From 697c6d8907e781534eeff062fbe90806ece4b25c Mon Sep 17 00:00:00 2001
From: Shinji Okumura <okuraofvegetable@gmail.com>
Date: Thu, 23 Jul 2020 20:26:30 +0900
Subject: [PATCH] [Attributor] Cache query results for isPotentiallyReachable
 in AAReachability

Summary:
This is the next patch of [[ https://reviews.llvm.org/D76210 | D76210 ]].
This patch made a map in `InformationCache` for caching results.

Reviewers: jdoerfert, sstefan1, uenoku, homerdin, baziotis

Reviewed By: jdoerfert

Subscribers: hiraditya, uenoku, kuter, bbn, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D83246
---
 llvm/include/llvm/Transforms/IPO/Attributor.h | 30 +++++++++++++++----
 .../Transforms/IPO/AttributorAttributes.cpp   |  2 +-
 2 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
index bed180e6717a..1eead8ee788d 100644
--- a/llvm/include/llvm/Transforms/IPO/Attributor.h
+++ b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -715,6 +715,21 @@ struct InformationCache {
   /// Return the map conaining all the knowledge we have from `llvm.assume`s.
   const RetainedKnowledgeMap &getKnowledgeMap() const { return KnowledgeMap; }
 
+  /// Return if \p To is potentially reachable form \p From or not
+  /// If the same query was answered, return cached result
+  bool getPotentiallyReachable(const Instruction &From, const Instruction &To) {
+    auto KeyPair = std::make_pair(&From, &To);
+    auto Iter = PotentiallyReachableMap.find(KeyPair);
+    if (Iter != PotentiallyReachableMap.end())
+      return Iter->second;
+    const Function &F = *From.getFunction();
+    bool Result = isPotentiallyReachable(
+        &From, &To, nullptr, AG.getAnalysis<DominatorTreeAnalysis>(F),
+        AG.getAnalysis<LoopAnalysis>(F));
+    PotentiallyReachableMap.insert(std::make_pair(KeyPair, Result));
+    return Result;
+  }
+
 private:
   struct FunctionInfo {
     ~FunctionInfo();
@@ -774,6 +789,10 @@ private:
   /// Set of inlineable functions
   SmallPtrSet<const Function *, 8> InlineableFunctions;
 
+  /// A map for caching results of queries for isPotentiallyReachable
+  DenseMap<std::pair<const Instruction *, const Instruction *>, bool>
+      PotentiallyReachableMap;
+
   /// Give the Attributor access to the members so
   /// Attributor::identifyDefaultAbstractAttributes(...) can initialize them.
   friend struct Attributor;
@@ -2374,16 +2393,17 @@ struct AAReachability : public StateWrapper<BooleanState, AbstractAttribute> {
   /// Returns true if 'From' instruction is assumed to reach, 'To' instruction.
   /// Users should provide two positions they are interested in, and the class
   /// determines (and caches) reachability.
-  bool isAssumedReachable(const Instruction *From,
-                          const Instruction *To) const {
-    return isPotentiallyReachable(From, To);
+  bool isAssumedReachable(Attributor &A, const Instruction &From,
+                          const Instruction &To) const {
+    return A.getInfoCache().getPotentiallyReachable(From, To);
   }
 
   /// Returns true if 'From' instruction is known to reach, 'To' instruction.
   /// Users should provide two positions they are interested in, and the class
   /// determines (and caches) reachability.
-  bool isKnownReachable(const Instruction *From, const Instruction *To) const {
-    return isPotentiallyReachable(From, To);
+  bool isKnownReachable(Attributor &A, const Instruction &From,
+                        const Instruction &To) const {
+    return A.getInfoCache().getPotentiallyReachable(From, To);
   }
 
   /// Create an abstract attribute view for the position \p IRP.
diff --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index 7e9fd61eeb41..dc916089d394 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -2468,7 +2468,7 @@ struct AANoAliasCallSiteArgument final : AANoAliasImpl {
         const auto &ReachabilityAA =
             A.getAAFor<AAReachability>(*this, IRPosition::function(*ScopeFn));
 
-        if (!ReachabilityAA.isAssumedReachable(UserI, getCtxI()))
+        if (!ReachabilityAA.isAssumedReachable(A, *UserI, *getCtxI()))
           return true;
 
         if (auto *CB = dyn_cast<CallBase>(UserI)) {
-- 
2.34.1