[llvm] [NVPTX] Add Custom ABI (abi_preserve) support via function attributes (PR #227499)

[Durgadoss R via llvm-commits]

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@@ -844,6 +852,8 @@ void NVPTXAsmPrinter::emitFunctionEntryLabel() {
   if (isKernelFunction(*F))
     emitKernelFunctionDirectives(*F, O);
 
+  emitFunctionDirectives(*F, O);
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durga4github wrote:

Can we add a comment stating that this needs to be "here" ...between .func and the body?
would moving it after no-return work?

https://github.com/llvm/llvm-project/pull/227499