[llvm-commits] [llvm] r42269 - in /llvm/trunk: include/llvm/ADT/DenseMap.h include/llvm/ADT/SparseBitVector.h lib/Analysis/IPA/Andersens.cpp
Daniel Berlin
dberlin at dberlin.org
Mon Sep 24 12:45:50 PDT 2007
Author: dannyb
Date: Mon Sep 24 14:45:49 2007
New Revision: 42269
URL: http://llvm.org/viewvc/llvm-project?rev=42269&view=rev
Log:
Implement offline variable substitution in order to reduce memory
and time usage.
Fixup operator == to make this work, and add a resize method to DenseMap
so we can resize our hashtable once we know how big it should be.
Modified:
llvm/trunk/include/llvm/ADT/DenseMap.h
llvm/trunk/include/llvm/ADT/SparseBitVector.h
llvm/trunk/lib/Analysis/IPA/Andersens.cpp
Modified: llvm/trunk/include/llvm/ADT/DenseMap.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/DenseMap.h?rev=42269&r1=42268&r2=42269&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/DenseMap.h (original)
+++ llvm/trunk/include/llvm/ADT/DenseMap.h Mon Sep 24 14:45:49 2007
@@ -99,6 +99,9 @@
bool empty() const { return NumEntries == 0; }
unsigned size() const { return NumEntries; }
+
+ /// Grow the densemap so that it has at least Size buckets. Does not shrink
+ void resize(size_t Size) { grow(Size); }
void clear() {
// If the capacity of the array is huge, and the # elements used is small,
@@ -228,7 +231,7 @@
// causing infinite loops in lookup.
if (NumEntries*4 >= NumBuckets*3 ||
NumBuckets-(NumEntries+NumTombstones) < NumBuckets/8) {
- this->grow();
+ this->grow(NumBuckets * 2);
LookupBucketFor(Key, TheBucket);
}
++NumEntries;
@@ -310,12 +313,13 @@
new (&Buckets[i].first) KeyT(EmptyKey);
}
- void grow() {
+ void grow(unsigned AtLeast) {
unsigned OldNumBuckets = NumBuckets;
BucketT *OldBuckets = Buckets;
// Double the number of buckets.
- NumBuckets <<= 1;
+ while (NumBuckets <= AtLeast)
+ NumBuckets <<= 1;
NumTombstones = 0;
Buckets = reinterpret_cast<BucketT*>(new char[sizeof(BucketT)*NumBuckets]);
Modified: llvm/trunk/include/llvm/ADT/SparseBitVector.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ADT/SparseBitVector.h?rev=42269&r1=42268&r2=42269&view=diff
==============================================================================
--- llvm/trunk/include/llvm/ADT/SparseBitVector.h (original)
+++ llvm/trunk/include/llvm/ADT/SparseBitVector.h Mon Sep 24 14:45:49 2007
@@ -75,7 +75,6 @@
}
friend struct ilist_traits<SparseBitVectorElement<ElementSize> >;
-
public:
explicit SparseBitVectorElement(unsigned Idx) {
ElementIndex = Idx;
@@ -287,6 +286,14 @@
}
BecameZero = allzero;
}
+ // Get a hash value for this element;
+ uint64_t getHashValue() const {
+ uint64_t HashVal = 0;
+ for (unsigned i = 0; i < BITWORDS_PER_ELEMENT; ++i) {
+ HashVal ^= Bits[i];
+ }
+ return HashVal;
+ }
};
template <unsigned ElementSize = 128>
@@ -544,22 +551,20 @@
return false;
}
- bool operator!=(const SparseBitVector &RHS) {
+ bool operator!=(const SparseBitVector &RHS) const {
return !(*this == RHS);
}
- bool operator==(const SparseBitVector &RHS) {
+ bool operator==(const SparseBitVector &RHS) const {
ElementListConstIter Iter1 = Elements.begin();
ElementListConstIter Iter2 = RHS.Elements.begin();
- while (Iter2 != RHS.Elements.end()) {
- if (Iter1->index() != Iter2->index()
- || *Iter1 != *Iter2)
+ for (; Iter1 != Elements.end() && Iter2 != RHS.Elements.end();
+ ++Iter1, ++Iter2) {
+ if (*Iter1 != *Iter2)
return false;
- ++Iter1;
- ++Iter2;
}
- return Iter1 == Elements.end();
+ return Iter1 == Elements.end() && Iter2 == RHS.Elements.end();
}
// Union our bitmap with the RHS and return true if we changed.
