Richard Biener <rguent...@suse.de> writes:
> 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)?
Ah, OK. I wasn't sure which of the paths we were going down to get here.
So yeah, I agree the patch is OK. Sorry for the noise.
Richard
> 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);
>> > }
>>
