OpenCL call lowering to LLVM IR SPIRV fails LLVM's verifier

[bcardosolopes]

LLVM's verifier (llvm/lib/IR/Verifier.cpp:3647) is choking on a call:

calling convention does not permit calls
  call spir_kernel void @bar(ptr addrspace(1) %10)
fatal error: error in backend: Lowering from LLVMIR dialect to llvm IR failed!

The CIR output indicates cc(spir_kernel), maybe a bug during lowering. Needs investigation, reduced testcase here: 11e643e

[bcardosolopes]

clang/test/CIR/Lowering/call-op-call-conv.cir also contains a disabled test hitting this issue

[piotrrak]

Should kernels be callable from kernels? Calling __kernel bar directly looks incorrect to me. There's device side enqueue extension, but I imagine it'd be intrinsic rather than callinst. Don't quote me on this, but this test looks wrong.

[bcardosolopes]

cc @seven-mile

[seven-mile]

Yes. That's a sloppy test that wishes to cover more diverse cases.

I believe directly removing kernel call stuff does no harm to code coverage. Will submit a patch ; )