blob: 92b4b317cfbd7cdecd55eddc53b5e4702b5eeea6 [file] [log] [blame]
//===----- llvm/unittest/ADT/SCCIteratorTest.cpp - SCCIterator tests ------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/GraphTraits.h"
#include "gtest/gtest.h"
#include <limits.h>
using namespace llvm;
namespace llvm {
/// Graph<N> - A graph with N nodes. Note that N can be at most 8.
template <unsigned N>
class Graph {
private:
// Disable copying.
Graph(const Graph&);
Graph& operator=(const Graph&);
static void ValidateIndex(unsigned Idx) {
assert(Idx < N && "Invalid node index!");
}
public:
/// NodeSubset - A subset of the graph's nodes.
class NodeSubset {
typedef unsigned char BitVector; // Where the limitation N <= 8 comes from.
BitVector Elements;
NodeSubset(BitVector e) : Elements(e) {}
public:
/// NodeSubset - Default constructor, creates an empty subset.
NodeSubset() : Elements(0) {
assert(N <= sizeof(BitVector)*CHAR_BIT && "Graph too big!");
}
/// NodeSubset - Copy constructor.
NodeSubset(const NodeSubset &other) : Elements(other.Elements) {}
/// Comparison operators.
bool operator==(const NodeSubset &other) const {
return other.Elements == this->Elements;
}
bool operator!=(const NodeSubset &other) const {
return !(*this == other);
}
/// AddNode - Add the node with the given index to the subset.
void AddNode(unsigned Idx) {
ValidateIndex(Idx);
Elements |= 1U << Idx;
}
/// DeleteNode - Remove the node with the given index from the subset.
void DeleteNode(unsigned Idx) {
ValidateIndex(Idx);
Elements &= ~(1U << Idx);
}
/// count - Return true if the node with the given index is in the subset.
bool count(unsigned Idx) {
ValidateIndex(Idx);
return (Elements & (1U << Idx)) != 0;
}
/// isEmpty - Return true if this is the empty set.
bool isEmpty() const {
return Elements == 0;
}
/// isSubsetOf - Return true if this set is a subset of the given one.
bool isSubsetOf(const NodeSubset &other) const {
return (this->Elements | other.Elements) == other.Elements;
}
/// Complement - Return the complement of this subset.
NodeSubset Complement() const {
return ~(unsigned)this->Elements & ((1U << N) - 1);
}
/// Join - Return the union of this subset and the given one.
NodeSubset Join(const NodeSubset &other) const {
return this->Elements | other.Elements;
}
/// Meet - Return the intersection of this subset and the given one.
NodeSubset Meet(const NodeSubset &other) const {
return this->Elements & other.Elements;
}
};
/// NodeType - Node index and set of children of the node.
typedef std::pair<unsigned, NodeSubset> NodeType;
private:
/// Nodes - The list of nodes for this graph.
NodeType Nodes[N];
public:
/// Graph - Default constructor. Creates an empty graph.
Graph() {
// Let each node know which node it is. This allows us to find the start of
// the Nodes array given a pointer to any element of it.
for (unsigned i = 0; i != N; ++i)
Nodes[i].first = i;
}
/// AddEdge - Add an edge from the node with index FromIdx to the node with
/// index ToIdx.
void AddEdge(unsigned FromIdx, unsigned ToIdx) {
ValidateIndex(FromIdx);
Nodes[FromIdx].second.AddNode(ToIdx);
}
/// DeleteEdge - Remove the edge (if any) from the node with index FromIdx to
/// the node with index ToIdx.
void DeleteEdge(unsigned FromIdx, unsigned ToIdx) {
ValidateIndex(FromIdx);
Nodes[FromIdx].second.DeleteNode(ToIdx);
}
/// AccessNode - Get a pointer to the node with the given index.
NodeType *AccessNode(unsigned Idx) const {
ValidateIndex(Idx);
// The constant cast is needed when working with GraphTraits, which insists
// on taking a constant Graph.
return const_cast<NodeType *>(&Nodes[Idx]);
}
/// NodesReachableFrom - Return the set of all nodes reachable from the given
/// node.
NodeSubset NodesReachableFrom(unsigned Idx) const {
// This algorithm doesn't scale, but that doesn't matter given the small
// size of our graphs.
NodeSubset Reachable;
// The initial node is reachable.
Reachable.AddNode(Idx);
do {
NodeSubset Previous(Reachable);
// Add in all nodes which are children of a reachable node.
for (unsigned i = 0; i != N; ++i)
if (Previous.count(i))
Reachable = Reachable.Join(Nodes[i].second);
// If nothing changed then we have found all reachable nodes.
if (Reachable == Previous)
return Reachable;
// Rinse and repeat.
} while (1);
}
/// ChildIterator - Visit all children of a node.
class ChildIterator {
friend class Graph;
/// FirstNode - Pointer to first node in the graph's Nodes array.
NodeType *FirstNode;
/// Children - Set of nodes which are children of this one and that haven't
/// yet been visited.
NodeSubset Children;
ChildIterator(); // Disable default constructor.
protected:
ChildIterator(NodeType *F, NodeSubset C) : FirstNode(F), Children(C) {}
public:
/// ChildIterator - Copy constructor.
ChildIterator(const ChildIterator& other) : FirstNode(other.FirstNode),
Children(other.Children) {}
/// Comparison operators.
bool operator==(const ChildIterator &other) const {
return other.FirstNode == this->FirstNode &&
other.Children == this->Children;
}
bool operator!=(const ChildIterator &other) const {
return !(*this == other);
}
/// Prefix increment operator.
ChildIterator& operator++() {
// Find the next unvisited child node.
for (unsigned i = 0; i != N; ++i)
if (Children.count(i)) {
// Remove that child - it has been visited. This is the increment!
