diff options
Diffstat (limited to 'mesalib/src/glsl/opt_copy_propagation.cpp')
| -rw-r--r-- | mesalib/src/glsl/opt_copy_propagation.cpp | 348 |
1 files changed, 348 insertions, 0 deletions
diff --git a/mesalib/src/glsl/opt_copy_propagation.cpp b/mesalib/src/glsl/opt_copy_propagation.cpp new file mode 100644 index 000000000..088c4bdbc --- /dev/null +++ b/mesalib/src/glsl/opt_copy_propagation.cpp @@ -0,0 +1,348 @@ +/*
+ * 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_copy_propagation.cpp
+ *
+ * Moves usage of recently-copied variables to the previous copy of
+ * the variable.
+ *
+ * This should reduce the number of MOV instructions in the generated
+ * programs unless copy propagation is also done on the LIR, and may
+ * help anyway by triggering other optimizations that live in the HIR.
+ */
+
+#include "ir.h"
+#include "ir_visitor.h"
+#include "ir_basic_block.h"
+#include "ir_optimization.h"
+#include "glsl_types.h"
+
+class acp_entry : public exec_node
+{
+public:
+ acp_entry(ir_variable *lhs, ir_variable *rhs)
+ {
+ assert(lhs);
+ assert(rhs);
+ this->lhs = lhs;
+ this->rhs = rhs;
+ }
+
+ ir_variable *lhs;
+ ir_variable *rhs;
+};
+
+
+class kill_entry : public exec_node
+{
+public:
+ kill_entry(ir_variable *var)
+ {
+ assert(var);
+ this->var = var;
+ }
+
+ ir_variable *var;
+};
+
+class ir_copy_propagation_visitor : public ir_hierarchical_visitor {
+public:
+ ir_copy_propagation_visitor()
+ {
+ progress = false;
+ mem_ctx = talloc_new(0);
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ }
+ ~ir_copy_propagation_visitor()
+ {
+ talloc_free(mem_ctx);
+ }
+
+ virtual ir_visitor_status visit(class ir_dereference_variable *);
+ virtual ir_visitor_status visit_enter(class ir_loop *);
+ virtual ir_visitor_status visit_enter(class ir_function_signature *);
+ virtual ir_visitor_status visit_enter(class ir_function *);
+ virtual ir_visitor_status visit_leave(class ir_assignment *);
+ virtual ir_visitor_status visit_enter(class ir_call *);
+ virtual ir_visitor_status visit_enter(class ir_if *);
+
+ void add_copy(ir_assignment *ir);
+ void kill(ir_variable *ir);
+ void handle_if_block(exec_list *instructions);
+
+ /** List of acp_entry: The available copies to propagate */
+ exec_list *acp;
+ /**
+ * List of kill_entry: The variables whose values were killed in this
+ * block.
+ */
+ exec_list *kills;
+
+ bool progress;
+
+ bool killed_all;
+
+ void *mem_ctx;
+};
+
+ir_visitor_status
+ir_copy_propagation_visitor::visit_enter(ir_function_signature *ir)
+{
+ /* Treat entry into a function signature as a completely separate
+ * block. Any instructions at global scope will be shuffled into
+ * main() at link time, so they're irrelevant to us.
+ */
+ exec_list *orig_acp = this->acp;
+ exec_list *orig_kills = this->kills;
+ bool orig_killed_all = this->killed_all;
+
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ this->killed_all = false;
+
+ visit_list_elements(this, &ir->body);
+
+ this->kills = orig_kills;
+ this->acp = orig_acp;
+ this->killed_all = orig_killed_all;
+
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_copy_propagation_visitor::visit_leave(ir_assignment *ir)
+{
+ kill(ir->lhs->variable_referenced());
+
+ add_copy(ir);
+
+ return visit_continue;
+}
+
+ir_visitor_status
+ir_copy_propagation_visitor::visit_enter(ir_function *ir)
+{
+ (void) ir;
+ return visit_continue;
+}
+
+/**
+ * Replaces dereferences of ACP RHS variables with ACP LHS variables.
+ *
+ * This is where the actual copy propagation occurs. Note that the
+ * rewriting of ir_dereference means that the ir_dereference instance
+ * must not be shared by multiple IR operations!
+ */
+ir_visitor_status
+ir_copy_propagation_visitor::visit(ir_dereference_variable *ir)
+{
+ if (this->in_assignee)
+ return visit_continue;
+
+ ir_variable *var = ir->var;
+
+ foreach_iter(exec_list_iterator, iter, *this->acp) {
+ acp_entry *entry = (acp_entry *)iter.get();
+
+ if (var == entry->lhs) {
+ ir->var = entry->rhs;
+ this->progress = true;
+ break;
+ }
+ }
+
+ return visit_continue;
+}
+
+
+ir_visitor_status
+ir_copy_propagation_visitor::visit_enter(ir_call *ir)
+{
+ /* Do copy propagation on call parameters, but skip any out params */
+ exec_list_iterator sig_param_iter = ir->get_callee()->parameters.iterator();
+ foreach_iter(exec_list_iterator, iter, ir->actual_parameters) {
+ ir_variable *sig_param = (ir_variable *)sig_param_iter.get();
+ ir_instruction *ir = (ir_instruction *)iter.get();
+ if (sig_param->mode != ir_var_out && sig_param->mode != ir_var_inout) {
+ ir->accept(this);
+ }
+ sig_param_iter.next();
+ }
+
+ /* Since we're unlinked, we don't (necssarily) know the side effects of
+ * this call. So kill all copies.
