[llvm-dev] Proposal: introduce dependency on abseil when building benchmarks

[Tom Stellard via llvm-dev]

On 10/7/21 9:49 AM, Mircea Trofin wrote:
> 
> 
> On Thu, Oct 7, 2021 at 9:47 AM Tom Stellard <tstellar at redhat.com <mailto:tstellar at redhat.com>> wrote:
> 
>     On 9/30/21 10:07 AM, Mircea Trofin via llvm-dev wrote:
>      > TL;DR; When either of LLVM_BUILD_BENCHMARKS or LIBCXX_INCLUDE_BENCHMARKS are enabled, as well as for llvm-test-suite, a dependency to abseil would either be auto-downloaded by the build system, or need to be user-specifiable, or provided in the source tree.
>      >
>      > Details
>      >
>      > There are (afaik) 3 copies of the google/benchmark <https://github.com/google/benchmark <https://github.com/google/benchmark>> project in the llvm tree: in llvm-test-suite, in llvm/utils, and in libcxx/utils/.
>      >
>      > The benchmark code uses some functionality otherwise offered by abseil <https://abseil.io/ <https://abseil.io/>>. Over time, this is inconvenient: continued need for duplication for some features; integration issues in projects using abseil due to macro conflicts; and overall bit rot / maintenance overhead.
>      >
>      > We want <https://github.com/google/benchmark/pull/1183 <https://github.com/google/benchmark/pull/1183>> to add a dependency to abseil to the benchmarks project.
>      >
>      > Abseil has some requirements <https://abseil.io/docs/cpp/platforms/platforms#:~:text=Abseil%20requires%20a%20code%20base,14%20through%20C%2B%2B20) <https://abseil.io/docs/cpp/platforms/platforms#:~:text=Abseil%20requires%20a%20code%20base,14%20through%20C%2B%2B20)>.> that may not perfectly match those of the impacted projects. For example, abseil stopped supporting Ubuntu 14.04 before its TLS.
>      >
> 
>     Does this mean it would no longer be  possible to build the test-suite
>     on any architecture besides x86_64, aarch64, and arm?
> 
> *if* there's a desire to keep in sync automatically with the upstream benchmark suite (which we don't currently do)
> 

Ok, where in the test-suite is this code?

-Tom

> 
> 
>     -Tom
> 
>      > Naturally, projects snap to whichever version of benchmark they want to; but this new dependency would add an extra consideration when considering updating the version of benchmarks; and the need to handle the extra dependency (either by being OK with it being auto-downloaded, or via the other means described above)
>      >
>      > Are there any other issues that we're missing? Would anyone be hindered by this adoption of abseil in google/benchmarks?
>      >
>      > Thanks,
>      > Mircea.
>      >
>      >
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