This is part 2, covering the commands source.
Some uses remain where it's tricky to see what the
logic is or they are not used with AppendError.
Reviewed By: teemperor
Differential Revision: https://reviews.llvm.org/D104448
This implements the interactive trace start and stop methods.
This diff ended up being much larger than I anticipated because, by doing it, I found that I had implemented in the beginning many things in a non optimal way. In any case, the code is much better now.
There's a lot of boilerplate code due to the gdb-remote protocol, but the main changes are:
- New tracing packets: jLLDBTraceStop, jLLDBTraceStart, jLLDBTraceGetBinaryData. The gdb-remote packet definitions are quite comprehensive.
- Implementation of the "process trace start|stop" and "thread trace start|stop" commands.
- Implementaiton of an API in Trace.h to interact with live traces.
- Created an IntelPTDecoder for live threads, that use the debugger's stop id as checkpoint for its internal cache.
- Added a functionality to stop the process in case "process tracing" is enabled and a new thread can't traced.
- Added tests
I have some ideas to unify the code paths for post mortem and live threads, but I'll do that in another diff.
Differential Revision: https://reviews.llvm.org/D91679
These warnings are raised when compiling with gcc due to either having too few or too many commas, or in the case of lldb, the possibility of a nullptr.
Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D97586
With the feedback I was getting in different diffs, I realized that splitting the parsing logic into two classes was not easy to deal with. I do see value in doing that, but I'd rather leave that as a refactor after most of the intel-pt logic is in place. Thus, I'm merging the common parser into the intel pt one, having thus only one that is fully aware of Intel PT during parsing and object creation.
Besides, based on the feedback in https://reviews.llvm.org/D88769, I'm creating a ThreadIntelPT class that will be able to orchestrate decoding of its own trace and can handle the stop events correctly.
This leaves the TraceIntelPT class as an initialization class that glues together different components. Right now it can initialize a trace session from a json file, and in the future will be able to initialize a trace session from a live process.
Besides, I'm renaming SettingsParser to SessionParser, which I think is a better name, as the json object represents a trace session of possibly many processes.
With the current set of targets, we have the following
- Trace: main interface for dealing with trace sessions
- TraceIntelPT: plugin Trace for dealing with intel pt sessions
- TraceIntelPTSessionParser: a parser of a json trace session file that can create a corresponding TraceIntelPT instance along with Targets, ProcessTraces (to be created in https://reviews.llvm.org/D88769), and ThreadIntelPT threads.
- ProcessTrace: (to be created in https://reviews.llvm.org/D88769) can handle the correct state of the traces as the user traverses the trace. I don't think there'll be a need an intel-pt specific implementation of this class.
- ThreadIntelPT: a thread implementation that can handle the decoding of its own trace file, along with keeping track of the current position the user is looking at when doing reverse debugging.
Differential Revision: https://reviews.llvm.org/D88841
This is the first in a series of patches that will adds a new processor trace plug-in to LLDB.
The idea for this first patch to to add the plug-in interface with simple commands for the trace files that can "load" and "dump" the trace information. We can test the functionality and ensure people are happy with the way things are done and how things are organized before moving on to adding more functionality.
Processor trace information can be view in a few different ways:
- post mortem where a trace is saved off that can be viewed later in the debugger
- gathered while a process is running and allow the user to step back in time (with no variables, memory or registers) to see how each thread arrived at where it is currently stopped.
This patch attempts to start with the first solution of loading a trace file after the fact. The idea is that we will use a JSON file to load the trace information. JSON allows us to specify information about the trace like:
- plug-in name in LLDB
- path to trace file
- shared library load information so we can re-create a target and symbolicate the information in the trace
- any other info that the trace plug-in will need to be able to successfully parse the trace information
- cpu type
- version info
- ???
A new "trace" command was added at the top level of the LLDB commmands:
- "trace load"
- "trace dump"
I did this because if we load trace information we don't need to have a process and we might end up creating a new target for the trace information that will become active. If anyone has any input on where this would be better suited, please let me know. Walter Erquinigo will end up filling in the Intel PT specific plug-in so that it works and is tested once we can agree that the direction of this patch is the correct one, so please feel free to chime in with ideas on comments!
Reviewed By: clayborg
Differential Revision: https://reviews.llvm.org/D85705
David Spickett