diff options
Diffstat (limited to 'mesalib/src/glsl/opt_dead_builtin_varyings.cpp')
| -rw-r--r-- | mesalib/src/glsl/opt_dead_builtin_varyings.cpp | 477 |
1 files changed, 477 insertions, 0 deletions
diff --git a/mesalib/src/glsl/opt_dead_builtin_varyings.cpp b/mesalib/src/glsl/opt_dead_builtin_varyings.cpp new file mode 100644 index 000000000..2e813d24e --- /dev/null +++ b/mesalib/src/glsl/opt_dead_builtin_varyings.cpp @@ -0,0 +1,477 @@ +/* + * Copyright © 2013 Marek Olšák <maraeo@gmail.com> + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice (including the next + * paragraph) shall be included in all copies or substantial portions of the + * Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER + * DEALINGS IN THE SOFTWARE. + */ + +/** + * \file opt_dead_builtin_varyings.cpp + * + * This eliminates the built-in shader outputs which are either not written + * at all or not used by the next stage. It also eliminates unused elements + * of gl_TexCoord inputs, which reduces the overall varying usage. + * The varyings handled here are the primary and secondary color, the fog, + * and the texture coordinates (gl_TexCoord). + * + * This pass is necessary, because the Mesa GLSL linker cannot eliminate + * built-in varyings like it eliminates user-defined varyings, because + * the built-in varyings have pre-assigned locations. Also, the elimination + * of unused gl_TexCoord elements requires its own lowering pass anyway. + * + * It's implemented by replacing all occurences of dead varyings with + * temporary variables, which creates dead code. It is recommended to run + * a dead-code elimination pass after this. + * + * If any texture coordinate slots can be eliminated, the gl_TexCoord array is + * broken down into separate vec4 variables with locations equal to + * VARYING_SLOT_TEX0 + i. + */ + +#include "main/imports.h" /* for snprintf */ +#include "ir.h" +#include "ir_rvalue_visitor.h" +#include "ir_optimization.h" +#include "ir_print_visitor.h" +#include "glsl_types.h" +#include "link_varyings.h" + + +/** + * This obtains detailed information about built-in varyings from shader code. + */ +class varying_info_visitor : public ir_hierarchical_visitor { +public: + /* "mode" can be either ir_var_shader_in or ir_var_shader_out */ + varying_info_visitor(ir_variable_mode mode) + : lower_texcoord_array(true), + texcoord_array(NULL), + texcoord_usage(0), + color_usage(0), + tfeedback_color_usage(0), + fog(NULL), + has_fog(false), + tfeedback_has_fog(false), + mode(mode) + { + memset(color, 0, sizeof(color)); + memset(backcolor, 0, sizeof(backcolor)); + } + + virtual ir_visitor_status visit_enter(ir_dereference_array *ir) + { + ir_variable *var = ir->variable_referenced(); + + if (var && var->mode == this->mode && + var->location == VARYING_SLOT_TEX0) { + this->texcoord_array = var; + + ir_constant *index = ir->array_index->as_constant(); + if (index == NULL) { + /* There is variable indexing, we can't lower the texcoord array. + */ + this->texcoord_usage |= (1 << var->type->array_size()) - 1; + this->lower_texcoord_array = false; + } + else { + this->texcoord_usage |= 1 << index->get_uint_component(0); + } + + /* Don't visit the leaves of ir_dereference_array. */ + return visit_continue_with_parent; + } + + return visit_continue; + } + + virtual ir_visitor_status visit(ir_dereference_variable *ir) + { + ir_variable *var = ir->variable_referenced(); + + if (var->mode == this->mode && var->type->is_array() && + var->location == VARYING_SLOT_TEX0) { + /* This is a whole array dereference like "gl_TexCoord = x;", + * there's probably no point in lowering that. + */ + this->texcoord_usage |= (1 << var->type->array_size()) - 1; + this->lower_texcoord_array = false; + } + return visit_continue; + } + + virtual ir_visitor_status visit(ir_variable *var) + { + if (var->mode != this->mode) + return visit_continue; + + /* Handle colors and fog. */ + switch (var->location) { + case VARYING_SLOT_COL0: + this->color[0] = var; + this->color_usage |= 1; + break; + case VARYING_SLOT_COL1: + this->color[1] = var; + this->color_usage |= 2; + break; + case VARYING_SLOT_BFC0: + this->backcolor[0] = var; + this->color_usage |= 1; + break; + case VARYING_SLOT_BFC1: + this->backcolor[1] = var; + this->color_usage |= 2; + break; + case VARYING_SLOT_FOGC: + this->fog = var; + this->has_fog = true; + break; + } + + return visit_continue; + } + + void get(exec_list *ir, + unsigned num_tfeedback_decls, + tfeedback_decl *tfeedback_decls) + { + /* Handle the transform feedback varyings. */ + for (unsigned i = 0; i < num_tfeedback_decls; i++) { + if (!tfeedback_decls[i].is_varying()) + continue; + + unsigned location = tfeedback_decls[i].get_location(); + + switch (location) { + case VARYING_SLOT_COL0: + case VARYING_SLOT_BFC0: + this->tfeedback_color_usage |= 1; + break; + case VARYING_SLOT_COL1: + case VARYING_SLOT_BFC1: + this->tfeedback_color_usage |= 2; + break; + case VARYING_SLOT_FOGC: + this->tfeedback_has_fog = true; + break; + default: + if (location >= VARYING_SLOT_TEX0 && + location <= VARYING_SLOT_TEX7) { + this->lower_texcoord_array = false; + } + } + } + + /* Process the shader. */ + visit_list_elements(this, ir); + + if (!this->texcoord_array) { + this->lower_texcoord_array = false; + } + } + + bool lower_texcoord_array; + ir_variable *texcoord_array; + unsigned texcoord_usage; /* bitmask */ + + ir_variable *color[2]; + ir_variable *backcolor[2]; + unsigned color_usage; /* bitmask */ + unsigned tfeedback_color_usage; /* bitmask */ + + ir_variable *fog; + bool has_fog; + bool tfeedback_has_fog; + + ir_variable_mode mode; +}; + + +/** + * This replaces unused varyings with temporary variables. + * + * If "ir" is the producer, the "external" usage should come from + * the consumer. It also works the other way around. If either one is + * missing, set the "external" usage to a full mask. + */ +class replace_varyings_visitor : public ir_rvalue_visitor { +public: + replace_varyings_visitor(exec_list *ir, + const varying_info_visitor *info, + unsigned external_texcoord_usage, + unsigned external_color_usage, + bool external_has_fog) + : info(info), new_fog(NULL) + { + void *const ctx = ir; + + memset(this->new_texcoord, 0, sizeof(this->new_texcoord)); + memset(this->new_color, 0, sizeof(this->new_color)); + memset(this->new_backcolor, 0, sizeof(this->new_backcolor)); + + const char *mode_str = + info->mode == ir_var_shader_in ? "in" : "out"; + + /* Handle texcoord outputs. + * + * We're going to break down the gl_TexCoord array into separate + * variables. First, add declarations of the new variables all + * occurences of gl_TexCoord will be replaced with. + */ + if (info->lower_texcoord_array) { + for (int i = MAX_TEXTURE_COORD_UNITS-1; i >= 0; i--) { + if (info->texcoord_usage & (1 << i)) { + char name[32]; + + if (!(external_texcoord_usage & (1 << i))) { + /* This varying is unused in the next stage. Declare + * a temporary instead of an output. */ + snprintf(name, 32, "gl_%s_TexCoord%i_dummy", mode_str, i); + this->new_texcoord[i] = + new (ctx) ir_variable(glsl_type::vec4_type, name, + ir_var_temporary); + } + else { + snprintf(name, 32, "gl_%s_TexCoord%i", mode_str, i); + this->new_texcoord[i] = + new(ctx) ir_variable(glsl_type::vec4_type, name, + info->mode); + this->new_texcoord[i]->location = VARYING_SLOT_TEX0 + i; + this->new_texcoord[i]->explicit_location = true; + this->new_texcoord[i]->explicit_index = 0; + } + + ir->head->insert_before(new_texcoord[i]); + } + } + } + + /* Create dummy variables which will replace set-but-unused color and + * fog outputs. + */ + external_color_usage |= info->tfeedback_color_usage; + + for (int i = 0; i < 2; i++) { + char name[32]; + + if (!(external_color_usage & (1 << i))) { + if (info->color[i]) { + snprintf(name, 32, "gl_%s_FrontColor%i_dummy", mode_str, i); + this->new_color[i] = + new (ctx) ir_variable(glsl_type::vec4_type, name, + ir_var_temporary); + } + + if (info->backcolor[i]) { + snprintf(name, 32, "gl_%s_BackColor%i_dummy", mode_str, i); + this->new_backcolor[i] = + new (ctx) ir_variable(glsl_type::vec4_type, name, + ir_var_temporary); + } + } + } + + if (!external_has_fog && !info->tfeedback_has_fog && + info->fog) { + char name[32]; + + snprintf(name, 32, "gl_%s_FogFragCoord_dummy", mode_str); + this->new_fog = new (ctx) ir_variable(glsl_type::float_type, name, + ir_var_temporary); + } + + /* Now do the replacing. */ + visit_list_elements(this, ir); + } + + virtual ir_visitor_status visit(ir_variable *var) + { + /* Remove the gl_TexCoord array. */ + if (this->info->lower_texcoord_array && + var == this->info->texcoord_array) { + var->remove(); + } + + /* Replace set-but-unused color and fog outputs with dummy variables. */ + for (int i = 0; i < 2; i++) { + if (var == this->info->color[i] && this->new_color[i]) { + var->replace_with(this->new_color[i]); + } + if (var == this->info->backcolor[i] && + this->new_backcolor[i]) { + var->replace_with(this->new_backcolor[i]); + } + } + + if (var == this->info->fog && this->new_fog) { + var->replace_with(this->new_fog); + } + + return visit_continue; + } + + virtual void handle_rvalue(ir_rvalue **rvalue) + { + if (!