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Zach Devito

2014-Mar-25 20:35 UTC

[LLVMdev] Getting the Debugging JIT-ed Code with GDB example to work

I'm trying to run the example described at:

http://llvm.org/docs/DebuggingJITedCode.html

I followed the sample command line session (below, with versions numbers
for everything), but gdb doesn't stop at the breakpoints as described. Any
idea what is wrong?

Thanks,

Zach


zdevito at derp:~/terra/tests$> ~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/clang -cc1 -O0 -g
> -emit-llvm showdebug.c
> zdevito at derp:~/terra/tests$ gdb --args
> ~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit showdebug.ll
> 5
> GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04
> Copyright (C) 2012 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <
> http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show
copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu".
> For bug reporting instructions, please see:
> <http://bugs.launchpad.net/gdb-linaro/>...
> Reading symbols from
> /home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli...(no
> debugging symbols found)...done.
> (gdb) b showdebug.c:6
> No symbol table is loaded.  Use the "file" command.
> Make breakpoint pending on future shared library load? (y or [n]) y
> Breakpoint 1 (showdebug.c:6) pending.
> (gdb) r
> Starting program:
> /home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit
> showdebug.ll 5
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
> [Inferior 1 (process 8538) exited with code 0170]
> (gdb)-------------- next part --------------
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Kaylor, Andrew

2014-Mar-25 23:14 UTC

head link

[LLVMdev] Getting the Debugging JIT-ed Code with GDB example to work

I haven't tried that in a while.  It's possible that it has been broken.
I thought there was a test for it, but I'm not seeing it right now.

A couple of suggestions to help you troubleshoot the problem:


1.       Enable verbose output in GDB.

2.       Set a breakpoint in MCJIT.cpp where it calls
loadedObject->registerWithDebugger.  Step through that and verify that it
gets as far as the call to __jit_debug_register_code in GDBRegistrar.cpp.

When __jit_debug_register_code is called, you should get a message saying that
GDB has loaded symbols for the dynamic code (or possibly that it couldn't
find symbols).

Let me know what happens when you do that, and I might be able to make a
reasonable suggestion as to what to do next.

-Andy

From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Zach Devito
Sent: Tuesday, March 25, 2014 1:35 PM
To: LLVM Developers Mailing List
Subject: [LLVMdev] Getting the Debugging JIT-ed Code with GDB example to work

I'm trying to run the example described at:

http://llvm.org/docs/DebuggingJITedCode.html

I followed the sample command line session (below, with versions numbers for
everything), but gdb doesn't stop at the breakpoints as described. Any idea
what is wrong?

Thanks,

Zach


zdevito at derp:~/terra/tests$
~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/clang -cc1 -O0 -g -emit-llvm
showdebug.c
zdevito at derp:~/terra/tests$ gdb --args
~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit showdebug.ll 5
GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show
copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.launchpad.net/gdb-linaro/>...
Reading symbols from
/home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli...(no debugging
symbols found)...done.
(gdb) b showdebug.c:6
No symbol table is loaded.  Use the "file" command.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (showdebug.c:6) pending.
(gdb) r
Starting program:
/home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit
showdebug.ll 5
[Thread debugging using libthread_db enabled]
Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
[Inferior 1 (process 8538) exited with code 0170]
(gdb)

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Kaylor, Andrew

2014-Mar-25 23:19 UTC

head link

[LLVMdev] Getting the Debugging JIT-ed Code with GDB example to work

Actually, put aside what I said in my previous reply for a second.

I just noticed in your output below that GDB didn't have symbols for lli. 
That's probably the heart of your problem.  GDB relies on hooking a known
function to get the JITed code registration to work.  Since it didn't find
symbols for lli, it won't find the hook function.

You'll need to use a build of lli with symbols to make this work.

