llvm dev - Jul 2020 - 来自林政宗的邮件

Hi, there.


I am writing an new backend. I defined an intrinsic which has two output. How
could I design the built-in function prototype? How could the built-in function
pass two output out?


Thanks!


Best regards,
Jerry
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On Thu, 23 Jul 2020 at 10:27, 林政宗 via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> I am writing an new backend. I defined an intrinsic which has two output.
How could I design the built-in function prototype? How could the built-in
function pass two output out?
I take it you mean in Clang? I think the usual solution is to return
one value normally and take a pointer argument to store the other in,
then emit the right code in CGBuiltin.cpp. The unnecessary store
usually gets optimized away pretty easily.

For example overflow intrinsics here:
https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html.

Cheers.

Tim.