@@ -789,6 +794,17 @@
return iterator(this, ~0);
}
+ // Get a hash value for this bitmap.
+ uint64_t getHashValue() const {
+ uint64_t HashVal = 0;
+ for (ElementListConstIter Iter = Elements.begin();
+ Iter != Elements.end();
+ ++Iter) {
+ HashVal ^= Iter->index();
+ HashVal ^= Iter->getHashValue();
+ }
+ return HashVal;
+ }
};
// Convenience functions to allow Or and And without dereferencing in the user
@@ -828,9 +844,10 @@
for (bi = LHS.begin(); bi != LHS.end(); ++bi) {
out << *bi << " ";
}
- out << "\n";
+ out << " ]\n";
}
-
}
+
+
#endif
Modified: llvm/trunk/lib/Analysis/IPA/Andersens.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/IPA/Andersens.cpp?rev=42269&r1=42268&r2=42269&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/IPA/Andersens.cpp (original)
+++ llvm/trunk/lib/Analysis/IPA/Andersens.cpp Mon Sep 24 14:45:49 2007
@@ -16,7 +16,8 @@
// This algorithm is implemented as three stages:
// 1. Object identification.
// 2. Inclusion constraint identification.
-// 3. Inclusion constraint solving.
+// 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
@@ -29,20 +30,25 @@
// 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 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.
+//
// 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 equivalence to
+// 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:
-// Offline variable substitution, offline detection of online
-// cycles. Use of BDD's.
+// Offline detection of online cycles. Use of BDD's.
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "anders-aa"
@@ -59,6 +65,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/SparseBitVector.h"
+#include "llvm/ADT/DenseMap.h"
#include <algorithm>
#include <set>
#include <list>
@@ -66,18 +73,42 @@
#include <vector>
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(NumIters , "Number of iterations to reach convergence");
+STATISTIC(NumConstraints, "Number of constraints");
+STATISTIC(NumNodes , "Number of nodes");
+STATISTIC(NumUnified , "Number of variables unified");
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 = 2;
+ const unsigned CallReturnPos = 1;
// Position of the function call node relative to the function node.
- const unsigned CallFirstArgPos = 3;
+ 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> {
@@ -89,7 +120,7 @@
/// '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
+ /// illegal on addressof constraints (because it is statically
/// resolvable to A = &C where C = B + K)
struct Constraint {
@@ -105,29 +136,53 @@
}
};
- // Node class - This class is used to represent a node
- // in the constraint graph. Due to various optimizations,
- // 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.
+ // Node class - This class is used to represent a node in the constraint
+ // graph. Due to various optimizations, 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 {
- Value *Val;
+ Value *Val;
SparseBitVector<> *Edges;
SparseBitVector<> *PointsTo;
SparseBitVector<> *OldPointsTo;
bool Changed;
std::list<Constraint> Constraints;
- // 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
- // representative for this one.
- unsigned NodeRep; public:
-
- Node() : Val(0), Edges(0), PointsTo(0), OldPointsTo(0), Changed(false),
- NodeRep(SelfRep) {
- }
+ // 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 ponits-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.
+ // 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;
+ public:
+
+ Node(bool direct = true) :
+ Val(0), Edges(0), PointsTo(0), OldPointsTo(0), Changed(false),
+ PointerEquivLabel(0), LocationEquivLabel(0), PredEdges(0),
+ ImplicitPredEdges(0), PointedToBy(0), NumInEdges(0),
+ StoredInHash(false), Direct(direct), AddressTaken(false),
+ NodeRep(SelfRep) { }
Node *setValue(Value *V) {
assert(Val == 0 && "Value already set for this node!");
@@ -163,28 +218,28 @@
/// ValueNodes - This map indicates the Node that a particular Value* is
/// represented by. This contains entries for all pointers.
