Change NonLocalDeps to be a densemap of pointers to densemap

instead of containing them by value.  This increases the density
(!) of NonLocalDeps as well as making the reallocation case 
faster.  This speeds up gvn on 403.gcc by 2% and makes room for
future improvements.

I'm not super thrilled with having to explicitly manage the new/delete
of the map, but it is necesary for the next change.

llvm-svn: 60271

2 files changed, 60 insertions, 35 deletions

diff --git a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
index fa457187589..01a731730c5 100644
--- a/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
+++ b/llvm/include/llvm/Analysis/MemoryDependenceAnalysis.h
@@ -111,9 +111,9 @@ namespace llvm {
       Normal,
 
       /// None - This dependence type indicates that the query does not depend
-      /// on any instructions, either because it scanned to the start of the
-      /// function or it scanned to the definition of the memory
-      /// (alloca/malloc).
+      /// on any instructions, either because it is not a memory instruction or
+      /// because it scanned to the definition of the memory (alloca/malloc)
+      /// being accessed.
       None,
       
       /// NonLocal - This marker indicates that the query has no dependency in
@@ -128,9 +128,9 @@ namespace llvm {
     LocalDepMapType LocalDeps;
 
     // A map from instructions to their non-local dependencies.
-    // FIXME: DENSEMAP of DENSEMAP not a great idea.
     typedef DenseMap<Instruction*,
-                     DenseMap<BasicBlock*, DepResultTy> > NonLocalDepMapType;
+                     // This is an owning pointer.
+                     DenseMap<BasicBlock*, DepResultTy>*> NonLocalDepMapType;
     NonLocalDepMapType NonLocalDeps;
     
     // A reverse mapping from dependencies to the dependees.  This is
@@ -153,6 +153,9 @@ namespace llvm {
     /// Clean up memory in between runs
     void releaseMemory() {
       LocalDeps.clear();
+      for (NonLocalDepMapType::iterator I = NonLocalDeps.begin(),
+           E = NonLocalDeps.end(); I != E; ++I)
+        delete I->second;
       NonLocalDeps.clear();
       ReverseLocalDeps.clear();
       ReverseNonLocalDeps.clear();
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index 0a71b30de5e..01af42c8636 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -227,7 +227,10 @@ getNonLocalDependency(Instruction *QueryInst,
                                                       MemDepResult> > &Result) {
   assert(getDependency(QueryInst).isNonLocal() &&
      "getNonLocalDependency should only be used on insts with non-local deps!");
-  DenseMap<BasicBlock*, DepResultTy> &Cache = NonLocalDeps[QueryInst];
+  DenseMap<BasicBlock*, DepResultTy>* &CacheP = NonLocalDeps[QueryInst];
+  if (CacheP == 0) CacheP = new DenseMap<BasicBlock*, DepResultTy>();
+  
+  DenseMap<BasicBlock*, DepResultTy> &Cache = *CacheP;
 
   /// DirtyBlocks - This is the set of blocks that need to be recomputed.  In
   /// the cached case, this can happen due to instructions being deleted etc. In
@@ -271,8 +274,14 @@ getNonLocalDependency(Instruction *QueryInst,
     // If the dirty entry has a pointer, start scanning from it so we don't have
     // to rescan the entire block.
     BasicBlock::iterator ScanPos = DirtyBB->end();
-    if (Instruction *Inst = DirtyBBEntry.getPointer())
+    if (Instruction *Inst = DirtyBBEntry.getPointer()) {
       ScanPos = Inst;
+      
+      // We're removing QueryInst's dependence on Inst.
+      SmallPtrSet<Instruction*, 4> &InstMap = ReverseNonLocalDeps[Inst];
+      InstMap.erase(QueryInst);
+      if (InstMap.empty()) ReverseNonLocalDeps.erase(Inst);
+    }
     
     // Find out if this block has a local dependency for QueryInst.
     DirtyBBEntry = getDependencyFromInternal(QueryInst, ScanPos, DirtyBB);
@@ -305,11 +314,16 @@ getNonLocalDependency(Instruction *QueryInst,
 void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
   // Walk through the Non-local dependencies, removing this one as the value
   // for any cached queries.
-  for (DenseMap<BasicBlock*, DepResultTy>::iterator DI =
-       NonLocalDeps[RemInst].begin(), DE = NonLocalDeps[RemInst].end();
-       DI != DE; ++DI)
-    if (Instruction *Inst = DI->second.getPointer())
-      ReverseNonLocalDeps[Inst].erase(RemInst);
+  NonLocalDepMapType::iterator NLDI = NonLocalDeps.find(RemInst);
+  if (NLDI != NonLocalDeps.end()) {
+    DenseMap<BasicBlock*, DepResultTy> &BlockMap = *NLDI->second;
+    for (DenseMap<BasicBlock*, DepResultTy>::iterator DI =
+         BlockMap.begin(), DE = BlockMap.end(); DI != DE; ++DI)
+      if (Instruction *Inst = DI->second.getPointer())
+        ReverseNonLocalDeps[Inst].erase(RemInst);
+    delete &BlockMap;
+    NonLocalDeps.erase(NLDI);
+  }
 
