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      <base href="https://bugs.freedesktop.org/" />
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Make shader precompile guess MSAA layout properly"
   href="https://bugs.freedesktop.org/show_bug.cgi?id=90158">90158</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Make shader precompile guess MSAA layout properly
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>Mesa
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>git
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Other
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>medium
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Drivers/DRI/i965
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>idr@freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>kenneth@whitecape.org
          </td>
        </tr>

        <tr>
          <th>QA Contact</th>
          <td>intel-3d-bugs@lists.freedesktop.org
          </td>
        </tr>

        <tr>
          <th>Blocks</th>
          <td>77547
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Currently, brw_fs_precompile doesn't set compressed_multisample_layout_mask,
leaving it at the default value of 0 (non-CMS).

This is dumb.  Virtually all multisampled color buffers on Gen7+ use the CMS
layout, not UMS or IMS.  So, basically every shader that uses a sampler2DMS
type (including most of WebGL) will require a recompile.

A better guess would be:
- 1 for sampler2DMS on Gen7+ (0 on Gen6)
- 0 for sampler2DMSShadow
- 0 for non-MS sampler types.

This should eliminate almost all recompiles due to
compressed_multisample_layout_mask.

To accomplish this, we may want to create a bitfield similar to SamplersUsed or
ShadowSamplers...SamplerIsMSAA or such.  Then the precompile could easily check
it.  Alternatively, we could stop using bitfields and walk a list of NIR
uniforms.  It should be pretty simple.</pre>
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      </p>
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