Re: Proposal for handling large numbers of registers

[jtc@redback.com (J.T. Conklin)]

>> So I'm considering importing the idea of "register classes" from
>> GCC.  GCC uses the class idea to guide allocation and instruction
>> selection, but we don't even need that much; just define the names
>> of the classes and which registers belong to each.

> It would be nice if one could just cut the register class
> definitions from gcc tm.h and paste them into gdb tm.h.

I'm not sure that a compilers notion of register classes make sense
for debugging and vice versa.  For debugging, broad categories like
"integer registers", "floating point registers", "system registers"
seem to be most appropriate; while compilers think of classes like
"registers that can be used for indexing", "special register used
for integer divide instructions", etc.

        --jtc

-- 
J.T. Conklin
RedBack Networks
From m.hayes@elec.canterbury.ac.nz Fri Aug 06 18:36:00 1999
From: Michael Hayes <m.hayes@elec.canterbury.ac.nz>
To: jtc@redback.com
Cc: Michael Hayes <m.hayes@elec.canterbury.ac.nz>, Stan Shebs <shebs@cygnus.com>, gdb@sourceware.cygnus.com
Subject: Re: Proposal for handling large numbers of registers
Date: Fri, 06 Aug 1999 18:36:00 -0000
Message-id: <14251.35343.506647.777893@ongaonga.elec.canterbury.ac.nz>
References: <199908062333.QAA16667@andros.cygnus.com> <14251.31513.361599.969792@ongaonga.elec.canterbury.ac.nz> <5mwvv82xei.fsf@jtc.redbacknetworks.com>
X-SW-Source: 1999-q3/msg00125.html
Content-length: 679

J.T. Conklin writes:
 > I'm not sure that a compilers notion of register classes make sense
 > for debugging and vice versa.  For debugging, broad categories like
 > "integer registers", "floating point registers", "system registers"
 > seem to be most appropriate; while compilers think of classes like
 > "registers that can be used for indexing", "special register used
 > for integer divide instructions", etc.

For most targets I have looked at, these other classes you mention are
usually sub-classes of the "integer registers", "fp registers", etc.
However, I can see from most user's perspectives that they will not be
interested in these special sub-classes.

Michael.