[Command] Implement `statistics` command.

This allows us to collect useful metrics about lldb debugging sessions.

I thought that an example would be better than a thousand words:

  Process 19705 stopped
  * thread #1, queue = 'com.apple.main-thread', stop reason = step in
      frame #0: 0x0000000100000fb4 blah`main at blah.c:3
     1    int main(void) {
     2      int a = 6;
  -> 3      return 0;
     4    }
  (lldb) statistics enable
  (lldb) frame var a
  (int) a = 6
  (lldb) expr a
  (int) $1 = 6
  (lldb) statistics disable
  (lldb) statistics dump
  Number of expr evaluation successes : 1
  Number of expr evaluation failures : 0
  Number of frame var successes : 1
  Number of frame var failures : 0

Future improvements might include:

1. Passing a file, or implementing categories. The way this patch has
been implemented is generic enough to allow this to be extended
easily without breaking the grammar.
2. Adding an SBAPI and Python API for use in scripts.

Thanks to Jim Ingham for discussing the design with me.

<rdar://problem/36555975>

Differential Revision:  https://reviews.llvm.org/D45547

llvm-svn: 330043

lldb/include/lldb/Target/Target.h

@@ -35,6 +35,7 @@
 #include "lldb/Target/ProcessLaunchInfo.h"
 #include "lldb/Target/SectionLoadHistory.h"
 #include "lldb/Utility/ArchSpec.h"
+#include "lldb/Utility/LLDBAssert.h"
 #include "lldb/Utility/Timeout.h"
 #include "lldb/lldb-public.h"
 
@@ -1284,6 +1285,28 @@ protected:
   static void ImageSearchPathsChanged(const PathMappingList &path_list,
                                       void *baton);
 
+  //------------------------------------------------------------------
+  // Utilities for `statistics` command.
+  //------------------------------------------------------------------
+private:
+  std::vector<uint32_t> m_stats_storage;
+  bool m_collecting_stats = false;
+
+public:
+  void SetCollectingStats(bool v) { m_collecting_stats = v; }
+
+  bool GetCollectingStats() { return m_collecting_stats; }
+
+  void IncrementStats(lldb_private::StatisticKind key) {
+    if (!GetCollectingStats())
+      return;
+    lldbassert(key < lldb_private::StatisticKind::StatisticMax &&
+               "invalid statistics!");
+    m_stats_storage[key] += 1;
+  }
+
+  std::vector<uint32_t> GetStatistics() { return m_stats_storage; }
+
 private:
   //------------------------------------------------------------------
   /// Construct with optional file and arch.

lldb/include/lldb/lldb-private-enumerations.h

@@ -234,6 +234,18 @@ enum class CompilerContextKind {
   Typedef
 };
 
+//----------------------------------------------------------------------
+// Enumerations that can be used to specify the kind of metric we're
+// looking at when collecting stats.
+//----------------------------------------------------------------------
+enum StatisticKind {
+  ExpressionSuccessful = 0,
+  ExpressionFailure = 1,
+  FrameVarSuccess = 2,
+  FrameVarFailure = 3,
+  StatisticMax = 4
+};
+
 } // namespace lldb_private
 
 namespace llvm {

lldb/packages/Python/lldbsuite/test/functionalities/stats/Makefile

@@ -0,0 +1,3 @@
+LEVEL = ../../make
+C_SOURCES := main.c
+include $(LEVEL)/Makefile.rules

lldb/packages/Python/lldbsuite/test/functionalities/stats/TestStats.py

@@ -0,0 +1,5 @@
+from lldbsuite.test import lldbinline
+from lldbsuite.test import decorators
+
+lldbinline.MakeInlineTest(
+    __file__, globals(), [])

lldb/packages/Python/lldbsuite/test/functionalities/stats/main.c

@@ -0,0 +1,18 @@
+// Test that the lldb command `statistics` works.
+
+int main(void) {
+  int patatino = 27;
+  //%self.expect("statistics disable", substrs=['need to enable statistics before disabling'], error=True)
+  //%self.expect("statistics enable")
+  //%self.expect("statistics enable", substrs=['already enabled'], error=True)
+  //%self.expect("expr patatino", substrs=['27'])
+  //%self.expect("statistics disable")
+  //%self.expect("statistics dump", substrs=['expr evaluation successes : 1', 'expr evaluation failures : 0'])
+  //%self.expect("frame var", substrs=['27'])
+  //%self.expect("statistics enable")
+  //%self.expect("frame var", substrs=['27'])
+  //%self.expect("statistics disable")
+  //%self.expect("statistics dump", substrs=['frame var successes : 1', 'frame var failures : 0'])
+
+  return 0;
+}

lldb/source/Commands/CommandObjectExpression.cpp

@@ -623,11 +623,12 @@ bool CommandObjectExpression::DoExecute(const char *command,
   if (expr == nullptr)
     expr = command;
 
