Implemented color coding and Vertex labels in XRay Graph

Summary: A patch to enable the llvm-xray graph subcommand to color edges and vertices based on statistics and to annotate vertices with statistics. Depends on D27243 Reviewers: dblaikie, dberris Reviewed By: dberris Subscribers: mgorny, llvm-commits Differential Revision: https://reviews.llvm.org/D28225 llvm-svn: 293031
2024-10-19 11:02:59 +02:00 · 2017-01-25 07:14:43 +00:00 · 2017-01-25 07:14:43 +00:00 · ace789b028
commit ace789b028
parent 00c1f58b67
6 changed files with 434 additions and 91 deletions
--- a/test/tools/llvm-xray/X86/Inputs/simple-instrmap.yaml
+++ b/test/tools/llvm-xray/X86/Inputs/simple-instrmap.yaml
@ -7,4 +7,16 @@
 - { id: 2, address: 0x3, function: 0x2, kind: function-exit, always-instrument: true}
 - { id: 3, address: 0x3, function: 0x3, kind: function-enter, always-instrument: true}
 - { id: 3, address: 0x4, function: 0x3, kind: function-exit, always-instrument: true}
+- { id: 4, address: 0x4, function: 0x4, kind: function-enter, always-instrument: true}
+- { id: 4, address: 0x5, function: 0x4, kind: function-exit, always-instrument: true}
+- { id: 5, address: 0x5, function: 0x5, kind: function-enter, always-instrument: true}
+- { id: 5, address: 0x6, function: 0x5, kind: function-exit, always-instrument: true}
+- { id: 6, address: 0x6, function: 0x6, kind: function-enter, always-instrument: true}
+- { id: 6, address: 0x7, function: 0x6, kind: function-exit, always-instrument: true}
+- { id: 7, address: 0x7, function: 0x7, kind: function-enter, always-instrument: true}
+- { id: 7, address: 0x8, function: 0x7, kind: function-exit, always-instrument: true}
+- { id: 8, address: 0x8, function: 0x8, kind: function-enter, always-instrument: true}
+- { id: 8, address: 0x9, function: 0x8, kind: function-exit, always-instrument: true}
+- { id: 9, address: 0x9, function: 0x9, kind: function-enter, always-instrument: true}
+- { id: 9, address: 0xA, function: 0x9, kind: function-exit, always-instrument: true}
 ...
--- a/test/tools/llvm-xray/X86/graph-color-simple-case.yaml
+++ b/test/tools/llvm-xray/X86/graph-color-simple-case.yaml
@ -0,0 +1,75 @@
+#RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml -t yaml -e sum -c sum \
+#RUN:    | FileCheck %s -check-prefix=EDGE
+#RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml -t yaml -v sum -b sum \
+#RUN:    | FileCheck %s -check-prefix=VERTEX
+---
+header:
+  version: 1
+  type: 0
+  constant-tsc: true
+  nonstop-tsc: true
+  cycle-frequency: 1
+records:
+  - { type: 0, func-id: 1, cpu: 1, thread: 111, kind: function-enter, tsc: 10000 }
+  - { type: 0, func-id: 1, cpu: 1, thread: 111, kind: function-exit,  tsc: 10010 }
+  - { type: 0, func-id: 2, cpu: 1, thread: 111, kind: function-enter, tsc: 10100 }
+  - { type: 0, func-id: 2, cpu: 1, thread: 111, kind: function-exit,  tsc: 10120 }
+  - { type: 0, func-id: 3, cpu: 1, thread: 111, kind: function-enter, tsc: 10200 }
+  - { type: 0, func-id: 3, cpu: 1, thread: 111, kind: function-exit,  tsc: 10230 }
+  - { type: 0, func-id: 4, cpu: 1, thread: 111, kind: function-enter, tsc: 10300 }
+  - { type: 0, func-id: 4, cpu: 1, thread: 111, kind: function-exit,  tsc: 10340 }
+  - { type: 0, func-id: 5, cpu: 1, thread: 111, kind: function-enter, tsc: 10400 }
+  - { type: 0, func-id: 5, cpu: 1, thread: 111, kind: function-exit,  tsc: 10450 }
+  - { type: 0, func-id: 6, cpu: 1, thread: 111, kind: function-enter, tsc: 10500 }
+  - { type: 0, func-id: 6, cpu: 1, thread: 111, kind: function-exit,  tsc: 10560 }
