softpipe: fix unreliable FS variant binding bug

In exec_prepare() we were comparing pointers to see if the fragment
shader variant had changed before calling tgsi_exec_machine_bind_shader().
This didn't work reliably when there was a lot of shader token malloc/
freeing going on because the memory might get reused.
Instead, bind the shader variant during regular state validation.

Fixes http://bugs.freedesktop.org/show_bug.cgi?id=40404
(fixes a couple of piglit's glsl-max-varyings test)

Note: This is a candidate for the stable branches.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/gallium/drivers/softpipe/sp_state_derived.c b/src/gallium/drivers/softpipe/sp_state_derived.c
index cb954a17ef6..e4a5a632097 100644
--- a/src/gallium/drivers/softpipe/sp_state_derived.c
+++ b/src/gallium/drivers/softpipe/sp_state_derived.c
@@ -242,6 +242,12 @@ update_fragment_shader(struct softpipe_context *softpipe, unsigned prim)
    if (softpipe->fs) {
       softpipe->fs_variant = softpipe_find_fs_variant(softpipe,
                                                       softpipe->fs, &key);
+
+      /* prepare the TGSI interpreter for FS execution */
+      softpipe->fs_variant->prepare(softpipe->fs_variant, 
+                                    softpipe->fs_machine,
+                                    (struct tgsi_sampler **) softpipe->
+                                    tgsi.samplers_list[PIPE_SHADER_FRAGMENT]);
    }
    else {
       softpipe->fs_variant = NULL;