[Vm-dev] [OpenSmalltalk/opensmalltalk-vm] CogVM source as per VMMaker.oscog-eem.2502 (f954a91)

Eliot Miranda eliot.miranda at gmail.com
Sat Jan 5 05:36:07 UTC 2019


Hi Tim, Hi Ken, Hi Doug,

On Wed, Jan 2, 2019 at 11:12 AM tim Rowledge <tim at rowledge.org> wrote:

>
> > On 2019-01-02, at 3:50 AM, Nicolas Cellier <notifications at github.com>
> wrote:
> >
> > But __ARM_ARCH_V8__ can run in 32 bits mode (aarch32) right?
> > So maybe we want to compile for V8, but not for 64bits (aarch64)...
>
> v8 is a completely different instruction set and you can't (to the best of
> my knowledge!) swap between v7 & v8. We don't (yet) have a cog for v8
> (trying to work on that).
>
> The stack VM does appear to work ok on v8 systems like chromebooks. We'll
> need to handle both v7 & v8 just as x86 & x64.
>

Currently the FFI tests don't test callbacks.  According to Ken's code for
the ThreadedFFIARM64Plugin the ARMv8 C ABI uses 8 integer register
parameters whereas ARMv7/6/5/4 uses 4.  So that changes the signature for
thunkEntry on ARMv8.  We won't see the effects of this unless we have a
callback test with more than 4 arguments.  We really need two tests that
call callbacks with no arguments, a few integer, float or double arguments,
large numbers of integer, float or double argument, and then calls with
alternating integer, float and double arguments.

Doug added a few tests when getting ThreadedFFIARMPlugin working.  This
source hans't made it back into sqFFITestFuncs.c.  This code could really
do with some love.  Someone willing to add a few tests, including some
callback tests.  I'm happy to write tip a description of the FFI
architecture if someone will volunteer to write those tests :-)

_,,,^..^,,,_
best, Eliot
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