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From: rfg@MCC.COM (Ron Guilmette)
Newsgroups: gnu.gcc
Subject: question on parm passing in regs
Message-ID: <8905182218.AA12401@riunite.aca.mcc.com>
Date: 18 May 89 22:18:05 GMT
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I have just noticed that the tm-sparc.h file allows for
function parameters to be passed via registers, but it
does *not* allow parameters (no matter what their type)
to be passed via the floating point registers.

This gives rise to two questions.

First, is the tm-sparc.h file just obeying existing
conventions?

Second, regardless of whether or not the tm-sparc.h file
reflects the existing (Sun mandated) conventions, doesn't
this seem wasteful?  It seems that this would be especially
wasteful whenever you had some function calls like:

	calculate_something (x1+y1, x2+y2);

where the values of the parameters had to be calculated into
the floating-point registers just before the call anyway.

It there some secret reason that I don't know about which
makes it inadvisable to pass floating-point parameters in
floating-point registers?

// Ron Guilmette  -  MCC  -  Experimental Systems Kit Project
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