On 10/12/2025 09:04, Kyrylo Tkachov wrote:
Hi all,
We've received reports from users confused about -mcpu=neoverse-v2 enabling
the RNG intrinsics by default, even though it is an optional feature in the
core and not implemented in their implementation.
We think it'd be cleaner to not enable it by default for -mcpu=neoverse-v2,
same as for -mcpu=grace. We'll also propose the change to Clang to keep
the two compilers consistent.
Bootstrapped and tested on aarch64-none-linux-gnu.
Ok for trunk if the Clang change is also agreed upon?
Signed-off-by: Kyrylo Tkachov <[email protected]>
gcc/
* config/aarch64/aarch64-cores.def (neoverse-v2): Remove RNG.
So the principle that we've normally applied is that (except for crypto)
optional features in the architecture are not enabled by default while
for CPUs optional features are enabled by default. The idea is that
it's much more obvious for users if something optional gets included (it
will show up quickly during debugging/execution), whilst missing a
feature can lead to poor performance when the feature isn't being
utilized - something that is not obvious during a test/debug run.
So I think this is inconsistent with our previous position.
R.