+  - { type: 0, func-id: 7, cpu: 1, thread: 111, kind: function-enter, tsc: 10600 }
+  - { type: 0, func-id: 7, cpu: 1, thread: 111, kind: function-exit,  tsc: 10670 }
+  - { type: 0, func-id: 8, cpu: 1, thread: 111, kind: function-enter, tsc: 10700 }
+  - { type: 0, func-id: 8, cpu: 1, thread: 111, kind: function-exit,  tsc: 10780 }
+  - { type: 0, func-id: 9, cpu: 1, thread: 111, kind: function-enter, tsc: 10800 }
+  - { type: 0, func-id: 9, cpu: 1, thread: 111, kind: function-exit,  tsc: 10890 }
+---
+
+
+#EDGE:     digraph xray {
+#EDGE-DAG: F0 -> F7 [label="7.{{[0-9]*}}e+01" color="#B00100"];
+#EDGE-DAG: F0 -> F2 [label="2.{{[0-9]*}}e+01" color="#FD9965"];
+#EDGE-DAG: F0 -> F9 [label="9.{{[0-9]*}}e+01" color="#7F0000"];
+#EDGE-DAG: F0 -> F4 [label="4.{{[0-9]*}}e+01" color="#E8543b"];
+#EDGE-DAG: F0 -> F6 [label="6.{{[0-9]*}}e+01" color="#C5140a"];
+#EDGE-DAG: F0 -> F1 [label="1.{{[0-9]*}}e+01" color="#FDC58c"];
+#EDGE-DAG: F0 -> F8 [label="8.{{[0-9]*}}e+01" color="#990101"];
+#EDGE-DAG: F0 -> F3 [label="3.{{[0-9]*}}e+01" color="#F5744d"];
+#EDGE-DAG: F0 -> F5 [label="5.{{[0-9]*}}e+01" color="#D83323"];
+#EDGE-DAG: F7 [label="@(7)"];
+#EDGE-DAG: F2 [label="@(2)"];
+#EDGE-DAG: F9 [label="@(9)"];
+#EDGE-DAG: F4 [label="@(4)"];
+#EDGE-DAG: F6 [label="@(6)"];
+#EDGE-DAG: F1 [label="@(1)"];
+#EDGE-DAG: F8 [label="@(8)"];
+#EDGE-DAG: F3 [label="@(3)"];
+#EDGE-DAG: F5 [label="@(5)"];
+#EDGE-NEXT:     }
+#
+#VERTEX:     digraph xray {
+#VERTEX-DAG: node [shape=record];
+#VERTEX-DAG: F0 -> F7 [label=""];
+#VERTEX-DAG: F0 -> F2 [label=""];
+#VERTEX-DAG: F0 -> F9 [label=""];
+#VERTEX-DAG: F0 -> F4 [label=""];
+#VERTEX-DAG: F0 -> F6 [label=""];
+#VERTEX-DAG: F0 -> F1 [label=""];
+#VERTEX-DAG: F0 -> F8 [label=""];
+#VERTEX-DAG: F0 -> F3 [label=""];
+#VERTEX-DAG: F0 -> F5 [label=""];
+#VERTEX-DAG: F7 [label="{@(7)|7.{{[0-9]*}}e+01}" color="#B00100"];
+#VERTEX-DAG: F2 [label="{@(2)|2.{{[0-9]*}}e+01}" color="#FD9965"];
+#VERTEX-DAG: F9 [label="{@(9)|9.{{[0-9]*}}e+01}" color="#7F0000"];
+#VERTEX-DAG: F4 [label="{@(4)|4.{{[0-9]*}}e+01}" color="#E8543b"];
+#VERTEX-DAG: F6 [label="{@(6)|6.{{[0-9]*}}e+01}" color="#C5140a"];
+#VERTEX-DAG: F1 [label="{@(1)|1.{{[0-9]*}}e+01}" color="#FDC58c"];
+#VERTEX-DAG: F8 [label="{@(8)|8.{{[0-9]*}}e+01}" color="#990101"];
+#VERTEX-DAG: F3 [label="{@(3)|3.{{[0-9]*}}e+01}" color="#F5744d"];
+#VERTEX-DAG: F5 [label="{@(5)|5.{{[0-9]*}}e+01}" color="#D83323"];
+#VERTEX-NEXT: }
--- a/test/tools/llvm-xray/X86/graph-deduce-tail-call.yaml
+++ b/test/tools/llvm-xray/X86/graph-deduce-tail-call.yaml
@ -1,5 +1,5 @@
 #RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml -t yaml -d \
-#RUN:    | FileCheck %s -check-prefix=COUNT
+#RUN:    | FileCheck %s -check-prefix=EMPTY
 #RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml -t yaml -d -e count \
 #RUN:    | FileCheck %s -check-prefix=COUNT
 #
--- a/test/tools/llvm-xray/X86/graph-simple-case.yaml
+++ b/test/tools/llvm-xray/X86/graph-simple-case.yaml
@ -1,5 +1,5 @@
 #RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml -t yaml \
-#RUN:    | FileCheck %s -check-prefix=COUNT
+#RUN:    | FileCheck %s -check-prefix=EMPTY
 #RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml -t yaml -e count \
 #RUN:    | FileCheck %s -check-prefix=COUNT
 #
--- a/tools/llvm-xray/xray-graph.cc
+++ b/tools/llvm-xray/xray-graph.cc
@ -13,13 +13,14 @@
 //===----------------------------------------------------------------------===//
 #include <algorithm>
 #include <cassert>
+#include <cmath>
 #include <system_error>
 #include <utility>

