llvm-cov: Added edge struct for traversal in block.

Added GCOVEdge which are simple structs owned by the GCOVFunction that
stores the source and destination GCOVBlocks, as well as the counts.
Changed GCOVBlocks so that it stores a vector of source GCOVEdges and a
vector of destination GCOVEdges, rather than just the block number.

Storing the block number was only useful for knowing the number of edges
and for debug info. Using a struct is useful for traversing the edges,
especially back edges which may be needed later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196175 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 70 insertions, 17 deletions

diff --git a/include/llvm/Support/GCOV.h b/include/llvm/Support/GCOV.h
index 9649a1dad3..ee81229ff8 100644
--- a/include/llvm/Support/GCOV.h
+++ b/include/llvm/Support/GCOV.h
@@ -205,6 +205,14 @@ private:
   uint32_t ProgramCount;
 };
 
+struct GCOVEdge {
+  GCOVEdge(GCOVBlock *S, GCOVBlock *D): Src(S), Dst(D), Count(0) {}
+
+  GCOVBlock *Src;
+  GCOVBlock *Dst;
+  uint64_t Count;
+};
+
 /// GCOVFunction - Collects function information.
 class GCOVFunction {
 public:
@@ -221,25 +229,43 @@ private:
   StringRef Name;
   StringRef Filename;
   SmallVector<GCOVBlock *, 16> Blocks;
+  SmallVector<GCOVEdge *, 16> Edges;
 };
 
 /// GCOVBlock - Collects block information.
 class GCOVBlock {
 public:
+  typedef SmallVectorImpl<GCOVEdge *>::const_iterator EdgeIterator;
+
   GCOVBlock(GCOVFunction &P, uint32_t N) :
-    Parent(P), Number(N), Counter(0), Edges(), Lines() {}
+    Parent(P), Number(N), Counter(0), SrcEdges(), DstEdges(), Lines() {}
   ~GCOVBlock();
-  void addEdge(uint32_t N) { Edges.push_back(N); }
+  void addSrcEdge(GCOVEdge *Edge) {
+    assert(Edge->Dst == this); // up to caller to ensure edge is valid
+    SrcEdges.push_back(Edge);
+  }
+  void addDstEdge(GCOVEdge *Edge) {
+    assert(Edge->Src == this); // up to caller to ensure edge is valid
+    DstEdges.push_back(Edge);
+  }
   void addLine(uint32_t N) { Lines.push_back(N); }
-  void addCount(uint64_t N) { Counter += N; }
-  size_t getNumEdges() const { return Edges.size(); }
+  void addCount(size_t DstEdgeNo, uint64_t N);
+  size_t getNumSrcEdges() const { return SrcEdges.size(); }
+  size_t getNumDstEdges() const { return DstEdges.size(); }
+
+  EdgeIterator src_begin() const { return SrcEdges.begin(); }
+  EdgeIterator src_end() const { return SrcEdges.end(); }
+  EdgeIterator dst_begin() const { return DstEdges.begin(); }
+  EdgeIterator dst_end() const { return DstEdges.end(); }
+
   void dump() const;
   void collectLineCounts(FileInfo &FI);
 private:
   GCOVFunction &Parent;
   uint32_t Number;
   uint64_t Counter;
-  SmallVector<uint32_t, 16> Edges;
+  SmallVector<GCOVEdge *, 16> SrcEdges;
+  SmallVector<GCOVEdge *, 16> DstEdges;
   SmallVector<uint32_t, 16> Lines;
 };
 
diff --git a/lib/IR/GCOV.cpp b/lib/IR/GCOV.cpp
index 3b0dee4016..ebf10927fc 100644
--- a/lib/IR/GCOV.cpp
+++ b/lib/IR/GCOV.cpp
@@ -112,6 +112,7 @@ void GCOVFile::collectLineCounts(FileInfo &FI) {
 /// ~GCOVFunction - Delete GCOVFunction and its content.
 GCOVFunction::~GCOVFunction() {
   DeleteContainerPointers(Blocks);
+  DeleteContainerPointers(Edges);
 }
 
