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Diffstat (limited to 'src/compiler/glsl/lower_clip_distance.cpp')
| -rw-r--r-- | src/compiler/glsl/lower_clip_distance.cpp | 574 |
1 files changed, 574 insertions, 0 deletions
diff --git a/src/compiler/glsl/lower_clip_distance.cpp b/src/compiler/glsl/lower_clip_distance.cpp new file mode 100644 index 00000000000..1ada215796c --- /dev/null +++ b/src/compiler/glsl/lower_clip_distance.cpp @@ -0,0 +1,574 @@ +/* + * Copyright © 2011 Intel Corporation + * + * 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 lower_clip_distance.cpp + * + * This pass accounts for the difference between the way + * gl_ClipDistance is declared in standard GLSL (as an array of + * floats), and the way it is frequently implemented in hardware (as + * a pair of vec4s, with four clip distances packed into each). + * + * The declaration of gl_ClipDistance is replaced with a declaration + * of gl_ClipDistanceMESA, and any references to gl_ClipDistance are + * translated to refer to gl_ClipDistanceMESA with the appropriate + * swizzling of array indices. For instance: + * + * gl_ClipDistance[i] + * + * is translated into: + * + * gl_ClipDistanceMESA[i>>2][i&3] + * + * Since some hardware may not internally represent gl_ClipDistance as a pair + * of vec4's, this lowering pass is optional. To enable it, set the + * LowerClipDistance flag in gl_shader_compiler_options to true. + */ + +#include "glsl_symbol_table.h" +#include "ir_rvalue_visitor.h" +#include "ir.h" +#include "program/prog_instruction.h" /* For WRITEMASK_* */ + +namespace { + +class lower_clip_distance_visitor : public ir_rvalue_visitor { +public: + explicit lower_clip_distance_visitor(gl_shader_stage shader_stage) + : progress(false), old_clip_distance_out_var(NULL), + old_clip_distance_in_var(NULL), new_clip_distance_out_var(NULL), + new_clip_distance_in_var(NULL), shader_stage(shader_stage) + { + } + + virtual ir_visitor_status visit(ir_variable *); + void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&); + bool is_clip_distance_vec8(ir_rvalue *ir); + ir_rvalue *lower_clip_distance_vec8(ir_rvalue *ir); + virtual ir_visitor_status visit_leave(ir_assignment *); + void visit_new_assignment(ir_assignment *ir); + virtual ir_visitor_status visit_leave(ir_call *); + + virtual void handle_rvalue(ir_rvalue **rvalue); + + void fix_lhs(ir_assignment *); + + bool progress; + + /** + * Pointer to the declaration of gl_ClipDistance, if found. + * + * Note: + * + * - the in_var is for geometry and both tessellation shader inputs only. + * + * - since gl_ClipDistance is available in tessellation control, + * tessellation evaluation and geometry shaders as both an input + * and an output, it's possible for both old_clip_distance_out_var + * and old_clip_distance_in_var to be non-null. + */ + ir_variable *old_clip_distance_out_var; + ir_variable *old_clip_distance_in_var; + + /** + * Pointer to the newly-created gl_ClipDistanceMESA variable. + */ + ir_variable *new_clip_distance_out_var; + ir_variable *new_clip_distance_in_var; + + /** + * Type of shader we are compiling (e.g. MESA_SHADER_VERTEX) + */ + const gl_shader_stage shader_stage; +}; + +} /* anonymous namespace */ + +/** + * Replace any declaration of gl_ClipDistance as an array of floats with a + * declaration of gl_ClipDistanceMESA as an array of vec4's. + */ +ir_visitor_status +lower_clip_distance_visitor::visit(ir_variable *ir) +{ + ir_variable **old_var; + ir_variable **new_var; + + if (!ir->name || strcmp(ir->name, "gl_ClipDistance") != 0) + return visit_continue; + assert (ir->type->is_array()); + + if (ir->data.mode == ir_var_shader_out) { + if (this->old_clip_distance_out_var) + return visit_continue; + old_var = &old_clip_distance_out_var; + new_var = &new_clip_distance_out_var; + } else if (ir->data.mode == ir_var_shader_in) { + if (this->old_clip_distance_in_var) + return