mesa/program_interface_query: fix transform feedback varyings.

The spec says gl_NextBuffer and gl_SkipComponents need to be
returned to userspace in the program interface queries.

We currently throw those away, this requires a complete piglit
run to make sure no drivers fallover due to the extra varyings.

This fixes:
GL45-CTS.program_interface_query.transform-feedback-built-in

Reviewed-by: Timothy Arceri <timothy.arceri@collabora.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

src/compiler/glsl/link_varyings.cpp

@@ -812,15 +812,20 @@ tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,
                       const unsigned max_outputs, bool *explicit_stride,
                       bool has_xfb_qualifiers) const
 {
-   assert(!this->next_buffer_separator);
+   unsigned xfb_offset = 0;
-
+   unsigned size = this->size;
    /* Handle gl_SkipComponents. */
    if (this->skip_components) {
       info->Buffers[buffer].Stride += this->skip_components;
-      return true;
+      size = this->skip_components;
+      goto store_varying;
+   }
+
+   if (this->next_buffer_separator) {
+      size = 0;
+      goto store_varying;
    }
 
-   unsigned xfb_offset = 0;
    if (has_xfb_qualifiers) {
       xfb_offset = this->offset / 4;
    } else {
@@ -828,6 +833,7 @@ tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,
    }
    info->Varyings[info->NumVarying].Offset = xfb_offset * 4;
 
+   {
       unsigned location = this->location;
       unsigned location_frac = this->location_frac;
       unsigned num_components = this->num_components();
@@ -860,6 +866,7 @@ tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,
          location++;
          location_frac = 0;
       }
+   }
 
    if (explicit_stride && explicit_stride[buffer]) {
       if (this->is_double() && info->Buffers[buffer].Stride % 2) {
@@ -903,10 +910,11 @@ tfeedback_decl::store(struct gl_context *ctx, struct gl_shader_program *prog,
       return false;
    }
 
+ store_varying:
    info->Varyings[info->NumVarying].Name = ralloc_strdup(prog,
                                                          this->orig_name);
    info->Varyings[info->NumVarying].Type = this->type;
-   info->Varyings[info->NumVarying].Size = this->size;
+   info->Varyings[info->NumVarying].Size = size;
    info->Varyings[info->NumVarying].BufferIndex = buffer_index;
    info->NumVarying++;
    info->Buffers[buffer].NumVaryings++;
@@ -1101,6 +1109,11 @@ store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
          }
 
          if (tfeedback_decls[i].is_next_buffer_separator()) {
+            if (!tfeedback_decls[i].store(ctx, prog,
+                                          &prog->LinkedTransformFeedback,
+                                          buffer, num_buffers, num_outputs,
+                                          explicit_stride, has_xfb_qualifiers))
+               return false;
             num_buffers++;
             buffer_stream_id = -1;
             continue;

src/mesa/main/shader_query.cpp

@@ -1143,7 +1143,7 @@ _mesa_program_resource_prop(struct gl_shader_program *shProg,
          *val = MAX2(_mesa_program_resource_array_size(res), 1);
          return 1;
       case GL_TRANSFORM_FEEDBACK_VARYING:
-         *val = MAX2(RESOURCE_XFV(res)->Size, 1);
+         *val = RESOURCE_XFV(res)->Size;
          return 1;
       default:
          goto invalid_operation;