[RS4GC] Dont' propagate call attrs related to patchable statepoints

The `"statepoint-id"` and `"statepoint-num-patch-bytes"` attributes are
used solely to determine properties of the `gc.statepoint` being
created.  Once the `gc.statepoint` is in place, these should be removed.

llvm-svn: 250491
diff --git a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
index de6e8b5..ca92b14 100644
--- a/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
+++ b/llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
@@ -1290,6 +1290,13 @@
             Attr.hasAttribute(Attribute::ReadOnly))
           continue;
 
+        // These attributes control the generation of the gc.statepoint call /
+        // invoke itself; and once the gc.statepoint is in place, they're of no
+        // use.
+        if (Attr.hasAttribute("statepoint-num-patch-bytes") ||
+            Attr.hasAttribute("statepoint-id"))
+          continue;
+
         Ret = Ret.addAttributes(
             AS.getContext(), Index,
             AttributeSet::get(AS.getContext(), Index, AttrBuilder(Attr)));