visit_continue; + old_var = &old_clip_distance_in_var; + new_var = &new_clip_distance_in_var; + } else { + unreachable("not reached"); + } + + this->progress = true; + + if (!ir->type->fields.array->is_array()) { + /* gl_ClipDistance (used for vertex, tessellation evaluation and + * geometry output, and fragment input). + */ + assert((ir->data.mode == ir_var_shader_in && + this->shader_stage == MESA_SHADER_FRAGMENT) || + (ir->data.mode == ir_var_shader_out && + (this->shader_stage == MESA_SHADER_VERTEX || + this->shader_stage == MESA_SHADER_TESS_EVAL || + this->shader_stage == MESA_SHADER_GEOMETRY))); + + *old_var = ir; + assert (ir->type->fields.array == glsl_type::float_type); + unsigned new_size = (ir->type->array_size() + 3) / 4; + + /* Clone the old var so that we inherit all of its properties */ + *new_var = ir->clone(ralloc_parent(ir), NULL); + + /* And change the properties that we need to change */ + (*new_var)->name = ralloc_strdup(*new_var, "gl_ClipDistanceMESA"); + (*new_var)->type = glsl_type::get_array_instance(glsl_type::vec4_type, + new_size); + (*new_var)->data.max_array_access = ir->data.max_array_access / 4; + + ir->replace_with(*new_var); + } else { + /* 2D gl_ClipDistance (used for tessellation control, tessellation + * evaluation and geometry input, and tessellation control output). + */ + assert((ir->data.mode == ir_var_shader_in && + (this->shader_stage == MESA_SHADER_GEOMETRY || + this->shader_stage == MESA_SHADER_TESS_EVAL)) || + this->shader_stage == MESA_SHADER_TESS_CTRL); + + *old_var = ir; + assert (ir->type->fields.array->fields.array == glsl_type::float_type); + unsigned new_size = (ir->type->fields.array->array_size() + 3) / 4; + + /* Clone the old var so that we inherit all of its properties */ + *new_var = ir->clone(ralloc_parent(ir), NULL); + + /* And change the properties that we need to change */ + (*new_var)->name = ralloc_strdup(*new_var, "gl_ClipDistanceMESA"); + (*new_var)->type = glsl_type::get_array_instance( + glsl_type::get_array_instance(glsl_type::vec4_type, + new_size), + ir->type->array_size()); + (*new_var)->data.max_array_access = ir->data.max_array_access / 4; + + ir->replace_with(*new_var); + } + + return visit_continue; +} + + +/** + * Create the necessary GLSL rvalues to index into gl_ClipDistanceMESA based + * on the rvalue previously used to index into gl_ClipDistance. + * + * \param array_index Selects one of the vec4's in gl_ClipDistanceMESA + * \param swizzle_index Selects a component within the vec4 selected by + * array_index. + */ +void +lower_clip_distance_visitor::create_indices(ir_rvalue *old_index, + ir_rvalue *&array_index, + ir_rvalue *&swizzle_index) +{ + void *ctx = ralloc_parent(old_index); + + /* Make sure old_index is a signed int so that the bitwise "shift" and + * "and" operations below type check properly. + */ + if (old_index->type != glsl_type::int_type) { + assert (old_index->type == glsl_type::uint_type); + old_index = new(ctx) ir_expression(ir_unop_u2i, old_index); + } + + ir_constant *old_index_constant = old_index->constant_expression_value(); + if (old_index_constant) { + /* gl_ClipDistance is being accessed via a constant index. Don't bother + * creating expressions to calculate the lowered indices. Just create + * constants. + */ + int const_val = old_index_constant->get_int_component(0); + array_index = new(ctx) ir_constant(const_val / 4); + swizzle_index = new(ctx) ir_constant(const_val % 4); + } else { + /* Create a variable to hold the value of old_index (so that we + * don't compute it twice). + */ + ir_variable *old_index_var = new(ctx) ir_variable( + glsl_type::int_type, "clip_distance_index", ir_var_temporary); + this->base_ir->insert_before(old_index_var); + this->base_ir->insert_before(new(ctx) ir_assignment( + new(ctx) ir_dereference_variable(old_index_var), old_index)); + + /* Create the expression clip_distance_index / 4. Do this as a