Instead of callign removeTriviallyDeadNodes on the global graph every time

removeDeadNodes is called, only call it at the end of the pass being run.
This saves 1.3 seconds running DSA on 177.mesa (5.3->4.0s), which is
pretty big.  This is only possible because of the automatic garbage
collection done on forwarding nodes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@11178 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Analysis/DataStructure/BottomUpClosure.cpp

@@ -63,6 +63,7 @@ bool BUDataStructures::run(Module &M) {
   // nodes at the end of the BU phase should make things that they point to
   // incomplete in the globals graph.
   // 
+  GlobalsGraph->removeTriviallyDeadNodes();
   GlobalsGraph->maskIncompleteMarkers();
   return false;
 }

lib/Analysis/DataStructure/DataStructure.cpp

@@ -30,6 +30,8 @@ namespace {
   Statistic<> NumCallNodesMerged("dsa", "Number of call nodes merged");
   Statistic<> NumNodeAllocated  ("dsa", "Number of nodes allocated");
   Statistic<> NumDNE            ("dsa", "Number of nodes removed by reachability");
+  Statistic<> NumTrivialDNE     ("dsa", "Number of nodes trivially removed");
+  Statistic<> NumTrivialGlobalDNE("dsa", "Number of globals trivially removed");
 
   cl::opt<bool>
   EnableDSNodeGlobalRootsHack("enable-dsa-globalrootshack", cl::Hidden,
@@ -1470,8 +1472,6 @@ static void removeIdenticalCalls(std::vector<DSCallSite> &Calls) {
 //
 void DSGraph::removeTriviallyDeadNodes() {
   TIME_REGION(X, "removeTriviallyDeadNodes");
-  removeIdenticalCalls(FunctionCalls);
-  removeIdenticalCalls(AuxFunctionCalls);
 
   // Loop over all of the nodes in the graph, calling getNode on each field.
   // This will cause all nodes to update their forwarding edges, causing
@@ -1531,6 +1531,7 @@ void DSGraph::removeTriviallyDeadNodes() {
           for (unsigned j = 0, e = Globals.size(); j != e; ++j)
             ScalarMap.erase(Globals[j]);
           Node.makeNodeDead();
+          ++NumTrivialGlobalDNE;
         }
       }
     }
@@ -1538,10 +1539,14 @@ void DSGraph::removeTriviallyDeadNodes() {
     if (Node.getNodeFlags() == 0 && Node.hasNoReferrers()) {
       // This node is dead!
       NI = Nodes.erase(NI);    // Erase & remove from node list.
+      ++NumTrivialDNE;
     } else {
       ++NI;
     }
   }
+
+  removeIdenticalCalls(FunctionCalls);
+  removeIdenticalCalls(AuxFunctionCalls);
 }
 
 
@@ -1755,12 +1760,8 @@ void DSGraph::removeDeadNodes(unsigned Flags) {
   AuxFunctionCalls.erase(AuxFunctionCalls.begin()+CurIdx,
                          AuxFunctionCalls.end());
 
-  // We are finally done with the GGCloner so we can clear it and then get rid
-  // of unused nodes in the GlobalsGraph produced by merging.
-  if (GGCloner.clonedNode()) {
-    GGCloner.destroy();
-    GlobalsGraph->removeTriviallyDeadNodes();
-  }
+  // We are finally done with the GGCloner so we can destroy it.
+  GGCloner.destroy();
 
   // At this point, any nodes which are visited, but not alive, are nodes
   // which can be removed.  Loop over all nodes, eliminating completely

lib/Analysis/DataStructure/Local.cpp

@@ -623,6 +623,7 @@ bool LocalDataStructures::run(Module &M) {
     if (!I->isExternal())
       GGB.mergeInGlobalInitializer(I);
 
+  GlobalsGraph->removeTriviallyDeadNodes();
   GlobalsGraph->markIncompleteNodes(DSGraph::MarkFormalArgs);
   return false;
 }

lib/Analysis/DataStructure/TopDownClosure.cpp

@@ -107,6 +107,8 @@ bool TDDataStructures::run(Module &M) {
   }
 
   ArgsRemainIncomplete.clear();
+  GlobalsGraph->removeTriviallyDeadNodes();
+
   return false;
 }