Re: Unifying the x86 FPU register sets

[jtc at redback dot com (J.T. Conklin)]

>>>>> "Jim" == Jim Blandy <jimb@cygnus.com> writes:
Jim> I propose making the register file section of tm-i386.h, from which
Jim> everyone inherits, read as shown below.  Given this, we can write an
Jim> i387-tdep.c that actually has some meat to it.  Some comments:

Jim> - I have not included support for the MMX or 3DNow! registers.  Since
Jim>   they're superimposed on the FPU registers, it's not clear how best
Jim>   to provide access to them.  I want to leave that for a separate
Jim>   discussion.

I wanted to discuss this, at least a little bit, before we get too far
ahead of ourselves.

At present, we have contiguous sets of registers that are supersets of
each other.  What I mean by this is that the base X86 is 0 through 16;
an X86 with an FPU is 0 through 31; and an X86 with FPU with MMX and
SSE is 0 through 40.  But if we're going to support MMX registers as
GDB registers, we may want them placed between the FPU registers and
the SSE registers to keep this property.

I think we want to have the MMX registers be GDB registers, because if
they are only displayed as such with an 'info mmx' some such command
there will be no way to fetch/store the value of them in scripts.  

Does anyone have any experience with other X86 debuggers, emulators,
etc. that supports MMX?  How do they handle the MMX registers?

        --jtc

-- 
J.T. Conklin
RedBack Networks