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A possible optimisation, but note that TAS sets the condition codes differently. Useful if you want to set bit 7 of a data register and don't care about its previous contents.
BSET #7,Dn → TAS Dn
ORI.B #$80,Dn → TAS Dn
The only condition code affected by BSET is Z (set if bit 7 was 0, cleared otherwise). For TAS, N is set if bit 7 was already 1. Z is set if Dn.B was 0. V and C are cleared.
For ORI, condition codes are set similarly to TAS, except they refer to the "after" value, whereas the TAS condition codes refer to the "before" value. So Z will never be set with ORI.B #$80,Dn.
The TAS instruction isn't generally/reliably usable when accessing memory on the Amiga, due to the locked read-modify-write cycle it uses. But since there's no memory access when the operand is a data register using it is okay in that case.
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