On Tue, 2015-05-26 at 13:57 +0000, David Laight wrote: > From: Scott Wood ... > > > I'd also have thought that the 64bit C version above would be > > > generally 'good'. > > > > It doesn't generate the addc/addze sequence. At least with GCC > > 4.8.2, > > it does something like: > > > > mr tmp0, csum > > li tmp1, 0 > > li tmp2, 0 > > addc tmp3, addend, tmp0 > > adde csum, tmp2, tmp1 > > add csum, csum, tmp3 > > I was thinking of all 64bit targets, not 32bit ones.
Oh, you mean move it out of arch/powerpc? Sounds reasonable, but someone should probably check what the resulting code looks like on other common arches. OTOH, if we're going to modify non-arch code, that might be a good opportunity to implement Segher's suggestion and move to a 64-bit accumulator. -Scott -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
