1 files changed, 239 insertions, 0 deletions
diff --git a/clang-r353983e/include/llvm/Analysis/AssumptionCache.h b/clang-r353983e/include/llvm/Analysis/AssumptionCache.h
new file mode 100644
index 00000000..b4284647
--- /dev/null
+++ b/clang-r353983e/include/llvm/Analysis/AssumptionCache.h
@@ -0,0 +1,239 @@
+//===- llvm/Analysis/AssumptionCache.h - Track @llvm.assume -----*- C++ -*-===//
+//
+// 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 (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/DenseMapInfo.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/PassManager.h"
+#include "llvm/IR/ValueHandle.h"
+#include "llvm/Pass.h"
+#include <memory>
+
+namespace llvm {
+
+class CallInst;
+class Function;
+class raw_ostream;
+class Value;
+
+/// 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. Passes
+/// that create new assumptions are required to call registerAssumption() to
+/// register any new \@llvm.assume calls that they create. Deletions of
+/// \@llvm.assume calls do not require special handling.
+class AssumptionCache {
+  /// The function for which this cache is handling assumptions.
+  ///
+  /// We track this to lazily populate our assumptions.
+  Function &F;
+
+  /// Vector of weak value handles to calls of the \@llvm.assume
+  /// intrinsic.
+  SmallVector<WeakTrackingVH, 4> AssumeHandles;
+
+  class AffectedValueCallbackVH final : public CallbackVH {
+    AssumptionCache *AC;
+
+    void deleted() override;
+    void allUsesReplacedWith(Value *) override;
+
+  public:
+    using DMI = DenseMapInfo<Value *>;
+
+    AffectedValueCallbackVH(Value *V, AssumptionCache *AC = nullptr)
+        : CallbackVH(V), AC(AC) {}
+  };
+
+  friend AffectedValueCallbackVH;
+
+  /// A map of values about which an assumption might be providing
+  /// information to the relevant set of assumptions.
+  using AffectedValuesMap =
+      DenseMap<AffectedValueCallbackVH, SmallVector<WeakTrackingVH, 1>,
+               AffectedValueCallbackVH::DMI>;
+  AffectedValuesMap AffectedValues;
+
+  /// Get the vector of assumptions which affect a value from the cache.
+  SmallVector<WeakTrackingVH, 1> &getOrInsertAffectedValues(Value *V);
+
+  /// Copy affected values in the cache for OV to be affected values for NV.
+  void copyAffectedValuesInCache(Value *OV, Value *NV);
+
+  /// 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 = false;
+
+  /// Scan the function for assumptions and add them to the cache.
+  void scanFunction();
+
+public:
+  /// Construct an AssumptionCache from a function by scanning all of
+  /// its instructions.
+  AssumptionCache(Function &F) : F(F) {}
+
+  /// This cache is designed to be self-updating and so it should never be
+  /// invalidated.
+  bool invalidate(Function &, const PreservedAnalyses &,
+                  FunctionAnalysisManager::Invalidator &) {
+    return false;
+  }
+
+  /// 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);
+
+  /// Remove an \@llvm.assume intrinsic from this function's cache if it has
+  /// been added to the cache earlier.
+  void unregisterAssumption(CallInst *CI);
+
+  /// Update the cache of values being affected by this assumption (i.e.
+  /// the values about which this assumption provides information).
+  void updateAffectedValues(CallInst *CI);
+
+  /// 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();
+    AffectedValues.clear();
+    Scanned = false;
+  }
+
+  /// 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<WeakTrackingVH> assumptions() {
+    if (!Scanned)
+      scanFunction();
+    return AssumeHandles;
+  }
+
+  /// Access the list of assumptions which affect this value.
+  MutableArrayRef<WeakTrackingVH> assumptionsFor(const Value *V) {
+    if (!Scanned)
+      scanFunction();
+
+    auto AVI = AffectedValues.find_as(const_cast<Value *>(V));
+    if (AVI == AffectedValues.end())
+      return MutableArrayRef<WeakTrackingVH>();
+
+    return AVI->second;
+  }
+};
+
+/// 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:
+  using Result = AssumptionCache;
+
+  AssumptionCache run(Function &F, FunctionAnalysisManager &) {
+    return AssumptionCache(F);
+  }
+};
+
+/// 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);
+};
+
+/// 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:
+    using DMI = DenseMapInfo<Value *>;
+
+    FunctionCallbackVH(Value *V, AssumptionCacheTracker *ACT = nullptr)
+        : CallbackVH(V), ACT(ACT) {}
+  };
+
+  friend FunctionCallbackVH;
+
+  using FunctionCallsMap =
+      DenseMap<FunctionCallbackVH, std::unique_ptr<AssumptionCache>,
+               FunctionCallbackVH::DMI>;
+
+  FunctionCallsMap AssumptionCaches;
+
+public:
+  /// 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);
+
+  /// Return the cached assumptions for a function if it has already been
+  /// scanned. Otherwise return nullptr.
+  AssumptionCache *lookupAssumptionCache(Function &F);
+
+  AssumptionCacheTracker();
+  ~AssumptionCacheTracker() override;
+
+  void releaseMemory() override {
+    verifyAnalysis();
+    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 // LLVM_ANALYSIS_ASSUMPTIONCACHE_H