Add setting to require hardware breakpoints.

When debugging read-only memory we cannot use software breakpoint. We
already have support for hardware breakpoints and users can specify them
with `-H`. However, there's no option to force LLDB to use hardware
breakpoints internally, for example while stepping.

This patch adds a setting target.require-hardware-breakpoint that forces
LLDB to always use hardware breakpoints. Because hardware breakpoints
are a limited resource and can fail to resolve, this patch also extends
error handling in thread plans, where breakpoints are used for stepping.

Differential revision: https://reviews.llvm.org/D54221

llvm-svn: 346920

lldb/include/lldb/API/SBBreakpoint.h

@@ -129,6 +129,8 @@ class LLDB_API SBBreakpoint {
   static uint32_t
   GetNumBreakpointLocationsFromEvent(const lldb::SBEvent &event_sp);
 
+  bool IsHardware() const;
+
   // Can only be called from a ScriptedBreakpointResolver...
   SBError
   AddLocation(SBAddress &address);

lldb/include/lldb/API/SBThreadPlan.h

@@ -79,16 +79,28 @@ class LLDB_API SBThreadPlan {
   // plans...
   SBThreadPlan QueueThreadPlanForStepOverRange(SBAddress &start_address,
                                                lldb::addr_t range_size);
+  SBThreadPlan QueueThreadPlanForStepOverRange(SBAddress &start_address,
+                                               lldb::addr_t range_size,
+                                               SBError &error);
 
   SBThreadPlan QueueThreadPlanForStepInRange(SBAddress &start_address,
                                              lldb::addr_t range_size);
+  SBThreadPlan QueueThreadPlanForStepInRange(SBAddress &start_address,
+                                             lldb::addr_t range_size,
+                                             SBError &error);
 
   SBThreadPlan QueueThreadPlanForStepOut(uint32_t frame_idx_to_step_to,
                                          bool first_insn = false);
+  SBThreadPlan QueueThreadPlanForStepOut(uint32_t frame_idx_to_step_to,
+                                         bool first_insn, SBError &error);
 
   SBThreadPlan QueueThreadPlanForRunToAddress(SBAddress address);
+  SBThreadPlan QueueThreadPlanForRunToAddress(SBAddress address,
+                                              SBError &error);
 
   SBThreadPlan QueueThreadPlanForStepScripted(const char *script_class_name);
+  SBThreadPlan QueueThreadPlanForStepScripted(const char *script_class_name,
+                                              SBError &error);
 
 #ifndef SWIG
   lldb_private::ThreadPlan *get();

lldb/include/lldb/Breakpoint/Breakpoint.h

@@ -498,6 +498,14 @@ class Breakpoint : public std::enable_shared_from_this<Breakpoint>,
   //------------------------------------------------------------------
   size_t GetNumResolvedLocations() const;
 
+  //------------------------------------------------------------------
+  /// Return whether this breakpoint has any resolved locations.
+  ///
+  /// @return
+  ///     True if GetNumResolvedLocations > 0
+  //------------------------------------------------------------------
+  bool HasResolvedLocations() const;
+
   //------------------------------------------------------------------
   /// Return the number of breakpoint locations.
   ///

lldb/include/lldb/Target/Target.h

@@ -198,6 +198,10 @@ class TargetProperties : public Properties {
 
   bool GetUseModernTypeLookup() const;
 
+  void SetRequireHardwareBreakpoints(bool b);
+
+  bool GetRequireHardwareBreakpoints() const;
+
 private:
   //------------------------------------------------------------------
   // Callbacks for m_launch_info.

lldb/include/lldb/Target/Thread.h

@@ -53,7 +53,7 @@ class ThreadProperties : public Properties {
   bool GetStepInAvoidsNoDebug() const;
 
   bool GetStepOutAvoidsNoDebug() const;
-  
+
   uint64_t GetMaxBacktraceDepth() const;
 };
 
@@ -494,9 +494,9 @@ class Thread : public std::enable_shared_from_this<Thread>,
 
   // If stop_format is true, this will be the form used when we print stop
   // info. If false, it will be the form we use for thread list and co.
-  void DumpUsingSettingsFormat(Stream &strm, uint32_t frame_idx, 
+  void DumpUsingSettingsFormat(Stream &strm, uint32_t frame_idx,
                                bool stop_format);
- 
+
   bool GetDescription(Stream &s, lldb::DescriptionLevel level,
                       bool print_json_thread, bool print_json_stopinfo);
 
