diff options
| -rw-r--r-- | src/glsl/lower_ubo_reference.cpp | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/src/glsl/lower_ubo_reference.cpp b/src/glsl/lower_ubo_reference.cpp index b74aa3d0630..b82d800eefb 100644 --- a/src/glsl/lower_ubo_reference.cpp +++ b/src/glsl/lower_ubo_reference.cpp @@ -154,6 +154,7 @@ public: ir_call *ssbo_load(const struct glsl_type *type, ir_rvalue *offset); + bool check_for_buffer_array_copy(ir_assignment *ir); void check_for_ssbo_store(ir_assignment *ir); void write_to_memory(ir_dereference *deref, ir_variable *var, @@ -1132,10 +1133,76 @@ lower_ubo_reference_visitor::check_for_ssbo_store(ir_assignment *ir) progress = true; } +static bool +is_buffer_backed_variable(ir_variable *var) +{ + return var->is_in_buffer_block() || + var->data.mode == ir_var_shader_shared; +} + +bool +lower_ubo_reference_visitor::check_for_buffer_array_copy(ir_assignment *ir) +{ + if (!ir || !ir->lhs || !ir->rhs) + return false; + + /* LHS and RHS must be arrays + * FIXME: arrays of arrays? + */ + if (!ir->lhs->type->is_array() || !ir->rhs->type->is_array()) + return false; + + /* RHS must be a buffer-backed variable. This is what can cause the problem + * since it would lead to a series of loads that need to live until we + * see the writes to the LHS. + */ + ir_variable *rhs_var = ir->rhs->variable_referenced(); + if (!rhs_var || !is_buffer_backed_variable(rhs_var)) + return false; + + /* Split the array copy into individual element copies to reduce + * register pressure + */ + ir_dereference *rhs_deref = ir->rhs->as_dereference(); + if (!rhs_deref) + return false; + + ir_dereference *lhs_deref = ir->lhs->as_dereference(); + if (!lhs_deref) + return false; + + assert(lhs_deref->type->length == rhs_deref->type->length); + mem_ctx = ralloc_parent(shader->ir); + + for (unsigned i = 0; i < lhs_deref->type->length; i++) { + ir_dereference *lhs_i = + new(mem_ctx) ir_dereference_array(lhs_deref->clone(mem_ctx, NULL), + new(mem_ctx) ir_constant(i)); + + ir_dereference *rhs_i = + new(mem_ctx) ir_dereference_array(rhs_deref->clone(mem_ctx, NULL), + new(mem_ctx) ir_constant(i)); + ir->insert_after(assign(lhs_i, rhs_i)); + } + + ir->remove(); + progress = true; + return true; +} ir_visitor_status lower_ubo_reference_visitor::visit_enter(ir_assignment *ir) { + /* Array copies could involve large amounts of load/store + * operations. To improve register pressure we want to special-case + * these and split array copies into individual element copies. + * This way we avoid emitting all the loads for the RHS first and + * all the writes for the LHS second and register usage is more + * efficient. + */ + if (check_for_buffer_array_copy(ir)) + return visit_continue_with_parent; + check_ssbo_unsized_array_length_assignment(ir); check_for_ssbo_store(ir); return rvalue_visit(ir); |