Playing WoW with Mesa-git recently, and I discovered that the frame rate had dropped by ~10 FPS. (From 25 FPS to 15 FPS). A git bisect identifies this commit:

$ git bisect bad
6a2baf3a06125405aa648e208af782e53f1312c0 is the first bad commit
commit 6a2baf3a06125405aa648e208af782e53f1312c0
Author: Paul Berry <stereotype441@gmail.com>
Date:  Mon Jun 10 14:01:45 2013 -0700

    glsl/linker: Make update_array_sizes apply to just uniforms.
   
    Commit 586b4b5 (glsl: Also update implicit sizes of varyings at link
    time) extended update_array_sizes() to apply to both uniforms and
    shader ins/outs.  However, doing creates problems for geometry
    shaders, because update_array_sizes() assumes that variables with
    matching names in different parts of the pipeline should have the same
    sizes.  With the addition of geometry shaders, this is no longer true
    (e.g. both vertex and geometry shaders have a gl_ClipDistance output
    variable, but there's no reason these variables should have the same
    sizes).
   
    The original reason for commit 586b4b5 (avoid problems with
    gl_TexCoord being 0 length) has since been addressed by commit 6f53921
    (linker: Ensure that unsized arrays have a size after linking).  So go
    ahead and switch update_array_sizes() back to only acting on uniforms.
   
    Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
    Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

:040000 040000 304adffc0a8c034063a526a7d693fe792399a7d9 77b9d43aacde4ec2172578b7158399d94f6e3b2e M    src