On Wed, Aug 5, 2020 at 3:33 PM Marc Glisse <marc.gli...@inria.fr> wrote: > > New version that passed bootstrap+regtest during the night. > > When vector comparisons were forced to use vec_cond_expr, we lost a number of > optimizations (my fault for not adding enough testcases to prevent that). > This patch tries to unwrap vec_cond_expr a bit so some optimizations can > still happen. > > I wasn't planning to add all those transformations together, but adding one > caused a regression, whose fix introduced a second regression, etc. > > Restricting to constant folding would not be sufficient, we also need at > least things like X|0 or X&X. The transformations are quite conservative > with :s and folding only if everything simplifies, we may want to relax > this later. And of course we are going to miss things like a?b:c + a?c:b > -> b+c. > > In terms of number of operations, some transformations turning 2 > VEC_COND_EXPR into VEC_COND_EXPR + BIT_IOR_EXPR + BIT_NOT_EXPR might not look > like a gain... I expect the bit_not disappears in most cases, and > VEC_COND_EXPR looks more costly than a simpler BIT_IOR_EXPR. > > I am a bit confused that with avx512 we get types like "vector(4) > <signed-boolean:2>" with :2 and not :1 (is it a hack so true is 1 and not > -1?), but that doesn't matter for this patch.
OK. Thanks, Richard. > 2020-08-05 Marc Glisse <marc.gli...@inria.fr> > > PR tree-optimization/95906 > PR target/70314 > * match.pd ((c ? a : b) op d, (c ? a : b) op (c ? d : e), > (v ? w : 0) ? a : b, c1 ? c2 ? a : b : b): New transformations. > (op (c ? a : b)): Update to match the new transformations. > > * gcc.dg/tree-ssa/andnot-2.c: New file. > * gcc.dg/tree-ssa/pr95906.c: Likewise. > * gcc.target/i386/pr70314.c: Likewise. > > -- > Marc Glisse
