From 6e5b882339e9128348f0e7b828230f07338fce55 Mon Sep 17 00:00:00 2001 From: Brian Paul Date: Mon, 18 Dec 2017 12:32:56 -0700 Subject: [PATCH] glsl: disable vec3 packing/splitting in tfb separate mode This fixes a varying packing issue when using transform feedback in GL_SEPARATE_ATTRIBS mode. By time we get to linking, we already know that the number of feedback attributes is under the GL_MAX_TRANSFORM_FEEDBACK_SEPARATE_ATTRIBS limit so packing isn't as critical. In fact, packing/splitting vec3 attributes can cause trouble because splitting effectively creates another TFB output which can exceed device limits. So, disable vec3 packing when it's not needed to avoid that issue. Fixes the Piglit ext_transform_feedback-separate test on VMware driver. Reviewed-by: Timothy Arceri --- src/compiler/glsl/link_varyings.cpp | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp index e0f3afb9616..0a484ce1329 100644 --- a/src/compiler/glsl/link_varyings.cpp +++ b/src/compiler/glsl/link_varyings.cpp @@ -1777,6 +1777,16 @@ varying_matches::assign_locations(struct gl_shader_program *prog, bool previous_var_xfb_only = false; unsigned previous_packing_class = ~0u; + /* For tranform feedback separate mode, we know the number of attributes + * is <= the number of buffers. So packing isn't critical. In fact, + * packing vec3 attributes can cause trouble because splitting a vec3 + * effectively creates an additional transform feedback output. The + * extra TFB output may exceed device driver limits. + */ + const bool dont_pack_vec3 = + (prog->TransformFeedback.BufferMode == GL_SEPARATE_ATTRIBS && + prog->TransformFeedback.NumVarying > 0); + for (unsigned i = 0; i < this->num_matches; i++) { unsigned *location = &generic_location; const ir_variable *var; @@ -1810,7 +1820,9 @@ varying_matches::assign_locations(struct gl_shader_program *prog, if (var->data.must_be_shader_input || (this->disable_varying_packing && !(previous_var_xfb_only && var->data.is_xfb_only)) || - (previous_packing_class != this->matches[i].packing_class )) { + (previous_packing_class != this->matches[i].packing_class) || + (this->matches[i].packing_order == PACKING_ORDER_VEC3 && + dont_pack_vec3)) { *location = ALIGN(*location, 4); } -- 2.30.2