@@ -653,12 +653,16 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @param[in] stop_other_threads
   ///    \b true if we will stop other threads while we single step this one.
   ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @return
   ///     A shared pointer to the newly queued thread plan, or nullptr if the
   ///     plan could not be queued.
   //------------------------------------------------------------------
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepSingleInstruction(
-      bool step_over, bool abort_other_plans, bool stop_other_threads);
+      bool step_over, bool abort_other_plans, bool stop_other_threads,
+      Status &status);
 
   //------------------------------------------------------------------
   /// Queues the plan used to step through an address range, stepping  over
@@ -688,6 +692,9 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @param[in] stop_other_threads
   ///    \b true if we will stop other threads while we single step this one.
   ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @param[in] step_out_avoids_code_without_debug_info
   ///    If eLazyBoolYes, if the step over steps out it will continue to step
   ///    out till it comes to a frame with debug info.
@@ -700,6 +707,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepOverRange(
       bool abort_other_plans, const AddressRange &range,
       const SymbolContext &addr_context, lldb::RunMode stop_other_threads,
+      Status &status,
       LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);
 
   // Helper function that takes a LineEntry to step, insted of an AddressRange.
@@ -708,6 +716,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepOverRange(
       bool abort_other_plans, const LineEntry &line_entry,
       const SymbolContext &addr_context, lldb::RunMode stop_other_threads,
+      Status &status,
       LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);
 
   //------------------------------------------------------------------
@@ -742,6 +751,9 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @param[in] stop_other_threads
   ///    \b true if we will stop other threads while we single step this one.
   ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @param[in] step_in_avoids_code_without_debug_info
   ///    If eLazyBoolYes we will step out if we step into code with no debug
   ///    info.
@@ -759,7 +771,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepInRange(
       bool abort_other_plans, const AddressRange &range,
       const SymbolContext &addr_context, const char *step_in_target,
-      lldb::RunMode stop_other_threads,
+      lldb::RunMode stop_other_threads, Status &status,
       LazyBool step_in_avoids_code_without_debug_info = eLazyBoolCalculate,
       LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);
 
@@ -769,7 +781,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepInRange(
       bool abort_other_plans, const LineEntry &line_entry,
       const SymbolContext &addr_context, const char *step_in_target,
-      lldb::RunMode stop_other_threads,
+      lldb::RunMode stop_other_threads, Status &status,
       LazyBool step_in_avoids_code_without_debug_info = eLazyBoolCalculate,
       LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);
 
@@ -801,6 +813,9 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @param[in] run_vote
   ///    See standard meanings for the stop & run votes in ThreadPlan.h.
   ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @param[in] step_out_avoids_code_without_debug_info
   ///    If eLazyBoolYes, if the step over steps out it will continue to step
   ///    out till it comes to a frame with debug info.
@@ -812,10 +827,8 @@ class Thread : public std::enable_shared_from_this<Thread>,
   //------------------------------------------------------------------
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepOut(
       bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
-      bool stop_other_threads,
-      Vote stop_vote, // = eVoteYes,
-      Vote run_vote,  // = eVoteNoOpinion);
-      uint32_t frame_idx,
+      bool stop_other_threads, Vote stop_vote, Vote run_vote,
+      uint32_t frame_idx, Status &status,
       LazyBool step_out_avoids_code_without_debug_info = eLazyBoolCalculate);
 
   //------------------------------------------------------------------
@@ -846,9 +859,15 @@ class Thread : public std::enable_shared_from_this<Thread>,
   ///    \b true if we will stop other threads while we single step this one.
   ///
   /// @param[in] stop_vote
+  ///
   /// @param[in] run_vote
   ///    See standard meanings for the stop & run votes in ThreadPlan.h.
   ///
+  /// @param[in] frame_idx
+  ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @param[in] continue_to_next_branch
   ///    Normally this will enqueue a plan that will put a breakpoint on the
   ///    return address and continue
@@ -872,16 +891,13 @@ class Thread : public std::enable_shared_from_this<Thread>,
   //------------------------------------------------------------------
   virtual lldb::ThreadPlanSP QueueThreadPlanForStepOutNoShouldStop(
       bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
-      bool stop_other_threads,
-      Vote stop_vote, // = eVoteYes,
-      Vote run_vote,  // = eVoteNoOpinion);
-      uint32_t frame_idx, bool continue_to_next_branch = false);
+      bool stop_other_threads, Vote stop_vote, Vote run_vote,
+      uint32_t frame_idx, Status &status, bool continue_to_next_branch = false);
 
