[llvm-dev] Why x86_64 divq is not used for 128-bit by 64-bit division?

[Paweł Bylica via llvm-dev]

Hi there,

Let's have this C code:

unsigned long div(unsigned __int128 n, unsigned long d)
{
return n / d;
}

I would assume that the divq is the perfect match here. But the compiler
generates the
code that calls the __udivti3 procedure which performs 128-bit by 128-bit
division.

Why is divq not used here?

- Paweł
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