[Lldb-commits] [PATCH] D89283: [trace][intel-pt] Implement the basic decoding functionality

[walter erquinigo via Phabricator via lldb-commits]

wallace created this revision.
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This diff finally implements trace decoding!

The current interface is

  $ trace load /path/to/trace/session/file.json
  $ thread trace dump instructions
  
  thread #1: tid = 3842849, total instructions = 22
    [ 0] 0x40052d
    [ 1] 0x40052d  
    ...
    [19] 0x400521
  
  $ # simply enter, which is a repeat command
    [20] 0x40052d
    [21] 0x400529
    ...

This doesn't do any disassembly, which will be done in the next diff.

Changes:

- Renamed ThreadIntelPT to TreaceThread, which is a top-level class. I noticed that this should work for any trace plugin and there's nothing intel-pt specific to it.
- With that ThreadThread change, I was able to move most of the json file parsing logic to the base class TraceSessionFileParser, which makes adding new plug-ins easier.
- Added an IntelPTDecoder class, which is a wrapper for libipt, which is the actual library that performs the decoding.
- Added TraceThreadDecoder class that decodes TraceThreads and memoizes the result to avoid repeating the decoding step.
- Added a DecodedThread class, which represents the output from decoding and that for the time being only stored the list of reconstructed instructions. Later it'll contain the function call hierarchy, which will enable reconstructing backtraces.
- Added basic APIs for accessing the trace in Trace.h:
  - GetInstructionCount, which counts the number of instructions traced for a given thread
  - IsTraceFailed, which returns an Error if decoding a thread failed
  - ForEachInstruction, which iterates on the instructions traced for a given thread, concealing the internal storage of threads, as plug-ins can decide to generate the instructions on the fly or to store them all in a vector, like I do.
- DumpTraceInstructions was updated to print the instructions or show an error message if decoding was impossible.
- Tests included


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D89283

Files:
  lldb/include/lldb/Target/Trace.h
  lldb/include/lldb/Target/TraceSessionFileParser.h
  lldb/include/lldb/Target/TraceThread.h
  lldb/include/lldb/lldb-forward.h
  lldb/source/Plugins/Trace/intel-pt/CMakeLists.txt
  lldb/source/Plugins/Trace/intel-pt/DecodedThread.cpp
  lldb/source/Plugins/Trace/intel-pt/DecodedThread.h
  lldb/source/Plugins/Trace/intel-pt/IntelPTDecoder.cpp
  lldb/source/Plugins/Trace/intel-pt/IntelPTDecoder.h
  lldb/source/Plugins/Trace/intel-pt/ThreadIntelPT.cpp
  lldb/source/Plugins/Trace/intel-pt/ThreadIntelPT.h
  lldb/source/Plugins/Trace/intel-pt/TraceIntelPT.cpp
  lldb/source/Plugins/Trace/intel-pt/TraceIntelPT.h
  lldb/source/Plugins/Trace/intel-pt/TraceIntelPTSessionFileParser.cpp
  lldb/source/Plugins/Trace/intel-pt/TraceIntelPTSessionFileParser.h
  lldb/source/Target/CMakeLists.txt
  lldb/source/Target/Thread.cpp
  lldb/source/Target/Trace.cpp
  lldb/source/Target/TraceSessionFileParser.cpp
  lldb/source/Target/TraceThread.cpp
  lldb/test/API/commands/trace/TestTraceDumpInstructions.py
  lldb/test/API/commands/trace/intelpt-trace/trace_bad_image.json
  lldb/test/API/commands/trace/intelpt-trace/trace_wrong_cpu.json

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