Revamp PredIteratorCache interface to be cleaner.

Summary:
This lets us use range based for loops.

Reviewers: chandlerc

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9169

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235416 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Analysis/MemoryDependenceAnalysis.h

@@ -19,6 +19,7 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/PredIteratorCache.h"
 #include "llvm/IR/ValueHandle.h"
 #include "llvm/Pass.h"
 
@@ -325,7 +326,7 @@ namespace llvm {
     AliasAnalysis *AA;
     DominatorTree *DT;
     AssumptionCache *AC;
-    std::unique_ptr<PredIteratorCache> PredCache;
+    PredIteratorCache PredCache;
 
   public:
     MemoryDependenceAnalysis();

include/llvm/IR/PredIteratorCache.h

@@ -14,6 +14,7 @@
 #ifndef LLVM_IR_PREDITERATORCACHE_H
 #define LLVM_IR_PREDITERATORCACHE_H
 
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/IR/CFG.h"
@@ -21,50 +22,58 @@
 
 namespace llvm {
 
-  /// PredIteratorCache - This class is an extremely trivial cache for
-  /// predecessor iterator queries.  This is useful for code that repeatedly
-  /// wants the predecessor list for the same blocks.
-  class PredIteratorCache {
-    /// BlockToPredsMap - Pointer to null-terminated list.
-    DenseMap<BasicBlock*, BasicBlock**> BlockToPredsMap;
-    DenseMap<BasicBlock*, unsigned> BlockToPredCountMap;
+/// PredIteratorCache - This class is an extremely trivial cache for
+/// predecessor iterator queries.  This is useful for code that repeatedly
+/// wants the predecessor list for the same blocks.
+class PredIteratorCache {
+  /// BlockToPredsMap - Pointer to null-terminated list.
+  DenseMap<BasicBlock *, BasicBlock **> BlockToPredsMap;
+  DenseMap<BasicBlock *, unsigned> BlockToPredCountMap;
 
-    /// Memory - This is the space that holds cached preds.
-    BumpPtrAllocator Memory;
-  public:
+  /// Memory - This is the space that holds cached preds.
+  BumpPtrAllocator Memory;
 
-    /// GetPreds - Get a cached list for the null-terminated predecessor list of
-    /// the specified block.  This can be used in a loop like this:
-    ///   for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI)
-    ///      use(*PI);
-    /// instead of:
-    /// for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
-    BasicBlock **GetPreds(BasicBlock *BB) {
-      BasicBlock **&Entry = BlockToPredsMap[BB];
-      if (Entry) return Entry;
-
-      SmallVector<BasicBlock*, 32> PredCache(pred_begin(BB), pred_end(BB));
-      PredCache.push_back(nullptr); // null terminator.
-      
-      BlockToPredCountMap[BB] = PredCache.size()-1;
-
-      Entry = Memory.Allocate<BasicBlock*>(PredCache.size());
-      std::copy(PredCache.begin(), PredCache.end(), Entry);
+private:
+  /// GetPreds - Get a cached list for the null-terminated predecessor list of
+  /// the specified block.  This can be used in a loop like this:
+  ///   for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI)
+  ///      use(*PI);
+  /// instead of:
+  /// for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
+  BasicBlock **GetPreds(BasicBlock *BB) {
+    BasicBlock **&Entry = BlockToPredsMap[BB];
+    if (Entry)
       return Entry;
-    }
-    
-    unsigned GetNumPreds(BasicBlock *BB) {
-      GetPreds(BB);
-      return BlockToPredCountMap[BB];
-    }
 
-    /// clear - Remove all information.
-    void clear() {
-      BlockToPredsMap.clear();
-      BlockToPredCountMap.clear();
-      Memory.Reset();
-    }
-  };
+    SmallVector<BasicBlock *, 32> PredCache(pred_begin(BB), pred_end(BB));
+    PredCache.push_back(nullptr); // null terminator.
+
+    BlockToPredCountMap[BB] = PredCache.size() - 1;
+
+    Entry = Memory.Allocate<BasicBlock *>(PredCache.size());
+    std::copy(PredCache.begin(), PredCache.end(), Entry);
+    return Entry;
+  }
+
+  unsigned GetNumPreds(BasicBlock *BB) {
+    GetPreds(BB);
+    return BlockToPredCountMap[BB];
+  }
+
+public:
+  size_t size(BasicBlock *BB) { return GetNumPreds(BB); }
+  ArrayRef<BasicBlock *> get(BasicBlock *BB) {
+    return makeArrayRef(GetPreds(BB), GetNumPreds(BB));
+  }
+
+  /// clear - Remove all information.
+  void clear() {
+    BlockToPredsMap.clear();
+    BlockToPredCountMap.clear();
+    Memory.Reset();
+  }
+};
+
 } // end namespace llvm
 
 #endif

lib/Analysis/MemoryDependenceAnalysis.cpp

@@ -65,7 +65,7 @@ INITIALIZE_PASS_END(MemoryDependenceAnalysis, "memdep",
                       "Memory Dependence Analysis", false, true)
 
 MemoryDependenceAnalysis::MemoryDependenceAnalysis()
-    : FunctionPass(ID), PredCache() {
+    : FunctionPass(ID) {
   initializeMemoryDependenceAnalysisPass(*PassRegistry::getPassRegistry());
 }
 MemoryDependenceAnalysis::~MemoryDependenceAnalysis() {
@@ -79,7 +79,7 @@ void MemoryDependenceAnalysis::releaseMemory() {
   ReverseLocalDeps.clear();
   ReverseNonLocalDeps.clear();
   ReverseNonLocalPtrDeps.clear();
-  PredCache->clear();
+  PredCache.clear();
 }
 
