freedreno/ir3: Make imageStore use num components from image format

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, rg32i, etc) 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.

v2: - Added support for image formats from NV_image_format extension
    (Ilia Mirkin).
    - Return 4 components by default instead of asserting. (Rob Clark).

v3: Added more missing formats (Ilia Mirkin).

v4: Added a debug message for unknown image formats (Rob Clark).

Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Rob Clark <robdclark@gmail.com>

diff --git a/src/freedreno/ir3/ir3_compiler_nir.c b/src/freedreno/ir3/ir3_compiler_nir.c
index 85f14f354d25becbbde6f135e2c2e4add28264c6..19aef3eb27ed9d9632227b37a25538a37f21ba37 100644 (file)
--- a/src/freedreno/ir3/ir3_compiler_nir.c
+++ b/src/freedreno/ir3/ir3_compiler_nir.c
@@ -1251,6 +1251,73 @@ emit_intrinsic_load_image(struct ir3_context *ctx, nir_intrinsic_instr *intr,
        ir3_split_dest(b, dst, sam, 0, 4);
 }
 
+/* Returns the number of components for the different image formats
+ * supported by the GLES 3.1 spec, plus those added by the
+ * GL_NV_image_formats extension.
+ */
+static unsigned
+get_num_components_for_glformat(GLuint format)
+{
+       switch (format) {
+       case GL_R32F:
+       case GL_R32I:
+       case GL_R32UI:
+       case GL_R16F:
+       case GL_R16I:
+       case GL_R16UI:
+       case GL_R16:
+       case GL_R16_SNORM:
+       case GL_R8I:
+       case GL_R8UI:
+       case GL_R8:
+       case GL_R8_SNORM:
+               return 1;
+
+       case GL_RG32F:
+       case GL_RG32I:
+       case GL_RG32UI:
+       case GL_RG16F:
+       case GL_RG16I:
+       case GL_RG16UI:
+       case GL_RG16:
+       case GL_RG16_SNORM:
+       case GL_RG8I:
+       case GL_RG8UI:
+       case GL_RG8:
+       case GL_RG8_SNORM:
+               return 2;
+
+       case GL_R11F_G11F_B10F:
+               return 3;
+
+       case GL_RGBA32F:
+       case GL_RGBA32I:
+       case GL_RGBA32UI:
+       case GL_RGBA16F:
+       case GL_RGBA16I:
+       case GL_RGBA16UI:
+       case GL_RGBA16:
+       case GL_RGBA16_SNORM:
+       case GL_RGBA8I:
+       case GL_RGBA8UI:
+       case GL_RGBA8:
+       case GL_RGBA8_SNORM:
+       case GL_RGB10_A2UI:
+       case GL_RGB10_A2:
+               return 4;
+
+       default:
+               /* Return 4 components also for all other formats we don't know
+                * about. This is always safe. Also, the format should have been
+                * validated already by the higher level API. Drop a debug message
+                * just in case.
+                */
+               debug_printf("Unhandled GL format %u while emitting imageStore()\n",
+                                        format);
+               return 4;
+       }
+}
+
 /* src[] = { deref, coord, sample_index, value }. const_index[] = {} */
 static void
 emit_intrinsic_store_image(struct ir3_context *ctx, nir_intrinsic_instr *intr)
@@ -1262,6 +1329,7 @@ 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 +1344,10 @@ 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;