llvm dev - Aug 2011 - [LLVMdev] Trouble using the MCJIT: "Target does not support MC emission" error

Following along from lli code, if you add a call to
InitializeNativeTargetAsmPrinter() during setup, it gets a bit farther and
crashes rather than issuing that error.  (Rebuilding with debugging symbols now
to dig into it further…)

-matt

Program received signal EXC_BAD_ACCESS, Could not access memory.
Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000000
0x000000010000349e in llvm::MCJITMemoryManager::startFunctionBody ()
(gdb) where
#0  0x000000010000349e in llvm::MCJITMemoryManager::startFunctionBody ()
#1  0x0000000100003ea0 in llvm::RuntimeDyldImpl::extractFunction ()
#2  0x00000001000059a5 in llvm::RuntimeDyldMachO::loadSegment64 ()
#3  0x000000010000493d in llvm::RuntimeDyldMachO::loadObject ()
#4  0x0000000100003cf9 in llvm::RuntimeDyld::loadObject ()
#5  0x00000001000032e5 in llvm::MCJIT::MCJIT ()
#6  0x00000001000021c2 in llvm::MCJIT::createJIT ()
#7  0x0000000100023274 in llvm::EngineBuilder::create ()
#8  0x0000000100001417 in lRunTest (fn=0x7fff5fbffb3a "a.bc") at
bug.cpp:44
#9  0x000000010000175a in main (argc=2, argv=0x7fff5fbff9c8) at bug.cpp:61
(gdb) quit


On Aug 26, 2011, at 7:58 AM, Ralf Karrenberg wrote:
> Ah, now that makes sense. Guess I was a little over-eager with my
> bugreport. Thanks! :)
> 
> However, I am now running into the same Problem as Matt ("Target does
> not support MC emission!").
> 
> Best,
> Ralf
> 
> Am 25.08.2011 19:32, schrieb Bruno Cardoso Lopes:
>> Hi Ralf,
>> 
>> FYI, old JIT doesn't support AVX at all, no encoding info, etc...
The
>> only way to use AVX+JIT is using MCJIT, which contains the correct
>> encoding, but unfortunately the framework isn't good yet as the old
>> one is.
>> 
>> On Thu, Aug 25, 2011 at 10:12 AM, Ralf Karrenberg<Chareos at
gmx.de>  wrote:
>>> Hi Matt,
>>> 
>>> I am unsure about MCJIT, but I guess the problem is the same.
>>> Just like when invoking llc, you need to pass the information to
use AVX
>>> (llc -mattr=+avx).
>>> I guess the corresponding code should look like this:
>>> 
>>>     llvm::EngineBuilder engineBuilder(module);
>>>     engineBuilder.setErrorStr(&eeError);
>>>     engineBuilder.setEngineKind(llvm::EngineKind::JIT);
>>>     engineBuilder.setUseMCJIT(true);
>>>     engineBuilder.setMCPU("corei7-avx");
>>>     std::vector<std::string>  attrs;
>>>     attrs.push_back("avx");
>>>     engineBuilder.setMAttrs(attrs);
>>>     llvm::ExecutionEngine *ee = engineBuilder.create();
>>> 
>>> Note that I have just today filed a bug report also related to
jitted
>>> AVX: http://llvm.org/bugs/show_bug.cgi?id=10742
>>> Thus, it might very well be the case that I am also mistaken and
need to
>>> do something different.
>>> 
>>> Best,
>>> Ralf
>>> 
>>> Am 25.08.2011 13:16, schrieb Matt Pharr:
>>>> I'm trying to wire up some code to use the MC-based JIT; my
understanding is that it should be able to JIT AVX code (and that the regular
JIT cannot).  However, I'm getting the error "Target does not support
MC emission!" when I call EngineBuilder::create().  I assume that I'm
just not doing something necessary for initialization, but I'm not sure what
it would be--I am calling all of:
>>>> 
>>>>      llvm::InitializeNativeTarget();
>>>>      llvm::InitializeAllTargetMCs();
>>>>      LLVMLinkInMCJIT();
>>>>      LLVMLinkInJIT();
>>>> 
>>>> and the module I'm trying to load does have a reasonable
target:
>>>> 
>>>> target triple = "x86_64-apple-darwin11.0.0"
>>>> 
>>>> I've attached a short test case that has the sequence of
calls that I'm making and one of the bitcode files I'm trying to use. 
I'd be happy for any guidance or suggestions.
>>>> 
>>>> Thanks,
>>>> -matt
>>>> 
>>>> 
>>>> 
>>>> 
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>> 
>> 
>> 
>>

Hi Matt, hi Bruno,

I am still struggling to use AVX via MCJIT on TOT... did you succeed yet?

I seem to be unable to even get lli to run some code with the
"use-mcjit" flag.
I attached a test case that works fine for "lli y.bc" but exits with
an
error for "lli -use-mcjit y.bc":
"LLVM ERROR: Unknown object format"

If I call InitializeAllTargetMCs() before creating the execution engine,
I end up with linker errors for PPC, MIPS, and MSP430 like this one:

llvm-svn-install/lib/libLLVMPowerPCDesc.a(PPCMCTargetDesc.o): In
function `PPCInstPrinter':
llvm-svn/lib/Target/PowerPC/MCTargetDesc/../InstPrinter/PPCInstPrinter.h:28:
undefined reference to `vtable for llvm::PPCInstPrinter'

However, I noticed that lli does neither call InitializeAllTargetMCs(),
nor does it call LLVMLinkInMCJIT() and LLVMLinkInJIT(). Adapting my code
to lli yields the same problem as for lli (unknown object format).

Any more ideas?

