On 1/8/2013 4:24 PM, Eli Friedman wrote:> > It's kind of weird... inline asm hooks into the compiler at a low > level, so think of it this way: alias analysis queries the "memory" > clobber, but dead code elimination ignores the clobber list. You're > right, this makes absolutely no sense from the user's perspective.Ok, this sheds some light on it. Given that the "memory" clobber in the original example had no effect, I am assuming that this is indeed a bug. Am I correct? The problem there is that the load from G has been lost during translation to MI, so I'm assuming that this is something that the clobber should have prevented. I have a local patch for it that I can submit here for review. -Krzysztof -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
On Tue, Jan 8, 2013 at 2:28 PM, Krzysztof Parzyszek <kparzysz at codeaurora.org> wrote:> On 1/8/2013 4:24 PM, Eli Friedman wrote: >> >> >> It's kind of weird... inline asm hooks into the compiler at a low >> level, so think of it this way: alias analysis queries the "memory" >> clobber, but dead code elimination ignores the clobber list. You're >> right, this makes absolutely no sense from the user's perspective. > > > Ok, this sheds some light on it. > > Given that the "memory" clobber in the original example had no effect, I am > assuming that this is indeed a bug. Am I correct? The problem there is > that the load from G has been lost during translation to MI, so I'm assuming > that this is something that the clobber should have prevented.Yes, I believe so. -Eli