Drop @llvm.annotation and @llvm.ptr.annotation intrinsics during codegen.

The intrinsic calls are dropped, but the annotated value is propagated.

Fixes PR 15253

Original patch by Zeng Bin!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182387 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 4c6d028..c12cf52 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -5037,6 +5037,11 @@
     setValue(&I, Res);
     return 0;
   }
+  case Intrinsic::annotation:
+  case Intrinsic::ptr_annotation:
+    // Drop the intrinsic, but forward the value
+    setValue(&I, getValue(I.getOperand(0)));
+    return 0;
   case Intrinsic::var_annotation:
     // Discard annotate attributes
     return 0;