On Tue, 3 May 2022 at 18:25, Richard Sandiford
<richard.sandif...@arm.com> wrote:
>
> Prathamesh Kulkarni <prathamesh.kulka...@linaro.org> writes:
> > On Tue, 4 Jan 2022 at 19:12, Richard Sandiford
> > <richard.sandif...@arm.com> wrote:
> >>
> >> Richard Biener <rguent...@suse.de> writes:
> >> > On Tue, 4 Jan 2022, Richard Sandiford wrote:
> >> >
> >> >> Richard Biener <rguent...@suse.de> writes:
> >> >> > On Fri, 17 Dec 2021, Richard Sandiford wrote:
> >> >> >
> >> >> >> Prathamesh Kulkarni <prathamesh.kulka...@linaro.org> writes:
> >> >> >> > Hi,
> >> >> >> > The attached patch rearranges order of type-check for vec_perm_expr
> >> >> >> > and relaxes type checking for
> >> >> >> > lhs = vec_perm_expr<rhs1, rhs2, mask>
> >> >> >> >
> >> >> >> > when:
> >> >> >> > rhs1 == rhs2,
> >> >> >> > lhs is variable length vector,
> >> >> >> > rhs1 is fixed length vector,
> >> >> >> > TREE_TYPE (lhs) == TREE_TYPE (rhs1)
> >> >> >> >
> >> >> >> > I am not sure tho if this check is correct ? My intent was to
> >> >> >> > capture
> >> >> >> > case when vec_perm_expr is used to "extend" fixed length vector to
> >> >> >> > it's VLA equivalent.
> >> >> >>
> >> >> >> VLAness isn't really the issue. We want the same thing to work for
> >> >> >> -msve-vector-bits=256, -msve-vector-bits=512, etc., even though the
> >> >> >> vectors are fixed-length in that case.
> >> >> >>
> >> >> >> The principle is that for:
> >> >> >>
> >> >> >> A = VEC_PERM_EXPR <B, C, D>;
> >> >> >>
> >> >> >> the requirements are:
> >> >> >>
> >> >> >> - A, B, C and D must be vectors
> >> >> >> - A, B and C must have the same element type
> >> >> >> - D must have an integer element type
> >> >> >> - A and D must have the same number of elements (NA)
> >> >> >> - B and C must have the same number of elements (NB)
> >> >> >>
> >> >> >> The semantics are that we create a joined vector BC (all elements of
> >> >> >> B
> >> >> >> followed by all element of C) and that:
> >> >> >>
> >> >> >> A[i] = BC[D[i] % (NB+NB)]
> >> >> >>
> >> >> >> for 0 ≤ i < NA.
> >> >> >>
> >> >> >> This operation makes sense even if NA != NB.
> >> >> >
> >> >> > But note that we don't currently expect NA != NB and the optab just
> >> >> > has a single mode.
> >> >>
> >> >> True, but we only need this for constant permutes. They are already
> >> >> special in that they allow the index elements to be wider than the data
> >> >> elements.
> >> >
> >> > OK, then we should reflect this in the stmt verification and only relax
> >> > the constant permute vector case and also amend the
> >> > TARGET_VECTORIZE_VEC_PERM_CONST accordingly.
> >>
> >> Sounds good.
> >>
> >> > For non-constant permutes the docs say the mode of vec_perm is
> >> > the common mode of operands 1 and 2 whilst the mode of operand 0
> >> > is unspecified - even unconstrained by the docs. I'm not sure
> >> > if vec_perm expansion is expected to eventually FAIL. Updating the
> >> > docs of vec_perm would be appreciated as well.
> >>
> >> Yeah, I guess de facto operand 0 has to be the same mode as operands
> >> 1 and 2. Maybe that was just an oversight, or maybe it seemed obvious
> >> or self-explanatory at the time. :-)
> >>
> >> > As said I prefer to not mangle the existing stmt checking too much
> >> > at this stage so minimal adjustment is prefered there.
> >>
> >> The PR is only an enhancement request rather than a bug, so I think the
> >> patch would need to wait for GCC 13 whatever happens.
> > Hi,
> > In attached patch, the type checking is relaxed only if mask is constant.
> > Does this look OK ?
> >
> > Thanks,
> > Prathamesh
> >>
> >> Thanks,
> >> Richard
> >
> > diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
> > index e321d929fd0..02b88f67855 100644
> > --- a/gcc/tree-cfg.cc
> > +++ b/gcc/tree-cfg.cc
> > @@ -4307,6 +4307,24 @@ verify_gimple_assign_ternary (gassign *stmt)
> > break;
> >
> > case VEC_PERM_EXPR:
> > + /* If permute is constant, then we allow for lhs and rhs
> > + to have different vector types, provided:
> > + (1) lhs, rhs1, rhs2, and rhs3 have same element type.
>
> This isn't a requirement for rhs3.
>
> > + (2) rhs3 vector has integer element type.
