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Date: Mon, 2 Feb 2015 15:30:54 +0100
From: Radim Krčmář <rkrcmar@...hat.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
Nadav Amit <namit@...technion.ac.il>,
Gleb Natapov <gleb@...nel.org>
Subject: Re: [PATCH 2/8] KVM: x86: cleanup kvm_apic_match_*()
2015-02-02 15:28+0100, Paolo Bonzini:
>
>
> On 02/02/2015 15:26, Radim Krčmář wrote:
> >>> > > + return ((logical_id >> 4) == (mda >> 4))
> >>> > > + && (logical_id & mda & 0xf);
> > was merged as
> >
> > + return ((logical_id >> 4) == (mda >> 4))
> > + && (logical_id & mda & 0xf) != 0;
> >
> > but it has to be parenthesized ('&&' has lower precedence than '!=').
>
> Lower precedence means that the merged version is right (unless my brain
> went bonkers, which I cannot exclude). "!=" has higher precedence and
> thus it is implicitly parenthesized.
>
> In fact the first comparison could have its parentheses removed as well.
Yes, it could be,
logical_id >> 4 == mda >> 4 && (logical_id & mda & 0xf) != 0
I missed the point and thought that you wanted to turn the whole
expression into bool, when it already was one.
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