C-Breeze C Compiler Infrastructure [ Project home page]

whilenode.cc Go to the documentation of this file. // $Id: whilenode.cc,v 1.3 2003/08/07 23:13:16 pnav Exp $ // ---------------------------------------------------------------------- // // C-Breeze // C Compiler Framework // // Copyright (c) 2000 University of Texas at Austin // // Samuel Z. Guyer // Daniel A. Jimenez // Calvin Lin // // 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 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 UNIVERSITY OF TEXAS AT // AUSTIN 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. // // We acknowledge the C-to-C Translator from MIT Laboratory for // Computer Science for inspiring parts of the C-Breeze design. // // ---------------------------------------------------------------------- #include "c_breeze.h" // -------------------------------------------------------------------- // Constructors // -------------------------------------------------------------------- whileNode::whileNode(exprNode * cond, stmtNode * body, const Coord coord) : loopNode(While, cond, body, coord) {} // ------------------------------------------------------------ // Walker // ------------------------------------------------------------ void whileNode::visit(Visitor * the_visitor) { the_visitor->at_while(this); } void whileNode::walk(Walker & the_walker) { Walker::Order ord = the_walker.order(); if (ord == Walker::Preorder || ord == Walker::Both) the_walker.at_while(this, Walker::Preorder); if (the_walker.depth() == Walker::Subtree) { // -- Visit the children if (cond()) cond()->walk(the_walker); if (body()) body()->walk(the_walker); } if (ord == Walker::Postorder || ord == Walker::Both) the_walker.at_while(this, Walker::Postorder); } // ------------------------------------------------------------ // Dataflow // ------------------------------------------------------------ void whileNode::dataflow(FlowVal * v, FlowProblem & fp) { if (fp.forward()) { fp.flow_while(v, this, FlowProblem::Entry); // -- Get the values from the previous loop iteration v->meet(at_loop_head()); if (cond()) if (fp.basicblocks()) { fp.flow_basicblock(v, cond(), FlowProblem::Entry); fp.flow_basicblock(v, cond(), FlowProblem::Exit); } else cond()->dataflow(v, fp); // -- Dataflow the loop body (collect break values in at_exit and // continue values in at_loop_tail) FlowVal * bv = v->clone(); if (body()) body()->dataflow(bv, fp); // -- Get the collected continue values bv->meet(at_loop_tail()); // -- Transfer values at the end of the loop to the loop head at_loop_head()->meet_and_diff(bv, fp); delete bv; // -- If there is no condition, then flow cannot go directly from // the cond to the exit. if (! cond()) v->to_top(); // -- Get the collected break values v->meet(at_exit()); fp.flow_while(v, this, FlowProblem::Exit); } else { fp.flow_while(v, this, FlowProblem::Exit); // -- at_exit holds the values need by breaks at_exit()->meet_and_diff(v, fp); // -- Transfer values at loop head to the loop end at_loop_tail()->meet_and_diff(at_loop_head(), fp); // -- Dataflow the body (breaks and continues read values from // at_exit and at_loop_end, respectively). FlowVal * bv = at_loop_tail()->clone(); if (body()) body()->dataflow(bv, fp); // -- If there is no condition, then flow cannot go directly from // the cond to the exit. if (! cond()) v->to_top(); // -- Merge in the loop body values v->meet(bv); delete bv; if (cond()) if (fp.basicblocks()) { fp.flow_basicblock(v, cond(), FlowProblem::Exit); fp.flow_basicblock(v, cond(), FlowProblem::Entry); } else cond()->dataflow(v, fp); // -- Save the values for the next loop iteration at_loop_head()->meet_and_diff(v, fp); fp.flow_while(v, this, FlowProblem::Entry); } } // ------------------------------------------------------------ // Output // ------------------------------------------------------------ void whileNode::output_stmt(output_context & ct, Node * parent) { ct << "while " << '('; if (cond()) cond()->output(ct, this); ct << ')'; ct.space(); if (body()) body()->output(ct, this); else ct << ';'; } // ------------------------------------------------------------ // Changer // ------------------------------------------------------------ Node * whileNode::change(Changer & the_changer, bool redispatch) { Changer::Order ord = the_changer.order(); whileNode * the_while = this; if ((ord == Changer::Preorder || ord == Changer::Both) && ! redispatch) the_while = (whileNode *) the_changer.at_while(the_while, Changer::Preorder); if (the_while) { if (the_while != this) return the_while->change(the_changer, true); exprNode * old_cond = the_while->cond(); if (old_cond) { exprNode * new_cond = (exprNode *) old_cond->change(the_changer); if (old_cond != new_cond) { //if (the_changer.delete_old()) //delete old_cond; the_while->cond(new_cond); } } blockNode * old_body = the_while->body(); if (old_body) { blockNode * new_body = (blockNode *) old_body->change(the_changer); if (old_body != new_body) { //if (the_changer.delete_old()) //delete old_body; the_while->body(new_body); } } } if ((ord == Changer::Postorder || ord == Changer::Both) && ! redispatch) the_while = (whileNode *) the_changer.at_while(the_while, Changer::Postorder); return the_while; } // ------------------------------------------------------------ // Destructor // ------------------------------------------------------------ whileNode::~whileNode() { }

Generated on August 27, 2003
Back to the C-Breeze home page