Re: [BUG FIX] Make x86_32 uni-processor Atomic ops, Atomic

[H. Peter Anvin]

Michael S. Zick wrote:
> 
> Load Effective Address does two's complement arithmetic?
> I'll take your word for it.
> 

LEA, and all other address calculations use 2's-complement arithmetic:

	leal -1(%ebx),%eax
	leal 0xffffffff(%ebx),%eax

... is the same instruction.

However, gcc has been known to optimize out range checks when operating
on signed integers; it is allowed to do this by the C standard, but it
can give surprising results if the user expected wraparound.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

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