[Mesa-dev] [PATCH] freedreno/ir3: Make imageStore use num components from image format

[Ilia Mirkin]

Nv_image_formats adds all the core formats to gles.

It's pretty easy to add them all in, so I don't see why not.

On Tue, Dec 18, 2018, 03:17 Eduardo Lima Mitev <elima at igalia.com wrote:

>
>
> On 12/18/18 9:05 AM, Eduardo Lima Mitev wrote:
> > On 12/17/18 10:02 PM, Ilia Mirkin wrote:
> >> Note that the format may not be known. I suspect that falls into your
> >> "default" case.
> >>
> >
> > Hi Ilia,
> >
> > while on GLES profiles the format qualifier must be declared for all
> > image variables, it is true that core profiles allow to omit it for
> > writeonly-qualified images.
> >
> > I guess we can add a special case for GL_NONE to the switch, that also
> > returns 4 components, to at least not break current behavior if image
> > format is not known. What do you think?
> >
>
> Thinking a bit more about this, if we care about core profile then there
> are more GL formats to consider apart from those supported by GLES 3.1.
>
> However, since image format layout qualifiers were introduced in core
> 4.20, I don't think we should care for now. So I would leave the patch
> as-is and fail the assert on unknown formats.
>
> Eduardo
>
> > Eduardo
> >
> >> On Mon, Dec 17, 2018 at 3:41 PM Eduardo Lima Mitev <elima at igalia.com>
> wrote:
> >>>
> >>> emit_intrinsic_store_image() is always using 4 components when
> >>> collecting registers for the value. When image has less than
> >>> 4 components (e.g, r32f, r32i, r32ui) this results in extra mov
> >>> instructions.
> >>>
> >>> This patch uses the actual number of components from the image format.
> >>>
> >>> For example, in a shader like:
> >>>
> >>> layout (r32f, binding=0) writeonly uniform imageBuffer u_image;
> >>> ...
> >>> void main(void) {
> >>>    ...
> >>>    imageStore (u_image, some_offset, vec4(1.0));
> >>>    ...
> >>> }
> >>>
> >>> instruction count is reduced in at least 3 instructions (note image
> >>> format is r32f, 1 component only).
> >>>
> >>> This obviously reduces register pressure as well.
> >>> ---
> >>>  src/freedreno/ir3/ir3_compiler_nir.c | 34 ++++++++++++++++++++++++++--
> >>>  1 file changed, 32 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/src/freedreno/ir3/ir3_compiler_nir.c
> b/src/freedreno/ir3/ir3_compiler_nir.c
> >>> index 85f14f354d2..cc00602c249 100644
> >>> --- a/src/freedreno/ir3/ir3_compiler_nir.c
> >>> +++ b/src/freedreno/ir3/ir3_compiler_nir.c
> >>> @@ -1251,6 +1251,35 @@ emit_intrinsic_load_image(struct ir3_context
> *ctx, nir_intrinsic_instr *intr,
> >>>         ir3_split_dest(b, dst, sam, 0, 4);
> >>>  }
> >>>
> >>> +/* Get the number of components of the different image formats
> supported
> >>> + * by the GLES 3.1 spec.
> >>> + */
> >>> +static unsigned
> >>> +get_num_components_for_glformat(GLuint format)
> >>> +{
> >>> +       switch (format) {
> >>> +       case GL_R32F:
> >>> +       case GL_R32I:
> >>> +       case GL_R32UI:
> >>> +               return 1;
> >>> +
> >>> +       case GL_RGBA32F:
> >>> +       case GL_RGBA16F:
> >>> +       case GL_RGBA8:
> >>> +       case GL_RGBA8_SNORM:
> >>> +       case GL_RGBA32I:
> >>> +       case GL_RGBA16I:
> >>> +       case GL_RGBA8I:
> >>> +       case GL_RGBA32UI:
> >>> +       case GL_RGBA16UI:
> >>> +       case GL_RGBA8UI:
> >>> +               return 4;
> >>> +
> >>> +       default:
> >>> +               assert(!"Unsupported GL format for image");
> >>> +       }
> >>> +}
> >>> +
> >>>  /* src[] = { deref, coord, sample_index, value }. const_index[] = {}
> */
> >>>  static void
> >>>  emit_intrinsic_store_image(struct ir3_context *ctx,
> nir_intrinsic_instr *intr)
> >>> @@ -1262,6 +1291,7 @@ emit_intrinsic_store_image(struct ir3_context
> *ctx, nir_intrinsic_instr *intr)
> >>>         struct ir3_instruction * const *coords = ir3_get_src(ctx,
> &intr->src[1]);
> >>>         unsigned ncoords = get_image_coords(var, NULL);
> >>>         unsigned tex_idx = get_image_slot(ctx,
> nir_src_as_deref(intr->src[0]));
> >>> +       unsigned ncomp =
> get_num_components_for_glformat(var->data.image.format);
> >>>
> >>>         /* src0 is value
> >>>          * src1 is coords
> >>> @@ -1276,10 +1306,10 @@ emit_intrinsic_store_image(struct ir3_context
> *ctx, nir_intrinsic_instr *intr)
> >>>          */
> >>>
> >>>         stib = ir3_STIB(b, create_immed(b, tex_idx), 0,
> >>> -                       ir3_create_collect(ctx, value, 4), 0,
> >>> +                       ir3_create_collect(ctx, value, ncomp), 0,
> >>>                         ir3_create_collect(ctx, coords, ncoords), 0,
> >>>                         offset, 0);
> >>> -       stib->cat6.iim_val = 4;
> >>> +       stib->cat6.iim_val = ncomp;
> >>>         stib->cat6.d = ncoords;
> >>>         stib->cat6.type = get_image_type(var);
> >>>         stib->cat6.typed = true;
> >>> --
> >>> 2.19.2
> >>>
> >>> _______________________________________________
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> >>
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