From: Tkhai Kirill <tkhai@xxxxxxxxx> Date: Wed, 11 May 2011 03:21:49 +0400 > 11.05.11, 00:28, "David Miller" <davem@xxxxxxxxxxxxx>: > >>I don't understand why you're testing "andcc %o3, %o0, %g0", as %o3 has >>the value computed in "srl %g1, 1, %o3" here. > >>What is so interesting about "ptr & (length >> 1)"? > > 1)Label ccte (rather, cc_end_cruft) copies data sequentially by pieces of length 2^x bytes from biggest to smallest. For example, if %g1 is 15, then the label copies 8+4+2+1=15, and %o0 must be aligned to 8. > > Let alignment a = 2^x. Pointer ptr % a == 0 when: > ptr & (a >> 1) == 0 > ptr & (a >> 2) == 0 > .. > > Or, what is the same: > ptr & (length >> 1) == 0 > ptr & (length >> 2) == 0 > .. > > I.e. we are looking for right alignment, if another case don't call ccte. > > 2)We check %o0 only, because %o1 has the same last two bits, and cc_end_cruft writes 4 bytes or less. Now I understand, thanks for explaining. Applied. -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
