11591693c7b415e9869157c711fe11263c95d74eDavid Li/*
21591693c7b415e9869157c711fe11263c95d74eDavid Li * Copyright © 2010 Intel Corporation
31591693c7b415e9869157c711fe11263c95d74eDavid Li *
41591693c7b415e9869157c711fe11263c95d74eDavid Li * Permission is hereby granted, free of charge, to any person obtaining a
51591693c7b415e9869157c711fe11263c95d74eDavid Li * copy of this software and associated documentation files (the "Software"),
61591693c7b415e9869157c711fe11263c95d74eDavid Li * to deal in the Software without restriction, including without limitation
71591693c7b415e9869157c711fe11263c95d74eDavid Li * the rights to use, copy, modify, merge, publish, distribute, sublicense,
81591693c7b415e9869157c711fe11263c95d74eDavid Li * and/or sell copies of the Software, and to permit persons to whom the
91591693c7b415e9869157c711fe11263c95d74eDavid Li * Software is furnished to do so, subject to the following conditions:
101591693c7b415e9869157c711fe11263c95d74eDavid Li *
111591693c7b415e9869157c711fe11263c95d74eDavid Li * The above copyright notice and this permission notice (including the next
121591693c7b415e9869157c711fe11263c95d74eDavid Li * paragraph) shall be included in all copies or substantial portions of the
131591693c7b415e9869157c711fe11263c95d74eDavid Li * Software.
141591693c7b415e9869157c711fe11263c95d74eDavid Li *
151591693c7b415e9869157c711fe11263c95d74eDavid Li * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
161591693c7b415e9869157c711fe11263c95d74eDavid Li * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
171591693c7b415e9869157c711fe11263c95d74eDavid Li * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
181591693c7b415e9869157c711fe11263c95d74eDavid Li * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
191591693c7b415e9869157c711fe11263c95d74eDavid Li * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
201591693c7b415e9869157c711fe11263c95d74eDavid Li * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
211591693c7b415e9869157c711fe11263c95d74eDavid Li * DEALINGS IN THE SOFTWARE.
221591693c7b415e9869157c711fe11263c95d74eDavid Li */
231591693c7b415e9869157c711fe11263c95d74eDavid Li
241591693c7b415e9869157c711fe11263c95d74eDavid Li/**
251591693c7b415e9869157c711fe11263c95d74eDavid Li * \file opt_if_simplification.cpp
261591693c7b415e9869157c711fe11263c95d74eDavid Li *
271591693c7b415e9869157c711fe11263c95d74eDavid Li * Moves constant branches of if statements out to the surrounding
281591693c7b415e9869157c711fe11263c95d74eDavid Li * instruction stream.
291591693c7b415e9869157c711fe11263c95d74eDavid Li */
301591693c7b415e9869157c711fe11263c95d74eDavid Li
311591693c7b415e9869157c711fe11263c95d74eDavid Li#include "ir.h"
321591693c7b415e9869157c711fe11263c95d74eDavid Li
331591693c7b415e9869157c711fe11263c95d74eDavid Liclass ir_if_simplification_visitor : public ir_hierarchical_visitor {
341591693c7b415e9869157c711fe11263c95d74eDavid Lipublic:
351591693c7b415e9869157c711fe11263c95d74eDavid Li   ir_if_simplification_visitor()
361591693c7b415e9869157c711fe11263c95d74eDavid Li   {
371591693c7b415e9869157c711fe11263c95d74eDavid Li      this->made_progress = false;
381591693c7b415e9869157c711fe11263c95d74eDavid Li   }
391591693c7b415e9869157c711fe11263c95d74eDavid Li
401591693c7b415e9869157c711fe11263c95d74eDavid Li   ir_visitor_status visit_leave(ir_if *);
411591693c7b415e9869157c711fe11263c95d74eDavid Li
