[lldb-dev] Execution contexts in the OptionValue subsystem?

Jim Ingham via lldb-dev lldb-dev at lists.llvm.org
Fri Jul 21 16:50:03 PDT 2017

> On Jul 21, 2017, at 4:41 PM, Sean Callanan via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> There's a function in OptionValueProperties (http://llvm.org/viewvc/llvm-project/lldb/trunk/source/Interpreter/OptionValueProperties.cpp?view=markup line 234):
> const Property *OptionValueProperties::GetPropertyAtIndex(
>     const ExecutionContext *exe_ctx, bool will_modify, uint32_t idx) const {
>   return ProtectedGetPropertyAtIndex(idx);
> }
> Its callers  go to some trouble to collect and pass around the ExecutionContext (e.g., GetSubValue passes it around everywhere, GetPropertyAtrIndexAs* has to keep it everywhere, the Dump mechanism passes around ExecutionContexts, etc.)
> Aside from calling this function with completely ignores the ExecutionContext, I don't see the execution contexts getting used anywhere.  Is this a remnant from old code?

For instance (from Process.cpp):

class ProcessOptionValueProperties : public OptionValueProperties {
  ProcessOptionValueProperties(const ConstString &name)
      : OptionValueProperties(name) {}

  // This constructor is used when creating ProcessOptionValueProperties when it
  // is part of a new lldb_private::Process instance. It will copy all current
  // global property values as needed
  ProcessOptionValueProperties(ProcessProperties *global_properties)
      : OptionValueProperties(*global_properties->GetValueProperties()) {}

  const Property *GetPropertyAtIndex(const ExecutionContext *exe_ctx,
                                     bool will_modify,
                                     uint32_t idx) const override {
    // When getting the value for a key from the process options, we will always
    // try and grab the setting from the current process if there is one. Else
    // we just
    // use the one from this instance.
    if (exe_ctx) {
      Process *process = exe_ctx->GetProcessPtr();
      if (process) {
        ProcessOptionValueProperties *instance_properties =
            static_cast<ProcessOptionValueProperties *>(
        if (this != instance_properties)
          return instance_properties->ProtectedGetPropertyAtIndex(idx);
    return ProtectedGetPropertyAtIndex(idx);

That's what tells you whether to use the global process property, or this process specific one.  Ditto for Thread properties.



> Sean
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