[Mesa-dev] [PATCH 0/4] Clean up dFdy() bug fix.

Kenneth Graunke kenneth at whitecape.org
Wed Jul 18 15:11:19 PDT 2012

On 07/18/2012 12:16 PM, Paul Berry wrote:
> This patch series cleans up a bug fix I made to Mesa on June 22
> (commit 82d2596: i965: Compute dFdy() correctly for FBOs).  The bug
> was that the i965 driver wasn't adjusting the dFdy() logic to account
> for the fact that window system framebuffers use flipped Y coordinates
> compared to FBOs.  The fix was to compile fragment shaders differently
> when they are used for FBOs vs window system framebuffers.
> Commit 82d2596 conservatively assumed that all fragment shader
> programs might use dFdy(), so it recompiled all of them when switching
> between FBOs and window system framebuffers.  For shaders that don't
> use dFdy(), the recompile is an unnecessary performance hit.  This
> patch series adds accounting to core mesa to keep track of whether or
> not a shader uses dFdy(), and changes the i965 back-end to only
> recompile shaders that actually need it.
> Patches 1-3 may be of interest to non-i965 developers, since the
> accounting in core Mesa applies to all back-ends.
> [PATCH 1/4] mesa: Add UsesDFdy to struct gl_fragment_program.
> [PATCH 2/4] mesa: Set UsesDFdy appropriately for assembly programs.
> [PATCH 3/4] glsl: Set UsesDFdy appropriately for GLSL shaders.
> [PATCH 4/4] i965: Avoid unnecessary recompiles for shaders that don't use dFdy().

Looks fine to me, but please get Ian's ack before pushing.

For the series:
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

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