[LLVMdev] NVPTX: why ret instruction is not translated to exit in kernel function?

[Justin Holewinski]

> -----Original Message-----
> From: Yabin Hu [mailto:yabin.hwu at gmail.com]
> Sent: Monday, May 14, 2012 11:40 PM
> To: LLVM Developers Mailing List; Justin Holewinski
> Subject: NVPTX: why ret instruction is not translated to exit in kernel
> function?
> 
> Hi Justin,
> 
> In the PTX backend, "ret" instruction at the end of a ptx_kernel function is
> translated to "exit" instruction. A test case named exit.ll demos this.
> But in the NVPTX backend, it seems that you didn't do such a translation.
> Why do you choose this? Is this due to the changes of the NVIDA PTX itself?

Either way is valid.  From the PTX spec:

    A return instruction executed in a top-level entry routine will terminate thread execution.

> 
> Thanks,
> 
> Yabin

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