[Mesa-dev] [PATCH] glsl: only match gl_FragData and not gl_SecondaryFragDataEXT

[Ilia Mirkin]

There's special logic around finding gl_FragData. It latches onto any
array with FRAG_RESULT_DATA0. However gl_SecondaryFragDataEXT[], added
by GL_EXT_blend_func_extended, fits those parameters as well. The real
frag data array should have index 0 though, so we can use that to
distinguish them.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=96617
Signed-off-by: Ilia Mirkin <imirkin at alum.mit.edu>
Cc: "11.1 11.2 12.0" <mesa-stable at lists.freedesktop.org>
---

TBH I don't fully understand all this code. However this makes a hacked-up piglit test pass. This should go through a full testing cycle before being pushed to make sure it doesn't break anything in the process.

 src/compiler/glsl/opt_dead_builtin_varyings.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/compiler/glsl/opt_dead_builtin_varyings.cpp b/src/compiler/glsl/opt_dead_builtin_varyings.cpp
index 37bcbcc..0f9fdb3 100644
--- a/src/compiler/glsl/opt_dead_builtin_varyings.cpp
+++ b/src/compiler/glsl/opt_dead_builtin_varyings.cpp
@@ -88,7 +88,9 @@ public:
       if (!var || var->data.mode != this->mode || !var->type->is_array())
          return visit_continue;
 
-      if (this->find_frag_outputs && var->data.location == FRAG_RESULT_DATA0) {
+      /* Only match gl_FragData[], not gl_SecondaryFragDataEXT[] */
+      if (this->find_frag_outputs && var->data.location == FRAG_RESULT_DATA0 &&
+          var->data.index == 0) {
          this->fragdata_array = var;
 
          ir_constant *index = ir->array_index->as_constant();
-- 
2.7.3