mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2024-08-18 12:29:21 +00:00
Patch by Curtis Dunham. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47959 91177308-0d34-0410-b5e6-96231b3b80d8
2827 lines
100 KiB
C++
2827 lines
100 KiB
C++
//===- Andersens.cpp - Andersen's Interprocedural Alias Analysis ----------===//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file defines an implementation of Andersen's interprocedural alias
|
|
// analysis
|
|
//
|
|
// In pointer analysis terms, this is a subset-based, flow-insensitive,
|
|
// field-sensitive, and context-insensitive algorithm pointer algorithm.
|
|
//
|
|
// This algorithm is implemented as three stages:
|
|
// 1. Object identification.
|
|
// 2. Inclusion constraint identification.
|
|
// 3. Offline constraint graph optimization
|
|
// 4. Inclusion constraint solving.
|
|
//
|
|
// The object identification stage identifies all of the memory objects in the
|
|
// program, which includes globals, heap allocated objects, and stack allocated
|
|
// objects.
|
|
//
|
|
// The inclusion constraint identification stage finds all inclusion constraints
|
|
// in the program by scanning the program, looking for pointer assignments and
|
|
// other statements that effect the points-to graph. For a statement like "A =
|
|
// B", this statement is processed to indicate that A can point to anything that
|
|
// B can point to. Constraints can handle copies, loads, and stores, and
|
|
// address taking.
|
|
//
|
|
// The offline constraint graph optimization portion includes offline variable
|
|
// substitution algorithms intended to compute pointer and location
|
|
// equivalences. Pointer equivalences are those pointers that will have the
|
|
// same points-to sets, and location equivalences are those variables that
|
|
// always appear together in points-to sets. It also includes an offline
|
|
// cycle detection algorithm that allows cycles to be collapsed sooner
|
|
// during solving.
|
|
//
|
|
// The inclusion constraint solving phase iteratively propagates the inclusion
|
|
// constraints until a fixed point is reached. This is an O(N^3) algorithm.
|
|
//
|
|
// Function constraints are handled as if they were structs with X fields.
|
|
// Thus, an access to argument X of function Y is an access to node index
|
|
// getNode(Y) + X. This representation allows handling of indirect calls
|
|
// without any issues. To wit, an indirect call Y(a,b) is equivalent to
|
|
// *(Y + 1) = a, *(Y + 2) = b.
|
|
// The return node for a function is always located at getNode(F) +
|
|
// CallReturnPos. The arguments start at getNode(F) + CallArgPos.
|
|
//
|
|
// Future Improvements:
|
|
// Use of BDD's.
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#define DEBUG_TYPE "anders-aa"
|
|
#include "llvm/Constants.h"
|
|
#include "llvm/DerivedTypes.h"
|
|
#include "llvm/Instructions.h"
|
|
#include "llvm/Module.h"
|
|
#include "llvm/Pass.h"
|
|
#include "llvm/Support/Compiler.h"
|
|
#include "llvm/Support/InstIterator.h"
|
|
#include "llvm/Support/InstVisitor.h"
|
|
#include "llvm/Analysis/AliasAnalysis.h"
|
|
#include "llvm/Analysis/Passes.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/ADT/Statistic.h"
|
|
#include "llvm/ADT/SparseBitVector.h"
|
|
#include "llvm/ADT/DenseSet.h"
|
|
#include <algorithm>
|
|
#include <set>
|
|
#include <list>
|
|
#include <stack>
|
|
#include <vector>
|
|
#include <queue>
|
|
|
|
// Determining the actual set of nodes the universal set can consist of is very
|
|
// expensive because it means propagating around very large sets. We rely on
|
|
// other analysis being able to determine which nodes can never be pointed to in
|
|
// order to disambiguate further than "points-to anything".
|
|
#define FULL_UNIVERSAL 0
|
|
|
|
using namespace llvm;
|
|
STATISTIC(NumIters , "Number of iterations to reach convergence");
|
|
STATISTIC(NumConstraints, "Number of constraints");
|
|
STATISTIC(NumNodes , "Number of nodes");
|
|
STATISTIC(NumUnified , "Number of variables unified");
|
|
STATISTIC(NumErased , "Number of redundant constraints erased");
|
|
|
|
namespace {
|
|
const unsigned SelfRep = (unsigned)-1;
|
|
const unsigned Unvisited = (unsigned)-1;
|
|
// Position of the function return node relative to the function node.
|
|
const unsigned CallReturnPos = 1;
|
|
// Position of the function call node relative to the function node.
|
|
const unsigned CallFirstArgPos = 2;
|
|
|
|
struct BitmapKeyInfo {
|
|
static inline SparseBitVector<> *getEmptyKey() {
|
|
return reinterpret_cast<SparseBitVector<> *>(-1);
|
|
}
|
|
static inline SparseBitVector<> *getTombstoneKey() {
|
|
return reinterpret_cast<SparseBitVector<> *>(-2);
|
|
}
|
|
static unsigned getHashValue(const SparseBitVector<> *bitmap) {
|
|
return bitmap->getHashValue();
|
|
}
|
|
static bool isEqual(const SparseBitVector<> *LHS,
|
|
const SparseBitVector<> *RHS) {
|
|
if (LHS == RHS)
|
|
return true;
|
|
else if (LHS == getEmptyKey() || RHS == getEmptyKey()
|
|
|| LHS == getTombstoneKey() || RHS == getTombstoneKey())
|
|
return false;
|
|
|
|
return *LHS == *RHS;
|
|
}
|
|
|
|
static bool isPod() { return true; }
|
|
};
|
|
|
|
class VISIBILITY_HIDDEN Andersens : public ModulePass, public AliasAnalysis,
|
|
private InstVisitor<Andersens> {
|
|
struct Node;
|
|
|
|
/// Constraint - Objects of this structure are used to represent the various
|
|
/// constraints identified by the algorithm. The constraints are 'copy',
|
|
/// for statements like "A = B", 'load' for statements like "A = *B",
|
|
/// 'store' for statements like "*A = B", and AddressOf for statements like
|
|
/// A = alloca; The Offset is applied as *(A + K) = B for stores,
|
|
/// A = *(B + K) for loads, and A = B + K for copies. It is
|
|
/// illegal on addressof constraints (because it is statically
|
|
/// resolvable to A = &C where C = B + K)
|
|
|
|
struct Constraint {
|
|
enum ConstraintType { Copy, Load, Store, AddressOf } Type;
|
|
unsigned Dest;
|
|
unsigned Src;
|
|
unsigned Offset;
|
|
|
|
Constraint(ConstraintType Ty, unsigned D, unsigned S, unsigned O = 0)
|
|
: Type(Ty), Dest(D), Src(S), Offset(O) {
|
|
assert((Offset == 0 || Ty != AddressOf) &&
|
|
"Offset is illegal on addressof constraints");
|
|
}
|
|
|
|
bool operator==(const Constraint &RHS) const {
|
|
return RHS.Type == Type
|
|
&& RHS.Dest == Dest
|
|
&& RHS.Src == Src
|
|
&& RHS.Offset == Offset;
|
|
}
|
|
|
|
bool operator!=(const Constraint &RHS) const {
|
|
return !(*this == RHS);
|
|
}
|
|
|
|
bool operator<(const Constraint &RHS) const {
|
|
if (RHS.Type != Type)
|
|
return RHS.Type < Type;
|
|
else if (RHS.Dest != Dest)
|
|
return RHS.Dest < Dest;
|
|
else if (RHS.Src != Src)
|
|
return RHS.Src < Src;
|
|
return RHS.Offset < Offset;
|
|
}
|
|
};
|
|
|
|
// Information DenseSet requires implemented in order to be able to do
|
|
// it's thing
|
|
struct PairKeyInfo {
|
|
static inline std::pair<unsigned, unsigned> getEmptyKey() {
|
|
return std::make_pair(~0UL, ~0UL);
|
|
}
|
|
static inline std::pair<unsigned, unsigned> getTombstoneKey() {
|
|
return std::make_pair(~0UL - 1, ~0UL - 1);
|
|
}
|
|
static unsigned getHashValue(const std::pair<unsigned, unsigned> &P) {
|
|
return P.first ^ P.second;
|
|
}
|
|
static unsigned isEqual(const std::pair<unsigned, unsigned> &LHS,
|
|
const std::pair<unsigned, unsigned> &RHS) {
|
|
return LHS == RHS;
|
|
}
|
|
};
|
|
|
|
struct ConstraintKeyInfo {
|
|
static inline Constraint getEmptyKey() {
|
|
return Constraint(Constraint::Copy, ~0UL, ~0UL, ~0UL);
|
|
}
|
|
static inline Constraint getTombstoneKey() {
|
|
return Constraint(Constraint::Copy, ~0UL - 1, ~0UL - 1, ~0UL - 1);
|
|
}
|
|
static unsigned getHashValue(const Constraint &C) {
|
|
return C.Src ^ C.Dest ^ C.Type ^ C.Offset;
|
|
}
|
|
static bool isEqual(const Constraint &LHS,
|
|
const Constraint &RHS) {
|
|
return LHS.Type == RHS.Type && LHS.Dest == RHS.Dest
|
|
&& LHS.Src == RHS.Src && LHS.Offset == RHS.Offset;
|
|
}
|
|
};
|
|
|
|
// Node class - This class is used to represent a node in the constraint
|
|
// graph. Due to various optimizations, it is not always the case that
|
|
// there is a mapping from a Node to a Value. In particular, we add
|
|
// artificial Node's that represent the set of pointed-to variables shared
|
|
// for each location equivalent Node.
|
|
struct Node {
|
|
private:
|
|
static unsigned Counter;
|
|
|
|
public:
|
|
Value *Val;
|
|
SparseBitVector<> *Edges;
|
|
SparseBitVector<> *PointsTo;
|
|
SparseBitVector<> *OldPointsTo;
|
|
std::list<Constraint> Constraints;
|
|
|
|
// Pointer and location equivalence labels
|
|
unsigned PointerEquivLabel;
|
|
unsigned LocationEquivLabel;
|
|
// Predecessor edges, both real and implicit
|
|
SparseBitVector<> *PredEdges;
|
|
SparseBitVector<> *ImplicitPredEdges;
|
|
// Set of nodes that point to us, only use for location equivalence.
|
|
SparseBitVector<> *PointedToBy;
|
|
// Number of incoming edges, used during variable substitution to early
|
|
// free the points-to sets
|
|
unsigned NumInEdges;
|
|
// True if our points-to set is in the Set2PEClass map
|
|
bool StoredInHash;
|
|
// True if our node has no indirect constraints (complex or otherwise)
|
|
bool Direct;
|
|
// True if the node is address taken, *or* it is part of a group of nodes
|
|
// that must be kept together. This is set to true for functions and
|
|
// their arg nodes, which must be kept at the same position relative to
|
|
// their base function node.
|
|
bool AddressTaken;
|
|
|
|
// Nodes in cycles (or in equivalence classes) are united together using a
|
|
// standard union-find representation with path compression. NodeRep
|
|
// gives the index into GraphNodes for the representative Node.
|
|
unsigned NodeRep;
|
|
|
|
// Modification timestamp. Assigned from Counter.
|
|
// Used for work list prioritization.
|
|
unsigned Timestamp;
|
|
|
|
explicit Node(bool direct = true) :
|
|
Val(0), Edges(0), PointsTo(0), OldPointsTo(0),
|
|
PointerEquivLabel(0), LocationEquivLabel(0), PredEdges(0),
|
|
ImplicitPredEdges(0), PointedToBy(0), NumInEdges(0),
|
|
StoredInHash(false), Direct(direct), AddressTaken(false),
|
|
NodeRep(SelfRep), Timestamp(0) { }
|
|
|
|
Node *setValue(Value *V) {
|
|
assert(Val == 0 && "Value already set for this node!");
|
|
Val = V;
|
|
return this;
|
|
}
|
|
|
|
/// getValue - Return the LLVM value corresponding to this node.
|
|
///
|
|
Value *getValue() const { return Val; }
|
|
|
|
/// addPointerTo - Add a pointer to the list of pointees of this node,
|
|
/// returning true if this caused a new pointer to be added, or false if
|
|
/// we already knew about the points-to relation.
|
|
bool addPointerTo(unsigned Node) {
|
|
return PointsTo->test_and_set(Node);
|
|
}
|
|
|
|
/// intersects - Return true if the points-to set of this node intersects
|
|
/// with the points-to set of the specified node.
|
|
bool intersects(Node *N) const;
|
|
|
|
/// intersectsIgnoring - Return true if the points-to set of this node
|
|
/// intersects with the points-to set of the specified node on any nodes
|
|
/// except for the specified node to ignore.
|
|
bool intersectsIgnoring(Node *N, unsigned) const;
|
|
|
|
// Timestamp a node (used for work list prioritization)
|
|
void Stamp() {
|
|
Timestamp = Counter++;
|
|
}
|
|
|
|
bool isRep() {
|
|
return( (int) NodeRep < 0 );
|
|
}
|
|
};
|
|
|
|
struct WorkListElement {
|
|
Node* node;
|
|
unsigned Timestamp;
|
|
WorkListElement(Node* n, unsigned t) : node(n), Timestamp(t) {}
|
|
|
|
// Note that we reverse the sense of the comparison because we
|
|
// actually want to give low timestamps the priority over high,
|
|
// whereas priority is typically interpreted as a greater value is
|
|
// given high priority.
|
|
bool operator<(const WorkListElement& that) const {
|
|
return( this->Timestamp > that.Timestamp );
|
|
}
|
|
};
|
|
|
|
// Priority-queue based work list specialized for Nodes.
|
|
class WorkList {
|
|
std::priority_queue<WorkListElement> Q;
|
|
|
|
public:
|
|
void insert(Node* n) {
|
|
Q.push( WorkListElement(n, n->Timestamp) );
|
|
}
|
|
|
|
// We automatically discard non-representative nodes and nodes
|
|
// that were in the work list twice (we keep a copy of the
|
|
// timestamp in the work list so we can detect this situation by
|
|
// comparing against the node's current timestamp).
|
|
Node* pop() {
|
|
while( !Q.empty() ) {
|
|
WorkListElement x = Q.top(); Q.pop();
|
|
Node* INode = x.node;
|
|
|
|
if( INode->isRep() &&
|
|
INode->Timestamp == x.Timestamp ) {
|
|
return(x.node);
|
|
}
|
|
}
|
|
return(0);
|
|
}
|
|
|
|
bool empty() {
|
|
return Q.empty();
|
|
}
|
|
};
|
|
|
|
/// GraphNodes - This vector is populated as part of the object
|
|
/// identification stage of the analysis, which populates this vector with a
|
|
/// node for each memory object and fills in the ValueNodes map.
|
|
std::vector<Node> GraphNodes;
|
|
|
|
/// ValueNodes - This map indicates the Node that a particular Value* is
|
|
/// represented by. This contains entries for all pointers.
|
|
DenseMap<Value*, unsigned> ValueNodes;
|
|
|
|
/// ObjectNodes - This map contains entries for each memory object in the
|
|
/// program: globals, alloca's and mallocs.
|
|
DenseMap<Value*, unsigned> ObjectNodes;
|
|
|
|
/// ReturnNodes - This map contains an entry for each function in the
|
|
/// program that returns a value.
|
|
DenseMap<Function*, unsigned> ReturnNodes;
|
|
|
|
/// VarargNodes - This map contains the entry used to represent all pointers
|
|
/// passed through the varargs portion of a function call for a particular
|
|
/// function. An entry is not present in this map for functions that do not
|
|
/// take variable arguments.
