Re: [PATCH 06/31] perf, kvm: Support the intx/intx_cp modifiers inKVM arch perfmon emulation

[Avi Kivity]

On 10/03/2012 02:11 PM, Andi Kleen wrote:
>> > -			eventsel & ARCH_PERFMON_EVENTSEL_INT);
>> > +			eventsel & ARCH_PERFMON_EVENTSEL_INT,
>> > +			!!(eventsel & HSW_INTX),
>> > +			!!(eventsel & HSW_INTX_CHECKPOINTED));
>> >  }
>> >  
>> 
>> Those !! are !necessary, since the formal argument is a bool.
> 
> bool is 1 or 0, x & y with y > 1 is not 1 or 0.
> iirc assigning > 1 to bool is undefined
> 
> So I think they are necessary.

Conversion to bool coerces the value to 0 or 1.

_Bool ret(int x) { return x & 0x10000; }
  20:	81 e7 00 00 01 00    	and    $0x10000,%edi
  26:	0f 95 c0             	setne  %al
  29:	c3                   	retq


-- 
error compiling committee.c: too many arguments to function
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