diff options
| -rw-r--r-- | src/compiler/glsl/ir.h | 7 | ||||
| -rw-r--r-- | src/compiler/glsl/ir_optimization.h | 2 | ||||
| -rw-r--r-- | src/compiler/glsl/link_varyings.cpp | 196 | ||||
| -rw-r--r-- | src/compiler/glsl/lower_packed_varyings.cpp | 28 |
4 files changed, 180 insertions, 53 deletions
diff --git a/src/compiler/glsl/ir.h b/src/compiler/glsl/ir.h index f451967..b74d68a 100644 --- a/src/compiler/glsl/ir.h +++ b/src/compiler/glsl/ir.h @@ -720,6 +720,13 @@ public: unsigned is_unmatched_generic_inout:1; /** + * Is this varying used only by transform feedback? + * + * This is used by the linker to decide if its safe to pack the varying. + */ + unsigned is_xfb_only:1; + + /** * If non-zero, then this variable may be packed along with other variables * into a single varying slot, so this offset should be applied when * accessing components. For example, an offset of 1 means that the x diff --git a/src/compiler/glsl/ir_optimization.h b/src/compiler/glsl/ir_optimization.h index 30c95f4..2d77376 100644 --- a/src/compiler/glsl/ir_optimization.h +++ b/src/compiler/glsl/ir_optimization.h @@ -125,7 +125,7 @@ void lower_ubo_reference(struct gl_shader *shader); void lower_packed_varyings(void *mem_ctx, unsigned locations_used, ir_variable_mode mode, unsigned gs_input_vertices, gl_shader *shader, - bool disable_varying_packing); + bool disable_varying_packing, bool xfb_enabled); bool lower_vector_insert(exec_list *instructions, bool lower_nonconstant_index); bool lower_vector_derefs(gl_shader *shader); void lower_named_interface_blocks(void *mem_ctx, gl_shader *shader); diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp index 806191b..44fc8f6 100644 --- a/src/compiler/glsl/link_varyings.cpp +++ b/src/compiler/glsl/link_varyings.cpp @@ -826,7 +826,7 @@ namespace { class varying_matches { public: - varying_matches(bool disable_varying_packing, + varying_matches(bool disable_varying_packing, bool xfb_enabled, gl_shader_stage producer_stage, gl_shader_stage consumer_stage); ~varying_matches(); @@ -836,14 +836,30 @@ public: void store_locations() const; private: + bool is_varying_packing_safe(const glsl_type *type, + const ir_variable *var); + /** * If true, this driver disables varying packing, so all varyings need to * be aligned on slot boundaries, and take up a number of slots equal to * their number of matrix columns times their array size. + * + * Packing may also be disabled because our current packing method is not + * safe in SSO or versions of OpenGL where interpolation qualifiers are not + * guaranteed to match across stages. */ const bool disable_varying_packing; /** + * If true, this driver has transform feedback enabled. The transform + * feedback code requires at least some packing be done even when varying + * packing is disabled, fortunately where transform feedback requires + * packing it's safe to override the disabled setting. See + * is_varying_packing_safe(). + */ + const bool xfb_enabled; + + /** * Enum representing the order in which varyings are packed within a * packing class. * @@ -862,6 +878,7 @@ private: static unsigned compute_packing_class(const ir_variable *var); static packing_order_enum compute_packing_order(const ir_variable *var); static int match_comparator(const void *x_generic, const void *y_generic); + static int xfb_comparator(const void *x_generic, const void *y_generic); /** * Structure recording the relationship between a single producer output @@ -917,9 +934,11 @@ private: } /* anonymous namespace */ varying_matches::varying_matches(bool disable_varying_packing, + bool xfb_enabled, gl_shader_stage producer_stage, gl_shader_stage consumer_stage) : disable_varying_packing(disable_varying_packing), + xfb_enabled(xfb_enabled), producer_stage(producer_stage), consumer_stage(consumer_stage) { @@ -942,6 +961,24 @@ varying_matches::~varying_matches() /** + * Packing is always safe on individual arrays, structure and matices. It is + * also safe if the varying is only used for transform feedback. + */ +bool +varying_matches::is_varying_packing_safe(const glsl_type *type, + const ir_variable *var) +{ + if (consumer_stage == MESA_SHADER_TESS_EVAL || + consumer_stage == MESA_SHADER_TESS_CTRL || + producer_stage == MESA_SHADER_TESS_CTRL) + return false; + + return xfb_enabled && (type->is_array() || type->is_record() || + type->is_matrix() || var->data.is_xfb_only); +} + + +/** * Record the given producer/consumer variable pair in the list of variables * that should later be assigned locations. * @@ -1020,7 +1057,7 @@ varying_matches::record(ir_variable *producer_var, ir_variable *consumer_var) = this->compute_packing_class(var); this->matches[this->num_matches].packing_order = this->compute_packing_order(var); - if (this->disable_varying_packing) { + if (this->disable_varying_packing && !is_varying_packing_safe(type, var)) { unsigned slots = type->count_attribute_slots(false); this->matches[this->num_matches].num_components = slots * 4; } else { @@ -1046,37 +1083,28 @@ varying_matches::assign_locations(struct gl_shader_program *prog, uint64_t reserved_slots, bool separate_shader) { - /* We disable varying sorting for separate shader programs for the - * following reasons: - * - * 1/ All programs must sort the code in the same order to guarantee the - * interface matching. However varying_matches::record() will change the - * interpolation qualifier of some stages. - * - * 2/ GLSL version 4.50 removes the matching constrain on the interpolation - * qualifier. - * - * From Section 4.5 (Interpolation Qualifiers) of the GLSL 4.40 spec: - * - * "The type and presence of interpolation qualifiers of variables with - * the same name declared in all linked shaders for the same cross-stage - * interface must match, otherwise the link command will fail. - * - * When comparing an output from one stage to an input of a subsequent - * stage, the input and output don't match if their interpolation - * qualifiers (or lack thereof) are not the same." - * - * "It is a link-time error if, within the same stage, the interpolation - * qualifiers of variables of the same name do not match." + /* If packing has been disabled then we cannot safely sort the varyings by + * class as it may mean we are using a version of OpenGL where + * interpolation qualifiers are not guaranteed to be matching across + * shaders, sorting in this case could result in mismatching shader + * interfaces. + * When packing is disabled the sort orders varyings used by transform + * feedback first, but also depends on *undefined behaviour* of qsort to + * reverse the order of the varyings. See: xfb_comparator(). */ - if (!separate_shader) { + if (!this->disable_varying_packing) { /* Sort varying matches into an order that makes them easy to pack. */ qsort(this->matches, this->num_matches, sizeof(*this->matches), &varying_matches::match_comparator); + } else { + /* Only sort varyings that are only used by transform feedback. */ + qsort(this->matches, this->num_matches, sizeof(*this->matches), + &varying_matches::xfb_comparator); } unsigned generic_location = 0; unsigned generic_patch_location = MAX_VARYING*4; + bool previous_var_xfb_only = false; for (unsigned i = 0; i < this->num_matches; i++) { unsigned *location = &generic_location; @@ -1100,16 +1128,30 @@ varying_matches::assign_locations(struct gl_shader_program *prog, /* Advance to the next slot if this varying has a different packing * class than the previous one, and we're not already on a slot * boundary. + * + * Also advance to the next slot if packing is disabled. This makes sure + * we don't assign varyings the same locations which is possible + * because we still pack individual arrays, records and matrices even + * when packing is disabled. Note we don't advance to the next slot if + * we can pack varyings together that are only used for transform + * feedback. */ - if (i > 0 && - this->matches[i - 1].packing_class - != this->matches[i].packing_class) { + if ((this->disable_varying_packing && + !(previous_var_xfb_only && var->data.is_xfb_only)) || + (i > 0 && this->matches[i - 1].packing_class + != this->matches[i].packing_class )) { *location = ALIGN(*location, 4); } + previous_var_xfb_only = var->data.is_xfb_only; + unsigned num_elements = type->count_attribute_slots(is_vertex_input); - unsigned slot_end = this->disable_varying_packing ? 