[llvm-dev] llvm emits unoptimized code

David Blaikie via llvm-dev llvm-dev at lists.llvm.org
Thu Oct 31 10:36:19 PDT 2019

Looks pretty similar to the GCC generated code - have you benchmarked this
code compared to something else hand-crafted to see if the tls_get_address
is measurably slow? (& I guess there's the possibility that the loop runs
zero times - in which case doing it outside the loop would be a
pessimization, potentially)

On Thu, Oct 31, 2019 at 8:49 AM kamlesh kumar via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi Devs,
> Consider testcase here
> https://godbolt.org/z/qHZzqw
> When optimization is O1 or above it produces unoptimized code
> because it calls __tls_get_address in loops.
> While with optimization disabled
> It produce single call to __tls_get_address outside of loop.
> is this a missed optimization by llvm?
> ./Kamlesh
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