LLVM  6.0.0svn
IntervalPartition.h
Go to the documentation of this file.
1 //===- IntervalPartition.h - Interval partition Calculation -----*- C++ -*-===//
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 declaration of the IntervalPartition class, which
11 // calculates and represents the interval partition of a function, or a
12 // preexisting interval partition.
13 //
14 // In this way, the interval partition may be used to reduce a flow graph down
15 // to its degenerate single node interval partition (unless it is irreducible).
16 //
17 // TODO: The IntervalPartition class should take a bool parameter that tells
18 // whether it should add the "tails" of an interval to an interval itself or if
19 // they should be represented as distinct intervals.
20 //
21 //===----------------------------------------------------------------------===//
22 
23 #ifndef LLVM_ANALYSIS_INTERVALPARTITION_H
24 #define LLVM_ANALYSIS_INTERVALPARTITION_H
25 
26 #include "llvm/Pass.h"
27 #include <map>
28 #include <vector>
29 
30 namespace llvm {
31 
32 class BasicBlock;
33 class Interval;
34 
35 //===----------------------------------------------------------------------===//
36 //
37 // IntervalPartition - This class builds and holds an "interval partition" for
38 // a function. This partition divides the control flow graph into a set of
39 // maximal intervals, as defined with the properties above. Intuitively, an
40 // interval is a (possibly nonexistent) loop with a "tail" of non-looping
41 // nodes following it.
42 //
44  using IntervalMapTy = std::map<BasicBlock *, Interval *>;
45  IntervalMapTy IntervalMap;
46 
47  using IntervalListTy = std::vector<Interval *>;
48  Interval *RootInterval = nullptr;
49  std::vector<Interval *> Intervals;
50 
51 public:
52  static char ID; // Pass identification, replacement for typeid
53 
56  }
57 
58  // run - Calculate the interval partition for this function
59  bool runOnFunction(Function &F) override;
60 
61  // IntervalPartition ctor - Build a reduced interval partition from an
62  // existing interval graph. This takes an additional boolean parameter to
63  // distinguish it from a copy constructor. Always pass in false for now.
65 
66  // print - Show contents in human readable format...
67  void print(raw_ostream &O, const Module* = nullptr) const override;
68 
69  // getRootInterval() - Return the root interval that contains the starting
70  // block of the function.
71  inline Interval *getRootInterval() { return RootInterval; }
72 
73  // isDegeneratePartition() - Returns true if the interval partition contains
74  // a single interval, and thus cannot be simplified anymore.
75  bool isDegeneratePartition() { return Intervals.size() == 1; }
76 
77  // TODO: isIrreducible - look for triangle graph.
78 
79  // getBlockInterval - Return the interval that a basic block exists in.
81  IntervalMapTy::iterator I = IntervalMap.find(BB);
82  return I != IntervalMap.end() ? I->second : nullptr;
83  }
84 
85  // getAnalysisUsage - Implement the Pass API
86  void getAnalysisUsage(AnalysisUsage &AU) const override {
87  AU.setPreservesAll();
88  }
89 
90  // Interface to Intervals vector...
91  const std::vector<Interval*> &getIntervals() const { return Intervals; }
92 
93  // releaseMemory - Reset state back to before function was analyzed
94  void releaseMemory() override;
95 
96 private:
97  // addIntervalToPartition - Add an interval to the internal list of intervals,
98  // and then add mappings from all of the basic blocks in the interval to the
99  // interval itself (in the IntervalMap).
100  void addIntervalToPartition(Interval *I);
101 
102  // updatePredecessors - Interval generation only sets the successor fields of
103  // the interval data structures. After interval generation is complete,
104  // run through all of the intervals and propagate successor info as
105  // predecessor info.
106  void updatePredecessors(Interval *Int);
107 };
108 
109 } // end namespace llvm
110 
111 #endif // LLVM_ANALYSIS_INTERVALPARTITION_H
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
Various leaf nodes.
Definition: ISDOpcodes.h:60
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:63
Interval Class - An Interval is a set of nodes defined such that every node in the interval has all o...
Definition: Interval.h:37
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
const std::vector< Interval * > & getIntervals() const
std::pair< uint32_t, uint32_t > Interval
#define F(x, y, z)
Definition: MD5.cpp:55
void print(raw_ostream &O, const Module *=nullptr) const override
print - Print out the internal state of the pass.
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
Represent the analysis usage information of a pass.
bool runOnFunction(Function &F) override
runOnFunction - Virtual method overriden by subclasses to do the per-function processing of the pass...
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:298
void initializeIntervalPartitionPass(PassRegistry &)
void setPreservesAll()
Set by analyses that do not transform their input at all.
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - This function should be overriden by passes that need analysis information to do t...
#define I(x, y, z)
Definition: MD5.cpp:58
This class implements an extremely fast bulk output stream that can only output to a stream...
Definition: raw_ostream.h:44
Interval * getBlockInterval(BasicBlock *BB)