On Tue, Feb 14, 2017 at 09:51:02PM +0000, Ard Biesheuvel wrote: > To prevent unnecessary branching, mark the exit condition of the > primary loop as likely(), given that a carry in a 32-bit counter > occurs very rarely. > > On arm64, the resulting code is emitted by GCC as > > 9a8: cmp w1, #0x3 > 9ac: add x3, x0, w1, uxtw > 9b0: b.ls 9e0 <crypto_inc+0x38> > 9b4: ldr w2, [x3,#-4]! > 9b8: rev w2, w2 > 9bc: add w2, w2, #0x1 > 9c0: rev w4, w2 > 9c4: str w4, [x3] > 9c8: cbz w2, 9d0 <crypto_inc+0x28> > 9cc: ret > > where the two remaining branch conditions (one for size < 4 and one for > the carry) are statically predicted as non-taken, resulting in optimal > execution in the vast majority of cases. > > Also, replace the open coded alignment test with IS_ALIGNED(). > > Cc: Jason A. Donenfeld <Jason@xxxxxxxxx> > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> Patch applied. Thanks. -- Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
