Re: GC and simple smobs??

[Jean Abou Samra]

Le 21/06/2022 à 13:21, David Kastrup a écrit :
> Jean Abou Samra <jean@abou-samra.fr> writes:
>
> > To check that, I applied
> >
> > diff --git a/lily/duration-scheme.cc b/lily/duration-scheme.cc
> > index 5d9b4447f1..6a09253adf 100644
> > --- a/lily/duration-scheme.cc
> > +++ b/lily/duration-scheme.cc
> > @@ -45,6 +45,8 @@ Is @var{p1} shorter than @var{p2}?
> >     auto *const a = LY_ASSERT_SMOB (Duration, p1, 1);
> >     auto *const b = LY_ASSERT_SMOB (Duration, p2, 2);
> >
> > +  scm_gc ();
> > +
> >     if (Duration::compare (*a, *b) < 0)
> >       return SCM_BOOL_T;
> >     else
> >
> > and compiled
> >
> > #(do ((i 0 (1+ i)))
> >     ((= i 100))
> >     (ly:duration<? #{ 4 #} #{ 8 #}))
> >
> >
> > No crashes observed.
> That tells you nothing at all unless you verify that the generated code
> writes over p1 and p2 before scm_gc is called.  This is possible due to
> optimisation but unlikely.


<facepalm> Correct. Next try:

diff --git a/lily/duration-scheme.cc b/lily/duration-scheme.cc
index 5d9b4447f1..be75c6ac9d 100644
--- a/lily/duration-scheme.cc
+++ b/lily/duration-scheme.cc
@@ -45,6 +45,11 @@ Is @var{p1} shorter than @var{p2}?
   auto *const a = LY_ASSERT_SMOB (Duration, p1, 1);
   auto *const b = LY_ASSERT_SMOB (Duration, p2, 2);

+  p1 = SCM_UNDEFINED;
+  p2 = SCM_UNDEFINED;
+
+  scm_gc ();
+
   if (Duration::compare (*a, *b) < 0)
     return SCM_BOOL_T;
   else


Does that look better?