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From: srg@quick.COM (Spencer Garrett)
Newsgroups: comp.arch
Subject: MIPS register handling question
Message-ID: <166@quick.COM>
Date: Sun, 15-Nov-87 04:25:51 EST
Article-I.D.: quick.166
Posted: Sun Nov 15 04:25:51 1987
Date-Received: Mon, 16-Nov-87 04:13:19 EST
Organization: Quicksilver Engineering, Seattle
Lines: 18

I haven't seen one of these beasts, but I understand they have a single
large register pool which their compiler allocates as needed to procedures.
The idea sounded intriguing at first, but on closer examination I can't
see how to avoid acting like a vax (i.e. - save the regs you're going
to use at procedure entry and restore them at exit).  Here are several
specific questions I hope someone can answer, or maybe someone at MIPS
could post a short "here's how we do it" article.

1) If you're going to have object libraries, then it would have to be
the linker that really allocates the registers.  How does it handle
running out of registers? (since it's too late to generate code that
uses fewer or saves the ones it needs)

2) How does the compiler deal with recursion?

3) How does the register allocator (compiler or linker) handle computed
calls, since it can't generate a static call tree at all in this case?
(i.e. - calls of the form    (*pointer)(args);  )