[BFI/MBFI]: cfg graph view with color scheme

This patch enhances dot graph viewer to show hot regions
with hot bbs/edges displayed in red. The ratio of the bb
freq to the max freq of the function needs to be no less
than the value specified by view-hot-freq-percent option.
The default value is 10 (i.e. 10%).

llvm-svn: 273996

llvm/include/llvm/Analysis/BlockFrequencyInfoImpl.h

@@ -1249,10 +1249,42 @@ struct BFIDOTGraphTraitsBase : public DefaultDOTGraphTraits {
   typedef typename GTraits::ChildIteratorType EdgeIter;
   typedef typename GTraits::nodes_iterator NodeIter;
 
+  uint64_t MaxFrequency = 0;
   static std::string getGraphName(const BlockFrequencyInfoT *G) {
     return G->getFunction()->getName();
   }
 
+  std::string getNodeAttributes(const NodeType *Node,
+                                const BlockFrequencyInfoT *Graph,
+                                unsigned HotPercentThreshold = 0) {
+    std::string Result;
+    if (!HotPercentThreshold)
+      return Result;
+
+    // Compute MaxFrequency on the fly:
+    if (!MaxFrequency) {
+      for (NodeIter I = GTraits::nodes_begin(Graph),
+                    E = GTraits::nodes_end(Graph);
+           I != E; ++I) {
+        NodeType &N = *I;
+        MaxFrequency =
+            std::max(MaxFrequency, Graph->getBlockFreq(&N).getFrequency());
+      }
+    }
+    BlockFrequency Freq = Graph->getBlockFreq(Node);
+    BlockFrequency HotFreq =
+        (BlockFrequency(MaxFrequency) *
+         BranchProbability::getBranchProbability(HotPercentThreshold, 100));
+
+    if (Freq < HotFreq)
+      return Result;
+
+    raw_string_ostream OS(Result);
+    OS << "color=\"red\"";
+    OS.flush();
+    return Result;
+  }
+
   std::string getNodeLabel(const NodeType *Node,
                            const BlockFrequencyInfoT *Graph, GVDAGType GType) {
     std::string Result;
@@ -1282,7 +1314,9 @@ struct BFIDOTGraphTraitsBase : public DefaultDOTGraphTraits {
   }
 
   std::string getEdgeAttributes(const NodeType *Node, EdgeIter EI,
-                                const BranchProbabilityInfoT *BPI) {
+                                const BlockFrequencyInfoT *BFI,
+                                const BranchProbabilityInfoT *BPI,
+                                unsigned HotPercentThreshold = 0) {
     std::string Str;
     if (!BPI)
       return Str;
@@ -1293,6 +1327,17 @@ struct BFIDOTGraphTraitsBase : public DefaultDOTGraphTraits {
     double Percent = 100.0 * N / D;
     raw_string_ostream OS(Str);
     OS << format("label=\"%.1f%%\"", Percent);
+
+    if (HotPercentThreshold) {
+      BlockFrequency EFreq = BFI->getBlockFreq(Node) * BP;
+      BlockFrequency HotFreq = BlockFrequency(MaxFrequency) *
+                               BranchProbability(HotPercentThreshold, 100);
+
+      if (EFreq >= HotFreq) {
+        OS << ",color=\"red\"";
+      }
+    }
+
     OS.flush();
     return Str;
   }

llvm/lib/Analysis/BlockFrequencyInfo.cpp

@@ -42,7 +42,19 @@ static cl::opt<GVDAGType> ViewBlockFreqPropagationDAG(
                                                "profile count if available."),
                clEnumValEnd));
 
-cl::opt<std::string> ViewBlockFreqFuncName("view-bfi-func-name", cl::Hidden);
+cl::opt<std::string>
+    ViewBlockFreqFuncName("view-bfi-func-name", cl::Hidden,
+                          cl::desc("The option to specify "
+                                   "the name of the function "
+                                   "whose CFG will be displayed."));
+
+cl::opt<unsigned>
+    ViewHotFreqPercent("view-hot-freq-percent", cl::init(10), cl::Hidden,
+                       cl::desc("An integer in percent used to specify "
+                                "the hot blocks/edges to be displayed "
+                                "in red: a block or edge whose frequency "
+                                "is no less than the max frequency of the "
+                                "function multiplied by this percent."));
 
 namespace llvm {
 
@@ -84,9 +96,16 @@ struct DOTGraphTraits<BlockFrequencyInfo *> : public BFIDOTGTraitsBase {
                                            ViewBlockFreqPropagationDAG);
   }
 
+  std::string getNodeAttributes(const BasicBlock *Node,
+                                const BlockFrequencyInfo *Graph) {
+    return BFIDOTGTraitsBase::getNodeAttributes(Node, Graph,
+                                                ViewHotFreqPercent);
+  }
+
   std::string getEdgeAttributes(const BasicBlock *Node, EdgeIter EI,
                                 const BlockFrequencyInfo *BFI) {
-    return BFIDOTGTraitsBase::getEdgeAttributes(Node, EI, BFI->getBPI());
+    return BFIDOTGTraitsBase::getEdgeAttributes(Node, EI, BFI, BFI->getBPI(),
+                                                ViewHotFreqPercent);
   }
 };
 

llvm/lib/CodeGen/MachineBlockFrequencyInfo.cpp

@@ -47,6 +47,7 @@ static cl::opt<GVDAGType> ViewMachineBlockFreqPropagationDAG(
                clEnumValEnd));
 
 extern cl::opt<std::string> ViewBlockFreqFuncName;
+extern cl::opt<uint64_t> ViewHotFreqPercent;
 
 namespace llvm {
 
@@ -92,9 +93,16 @@ struct DOTGraphTraits<MachineBlockFrequencyInfo *>
         Node, Graph, ViewMachineBlockFreqPropagationDAG);
   }
 
+  std::string getNodeAttributes(const MachineBasicBlock *Node,
+                                const MachineBlockFrequencyInfo *Graph) {
+    return MBFIDOTGraphTraitsBase::getNodeAttributes(Node, Graph,
+                                                     ViewHotFreqPercent);
+  }
+
   std::string getEdgeAttributes(const MachineBasicBlock *Node, EdgeIter EI,
                                 const MachineBlockFrequencyInfo *MBFI) {
-    return MBFIDOTGraphTraitsBase::getEdgeAttributes(Node, EI, MBFI->getMBPI());
+    return MBFIDOTGraphTraitsBase::getEdgeAttributes(
+        Node, EI, MBFI, MBFI->getMBPI(), ViewHotFreqPercent);
   }
 };