+  Target *target = m_interpreter.GetExecutionContext().GetTargetPtr();
+  if (!target)
+    target = GetDummyTarget();
+
   if (EvaluateExpression(expr, &(result.GetOutputStream()),
                          &(result.GetErrorStream()), &result)) {
-    Target *target = m_interpreter.GetExecutionContext().GetTargetPtr();
-    if (!target)
-        target = GetDummyTarget();
 
     if (!m_fixed_expression.empty() && target->GetEnableNotifyAboutFixIts()) {
       CommandHistory &history = m_interpreter.GetCommandHistory();
@@ -644,9 +645,15 @@ bool CommandObjectExpression::DoExecute(const char *command,
       }
       history.AppendString(fixed_command);
     }
+    // Increment statistics to record this expression evaluation
+    // success.
+    target->IncrementStats(StatisticKind::ExpressionSuccessful);
     return true;
   }
 
+  // Increment statistics to record this expression evaluation
+  // failure.
+  target->IncrementStats(StatisticKind::ExpressionFailure);
   result.SetStatus(eReturnStatusFailed);
   return false;
 }

lldb/source/Commands/CommandObjectFrame.cpp

@@ -720,7 +720,16 @@ protected:
       m_interpreter.TruncationWarningGiven();
     }
 
-    return result.Succeeded();
+    // Increment statistics.
+    bool res = result.Succeeded();
+    Target *target = m_exe_ctx.GetTargetPtr();
+    if (!target)
+      target = GetDummyTarget();
+    if (res)
+      target->IncrementStats(StatisticKind::FrameVarSuccess);
+    else
+      target->IncrementStats(StatisticKind::FrameVarFailure);
+    return res;
   }
 
 protected:

lldb/source/Commands/CommandObjectStats.cpp

@@ -11,18 +11,114 @@
 #include "lldb/Host/Host.h"
 #include "lldb/Interpreter/CommandInterpreter.h"
 #include "lldb/Interpreter/CommandReturnObject.h"
+#include "lldb/Target/Target.h"
 
 using namespace lldb;
 using namespace lldb_private;
 
+class CommandObjectStatsEnable : public CommandObjectParsed {
+public:
+  CommandObjectStatsEnable(CommandInterpreter &interpreter)
+      : CommandObjectParsed(interpreter, "enable",
+                            "Enable statistics collection", nullptr,
+                            eCommandProcessMustBePaused) {}
+
+  ~CommandObjectStatsEnable() override = default;
+
+protected:
+  bool DoExecute(Args &command, CommandReturnObject &result) override {
+    Target *target = GetSelectedOrDummyTarget();
+
+    if (target->GetCollectingStats()) {
+      result.AppendError("statistics already enabled");
+      result.SetStatus(eReturnStatusFailed);
+      return false;
+    }
+
+    target->SetCollectingStats(true);
+    result.SetStatus(eReturnStatusSuccessFinishResult);
+    return true;
+  }
+};
+
+class CommandObjectStatsDisable : public CommandObjectParsed {
+public:
+  CommandObjectStatsDisable(CommandInterpreter &interpreter)
+      : CommandObjectParsed(interpreter, "disable",
+                            "Disable statistics collection", nullptr,
+                            eCommandProcessMustBePaused) {}
+
+  ~CommandObjectStatsDisable() override = default;
+
+protected:
+  bool DoExecute(Args &command, CommandReturnObject &result) override {
+    Target *target = GetSelectedOrDummyTarget();
+
+    if (!target->GetCollectingStats()) {
+      result.AppendError("need to enable statistics before disabling them");
+      result.SetStatus(eReturnStatusFailed);
+      return false;
+    }
+
+    target->SetCollectingStats(false);
+    result.SetStatus(eReturnStatusSuccessFinishResult);
+    return true;
+  }
+};
+
+class CommandObjectStatsDump : public CommandObjectParsed {
+private:
+  std::string GetStatDescription(lldb_private::StatisticKind K) {
+    switch (K) {
+    case StatisticKind::ExpressionSuccessful:
+      return "Number of expr evaluation successes";
+    case StatisticKind::ExpressionFailure:
+      return "Number of expr evaluation failures";
+    case StatisticKind::FrameVarSuccess:
+      return "Number of frame var successes";
+    case StatisticKind::FrameVarFailure:
+      return "Number of frame var failures";
+    case StatisticKind::StatisticMax:
+      return "";
+    }
+    llvm_unreachable("Statistic not registered!");
+  }
+
+public:
+  CommandObjectStatsDump(CommandInterpreter &interpreter)
+      : CommandObjectParsed(interpreter, "dump", "Dump statistics results",
+                            nullptr, eCommandProcessMustBePaused) {}
+
+  ~CommandObjectStatsDump() override = default;
+
+protected:
+  bool DoExecute(Args &command, CommandReturnObject &result) override {
+    Target *target = GetSelectedOrDummyTarget();
+
+    uint32_t i = 0;
+    for (auto &stat : target->GetStatistics()) {
+      result.AppendMessageWithFormat(
+          "%s : %u\n",
+          GetStatDescription(static_cast<lldb_private::StatisticKind>(i))
+              .c_str(),
+          stat);
+      i += 1;
+    }
+    result.SetStatus(eReturnStatusSuccessFinishResult);
+    return true;
+  }
+};
+
 CommandObjectStats::CommandObjectStats(CommandInterpreter &interpreter)
-    : CommandObjectParsed(
-          interpreter, "stats", "Print statistics about a debugging session",
-          nullptr) {
+    : CommandObjectMultiword(interpreter, "statistics",
+                             "Print statistics about a debugging session",
+                             "statistics <subcommand> [<subcommand-options>]") {
+  LoadSubCommand("enable",
+                 CommandObjectSP(new CommandObjectStatsEnable(interpreter)));
+  LoadSubCommand("disable",
+                 CommandObjectSP(new CommandObjectStatsDisable(interpreter)));
+  LoadSubCommand("dump",
+                 CommandObjectSP(new CommandObjectStatsDump(interpreter)));
 }
 