 #include "xray-extract.h"
 #include "xray-graph.h"
 #include "xray-registry.h"
-#include "llvm/Support/Errc.h"
+#include "llvm/ADT/ArrayRef.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FormatVariadic.h"
 #include "llvm/XRay/Trace.h"
@ -34,16 +35,25 @@ static cl::opt<std::string> GraphInput(cl::Positional,
                                       cl::desc("<xray log file>"),
                                       cl::Required, cl::sub(Graph));

+static cl::opt<bool>
+    GraphKeepGoing("keep-going", cl::desc("Keep going on errors encountered"),
+                   cl::sub(Graph), cl::init(false));
+static cl::alias GraphKeepGoing2("k", cl::aliasopt(GraphKeepGoing),
+                                 cl::desc("Alias for -keep-going"),
+                                 cl::sub(Graph));
+
 static cl::opt<std::string>
    GraphOutput("output", cl::value_desc("Output file"), cl::init("-"),
                cl::desc("output file; use '-' for stdout"), cl::sub(Graph));
 static cl::alias GraphOutput2("o", cl::aliasopt(GraphOutput),
                              cl::desc("Alias for -output"), cl::sub(Graph));

-static cl::opt<std::string> GraphInstrMap(
-    "instr_map", cl::desc("binary with the instrumrntation map, or "
-                          "a separate instrumentation map"),
-    cl::value_desc("binary with xray_instr_map"), cl::sub(Graph), cl::init(""));
+static cl::opt<std::string>
+    GraphInstrMap("instr_map",
+                  cl::desc("binary with the instrumrntation map, or "
+                           "a separate instrumentation map"),
+                  cl::value_desc("binary with xray_instr_map"), cl::sub(Graph),
+                  cl::init(""));
 static cl::alias GraphInstrMap2("m", cl::aliasopt(GraphInstrMap),
                                cl::desc("alias for -instr_map"),
                                cl::sub(Graph));
@ -72,8 +82,10 @@ static cl::opt<GraphRenderer::StatType>
    GraphEdgeLabel("edge-label",
                   cl::desc("Output graphs with edges labeled with this field"),
                   cl::value_desc("field"), cl::sub(Graph),
-                   cl::init(GraphRenderer::StatType::COUNT),
-                   cl::values(clEnumValN(GraphRenderer::StatType::COUNT,
+                   cl::init(GraphRenderer::StatType::NONE),
+                   cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
+                                         "Do not label Edges"),
+                              clEnumValN(GraphRenderer::StatType::COUNT,
                                         "count", "function call counts"),
                              clEnumValN(GraphRenderer::StatType::MIN, "min",
                                         "minimum function durations"),
@ -91,36 +103,120 @@ static cl::alias GraphEdgeLabel2("e", cl::aliasopt(GraphEdgeLabel),
                                 cl::desc("Alias for -edge-label"),
                                 cl::sub(Graph));

