[llvm-dev] [RFC] Switching to MemorySSA-backed Dead Store Elimination (aka cross-bb DSE)

[Michael Kruse via llvm-dev]

Thank you for the performance numbers. IMHO they justify switching to
MSSA-DSE for all configuration even with slight compile time regressions.

Michael

Am Mi., 19. Aug. 2020 um 09:37 Uhr schrieb Florian Hahn <
florian_hahn at apple.com>:

>
>
> > On Aug 18, 2020, at 22:14, Florian Hahn via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
> >
> >
> >
> >> On Aug 18, 2020, at 16:59, Michael Kruse <llvmdev at meinersbur.de> wrote:
> >>
> >> Thanks for all the work. The reductions in stores look promising. Do
> you also have performance numbers how much this improves the execution
> time? Did you observe any regressions where MSSA resulted in fewer removed
> stores?
> >
> > I did not gather numbers for execution time yet, but I’ll try to share
> some tomorrow.
>
>
> Here are some execution time results for ARM64 with -O3 -flto with the
> MemorySSA-DSE compared against the current DSE implementation for CINT2006
> (negative % means reduction in execution time with MemorySSA-DSE). This
> excludes small changes within the noise (<= 0.5%)
>
>
> Exec_time  number of stores removed
>  test-suite...T2006/456.hmmer/456.hmmer.test   -1.6%.     + 70.8%
>  test-suite.../CINT2006/403.gcc/403.gcc.test       -1.4%.     + 35.7%
>  test-suite...0.perlbench/400.perlbench.test         -1.2%.     + 33.2%
>  test-suite...3.xalancbmk/483.xalancbmk.test      -1.0%.     + 3.02%
>  test-suite...T2006/401.bzip2/401.bzip2.test        -0.8%.     + 70.6%
>
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