4 : - type->without_array()->vector_elements; + unsigned slot_end; + if (this->disable_varying_packing && + !is_varying_packing_safe(type, var)) + slot_end = 4; + else + slot_end = type->without_array()->vector_elements; slot_end += *location - 1; /* FIXME: We could be smarter in the below code and loop back over @@ -1133,7 +1175,8 @@ varying_matches::assign_locations(struct gl_shader_program *prog, /* Increase the slot to make sure there is enough room for next * array element. */ - if (this->disable_varying_packing) + if (this->disable_varying_packing && + !is_varying_packing_safe(type, var)) slot_end += 4; else slot_end += type->without_array()->vector_elements; @@ -1259,6 +1302,32 @@ varying_matches::match_comparator(const void *x_generic, const void *y_generic) /** + * Comparison function passed to qsort() to sort varyings used only by + * transform feedback when packing of other varyings is disabled. + */ +int +varying_matches::xfb_comparator(const void *x_generic, const void *y_generic) +{ + const match *x = (const match *) x_generic; + + if (x->producer_var != NULL && x->producer_var->data.is_xfb_only) + return match_comparator(x_generic, y_generic); + + /* FIXME: When the comparator returns 0 it means the elements being + * compared are equivalent. However the qsort documentation says: + * + * "The order of equivalent elements is undefined." + * + * In practice the sort ends up reversing the order of the varyings which + * means locations are also assigned in this reversed order and happens to + * be what we want. This is also whats happening in + * varying_matches::match_comparator(). + */ + return 0; +} + + +/** * Is the given variable a varying variable to be counted against the * limit in ctx->Const.MaxVarying? * This includes variables such as texcoords, colors and generic @@ -1573,26 +1642,60 @@ assign_varying_locations(struct gl_context *ctx, unsigned num_tfeedback_decls, tfeedback_decl *tfeedback_decls) { - if (ctx->Const.DisableVaryingPacking) { - /* Transform feedback code assumes varyings are packed, so if the driver - * has disabled varying packing, make sure it does not support transform - * feedback. - */ - assert(!ctx->Extensions.EXT_transform_feedback); - } - /* Tessellation shaders treat inputs and outputs as shared memory and can * access inputs and outputs of other invocations. * Therefore, they can't be lowered to temps easily (and definitely not * efficiently). */ - bool disable_varying_packing = - ctx->Const.DisableVaryingPacking || + bool unpackable_tess = (consumer && consumer->Stage == MESA_SHADER_TESS_EVAL) || (consumer && consumer->Stage == MESA_SHADER_TESS_CTRL) || (producer && producer->Stage == MESA_SHADER_TESS_CTRL); - varying_matches matches(disable_varying_packing, + /* Transform feedback code assumes varying arrays are packed, so if the + * driver has disabled varying packing, make sure to at least enable + * packing required by transform feedback. + */ + bool xfb_enabled = + ctx->Extensions.EXT_transform_feedback && !unpackable_tess; + + /* Disable varying packing for GL 4.4+ as there is no guarantee + * that interpolation qualifiers will match between shaders in these + * versions. We also disable packing on outerward facing interfaces for + * SSO because in ES we need to retain the unpacked varying information + * for draw time validation. For desktop GL we could allow packing for + * versions < 4.4 but its just safer not to do packing. + * + * Packing is still enabled on individual arrays, structs, and matrices as + * these are required by the transform feedback code and it is still safe + * to do so. We also enable packing when a varying is only used for + * transform feedback and its not a SSO. + * + * Varying packing currently only packs together varyings with matching + * interpolation qualifiers as the backends assume all packed components + * are to be processed in the same way. Therefore we cannot do packing in + * these versions of GL without the risk of mismatching interfaces. + * + * From Section 4.5 (Interpolation Qualifiers) of the GLSL 4.30 spec: + * + * "The type and presence of interpolation qualifiers of variables with + * the same name declared in all linked shaders for the same cross-stage + * interface must match, otherwise the link command will fail. + * + * When comparing an output from one stage to an input of a subsequent + * stage, the input and output don't match if their interpolation + * qualifiers (or lack thereof) are not the same." + * + * This text was also in at