   // If we have a cached local dependence query for this instruction, remove it.
   //
@@ -347,10 +361,8 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
     for (SmallPtrSet<Instruction*, 4>::iterator I = ReverseDeps.begin(),
          E = ReverseDeps.end(); I != E; ++I) {
       Instruction *InstDependingOnRemInst = *I;
-      
-      // If we thought the instruction depended on itself (possible for
-      // unconfirmed dependencies) ignore the update.
-      if (InstDependingOnRemInst == RemInst) continue;
+      assert(InstDependingOnRemInst != RemInst &&
+             "Already removed our local dep info");
                         
       LocalDeps[InstDependingOnRemInst] = DepResultTy(NewDepInst, Dirty);
       
@@ -374,22 +386,27 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
   if (ReverseDepIt != ReverseNonLocalDeps.end()) {
     SmallPtrSet<Instruction*, 4>& set = ReverseDepIt->second;
     for (SmallPtrSet<Instruction*, 4>::iterator I = set.begin(), E = set.end();
-         I != E; ++I)
+         I != E; ++I) {
+      assert(*I != RemInst && "Already removed NonLocalDep info for RemInst");
+      
+      DenseMap<BasicBlock*, DepResultTy> &INLD = *NonLocalDeps[*I];
+      assert(&INLD != 0 && "Reverse mapping out of date?");
+      
       for (DenseMap<BasicBlock*, DepResultTy>::iterator
-           DI = NonLocalDeps[*I].begin(), DE = NonLocalDeps[*I].end();
-           DI != DE; ++DI)
-        if (DI->second.getPointer() == RemInst) {
-          // Convert to a dirty entry for the subsequent instruction.
-          DI->second.setInt(Dirty);
-          if (RemInst->isTerminator())
-            DI->second.setPointer(0);
-          else {
-            Instruction *NextI = next(BasicBlock::iterator(RemInst));
-            DI->second.setPointer(NextI);
-            assert(NextI != RemInst);
-            ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
-          }
+           DI = INLD.begin(), DE = INLD.end(); DI != DE; ++DI) {
+        if (DI->second.getPointer() != RemInst) continue;
+        
+        // Convert to a dirty entry for the subsequent instruction.
+        DI->second.setInt(Dirty);
+        if (RemInst->isTerminator())
+          DI->second.setPointer(0);
+        else {
+          Instruction *NextI = next(BasicBlock::iterator(RemInst));
+          DI->second.setPointer(NextI);
+          ReverseDepsToAdd.push_back(std::make_pair(NextI, *I));
         }
+      }
+    }
 
     ReverseNonLocalDeps.erase(ReverseDepIt);
 
@@ -401,7 +418,7 @@ void MemoryDependenceAnalysis::removeInstruction(Instruction *RemInst) {
     }
   }
   
-  NonLocalDeps.erase(RemInst);
+  assert(!NonLocalDeps.count(RemInst) && "RemInst got reinserted?");
   getAnalysis<AliasAnalysis>().deleteValue(RemInst);
   DEBUG(verifyRemoved(RemInst));
 }
@@ -419,21 +436,26 @@ void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {
   for (NonLocalDepMapType::const_iterator I = NonLocalDeps.begin(),
        E = NonLocalDeps.end(); I != E; ++I) {
     assert(I->first != D && "Inst occurs in data structures");
-    for (DenseMap<BasicBlock*, DepResultTy>::iterator II = I->second.begin(),
-         EE = I->second.end(); II  != EE; ++II)
+    DenseMap<BasicBlock*, DepResultTy> &INLD = *I->second;
+    for (DenseMap<BasicBlock*, DepResultTy>::iterator II = INLD.begin(),
+         EE = INLD.end(); II  != EE; ++II)
       assert(II->second.getPointer() != D && "Inst occurs in data structures");
   }
   
   for (ReverseDepMapType::const_iterator I = ReverseLocalDeps.begin(),
-       E = ReverseLocalDeps.end(); I != E; ++I)
+       E = ReverseLocalDeps.end(); I != E; ++I) {
+    assert(I->first != D && "Inst occurs in data structures");
     for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
          EE = I->second.end(); II != EE; ++II)
       assert(*II != D && "Inst occurs in data structures");
+  }
   
   for (ReverseDepMapType::const_iterator I = ReverseNonLocalDeps.begin(),
        E = ReverseNonLocalDeps.end();
-       I != E; ++I)
+       I != E; ++I) {
+    assert(I->first != D && "Inst occurs in data structures");
     for (SmallPtrSet<Instruction*, 4>::const_iterator II = I->second.begin(),
          EE = I->second.end(); II != EE; ++II)
       assert(*II != D && "Inst occurs in data structures");
+  }
 }