On Fri, 4 Nov 2016, Prathamesh Kulkarni wrote:
> On 4 November 2016 at 13:41, Richard Biener <rguent...@suse.de> wrote:
> > On Thu, 3 Nov 2016, Marc Glisse wrote:
> >
> >> On Thu, 3 Nov 2016, Richard Biener wrote:
> >>
> >> > > > > The transform would also work for vectors (element_precision for
> >> > > > > the test but also a value-matching zero which should ensure the
> >> > > > > same number of elements).
> >> > > > Um sorry, I didn't get how to check vectors to be of equal length by
> >> > > > a
> >> > > > matching zero.
> >> > > > Could you please elaborate on that ?
> >> > >
> >> > > He may have meant something like:
> >> > >
> >> > > (op (cmp @0 integer_zerop@2) (cmp @1 @2))
> >> >
> >> > I meant with one being @@2 to allow signed vs. Unsigned @0/@1 which was
> >> > the
> >> > point of the pattern.
> >>
> >> Oups, that's what I had written first, and then I somehow managed to
> >> confuse
> >> myself enough to remove it so as to remove the call to types_match :-(
> >>
> >> > > So the last operand is checked with operand_equal_p instead of
> >> > > integer_zerop. But the fact that we could compute bit_ior on the
> >> > > comparison results should already imply that the number of elements is
> >> > > the
> >> > > same.
> >> >
> >> > Though for equality compares we also allow scalar results IIRC.
> >>
> >> Oh, right, I keep forgetting that :-( And I have no idea how to generate
> >> one
> >> for a testcase, at least until the GIMPLE FE lands...
> >>
> >> > > On platforms that have IOR on floats (at least x86 with SSE, maybe some
> >> > > vector mode on s390?), it would be cool to do the same for floats (most
> >> > > likely at the RTL level).
> >> >
> >> > On GIMPLE view-converts could come to the rescue here as well. Or we cab
> >> > just allow bit-and/or on floats as much as we allow them on pointers.
> >>
> >> Would that generate sensible code on targets that do not have logic insns
> >> for
> >> floats? Actually, even on x86_64 that generates inefficient code, so there
> >> would be some work (for instance grep finds no gen_iordf3, only
> >> gen_iorv2df3).
> >>
> >> I am also a bit wary of doing those obfuscating optimizations too early...
> >> a==0 is something that other optimizations might use. long
> >> c=(long&)a|(long&)b; (double&)c==0; less so...
> >>
> >> (and I am assuming that signaling NaNs don't make the whole transformation
> >> impossible, which might be wrong)
> >
> > Yeah. I also think it's not so much important - I just wanted to mention
> > vectors...
> >
> > Btw, I still think we need a more sensible infrastructure for passes
> > to gather, analyze and modify complex conditions. (I'm always pointing
> > to tree-affine.c as an, albeit not very good, example for handling
> > a similar problem)
> Thanks for mentioning the value-matching capture @@, I wasn't aware of
> this match.pd feature.
> The current patch keeps it restricted to only bitwise operators on integers.
> Bootstrap+test running on x86_64-unknown-linux-gnu.
> OK to commit if passes ?
+/* PR35691: Transform
+ (x == 0 & y == 0) -> (x | typeof(x)(y)) == 0.
+ (x != 0 | y != 0) -> (x | typeof(x)(y)) != 0. */
+
Please omit the vertical space
+(for bitop (bit_and bit_ior)
+ cmp (eq ne)
+ (simplify
+ (bitop (cmp @0 integer_zerop) (cmp @1 integer_zerop))
if you capture the first integer_zerop as @2 then you can re-use it...
+ (if (INTEGRAL_TYPE_P (TREE_TYPE (@0))
+ && INTEGRAL_TYPE_P (TREE_TYPE (@1))
+ && TYPE_PRECISION (TREE_TYPE (@0)) == TYPE_PRECISION (TREE_TYPE
(@1)))
+ (cmp (bit_ior @0 (convert @1)) { build_zero_cst (TREE_TYPE (@0));
... here inplace of the { build_zero_cst ... }.
Ok with that changes.
Richard.
