From: Pete Zaitcev <[EMAIL PROTECTED]> Date: Mon, 11 Dec 2006 17:29:07 -0800
> On Mon, 11 Dec 2006 15:52:47 -0800, Matt Helsley <[EMAIL PROTECTED]> wrote: > > > I'm shocked memcpy() introduces 8-byte stores that violate architecture > > alignment rules. Is there any chance this a bug in ia64's memcpy() > > implementation? I've tried to read it but since I'm not familiar with > > ia64 asm I can't make out significant parts of it in > > arch/ia64/lib/memcpy.S. > > The arch/ia64/lib/memcpy.S is probably fine, it must be gcc doing > an inline substitution of a well-known function. > > A commenter on my blog mentioned seeing the same thing in the past. > (http://zaitcev.livejournal.com/107185.html?thread=128945#t128945) > > It's possible that applying (void *) cast to the first argument of memcpy > would disrupt this optimization. But since we have a well understood > patch by Erik, which only adds a penalty of 32 bytes of stack waste > and 32 bytes of memcpy, I thought it best not to bother with heaping > workarounds. Yes GCC can assume the object is aligned because of the type of the argument to memcpy(). I tried myself some games with adding a "packed" attribute to the pointer declaration (trying to tell it that "the thing pointed to" might be unaligned), but to no avail. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/