-Andy

From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of Zach Devito
Sent: Tuesday, March 25, 2014 1:35 PM
To: LLVM Developers Mailing List
Subject: [LLVMdev] Getting the Debugging JIT-ed Code with GDB example to work

I'm trying to run the example described at:

http://llvm.org/docs/DebuggingJITedCode.html

I followed the sample command line session (below, with versions numbers for
everything), but gdb doesn't stop at the breakpoints as described. Any idea
what is wrong?

Thanks,

Zach


zdevito at derp:~/terra/tests$
~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/clang -cc1 -O0 -g -emit-llvm
showdebug.c
zdevito at derp:~/terra/tests$ gdb --args
~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit showdebug.ll 5
GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04
Copyright (C) 2012 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show
copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.launchpad.net/gdb-linaro/>...
Reading symbols from
/home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli...(no debugging
symbols found)...done.
(gdb) b showdebug.c:6
No symbol table is loaded.  Use the "file" command.
Make breakpoint pending on future shared library load? (y or [n]) y
Breakpoint 1 (showdebug.c:6) pending.
(gdb) r
Starting program:
/home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit
showdebug.ll 5
[Thread debugging using libthread_db enabled]
Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
[Inferior 1 (process 8538) exited with code 0170]
(gdb)

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Zach Devito

2014-Mar-26 01:44 UTC

head link

[LLVMdev] Getting the Debugging JIT-ed Code with GDB example to work

I tested it with the symbols enabled for lli and it still doesn't work.
Below is the assembly for GDBJITRegistrar::registerObject containing the
inlined body of NotifyDebugger.  It looks like the call to
__jit_debug_register_code was inlined away despite being marked with
LLVM_ATTRIBUTE_NOINLINE. LLVM was compiled with the following GCC:

zdevito at derp:~/terra/tests$ gcc --version> gcc (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3
> Copyright (C) 2011 Free Software Foundation, Inc.
> This is free software; see the source for copying conditions.  There is NO
> warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Maybe the LLVM_ATTRIBUTE_NOINLINE macro is defined wrong, or the compiler
is ignoring it?

