compiler: add a new explicit interpolation mode

This introduces one more interpolation mode INTERP_MODE_EXPLICIT,
which is needed for AMD_shader_explicit_vertex_parameter.

Signed-off-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
Reviewed-by: Bas Nieuwenhuizen <bas@basnieuwenhuizen.nl>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/merge_requests/3578>

src/compiler/glsl/ir_print_visitor.cpp

@@ -213,7 +213,7 @@ void ir_print_visitor::visit(ir_variable *ir)
                                 "in ", "out ", "inout ",
 			        "const_in ", "sys ", "temporary " };
    STATIC_ASSERT(ARRAY_SIZE(mode) == ir_var_mode_count);
-   const char *const interp[] = { "", "smooth", "flat", "noperspective" };
+   const char *const interp[] = { "", "smooth", "flat", "noperspective", "explicit" };
    STATIC_ASSERT(ARRAY_SIZE(interp) == INTERP_MODE_COUNT);
 
    fprintf(f, "(%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s) ",

src/compiler/glsl_types.h

@@ -1254,7 +1254,7 @@ struct glsl_struct_field {
     * For interface blocks, the interpolation mode (as in
     * ir_variable::interpolation).  0 otherwise.
     */
-   unsigned interpolation:2;
+   unsigned interpolation:3;
 
    /**
     * For interface blocks, 1 if this variable uses centroid interpolation (as

src/compiler/nir/nir.h

@@ -378,7 +378,7 @@ typedef struct nir_variable {
        *
        * \sa glsl_interp_mode
        */
-      unsigned interpolation:2;
+      unsigned interpolation:3;
 
       /**
        * If non-zero, then this variable may be packed along with other variables

src/compiler/shader_enums.c

@@ -269,6 +269,7 @@ glsl_interp_mode_name(enum glsl_interp_mode qual)
       ENUM(INTERP_MODE_SMOOTH),
       ENUM(INTERP_MODE_FLAT),
       ENUM(INTERP_MODE_NOPERSPECTIVE),
+      ENUM(INTERP_MODE_EXPLICIT),
    };
    STATIC_ASSERT(ARRAY_SIZE(names) == INTERP_MODE_COUNT);
    return NAME(qual);

src/compiler/shader_enums.h

@@ -667,6 +667,7 @@ enum glsl_interp_mode
    INTERP_MODE_SMOOTH,
    INTERP_MODE_FLAT,
    INTERP_MODE_NOPERSPECTIVE,
+   INTERP_MODE_EXPLICIT,
    INTERP_MODE_COUNT /**< Number of interpolation qualifiers */
 };