[lldb-dev] Python example does not work with latest LLDBs

Greg Clayton via lldb-dev lldb-dev at lists.llvm.org
Mon Feb 13 11:15:15 PST 2017


Works for me with top of tree:

% PYTHONPATH=/tmp/lldb/build/Debug/LLDB.framework/Resources/Python ; ./foo.py )
Creating a target for './a.out'
SBBreakpoint: id = 1, name = 'main', module = a.out, locations = 1
SBProcess: pid = 62855, state = stopped, threads = 1, executable = a.out
thread #1: tid = 0x558f56, 0x000000010226bf74 a.out`main(argc=1, argv=0x00007fff5d994ec8) at main.cpp:15, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
frame #0: 0x000000010226bf74 a.out`main(argc=1, argv=0x00007fff5d994ec8) at main.cpp:15
SBFunction: id = 0x0000004b, name = main, type = main
a.out[0x100000f60]: pushq  %rbp
a.out[0x100000f61]: movq   %rsp, %rbp
a.out[0x100000f64]: xorl   %eax, %eax
a.out[0x100000f66]: movl   $0x0, -0x4(%rbp)
a.out[0x100000f6d]: movl   %edi, -0x8(%rbp)
a.out[0x100000f70]: movq   %rsi, -0x10(%rbp)
a.out[0x100000f74]: popq   %rbp
a.out[0x100000f75]: retq   

this is on a Mac though. Might be something specific to linux.

Greg

> On Feb 13, 2017, at 10:23 AM, Roman Popov <ripopov at gmail.com> wrote:
> 
> Do you mean you were able to reproduce it? Because it is used to work on trunk month ago, but since then I've switched from ubuntu 14.04 to fresh 16.04 and it no longer works for me. 
> 
> 2017-02-13 21:21 GMT+03:00 Greg Clayton <gclayton at apple.com <mailto:gclayton at apple.com>>:
> I would be probably best to just step through it and see why it is incorrectly returning. We know it is broken. We should also add a test for this so we don't regress again.
> 
> Greg
> 
>> On Feb 13, 2017, at 10:19 AM, Roman Popov <ripopov at gmail.com <mailto:ripopov at gmail.com>> wrote:
>> 
>> Yes Greg, this was my expectation that it should not return until stops on break-point. But I had to downgrade sequentially from 5.0 to 4.0 to 3.9 to make it work as expected.
>> 
>> Can I get some diagnostics? Any log files? 
>> 
>> 2017-02-13 20:11 GMT+03:00 Greg Clayton <gclayton at apple.com <mailto:gclayton at apple.com>>:
>> The example code is:
>> 
>> #!/usr/bin/python
>> 
>> import lldb
>> import os
>> 
>> def disassemble_instructions(insts):
>>     for i in insts:
>>         print i
>> 
>> # Set the path to the executable to debug
>> exe = "./a.out"
>> 
>> # Create a new debugger instance
>> debugger = lldb.SBDebugger.Create()
>> 
>> # When we step or continue, don't return from the function until the process 
>> # stops. Otherwise we would have to handle the process events ourselves which, while doable is
>> #a little tricky.  We do this by setting the async mode to false.
>> debugger.SetAsync (False)
>> 
>> # Create a target from a file and arch
>> print "Creating a target for '%s'" % exe
>> 
>> target = debugger.CreateTargetWithFileAndArch (exe, lldb.LLDB_ARCH_DEFAULT)
>> 
>> if target:
>>     # If the target is valid set a breakpoint at main
>>     main_bp = target.BreakpointCreateByName ("main", target.GetExecutable().GetFilename());
>> 
>>     print main_bp
>> 
>>     # Launch the process. Since we specified synchronous mode, we won't return
>>     # from this function until we hit the breakpoint at main
>>     process = target.LaunchSimple (None, None, os.getcwd())
>>     
>>     # Make sure the launch went ok
>>     if process:
>>         # Print some simple process info
>>         state = process.GetState ()
>>         print process
>>         if state == lldb.eStateStopped:
>>             # Get the first thread
>>             thread = process.GetThreadAtIndex (0)
>>             if thread:
>>                 # Print some simple thread info
>>                 print thread
>>                 # Get the first frame
>>                 frame = thread.GetFrameAtIndex (0)
>>                 if frame:
>>                     # Print some simple frame info
>>                     print frame
>>                     function = frame.GetFunction()
>>                     # See if we have debug info (a function)
>>                     if function:
>>                         # We do have a function, print some info for the function
>>                         print function
>>                         # Now get all instructions for this function and print them
>>                         insts = function.GetInstructions(target)
>>                         disassemble_instructions (insts)
>>                     else:
>>                         # See if we have a symbol in the symbol table for where we stopped
>>                         symbol = frame.GetSymbol();
>>                         if symbol:
>>                             # We do have a symbol, print some info for the symbol
>>                             print symbol
>> 
>> We set the async mode to false, so target.LaunchSimple() should not return until the process is stopped or exited. Note in your example it is returning with "state = launching", so this is what is failing. For some reason synchronous mode is not being obeyed.
>> 
>> Greg
>> 
>>> On Feb 11, 2017, at 10:07 AM, Roman Popov via lldb-dev <lldb-dev at lists.llvm.org <mailto:lldb-dev at lists.llvm.org>> wrote:
>>> 
>>> I'm testing example from https://lldb.llvm.org/python-reference.html <https://lldb.llvm.org/python-reference.html> (USING THE LLDB.PY MODULE IN PYTHON)  on Ubuntu 16.04
>>> 
>>> For some reason it works only with LLDB 3.9, is it because LLDB 4.0/5.0 are not stable yet?
>>> 
>>> #5.0   -- Does not work
>>> deb http://apt.llvm.org/xenial/ <http://apt.llvm.org/xenial/> llvm-toolchain-xenial main
>>> # 3.9  -- Works
>>> deb http://apt.llvm.org/xenial/ <http://apt.llvm.org/xenial/> llvm-toolchain-xenial-3.9 main
>>> # 4.0  -- Does not work
>>> deb http://apt.llvm.org/xenial/ <http://apt.llvm.org/xenial/> llvm-toolchain-xenial-4.0 main
>>> 
>>> >clang-5.0 -g test.cpp
>>> >./python_example.py
>>> Creating a target for './a.out'
>>> SBBreakpoint: id = 1, name = 'main', locations = 1
>>> SBProcess: pid = 0, state = launching, threads = 0, executable = a.out
>>> Thanks,
>>> Roman
>>> _______________________________________________
>>> lldb-dev mailing list
>>> lldb-dev at lists.llvm.org <mailto:lldb-dev at lists.llvm.org>
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev <http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev>
>> 
>> 
> 
> 

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