- std::map<Value*, unsigned> ValueNodes;
+ DenseMap<Value*, unsigned> ValueNodes;
/// ObjectNodes - This map contains entries for each memory object in the
/// program: globals, alloca's and mallocs.
- std::map<Value*, unsigned> ObjectNodes;
+ DenseMap<Value*, unsigned> ObjectNodes;
/// ReturnNodes - This map contains an entry for each function in the
/// program that returns a value.
- std::map<Function*, unsigned> ReturnNodes;
+ 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.
- std::map<Function*, unsigned> VarargNodes;
+ 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,
+ // 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;
@@ -193,9 +248,10 @@
enum {
UniversalSet = 0,
NullPtr = 1,
- NullObject = 2
+ NullObject = 2,
+ NumberSpecialNodes
};
- // Stack for Tarjans
+ // Stack for Tarjan's
std::stack<unsigned> SCCStack;
// Topological Index -> Graph node
std::vector<unsigned> Topo2Node;
@@ -209,6 +265,34 @@
unsigned DFSNumber;
unsigned RPONumber;
+ // 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;
+
public:
static char ID;
Andersens() : ModulePass((intptr_t)&ID) {}
@@ -217,7 +301,11 @@
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());
@@ -275,7 +363,7 @@
if (!isa<GlobalValue>(C))
return getNodeForConstantPointer(C);
- std::map<Value*, unsigned>::iterator I = ValueNodes.find(V);
+ DenseMap<Value*, unsigned>::iterator I = ValueNodes.find(V);
if (I == ValueNodes.end()) {
#ifndef NDEBUG
V->dump();
@@ -288,7 +376,7 @@
/// getObject - Return the node corresponding to the memory object for the
/// specified global or allocation instruction.
unsigned getObject(Value *V) {
- std::map<Value*, unsigned>::iterator I = ObjectNodes.find(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;
@@ -297,7 +385,7 @@
/// getReturnNode - Return the node representing the return value for the
/// specified function.
unsigned getReturnNode(Function *F) {
- std::map<Function*, unsigned>::iterator I = ReturnNodes.find(F);
+ DenseMap<Function*, unsigned>::iterator I = ReturnNodes.find(F);
assert(I != ReturnNodes.end() && "Function does not return a value!");
return I->second;
}
@@ -305,7 +393,7 @@
/// getVarargNode - Return the node representing the variable arguments
/// formal for the specified function.
unsigned getVarargNode(Function *F) {
- std::map<Function*, unsigned>::iterator I = VarargNodes.find(F);
+ DenseMap<Function*, unsigned>::iterator I = VarargNodes.find(F);
assert(I != VarargNodes.end() && "Function does not take var args!");
return I->second;
}
@@ -325,9 +413,18 @@
void CollectConstraints(Module &M);
bool AnalyzeUsesOfFunction(Value *);
void CreateConstraintGraph();
+ void OptimizeConstraints();
+ unsigned FindEquivalentNode(unsigned, unsigned);
+ void ClumpAddressTaken();
+ void RewriteConstraints();
+ void HU();
+ void HVN();
+ void UnitePointerEquivalences();
void SolveConstraints();
void 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);
@@ -339,6 +436,8 @@
void PrintNode(Node *N);
void PrintConstraints();
+ void PrintConstraint(const Constraint &);
+ void PrintLabels();
void PrintPointsToGraph();
//===------------------------------------------------------------------===//
@@ -506,7 +605,6 @@
// The function itself is a memory object.
unsigned First = NumObjects;
ValueNodes[F] = NumObjects++;
- ObjectNodes[F] = NumObjects++;
if (isa<PointerType>(F->getFunctionType()->getReturnType()))
ReturnNodes[F] = NumObjects++;
if (F->getFunctionType()->isVarArg())
@@ -516,10 +614,11 @@
// 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++;
+ {
+ if (isa<PointerType>(I->getType()))
+ ValueNodes[I] = NumObjects++;
+ }
MaxK[First] = NumObjects - First;
- MaxK[First + 1] = NumObjects - First - 1;
// 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
@@ -796,11 +895,6 @@
}
for (Module::iterator F = M.begin(), E = M.end(); F != E; ++F) {
- // Make the function address point to the function object.
