llvm dev - Feb 2010 - [LLVMdev] ConstantMerge & addressSpaces

Hello,

It seems I stepped on a bug with the ConstantMerge IPO pass, regarding address
spaces.

For example, if a module contains the following:

@a = internal constant i16 224
@b = internal addrspace(30) constant i16 224

Although a & b have the same initializer, i think they should not be merged.
Attempting to do it anyway will trigger an assertion.

I guess the safe and easy way is to only merge constants in the 0 address space,
as the other address spaces may need a target specific behaviour. The patch for
this is attached.

Best regards,
--
Arnaud de Grandmaison
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On Feb 12, 2010, at 3:57 AM, Arnaud Allard de Grandmaison wrote:
> Hello,
>  
> It seems I stepped on a bug with the ConstantMerge IPO pass, regarding
address spaces.
>  
> For example, if a module contains the following:
>  
> @a = internal constant i16 224
> @b = internal addrspace(30) constant i16 224
>  
> Although a & b have the same initializer, i think they should not be
merged. Attempting to do it anyway will trigger an assertion.
>  
> I guess the safe and easy way is to only merge constants in the 0 address
space, as the other address spaces may need a target specific behaviour. The
patch for this is attached.
>  
Nice catch, I took the opportunity to clean up the constmerge pass while fixing
this:
http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20100208/096071.html

-Chris

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