Undefined behavior negating minimum int64_t value

[jandem]

There are a few places where the aarch64 code uses -operand.immediate(). If the immediate is INT64_MIN, the behavior is undefined.

This was fixed for Add and Sub in 2020 in b8da04d, but the same pattern still shows up in Ccmp, Ccmn, and Neg.

We (Mozilla) ran into this because our fork didn't have the fix for Add and Sub and it was causing problems with recent Clang versions, but we then noticed the same pattern is still present in these other methods.

[mmc28a]

Thanks for the report. Agreed about the missing cases - I'll put together a fix.

[jandem]

For what it's worth, this is the patch I wrote but our code bases have diverged some: https://hg.mozilla.org/mozilla-central/rev/95db18f53141

[mmc28a]

CR #99 refactors the existing code and should fix the remaining cases.