Messages in this thread | | | Date | Thu, 30 Oct 2008 07:51:05 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH] x86: fix inline assembly constraints |
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Jike Song wrote: > > Yes, sometimes gcc did have bugs with its obscure inline asm > conventions. But I think the change of x86-64 atomic operations should > be OK. Anyway, the "+" constraint is more clear than a "=m" output and > a "m" input. > > The 32-bit atomic ops were already changed to "+m".(commit > b862f3b099f3ea672c7438c0b282ce8201d39dfc) >
You *THINK*. It's very easy to *THINK* that gcc won't do something utterly moronic, and you'd be wrong.
Just changing it for the sake of churn is pointless... if there is a bug, then we have to take the risk anyway, but if it is already correct, then there is no point in provoking a bug. Not *your* bug, because your code is correct, but gcc's bug.
FWIW, the reason that code doesn't use "+m" is because a version of gcc which we no longer support didn't handle it. That by itself isn't a reason to keep it, but there is also no reason to just "tidy" it, IMNSHO.
-hpa
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