GCC complains thusly: "attributes at the beginning of statement are ignored [-Werror=attributes]". Very well then! NFC

llvm-svn: 234788
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 11094e9..fb4c614 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -428,7 +428,7 @@
       II->setArgOperand(1, LHS);
       return II;
     }
-    [[clang::fallthrough]];
+    // fall through
 
   case Intrinsic::usub_with_overflow:
   case Intrinsic::ssub_with_overflow: {