linux-kernel - Re: riscv: llvm-compiler: calling convention violation: temporary register $t2 is used to pass the ninth function parameter

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Message-ID: <CA+wH296d8p06E6LU4HUxcGZEf6ZkcUS_oEUY4k_zcC-Y6+-1+Q@mail.gmail.com>
Date:   Thu, 12 May 2022 09:35:03 +0100
From:   Alex Bradbury <asb@...radbury.org>
To:     Changbin Du <changbin.du@...wei.com>
Cc:     Craig Topper <craig.topper@...ive.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Steven Rostedt <rostedt@...dmis.org>, hw.huiwang@...wei.com,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, codegen-riscv@...course.llvm.org,
        llvmproject@...course.llvm.org
Subject: Re: riscv: llvm-compiler: calling convention violation: temporary
 register $t2 is used to pass the ninth function parameter

On Thu, 12 May 2022 at 09:30, Changbin Du <changbin.du@...wei.com> wrote:
>
> On Wed, May 11, 2022 at 01:07:14PM -0700, Craig Topper wrote:
> > I’m guessing that because the function is static, the calling convention was changed to fastcall which allows us to ignore the ABI.
> >
> I think so. But the mcount function assumes the ABI is not changed.

It feels like this is a problem that would be encountered on other
architectures with clangbuiltlinux as well, due to dropping the ABI
requirements for local functions. Have you seen something similar
elsewhere Nick?

Best,

Alex