On Thursday 16 July 2015 23:09:55 Gunnar Roth wrote:
> > QHash is slower than std::unordered because std::hash<double> is inline
> > and qHash(double) is out-of-line.
>
> May I ask why?
> Is this valid for all qHash()?
Commit c0791ac76ec7cfdc3945efa67a6f72ee3623413c
Add qHash() overloads for floating-point types
Implemented out-of-line to avoid potential FP-comparison warnings, as well
as to be able to use the file-static hash() functions, which gets inlined
unlike qHashBits(), which cannot be.
It was a tradeoff between a faster inlining into your code and a faster hashing
algorithm.
--
Thiago Macieira - thiago.macieira (AT) intel.com
Software Architect - Intel Open Source Technology Center
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