-namespace {
+static cl::opt<GraphRenderer::StatType> GraphVertexLabel(
+    "vertex-label",
+    cl::desc("Output graphs with vertices labeled with this field"),
+    cl::value_desc("field"), cl::sub(Graph),
+    cl::init(GraphRenderer::StatType::NONE),
+    cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
+                          "Do not label Edges"),
+               clEnumValN(GraphRenderer::StatType::COUNT, "count",
+                          "function call counts"),
+               clEnumValN(GraphRenderer::StatType::MIN, "min",
+                          "minimum function durations"),
+               clEnumValN(GraphRenderer::StatType::MED, "med",
+                          "median function durations"),
+               clEnumValN(GraphRenderer::StatType::PCT90, "90p",
+                          "90th percentile durations"),
+               clEnumValN(GraphRenderer::StatType::PCT99, "99p",
+                          "99th percentile durations"),
+               clEnumValN(GraphRenderer::StatType::MAX, "max",
+                          "maximum function durations"),
+               clEnumValN(GraphRenderer::StatType::SUM, "sum",
+                          "sum of call durations")));
+static cl::alias GraphVertexLabel2("v", cl::aliasopt(GraphVertexLabel),
+                                   cl::desc("Alias for -edge-label"),
+                                   cl::sub(Graph));
+
+static cl::opt<GraphRenderer::StatType> GraphEdgeColorType(
+    "color-edges",
+    cl::desc("Output graphs with edge colors determined by this field"),
+    cl::value_desc("field"), cl::sub(Graph),
+    cl::init(GraphRenderer::StatType::NONE),
+    cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
+                          "Do not label Edges"),
+               clEnumValN(GraphRenderer::StatType::COUNT, "count",
+                          "function call counts"),
+               clEnumValN(GraphRenderer::StatType::MIN, "min",
+                          "minimum function durations"),
+               clEnumValN(GraphRenderer::StatType::MED, "med",
+                          "median function durations"),
+               clEnumValN(GraphRenderer::StatType::PCT90, "90p",
+                          "90th percentile durations"),
+               clEnumValN(GraphRenderer::StatType::PCT99, "99p",
+                          "99th percentile durations"),
+               clEnumValN(GraphRenderer::StatType::MAX, "max",
+                          "maximum function durations"),
+               clEnumValN(GraphRenderer::StatType::SUM, "sum",
+                          "sum of call durations")));
+static cl::alias GraphEdgeColorType2("c", cl::aliasopt(GraphEdgeColorType),
+                                     cl::desc("Alias for -color-edges"),
+                                     cl::sub(Graph));
+
+static cl::opt<GraphRenderer::StatType> GraphVertexColorType(
+    "color-vertices",
+    cl::desc("Output graphs with vertex colors determined by this field"),
+    cl::value_desc("field"), cl::sub(Graph),
+    cl::init(GraphRenderer::StatType::NONE),
+    cl::values(clEnumValN(GraphRenderer::StatType::NONE, "none",
+                          "Do not label Edges"),
+               clEnumValN(GraphRenderer::StatType::COUNT, "count",
+                          "function call counts"),
+               clEnumValN(GraphRenderer::StatType::MIN, "min",
+                          "minimum function durations"),
+               clEnumValN(GraphRenderer::StatType::MED, "med",
+                          "median function durations"),
+               clEnumValN(GraphRenderer::StatType::PCT90, "90p",
+                          "90th percentile durations"),
+               clEnumValN(GraphRenderer::StatType::PCT99, "99p",
+                          "99th percentile durations"),
+               clEnumValN(GraphRenderer::StatType::MAX, "max",
+                          "maximum function durations"),
+               clEnumValN(GraphRenderer::StatType::SUM, "sum",
+                          "sum of call durations")));
+static cl::alias GraphVertexColorType2("b", cl::aliasopt(GraphVertexColorType),
+                                       cl::desc("Alias for -edge-label"),
+                                       cl::sub(Graph));
+
 template <class T> T diff(T L, T R) { return std::max(L, R) - std::min(L, R); }

-void updateStat(GraphRenderer::TimeStat &S, int64_t lat) {
+// Updates the statistics for a GraphRenderer::TimeStat
+static void updateStat(GraphRenderer::TimeStat &S, int64_t L) {
  S.Count++;
-  if (S.Min > lat || S.Min == 0)
-    S.Min = lat;
-  if (S.Max < lat)
-    S.Max = lat;
-  S.Sum += lat;
-}
+  if (S.Min > L || S.Min == 0)
+    S.Min = L;
+  if (S.Max < L)
+    S.Max = L;
+  S.Sum += L;
 }

-// Evaluates an XRay record and performs accounting on it, creating and
-// decorating a function call graph as it does so. It does this by maintaining
-// a call stack on a per-thread basis and adding edges and verticies to the
-// graph as they are seen for the first time.
+// Evaluates an XRay record and performs accounting on it.
 //
-// There is an immaginary root for functions at the top of their stack with
+// If the record is an ENTER record it pushes the FuncID and TSC onto a
+// structure representing the call stack for that function.
+// If the record is an EXIT record it checks computes computes the ammount of
+// time the function took to complete and then stores that information in an
+// edge of the graph. If there is no matching ENTER record the function tries
+// to recover by assuming that there were EXIT records which were missed, for
+// example caused by tail call elimination and if the option is enabled then
+// then tries to recover from this.
+//
+// This funciton will also error if the records are out of order, as the trace
+// is expected to be sorted.
+//
+// The graph generated has an immaginary root for functions called by no-one at
 // FuncId 0.
 //
-// FIXME: make more robust to errors and
-// Decorate Graph More Heavily.
 // FIXME: Refactor this and account subcommand to reduce code duplication.
-bool GraphRenderer::accountRecord(const XRayRecord &Record) {
+Error GraphRenderer::accountRecord(const XRayRecord &Record) {
+  using std::make_error_code;
+  using std::errc;
  if (CurrentMaxTSC == 0)
    CurrentMaxTSC = Record.TSC;

