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* Copyright © 2013 Intel Corporation
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice (including the next
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* paragraph) shall be included in all copies or substantial portions of the
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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* DEALINGS IN THE SOFTWARE.
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#include "ir_builder.h"
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#include "ir_rvalue_visitor.h"
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#include "ir_optimization.h"
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#include "main/shader_types.h"
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using namespace ir_builder;
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class vector_deref_visitor : public ir_rvalue_enter_visitor {
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vector_deref_visitor(void *mem_ctx, gl_shader_stage shader_stage)
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: progress(false), shader_stage(shader_stage),
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factory(&factory_instructions, mem_ctx)
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virtual ~vector_deref_visitor()
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virtual void handle_rvalue(ir_rvalue **rv);
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virtual ir_visitor_status visit_enter(ir_assignment *ir);
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gl_shader_stage shader_stage;
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exec_list factory_instructions;
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} /* anonymous namespace */
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vector_deref_visitor::visit_enter(ir_assignment *ir)
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if (!ir->lhs || ir->lhs->ir_type != ir_type_dereference_array)
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return ir_rvalue_enter_visitor::visit_enter(ir);
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ir_dereference_array *const deref = (ir_dereference_array *) ir->lhs;
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if (!deref->array->type->is_vector())
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return ir_rvalue_enter_visitor::visit_enter(ir);
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/* SSBOs and shared variables are backed by memory and may be accessed by
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* multiple threads simultaneously. It's not safe to lower a single
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* component store to a load-vec-store because it may race with writes to
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ir_variable *var = deref->variable_referenced();
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if (var->data.mode == ir_var_shader_storage ||
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var->data.mode == ir_var_shader_shared)
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return ir_rvalue_enter_visitor::visit_enter(ir);
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ir_rvalue *const new_lhs = deref->array;
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void *mem_ctx = ralloc_parent(ir);
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ir_constant *old_index_constant =
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deref->array_index->constant_expression_value(mem_ctx);
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if (!old_index_constant) {
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if (shader_stage == MESA_SHADER_TESS_CTRL &&
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deref->variable_referenced()->data.mode == ir_var_shader_out) {
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/* Tessellation control shader outputs act as if they have memory
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* backing them and if we have writes from multiple threads
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* targeting the same vec4 (this can happen for patch outputs), the
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* load-vec-store pattern of ir_triop_vector_insert doesn't work.
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* Instead, we have to lower to a series of conditional write-masked
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ir_variable *const src_temp =
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factory.make_temp(ir->rhs->type, "scalar_tmp");
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/* The newly created variable declaration goes before the assignment
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* because we're going to set it as the new LHS.
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ir->insert_before(factory.instructions);
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ir->set_lhs(new(mem_ctx) ir_dereference_variable(src_temp));
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ir_variable *const arr_index =
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factory.make_temp(deref->array_index->type, "index_tmp");
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factory.emit(assign(arr_index, deref->array_index));
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for (unsigned i = 0; i < new_lhs->type->vector_elements; i++) {
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ir_constant *const cmp_index =
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ir_constant::zero(factory.mem_ctx, deref->array_index->type);
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cmp_index->value.u[0] = i;
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ir_rvalue *const lhs_clone = new_lhs->clone(factory.mem_ctx, NULL);
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ir_dereference_variable *const src_temp_deref =
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new(mem_ctx) ir_dereference_variable(src_temp);
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if (new_lhs->ir_type != ir_type_swizzle) {
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assert(lhs_clone->as_dereference());
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factory.emit(if_tree(equal(arr_index, cmp_index),
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assign(lhs_clone->as_dereference(),
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ir_assignment *cond_assign =
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new(mem_ctx) ir_assignment(swizzle(lhs_clone, i, 1),
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factory.emit(if_tree(equal(arr_index, cmp_index), cond_assign));
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ir->insert_after(factory.instructions);
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ir->rhs = new(mem_ctx) ir_expression(ir_triop_vector_insert,
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new_lhs->clone(mem_ctx, NULL),
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ir->write_mask = (1 << new_lhs->type->vector_elements) - 1;
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ir->set_lhs(new_lhs);
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unsigned index = old_index_constant->get_uint_component(0);
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if (index >= new_lhs->type->vector_elements) {
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/* Section 5.11 (Out-of-Bounds Accesses) of the GLSL 4.60 spec says:
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* In the subsections described above for array, vector, matrix and
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* structure accesses, any out-of-bounds access produced undefined
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* behavior.... Out-of-bounds writes may be discarded or overwrite
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* other variables of the active program.
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return visit_continue;
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if (new_lhs->ir_type != ir_type_swizzle) {
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ir->set_lhs(new_lhs);
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ir->write_mask = 1 << index;
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/* If the "new" LHS is a swizzle, use the set_lhs helper to instead
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unsigned component[1] = { index };
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ir->set_lhs(new(mem_ctx) ir_swizzle(new_lhs, component, 1));
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return ir_rvalue_enter_visitor::visit_enter(ir);
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vector_deref_visitor::handle_rvalue(ir_rvalue **rv)
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if (*rv == NULL || (*rv)->ir_type != ir_type_dereference_array)
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ir_dereference_array *const deref = (ir_dereference_array *) *rv;
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if (!deref->array->type->is_vector())
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/* Back-ends need to be able to handle derefs on vectors for SSBOs, UBOs,
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* and shared variables. They have to handle it for writes anyway so we
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* may as well require it for reads.
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ir_variable *var = deref->variable_referenced();
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if (var && (var->data.mode == ir_var_shader_storage ||
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var->data.mode == ir_var_shader_shared ||
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(var->data.mode == ir_var_uniform &&
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var->get_interface_type())))
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void *mem_ctx = ralloc_parent(deref);
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*rv = new(mem_ctx) ir_expression(ir_binop_vector_extract,
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lower_vector_derefs(gl_linked_shader *shader)
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vector_deref_visitor v(shader->ir, shader->Stage);
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visit_list_elements(&v, shader->ir);