should not be marked nounwind.
Marking them nounwind caused crashes in the WebKit FTL JIT, because if we enable
sufficient optimizations, LLVM starts eliding compact_unwind sections (or any unwind
data for that matter), making deoptimization via stackmaps impossible.
This changes the stackmap intrinsic to be may-throw, adds a test for exactly the
sympton that WebKit saw, and fixes TableGen to handle un-attributed intrinsics.
Thanks to atrick and philipreames for reviewing this.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201826 91177308-0d34-0410-b5e6-96231b3b80d8