[PATCH 1/3] mbedtls: Introduce subset of compiler-rt from LLVM

[Tom Rini]

On Fri, Jun 20, 2025 at 02:00:09PM -0400, Raymond Mao wrote:
> Hi Tom,
> 
> On Fri, 20 Jun 2025 at 13:20, Tom Rini <trini at konsulko.com> wrote:
> >
> > On Fri, Jun 20, 2025 at 08:10:08AM -0700, Raymond Mao wrote:
> > > Introduce the implementation of udivti3 and udivmodti4 from LLVM
> > > compiler-rt builtins for building MbedTLS bignum module via Clang.
> > >
> > > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
> > > ---
> > >  lib/mbedtls/port/compiler-rt/LICENSE.TXT      | 311 ++++++++++++++++++
> > >  lib/mbedtls/port/compiler-rt/README.txt       |  11 +
> > >  .../compiler-rt/lib/builtins/int_endianness.h | 114 +++++++
> > >  .../port/compiler-rt/lib/builtins/int_lib.h   | 171 ++++++++++
> > >  .../port/compiler-rt/lib/builtins/int_types.h | 276 ++++++++++++++++
> > >  .../port/compiler-rt/lib/builtins/int_util.h  |  47 +++
> > >  .../compiler-rt/lib/builtins/udivmodti4.c     | 158 +++++++++
> > >  .../port/compiler-rt/lib/builtins/udivti3.c   |  23 ++
> > >  8 files changed, 1111 insertions(+)
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/LICENSE.TXT
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/README.txt
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/lib/builtins/int_endianness.h
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/lib/builtins/int_lib.h
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/lib/builtins/int_types.h
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/lib/builtins/int_util.h
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/lib/builtins/udivmodti4.c
> > >  create mode 100644 lib/mbedtls/port/compiler-rt/lib/builtins/udivti3.c
> > >
> > > diff --git a/lib/mbedtls/port/compiler-rt/LICENSE.TXT b/lib/mbedtls/port/compiler-rt/LICENSE.TXT
> > > new file mode 100644
> > > index 00000000000..5a79a1b9d5c
> > > --- /dev/null
> > > +++ b/lib/mbedtls/port/compiler-rt/LICENSE.TXT
> > > @@ -0,0 +1,311 @@
> > > +==============================================================================
> > > +The LLVM Project is under the Apache License v2.0 with LLVM Exceptions:
> > > +==============================================================================
> > > +
> > > +                                 Apache License
> > > +                           Version 2.0, January 2004
> > > +                        http://www.apache.org/licenses/
> >
> > I don't know that this is compatible for us. Looking at
> > https://www.apache.org/licenses/GPL-compatibility.html it talks about
> > how you can use it with GPLv3 (which we are *NOT*) but not GPLv2.
> >
> My bad didn't realize Apache 2.0 is not compatible with GPLv2...
> I am not sure but it seems that this incompatibility does not even
> allow static linking into a GPLv2 project.
> Then, how to make it possible to use LLVM? Can we upgrade to GPLv2+?

However the linux kernel people do it, we can do it too. And perhaps
that's part of what's motivating LLVM to be able to disable these
intrinsics that we don't actually need?

-- 
Tom
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