[Bug rtl-optimization/96388] scheduling takes forever with -fPIC

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96388

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |amker at gcc dot gnu.org

--- Comment #13 from Martin Liška <marxin at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #10)
> The partially reduced (In reply to Martin Liška from comment #9)
> > Created attachment 48962 [details]
> > Partially reduced test-case
> > 
> > The reduction is quite stuck at this point.
> 
> No longer keys on -fPIC though, so the bisection for this is likely wrong.

You are right, without the -fPIC argument, for 1GB memory limit, first bad is:
r5-4790-g43722f9fa69d4cc9

where the previous revision only needs ~190MB.


> -fno-schedule-insns2 improves it from 18s to 5s compile time and from
> 1.1GB of peak RSS to 320MB.
> 
>  scheduling 2                       :  12.69 ( 71%)   0.10 ( 67%)  12.79 (
> 70%)   11128 kB ( 16%)
> 
> -fmem-report doesn't show anything interesting, looking for heap allocations
> now to find the offender.
> 
> Can you bisect your reduced testcase again?  GCC 8.4 behaves the same for it
> rather than being good but GCC 4.8.5 is fine.