buildflags.md: Update downstream cpu and tuning choices

Related: RHEL-58074
This commit is contained in:
Siddhesh Poyarekar 2024-09-25 05:35:56 -04:00
parent 3c25b90657
commit b18b552478

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@ -608,20 +608,17 @@ tuning in the `gcc` package. These settings are:
instructs GCC to use the SSE2 unit for floating point math to avoid
excess precision issues. `-mstackrealign` avoids relying on the
stack alignment guaranteed by the current version of the i386 ABI.
* **ppc64le**: `-mcpu=power8 -mtune=power8` selects a minimum
supported CPU level of POWER8 (the first CPU with ppc64le support)
and tunes for POWER8.
* **s390x**: `-march=zEC12 -mtune=z13` specifies a minimum supported
CPU level of zEC12, while optimizing for a subsequent CPU generation
(z13).
* **x86_64**: `-mtune=generic` selects tuning which is expected to
beneficial for a broad range of current CPUs. Distribution-specific
defaults for `-march=x86-64-v2` or `-march=x86-64-v3` may be
applied. The default can be overriden (for any distribution)
by specifying `--target x86_64_v2`, `--target x86_64_v3`,
`--target x86_64_v4` in the `rpmbuild` invocation.
With the GCC toolchain, TLS descriptors are enabled using
`-mtls-dialect=gnu2`.
* **ppc64le**: `-mcpu=power9 -mtune=power10` selects a minimum
supported CPU level of POWER9 and tunes for POWER10.
* **s390x**: `-march=z14 -mtune=z15` specifies a minimum supported CPU
level of z14, while optimizing for a subsequent CPU generation
(z15).
* **x86_64**: `-march=x86-64-v3 -mtune=generic` builds for the
[x86-64-v3 micro-architecture level](https://gitlab.com/x86-psABIs/x86-64-ABI/-/blob/master/x86-64-ABI/low-level-sys-info.tex)
and selects tuning which is expected to beneficial for a broad range
of current CPUs.
With the GCC toolchain, TLS descriptors are enabled using
`-mtls-dialect=gnu2`.
* **aarch64** does not have any architecture-specific tuning.
### Vala-specific compiler flags