AMDGPU/SI: Add amdgpu_kernel calling convention. Part 1.

Summary:
This will be used for AMDGPU_HSA_KERNEL symbol type in output ELF.

Also, in the future unused non-kernels may be optimized.

For now, also accept SPIR_KERNEL for HCC frontend.

Also, add bitcode compatibility tests for missing calling conventions
except AVR_BUILTIN which doesn't have parse code.

Reviewers: tstellarAMD, arsenm

Subscribers: arsenm, joker.eph, llvm-commits
llvm-svn: 268717
diff --git a/llvm/test/CodeGen/AMDGPU/hsa.ll b/llvm/test/CodeGen/AMDGPU/hsa.ll
index 9017b62..1f07242 100644
--- a/llvm/test/CodeGen/AMDGPU/hsa.ll
+++ b/llvm/test/CodeGen/AMDGPU/hsa.ll
@@ -53,7 +53,7 @@
 ; HSA: .Lfunc_end0:
 ; HSA: .size   simple, .Lfunc_end0-simple
 
-define void @simple(i32 addrspace(1)* %out) {
+define amdgpu_kernel void @simple(i32 addrspace(1)* %out) {
 entry:
   store i32 0, i32 addrspace(1)* %out
   ret void