Re: [Nasm-devel] [nasm:master] nosplit: Limit the effect of NOSPLIT

[anonymous c. <nas...@us...>]

> To put things differently: what is the specific behavior you rely on,

The code base I am faced with contains instances of both
the "reg times 1" and "reg times 2" cases, each with both
natural (e.g. [reg] or [reg+rex]) and explicit (e.g. [reg*1] or
[reg*2]) uses. An explicit NOSPLIT qualifier is used when-
ever a SIB encoding without a base register is desired.

> what made you rely on that specific behavior,

The "reg times 2" case worked since 0.96 (late 1997).

The "reg times 1" case worked since 0.98.34 (mid 2002).

> and how would this naturally appear in programmers' code?

Via explicitly specified NOSPLIT qualifiers.

>> [reg times 1]
>
> It has been undocumented all along, and looks nothing so much as an
> unintentional consequence of Debbie, who implemented this, not wanting
> to deal with distinguishing "reg*1" from "reg".  So when you say
> "intentional/expected behavior" I would argue it is very questionable on
> both fronts.

The feature request asked for -- and got -- a rather specific
behavior: permit NOSPLIT not just for the "reg times 2" but
also for the "reg times 1" case.

The blame for not getting this 0.98.34 change documented
should fall on me -- I should have spotted the lack of a doc
change in Debbie's commit... but failed to do so.