On 12/03/2015 02:06 PM, Richard Sandiford wrote:
As Bernd requested, this patch adds "This pattern cannot FAIL" to the
documentation of optabs that came to be mapped to interal functions.
For consistency I did the same for optabs that were already being
used for internal functions.
Many of the optabs weren't documented in the first place, so I added
entries for the missing ones. Also, there were some inaccuracies in
the documentation of the rounding optabs. The bitcount optabs said
that operand 0 has mode @var{m} and that operand 1 is under target
control, whereas it should be the other way around.
That actually goes beyond what I imagined. I was looking at the top part
of md.texi (line 87), where there is a brief discussion of what is
allowed to FAIL and what isn't. Also, there is "@item FAIL":
"Failure is currently supported only for binary (addition,
multiplication, shifting, etc.) and bit-field (@code{extv},
@code{extzv}, and @code{insv}) operations."
That's pretty outdated. I think unary operations are probably missing by
accident, and from what my grep showed there are also conditional moves,
atomic operations, certain vec_ patterns that can all fail. As a minimum
this paragraph should also mention internal functions.
Thank you for this patch, it is OK, but we probably ought to tweak at
least the @item FAIL sections as well.
Bernd
