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Division by zero

Division by zero

Posted Jan 4, 2025 22:56 UTC (Sat) by khim (subscriber, #9252)
In reply to: Division by zero by dskoll
Parent article: Preventing data races with Pony

How do you compile that? GCC is smart enough to recognize UB and produce appropriate brk if optimizations are enabled, but that's not related to what CPU is doing. And unoptimized version calls function that can check the divisior.

Try to invoke sdiv directly, then CPU should do what it does. At least for me it produces zero, as CPU manual promised.

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Division by zero

Posted Jan 4, 2025 23:18 UTC (Sat) by dskoll (subscriber, #1630) [Link]

I compiled in both cases with make test which simply invoked gcc with no optimization. I checked the assembly output and you are right. On the armhf architecture, it looks like gcc calls into a library function: 

        bl      __aeabi_idiv

but on the aarch64 architecture, it calls an assembly instruction: 

        sdiv    w0, w1, w0


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