1 //===- IntervalPartition.h - Interval partition Calculation ------*- C++ -*--=//
3 // This file contains the declaration of the cfg::IntervalPartition class, which
4 // calculates and represents the interval partition of a method, or a
5 // preexisting interval partition.
7 // In this way, the interval partition may be used to reduce a flow graph down
8 // to its degenerate single node interval partition (unless it is irreducible).
10 // TODO: The IntervalPartition class should take a bool parameter that tells
11 // whether it should add the "tails" of an interval to an interval itself or if
12 // they should be represented as distinct intervals.
14 //===----------------------------------------------------------------------===//
16 #ifndef LLVM_INTERVAL_PARTITION_H
17 #define LLVM_INTERVAL_PARTITION_H
19 #include "llvm/Analysis/Interval.h"
20 #include "llvm/Pass.h"
24 //===----------------------------------------------------------------------===//
26 // IntervalPartition - This class builds and holds an "interval partition" for
27 // a method. This partition divides the control flow graph into a set of
28 // maximal intervals, as defined with the properties above. Intuitively, a
29 // BasicBlock is a (possibly nonexistent) loop with a "tail" of non looping
30 // nodes following it.
32 class IntervalPartition : public MethodPass, public std::vector<Interval*> {
33 typedef std::map<BasicBlock*, Interval*> IntervalMapTy;
34 IntervalMapTy IntervalMap;
36 typedef std::vector<Interval*> IntervalListTy;
37 Interval *RootInterval;
40 static AnalysisID ID; // We are an analysis, we must have an ID
42 IntervalPartition(AnalysisID AID) : RootInterval(0) { assert(AID == ID); }
44 // run - Calculate the interval partition for this method
45 virtual bool runOnMethod(Method *M);
47 // IntervalPartition ctor - Build a reduced interval partition from an
48 // existing interval graph. This takes an additional boolean parameter to
49 // distinguish it from a copy constructor. Always pass in false for now.
51 IntervalPartition(IntervalPartition &I, bool);
53 // Destructor - Free memory
54 ~IntervalPartition() { destroy(); }
56 // getRootInterval() - Return the root interval that contains the starting
57 // block of the method.
58 inline Interval *getRootInterval() { return RootInterval; }
60 // isDegeneratePartition() - Returns true if the interval partition contains
61 // a single interval, and thus cannot be simplified anymore.
62 bool isDegeneratePartition() { return size() == 1; }
64 // TODO: isIrreducible - look for triangle graph.
66 // getBlockInterval - Return the interval that a basic block exists in.
67 inline Interval *getBlockInterval(BasicBlock *BB) {
68 IntervalMapTy::iterator I = IntervalMap.find(BB);
69 return I != IntervalMap.end() ? I->second : 0;
72 // getAnalysisUsageInfo - Implement the Pass API
73 virtual void getAnalysisUsageInfo(AnalysisSet &Required,
74 AnalysisSet &Destroyed,
75 AnalysisSet &Provided) {
76 Provided.push_back(ID);
80 // destroy - Reset state back to before method was analyzed
83 // addIntervalToPartition - Add an interval to the internal list of intervals,
84 // and then add mappings from all of the basic blocks in the interval to the
85 // interval itself (in the IntervalMap).
87 void addIntervalToPartition(Interval *I);
89 // updatePredecessors - Interval generation only sets the successor fields of
90 // the interval data structures. After interval generation is complete,
91 // run through all of the intervals and propogate successor info as
94 void updatePredecessors(Interval *Int);
97 } // End namespace cfg