[clang] [OpenCL][NVPTX] Don't set calling convention for OpenCL kernel (PR #170170)

[Hongyu Chen via cfe-commits]

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@@ -277,7 +277,9 @@ void NVPTXTargetCodeGenInfo::setTargetAttributes(
     }
   }
   // Attach kernel metadata directly if compiling for NVPTX.
-  if (FD->hasAttr<DeviceKernelAttr>())
+  // NOTE: Don't set kernel calling convention for handled OpenCL kernel,
+  // otherwise the stub version of kernel would be incorrect.
+  if (FD->hasAttr<DeviceKernelAttr>() && !M.getLangOpts().OpenCL)
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XChy wrote:

In the context here, I didn't find a way to check whether it's a stub unless by the mangled name. So I apply this code to the ones without `__clang_ocl_kern_imp_` prefix in the mangled name.

https://github.com/llvm/llvm-project/pull/170170