1 //===- IntervalPartition.h - Interval partition Calculation -----*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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.
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).
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.
21 //===----------------------------------------------------------------------===//
23 #ifndef LLVM_ANALYSIS_INTERVALPARTITION_H
24 #define LLVM_ANALYSIS_INTERVALPARTITION_H
26 #include "llvm/Pass.h"
35 //===----------------------------------------------------------------------===//
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.
43 class IntervalPartition
: public FunctionPass
{
44 using IntervalMapTy
= std::map
<BasicBlock
*, Interval
*>;
45 IntervalMapTy IntervalMap
;
47 using IntervalListTy
= std::vector
<Interval
*>;
48 Interval
*RootInterval
= nullptr;
49 std::vector
<Interval
*> Intervals
;
52 static char ID
; // Pass identification, replacement for typeid
54 IntervalPartition() : FunctionPass(ID
) {
55 initializeIntervalPartitionPass(*PassRegistry::getPassRegistry());
58 // run - Calculate the interval partition for this function
59 bool runOnFunction(Function
&F
) override
;
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.
64 IntervalPartition(IntervalPartition
&I
, bool);
66 // print - Show contents in human readable format...
67 void print(raw_ostream
&O
, const Module
* = nullptr) const override
;
69 // getRootInterval() - Return the root interval that contains the starting
70 // block of the function.
71 inline Interval
*getRootInterval() { return RootInterval
; }
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; }
77 // TODO: isIrreducible - look for triangle graph.
79 // getBlockInterval - Return the interval that a basic block exists in.
80 inline Interval
*getBlockInterval(BasicBlock
*BB
) {
81 IntervalMapTy::iterator I
= IntervalMap
.find(BB
);
82 return I
!= IntervalMap
.end() ? I
->second
: nullptr;
85 // getAnalysisUsage - Implement the Pass API
86 void getAnalysisUsage(AnalysisUsage
&AU
) const override
{
90 // Interface to Intervals vector...
91 const std::vector
<Interval
*> &getIntervals() const { return Intervals
; }
93 // releaseMemory - Reset state back to before function was analyzed
94 void releaseMemory() override
;
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
);
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
106 void updatePredecessors(Interval
*Int
);
109 } // end namespace llvm
111 #endif // LLVM_ANALYSIS_INTERVALPARTITION_H