[PATCH] D32252: [GVN] Add phi-translate for scalarpre as a temporary solution

[Daniel Berlin via llvm-commits]

On Mon, May 1, 2017 at 6:56 PM, Wei Mi <wmi at google.com> wrote:

> > This also needs compile time and performance measurements.
>
> I used spec2006 to do compile time testing. The compile time had a
> small increase.
>
> 400.perlbench       0.54%
> 401.bzip2              1.62%
> 403.gcc                 0.79%
> 429.mcf                 1.15%
> 433.milc                 0.24%
> 445.gobmk             0.71%
> 456.hmmer            0.26%
> 458.sjeng              -0.53%
> 462.libquantum     0.22%
> 464.h264ref          -0.18%
> 470.lbm                 0.86%
> 482.sphinx3           -1.01%
> 998.specrand        -2.35%
> 999.specrand        -3.45%
> 444.namd              0.46%
> 447.dealII              1.65%
> 450.soplex             0.92%
> 453.povray             0.88%
> 471.omnetpp          1.77%
> 473.astar                1.23%
> 483.xalancbmk       1.33%
>
> However, the compile time increase is not caused by phiTranslate call,
> but caused by some data structure setting like numberingExpression map
> (I removed the phiTranslate call and the compile time increase is
> almost the same). I think that is because GVN is already a big compile
> time consumer (top3 according to
> http://lists.llvm.org/pipermail/llvm-dev/2016-November/107110.html),
> and even small increase in the existing cost will be reflected in the
> total compile time.
>
> Considering this is a temporary solution, is this compile time
> increase acceptable?
>

Are you willing to commit to solving it?

I'm generally going to be okay with increasing compile time a bit if the
same people are willing to commit to solving that, but less so if they just
want someone else to solve it later :)
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