|
|
DenseMap<Function*, unsigned> VarargNodes;
|
|
|
|
|
|
/// Constraints - This vector contains a list of all of the constraints
|
|
/// identified by the program.
|
|
std::vector<Constraint> Constraints;
|
|
|
|
// Map from graph node to maximum K value that is allowed (for functions,
|
|
// this is equivalent to the number of arguments + CallFirstArgPos)
|
|
std::map<unsigned, unsigned> MaxK;
|
|
|
|
/// This enum defines the GraphNodes indices that correspond to important
|
|
/// fixed sets.
|
|
enum {
|
|
UniversalSet = 0,
|
|
NullPtr = 1,
|
|
NullObject = 2,
|
|
NumberSpecialNodes
|
|
};
|
|
// Stack for Tarjan's
|
|
std::stack<unsigned> SCCStack;
|
|
// Map from Graph Node to DFS number
|
|
std::vector<unsigned> Node2DFS;
|
|
// Map from Graph Node to Deleted from graph.
|
|
std::vector<bool> Node2Deleted;
|
|
// Same as Node Maps, but implemented as std::map because it is faster to
|
|
// clear
|
|
std::map<unsigned, unsigned> Tarjan2DFS;
|
|
std::map<unsigned, bool> Tarjan2Deleted;
|
|
// Current DFS number
|
|
unsigned DFSNumber;
|
|
|
|
// Work lists.
|
|
WorkList w1, w2;
|
|
WorkList *CurrWL, *NextWL; // "current" and "next" work lists
|
|
|
|
// Offline variable substitution related things
|
|
|
|
// Temporary rep storage, used because we can't collapse SCC's in the
|
|
// predecessor graph by uniting the variables permanently, we can only do so
|
|
// for the successor graph.
|
|
std::vector<unsigned> VSSCCRep;
|
|
// Mapping from node to whether we have visited it during SCC finding yet.
|
|
std::vector<bool> Node2Visited;
|
|
// During variable substitution, we create unknowns to represent the unknown
|
|
// value that is a dereference of a variable. These nodes are known as
|
|
// "ref" nodes (since they represent the value of dereferences).
|
|
unsigned FirstRefNode;
|
|
// During HVN, we create represent address taken nodes as if they were
|
|
// unknown (since HVN, unlike HU, does not evaluate unions).
|
|
unsigned FirstAdrNode;
|
|
// Current pointer equivalence class number
|
|
unsigned PEClass;
|
|
// Mapping from points-to sets to equivalence classes
|
|
typedef DenseMap<SparseBitVector<> *, unsigned, BitmapKeyInfo> BitVectorMap;
|
|
BitVectorMap Set2PEClass;
|
|
// Mapping from pointer equivalences to the representative node. -1 if we
|
|
// have no representative node for this pointer equivalence class yet.
|
|
std::vector<int> PEClass2Node;
|
|
// Mapping from pointer equivalences to representative node. This includes
|
|
// pointer equivalent but not location equivalent variables. -1 if we have
|
|
// no representative node for this pointer equivalence class yet.
|
|
std::vector<int> PENLEClass2Node;
|
|
// Union/Find for HCD
|
|
std::vector<unsigned> HCDSCCRep;
|
|
// HCD's offline-detected cycles; "Statically DeTected"
|
|
// -1 if not part of such a cycle, otherwise a representative node.
|
|
std::vector<int> SDT;
|
|
// Whether to use SDT (UniteNodes can use it during solving, but not before)
|
|
bool SDTActive;
|
|
|
|
public:
|
|
static char ID;
|
|
Andersens() : ModulePass((intptr_t)&ID) {}
|
|
|
|
bool runOnModule(Module &M) {
|
|
InitializeAliasAnalysis(this);
|
|
IdentifyObjects(M);
|
|
CollectConstraints(M);
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa-constraints"
|
|
DEBUG(PrintConstraints());
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa"
|
|
SolveConstraints();
|
|
DEBUG(PrintPointsToGraph());
|
|
|
|
// Free the constraints list, as we don't need it to respond to alias
|
|
// requests.
|
|
ObjectNodes.clear();
|
|
ReturnNodes.clear();
|
|
VarargNodes.clear();
|
|
std::vector<Constraint>().swap(Constraints);
|
|
return false;
|
|
}
|
|
|
|
void releaseMemory() {
|
|
// FIXME: Until we have transitively required passes working correctly,
|
|
// this cannot be enabled! Otherwise, using -count-aa with the pass
|
|
// causes memory to be freed too early. :(
|
|
#if 0
|
|
// The memory objects and ValueNodes data structures at the only ones that
|
|
// are still live after construction.
|
|
std::vector<Node>().swap(GraphNodes);
|
|
ValueNodes.clear();
|
|
#endif
|
|
}
|
|
|
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
|
AliasAnalysis::getAnalysisUsage(AU);
|
|
AU.setPreservesAll(); // Does not transform code
|
|
}
|
|
|
|
//------------------------------------------------
|
|
// Implement the AliasAnalysis API
|
|
//
|
|
AliasResult alias(const Value *V1, unsigned V1Size,
|
|
const Value *V2, unsigned V2Size);
|
|
virtual ModRefResult getModRefInfo(CallSite CS, Value *P, unsigned Size);
|
|
virtual ModRefResult getModRefInfo(CallSite CS1, CallSite CS2);
|
|
void getMustAliases(Value *P, std::vector<Value*> &RetVals);
|
|
bool pointsToConstantMemory(const Value *P);
|
|
|
|
virtual void deleteValue(Value *V) {
|
|
ValueNodes.erase(V);
|
|
getAnalysis<AliasAnalysis>().deleteValue(V);
|
|
}
|
|
|
|
virtual void copyValue(Value *From, Value *To) {
|
|
ValueNodes[To] = ValueNodes[From];
|
|
getAnalysis<AliasAnalysis>().copyValue(From, To);
|
|
}
|
|
|
|
private:
|
|
/// getNode - Return the node corresponding to the specified pointer scalar.
|
|
///
|
|
unsigned getNode(Value *V) {
|
|
if (Constant *C = dyn_cast<Constant>(V))
|
|
if (!isa<GlobalValue>(C))
|
|
return getNodeForConstantPointer(C);
|
|
|
|
DenseMap<Value*, unsigned>::iterator I = ValueNodes.find(V);
|
|
if (I == ValueNodes.end()) {
|
|
#ifndef NDEBUG
|
|
V->dump();
|
|
#endif
|
|
assert(0 && "Value does not have a node in the points-to graph!");
|
|
}
|
|
return I->second;
|
|
}
|
|
|
|
/// getObject - Return the node corresponding to the memory object for the
|
|
/// specified global or allocation instruction.
|
|
unsigned getObject(Value *V) {
|
|
DenseMap<Value*, unsigned>::iterator I = ObjectNodes.find(V);
|
|
assert(I != ObjectNodes.end() &&
|
|
"Value does not have an object in the points-to graph!");
|
|
return I->second;
|
|
}
|
|
|
|
/// getReturnNode - Return the node representing the return value for the
|
|
/// specified function.
|
|
unsigned getReturnNode(Function *F) {
|
|
DenseMap<Function*, unsigned>::iterator I = ReturnNodes.find(F);
|
|
assert(I != ReturnNodes.end() && "Function does not return a value!");
|
|
return I->second;
|
|
}
|
|
|
|
/// getVarargNode - Return the node representing the variable arguments
|
|
/// formal for the specified function.
|
|
unsigned getVarargNode(Function *F) {
|
|
DenseMap<Function*, unsigned>::iterator I = VarargNodes.find(F);
|
|
assert(I != VarargNodes.end() && "Function does not take var args!");
|
|
return I->second;
|
|
}
|
|
|
|
/// getNodeValue - Get the node for the specified LLVM value and set the
|
|
/// value for it to be the specified value.
|
|
unsigned getNodeValue(Value &V) {
|
|
unsigned Index = getNode(&V);
|
|
GraphNodes[Index].setValue(&V);
|
|
return Index;
|
|
}
|
|
|
|
unsigned UniteNodes(unsigned First, unsigned Second,
|
|
bool UnionByRank = true);
|
|
unsigned FindNode(unsigned Node);
|
|
|
|
void IdentifyObjects(Module &M);
|
|
void CollectConstraints(Module &M);
|
|
bool AnalyzeUsesOfFunction(Value *);
|
|
void CreateConstraintGraph();
|
|
void OptimizeConstraints();
|
|
unsigned FindEquivalentNode(unsigned, unsigned);
|
|
void ClumpAddressTaken();
|
|
void RewriteConstraints();
|
|
void HU();
|
|
void HVN();
|
|
void HCD();
|
|
void Search(unsigned Node);
|
|
void UnitePointerEquivalences();
|
|
void SolveConstraints();
|
|
bool QueryNode(unsigned Node);
|
|
void Condense(unsigned Node);
|
|
void HUValNum(unsigned Node);
|
|
void HVNValNum(unsigned Node);
|
|
unsigned getNodeForConstantPointer(Constant *C);
|
|
unsigned getNodeForConstantPointerTarget(Constant *C);
|
|
void AddGlobalInitializerConstraints(unsigned, Constant *C);
|
|
|
|
void AddConstraintsForNonInternalLinkage(Function *F);
|
|
void AddConstraintsForCall(CallSite CS, Function *F);
|
|
bool AddConstraintsForExternalCall(CallSite CS, Function *F);
|
|
|
|
|
|
void PrintNode(Node *N);
|
|
void PrintConstraints();
|
|
void PrintConstraint(const Constraint &);
|
|
void PrintLabels();
|
|
void PrintPointsToGraph();
|
|
|
|
//===------------------------------------------------------------------===//
|
|
// Instruction visitation methods for adding constraints
|
|
//
|
|
friend class InstVisitor<Andersens>;
|
|
void visitReturnInst(ReturnInst &RI);
|
|
void visitInvokeInst(InvokeInst &II) { visitCallSite(CallSite(&II)); }
|
|
void visitCallInst(CallInst &CI) { visitCallSite(CallSite(&CI)); }
|
|
void visitCallSite(CallSite CS);
|
|
void visitAllocationInst(AllocationInst &AI);
|
|
void visitLoadInst(LoadInst &LI);
|
|
void visitStoreInst(StoreInst &SI);
|
|
void visitGetElementPtrInst(GetElementPtrInst &GEP);
|
|
void visitPHINode(PHINode &PN);
|
|
void visitCastInst(CastInst &CI);
|
|
void visitICmpInst(ICmpInst &ICI) {} // NOOP!
|
|
void visitFCmpInst(FCmpInst &ICI) {} // NOOP!
|
|
void visitSelectInst(SelectInst &SI);
|
|
void visitVAArg(VAArgInst &I);
|
|
void visitInstruction(Instruction &I);
|
|
|
|
};
|
|
|
|
char Andersens::ID = 0;
|
|
RegisterPass<Andersens> X("anders-aa",
|
|
"Andersen's Interprocedural Alias Analysis");
|
|
RegisterAnalysisGroup<AliasAnalysis> Y(X);
|
|
|
|
// Initialize Timestamp Counter (static).
|
|
unsigned Andersens::Node::Counter = 0;
|
|
}
|
|
|
|
ModulePass *llvm::createAndersensPass() { return new Andersens(); }
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// AliasAnalysis Interface Implementation
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
AliasAnalysis::AliasResult Andersens::alias(const Value *V1, unsigned V1Size,
|
|
const Value *V2, unsigned V2Size) {
|
|
Node *N1 = &GraphNodes[FindNode(getNode(const_cast<Value*>(V1)))];
|
|
Node *N2 = &GraphNodes[FindNode(getNode(const_cast<Value*>(V2)))];
|
|
|
|
// Check to see if the two pointers are known to not alias. They don't alias
|
|
// if their points-to sets do not intersect.
|
|
if (!N1->intersectsIgnoring(N2, NullObject))
|
|
return NoAlias;
|
|
|
|
return AliasAnalysis::alias(V1, V1Size, V2, V2Size);
|
|
}
|
|
|
|
AliasAnalysis::ModRefResult
|
|
Andersens::getModRefInfo(CallSite CS, Value *P, unsigned Size) {
|
|
// The only thing useful that we can contribute for mod/ref information is
|
|
// when calling external function calls: if we know that memory never escapes
|
|
// from the program, it cannot be modified by an external call.
|
|
//
|
|
// NOTE: This is not really safe, at least not when the entire program is not
|
|
// available. The deal is that the external function could call back into the
|
|
// program and modify stuff. We ignore this technical niggle for now. This
|
|
// is, after all, a "research quality" implementation of Andersen's analysis.
|
|
if (Function *F = CS.getCalledFunction())
|
|
if (F->isDeclaration()) {
|
|
Node *N1 = &GraphNodes[FindNode(getNode(P))];
|
|
|
|
if (N1->PointsTo->empty())
|
|
return NoModRef;
|
|
|
|
if (!N1->PointsTo->test(UniversalSet))
|
|
return NoModRef; // P doesn't point to the universal set.
|
|
}
|
|
|
|
return AliasAnalysis::getModRefInfo(CS, P, Size);
|
|
}
|
|
|
|
AliasAnalysis::ModRefResult
|
|
Andersens::getModRefInfo(CallSite CS1, CallSite CS2) {
|
|
return AliasAnalysis::getModRefInfo(CS1,CS2);
|
|
}
|
|
|
|
/// getMustAlias - We can provide must alias information if we know that a
|
|
/// pointer can only point to a specific function or the null pointer.
|
|
/// Unfortunately we cannot determine must-alias information for global
|
|
/// variables or any other memory memory objects because we do not track whether
|
|
/// a pointer points to the beginning of an object or a field of it.
|
|
void Andersens::getMustAliases(Value *P, std::vector<Value*> &RetVals) {
|
|
Node *N = &GraphNodes[FindNode(getNode(P))];
|
|
if (N->PointsTo->count() == 1) {
|
|
Node *Pointee = &GraphNodes[N->PointsTo->find_first()];
|
|
// If a function is the only object in the points-to set, then it must be
|
|
// the destination. Note that we can't handle global variables here,
|
|
// because we don't know if the pointer is actually pointing to a field of
|
|
// the global or to the beginning of it.
|
|
if (Value *V = Pointee->getValue()) {
|
|
if (Function *F = dyn_cast<Function>(V))
|
|
RetVals.push_back(F);
|
|
} else {
|
|
// If the object in the points-to set is the null object, then the null
|
|
// pointer is a must alias.
|
|
if (Pointee == &GraphNodes[NullObject])
|
|
RetVals.push_back(Constant::getNullValue(P->getType()));
|
|
}
|
|
}
|
|
AliasAnalysis::getMustAliases(P, RetVals);
|
|
}
|
|
|
|
/// pointsToConstantMemory - If we can determine that this pointer only points
|
|
/// to constant memory, return true. In practice, this means that if the
|
|
/// pointer can only point to constant globals, functions, or the null pointer,
|
|
/// return true.
