llvm dev - Sep 2012 - [LLVMdev] JIT problem with thread local global variable

Hello,
        I am trying to use LLVM JIT to emit the following codes and execute
both functions in my program, but

I get segmentation fault, the problem seems to originate from
"thread_local" global variable.

my LLVM library is 3.1 and platform is x86 32bit , OS : Ubuntu 10.04


@0 = internal thread_local global i32 522, align 4

define void @setValue(i32 %v) {
  %1 = alloca i32, align 4
  store i32 %v, i32* %1, align 4
  %2 = load i32* %1, align 4
  store i32 %2, i32* @0, align 4
  ret void
}

define i32 @getValue() {
  %1 = load i32* @0, align 4
  ret i32 %1
}




I am wondering if LLVM JIT is able to emit machine codes with thread_local
memory because in

lib/Target/X86/X86JITInfo.cpp, the following function is responsible for
allocating thread memory for global variable.

It does not return an address, but an index.


*char** X86JITInfo
<http://140.113.166.39/llvm-3.1.src/HTML/S/8340.html#L442>::allocateThreadLocalMemory
<http://140.113.166.39/llvm-3.1.src/HTML/R/13517.html>(size_t
<http://140.113.166.39/llvm-3.1.src/HTML/D/21902.html> size
<http://140.113.166.39/llvm-3.1.src/HTML/Y/37476.html>) *{*** *#if*
*defined*(X86_32_JIT
<http://140.113.166.39/llvm-3.1.src/HTML/Y/27302.html>) &&
!*defined*(__APPLE__
<http://140.113.166.39/llvm-3.1.src/HTML/Y/27623.html>) &&
!*defined*(_MSC_VER
<http://140.113.166.39/llvm-3.1.src/HTML/Y/27566.html>)   TLSOffset
<http://140.113.166.39/llvm-3.1.src/HTML/Y/23295.html> -= size
<http://140.113.166.39/llvm-3.1.src/HTML/D/21901.html>;   *return*
TLSOffset <http://140.113.166.39/llvm-3.1.src/HTML/Y/23295.html>;
*#else*   llvm_unreachable
<http://140.113.166.39/llvm-3.1.src/HTML/D/20353.html>("Cannot
allocate thread local storage on this arch!"); *#endif
}*
**

Consequently, if we set LLVM global variable G to be thread local, and use

jit to call getOrEmitGlobalVariable(G), we get an index, not address.

So what if we want to change the value in G, how can we do this.


Have A Nice Day
Chia Lun Liu
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Hi,
>          I am trying to use LLVM JIT to emit the following codes and
execute
> both functions in my program, but
>
> I get segmentation fault, the problem seems to originate from
"thread_local"
> global variable.
>
> my LLVM library is 3.1 and platform is x86 32bit , OS : Ubuntu 10.04
try passing -use-mcjit to lli.  The old JIT implementation didn't support
thread
local variables, while the new implementation (turned on by -use-mcjit) does.

Ciao, Duncan.
>
>
> @0 = internal thread_local global i32 522, align 4
>
> define void @setValue(i32 %v) {
>    %1 = alloca i32, align 4
>    store i32 %v, i32* %1, align 4
>    %2 = load i32* %1, align 4
>    store i32 %2, i32* @0, align 4
>    ret void
> }
>
> define i32 @getValue() {
>    %1 = load i32* @0, align 4
>    ret i32 %1
> }
>
>
>
>
> I am wondering if LLVM JIT is able to emit machine codes with thread_local
> memory because in
>
> lib/Target/X86/X86JITInfo.cpp, the following function is responsible for
> allocating thread memory for global variable.
>
> It does not return an address, but an index.
>
>
> *char**X86JITInfo 
<http://140.113.166.39/llvm-3.1.src/HTML/S/8340.html#L442>::allocateThreadLocalMemory
<http://140.113.166.39/llvm-3.1.src/HTML/R/13517.html>(size_t 
<http://140.113.166.39/llvm-3.1.src/HTML/D/21902.html>  size 
<http://140.113.166.39/llvm-3.1.src/HTML/Y/37476.html>)/{/
> ////
>   /#if/  *defined*(X86_32_JIT 
<http://140.113.166.39/llvm-3.1.src/HTML/Y/27302.html>) &&
!*defined*(__APPLE__ 
<http://140.113.166.39/llvm-3.1.src/HTML/Y/27623.html>) &&
!*defined*(_MSC_VER 
<http://140.113.166.39/llvm-3.1.src/HTML/Y/27566.html>)
>     TLSOffset  <http://140.113.166.39/llvm-3.1.src/HTML/Y/23295.html>
-=size  <http://140.113.166.39/llvm-3.1.src/HTML/D/21901.html>;
>     *return*  TLSOffset 
<http://140.113.166.39/llvm-3.1.src/HTML/Y/23295.html>;
>   /#else/
>     llvm_unreachable 
<http://140.113.166.39/llvm-3.1.src/HTML/D/20353.html>("Cannot
allocate thread local storage on this arch!");
>   /#endif
> }/
> //
>
> Consequently, if we set LLVM global variable G to be thread local, and use
>
> jit to call getOrEmitGlobalVariable(G), we get an index, not address.
>
>
> So what if we want to change the value in G, how can we do this.
>
>
> Have A Nice Day
> Chia Lun Liu
>
>
>
>
>
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>

Thanks for your hint, I will try that 


Have A Nice Day

Chia Lun



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