On Thu, 3 Nov 2016, Prathamesh Kulkarni wrote:
On 3 November 2016 at 16:13, Richard Biener <rguent...@suse.de> wrote:
On Thu, 3 Nov 2016, Prathamesh Kulkarni wrote:
Hi Richard,
The attached patch tries to fix PR35691, by adding the following two
transforms to match.pd:
(x == 0 && y == 0) -> (x | typeof(x)(y)) == 0.
(x != 0 || y != 0) -> (x | typeof(x)(y)) != 0.
For GENERIC, the "and" operator is truth_andif_expr, and it seems for GIMPLE,
it gets transformed to bit_and_expr
so to match for both GENERIC and GIMPLE, I had to guard the for-stmt:
#if GENERIC
(for op (truth_andif truth_orif)
#elif GIMPLE
(for op (bit_and bit_ior)
#endif
Is that OK ?
As you are not removing the fold-const.c variant I'd say you should
simply not look for truth_* and only handle GIMPLE. Note that we
have tree-ssa-ifcombine.c which should handle the variant with
control-flow (but I guess it does not and your patch wouldn't help
it either).
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))
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. This would also prevent the case where one vector is signed and the
other unsigned, which requires a view_convert (I don't remember if convert
automatically becomes view_convert here as in fold_convert or not).
For (some_int == 0) & (some_long == 0), doing ((long)some_int | some_long)
== 0 should also work (and it doesn't matter if we pick a sign- or
zero-extension), but that's more complicated, not necessary for a first
version.
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).
--
Marc Glisse