bit + * shift because that's likely to be more efficient. + */ + array_index = new(ctx) ir_expression( + ir_binop_rshift, new(ctx) ir_dereference_variable(old_index_var), + new(ctx) ir_constant(2)); + + /* Create the expression clip_distance_index % 4. Do this as a bitwise + * AND because that's likely to be more efficient. + */ + swizzle_index = new(ctx) ir_expression( + ir_binop_bit_and, new(ctx) ir_dereference_variable(old_index_var), + new(ctx) ir_constant(3)); + } +} + + +/** + * Determine whether the given rvalue describes an array of 8 floats that + * needs to be lowered to an array of 2 vec4's; that is, determine whether it + * matches one of the following patterns: + * + * - gl_ClipDistance (if gl_ClipDistance is 1D) + * - gl_ClipDistance[i] (if gl_ClipDistance is 2D) + */ +bool +lower_clip_distance_visitor::is_clip_distance_vec8(ir_rvalue *ir) +{ + /* Note that geometry shaders contain gl_ClipDistance both as an input + * (which is a 2D array) and an output (which is a 1D array), so it's + * possible for both this->old_clip_distance_out_var and + * this->old_clip_distance_in_var to be non-NULL in the same shader. + */ + + if (!ir->type->is_array()) + return false; + if (ir->type->fields.array != glsl_type::float_type) + return false; + + if (this->old_clip_distance_out_var) { + if (ir->variable_referenced() == this->old_clip_distance_out_var) + return true; + } + if (this->old_clip_distance_in_var) { + assert(this->shader_stage == MESA_SHADER_TESS_CTRL || + this->shader_stage == MESA_SHADER_TESS_EVAL || + this->shader_stage == MESA_SHADER_GEOMETRY || + this->shader_stage == MESA_SHADER_FRAGMENT); + + if (ir->variable_referenced() == this->old_clip_distance_in_var) + return true; + } + return false; +} + + +/** + * If the given ir satisfies is_clip_distance_vec8(), return new ir + * representing its lowered equivalent. That is, map: + * + * - gl_ClipDistance => gl_ClipDistanceMESA (if gl_ClipDistance is 1D) + * - gl_ClipDistance[i] => gl_ClipDistanceMESA[i] (if gl_ClipDistance is 2D) + * + * Otherwise return NULL. + */ +ir_rvalue * +lower_clip_distance_visitor::lower_clip_distance_vec8(ir_rvalue *ir) +{ + if (!ir->type->is_array()) + return NULL; + if (ir->type->fields.array != glsl_type::float_type) + return NULL; + + ir_variable **new_var = NULL; + if (this->old_clip_distance_out_var) { + if (ir->variable_referenced() == this->old_clip_distance_out_var) + new_var = &this->new_clip_distance_out_var; + } + if (this->old_clip_distance_in_var) { + if (ir->variable_referenced() == this->old_clip_distance_in_var) + new_var = &this->new_clip_distance_in_var; + } + if (new_var == NULL) + return NULL; + + if (ir->as_dereference_variable()) { + return new(ralloc_parent(ir)) ir_dereference_variable(*new_var); + } else { + ir_dereference_array *array_ref = ir->as_dereference_array(); + assert(array_ref); + assert(array_ref->array->as_dereference_variable()); + + return new(ralloc_parent(ir)) + ir_dereference_array(*new_var, array_ref->array_index); + } +} + + +void +lower_clip_distance_visitor::handle_rvalue(ir_rvalue **rv) +{ + if (*rv == NULL) + return; + + ir_dereference_array *const array_deref = (*rv)->as_dereference_array(); + if (array_deref == NULL) + return; + + /* Replace any expression that indexes one of the floats in gl_ClipDistance + * with an expression that indexes into one of the vec4's in + * gl_ClipDistanceMESA and accesses the appropriate component. + */ + ir_rvalue *lowered_vec8 = + this->lower_clip_distance_vec8(array_deref->array); + if (lowered_vec8 != NULL) { + this->progress = true; + ir_rvalue *array_index; + ir_rvalue *swizzle_index; + this->create_indices(array_deref->array_index, array_index, swizzle_index); + void *mem_ctx = ralloc_parent(array_deref); + + ir_dereference_array *const new_array_deref = + new(mem_ctx) ir_dereference_array(lowered_vec8, array_index); + + ir_expression *const expr = + new(mem_ctx) ir_expression(ir_binop_vector_extract, + new_array_deref, + swizzle_index); + + *rv = expr; + } +} + +void +lower_clip_distance_visitor::fix_lhs(ir_assignment *ir) +{ + if (ir->lhs->ir_type == ir_type_expression) { + void *mem_ctx = ralloc_parent(ir); + ir_expression *const expr = (ir_expression *) ir->lhs; + + /* The expression must be of the form: + * + * (vector_extract gl_ClipDistanceMESA[i], j). + */ + assert(expr->operation == ir_binop_vector_extract); + assert(expr->operands[0]->ir_type == ir_type_dereference_array); + assert(expr->operands[0]->type == glsl_type::vec4_type); + + ir_dereference *const new_lhs = (ir_dereference *) expr->operands[0]; + ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert, + glsl_type::vec4_type, + new_lhs->clone(mem_ctx, NULL), + ir->rhs, + expr->operands[1]); + ir->set_lhs(new_lhs); + ir->write_mask = WRITEMASK_XYZW; + } +} + +/** + * Replace any assignment having the 1D gl_ClipDistance (undereferenced) as + * its LHS or RHS with a sequence of assignments, one for each component of + * the array. Each of these assignments is lowered to refer to + * gl_ClipDistanceMESA as appropriate. + * + * We need to do a similar replacement for 2D gl_ClipDistance, however since + * it's an input, the only case we need to address is where a 1D slice of it + * is the entire RHS of an assignment, e.g.: + * + * foo = gl_in[i].gl_ClipDistance + */ +ir_visitor_status +lower_clip_distance_visitor::visit_leave(ir_assignment *ir) +{ + /* First invoke the base class visitor. This causes handle_rvalue() to be + * called on ir->rhs and ir->condition. + */ + ir_rvalue_visitor::visit_leave(ir); + + if (this->is_clip_distance_vec8(ir->lhs) || + this->is_clip_distance_vec8(ir->rhs)) { + /* LHS or RHS of the assignment is the entire 1D gl_ClipDistance array + * (or a 1D slice of a 2D gl_ClipDistance input array). Since we are + * reshaping gl_ClipDistance from an array of floats to an array of + * vec4's, this isn't going to work as a bulk assignment anymore, so + * unroll it to element-by-element assignments and lower each of them. + * + * Note: to unroll into element-by-element assignments, we need to make + * clones of the LHS and RHS. This is safe because expressions and + * l-values are side-effect free. + */ + void *ctx = ralloc_parent(ir); + int array_size = ir->lhs->type->array_size(); + for (int i = 0; i < array_size; ++i) { + ir_dereference_array *new_lhs = new(ctx) ir_dereference_array( + ir->lhs->clone(ctx, NULL), new(ctx) ir_constant(i)); + ir_dereference_array *new_rhs = new(ctx) ir_dereference_array( + ir->rhs->clone(ctx, NULL), new(ctx) ir_constant(i)); + this->handle_rvalue((ir_rvalue **) &new_rhs); + + /* Handle the LHS after creating the new assignment. This must + * happen in this order because handle_rvalue may replace the old LHS + * with an ir_expression of ir_binop_vector_extract. Since this is + * not a valide l-value, this will cause an assertion in the + * ir_assignment constructor to fail. + * + * If this occurs, replace the mangled LHS with a dereference of the + * vector, and replace the RHS with an ir_triop_vector_insert. + */ + ir_assignment *const assign = new(ctx) ir_assignment(new_lhs, new_rhs); + this->handle_rvalue((ir_rvalue **) &assign->lhs); + this->fix_lhs(assign); + + this->base_ir->insert_before(assign); + } + ir->remove(); + + return visit_continue; + } + + /* Handle the LHS as if it were an r-value. Normally + * rvalue_visit(ir_assignment *) only visits the RHS, but we need to lower + * expressions in the LHS as well. + * + * This may cause the LHS to get replaced with an ir_expression of + * ir_binop_vector_extract. If this occurs, replace it with a dereference + * of the vector, and replace the RHS with an ir_triop_vector_insert. + */ + handle_rvalue((ir_rvalue **)&ir->lhs); + this->fix_lhs(ir); + + return rvalue_visit(ir); +} + + +/** + * Set up base_ir