[llvm-commits] [llvm] r57340 - /llvm/trunk/lib/ExecutionEngine/JIT/JIT.cpp

[Mon Ping Wang]

Hi Nicolas,

Sorry, I was not aware of Java issues.  I moved the locked upwards  
because if I didn't, I ran into a problem that materialized function  
got corrupted occasionally and I got some weird errors.  I'm not sure  
if this also could occur in Java as it is possible that it will never  
call getPointerToFunction twice on the same function by different  
threads.  Is the requirement that materializing the function must be  
lockless?  If no, maybe we can create a local lock around the  
materialization so we don't try to do it at the same time.  Otherwise,  
clients would need guard calls to getPointerToFunction.

   -- Mon Ping


On Oct 10, 2008, at 1:25 AM, Nicolas Geoffray wrote:

> Hi Mon,
>
> We're having a conflict here.
>
> Originally, materializing a function was guarded. However, in Java,
> materializing a function may execute Java code that use locks, hence
> deadlocks can happen.
> So I moved the guard after materialization.
>
> On a more general note I *don't* think materializing a function should
> be guarded by the JIT compiler. The JIT's mutex should only protect  
> JIT
> internal data. Materializing a function does not modify any JIT data.
>
> Nicolas
>
>
> Mon P Wang wrote:
>> Author: wangmp
>> Date: Thu Oct  9 20:47:42 2008
>> New Revision: 57340
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=57340&view=rev
>> Log:
>> Moved guard mutex upwards to guard materializing a function
>> in getPointerToFunction
>>
>>
>> Modified:
>>    llvm/trunk/lib/ExecutionEngine/JIT/JIT.cpp
>>
>> Modified: llvm/trunk/lib/ExecutionEngine/JIT/JIT.cpp
>> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/JIT/JIT.cpp?rev=57340&r1=57339&r2=57340&view=diff
>>
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> = 
>> =====================================================================
>> --- llvm/trunk/lib/ExecutionEngine/JIT/JIT.cpp (original)
>> +++ llvm/trunk/lib/ExecutionEngine/JIT/JIT.cpp Thu Oct  9 20:47:42  
>> 2008
>> @@ -489,6 +489,8 @@
>>   if (void *Addr = getPointerToGlobalIfAvailable(F))
>>     return Addr;   // Check if function already code gen'd
>>
>> +  MutexGuard locked(lock);
>> +
>>   // Make sure we read in the function if it exists in this Module.
>>   if (F->hasNotBeenReadFromBitcode()) {
>>     // Determine the module provider this function is provided by.
>> @@ -509,13 +511,11 @@
>>       abort();
>>     }
>>   }
>> -
>> +
>>   if (void *Addr = getPointerToGlobalIfAvailable(F)) {
>>     return Addr;
>>   }
>>
>> -  MutexGuard locked(lock);
>> -
>>   if (F->isDeclaration()) {
>>     void *Addr = getPointerToNamedFunction(F->getName());
>>     addGlobalMapping(F, Addr);
>>
>>
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