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Diffstat (limited to 'src/glsl/lower_clip_distance.cpp')
| -rw-r--r-- | src/glsl/lower_clip_distance.cpp | 344 |
1 files changed, 344 insertions, 0 deletions
diff --git a/src/glsl/lower_clip_distance.cpp b/src/glsl/lower_clip_distance.cpp new file mode 100644 index 00000000000..143e378f97b --- /dev/null +++ b/src/glsl/lower_clip_distance.cpp @@ -0,0 +1,344 @@ +/* + * 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 "ir_hierarchical_visitor.h" +#include "ir.h" + +class lower_clip_distance_visitor : public ir_hierarchical_visitor { +public: + lower_clip_distance_visitor() + : progress(false), old_clip_distance_var(NULL), + new_clip_distance_var(NULL) + { + } + + virtual ir_visitor_status visit(ir_variable *); + void create_indices(ir_rvalue*, ir_rvalue *&, ir_rvalue *&); + virtual ir_visitor_status visit_leave(ir_dereference_array *); + virtual ir_visitor_status visit_leave(ir_assignment *); + void visit_new_assignment(ir_assignment *ir); + virtual ir_visitor_status visit_leave(ir_call *); + + bool progress; + + /** + * Pointer to the declaration of gl_ClipDistance, if found. + */ + ir_variable *old_clip_distance_var; + + /** + * Pointer to the newly-created gl_ClipDistanceMESA variable. + */ + ir_variable *new_clip_distance_var; +}; + + +/** + * 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) +{ + /* No point in looking for the declaration of gl_ClipDistance if + * we've already found it. + */ + if (this->old_clip_distance_var) + return visit_continue; + + if (ir->name && strcmp(ir->name, "gl_ClipDistance") == 0) { + this->progress = true; + this->old_clip_distance_var = ir; + assert (ir->type->is_array()); + assert (ir->type->element_type() == 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 */ + this->new_clip_distance_var = ir->clone(ralloc_parent(ir), NULL); + + /* And change the properties that we need to change */ + this->new_clip_distance_var->name + = ralloc_strdup(this->new_clip_distance_var, "gl_ClipDistanceMESA"); + this->new_clip_distance_var->type + = glsl_type::get_array_instance(glsl_type::vec4_type, new_size); + this->new_clip_distance_var->max_array_access = ir->max_array_access / 4; + + ir->replace_with(this->new_clip_distance_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)); + } +} + + +/** + * Replace any expression that indexes into the gl_ClipDistance array with an + * expression that indexes into one of the vec4's in gl_ClipDistanceMESA and + * accesses the appropriate component. + */ +ir_visitor_status +lower_clip_distance_visitor::visit_leave(ir_dereference_array *ir) +{ + /* If the gl_ClipDistance var hasn't been declared yet, then + * there's no way this deref can refer to it. + */ + if (!this->old_clip_distance_var) + return visit_continue; + + ir_dereference_variable *old_var_ref = ir->array->as_dereference_variable(); + if (old_var_ref && old_var_ref->var == this->old_clip_distance_var) { + this->progress = true; + ir_rvalue *array_index; + ir_rvalue *swizzle_index; + this->create_indices(ir->array_index, array_index, swizzle_index); + void *mem_ctx = ralloc_parent(ir); + ir->array = new(mem_ctx) ir_dereference_array( + this->new_clip_distance_var, array_index); + ir->array_index = swizzle_index; + } + + return visit_continue; +} + + +/** + * Replace any assignment having 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. + */ +ir_visitor_status +lower_clip_distance_visitor::visit_leave(ir_assignment *ir) +{ + ir_dereference_variable *lhs_var = ir->lhs->as_dereference_variable(); + ir_dereference_variable *rhs_var = ir->rhs->as_dereference_variable(); + if ((lhs_var && lhs_var->var == this->old_clip_distance_var) + || (rhs_var && rhs_var->var == this->old_clip_distance_var)) { + /* LHS or RHS of the assignment is the entire gl_ClipDistance 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 only safe if the LHS and RHS are + * side-effect free. Fortunately, we know that they are, because the + * only kind of rvalue that can have side effects is an ir_call, and + * ir_calls only appear (a) as a statement on their own, or (b) as the + * RHS of an assignment that stores the result of the call in a + * temporary variable. + */ + void *ctx = ralloc_parent(ir); + int array_size = this->old_clip_distance_var->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)); + new_lhs->accept(this); + ir_dereference_array *new_rhs = new(ctx) ir_dereference_array( + ir->rhs->clone(ctx, NULL), new(ctx) ir_constant(i)); + new_rhs->accept(this); + this->base_ir->insert_before( + new(ctx) ir_assignment(new_lhs, new_rhs)); + } + ir->remove(); + } + + return visit_continue; +} + + +/** + * 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 gl_ClipDistance 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. + */ +ir_visitor_status +lower_clip_distance_visitor::visit_leave(ir_call *ir) +{ + void *ctx = ralloc_parent(ir); + + const exec_node *formal_param_node = ir->get_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; + + ir_dereference_variable *deref = actual_param->as_dereference_variable(); + if (deref && deref->var == this->old_clip_distance_var) { + /* User is trying to pass the whole 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->mode == ir_var_in + || formal_param->mode == ir_var_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), + new(ctx) ir_dereference_variable(old_clip_distance_var)); + this->base_ir->insert_before(new_assignment); + this->visit_new_assignment(new_assignment); + } + if (formal_param->mode == ir_var_out + || formal_param->mode == ir_var_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( + new(ctx) ir_dereference_variable(old_clip_distance_var), + new(ctx) ir_dereference_variable(temp_clip_distance)); + this->base_ir->insert_after(new_assignment); + this->visit_new_assignment(new_assignment); + } + } + } + + return visit_continue; +} + + +bool +lower_clip_distance(exec_list *instructions) +{ + lower_clip_distance_visitor v; + + visit_list_elements(&v, instructions); + + return v.progress; +} |