[LLVMdev] broken Atomic.cpp on Darwin

Xi Wang xi.wang at gmail.com
Sun May 24 00:30:28 PDT 2009


sorry, i checked my installation again.  the symbolic link of g++
pointed to g++-4.0 (weird) while that of gcc pointed to gcc-4.2.  my
bad.  sorry again & thanks!

On Sun, May 24, 2009 at 2:34 AM, Owen Anderson <resistor at mac.com> wrote:
> No, that should work fine, and is exactly what I use to compile atomics on
> Darwin.
>
> --Owen
>
> On May 23, 2009, at 11:02 PM, Xi Wang wrote:
>
>> Thanks.  I think I am using Apple GCC 4.2.
>>
>> i686-apple-darwin9-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5566)
>>
>> Should I use something else for LLVM?
>>
>> - xi
>>
>> On Sun, May 24, 2009 at 1:20 AM, Owen Anderson <resistor at mac.com> wrote:
>>>
>>> On May 23, 2009, at 9:41 PM, Xi Wang wrote:
>>>
>>> There is no __sync_synchronize or __sync_val_compare_and_swap on Mac
>>> OS X.  One might use OSMemoryBarrier or OSAtomicCompareAndSwap32
>>> instead.  The patch is attached.
>>>
>>> Actually, __sync_synchronize and __sync_val_compare_and_swap DO exist on
>>> Darwin, but only if you use Apple's GCC 4.2 (or later), just as it is on
>>> Linux.  We always want to use these intrinsic versions if possible,
>>> because
>>> they're much lower overhead.
>>> The policy Chris has proposed is that we simply do not support
>>> multithreaded
>>> LLVM with a host compiler pre-GCC 4.2.  If you need multithreaded LLVM on
>>> an
>>> unsupported platform, you can build a single threaded LLVM and LLVM-GCC,
>>> and
>>> then use that to build a multithreaded LLVM.
>>> --Owen
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
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>>>
>>>
>>
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