|
|
///
|
|
bool Andersens::pointsToConstantMemory(const Value *P) {
|
|
Node *N = &GraphNodes[FindNode(getNode(const_cast<Value*>(P)))];
|
|
unsigned i;
|
|
|
|
for (SparseBitVector<>::iterator bi = N->PointsTo->begin();
|
|
bi != N->PointsTo->end();
|
|
++bi) {
|
|
i = *bi;
|
|
Node *Pointee = &GraphNodes[i];
|
|
if (Value *V = Pointee->getValue()) {
|
|
if (!isa<GlobalValue>(V) || (isa<GlobalVariable>(V) &&
|
|
!cast<GlobalVariable>(V)->isConstant()))
|
|
return AliasAnalysis::pointsToConstantMemory(P);
|
|
} else {
|
|
if (i != NullObject)
|
|
return AliasAnalysis::pointsToConstantMemory(P);
|
|
}
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Object Identification Phase
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// IdentifyObjects - This stage scans the program, adding an entry to the
|
|
/// GraphNodes list for each memory object in the program (global stack or
|
|
/// heap), and populates the ValueNodes and ObjectNodes maps for these objects.
|
|
///
|
|
void Andersens::IdentifyObjects(Module &M) {
|
|
unsigned NumObjects = 0;
|
|
|
|
// Object #0 is always the universal set: the object that we don't know
|
|
// anything about.
|
|
assert(NumObjects == UniversalSet && "Something changed!");
|
|
++NumObjects;
|
|
|
|
// Object #1 always represents the null pointer.
|
|
assert(NumObjects == NullPtr && "Something changed!");
|
|
++NumObjects;
|
|
|
|
// Object #2 always represents the null object (the object pointed to by null)
|
|
assert(NumObjects == NullObject && "Something changed!");
|
|
++NumObjects;
|
|
|
|
// Add all the globals first.
|
|
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
|
|
I != E; ++I) {
|
|
ObjectNodes[I] = NumObjects++;
|
|
ValueNodes[I] = NumObjects++;
|
|
}
|
|
|
|
// Add nodes for all of the functions and the instructions inside of them.
|
|
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
|
|
// The function itself is a memory object.
|
|
unsigned First = NumObjects;
|
|
ValueNodes[F] = NumObjects++;
|
|
if (isa<PointerType>(F->getFunctionType()->getReturnType()))
|
|
ReturnNodes[F] = NumObjects++;
|
|
if (F->getFunctionType()->isVarArg())
|
|
VarargNodes[F] = NumObjects++;
|
|
|
|
|
|
// Add nodes for all of the incoming pointer arguments.
|
|
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
|
|
I != E; ++I)
|
|
{
|
|
if (isa<PointerType>(I->getType()))
|
|
ValueNodes[I] = NumObjects++;
|
|
}
|
|
MaxK[First] = NumObjects - First;
|
|
|
|
// Scan the function body, creating a memory object for each heap/stack
|
|
// allocation in the body of the function and a node to represent all
|
|
// pointer values defined by instructions and used as operands.
|
|
for (inst_iterator II = inst_begin(F), E = inst_end(F); II != E; ++II) {
|
|
// If this is an heap or stack allocation, create a node for the memory
|
|
// object.
|
|
if (isa<PointerType>(II->getType())) {
|
|
ValueNodes[&*II] = NumObjects++;
|
|
if (AllocationInst *AI = dyn_cast<AllocationInst>(&*II))
|
|
ObjectNodes[AI] = NumObjects++;
|
|
}
|
|
|
|
// Calls to inline asm need to be added as well because the callee isn't
|
|
// referenced anywhere else.
|
|
if (CallInst *CI = dyn_cast<CallInst>(&*II)) {
|
|
Value *Callee = CI->getCalledValue();
|
|
if (isa<InlineAsm>(Callee))
|
|
ValueNodes[Callee] = NumObjects++;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Now that we know how many objects to create, make them all now!
|
|
GraphNodes.resize(NumObjects);
|
|
NumNodes += NumObjects;
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Constraint Identification Phase
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// getNodeForConstantPointer - Return the node corresponding to the constant
|
|
/// pointer itself.
|
|
unsigned Andersens::getNodeForConstantPointer(Constant *C) {
|
|
assert(isa<PointerType>(C->getType()) && "Not a constant pointer!");
|
|
|
|
if (isa<ConstantPointerNull>(C) || isa<UndefValue>(C))
|
|
return NullPtr;
|
|
else if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
|
|
return getNode(GV);
|
|
else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
|
|
switch (CE->getOpcode()) {
|
|
case Instruction::GetElementPtr:
|
|
return getNodeForConstantPointer(CE->getOperand(0));
|
|
case Instruction::IntToPtr:
|
|
return UniversalSet;
|
|
case Instruction::BitCast:
|
|
return getNodeForConstantPointer(CE->getOperand(0));
|
|
default:
|
|
cerr << "Constant Expr not yet handled: " << *CE << "\n";
|
|
assert(0);
|
|
}
|
|
} else {
|
|
assert(0 && "Unknown constant pointer!");
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// getNodeForConstantPointerTarget - Return the node POINTED TO by the
|
|
/// specified constant pointer.
|
|
unsigned Andersens::getNodeForConstantPointerTarget(Constant *C) {
|
|
assert(isa<PointerType>(C->getType()) && "Not a constant pointer!");
|
|
|
|
if (isa<ConstantPointerNull>(C))
|
|
return NullObject;
|
|
else if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
|
|
return getObject(GV);
|
|
else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
|
|
switch (CE->getOpcode()) {
|
|
case Instruction::GetElementPtr:
|
|
return getNodeForConstantPointerTarget(CE->getOperand(0));
|
|
case Instruction::IntToPtr:
|
|
return UniversalSet;
|
|
case Instruction::BitCast:
|
|
return getNodeForConstantPointerTarget(CE->getOperand(0));
|
|
default:
|
|
cerr << "Constant Expr not yet handled: " << *CE << "\n";
|
|
assert(0);
|
|
}
|
|
} else {
|
|
assert(0 && "Unknown constant pointer!");
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/// AddGlobalInitializerConstraints - Add inclusion constraints for the memory
|
|
/// object N, which contains values indicated by C.
|
|
void Andersens::AddGlobalInitializerConstraints(unsigned NodeIndex,
|
|
Constant *C) {
|
|
if (C->getType()->isFirstClassType()) {
|
|
if (isa<PointerType>(C->getType()))
|
|
Constraints.push_back(Constraint(Constraint::Copy, NodeIndex,
|
|
getNodeForConstantPointer(C)));
|
|
} else if (C->isNullValue()) {
|
|
Constraints.push_back(Constraint(Constraint::Copy, NodeIndex,
|
|
NullObject));
|
|
return;
|
|
} else if (!isa<UndefValue>(C)) {
|
|
// If this is an array or struct, include constraints for each element.
|
|
assert(isa<ConstantArray>(C) || isa<ConstantStruct>(C));
|
|
for (unsigned i = 0, e = C->getNumOperands(); i != e; ++i)
|
|
AddGlobalInitializerConstraints(NodeIndex,
|
|
cast<Constant>(C->getOperand(i)));
|
|
}
|
|
}
|
|
|
|
/// AddConstraintsForNonInternalLinkage - If this function does not have
|
|
/// internal linkage, realize that we can't trust anything passed into or
|
|
/// returned by this function.
|
|
void Andersens::AddConstraintsForNonInternalLinkage(Function *F) {
|
|
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E; ++I)
|
|
if (isa<PointerType>(I->getType()))
|
|
// If this is an argument of an externally accessible function, the
|
|
// incoming pointer might point to anything.
|
|
Constraints.push_back(Constraint(Constraint::Copy, getNode(I),
|
|
UniversalSet));
|
|
}
|
|
|
|
/// AddConstraintsForCall - If this is a call to a "known" function, add the
|
|
/// constraints and return true. If this is a call to an unknown function,
|
|
/// return false.
|
|
bool Andersens::AddConstraintsForExternalCall(CallSite CS, Function *F) {
|
|
assert(F->isDeclaration() && "Not an external function!");
|
|
|
|
// These functions don't induce any points-to constraints.
|
|
if (F->getName() == "atoi" || F->getName() == "atof" ||
|
|
F->getName() == "atol" || F->getName() == "atoll" ||
|
|
F->getName() == "remove" || F->getName() == "unlink" ||
|
|
F->getName() == "rename" || F->getName() == "memcmp" ||
|
|
F->getName() == "llvm.memset.i32" ||
|
|
F->getName() == "llvm.memset.i64" ||
|
|
F->getName() == "strcmp" || F->getName() == "strncmp" ||
|
|
F->getName() == "execl" || F->getName() == "execlp" ||
|
|
F->getName() == "execle" || F->getName() == "execv" ||
|
|
F->getName() == "execvp" || F->getName() == "chmod" ||
|
|
F->getName() == "puts" || F->getName() == "write" ||
|
|
F->getName() == "open" || F->getName() == "create" ||
|
|
F->getName() == "truncate" || F->getName() == "chdir" ||
|
|
F->getName() == "mkdir" || F->getName() == "rmdir" ||
|
|
F->getName() == "read" || F->getName() == "pipe" ||
|
|
F->getName() == "wait" || F->getName() == "time" ||
|
|
F->getName() == "stat" || F->getName() == "fstat" ||
|
|
F->getName() == "lstat" || F->getName() == "strtod" ||
|
|
F->getName() == "strtof" || F->getName() == "strtold" ||
|
|
F->getName() == "fopen" || F->getName() == "fdopen" ||
|
|
F->getName() == "freopen" ||
|
|
F->getName() == "fflush" || F->getName() == "feof" ||
|
|
F->getName() == "fileno" || F->getName() == "clearerr" ||
|
|
F->getName() == "rewind" || F->getName() == "ftell" ||
|
|
F->getName() == "ferror" || F->getName() == "fgetc" ||
|
|
F->getName() == "fgetc" || F->getName() == "_IO_getc" ||
|
|
F->getName() == "fwrite" || F->getName() == "fread" ||
|
|
F->getName() == "fgets" || F->getName() == "ungetc" ||
|
|
F->getName() == "fputc" ||
|
|
F->getName() == "fputs" || F->getName() == "putc" ||
|
|
F->getName() == "ftell" || F->getName() == "rewind" ||
|
|
F->getName() == "_IO_putc" || F->getName() == "fseek" ||
|
|
F->getName() == "fgetpos" || F->getName() == "fsetpos" ||
|
|
F->getName() == "printf" || F->getName() == "fprintf" ||
|
|
F->getName() == "sprintf" || F->getName() == "vprintf" ||
|
|
F->getName() == "vfprintf" || F->getName() == "vsprintf" ||
|
|
F->getName() == "scanf" || F->getName() == "fscanf" ||
|
|
F->getName() == "sscanf" || F->getName() == "__assert_fail" ||
|
|
F->getName() == "modf")
|
|
return true;
|
|
|
|
|
|
// These functions do induce points-to edges.
|
|
if (F->getName() == "llvm.memcpy.i32" || F->getName() == "llvm.memcpy.i64" ||
|
|
F->getName() == "llvm.memmove.i32" ||F->getName() == "llvm.memmove.i64" ||
|
|
F->getName() == "memmove") {
|
|
|
|
// *Dest = *Src, which requires an artificial graph node to represent the
|
|
// constraint. It is broken up into *Dest = temp, temp = *Src
|
|
unsigned FirstArg = getNode(CS.getArgument(0));
|
|
unsigned SecondArg = getNode(CS.getArgument(1));
|
|
unsigned TempArg = GraphNodes.size();
|
|
GraphNodes.push_back(Node());
|
|
Constraints.push_back(Constraint(Constraint::Store,
|
|
FirstArg, TempArg));
|
|
Constraints.push_back(Constraint(Constraint::Load,
|
|
TempArg, SecondArg));
|
|
return true;
|
|
}
|
|
|
|
// Result = Arg0
|
|
if (F->getName() == "realloc" || F->getName() == "strchr" ||
|
|
F->getName() == "strrchr" || F->getName() == "strstr" ||
|
|
F->getName() == "strtok") {
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
getNode(CS.getInstruction()),
|
|
getNode(CS.getArgument(0))));
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
|
|
/// AnalyzeUsesOfFunction - Look at all of the users of the specified function.
|
|
/// If this is used by anything complex (i.e., the address escapes), return
|
|
/// true.
|
|
bool Andersens::AnalyzeUsesOfFunction(Value *V) {
|
|
|
|
if (!isa<PointerType>(V->getType())) return true;
|
|
|
|
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E; ++UI)
|
|
if (dyn_cast<LoadInst>(*UI)) {
|
|
return false;
|
|
} else if (StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
|
|
if (V == SI->getOperand(1)) {
|
|
return false;
|
|
} else if (SI->getOperand(1)) {
|
|
return true; // Storing the pointer
|
|
}
|
|
} else if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(*UI)) {
|
|
if (AnalyzeUsesOfFunction(GEP)) return true;
|
|
} else if (CallInst *CI = dyn_cast<CallInst>(*UI)) {
|
|
// Make sure that this is just the function being called, not that it is
|
|
// passing into the function.
|
|
for (unsigned i = 1, e = CI->getNumOperands(); i != e; ++i)
|
|
if (CI->getOperand(i) == V) return true;
|
|
} else if (InvokeInst *II = dyn_cast<InvokeInst>(*UI)) {
|
|
// Make sure that this is just the function being called, not that it is
|
|
// passing into the function.
|
|
for (unsigned i = 3, e = II->getNumOperands(); i != e; ++i)
|
|
if (II->getOperand(i) == V) return true;
|
|
} else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(*UI)) {
|
|
if (CE->getOpcode() == Instruction::GetElementPtr ||
|
|
CE->getOpcode() == Instruction::BitCast) {
|
|
if (AnalyzeUsesOfFunction(CE))
|
|
return true;
|
|
} else {
|
|
return true;
|
|
}
|
|
} else if (ICmpInst *ICI = dyn_cast<ICmpInst>(*UI)) {
|
|
if (!isa<ConstantPointerNull>(ICI->getOperand(1)))
|
|
return true; // Allow comparison against null.
|
|
} else if (dyn_cast<FreeInst>(*UI)) {
|
|
return false;
|
|
} else {
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|
|
|
|
/// CollectConstraints - This stage scans the program, adding a constraint to
|
|
/// the Constraints list for each instruction in the program that induces a
|
|
/// constraint, and setting up the initial points-to graph.
|
|
///
|
|
void Andersens::CollectConstraints(Module &M) {
|
|
// First, the universal set points to itself.
|
|
Constraints.push_back(Constraint(Constraint::AddressOf, UniversalSet,
|
|
UniversalSet));
|
|
Constraints.push_back(Constraint(Constraint::Store, UniversalSet,
|
|
UniversalSet));
|
|
|
|
// Next, the null pointer points to the null object.
|
|
Constraints.push_back(Constraint(Constraint::AddressOf, NullPtr, NullObject));
|
|
|
|
// Next, add any constraints on global variables and their initializers.
|
|
for (Module::global_iterator I = M.global_begin(), E = M.global_end();
|
|
I != E; ++I) {
|
|
// Associate the address of the global object as pointing to the memory for
|
|
// the global: &G = <G memory>
|
|
unsigned ObjectIndex = getObject(I);
|
|
Node *Object = &GraphNodes[ObjectIndex];
|
|
Object->setValue(I);
|
|
Constraints.push_back(Constraint(Constraint::AddressOf, getNodeValue(*I),
|
|
ObjectIndex));
|
|
|
|
if (I->hasInitializer()) {
|
|
AddGlobalInitializerConstraints(ObjectIndex, I->getInitializer());
|
|
} else {
|
|
// If it doesn't have an initializer (i.e. it's defined in another
|
|
// translation unit), it points to the universal set.
|
|
Constraints.push_back(Constraint(Constraint::Copy, ObjectIndex,
|
|
UniversalSet));
|
|
}
|
|
}
|
|
|
|
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
|
|
// Set up the return value node.
