[Chicken-hackers] [PATCH] Simplify forwarding pointer wrapping and unwrapping

[Peter Bex]

Hi all,

While looking at the GC bug I already posted a patch for, I noticed that
forwarding pointers are constructed in a bit of a roundabout way, and
this could be simplified purely for readability reasons.

I tested the attached patch on x86_64 as well as 32-bit PowerPC and
nothing breaks.  Unfortunately, it doesn't make any difference in
performance - I had hoped GCs would be sped up a bit due to less
instructions being needed to create the forwarding pointers.

In case you're wondering if there's a reason for why it's done in the
way it's done, we can check the original commit in which it changed
from a simple setting of the top bit to the current code:

cvs -d:pserver:anonymous:@cvs.sv.nongnu.org:/cvsroot/chicken rlog -r1.55 
chicken/runtime.c 
cvs -d:pserver:anonymous:@cvs.sv.nongnu.org:/cvsroot/chicken rdiff -r1.55 
chicken/runtime.c 

I also added a comment to the code to (hopefully) clarify what's going
on in these macros.

Cheers,
Peter

0001-Simplify-forwarding-pointer-wrapping-unwrapping.patch
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