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diff --git a/llvm/lib/Analysis/AssumptionCache.cpp b/llvm/lib/Analysis/AssumptionCache.cpp
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+//===- AssumptionCache.cpp - Cache finding @llvm.assume calls -------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains a pass that keeps track of @llvm.assume intrinsics in
+// the functions of a module.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Analysis/AssumptionCache.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/InstrTypes.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Pass.h"
+#include "llvm/Support/Casting.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include <algorithm>
+#include <cassert>
+#include <utility>
+
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+static cl::opt<bool>
+    VerifyAssumptionCache("verify-assumption-cache", cl::Hidden,
+                          cl::desc("Enable verification of assumption cache"),
+                          cl::init(false));
+
+SmallVector<WeakTrackingVH, 1> &
+AssumptionCache::getOrInsertAffectedValues(Value *V) {
+  // Try using find_as first to avoid creating extra value handles just for the
+  // purpose of doing the lookup.
+  auto AVI = AffectedValues.find_as(V);
+  if (AVI != AffectedValues.end())
+    return AVI->second;
+
+  auto AVIP = AffectedValues.insert(
+      {AffectedValueCallbackVH(V, this), SmallVector<WeakTrackingVH, 1>()});
+  return AVIP.first->second;
+}
+
+static void findAffectedValues(CallInst *CI,
+                               SmallVectorImpl<Value *> &Affected) {
+  // Note: This code must be kept in-sync with the code in
+  // computeKnownBitsFromAssume in ValueTracking.
+
+  auto AddAffected = [&Affected](Value *V) {
+    if (isa<Argument>(V)) {
+      Affected.push_back(V);
+    } else if (auto *I = dyn_cast<Instruction>(V)) {
+      Affected.push_back(I);
+
+      // Peek through unary operators to find the source of the condition.
+      Value *Op;
+      if (match(I, m_BitCast(m_Value(Op))) ||
+          match(I, m_PtrToInt(m_Value(Op))) ||
+          match(I, m_Not(m_Value(Op)))) {
+        if (isa<Instruction>(Op) || isa<Argument>(Op))
+          Affected.push_back(Op);
+      }
+    }
+  };
+
+  Value *Cond = CI->getArgOperand(0), *A, *B;
+  AddAffected(Cond);
+
+  CmpInst::Predicate Pred;
+  if (match(Cond, m_ICmp(Pred, m_Value(A), m_Value(B)))) {
+    AddAffected(A);
+    AddAffected(B);
+
+    if (Pred == ICmpInst::ICMP_EQ) {
+      // For equality comparisons, we handle the case of bit inversion.
+      auto AddAffectedFromEq = [&AddAffected](Value *V) {
+        Value *A;
+        if (match(V, m_Not(m_Value(A)))) {
+          AddAffected(A);
+          V = A;
+        }
+
+        Value *B;
+        ConstantInt *C;
+        // (A & B) or (A | B) or (A ^ B).
+        if (match(V, m_BitwiseLogic(m_Value(A), m_Value(B)))) {
+          AddAffected(A);
+          AddAffected(B);
+        // (A << C) or (A >>_s C) or (A >>_u C) where C is some constant.
+        } else if (match(V, m_Shift(m_Value(A), m_ConstantInt(C)))) {
+          AddAffected(A);
+        }
+      };
+
+      AddAffectedFromEq(A);
+      AddAffectedFromEq(B);
+    }
+  }
+}
+
+void AssumptionCache::updateAffectedValues(CallInst *CI) {
+  SmallVector<Value *, 16> Affected;
+  findAffectedValues(CI, Affected);
+
+  for (auto &AV : Affected) {
+    auto &AVV = getOrInsertAffectedValues(AV);
+    if (std::find(AVV.begin(), AVV.end(), CI) == AVV.end())
+      AVV.push_back(CI);
+  }
+}
+
+void AssumptionCache::unregisterAssumption(CallInst *CI) {
+  SmallVector<Value *, 16> Affected;
+  findAffectedValues(CI, Affected);
+
+  for (auto &AV : Affected) {
+    auto AVI = AffectedValues.find_as(AV);
+    if (AVI != AffectedValues.end())
+      AffectedValues.erase(AVI);
+  }
+
+  AssumeHandles.erase(
+      remove_if(AssumeHandles, [CI](WeakTrackingVH &VH) { return CI == VH; }),
+      AssumeHandles.end());
+}
+
+void AssumptionCache::AffectedValueCallbackVH::deleted() {
+  auto AVI = AC->AffectedValues.find(getValPtr());
+  if (AVI != AC->AffectedValues.end())
+    AC->AffectedValues.erase(AVI);
+  // 'this' now dangles!
+}
+
+void AssumptionCache::transferAffectedValuesInCache(Value *OV, Value *NV) {
+  auto &NAVV = getOrInsertAffectedValues(NV);
+  auto AVI = AffectedValues.find(OV);
+  if (AVI == AffectedValues.end())
+    return;
+
+  for (auto &A : AVI->second)
+    if (std::find(NAVV.begin(), NAVV.end(), A) == NAVV.end())
+      NAVV.push_back(A);
+  AffectedValues.erase(OV);
+}
+
+void AssumptionCache::AffectedValueCallbackVH::allUsesReplacedWith(Value *NV) {
+  if (!isa<Instruction>(NV) && !isa<Argument>(NV))
+    return;
+
+  // Any assumptions that affected this value now affect the new value.
+
+  AC->transferAffectedValuesInCache(getValPtr(), NV);
+  // 'this' now might dangle! If the AffectedValues map was resized to add an
+  // entry for NV then this object might have been destroyed in favor of some
+  // copy in the grown map.