|
|
if (isa<PointerType>(F->getFunctionType()->getReturnType()))
|
|
GraphNodes[getReturnNode(F)].setValue(F);
|
|
if (F->getFunctionType()->isVarArg())
|
|
GraphNodes[getVarargNode(F)].setValue(F);
|
|
|
|
// Set up incoming argument nodes.
|
|
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
|
|
I != E; ++I)
|
|
if (isa<PointerType>(I->getType()))
|
|
getNodeValue(*I);
|
|
|
|
// At some point we should just add constraints for the escaping functions
|
|
// at solve time, but this slows down solving. For now, we simply mark
|
|
// address taken functions as escaping and treat them as external.
|
|
if (!F->hasInternalLinkage() || AnalyzeUsesOfFunction(F))
|
|
AddConstraintsForNonInternalLinkage(F);
|
|
|
|
if (!F->isDeclaration()) {
|
|
// Scan the function body, creating a memory object for each heap/stack
|
|
// allocation in the body of the function and a node to represent all
|
|
// pointer values defined by instructions and used as operands.
|
|
visit(F);
|
|
} else {
|
|
// External functions that return pointers return the universal set.
|
|
if (isa<PointerType>(F->getFunctionType()->getReturnType()))
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
getReturnNode(F),
|
|
UniversalSet));
|
|
|
|
// Any pointers that are passed into the function have the universal set
|
|
// stored into them.
|
|
for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end();
|
|
I != E; ++I)
|
|
if (isa<PointerType>(I->getType())) {
|
|
// Pointers passed into external functions could have anything stored
|
|
// through them.
|
|
Constraints.push_back(Constraint(Constraint::Store, getNode(I),
|
|
UniversalSet));
|
|
// Memory objects passed into external function calls can have the
|
|
// universal set point to them.
|
|
#if FULL_UNIVERSAL
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
UniversalSet,
|
|
getNode(I)));
|
|
#else
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
getNode(I),
|
|
UniversalSet));
|
|
#endif
|
|
}
|
|
|
|
// If this is an external varargs function, it can also store pointers
|
|
// into any pointers passed through the varargs section.
|
|
if (F->getFunctionType()->isVarArg())
|
|
Constraints.push_back(Constraint(Constraint::Store, getVarargNode(F),
|
|
UniversalSet));
|
|
}
|
|
}
|
|
NumConstraints += Constraints.size();
|
|
}
|
|
|
|
|
|
void Andersens::visitInstruction(Instruction &I) {
|
|
#ifdef NDEBUG
|
|
return; // This function is just a big assert.
|
|
#endif
|
|
if (isa<BinaryOperator>(I))
|
|
return;
|
|
// Most instructions don't have any effect on pointer values.
|
|
switch (I.getOpcode()) {
|
|
case Instruction::Br:
|
|
case Instruction::Switch:
|
|
case Instruction::Unwind:
|
|
case Instruction::Unreachable:
|
|
case Instruction::Free:
|
|
case Instruction::ICmp:
|
|
case Instruction::FCmp:
|
|
return;
|
|
default:
|
|
// Is this something we aren't handling yet?
|
|
cerr << "Unknown instruction: " << I;
|
|
abort();
|
|
}
|
|
}
|
|
|
|
void Andersens::visitAllocationInst(AllocationInst &AI) {
|
|
unsigned ObjectIndex = getObject(&AI);
|
|
GraphNodes[ObjectIndex].setValue(&AI);
|
|
Constraints.push_back(Constraint(Constraint::AddressOf, getNodeValue(AI),
|
|
ObjectIndex));
|
|
}
|
|
|
|
void Andersens::visitReturnInst(ReturnInst &RI) {
|
|
if (RI.getNumOperands() && isa<PointerType>(RI.getOperand(0)->getType()))
|
|
// return V --> <Copy/retval{F}/v>
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
getReturnNode(RI.getParent()->getParent()),
|
|
getNode(RI.getOperand(0))));
|
|
}
|
|
|
|
void Andersens::visitLoadInst(LoadInst &LI) {
|
|
if (isa<PointerType>(LI.getType()))
|
|
// P1 = load P2 --> <Load/P1/P2>
|
|
Constraints.push_back(Constraint(Constraint::Load, getNodeValue(LI),
|
|
getNode(LI.getOperand(0))));
|
|
}
|
|
|
|
void Andersens::visitStoreInst(StoreInst &SI) {
|
|
if (isa<PointerType>(SI.getOperand(0)->getType()))
|
|
// store P1, P2 --> <Store/P2/P1>
|
|
Constraints.push_back(Constraint(Constraint::Store,
|
|
getNode(SI.getOperand(1)),
|
|
getNode(SI.getOperand(0))));
|
|
}
|
|
|
|
void Andersens::visitGetElementPtrInst(GetElementPtrInst &GEP) {
|
|
// P1 = getelementptr P2, ... --> <Copy/P1/P2>
|
|
Constraints.push_back(Constraint(Constraint::Copy, getNodeValue(GEP),
|
|
getNode(GEP.getOperand(0))));
|
|
}
|
|
|
|
void Andersens::visitPHINode(PHINode &PN) {
|
|
if (isa<PointerType>(PN.getType())) {
|
|
unsigned PNN = getNodeValue(PN);
|
|
for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
|
|
// P1 = phi P2, P3 --> <Copy/P1/P2>, <Copy/P1/P3>, ...
|
|
Constraints.push_back(Constraint(Constraint::Copy, PNN,
|
|
getNode(PN.getIncomingValue(i))));
|
|
}
|
|
}
|
|
|
|
void Andersens::visitCastInst(CastInst &CI) {
|
|
Value *Op = CI.getOperand(0);
|
|
if (isa<PointerType>(CI.getType())) {
|
|
if (isa<PointerType>(Op->getType())) {
|
|
// P1 = cast P2 --> <Copy/P1/P2>
|
|
Constraints.push_back(Constraint(Constraint::Copy, getNodeValue(CI),
|
|
getNode(CI.getOperand(0))));
|
|
} else {
|
|
// P1 = cast int --> <Copy/P1/Univ>
|
|
#if 0
|
|
Constraints.push_back(Constraint(Constraint::Copy, getNodeValue(CI),
|
|
UniversalSet));
|
|
#else
|
|
getNodeValue(CI);
|
|
#endif
|
|
}
|
|
} else if (isa<PointerType>(Op->getType())) {
|
|
// int = cast P1 --> <Copy/Univ/P1>
|
|
#if 0
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
UniversalSet,
|
|
getNode(CI.getOperand(0))));
|
|
#else
|
|
getNode(CI.getOperand(0));
|
|
#endif
|
|
}
|
|
}
|
|
|
|
void Andersens::visitSelectInst(SelectInst &SI) {
|
|
if (isa<PointerType>(SI.getType())) {
|
|
unsigned SIN = getNodeValue(SI);
|
|
// P1 = select C, P2, P3 ---> <Copy/P1/P2>, <Copy/P1/P3>
|
|
Constraints.push_back(Constraint(Constraint::Copy, SIN,
|
|
getNode(SI.getOperand(1))));
|
|
Constraints.push_back(Constraint(Constraint::Copy, SIN,
|
|
getNode(SI.getOperand(2))));
|
|
}
|
|
}
|
|
|
|
void Andersens::visitVAArg(VAArgInst &I) {
|
|
assert(0 && "vaarg not handled yet!");
|
|
}
|
|
|
|
/// AddConstraintsForCall - Add constraints for a call with actual arguments
|
|
/// specified by CS to the function specified by F. Note that the types of
|
|
/// arguments might not match up in the case where this is an indirect call and
|
|
/// the function pointer has been casted. If this is the case, do something
|
|
/// reasonable.
|
|
void Andersens::AddConstraintsForCall(CallSite CS, Function *F) {
|
|
Value *CallValue = CS.getCalledValue();
|
|
bool IsDeref = F == NULL;
|
|
|
|
// If this is a call to an external function, try to handle it directly to get
|
|
// some taste of context sensitivity.
|
|
if (F && F->isDeclaration() && AddConstraintsForExternalCall(CS, F))
|
|
return;
|
|
|
|
if (isa<PointerType>(CS.getType())) {
|
|
unsigned CSN = getNode(CS.getInstruction());
|
|
if (!F || isa<PointerType>(F->getFunctionType()->getReturnType())) {
|
|
if (IsDeref)
|
|
Constraints.push_back(Constraint(Constraint::Load, CSN,
|
|
getNode(CallValue), CallReturnPos));
|
|
else
|
|
Constraints.push_back(Constraint(Constraint::Copy, CSN,
|
|
getNode(CallValue) + CallReturnPos));
|
|
} else {
|
|
// If the function returns a non-pointer value, handle this just like we
|
|
// treat a nonpointer cast to pointer.
|
|
Constraints.push_back(Constraint(Constraint::Copy, CSN,
|
|
UniversalSet));
|
|
}
|
|
} else if (F && isa<PointerType>(F->getFunctionType()->getReturnType())) {
|
|
#if FULL_UNIVERSAL
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
UniversalSet,
|
|
getNode(CallValue) + CallReturnPos));
|
|
#else
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
getNode(CallValue) + CallReturnPos,
|
|
UniversalSet));
|
|
#endif
|
|
|
|
|
|
}
|
|
|
|
CallSite::arg_iterator ArgI = CS.arg_begin(), ArgE = CS.arg_end();
|
|
if (F) {
|
|
// Direct Call
|
|
Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end();
|
|
for (; AI != AE && ArgI != ArgE; ++AI, ++ArgI)
|
|
if (isa<PointerType>(AI->getType())) {
|
|
if (isa<PointerType>((*ArgI)->getType())) {
|
|
// Copy the actual argument into the formal argument.
|
|
Constraints.push_back(Constraint(Constraint::Copy, getNode(AI),
|
|
getNode(*ArgI)));
|
|
} else {
|
|
Constraints.push_back(Constraint(Constraint::Copy, getNode(AI),
|
|
UniversalSet));
|
|
}
|
|
} else if (isa<PointerType>((*ArgI)->getType())) {
|
|
#if FULL_UNIVERSAL
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
UniversalSet,
|
|
getNode(*ArgI)));
|
|
#else
|
|
Constraints.push_back(Constraint(Constraint::Copy,
|
|
getNode(*ArgI),
|
|
UniversalSet));
|
|
#endif
|
|
}
|
|
} else {
|
|
//Indirect Call
|
|
unsigned ArgPos = CallFirstArgPos;
|
|
for (; ArgI != ArgE; ++ArgI) {
|
|
if (isa<PointerType>((*ArgI)->getType())) {
|
|
// Copy the actual argument into the formal argument.
|
|
Constraints.push_back(Constraint(Constraint::Store,
|
|
getNode(CallValue),
|
|
getNode(*ArgI), ArgPos++));
|
|
} else {
|
|
Constraints.push_back(Constraint(Constraint::Store,
|
|
getNode (CallValue),
|
|
UniversalSet, ArgPos++));
|
|
}
|
|
}
|
|
}
|
|
// Copy all pointers passed through the varargs section to the varargs node.
|
|
if (F && F->getFunctionType()->isVarArg())
|
|
for (; ArgI != ArgE; ++ArgI)
|
|
if (isa<PointerType>((*ArgI)->getType()))
|
|
Constraints.push_back(Constraint(Constraint::Copy, getVarargNode(F),
|
|
getNode(*ArgI)));
|
|
// If more arguments are passed in than we track, just drop them on the floor.
|
|
}
|
|
|
|
void Andersens::visitCallSite(CallSite CS) {
|
|
if (isa<PointerType>(CS.getType()))
|
|
getNodeValue(*CS.getInstruction());
|
|
|
|
if (Function *F = CS.getCalledFunction()) {
|
|
AddConstraintsForCall(CS, F);
|
|
} else {
|
|
AddConstraintsForCall(CS, NULL);
|
|
}
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Constraint Solving Phase
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
/// intersects - Return true if the points-to set of this node intersects
|
|
/// with the points-to set of the specified node.
|
|
bool Andersens::Node::intersects(Node *N) const {
|
|
return PointsTo->intersects(N->PointsTo);
|
|
}
|
|
|
|
/// intersectsIgnoring - Return true if the points-to set of this node
|
|
/// intersects with the points-to set of the specified node on any nodes
|
|
/// except for the specified node to ignore.
|
|
bool Andersens::Node::intersectsIgnoring(Node *N, unsigned Ignoring) const {
|
|
// TODO: If we are only going to call this with the same value for Ignoring,
|
|
// we should move the special values out of the points-to bitmap.
|
|
bool WeHadIt = PointsTo->test(Ignoring);
|
|
bool NHadIt = N->PointsTo->test(Ignoring);
|
|
bool Result = false;
|
|
if (WeHadIt)
|
|
PointsTo->reset(Ignoring);
|
|
if (NHadIt)
|
|
N->PointsTo->reset(Ignoring);
|
|
Result = PointsTo->intersects(N->PointsTo);
|
|
if (WeHadIt)
|
|
PointsTo->set(Ignoring);
|
|
if (NHadIt)
|
|
N->PointsTo->set(Ignoring);
|
|
return Result;
|
|
}
|
|
|
|
void dumpToDOUT(SparseBitVector<> *bitmap) {
|
|
#ifndef NDEBUG
|
|
dump(*bitmap, DOUT);
|
|
#endif
|
|
}
|
|
|
|
|
|
/// Clump together address taken variables so that the points-to sets use up
|
|
/// less space and can be operated on faster.
|
|
|
|
void Andersens::ClumpAddressTaken() {
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa-renumber"
|
|
std::vector<unsigned> Translate;
|
|
std::vector<Node> NewGraphNodes;
|
|
|
|
Translate.resize(GraphNodes.size());
|
|
unsigned NewPos = 0;
|
|
|
|
for (unsigned i = 0; i < Constraints.size(); ++i) {
|
|
Constraint &C = Constraints[i];
|
|
if (C.Type == Constraint::AddressOf) {
|
|
GraphNodes[C.Src].AddressTaken = true;
|
|
}
|
|
}
|
|
for (unsigned i = 0; i < NumberSpecialNodes; ++i) {
|
|
unsigned Pos = NewPos++;
|
|
Translate[i] = Pos;
|
|
NewGraphNodes.push_back(GraphNodes[i]);
|
|
DOUT << "Renumbering node " << i << " to node " << Pos << "\n";
|
|
}
|
|
|
|
// I believe this ends up being faster than making two vectors and splicing
|
|
// them.
