Add files I seem to have dropped in my revert (r290086).

Sorry!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@290087 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/AssumptionCache.h

@@ -0,0 +1,168 @@
+//===- llvm/Analysis/AssumptionCache.h - Track @llvm.assume ---*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains a pass that keeps track of @llvm.assume intrinsics in
+// the functions of a module (allowing assumptions within any function to be
+// found cheaply by other parts of the optimizer).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_ASSUMPTIONCACHE_H
+#define LLVM_ANALYSIS_ASSUMPTIONCACHE_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/Pass.h"
+#include <memory>
+
+namespace llvm {
+
+/// \brief A cache of @llvm.assume calls within a function.
+///
+/// This cache provides fast lookup of assumptions within a function by caching
+/// them and amortizing the cost of scanning for them across all queries. The
+/// cache is also conservatively self-updating so that it will never return
+/// incorrect results about a function even as the function is being mutated.
+/// However, flushing the cache and rebuilding it (or explicitly updating it)
+/// may allow it to discover new assumptions.
+class AssumptionCache {
+  /// \brief The function for which this cache is handling assumptions.
+  ///
+  /// We track this to lazily populate our assumptions.
+  Function &F;
+
+  /// \brief Vector of weak value handles to calls of the @llvm.assume
+  /// intrinsic.
+  SmallVector<WeakVH, 4> AssumeHandles;
+
+  /// \brief Flag tracking whether we have scanned the function yet.
+  ///
+  /// We want to be as lazy about this as possible, and so we scan the function
+  /// at the last moment.
+  bool Scanned;
+
+  /// \brief Scan the function for assumptions and add them to the cache.
+  void scanFunction();
+
+public:
+  /// \brief Construct an AssumptionCache from a function by scanning all of
+  /// its instructions.
+  AssumptionCache(Function &F) : F(F), Scanned(false) {}
+
+  /// \brief Add an @llvm.assume intrinsic to this function's cache.
+  ///
+  /// The call passed in must be an instruction within this function and must
+  /// not already be in the cache.
+  void registerAssumption(CallInst *CI);
+
+  /// \brief Clear the cache of @llvm.assume intrinsics for a function.
+  ///
+  /// It will be re-scanned the next time it is requested.
+  void clear() {
+    AssumeHandles.clear();
+    Scanned = false;
+  }
+
+  /// \brief Access the list of assumption handles currently tracked for this
+  /// function.
+  ///
+  /// Note that these produce weak handles that may be null. The caller must
+  /// handle that case.
+  /// FIXME: We should replace this with pointee_iterator<filter_iterator<...>>
+  /// when we can write that to filter out the null values. Then caller code
+  /// will become simpler.
+  MutableArrayRef<WeakVH> assumptions() {
+    if (!Scanned)
+      scanFunction();
+    return AssumeHandles;
+  }
+};
+
+/// \brief A function analysis which provides an \c AssumptionCache.
+///
+/// This analysis is intended for use with the new pass manager and will vend
+/// assumption caches for a given function.
+class AssumptionAnalysis : public AnalysisInfoMixin<AssumptionAnalysis> {
+  friend AnalysisInfoMixin<AssumptionAnalysis>;
+  static AnalysisKey Key;
+
+public:
+  typedef AssumptionCache Result;
+
+  AssumptionCache run(Function &F, FunctionAnalysisManager &) {
+    return AssumptionCache(F);
+  }
+};
+
+/// \brief Printer pass for the \c AssumptionAnalysis results.
+class AssumptionPrinterPass : public PassInfoMixin<AssumptionPrinterPass> {
+  raw_ostream &OS;
+
+public:
+  explicit AssumptionPrinterPass(raw_ostream &OS) : OS(OS) {}
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
+};
+
+/// \brief An immutable pass that tracks lazily created \c AssumptionCache
+/// objects.
+///
+/// This is essentially a workaround for the legacy pass manager's weaknesses
+/// which associates each assumption cache with Function and clears it if the
+/// function is deleted. The nature of the AssumptionCache is that it is not
+/// invalidated by any changes to the function body and so this is sufficient
+/// to be conservatively correct.
+class AssumptionCacheTracker : public ImmutablePass {
+  /// A callback value handle applied to function objects, which we use to
+  /// delete our cache of intrinsics for a function when it is deleted.
+  class FunctionCallbackVH final : public CallbackVH {
+    AssumptionCacheTracker *ACT;
+    void deleted() override;
+
+  public:
+    typedef DenseMapInfo<Value *> DMI;
+
+    FunctionCallbackVH(Value *V, AssumptionCacheTracker *ACT = nullptr)
+        : CallbackVH(V), ACT(ACT) {}
+  };
+
+  friend FunctionCallbackVH;
+
+  typedef DenseMap<FunctionCallbackVH, std::unique_ptr<AssumptionCache>,
+                   FunctionCallbackVH::DMI> FunctionCallsMap;
+  FunctionCallsMap AssumptionCaches;
+
+public:
+  /// \brief Get the cached assumptions for a function.
+  ///
+  /// If no assumptions are cached, this will scan the function. Otherwise, the
+  /// existing cache will be returned.
+  AssumptionCache &getAssumptionCache(Function &F);
+
+  AssumptionCacheTracker();
+  ~AssumptionCacheTracker() override;
+
+  void releaseMemory() override { AssumptionCaches.shrink_and_clear(); }
+
+  void verifyAnalysis() const override;
+  bool doFinalization(Module &) override {
+    verifyAnalysis();
+    return false;
+  }
+
+  static char ID; // Pass identification, replacement for typeid
+};
+
+} // end namespace llvm
+
+#endif

