Re: Please revert b2e843161d

> On 25 Jun 2026, at 19:32, Steve Kargl <kargls@comcast.net> wrote:
> 
> On 6/25/26 10:57, Andrew Turner wrote:
>> I don’t expect it to work on amd64 in the general case. Godbolt shows both GCC and Clang generating an infinite loop jumping to its self [1]. It may work on some architecture levels, however I don’t know enough about amd64 to know if it’s safe to enable.
>> The USE_BUILTIN_* flags aren’t intended on being set by users as you found.
> 
> The comment in the source code certainly does not alert a
> user to not use -DUSE_BUILTIN_FMAF (or any of the other
> USE_BUILTIN_*).

> 
> Architecture specific code should be in msun/arm/.  It would
> also seem to me that if this is indeed arm specific then
> it should be guarded with "#if defined(__ARM) && …”

Other architectures could use this if they have a simple instruction sequence that the compiler uses. I know about arm64 so am comfortable enabling it there, but not on other architectures I don’t use.

Andrew