I recently did some piglit testing and noticed two old unreported regressions on my GM45 in tests/spec/arb_fragment_program_shadow/tex-shadow2drect.shader_test and tests/spec/arb_fragment_program_shadow/txp-shadow2drect.shader_test

Its caused by commit 
commit 97615b2d8c7c3cea6fd3a43bcb1739a96e2046c4
Author: Eric Anholt <eric@anholt.net>
Date:   Mon Aug 27 14:35:01 2012 -0700

    i965: Replace brw_wm_* with dumping code into the fs_visitor.
    
    This makes a giant pile of code newly dead.  It also fixes TXB on newer
    chipsets, which has been totally broken (I now have a piglit test for that).
    It passes the same set of Ian's ARB_fragment_program tests.  It also improve
    high-settings ETQW performance by 3.2 +/- 1.9% (n=3), thanks to better
    optimization and having 8-wide along with 16-wide shaders.
    
    Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=24355
    Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

Another regression from that commit was in the past tracked in bug 55825, so I just made a comment in bug 55825 comment 5, cause I thought it is a duplicate. Bug 55825 was however closed some time ago and this regression is still present. 

BTW the tests doesn't fail everytime, there is some chance of pass (like 5-10 passes in 100 runs).

./bin/shader_runner tests/spec/arb_fragment_program_shadow/tex-shadow2drect.shader_test -auto
Output:
Probe at (0,25)
  Expected: 1.000000 1.000000 1.000000 1.000000
  Observed: 0.000000 0.000000 0.000000 1.000000
Probe at (225,249)
  Expected: 1.000000 1.000000 1.000000 1.000000
  Observed: 0.000000 0.000000 0.000000 1.000000

./bin/shader_runner tests/spec/arb_fragment_program_shadow/txp-shadow2drect.shader_test -auto
Output:
Probe at (0,25)
  Expected: 1.000000 1.000000 1.000000 1.000000
  Observed: 0.000000 0.000000 0.000000 1.000000
Probe at (225,249)
  Expected: 1.000000 1.000000 1.000000 1.000000
  Observed: 0.000000 0.000000 0.000000 1.000000

GPU:GM45
Mesa: ec44d56a5b20632bcd4cb19ae6fa5d615df4149f
Kernel: 3.10.11-100.fc18.x86_64
Libdrm: 2.4.45-1.fc18