[LLVMdev] Disable optimization

Daniel M Gessel gessel at apple.com
Fri Nov 28 08:23:03 PST 2008


Wouldn't Clang be a good option to generating unoptimized LLVM IR?

Dan


On Nov 28, 2008, at 6:13 AM, Duncan Sands wrote:

>> It matters if the optimisations the students have to implement are  
>> the
>> optimisations done implicitly by LLVM.
>
> They are not really done by LLVM, because no optimizations are done  
> on the
> LLVM IR.  They are done by llvm-gcc, a front-end to LLVM:
> (1) gcc does constant folding all over the place (nothing can be  
> done about
> this)
> (2) the llvm-gcc to LLVM converter also does constant folding (this  
> can
> be turned off easily enough)
> (3) it seems that unused code can also be eliminated during the  
> conversion
> to LLVM IR.  Presumably the code is simply never converted to IR in  
> the
> first place.  I'm not sure how this happens.  Perhaps it is possible  
> to
> ensure that everything gets converted.
>
> Ciao,
>
> Duncan.
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