[LLVMdev] Fw: LLVM GC

[Trevor Elliott]

Hi Sam,

I've not actually gotten to the linking process with my runtime, as I've
compiled it with clang -emit-llvm -c, and then archived it with llvm-ar
and llvm-ranlib.  I'm also not producing a GC plugin, as I'm using the
builtin "shadow-stack" strategy.

My current build process looks like this:

 1. build the compiler
 2. build the runtime using clang -emit-llvm -c
 3. generate an archive from the runtime .bc files using llvm-ar and
llvm-ranlib
 3. compile a program with the compiler, producing a .bc file
 4. link the program and runtime together using llvm-ld
 5. run the program with lli

This all works fine until step 5 when the stack trace gets generated.
The function that it complains about, @main, is the main function from
my runtime.  When disassembled with llvm-dis, it doesn't have a gc
attribute on the declaration.  Should it still be getting processed by
the "shadow-stack" strategy?

Thanks!

--trevor


On 01/14/2011 05:33 PM, Samuel Crow wrote:
> Forgot to CC the list.
> 
> 
> ----- Forwarded Message ----
>> From: Samuel Crow <samuraileumas at yahoo.com>
>> To: Trevor Elliott <trevor at galois.com>
>> Sent: Fri, January 14, 2011 7:33:15 PM
>> Subject: Re: [LLVMdev] LLVM GC
>>
>> Hi Trevor,
>>
>> Are you linking with LibStdC++ or LibC++?  That is a  requirement for running 
>> code that has been compiled from C++ to  bitcode.
>>
>> Hope this helps,
>>
>> --Sam Crow
>>
>>
>> ----- Original  Message ----
>>> From: Trevor Elliott <trevor at galois.com>
>>> To: llvmdev at cs.uiuc.edu
>>> Sent: Fri,  January 14, 2011 7:17:30 PM
>>> Subject: [LLVMdev] LLVM GC
>>>
>>>  Hi,
>>>
>>> I've been implementing a compiler that targets LLVM, and  was  looking
>>> into using the shadow-stack gc strategy.   Currently, I build the  runtime
>>> with clang (using -emit-llvm), and  then link that with the LLVM  bitcode
>>> output from my compiler using  llvm-ld.
>>>
>>> This works fine without  the gc strategy  annotations and use of the
>>> llvm.gcroot intrinsic, but adding  them  causes some odd behavior: the
>>> resulting bitcode will generate a  large  stack trace from lli (appended
>>> at the end of this message),  and the resulting  native assembly,
>>> generated with llc, will never  update my llvm_gc_root_chain  global.
>>>
>>> Interestingly, if I  build my runtime with g++, or clang  without
>>> -emit-llvm, and link  everything together after generating  native
>>> assembly from the  output of my compiler, it works.  The stack  roots get
>>>  registered, and the llvm_gc_root_chain global gets  updated.
>>>
>>> Is linking in the runtime as an LLVM bitcode object something   that I
>>> should expect to work, or does it make more sense to build  the  runtime
>>> for the target, and not try to emit LLVM bitcode  programs from my  
> compiler?
>>>
>>> Thanks!
>>>
>>>  --trevor
>>>
>>>
>>> 0  libLLVM-2.8.so    0x0000003cc36eee9f
>>> 1  libLLVM-2.8.so   0x0000003cc36ef99a
>>> 2  libpthread.so.0  0x0000003cc200f4a0
>>>  3  libLLVM-2.8.so   0x0000003cc33360dd
>>>  llvm::StructType::StructType(llvm::LLVMContext&,   std::vector<llvm::Type
>>> const*, std::allocator<llvm::Type  const*>  > const&, bool) + 237
>>> 4   libLLVM-2.8.so   0x0000003cc3337c95
>>>  llvm::StructType::get(llvm::LLVMContext&,  std::vector<llvm::Type  const*,
>>> std::allocator<llvm::Type const*>  > const&,  bool) + 533
>>> 5  libLLVM-2.8.so   0x0000003cc3242d58
>>>  6  libLLVM-2.8.so  0x0000003cc318f09e
>>> 7    libLLVM-2.8.so   0x0000003cc3330628
>>>  llvm::FPPassManager::runOnFunction(llvm::Function&) +  424
>>>  8  libLLVM-2.8.so   0x0000003cc33307cb
>>>  llvm::FunctionPassManagerImpl::run(llvm::Function&) +  91
>>>  9  libLLVM-2.8.so   0x0000003cc33309bd
>>>  llvm::FunctionPassManager::run(llvm::Function&) +  173
>>> 10  libLLVM-2.8.so   0x0000003cc33e8647
>>>  llvm::JIT::jitTheFunction(llvm::Function*,  llvm::MutexGuard const&) +  39
>>> 11 libLLVM-2.8.so   0x0000003cc33e8a2f
>>>  llvm::JIT::runJITOnFunctionUnlocked(llvm::Function*,   llvm::MutexGuard
>>> const&) + 15
>>> 12 libLLVM-2.8.so    0x0000003cc33e8cde
>>> llvm::JIT::getPointerToFunction(llvm::Function*)  +  606
>>> 13 libLLVM-2.8.so   0x0000003cc33ea253
>>>  llvm::JIT::runFunction(llvm::Function*,   std::vector<llvm::GenericValue,
>>>  std::allocator<llvm::GenericValue>  > const&) + 67
>>> 14  libLLVM-2.8.so   0x0000003cc336ad4a
>>>  llvm::ExecutionEngine::runFunctionAsMain(llvm::Function*,
>>>  std::vector<std::string,  std::allocator<std::string> >  const&, char
>>> const* const*) +  1130
>>> 15 lli              0x0000000000404cd6 main  + 2054
>>> 16 libc.so.6         0x0000003cc1c1ec5d __libc_start_main + 253
>>> 17 lli               0x0000000000403689
>>> Stack dump:
>>>  0.     Program arguments: lli test.bc
>>> 1.    Running  pass 'Lower  Garbage Collection Instructions' on function 
>> '@main'
>>> zsh: segmentation fault  (core dumped)   ./test
>>>
>>>
>>
>>
>>       
>>
> 
> 
>       
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