[Lldb-commits] [PATCH] D18692: Fix a cornercase in breakpoint reporting

[Pavel Labath via lldb-commits]

labath created this revision.
labath added a reviewer: clayborg.
labath added a subscriber: lldb-commits.

This resolves a similar problem as D16720 (which handled the case when we single-step onto a
breakpoint), but this one deals with involutary stops: when we stop a thread (e.g. because
another thread has hit a breakpont and we are doing a full stop), we can end up stopping it right
before it executes a breakpoint instruction. In this case, the stop reason will be empty, but we
will still step over the breakpoint when do the next resume, thereby missing a breakpoint hit.

I have observed this happening in TestConcurrentEvents, but I have no idea how to reproduce this
behavior more reliably.

http://reviews.llvm.org/D18692

Files:
  source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp

Index: source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
===================================================================
--- source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
+++ source/Plugins/Process/gdb-remote/ProcessGDBRemote.cpp
@@ -2089,6 +2089,23 @@
                             handled = true;
                         }
                     }
+                    else
+                    {
+                        addr_t pc = thread_sp->GetRegisterContext()->GetPC();
+                        lldb::BreakpointSiteSP bp_site_sp =
+                            thread_sp->GetProcess()->GetBreakpointSiteList().FindByAddress(pc);
+
+                        // If the current pc is a breakpoint site then the StopInfo should be set to Breakpoint
+                        // even though the remote stub did not set it as such. This can happen when
+                        // the thread is involuntarily interrupted (e.g. due to stops on other
+                        // threads) just as it is about to execute the breakpoint instruction.
+                        if (bp_site_sp && bp_site_sp->ValidForThisThread(thread_sp.get()))
+                        {
+                            thread_sp->SetStopInfo(
+                                StopInfo::CreateStopReasonWithBreakpointSiteID(*thread_sp, bp_site_sp->GetID()));
+                            handled = true;
+                        }
+                    }
 
                     if (!handled && signo && did_exec == false)
                     {


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