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Re: SPE configuration in GCC


David Edelsohn wrote:

	As Aldy mentioned, there already is a powerpc-linuxspe
configuration that seems to do what your customer wants.
gcc/config/rs6000/linuxspe.h makes the options active and defaults to a
8540 scheduling model, but does not enable the SPE features by default.

I don't think that's quite true. It seems to default to enabling SPE via SUBTARGET_OVERRIDE_OIPTIONS. It also passes "-mspe -me500" to the assembler unconditionally. Our customer wants SPE to be an option, not the default.


	I am wliling to consider a patch to rs6000.h and the other
headers, but I am not sure what benefit it provides over the
configurations that Aldy already designed and implemented.

I think that the best solution, then, is probably a new configuration header for this customer. That's easy enough to arrange. We've certainly established that the current situation is a conscious choice, which was my primary objective.


As a secondary issue, it would be nice to have a GCC-wide policy about whether "target-elf" should support all variants of a chip, or just some. Based on my knowledge of users, I'd suggest that it should support all variants.

As another secondary issue, I consider it a bug in the PowerPC back end that command-line options (like -misel) are silently ignored in the default configuration. If you agree, I can file a PR about that.

Thanks,

--
Mark Mitchell
CodeSourcery, LLC
mark@codesourcery.com
(916) 791-8304


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