+ */
+ acp->make_empty();
+ this->killed_all = true;
+
+ return visit_continue_with_parent;
+}
+
+void
+ir_copy_propagation_visitor::handle_if_block(exec_list *instructions)
+{
+ exec_list *orig_acp = this->acp;
+ exec_list *orig_kills = this->kills;
+ bool orig_killed_all = this->killed_all;
+
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ this->killed_all = false;
+
+ /* Populate the initial acp with a copy of the original */
+ foreach_iter(exec_list_iterator, iter, *orig_acp) {
+ acp_entry *a = (acp_entry *)iter.get();
+ this->acp->push_tail(new(this->mem_ctx) acp_entry(a->lhs, a->rhs));
+ }
+
+ visit_list_elements(this, instructions);
+
+ if (this->killed_all) {
+ orig_acp->make_empty();
+ }
+
+ exec_list *new_kills = this->kills;
+ this->kills = orig_kills;
+ this->acp = orig_acp;
+ this->killed_all = this->killed_all || orig_killed_all;
+
+ foreach_iter(exec_list_iterator, iter, *new_kills) {
+ kill_entry *k = (kill_entry *)iter.get();
+ kill(k->var);
+ }
+}
+
+ir_visitor_status
+ir_copy_propagation_visitor::visit_enter(ir_if *ir)
+{
+ ir->condition->accept(this);
+
+ handle_if_block(&ir->then_instructions);
+ handle_if_block(&ir->else_instructions);
+
+ /* handle_if_block() already descended into the children. */
+ return visit_continue_with_parent;
+}
+
+ir_visitor_status
+ir_copy_propagation_visitor::visit_enter(ir_loop *ir)
+{
+ exec_list *orig_acp = this->acp;
+ exec_list *orig_kills = this->kills;
+ bool orig_killed_all = this->killed_all;
+
+ /* FINISHME: For now, the initial acp for loops is totally empty.
+ * We could go through once, then go through again with the acp
+ * cloned minus the killed entries after the first run through.
+ */
+ this->acp = new(mem_ctx) exec_list;
+ this->kills = new(mem_ctx) exec_list;
+ this->killed_all = false;
+
+ visit_list_elements(this, &ir->body_instructions);
+
+ if (this->killed_all) {
+ orig_acp->make_empty();
+ }
+
+ exec_list *new_kills = this->kills;
+ this->kills = orig_kills;
+ this->acp = orig_acp;
+ this->killed_all = this->killed_all || orig_killed_all;
+
+ foreach_iter(exec_list_iterator, iter, *new_kills) {
+ kill_entry *k = (kill_entry *)iter.get();
+ kill(k->var);
+ }
+
+ /* already descended into the children. */
+ return visit_continue_with_parent;
+}
+
+void
+ir_copy_propagation_visitor::kill(ir_variable *var)
+{
+ assert(var != NULL);
+
+ /* Remove any entries currently in the ACP for this kill. */
+ foreach_iter(exec_list_iterator, iter, *acp) {
+ acp_entry *entry = (acp_entry *)iter.get();
+
+ if (entry->lhs == var || entry->rhs == var) {
+ entry->remove();
+ }
+ }
+
+ /* Add the LHS variable to the list of killed variables in this block.
+ */
+ this->kills->push_tail(new(this->mem_ctx) kill_entry(var));
+}
+
+/**
+ * Adds an entry to the available copy list if it's a plain assignment
+ * of a variable to a variable.
+ */
+void
+ir_copy_propagation_visitor::add_copy(ir_assignment *ir)
+{
+ acp_entry *entry;
+
+ if (ir->condition) {
+ ir_constant *condition = ir->condition->as_constant();
+ if (!condition || !condition->value.b[0])
+ return;
+ }
+
+ ir_variable *lhs_var = ir->whole_variable_written();
+ ir_variable *rhs_var = ir->rhs->whole_variable_referenced();
+
+ if ((lhs_var != NULL) && (rhs_var != NULL)) {
+ if (lhs_var == rhs_var) {
+ /* This is a dumb assignment, but we've conveniently noticed
+ * it here. Removing it now would mess up the loop iteration
+ * calling us. Just flag it to not execute, and someone else
+ * will clean up the mess.
+ */
+ ir->condition = new(talloc_parent(ir)) ir_constant(false);
+ this->progress = true;
+ } else {
+ entry = new(this->mem_ctx) acp_entry(lhs_var, rhs_var);
+ this->acp->push_tail(entry);
+ }
+ }
+}
+
+/**
+ * Does a copy propagation pass on the code present in the instruction stream.
+ */
+bool
+do_copy_propagation(exec_list *instructions)
+{
+ ir_copy_propagation_visitor v;
+
+ visit_list_elements(&v, instructions);
+
+ return v.progress;
+}
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