lib/Analysis/IntervalPartition.cpp

   1 //===- IntervalPartition.cpp - Interval Partition module code -------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains the definition of the IntervalPartition class, which
  10 // calculates and represent the interval partition of a function.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "llvm/Analysis/IntervalPartition.h"
  15 #include "llvm/Analysis/Interval.h"
  16 #include "llvm/Analysis/IntervalIterator.h"
  17 #include "llvm/Pass.h"
  18 #include <cassert>
  19 #include <utility>
  20
  21 using namespace llvm;
  22
  23 char IntervalPartition::ID = 0;
  24
  25 INITIALIZE_PASS(IntervalPartition, "intervals",
  26                 "Interval Partition Construction", true, true)
  27
  28 //===----------------------------------------------------------------------===//
  29 // IntervalPartition Implementation
  30 //===----------------------------------------------------------------------===//
  31
  32 // releaseMemory - Reset state back to before function was analyzed
  33 void IntervalPartition::releaseMemory() {
  34   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  35     delete Intervals[i];
  36   IntervalMap.clear();
  37   Intervals.clear();
  38   RootInterval = nullptr;
  39 }
  40
  41 void IntervalPartition::print(raw_ostream &O, const Module*) const {
  42   for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
  43     Intervals[i]->print(O);
  44 }
  45
  46 // addIntervalToPartition - Add an interval to the internal list of intervals,
  47 // and then add mappings from all of the basic blocks in the interval to the
  48 // interval itself (in the IntervalMap).
  49 void IntervalPartition::addIntervalToPartition(Interval *I) {
  50   Intervals.push_back(I);
  51
  52   // Add mappings for all of the basic blocks in I to the IntervalPartition
  53   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
  54        It != End; ++It)
  55     IntervalMap.insert(std::make_pair(*It, I));
  56 }
  57
  58 // updatePredecessors - Interval generation only sets the successor fields of
  59 // the interval data structures.  After interval generation is complete,
  60 // run through all of the intervals and propagate successor info as
  61 // predecessor info.
  62 void IntervalPartition::updatePredecessors(Interval *Int) {
  63   BasicBlock *Header = Int->getHeaderNode();
  64   for (BasicBlock *Successor : Int->Successors)
  65     getBlockInterval(Successor)->Predecessors.push_back(Header);
  66 }
  67
  68 // IntervalPartition ctor - Build the first level interval partition for the
  69 // specified function...
  70 bool IntervalPartition::runOnFunction(Function &F) {
  71   // Pass false to intervals_begin because we take ownership of it's memory
  72   function_interval_iterator I = intervals_begin(&F, false);
  73   assert(I != intervals_end(&F) && "No intervals in function!?!?!");
  74
  75   addIntervalToPartition(RootInterval = *I);
  76
  77   ++I;  // After the first one...
  78
  79   // Add the rest of the intervals to the partition.
  80   for (function_interval_iterator E = intervals_end(&F); I != E; ++I)
  81     addIntervalToPartition(*I);
  82
  83   // Now that we know all of the successor information, propagate this to the
  84   // predecessors for each block.
  85   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
  86     updatePredecessors(Intervals[i]);
  87   return false;
  88 }
  89
  90 // IntervalPartition ctor - Build a reduced interval partition from an
  91 // existing interval graph.  This takes an additional boolean parameter to
  92 // distinguish it from a copy constructor.  Always pass in false for now.
  93 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool)
  94   : FunctionPass(ID) {
  95   assert(IP.getRootInterval() && "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 }