[Mesa-dev] [PATCH 11/12] genX/cmd_buffer: Enable fast depth clears

[Nanley Chery]

On Fri, Sep 02, 2016 at 05:12:58PM -0700, Jason Ekstrand wrote:
> On Wed, Aug 31, 2016 at 8:29 PM, Nanley Chery <nanleychery at gmail.com> wrote:
> 
> > Provides an FPS increase of ~30% on the Sascha triangle and multisampling
> > demos.
> >
> > Clears that happen within a render pass via vkCmdClearAttachments are safe
> > even if the clear color changes. This is because the meta implementation
> > does
> > not use LOAD_OP_CLEAR which avoids any conflicts with 3DSTATE_CLEAR_PARAMS.
> >
> > Signed-off-by: Nanley Chery <nanley.g.chery at intel.com>
> > ---
> >  src/intel/vulkan/anv_pass.c        | 11 +++++++++++
> >  src/intel/vulkan/gen8_cmd_buffer.c |  6 ++++++
> >  src/intel/vulkan/genX_cmd_buffer.c |  4 +---
> >  3 files changed, 18 insertions(+), 3 deletions(-)
> >
> > diff --git a/src/intel/vulkan/anv_pass.c b/src/intel/vulkan/anv_pass.c
> > index 69c3c7e..823f9cf 100644
> > --- a/src/intel/vulkan/anv_pass.c
> > +++ b/src/intel/vulkan/anv_pass.c
> > @@ -155,5 +155,16 @@ void anv_GetRenderAreaGranularity(
> >      VkRenderPass                                renderPass,
> >      VkExtent2D*                                 pGranularity)
> >  {
> > +   ANV_FROM_HANDLE(anv_render_pass, pass, renderPass);
> > +
> > +   /* This granularity is needed for HiZ fast clears */
> > +   for (unsigned i = 0; i < pass->subpass_count; ++i) {
> > +      if (pass->subpasses[i].depth_stencil_attachment !=
> > +          VK_ATTACHMENT_UNUSED) {
> > +         *pGranularity = (VkExtent2D) { 8, 4 };
> > +         return;
> > +      }
> > +   }
> >
> 
> Thanks for remembering this!  As mentioned in an earlier e-mail, I'm not
> sure this is needed for Sky Lake or Broadwell with a format other than
> D16_UNORM but setting it all the time doesn't hurt.  8x4 isn't onerous and
> once we get fast clears, it'll get much bigger anyway.
> 
> 

Np. It's a bit unfortunate that the Vulkan apps I've tested don't call
this function. I do need to update the comment as it's not exactly true
(gen8 can have smaller alignments depending on the sample count).

> > +
> >     *pGranularity = (VkExtent2D) { 1, 1 };
> >  }
> > diff --git a/src/intel/vulkan/gen8_cmd_buffer.c
> > b/src/intel/vulkan/gen8_cmd_buffer.c
> > index 7f65fe2..ec91ecd 100644
> > --- a/src/intel/vulkan/gen8_cmd_buffer.c
> > +++ b/src/intel/vulkan/gen8_cmd_buffer.c
> > @@ -451,6 +451,12 @@ genX(cmd_buffer_do_hz_op)(struct anv_cmd_buffer
> > *cmd_buffer, enum anv_hz_op op)
> >               cmd_state->render_area.extent.height % align_h)
> >              return;
> >        }
> > +
> > +      anv_batch_emit(&cmd_buffer->batch, GENX(3DSTATE_CLEAR_PARAMS), cp)
> > {
> > +         cp.DepthClearValueValid = true;
> > +         cp.DepthClearValue =
> > +            cmd_buffer->state.attachments[ds].clear_value.depthStencil.
> > depth;
> > +      }
> >
> 
> Hrm... I'm not sure where the best place to set CLEAR_PARAMS is.  It might
> almost be better in BeginSubpass...  In any case, I think this works.  We
> can move it later if we want.
> 
> 
> >        break;
> >     case ANV_HZ_OP_DEPTH_RESOLVE:
> >        if (cmd_buffer->state.pass->attachments[ds].store_op !=
> > diff --git a/src/intel/vulkan/genX_cmd_buffer.c
> > b/src/intel/vulkan/genX_cmd_buffer.c
> > index 349d2a4..7d2a6bd 100644
> > --- a/src/intel/vulkan/genX_cmd_buffer.c
> > +++ b/src/intel/vulkan/genX_cmd_buffer.c
> > @@ -1159,9 +1159,6 @@ cmd_buffer_emit_depth_stencil(struct anv_cmd_buffer
> > *cmd_buffer)
> >     } else {
> >        anv_batch_emit(&cmd_buffer->batch, GENX(3DSTATE_STENCIL_BUFFER),
> > sb);
> >     }
> > -
> > -   /* Clear the clear params. */
> > -   anv_batch_emit(&cmd_buffer->batch, GENX(3DSTATE_CLEAR_PARAMS), cp);
> >  }
> >
> >  /**
> > @@ -1196,6 +1193,7 @@ void genX(CmdBeginRenderPass)(
> >
> >     genX(cmd_buffer_set_subpass)(cmd_buffer, pass->subpasses);
> >     genX(cmd_buffer_do_hz_op)(cmd_buffer, ANV_HZ_OP_HIZ_RESOLVE);
> > +   genX(cmd_buffer_do_hz_op)(cmd_buffer, ANV_HZ_OP_CLEAR);
> >     anv_cmd_buffer_clear_subpass(cmd_buffer);
> >  }
> >
> > --
> > 2.9.3
> >
> >