[llvm-dev] printing statistics timers

[George Karpenkov via llvm-dev]

The diff which I’ve ended up using to do what I need is:

diff --git a/lib/Support/Timer.cpp b/lib/Support/Timer.cpp
index 0c85faecca8..7fe8d776cfb 100644
--- a/lib/Support/Timer.cpp
+++ b/lib/Support/Timer.cpp
@@ -336,10 +336,16 @@ void TimerGroup::prepareToPrintList() {
   // reset them.
   for (Timer *T = FirstTimer; T; T = T->Next) {
     if (!T->hasTriggered()) continue;
+
+    bool WasRunning = T->isRunning();
+    if (WasRunning)
+      T->stopTimer();
+
     TimersToPrint.emplace_back(T->Time, T->Name, T->Description);
 
-    // Clear out the time.
-    T->clear();
+    if (WasRunning)
+      T->startTimer();
   }
 }
 
…but the code could race, so further hints are welcome.

> On Feb 6, 2018, at 6:42 PM, George Karpenkov <ekarpenkov at apple.com> wrote:
> 
> Hi,
> 
> The code in Support/Timer.cpp has strangely inconsistent behavior for printAll vs printJSONValues.
> The former can work multiple times, while the latter calls prepareToPrintList(), which stops all timers,
> hence making all further attempts to print timers crash.
> 
> Would it be possible not to call prepareToPrintList on printJSONValues, or at least make it optional?
> I am trying to serialize displayed statistic using PrintStatisticJSON, and it actually crashes if the statistic is printed again
> due to stopped timers.
> 
> George