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Re: rs6000 fused multiply-add patch [+ patchlet]
- From: David Edelsohn <dje at watson dot ibm dot com>
- To: Zack Weinberg <zack at codesourcery dot com>
- Cc: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner), segher at koffie dot nl, gcc-patches at gcc dot gnu dot org
- Date: Sun, 05 Jan 2003 21:24:22 -0500
- Subject: Re: rs6000 fused multiply-add patch [+ patchlet]
- References: <87n0mfgozb.fsf@egil.codesourcery.com>
I don't think that anyone is objecting to the concept and the
benefit. If I understand correctly, the patch violates the semantics of
the combiner algorithm which requires a declining cost calculated as the
number of instructions. Allowing combinations that do not decrease the
cost would make the algorithm non-deterministic and possibly not converge,
right?
David