fatal error: error in backend: Cannot select: intrinsic %llvm.aarch64.fjcvtzs

[ahatanak]

Bugzilla Link	46828
Version	trunk
OS	All
CC	@Arnaud-de-Grandmaison-ARM,@RKSimon,@pbarrio,@zygoloid,@sjoerdmeijer,@smithp35,@TNorthover

Extended Description

$ cat test.c
int main(int argc, char *argv[]) {
double x = argc;
return __builtin_arm_jcvt(x);
}

$ clang test.c -c -target aarch64-arm-none-eabi

[ahatanak]

This is the commit that added support for the intrinsic: https://reviews.llvm.org/D64495

It wasn't clear to me whether this is a backend or frontend bug. It seemed to me that the frontend should reject the code if the backend cannot handle the builtin.

[TNorthover]

I'd say neither, or maybe a very weak QoI issue in the front-end.

If you're using random _builtin* CPU-specific intrinsics you're expected to make sure they work first IMO. The supported way to access this functionality is to include arm_acle.h which will define __jcvt if the CPU you're targetting supports this functionality.

[c-rhodes]

fails more gracefully now: https://godbolt.org/z/bbnddfqhM

$ clang-15
fatal error: error in backend: Cannot select: intrinsic %llvm.aarch64.fjcvtzs

$ clang (trunk)
<source>:3:10: error: '__builtin_arm_jcvt' needs target feature v8.3a
    3 |   return __builtin_arm_jcvt(x);
      |          ^
1 error generated.