On Tue, 10 Jan 2023, Richard Sandiford wrote:
> Richard Biener <rguent...@suse.de> writes:
> > The extract-last reduction internal function expects the then and
> > else clause as vector and scalar and thus we cannot perform optimization
> > of the inversion of the condition by swapping the then/else clauses.
> >
> > Bootstrap and regtest running on x86_64-unknown-linux-gnu, OK?
>
> Sorry for not having found the time to look at the PR yet.
> Like you say in the trail, it seems kind-of familiar.
>
> I think we should instead prevent the else in:
>
> scalar_cond_masked_key cond (cond_expr, ncopies);
> if (loop_vinfo->scalar_cond_masked_set.contains (cond))
> masks = &LOOP_VINFO_MASKS (loop_vinfo);
> else
> {
>
> for EXTRACT_LAST. We've lost as soon as swap_cond_operands gets
> set to true.
But we're not getting there - the above is guarded with
if (reduction_type == EXTRACT_LAST_REDUCTION)
masks = &LOOP_VINFO_MASKS (loop_vinfo);
else
{
instead we run into
if (masked)
vec_compare = vec_cond_lhs;
else
{
vec_cond_rhs = vec_oprnds1[i];
if (bitop1 == NOP_EXPR)
{
...
else
{
...
else if (bitop2 == BIT_NOT_EXPR
{
/* Instead of doing ~x ? y : z do x ? z : y. */
vec_compare = new_temp;
std::swap (vec_then_clause, vec_else_clause);
so we could instead reject vectorizing for EQ_EXPR but then
applying the negation to the condition allows this to be
vectorized just fine (which is what the patch does)?
Richard.
> Thanks,
> Richard
>
> > Thanks,
> > Richard.
> >
> > PR tree-optimization/108314
> > * tree-vect-stmts.cc (vectorizable_condition): Do not
> > perform BIT_NOT_EXPR optimization for EXTRACT_LAST_REDUCTION.
> >
> > * gcc.dg/vect/pr108314.c: New testcase.
> > ---
> > gcc/testsuite/gcc.dg/vect/pr108314.c | 16 ++++++++++++++++
> > gcc/tree-vect-stmts.cc | 13 +++++++++----
> > 2 files changed, 25 insertions(+), 4 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.dg/vect/pr108314.c
> >
> > diff --git a/gcc/testsuite/gcc.dg/vect/pr108314.c
> > b/gcc/testsuite/gcc.dg/vect/pr108314.c
> > new file mode 100644
> > index 00000000000..07260e06915
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.dg/vect/pr108314.c
> > @@ -0,0 +1,16 @@
> > +/* { dg-do compile } */
> > +/* { dg-additional-options "-march=armv9-a" { target aarch64-*-* } } */
> > +
> > +int x, y, z;
> > +
> > +void f(void)
> > +{
> > + int t = 4;
> > + for (; x; x++)
> > + {
> > + if (y)
> > + continue;
> > + t = 0;
> > + }
> > + z = t;
> > +}
> > diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> > index 6ddd41fb473..eb4ca1f184e 100644
> > --- a/gcc/tree-vect-stmts.cc
> > +++ b/gcc/tree-vect-stmts.cc
> > @@ -10677,7 +10677,8 @@ vectorizable_condition (vec_info *vinfo,
> > vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
> > if (bitop2 == NOP_EXPR)
> > vec_compare = new_temp;
> > - else if (bitop2 == BIT_NOT_EXPR)
> > + else if (bitop2 == BIT_NOT_EXPR
> > + && reduction_type != EXTRACT_LAST_REDUCTION)
> > {
> > /* Instead of doing ~x ? y : z do x ? z : y. */
> > vec_compare = new_temp;
> > @@ -10686,9 +10687,13 @@ vectorizable_condition (vec_info *vinfo,
> > else
> > {
> > vec_compare = make_ssa_name (vec_cmp_type);
> > - new_stmt
> > - = gimple_build_assign (vec_compare, bitop2,
> > - vec_cond_lhs, new_temp);
> > + if (bitop2 == BIT_NOT_EXPR)
> > + new_stmt
> > + = gimple_build_assign (vec_compare, bitop2, new_temp);
> > + else
> > + new_stmt
> > + = gimple_build_assign (vec_compare, bitop2,
> > + vec_cond_lhs, new_temp);
> > vect_finish_stmt_generation (vinfo, stmt_info,
> > new_stmt, gsi);
> > }
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH, Frankenstrasse 146, 90461 Nuernberg,
Germany; GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman;
HRB 36809 (AG Nuernberg)
