Several changes here:

1. Increase max node size from 64->256 to avoid collapsing an important
   structure in 181.mcf
2. If we have multiple calls to an indirect call node with an indirect
   callee, fold these call nodes together, to avoid DSA turning apoc into
   a flaming fireball of death when analyzing 176.gcc.
  With this change, 176.gcc now takes ~7s to analyze for loc+bu+td, with
  5.7s of that in the BU pass.

llvm-svn: 20775

llvm/lib/Analysis/DataStructure/DataStructure.cpp

@@ -39,7 +39,7 @@ namespace {
   Statistic<> NumTrivialGlobalDNE("dsa", "Number of globals trivially removed");
 };
 
-#if 1
+#if 0
 #define TIME_REGION(VARNAME, DESC) \
    NamedRegionTimer VARNAME(DESC)
 #else
@@ -467,7 +467,7 @@ bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset,
     // collapse it.  This can occur for fortran common blocks, which have stupid
     // things like { [100000000 x double], [1000000 x double] }.
     unsigned NumFields = (NewTySize+DS::PointerSize-1) >> DS::PointerShift;
-    if (NumFields > 64) {
+    if (NumFields > 256) {
       foldNodeCompletely();
       return true;
     }
@@ -509,7 +509,7 @@ bool DSNode::mergeTypeInfo(const Type *NewTy, unsigned Offset,
     // collapse it.  This can occur for fortran common blocks, which have stupid
     // things like { [100000000 x double], [1000000 x double] }.
     unsigned NumFields = (NewTySize+DS::PointerSize-1) >> DS::PointerShift;
-    if (NumFields > 64) {
+    if (NumFields > 256) {
       foldNodeCompletely();
       return true;
     }
@@ -1574,22 +1574,20 @@ static inline void killIfUselessEdge(DSNodeHandle &Edge) {
         Edge.setTo(0, 0);  // Kill the edge!
 }
 
-#if 0
 static inline bool nodeContainsExternalFunction(const DSNode *N) {
-  const std::vector<GlobalValue*> &Globals = N->getGlobals();
-  for (unsigned i = 0, e = Globals.size(); i != e; ++i)
-    if (Globals[i]->isExternal() && isa<Function>(Globals[i]))
-      return true;
+  std::vector<Function*> Funcs;
+  N->addFullFunctionList(Funcs);
+  for (unsigned i = 0, e = Funcs.size(); i != e; ++i)
+    if (Funcs[i]->isExternal()) return true;
   return false;
 }
-#endif
 
 static void removeIdenticalCalls(std::list<DSCallSite> &Calls) {
   // Remove trivially identical function calls
   Calls.sort();  // Sort by callee as primary key!
 
   // Scan the call list cleaning it up as necessary...
-  DSNode   *LastCalleeNode = 0;
+  DSNodeHandle LastCalleeNode;
   Function *LastCalleeFunc = 0;
   unsigned NumDuplicateCalls = 0;
   bool LastCalleeContainsExternalFunction = false;
@@ -1600,17 +1598,41 @@ static void removeIdenticalCalls(std::list<DSCallSite> &Calls) {
     DSCallSite &CS = *I;
     std::list<DSCallSite>::iterator OldIt = I++;
 
-    // If the Callee is a useless edge, this must be an unreachable call site,
-    // eliminate it.
-    if (CS.isIndirectCall() && CS.getCalleeNode()->getNumReferrers() == 1 &&
-        CS.getCalleeNode()->isComplete() &&
-        CS.getCalleeNode()->getGlobalsList().empty()) {  // No useful info?
+    if (!CS.isIndirectCall()) {
+      LastCalleeNode = 0;
+    } else {
+      DSNode *Callee = CS.getCalleeNode();
+
+      // If the Callee is a useless edge, this must be an unreachable call site,
+      // eliminate it.
+      if (Callee->getNumReferrers() == 1 && Callee->isComplete() &&
+          Callee->getGlobalsList().empty()) {  // No useful info?
 #ifndef NDEBUG
-      std::cerr << "WARNING: Useless call site found.\n";
+        std::cerr << "WARNING: Useless call site found.\n";
 #endif
-      Calls.erase(OldIt);
-      ++NumDeleted;
-      continue;
+        Calls.erase(OldIt);
+        ++NumDeleted;
+        continue;
+      }
+
+      // If the last call site in the list has the same callee as this one, and
+      // if the callee contains an external function, it will never be
+      // resolvable, just merge the call sites.
+      if (!LastCalleeNode.isNull() && LastCalleeNode.getNode() == Callee) {
+        LastCalleeContainsExternalFunction =
+          nodeContainsExternalFunction(Callee);
+
+        std::list<DSCallSite>::iterator PrevIt = OldIt;
+        --PrevIt;
+        PrevIt->mergeWith(CS);
+
+        // No need to keep this call anymore.
+        Calls.erase(OldIt);
+        ++NumDeleted;
+        continue;
+      } else {
+        LastCalleeNode = Callee;
+      }
     }
 
     // If the return value or any arguments point to a void node with no
@@ -1676,6 +1698,7 @@ static void removeIdenticalCalls(std::list<DSCallSite> &Calls) {
 #endif
 
     if (I != Calls.end() && CS == *I) {
+      LastCalleeNode = 0;
       Calls.erase(OldIt);
       ++NumDeleted;
       continue;