|
|
for (unsigned i = NumberSpecialNodes; i < GraphNodes.size(); ++i) {
|
|
if (GraphNodes[i].AddressTaken) {
|
|
unsigned Pos = NewPos++;
|
|
Translate[i] = Pos;
|
|
NewGraphNodes.push_back(GraphNodes[i]);
|
|
DOUT << "Renumbering node " << i << " to node " << Pos << "\n";
|
|
}
|
|
}
|
|
|
|
for (unsigned i = NumberSpecialNodes; i < GraphNodes.size(); ++i) {
|
|
if (!GraphNodes[i].AddressTaken) {
|
|
unsigned Pos = NewPos++;
|
|
Translate[i] = Pos;
|
|
NewGraphNodes.push_back(GraphNodes[i]);
|
|
DOUT << "Renumbering node " << i << " to node " << Pos << "\n";
|
|
}
|
|
}
|
|
|
|
for (DenseMap<Value*, unsigned>::iterator Iter = ValueNodes.begin();
|
|
Iter != ValueNodes.end();
|
|
++Iter)
|
|
Iter->second = Translate[Iter->second];
|
|
|
|
for (DenseMap<Value*, unsigned>::iterator Iter = ObjectNodes.begin();
|
|
Iter != ObjectNodes.end();
|
|
++Iter)
|
|
Iter->second = Translate[Iter->second];
|
|
|
|
for (DenseMap<Function*, unsigned>::iterator Iter = ReturnNodes.begin();
|
|
Iter != ReturnNodes.end();
|
|
++Iter)
|
|
Iter->second = Translate[Iter->second];
|
|
|
|
for (DenseMap<Function*, unsigned>::iterator Iter = VarargNodes.begin();
|
|
Iter != VarargNodes.end();
|
|
++Iter)
|
|
Iter->second = Translate[Iter->second];
|
|
|
|
for (unsigned i = 0; i < Constraints.size(); ++i) {
|
|
Constraint &C = Constraints[i];
|
|
C.Src = Translate[C.Src];
|
|
C.Dest = Translate[C.Dest];
|
|
}
|
|
|
|
GraphNodes.swap(NewGraphNodes);
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa"
|
|
}
|
|
|
|
/// The technique used here is described in "Exploiting Pointer and Location
|
|
/// Equivalence to Optimize Pointer Analysis. In the 14th International Static
|
|
/// Analysis Symposium (SAS), August 2007." It is known as the "HVN" algorithm,
|
|
/// and is equivalent to value numbering the collapsed constraint graph without
|
|
/// evaluating unions. This is used as a pre-pass to HU in order to resolve
|
|
/// first order pointer dereferences and speed up/reduce memory usage of HU.
|
|
/// Running both is equivalent to HRU without the iteration
|
|
/// HVN in more detail:
|
|
/// Imagine the set of constraints was simply straight line code with no loops
|
|
/// (we eliminate cycles, so there are no loops), such as:
|
|
/// E = &D
|
|
/// E = &C
|
|
/// E = F
|
|
/// F = G
|
|
/// G = F
|
|
/// Applying value numbering to this code tells us:
|
|
/// G == F == E
|
|
///
|
|
/// For HVN, this is as far as it goes. We assign new value numbers to every
|
|
/// "address node", and every "reference node".
|
|
/// To get the optimal result for this, we use a DFS + SCC (since all nodes in a
|
|
/// cycle must have the same value number since the = operation is really
|
|
/// inclusion, not overwrite), and value number nodes we receive points-to sets
|
|
/// before we value our own node.
|
|
/// The advantage of HU over HVN is that HU considers the inclusion property, so
|
|
/// that if you have
|
|
/// E = &D
|
|
/// E = &C
|
|
/// E = F
|
|
/// F = G
|
|
/// F = &D
|
|
/// G = F
|
|
/// HU will determine that G == F == E. HVN will not, because it cannot prove
|
|
/// that the points to information ends up being the same because they all
|
|
/// receive &D from E anyway.
|
|
|
|
void Andersens::HVN() {
|
|
DOUT << "Beginning HVN\n";
|
|
// Build a predecessor graph. This is like our constraint graph with the
|
|
// edges going in the opposite direction, and there are edges for all the
|
|
// constraints, instead of just copy constraints. We also build implicit
|
|
// edges for constraints are implied but not explicit. I.E for the constraint
|
|
// a = &b, we add implicit edges *a = b. This helps us capture more cycles
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
|
|
Constraint &C = Constraints[i];
|
|
if (C.Type == Constraint::AddressOf) {
|
|
GraphNodes[C.Src].AddressTaken = true;
|
|
GraphNodes[C.Src].Direct = false;
|
|
|
|
// Dest = &src edge
|
|
unsigned AdrNode = C.Src + FirstAdrNode;
|
|
if (!GraphNodes[C.Dest].PredEdges)
|
|
GraphNodes[C.Dest].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[C.Dest].PredEdges->set(AdrNode);
|
|
|
|
// *Dest = src edge
|
|
unsigned RefNode = C.Dest + FirstRefNode;
|
|
if (!GraphNodes[RefNode].ImplicitPredEdges)
|
|
GraphNodes[RefNode].ImplicitPredEdges = new SparseBitVector<>;
|
|
GraphNodes[RefNode].ImplicitPredEdges->set(C.Src);
|
|
} else if (C.Type == Constraint::Load) {
|
|
if (C.Offset == 0) {
|
|
// dest = *src edge
|
|
if (!GraphNodes[C.Dest].PredEdges)
|
|
GraphNodes[C.Dest].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[C.Dest].PredEdges->set(C.Src + FirstRefNode);
|
|
} else {
|
|
GraphNodes[C.Dest].Direct = false;
|
|
}
|
|
} else if (C.Type == Constraint::Store) {
|
|
if (C.Offset == 0) {
|
|
// *dest = src edge
|
|
unsigned RefNode = C.Dest + FirstRefNode;
|
|
if (!GraphNodes[RefNode].PredEdges)
|
|
GraphNodes[RefNode].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[RefNode].PredEdges->set(C.Src);
|
|
}
|
|
} else {
|
|
// Dest = Src edge and *Dest = *Src edge
|
|
if (!GraphNodes[C.Dest].PredEdges)
|
|
GraphNodes[C.Dest].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[C.Dest].PredEdges->set(C.Src);
|
|
unsigned RefNode = C.Dest + FirstRefNode;
|
|
if (!GraphNodes[RefNode].ImplicitPredEdges)
|
|
GraphNodes[RefNode].ImplicitPredEdges = new SparseBitVector<>;
|
|
GraphNodes[RefNode].ImplicitPredEdges->set(C.Src + FirstRefNode);
|
|
}
|
|
}
|
|
PEClass = 1;
|
|
// Do SCC finding first to condense our predecessor graph
|
|
DFSNumber = 0;
|
|
Node2DFS.insert(Node2DFS.begin(), GraphNodes.size(), 0);
|
|
Node2Deleted.insert(Node2Deleted.begin(), GraphNodes.size(), false);
|
|
Node2Visited.insert(Node2Visited.begin(), GraphNodes.size(), false);
|
|
|
|
for (unsigned i = 0; i < FirstRefNode; ++i) {
|
|
unsigned Node = VSSCCRep[i];
|
|
if (!Node2Visited[Node])
|
|
HVNValNum(Node);
|
|
}
|
|
for (BitVectorMap::iterator Iter = Set2PEClass.begin();
|
|
Iter != Set2PEClass.end();
|
|
++Iter)
|
|
delete Iter->first;
|
|
Set2PEClass.clear();
|
|
Node2DFS.clear();
|
|
Node2Deleted.clear();
|
|
Node2Visited.clear();
|
|
DOUT << "Finished HVN\n";
|
|
|
|
}
|
|
|
|
/// This is the workhorse of HVN value numbering. We combine SCC finding at the
|
|
/// same time because it's easy.
|
|
void Andersens::HVNValNum(unsigned NodeIndex) {
|
|
unsigned MyDFS = DFSNumber++;
|
|
Node *N = &GraphNodes[NodeIndex];
|
|
Node2Visited[NodeIndex] = true;
|
|
Node2DFS[NodeIndex] = MyDFS;
|
|
|
|
// First process all our explicit edges
|
|
if (N->PredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->PredEdges->begin();
|
|
Iter != N->PredEdges->end();
|
|
++Iter) {
|
|
unsigned j = VSSCCRep[*Iter];
|
|
if (!Node2Deleted[j]) {
|
|
if (!Node2Visited[j])
|
|
HVNValNum(j);
|
|
if (Node2DFS[NodeIndex] > Node2DFS[j])
|
|
Node2DFS[NodeIndex] = Node2DFS[j];
|
|
}
|
|
}
|
|
|
|
// Now process all the implicit edges
|
|
if (N->ImplicitPredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->ImplicitPredEdges->begin();
|
|
Iter != N->ImplicitPredEdges->end();
|
|
++Iter) {
|
|
unsigned j = VSSCCRep[*Iter];
|
|
if (!Node2Deleted[j]) {
|
|
if (!Node2Visited[j])
|
|
HVNValNum(j);
|
|
if (Node2DFS[NodeIndex] > Node2DFS[j])
|
|
Node2DFS[NodeIndex] = Node2DFS[j];
|
|
}
|
|
}
|
|
|
|
// See if we found any cycles
|
|
if (MyDFS == Node2DFS[NodeIndex]) {
|
|
while (!SCCStack.empty() && Node2DFS[SCCStack.top()] >= MyDFS) {
|
|
unsigned CycleNodeIndex = SCCStack.top();
|
|
Node *CycleNode = &GraphNodes[CycleNodeIndex];
|
|
VSSCCRep[CycleNodeIndex] = NodeIndex;
|
|
// Unify the nodes
|
|
N->Direct &= CycleNode->Direct;
|
|
|
|
if (CycleNode->PredEdges) {
|
|
if (!N->PredEdges)
|
|
N->PredEdges = new SparseBitVector<>;
|
|
*(N->PredEdges) |= CycleNode->PredEdges;
|
|
delete CycleNode->PredEdges;
|
|
CycleNode->PredEdges = NULL;
|
|
}
|
|
if (CycleNode->ImplicitPredEdges) {
|
|
if (!N->ImplicitPredEdges)
|
|
N->ImplicitPredEdges = new SparseBitVector<>;
|
|
*(N->ImplicitPredEdges) |= CycleNode->ImplicitPredEdges;
|
|
delete CycleNode->ImplicitPredEdges;
|
|
CycleNode->ImplicitPredEdges = NULL;
|
|
}
|
|
|
|
SCCStack.pop();
|
|
}
|
|
|
|
Node2Deleted[NodeIndex] = true;
|
|
|
|
if (!N->Direct) {
|
|
GraphNodes[NodeIndex].PointerEquivLabel = PEClass++;
|
|
return;
|
|
}
|
|
|
|
// Collect labels of successor nodes
|
|
bool AllSame = true;
|
|
unsigned First = ~0;
|
|
SparseBitVector<> *Labels = new SparseBitVector<>;
|
|
bool Used = false;
|
|
|
|
if (N->PredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->PredEdges->begin();
|
|
Iter != N->PredEdges->end();
|
|
++Iter) {
|
|
unsigned j = VSSCCRep[*Iter];
|
|
unsigned Label = GraphNodes[j].PointerEquivLabel;
|
|
// Ignore labels that are equal to us or non-pointers
|
|
if (j == NodeIndex || Label == 0)
|
|
continue;
|
|
if (First == (unsigned)~0)
|
|
First = Label;
|
|
else if (First != Label)
|
|
AllSame = false;
|
|
Labels->set(Label);
|
|
}
|
|
|
|
// We either have a non-pointer, a copy of an existing node, or a new node.
|
|
// Assign the appropriate pointer equivalence label.
|
|
if (Labels->empty()) {
|
|
GraphNodes[NodeIndex].PointerEquivLabel = 0;
|
|
} else if (AllSame) {
|
|
GraphNodes[NodeIndex].PointerEquivLabel = First;
|
|
} else {
|
|
GraphNodes[NodeIndex].PointerEquivLabel = Set2PEClass[Labels];
|
|
if (GraphNodes[NodeIndex].PointerEquivLabel == 0) {
|
|
unsigned EquivClass = PEClass++;
|
|
Set2PEClass[Labels] = EquivClass;
|
|
GraphNodes[NodeIndex].PointerEquivLabel = EquivClass;
|
|
Used = true;
|
|
}
|
|
}
|
|
if (!Used)
|
|
delete Labels;
|
|
} else {
|
|
SCCStack.push(NodeIndex);
|
|
}
|
|
}
|
|
|
|
/// The technique used here is described in "Exploiting Pointer and Location
|
|
/// Equivalence to Optimize Pointer Analysis. In the 14th International Static
|
|
/// Analysis Symposium (SAS), August 2007." It is known as the "HU" algorithm,
|
|
/// and is equivalent to value numbering the collapsed constraint graph
|
|
/// including evaluating unions.
|
|
void Andersens::HU() {
|
|
DOUT << "Beginning HU\n";
|
|
// Build a predecessor graph. This is like our constraint graph with the
|
|
// edges going in the opposite direction, and there are edges for all the
|
|
// constraints, instead of just copy constraints. We also build implicit
|
|
// edges for constraints are implied but not explicit. I.E for the constraint
|
|
// a = &b, we add implicit edges *a = b. This helps us capture more cycles
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
|
|
Constraint &C = Constraints[i];
|
|
if (C.Type == Constraint::AddressOf) {
|
|
GraphNodes[C.Src].AddressTaken = true;
|
|
GraphNodes[C.Src].Direct = false;
|
|
|
|
GraphNodes[C.Dest].PointsTo->set(C.Src);
|
|
// *Dest = src edge
|
|
unsigned RefNode = C.Dest + FirstRefNode;
|
|
if (!GraphNodes[RefNode].ImplicitPredEdges)
|
|
GraphNodes[RefNode].ImplicitPredEdges = new SparseBitVector<>;
|
|
GraphNodes[RefNode].ImplicitPredEdges->set(C.Src);
|
|
GraphNodes[C.Src].PointedToBy->set(C.Dest);
|
|
} else if (C.Type == Constraint::Load) {
|
|
if (C.Offset == 0) {
|
|
// dest = *src edge
|
|
if (!GraphNodes[C.Dest].PredEdges)
|
|
GraphNodes[C.Dest].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[C.Dest].PredEdges->set(C.Src + FirstRefNode);
|
|
} else {
|
|
GraphNodes[C.Dest].Direct = false;
|
|
}
|
|
} else if (C.Type == Constraint::Store) {
|
|
if (C.Offset == 0) {
|
|
// *dest = src edge
|
|
unsigned RefNode = C.Dest + FirstRefNode;
|
|
if (!GraphNodes[RefNode].PredEdges)
|
|
GraphNodes[RefNode].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[RefNode].PredEdges->set(C.Src);
|
|
}
|
|
} else {
|
|
// Dest = Src edge and *Dest = *Src edg
|
|
if (!GraphNodes[C.Dest].PredEdges)
|
|
GraphNodes[C.Dest].PredEdges = new SparseBitVector<>;
|
|
GraphNodes[C.Dest].PredEdges->set(C.Src);
|
|
unsigned RefNode = C.Dest + FirstRefNode;
|
|
if (!GraphNodes[RefNode].ImplicitPredEdges)
|
|
GraphNodes[RefNode].ImplicitPredEdges = new SparseBitVector<>;
|
|
GraphNodes[RefNode].ImplicitPredEdges->set(C.Src + FirstRefNode);
|
|
}
|
|
}
|
|
PEClass = 1;
|
|
// Do SCC finding first to condense our predecessor graph
|
|
DFSNumber = 0;
|
|
Node2DFS.insert(Node2DFS.begin(), GraphNodes.size(), 0);
|
|
Node2Deleted.insert(Node2Deleted.begin(), GraphNodes.size(), false);
|
|
Node2Visited.insert(Node2Visited.begin(), GraphNodes.size(), false);
|
|
|
|
for (unsigned i = 0; i < FirstRefNode; ++i) {
|
|
if (FindNode(i) == i) {
|
|
unsigned Node = VSSCCRep[i];
|
|
if (!Node2Visited[Node])
|
|
Condense(Node);
|
|
}
|
|
}
|
|
|
|
// Reset tables for actual labeling
|
|
Node2DFS.clear();
|
|
Node2Visited.clear();
|
|
Node2Deleted.clear();
|
|
// Pre-grow our densemap so that we don't get really bad behavior
|
|
Set2PEClass.resize(GraphNodes.size());
|
|
|
|
// Visit the condensed graph and generate pointer equivalence labels.
