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 IntervalPartition() : RootInterval(0) {}
41 // run - Calculate the interval partition for this function
42 virtual bool runOnFunction(Function &F);
44 // IntervalPartition ctor - Build a reduced interval partition from an
45 // existing interval graph. This takes an additional boolean parameter to
46 // distinguish it from a copy constructor. Always pass in false for now.
48 IntervalPartition(IntervalPartition &I, bool);
50 // Destructor - Free memory
51 ~IntervalPartition() { destroy(); }
53 // print - Show contents in human readable format...
54 virtual void print(std::ostream &O) const;
56 // getRootInterval() - Return the root interval that contains the starting
57 // block of the function.
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 Intervals.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 // getAnalysisUsage - Implement the Pass API
73 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
77 // Interface to Intervals vector...
78 const std::vector<Interval*> &getIntervals() const { return Intervals; }
81 // destroy - Reset state back to before function was analyzed
84 // addIntervalToPartition - Add an interval to the internal list of intervals,
85 // and then add mappings from all of the basic blocks in the interval to the
86 // interval itself (in the IntervalMap).
88 void addIntervalToPartition(Interval *I);
90 // updatePredecessors - Interval generation only sets the successor fields of
91 // the interval data structures. After interval generation is complete,
92 // run through all of the intervals and propagate successor info as
95 void updatePredecessors(Interval *Int);