On Wed, 4 Aug 2004, Nigel Stephens wrote: > > Here are my proposals I've referred to previously. Instruction counts > >are 9, 9 and 10, respectively, as I've missed an additional instruction > >required to handle shifts by 0 (or actually any multiples of 64). > > IMHO handling a shift by zero correctly is important. Agreed, hence an additional instruction needed. > > "not %1, %3\n\t" > > "srlv %1, %L2, %1\n\t" > > "srl %1, %1, 1\n\t" > > > > Why not the shorter: > > > "neg %1, %3\n\t" > > "srlv %1, %L2, %1\n\t" Notice the difference -- this shorter code doesn't handle shifts by zero correctly. ;-) > And then in __ashrdi3: > > "andi %1, %3, 0x20\n\t" > ".set push\n\t" > ".set noat\n\t" > "sra $1, %M2, 31\n\t" > "movn %L0, %M0, %1\n\t" > "movn %M0, $1, %1\n\t" > ".set pop" > > Cute, but I think that should be > > "sra $1, %M0, 31\n\t" > > (i.e %M0 not %M2) Well, I've tested it for all shift counts and it works properly as is -- we care of the value of bit #31 to be shifted only and at this stage it's the same in both registers. So it's just a matter of style. Maciej
