By: -.- (blarg.delete@this.mailinator.com), May 23, 2022 4:23 am
Room: Moderated Discussions
Doug S (foo.delete@this.bar.bar) on May 22, 2022 10:57 am wrote:
> I would assume the first step in deprecating NEON (if that was the plan) would
> be to require SVE2 or some successor spec. SVE2 remains optional in ARMv9.
On GCC and Clang,
ARM have been less afraid to drop support for old ISAs/extensions (like AArch32), unlike x86. Given NEON's prevalence, it'll likely stay around for quite some time, and given the markets ARM is now in (or entering into), they probably can't drop backwards compatibility as much as they used to. But SVE was designed with no reliance on NEON, so it's possible the latter will slowly be phased out over many years.
> I would assume the first step in deprecating NEON (if that was the plan) would
> be to require SVE2 or some successor spec. SVE2 remains optional in ARMv9.
On GCC and Clang,
-march=armv9-a is an alias for -march=armv8.5-a+sve2, so assuming they're correct, it sounds like SVE2 is as "optional" on ARMv9 as NEON is "optional" on ARMv8. (i.e. "opt-out optional")ARM have been less afraid to drop support for old ISAs/extensions (like AArch32), unlike x86. Given NEON's prevalence, it'll likely stay around for quite some time, and given the markets ARM is now in (or entering into), they probably can't drop backwards compatibility as much as they used to. But SVE was designed with no reliance on NEON, so it's possible the latter will slowly be phased out over many years.
