LLVM  9.0.0svn
IntervalPartition.h
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1 //===- IntervalPartition.h - Interval partition Calculation -----*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file contains the declaration of the IntervalPartition class, which
10 // calculates and represents the interval partition of a function, or a
11 // preexisting interval partition.
12 //
13 // In this way, the interval partition may be used to reduce a flow graph down
14 // to its degenerate single node interval partition (unless it is irreducible).
15 //
16 // TODO: The IntervalPartition class should take a bool parameter that tells
17 // whether it should add the "tails" of an interval to an interval itself or if
18 // they should be represented as distinct intervals.
19 //
20 //===----------------------------------------------------------------------===//
21 
22 #ifndef LLVM_ANALYSIS_INTERVALPARTITION_H
23 #define LLVM_ANALYSIS_INTERVALPARTITION_H
24 
25 #include "llvm/Pass.h"
26 #include <map>
27 #include <vector>
28 
29 namespace llvm {
30 
31 class BasicBlock;
32 class Interval;
33 
34 //===----------------------------------------------------------------------===//
35 //
36 // IntervalPartition - This class builds and holds an "interval partition" for
37 // a function. This partition divides the control flow graph into a set of
38 // maximal intervals, as defined with the properties above. Intuitively, an
39 // interval is a (possibly nonexistent) loop with a "tail" of non-looping
40 // nodes following it.
41 //
43  using IntervalMapTy = std::map<BasicBlock *, Interval *>;
44  IntervalMapTy IntervalMap;
45 
46  using IntervalListTy = std::vector<Interval *>;
47  Interval *RootInterval = nullptr;
48  std::vector<Interval *> Intervals;
49 
50 public:
51  static char ID; // Pass identification, replacement for typeid
52 
55  }
56 
57  // run - Calculate the interval partition for this function
58  bool runOnFunction(Function &F) override;
59 
60  // IntervalPartition ctor - Build a reduced interval partition from an
61  // existing interval graph. This takes an additional boolean parameter to
62  // distinguish it from a copy constructor. Always pass in false for now.
64 
65  // print - Show contents in human readable format...
66  void print(raw_ostream &O, const Module* = nullptr) const override;
67 
68  // getRootInterval() - Return the root interval that contains the starting
69  // block of the function.
70  inline Interval *getRootInterval() { return RootInterval; }
71 
72  // isDegeneratePartition() - Returns true if the interval partition contains
73  // a single interval, and thus cannot be simplified anymore.
74  bool isDegeneratePartition() { return Intervals.size() == 1; }
75 
76  // TODO: isIrreducible - look for triangle graph.
77 
78  // getBlockInterval - Return the interval that a basic block exists in.
80  IntervalMapTy::iterator I = IntervalMap.find(BB);
81  return I != IntervalMap.end() ? I->second : nullptr;
82  }
83 
84  // getAnalysisUsage - Implement the Pass API
85  void getAnalysisUsage(AnalysisUsage &AU) const override {
86  AU.setPreservesAll();
87  }
88 
89  // Interface to Intervals vector...
90  const std::vector<Interval*> &getIntervals() const { return Intervals; }
91 
92  // releaseMemory - Reset state back to before function was analyzed
93  void releaseMemory() override;
94 
95 private:
96  // addIntervalToPartition - Add an interval to the internal list of intervals,
97  // and then add mappings from all of the basic blocks in the interval to the
98  // interval itself (in the IntervalMap).
99  void addIntervalToPartition(Interval *I);
100 
101  // updatePredecessors - Interval generation only sets the successor fields of
102  // the interval data structures. After interval generation is complete,
103  // run through all of the intervals and propagate successor info as
104  // predecessor info.
105  void updatePredecessors(Interval *Int);
106 };
107 
108 } // end namespace llvm
109 
110 #endif // LLVM_ANALYSIS_INTERVALPARTITION_H
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
This class represents lattice values for constants.
Definition: AllocatorList.h:23
Various leaf nodes.
Definition: ISDOpcodes.h:59
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:65
Interval Class - An Interval is a set of nodes defined such that every node in the interval has all o...
Definition: Interval.h:36
void releaseMemory() override
releaseMemory() - This member can be implemented by a pass if it wants to be able to release its memo...
F(f)
const std::vector< Interval * > & getIntervals() const
std::pair< uint32_t, uint32_t > Interval
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:57
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:284
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:45
Interval * getBlockInterval(BasicBlock *BB)