Messages in this thread | | | Date | Sat, 18 Aug 2007 16:19:24 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 0/24] make atomic_read() behave consistently across all architectures |
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On Sat, Aug 18, 2007 at 03:41:13PM -0700, Linus Torvalds wrote: > > > On Sat, 18 Aug 2007, Paul E. McKenney wrote: > > > > One of the gcc guys claimed that he thought that the two-instruction > > sequence would be faster on some x86 machines. I pointed out that > > there might be a concern about code size. I chose not to point out > > that people might also care about the other x86 machines. ;-) > > Some (very few) x86 uarchs do tend to prefer "load-store" like code > generation, and doing a "mov [mem],reg + op reg" instead of "op [mem]" can > actually be faster on some of them. Not any that are relevant today, > though.
;-)
> Also, that has nothing to do with volatile, and should be controlled by > optimization flags (like -mtune). In fact, I thought there was a separate > flag to do that (ie something like "-mload-store"), but I can't find it, > so maybe that's just my fevered brain..
Good point, will suggest this if the need arises.
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