On Wed, Sep 30, 2020 at 02:27:38PM +0200, Florian Weimer wrote:
> --- a/gcc/doc/invoke.texi
> +++ b/gcc/doc/invoke.texi
> @@ -29258,6 +29258,13 @@ of the selected instruction set.
> @item x86-64
> A generic CPU with 64-bit extensions.
>
> +@item x86-64-v2
> +@itemx x86-64-v3
> +@itemx x86-64-v4
> +These choices for @var{cpu-type} select the corresponding
> +micro-architecture level from the x86-64 psABI. They are only available
> +when compiling for a x86-64 target that uses the System V psABI@.
I think the documentation should state that these are not valid in -mtune=,
just in -march=, and that using -march=x86-64-v* will not change tuning.
I guess there should be some testsuite coverage for the for some unexpected
behavior of
-march=skylake -march=x86-64-v3
actually acting as
-march=x86-64-v3 -mtune=skylake
though perhaps it needs to be skipped if user used explicit -mtune= and
not sure how to actually test that (-fverbose-asm doesn't print -mtune=
when it is not explicit).
Jakub