properly and call visit_leave() on a newly created + * ir_assignment node. This is used in cases where we have to insert an + * ir_assignment in a place where we know the hierarchical visitor won't see + * it. + */ +void +lower_clip_distance_visitor::visit_new_assignment(ir_assignment *ir) +{ + ir_instruction *old_base_ir = this->base_ir; + this->base_ir = ir; + ir->accept(this); + this->base_ir = old_base_ir; +} + + +/** + * If a 1D gl_ClipDistance variable appears as an argument in an ir_call + * expression, replace it with a temporary variable, and make sure the ir_call + * is preceded and/or followed by assignments that copy the contents of the + * temporary variable to and/or from gl_ClipDistance. Each of these + * assignments is then lowered to refer to gl_ClipDistanceMESA. + * + * We need to do a similar replacement for 2D gl_ClipDistance, however since + * it's an input, the only case we need to address is where a 1D slice of it + * is passed as an "in" parameter to an ir_call, e.g.: + * + * foo(gl_in[i].gl_ClipDistance) + */ +ir_visitor_status +lower_clip_distance_visitor::visit_leave(ir_call *ir) +{ + void *ctx = ralloc_parent(ir); + + const exec_node *formal_param_node = ir->callee->parameters.head; + const exec_node *actual_param_node = ir->actual_parameters.head; + while (!actual_param_node->is_tail_sentinel()) { + ir_variable *formal_param = (ir_variable *) formal_param_node; + ir_rvalue *actual_param = (ir_rvalue *) actual_param_node; + + /* Advance formal_param_node and actual_param_node now so that we can + * safely replace actual_param with another node, if necessary, below. + */ + formal_param_node = formal_param_node->next; + actual_param_node = actual_param_node->next; + + if (this->is_clip_distance_vec8(actual_param)) { + /* User is trying to pass the whole 1D gl_ClipDistance array (or a 1D + * slice of a 2D gl_ClipDistance array) to a function call. Since we + * are reshaping gl_ClipDistance from an array of floats to an array + * of vec4's, this isn't going to work anymore, so use a temporary + * array instead. + */ + ir_variable *temp_clip_distance = new(ctx) ir_variable( + actual_param->type, "temp_clip_distance", ir_var_temporary); + this->base_ir->insert_before(temp_clip_distance); + actual_param->replace_with( + new(ctx) ir_dereference_variable(temp_clip_distance)); + if (formal_param->data.mode == ir_var_function_in + || formal_param->data.mode == ir_var_function_inout) { + /* Copy from gl_ClipDistance to the temporary before the call. + * Since we are going to insert this copy before the current + * instruction, we need to visit it afterwards to make sure it + * gets lowered. + */ + ir_assignment *new_assignment = new(ctx) ir_assignment( + new(ctx) ir_dereference_variable(temp_clip_distance), + actual_param->clone(ctx, NULL)); + this->base_ir->insert_before(new_assignment); + this->visit_new_assignment(new_assignment); + } + if (formal_param->data.mode == ir_var_function_out + || formal_param->data.mode == ir_var_function_inout) { + /* Copy from the temporary to gl_ClipDistance after the call. + * Since visit_list_elements() has already decided which + * instruction it's going to visit next, we need to visit + * afterwards to make sure it gets lowered. + */ + ir_assignment *new_assignment = new(ctx) ir_assignment( + actual_param->clone(ctx, NULL), + new(ctx) ir_dereference_variable(temp_clip_distance)); + this->base_ir->insert_after(new_assignment); + this->visit_new_assignment(new_assignment); + } + } + } + + return rvalue_visit(ir); +} + + +bool +lower_clip_distance(gl_shader *shader) +{ + lower_clip_distance_visitor v(shader->Stage); + + visit_list_elements(&v, shader->ir); + + if (v.new_clip_distance_out_var) + shader->symbols->add_variable(v.new_clip_distance_out_var); + if (v.new_clip_distance_in_var) + shader->symbols->add_variable(v.new_clip_distance_in_var); + + return v.progress; +} |