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" 24using namespace llvm; 25using namespace llvm::PatternMatch; 26 27void 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 42void 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 77char AssumptionAnalysis::PassID; 78 79PreservedAnalyses 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 91void 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 98AssumptionCache &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 115void 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 132AssumptionCacheTracker::AssumptionCacheTracker() : ImmutablePass(ID) { 133 initializeAssumptionCacheTrackerPass(*PassRegistry::getPassRegistry()); 134} 135 136AssumptionCacheTracker::~AssumptionCacheTracker() {} 137 138INITIALIZE_PASS(AssumptionCacheTracker, "assumption-cache-tracker", 139 "Assumption Cache Tracker", false, true) 140char AssumptionCacheTracker::ID = 0; 141