llvm-6502/include/llvm/Analysis/PathNumbering.h
Andrew Trick 04317cc618 Implementation of path profiling.
Modified patch by Adam Preuss.

This builds on the existing framework for block tracing, edge profiling and optimal edge profiling.
See -help-hidden for new flags.
For documentation, see the technical report "Implementation of Path Profiling..." in llvm.org/pubs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124515 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-29 01:09:53 +00:00

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9.9 KiB
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//===- PathNumbering.h ----------------------------------------*- C++ -*---===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Ball-Larus path numbers uniquely identify paths through a directed acyclic
// graph (DAG) [Ball96]. For a CFG backedges are removed and replaced by phony
// edges to obtain a DAG, and thus the unique path numbers [Ball96].
//
// The purpose of this analysis is to enumerate the edges in a CFG in order
// to obtain paths from path numbers in a convenient manner. As described in
// [Ball96] edges can be enumerated such that given a path number by following
// the CFG and updating the path number, the path is obtained.
//
// [Ball96]
// T. Ball and J. R. Larus. "Efficient Path Profiling."
// International Symposium on Microarchitecture, pages 46-57, 1996.
// http://portal.acm.org/citation.cfm?id=243857
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_PATH_NUMBERING_H
#define LLVM_PATH_NUMBERING_H
#include "llvm/BasicBlock.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
#include "llvm/Support/CFG.h"
#include "llvm/Analysis/ProfileInfoTypes.h"
#include <map>
#include <stack>
#include <vector>
namespace llvm {
class BallLarusNode;
class BallLarusEdge;
class BallLarusDag;
// typedefs for storage/ interators of various DAG components
typedef std::vector<BallLarusNode*> BLNodeVector;
typedef std::vector<BallLarusNode*>::iterator BLNodeIterator;
typedef std::vector<BallLarusEdge*> BLEdgeVector;
typedef std::vector<BallLarusEdge*>::iterator BLEdgeIterator;
typedef std::map<BasicBlock*, BallLarusNode*> BLBlockNodeMap;
typedef std::stack<BallLarusNode*> BLNodeStack;
// Represents a basic block with information necessary for the BallLarus
// algorithms.
class BallLarusNode {
public:
enum NodeColor { WHITE, GRAY, BLACK };
// Constructor: Initializes a new Node for the given BasicBlock
BallLarusNode(BasicBlock* BB) :
_basicBlock(BB), _numberPaths(0), _color(WHITE) {
static unsigned nextUID = 0;
_uid = nextUID++;
}
// Returns the basic block for the BallLarusNode
BasicBlock* getBlock();
// Get/set the number of paths to the exit starting at the node.
unsigned getNumberPaths();
void setNumberPaths(unsigned numberPaths);
// Get/set the NodeColor used in graph algorithms.
NodeColor getColor();
void setColor(NodeColor color);
// Iterator information for predecessor edges. Includes phony and
// backedges.
BLEdgeIterator predBegin();
BLEdgeIterator predEnd();
unsigned getNumberPredEdges();
// Iterator information for successor edges. Includes phony and
// backedges.
BLEdgeIterator succBegin();
BLEdgeIterator succEnd();
unsigned getNumberSuccEdges();
// Add an edge to the predecessor list.
void addPredEdge(BallLarusEdge* edge);
// Remove an edge from the predecessor list.
void removePredEdge(BallLarusEdge* edge);
// Add an edge to the successor list.
void addSuccEdge(BallLarusEdge* edge);
// Remove an edge from the successor list.
void removeSuccEdge(BallLarusEdge* edge);
// Returns the name of the BasicBlock being represented. If BasicBlock
// is null then returns "<null>". If BasicBlock has no name, then
// "<unnamed>" is returned. Intended for use with debug output.
std::string getName();
private:
// The corresponding underlying BB.
BasicBlock* _basicBlock;
// Holds the predecessor edges of this node.
BLEdgeVector _predEdges;
// Holds the successor edges of this node.
BLEdgeVector _succEdges;
// The number of paths from the node to the exit.
unsigned _numberPaths;
// 'Color' used by graph algorithms to mark the node.
NodeColor _color;
// Unique ID to ensure naming difference with dotgraphs
unsigned _uid;
// Removes an edge from an edgeVector. Used by removePredEdge and
// removeSuccEdge.
void removeEdge(BLEdgeVector& v, BallLarusEdge* e);
};
// Represents an edge in the Dag. For an edge, v -> w, v is the source, and
// w is the target.
class BallLarusEdge {
public:
enum EdgeType { NORMAL, BACKEDGE, SPLITEDGE,
BACKEDGE_PHONY, SPLITEDGE_PHONY, CALLEDGE_PHONY };
// Constructor: Initializes an BallLarusEdge with a source and target.
BallLarusEdge(BallLarusNode* source, BallLarusNode* target,
unsigned duplicateNumber)
: _source(source), _target(target), _weight(0), _edgeType(NORMAL),
_realEdge(NULL), _duplicateNumber(duplicateNumber) {}
// Returns the source/ target node of this edge.