 /// readGCNO - Read a function from the GCNO buffer. Return false if an error
@@ -154,7 +155,10 @@ bool GCOVFunction::readGCNO(GCOVBuffer &Buff, GCOV::GCOVFormat Format) {
     for (uint32_t i = 0, e = EdgeCount; i != e; ++i) {
       uint32_t Dst;
       if (!Buff.readInt(Dst)) return false;
-      Blocks[BlockNo]->addEdge(Dst);
+      GCOVEdge *Edge = new GCOVEdge(Blocks[BlockNo], Blocks[Dst]);
+      Edges.push_back(Edge);
+      Blocks[BlockNo]->addDstEdge(Edge);
+      Blocks[Dst]->addSrcEdge(Edge);
       if (!Buff.readInt(Dummy)) return false; // Edge flag
     }
   }
@@ -208,26 +212,29 @@ bool GCOVFunction::readGCDA(GCOVBuffer &Buff, GCOV::GCOVFormat Format) {
     errs() << "Arc tag not found.\n";
     return false;
   }
+
   uint32_t Count;
   if (!Buff.readInt(Count)) return false;
   Count /= 2;
 
   // This for loop adds the counts for each block. A second nested loop is
   // required to combine the edge counts that are contained in the GCDA file.
-  for (uint32_t Line = 0; Count > 0; ++Line) {
-    if (Line >= Blocks.size()) {
+  for (uint32_t BlockNo = 0; Count > 0; ++BlockNo) {
+    // The last block is always reserved for exit block
+    if (BlockNo >= Blocks.size()-1) {
       errs() << "Unexpected number of edges.\n";
       return false;
     }
-    GCOVBlock &Block = *Blocks[Line];
-    for (size_t Edge = 0, End = Block.getNumEdges(); Edge < End; ++Edge) {
+    GCOVBlock &Block = *Blocks[BlockNo];
+    for (size_t EdgeNo = 0, End = Block.getNumDstEdges(); EdgeNo < End;
+           ++EdgeNo) {
       if (Count == 0) {
         errs() << "Unexpected number of edges.\n";
         return false;
       }
       uint64_t ArcCount;
       if (!Buff.readInt64(ArcCount)) return false;
-      Block.addCount(ArcCount);
+      Block.addCount(EdgeNo, ArcCount);
       --Count;
     }
   }
@@ -255,10 +262,21 @@ void GCOVFunction::collectLineCounts(FileInfo &FI) {
 
 /// ~GCOVBlock - Delete GCOVBlock and its content.
 GCOVBlock::~GCOVBlock() {
-  Edges.clear();
+  SrcEdges.clear();
+  DstEdges.clear();
   Lines.clear();
 }
 
+/// addCount - Add to block counter while storing the edge count. If the
+/// destination has no outgoing edges, also update that block's count too.
+void GCOVBlock::addCount(size_t DstEdgeNo, uint64_t N) {
+  assert(DstEdgeNo < DstEdges.size()); // up to caller to ensure EdgeNo is valid
+  DstEdges[DstEdgeNo]->Count = N;
+  Counter += N;
+  if (!DstEdges[DstEdgeNo]->Dst->getNumDstEdges())
+    DstEdges[DstEdgeNo]->Dst->Counter += N;
+}
+
 /// collectLineCounts - Collect line counts. This must be used after
 /// reading .gcno and .gcda files.
 void GCOVBlock::collectLineCounts(FileInfo &FI) {
@@ -270,11 +288,20 @@ void GCOVBlock::collectLineCounts(FileInfo &FI) {
 /// dump - Dump GCOVBlock content to dbgs() for debugging purposes.
 void GCOVBlock::dump() const {
   dbgs() << "Block : " << Number << " Counter : " << Counter << "\n";
-  if (!Edges.empty()) {
-    dbgs() << "\tEdges : ";
-    for (SmallVectorImpl<uint32_t>::const_iterator I = Edges.begin(), E = Edges.end();
-         I != E; ++I)
-      dbgs() << (*I) << ",";
+  if (!SrcEdges.empty()) {
+    dbgs() << "\tSource Edges : ";
+    for (EdgeIterator I = SrcEdges.begin(), E = SrcEdges.end(); I != E; ++I) {
+      const GCOVEdge *Edge = *I;
+      dbgs() << Edge->Src->Number << " (" << Edge->Count << "), ";
+    }
+    dbgs() << "\n";
+  }
+  if (!DstEdges.empty()) {
+    dbgs() << "\tDestination Edges : ";
+    for (EdgeIterator I = DstEdges.begin(), E = DstEdges.end(); I != E; ++I) {
+      const GCOVEdge *Edge = *I;
+      dbgs() << Edge->Dst->Number << " (" << Edge->Count << "), ";
+    }
     dbgs() << "\n";
   }
   if (!Lines.empty()) {