  if (Record.TSC < CurrentMaxTSC)
-    return false;
+    return make_error<StringError>("Records not in order",
+                                   make_error_code(errc::invalid_argument));

  auto &ThreadStack = PerThreadFunctionStack[Record.TId];
  switch (Record.Type) {
@ -136,12 +232,16 @@ bool GraphRenderer::accountRecord(const XRayRecord &Record) {
    // duplication
    if (ThreadStack.size() == 0 || ThreadStack.back().FuncId != Record.FuncId) {
      if (!DeduceSiblingCalls)
-        return false;
+        return make_error<StringError>("No matching ENTRY record",
+                                       make_error_code(errc::invalid_argument));
      auto Parent = std::find_if(
          ThreadStack.rbegin(), ThreadStack.rend(),
          [&](const FunctionAttr &A) { return A.FuncId == Record.FuncId; });
      if (Parent == ThreadStack.rend())
-        return false; // There is no matching Function for this exit.
+        return make_error<StringError>(
+            "No matching Entry record in stack",
+            make_error_code(errc::invalid_argument)); // There is no matching
+                                                      // Function for this exit.
      while (ThreadStack.back().FuncId != Record.FuncId) {
        uint64_t D = diff(ThreadStack.back().TSC, Record.TSC);
        int32_t TopFuncId = ThreadStack.back().FuncId;
@ -164,7 +264,7 @@ bool GraphRenderer::accountRecord(const XRayRecord &Record) {
  }
  }

-  return true;
+  return Error::success();
 }

 template <typename U>
@ -181,11 +281,23 @@ void GraphRenderer::getStats(U begin, U end, GraphRenderer::TimeStat &S) {
  S.Pct99 = *(begin + Pct99Off);
 }

+void GraphRenderer::updateMaxStats(const GraphRenderer::TimeStat &S,
+                                   GraphRenderer::TimeStat &M) {
+  M.Count = std::max(M.Count, S.Count);
+  M.Min = std::max(M.Min, S.Min);
+  M.Median = std::max(M.Median, S.Median);
+  M.Pct90 = std::max(M.Pct90, S.Pct90);
+  M.Pct99 = std::max(M.Pct99, S.Pct99);
+  M.Max = std::max(M.Max, S.Max);
+  M.Sum = std::max(M.Sum, S.Sum);
+}
+
 void GraphRenderer::calculateEdgeStatistics() {
  for (auto &V : Graph) {
    for (auto &E : V.second) {
      auto &A = E.second;
      getStats(A.Timings.begin(), A.Timings.end(), A.S);
+      updateMaxStats(A.S, GraphEdgeMax);
    }
  }
 }
@ -211,60 +323,162 @@ void GraphRenderer::calculateVertexStatistics() {
                         P->Timings.end());
    }
    getStats(TempTimings.begin(), TempTimings.end(), VertexAttrs[V.first].S);
+    updateMaxStats(VertexAttrs[V.first].S, GraphVertexMax);
    TempTimings.clear();
  }
 }

-void GraphRenderer::normaliseStatistics(double CycleFrequency) {
+// A Helper function for normalizeStatistics which normalises a single
+// TimeStat element.
+static void normalizeTimeStat(GraphRenderer::TimeStat &S,
+                              double CycleFrequency) {
+  S.Min /= CycleFrequency;
+  S.Median /= CycleFrequency;
+  S.Max /= CycleFrequency;
+  S.Sum /= CycleFrequency;
+  S.Pct90 /= CycleFrequency;
+  S.Pct99 /= CycleFrequency;
+}
+
+// Normalises the statistics in the graph for a given TSC frequency.
+void GraphRenderer::normalizeStatistics(double CycleFrequency) {
  for (auto &V : Graph) {
    for (auto &E : V.second) {
      auto &S = E.second.S;
-      S.Min /= CycleFrequency;
-      S.Median /= CycleFrequency;
-      S.Max /= CycleFrequency;
-      S.Sum /= CycleFrequency;
-      S.Pct90 /= CycleFrequency;
-      S.Pct99 /= CycleFrequency;
+      normalizeTimeStat(S, CycleFrequency);
    }
  }
  for (auto &V : VertexAttrs) {
    auto &S = V.second.S;
-    S.Min /= CycleFrequency;
-    S.Median /= CycleFrequency;
-    S.Max /= CycleFrequency;
-    S.Sum /= CycleFrequency;
-    S.Pct90 /= CycleFrequency;
-    S.Pct99 /= CycleFrequency;
+    normalizeTimeStat(S, CycleFrequency);
  }
+
+  normalizeTimeStat(GraphEdgeMax, CycleFrequency);
+  normalizeTimeStat(GraphVertexMax, CycleFrequency);
 }

