FunctionAttrs: Skip it if the effective SCC (ignoring optnone functions) is empty

Minor optimization but mostly simplifies my debugging so I'm not dealing
with empty SCCNodeSets while investigating issues in this optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304597 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index 28cc81c76d4fb08f71d2016b2096f60e5be492af..5cc29a49379869e6c808ac2916b4be55e863d45d 100644 (file)
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -1188,6 +1188,10 @@ static bool runImpl(CallGraphSCC &SCC, AARGetterT AARGetter) {
     SCCNodes.insert(F);
   }
 
+  // Skip it if the SCC only contains optnone functions.
+  if (SCCNodes.empty())
+    return Changed;
+
   Changed |= addArgumentReturnedAttrs(SCCNodes);
   Changed |= addReadAttrs(SCCNodes, AARGetter);
   Changed |= addArgumentAttrs(SCCNodes);