|
|
Node2Visited.insert(Node2Visited.begin(), GraphNodes.size(), false);
|
|
for (unsigned i = 0; i < FirstRefNode; ++i) {
|
|
if (FindNode(i) == i) {
|
|
unsigned Node = VSSCCRep[i];
|
|
if (!Node2Visited[Node])
|
|
HUValNum(Node);
|
|
}
|
|
}
|
|
// PEClass nodes will be deleted by the deleting of N->PointsTo in our caller.
|
|
Set2PEClass.clear();
|
|
DOUT << "Finished HU\n";
|
|
}
|
|
|
|
|
|
/// Implementation of standard Tarjan SCC algorithm as modified by Nuutilla.
|
|
void Andersens::Condense(unsigned NodeIndex) {
|
|
unsigned MyDFS = DFSNumber++;
|
|
Node *N = &GraphNodes[NodeIndex];
|
|
Node2Visited[NodeIndex] = true;
|
|
Node2DFS[NodeIndex] = MyDFS;
|
|
|
|
// First process all our explicit edges
|
|
if (N->PredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->PredEdges->begin();
|
|
Iter != N->PredEdges->end();
|
|
++Iter) {
|
|
unsigned j = VSSCCRep[*Iter];
|
|
if (!Node2Deleted[j]) {
|
|
if (!Node2Visited[j])
|
|
Condense(j);
|
|
if (Node2DFS[NodeIndex] > Node2DFS[j])
|
|
Node2DFS[NodeIndex] = Node2DFS[j];
|
|
}
|
|
}
|
|
|
|
// Now process all the implicit edges
|
|
if (N->ImplicitPredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->ImplicitPredEdges->begin();
|
|
Iter != N->ImplicitPredEdges->end();
|
|
++Iter) {
|
|
unsigned j = VSSCCRep[*Iter];
|
|
if (!Node2Deleted[j]) {
|
|
if (!Node2Visited[j])
|
|
Condense(j);
|
|
if (Node2DFS[NodeIndex] > Node2DFS[j])
|
|
Node2DFS[NodeIndex] = Node2DFS[j];
|
|
}
|
|
}
|
|
|
|
// See if we found any cycles
|
|
if (MyDFS == Node2DFS[NodeIndex]) {
|
|
while (!SCCStack.empty() && Node2DFS[SCCStack.top()] >= MyDFS) {
|
|
unsigned CycleNodeIndex = SCCStack.top();
|
|
Node *CycleNode = &GraphNodes[CycleNodeIndex];
|
|
VSSCCRep[CycleNodeIndex] = NodeIndex;
|
|
// Unify the nodes
|
|
N->Direct &= CycleNode->Direct;
|
|
|
|
*(N->PointsTo) |= CycleNode->PointsTo;
|
|
delete CycleNode->PointsTo;
|
|
CycleNode->PointsTo = NULL;
|
|
if (CycleNode->PredEdges) {
|
|
if (!N->PredEdges)
|
|
N->PredEdges = new SparseBitVector<>;
|
|
*(N->PredEdges) |= CycleNode->PredEdges;
|
|
delete CycleNode->PredEdges;
|
|
CycleNode->PredEdges = NULL;
|
|
}
|
|
if (CycleNode->ImplicitPredEdges) {
|
|
if (!N->ImplicitPredEdges)
|
|
N->ImplicitPredEdges = new SparseBitVector<>;
|
|
*(N->ImplicitPredEdges) |= CycleNode->ImplicitPredEdges;
|
|
delete CycleNode->ImplicitPredEdges;
|
|
CycleNode->ImplicitPredEdges = NULL;
|
|
}
|
|
SCCStack.pop();
|
|
}
|
|
|
|
Node2Deleted[NodeIndex] = true;
|
|
|
|
// Set up number of incoming edges for other nodes
|
|
if (N->PredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->PredEdges->begin();
|
|
Iter != N->PredEdges->end();
|
|
++Iter)
|
|
++GraphNodes[VSSCCRep[*Iter]].NumInEdges;
|
|
} else {
|
|
SCCStack.push(NodeIndex);
|
|
}
|
|
}
|
|
|
|
void Andersens::HUValNum(unsigned NodeIndex) {
|
|
Node *N = &GraphNodes[NodeIndex];
|
|
Node2Visited[NodeIndex] = true;
|
|
|
|
// Eliminate dereferences of non-pointers for those non-pointers we have
|
|
// already identified. These are ref nodes whose non-ref node:
|
|
// 1. Has already been visited determined to point to nothing (and thus, a
|
|
// dereference of it must point to nothing)
|
|
// 2. Any direct node with no predecessor edges in our graph and with no
|
|
// points-to set (since it can't point to anything either, being that it
|
|
// receives no points-to sets and has none).
|
|
if (NodeIndex >= FirstRefNode) {
|
|
unsigned j = VSSCCRep[FindNode(NodeIndex - FirstRefNode)];
|
|
if ((Node2Visited[j] && !GraphNodes[j].PointerEquivLabel)
|
|
|| (GraphNodes[j].Direct && !GraphNodes[j].PredEdges
|
|
&& GraphNodes[j].PointsTo->empty())){
|
|
return;
|
|
}
|
|
}
|
|
// Process all our explicit edges
|
|
if (N->PredEdges)
|
|
for (SparseBitVector<>::iterator Iter = N->PredEdges->begin();
|
|
Iter != N->PredEdges->end();
|
|
++Iter) {
|
|
unsigned j = VSSCCRep[*Iter];
|
|
if (!Node2Visited[j])
|
|
HUValNum(j);
|
|
|
|
// If this edge turned out to be the same as us, or got no pointer
|
|
// equivalence label (and thus points to nothing) , just decrement our
|
|
// incoming edges and continue.
|
|
if (j == NodeIndex || GraphNodes[j].PointerEquivLabel == 0) {
|
|
--GraphNodes[j].NumInEdges;
|
|
continue;
|
|
}
|
|
|
|
*(N->PointsTo) |= GraphNodes[j].PointsTo;
|
|
|
|
// If we didn't end up storing this in the hash, and we're done with all
|
|
// the edges, we don't need the points-to set anymore.
|
|
--GraphNodes[j].NumInEdges;
|
|
if (!GraphNodes[j].NumInEdges && !GraphNodes[j].StoredInHash) {
|
|
delete GraphNodes[j].PointsTo;
|
|
GraphNodes[j].PointsTo = NULL;
|
|
}
|
|
}
|
|
// If this isn't a direct node, generate a fresh variable.
|
|
if (!N->Direct) {
|
|
N->PointsTo->set(FirstRefNode + NodeIndex);
|
|
}
|
|
|
|
// See If we have something equivalent to us, if not, generate a new
|
|
// equivalence class.
|
|
if (N->PointsTo->empty()) {
|
|
delete N->PointsTo;
|
|
N->PointsTo = NULL;
|
|
} else {
|
|
if (N->Direct) {
|
|
N->PointerEquivLabel = Set2PEClass[N->PointsTo];
|
|
if (N->PointerEquivLabel == 0) {
|
|
unsigned EquivClass = PEClass++;
|
|
N->StoredInHash = true;
|
|
Set2PEClass[N->PointsTo] = EquivClass;
|
|
N->PointerEquivLabel = EquivClass;
|
|
}
|
|
} else {
|
|
N->PointerEquivLabel = PEClass++;
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Rewrite our list of constraints so that pointer equivalent nodes are
|
|
/// replaced by their the pointer equivalence class representative.
|
|
void Andersens::RewriteConstraints() {
|
|
std::vector<Constraint> NewConstraints;
|
|
DenseSet<Constraint, ConstraintKeyInfo> Seen;
|
|
|
|
PEClass2Node.clear();
|
|
PENLEClass2Node.clear();
|
|
|
|
// We may have from 1 to Graphnodes + 1 equivalence classes.
|
|
PEClass2Node.insert(PEClass2Node.begin(), GraphNodes.size() + 1, -1);
|
|
PENLEClass2Node.insert(PENLEClass2Node.begin(), GraphNodes.size() + 1, -1);
|
|
|
|
// Rewrite constraints, ignoring non-pointer constraints, uniting equivalent
|
|
// nodes, and rewriting constraints to use the representative nodes.
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
|
|
Constraint &C = Constraints[i];
|
|
unsigned RHSNode = FindNode(C.Src);
|
|
unsigned LHSNode = FindNode(C.Dest);
|
|
unsigned RHSLabel = GraphNodes[VSSCCRep[RHSNode]].PointerEquivLabel;
|
|
unsigned LHSLabel = GraphNodes[VSSCCRep[LHSNode]].PointerEquivLabel;
|
|
|
|
// First we try to eliminate constraints for things we can prove don't point
|
|
// to anything.
|
|
if (LHSLabel == 0) {
|
|
DEBUG(PrintNode(&GraphNodes[LHSNode]));
|
|
DOUT << " is a non-pointer, ignoring constraint.\n";
|
|
continue;
|
|
}
|
|
if (RHSLabel == 0) {
|
|
DEBUG(PrintNode(&GraphNodes[RHSNode]));
|
|
DOUT << " is a non-pointer, ignoring constraint.\n";
|
|
continue;
|
|
}
|
|
// This constraint may be useless, and it may become useless as we translate
|
|
// it.
|
|
if (C.Src == C.Dest && C.Type == Constraint::Copy)
|
|
continue;
|
|
|
|
C.Src = FindEquivalentNode(RHSNode, RHSLabel);
|
|
C.Dest = FindEquivalentNode(FindNode(LHSNode), LHSLabel);
|
|
if ((C.Src == C.Dest && C.Type == Constraint::Copy)
|
|
|| Seen.count(C))
|
|
continue;
|
|
|
|
Seen.insert(C);
|
|
NewConstraints.push_back(C);
|
|
}
|
|
Constraints.swap(NewConstraints);
|
|
PEClass2Node.clear();
|
|
}
|
|
|
|
/// See if we have a node that is pointer equivalent to the one being asked
|
|
/// about, and if so, unite them and return the equivalent node. Otherwise,
|
|
/// return the original node.
|
|
unsigned Andersens::FindEquivalentNode(unsigned NodeIndex,
|
|
unsigned NodeLabel) {
|
|
if (!GraphNodes[NodeIndex].AddressTaken) {
|
|
if (PEClass2Node[NodeLabel] != -1) {
|
|
// We found an existing node with the same pointer label, so unify them.
|
|
// We specifically request that Union-By-Rank not be used so that
|
|
// PEClass2Node[NodeLabel] U= NodeIndex and not the other way around.
|
|
return UniteNodes(PEClass2Node[NodeLabel], NodeIndex, false);
|
|
} else {
|
|
PEClass2Node[NodeLabel] = NodeIndex;
|
|
PENLEClass2Node[NodeLabel] = NodeIndex;
|
|
}
|
|
} else if (PENLEClass2Node[NodeLabel] == -1) {
|
|
PENLEClass2Node[NodeLabel] = NodeIndex;
|
|
}
|
|
|
|
return NodeIndex;
|
|
}
|
|
|
|
void Andersens::PrintLabels() {
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
if (i < FirstRefNode) {
|
|
PrintNode(&GraphNodes[i]);
|
|
} else if (i < FirstAdrNode) {
|
|
DOUT << "REF(";
|
|
PrintNode(&GraphNodes[i-FirstRefNode]);
|
|
DOUT <<")";
|
|
} else {
|
|
DOUT << "ADR(";
|
|
PrintNode(&GraphNodes[i-FirstAdrNode]);
|
|
DOUT <<")";
|
|
}
|
|
|
|
DOUT << " has pointer label " << GraphNodes[i].PointerEquivLabel
|
|
<< " and SCC rep " << VSSCCRep[i]
|
|
<< " and is " << (GraphNodes[i].Direct ? "Direct" : "Not direct")
|
|
<< "\n";
|
|
}
|
|
}
|
|
|
|
/// The technique used here is described in "The Ant and the
|
|
/// Grasshopper: Fast and Accurate Pointer Analysis for Millions of
|
|
/// Lines of Code. In Programming Language Design and Implementation
|
|
/// (PLDI), June 2007." It is known as the "HCD" (Hybrid Cycle
|
|
/// Detection) algorithm. It is called a hybrid because it performs an
|
|
/// offline analysis and uses its results during the solving (online)
|
|
/// phase. This is just the offline portion; the results of this
|
|
/// operation are stored in SDT and are later used in SolveContraints()
|
|
/// and UniteNodes().
|
|
void Andersens::HCD() {
|
|
DOUT << "Starting HCD.\n";
|
|
HCDSCCRep.resize(GraphNodes.size());
|
|
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
GraphNodes[i].Edges = new SparseBitVector<>;
|
|
HCDSCCRep[i] = i;
|
|
}
|
|
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
|
|
Constraint &C = Constraints[i];
|
|
assert (C.Src < GraphNodes.size() && C.Dest < GraphNodes.size());
|
|
if (C.Type == Constraint::AddressOf) {
|
|
continue;
|
|
} else if (C.Type == Constraint::Load) {
|
|
if( C.Offset == 0 )
|
|
GraphNodes[C.Dest].Edges->set(C.Src + FirstRefNode);
|
|
} else if (C.Type == Constraint::Store) {
|
|
if( C.Offset == 0 )
|
|
GraphNodes[C.Dest + FirstRefNode].Edges->set(C.Src);
|
|
} else {
|
|
GraphNodes[C.Dest].Edges->set(C.Src);
|
|
}
|
|
}
|
|
|
|
Node2DFS.insert(Node2DFS.begin(), GraphNodes.size(), 0);
|
|
Node2Deleted.insert(Node2Deleted.begin(), GraphNodes.size(), false);
|
|
Node2Visited.insert(Node2Visited.begin(), GraphNodes.size(), false);
|
|
SDT.insert(SDT.begin(), GraphNodes.size() / 2, -1);
|
|
|
|
DFSNumber = 0;
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
unsigned Node = HCDSCCRep[i];
|
|
if (!Node2Deleted[Node])
|
|
Search(Node);
|
|
}
|
|
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i)
|
|
if (GraphNodes[i].Edges != NULL) {
|
|
delete GraphNodes[i].Edges;
|
|
GraphNodes[i].Edges = NULL;
|
|
}
|
|
|
|
while( !SCCStack.empty() )
|
|
SCCStack.pop();
|
|
|
|
Node2DFS.clear();
|
|
Node2Visited.clear();
|
|
Node2Deleted.clear();
|
|
HCDSCCRep.clear();
|
|
DOUT << "HCD complete.\n";
|
|
}
|
|
|
|
// Component of HCD:
|
|
// Use Nuutila's variant of Tarjan's algorithm to detect
|
|
// Strongly-Connected Components (SCCs). For non-trivial SCCs
|
|
// containing ref nodes, insert the appropriate information in SDT.
