Re: [PATCH v2, middle end]: Fix PR 37908, thinko with atomic NAND operation

[Uros Bizjak <ubizjak at gmail dot com>]

David Daney wrote:

> > Attached (now for real :) patch corrects __sync nand intrinsics to
> > generate ~(target & val). The patch was tested on i686-pc-linux-gnu. I
> > propose to commit the patch, since all unfixed targets will fail fixed
> > sync tests and after all targets are fixed, we can backport complete
> > patch to release branches and  add the note to release notes.
>
> What is the motivation for getting this into 4.4 two days before the 
> end of stage3?  It makes it more difficult for the maintainers of the 
> ports you don't fix to have clean test results for 4.4.

The motivation is, that the intrinsic does not operate correctly.  It is 
wrong code bug, and this is certainly enough to warrant the change 
during bugfix-only stage.  I couldn't care less  for clean target test 
results, since two wrongs  (wrong code and wrong test, to be precise) 
does not make right operation here.

> As asked by APH in a different reply, Where are the nand intrinsics 
> actually being used?

So, if i.e. printf function produces wrong result - eats minus signs for 
example -, this is OK then? The fact that you don't need it doesn't mean 
that we can neglect published standard (Intel ia64 intrinsics). IOW, the 
intrinsic will be changed before 4.4 is released - IIRC, there were 
examples in the past when the release was delayed because of wrong code 
bugs like that.

Uros.