[Mesa-dev] [PATCH] i965/fs: Don't use brw->fragment_program in calculate_urb_setup().

[Kenneth Graunke]

Reading brw->fragment_program is nonsensical in compiler code: it
contains the currently active program (if any), not the one currently
being compiled.  Attempting to access it may either lead to crashes
(null pointer dereference if no program is active) or wrong results.

Fixes piglit regressions since 9ef710575b914ddfc8e9a162d98ad554c1c217f7
on pre-Sandybridge hardware.  The actual bug was created in commit
7b1fbc688999fd568e65211d79d7678562061594.

NOTE: This is a candidate for the 9.0 and 8.0 branches.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=54183
Cc: Rico Tzschichholz <ricotz at t-online.de>
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_fs.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

As I suspected: the precompile just exposed a bug that'd been lurking for
a while (February 2012 to be precise).

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index a8d55ff..167ea08 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -979,7 +979,7 @@ fs_visitor::calculate_urb_setup()
        *
        * See compile_sf_prog() for more info.
        */
-      if (brw->fragment_program->Base.InputsRead & BITFIELD64_BIT(FRAG_ATTRIB_PNTC))
+      if (fp->Base.InputsRead & BITFIELD64_BIT(FRAG_ATTRIB_PNTC))
          urb_setup[FRAG_ATTRIB_PNTC] = urb_next++;
    }
 
-- 
1.7.11.4