Re: [PATCH] ARM: mtd-xip: work around clang/llvm bug

From: Nick Desaulniers
Date: Tue Jul 09 2019 - 14:08:05 EST


On Tue, Jul 9, 2019 at 1:41 AM Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
>
> On Mon, Jul 8, 2019 at 10:31 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
>
> > llvm gets confused by inline asm with .rep directives,
>
> Are the LLVM developers aware of the bug?
> It seems like something we can work around but should
> eventually be fixed properly in LLVM, right?

Arnd filed the bug yesterday. I looked at it; so someone working on
LLVM is aware of it. The kernel is definitely exercising weak points
in our inline assembly support.

> > Link: https://bugs.llvm.org/show_bug.cgi?id=42539

> I guess this brings up the old question whether the compiler should
> be worked around or just considered immature, but as it happens this

Definitely a balancing act; we prioritize work based on what's
feasible to work around vs must be implemented. A lot of my time is
going into validation of asm goto right now, but others are ramping up
on the integrated assembler (clang itself can be invoked as a
substitute for GNU AS; but there's not enough support to do `make
AS=clang` for the kernel just yet).
--
Thanks,
~Nick Desaulniers