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Re: changing fp insns to parallels...
- To: Richard Henderson <rth at cygnus dot com>
- Subject: Re: changing fp insns to parallels...
- From: Michael Hayes <m dot hayes at elec dot canterbury dot ac dot nz>
- Date: Wed, 14 Apr 1999 18:11:39 +1200 (NZST)
- Cc: Jan Hubicka <hubicka at atrey dot karlin dot mff dot cuni dot cz>, egcs at egcs dot cygnus dot com
- References: <19990412130624.36622@atrey.karlin.mff.cuni.cz><19990413223547.A23366@cygnus.com>
Richard Henderson writes:
> My favorite representation at the moment is to expose the
> extra-architectual fp stack pointer to the compiler, and use a
> new rtx `indreg' to indicate indirection on a register as opposed
> to a memory. Pushes and pops are easiest to represent as
> PRE_INC/POST_DEC.
I like this approach since it describes to GCC what the hardware is
doing, however, I would prefer a more general mechanism than indreg to
handle alternate memory spaces (like the x86 floating point register
stack). Maybe a new rtx like `altmem' or even something like `mem2'
which has a second const int argument indicating the memory space for
processors that support multiple memory spaces.
Michael.