BallLarusNode* getSource() const;
BallLarusNode* getTarget() const;
// Sets the type of the edge.
EdgeType getType() const;
// Gets the type of the edge.
void setType(EdgeType type);
// Returns the weight of this edge. Used to decode path numbers to
// sequences of basic blocks.
unsigned getWeight();
// Sets the weight of the edge. Used during path numbering.
void setWeight(unsigned weight);
// Gets/sets the phony edge originating at the root.
BallLarusEdge* getPhonyRoot();
void setPhonyRoot(BallLarusEdge* phonyRoot);
// Gets/sets the phony edge terminating at the exit.
BallLarusEdge* getPhonyExit();
void setPhonyExit(BallLarusEdge* phonyExit);
// Gets/sets the associated real edge if this is a phony edge.
BallLarusEdge* getRealEdge();
void setRealEdge(BallLarusEdge* realEdge);
// Returns the duplicate number of the edge.
unsigned getDuplicateNumber();
protected:
// Source node for this edge.
BallLarusNode* _source;
// Target node for this edge.
BallLarusNode* _target;
private:
// Edge weight cooresponding to path number increments before removing
// increments along a spanning tree. The sum over the edge weights gives
// the path number.
unsigned _weight;
// Type to represent for what this edge is intended
EdgeType _edgeType;
// For backedges and split-edges, the phony edge which is linked to the
// root node of the DAG. This contains a path number initialization.
BallLarusEdge* _phonyRoot;
// For backedges and split-edges, the phony edge which is linked to the
// exit node of the DAG. This contains a path counter increment, and
// potentially a path number increment.
BallLarusEdge* _phonyExit;
// If this is a phony edge, _realEdge is a link to the back or split
// edge. Otherwise, this is null.
BallLarusEdge* _realEdge;
// An ID to differentiate between those edges which have the same source
// and destination blocks.
unsigned _duplicateNumber;
};
// Represents the Ball Larus DAG for a given Function. Can calculate
// various properties required for instrumentation or analysis. E.g. the
// edge weights that determine the path number.
class BallLarusDag {
public:
// Initializes a BallLarusDag from the CFG of a given function. Must
// call init() after creation, since some initialization requires
// virtual functions.
BallLarusDag(Function &F)
: _root(NULL), _exit(NULL), _function(F) {}
// Initialization that requires virtual functions which are not fully
// functional in the constructor.
void init();
// Frees all memory associated with the DAG.
virtual ~BallLarusDag();
// Calculate the path numbers by assigning edge increments as prescribed
// in Ball-Larus path profiling.
void calculatePathNumbers();
// Returns the number of paths for the DAG.
unsigned getNumberOfPaths();
// Returns the root (i.e. entry) node for the DAG.
BallLarusNode* getRoot();
// Returns the exit node for the DAG.
BallLarusNode* getExit();
// Returns the function for the DAG.
Function& getFunction();
// Clears the node colors.
void clearColors(BallLarusNode::NodeColor color);
protected:
// All nodes in the DAG.
BLNodeVector _nodes;
// All edges in the DAG.
BLEdgeVector _edges;
// All backedges in the DAG.
BLEdgeVector _backEdges;
// Allows subclasses to determine which type of Node is created.
// Override this method to produce subclasses of BallLarusNode if
// necessary. The destructor of BallLarusDag will call free on each pointer
// created.
virtual BallLarusNode* createNode(BasicBlock* BB);
// Allows subclasses to determine which type of Edge is created.
// Override this method to produce subclasses of BallLarusEdge if
// necessary. Parameters source and target will have been created by
// createNode and can be cast to the subclass of BallLarusNode*
// returned by createNode. The destructor of BallLarusDag will call free
// on each pointer created.
virtual BallLarusEdge* createEdge(BallLarusNode* source, BallLarusNode*
target, unsigned duplicateNumber);
// Proxy to node's constructor. Updates the DAG state.
BallLarusNode* addNode(BasicBlock* BB);
// Proxy to edge's constructor. Updates the DAG state.
BallLarusEdge* addEdge(BallLarusNode* source, BallLarusNode* target,
unsigned duplicateNumber);
private:
// The root (i.e. entry) node for this DAG.
BallLarusNode* _root;
// The exit node for this DAG.
BallLarusNode* _exit;
// The function represented by this DAG.
Function& _function;
// Processes one node and its imediate edges for building the DAG.
void buildNode(BLBlockNodeMap& inDag, std::stack<BallLarusNode*>& dfsStack);
// Process an edge in the CFG for DAG building.
void buildEdge(BLBlockNodeMap& inDag, std::stack<BallLarusNode*>& dfsStack,
BallLarusNode* currentNode, BasicBlock* succBB,
unsigned duplicateNumber);
// The weight on each edge is the increment required along any path that
// contains that edge.
void calculatePathNumbersFrom(BallLarusNode* node);
// Adds a backedge with its phony edges. Updates the DAG state.
void addBackedge(BallLarusNode* source, BallLarusNode* target,
unsigned duplicateCount);
};
} // end namespace llvm
#endif