Branch hints

[Joseph M. Newcomer]

Are there any mnemonics for the branch hint prefixes? The MASM documentation is so bad it
is hard to tell. The official Intel manuals also do not mention anything.

In a related question of poor documentation, are the REX prefixes implicit if I mention a
register in the 64-bit architecture extended range? I have not begun to experiment with
64-bit assembler.

joe
Joseph M. Newcomer [MVP]
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[Tim Roberts]

Post by Joseph M. Newcomer
Are there any mnemonics for the branch hint prefixes? The MASM documentation is so bad it
is hard to tell. The official Intel manuals also do not mention anything.

Good question. Unless I've missed a memo, MASM does not have prefixes
defined -- you'll have to use "db". Gas allows ",pt" or ",pn" suffixes for
"predict taken" or "predict not-taken", a notation copied from the Sparc:

je,pt dest

Post by Joseph M. Newcomer
In a related question of poor documentation, are the REX prefixes implicit if I mention a
register in the 64-bit architecture extended range? I have not begun to experiment with
64-bit assembler.

MASM will do that for you. I don't think there are any situations where an
explicit override is required, although I haven't done nearly as much
64-bit as 32-bit. Gas also has a syntax for that, although again they say
it should never be required.