[LLVMbugs] LICM Test Failure?

[Duncan Sands]

Hi Bill,

> Anyone seeing this failure in a fresh tree?

> Running /Users/wendling/llvm/test/Transforms/LICM/dg.exp ...
> FAIL: /Users/wendling/llvm/test/Transforms/LICM/scalar_promote.ll
> Failed with signal(SIGPIPE) at line 1
> while running: llvm-upgrade < /Users/wendling/llvm/test/Transforms/ 
> LICM/scalar_promote.ll | llvm-as | opt  -licm -stats |&  grep {memory  
> locations promoted to register}
> Binary file (standard input) matches
> child killed: write on pipe with no readers

I've been seen failures like this from time to time (not sure if it
was for this test).  I couldn't work out what was going on.  It smells
to me like one of the commands in the pipeline has exited before the
preceding command finished writing into the pipe, meaning it gets hit
with SIGPIPE.  The fact that this doesn't always happens makes me
suspect a race condition, for example when you do a fork does the
parent or child run first?  Answer: either, depending on the whim of
the OS.  On linux, I think it almost always used to be the child that
ran first, but in fact this was never reliable; that didn't stop some
programs (eg bash) relying on it anyway - though I understand this was
fixed in bash some time ago.  I wouldn't be surprised if something like
this was causing the problem you see.

Ciao,

Duncan.