[PATCH] libstdc++: testsuite: reduce max_size_type.cc exec time [PR113175]

[Jonathan Wakely]

On Tue, 2 Jan 2024, 17:49 Patrick Palka, <ppalka@redhat.com> wrote:

> Tested on x86_64-pc-linux-gnu, does this look OK for trunk and release
> branches (r14-205 was backported everywhere)?
>

Yes, thanks.



> -- >8 --
>
> The adjustment to max_size_type.cc in r14-205-g83470a5cd4c3d2
> inadvertently increased the execution time of the test by over 5x due to
> enabling the two main loops to actually run in the signed_p case instead
> of being dead code.  This suggests that the current range of the loop is
> far too big and the test too time consuming, especially when run on
> simulators.
>
> So this patch cuts the loop range by 10x as proposed in the PR.  This
> shouldn't significantly weaken the test since the same important edge
> cases are still checked in the new range.  On my x86_64 machine this
> reduces the test execution time by 10x, and 1.6x less time than before
> r14-205.
>
>         PR testsuite/113175
>
> libstdc++-v3/ChangeLog:
>
>         * testsuite/std/ranges/iota/max_size_type.cc (test02): Reduce
>         'limit' to 100 from 1000 and adjust 'log2_limit' accordingly.
>         (test03): Likewise.
> ---
>  libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
> b/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
> index a1fbc3241dc..27f25c758fe 100644
> --- a/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/iota/max_size_type.cc
> @@ -199,8 +199,8 @@ test02()
>    using max_type = std::conditional_t<signed_p, max_diff_t, max_size_t>;
>    using shorten_type = std::conditional_t<shorten_p, hw_type, max_type>;
>    const int hw_type_bit_size = sizeof(hw_type) * __CHAR_BIT__;
> -  const int limit = 1000;
> -  const int log2_limit = 10;
> +  const unsigned limit = 100;
> +  const int log2_limit = 7;
>    static_assert((1 << log2_limit) >= limit);
>    const int min = (signed_p ? -limit : 0);
>    const int max = limit;
> @@ -257,8 +257,8 @@ test03()
>    using max_type = std::conditional_t<signed_p, max_diff_t, max_size_t>;
>    using base_type = std::conditional_t<toggle_base_p, hw_type, max_type>;
>    constexpr int hw_type_bit_size = sizeof(hw_type) * __CHAR_BIT__;
> -  constexpr int limit = 1000;
> -  constexpr int log2_limit = 10;
> +  constexpr unsigned limit = 100;
> +  constexpr int log2_limit = 7;
>    static_assert((1 << log2_limit) >= limit);
>    const int min = (signed_p ? -limit : 0);
>    const int max = limit;
> --
> 2.43.0.232.ge79552d197
>
>
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