Zach


Dump of assembler code for function (anonymous> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer const&):
>    0x0000000000b1eba0 <+0>: push   rbp
>    0x0000000000b1eba1 <+1>: push   r15
>    0x0000000000b1eba3 <+3>: push   r14
>    0x0000000000b1eba5 <+5>: push   r13
>    0x0000000000b1eba7 <+7>: push   r12
>    0x0000000000b1eba9 <+9>: push   rbx
>    0x0000000000b1ebaa <+10>: sub    rsp,0x28
>    0x0000000000b1ebae <+14>: mov    r14,rdi
>    0x0000000000b1ebb1 <+17>: mov    rax,QWORD PTR [rsi+0x8]
>    0x0000000000b1ebb5 <+21>: mov    r13,QWORD PTR [rax+0x8]
>    0x0000000000b1ebb9 <+25>: mov    QWORD PTR [rsp+0x8],r13
>    0x0000000000b1ebbe <+30>: test   r13,r13
>    0x0000000000b1ebc1 <+33>: je     0xb1edcf <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+559>
>    0x0000000000b1ebc7 <+39>: mov    rax,QWORD PTR [rax+0x10]
>    0x0000000000b1ebcb <+43>: sub    rax,r13
>    0x0000000000b1ebce <+46>: mov    QWORD PTR [rsp],rax
>    0x0000000000b1ebd2 <+50>: mov    r15,QWORD PTR [r14+0x8]
>    0x0000000000b1ebd6 <+54>: mov    ebp,DWORD PTR [r14+0x18]
>    0x0000000000b1ebda <+58>: add    r14,0x8
>    0x0000000000b1ebde <+62>: test   rbp,rbp
>    0x0000000000b1ebe1 <+65>: je     0xb1ec3f <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+159>
>    0x0000000000b1ebe3 <+67>: mov    rax,r13
>    0x0000000000b1ebe6 <+70>: or     rax,0x4
>    0x0000000000b1ebea <+74>: cmp    rax,0xfffffffffffffffc
>    0x0000000000b1ebee <+78>: je     0xb1ee1e <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+638>
>    0x0000000000b1ebf4 <+84>: mov    ecx,r13d
>    0x0000000000b1ebf7 <+87>: shr    ecx,0x9
>    0x0000000000b1ebfa <+90>: mov    eax,r13d
>    0x0000000000b1ebfd <+93>: shr    eax,0x4
>    0x0000000000b1ec00 <+96>: xor    eax,ecx
>    0x0000000000b1ec02 <+98>: lea    ecx,[rbp-0x1]
>    0x0000000000b1ec05 <+101>: and    eax,ecx
>    0x0000000000b1ec07 <+103>: lea    rdx,[rax+rax*2]
>    0x0000000000b1ec0b <+107>: mov    rsi,QWORD PTR [r15+rdx*8]
>    0x0000000000b1ec0f <+111>: cmp    r13,rsi
>    0x0000000000b1ec12 <+114>: je     0xb1ec4a <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+170>
>    0x0000000000b1ec14 <+116>: mov    edx,0x1
>    0x0000000000b1ec19 <+121>: nop    DWORD PTR [rax+0x0]
>    0x0000000000b1ec20 <+128>: cmp    rsi,0xfffffffffffffffc
>    0x0000000000b1ec24 <+132>: je     0xb1ec3f <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+159>
>    0x0000000000b1ec26 <+134>: add    eax,edx
>    0x0000000000b1ec28 <+136>: and    eax,ecx
>    0x0000000000b1ec2a <+138>: lea    rdi,[rax+rax*2]
>    0x0000000000b1ec2e <+142>: mov    rsi,QWORD PTR [r15+rdi*8]
>    0x0000000000b1ec32 <+146>: inc    edx
>    0x0000000000b1ec34 <+148>: cmp    r13,rsi
>    0x0000000000b1ec37 <+151>: jne    0xb1ec20 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+128>
>    0x0000000000b1ec39 <+153>: lea    rax,[r15+rdi*8]
>    0x0000000000b1ec3d <+157>: jmp    0xb1ec4e <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+174>
>    0x0000000000b1ec3f <+159>: lea    rax,[rbp+rbp*2+0x0]
>    0x0000000000b1ec44 <+164>: lea    rax,[r15+rax*8]
>    0x0000000000b1ec48 <+168>: jmp    0xb1ec4e <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+174>
>    0x0000000000b1ec4a <+170>: lea    rax,[r15+rdx*8]
>    0x0000000000b1ec4e <+174>: lea    rcx,[rbp+rbp*2+0x0]
>    0x0000000000b1ec53 <+179>: lea    rcx,[r15+rcx*8]
>    0x0000000000b1ec57 <+183>: cmp    rax,rcx
>    0x0000000000b1ec5a <+186>: jne    0xb1edee <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+590>
>    0x0000000000b1ec60 <+192>: mov    edi,0x20
>    0x0000000000b1ec65 <+197>: call   0x4e8120 <_Znwm at plt>
