Revert "[ScopedNoAliasAA] Remove an unneccesary set"

This reverts commit r278641.  I'm not sure why but this has upset the
multistage builders...

llvm-svn: 278644

1 files changed, 20 insertions, 13 deletions

diff --git a/llvm/lib/Analysis/ScopedNoAliasAA.cpp b/llvm/lib/Analysis/ScopedNoAliasAA.cpp
index b631faddbeb..1c4d0fa94bf 100644
--- a/llvm/lib/Analysis/ScopedNoAliasAA.cpp
+++ b/llvm/lib/Analysis/ScopedNoAliasAA.cpp
@@ -127,6 +127,15 @@ ModRefInfo ScopedNoAliasAAResult::getModRefInfo(ImmutableCallSite CS1,
   return AAResultBase::getModRefInfo(CS1, CS2);
 }
 
+void ScopedNoAliasAAResult::collectMDInDomain(
+    const MDNode *List, const MDNode *Domain,
+    SmallPtrSetImpl<const MDNode *> &Nodes) const {
+  for (const MDOperand &MDOp : List->operands())
+    if (const MDNode *MD = dyn_cast<MDNode>(MDOp))
+      if (AliasScopeNode(MD).getDomain() == Domain)
+        Nodes.insert(MD);
+}
+
 bool ScopedNoAliasAAResult::mayAliasInScopes(const MDNode *Scopes,
                                              const MDNode *NoAlias) const {
   if (!Scopes || !NoAlias)
@@ -142,21 +151,19 @@ bool ScopedNoAliasAAResult::mayAliasInScopes(const MDNode *Scopes,
   // We alias unless, for some domain, the set of noalias scopes in that domain
   // is a superset of the set of alias scopes in that domain.
   for (const MDNode *Domain : Domains) {
-    SmallPtrSet<const MDNode *, 16> NANodes;
-    for (const MDOperand &MDOp : NoAlias->operands())
-      if (const MDNode *MD = dyn_cast<MDNode>(MDOp))
-        if (AliasScopeNode(MD).getDomain() == Domain)
-          NANodes.insert(MD);
+    SmallPtrSet<const MDNode *, 16> NANodes, ScopeNodes;
+    collectMDInDomain(NoAlias, Domain, NANodes);
+    collectMDInDomain(Scopes, Domain, ScopeNodes);
+    if (!ScopeNodes.size())
+      continue;
 
-    // To not alias, all of the nodes in Scopes must be in NANodes.
+    // To not alias, all of the nodes in ScopeNodes must be in NANodes.
     bool FoundAll = true;
-    for (const MDOperand &MDOp : Scopes->operands())
-      if (const MDNode *SMD = dyn_cast<MDNode>(MDOp))
-        if (AliasScopeNode(SMD).getDomain() == Domain)
-          if (!NANodes.count(SMD)) {
-            FoundAll = false;
-            break;
-          }
+    for (const MDNode *SMD : ScopeNodes)
+      if (!NANodes.count(SMD)) {
+        FoundAll = false;
+        break;
+      }
 
     if (FoundAll)
       return false;