[llvm-commits] [PATCH] (try 2) Add an atomic lowering pass

[Peter Collingbourne]

Hi,

Here is the new version of the patch.  I updated it to use
getArgOperand and fixed a coding style issue (header ordering).

Thanks,

On Thu, Jun 24, 2010 at 12:32:42AM +0100, Peter Collingbourne wrote:
> Hi Duncan,
> 
> On Wed, Jun 23, 2010 at 09:25:39AM +0200, Duncan Sands wrote:
> > Hi Peter,
> > 
> > > My main motivation for the single-thread lowering is to be able to run
> > > code that uses these intrinsics in the KLEE symbolic execution engine
> > > but I imagine it could have other uses such as a whole-program LTO
> > > that lowers atomic operations to more efficient non-atomic operations
> > > when it is known to be safe to do so.
> > 
> > instead, how about writing an LLVM IR pass that turns atomic intrinsics into
> > non-atomic equivalent LLVM IR?
> 
> Yes, that seems more sensible.  I refactored the lowering into a pass
> and added the remaining intrinsics (see attached patch).  I'll commit
> this if approved.
> 
> I wonder if IntrinsicLowering should also be made into a pass, for
> consistency with the other lowering passes.
> 
> > Finally, I guess even "single threaded" code
> > may have a use for some atomic operations if it makes use of signal handlers.
> 
> Yes, good point.  Perhaps "non-preemptible" is better terminology
> which is what I used in the new patch.

-- 
Peter
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