Make stop-hooks fire when lldb first gains control of a process. (#137410)

stop-hooks are supposed to trigger every time the process stops, but as
initially implemented they would only fire when control was returned to
the user. So for instance when a process was launched the stop hook
would only trigger when the process hit a breakpoint or crashed.

However, it would be really useful to be able to trigger a stop hook
when lldb first gains control over the process. One way to do that would
be to implement general "target lifecycle events" and then send process
created events that users could bind actions to.

OTOH, extending the stop hooks to fire when lldb first gains control
over the process is a pretty natural extension to the notion of a stop
hook. So this patch takes the shorter route to that ability by making
stop-hooks fire when lldb first gains control over the process.

I also added the ability to specify whether to trigger the stop hook "on
gaining control". I'm on the fence about whether to set the default to
be "trigger on gaining control" or "don't trigger on gaining control".
Since I think it's a generally useful feature, I've set the default to
"trigger on gaining control".

1 files changed, 16 insertions, 0 deletions

diff --git a/lldb/source/Commands/CommandObjectTarget.cpp b/lldb/source/Commands/CommandObjectTarget.cpp
index e5421e566cd5..8c877fc97105 100644
--- a/lldb/source/Commands/CommandObjectTarget.cpp
+++ b/lldb/source/Commands/CommandObjectTarget.cpp
@@ -4794,6 +4794,17 @@ public:
         m_one_liner.push_back(std::string(option_arg));
         break;
 
+      case 'I': {
+        bool value, success;
+        value = OptionArgParser::ToBoolean(option_arg, false, &success);
+        if (success)
+          m_at_initial_stop = value;
+        else
+          error = Status::FromErrorStringWithFormat(
+              "invalid boolean value '%s' passed for -F option",
+              option_arg.str().c_str());
+      } break;
+
       default:
         llvm_unreachable("Unimplemented option");
       }
@@ -4820,6 +4831,7 @@ public:
       m_use_one_liner = false;
       m_one_liner.clear();
       m_auto_continue = false;
+      m_at_initial_stop = true;
     }
 
     std::string m_class_name;
@@ -4840,6 +4852,7 @@ public:
     // Instance variables to hold the values for one_liner options.
     bool m_use_one_liner = false;
     std::vector<std::string> m_one_liner;
+    bool m_at_initial_stop;
 
     bool m_auto_continue = false;
   };
@@ -5005,6 +5018,9 @@ protected:
     if (specifier_up)
       new_hook_sp->SetSpecifier(specifier_up.release());
 
+    // Should we run at the initial stop:
+    new_hook_sp->SetRunAtInitialStop(m_options.m_at_initial_stop);
+
     // Next see if any of the thread options have been entered:
 
     if (m_options.m_thread_specified) {