1 //===- IntervalPartition.cpp - Interval Partition module code -------------===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source 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 const int IntervalPartition::ID = 0;
19 static RegisterPass<IntervalPartition>
20 X("intervals", "Interval Partition Construction", true);
21 
22 //===----------------------------------------------------------------------===//
23 // IntervalPartition Implementation
24 //===----------------------------------------------------------------------===//
25 
26 // destroy - Reset state back to before function was analyzed
27 void 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 
34 void 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 //
43 void 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 //
57 void 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 //
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 //
92 IntervalPartition::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