[LLVMdev] Question on equivalence of pointer types

[Rafael Espíndola]

I think so. My understanding is that address spaces can model things
like segmented memory or address regions that need special
instructions.

On 8 December 2014 at 20:12, Sanjoy Das <sanjoy at playingwithpointers.com> wrote:
> Partially answering my own question, in general these are not
> equivalent because LLVM allows for pointers in different address
> spaces to have different sizes.  However, are they equivalent if
> pointers in addrspace(1) have the same size as pointers in
> addrspace(0)?
>
> In other words, assuming pointers have the same size irrespective of
> address spaces, is storing / loading an (not storing into / loading
> from) addrspace(1)* allowed to do something semantically different
> than storing / loading an addrspace(0)*?
>
> Thanks,
> -- Sanjoy
>
> On Thu, Dec 4, 2014 at 10:09 PM, Sanjoy Das
> <sanjoy at playingwithpointers.com> wrote:
>> Is copy.0 semantically equivalent to copy.1 in the following example?
>>
>> define void @copy.0(i8 addrspace(1)* addrspace(1)* %src, i8
>> addrspace(1)* addrspace(1)* %dst) {
>>  entry:
>>   %val = load i8 addrspace(1)* addrspace(1)* %src
>>   store i8 addrspace(1)* %val, i8 addrspace(1)* addrspace(1)* %dst
>>   ret void
>> }
>>
>> define void @copy.1(i8 addrspace(1)* addrspace(1)* %src, i8
>> addrspace(1)* addrspace(1)* %dst) {
>>  entry:
>>   %src.cast = bitcast i8 addrspace(1)* addrspace(1)* %src to i8* addrspace(1)*
>>   %dst.cast = bitcast i8 addrspace(1)* addrspace(1)* %dst to i8* addrspace(1)*
>>
>>   %val = load i8* addrspace(1)* %src.cast
>>   store i8* %val, i8* addrspace(1)* %dst.cast
>>   ret void
>> }
>>
>> -- Sanjoy
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