1 //===- AssumptionCache.cpp - Cache finding @llvm.assume calls -------------===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file contains a pass that keeps track of @llvm.assume intrinsics in 11 // the functions of a module. 12 // 13 //===----------------------------------------------------------------------===// 14 15 #include "llvm/Analysis/AssumptionCache.h" 16 #include "llvm/IR/CallSite.h" 17 #include "llvm/IR/Dominators.h" 18 #include "llvm/IR/Function.h" 19 #include "llvm/IR/Instructions.h" 20 #include "llvm/IR/IntrinsicInst.h" 21 #include "llvm/IR/PassManager.h" 22 #include "llvm/IR/PatternMatch.h" 23 #include "llvm/Support/Debug.h" 24 using namespace llvm; 25 using namespace llvm::PatternMatch; 26 27 void AssumptionCache::scanFunction() { 28 assert(!Scanned && "Tried to scan the function twice!"); 29 assert(AssumeHandles.empty() && "Already have assumes when scanning!"); 30 31 // Go through all instructions in all blocks, add all calls to @llvm.assume 32 // to this cache. 33 for (BasicBlock &B : F) 34 for (Instruction &II : B) 35 if (match(&II, m_Intrinsic<Intrinsic::assume>())) 36 AssumeHandles.push_back(&II); 37 38 // Mark the scan as complete. 39 Scanned = true; 40 } 41 42 void AssumptionCache::registerAssumption(CallInst *CI) { 43 assert(match(CI, m_Intrinsic<Intrinsic::assume>()) && 44 "Registered call does not call @llvm.assume"); 45 46 // If we haven't scanned the function yet, just drop this assumption. It will 47 // be found when we scan later. 48 if (!Scanned) 49 return; 50 51 AssumeHandles.push_back(CI); 52 53 #ifndef NDEBUG 54 assert(CI->getParent() && 55 "Cannot register @llvm.assume call not in a basic block"); 56 assert(&F == CI->getParent()->getParent() && 57 "Cannot register @llvm.assume call not in this function"); 58 59 // We expect the number of assumptions to be small, so in an asserts build 60 // check that we don't accumulate duplicates and that all assumptions point 61 // to the same function. 62 SmallPtrSet<Value *, 16> AssumptionSet; 63 for (auto &VH : AssumeHandles) { 64 if (!VH) 65 continue; 66 67 assert(&F == cast<Instruction>(VH)->getParent()->getParent() && 68 "Cached assumption not inside this function!"); 69 assert(match(cast<CallInst>(VH), m_Intrinsic<Intrinsic::assume>()) && 70 "Cached something other than a call to @llvm.assume!"); 71 assert(AssumptionSet.insert(VH).second && 72 "Cache contains multiple copies of a call!"); 73 } 74 #endif 75 } 76 77 char AssumptionAnalysis::PassID; 78 79 PreservedAnalyses AssumptionPrinterPass::run(Function &F, 80 AnalysisManager<Function> *AM) { 81 AssumptionCache &AC = AM->getResult<AssumptionAnalysis>(F); 82 83 OS << "Cached assumptions for function: " << F.getName() << "\n"; 84 for (auto &VH : AC.assumptions()) 85 if (VH) 86 OS << " " << *cast<CallInst>(VH)->getArgOperand(0) << "\n"; 87 88 return PreservedAnalyses::all(); 89 } 90 91 void AssumptionCacheTracker::FunctionCallbackVH::deleted() { 92 auto I = ACT->AssumptionCaches.find_as(cast<Function>(getValPtr())); 93 if (I != ACT->AssumptionCaches.end()) 94 ACT->AssumptionCaches.erase(I); 95 // 'this' now dangles! 96 } 97 98 AssumptionCache &AssumptionCacheTracker::getAssumptionCache(Function &F) { 99 // We probe the function map twice to try and avoid creating a value handle 100 // around the function in common cases. This makes insertion a bit slower, 101 // but if we have to insert we're going to scan the whole function so that 102 // shouldn't matter. 103 auto I = AssumptionCaches.find_as(&F); 104 if (I != AssumptionCaches.end()) 105 return *I->second; 106 107 // Ok, build a new cache by scanning the function, insert it and the value 108 // handle into our map, and return the newly populated cache. 109 auto IP = AssumptionCaches.insert(std::make_pair( 110 FunctionCallbackVH(&F, this), llvm::make_unique<AssumptionCache>(F))); 111 assert(IP.second && "Scanning function already in the map?"); 112 return *IP.first->second; 113 } 114 115 void AssumptionCacheTracker::verifyAnalysis() const { 116 #ifndef NDEBUG 117 SmallPtrSet<const CallInst *, 4> AssumptionSet; 118 for (const auto &I : AssumptionCaches) { 119 for (auto &VH : I.second->assumptions()) 120 if (VH) 121 AssumptionSet.insert(cast<CallInst>(VH)); 122 123 for (const BasicBlock &B : cast<Function>(*I.first)) 124 for (const Instruction &II : B) 125 if (match(&II, m_Intrinsic<Intrinsic::assume>())) 126 assert(AssumptionSet.count(cast<CallInst>(&II)) && 127 "Assumption in scanned function not in cache"); 128 } 129 #endif 130 } 131 132 AssumptionCacheTracker::AssumptionCacheTracker() : ImmutablePass(ID) { 133 initializeAssumptionCacheTrackerPass(*PassRegistry::getPassRegistry()); 134 } 135 136 AssumptionCacheTracker::~AssumptionCacheTracker() {} 137 138 INITIALIZE_PASS(AssumptionCacheTracker, "assumption-cache-tracker", 139 "Assumption Cache Tracker", false, true) 140 char AssumptionCacheTracker::ID = 0; 141
