[LLVMdev] Named register variables GNU-style, deux

[Richard Sandiford]

Thanks for the excellent write-up.  Just wanted to clarify...

Austin Seipp <aseipp at pobox.com> writes:
> Recently on this list (as of last month), Renato Golin of Linaro
> posted a thread entitled "Named register variables, GNU-style"[1].
> This thread concerned the implementation of the GNU Register variables
> feature for LLVM. I'd like to give some input on this, as a developer
> of the Glasgow Haskell Compiler, as we are a user of this feature.
> Furthermore, our use case is atypical - it is efficiency oriented, not
> hardware oriented (e.g. I believe the Linux APIC x86 subsystem uses
> them for hardware, as well as MIPS Linux as mentioned).

The MIPS case sounds pretty similar to yours: it sets aside a specific
GPR to hold thread-local information.  The main difference is that MIPS
Linux was in the lucky position of being able to use a nonallocatable
GPR, since $gp ($28) is normally reserved for ABI features that Linux
doesn't need.

Thanks,
Richard