[LLVMdev] Problem with regression tests using stderr

Bill Wendling isanbard at gmail.com
Tue Nov 20 19:01:25 PST 2007

On Nov 20, 2007, at 8:22 AM, Dan Gohman wrote:

> I was attempting to write a test that involves grepping though the
> stderr produced by opt -analyze, but found that my test was passing
> even before I fixed the bug I was writing the test for!
> I found that this one-line sure-fail test:
> ; RUN: echo hi |& false
> passes. I also tried 2>&1, because I've seen some tests do that,
> though that doesn't appear to work in this context either. It didn't
> seem to create a file nameed &1 though, as the LLVM test-writing
> documentation says.
> After some investigation, I believe the problem is due to the regexp
> on this line in test/lib/llvm.exp:
>       } elseif {[regexp {RUN: *([^&]+)(&&)?} $line match oneline  
> suffix]} {
> I don't understand what this is trying to do. What is intended by
> the special handling of && here?
> I found only one test that uses && on a RUN line,
> test/CodeGen/X86/2007-07-03-GR64ToVR64.ll, and it's not clear to
> me what it's doing there.
I think that it's a hold-over to how things used to be done. IIRC,  
you had to have the && at the end of the RUN line if you had another  
RUN line that needed to be executed. That's no longer the case, of  

If you want to catch stderr, there is one test doing that:


; RUN: llvm-as < %s | opt -analyze -scalar-evolution 2>&1 | grep  
"Loop bb:  100 iterations"


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