-namespace {
-void outputEdgeInfo(const GraphRenderer::TimeStat &S, GraphRenderer::StatType T,
-                    raw_ostream &OS) {
+// Returns a string containing the value of statistic field T
+std::string
+GraphRenderer::TimeStat::getAsString(GraphRenderer::StatType T) const {
+  std::string St;
+  raw_string_ostream S{St};
  switch (T) {
  case GraphRenderer::StatType::COUNT:
-    OS << S.Count;
+    S << Count;
    break;
  case GraphRenderer::StatType::MIN:
-    OS << S.Min;
+    S << Min;
    break;
  case GraphRenderer::StatType::MED:
-    OS << S.Median;
+    S << Median;
    break;
  case GraphRenderer::StatType::PCT90:
-    OS << S.Pct90;
+    S << Pct90;
    break;
  case GraphRenderer::StatType::PCT99:
-    OS << S.Pct99;
+    S << Pct99;
    break;
  case GraphRenderer::StatType::MAX:
-    OS << S.Max;
+    S << Max;
    break;
  case GraphRenderer::StatType::SUM:
-    OS << S.Sum;
+    S << Sum;
+    break;
+  case GraphRenderer::StatType::NONE:
    break;
  }
+  return S.str();
 }
+
+// Evaluates a polynomial given the coefficints provided in an ArrayRef
+// evaluating:
+//
+//    p(x) = a[n-0]*x^0 + a[n-1]*x^1 + ... a[n-n]*x^n
+//
+// at x_0 using Horner's Method for both performance and stability reasons.
+static double polyEval(ArrayRef<double> a, double x_0) {
+  double B = 0;
+  for (const auto &c : a) {
+    B = c + B * x_0;
+  }
+  return B;
+}
+
+// Takes a double precision number, clips it between 0 and 1 and then converts
+// that to an integer between 0x00 and 0xFF with proxpper rounding.
+static uint8_t uintIntervalTo8bitChar(double B) {
+  double n = std::max(std::min(B, 1.0), 0.0);
+  return static_cast<uint8_t>(255 * n + 0.5);
+}
+
+// Gets a color in a gradient given a number in the interval [0,1], it does this
+// by evaluating a polynomial which maps [0, 1] -> [0, 1] for each of the R G
+// and B values in the color. It then converts this [0,1] colors to a 24 bit
+// color.
+//
+// In order to calculate these polynomials,
+//   1. Convert the OrRed9 color scheme from http://colorbrewer2.org/ from sRGB
+//      to LAB color space.
+//   2. Interpolate between the descrete colors in LAB space using a cubic
+//      spline interpolation.
+//   3. Sample this interpolation at 100 points and convert to sRGB.
+//   4. Calculate a polynomial fit for these 100 points for each of R G and B.
+//      We used a polynomial of degree 9 arbitrarily based on a fuzzy goodness
+//      of fit metric (using human judgement);
+//   5. Extract these polynomial coefficients from matlab as a set of constants.
+static std::string getColor(double point) {
+  assert(point >= 0.0 && point <= 1);
+  const static double RedPoly[] = {-38.4295,  239.239, -600.108, 790.544,
+                                   -591.26,   251.304, -58.0983, 6.62999,
+                                   -0.325899, 1.00173};
+  const static double GreenPoly[] = {-603.634,   2338.15, -3606.74, 2786.16,
+                                     -1085.19,   165.15,  11.2584,  -6.11338,
+                                     -0.0091078, 0.965469};
+  const static double BluePoly[] = {-325.686, 947.415,  -699.079, -513.75,
+                                    1127.78,  -732.617, 228.092,  -33.8202,
+                                    0.732108, 0.913916};
+
+  uint8_t r = uintIntervalTo8bitChar(polyEval(RedPoly, point));
+  uint8_t g = uintIntervalTo8bitChar(polyEval(GreenPoly, point));
+  uint8_t b = uintIntervalTo8bitChar(polyEval(BluePoly, point));
+
+  return llvm::formatv("#{0:X-2}{1:X-2}{2:x-2}", r, g, b);
+}
+
+// Returns the quotient between the property T of this and another TimeStat as
+// a double
+double GraphRenderer::TimeStat::compare(StatType T, const TimeStat &O) const {
+  double retval = 0;
+  switch (T) {
+  case GraphRenderer::StatType::COUNT:
+    retval = static_cast<double>(Count) / static_cast<double>(O.Count);
+    break;
+  case GraphRenderer::StatType::MIN:
+    retval = Min / O.Min;
+    break;
+  case GraphRenderer::StatType::MED:
+    retval = Median / O.Median;
+    break;
+  case GraphRenderer::StatType::PCT90:
+    retval = Pct90 / O.Pct90;
+    break;
+  case GraphRenderer::StatType::PCT99:
+    retval = Pct99 / O.Pct99;
+    break;
+  case GraphRenderer::StatType::MAX:
+    retval = Max / O.Max;
+    break;
+  case GraphRenderer::StatType::SUM:
+    retval = Sum / O.Sum;
+    break;
+  case GraphRenderer::StatType::NONE:
+    retval = 0.0;
+    break;
+  }
+  return std::sqrt(
+      retval); // the square root here provides more dynamic contrast for
+               // low runtime edges, giving better separation and
+               // coloring lower down the call stack.
 }

