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From: "H. Peter Anvin" <hpa@zytor.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>,
	Jesse Brandeburg <jesse.brandeburg@intel.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Regression due to 0c44c2d0f459 x86: Use asm goto to implement better modify_and_test() functions
Date: Tue, 03 Dec 2013 17:36:25 -0800	[thread overview]
Message-ID: <529E8719.4070202@zytor.com> (raw)

Hi guys,

0c44c2d0f459 x86: Use asm goto to implement better modify_and_test()
functions

causes a regression, because it incorrectly changed the constraints of
bitops.

Specifically, the GEN_BINARY_RMWcc() hardcodes a constraint as "er", but
it needs to be "Ir" for the bitops themselves.  "I" is correct (as
opposed to "J" even on 64 bits, because we only generate the 64-bit
version when we have a register operand.

Unfortunately there isn't a way we can get gcc+gas to generate a version
with an offset pointer.

	-hpa



             reply	other threads:[~2013-12-04  1:37 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-12-04  1:36 H. Peter Anvin [this message]
2013-12-04  8:59 ` Regression due to 0c44c2d0f459 x86: Use asm goto to implement better modify_and_test() functions Ingo Molnar
2013-12-04 16:44   ` H. Peter Anvin
2014-01-31 21:32     ` Alex Williamson
2013-12-04 22:51 ` [tip:x86/urgent] x86, bitops: Correct the assembly constraints to testing bitops tip-bot for H. Peter Anvin

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