glsl: Treat gl_FragCoord as a varying even when it's a system value

This fixes glsl-fcoord-invariant-pass.shader_test on drivers that set
GLSLFragCoordIsSysVal which includes radeonsi among others.

Reviewed-by: Kenneth Graunke <[email protected]>

1 files changed, 3 insertions, 1 deletions

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index 9cd67ab7885..d7c396aa0eb 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -2706,7 +2706,9 @@ is_varying_var(ir_variable *var, gl_shader_stage target)
    case MESA_SHADER_VERTEX:
       return var->data.mode == ir_var_shader_out;
    case MESA_SHADER_FRAGMENT:
-      return var->data.mode == ir_var_shader_in;
+      return var->data.mode == ir_var_shader_in ||
+             (var->data.mode == ir_var_system_value &&
+              var->data.location == SYSTEM_VALUE_FRAG_COORD);
    default:
       return var->data.mode == ir_var_shader_out || var->data.mode == ir_var_shader_in;
    }