On 2/14/2012 3:41 PM, robin wrote:
If "everyone" understands that "SR regx,regx" and "XR regx,regx" zero
regx then there is little to no benefit to having a macro that is "ZERO
regx".
If so, there's be little need for comments such as the example
XR R5,R5 zeroise R5
Something sensible like
ZERO 5
makes it absolutely clear, and soes not need a "clarifying" remark.
Even this may depend on your trust in the author of
the macro; possibly yourself; possibly not.
A novice may have coded as the macro body:
L regx,=F'0'
which requires addressability to the literal pool. The results
are worst if the caller has changed the content of the base
register and neglected to code a DROP.
Or:
LA regx,0
where the effect on the top half of regx depends on whether
64-bit mode is in effect. This may actually be reason to
prefer this form.
-- gil
