Subject: Re: How much tuning does regular lisp compilers do?
From: rpw3@rpw3.org (Rob Warnock)
Date: Sun, 31 Aug 2008 06:57:53 -0500
Newsgroups: comp.lang.lisp
Message-ID: <s72dnZxH2JTcGifVnZ2dnUVZ_rTinZ2d@speakeasy.net>
Bakul Shah  <bakul+usenet@bitblocks.com> wrote:
+---------------
| Rob Warnock wrote:
| > Bakul Shah  <bakul+usenet@bitblocks.com> wrote:
| > You don't want to have to force conses to 16-byte boundaries,
| > since on a 32-bit machine that would *double* the space taken
| > by them [though on 64-bit it's a no-brainer],
| 
| I am lost. What does consing have to do with loops? I am only
| talking about aligning loops (as part of some compiled code).
+---------------

And I was talking about needing to *maintain* that alignment
when a copying GC copies such an aligned code block.

But as Thomas Burdick said in a parallel reply, I may have
been trying too hard to save a few bytes when I suggested
partitioning the heap. In fact, when copying a code object,
if you simply allow the GC to waste 8 bytes if it needs to
for maintaining alignment, that should be "good enough".


-Rob

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