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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"
16 using namespace llvm;
17 
18 char IntervalPartition::ID = 0;
19 INITIALIZE_PASS(IntervalPartition, "intervals",
20                 "Interval Partition Construction", true, true)
21 
22 //===----------------------------------------------------------------------===//
23 // IntervalPartition Implementation
24 //===----------------------------------------------------------------------===//
25 
26 // releaseMemory - Reset state back to before function was analyzed
releaseMemory()27 void IntervalPartition::releaseMemory() {
28   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
29     delete Intervals[i];
30   IntervalMap.clear();
31   Intervals.clear();
32   RootInterval = nullptr;
33 }
34 
print(raw_ostream & O,const Module *) const35 void IntervalPartition::print(raw_ostream &O, const Module*) const {
36   for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
37     Intervals[i]->print(O);
38 }
39 
40 // addIntervalToPartition - Add an interval to the internal list of intervals,
41 // and then add mappings from all of the basic blocks in the interval to the
42 // interval itself (in the IntervalMap).
43 //
addIntervalToPartition(Interval * I)44 void IntervalPartition::addIntervalToPartition(Interval *I) {
45   Intervals.push_back(I);
46 
47   // Add mappings for all of the basic blocks in I to the IntervalPartition
48   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
49        It != End; ++It)
50     IntervalMap.insert(std::make_pair(*It, I));
51 }
52 
53 // updatePredecessors - Interval generation only sets the successor fields of
54 // the interval data structures.  After interval generation is complete,
55 // run through all of the intervals and propagate successor info as
56 // predecessor info.
57 //
updatePredecessors(Interval * Int)58 void IntervalPartition::updatePredecessors(Interval *Int) {
59   BasicBlock *Header = Int->getHeaderNode();
60   for (BasicBlock *Successor : Int->Successors)
61     getBlockInterval(Successor)->Predecessors.push_back(Header);
62 }
63 
64 // IntervalPartition ctor - Build the first level interval partition for the
65 // specified function...
66 //
runOnFunction(Function & F)67 bool 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 //
IntervalPartition(IntervalPartition & IP,bool)92 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool)
93   : FunctionPass(ID) {
94   assert(IP.getRootInterval() && "Cannot operate on empty IntervalPartitions!");
95 
96   // Pass false to intervals_begin because we take ownership of it's memory
97   interval_part_interval_iterator I = intervals_begin(IP, false);
98   assert(I != intervals_end(IP) && "No intervals in interval partition!?!?!");
99 
100   addIntervalToPartition(RootInterval = *I);
101 
102   ++I;  // After the first one...
103 
104   // Add the rest of the intervals to the partition.
105   for (interval_part_interval_iterator E = intervals_end(IP); I != E; ++I)
106     addIntervalToPartition(*I);
107 
108   // Now that we know all of the successor information, propagate this to the
109   // predecessors for each block.
110   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
111     updatePredecessors(Intervals[i]);
112 }
113 
114