On Tue, 2 Jul 2019, Tamar Christina wrote:
> Hi Richi,
>
> The 06/25/2019 10:02, Richard Biener wrote:
> >
> > This looks like a literal 1:1 translation plus merging with the
> > existing pattern around integers. You changed
> > (op:s@0 (convert@3 @1) (convert?@4 @2)) to
> > (op:s@0 (convert1?@3 @1) (convert2?@4 @2)) where this now also
> > matches if there are no inner conversions at all - was that a
> > desired change or did you merely want to catch when the first
> > operand is not a conversion but the second is, possibly only
> > for the RDIV_EXPR case?
> >
>
> Yes, the ? ? is for the RDIV case, I really only want (c a) `op` (c b),
> a `op` (c b) and (c a) `op` b. But didn't find a way to do this.
One way would be to do
(simplify
(convert (op:sc@0 (convert @1) (convert? @2)))
but that doesn't work for RDIV. Using :C is tempting but you
do not get to know the original operand order which you of
course need. So I guess the way you do it is fine - you
could guard all of the code with a few types_match () checks
but I'm not sure it is worth the trouble.
Richard.
> The only thing I can think of that gets this is without overmatching is
> to either duplicate the code or move this back to a C helper function and
> call that from match.pd. But I was hoping to have it all in match.pd
> instead of hiding it away in a C call.
>
> Do you have a better way of doing it or a preference to an approach?
>
> > +(for op (plus minus mult rdiv)
> > + (simplify
> > + (convert (op:s@0 (convert1?@3 @1) (convert2?@4 @2)))
> > + (with { tree arg0 = strip_float_extensions (@1);
> > + tree arg1 = strip_float_extensions (@2);
> > + tree itype = TREE_TYPE (@0);
> >
> > you now unconditionally call strip_float_extensions on each operand
> > even for the integer case, please sink stuff only used in one
> > case arm. I guess keeping the integer case first via
> >
>
> Done, Initially didn't think it would be an issue since I don't use the value
> it
> creates in the integer case. But I re-ordered it.
>
> > should work (with the 'with' being in the ifs else position).
> >
> > + (if (code == REAL_TYPE)
> > + /* Ignore the conversion if we don't need to store intermediate
> > + results and neither type is a decimal float. */
> > + (if (!(flag_float_store
> > + || DECIMAL_FLOAT_TYPE_P (type)
> > + || DECIMAL_FLOAT_TYPE_P (itype))
> > + && types_match (ty1, ty2))
> > + (convert (op (convert:ty1 @1) (convert:ty2 @2)))))
> >
> > this looks prone to the same recursion issue you described above.
>
> It's to break the recursion when you don't match anything. Indeed don't need
> it if
> I change the match condition above.
> Thanks,
> Tamar
> >
> > 'code' is used exactly once, using SCALAR_FLOAT_TYPE_P (itype)
> > in the above test would be clearer. Also both ifs can be combined.
> > The snipped above also doesn't appear in the convert.c code you
> > remove and the original one is
> >
> > switch (TREE_CODE (TREE_TYPE (expr)))
> > {
> > case REAL_TYPE:
> > /* Ignore the conversion if we don't need to store intermediate
> > results and neither type is a decimal float. */
> > return build1_loc (loc,
> > (flag_float_store
> > || DECIMAL_FLOAT_TYPE_P (type)
> > || DECIMAL_FLOAT_TYPE_P (itype))
> > ? CONVERT_EXPR : NOP_EXPR, type, expr);
> >
> > which as far as I can see doesn't do anything besides
> > exchanging CONVERT_EXPR for NOP_EXPR which is a noop to the IL.
> > So it appears this shouldn't be moved to match.pd at all?
> > It's also not a 1:1 move since you are changing 'expr'.
> >
> > Thanks,
> > Richard.
> >
> > > > Thanks,
> > > > Tamar
> > > >
> > > > Concretely it makes both these cases behave the same
> > > >
> > > > float e = (float)a * (float)b;
> > > > *c = (_Float16)e;
> > > >
> > > > and
> > > >
> > > > *c = (_Float16)((float)a * (float)b);
> > > >
> > > > Thanks,
> > > > Tamar
> > > >
> > > > gcc/ChangeLog:
> > > >
> > > > 2019-06-25 Tamar Christina <tamar.christ...@arm.com>
> > > >
> > > > * convert.c (convert_to_real_1): Move part of conversion code...
> > > > * match.pd: ...To here.
> > > >
> > > > gcc/testsuite/ChangeLog:
> > > >
> > > > 2019-06-25 Tamar Christina <tamar.christ...@arm.com>
> > > >
> > > > * gcc.dg/type-convert-var.c: New test.
> > > >
> > > > --
> > >
> >
> > --
> > Richard Biener <rguent...@suse.de>
> > SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany;
> > GF: Felix Imendörffer, Mary Higgins, Sri Rasiah; HRB 21284 (AG Nürnberg)
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany;
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah; HRB 21284 (AG Nürnberg)
