Re: [boost] [multiprecision] Help needed with strange constexpr slowdown

Subject: Re: [boost] [multiprecision] Help needed with strange constexpr slowdown
From: Hans Dembinski (hans.dembinski_at_[hidden])
Date: 2018-01-02 08:24:38

Hi John,

> On 31. Dec 2017, at 20:50, John Maddock via Boost <boost_at_[hidden]> wrote:
> 
> Folks I have a very strange issue that I need help with understanding, it comes from https://github.com/boostorg/multiprecision/issues/32 but in summary:

> There is a 20-30% slowdown when compiled in C++11 or later compared to C++03 with gcc 5.x or 6.x.

I am not able to answer you, I just also want to say it is weird. I thought that making things constexpr should not change run-time code emitted by the compiler at all.

Best regards,
Hans