[m-rev.] diff: use global registers on aarch64
jfischer at opturion.com
Wed Jan 13 20:34:06 AEDT 2021
On Wed, 13 Jan 2021, Zoltan Somogyi wrote:
> 2021-01-13 14:03 GMT+11:00 "Julien Fischer" <jfischer at opturion.com>:
>> The diff below is sufficient to allow Mercury to bootcheck in grade
>> reg.gc on my aarch64 Linux system.
> That's great.
> BTW, how did you *get* an aarch64 linux system?
I'm building it on my Chromebook for the moment, although the end game
here is to be able to run stuff on AWS's Graviton 2 based instances.
>> Compile with -fomit-frame-pointer on aarch64.
> I see no evidence of this in the diff to configure.ac.
@@ -2420,10 +2420,11 @@ case "$ac_cv_prog_gcc" in yes)
- # The test for GCC labels goes into a loop on AArch64.
+ # The test for GCC labels goes into a loop on AArch64.
MERCURY_MSG("gcc labels do not work on AArch64")
>> (Doing so, frees
>> up register x29.)
> Nor do I see any reference to x29 in aarch64_regs.h.
It frees it up for use by GCC, we don't use it as a global register
variable. It will be used to hold the frame pointer unless we compile
We could potentially use more global registers on aarch64 -- there are
plenty of callee-save registers available. That said, I seem to recall
having more than handful not having much benefit when we experimented
with the x86_64 and powerpc ports.
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