dlav-sc wrote: @jimingham,
> I found this a bit confusing when reading this patch. There are really two > "conditions" being talked about here. There's the primary "hidden" condition > that tests "did the region we are watching change value" and then there's the > watchpoint condition set with watch modify -c. Sometimes the patch wasn't > clear about this. The first condition you mentioned is generally speaking only necessary for modify-type watchpoints. With hardware watchpoints, lldb-server can only detect read/write access to the watched region but cannot determine the actual value. Therefore, to implement modify-type watchpoint logic, lldb-client needs to perform additional checks to verify that the watched value has actually changed (ensuring we're not writing the same value) after lldb-server reports write access to the watched region. For software watchpoints, the entire logic is implemented on the lldb-client side. Since we cannot trigger on memory access (read or write), software watchpoints can only be of the modify type (gdb also only supports modify-type for software watchpoints). lldb-client checks whether the watched value has changed, similar to hardware modify-type watchpoints, but after each step in this case. The second condition is the one I referenced in my previous comment. It is checked by lldb-client using the standard expression mechanism (similar to when you type expr -- <expression>). Please take a look at `Watchpoint::WatchedValueReportable`. In this function, I check both conditions: first, I check the watch condition (the second one) using `CheckWatchpointCondition()` then I calculate the current watched value (`CalculateWatchedValue()`) and compare it with the old value for software watchpoints and hardware modify-type watchpoints using `IsValueObjectsEqual()` (the first condition). https://github.com/llvm/llvm-project/pull/151195 _______________________________________________ lldb-commits mailing list lldb-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-commits
