linux-kernel - Re: [PATCH] m68k: Fix asm register constraints for atomic ops

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Message-ID: <87r1fm4gkc.fsf@igel.home>
Date:   Sun, 25 Jul 2021 16:24:35 +0200
From:   Andreas Schwab <schwab@...ux-m68k.org>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Greg Ungerer <gerg@...inux.org>, Will Deacon <will@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Boqun Feng <boqun.feng@...il.com>,
        Brendan Jackman <jackmanb@...gle.com>,
        kernel test robot <lkp@...el.com>,
        Arnd Bergmann <arnd@...db.de>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        linux-m68k@...ts.linux-m68k.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] m68k: Fix asm register constraints for atomic ops

On Jul 25 2021, Geert Uytterhoeven wrote:

> Depending on register assignment by the compiler:
>
>     {standard input}:3084: Error: operands mismatch -- statement `andl %a1,%d1' ignored
>     {standard input}:3145: Error: operands mismatch -- statement `orl %a1,%d1' ignored
>     {standard input}:3195: Error: operands mismatch -- statement `eorl %a1,%d1' ignored
>
> Indeed, the first operand must not be an address register.  Fix this by
> adjusting the register constraint from "g" (general purpose register) to
> "d" (data register).

You should also allow immediate ("i").

There is the ASM_DI macro for that, but since CONFIG_RMW_INSNS is never
defined for CONFIG_COLDFIRE, it probably doesn't matter.

Andreas.

-- 
Andreas Schwab, schwab@...ux-m68k.org
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