Bug 1241249 - Add an SPS pseudo entry for JS stack capturing; r=shu

This commit adds SPS pseudo frame entries for
`js::SavedStacks::saveCurrentStack` with the `AutoSPSEntry` RAII class.

js/src/vm/SavedStacks.cpp

@@ -27,6 +27,7 @@
 #include "js/Vector.h"
 #include "vm/Debugger.h"
 #include "vm/SavedFrame.h"
+#include "vm/SPSProfiler.h"
 #include "vm/StringBuffer.h"
 #include "vm/Time.h"
 #include "vm/WrapperObject.h"
@@ -1010,6 +1011,7 @@ SavedStacks::saveCurrentStack(JSContext* cx, MutableHandleSavedFrame frame, unsi
         return true;
     }
 
+    AutoSPSEntry psuedoFrame(cx->runtime(), "js::SavedStacks::saveCurrentStack");
     FrameIter iter(cx, FrameIter::ALL_CONTEXTS, FrameIter::GO_THROUGH_SAVED);
     return insertFrames(cx, iter, frame, maxFrameCount);
 }

tools/profiler/tests/test_saved_stacks.js

@@ -0,0 +1,69 @@
+// Test that we get `js::SavedStacks::saveCurrentStack` frames.
+
+function run_test() {
+  let p = Cc["@mozilla.org/tools/profiler;1"];
+  // Just skip the test if the profiler component isn't present.
+  if (!p)
+    return;
+  p = p.getService(Ci.nsIProfiler);
+  if (!p)
+    return;
+
+  const { saveStack } = Cu.getJSTestingFunctions();
+
+  const ms = 5;
+  p.StartProfiler(100, ms, ["js"], 1);
+
+  let then = Date.now();
+  while (Date.now() - then < 30000) {
+    function a() {
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+      saveStack();
+    }
+
+    a();
+    a();
+    a();
+    a();
+    a();
+
+    function b() {
+      a();
+    }
+
+    b();
+    b();
+    b();
+    b();
+    b();
+  }
+
+  var profile = p.getProfileData().threads[0];
+
+  do_check_neq(profile.samples.data.length, 0);
+
+  let found = false;
+  for (let sample of profile.samples.data) {
+    const stack = getInflatedStackLocations(profile, sample);
+    for (let frame of stack) {
+      if (frame.indexOf("js::SavedStacks::saveCurrentStack") >= 0) {
+        found = true;
+        break;
+      }
+    }
+  }
+  do_check_true(found);
+
+  p.StopProfiler();
+}

tools/profiler/tests/xpcshell.ini

@@ -16,3 +16,4 @@ skip-if = !debug
 [test_enterjit_osr_enabling.js]
 skip-if = !debug
 [test_asm.js]
+[test_saved_stacks.js]