Hello all,
I'm seeing some very strange behaviour from `atomic-box-swap!` (but not
`atomic-box-compare-and-swap!`) on Guile 3.0.9 from Homebrew on OSX
Sonoma using an M3 Pro cpu. The issue does not seem to manifest on
x86_64. Could it be some interaction between Guile and M3 CPUs?
Or am I ju
A small bit of extra information: it's not just one machine; the problem
also manifests on an M1 running OSX 14.1.1. In addition, it happens with
newer Guile versions including `guile-next` from `aconchillo`'s Homebrew
tap and including a version I built from Guile git main just now.
Regards,
I'm not sure why, exactly, but I needed this to get builds to work on
OSX Sonoma at all.
---
libguile/scmsigs.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/libguile/scmsigs.c b/libguile/scmsigs.c
index 7fd3fd8f1..be96dbd5c 100644
--- a/libguile/scmsigs.c
+++ b/libguile/s
This appears to make the problem go away. I'm new at working with
`lightening` so I'm not confident I've covered everything that needs
covering, particularly wrt the implementation of cas_atomic. But perhaps
this can be a foundation for someone who knows more than I do to work from.
---
libgu
As an alternative to changing the JIT to produce SWPAL/CASAL, because I
wasn't sure if *all* aarch64 targets support these, I tried adding DMB
ISH or DMB SY to the end of the generated code sequences. Surprisingly,
this did not fix the issue! So there's perhaps something fishy about the
LDAXR-S
Oh man. This little patch all by itself makes the problem behaviour go
away. No switching to SWPAL/CASAL, just tightening the spinloop. (And no
changes at all to the CAS code, so nothing to do with the fibers bug I
guess.)
With the patch, the spinloop goes LDAXR-STLXR-CBNZ (which is what GCC
Andy Wingo in IRC pointed out that the reason the patch appears to work
is that the `movr` isn't idempotent! By the time it comes round again,
`val` has already been overwritten by LDAXR in the case that `dst == val`.
On 22/04/2024 10:18, Tony Garnock-Jones wrote:
Oh man. This little patc
This is a nice idea. The way Racket does it is to make
with-output-to-string cooperate with system:
(with-output-to-string (lambda () (system "date")))
but a quick check shows that Guile does not yet have such cooperation in
place. Would that be a good place to start looking?
Tony
On 2
