On 24 August 2012 03:06, Kenneth Graunke <kenn...@whitecape.org> wrote:
> When assigning uniform locations, the linker assigns each sampler
> uniform a sequential numerical ID. gl_shader_program::SamplerUnits maps
> these sampler variable IDs to the actual texture units they reference
> (specified via glUniform1i).
>
> Previously, we encoded this mapping in the SEND instruction encoding:
> the "sampler" was the texture unit number, and the binding table index
> was SURF_INDEX_TEXTURE(the texture unit number). This unfortunately
> meant that whenever the application changed the value of a sampler
> uniform, we had to recompile the shader to change the SEND instructions.
>
> This was horrible for the game Cogs, which repeatedly switches between
> using texture unit 0 and 1. It also made fragment shader precompiles
> useless: we'd do the precompile at glLinkShader() time, before the
> application called glUniform1i to set the sampler values. As soon as
> it did that, we'd have to recompile, wasting time and space in the
> program cache.
>
> This patch encodes the SamplerUnits indirection in the binding table,
> sampler state, and sampler default color tables. Instead of baking the
> texture unit number into the shader, we bake in the sampler variable ID
> assigned by the linker. Since those never change, we don't need to
> recompile programs on uniform changes.
>
> This does mean that the tables now depend on the linked shader program
> being used for rendering, rather than simply representing all available
> texture units. This could cause an increase in state emission.
>
> Another plus is that the sampler state and sampler default color tables
> are now compact: we only emit as many entries as there are sampler
> uniforms, with no holes in the table since the new sampler IDs are
> sequential. Previously we had to emit a full 16 entries every time,
> since the tables tracked the state of all active texture units.
>
> Signed-off-by: Kenneth Graunke <kenn...@whitecape.org>
> ---
> src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 2 +-
> src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp | 2 +-
> src/mesa/drivers/dri/i965/brw_wm_sampler_state.c | 27 ++++++++-----
> src/mesa/drivers/dri/i965/brw_wm_surface_state.c | 51
> ++++++++++++++++++------
> src/mesa/drivers/dri/i965/gen7_sampler_state.c | 27 ++++++++-----
> 5 files changed, 74 insertions(+), 35 deletions(-)
>
> The big patch that actually changes how we do things.
>
> diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> index 601f83c..e3d3a98 100644
> --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
> @@ -1345,7 +1345,7 @@ fs_visitor::visit(ir_texture *ir)
> if (ir->offset != NULL && ir->op != ir_txf)
> inst->texture_offset =
> brw_texture_offset(ir->offset->as_constant());
>
> - inst->sampler = texunit;
> + inst->sampler = sampler;
>
> if (ir->shadow_comparitor)
> inst->shadow_compare = true;
> diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> index c22ba60..629ecb0 100644
> --- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> +++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
> @@ -1897,7 +1897,7 @@ vec4_visitor::visit(ir_texture *ir)
> inst->header_present = ir->offset || intel->gen < 5;
> inst->base_mrf = 2;
> inst->mlen = inst->header_present + 1; /* always at least one */
> - inst->sampler = texunit;
> + inst->sampler = sampler;
> inst->dst = dst_reg(this, ir->type);
> inst->shadow_compare = ir->shadow_comparitor != NULL;
>
> diff --git a/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
> b/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
> index 10deb1d..610ef34 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm_sampler_state.c
> @@ -334,13 +334,14 @@ brw_upload_samplers(struct brw_context *brw)
> {
> struct gl_context *ctx = &brw->intel.ctx;
> struct brw_sampler_state *samplers;
> - int i;
>
> - brw->sampler.count = 0;
> - for (i = 0; i < BRW_MAX_TEX_UNIT; i++) {
> - if (ctx->Texture.Unit[i]._ReallyEnabled)
> - brw->sampler.count = i + 1;
> - }
> + /* BRW_NEW_VERTEX_PROGRAM and BRW_NEW_FRAGMENT_PROGRAM */
> + struct gl_program *vs = (struct gl_program *) brw->vertex_program;
> + struct gl_program *fs = (struct gl_program *) brw->fragment_program;
> +
> + GLbitfield SamplersUsed = vs->SamplersUsed | fs->SamplersUsed;
> +
> + brw->sampler.count = _mesa_bitcount(SamplersUsed);
>
> if (brw->sampler.count == 0)
> return;
> @@ -350,9 +351,13 @@ brw_upload_samplers(struct brw_context *brw)
> 32, &brw->sampler.offset);
> memset(samplers, 0, brw->sampler.count * sizeof(*samplers));
>
> - for (i = 0; i < brw->sampler.count; i++) {
> - if (ctx->Texture.Unit[i]._ReallyEnabled)
> - brw_update_sampler_state(brw, i, i, &samplers[i]);
> + for (unsigned s = 0; s < brw->sampler.count; s++) {
> + if (SamplersUsed & (1 << s)) {
> + const unsigned unit = (fs->SamplersUsed & (1 << s)) ?
