Messages in this thread | | | Date | Mon, 22 Aug 2011 21:41:09 -0700 | From | "H. Peter Anvin" <> | Subject | Re: [PATCH 07/15] x86: add xadd helper macro |
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On 08/22/2011 04:43 PM, Jeremy Fitzhardinge wrote: > On 08/22/2011 04:29 PM, H. Peter Anvin wrote: >> On 08/22/2011 04:15 PM, Jeremy Fitzhardinge wrote: >>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com> >>> >>> Add a common xadd implementation. >>> >>> This has the side effect of generating a bad instruction if you try to >>> use it on a 64-bit value on a 32-bit system - but don't do that. >>> >> It would be better to barf at that point, so we get the error with a C >> line... also, there needs to be a default clause with >> __compiletime_error() in it. > > OK, but the "standard of care" here is the old "calling undefined > function" link error; getting a bad asm instruction is a little more > helpful, in a sense. But agreed on the default: case. I'll see if I > can fix up xadd and cmpxchg to fail better as well. >
__compiletime_error() is better than either, obviously...
-hpa
-- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
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