>    0x0000000000b1ec6a <+202>: mov    r12,rax
>    0x0000000000b1ec6d <+205>: mov    QWORD PTR [r12+0x18],0x0
>    0x0000000000b1ec76 <+214>: mov    QWORD PTR [r12+0x10],0x0
>    0x0000000000b1ec7f <+223>: mov    QWORD PTR [r12+0x8],0x0
>    0x0000000000b1ec88 <+232>: mov    QWORD PTR [r12],0x0
>    0x0000000000b1ec90 <+240>: test   r12,r12
>    0x0000000000b1ec93 <+243>: je     0xb1ee0d <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+621>
>    0x0000000000b1ec99 <+249>: mov    QWORD PTR [r12+0x10],r13
>    0x0000000000b1ec9e <+254>: mov    rax,QWORD PTR [rsp]
>    0x0000000000b1eca2 <+258>: mov    QWORD PTR [r12+0x18],rax
>    0x0000000000b1eca7 <+263>: xor    eax,eax
>    0x0000000000b1eca9 <+265>: test   ebp,ebp
>    0x0000000000b1ecab <+267>: je     0xb1ed2b <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+395>
>    0x0000000000b1ecad <+269>: mov    rax,r13
>    0x0000000000b1ecb0 <+272>: or     rax,0x4
>    0x0000000000b1ecb4 <+276>: cmp    rax,0xfffffffffffffffc
>    0x0000000000b1ecb8 <+280>: je     0xb1ee1e <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+638>
>    0x0000000000b1ecbe <+286>: mov    eax,r13d
>    0x0000000000b1ecc1 <+289>: shr    eax,0x9
>    0x0000000000b1ecc4 <+292>: mov    ecx,r13d
>    0x0000000000b1ecc7 <+295>: shr    ecx,0x4
>    0x0000000000b1ecca <+298>: xor    ecx,eax
>    0x0000000000b1eccc <+300>: dec    ebp
>    0x0000000000b1ecce <+302>: and    ecx,ebp
>    0x0000000000b1ecd0 <+304>: lea    rdx,[rcx+rcx*2]
>    0x0000000000b1ecd4 <+308>: lea    rax,[r15+rdx*8]
>    0x0000000000b1ecd8 <+312>: mov    rdi,QWORD PTR [r15+rdx*8]
>    0x0000000000b1ecdc <+316>: cmp    r13,rdi
>    0x0000000000b1ecdf <+319>: je     0xb1ed65 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+453>
>    0x0000000000b1ece5 <+325>: xor    edx,edx
>    0x0000000000b1ece7 <+327>: mov    esi,0x1
>    0x0000000000b1ecec <+332>: nop    DWORD PTR [rax+0x0]
>    0x0000000000b1ecf0 <+336>: cmp    rdi,0xfffffffffffffffc
>    0x0000000000b1ecf4 <+340>: je     0xb1ed24 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+388>
>    0x0000000000b1ecf6 <+342>: add    ecx,esi
>    0x0000000000b1ecf8 <+344>: and    ecx,ebp
>    0x0000000000b1ecfa <+346>: test   rdx,rdx
>    0x0000000000b1ecfd <+349>: sete   r8b
>    0x0000000000b1ed01 <+353>: cmp    rdi,0xfffffffffffffff8
>    0x0000000000b1ed05 <+357>: sete   bl
>    0x0000000000b1ed08 <+360>: test   r8b,bl
>    0x0000000000b1ed0b <+363>: cmovne rdx,rax
>    0x0000000000b1ed0f <+367>: lea    rdi,[rcx+rcx*2]
>    0x0000000000b1ed13 <+371>: lea    rax,[r15+rdi*8]
>    0x0000000000b1ed17 <+375>: mov    rdi,QWORD PTR [r15+rdi*8]
>    0x0000000000b1ed1b <+379>: inc    esi
>    0x0000000000b1ed1d <+381>: cmp    r13,rdi
>    0x0000000000b1ed20 <+384>: jne    0xb1ecf0 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+336>
>    0x0000000000b1ed22 <+386>: jmp    0xb1ed65 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+453>
>    0x0000000000b1ed24 <+388>: test   rdx,rdx
>    0x0000000000b1ed27 <+391>: cmovne rax,rdx
>    0x0000000000b1ed2b <+395>: xorps  xmm0,xmm0
>    0x0000000000b1ed2e <+398>: movaps XMMWORD PTR [rsp+0x10],xmm0
>    0x0000000000b1ed33 <+403>: lea    rsi,[rsp+0x8]
>    0x0000000000b1ed38 <+408>: mov    rdi,r14
>    0x0000000000b1ed3b <+411>: mov    rdx,rax
>    0x0000000000b1ed3e <+414>: call   0xb1f150
> <llvm::DenseMapBase<llvm::DenseMap<char const*,
std::pair<unsigned long,
> jit_code_entry*>, llvm::DenseMapInfo<char const*> >, char
const*,
> std::pair<unsigned long, jit_code_entry*>, llvm::DenseMapInfo<char
const*>
> >::InsertIntoBucketImpl(char const* const&, std::pair<char