 /// getAnalysisUsage - Does not modify anything.  It uses Alias Analysis.
@@ -96,8 +96,6 @@ bool MemoryDependenceAnalysis::runOnFunction(Function &F) {
   DominatorTreeWrapperPass *DTWP =
       getAnalysisIfAvailable<DominatorTreeWrapperPass>();
   DT = DTWP ? &DTWP->getDomTree() : nullptr;
-  if (!PredCache)
-    PredCache.reset(new PredIteratorCache());
   return false;
 }
 
@@ -770,8 +768,8 @@ MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
   } else {
     // Seed DirtyBlocks with each of the preds of QueryInst's block.
     BasicBlock *QueryBB = QueryCS.getInstruction()->getParent();
-    for (BasicBlock **PI = PredCache->GetPreds(QueryBB); *PI; ++PI)
-      DirtyBlocks.push_back(*PI);
+    for (BasicBlock *Pred : PredCache.get(QueryBB))
+      DirtyBlocks.push_back(Pred);
     ++NumUncacheNonLocal;
   }
 
@@ -856,8 +854,8 @@ MemoryDependenceAnalysis::getNonLocalCallDependency(CallSite QueryCS) {
 
       // If the block *is* completely transparent to the load, we need to check
       // the predecessors of this block.  Add them to our worklist.
-      for (BasicBlock **PI = PredCache->GetPreds(DirtyBB); *PI; ++PI)
-        DirtyBlocks.push_back(*PI);
+      for (BasicBlock *Pred : PredCache.get(DirtyBB))
+        DirtyBlocks.push_back(Pred);
     }
   }
 
@@ -1232,13 +1230,13 @@ getNonLocalPointerDepFromBB(Instruction *QueryInst,
     if (!Pointer.NeedsPHITranslationFromBlock(BB)) {
       SkipFirstBlock = false;
       SmallVector<BasicBlock*, 16> NewBlocks;
-      for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
+      for (BasicBlock *Pred : PredCache.get(BB)) {
         // Verify that we haven't looked at this block yet.
         std::pair<DenseMap<BasicBlock*,Value*>::iterator, bool>
-          InsertRes = Visited.insert(std::make_pair(*PI, Pointer.getAddr()));
+          InsertRes = Visited.insert(std::make_pair(Pred, Pointer.getAddr()));
         if (InsertRes.second) {
           // First time we've looked at *PI.
-          NewBlocks.push_back(*PI);
+          NewBlocks.push_back(Pred);
           continue;
         }
 
@@ -1274,8 +1272,7 @@ getNonLocalPointerDepFromBB(Instruction *QueryInst,
     Cache = nullptr;
 
     PredList.clear();
-    for (BasicBlock **PI = PredCache->GetPreds(BB); *PI; ++PI) {
-      BasicBlock *Pred = *PI;
+    for (BasicBlock *Pred : PredCache.get(BB)) {
       PredList.push_back(std::make_pair(Pred, Pointer));
 
       // Get the PHI translated pointer in this predecessor.  This can fail if
@@ -1465,7 +1462,7 @@ void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
 /// This needs to be done when the CFG changes, e.g., due to splitting
 /// critical edges.
 void MemoryDependenceAnalysis::invalidateCachedPredecessors() {
-  PredCache->clear();
+  PredCache.clear();
 }
 
 /// removeInstruction - Remove an instruction from the dependence analysis,

lib/Transforms/Scalar/LICM.cpp

@@ -704,10 +704,10 @@ namespace {
             // We need to create an LCSSA PHI node for the incoming value and
             // store that.
             PHINode *PN = PHINode::Create(
-                I->getType(), PredCache.GetNumPreds(BB),
+                I->getType(), PredCache.size(BB),
                 I->getName() + ".lcssa", BB->begin());
-            for (BasicBlock **PI = PredCache.GetPreds(BB); *PI; ++PI)
-              PN->addIncoming(I, *PI);
+            for (BasicBlock *Pred : PredCache.get(BB))
+              PN->addIncoming(I, Pred);
             return PN;
           }
       return V;

lib/Transforms/Utils/LCSSA.cpp

@@ -112,17 +112,17 @@ static bool processInstruction(Loop &L, Instruction &Inst, DominatorTree &DT,
     if (SSAUpdate.HasValueForBlock(ExitBB))
       continue;
 
-    PHINode *PN = PHINode::Create(Inst.getType(), PredCache.GetNumPreds(ExitBB),
+    PHINode *PN = PHINode::Create(Inst.getType(), PredCache.size(ExitBB),
                                   Inst.getName() + ".lcssa", ExitBB->begin());
 
     // Add inputs from inside the loop for this PHI.
-    for (BasicBlock **PI = PredCache.GetPreds(ExitBB); *PI; ++PI) {
-      PN->addIncoming(&Inst, *PI);
+    for (BasicBlock *Pred : PredCache.get(ExitBB)) {
+      PN->addIncoming(&Inst, Pred);
 
       // If the exit block has a predecessor not within the loop, arrange for
       // the incoming value use corresponding to that predecessor to be
       // rewritten in terms of a different LCSSA PHI.
-      if (!L.contains(*PI))
+      if (!L.contains(Pred))
         UsesToRewrite.push_back(
             &PN->getOperandUse(PN->getOperandNumForIncomingValue(
                  PN->getNumIncomingValues() - 1)));