[clang] [llvm] Stop using spir_kernel calling convention on non-SPIR targets. (PR #191090)

[Matt Arsenault via cfe-commits]

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@@ -86,6 +85,7 @@ class NVPTXTargetCodeGenInfo : public TargetCodeGenInfo {
   unsigned getDeviceKernelCallingConv() const override {
     return llvm::CallingConv::PTX_Kernel;
   }
+  bool supportsKernelLowering() const override { return true; }
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arsenm wrote:

I don't understand the point of this when getDeviceKernelCallingConv already exists 

https://github.com/llvm/llvm-project/pull/191090