On Wed, 8 Jun 2016, Bill Schmidt wrote:
> Hi Richard,
>
> > On Jun 8, 2016, at 7:29 AM, Richard Biener <[email protected]>
> > wrote:
> >
> > On Wed, Jun 13, 2012 at 4:18 AM, William J. Schmidt
> > <[email protected]> wrote:
> >> This patch is a follow-up to the discussion generated by
> >> http://gcc.gnu.org/ml/gcc-patches/2012-06/msg00546.html. I've added
> >> vec_construct to the cost model for use in vect_model_load_cost, and
> >> implemented a cost calculation that makes sense to me for PowerPC. I'm
> >> less certain about the default, i386, and spu implementations. I took a
> >> guess at i386 from the discussions we had, and used the same calculation
> >> for the default and for spu. I'm hoping you or others can fill in the
> >> blanks if I guessed badly.
> >>
> >> The i386 cost for vec_construct is different from all the others, which
> >> are parameterized for each processor description. This should probably
> >> be parameterized in some way as well, but thought you'd know better than
> >> I how that should be. Perhaps instead of
> >>
> >> elements / 2 + 1
> >>
> >> it should be
> >>
> >> (elements / 2) * X + Y
> >>
> >> where X and Y are taken from the processor description, and represent
> >> the cost of a merge and a permute, respectively. Let me know what you
> >> think.
> >
> > Just trying to understand how you arrived at the above formulas in
> > investigating
> > strangely low cost for v16qi construction of 9. If we pairwise reduce
> > elements
> > with a cost of 1 then we arrive at a cost of elements - 1, that's what you'd
> > get with not accounting an initial move of element zero into a vector and
> > then
> > inserting each other element into that with elements - 1 inserts.
>
> What I wrote there only makes partial sense for certain types on Power, so
> far as
> I can tell, and even then it doesn’t generalize properly. When the scalar
> registers
> are contained in the vector registers (as happens for floating-point on
> Power), then
> you can do some merges and other forms of permutes to combine them faster
> than doing specific inserts. But that isn’t a general solution even on
> Power; for the
> integer modes we still do inserts.
You mean Power has instructions to combine more than two vector registers
into one? Otherwise you still need n / 2 plus n / 4 plus n / 8 ...
"permutes" which boils down to n - 1.
> So what you have makes sense to me, and what’s currently in place for Power
> needs
> work also, so far as I can tell. I’ll take a note to revisit this.
Thanks.
Richard.
> — Bill
>
> >
> > This also matches up with code-generation on x86_64 for
> >
> > vT foo (T a, T b, ...)
> > {
> > return (vT) {a, b, ... };
> > }
> >
> > for any vector / element type combination I tried. Thus the patch below.
> >
> > I'll bootstrap / test that on x86_64-linux and I'm leaving other
> > targets to target
> > maintainers.
> >
> > Ok for the i386 parts?
> >
> > Thanks,
> > Richard.
> >
> > 2016-06-08 Richard Biener <[email protected]>
> >
> > * targhooks.c (default_builtin_vectorization_cost): Adjust
> > vec_construct cost.
> > * config/i386/i386.c (ix86_builtin_vectorization_cost): Likewise.
> >
> > Index: gcc/targhooks.c
> > ===================================================================
> > --- gcc/targhooks.c (revision 237196)
> > +++ gcc/targhooks.c (working copy)
> > @@ -589,8 +589,7 @@ default_builtin_vectorization_cost (enum
> > return 3;
> >
> > case vec_construct:
> > - elements = TYPE_VECTOR_SUBPARTS (vectype);
> > - return elements / 2 + 1;
> > + return TYPE_VECTOR_SUBPARTS (vectype) - 1;
> >
> > default:
> > gcc_unreachable ();
> > Index: gcc/config/i386/i386.c
> > ===================================================================
> > --- gcc/config/i386/i386.c (revision 237196)
> > +++ gcc/config/i386/i386.c (working copy)
> > @@ -49503,8 +49520,6 @@ static int
> > ix86_builtin_vectorization_cost (enum vect_cost_for_stmt type_of_cost,
> > tree vectype, int)
> > {
> > - unsigned elements;
> > -
> > switch (type_of_cost)
> > {
> > case scalar_stmt:
> > @@ -49546,8 +49561,7 @@ ix86_builtin_vectorization_cost (enum ve
> > return ix86_cost->vec_stmt_cost;
> >
> > case vec_construct:
> > - elements = TYPE_VECTOR_SUBPARTS (vectype);
> > - return ix86_cost->vec_stmt_cost * (elements / 2 + 1);
> > + return ix86_cost->vec_stmt_cost * (TYPE_VECTOR_SUBPARTS (vectype) -
> > 1);
> >
> > default:
> > gcc_unreachable ();
> >
> >
> >> Thanks,
> >> Bill
> >>
> >>
> >> 2012-06-12 Bill Schmidt <[email protected]>
> >>
> >> * targhooks.c (default_builtin_vectorized_conversion): Handle
> >> vec_construct, using vectype to base cost on subparts.
