From: Dean Michael Berris <dberris@google.com>
Date: Fri, 31 Mar 2017 01:56:45 +0000 (+0000)
Subject: [XRay][tools] Remove some assertions in llvm-xray graph
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=365612c08f3e1380ddfbb0748353d4585894d542;p=llvm

[XRay][tools] Remove some assertions in llvm-xray graph

Summary:
Assertions assuming that function calls may not have zero durations do
not seem to hold in the wild. There are valid cases where the conversion
of the tsc counters end up becoming zero-length durations. These
assertions don't really hold and the algorithms don't need those to be
true for them to work.

Reviewers: dblaikie, echristo

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D31519

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@299150 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/test/tools/llvm-xray/X86/graph-zero-latency-calls.yaml b/test/tools/llvm-xray/X86/graph-zero-latency-calls.yaml
new file mode 100644
index 00000000000..602f209072a
--- /dev/null
+++ b/test/tools/llvm-xray/X86/graph-zero-latency-calls.yaml
@@ -0,0 +1,20 @@
+#RUN: llvm-xray graph %s -o - -m %S/Inputs/simple-instrmap.yaml | FileCheck %s
+
+---
+header:
+  version: 1
+  type: 0
+  constant-tsc: true
+  nonstop-tsc: true
+  cycle-frequency: 2601000000
+records:
+  - { type: 0, func-id: 1, cpu: 1, thread: 111, kind: function-enter, tsc: 10001 }
+  - { type: 0, func-id: 2, cpu: 1, thread: 111, kind: function-enter, tsc: 10002 }
+  - { type: 0, func-id: 2, cpu: 1, thread: 111, kind: function-exit, tsc: 10002 }
+  - { type: 0, func-id: 1, cpu: 1, thread: 111, kind: function-exit, tsc: 10100 }
+...
+
+#CHECK:     digraph xray {
+#CHECK-DAG:   F0 -> F1 [{{.*}}];
+#CHECK-DAG:   F1 -> F2 [{{.*}}];
+#CHECK-DAG: }
diff --git a/tools/llvm-xray/xray-graph.cc b/tools/llvm-xray/xray-graph.cc
index 9fdc099b6be..9be0b70c2cd 100644
--- a/tools/llvm-xray/xray-graph.cc
+++ b/tools/llvm-xray/xray-graph.cc
@@ -259,7 +259,7 @@ Error GraphRenderer::accountRecord(const XRayRecord &Record) {
 
 template <typename U>
 void GraphRenderer::getStats(U begin, U end, GraphRenderer::TimeStat &S) {
-  assert(begin != end);
+  if (begin == end) return;
   std::ptrdiff_t MedianOff = S.Count / 2;
   std::nth_element(begin, begin + MedianOff, end);
   S.Median = *(begin + MedianOff);
@@ -287,9 +287,7 @@ void GraphRenderer::calculateEdgeStatistics() {
   for (auto &E : G.edges()) {
     auto &A = E.second;
     assert(!A.Timings.empty());
-    assert((A.Timings[0] > 0));
     getStats(A.Timings.begin(), A.Timings.end(), A.S);
-    assert(A.S.Sum > 0);
     updateMaxStats(A.S, G.GraphEdgeMax);
   }
 }
@@ -297,15 +295,12 @@ void GraphRenderer::calculateEdgeStatistics() {
 void GraphRenderer::calculateVertexStatistics() {
   std::vector<uint64_t> TempTimings;
   for (auto &V : G.vertices()) {
-    assert((V.first == 0 || G[V.first].S.Sum != 0) &&
-           "Every non-root vertex should have at least one call");
     if (V.first != 0) {
       for (auto &E : G.inEdges(V.first)) {
         auto &A = E.second;
         TempTimings.insert(TempTimings.end(), A.Timings.begin(),
                            A.Timings.end());
       }
-      assert(!TempTimings.empty() && TempTimings[0] > 0);
       getStats(TempTimings.begin(), TempTimings.end(), G[V.first].S);
       updateMaxStats(G[V.first].S, G.GraphVertexMax);
       TempTimings.clear();