[lldb-dev] Not able to set breakpoints above line #70 in lldb-mi.

[Michael Kuklinski via lldb-dev]

Those are the same results I get - however, when actually attached to the remote target, line 70 sends a Z0 packet, whereas line 72 sends absolutely nothing, regardless of the order.

I am on LLDB revision 279920, and LLVM revision 279925.

Michael

-----Original Message-----
From: Greg Clayton [mailto:gclayton at apple.com] 
Sent: Tuesday, August 30, 2016 10:41 AM
To: Michael Kuklinski <mike.k at pixelcarbide.com>
Cc: lldb-dev at lists.llvm.org
Subject: Re: [lldb-dev] Not able to set breakpoints above line #70 in lldb-mi.

Seems to work for me just fine with your binary:

lldb /Volumes/work/gclayton/Downloads/MipsTest.bin
(lldb) target create "/Volumes/work/gclayton/Downloads/MipsTest.bin"
Current executable set to '/Volumes/work/gclayton/Downloads/MipsTest.bin' (mipsr6el).
(lldb) break set -H -f Main.cpp -l 70
Breakpoint 1: where = MipsTest.bin`main + 520 at Main.cpp:70, address = 0x00013488
(lldb) break set -H -f Main.cpp -l 72
Breakpoint 2: where = MipsTest.bin`main + 544 at Main.cpp:72, address = 0x000134a0
(lldb) b
Current breakpoints:
1: file = 'Main.cpp', line = 70, exact_match = 0, locations = 1
  1.1: where = MipsTest.bin`main + 520 at Main.cpp:70, address = MipsTest.bin[0x00013488], unresolved, hit count = 0 

2: file = 'Main.cpp', line = 72, exact_match = 0, locations = 1
  2.1: where = MipsTest.bin`main + 544 at Main.cpp:72, address = MipsTest.bin[0x000134a0], unresolved, hit count = 0 

You don't need to use lldb-mi to reproduce this. Command line LLDB should give you the same results.

What version of LLDB are you using?

> On Aug 30, 2016, at 2:45 AM, Michael Kuklinski via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> 
> Hello,
>  
> I’m having an issue setting breakpoints using lldb-mi.
>  
> I am trying to run a C++ program (which is itself a brainfsck interpreter), compiled for MIPS32r6 using Clang, linked with lld, and am trying to use lldb-mi as the debugger. I am using lldb-mi as my primary use for it is as an intermediary for a visual debugger, but I get the same behavior when using it myself.
>  
> Whenever I try to set a reasonable breakpoint at or below line #70 in Main.cpp, it works – it is resolved, it sends a Z0 packet to the gdb stub, and it works. However, when I attempt to set any breakpoint above line #70, it comes up as ‘unresolved’ (though the addresses shown in the list seem reasonable) and does not submit anything to the stub as a result.
>  
> When I dumped the line table using both readelf and lldb, they were completely reasonable – almost every line until the end had an entry – there was no cut off at line #70.
>  
> At this point, I’m unsure if I’m doing something wrong, or if lldb-mi is having some difficulty with my MIPS binary. 
>  
> I’m building with the following options:
> 
> clang -std=c++14 -mcompact-branches=always -fasynchronous-unwind-tables -funwind-tables -fexceptions -fcxx-exceptions -mips32r6 -O0 -g -glldb ...
>  
> lld --discard-none -znorelro --eh-frame-hdr ...
>  
> And the resultant binary is here: http://filebin.ca/2tJzo2LLBJWO/MipsTest.bin (if you wish something to analyze).
>  
> I’ve also uploaded the rather poor code for Main.cpp here: 
> https://paste.ee/p/WYs8Y
>  
> I’ve also tested this on a second source file in the ELF (‘Recoder.cpp’) which stops working at a lower line number, but has similar behavior – there’s a hard cut-off where lldb stops working with breakpoints. The line table for that file also seems fine.
>  
> Just for example, when I set a breakpoint at or below 70 (note, I get the same behavior when not specifying -H):
>  
> break set -H -f Main.cpp -l 70
> (gdb)
> =breakpoint-created,bkpt={number="1",type="breakpoint",disp="keep",ena
> bled="y",addr="0x0000000000013488",func="main",file="Main.cpp",fullnam
> e="D:\Proj 
> ects\MipsTest2\MipsTest/Main.cpp",line="70",times="0",original-locatio
> n="Main.cpp:70"}
> (gdb)
> =breakpoint-modified,bkpt={number="1",type="breakpoint",disp="keep",en
> abled="y",addr="0x0000000000013488",func="main",file="Main.cpp",fullna
> me="D:\Pro 
> jects\MipsTest2\MipsTest/Main.cpp",line="70",times="0",original-locati
> on="Main.cpp:70"}
>  
> And this is what I see when I set a breakpoint after 70:
> 
> break set -H -f Main.cpp -l 72
> (gdb)
> =breakpoint-created,bkpt={number="2",type="breakpoint",disp="keep",ena
> bled="y",addr="0x00000000000134a0",func="main",file="Main.cpp",fullnam
> e="D:\Proj 
> ects\MipsTest2\MipsTest/Main.cpp",line="72",times="0",original-locatio
> n="Main.cpp:72"}
>  
> However, the list looks as such:
>  
> break list
> Current breakpoints:
> 1: file = 'Main.cpp', line = 70, exact_match = 0, locations = 1, resolved = 1, hit count = 1
>   1.1: where = MipsTest.bin`main + 520 at Main.cpp:70, address = 
> 0x00013488, resolved, hit count = 1
>  
> 2: file = 'Main.cpp', line = 72, exact_match = 0, locations = 1
>   2.1: where = MipsTest.bin`main + 544 at Main.cpp:72, address = 
> MipsTest.bin[0x000134a0], unresolved, hit count = 0
> 
> Note that the address seems completely reasonable but it remains unresolved, and does not submit anything to the stub.
>  
> Thanks for any help or insight you might be able to provide, Michael
>  
> _______________________________________________
> lldb-dev mailing list
> lldb-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/lldb-dev