[Mesa-dev] [PATCH] spirv: Builtin Layer is an input for fragment shaders

[Iago Toral Quiroga]

This change makes it so we emit a load_input intrinsic when Layer
is read in a fragment shader.
---

Even with this, layered rendering does not seem to work in the Vulkan
driver, so there is something else that is broken. We are probably
not mapping the Layer input correctly somewhere.

 src/compiler/spirv/vtn_variables.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/compiler/spirv/vtn_variables.c b/src/compiler/spirv/vtn_variables.c
index 14366dc..c6d73a7 100644
--- a/src/compiler/spirv/vtn_variables.c
+++ b/src/compiler/spirv/vtn_variables.c
@@ -819,7 +819,12 @@ vtn_get_builtin_location(struct vtn_builder *b,
       break;
    case SpvBuiltInLayer:
       *location = VARYING_SLOT_LAYER;
-      *mode = nir_var_shader_out;
+      if (b->shader->stage == MESA_SHADER_FRAGMENT)
+         *mode = nir_var_shader_in;
+      else if (b->shader->stage == MESA_SHADER_GEOMETRY)
+         *mode = nir_var_shader_out;
+      else
+         unreachable("invalid stage for SpvBuiltInLayer");
       break;
    case SpvBuiltInViewportIndex:
       *location = VARYING_SLOT_VIEWPORT;
-- 
2.7.4