Switch to the LLVM SPIR-V back-end.

[maleadt]

PoC, requires quite some work

• exp intrinsic is broken

  PHI node operands are not the same type as the result!
    %common.ret.op = phi [2 x float] [ %177, %L5 ], [ %192, %L28 ], [ %201, %L41 ], [ %213, %L53 ], [ %4, %L25 ], [ %8, %L19 ]
  Function return type does not match operand type of return inst!
    ret [2 x float] %common.ret.op
   i32in function julia_exp_27849
  

• atomics probably have to be ported to native LLVM atomics
• the lack of OpCapability Linkage results in ZE_RESULT_ERROR_INVALID_MODULE_UNLINKED (I think)

[maleadt]

the lack of OpCapability Linkage results in ZE_RESULT_ERROR_INVALID_MODULE_UNLINKED (I think)

The actual issue is our use of OpenCL intrinsic functions to access things like the work dimension. We'll have to implement get_work_dim as an access to @__spirv_BuiltInWorkDim = external addrspace(1) global i32 instead of call to _Z12get_work_dim.

[maleadt]

Rebased. Things work, however, this triggers multiple crashes in the Intel compiler stack. Anybody who would want to look into this would need to (first upgrade the compiler stack, but if things persist then) reduce the issues to minimal issues and file them upstream.

[michel2323]

@maleadt We released a new oneAPI.jl version with NEO 25 and then rebased this branch. Now I get error: undefined reference to '_Z17__spirv_IAddCarryll'. Since this looks like a missing intrinsic I tried to bump SPIRVInstrinsics. However, in later versions this requires a method_table in oneAPI. I've tried to add that too, but I can't get the kernels to pick up anything and they return zeros. Mainly, I was then fiddling with @device_override, but I just got lost. Can you help a long here a bit?

[michel2323]

See: JuliaGPU/OpenCL.jl#316

[michel2323]

@maleadt I've rebased this again cleanly onto master.