How to use a fast scratchpad-RAM for fill/spill ?

[Daniel Jacobowitz]

On Wed, May 11, 2005 at 11:31:51AM -0700, Greg McGary wrote:
> I have a port for a multi-processor with high-latency memory accesses,
> even for cache hits.  Each CPU core has a small private scratchpad RAM
> with 1 cycle access.  I'd like to persuade GCC to use the scratchpad
> (I'll probably allocate somewhere between 8 and 32 words) for reload,
> rather than stack slots which have much higher latency.  I have some
> ill-formed ideas about how to do this, which could involve describing
> these as another class of register, only movable in/out of general
> registers.  I'm still trying to understand secondary-reload well
> enough to determine if that's the mechanism I want.

Yes, that's one way to do it.  Or you could try telling the entire
compiler to treat them as registers, instead of just reload.  That's
likely to work as well or better.

-- 
Daniel Jacobowitz
CodeSourcery, LLC