osf.S using 3 operand jmp and jsr

Richard Henderson rth@redhat.com
Wed Feb 25 16:41:00 GMT 2015


On 02/25/2015 03:18 AM, John E. Malmberg wrote:
> I noticed that the src/alpha/osf.S is using 3 operand jmp and jsr instructions.
> 
> What does gas do with the third operand?

It encodes it in bits 0:13 as a branch prediction hint.

> The VMS Macro 64 assembler only supports 2 operand jmp/jsr instructions.

Since it's a hint, you can just drop it.


r~



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