[clang] [clang] Fallback to C calling convention for sycl_kernel attribute (PR #161349)

[Nick Sarnie via cfe-commits]

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@@ -123,8 +123,9 @@ unsigned TargetCodeGenInfo::getDeviceKernelCallingConv() const {
     // conventions; different targets might split structs passed as values
     // to multiple function arguments etc.
     return llvm::CallingConv::SPIR_KERNEL;
+  } else {
+    return llvm::CallingConv::C;
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sarnex wrote:

I'm not an expert in this area, but think I agree with Mariya on this one. we're going to run into a ton of problems if we are trying to use offloading attributes when not offloading. 

https://github.com/llvm/llvm-project/pull/161349