-bool CommandObjectStats::DoExecute(Args &command, CommandReturnObject &result) {
-  return true;
-}
-
-CommandObjectStats::~CommandObjectStats() {}
+CommandObjectStats::~CommandObjectStats() = default;

lldb/source/Commands/CommandObjectStats.h

@@ -11,16 +11,14 @@
 #define liblldb_CommandObjectStats_h_
 
 #include "lldb/Interpreter/CommandObject.h"
+#include "lldb/Interpreter/CommandObjectMultiword.h"
 
 namespace lldb_private {
-class CommandObjectStats : public CommandObjectParsed {
+class CommandObjectStats : public CommandObjectMultiword {
 public:
   CommandObjectStats(CommandInterpreter &interpreter);
 
   ~CommandObjectStats() override;
-
-protected:
-  bool DoExecute(Args &command, CommandReturnObject &result) override;
 };
 } // namespace lldb_private
 

lldb/source/Interpreter/CommandInterpreter.cpp

@@ -425,7 +425,7 @@ void CommandInterpreter::LoadCommandDictionary() {
       CommandObjectSP(new CommandObjectMultiwordSettings(*this));
   m_command_dict["source"] =
       CommandObjectSP(new CommandObjectMultiwordSource(*this));
-  m_command_dict["stats"] = CommandObjectSP(new CommandObjectStats(*this));
+  m_command_dict["statistics"] = CommandObjectSP(new CommandObjectStats(*this));
   m_command_dict["target"] =
       CommandObjectSP(new CommandObjectMultiwordTarget(*this));
   m_command_dict["thread"] =

lldb/source/Target/Target.cpp

@@ -87,13 +87,14 @@ Target::Target(Debugger &debugger, const ArchSpec &target_arch,
       Broadcaster(debugger.GetBroadcasterManager(),
                   Target::GetStaticBroadcasterClass().AsCString()),
       ExecutionContextScope(), m_debugger(debugger), m_platform_sp(platform_sp),
-      m_mutex(), m_arch(target_arch),
-      m_images(this), m_section_load_history(), m_breakpoint_list(false),
-      m_internal_breakpoint_list(true), m_watchpoint_list(), m_process_sp(),
-      m_search_filter_sp(), m_image_search_paths(ImageSearchPathsChanged, this),
-      m_ast_importer_sp(), m_source_manager_ap(), m_stop_hooks(),
-      m_stop_hook_next_id(0), m_valid(true), m_suppress_stop_hooks(false),
-      m_is_dummy_target(is_dummy_target)
+      m_mutex(), m_arch(target_arch), m_images(this), m_section_load_history(),
+      m_breakpoint_list(false), m_internal_breakpoint_list(true),
+      m_watchpoint_list(), m_process_sp(), m_search_filter_sp(),
+      m_image_search_paths(ImageSearchPathsChanged, this), m_ast_importer_sp(),
+      m_source_manager_ap(), m_stop_hooks(), m_stop_hook_next_id(0),
+      m_valid(true), m_suppress_stop_hooks(false),
+      m_is_dummy_target(is_dummy_target),
+      m_stats_storage(static_cast<int>(StatisticKind::StatisticMax))
 
 {
   SetEventName(eBroadcastBitBreakpointChanged, "breakpoint-changed");