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From: "H. Peter Anvin" <hpa@zytor.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
	peng.hao2@zte.com.cn, richard.weiyang@gmail.com
Cc: penghao122@sina.com.cn, rkrcmar@redhat.com, tglx@linutronix.de,
	mingo@redhat.com, joro@8bytes.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, x86@kernel.org
Subject: Re: [PATCH] kvm/x86 : avoid shifting signed 32-bit value by 31 bits
Date: Mon, 15 Oct 2018 10:30:43 -0700	[thread overview]
Message-ID: <32ae2c96-51da-304f-9fc0-d531979eff97@zytor.com> (raw)
In-Reply-To: <08fd066f-e6c5-f82c-544f-536e9f29e6f3@redhat.com>

On 10/15/18 10:23 AM, Paolo Bonzini wrote:
> 
> Even for a value from a 32-bit register?  That would be _BIT, which
> doesn't exist.
> 

Just use _BITUL(). gcc is smart enough to know that that the resulting value
is representable in 32 bits.

Or if you really care, submit a patch to create _BITU(), but I don't
personally see much of a point.

	-hpa

      reply	other threads:[~2018-10-15 17:30 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-04 17:47 [PATCH] kvm/x86 : avoid shifting signed 32-bit value by 31 bits Peng Hao
2018-10-06  2:11 ` Wei Yang
     [not found]   ` <201810061131044868733@zte.com.cn>
2018-10-06  7:08     ` Wei Yang
     [not found]       ` <201810080904344038939@zte.com.cn>
2018-10-08  2:25         ` Wei Yang
2018-10-15 17:12           ` Paolo Bonzini
2018-10-15 17:16         ` H. Peter Anvin
2018-10-15 17:23           ` Paolo Bonzini
2018-10-15 17:30             ` H. Peter Anvin [this message]

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