Add more information to the log timer dump

Summary:
The `log timer dump` is showing the time of the function itself minus any function that is called from this one that also happens to be timed. However, this is really not obvious and it also makes it hard to understand the time spent in total and also which children are actually taking the time.
To get a better reading of the timer dump I added the total, children (which I named child) and also the hit count. I used these timers to figure out a performance issue and only after adding this things were more clear to me.

It looks like this:
```
(lldb) log timer dump
35.447713617 sec (total: 35.449s; child: 0.001s; count: 1374) for void SymbolFileDWARF::Index()
29.717921481 sec (total: 29.718s; child: 0.000s; count: 8230500) for const lldb_private::ConstString &lldb_private::Mangled::GetDemangledName(lldb::LanguageType) const
21.049508865 sec (total: 24.683s; child: 3.633s; count: 1399) for void lldb_private::Symtab::InitNameIndexes()
...
```

Reviewers: clayborg, teemperor, labath, espindola, xiaobai

Reviewed By: labath, xiaobai

Subscribers: emaste, mgorny, arichardson, eraman, MaskRay, jdoerfert, labath, davide, teemperor, aprantl, erik.pilkington, jfb, abidh, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D61235

llvm-svn: 361987

1 files changed, 32 insertions, 12 deletions

diff --git a/lldb/source/Utility/Timer.cpp b/lldb/source/Utility/Timer.cpp
index 68319244976..7492045bc32 100644
--- a/lldb/source/Utility/Timer.cpp
+++ b/lldb/source/Utility/Timer.cpp
@@ -41,6 +41,8 @@ static TimerStack &GetTimerStackForCurrentThread() {
 
 Timer::Category::Category(const char *cat) : m_name(cat) {
   m_nanos.store(0, std::memory_order_release);
+  m_nanos_total.store(0, std::memory_order_release);
+  m_count.store(0, std::memory_order_release);
   Category *expected = g_categories;
   do {
     m_next = expected;
@@ -93,6 +95,8 @@ Timer::~Timer() {
 
   // Keep total results for each category so we can dump results.
   m_category.m_nanos += std::chrono::nanoseconds(timer_dur).count();
+  m_category.m_nanos_total += std::chrono::nanoseconds(total_dur).count();
+  m_category.m_count++;
 }
 
 void Timer::SetDisplayDepth(uint32_t depth) { g_display_depth = depth; }
@@ -100,25 +104,38 @@ void Timer::SetDisplayDepth(uint32_t depth) { g_display_depth = depth; }
 /* binary function predicate:
  * - returns whether a person is less than another person
  */
-
-typedef std::pair<const char *, uint64_t> TimerEntry;
-
-static bool CategoryMapIteratorSortCriterion(const TimerEntry &lhs,
-                                             const TimerEntry &rhs) {
-  return lhs.second > rhs.second;
+namespace {
+struct Stats {
+  const char *name;
+  uint64_t nanos;
+  uint64_t nanos_total;
+  uint64_t count;
+};
+} // namespace
+
+static bool CategoryMapIteratorSortCriterion(const Stats &lhs,
+                                             const Stats &rhs) {
+  return lhs.nanos > rhs.nanos;
 }
 
 void Timer::ResetCategoryTimes() {
-  for (Category *i = g_categories; i; i = i->m_next)
+  for (Category *i = g_categories; i; i = i->m_next) {
     i->m_nanos.store(0, std::memory_order_release);
+    i->m_nanos_total.store(0, std::memory_order_release);
+    i->m_count.store(0, std::memory_order_release);
+  }
 }
 
 void Timer::DumpCategoryTimes(Stream *s) {
-  std::vector<TimerEntry> sorted;
+  std::vector<Stats> sorted;
   for (Category *i = g_categories; i; i = i->m_next) {
     uint64_t nanos = i->m_nanos.load(std::memory_order_acquire);
-    if (nanos)
-      sorted.push_back(std::make_pair(i->m_name, nanos));
+    if (nanos) {
+      uint64_t nanos_total = i->m_nanos_total.load(std::memory_order_acquire);
+      uint64_t count = i->m_count.load(std::memory_order_acquire);
+      Stats stats{i->m_name, nanos, nanos_total, count};
+      sorted.push_back(stats);
+    }
   }
   if (sorted.empty())
     return; // Later code will break without any elements.
@@ -126,6 +143,9 @@ void Timer::DumpCategoryTimes(Stream *s) {
   // Sort by time
   llvm::sort(sorted.begin(), sorted.end(), CategoryMapIteratorSortCriterion);
 
-  for (const auto &timer : sorted)
-    s->Printf("%.9f sec for %s\n", timer.second / 1000000000., timer.first);
+  for (const auto &stats : sorted)
+    s->Printf("%.9f sec (total: %.3fs; child: %.3fs; count: %llu) for %s\n",
+              stats.nanos / 1000000000., stats.nanos_total / 1000000000.,
+              (stats.nanos_total - stats.nanos) / 1000000000., stats.count,
+              stats.name);
 }