diff options
Diffstat (limited to 'mesalib/src/glsl/opt_dead_code_local.cpp')
| -rw-r--r-- | mesalib/src/glsl/opt_dead_code_local.cpp | 229 |
1 files changed, 229 insertions, 0 deletions
diff --git a/mesalib/src/glsl/opt_dead_code_local.cpp b/mesalib/src/glsl/opt_dead_code_local.cpp new file mode 100644 index 000000000..182eccac2 --- /dev/null +++ b/mesalib/src/glsl/opt_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 opt_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;
+}
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