Does 6.3.0 still use x18 in arm64 code?

Torbjörn Granlund tg at
Tue Oct 17 12:46:03 CEST 2023

Jay Freeman <jay_reynolds_freeman at> writes:

  I must respectfully beg your pardon and request clarification. I am
  contemplating adding bignum capabilities to an existing MacOS
  application (an R5 Scheme implementation, Wraith Scheme, which I wrote
  and maintain). It looks like it will require considerable time and
  effort sufficiently to master GMP to implement Scheme bignums using
  it, and because of the previous discussion concerning register x18, I
  have thus far avoided taking the plunge. Therefore I asked a yes/no
  question about whether it was reasonable for me to proceed. I suspect
  that Torbjörn's answer makes perfect sense to people already at least
  somewhat familiar with GMP, which -- alas -- I am not: Would someone
  please provide an answer simple enough for me to decide whether now is
  the time for me to join their ranks?

You can trust our release notes, which you quote from in your initial

  * Support for 64-bit Arm under Macos.

(That of course does not preclude the existence of GMP bugs which affect
the platform in question, but we have surely addressed the register
usage to adhere to the relevant ABI.)

Please encrypt, key id 0xC8601622

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