On Thu, Apr 24, 2014 at 8:50 PM, Eric Anholt <e...@anholt.net> wrote:
> Instead of walking 6 shader stages for each of the 96 combined texture
> image units, now we just walk the samplers used in each shader stage.
>
> With cairo-perf-trace on Xephyr with glamor, I'm seeing a -6.50518% +/-
> 2.55601% effect on runtime (n=22) since the "drop _EnabledUnits" change.
> No significant performance difference on an apitrace of minecraft (n=442).
> ---
> src/mesa/main/texstate.c | 122
> ++++++++++++++++++++++++++++-------------------
> 1 file changed, 73 insertions(+), 49 deletions(-)
>
> diff --git a/src/mesa/main/texstate.c b/src/mesa/main/texstate.c
> index 0082caf..3a7e227 100644
> --- a/src/mesa/main/texstate.c
> +++ b/src/mesa/main/texstate.c
> @@ -515,68 +515,92 @@ update_texgen(struct gl_context *ctx)
> }
> }
>
> +static struct gl_texture_object *
> +update_single_program_texture(struct gl_context *ctx, struct gl_program
> *prog,
> + int s)
> +{
> + gl_texture_index target_index;
> + struct gl_texture_unit *texUnit;
> + struct gl_texture_object *texObj;
> + int unit;
> +
> + if (!(prog->SamplersUsed & (1 << s)))
> + return NULL;
> +
> + unit = prog->SamplerUnits[s];
> + texUnit = &ctx->Texture.Unit[unit];
> +
> + /* Note: If more than one bit was set in TexturesUsed[unit], then we
> should
> + * have had the draw call rejected already. From the GL 4.4
> specification,
> + * section 7.10 ("Samplers"):
> + *
> + * "It is not allowed to have variables of different sampler types
> + * pointing to the same texture image unit within a program
> + * object. This situation can only be detected at the next rendering
> + * command issued which triggers shader invocations, and an
> + * INVALID_OPERATION error will then be generated."
> + */
> + target_index = ffs(prog->TexturesUsed[unit]) - 1;
> + texObj = texUnit->CurrentTex[target_index];
> +
> + struct gl_sampler_object *sampler = texUnit->Sampler ?
> + texUnit->Sampler : &texObj->Sampler;
> +
> + if (likely(texObj)) {
> + if (_mesa_is_texture_complete(texObj, sampler))
> + return texObj;
> +
> + _mesa_test_texobj_completeness(ctx, texObj);
> + if (_mesa_is_texture_complete(texObj, sampler))
> + return texObj;
> + }
> +
> + /* If we've reached this point, we didn't find a complete texture of the
> + * shader's target. From the GL 4.4 core specification, section 11.1.3.5
> + * ("Texture Access"):
> + *
> + * "If a sampler is used in a shader and the sampler’s associated
> + * texture is not complete, as defined in section 8.17, (0, 0, 0, 1)
> + * will be returned for a non-shadow sampler and 0 for a shadow
> + * sampler."
> + *
> + * Mesa implements this by creating a hidden texture object with a pixel
> of
> + * that value.
> + */
> + texObj = _mesa_get_fallback_texture(ctx, target_index);
> + assert(texObj);
> +
> + return texObj;
> +}
> +
> static void
> update_program_texture_state(struct gl_context *ctx, struct gl_program
> **prog,
> BITSET_WORD *enabled_texture_units)
> {
> - GLuint unit;
> int i;
>
> - for (unit = 0; unit < ctx->Const.MaxCombinedTextureImageUnits; unit++) {
> - struct gl_texture_unit *texUnit = &ctx->Texture.Unit[unit];
> - GLbitfield enabledTargets = 0x0;
> - GLuint texIndex;
> -
> - for (i = 0; i < MESA_SHADER_STAGES; i++) {
> - if (prog[i])
> - enabledTargets |= prog[i]->TexturesUsed[unit];
> - }
> + for (i = 0; i < MESA_SHADER_STAGES; i++) {
> + int s;
>
> - if (enabledTargets == 0x0) {
> - /* neither vertex nor fragment processing uses this unit */
> + if (!prog[i])
> continue;
> - }
> -
> - for (texIndex = 0; texIndex < NUM_TEXTURE_TARGETS; texIndex++) {
> - if (enabledTargets & (1 << texIndex)) {
> - struct gl_texture_object *texObj = texUnit->CurrentTex[texIndex];
> - struct gl_sampler_object *sampler = texUnit->Sampler ?
> - texUnit->Sampler : &texObj->Sampler;
> -
> - if (!_mesa_is_texture_complete(texObj, sampler)) {
> - _mesa_test_texobj_completeness(ctx, texObj);
> - }
> - if (_mesa_is_texture_complete(texObj, sampler)) {
> - _mesa_reference_texobj(&texUnit->_Current, texObj);
> - break;
> - }
> - }
> - }
>
> - if (texIndex == NUM_TEXTURE_TARGETS) {
> - /* If we get here it means the shader is expecting a texture
> - * object, but there isn't one (or it's incomplete). Use the
> - * fallback texture.
> - */
> + /* We can't only do the shifting trick as the loop condition because if
> + * sampler 31 is active, the next iteration tries to shift by 32,
> which is
> + * undefined.
> + */
> + for (s = 0; s < MAX_SAMPLERS && (1 << s) <= prog[i]->SamplersUsed;
> s++) {
I could be confused, but are you trying to walk over all set bits of
SamplersUsed? You can do this with something like u_bit_scan() which
basically does
tmp = prog[i]->SamplersUsed;
while (tmp) {
s = ffs(tmp) - 1;
tmp &= ~(1 << s);
...
}
This should avoid pointless iteration when there are just a few bits
set. If the expectation is that 1..n bits are all going to be set,
then this provides little advantage.
-ilia
> struct gl_texture_object *texObj;
> - gl_texture_index texTarget;
> -
> - texTarget = (gl_texture_index) (ffs(enabledTargets) - 1);
> - texObj = _mesa_get_fallback_texture(ctx, texTarget);
>
> - assert(texObj);
> - if (!texObj) {
> - /* invalid fallback texture: don't enable the texture unit */
> - continue;
> + texObj = update_single_program_texture(ctx, prog[i], s);
> + if (texObj) {
> + int unit = prog[i]->SamplerUnits[s];
> + _mesa_reference_texobj(&ctx->Texture.Unit[unit]._Current,
> texObj);
> + BITSET_SET(enabled_texture_units, unit);
> + ctx->Texture._MaxEnabledTexImageUnit =
> + MAX2(ctx->Texture._MaxEnabledTexImageUnit, (int)unit);
> }
> -
> - _mesa_reference_texobj(&texUnit->_Current, texObj);
> }
> -
> - /* if we get here, we know this texture unit is enabled */
> - BITSET_SET(enabled_texture_units, unit);
> - ctx->Texture._MaxEnabledTexImageUnit =
> - MAX2(ctx->Texture._MaxEnabledTexImageUnit, (int)unit);
> }
>
> if (prog[MESA_SHADER_FRAGMENT]) {
> --
> 1.9.2
>
>
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