   //------------------------------------------------------------------
   /// Gets the plan used to step through the code that steps from a function
   /// call site at the current PC into the actual function call.
   ///
-  ///
   /// @param[in] return_stack_id
   ///    The stack id that we will return to (by setting backstop breakpoints on
   ///    the return
@@ -895,14 +911,17 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @param[in] stop_other_threads
   ///    \b true if we will stop other threads while we single step this one.
   ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @return
   ///     A shared pointer to the newly queued thread plan, or nullptr if the
   ///     plan could not be queued.
   //------------------------------------------------------------------
   virtual lldb::ThreadPlanSP
   QueueThreadPlanForStepThrough(StackID &return_stack_id,
-                                bool abort_other_plans,
-                                bool stop_other_threads);
+                                bool abort_other_plans, bool stop_other_threads,
+                                Status &status);
 
   //------------------------------------------------------------------
   /// Gets the plan used to continue from the current PC.
@@ -920,22 +939,24 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @param[in] stop_other_threads
   ///    \b true if we will stop other threads while we single step this one.
   ///
+  /// @param[out] status
+  ///     A status with an error if queuing failed.
+  ///
   /// @return
   ///     A shared pointer to the newly queued thread plan, or nullptr if the
   ///     plan could not be queued.
   //------------------------------------------------------------------
   virtual lldb::ThreadPlanSP
   QueueThreadPlanForRunToAddress(bool abort_other_plans, Address &target_addr,
-                                 bool stop_other_threads);
+                                 bool stop_other_threads, Status &status);
 
-  virtual lldb::ThreadPlanSP
-  QueueThreadPlanForStepUntil(bool abort_other_plans,
-                              lldb::addr_t *address_list, size_t num_addresses,
-                              bool stop_others, uint32_t frame_idx);
+  virtual lldb::ThreadPlanSP QueueThreadPlanForStepUntil(
+      bool abort_other_plans, lldb::addr_t *address_list, size_t num_addresses,
+      bool stop_others, uint32_t frame_idx, Status &status);
 
   virtual lldb::ThreadPlanSP
   QueueThreadPlanForStepScripted(bool abort_other_plans, const char *class_name,
-                                 bool stop_other_threads);
+                                 bool stop_other_threads, Status &status);
 
   //------------------------------------------------------------------
   // Thread Plan accessors:
@@ -1021,7 +1042,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
   ///     false otherwise.
   //------------------------------------------------------------------
   bool CompletedPlanOverridesBreakpoint();
-                   
+
   //------------------------------------------------------------------
   /// Queues a generic thread plan.
   ///
@@ -1036,7 +1057,7 @@ class Thread : public std::enable_shared_from_this<Thread>,
   /// @return
   ///     A pointer to the last completed plan.
   //------------------------------------------------------------------
-  void QueueThreadPlan(lldb::ThreadPlanSP &plan_sp, bool abort_other_plans);
+  Status QueueThreadPlan(lldb::ThreadPlanSP &plan_sp, bool abort_other_plans);
 
   //------------------------------------------------------------------
   /// Discards the plans queued on the plan stack of the current thread.  This

lldb/include/lldb/Target/ThreadPlan.h

@@ -596,10 +596,12 @@ class ThreadPlan : public std::enable_shared_from_this<ThreadPlan>,
 
   bool IsUsuallyUnexplainedStopReason(lldb::StopReason);
 
+  Status m_status;
   Thread &m_thread;
   Vote m_stop_vote;
   Vote m_run_vote;
-  bool m_takes_iteration_count = false;
+  bool m_takes_iteration_count;
+  bool m_could_not_resolve_hw_bp;
   int32_t m_iteration_count = 1;
 
 private:
@@ -651,6 +653,8 @@ class ThreadPlanNull : public ThreadPlan {
 
   bool OkayToDiscard() override { return false; }
 
+  const Status &GetStatus() { return m_status; }
+
 protected:
   bool DoPlanExplainsStop(Event *event_ptr) override;
 

lldb/include/lldb/Target/ThreadPlanPython.h

@@ -59,6 +59,7 @@ class ThreadPlanPython : public ThreadPlan {
 private:
   std::string m_class_name;
   StructuredData::ObjectSP m_implementation_sp;
+  bool m_did_push;
 
