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/IntervalPartition.h"
16 #include "llvm/Analysis/Interval.h"
17 #include "llvm/Analysis/IntervalIterator.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 INITIALIZE_PASS(IntervalPartition, "intervals",
27                 "Interval Partition Construction", true, true)
28 
29 //===----------------------------------------------------------------------===//
30 // IntervalPartition Implementation
31 //===----------------------------------------------------------------------===//
32 
33 // releaseMemory - Reset state back to before function was analyzed
34 void IntervalPartition::releaseMemory() {
35   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
36     delete Intervals[i];
37   IntervalMap.clear();
38   Intervals.clear();
39   RootInterval = nullptr;
40 }
41 
42 void IntervalPartition::print(raw_ostream &O, const Module*) const {
43   for(unsigned i = 0, e = Intervals.size(); i != e; ++i)
44     Intervals[i]->print(O);
45 }
46 
47 // addIntervalToPartition - Add an interval to the internal list of intervals,
48 // and then add mappings from all of the basic blocks in the interval to the
49 // interval itself (in the IntervalMap).
50 void IntervalPartition::addIntervalToPartition(Interval *I) {
51   Intervals.push_back(I);
52 
53   // Add mappings for all of the basic blocks in I to the IntervalPartition
54   for (Interval::node_iterator It = I->Nodes.begin(), End = I->Nodes.end();
55        It != End; ++It)
56     IntervalMap.insert(std::make_pair(*It, I));
57 }
58 
59 // updatePredecessors - Interval generation only sets the successor fields of
60 // the interval data structures.  After interval generation is complete,
61 // run through all of the intervals and propagate successor info as
62 // predecessor info.
63 void IntervalPartition::updatePredecessors(Interval *Int) {
64   BasicBlock *Header = Int->getHeaderNode();
65   for (BasicBlock *Successor : Int->Successors)
66     getBlockInterval(Successor)->Predecessors.push_back(Header);
67 }
68 
69 // IntervalPartition ctor - Build the first level interval partition for the
70 // specified function...
71 bool IntervalPartition::runOnFunction(Function &F) {
72   // Pass false to intervals_begin because we take ownership of it's memory
73   function_interval_iterator I = intervals_begin(&F, false);
74   assert(I != intervals_end(&F) && "No intervals in function!?!?!");
75 
76   addIntervalToPartition(RootInterval = *I);
77 
78   ++I;  // After the first one...
79 
80   // Add the rest of the intervals to the partition.
81   for (function_interval_iterator E = intervals_end(&F); I != E; ++I)
82     addIntervalToPartition(*I);
83 
84   // Now that we know all of the successor information, propagate this to the
85   // predecessors for each block.
86   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
87     updatePredecessors(Intervals[i]);
88   return false;
89 }
90 
91 // IntervalPartition ctor - Build a reduced interval partition from an
92 // existing interval graph.  This takes an additional boolean parameter to
93 // distinguish it from a copy constructor.  Always pass in false for now.
94 IntervalPartition::IntervalPartition(IntervalPartition &IP, bool)
95   : FunctionPass(ID) {
96   assert(IP.getRootInterval() && "Cannot operate on empty IntervalPartitions!");
97 
98   // Pass false to intervals_begin because we take ownership of it's memory
99   interval_part_interval_iterator I = intervals_begin(IP, false);
100   assert(I != intervals_end(IP) && "No intervals in interval partition!?!?!");
101 
102   addIntervalToPartition(RootInterval = *I);
103 
104   ++I;  // After the first one...
105 
106   // Add the rest of the intervals to the partition.
107   for (interval_part_interval_iterator E = intervals_end(IP); I != E; ++I)
108     addIntervalToPartition(*I);
109 
110   // Now that we know all of the successor information, propagate this to the
111   // predecessors for each block.
112   for (unsigned i = 0, e = Intervals.size(); i != e; ++i)
113     updatePredecessors(Intervals[i]);
114 }
115