From: Stefan Agner <stefan@agner.ch>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: Robin Murphy <robin.murphy@arm.com>,
Russell King <linux@armlinux.org.uk>,
Nicolas Pitre <nicolas.pitre@linaro.org>,
Mark Rutland <mark.rutland@arm.com>,
Arnd Bergmann <arnd@arndb.de>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Will Deacon <will.deacon@arm.com>,
julien.thierry@arm.com, LKML <linux-kernel@vger.kernel.org>,
Thierry Reding <thierry.reding@gmail.com>,
Nathan Chancellor <natechancellor@gmail.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Kristof Beyls <Kristof.Beyls@arm.com>,
Peter Smith <Peter.Smith@arm.com>
Subject: Re: [PATCH 1/2] ARM: drop unnecessary WASM
Date: Sun, 17 Mar 2019 16:44:44 +0100 [thread overview]
Message-ID: <e78bcb6154a5bf5f791fe29b40188ba0@agner.ch> (raw)
In-Reply-To: <CAKwvOdnb58nGXdweWTobGjqry7=9ZmfnMWnjTn8uHKt=Z5iabQ@mail.gmail.com>
On 06.03.2019 01:47, Nick Desaulniers wrote:
> On Tue, Mar 5, 2019 at 3:39 PM Robin Murphy <robin.murphy@arm.com> wrote:
>>
>> Hi Stefan,
>>
>> On 2019-03-05 10:18 pm, Stefan Agner wrote:
>> > The W macro for generating wide instructions when targeting Thumb-2
>> > is not required for the preload data instructions (pld, pldw) since
>> > they are only available as wide instructions. The GNU assembler seems
>> > to work with or without the .w appended when compiling an Thumb-2
>> > kernel. However, Clang's integrated assembler does not consider the
>> > .w variants as valid instructions:
>> >
>> > ./arch/arm/include/asm/processor.h:133:5: error: invalid instruction
>> > "pldw.w\t%a0 \n"
>> > ^
>> > <inline asm>:2:1: note: instantiated into assembly here
>> > pldw.w [r0]
>> > ^
>> > 1 error generated.
>>
>> Have you filed a bug against Clang for that? Something like "pldwal.w"
>
> Yes; please. For each deficiency you find, please file a bug. We're
> working on identifying what's missing from Clang's integrated
> assembler support. Given the list of issues, it's easier to estimate
> how much effort is needed, which helps us allocate resources towards
> fixing those issues better.
>
> It would be good to know if pldw.w is valid under UAL or not.
As far as I understand the Arm ARM it is valid under UAL.
Reported a bug in LLVM's bug tracker:
https://bugs.llvm.org/show_bug.cgi?id=40972
Will send a v2 patch mentioning this is really a work around for LLVM
and link to the bug report.
>
> Hopefully, the ARM kernel team can stress the importance of assembler
> support for their ISA to their LLVM team.
--
Stefan
next prev parent reply other threads:[~2019-03-17 15:44 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-05 22:18 Stefan Agner
2019-03-05 22:18 ` [PATCH 2/2] ARM: drop -mauto-it Stefan Agner
2019-03-05 22:21 ` Nick Desaulniers
2019-03-05 22:40 ` Stefan Agner
2019-03-05 23:20 ` Nick Desaulniers
2019-03-05 23:39 ` [PATCH 1/2] ARM: drop unnecessary WASM Robin Murphy
2019-03-06 0:47 ` Nick Desaulniers
2019-03-17 15:44 ` Stefan Agner [this message]
2019-03-06 7:58 ` Stefan Agner
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