[Lldb-commits] [lldb] [lldb] Add 'modify' type watchpoints, make it default (PR #66308)

[Jason Molenda via lldb-commits]

jasonmolenda wrote:

> > Just to be clear, I need to find a solution for SBTarget::CreateWatchpoint before this PR is ready to land. I'm inclined towards adding a third bool parameter 'modify', but I'm not sure that's the best choice.
> 
> Anytime we keep adding more options to an API call we have two options:

Yeah exactly, I wasn't restating the options as clearly in that last comment, that's exactly what I meant.  I can't think of other options we would want to build in to a Watchpoint at creation time - but the argument for SBWatchpointOptions is that ten-years-in-the-future-Jason may want another flag.

Probably the best thing is to look at the SBTarget BreakpointCreate* methods; there are a dozen different methods for the different types of breakpoints you might want to create (address breakpoint, file & line breakpoint, symbol name breakpoint etc). An interesting aside is that none of the SB API methods take a flag for whether breakpoint should be set using a software or hardware breakpoint.  Jonas added that feature to debugserver a few years ago for x86_64 and aarch64, and I think he added the `target.require-hardware-breakpoint` setting then.  Otherwise the only way to set a hardware breakpoint is through the commandline `breakpoint set` command.

For a watchpoint, we only have SBTarget::WatchAddress, which takes and address and size.  If we were trying to follow the breakpoint API naming style, we would add SBTarget::WatchpointCreateByAddress, SBTarget::WatchpointCreateByVariable, and SBTarget::WatchpointCreateByExpression methods.  All of them would take the same read/write/modify flags, which might be the strongest argument for an options class even if it seems a little bit much for a few bools.

https://github.com/llvm/llvm-project/pull/66308