[XRay] Implement the `llvm-xray graph` subcommand

Here we define the `graph` subcommand which generates a graph from the function
call information and uses it to present the call information graphically with
additional annotations.

Reviewers: dblaikie, dberris

Differential Revision: https://reviews.llvm.org/D27243

llvm-svn: 292156

1 files changed, 129 insertions, 0 deletions

diff --git a/llvm/tools/llvm-xray/xray-graph.h b/llvm/tools/llvm-xray/xray-graph.h
new file mode 100644
index 00000000000..dbd92a7893d
--- /dev/null
+++ b/llvm/tools/llvm-xray/xray-graph.h
@@ -0,0 +1,129 @@
+//===-- xray-graph.h - XRay Function Call Graph Renderer --------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Generate a DOT file to represent the function call graph encountered in
+// the trace.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef XRAY_GRAPH_H
+#define XRAY_GRAPH_H
+
+#include <vector>
+
+#include "func-id-helper.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/XRay/Trace.h"
+#include "llvm/XRay/XRayRecord.h"
+
+namespace llvm {
+namespace xray {
+
+/// A class encapsulating the logic related to analyzing XRay traces, producting
+/// Graphs from them and then exporting those graphs for review.
+class GraphRenderer {
+public:
+  /// An inner struct for common timing statistics information
+  struct TimeStat {
+    uint64_t Count;
+    double Min;
+    double Median;
+    double Pct90;
+    double Pct99;
+    double Max;
+    double Sum;
+  };
+
+  /// An inner struct for storing edge attributes for our graph. Here the
+  /// attributes are mainly function call statistics.
+  ///
+  /// FIXME: expand to contain more information eg call latencies.
+  struct EdgeAttribute {
+    TimeStat S;
+    std::vector<uint64_t> Timings;
+  };
+
+  /// An Inner Struct for storing vertex attributes, at the moment just
+  /// SymbolNames, however in future we could store bulk function statistics.
+  ///
+  /// FIXME: Store more attributes based on instrumentation map.
+  struct VertexAttribute {
+    std::string SymbolName;
+    TimeStat S;
+  };
+
+private:
+  /// The Graph stored in an edge-list like format, with the edges also having
+  /// An attached set of attributes.
+  DenseMap<int32_t, DenseMap<int32_t, EdgeAttribute>> Graph;
+
+  /// Graph Vertex Attributes. These are presently stored seperate from the
+  /// main graph.
+  DenseMap<int32_t, VertexAttribute> VertexAttrs;
+
+  struct FunctionAttr {
+    int32_t FuncId;
+    uint64_t TSC;
+  };
+
+  /// Use a Map to store the Function stack for each thread whilst building the
+  /// graph.
+  ///
+  /// FIXME: Perhaps we can Build this into LatencyAccountant? or vise versa?
+  DenseMap<pid_t, SmallVector<FunctionAttr, 4>> PerThreadFunctionStack;
+
+  /// Usefull object for getting human readable Symbol Names.
+  FuncIdConversionHelper &FuncIdHelper;
+  bool DeduceSiblingCalls = false;
+  uint64_t CurrentMaxTSC = 0;
+
+  /// A private function to help implement the statistic generation functions;
+  template <typename U>
+  void getStats(U begin, U end, GraphRenderer::TimeStat &S);
+
+  /// Calculates latency statistics for each edge and stores the data in the
+  /// Graph
+  void calculateEdgeStatistics();
+
+  /// Calculates latency statistics for each vertex and stores the data in the
+  /// Graph
+  void calculateVertexStatistics();
+
+  /// Normalises latency statistics for each edge and vertex by CycleFrequency;
+  void normaliseStatistics(double CycleFrequency);
+
+public:
+  /// Takes in a reference to a FuncIdHelper in order to have ready access to
+  /// Symbol names.
+  explicit GraphRenderer(FuncIdConversionHelper &FuncIdHelper, bool DSC)
+      : FuncIdHelper(FuncIdHelper), DeduceSiblingCalls(DSC) {}
+
+  /// Process an Xray record and expand the graph.
+  ///
+  /// This Function will return true on success, or false if records are not
+  /// presented in per-thread call-tree DFS order. (That is for each thread the
+  /// Records should be in order runtime on an ideal system.)
+  ///
+  /// FIXME: Make this more robust against small irregularities.
+  bool accountRecord(const XRayRecord &Record);
+
+  /// An enum for enumerating the various statistics gathered on latencies
+  enum class StatType { COUNT, MIN, MED, PCT90, PCT99, MAX, SUM };
+
+  /// Output the Embedded graph in DOT format on \p OS, labeling the edges by
+  /// \p T
+  void exportGraphAsDOT(raw_ostream &OS, const XRayFileHeader &H,
+                        StatType T = StatType::COUNT);
+};
+}
+}
+
+#endif // XRAY_GRAPH_H