- unsigned ObjectIndex = getObject(F);
- GraphNodes[ObjectIndex].setValue(F);
- Constraints.push_back(Constraint(Constraint::AddressOf, getNodeValue(*F),
- ObjectIndex));
// Set up the return value node.
if (isa<PointerType>(F->getFunctionType()->getReturnType()))
GraphNodes[getReturnNode(F)].setValue(F);
@@ -1091,8 +1185,736 @@
return Result;
}
-// Create the constraint graph used for solving points-to analysis.
-//
+void dumpToDOUT(SparseBitVector<> *bitmap) {
+ dump(*bitmap, DOUT);
+}
+
+
+/// 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;
+
+ 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)
+ continue;
+
+ 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.
+ return UniteNodes(PEClass2Node[NodeLabel], NodeIndex);
+ } 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";
+ }
+}
+
+/// Optimize the constraints by performing offline variable substitution and
+/// other optimizations.
+void Andersens::OptimizeConstraints() {
+ DOUT << "Beginning constraint optimization\n";
+
+ // 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;
+ delete N->PredEdges;
+ delete N->ImplicitPredEdges;
+ delete N->PointedToBy;
+ }
+ }
+ GraphNodes.erase(GraphNodes.begin() + FirstRefNode, GraphNodes.end());
+ 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].NodeRep == SelfRep) {
+ 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];
@@ -1181,8 +2003,13 @@
bool Changed = true;
unsigned Iteration = 0;
- // We create the bitmaps here to avoid getting jerked around by the compiler
- // creating objects behind our back and wasting lots of memory.
+ 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<>;
@@ -1190,9 +2017,12 @@
N->Edges = new SparseBitVector<>;
}
CreateConstraintGraph();
-
+ UnitePointerEquivalences();
+ assert(SCCStack.empty() && "SCC Stack should be empty by now!");
Topo2Node.insert(Topo2Node.begin(), GraphNodes.size(), Unvisited);
Node2Topo.insert(Node2Topo.begin(), GraphNodes.size(), Unvisited);
+ Node2DFS.clear();
+ Node2Deleted.clear();
Node2DFS.insert(Node2DFS.begin(), GraphNodes.size(), 0);
Node2Deleted.insert(Node2Deleted.begin(), GraphNodes.size(), false);
DFSNumber = 0;
@@ -1214,7 +2044,7 @@
do {
Changed = false;
++NumIters;
- DOUT << "Starting iteration #" << Iteration++;
+ DOUT << "Starting iteration #" << Iteration++ << "\n";
// TODO: In the microoptimization category, we could just make Topo2Node
// a fast map and thus only contain the visited nodes.
for (unsigned i = 0; i < GraphNodes.size(); ++i) {
@@ -1248,7 +2078,7 @@
// TODO: We could delete redundant constraints here.
// 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 function.
+ // 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.
@@ -1282,11 +2112,10 @@
CurrMember = *bi;
// Need to increment the member by K since that is where we are
- // supposed to copy to/from
- // Node 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.
+ // 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
@@ -1393,12 +2222,17 @@
SecondNode->NodeRep = First;
FirstNode->Changed |= SecondNode->Changed;
- FirstNode->PointsTo |= *(SecondNode->PointsTo);
- FirstNode->Edges |= *(SecondNode->Edges);
- FirstNode->Constraints.splice(FirstNode->Constraints.begin(),
- SecondNode->Constraints);
- delete FirstNode->OldPointsTo;
- FirstNode->OldPointsTo = new SparseBitVector<>;
+ if (FirstNode->PointsTo && SecondNode->PointsTo)
+ FirstNode->PointsTo |= *(SecondNode->PointsTo);
+ if (FirstNode->Edges && SecondNode->Edges)
+ FirstNode->Edges |= *(SecondNode->Edges);
+ if (!FirstNode->Constraints.empty() && !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;
@@ -1479,35 +2313,36 @@
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) {
- const Constraint &C = Constraints[i];
- 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";
- }
+ for (unsigned i = 0, e = Constraints.size(); i != e; ++i)
+ PrintConstraint(Constraints[i]);
}
void Andersens::PrintPointsToGraph() {
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