glsl: add transform feedback built-in constants

These are new built-ins added by ARB_enhanced_layouts.

Reviewed-by: Dave Airlie <airlied@redhat.com>

src/compiler/glsl/builtin_variables.cpp

@@ -812,6 +812,13 @@ builtin_variable_generator::generate_constants()
        */
    }
 
+   if (state->has_enhanced_layouts()) {
+      add_const("gl_MaxTransformFeedbackBuffers",
+                state->Const.MaxTransformFeedbackBuffers);
+      add_const("gl_MaxTransformFeedbackInterleavedComponents",
+                state->Const.MaxTransformFeedbackInterleavedComponents);
+   }
+
    if (state->is_version(420, 310) ||
        state->ARB_shader_image_load_store_enable) {
       add_const("gl_MaxImageUnits",

src/compiler/glsl/glsl_parser_extras.cpp

@@ -138,6 +138,10 @@ _mesa_glsl_parse_state::_mesa_glsl_parse_state(struct gl_context *_ctx,
    this->Const.MaxAtomicCounterBufferSize =
       ctx->Const.MaxAtomicBufferSize;
 
+   /* ARB_enhanced_layouts constants */
+   this->Const.MaxTransformFeedbackBuffers = ctx->Const.MaxTransformFeedbackBuffers;
+   this->Const.MaxTransformFeedbackInterleavedComponents = ctx->Const.MaxTransformFeedbackInterleavedComponents;
+
    /* Compute shader constants */
    for (unsigned i = 0; i < ARRAY_SIZE(this->Const.MaxComputeWorkGroupCount); i++)
       this->Const.MaxComputeWorkGroupCount[i] = ctx->Const.MaxComputeWorkGroupCount[i];

src/compiler/glsl/glsl_parser_extras.h

@@ -383,6 +383,10 @@ struct _mesa_glsl_parse_state {
       /* ARB_draw_buffers */
       unsigned MaxDrawBuffers;
 
+      /* ARB_enhanced_layouts */
+      unsigned MaxTransformFeedbackBuffers;
+      unsigned MaxTransformFeedbackInterleavedComponents;
+
       /* ARB_blend_func_extended */
       unsigned MaxDualSourceDrawBuffers;