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, public std::vector<Interval*> {
31 typedef std::map<BasicBlock*, Interval*> IntervalMapTy;
32 IntervalMapTy IntervalMap;
34 typedef std::vector<Interval*> IntervalListTy;
35 Interval *RootInterval;
38 static AnalysisID ID; // We are an analysis, we must have an ID
40 IntervalPartition() : RootInterval(0) {}
42 // run - Calculate the interval partition for this function
43 virtual bool runOnFunction(Function &F);
45 // IntervalPartition ctor - Build a reduced interval partition from an
46 // existing interval graph. This takes an additional boolean parameter to
47 // distinguish it from a copy constructor. Always pass in false for now.
49 IntervalPartition(IntervalPartition &I, bool);
51 // Destructor - Free memory
52 ~IntervalPartition() { destroy(); }
54 // getRootInterval() - Return the root interval that contains the starting
55 // block of the function.
56 inline Interval *getRootInterval() { return RootInterval; }
58 // isDegeneratePartition() - Returns true if the interval partition contains
59 // a single interval, and thus cannot be simplified anymore.
60 bool isDegeneratePartition() { return size() == 1; }
62 // TODO: isIrreducible - look for triangle graph.
64 // getBlockInterval - Return the interval that a basic block exists in.
65 inline Interval *getBlockInterval(BasicBlock *BB) {
66 IntervalMapTy::iterator I = IntervalMap.find(BB);
67 return I != IntervalMap.end() ? I->second : 0;
70 // getAnalysisUsage - Implement the Pass API
71 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
77 // destroy - Reset state back to before function was analyzed
80 // addIntervalToPartition - Add an interval to the internal list of intervals,
81 // and then add mappings from all of the basic blocks in the interval to the
82 // interval itself (in the IntervalMap).
84 void addIntervalToPartition(Interval *I);
86 // updatePredecessors - Interval generation only sets the successor fields of
87 // the interval data structures. After interval generation is complete,
88 // run through all of the intervals and propogate successor info as
91 void updatePredecessors(Interval *Int);