+}
+
+void AssumptionCache::scanFunction() {
+  assert(!Scanned && "Tried to scan the function twice!");
+  assert(AssumeHandles.empty() && "Already have assumes when scanning!");
+
+  // Go through all instructions in all blocks, add all calls to @llvm.assume
+  // to this cache.
+  for (BasicBlock &B : F)
+    for (Instruction &II : B)
+      if (match(&II, m_Intrinsic<Intrinsic::assume>()))
+        AssumeHandles.push_back(&II);
+
+  // Mark the scan as complete.
+  Scanned = true;
+
+  // Update affected values.
+  for (auto &A : AssumeHandles)
+    updateAffectedValues(cast<CallInst>(A));
+}
+
+void AssumptionCache::registerAssumption(CallInst *CI) {
+  assert(match(CI, m_Intrinsic<Intrinsic::assume>()) &&
+         "Registered call does not call @llvm.assume");
+
+  // If we haven't scanned the function yet, just drop this assumption. It will
+  // be found when we scan later.
+  if (!Scanned)
+    return;
+
+  AssumeHandles.push_back(CI);
+
+#ifndef NDEBUG
+  assert(CI->getParent() &&
+         "Cannot register @llvm.assume call not in a basic block");
+  assert(&F == CI->getParent()->getParent() &&
+         "Cannot register @llvm.assume call not in this function");
+
+  // We expect the number of assumptions to be small, so in an asserts build
+  // check that we don't accumulate duplicates and that all assumptions point
+  // to the same function.
+  SmallPtrSet<Value *, 16> AssumptionSet;
+  for (auto &VH : AssumeHandles) {
+    if (!VH)
+      continue;
+
+    assert(&F == cast<Instruction>(VH)->getParent()->getParent() &&
+           "Cached assumption not inside this function!");
+    assert(match(cast<CallInst>(VH), m_Intrinsic<Intrinsic::assume>()) &&
+           "Cached something other than a call to @llvm.assume!");
+    assert(AssumptionSet.insert(VH).second &&
+           "Cache contains multiple copies of a call!");
+  }
+#endif
+
+  updateAffectedValues(CI);
+}
+
+AnalysisKey AssumptionAnalysis::Key;
+
+PreservedAnalyses AssumptionPrinterPass::run(Function &F,
+                                             FunctionAnalysisManager &AM) {
+  AssumptionCache &AC = AM.getResult<AssumptionAnalysis>(F);
+
+  OS << "Cached assumptions for function: " << F.getName() << "\n";
+  for (auto &VH : AC.assumptions())
+    if (VH)
+      OS << "  " << *cast<CallInst>(VH)->getArgOperand(0) << "\n";
+
+  return PreservedAnalyses::all();
+}
+
+void AssumptionCacheTracker::FunctionCallbackVH::deleted() {
+  auto I = ACT->AssumptionCaches.find_as(cast<Function>(getValPtr()));
+  if (I != ACT->AssumptionCaches.end())
+    ACT->AssumptionCaches.erase(I);
+  // 'this' now dangles!
+}
+
+AssumptionCache &AssumptionCacheTracker::getAssumptionCache(Function &F) {
+  // We probe the function map twice to try and avoid creating a value handle
+  // around the function in common cases. This makes insertion a bit slower,
+  // but if we have to insert we're going to scan the whole function so that
+  // shouldn't matter.
+  auto I = AssumptionCaches.find_as(&F);
+  if (I != AssumptionCaches.end())
+    return *I->second;
+
+  // Ok, build a new cache by scanning the function, insert it and the value
+  // handle into our map, and return the newly populated cache.
+  auto IP = AssumptionCaches.insert(std::make_pair(
+      FunctionCallbackVH(&F, this), std::make_unique<AssumptionCache>(F)));
+  assert(IP.second && "Scanning function already in the map?");
+  return *IP.first->second;
+}
+
+AssumptionCache *AssumptionCacheTracker::lookupAssumptionCache(Function &F) {
+  auto I = AssumptionCaches.find_as(&F);
+  if (I != AssumptionCaches.end())
+    return I->second.get();
+  return nullptr;
+}
+
+void AssumptionCacheTracker::verifyAnalysis() const {
+  // FIXME: In the long term the verifier should not be controllable with a
+  // flag. We should either fix all passes to correctly update the assumption
+  // cache and enable the verifier unconditionally or somehow arrange for the
+  // assumption list to be updated automatically by passes.
+  if (!VerifyAssumptionCache)
+    return;
+
+  SmallPtrSet<const CallInst *, 4> AssumptionSet;
+  for (const auto &I : AssumptionCaches) {
+    for (auto &VH : I.second->assumptions())
+      if (VH)
+        AssumptionSet.insert(cast<CallInst>(VH));
+
+    for (const BasicBlock &B : cast<Function>(*I.first))
+      for (const Instruction &II : B)
+        if (match(&II, m_Intrinsic<Intrinsic::assume>()) &&
+            !AssumptionSet.count(cast<CallInst>(&II)))
+          report_fatal_error("Assumption in scanned function not in cache");
+  }
+}
+
+AssumptionCacheTracker::AssumptionCacheTracker() : ImmutablePass(ID) {
+  initializeAssumptionCacheTrackerPass(*PassRegistry::getPassRegistry());
+}
+
+AssumptionCacheTracker::~AssumptionCacheTracker() = default;
+
+char AssumptionCacheTracker::ID = 0;
+
+INITIALIZE_PASS(AssumptionCacheTracker, "assumption-cache-tracker",
+                "Assumption Cache Tracker", false, true)