PostgreSQLv14 TPC-H performance GCC vs Clang

Yes, currently focusing affects queries as well.
In meanwhile on analysis(hardware level) and sample examples noticed
1. GCC performance better than Clang on int128 .
2. Clang performance better than GCC on long long
the reference example
https://stackoverflow.com/questions/63029428/why-is-int128-t-faster-than-long-long-on-x86-64-gcc

3.GCC enabled with “ fexcess-precision=standard” (precision cast for
floating point ).

Is these 3 points can make performance difference GCC vs Clang in
PostgreSQLv14 in Apple/AMD/()environment(intel environment need to check).
In these environment int128 enabled wrt PostgreSQLv14.

On Friday, November 5, 2021, Tomas Vondra <tomas(dot)vondra(at)enterprisedb(dot)com>
wrote:

> Hi,
>
> IMO this thread provides so little information it's almost impossible to
> answer the question. There's almost no information about the hardware,
> scale of the test, configuration of the Postgres instance, the exact build
> flags, differences in generated asm code, etc.
>
> I find it hard to believe merely switching from clang to gcc yields 22%
> speedup - that's way higher than any differences we've seen in the past.
>
> In my experience, the speedup is unlikely to be "across the board". There
> will be a handful of affected queries, while most remaining queries will be
> about the same. In that case you need to focus on those queries, see if the
> plans are the same, do some profiling, etc.
>
>
> regards
>
> --
> Tomas Vondra
> EnterpriseDB: http://www.enterprisedb.com
> The Enterprise PostgreSQL Company
>