Best,
Ralf

Matt Pharr wrote:
> Following along from lli code, if you add a call to
InitializeNativeTargetAsmPrinter() during setup, it gets a bit farther and
crashes rather than issuing that error.  (Rebuilding with debugging symbols now
to dig into it further…)
> 
> -matt
> 
> Program received signal EXC_BAD_ACCESS, Could not access memory.
> Reason: KERN_INVALID_ADDRESS at address: 0x0000000000000000
> 0x000000010000349e in llvm::MCJITMemoryManager::startFunctionBody ()
> (gdb) where
> #0  0x000000010000349e in llvm::MCJITMemoryManager::startFunctionBody ()
> #1  0x0000000100003ea0 in llvm::RuntimeDyldImpl::extractFunction ()
> #2  0x00000001000059a5 in llvm::RuntimeDyldMachO::loadSegment64 ()
> #3  0x000000010000493d in llvm::RuntimeDyldMachO::loadObject ()
> #4  0x0000000100003cf9 in llvm::RuntimeDyld::loadObject ()
> #5  0x00000001000032e5 in llvm::MCJIT::MCJIT ()
> #6  0x00000001000021c2 in llvm::MCJIT::createJIT ()
> #7  0x0000000100023274 in llvm::EngineBuilder::create ()
> #8  0x0000000100001417 in lRunTest (fn=0x7fff5fbffb3a "a.bc") at
bug.cpp:44
> #9  0x000000010000175a in main (argc=2, argv=0x7fff5fbff9c8) at bug.cpp:61
> (gdb) quit
> 
> 
> On Aug 26, 2011, at 7:58 AM, Ralf Karrenberg wrote:
> 
>> Ah, now that makes sense. Guess I was a little over-eager with my
>> bugreport. Thanks! :)
>>
>> However, I am now running into the same Problem as Matt ("Target
does
>> not support MC emission!").
>>
>> Best,
>> Ralf
>>
>> Am 25.08.2011 19:32, schrieb Bruno Cardoso Lopes:
>>> Hi Ralf,
>>>
>>> FYI, old JIT doesn't support AVX at all, no encoding info,
etc... The
>>> only way to use AVX+JIT is using MCJIT, which contains the correct
>>> encoding, but unfortunately the framework isn't good yet as the
old
>>> one is.
>>>
>>> On Thu, Aug 25, 2011 at 10:12 AM, Ralf Karrenberg<Chareos at
gmx.de>  wrote:
>>>> Hi Matt,
>>>>
>>>> I am unsure about MCJIT, but I guess the problem is the same.
>>>> Just like when invoking llc, you need to pass the information
to use AVX
>>>> (llc -mattr=+avx).
>>>> I guess the corresponding code should look like this:
>>>>
>>>>     llvm::EngineBuilder engineBuilder(module);
>>>>     engineBuilder.setErrorStr(&eeError);
>>>>     engineBuilder.setEngineKind(llvm::EngineKind::JIT);
>>>>     engineBuilder.setUseMCJIT(true);
>>>>     engineBuilder.setMCPU("corei7-avx");
>>>>     std::vector<std::string>  attrs;
>>>>     attrs.push_back("avx");
>>>>     engineBuilder.setMAttrs(attrs);
>>>>     llvm::ExecutionEngine *ee = engineBuilder.create();
>>>>
>>>> Note that I have just today filed a bug report also related to
jitted
>>>> AVX: http://llvm.org/bugs/show_bug.cgi?id=10742
>>>> Thus, it might very well be the case that I am also mistaken
and need to
>>>> do something different.
>>>>
>>>> Best,
>>>> Ralf
>>>>
>>>> Am 25.08.2011 13:16, schrieb Matt Pharr:
>>>>> I'm trying to wire up some code to use the MC-based
JIT; my understanding is that it should be able to JIT AVX code (and that the
regular JIT cannot).  However, I'm getting the error "Target does not
support MC emission!" when I call EngineBuilder::create().  I assume that
I'm just not doing something necessary for initialization, but I'm not
sure what it would be--I am calling all of:
>>>>>
>>>>>      llvm::InitializeNativeTarget();
>>>>>      llvm::InitializeAllTargetMCs();
>>>>>      LLVMLinkInMCJIT();
>>>>>      LLVMLinkInJIT();
>>>>>
>>>>> and the module I'm trying to load does have a
reasonable target:
>>>>>
>>>>> target triple = "x86_64-apple-darwin11.0.0"
>>>>>
>>>>> I've attached a short test case that has the sequence
of calls that I'm making and one of the bitcode files I'm trying to use.
I'd be happy for any guidance or suggestions.
>>>>>
>>>>> Thanks,
>>>>> -matt
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>>>
>>>
>>>
> 
> 
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ons 2011-08-31 klockan 10:51 +0200 skrev Ralf
Karrenberg:
> Hi Matt, hi Bruno,
> 
> I am still struggling to use AVX via MCJIT on TOT... did you succeed yet?
> 
> I seem to be unable to even get lli to run some code with the
> "use-mcjit" flag.
> I attached a test case that works fine for "lli y.bc" but exits
with an
> error for "lli -use-mcjit y.bc":
> "LLVM ERROR: Unknown object format"
When I test the MCJIT under Linux I notice that lli are indeed trying to
load a buffer that contains an ELF object but fails to verify the format
using RuntimeDyldMachO::isKnownFormat this of course fails since Linux
uses ELF instead of Mach-o and this are causing lli to report (unknown
object format).

We need to implement
llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldELF.cpp
for the MCJIT to work on ELF systems.

Testcase:
./llvm-as < llvm/test/ExecutionEngine/hello.ll | ./lli -use-mcjit
> 
> Any more ideas?
> 
> Best,
> Ralf
Cheers
Xerxes