least revison 7 of the 4.40 spec but is no + * longer in revision 9 and not in the 4.50 spec. + */ + bool disable_varying_packing = + ctx->Const.DisableVaryingPacking || unpackable_tess; + if ((ctx->API == API_OPENGL_CORE && ctx->Version >= 44) || + (prog->SeparateShader && (producer == NULL || consumer == NULL))) + disable_varying_packing = true; + + varying_matches matches(disable_varying_packing, xfb_enabled, producer ? producer->Stage : (gl_shader_stage)-1, consumer ? consumer->Stage : (gl_shader_stage)-1); hash_table *tfeedback_candidates @@ -1711,8 +1814,10 @@ assign_varying_locations(struct gl_context *ctx, return false; } - if (matched_candidate->toplevel_var->data.is_unmatched_generic_inout) + if (matched_candidate->toplevel_var->data.is_unmatched_generic_inout) { + matched_candidate->toplevel_var->data.is_xfb_only = 1; matches.record(matched_candidate->toplevel_var, NULL); + } } const uint64_t reserved_slots = @@ -1786,13 +1891,14 @@ assign_varying_locations(struct gl_context *ctx, if (producer) { lower_packed_varyings(mem_ctx, slots_used, ir_var_shader_out, - 0, producer, disable_varying_packing); + 0, producer, disable_varying_packing, + xfb_enabled); } if (consumer) { lower_packed_varyings(mem_ctx, slots_used, ir_var_shader_in, consumer_vertices, consumer, - disable_varying_packing); + disable_varying_packing, xfb_enabled); } return true; diff --git a/src/compiler/glsl/lower_packed_varyings.cpp b/src/compiler/glsl/lower_packed_varyings.cpp index d91aa22..825cc9e 100644 --- a/src/compiler/glsl/lower_packed_varyings.cpp +++ b/src/compiler/glsl/lower_packed_varyings.cpp @@ -169,7 +169,8 @@ public: unsigned gs_input_vertices, exec_list *out_instructions, exec_list *out_variables, - bool disable_varying_packing); + bool disable_varying_packing, + bool xfb_enabled); void run(struct gl_shader *shader); @@ -234,6 +235,7 @@ private: exec_list *out_variables; bool disable_varying_packing; + bool xfb_enabled; }; } /* anonymous namespace */ @@ -241,7 +243,8 @@ private: lower_packed_varyings_visitor::lower_packed_varyings_visitor( void *mem_ctx, unsigned locations_used, ir_variable_mode mode, unsigned gs_input_vertices, exec_list *out_instructions, - exec_list *out_variables, bool disable_varying_packing) + exec_list *out_variables, bool disable_varying_packing, + bool xfb_enabled) : mem_ctx(mem_ctx), locations_used(locations_used), packed_varyings((ir_variable **) @@ -251,7 +254,8 @@ lower_packed_varyings_visitor::lower_packed_varyings_visitor( gs_input_vertices(gs_input_vertices), out_instructions(out_instructions), out_variables(out_variables), - disable_varying_packing(disable_varying_packing) + disable_varying_packing(disable_varying_packing), + xfb_enabled(xfb_enabled) { } @@ -660,10 +664,18 @@ lower_packed_varyings_visitor::needs_lowering(ir_variable *var) if (var->data.explicit_location) return false; - if (disable_varying_packing) + /* Override disable_varying_packing if the var is only used by transform + * feedback. Also override it if transform feedback is enabled and the + * variable is an array, struct or matrix as the elements of these types + * will always has the same interpolation and therefore asre safe to pack. + */ + const glsl_type *type = var->type; + if (disable_varying_packing && !var->data.is_xfb_only && + !((type->is_array() || type->is_record() || type->is_matrix()) && + xfb_enabled)) return false; - const glsl_type *type = var->type->without_array(); + type = type->without_array(); if (type->vector_elements == 4 && !type->is_double()) return false; return true; @@ -716,7 +728,8 @@ lower_packed_varyings_gs_splicer::visit_leave(ir_emit_vertex *ev) void lower_packed_varyings(void *mem_ctx, unsigned locations_used, ir_variable_mode mode, unsigned gs_input_vertices, - gl_shader *shader, bool disable_varying_packing) + gl_shader *shader, bool disable_varying_packing, + bool xfb_enabled) { exec_list *instructions = shader->ir; ir_function *main_func = shader->symbols->get_function("main"); @@ -728,7 +741,8 @@ lower_packed_varyings(void *mem_ctx, unsigned locations_used, gs_input_vertices, &new_instructions, &new_variables, - disable_varying_packing); + disable_varying_packing, + xfb_enabled); visitor.run(shader); if (mode == ir_var_shader_out) { if (shader->Stage == MESA_SHADER_GEOMETRY) { |