#7411: Exceptions are optimized away in certain situations -------------------------------------+------------------------------------- Reporter: SimonHengel | Owner: tdammers Type: bug | Status: new Priority: high | Milestone: 8.6.1 Component: Compiler | Version: 7.6.1 Resolution: | Keywords: seq, deepseq, | evaluate, exceptions Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Incorrect result | Test Case: at runtime | simplCore/should_fail/T7411 Blocked By: | Blocking: Related Tickets: #5129 | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by tdammers): Replying to [comment:20 tdammers]:

Interestingly, the patch from #5129 does *not* fix this one too, so it's not just due to incorrectly optimizing `seq` away; there is more happening here.

Following the #5129 lead, I added some trace logging to the code touched in #5129; specifically I trapped this case: {{{ | SeqOp <- op -> all (expr_ok primop_ok) args }}} ...which is what caught the `seq#` instances that were inappropriately optimized away previously. However, for the offending examples, this trap doesn't fire, which means we're not hitting the `SeqOp` case at all. So apparently the `seq` call gets optimized away at an earlier stage. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/7411#comment:23 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler