1 //===- IntervalPartition.h - Interval partition Calculation ------*- C++ -*--=//
3 // This file contains the declaration of the IntervalPartition class, which
4 // calculates and represents the interval partition of a function, 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"
22 //===----------------------------------------------------------------------===//
24 // IntervalPartition - This class builds and holds an "interval partition" for
25 // a function. This partition divides the control flow graph into a set of
26 // maximal intervals, as defined with the properties above. Intuitively, a
27 // BasicBlock is a (possibly nonexistent) loop with a "tail" of non looping
28 // nodes following it.
30 class IntervalPartition : public FunctionPass {
31 typedef std::map<BasicBlock*, Interval*> IntervalMapTy;
32 IntervalMapTy IntervalMap;
34 typedef std::vector<Interval*> IntervalListTy;
35 Interval *RootInterval;
36 std::vector<Interval*> Intervals;
39 static AnalysisID ID; // We are an analysis, we must have an ID
41 IntervalPartition() : RootInterval(0) {}
43 // run - Calculate the interval partition for this function
44 virtual bool runOnFunction(Function &F);
46 // IntervalPartition ctor - Build a reduced interval partition from an
47 // existing interval graph. This takes an additional boolean parameter to
48 // distinguish it from a copy constructor. Always pass in false for now.
50 IntervalPartition(IntervalPartition &I, bool);
52 // Destructor - Free memory
53 ~IntervalPartition() { destroy(); }
55 // print - Show contents in human readable format...
56 virtual void print(std::ostream &O) const;
58 // getRootInterval() - Return the root interval that contains the starting
59 // block of the function.
60 inline Interval *getRootInterval() { return RootInterval; }
62 // isDegeneratePartition() - Returns true if the interval partition contains
63 // a single interval, and thus cannot be simplified anymore.
64 bool isDegeneratePartition() { return Intervals.size() == 1; }
66 // TODO: isIrreducible - look for triangle graph.
68 // getBlockInterval - Return the interval that a basic block exists in.
69 inline Interval *getBlockInterval(BasicBlock *BB) {
70 IntervalMapTy::iterator I = IntervalMap.find(BB);
71 return I != IntervalMap.end() ? I->second : 0;
74 // getAnalysisUsage - Implement the Pass API
75 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
79 // Interface to Intervals vector...
80 const std::vector<Interval*> &getIntervals() const { return Intervals; }
83 // destroy - Reset state back to before function was analyzed
86 // addIntervalToPartition - Add an interval to the internal list of intervals,
87 // and then add mappings from all of the basic blocks in the interval to the
88 // interval itself (in the IntervalMap).
90 void addIntervalToPartition(Interval *I);
92 // updatePredecessors - Interval generation only sets the successor fields of
93 // the interval data structures. After interval generation is complete,
94 // run through all of the intervals and propogate successor info as
97 void updatePredecessors(Interval *Int);