[llvm-dev] The builtins library of compiler-rt is a performance HOG^WKILLER

Chandler Carruth via llvm-dev llvm-dev at lists.llvm.org
Wed Dec 5 05:38:45 PST 2018


On Mon, Dec 3, 2018 at 2:51 PM Stefan Kanthak via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi @ll,
>
> LLVM-7.0.0-win32.exe contains and installs
> lib\clang\7.0.0\lib\windows\clang_rt.builtins-i386.lib
>
> The implementation of (at least) the multiplication and division
> routines __[u]{div,mod,divmod,mul}[sdt]i[34] shipped with this
> libraries SUCKS: they are factors SLOWER than even Microsoft's
> NOTORIOUS POOR implementation of 64-bit division shipped with
> MSVC and Windows!
>

I'm really happy that you're looking at making some of these routines
better (and Craig and others have given excellent suggestions about how to
go about this.

But in the future, please be more polite and respectful on the LLVM mailing
lists. Insults, all-capital-letters, and inflammatory language are
unnecessary and unhelpful in our community. You can tell us that "the
performance is really bad" and we'll actually take that more seriously than
the phrasing you've used in this email.

Anyways, also looking forward to the improvements to this area.

-Chandler
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