   DISALLOW_COPY_AND_ASSIGN(ThreadPlanPython);
 };

lldb/include/lldb/Target/ThreadPlanShouldStopHere.h

@@ -97,10 +97,12 @@ class ThreadPlanShouldStopHere {
 
   void ClearShouldStopHereCallbacks() { m_callbacks.Clear(); }
 
-  bool InvokeShouldStopHereCallback(lldb::FrameComparison operation);
+  bool InvokeShouldStopHereCallback(lldb::FrameComparison operation,
+                                    Status &status);
 
   lldb::ThreadPlanSP
-  CheckShouldStopHereAndQueueStepOut(lldb::FrameComparison operation);
+  CheckShouldStopHereAndQueueStepOut(lldb::FrameComparison operation,
+                                     Status &status);
 
   lldb_private::Flags &GetFlags() { return m_flags; }
 
@@ -110,14 +112,16 @@ class ThreadPlanShouldStopHere {
   static bool DefaultShouldStopHereCallback(ThreadPlan *current_plan,
                                             Flags &flags,
                                             lldb::FrameComparison operation,
-                                            void *baton);
+                                            Status &status, void *baton);
 
   static lldb::ThreadPlanSP
   DefaultStepFromHereCallback(ThreadPlan *current_plan, Flags &flags,
-                              lldb::FrameComparison operation, void *baton);
+                              lldb::FrameComparison operation, Status &status,
+                              void *baton);
 
   virtual lldb::ThreadPlanSP
-  QueueStepOutFromHerePlan(Flags &flags, lldb::FrameComparison operation);
+  QueueStepOutFromHerePlan(Flags &flags, lldb::FrameComparison operation,
+                           Status &status);
 
   // Implement this, and call it in the plan's constructor to set the default
   // flags.

lldb/include/lldb/Target/ThreadPlanStepInRange.h

@@ -54,7 +54,7 @@ class ThreadPlanStepInRange : public ThreadPlanStepRange,
   static bool DefaultShouldStopHereCallback(ThreadPlan *current_plan,
                                             Flags &flags,
                                             lldb::FrameComparison operation,
-                                            void *baton);
+                                            Status &status, void *baton);
 
   bool DoWillResume(lldb::StateType resume_state, bool current_plan) override;
 
@@ -76,11 +76,11 @@ class ThreadPlanStepInRange : public ThreadPlanStepRange,
   friend lldb::ThreadPlanSP Thread::QueueThreadPlanForStepOverRange(
       bool abort_other_plans, const AddressRange &range,
       const SymbolContext &addr_context, lldb::RunMode stop_others,
-      LazyBool avoid_code_without_debug_info);
+      Status &status, LazyBool avoid_code_without_debug_info);
   friend lldb::ThreadPlanSP Thread::QueueThreadPlanForStepInRange(
       bool abort_other_plans, const AddressRange &range,
       const SymbolContext &addr_context, const char *step_in_target,
-      lldb::RunMode stop_others,
+      lldb::RunMode stop_others, Status &status,
       LazyBool step_in_avoids_code_without_debug_info,
       LazyBool step_out_avoids_code_without_debug_info);
 

lldb/include/lldb/Target/ThreadPlanStepInstruction.h

@@ -39,7 +39,8 @@ class ThreadPlanStepInstruction : public ThreadPlan {
 
 private:
   friend lldb::ThreadPlanSP Thread::QueueThreadPlanForStepSingleInstruction(
-      bool step_over, bool abort_other_plans, bool stop_other_threads);
+      bool step_over, bool abort_other_plans, bool stop_other_threads,
+      Status &status);
 
   lldb::addr_t m_instruction_addr;
   bool m_stop_other_threads;

lldb/include/lldb/Target/ThreadPlanStepOut.h

@@ -77,7 +77,7 @@ class ThreadPlanStepOut : public ThreadPlan, public ThreadPlanShouldStopHere {
   friend lldb::ThreadPlanSP Thread::QueueThreadPlanForStepOut(
       bool abort_other_plans, SymbolContext *addr_context, bool first_insn,
       bool stop_others, Vote stop_vote, Vote run_vote, uint32_t frame_idx,
-      LazyBool step_out_avoids_code_without_debug_info);
+      Status &status, LazyBool step_out_avoids_code_without_debug_info);
 
   void SetupAvoidNoDebug(LazyBool step_out_avoids_code_without_debug_info);
   // Need an appropriate marker for the current stack so we can tell step out