> + fs->SamplerUnits[s] : vs->SamplerUnits[s];
>
Presumably the correctness of this code relies on the assumption that if a
given sampler is used by both the VS and the FS, then fs->SamplerUnits[s]
== vs->SamplerUnits[s]. Would you mind adding a comment explaining why
that is the case? It's not obvious to me without digging around the linker
code. (An assertion to this effect might be a good idea too, since we're
relying on the behaviour of code way off in glsl land).
> + if (ctx->Texture.Unit[unit]._ReallyEnabled)
> + brw_update_sampler_state(brw, unit, s, &samplers[s]);
> + }
> }
>
> brw->state.dirty.cache |= CACHE_NEW_SAMPLER;
> @@ -361,7 +366,9 @@ brw_upload_samplers(struct brw_context *brw)
> const struct brw_tracked_state brw_samplers = {
> .dirty = {
> .mesa = _NEW_TEXTURE,
> - .brw = BRW_NEW_BATCH,
> + .brw = BRW_NEW_BATCH |
> + BRW_NEW_VERTEX_PROGRAM |
> + BRW_NEW_FRAGMENT_PROGRAM,
> .cache = 0
> },
> .emit = brw_upload_samplers,
> diff --git a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> index 0c87b84..eefa427 100644
> --- a/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> +++ b/src/mesa/drivers/dri/i965/brw_wm_surface_state.c
> @@ -1238,22 +1238,45 @@ const struct brw_tracked_state
> gen6_renderbuffer_surfaces = {
> static void
> brw_update_texture_surfaces(struct brw_context *brw)
> {
> - struct gl_context *ctx = &brw->intel.ctx;
> + struct intel_context *intel = &brw->intel;
> + struct gl_context *ctx = &intel->ctx;
> +
> + /* BRW_NEW_VERTEX_PROGRAM and BRW_NEW_FRAGMENT_PROGRAM:
> + * Unfortunately, we're stuck using the gl_program structs until the
> + * ARB_fragment_program front-end gets converted to GLSL IR. These
> + * have the downside that SamplerUnits is split and only contains the
> + * mappings for samplers active in that stage.
> + */
>
A duplicate of this comment would be helpful in brw_upload_samplers() and
gen7_upload_samplers() too.
> + struct gl_program *vs = (struct gl_program *) brw->vertex_program;
> + struct gl_program *fs = (struct gl_program *) brw->fragment_program;
>
> - for (unsigned i = 0; i < BRW_MAX_TEX_UNIT; i++) {
> - const struct gl_texture_unit *texUnit = &ctx->Texture.Unit[i];
> - const GLuint surf = SURF_INDEX_TEXTURE(i);
> + unsigned num_samplers = _mesa_bitcount(vs->SamplersUsed |
> fs->SamplersUsed);
>
> - /* _NEW_TEXTURE */
> - if (texUnit->_ReallyEnabled) {
> - brw->intel.vtbl.update_texture_surface(ctx, i,
> brw->wm.surf_offset, surf);
> - } else {
> - brw->wm.surf_offset[surf] = 0;
> + for (unsigned s = 0; s < num_samplers; s++) {
> + brw->vs.surf_offset[SURF_INDEX_VS_TEXTURE(s)] = 0;
> + brw->wm.surf_offset[SURF_INDEX_TEXTURE(s)] = 0;
> +
> + if (vs->SamplersUsed & (1 << s)) {
> + const unsigned unit = vs->SamplerUnits[s];
> +
> + /* _NEW_TEXTURE */
> + if (ctx->Texture.Unit[unit]._ReallyEnabled) {
> + intel->vtbl.update_texture_surface(ctx, unit,
> + brw->vs.surf_offset,
> + SURF_INDEX_VS_TEXTURE(s));
> + }
> }
>
> - /* For now, just mirror the texture setup to the VS slots. */
