[all-commits] [llvm/llvm-project] a57b62: [lldb] Fix thread step until to not set breakpoint...

Venkata Ramanaiah Nalamothu via All-commits all-commits at lists.llvm.org
Fri Jun 24 11:31:18 PDT 2022

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: a57b62deef37c7f2ec31bca3bf9173a6206bfb9b
  Author: Venkata Ramanaiah Nalamothu <VenkataRamanaiah.Nalamothu at amd.com>
  Date:   2022-06-25 (Sat, 25 Jun 2022)

  Changed paths:
    M lldb/source/Commands/CommandObjectThread.cpp
    M lldb/test/API/functionalities/thread/step_until/TestStepUntil.py

  Log Message:
  [lldb] Fix thread step until to not set breakpoint(s) on incorrect line numbers

The requirements for "thread until <line number>" are:

a) If any code contributed by <line number> or the nearest subsequent of <line number> is executed before leaving the function, stop
b) If you end up leaving the function w/o triggering (a), then stop

In case of (a), since the <line number> may have multiple entries in the line table and the compiler might have scheduled/moved the relevant code across, and the lldb does not know the control flow, set breakpoints on all the line table entries of best match of <line number> i.e. exact or the nearest subsequent line.

Along with the above, currently, CommandObjectThreadUntil is also setting the breakpoints on all the subsequent line numbers after the best match and this latter part is wrong.

This issue is discussed at http://lists.llvm.org/pipermail/lldb-dev/2018-August/013979.html.

In fact, currently `TestStepUntil.py` is not actually testing step until scenarios and `test_missing_one` test fails without this patch if tests are made to run. Fixed the test as well.

Reviewed By: jingham

Differential Revision: https://reviews.llvm.org/D50304

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