|
|
void Andersens::Search(unsigned Node) {
|
|
unsigned MyDFS = DFSNumber++;
|
|
|
|
Node2Visited[Node] = true;
|
|
Node2DFS[Node] = MyDFS;
|
|
|
|
for (SparseBitVector<>::iterator Iter = GraphNodes[Node].Edges->begin(),
|
|
End = GraphNodes[Node].Edges->end();
|
|
Iter != End;
|
|
++Iter) {
|
|
unsigned J = HCDSCCRep[*Iter];
|
|
assert(GraphNodes[J].isRep() && "Debug check; must be representative");
|
|
if (!Node2Deleted[J]) {
|
|
if (!Node2Visited[J])
|
|
Search(J);
|
|
if (Node2DFS[Node] > Node2DFS[J])
|
|
Node2DFS[Node] = Node2DFS[J];
|
|
}
|
|
}
|
|
|
|
if( MyDFS != Node2DFS[Node] ) {
|
|
SCCStack.push(Node);
|
|
return;
|
|
}
|
|
|
|
// This node is the root of a SCC, so process it.
|
|
//
|
|
// If the SCC is "non-trivial" (not a singleton) and contains a reference
|
|
// node, we place this SCC into SDT. We unite the nodes in any case.
|
|
if (!SCCStack.empty() && Node2DFS[SCCStack.top()] >= MyDFS) {
|
|
SparseBitVector<> SCC;
|
|
|
|
SCC.set(Node);
|
|
|
|
bool Ref = (Node >= FirstRefNode);
|
|
|
|
Node2Deleted[Node] = true;
|
|
|
|
do {
|
|
unsigned P = SCCStack.top(); SCCStack.pop();
|
|
Ref |= (P >= FirstRefNode);
|
|
SCC.set(P);
|
|
HCDSCCRep[P] = Node;
|
|
} while (!SCCStack.empty() && Node2DFS[SCCStack.top()] >= MyDFS);
|
|
|
|
if (Ref) {
|
|
unsigned Rep = SCC.find_first();
|
|
assert(Rep < FirstRefNode && "The SCC didn't have a non-Ref node!");
|
|
|
|
SparseBitVector<>::iterator i = SCC.begin();
|
|
|
|
// Skip over the non-ref nodes
|
|
while( *i < FirstRefNode )
|
|
++i;
|
|
|
|
while( i != SCC.end() )
|
|
SDT[ (*i++) - FirstRefNode ] = Rep;
|
|
}
|
|
}
|
|
}
|
|
|
|
|
|
/// Optimize the constraints by performing offline variable substitution and
|
|
/// other optimizations.
|
|
void Andersens::OptimizeConstraints() {
|
|
DOUT << "Beginning constraint optimization\n";
|
|
|
|
SDTActive = false;
|
|
|
|
// Function related nodes need to stay in the same relative position and can't
|
|
// be location equivalent.
|
|
for (std::map<unsigned, unsigned>::iterator Iter = MaxK.begin();
|
|
Iter != MaxK.end();
|
|
++Iter) {
|
|
for (unsigned i = Iter->first;
|
|
i != Iter->first + Iter->second;
|
|
++i) {
|
|
GraphNodes[i].AddressTaken = true;
|
|
GraphNodes[i].Direct = false;
|
|
}
|
|
}
|
|
|
|
ClumpAddressTaken();
|
|
FirstRefNode = GraphNodes.size();
|
|
FirstAdrNode = FirstRefNode + GraphNodes.size();
|
|
GraphNodes.insert(GraphNodes.end(), 2 * GraphNodes.size(),
|
|
Node(false));
|
|
VSSCCRep.resize(GraphNodes.size());
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
VSSCCRep[i] = i;
|
|
}
|
|
HVN();
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
Node *N = &GraphNodes[i];
|
|
delete N->PredEdges;
|
|
N->PredEdges = NULL;
|
|
delete N->ImplicitPredEdges;
|
|
N->ImplicitPredEdges = NULL;
|
|
}
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa-labels"
|
|
DEBUG(PrintLabels());
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa"
|
|
RewriteConstraints();
|
|
// Delete the adr nodes.
|
|
GraphNodes.resize(FirstRefNode * 2);
|
|
|
|
// Now perform HU
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
Node *N = &GraphNodes[i];
|
|
if (FindNode(i) == i) {
|
|
N->PointsTo = new SparseBitVector<>;
|
|
N->PointedToBy = new SparseBitVector<>;
|
|
// Reset our labels
|
|
}
|
|
VSSCCRep[i] = i;
|
|
N->PointerEquivLabel = 0;
|
|
}
|
|
HU();
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa-labels"
|
|
DEBUG(PrintLabels());
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa"
|
|
RewriteConstraints();
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
if (FindNode(i) == i) {
|
|
Node *N = &GraphNodes[i];
|
|
delete N->PointsTo;
|
|
N->PointsTo = NULL;
|
|
delete N->PredEdges;
|
|
N->PredEdges = NULL;
|
|
delete N->ImplicitPredEdges;
|
|
N->ImplicitPredEdges = NULL;
|
|
delete N->PointedToBy;
|
|
N->PointedToBy = NULL;
|
|
}
|
|
}
|
|
|
|
// perform Hybrid Cycle Detection (HCD)
|
|
HCD();
|
|
SDTActive = true;
|
|
|
|
// No longer any need for the upper half of GraphNodes (for ref nodes).
|
|
GraphNodes.erase(GraphNodes.begin() + FirstRefNode, GraphNodes.end());
|
|
|
|
// HCD complete.
|
|
|
|
DOUT << "Finished constraint optimization\n";
|
|
FirstRefNode = 0;
|
|
FirstAdrNode = 0;
|
|
}
|
|
|
|
/// Unite pointer but not location equivalent variables, now that the constraint
|
|
/// graph is built.
|
|
void Andersens::UnitePointerEquivalences() {
|
|
DOUT << "Uniting remaining pointer equivalences\n";
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
if (GraphNodes[i].AddressTaken && GraphNodes[i].isRep()) {
|
|
unsigned Label = GraphNodes[i].PointerEquivLabel;
|
|
|
|
if (Label && PENLEClass2Node[Label] != -1)
|
|
UniteNodes(i, PENLEClass2Node[Label]);
|
|
}
|
|
}
|
|
DOUT << "Finished remaining pointer equivalences\n";
|
|
PENLEClass2Node.clear();
|
|
}
|
|
|
|
/// Create the constraint graph used for solving points-to analysis.
|
|
///
|
|
void Andersens::CreateConstraintGraph() {
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
|
|
Constraint &C = Constraints[i];
|
|
assert (C.Src < GraphNodes.size() && C.Dest < GraphNodes.size());
|
|
if (C.Type == Constraint::AddressOf)
|
|
GraphNodes[C.Dest].PointsTo->set(C.Src);
|
|
else if (C.Type == Constraint::Load)
|
|
GraphNodes[C.Src].Constraints.push_back(C);
|
|
else if (C.Type == Constraint::Store)
|
|
GraphNodes[C.Dest].Constraints.push_back(C);
|
|
else if (C.Offset != 0)
|
|
GraphNodes[C.Src].Constraints.push_back(C);
|
|
else
|
|
GraphNodes[C.Src].Edges->set(C.Dest);
|
|
}
|
|
}
|
|
|
|
// Perform DFS and cycle detection.
|
|
bool Andersens::QueryNode(unsigned Node) {
|
|
assert(GraphNodes[Node].isRep() && "Querying a non-rep node");
|
|
unsigned OurDFS = ++DFSNumber;
|
|
SparseBitVector<> ToErase;
|
|
SparseBitVector<> NewEdges;
|
|
Tarjan2DFS[Node] = OurDFS;
|
|
|
|
// Changed denotes a change from a recursive call that we will bubble up.
|
|
// Merged is set if we actually merge a node ourselves.
|
|
bool Changed = false, Merged = false;
|
|
|
|
for (SparseBitVector<>::iterator bi = GraphNodes[Node].Edges->begin();
|
|
bi != GraphNodes[Node].Edges->end();
|
|
++bi) {
|
|
unsigned RepNode = FindNode(*bi);
|
|
// If this edge points to a non-representative node but we are
|
|
// already planning to add an edge to its representative, we have no
|
|
// need for this edge anymore.
|
|
if (RepNode != *bi && NewEdges.test(RepNode)){
|
|
ToErase.set(*bi);
|
|
continue;
|
|
}
|
|
|
|
// Continue about our DFS.
|
|
if (!Tarjan2Deleted[RepNode]){
|
|
if (Tarjan2DFS[RepNode] == 0) {
|
|
Changed |= QueryNode(RepNode);
|
|
// May have been changed by QueryNode
|
|
RepNode = FindNode(RepNode);
|
|
}
|
|
if (Tarjan2DFS[RepNode] < Tarjan2DFS[Node])
|
|
Tarjan2DFS[Node] = Tarjan2DFS[RepNode];
|
|
}
|
|
|
|
// We may have just discovered that this node is part of a cycle, in
|
|
// which case we can also erase it.
|
|
if (RepNode != *bi) {
|
|
ToErase.set(*bi);
|
|
NewEdges.set(RepNode);
|
|
}
|
|
}
|
|
|
|
GraphNodes[Node].Edges->intersectWithComplement(ToErase);
|
|
GraphNodes[Node].Edges |= NewEdges;
|
|
|
|
// If this node is a root of a non-trivial SCC, place it on our
|
|
// worklist to be processed.
|
|
if (OurDFS == Tarjan2DFS[Node]) {
|
|
while (!SCCStack.empty() && Tarjan2DFS[SCCStack.top()] >= OurDFS) {
|
|
Node = UniteNodes(Node, SCCStack.top());
|
|
|
|
SCCStack.pop();
|
|
Merged = true;
|
|
}
|
|
Tarjan2Deleted[Node] = true;
|
|
|
|
if (Merged)
|
|
NextWL->insert(&GraphNodes[Node]);
|
|
} else {
|
|
SCCStack.push(Node);
|
|
}
|
|
|
|
return(Changed | Merged);
|
|
}
|
|
|
|
/// SolveConstraints - This stage iteratively processes the constraints list
|
|
/// propagating constraints (adding edges to the Nodes in the points-to graph)
|
|
/// until a fixed point is reached.
|
|
///
|
|
/// We use a variant of the technique called "Lazy Cycle Detection", which is
|
|
/// described in "The Ant and the Grasshopper: Fast and Accurate Pointer
|
|
/// Analysis for Millions of Lines of Code. In Programming Language Design and
|
|
/// Implementation (PLDI), June 2007."
|
|
/// The paper describes performing cycle detection one node at a time, which can
|
|
/// be expensive if there are no cycles, but there are long chains of nodes that
|
|
/// it heuristically believes are cycles (because it will DFS from each node
|
|
/// without state from previous nodes).
|
|
/// Instead, we use the heuristic to build a worklist of nodes to check, then
|
|
/// cycle detect them all at the same time to do this more cheaply. This
|
|
/// catches cycles slightly later than the original technique did, but does it
|
|
/// make significantly cheaper.
|
|
|
|
void Andersens::SolveConstraints() {
|
|
CurrWL = &w1;
|
|
NextWL = &w2;
|
|
|
|
OptimizeConstraints();
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa-constraints"
|
|
DEBUG(PrintConstraints());
|
|
#undef DEBUG_TYPE
|
|
#define DEBUG_TYPE "anders-aa"
|
|
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
Node *N = &GraphNodes[i];
|
|
N->PointsTo = new SparseBitVector<>;
|
|
N->OldPointsTo = new SparseBitVector<>;
|
|
N->Edges = new SparseBitVector<>;
|
|
}
|
|
CreateConstraintGraph();
|
|
UnitePointerEquivalences();
|
|
assert(SCCStack.empty() && "SCC Stack should be empty by now!");
|
|
Node2DFS.clear();
|
|
Node2Deleted.clear();
|
|
Node2DFS.insert(Node2DFS.begin(), GraphNodes.size(), 0);
|
|
Node2Deleted.insert(Node2Deleted.begin(), GraphNodes.size(), false);
|
|
DFSNumber = 0;
|
|
DenseSet<Constraint, ConstraintKeyInfo> Seen;
|
|
DenseSet<std::pair<unsigned,unsigned>, PairKeyInfo> EdgesChecked;
|
|
|
|
// Order graph and add initial nodes to work list.
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
Node *INode = &GraphNodes[i];
|
|
|
|
// Add to work list if it's a representative and can contribute to the
|
|
// calculation right now.
|
|
if (INode->isRep() && !INode->PointsTo->empty()
|
|
&& (!INode->Edges->empty() || !INode->Constraints.empty())) {
|
|
INode->Stamp();
|
|
CurrWL->insert(INode);
|
|
}
|
|
}
|
|
std::queue<unsigned int> TarjanWL;
|
|
#if !FULL_UNIVERSAL
|
|
// "Rep and special variables" - in order for HCD to maintain conservative
|
|
// results when !FULL_UNIVERSAL, we need to treat the special variables in
|
|
// the same way that the !FULL_UNIVERSAL tweak does throughout the rest of
|
|
// the analysis - it's ok to add edges from the special nodes, but never
|
|
// *to* the special nodes.
|
|
std::vector<unsigned int> RSV;
|
|
#endif
|
|
while( !CurrWL->empty() ) {
|
|
DOUT << "Starting iteration #" << ++NumIters << "\n";
|
|
|
|
Node* CurrNode;
|
|
unsigned CurrNodeIndex;
|
|
|
|
// Actual cycle checking code. We cycle check all of the lazy cycle
|
|
// candidates from the last iteration in one go.
|
|
if (!TarjanWL.empty()) {
|
|
DFSNumber = 0;
|
|
|
|
Tarjan2DFS.clear();
|
|
Tarjan2Deleted.clear();
|
|
while (!TarjanWL.empty()) {
|
|
unsigned int ToTarjan = TarjanWL.front();
|
|
TarjanWL.pop();
|
|
if (!Tarjan2Deleted[ToTarjan]
|
|
&& GraphNodes[ToTarjan].isRep()
|
|
&& Tarjan2DFS[ToTarjan] == 0)
|
|
QueryNode(ToTarjan);
|
|
}
|
|
}
|
|
|
|
// Add to work list if it's a representative and can contribute to the
|
|
// calculation right now.
|
|
while( (CurrNode = CurrWL->pop()) != NULL ) {
|
|
CurrNodeIndex = CurrNode - &GraphNodes[0];
|
|
CurrNode->Stamp();
|
|
|
|
|
|
// Figure out the changed points to bits
|
|
SparseBitVector<> CurrPointsTo;
|
|
CurrPointsTo.intersectWithComplement(CurrNode->PointsTo,
|
|
CurrNode->OldPointsTo);
|
|
if (CurrPointsTo.empty())
|
|
continue;
|
|
|
|
*(CurrNode->OldPointsTo) |= CurrPointsTo;
|
|
|
|
// Check the offline-computed equivalencies from HCD.
|
|
bool SCC = false;
|
|
unsigned Rep;
|
|
|
|
if (SDT[CurrNodeIndex] >= 0) {
|
|
SCC = true;
|
|
Rep = FindNode(SDT[CurrNodeIndex]);
|
|
|
|
#if !FULL_UNIVERSAL
|
|
RSV.clear();
|
|
#endif
|
|
for (SparseBitVector<>::iterator bi = CurrPointsTo.begin();
|
|
bi != CurrPointsTo.end(); ++bi) {
|
|
unsigned Node = FindNode(*bi);
|
|
#if !FULL_UNIVERSAL
|
|
if (Node < NumberSpecialNodes) {
|
|
RSV.push_back(Node);
|
|
continue;
|
|
}
|
|
#endif
|
|
Rep = UniteNodes(Rep,Node);
|
|
}
|
|
#if !FULL_UNIVERSAL
|
|
RSV.push_back(Rep);
|
|
#endif
|
|
|
|
NextWL->insert(&GraphNodes[Rep]);
|
|
|
|
if ( ! CurrNode->isRep() )
|
|
continue;
|
|
}
|
|
|
|
Seen.clear();
|
|
|
|
/* Now process the constraints for this node. */
|
|
for (std::list<Constraint>::iterator li = CurrNode->Constraints.begin();
|
|
li != CurrNode->Constraints.end(); ) {
|
|
li->Src = FindNode(li->Src);
|
|
li->Dest = FindNode(li->Dest);
|
|
|
|
// Delete redundant constraints
|
|
if( Seen.count(*li) ) {
|
|
std::list<Constraint>::iterator lk = li; li++;
|
|
|
|
CurrNode->Constraints.erase(lk);
|
|
++NumErased;
|
|
continue;
|
|
}
|
|
Seen.insert(*li);
|
|
|
|
// Src and Dest will be the vars we are going to process.