> >> * target.h (enum vect_cost_for_stmt): Add vec_construct.
> >> * tree-vect-stmts.c (vect_model_load_cost): Use vec_construct
> >> instead of scalar_to-vec.
> >> * config/spu/spu.c (spu_builtin_vectorization_cost): Handle
> >> vec_construct in same way as default for now.
> >> * config/i386/i386.c (ix86_builtin_vectorization_cost): Likewise.
> >> * config/rs6000/rs6000.c (rs6000_builtin_vectorization_cost):
> >> Handle vec_construct, including special case for 32-bit loads.
> >>
> >>
> >> Index: gcc/targhooks.c
> >> ===================================================================
> >> --- gcc/targhooks.c (revision 188482)
> >> +++ gcc/targhooks.c (working copy)
> >> @@ -499,9 +499,11 @@ default_builtin_vectorized_conversion (unsigned in
> >>
> >> int
> >> default_builtin_vectorization_cost (enum vect_cost_for_stmt type_of_cost,
> >> - tree vectype ATTRIBUTE_UNUSED,
> >> + tree vectype,
> >> int misalign ATTRIBUTE_UNUSED)
> >> {
> >> + unsigned elements;
> >> +
> >> switch (type_of_cost)
> >> {
> >> case scalar_stmt:
> >> @@ -524,6 +526,11 @@ default_builtin_vectorization_cost (enum vect_cost
> >> case cond_branch_taken:
> >> return 3;
> >>
> >> + case vec_construct:
> >> + elements = TYPE_VECTOR_SUBPARTS (vectype);
> >> + gcc_assert (elements > 1);
> >> + return elements / 2 + 1;
> >> +
> >> default:
> >> gcc_unreachable ();
> >> }
> >> Index: gcc/target.h
> >> ===================================================================
> >> --- gcc/target.h (revision 188482)
> >> +++ gcc/target.h (working copy)
> >> @@ -146,7 +146,8 @@ enum vect_cost_for_stmt
> >> cond_branch_not_taken,
> >> cond_branch_taken,
> >> vec_perm,
> >> - vec_promote_demote
> >> + vec_promote_demote,
> >> + vec_construct
> >> };
> >>
> >> /* The target structure. This holds all the backend hooks. */
> >> Index: gcc/tree-vect-stmts.c
> >> ===================================================================
> >> --- gcc/tree-vect-stmts.c (revision 188482)
> >> +++ gcc/tree-vect-stmts.c (working copy)
> >> @@ -1031,11 +1031,13 @@ vect_model_load_cost (stmt_vec_info stmt_info, int
> >> /* The loads themselves. */
> >> if (STMT_VINFO_STRIDE_LOAD_P (stmt_info))
> >> {
> >> - /* N scalar loads plus gathering them into a vector.
