Question about OpGenericCastToPtr/OpPtrCastToGeneric expansion

[MrSidims]

Hi,

Currently OpGenericCastToPtr/OpPtrCastToGeneric instructions provides casting from/to a pointer in Generic storage class to/from a pointer in Workgroup, CrossWorkgroup or Function storage classes.

In intel/llvm#1840 we added 2 more storage classes: DeviceOnlyINTEL/HostOnlyINTEL to represent global memory that can be allocated on device or host appropriately. Also we want to add in SPIR-V a possibility to cast from CrossWorkgroup pointer to DeviceOnlyINTEL/HostOnlyINTEL pointer and vice versa. There are basically two options how it can be achieved:

1. Add new instructions for that;
2. Expand OpGenericCastToPtr/OpPtrCastToGeneric potential in casting (under the extension).

The second option is slightly preferable for us, but taking in the account, that it will lead to addition of vendor customization in https://github.com/KhronosGroup/SPIRV-Tools which way is preferable for the community?

Thank you in advance.

[MrSidims]

Tagging @GarveyJoe @bashbaug