Mesa (master): glsl: restrict consumer stage condition to modify interpolation type

[Samuel Iglesias Gonsálvez]

Module: Mesa
Branch: master
Commit: 781d2787bc1cf975757a95d0d9324f734fa61c09
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=781d2787bc1cf975757a95d0d9324f734fa61c09

Author: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Date:   Tue Jan 12 15:36:56 2016 +0100

glsl: restrict consumer stage condition to modify interpolation type

Only modify interpolation type for integer-based varyings or when the
consumer is known and different than fragment shader.

If we are linking separate shader programs and the consumer is unknown,
the consumer could be added later and be a fragment shader. If we
modify the interpolation type in this case, we could read wrong
values in the fragment shader inputs, as shown in bug 93320.

Fixes the following CTS test:
   ES31-CTS.vertex_attrib_binding.advanced-bindingUpdate

Fixes the following dEQP tests:

dEQP-GLES31.functional.separate_shader.random.102
dEQP-GLES31.functional.separate_shader.random.111
dEQP-GLES31.functional.separate_shader.random.115
dEQP-GLES31.functional.separate_shader.random.17
dEQP-GLES31.functional.separate_shader.random.22
dEQP-GLES31.functional.separate_shader.random.23
dEQP-GLES31.functional.separate_shader.random.3
dEQP-GLES31.functional.separate_shader.random.32
dEQP-GLES31.functional.separate_shader.random.39
dEQP-GLES31.functional.separate_shader.random.64
dEQP-GLES31.functional.separate_shader.random.73
dEQP-GLES31.functional.separate_shader.random.91

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93320
Signed-off-by: Samuel Iglesias Gonsálvez <siglesias at igalia.com>
Reviewed-by: Tapani Pälli <tapani.palli at intel.com>

---

 src/glsl/link_varyings.cpp |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/glsl/link_varyings.cpp b/src/glsl/link_varyings.cpp
index 7cc5880..09f80d0 100644
--- a/src/glsl/link_varyings.cpp
+++ b/src/glsl/link_varyings.cpp
@@ -968,10 +968,12 @@ varying_matches::record(ir_variable *producer_var, ir_variable *consumer_var)
    }
 
    if ((consumer_var == NULL && producer_var->type->contains_integer()) ||
-       consumer_stage != MESA_SHADER_FRAGMENT) {
+       (consumer_stage != -1 && consumer_stage != MESA_SHADER_FRAGMENT)) {
       /* Since this varying is not being consumed by the fragment shader, its
-       * interpolation type varying cannot possibly affect rendering.  Also,
-       * this variable is non-flat and is (or contains) an integer.
+       * interpolation type varying cannot possibly affect rendering.
+       * Also, this variable is non-flat and is (or contains) an integer.
+       * If the consumer stage is unknown, don't modify the interpolation
+       * type as it could affect rendering later with separate shaders.
        *
        * lower_packed_varyings requires all integer varyings to flat,
        * regardless of where they appear.  We can trivially satisfy that