diff options
Diffstat (limited to 'src/glsl/ir_dead_code_local.cpp')
| -rw-r--r-- | src/glsl/ir_dead_code_local.cpp | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/src/glsl/ir_dead_code_local.cpp b/src/glsl/ir_dead_code_local.cpp new file mode 100644 index 00000000000..4bbedf0ff94 --- /dev/null +++ b/src/glsl/ir_dead_code_local.cpp @@ -0,0 +1,229 @@ +/* + * 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 ir_dead_code_local.cpp + * + * Eliminates local dead assignments from the code. + * + * This operates on basic blocks, tracking assignments and finding if + * they're used before the variable is completely reassigned. + * + * Compare this to ir_dead_code.cpp, which operates globally looking + * for assignments to variables that are never read. + */ + +#include "ir.h" +#include "ir_basic_block.h" +#include "ir_optimization.h" +#include "glsl_types.h" + +static bool debug = false; + +class assignment_entry : public exec_node +{ +public: + assignment_entry(ir_variable *lhs, ir_instruction *ir) + { + assert(lhs); + assert(ir); + this->lhs = lhs; + this->ir = ir; + } + + ir_variable *lhs; + ir_instruction *ir; +}; + +class kill_for_derefs_visitor : public ir_hierarchical_visitor { +public: + kill_for_derefs_visitor(exec_list *assignments) + { + this->assignments = assignments; + } + + virtual ir_visitor_status visit(ir_dereference_variable *ir) + { + ir_variable *const var = ir->variable_referenced(); + + foreach_iter(exec_list_iterator, iter, *this->assignments) { + assignment_entry *entry = (assignment_entry *)iter.get(); + + if (entry->lhs == var) { + if (debug) + printf("kill %s\n", entry->lhs->name); + entry->remove(); + } + } + + return visit_continue; + } + +private: + exec_list *assignments; +}; + +class array_index_visit : public ir_hierarchical_visitor { +public: + array_index_visit(ir_hierarchical_visitor *v) + { + this->visitor = v; + } + + virtual ir_visitor_status visit_enter(class ir_dereference_array *ir) + { + ir->array_index->accept(visitor); + return visit_continue; + } + + static void run(ir_instruction *ir, ir_hierarchical_visitor *v) + { + array_index_visit top_visit(v); + ir->accept(& top_visit); + } + + ir_hierarchical_visitor *visitor; +}; + + +/** + * Adds an entry to the available copy list if it's a plain assignment + * of a variable to a variable. + */ +static bool +process_assignment(void *ctx, ir_assignment *ir, exec_list *assignments) +{ + ir_variable *var = NULL; + bool progress = false; + kill_for_derefs_visitor v(assignments); + + /* Kill assignment entries for things used to produce this assignment. */ + ir->rhs->accept(&v); + if (ir->condition) { + ir->condition->accept(&v); + } + + /* Kill assignment enties used as array indices. + */ + array_index_visit::run(ir->lhs, &v); + var = ir->lhs->variable_referenced(); + assert(var); + + bool always_assign = true; + if (ir->condition) { + ir_constant *condition = ir->condition->as_constant(); + if (!condition || !condition->value.b[0]) + always_assign = false; + } + + /* Now, check if we did a whole-variable assignment. */ + if (always_assign && (ir->whole_variable_written() != NULL)) { + /* We did a whole-variable assignment. So, any instruction in + * the assignment list with the same LHS is dead. + */ + if (debug) + printf("looking for %s to remove\n", var->name); + foreach_iter(exec_list_iterator, iter, *assignments) { + assignment_entry *entry = (assignment_entry *)iter.get(); + + if (entry->lhs == var) { + if (debug) + printf("removing %s\n", var->name); + entry->ir->remove(); + entry->remove(); + progress = true; + } + } + } + + /* Add this instruction to the assignment list available to be removed. + * But not if the assignment has other side effects. + */ + if (ir_has_call(ir)) + return progress; + + assignment_entry *entry = new(ctx) assignment_entry(var, ir); + assignments->push_tail(entry); + + if (debug) { + printf("add %s\n", var->name); + + printf("current entries\n"); + foreach_iter(exec_list_iterator, iter, *assignments) { + assignment_entry *entry = (assignment_entry *)iter.get(); + + printf(" %s\n", entry->lhs->name); + } + } + + return progress; +} + +static void +dead_code_local_basic_block(ir_instruction *first, + ir_instruction *last, + void *data) +{ + ir_instruction *ir, *ir_next; + /* List of avaialble_copy */ + exec_list assignments; + bool *out_progress = (bool *)data; + bool progress = false; + + void *ctx = talloc_new(NULL); + /* Safe looping, since process_assignment */ + for (ir = first, ir_next = (ir_instruction *)first->next;; + ir = ir_next, ir_next = (ir_instruction *)ir->next) { + ir_assignment *ir_assign = ir->as_assignment(); + + if (debug) { + ir->print(); + printf("\n"); + } + + if (ir_assign) { + progress = process_assignment(ctx, ir_assign, &assignments) || progress; + } else { + kill_for_derefs_visitor kill(&assignments); + ir->accept(&kill); + } + + if (ir == last) + break; + } + *out_progress = progress; + talloc_free(ctx); +} + +/** + * Does a copy propagation pass on the code present in the instruction stream. + */ +bool +do_dead_code_local(exec_list *instructions) +{ + bool progress = false; + + call_for_basic_blocks(instructions, dead_code_local_basic_block, &progress); + + return progress; +} |