On Tue, Jul 28, 2015 at 02:12:36PM +0100, Jiong Wang wrote: > > The instruction sequences for preparing argument for TLS descriptor > runtime resolver and the later function call to resolver can actually be > hoisted out of the loop. > > Currently we can't because we have exposed the hard register X0 as > destination of "set". While GCC's RTL data flow infrastructure will > skip or do very conservative assumption when hard register involved in > and thus some loop IV opportunities are missed. > > This patch add another "tlsdesc_small_pseudo_<mode>" pattern, and avoid > expose x0 to gcc generic code. > > Generally, we define a new register class FIXED_R0 which only contains > register > 0, so the instruction sequences generated from the new add pattern is the same > as tlsdesc_small_<mode>, while the operand 0 is wrapped as pseudo register > that > RTL IV opt can handle it. > > Ideally, we should allow operand 0 to be any pseudo register, but then > we can't model the override of x0 caused by the function call which is > hidded by the UNSPEC. > > So here, we restricting operand 0 to be x0, the override of x0 can be > reflected to the gcc. > > OK for trunk?
OK. Thanks, James
