisor::getAdviceImpl(CallBase &CB) { 94 assert(HasReplayRemarks); 95 96 Function &Caller = *CB.getCaller(); 97 auto &ORE = FAM.getResult<OptimizationRemarkEmitterAnalysis>(Caller); 98 99 // Decision not made by replay system 100 if (!hasInlineAdvice(*CB.getFunction())) { 101 // If there's a registered original advisor, return its decision 102 if (OriginalAdvisor) 103 return OriginalAdvisor->getAdvice(CB); 104 105 // If no decision is made above, return non-decision 106 return {}; 107 } 108 109 std::string CallSiteLoc = 110 formatCallSiteLocation(CB.getDebugLoc(), ReplaySettings.ReplayFormat); 111 StringRef Callee = CB.getCalledFunction()->getName(); 112 std::string Combined = (Callee + CallSiteLoc).str(); 113 114 // Replay decision, if it has one 115 auto Iter = InlineSitesFromRemarks.find(Combined); 116 if (Iter != InlineSitesFromRemarks.end()) { 117 if (InlineSitesFromRemarks[Combined]) { 118 LLVM_DEBUG(dbgs() << "Replay Inliner: Inlined " << Callee << " @ " 119 << CallSiteLoc << "\n"); 120 return std::make_unique<DefaultInlineAdvice>( 121 this, CB, llvm::InlineCost::getAlways("previously inlined"), ORE, 122 EmitRemarks); 123 } else { 124 LLVM_DEBUG(dbgs() << "Replay Inliner: Not Inlined " << Callee << " @ " 125 << CallSiteLoc << "\n"); 126 // A negative inline is conveyed by "None" std::optional<InlineCost> 127 return std::make_unique<DefaultInlineAdvice>(this, CB, std::nullopt, ORE, 128 EmitRemarks); 129 } 130 } 131 132 // Fallback decisions 133 if (ReplaySettings.ReplayFallback == 134 ReplayInlinerSettings::Fallback::AlwaysInline) 135 return std::make_unique<DefaultInlineAdvice>( 136 this, CB, llvm::InlineCost::getAlways("AlwaysInline Fallback"), ORE, 137 EmitRemarks); 138 else if (ReplaySettings.ReplayFallback == 139 ReplayInlinerSettings::Fallback::NeverInline) 140 // A negative inline is conveyed by "None" std::optional<InlineCost> 141 return std::make_unique<DefaultInlineAdvice>(this, CB, std::nullopt, ORE, 142 EmitRemarks); 143 else { 144 assert(ReplaySettings.ReplayFallback == 145 ReplayInlinerSettings::Fallback::Original); 146 // If there's a registered original advisor, return its decision 147 if (OriginalAdvisor) 148 return OriginalAdvisor->getAdvice(CB); 149 } 150 151 // If no decision is made above, return non-decision 152 return {}; 153 } 154