*rvalue) + return; + + void *ctx = ralloc_parent(*rvalue); + + /* Replace an array dereference gl_TexCoord[i] with a single + * variable dereference representing gl_TexCoord[i]. + */ + if (this->info->lower_texcoord_array) { + /* gl_TexCoord[i] occurence */ + ir_dereference_array *const da = (*rvalue)->as_dereference_array(); + + if (da && da->variable_referenced() == + this->info->texcoord_array) { + unsigned i = da->array_index->as_constant()->get_uint_component(0); + + *rvalue = new(ctx) ir_dereference_variable(this->new_texcoord[i]); + return; + } + } + + /* Replace set-but-unused color and fog outputs with dummy variables. */ + ir_dereference_variable *const dv = (*rvalue)->as_dereference_variable(); + if (!dv) + return; + + ir_variable *var = dv->variable_referenced(); + + for (int i = 0; i < 2; i++) { + if (var == this->info->color[i] && this->new_color[i]) { + *rvalue = new(ctx) ir_dereference_variable(this->new_color[i]); + return; + } + if (var == this->info->backcolor[i] && + this->new_backcolor[i]) { + *rvalue = new(ctx) ir_dereference_variable(this->new_backcolor[i]); + return; + } + } + + if (var == this->info->fog && this->new_fog) { + *rvalue = new(ctx) ir_dereference_variable(this->new_fog); + } + } + + virtual ir_visitor_status visit_leave(ir_assignment *ir) + { + handle_rvalue(&ir->rhs); + handle_rvalue(&ir->condition); + + /* We have to use set_lhs when changing the LHS of an assignment. */ + ir_rvalue *lhs = ir->lhs; + + handle_rvalue(&lhs); + if (lhs != ir->lhs) { + ir->set_lhs(lhs); + } + + return visit_continue; + } + +private: + const varying_info_visitor *info; + struct ir_variable *new_texcoord[MAX_TEXTURE_COORD_UNITS]; + struct ir_variable *new_color[2]; + struct ir_variable *new_backcolor[2]; + struct ir_variable *new_fog; +}; + + +static void +lower_texcoord_array(exec_list *ir, const varying_info_visitor *info) +{ + replace_varyings_visitor(ir, info, + (1 << MAX_TEXTURE_COORD_UNITS) - 1, + 1 | 2, true); +} + + +void +do_dead_builtin_varyings(struct gl_context *ctx, + exec_list *producer, exec_list *consumer, + unsigned num_tfeedback_decls, + tfeedback_decl *tfeedback_decls) +{ + /* This optimization has no effect with the core context and GLES2, because + * the built-in varyings we're eliminating here are not available there. + * + * EXT_separate_shader_objects doesn't allow this optimization, + * because a program object can be bound partially (e.g. only one + * stage of a program object can be bound). + */ + if (ctx->API == API_OPENGL_CORE || + ctx->API == API_OPENGLES2 || + ctx->Extensions.EXT_separate_shader_objects) { + return; + } + + /* Information about built-in varyings. */ + varying_info_visitor producer_info(ir_var_shader_out); + varying_info_visitor consumer_info(ir_var_shader_in); + + if (producer) { + producer_info.get(producer, num_tfeedback_decls, tfeedback_decls); + + if (!consumer) { + /* At least eliminate unused gl_TexCoord elements. */ + if (producer_info.lower_texcoord_array) { + lower_texcoord_array(producer, &producer_info); + } + return; + } + } + + if (consumer) { + consumer_info.get(consumer, 0, NULL); + + if (!producer) { + /* At least eliminate unused gl_TexCoord elements. */ + if (consumer_info.lower_texcoord_array) { + lower_texcoord_array(consumer, &consumer_info); + } + return; + } + } + + /* Eliminate the varyings unused by the other shader. */ + if (producer_info.lower_texcoord_array || + producer_info.color_usage || + producer_info.has_fog) { + replace_varyings_visitor(producer, + &producer_info, + consumer_info.texcoord_usage, + consumer_info.color_usage, + consumer_info.has_fog); + } + + if (consumer_info.lower_texcoord_array || + consumer_info.color_usage || + consumer_info.has_fog) { + replace_varyings_visitor(consumer, + &consumer_info, + producer_info.texcoord_usage, + producer_info.color_usage, + producer_info.has_fog); + } +} |