[Bug rtl-optimization/31485] C complex numbers, amd64 SSE, missed optimization opportunity

[bisqwit at iki dot fi]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=31485

--- Comment #15 from Joel Yliluoma <bisqwit at iki dot fi> ---
(In reply to Richard Biener from comment #14)
> I also think llvms code generation is bogus since it appears the ABI
> does not guarantee zeroed upper elements of the xmm0 argument
> which means they could contain sNaNs:

Why would it matter that the unused portions of the register contain NaNs?