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C-Breeze C Compiler Infrastructure [ Project home page] |
dataflow.cc
Go to the documentation of this file.00001 // $Id: dataflow.cc,v 1.3 2003/08/07 23:14:11 pnav Exp $ 00002 // ---------------------------------------------------------------------- 00003 // 00004 // C-Breeze 00005 // C Compiler Framework 00006 // 00007 // Copyright (c) 2000 University of Texas at Austin 00008 // 00009 // Samuel Z. Guyer 00010 // Daniel A. Jimenez 00011 // Calvin Lin 00012 // 00013 // Permission is hereby granted, free of charge, to any person 00014 // obtaining a copy of this software and associated documentation 00015 // files (the "Software"), to deal in the Software without 00016 // restriction, including without limitation the rights to use, copy, 00017 // modify, merge, publish, distribute, sublicense, and/or sell copies 00018 // of the Software, and to permit persons to whom the Software is 00019 // furnished to do so, subject to the following conditions: 00020 // 00021 // The above copyright notice and this permission notice shall be 00022 // included in all copies or substantial portions of the Software. 00023 // 00024 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 00025 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 00026 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 00027 // NONINFRINGEMENT. IN NO EVENT SHALL THE UNIVERSITY OF TEXAS AT 00028 // AUSTIN BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 00029 // IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF 00030 // OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 00031 // THE SOFTWARE. 00032 // 00033 // We acknowledge the C-to-C Translator from MIT Laboratory for 00034 // Computer Science for inspiring parts of the C-Breeze design. 00035 // 00036 // ---------------------------------------------------------------------- 00037 00038 #include "c_breeze.h" 00039 #include "init_flowproblem_walker.h" 00040 00041 // ------------------------------------------------------------ 00042 // Main dataflow loop: 00043 // Call this after setting up gen/kill sets. 00044 // ------------------------------------------------------------ 00045 00046 void FlowProblem::iterate(Node * n, FlowVal * initial) 00047 { 00048 // -- Initialize all the confluence points with "top"... 00049 00050 init_flowproblem_walker::init(n, this); 00051 00052 // -- Iterate the dataflow problem until convergence... 00053 00054 if (initial == 0) 00055 initial = top(); 00056 00057 FlowVal * prev = initial->clone(); 00058 bool end_changed; 00059 int i = 0; 00060 00061 do { 00062 00063 // -- Initialize the state... 00064 changed(false); 00065 FlowVal * next = initial->clone(); 00066 00067 // -- Run one pass... 00068 n->dataflow(next, * this); 00069 00070 // -- Compare with previous pass... 00071 end_changed = next->diff(prev); 00072 00073 delete prev; 00074 prev = next; 00075 00076 i++; 00077 // cout << "Iteration " << i << " changed = " << (changed() || end_changed) << endl; 00078 00079 } while (changed() || end_changed); 00080 00081 // -- Last pass: collect the information... 00082 00083 last(true); 00084 FlowVal * next = initial->clone(); 00085 n->dataflow(next, * this); 00086 00087 // -- Clean up the confluence points 00088 00089 init_flowproblem_walker::cleanup(n, this); 00090 } 00091 00092 // ------------------------------------------------------------ 00093 // Meet and diff 00094 // This function is used to keep track of when the system 00095 // converges. 00096 // ------------------------------------------------------------ 00097 00098 void FlowVal::meet_and_diff(const FlowVal * other, FlowProblem & fp) 00099 { 00100 FlowVal * temp = clone(); 00101 00102 meet(other); 00103 00104 if (diff(temp)) 00105 fp.changed(true); 00106 00107 delete temp; 00108 }