> >> - ??? scalar_to_vec isn't the cost for that. */
> >> + /* N scalar loads plus gathering them into a vector. */
> >> + tree vectype = STMT_VINFO_VECTYPE (stmt_info);
> >> inside_cost += (vect_get_stmt_cost (scalar_load) * ncopies
> >> - * TYPE_VECTOR_SUBPARTS (STMT_VINFO_VECTYPE
> >> (stmt_info)));
> >> - inside_cost += ncopies * vect_get_stmt_cost (scalar_to_vec);
> >> + * TYPE_VECTOR_SUBPARTS (vectype));
> >> + inside_cost += ncopies
> >> + * targetm.vectorize.builtin_vectorization_cost (vec_construct,
> >> + vectype, 0);
> >> }
> >> else
> >> vect_get_load_cost (first_dr, ncopies,
> >> Index: gcc/config/spu/spu.c
> >> ===================================================================
> >> --- gcc/config/spu/spu.c (revision 188482)
> >> +++ gcc/config/spu/spu.c (working copy)
> >> @@ -6908,9 +6908,11 @@ spu_builtin_mask_for_load (void)
> >> /* Implement targetm.vectorize.builtin_vectorization_cost. */
> >> static int
> >> spu_builtin_vectorization_cost (enum vect_cost_for_stmt type_of_cost,
> >> - tree vectype ATTRIBUTE_UNUSED,
> >> + tree vectype,
> >> int misalign ATTRIBUTE_UNUSED)
> >> {
> >> + unsigned elements;
> >> +
> >> switch (type_of_cost)
> >> {
> >> case scalar_stmt:
> >> @@ -6937,6 +6939,11 @@ spu_builtin_vectorization_cost (enum vect_cost_for
> >> case cond_branch_taken:
> >> return 6;
> >>
> >> + case vec_construct:
> >> + elements = TYPE_VECTOR_SUBPARTS (vectype);
> >> + gcc_assert (elements > 1);
> >> + return elements / 2 + 1;
> >> +
> >> default:
> >> gcc_unreachable ();
> >> }
> >> Index: gcc/config/i386/i386.c
> >> ===================================================================
> >> --- gcc/config/i386/i386.c (revision 188482)
> >> +++ gcc/config/i386/i386.c (working copy)
> >> @@ -36072,9 +36072,11 @@ static const struct attribute_spec ix86_attribute_
> >> /* Implement targetm.vectorize.builtin_vectorization_cost. */
> >> static int
> >> ix86_builtin_vectorization_cost (enum vect_cost_for_stmt type_of_cost,
> >> - tree vectype ATTRIBUTE_UNUSED,
> >> + tree vectype,
> >> int misalign ATTRIBUTE_UNUSED)
> >> {
> >> + unsigned elements;
> >> +
> >> switch (type_of_cost)
> >> {
> >> case scalar_stmt:
> >> @@ -36115,6 +36117,11 @@ ix86_builtin_vectorization_cost (enum vect_cost_fo
> >> case vec_promote_demote:
> >> return ix86_cost->vec_stmt_cost;
> >>
> >> + case vec_construct:
> >> + elements = TYPE_VECTOR_SUBPARTS (vectype);
> >> + gcc_assert (elements > 1);
> >> + return elements / 2 + 1;
> >> +
> >> default:
> >> gcc_unreachable ();
> >> }
> >> Index: gcc/config/rs6000/rs6000.c
> >> ===================================================================
> >> --- gcc/config/rs6000/rs6000.c (revision 188482)
> >> +++ gcc/config/rs6000/rs6000.c (working copy)
> >> @@ -3405,6 +3405,7 @@ rs6000_builtin_vectorization_cost (enum vect_cost_
> >> tree vectype, int misalign)
> >> {
> >> unsigned elements;
> >> + tree elem_type;
> >>
> >> switch (type_of_cost)
> >> {
> >> @@ -3504,6 +3505,19 @@ rs6000_builtin_vectorization_cost (enum vect_cost_
> >>
> >> return 2;
> >>
> >> + case vec_construct:
> >> + elements = TYPE_VECTOR_SUBPARTS (vectype);
> >> + elem_type = TREE_TYPE (vectype);
> >> + gcc_assert (elements > 1);
> >> + /* 32-bit vectors loaded into registers are stored as double
> >> + precision, so we need n/2 converts in addition to the usual
> >> + n/2 merges to construct a vector of short floats from them. */
> >> + if (SCALAR_FLOAT_TYPE_P (elem_type)
> >> + && TYPE_PRECISION (elem_type) == 32)
> >> + return elements + 1;
> >> + else
> >> + return elements / 2 + 1;
> >> +
> >> default:
> >> gcc_unreachable ();
> >> }
> >>
> >>
> >
>
>
--
Richard Biener <[email protected]>
SUSE LINUX GmbH, GF: Felix Imendoerffer, Jane Smithard, Graham Norton, HRB
21284 (AG Nuernberg)
