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From: Peter Zijlstra <peterz@infradead.org>
To: will.deacon@arm.com, mingo@kernel.org
Cc: linux-kernel@vger.kernel.org, longman@redhat.com,
	andrea.parri@amarulasolutions.com, tglx@linutronix.de,
	bigeasy@linutronix.de, hpa@linux.intel.com, JBeulich@suse.com,
	bp@alien8.de
Subject: Re: [PATCH v2 3/4] x86/asm: Simplify GEN_*_RMWcc() macros
Date: Thu, 4 Oct 2018 11:18:47 +0200	[thread overview]
Message-ID: <20181004091847.GJ19272@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20181003130957.108960094@infradead.org>

On Wed, Oct 03, 2018 at 03:03:00PM +0200, Peter Zijlstra wrote:
> +#define __GEN_RMWcc(fullop, _var, cc, clobbers, ...)			\
> +({									\
> +	__label__ cc_label;						\
>  	asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"		\
> +			: : [var] "m" (_var), ## __VA_ARGS__		\
>  			: clobbers : cc_label);				\
> +	0;								\
>  cc_label:								\
> +	1;								\
> +})

That's obviously crap...

This one seems to actually compile and generate identical code:

#define __GEN_RMWcc(fullop, _var, cc, clobbers, ...)			\
({									\
	bool c = false;							\
	asm_volatile_goto (fullop "; j" #cc " %l[cc_label]"		\
			: : [var] "m" (_var), ## __VA_ARGS__		\
			: clobbers : cc_label);				\
	if (0) {							\
cc_label:	c = true;						\
	}								\
	c;								\
})

  reply	other threads:[~2018-10-04  9:36 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-03 13:02 [PATCH v2 0/4] locking/qspinlock, x86: Improve determinism for x86 Peter Zijlstra
2018-10-03 13:02 ` [PATCH v2 1/4] locking/qspinlock: Re-order code Peter Zijlstra
2018-10-03 13:02 ` [PATCH v2 2/4] locking/qspinlock: Rework some comments Peter Zijlstra
2018-10-10 16:13   ` Will Deacon
2018-10-03 13:03 ` [PATCH v2 3/4] x86/asm: Simplify GEN_*_RMWcc() macros Peter Zijlstra
2018-10-04  9:18   ` Peter Zijlstra [this message]
2018-10-16 16:05   ` [tip:locking/core] x86/asm: 'Simplify' " tip-bot for Peter Zijlstra
2018-10-03 13:03 ` [PATCH v2 4/4] locking/qspinlock, x86: Provide liveness guarantee Peter Zijlstra
2018-10-10 16:12   ` Will Deacon
2018-10-12  9:22     ` Will Deacon
2018-10-16 16:06   ` [tip:locking/core] " tip-bot for Peter Zijlstra
2018-10-16 16:04 ` [tip:locking/core] locking/qspinlock: Re-order code tip-bot for Peter Zijlstra
2018-10-16 16:04 ` [tip:locking/core] locking/qspinlock: Rework some comments tip-bot for Peter Zijlstra

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