IL2CPP generates bad code in 2019.2.6 (bad casting)

There's a new IL2CPP bug introduced in 2019.2.6. (Bug did not exist in 2019.2.5)

Code (CSharp):

1. double foo = 2147483649;
2. uint fooAsUint = (uint)foo;

In 2019.2.6 IL2CPP, fooAsUint is 2147483648.
When using the Mono runtime or using 2019.2.5 IL2CPP, fooAsUint is 2147483649.

This affects all platforms. I also tested on 2019.2.8, 2019.3.0b5, and 2020.1.0a7. The same bug exists in those Unity versions as well.

 

Have you looked at the generated IL2CPP in each case?

I just took a quick peek in an older Unity 5.6.6f2 targeting iOS and got this C codelet:

Code (csharp):

1.     double V_0 = 0.0;
2.     uint32_t V_1 = 0;
3.     {
4.         V_0 = (2147483649.0);
5.         double L_0 = V_0;
6.         V_1 = (((int32_t)((uint32_t)L_0)));
7.         uint32_t L_1 = V_1;
8.         return L_1;
9.     }

I don't have newer versions handy with me right now but I can check tomorrow. I'm curious because if you found a real bug, absolutely file it. Unity does fix a ton of bugs based on bug reports, and the smaller and simpler the repro steps the better.

 

@Kurt-Dekker, thanks, I just checked the C++ output and with 2019.2.6 it's performing an extra cast:

Code (CSharp):

1. V_1 = (((int32_t)((uint32_t)(int32_t)L_0)));

@JoshPeterson: I did submit a bug report two weeks ago, but I haven't heard any response or follow-up:
https://fogbugz.unity3d.com/default.asp?1186125_3dopatk59vmsmb67