st/mesa: fix transform feedback of unsubscripted gl_ClipDistance array

gl_ClipDistance needs special treatment in form of lowering pass
which transforms gl_ClipDistance representation from float[] to
vec4[]. There are 2 implementations - at glsl linker level (enabled
by LowerClipDistance option) and at glsl_to_tgsi level (enabled
unconditionally for gallium drivers). Second implementation is
incomplete - it does not take into account transform feedback (see
commit 642e5b413e0890b2070ba78fde42db381eaf02e5 "mesa: Fix transform
feedback of unsubscripted gl_ClipDistance array" for details).

There are 2 possible fixes:
- adding transform feedback support into glsl_to_tgsi version
- ripping gl_ClipDistance support from glsl_to_tgsi and enabling
  gl_ClipDistance lowering on glsl linker side

This patch implements 2nd option. All it does is:
- reverts most of the commit 59be691638200797583bce39a83f641d30d97492
  "st/mesa: add support for gl_ClipDistance"
- changes LowerClipDistance to true

Fixes Piglit tests "EXT_transform_feedback/builtin-varyings
gl_ClipDistance[{2,3,4,5,6,7,8}]-no-subscript" at least on nv50
and evergreen cards.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
index 17f271f02c1..dacad9bfb91 100644
--- a/src/mesa/state_tracker/st_extensions.c
+++ b/src/mesa/state_tracker/st_extensions.c
@@ -222,6 +222,7 @@ void st_init_limits(struct st_context *st)
          options->MaxUnrollIterations = MIN2(screen->get_shader_param(screen, sh, PIPE_SHADER_CAP_MAX_INSTRUCTIONS), 65536);
       else
          options->MaxUnrollIterations = 255; /* SM3 limit */
+      options->LowerClipDistance = true;
    }
 
    /* PIPE_SHADER_CAP_MAX_INPUTS for the FS specifies the maximum number