Re: Shrinking the C core

[Alfred M. Szmidt]

   > From: "Alfred M. Szmidt" <ams@gnu.org>
   > Cc: incal@dataswamp.org, emacs-devel@gnu.org
   > Date: Sun, 20 Aug 2023 14:54:43 -0400
   > 
   >    >    Does not look too bad in terms of the number of instructions. And 
I do
   >    >    not see any obvious indirection. 
   >    >
   >    > The Emacs VM will incure a switch to C for each call, SBCL doesn't.
   >    > You really cannot see the difference that makes?
   > 
   >    May you elaborate what you mean by "switch to C"?
   >    Emacs VM is running in C already.
   > 
   > How does the decoding of bytecode to C happen?  

   It doesn't.  bytecode.c is already written in C.

Tardy wording on my side, Emacs has to loop over the byte code to
execute it, and then maybe call C or Lisp depending.  While SBCL will
compile everything to whatever the target architecture is -- so no
bytecode is involved, and that (small) indirection is avoided since it
all becomes a normal function call.