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Re: How to use a fast scratchpad-RAM for fill/spill ?
- From: Daniel Jacobowitz <drow at false dot org>
- To: Greg McGary <greg at mcgary dot org>
- Cc: gcc at gcc dot gnu dot org
- Date: Wed, 11 May 2005 14:34:53 -0400
- Subject: Re: How to use a fast scratchpad-RAM for fill/spill ?
- References: <mszmv1lilk.fsf@mcgary.org>
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