glsl: set user defined varyings to smooth by default in ES

This is usually handled by the backends in order to handle the
various interactions with the gl_*Color built-ins.

The problem is this means linking will fail if one side on the
interface adds the smooth qualifier to the varying and the other
side just uses the default even though they match.

This fixes various deqp tests. The spec is not clear what to for
desktop GL so leave it as is for now.

Reviewed-by: Iago Toral Quiroga <[email protected]>
Reviewed-by: Ian Romanick <[email protected]>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92743

1 files changed, 11 insertions, 0 deletions

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index b63937899cb..0bb2ba2a5e9 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -2750,6 +2750,17 @@ interpret_interpolation_qualifier(const struct ast_type_qualifier *qual,
                           "vertex shader inputs or fragment shader outputs",
                           interpolation_string(interpolation));
       }
+   } else if (state->es_shader &&
+              ((mode == ir_var_shader_in &&
+                state->stage != MESA_SHADER_VERTEX) ||
+               (mode == ir_var_shader_out &&
+                state->stage != MESA_SHADER_FRAGMENT))) {
+      /* Section 4.3.9 (Interpolation) of the GLSL ES 3.00 spec says:
+       *
+       *    "When no interpolation qualifier is present, smooth interpolation
+       *    is used."
+       */
+      interpolation = INTERP_QUALIFIER_SMOOTH;
    }
 
    return interpolation;