> > + (3) len(lhs) == len(rhs3) && len(rhs1) == len(rhs2). */
> > +
> > + if (TREE_CONSTANT (rhs3)
> > + && VECTOR_TYPE_P (lhs_type)
> > + && VECTOR_TYPE_P (rhs1_type)
> > + && VECTOR_TYPE_P (rhs2_type)
> > + && VECTOR_TYPE_P (rhs3_type)
> > + && TREE_TYPE (lhs_type) == TREE_TYPE (rhs1_type)
> > + && TREE_TYPE (lhs_type) == TREE_TYPE (rhs2_type)
> > + && INTEGRAL_TYPE_P (TREE_TYPE (rhs3_type))
> > + && known_eq (TYPE_VECTOR_SUBPARTS (lhs_type), TYPE_VECTOR_SUBPARTS
> > (rhs3_type))
> > + && known_eq (TYPE_VECTOR_SUBPARTS (rhs1_type), TYPE_VECTOR_SUBPARTS
> > (rhs2_type)))
> > + return false;
> > +
>
> I think this should be integrated into the existing conditions
> rather than done as an initial special case.
>
> It might make sense to start with:
>
> if (TREE_CODE (rhs1_type) != VECTOR_TYPE
> || TREE_CODE (rhs2_type) != VECTOR_TYPE
> || TREE_CODE (rhs3_type) != VECTOR_TYPE)
> {
>
> but expanded to test lhs_type too. Then the other parts of the new test
> should be distributed across the existing conditions.
>
> The type tests should use useless_type_conversion_p rather than ==.
Hi Richard,
Thanks for the suggestions. In the attached patch, I tried to
distribute the checks
across existing conditions, does it look OK ?
I am not sure how to write tests for the type checks tho, does
gimple-fe support vec_perm_expr ?
I did a quick testsuite run for vect.exp and the patch doesn't seem to
cause any unexpected failures.
Thanks,
Prathamesh
>
> Thanks,
> Richard
>
>
>
> > if (!useless_type_conversion_p (lhs_type, rhs1_type)
> > || !useless_type_conversion_p (lhs_type, rhs2_type))
> > {
diff --git a/gcc/tree-cfg.cc b/gcc/tree-cfg.cc
index e321d929fd0..a845c7fff93 100644
--- a/gcc/tree-cfg.cc
+++ b/gcc/tree-cfg.cc
@@ -4307,18 +4307,14 @@ verify_gimple_assign_ternary (gassign *stmt)
break;
case VEC_PERM_EXPR:
- if (!useless_type_conversion_p (lhs_type, rhs1_type)
- || !useless_type_conversion_p (lhs_type, rhs2_type))
- {
- error ("type mismatch in %qs", code_name);
- debug_generic_expr (lhs_type);
- debug_generic_expr (rhs1_type);
- debug_generic_expr (rhs2_type);
- debug_generic_expr (rhs3_type);
- return true;
- }
+ /* If permute is constant, then we allow for lhs and rhs
+ to have different vector types, provided:
+ (1) lhs, rhs1, rhs2 have same element type.
+ (2) rhs3 vector has integer element type.
+ (3) len(lhs) == len(rhs3) && len(rhs1) == len(rhs2). */
- if (TREE_CODE (rhs1_type) != VECTOR_TYPE
+ if (TREE_CODE (lhs_type) != VECTOR_TYPE
+ || TREE_CODE (rhs1_type) != VECTOR_TYPE
|| TREE_CODE (rhs2_type) != VECTOR_TYPE
|| TREE_CODE (rhs3_type) != VECTOR_TYPE)
{
@@ -4330,10 +4326,29 @@ verify_gimple_assign_ternary (gassign *stmt)
return true;
}
+ /* If lhs, rhs1, and rhs2 are different vector types,
+ then relax the check if rhs3 is constant and lhs, rhs1, and rhs2
+ have same element types. */
+ if ((!useless_type_conversion_p (lhs_type, rhs1_type)
+ || !useless_type_conversion_p (lhs_type, rhs2_type))
+ && (!TREE_CONSTANT (rhs3)
+ || TREE_TYPE (lhs_type) != TREE_TYPE (rhs1_type)
+ || TREE_TYPE (lhs_type) != TREE_TYPE (rhs2_type)))
+ {
+ error ("type mismatch in %qs", code_name);
+ debug_generic_expr (lhs_type);
+ debug_generic_expr (rhs1_type);
+ debug_generic_expr (rhs2_type);
+ debug_generic_expr (rhs3_type);
+ return true;
+ }
+
+ /* If rhs3 is constant, relax the check len(rhs2) == len(rhs3). */
if (maybe_ne (TYPE_VECTOR_SUBPARTS (rhs1_type),
TYPE_VECTOR_SUBPARTS (rhs2_type))
- || maybe_ne (TYPE_VECTOR_SUBPARTS (rhs2_type),
+ || (maybe_ne (TYPE_VECTOR_SUBPARTS (rhs2_type),
TYPE_VECTOR_SUBPARTS (rhs3_type))
+ && !TREE_CONSTANT (rhs3))
|| maybe_ne (TYPE_VECTOR_SUBPARTS (rhs3_type),
TYPE_VECTOR_SUBPARTS (lhs_type)))
{
