SPECjbb X86 validation failures
Andrew Haley
aph@cambridge.redhat.com
Thu Apr 25 03:03:00 GMT 2002
Boehm, Hans writes:
> I'm unfortunately still seeing problems with SPECjbb on X86 with gcc3.1.
> These are apparently optimization failures. They don't seem to be
> correlated with the reload1.c ICEs that I mentioned earlier.
>
> I know that:
>
> - They occur at -O1 and -O2, but not at -O0.
>
> - The result is incorrect code, which is detected by the SPECjbb validation
> test.
>
> - More than one file in SPECjbb is misoptimized as a result.
>
> - They do not occur on IA64.
>
> I've identified one file that's definitely being misoptimized (by binary
> search). Are there known techniques for systematically narrowing this down
> further? I'm looking for something like a list of optimization flags
> implied by -O1 that I can toggle individually,
Use -fverbose-asm. A list of all the optimizations applies is in the
asm file.
> and ideally a flag to turn off optimization in all functions past
> line N, or something similar.
Ah, that's much harder. I guess you have a licence for SPECjbb and we
don't, so I can't look at it?
> The underying problem here is that this is a fairly large body of code,
> which I don't understand well. Thus tracking down a bug is hard, and
> tracking down a misoptimization is harder.
It is, and it takes time to understand how to fix optimizer bugs.
Andrew.
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