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Re: [patch] PR33600, fallout from pr33552 fix
On Mon, Oct 01, 2007 at 05:46:01PM +0200, Michael Matz wrote:
> So, I rather leave in the harmless short-living code pessimization which
> will be magically fixed by coalescing, instead of reducing the number of
> cases where this transformation applies. I hold off committing the patch
> for now nevertheless to hear your opinion about the above.
If you think RA's coalescing will fix this up, then why not do this
optimization through creating a new pseudo and only replacing the
input/output pair that needs it?
asm ("... " : "=r" (i) : "0" (j), "r" (j));
this would add
(set (reg temp_pseudo) (reg j))
asm ("... " : "=r" (temp_pseudo) : "0" (temp_pseudo), "r" (j));
(set (reg i) (reg temp_pseudo))