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

Tue Aug 30 12:52:21 PDT 2016

This is my output from that:

https://paste.ee/p/iGKZr

Though I am admittedly unsure what I am looking for.

Michael

-----Original Message-----
From: jingham at apple.com [mailto:jingham at apple.com] 
Sent: Tuesday, August 30, 2016 2:40 PM
To: Michael Kuklinski <mike.k at pixelcarbide.com>
Cc: Greg Clayton <gclayton at apple.com>; lldb-dev at lists.llvm.org
Subject: Re: [lldb-dev] Not able to set breakpoints above line #70 in lldb-mi.

The addresses for the two breakpoints are reported differently in your "break list" output.  The successful one is given as:

0x00013488

but the one that isn't sent is still given as:

MipsTest.bin[0x000134a0]

That's a file offset address, not a load address.  It sounds like we don't know where the section that contains the second address got loaded in memory.  In your binary they are all in the same text section, so I'm not sure how this would happen.  

Once you are running, try:

(lldb) image dump sections MipsTest.bin

and see if there's anything funny going on there.

Jim

> On Aug 30, 2016, at 11:11 AM, Michael Kuklinski via lldb-dev <lldb-dev at lists.llvm.org> wrote:
> 
> 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",en
>> a 
>> bled="y",addr="0x0000000000013488",func="main",file="Main.cpp",fullna
>> m
>> e="D:\Proj
>> ects\MipsTest2\MipsTest/Main.cpp",line="70",times="0",original-locati
>> o
>> n="Main.cpp:70"}
>> (gdb)
>> =breakpoint-modified,bkpt={number="1",type="breakpoint",disp="keep",e
>> n 
>> abled="y",addr="0x0000000000013488",func="main",file="Main.cpp",fulln
>> a
>> me="D:\Pro
>> jects\MipsTest2\MipsTest/Main.cpp",line="70",times="0",original-locat
>> i
>> 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",en
>> a 
>> bled="y",addr="0x00000000000134a0",func="main",file="Main.cpp",fullna
>> m
>> e="D:\Proj
>> ects\MipsTest2\MipsTest/Main.cpp",line="72",times="0",original-locati
>> o
>> 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
> 
> 
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