[llvmlinux] "make test" for x86_64 target just hung there, why?

Daniel Sanders Daniel.Sanders at imgtec.com
Fri Sep 11 18:37:31 UTC 2015

It could be that GCC does more inlining and optimises the bug away. This happened to me with the slab allocator initialization on the Mips arch.

At the time, I was able to reproduce it in GCC by making the inline and always_inline macros empty. I don't recall the exact spelling of those macros, they may have additional underscores.

Hope that helps.
From: llvmlinux-bounces at lists.linuxfoundation.org [llvmlinux-bounces at lists.linuxfoundation.org] on behalf of Sedat Dilek [sedat.dilek at gmail.com]
Sent: 11 September 2015 17:10
To: pageexec at gmail.com
Cc: llvmlinux at lists.linuxfoundation.org; David Woodhouse
Subject: Re: [llvmlinux] "make test" for x86_64 target just hung there, why?

On Wed, Sep 9, 2015 at 10:24 PM, PaX Team <pageexec at gmail.com> wrote:
> On 9 Sep 2015 at 12:12, Sedat Dilek wrote:
>> I can boot into a CLANG v3.7 compiled kernel when lib/bitmap is
>> compiled with GCC v4.9.
> are you sure it's not lib/hweight.o instead? under gcc it's compiled
> with special flags (CONFIG_ARCH_HWEIGHT_CFLAGS) which clang doesn't
> support and we used to patch that out but i have no idea about the
> current state of affairs.

Hi pipacs :-),

if I switch the compiler with the same llvmlinux-patchset and
kernel-config GCC v4.9 builds fine.
So, I am not sure if the CLANG v3.7 compiler is BROKEN when doing
(always-)inlining functions.

Can you give some aid, how to verify if it is a COMPILER problem or a
kernel-side one?

- Sedat -
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