IntervalPartition.cpp revision 3aab76e3790476cc00f04706e7c6d71fcf2e92a1 
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/IntervalIterator.h"
16using namespace llvm;
17
18char IntervalPartition::ID = 0;
19static RegisterPass<IntervalPartition>
20X("intervals", "Interval Partition Construction", true, true);
21
22//===----------------------------------------------------------------------===//
23// IntervalPartition Implementation
24//===----------------------------------------------------------------------===//
25
26// destroy - Reset state back to before function was analyzed
27void 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
34void 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//
43void 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//
57void 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//
67bool 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//
92IntervalPartition::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
115