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 char IntervalPartition::ID = 0;
  19 static RegisterPass<IntervalPartition>
  20 X("intervals", "Interval Partition Construction", true);
  21
  22 //===----------------------------------------------------------------------===//
  23 // IntervalPartition Implementation
  24 //===----------------------------------------------------------------------===//
  25
  26 // destroy - Reset state back to before function was analyzed
  27 void IntervalPartition::destroy() {
  28   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  29     delete Intervals[i];
  30   IntervalMap.clear();
  31   RootInterval = 0;
  32 }
  33
  34 void IntervalPartition::print(std::ostream &O, const Module*) const {
  35   for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
  36     Intervals[i]->print(O);
  37 }
  38
  39 // addIntervalToPartition - Add an interval to the internal list of intervals,
  40 // and then add mappings from all of the basic blocks in the interval to the
  41 // interval itself (in the IntervalMap).
  42 //
  43 void IntervalPartition::addIntervalToPartition(Interval *I) {
  44   Intervals.push_back(I);
  45
  46   // Add mappings for all of the basic blocks in I to the IntervalPartition
  47   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
  48        It != End; ++It)
  49     IntervalMap.insert(std::make_pair(*It, I));
  50 }
  51
  52 // updatePredecessors - Interval generation only sets the successor fields of
  53 // the interval data structures.  After interval generation is complete,
  54 // run through all of the intervals and propagate successor info as
  55 // predecessor info.
  56 //
  57 void IntervalPartition::updatePredecessors(Interval *Int) {
  58   BasicBlock *Header = Int->getHeaderNode();
  59   for (Interval::succ_iterator I = Int->Successors.begin(),
  60          E = Int->Successors.end(); I != E; ++I)
  61     getBlockInterval(*I)->Predecessors.push_back(Header);
  62 }
  63
  64 // IntervalPartition ctor - Build the first level interval partition for the
  65 // specified function...
  66 //
  67 bool IntervalPartition::runOnFunction(Function &F) {
  68   // Pass false to intervals_begin because we take ownership of it's memory
  69   function_interval_iterator I = intervals_begin(&F, false);
  70   assert(I != intervals_end(&F) && "No intervals in function!?!?!");
  71
  72   addIntervalToPartition(RootInterval = *I);
  73
  74   ++I;  // After the first one...
  75
  76   // Add the rest of the intervals to the partition.
  77   for (function_interval_iterator E = intervals_end(&F); I != E; ++I)
  78     addIntervalToPartition(*I);
  79
  80   // Now that we know all of the successor information, propagate this to the
  81   // predecessors for each block.
  82   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  83     updatePredecessors(Intervals[i]);
  84   return false;
  85 }
  86
  87
  88 // IntervalPartition ctor - Build a reduced interval partition from an
  89 // existing interval graph.  This takes an additional boolean parameter to
  90 // distinguish it from a copy constructor.  Always pass in false for now.
  91 //
  92 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool)
  93   : FunctionPass((intptr_t) &ID) {
  94   Interval *FunctionStart = IP.getRootInterval();
  95   assert(FunctionStart && "Cannot operate on empty IntervalPartitions!");
  96
  97   // Pass false to intervals_begin because we take ownership of it's memory
  98   interval_part_interval_iterator I = intervals_begin(IP, false);
  99   assert(I != intervals_end(IP) && "No intervals in interval partition!?!?!");
 100
 101   addIntervalToPartition(RootInterval = *I);
 102
 103   ++I;  // After the first one...
 104
 105   // Add the rest of the intervals to the partition.
 106   for (interval_part_interval_iterator E = intervals_end(IP); I != E; ++I)
 107     addIntervalToPartition(*I);
 108
 109   // Now that we know all of the successor information, propagate this to the
 110   // predecessors for each block.
 111   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
 112     updatePredecessors(Intervals[i]);
 113 }
 114