On Thu, 3 Nov 2016, Richard Biener 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).
On the other hand, now that we are using VEC_COND_EXPR all over the place,
it may be hard to write a testcase that makes this kind of pattern
appear...
(related to PR 68714)
--
Marc Glisse
