llvm/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/InitializePasses.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 IntervalPartition::IntervalPartition() : FunctionPass(ID) {
  27   initializeIntervalPartitionPass(*PassRegistry::getPassRegistry());
  28 }
  29
  30 INITIALIZE_PASS(IntervalPartition, "intervals",
  31                 "Interval Partition Construction", true, true)
  32
  33 //===----------------------------------------------------------------------===//
  34 // IntervalPartition Implementation
  35 //===----------------------------------------------------------------------===//
  36
  37 // releaseMemory - Reset state back to before function was analyzed
  38 void IntervalPartition::releaseMemory() {
  39   for (Interval *I : Intervals)
  40     delete I;
  41   IntervalMap.clear();
  42   Intervals.clear();
  43   RootInterval = nullptr;
  44 }
  45
  46 void IntervalPartition::print(raw_ostream &O, const Module*) const {
  47   for (const Interval *I : Intervals)
  48     I->print(O);
  49 }
  50
  51 // addIntervalToPartition - Add an interval to the internal list of intervals,
  52 // and then add mappings from all of the basic blocks in the interval to the
  53 // interval itself (in the IntervalMap).
  54 void IntervalPartition::addIntervalToPartition(Interval *I) {
  55   Intervals.push_back(I);
  56
  57   // Add mappings for all of the basic blocks in I to the IntervalPartition
  58   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
  59        It != End; ++It)
  60     IntervalMap.insert(std::make_pair(*It, I));
  61 }
  62
  63 // updatePredecessors - Interval generation only sets the successor fields of
  64 // the interval data structures.  After interval generation is complete,
  65 // run through all of the intervals and propagate successor info as
  66 // predecessor info.
  67 void IntervalPartition::updatePredecessors(Interval *Int) {
  68   BasicBlock *Header = Int->getHeaderNode();
  69   for (BasicBlock *Successor : Int->Successors)
  70     getBlockInterval(Successor)->Predecessors.push_back(Header);
  71 }
  72
  73 // IntervalPartition ctor - Build the first level interval partition for the
  74 // specified function...
  75 bool IntervalPartition::runOnFunction(Function &F) {
  76   // Pass false to intervals_begin because we take ownership of it's memory
  77   function_interval_iterator I = intervals_begin(&F, false);
  78   assert(I != intervals_end(&F) && "No intervals in function!?!?!");
  79
  80   addIntervalToPartition(RootInterval = *I);
  81
  82   ++I;  // After the first one...
  83
  84   // Add the rest of the intervals to the partition.
  85   for (function_interval_iterator E = intervals_end(&F); I != E; ++I)
  86     addIntervalToPartition(*I);
  87
  88   // Now that we know all of the successor information, propagate this to the
  89   // predecessors for each block.
  90   for (Interval *I : Intervals)
  91     updatePredecessors(I);
  92   return false;
  93 }
  94
  95 // IntervalPartition ctor - Build a reduced interval partition from an
  96 // existing interval graph.  This takes an additional boolean parameter to
  97 // distinguish it from a copy constructor.  Always pass in false for now.
  98 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool)
  99   : FunctionPass(ID) {
 100   assert(IP.getRootInterval() && "Cannot operate on empty IntervalPartitions!");
 101
 102   // Pass false to intervals_begin because we take ownership of it's memory
 103   interval_part_interval_iterator I = intervals_begin(IP, false);
 104   assert(I != intervals_end(IP) && "No intervals in interval partition!?!?!");
 105
 106   addIntervalToPartition(RootInterval = *I);
 107
 108   ++I;  // After the first one...
 109
 110   // Add the rest of the intervals to the partition.
 111   for (interval_part_interval_iterator E = intervals_end(IP); I != E; ++I)
 112     addIntervalToPartition(*I);
 113
 114   // Now that we know all of the successor information, propagate this to the
 115   // predecessors for each block.
 116   for (Interval *I : Intervals)
 117     updatePredecessors(I);
 118 }