lib/Analysis/IntervalPartition.cpp

   1 //===- IntervalPartition.cpp - Interval Partition module code -------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by the LLVM research group and is distributed under
   6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file contains the definition of the IntervalPartition class, which
  11 // calculates and represent the interval partition of a function.
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "llvm/Analysis/IntervalIterator.h"
  16 using namespace llvm;
  17
  18 static RegisterAnalysis<IntervalPartition>
  19 X("intervals", "Interval Partition Construction", true);
  20
  21 //===----------------------------------------------------------------------===//
  22 // IntervalPartition Implementation
  23 //===----------------------------------------------------------------------===//
  24
  25 // destroy - Reset state back to before function was analyzed
  26 void IntervalPartition::destroy() {
  27   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  28     delete Intervals[i];
  29   IntervalMap.clear();
  30   RootInterval = 0;
  31 }
  32
  33 void IntervalPartition::print(std::ostream &O, const Module*) const {
  34   for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
  35     Intervals[i]->print(O);
  36 }
  37
  38 // addIntervalToPartition - Add an interval to the internal list of intervals,
  39 // and then add mappings from all of the basic blocks in the interval to the
  40 // interval itself (in the IntervalMap).
  41 //
  42 void IntervalPartition::addIntervalToPartition(Interval *I) {
  43   Intervals.push_back(I);
  44
  45   // Add mappings for all of the basic blocks in I to the IntervalPartition
  46   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
  47        It != End; ++It)
  48     IntervalMap.insert(std::make_pair(*It, I));
  49 }
  50
  51 // updatePredecessors - Interval generation only sets the successor fields of
  52 // the interval data structures.  After interval generation is complete,
  53 // run through all of the intervals and propagate successor info as
  54 // predecessor info.
  55 //
  56 void IntervalPartition::updatePredecessors(Interval *Int) {
  57   BasicBlock *Header = Int->getHeaderNode();
  58   for (Interval::succ_iterator I = Int->Successors.begin(),
  59          E = Int->Successors.end(); I != E; ++I)
  60     getBlockInterval(*I)->Predecessors.push_back(Header);
  61 }
  62
  63 // IntervalPartition ctor - Build the first level interval partition for the
  64 // specified function...
  65 //
  66 bool IntervalPartition::runOnFunction(Function &F) {
  67   // Pass false to intervals_begin because we take ownership of it's memory
  68   function_interval_iterator I = intervals_begin(&F, false);
  69   assert(I != intervals_end(&F) && "No intervals in function!?!?!");
  70
  71   addIntervalToPartition(RootInterval = *I);
  72
  73   ++I;  // After the first one...
  74
  75   // Add the rest of the intervals to the partition.
  76   for (function_interval_iterator E = intervals_end(&F); I != E; ++I)
  77     addIntervalToPartition(*I);
  78
  79   // Now that we know all of the successor information, propagate this to the
  80   // predecessors for each block.
  81   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  82     updatePredecessors(Intervals[i]);
  83   return false;
  84 }
  85
  86
  87 // IntervalPartition ctor - Build a reduced interval partition from an
  88 // existing interval graph.  This takes an additional boolean parameter to
  89 // distinguish it from a copy constructor.  Always pass in false for now.
  90 //
  91 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool) {
  92   Interval *FunctionStart = IP.getRootInterval();
  93   assert(FunctionStart && "Cannot operate on empty IntervalPartitions!");
  94
  95   // Pass false to intervals_begin because we take ownership of it's memory
  96   interval_part_interval_iterator I = intervals_begin(IP, false);
  97   assert(I != intervals_end(IP) && "No intervals in interval partition!?!?!");
  98
  99   addIntervalToPartition(RootInterval = *I);
 100
 101   ++I;  // After the first one...
 102
 103   // Add the rest of the intervals to the partition.
 104   for (interval_part_interval_iterator E = intervals_end(IP); I != E; ++I)
 105     addIntervalToPartition(*I);
 106
 107   // Now that we know all of the successor information, propagate this to the
 108   // predecessors for each block.
 109   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
 110     updatePredecessors(Intervals[i]);
 111 }
 112