421591693c7b415e9869157c711fe11263c95d74eDavid Li   bool made_progress;
431591693c7b415e9869157c711fe11263c95d74eDavid Li};
441591693c7b415e9869157c711fe11263c95d74eDavid Li
451591693c7b415e9869157c711fe11263c95d74eDavid Libool
461591693c7b415e9869157c711fe11263c95d74eDavid Lido_if_simplification(exec_list *instructions)
471591693c7b415e9869157c711fe11263c95d74eDavid Li{
481591693c7b415e9869157c711fe11263c95d74eDavid Li   ir_if_simplification_visitor v;
491591693c7b415e9869157c711fe11263c95d74eDavid Li
501591693c7b415e9869157c711fe11263c95d74eDavid Li   v.run(instructions);
511591693c7b415e9869157c711fe11263c95d74eDavid Li   return v.made_progress;
521591693c7b415e9869157c711fe11263c95d74eDavid Li}
531591693c7b415e9869157c711fe11263c95d74eDavid Li
541591693c7b415e9869157c711fe11263c95d74eDavid Li
551591693c7b415e9869157c711fe11263c95d74eDavid Liir_visitor_status
561591693c7b415e9869157c711fe11263c95d74eDavid Liir_if_simplification_visitor::visit_leave(ir_if *ir)
571591693c7b415e9869157c711fe11263c95d74eDavid Li{
581591693c7b415e9869157c711fe11263c95d74eDavid Li   /* FINISHME: Ideally there would be a way to note that the condition results
591591693c7b415e9869157c711fe11263c95d74eDavid Li    * FINISHME: in a constant before processing both of the other subtrees.
601591693c7b415e9869157c711fe11263c95d74eDavid Li    * FINISHME: This can probably be done with some flags, but it would take
611591693c7b415e9869157c711fe11263c95d74eDavid Li    * FINISHME: some work to get right.
621591693c7b415e9869157c711fe11263c95d74eDavid Li    */
631591693c7b415e9869157c711fe11263c95d74eDavid Li   ir_constant *condition_constant = ir->condition->constant_expression_value();
641591693c7b415e9869157c711fe11263c95d74eDavid Li   if (condition_constant) {
651591693c7b415e9869157c711fe11263c95d74eDavid Li      /* Move the contents of the one branch of the conditional
661591693c7b415e9869157c711fe11263c95d74eDavid Li       * that matters out.
671591693c7b415e9869157c711fe11263c95d74eDavid Li       */
681591693c7b415e9869157c711fe11263c95d74eDavid Li      if (condition_constant->value.b[0]) {
691591693c7b415e9869157c711fe11263c95d74eDavid Li	 foreach_iter(exec_list_iterator, then_iter, ir->then_instructions) {
701591693c7b415e9869157c711fe11263c95d74eDavid Li	    ir_instruction *then_ir = (ir_instruction *)then_iter.get();
711591693c7b415e9869157c711fe11263c95d74eDavid Li	    ir->insert_before(then_ir);
721591693c7b415e9869157c711fe11263c95d74eDavid Li	 }
731591693c7b415e9869157c711fe11263c95d74eDavid Li      } else {
741591693c7b415e9869157c711fe11263c95d74eDavid Li	 foreach_iter(exec_list_iterator, else_iter, ir->else_instructions) {
751591693c7b415e9869157c711fe11263c95d74eDavid Li	    ir_instruction *else_ir = (ir_instruction *)else_iter.get();
761591693c7b415e9869157c711fe11263c95d74eDavid Li	    ir->insert_before(else_ir);
771591693c7b415e9869157c711fe11263c95d74eDavid Li	 }
781591693c7b415e9869157c711fe11263c95d74eDavid Li      }
791591693c7b415e9869157c711fe11263c95d74eDavid Li      ir->remove();
801591693c7b415e9869157c711fe11263c95d74eDavid Li      this->made_progress = true;
811591693c7b415e9869157c711fe11263c95d74eDavid Li   }
821591693c7b415e9869157c711fe11263c95d74eDavid Li
831591693c7b415e9869157c711fe11263c95d74eDavid Li   return visit_continue;
841591693c7b415e9869157c711fe11263c95d74eDavid Li}
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