 // Outputs a DOT format version of the Graph embedded in the GraphRenderer
@ -274,29 +488,41 @@ void outputEdgeInfo(const GraphRenderer::TimeStat &S, GraphRenderer::StatType T,
 //
 // FIXME: output more information, better presented.
 void GraphRenderer::exportGraphAsDOT(raw_ostream &OS, const XRayFileHeader &H,
-                                     StatType T) {
+                                     StatType ET, StatType EC, StatType VT,
+                                     StatType VC) {
  calculateEdgeStatistics();
  calculateVertexStatistics();
  if (H.CycleFrequency)
-    normaliseStatistics(H.CycleFrequency);
+    normalizeStatistics(H.CycleFrequency);

  OS << "digraph xray {\n";

+  if (VT != StatType::NONE)
+    OS << "node [shape=record];\n";
+
  for (const auto &V : Graph)
    for (const auto &E : V.second) {
+      const auto &S = E.second.S;
      OS << "F" << V.first << " -> "
-         << "F" << E.first << " [label=\"";
-      outputEdgeInfo(E.second.S, T, OS);
-      OS << "\"];\n";
+         << "F" << E.first << " [label=\"" << S.getAsString(ET) << "\"";
+      if (EC != StatType::NONE)
+        OS << " color=\"" << getColor(S.compare(EC, GraphEdgeMax)) << "\"";
+      OS << "];\n";
    }

-  for (const auto &V : VertexAttrs)
-    OS << "F" << V.first << " [label=\""
-       << (V.second.SymbolName.size() > 40
-               ? V.second.SymbolName.substr(0, 40) + "..."
-               : V.second.SymbolName)
-       << "\"];\n";
-
+  for (const auto &V : VertexAttrs) {
+    const auto &VA = V.second;
+    OS << "F" << V.first << " [label=\"" << (VT != StatType::NONE ? "{" : "")
+       << (VA.SymbolName.size() > 40 ? VA.SymbolName.substr(0, 40) + "..."
+                                     : VA.SymbolName);
+    if (VT != StatType::NONE)
+      OS << "|" << VA.S.getAsString(VT) << "}\"";
+    else
+      OS << "\"";
+    if (VC != StatType::NONE)
+      OS << " color=\"" << getColor(VA.S.compare(VC, GraphVertexMax)) << "\"";
+    OS << "];\n";
+  }
  OS << "}\n";
 }

@ -352,15 +578,26 @@ static CommandRegistration Unused(&Graph, []() -> Error {
  auto &Trace = *TraceOrErr;
  const auto &Header = Trace.getFileHeader();
  for (const auto &Record : Trace) {
-    // Generate graph, FIXME: better error recovery.
-    if (!GR.accountRecord(Record)) {
-      return make_error<StringError>(
-          Twine("Failed accounting function calls in file '") + GraphInput +
-              "'.",
-          make_error_code(llvm::errc::invalid_argument));
+    // Generate graph.
+    auto E = GR.accountRecord(Record);
+    if (!E)
+      continue;
+
+    for (const auto &ThreadStack : GR.getPerThreadFunctionStack()) {
+      errs() << "Thread ID: " << ThreadStack.first << "\n";
+      auto Level = ThreadStack.second.size();
+      for (const auto &Entry : llvm::reverse(ThreadStack.second))
+        errs() << "#" << Level-- << "\t"
+               << FuncIdHelper.SymbolOrNumber(Entry.FuncId) << '\n';
    }
+
+    if (!GraphKeepGoing)
+      return joinErrors(std::move(E), std::move(Err));
+    handleAllErrors(std::move(E),
+                    [&](const ErrorInfoBase &E) { E.log(errs()); });
  }

