search for: bticast

...not required to be disjoint. In the N1169 spec, it says A non-null pointer into an address space A can be cast to a pointer into another address space B, but such a cast is undefined if the source pointer does not point to a location in B. If the address spaces overlap, one should be able to bticast between them. -- Mon Ping On Sep 7, 2012, at 10:47 AM, Villmow, Micah wrote: > Should LLVM make bitcasts between pointers with different address spaces illegal? > > This will require a small clarification in the documentation and an assertion check added to the verifier, but I think...

Should LLVM make bitcasts between pointers with different address spaces illegal? This will require a small clarification in the documentation and an assertion check added to the verifier, but I think this would be a good approach. The reason being is that in different address spaces, pointers are not always the same size. This could be limited to make it legal only if the size of the pointer

...on-null pointer into an address space A can be cast to a pointer into > another address space B, but such a cast is undefined if the source > pointer does not point to a location in B. Use a ptrtoint + inttoptr to implement the cast. > If the address spaces overlap, one should be able to bticast between them. I am not okay with having the verifier accept or reject a bitcast based on the contents of the TargetData. Given that we intend to permit different address spaces to have different sized pointers, we'll need to reject all cross address-space bitcasts and casts will need to go...

...works for pointer-to-pointer conversions, this is specifically changing the address space. Ideas? '%bar = ptraddrspace i32 addrspace(5)* %foo to i32 addrspace(6)*' and the types must match except for the addrspace? Nick >>> If the address spaces overlap, one should be able to bticast between them. >> >> I am not okay with having the verifier accept or reject a bitcast based on the contents of the TargetData. Given that we intend to permit different address spaces to have different sized pointers, we'll need to reject all cross address-space bitcasts and casts wi...

...safe to convert to and from. It would seem more natural then to define a ptrtoptr operation that will truncate/extended as appropriate. It would make auto upgraded of old LLVM IR files easier to change bitcast of pointer to pointer. >> If the address spaces overlap, one should be able to bticast between them. > > I am not okay with having the verifier accept or reject a bitcast based on the contents of the TargetData. Given that we intend to permit different address spaces to have different sized pointers, we'll need to reject all cross address-space bitcasts and casts will need...

...h except for the addrspace? > I think you have the semantics right here that the types must match expect for the addrspace. How about addrspacecast since it is only changing the address space? -- Mon Ping > Nick > >>>> If the address spaces overlap, one should be able to bticast between them. >>> >>> I am not okay with having the verifier accept or reject a bitcast based on the contents of the TargetData. Given that we intend to permit different address spaces to have different sized pointers, we'll need to reject all cross address-space bitcasts and...