Children.DeleteNode(i);
return *this;
}
assert(false && "Incrementing end iterator!");
return *this; // Avoid compiler warnings.
}
/// Postfix increment operator.
ChildIterator operator++(int) {
ChildIterator Result(*this);
++(*this);
return Result;
}
/// Dereference operator.
NodeType *operator*() {
// Find the next unvisited child node.
for (unsigned i = 0; i != N; ++i)
if (Children.count(i))
// Return a pointer to it.
return FirstNode + i;
assert(false && "Dereferencing end iterator!");
return 0; // Avoid compiler warning.
}
};
/// child_begin - Return an iterator pointing to the first child of the given
/// node.
static ChildIterator child_begin(NodeType *Parent) {
return ChildIterator(Parent - Parent->first, Parent->second);
}
/// child_end - Return the end iterator for children of the given node.
static ChildIterator child_end(NodeType *Parent) {
return ChildIterator(Parent - Parent->first, NodeSubset());
}
};
template <unsigned N>
struct GraphTraits<Graph<N> > {
typedef typename Graph<N>::NodeType NodeType;
typedef typename Graph<N>::ChildIterator ChildIteratorType;
static inline NodeType *getEntryNode(const Graph<N> &G) { return G.AccessNode(0); }
static inline ChildIteratorType child_begin(NodeType *Node) {
return Graph<N>::child_begin(Node);
}
static inline ChildIteratorType child_end(NodeType *Node) {
return Graph<N>::child_end(Node);
}
};
TEST(SCCIteratorTest, AllSmallGraphs) {
// Test SCC computation against every graph with NUM_NODES nodes or less.
// Since SCC considers every node to have an implicit self-edge, we only
// create graphs for which every node has a self-edge.
#define NUM_NODES 4
#define NUM_GRAPHS (NUM_NODES * (NUM_NODES - 1))
typedef Graph<NUM_NODES> GT;
/// Enumerate all graphs using NUM_GRAPHS bits.
assert(NUM_GRAPHS < sizeof(unsigned) * CHAR_BIT && "Too many graphs!");
for (unsigned GraphDescriptor = 0; GraphDescriptor < (1U << NUM_GRAPHS);
++GraphDescriptor) {
GT G;
// Add edges as specified by the descriptor.
unsigned DescriptorCopy = GraphDescriptor;
for (unsigned i = 0; i != NUM_NODES; ++i)
for (unsigned j = 0; j != NUM_NODES; ++j) {
// Always add a self-edge.
if (i == j) {
G.AddEdge(i, j);
continue;
}
if (DescriptorCopy & 1)
G.AddEdge(i, j);
DescriptorCopy >>= 1;
}
// Test the SCC logic on this graph.
/// NodesInSomeSCC - Those nodes which are in some SCC.
GT::NodeSubset NodesInSomeSCC;
for (scc_iterator<GT> I = scc_begin(G), E = scc_end(G); I != E; ++I) {
std::vector<GT::NodeType*> &SCC = *I;
// Get the nodes in this SCC as a NodeSubset rather than a vector.
GT::NodeSubset NodesInThisSCC;
for (unsigned i = 0, e = SCC.size(); i != e; ++i)
NodesInThisSCC.AddNode(SCC[i]->first);
// There should be at least one node in every SCC.
EXPECT_FALSE(NodesInThisSCC.isEmpty());
// Check that every node in the SCC is reachable from every other node in
// the SCC.
for (unsigned i = 0; i != NUM_NODES; ++i)
if (NodesInThisSCC.count(i))
EXPECT_TRUE(NodesInThisSCC.isSubsetOf(G.NodesReachableFrom(i)));
// OK, now that we now that every node in the SCC is reachable from every
// other, this means that the set of nodes reachable from any node in the
// SCC is the same as the set of nodes reachable from every node in the
// SCC. Check that for every node N not in the SCC but reachable from the
// SCC, no element of the SCC is reachable from N.
for (unsigned i = 0; i != NUM_NODES; ++i)
if (NodesInThisSCC.count(i)) {
GT::NodeSubset NodesReachableFromSCC = G.NodesReachableFrom(i);
GT::NodeSubset ReachableButNotInSCC =
NodesReachableFromSCC.Meet(NodesInThisSCC.Complement());
for (unsigned j = 0; j != NUM_NODES; ++j)
if (ReachableButNotInSCC.count(j))
EXPECT_TRUE(G.NodesReachableFrom(j).Meet(NodesInThisSCC).isEmpty());
// The result must be the same for all other nodes in this SCC, so
// there is no point in checking them.
break;
}
// This is indeed a SCC: a maximal set of nodes for which each node is
// reachable from every other.
// Check that we didn't already see this SCC.
EXPECT_TRUE(NodesInSomeSCC.Meet(NodesInThisSCC).isEmpty());
NodesInSomeSCC = NodesInSomeSCC.Join(NodesInThisSCC);
// Check a property that is specific to the LLVM SCC iterator and
// guaranteed by it: if a node in SCC S1 has an edge to a node in
// SCC S2, then S1 is visited *after* S2. This means that the set
// of nodes reachable from this SCC must be contained either in the
// union of this SCC and all previously visited SCC's.
for (unsigned i = 0; i != NUM_NODES; ++i)
if (NodesInThisSCC.count(i)) {
GT::NodeSubset NodesReachableFromSCC = G.NodesReachableFrom(i);
EXPECT_TRUE(NodesReachableFromSCC.isSubsetOf(NodesInSomeSCC));
// The result must be the same for all other nodes in this SCC, so
// there is no point in checking them.
break;
}
}
// Finally, check that the nodes in some SCC are exactly those that are
// reachable from the initial node.
EXPECT_EQ(NodesInSomeSCC, G.NodesReachableFrom(0));
}
}
}