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On 06/15/2011 11:00 AM, Kenneth Graunke wrote:
> On 06/15/2011 08:27 AM, Eric Anholt wrote:
>> On Wed, 15 Jun 2011 01:24:54 -0700, Kenneth
>> Graunke<kenn...@whitecape.org> wrote:
>>> Gen4-6 don't have a sample_d_c message, so we have to do a regular
>>> sample_d and emit instructions to manually perform the comparison.
>>>
>>> This requires a state dependent recompile whenever ctx->Depth.Func
>>> changes. do_wm_prog looks for a compiled program in the cache based off
>>> of brw_wm_prog_key, and if it doesn't find one, recompiles. So we
>>> simply need to add the depth comparison function to the key; the
>>> _NEW_DEPTH dirty bit was already in-place.
>>
>>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> index 03687ce..67344bd 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>>> @@ -744,7 +744,7 @@ fs_visitor::emit_texture_gen5(ir_texture *ir,
>>> fs_reg dst, fs_reg coordinate,
>>> }
>>> mlen += ir->coordinate->type->vector_elements * reg_width;
>>>
>>> - if (ir->shadow_comparitor) {
>>> + if (ir->shadow_comparitor&& ir->op != ir_txd) {
>>> mlen = MAX2(mlen, header_present + 4 * reg_width);
>>>
>>> this->result = reg_undef;
>>> @@ -934,6 +934,21 @@ fs_visitor::visit(ir_texture *ir)
>>> int sampler = _mesa_get_sampler_uniform_value(ir->sampler,
>>> prog,&fp->Base);
>>> sampler = fp->Base.SamplerUnits[sampler];
>>>
>>> + /* Pre-Ivybridge doesn't have a sample_d_c message, so shadow
>>> compares
>>> + * for textureGrad/TXD need to be emulated with instructions.
>>> + */
>>> + bool hw_compare_supported = ir->op != ir_txd || intel->gen> 7;
>>> + if (ir->shadow_comparitor&& !hw_compare_supported) {
>>> + /* Mark that this program is only valid for the current
>>> glDepthFunc */
>>> + c->key.depth_compare_func = ctx->Depth.Func;
>>
>> The compiler is only called if the key wasn't found in the cache, so you
>> can't set the key inside the compiler :)
>
> You're right, of course. Unfortunately, I really want to! Only shaders
> using shadow2DGradARB need to be recompiled when glDepthFunc changes, so
> I really want to leave it as 0 for most shaders. Otherwise the common
> case will have completely pointless recompiles.
>
> Unfortunately, I only know whether or not I need it at compile time...
>
> This -almost- works...it just means we'll recompile shaders using
> shadow2DGradARB every time, since they'll never be found in the cache.
> Stupid. I'll reply with a patch which works around this.
We could always add a flag in the gl_shader_program that the program
uses TXD. You could force c->key.depth_compare_func to 0 whenever that
flag is zero. Or we could put a similar flag in the brw_fs structure
and do a preprocessing step to set it. Right?
>>> +
>>> + /* No need to even sample for GL_ALWAYS or GL_NEVER...bail
>>> early */
>>> + if (ctx->Depth.Func == GL_ALWAYS)
>>> + return swizzle_shadow_result(ir, fs_reg(1.0f), sampler);
>>> + else if (ctx->Depth.Func == GL_NEVER)
>>> + return swizzle_shadow_result(ir, fs_reg(0.0f), sampler);
>>> + }
>>
>> Generally I use "c->key." values to make it obvious that state dependent
>> recompiles are in place, instead of "ctx->".
>
> Good idea. Updated.
>
>>> diff --git a/src/mesa/drivers/dri/i965/brw_wm.h
>>> b/src/mesa/drivers/dri/i965/brw_wm.h
>>> index e244b55..0b284b6 100644
>>> --- a/src/mesa/drivers/dri/i965/brw_wm.h
>>> +++ b/src/mesa/drivers/dri/i965/brw_wm.h
>>> @@ -67,6 +67,7 @@ struct brw_wm_prog_key {
>>> GLuint alpha_test:1;
>>> GLuint clamp_fragment_color:1;
>>> GLuint line_aa:2;
>>> + uint8_t depth_compare_func; /* 0 if irrelevant, GL_LESS etc.
>>> otherwise */
>>
>> Wow, those do happen to fit in 8 bits. Might comment that explicitly --
>> leaving out bits when storing GLenums has been a common bug and seeing
>> things like this make me paranoid and go check :)
>
> :) Makes sense; commented. I figured we really want to pack the key.
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