On 08/21/2017 10:11 PM, Alan Modra wrote: > On Mon, Aug 21, 2017 at 06:33:09PM +0100, Richard Sandiford wrote: >> I think it's worth emphasising that tying operands doesn't change >> whether an output needs an earlyclobber or not. E.g. for: > > Thanks for noticing this. It turns out that my OpenBLAS example > actually ought to have an early-clobber on one of the tied outputs, so > you've also alerted me to another bug in the power8 code. (Well, only > if the dgemv kernel was called directly from user code with a 16*N A > matrix, or I suppose if LTO was used.) So I now have a real-world > example of the situation where you need an early-clobber on tied > outputs, and also where an early-clobber is undesirable. > > Revised and expanded. > > * doc/extend.texi (Extended Asm <Clobbers>): Rename to > "Clobbers and Scratch Registers". Add paragraph on > alternative to clobbers for scratch registers and OpenBLAS > example. Also OK. I think you had a minor revision on this which is OK as well. I never would have spotted the additional earlyclobber requirement.
jeff