> - brw->vs.surf_offset[SURF_INDEX_VS_TEXTURE(i)] =
> - brw->wm.surf_offset[surf];
> + if (fs->SamplersUsed & (1 << s)) {
> + const unsigned unit = fs->SamplerUnits[s];
> +
> + /* _NEW_TEXTURE */
> + if (ctx->Texture.Unit[unit]._ReallyEnabled) {
> + intel->vtbl.update_texture_surface(ctx, unit,
> + brw->wm.surf_offset,
> + SURF_INDEX_TEXTURE(s));
> + }
> + }
> }
>
> brw->state.dirty.brw |= BRW_NEW_SURFACES;
> @@ -1262,7 +1285,9 @@ brw_update_texture_surfaces(struct brw_context *brw)
> const struct brw_tracked_state brw_texture_surfaces = {
> .dirty = {
> .mesa = _NEW_TEXTURE,
> - .brw = BRW_NEW_BATCH,
> + .brw = BRW_NEW_BATCH |
> + BRW_NEW_VERTEX_PROGRAM |
> + BRW_NEW_FRAGMENT_PROGRAM,
> .cache = 0
> },
> .emit = brw_update_texture_surfaces,
> diff --git a/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> b/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> index 8969119..379a9c5 100644
> --- a/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> +++ b/src/mesa/drivers/dri/i965/gen7_sampler_state.c
> @@ -188,13 +188,14 @@ gen7_upload_samplers(struct brw_context *brw)
> {
> struct gl_context *ctx = &brw->intel.ctx;
> struct gen7_sampler_state *samplers;
> - int i;
>
> - brw->sampler.count = 0;
> - for (i = 0; i < BRW_MAX_TEX_UNIT; i++) {
> - if (ctx->Texture.Unit[i]._ReallyEnabled)
> - brw->sampler.count = i + 1;
> - }
> + /* BRW_NEW_VERTEX_PROGRAM and BRW_NEW_FRAGMENT_PROGRAM */
> + struct gl_program *vs = (struct gl_program *) brw->vertex_program;
> + struct gl_program *fs = (struct gl_program *) brw->fragment_program;
> +
> + GLbitfield SamplersUsed = vs->SamplersUsed | fs->SamplersUsed;
> +
> + brw->sampler.count = _mesa_bitcount(SamplersUsed);
>
> if (brw->sampler.count == 0)
> return;
> @@ -204,9 +205,13 @@ gen7_upload_samplers(struct brw_context *brw)
> 32, &brw->sampler.offset);
> memset(samplers, 0, brw->sampler.count * sizeof(*samplers));
>
> - for (i = 0; i < brw->sampler.count; i++) {
> - if (ctx->Texture.Unit[i]._ReallyEnabled)
> - gen7_update_sampler_state(brw, i, i, &samplers[i]);
> + for (unsigned s = 0; s < brw->sampler.count; s++) {
> + if (SamplersUsed & (1 << s)) {
> + const unsigned unit = (fs->SamplersUsed & (1 << s)) ?
> + fs->SamplerUnits[s] : vs->SamplerUnits[s];
> + if (ctx->Texture.Unit[unit]._ReallyEnabled)
> + gen7_update_sampler_state(brw, unit, s, &samplers[s]);
> + }
> }
>
> brw->state.dirty.cache |= CACHE_NEW_SAMPLER;
> @@ -215,7 +220,9 @@ gen7_upload_samplers(struct brw_context *brw)
> const struct brw_tracked_state gen7_samplers = {
> .dirty = {
> .mesa = _NEW_TEXTURE,
> - .brw = BRW_NEW_BATCH,
> + .brw = BRW_NEW_BATCH |
> + BRW_NEW_VERTEX_PROGRAM |
> + BRW_NEW_FRAGMENT_PROGRAM,
> .cache = 0
> },
> .emit = gen7_upload_samplers,
> --
> 1.7.11.4
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>
I admit to being pretty ignorant about this corner of the code, so for this
patch let's just say
Acked-by: Paul Berry <stereotype...@gmail.com>
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