Re: [PATCH 5/7] x86, boot, LLVM: Use regparm=0 for memcpy and memset

From: Peter Zijlstra
Date: Fri Mar 17 2017 - 08:10:20 EST


On Thu, Mar 16, 2017 at 05:15:18PM -0700, Michael Davidson wrote:
> Use the standard regparm=0 calling convention for memcpy and
> memset when building with clang.
>
> This is a work around for a long standing clang bug
> (see https://llvm.org/bugs/show_bug.cgi?id=3997) where
> clang always uses the standard regparm=0 calling convention
> for any implcit calls to memcpy and memset that it generates
> (eg for structure assignments and initialization) even if an
> alternate calling convention such as regparm=3 has been specified.

Seriously, fix LLVM already.