[PATCH] D12350: FastISel: Avoid adding a successor block twice for degenerate IR.

[Paul Robinson via llvm-commits]

probinson added a subscriber: probinson.
probinson added a comment.

I should think that if the input IR is legal, LLVM must not crash.  Therefore, ultimately this defensive patch seems appropriate.

But this patch is in response to PR24581, which is about a function with 'optnone' attribute.  The goal of optnone is to approximate -O0 even if you didn't say -O0.  If optnone is running something it should not, or failing to run something it really should, it's worth knowing.  The set of transformations that 'optnone' turns off was determined in a very ad-hoc way and it's *very* possible that there's a missing or extra check somewhere.  I'd like to see some kind of description of how the IR got into this state (or failed to get out of it).


Repository:
  rL LLVM

http://reviews.llvm.org/D12350