const*,
> std::pair<unsigned long, jit_code_entry*> >*)>
>    0x0000000000b1ed43 <+419>: mov    rcx,QWORD PTR [rsp+0x8]
>    0x0000000000b1ed48 <+424>: mov    QWORD PTR [rax],rcx
>    0x0000000000b1ed4b <+427>: mov    rcx,rax
>    0x0000000000b1ed4e <+430>: add    rcx,0x8
>    0x0000000000b1ed52 <+434>: je     0xb1ed65 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+453>
>    0x0000000000b1ed54 <+436>: mov    rdx,QWORD PTR [rsp+0x10]
>    0x0000000000b1ed59 <+441>: mov    rsi,QWORD PTR [rsp+0x18]
>    0x0000000000b1ed5e <+446>: mov    QWORD PTR [rcx+0x8],rsi
>    0x0000000000b1ed62 <+450>: mov    QWORD PTR [rcx],rdx
>    0x0000000000b1ed65 <+453>: mov    rcx,QWORD PTR [rsp]
>    0x0000000000b1ed69 <+457>: mov    QWORD PTR [rax+0x8],rcx
>    0x0000000000b1ed6d <+461>: mov    QWORD PTR [rax+0x10],r12
> => 0x0000000000b1ed71 <+465>: lea    rdi,[rip+0x707310]        #
> 0x1226088 <_ZN12_GLOBAL__N_112JITDebugLockE>
>    0x0000000000b1ed78 <+472>: call   0xca3810
> <llvm::sys::MutexImpl::acquire()>
>    0x0000000000b1ed7d <+477>: mov    rax,QWORD PTR [rip+0x6fdeb4]
>  # 0x121cc38
>    0x0000000000b1ed84 <+484>: mov    DWORD PTR [rax+0x4],0x1
>    0x0000000000b1ed8b <+491>: mov    QWORD PTR [r12+0x8],0x0
>    0x0000000000b1ed94 <+500>: mov    rax,QWORD PTR [rax+0x10]
>    0x0000000000b1ed98 <+504>: mov    QWORD PTR [r12],rax
>    0x0000000000b1ed9c <+508>: test   rax,rax
>    0x0000000000b1ed9f <+511>: je     0xb1eda5 <(anonymous
> namespace)::GDBJITRegistrar::registerObject(llvm::ObjectBuffer
const&)+517>
>    0x0000000000b1eda1 <+513>: mov    QWORD PTR [rax+0x8],r12
>    0x0000000000b1eda5 <+517>: mov    rax,QWORD PTR [rip+0x6fde8c]
>  # 0x121cc38
>    0x0000000000b1edac <+524>: mov    QWORD PTR [rax+0x10],r12
>    0x0000000000b1edb0 <+528>: mov    QWORD PTR [rax+0x8],r12
>    0x0000000000b1edb4 <+532>: lea    rdi,[rip+0x7072cd]        #
> 0x1226088 <_ZN12_GLOBAL__N_112JITDebugLockE>
>    0x0000000000b1edbb <+539>: call   0xca3850
> <llvm::sys::MutexImpl::release()>
>    0x0000000000b1edc0 <+544>: add    rsp,0x28
>    0x0000000000b1edc4 <+548>: pop    rbx
>    0x0000000000b1edc5 <+549>: pop    r12
>    0x0000000000b1edc7 <+551>: pop    r13
>    0x0000000000b1edc9 <+553>: pop    r14
>    0x0000000000b1edcb <+555>: pop    r15
>    0x0000000000b1edcd <+557>: pop    rbp
>    0x0000000000b1edce <+558>: ret
>    0x0000000000b1edcf <+559>: lea    rdi,[rip+0x35f9a9]        #
0xe7e77f
>    0x0000000000b1edd6 <+566>: lea    rsi,[rip+0x35f6fc]        #
0xe7e4d9
>    0x0000000000b1eddd <+573>: lea    rcx,[rip+0x35f9da]        #
0xe7e7be
>    0x0000000000b1ede4 <+580>: mov    edx,0x84
>    0x0000000000b1ede9 <+585>: call   0x4e7ef0 <__assert_fail at
plt>
>    0x0000000000b1edee <+590>: lea    rdi,[rip+0x35fa29]        #
0xe7e81e
>    0x0000000000b1edf5 <+597>: lea    rsi,[rip+0x35f6dd]        #
0xe7e4d9
>    0x0000000000b1edfc <+604>: lea    rcx,[rip+0x35f9bb]        #
0xe7e7be
>    0x0000000000b1ee03 <+611>: mov    edx,0x86
>    0x0000000000b1ee08 <+616>: call   0x4e7ef0 <__assert_fail at
plt>
>    0x0000000000b1ee0d <+621>: lea    rdi,[rip+0x35fa73]        #
0xe7e887
>    0x0000000000b1ee14 <+628>: mov    esi,0x1
>    0x0000000000b1ee19 <+633>: call   0xc9dbe0
> <llvm::report_fatal_error(char const*, bool)>
>    0x0000000000b1ee1e <+638>: lea    rdi,[rip+0x1a8998]        #
0xcc77bd
>    0x0000000000b1ee25 <+645>: lea    rsi,[rip+0x1a8045]        #
0xcc6e71
>    0x0000000000b1ee2c <+652>: lea    rcx,[rip+0x35f722]        #
0xe7e555
>    0x0000000000b1ee33 <+659>: mov    edx,0x1e0
>    0x0000000000b1ee38 <+664>: call   0x4e7ef0 <__assert_fail at
plt>