-  GR.exportGraphAsDOT(OS, Header, GraphEdgeLabel);
-  return Error::success();
+  GR.exportGraphAsDOT(OS, Header, GraphEdgeLabel, GraphEdgeColorType,
+                      GraphVertexLabel, GraphVertexColorType);
+  return Err;
 });
--- a/tools/llvm-xray/xray-graph.h
+++ b/tools/llvm-xray/xray-graph.h
@ -15,13 +15,15 @@
 #ifndef XRAY_GRAPH_H
 #define XRAY_GRAPH_H

+#include <string>
 #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/Support/Errc.h"
 #include "llvm/Support/Program.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/XRay/Trace.h"
 #include "llvm/XRay/XRayRecord.h"

@ -32,15 +34,20 @@ namespace xray {
 /// Graphs from them and then exporting those graphs for review.
 class GraphRenderer {
 public:
+  /// An enum for enumerating the various statistics gathered on latencies
+  enum class StatType { NONE, COUNT, MIN, MED, PCT90, PCT99, MAX, SUM };
+
  /// 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;
+    uint64_t Count = 0;
+    double Min = 0;
+    double Median = 0;
+    double Pct90 = 0;
+    double Pct99 = 0;
+    double Max = 0;
+    double Sum = 0;
+    std::string getAsString(StatType T) const;
+    double compare(StatType T, const TimeStat &Other) const;
  };

  /// An inner struct for storing edge attributes for our graph. Here the
@ -61,6 +68,16 @@ public:
    TimeStat S;
  };

+  struct FunctionAttr {
+    int32_t FuncId;
+    uint64_t TSC;
+  };
+
+  typedef SmallVector<FunctionAttr, 4> FunctionStack;
+
+  typedef DenseMap<llvm::sys::ProcessInfo::ProcessId, FunctionStack>
+      PerThreadFunctionStackMap;
+
 private:
  /// The Graph stored in an edge-list like format, with the edges also having
  /// An attached set of attributes.
@ -70,17 +87,14 @@ private:
  /// main graph.
  DenseMap<int32_t, VertexAttribute> VertexAttrs;

-  struct FunctionAttr {
-    int32_t FuncId;
-    uint64_t TSC;
-  };
+  TimeStat GraphEdgeMax;
+  TimeStat GraphVertexMax;

  /// 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<llvm::sys::ProcessInfo::ProcessId, SmallVector<FunctionAttr, 4>>
-      PerThreadFunctionStack;
+  PerThreadFunctionStackMap PerThreadFunctionStack;

  /// Usefull object for getting human readable Symbol Names.
  FuncIdConversionHelper &FuncIdHelper;
@ -90,6 +104,7 @@ private:
  /// A private function to help implement the statistic generation functions;
  template <typename U>
  void getStats(U begin, U end, GraphRenderer::TimeStat &S);
+  void updateMaxStats(const TimeStat &S, TimeStat &M);

  /// Calculates latency statistics for each edge and stores the data in the
  /// Graph
@ -100,7 +115,7 @@ private:
  void calculateVertexStatistics();

  /// Normalises latency statistics for each edge and vertex by CycleFrequency;
-  void normaliseStatistics(double CycleFrequency);
+  void normalizeStatistics(double CycleFrequency);

 public:
  /// Takes in a reference to a FuncIdHelper in order to have ready access to
@ -115,15 +130,19 @@ public:
  /// Records should be in order runtime on an ideal system.)
  ///
  /// FIXME: Make this more robust against small irregularities.
-  bool accountRecord(const XRayRecord &Record);
+  Error accountRecord(const XRayRecord &Record);

-  /// An enum for enumerating the various statistics gathered on latencies
-  enum class StatType { COUNT, MIN, MED, PCT90, PCT99, MAX, SUM };
+  const PerThreadFunctionStackMap getPerThreadFunctionStack() const {
+    return PerThreadFunctionStack;
+  }

  /// 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);
+                        StatType EdgeLabel = StatType::NONE,
+                        StatType EdgeColor = StatType::NONE,
+                        StatType VertexLabel = StatType::NONE,
+                        StatType VertexColor = StatType::NONE);
 };
 }
 }