diff options
Diffstat (limited to 'src/compiler/glsl/opt_constant_variable.cpp')
| -rw-r--r-- | src/compiler/glsl/opt_constant_variable.cpp | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/src/compiler/glsl/opt_constant_variable.cpp b/src/compiler/glsl/opt_constant_variable.cpp new file mode 100644 index 00000000000..3ddb12904c7 --- /dev/null +++ b/src/compiler/glsl/opt_constant_variable.cpp @@ -0,0 +1,218 @@ +/* + * Copyright © 2010 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 opt_constant_variable.cpp + * + * Marks variables assigned a single constant value over the course + * of the program as constant. + * + * The goal here is to trigger further constant folding and then dead + * code elimination. This is common with vector/matrix constructors + * and calls to builtin functions. + */ + +#include "ir.h" +#include "ir_visitor.h" +#include "ir_optimization.h" +#include "compiler/glsl_types.h" +#include "util/hash_table.h" + +namespace { + +struct assignment_entry { + int assignment_count; + ir_variable *var; + ir_constant *constval; + bool our_scope; +}; + +class ir_constant_variable_visitor : public ir_hierarchical_visitor { +public: + virtual ir_visitor_status visit_enter(ir_dereference_variable *); + virtual ir_visitor_status visit(ir_variable *); + virtual ir_visitor_status visit_enter(ir_assignment *); + virtual ir_visitor_status visit_enter(ir_call *); + + struct hash_table *ht; +}; + +} /* unnamed namespace */ + +static struct assignment_entry * +get_assignment_entry(ir_variable *var, struct hash_table *ht) +{ + struct hash_entry *hte = _mesa_hash_table_search(ht, var); + struct assignment_entry *entry; + + if (hte) { + entry = (struct assignment_entry *) hte->data; + } else { + entry = (struct assignment_entry *) calloc(1, sizeof(*entry)); + entry->var = var; + _mesa_hash_table_insert(ht, var, entry); + } + + return entry; +} + +ir_visitor_status +ir_constant_variable_visitor::visit(ir_variable *ir) +{ + struct assignment_entry *entry = get_assignment_entry(ir, this->ht); + entry->our_scope = true; + return visit_continue; +} + +/* Skip derefs of variables so that we can detect declarations. */ +ir_visitor_status +ir_constant_variable_visitor::visit_enter(ir_dereference_variable *ir) +{ + (void)ir; + return visit_continue_with_parent; +} + +ir_visitor_status +ir_constant_variable_visitor::visit_enter(ir_assignment *ir) +{ + ir_constant *constval; + struct assignment_entry *entry; + + entry = get_assignment_entry(ir->lhs->variable_referenced(), this->ht); + assert(entry); + entry->assignment_count++; + + /* If it's already constant, don't do the work. */ + if (entry->var->constant_value) + return visit_continue; + + /* OK, now find if we actually have all the right conditions for + * this to be a constant value assigned to the var. + */ + if (ir->condition) + return visit_continue; + + ir_variable *var = ir->whole_variable_written(); + if (!var) + return visit_continue; + + /* Ignore buffer variables, since the underlying storage is shared + * and we can't be sure that this variable won't be written by another + * thread. + */ + if (var->data.mode == ir_var_shader_storage || + var->data.mode == ir_var_shader_shared) + return visit_continue; + + constval = ir->rhs->constant_expression_value(); + if (!constval) + return visit_continue; + + /* Mark this entry as having a constant assignment (if the + * assignment count doesn't go >1). do_constant_variable will fix + * up the variable with the constant value later. + */ + entry->constval = constval; + + return visit_continue; +} + +ir_visitor_status +ir_constant_variable_visitor::visit_enter(ir_call *ir) +{ + /* Mark any out parameters as assigned to */ + foreach_two_lists(formal_node, &ir->callee->parameters, + actual_node, &ir->actual_parameters) { + ir_rvalue *param_rval = (ir_rvalue *) actual_node; + ir_variable *param = (ir_variable *) formal_node; + + if (param->data.mode == ir_var_function_out || + param->data.mode == ir_var_function_inout) { + ir_variable *var = param_rval->variable_referenced(); + struct assignment_entry *entry; + + assert(var); + entry = get_assignment_entry(var, this->ht); + entry->assignment_count++; + } + } + + /* Mark the return storage as having been assigned to */ + if (ir->return_deref != NULL) { + ir_variable *var = ir->return_deref->variable_referenced(); + struct assignment_entry *entry; + + assert(var); + entry = get_assignment_entry(var, this->ht); + entry->assignment_count++; + } + + return visit_continue; +} + +/** + * Does a copy propagation pass on the code present in the instruction stream. + */ +bool +do_constant_variable(exec_list *instructions) +{ + bool progress = false; + ir_constant_variable_visitor v; + + v.ht = _mesa_hash_table_create(NULL, _mesa_hash_pointer, + _mesa_key_pointer_equal); + v.run(instructions); + + struct hash_entry *hte; + hash_table_foreach(v.ht, hte) { + struct assignment_entry *entry = (struct assignment_entry *) hte->data; + + if (entry->assignment_count == 1 && entry->constval && entry->our_scope) { + entry->var->constant_value = entry->constval; + progress = true; + } + hte->data = NULL; + free(entry); + } + _mesa_hash_table_destroy(v.ht, NULL); + + return progress; +} + +bool +do_constant_variable_unlinked(exec_list *instructions) +{ + bool progress = false; + + foreach_in_list(ir_instruction, ir, instructions) { + ir_function *f = ir->as_function(); + if (f) { + foreach_in_list(ir_function_signature, sig, &f->signatures) { + if (do_constant_variable(&sig->body)) + progress = true; + } + } + } + + return progress; +} |