On Tue, Mar 25, 2014 at 4:19 PM, Kaylor, Andrew <andrew.kaylor at
intel.com>wrote:
>  Actually, put aside what I said in my previous reply for a second.
>
>
>
> I just noticed in your output below that GDB didn't have symbols for
lli.
> That's probably the heart of your problem.  GDB relies on hooking a
known
> function to get the JITed code registration to work.  Since it didn't
find
> symbols for lli, it won't find the hook function.
>
>
>
> You'll need to use a build of lli with symbols to make this work.
>
>
>
> -Andy
>
>
>
> *From:* llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu] *On
> Behalf Of *Zach Devito
> *Sent:* Tuesday, March 25, 2014 1:35 PM
> *To:* LLVM Developers Mailing List
> *Subject:* [LLVMdev] Getting the Debugging JIT-ed Code with GDB example
> to work
>
>
>
> I'm trying to run the example described at:
>
>
>
> http://llvm.org/docs/DebuggingJITedCode.html
>
>
>
> I followed the sample command line session (below, with versions numbers
> for everything), but gdb doesn't stop at the breakpoints as described.
Any
> idea what is wrong?
>
>
>
> Thanks,
>
>
>
> Zach
>
>
>
>
>
> zdevito at derp:~/terra/tests$
> ~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/clang -cc1 -O0 -g
> -emit-llvm showdebug.c
> zdevito at derp:~/terra/tests$ gdb --args
> ~/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit showdebug.ll
> 5
> GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04
> Copyright (C) 2012 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <
> http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show
copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu".
> For bug reporting instructions, please see:
> <http://bugs.launchpad.net/gdb-linaro/>...
> Reading symbols from
> /home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli...(no
> debugging symbols found)...done.
> (gdb) b showdebug.c:6
> No symbol table is loaded.  Use the "file" command.
> Make breakpoint pending on future shared library load? (y or [n]) y
> Breakpoint 1 (showdebug.c:6) pending.
> (gdb) r
> Starting program:
> /home/zdevito/clang+llvm-3.4-x86_64-unknown-ubuntu12.04/bin/lli -use-mcjit
> showdebug.ll 5
> [Thread debugging using libthread_db enabled]
> Using host libthread_db library
"/lib/x86_64-linux-gnu/libthread_db.so.1".
> [Inferior 1 (process 8538) exited with code 0170]
> (gdb)
>
>
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