[RewriteStatepointsForGC] Avoid inserting empty holder

We use dummy calls to adjust the liveness of values over statepoints in the midst of the insertion.  If there are no values which need held live, there's no point in actually inserting the holder.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234779 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index 47d6ffb..8c2cb35 100644 (file)
--- a/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1571,6 +1571,10 @@ static Function *getUseHolder(Module &M) {
 /// liftetime of the call.
 static void insertUseHolderAfter(CallSite &CS, const ArrayRef<Value *> Values,
                                  SmallVectorImpl<CallInst *> &holders) {
+  if (Values.empty())
+    // No values to hold live, might as well not insert the empty holder
+    return;
+
   Module *M = CS.getInstruction()->getParent()->getParent()->getParent();
   Function *Func = getUseHolder(*M);
   if (CS.isCall()) {