lib/Analysis/AssumptionCache.cpp

@@ -0,0 +1,140 @@
+//===- AssumptionCache.cpp - Cache finding @llvm.assume calls -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// 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/IR/CallSite.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/Debug.h"
+using namespace llvm;
+using namespace llvm::PatternMatch;
+
+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;
+}
+
+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
+}
+
+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), llvm::make_unique<AssumptionCache>(F)));
+  assert(IP.second && "Scanning function already in the map?");
+  return *IP.first->second;
+}
+
+void AssumptionCacheTracker::verifyAnalysis() const {
+#ifndef NDEBUG
+  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>()))
+          assert(AssumptionSet.count(cast<CallInst>(&II)) &&
+                 "Assumption in scanned function not in cache");
+  }
+#endif
+}
+
+AssumptionCacheTracker::AssumptionCacheTracker() : ImmutablePass(ID) {
+  initializeAssumptionCacheTrackerPass(*PassRegistry::getPassRegistry());
+}
+
+AssumptionCacheTracker::~AssumptionCacheTracker() {}
+
+INITIALIZE_PASS(AssumptionCacheTracker, "assumption-cache-tracker",
+                "Assumption Cache Tracker", false, true)
+char AssumptionCacheTracker::ID = 0;

test/Analysis/AssumptionCache/basic.ll

@@ -0,0 +1,22 @@
+; RUN: opt < %s -disable-output -passes='print<assumptions>' 2>&1 | FileCheck %s
+
+target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
+
+declare void @llvm.assume(i1)
+
+define void @test1(i32 %a) {
+; CHECK-LABEL: Cached assumptions for function: test1
+; CHECK-NEXT: icmp ne i32 %{{.*}}, 0
+; CHECK-NEXT: icmp slt i32 %{{.*}}, 0
+; CHECK-NEXT: icmp sgt i32 %{{.*}}, 0
+
+entry:
+  %cond1 = icmp ne i32 %a, 0
+  call void @llvm.assume(i1 %cond1)
+  %cond2 = icmp slt i32 %a, 0
+  call void @llvm.assume(i1 %cond2)
+  %cond3 = icmp sgt i32 %a, 0
+  call void @llvm.assume(i1 %cond3)
+
+  ret void
+}