IntervalPartition.cpp revision 360784 
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
22using namespace llvm;
23
24char IntervalPartition::ID = 0;
25
26IntervalPartition::IntervalPartition() : FunctionPass(ID) {
27  initializeIntervalPartitionPass(*PassRegistry::getPassRegistry());
28}
29
30INITIALIZE_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
38void IntervalPartition::releaseMemory() {
39  for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
40    delete Intervals[i];
41  IntervalMap.clear();
42  Intervals.clear();
43  RootInterval = nullptr;
44}
45
46void IntervalPartition::print(raw_ostream &O, const Module*) const {
47  for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
48    Intervals[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).
54void 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.
67void 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...
75bool 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 (unsigned i = 0, e = Intervals.size(); i != e; ++i)
91    updatePredecessors(Intervals[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.
98IntervalPartition::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 (unsigned i = 0, e = Intervals.size(); i != e; ++i)
117    updatePredecessors(Intervals[i]);
118}
119