lib/Analysis/IntervalPartition.cpp

   1 //===- IntervalPartition.cpp - Interval Partition module code -------------===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // 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/IntervalPartition.h"
  16 #include "llvm/Analysis/Interval.h"
  17 #include "llvm/Analysis/IntervalIterator.h"
  18 #include "llvm/Pass.h"
  19 #include <cassert>
  20 #include <utility>
  21
  22 using namespace llvm;
  23
  24 char IntervalPartition::ID = 0;
  25
  26 INITIALIZE_PASS(IntervalPartition, "intervals",
  27                 "Interval Partition Construction", true, true)
  28
  29 //===----------------------------------------------------------------------===//
  30 // IntervalPartition Implementation
  31 //===----------------------------------------------------------------------===//
  32
  33 // releaseMemory - Reset state back to before function was analyzed
  34 void IntervalPartition::releaseMemory() {
  35   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  36     delete Intervals[i];
  37   IntervalMap.clear();
  38   Intervals.clear();
  39   RootInterval = nullptr;
  40 }
  41
  42 void IntervalPartition::print(raw_ostream &O, const Module*) const {
  43   for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
  44     Intervals[i]->print(O);
  45 }
  46
  47 // addIntervalToPartition - Add an interval to the internal list of intervals,
  48 // and then add mappings from all of the basic blocks in the interval to the
  49 // interval itself (in the IntervalMap).
  50 void IntervalPartition::addIntervalToPartition(Interval *I) {
  51   Intervals.push_back(I);
  52
  53   // Add mappings for all of the basic blocks in I to the IntervalPartition
  54   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
  55        It != End; ++It)
  56     IntervalMap.insert(std::make_pair(*It, I));
  57 }
  58
  59 // updatePredecessors - Interval generation only sets the successor fields of
  60 // the interval data structures.  After interval generation is complete,
  61 // run through all of the intervals and propagate successor info as
  62 // predecessor info.
  63 void IntervalPartition::updatePredecessors(Interval *Int) {
  64   BasicBlock *Header = Int->getHeaderNode();
  65   for (BasicBlock *Successor : Int->Successors)
  66     getBlockInterval(Successor)->Predecessors.push_back(Header);
  67 }
  68
  69 // IntervalPartition ctor - Build the first level interval partition for the
  70 // specified function...
  71 bool IntervalPartition::runOnFunction(Function &F) {
  72   // Pass false to intervals_begin because we take ownership of it's memory
  73   function_interval_iterator I = intervals_begin(&F, false);
  74   assert(I != intervals_end(&F) && "No intervals in function!?!?!");
  75
  76   addIntervalToPartition(RootInterval = *I);
  77
  78   ++I;  // After the first one...
  79
  80   // Add the rest of the intervals to the partition.
  81   for (function_interval_iterator E = intervals_end(&F); I != E; ++I)
  82     addIntervalToPartition(*I);
  83
  84   // Now that we know all of the successor information, propagate this to the
  85   // predecessors for each block.
  86   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  87     updatePredecessors(Intervals[i]);
  88   return false;
  89 }
  90
  91 // IntervalPartition ctor - Build a reduced interval partition from an
  92 // existing interval graph.  This takes an additional boolean parameter to
  93 // distinguish it from a copy constructor.  Always pass in false for now.
  94 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool)
  95   : FunctionPass(ID) {
  96   assert(IP.getRootInterval() && "Cannot operate on empty IntervalPartitions!");
  97
  98   // Pass false to intervals_begin because we take ownership of it's memory
  99   interval_part_interval_iterator I = intervals_begin(IP, false);
 100   assert(I != intervals_end(IP) && "No intervals in interval partition!?!?!");
 101
 102   addIntervalToPartition(RootInterval = *I);
 103
 104   ++I;  // After the first one...
 105
 106   // Add the rest of the intervals to the partition.
 107   for (interval_part_interval_iterator E = intervals_end(IP); I != E; ++I)
 108     addIntervalToPartition(*I);
 109
 110   // Now that we know all of the successor information, propagate this to the
 111   // predecessors for each block.
 112   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
 113     updatePredecessors(Intervals[i]);
 114 }