Merge pull request scala#10795 from szeiger/wip/collect-statistics-2.13

Collect statistics without printing them

Author: lrytz

src/compiler/scala/tools/nsc/Global.scala

@@ -1326,7 +1326,7 @@ class Global(var currentSettings: Settings, reporter0: Reporter)
       checkPhaseSettings(including = false, exclusions.map(_.value): _*)
 
       // Report the overhead of statistics measurements per every run
-      if (settings.areStatisticsEnabled)
+      if (settings.areStatisticsEnabled && settings.Ystatistics.value.nonEmpty)
         statistics.reportStatisticsOverhead(reporter)
 
       phase = first   //parserPhase
@@ -1628,7 +1628,7 @@ class Global(var currentSettings: Settings, reporter0: Reporter)
       }
       symSource.keys foreach (x => resetPackageClass(x.owner))
 
-      if (timePhases) {
+      if (timePhases && settings.Ystatistics.value.nonEmpty) {
         statistics.stopTimer(totalCompileTime, startTotal)
         informTime("total", totalCompileTime.nanos)
         inform("*** Cumulative timers for phases")

src/compiler/scala/tools/nsc/settings/ScalaSettings.scala

@@ -607,12 +607,14 @@ trait ScalaSettings extends StandardScalaSettings with Warnings { _: MutableSett
     .withAbbreviation("-Yshow-symkinds")
   val Yshowsymowners  = BooleanSetting    ("-Vshow-symowners", "Print owner identifiers next to symbol names.")
     .withAbbreviation("-Yshow-symowners")
-  val Ystatistics = PhasesSetting("-Vstatistics", "Print compiler statistics for specific phases", "parser,typer,patmat,erasure,cleanup,jvm")
-    .withPostSetHook(s => YstatisticsEnabled.value = s.value.nonEmpty)
+  val Ystatistics = PhasesSetting("-Vstatistics", "Print compiler statistics for specific phases (implies `-Ycollect-statistics`)", "parser,typer,patmat,erasure,cleanup,jvm")
+    .withPostSetHook(s => if (s.value.nonEmpty) YstatisticsEnabled.value = true)
     .withAbbreviation("-Ystatistics")
   val YstatisticsEnabled = BooleanSetting("-Ystatistics-enabled", "Internal setting, indicating that statistics are enabled for some phase.").internalOnly().withPostSetHook(s => if (s.value) StatisticsStatics.enableColdStatsAndDeoptimize())
   val YhotStatisticsEnabled = BooleanSetting("-Vhot-statistics", s"Enable `${Ystatistics.name}` to also print hot statistics.")
     .withAbbreviation("-Yhot-statistics").withPostSetHook(s => if (s.value && YstatisticsEnabled.value) StatisticsStatics.enableHotStatsAndDeoptimize())
+  val YcollectStatistics = BooleanSetting("-Ycollect-statistics", "Collect cold statistics (quietly, unless `-Vstatistics` is set)")
+    .withPostSetHook(s => if (s.value) YstatisticsEnabled.value = true)
   val Yshowsyms       = BooleanSetting("-Vsymbols", "Print the AST symbol hierarchy after each phase.") withAbbreviation "-Yshow-syms"
   val Ytyperdebug        = BooleanSetting("-Vtyper", "Trace type assignments.") withAbbreviation "-Ytyper-debug"
   val Vimplicits            = BooleanSetting("-Vimplicits", "Print dependent missing implicits.").withAbbreviation("-Xlog-implicits")