|
|
// This may look a bit ugly, but what it does is allow us to process
|
|
// both store and load constraints with the same code.
|
|
// Load constraints say that every member of our RHS solution has K
|
|
// added to it, and that variable gets an edge to LHS. We also union
|
|
// RHS+K's solution into the LHS solution.
|
|
// Store constraints say that every member of our LHS solution has K
|
|
// added to it, and that variable gets an edge from RHS. We also union
|
|
// RHS's solution into the LHS+K solution.
|
|
unsigned *Src;
|
|
unsigned *Dest;
|
|
unsigned K = li->Offset;
|
|
unsigned CurrMember;
|
|
if (li->Type == Constraint::Load) {
|
|
Src = &CurrMember;
|
|
Dest = &li->Dest;
|
|
} else if (li->Type == Constraint::Store) {
|
|
Src = &li->Src;
|
|
Dest = &CurrMember;
|
|
} else {
|
|
// TODO Handle offseted copy constraint
|
|
li++;
|
|
continue;
|
|
}
|
|
|
|
// See if we can use Hybrid Cycle Detection (that is, check
|
|
// if it was a statically detected offline equivalence that
|
|
// involves pointers; if so, remove the redundant constraints).
|
|
if( SCC && K == 0 ) {
|
|
#if FULL_UNIVERSAL
|
|
CurrMember = Rep;
|
|
|
|
if (GraphNodes[*Src].Edges->test_and_set(*Dest))
|
|
if (GraphNodes[*Dest].PointsTo |= *(GraphNodes[*Src].PointsTo))
|
|
NextWL->insert(&GraphNodes[*Dest]);
|
|
#else
|
|
for (unsigned i=0; i < RSV.size(); ++i) {
|
|
CurrMember = RSV[i];
|
|
|
|
if (*Dest < NumberSpecialNodes)
|
|
continue;
|
|
if (GraphNodes[*Src].Edges->test_and_set(*Dest))
|
|
if (GraphNodes[*Dest].PointsTo |= *(GraphNodes[*Src].PointsTo))
|
|
NextWL->insert(&GraphNodes[*Dest]);
|
|
}
|
|
#endif
|
|
// since all future elements of the points-to set will be
|
|
// equivalent to the current ones, the complex constraints
|
|
// become redundant.
|
|
//
|
|
std::list<Constraint>::iterator lk = li; li++;
|
|
#if !FULL_UNIVERSAL
|
|
// In this case, we can still erase the constraints when the
|
|
// elements of the points-to sets are referenced by *Dest,
|
|
// but not when they are referenced by *Src (i.e. for a Load
|
|
// constraint). This is because if another special variable is
|
|
// put into the points-to set later, we still need to add the
|
|
// new edge from that special variable.
|
|
if( lk->Type != Constraint::Load)
|
|
#endif
|
|
GraphNodes[CurrNodeIndex].Constraints.erase(lk);
|
|
} else {
|
|
const SparseBitVector<> &Solution = CurrPointsTo;
|
|
|
|
for (SparseBitVector<>::iterator bi = Solution.begin();
|
|
bi != Solution.end();
|
|
++bi) {
|
|
CurrMember = *bi;
|
|
|
|
// Need to increment the member by K since that is where we are
|
|
// supposed to copy to/from. Note that in positive weight cycles,
|
|
// which occur in address taking of fields, K can go past
|
|
// MaxK[CurrMember] elements, even though that is all it could point
|
|
// to.
|
|
if (K > 0 && K > MaxK[CurrMember])
|
|
continue;
|
|
else
|
|
CurrMember = FindNode(CurrMember + K);
|
|
|
|
// Add an edge to the graph, so we can just do regular
|
|
// bitmap ior next time. It may also let us notice a cycle.
|
|
#if !FULL_UNIVERSAL
|
|
if (*Dest < NumberSpecialNodes)
|
|
continue;
|
|
#endif
|
|
if (GraphNodes[*Src].Edges->test_and_set(*Dest))
|
|
if (GraphNodes[*Dest].PointsTo |= *(GraphNodes[*Src].PointsTo))
|
|
NextWL->insert(&GraphNodes[*Dest]);
|
|
|
|
}
|
|
li++;
|
|
}
|
|
}
|
|
SparseBitVector<> NewEdges;
|
|
SparseBitVector<> ToErase;
|
|
|
|
// Now all we have left to do is propagate points-to info along the
|
|
// edges, erasing the redundant edges.
|
|
for (SparseBitVector<>::iterator bi = CurrNode->Edges->begin();
|
|
bi != CurrNode->Edges->end();
|
|
++bi) {
|
|
|
|
unsigned DestVar = *bi;
|
|
unsigned Rep = FindNode(DestVar);
|
|
|
|
// If we ended up with this node as our destination, or we've already
|
|
// got an edge for the representative, delete the current edge.
|
|
if (Rep == CurrNodeIndex ||
|
|
(Rep != DestVar && NewEdges.test(Rep))) {
|
|
ToErase.set(DestVar);
|
|
continue;
|
|
}
|
|
|
|
std::pair<unsigned,unsigned> edge(CurrNodeIndex,Rep);
|
|
|
|
// This is where we do lazy cycle detection.
|
|
// If this is a cycle candidate (equal points-to sets and this
|
|
// particular edge has not been cycle-checked previously), add to the
|
|
// list to check for cycles on the next iteration.
|
|
if (!EdgesChecked.count(edge) &&
|
|
*(GraphNodes[Rep].PointsTo) == *(CurrNode->PointsTo)) {
|
|
EdgesChecked.insert(edge);
|
|
TarjanWL.push(Rep);
|
|
}
|
|
// Union the points-to sets into the dest
|
|
#if !FULL_UNIVERSAL
|
|
if (Rep >= NumberSpecialNodes)
|
|
#endif
|
|
if (GraphNodes[Rep].PointsTo |= CurrPointsTo) {
|
|
NextWL->insert(&GraphNodes[Rep]);
|
|
}
|
|
// If this edge's destination was collapsed, rewrite the edge.
|
|
if (Rep != DestVar) {
|
|
ToErase.set(DestVar);
|
|
NewEdges.set(Rep);
|
|
}
|
|
}
|
|
CurrNode->Edges->intersectWithComplement(ToErase);
|
|
CurrNode->Edges |= NewEdges;
|
|
}
|
|
|
|
// Switch to other work list.
|
|
WorkList* t = CurrWL; CurrWL = NextWL; NextWL = t;
|
|
}
|
|
|
|
|
|
Node2DFS.clear();
|
|
Node2Deleted.clear();
|
|
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
|
|
Node *N = &GraphNodes[i];
|
|
delete N->OldPointsTo;
|
|
delete N->Edges;
|
|
}
|
|
SDTActive = false;
|
|
SDT.clear();
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Union-Find
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
// Unite nodes First and Second, returning the one which is now the
|
|
// representative node. First and Second are indexes into GraphNodes
|
|
unsigned Andersens::UniteNodes(unsigned First, unsigned Second,
|
|
bool UnionByRank) {
|
|
assert (First < GraphNodes.size() && Second < GraphNodes.size() &&
|
|
"Attempting to merge nodes that don't exist");
|
|
|
|
Node *FirstNode = &GraphNodes[First];
|
|
Node *SecondNode = &GraphNodes[Second];
|
|
|
|
assert (SecondNode->isRep() && FirstNode->isRep() &&
|
|
"Trying to unite two non-representative nodes!");
|
|
if (First == Second)
|
|
return First;
|
|
|
|
if (UnionByRank) {
|
|
int RankFirst = (int) FirstNode ->NodeRep;
|
|
int RankSecond = (int) SecondNode->NodeRep;
|
|
|
|
// Rank starts at -1 and gets decremented as it increases.
|
|
// Translation: higher rank, lower NodeRep value, which is always negative.
|
|
if (RankFirst > RankSecond) {
|
|
unsigned t = First; First = Second; Second = t;
|
|
Node* tp = FirstNode; FirstNode = SecondNode; SecondNode = tp;
|
|
} else if (RankFirst == RankSecond) {
|
|
FirstNode->NodeRep = (unsigned) (RankFirst - 1);
|
|
}
|
|
}
|
|
|
|
SecondNode->NodeRep = First;
|
|
#if !FULL_UNIVERSAL
|
|
if (First >= NumberSpecialNodes)
|
|
#endif
|
|
if (FirstNode->PointsTo && SecondNode->PointsTo)
|
|
FirstNode->PointsTo |= *(SecondNode->PointsTo);
|
|
if (FirstNode->Edges && SecondNode->Edges)
|
|
FirstNode->Edges |= *(SecondNode->Edges);
|
|
if (!SecondNode->Constraints.empty())
|
|
FirstNode->Constraints.splice(FirstNode->Constraints.begin(),
|
|
SecondNode->Constraints);
|
|
if (FirstNode->OldPointsTo) {
|
|
delete FirstNode->OldPointsTo;
|
|
FirstNode->OldPointsTo = new SparseBitVector<>;
|
|
}
|
|
|
|
// Destroy interesting parts of the merged-from node.
|
|
delete SecondNode->OldPointsTo;
|
|
delete SecondNode->Edges;
|
|
delete SecondNode->PointsTo;
|
|
SecondNode->Edges = NULL;
|
|
SecondNode->PointsTo = NULL;
|
|
SecondNode->OldPointsTo = NULL;
|
|
|
|
NumUnified++;
|
|
DOUT << "Unified Node ";
|
|
DEBUG(PrintNode(FirstNode));
|
|
DOUT << " and Node ";
|
|
DEBUG(PrintNode(SecondNode));
|
|
DOUT << "\n";
|
|
|
|
if (SDTActive)
|
|
if (SDT[Second] >= 0)
|
|
if (SDT[First] < 0)
|
|
SDT[First] = SDT[Second];
|
|
else {
|
|
UniteNodes( FindNode(SDT[First]), FindNode(SDT[Second]) );
|
|
First = FindNode(First);
|
|
}
|
|
|
|
return First;
|
|
}
|
|
|
|
// Find the index into GraphNodes of the node representing Node, performing
|
|
// path compression along the way
|
|
unsigned Andersens::FindNode(unsigned NodeIndex) {
|
|
assert (NodeIndex < GraphNodes.size()
|
|
&& "Attempting to find a node that can't exist");
|
|
Node *N = &GraphNodes[NodeIndex];
|
|
if (N->isRep())
|
|
return NodeIndex;
|
|
else
|
|
return (N->NodeRep = FindNode(N->NodeRep));
|
|
}
|
|
|
|
//===----------------------------------------------------------------------===//
|
|
// Debugging Output
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
void Andersens::PrintNode(Node *N) {
|
|
if (N == &GraphNodes[UniversalSet]) {
|
|
cerr << "<universal>";
|
|
return;
|
|
} else if (N == &GraphNodes[NullPtr]) {
|
|
cerr << "<nullptr>";
|
|
return;
|
|
} else if (N == &GraphNodes[NullObject]) {
|
|
cerr << "<null>";
|
|
return;
|
|
}
|
|
if (!N->getValue()) {
|
|
cerr << "artificial" << (intptr_t) N;
|
|
return;
|
|
}
|
|
|
|
assert(N->getValue() != 0 && "Never set node label!");
|
|
Value *V = N->getValue();
|
|
if (Function *F = dyn_cast<Function>(V)) {
|
|
if (isa<PointerType>(F->getFunctionType()->getReturnType()) &&
|
|
N == &GraphNodes[getReturnNode(F)]) {
|
|
cerr << F->getName() << ":retval";
|
|
return;
|
|
} else if (F->getFunctionType()->isVarArg() &&
|
|
N == &GraphNodes[getVarargNode(F)]) {
|
|
cerr << F->getName() << ":vararg";
|
|
return;
|
|
}
|
|
}
|
|
|
|
if (Instruction *I = dyn_cast<Instruction>(V))
|
|
cerr << I->getParent()->getParent()->getName() << ":";
|
|
else if (Argument *Arg = dyn_cast<Argument>(V))
|
|
cerr << Arg->getParent()->getName() << ":";
|
|
|
|
if (V->hasName())
|
|
cerr << V->getName();
|
|
else
|
|
cerr << "(unnamed)";
|
|
|
|
if (isa<GlobalValue>(V) || isa<AllocationInst>(V))
|
|
if (N == &GraphNodes[getObject(V)])
|
|
cerr << "<mem>";
|
|
}
|
|
void Andersens::PrintConstraint(const Constraint &C) {
|
|
if (C.Type == Constraint::Store) {
|
|
cerr << "*";
|
|
if (C.Offset != 0)
|
|
cerr << "(";
|
|
}
|
|
PrintNode(&GraphNodes[C.Dest]);
|
|
if (C.Type == Constraint::Store && C.Offset != 0)
|
|
cerr << " + " << C.Offset << ")";
|
|
cerr << " = ";
|
|
if (C.Type == Constraint::Load) {
|
|
cerr << "*";
|
|
if (C.Offset != 0)
|
|
cerr << "(";
|
|
}
|
|
else if (C.Type == Constraint::AddressOf)
|
|
cerr << "&";
|
|
PrintNode(&GraphNodes[C.Src]);
|
|
if (C.Offset != 0 && C.Type != Constraint::Store)
|
|
cerr << " + " << C.Offset;
|
|
if (C.Type == Constraint::Load && C.Offset != 0)
|
|
cerr << ")";
|
|
cerr << "\n";
|
|
}
|
|
|
|
void Andersens::PrintConstraints() {
|
|
cerr << "Constraints:\n";
|
|
|
|
for (unsigned i = 0, e = Constraints.size(); i != e; ++i)
|
|
PrintConstraint(Constraints[i]);
|
|
}
|
|
|
|
void Andersens::PrintPointsToGraph() {
|
|
cerr << "Points-to graph:\n";
|
|
for (unsigned i = 0, e = GraphNodes.size(); i != e; ++i) {
|
|
Node *N = &GraphNodes[i];
|
|
if (FindNode (i) != i) {
|
|
PrintNode(N);
|
|
cerr << "\t--> same as ";
|
|
PrintNode(&GraphNodes[FindNode(i)]);
|
|
cerr << "\n";
|
|
} else {
|
|
cerr << "[" << (N->PointsTo->count()) << "] ";
|
|
PrintNode(N);
|
|
cerr << "\t--> ";
|
|
|
|
bool first = true;
|
|
for (SparseBitVector<>::iterator bi = N->PointsTo->begin();
|
|
bi != N->PointsTo->end();
|
|
++bi) {
|
|
if (!first)
|
|
cerr << ", ";
|
|
PrintNode(&GraphNodes[*bi]);
|
|
first = false;
|
|
}
|
|
cerr << "\n";
|
|
}
|
|
}
|
|
}
|