The subreg question

[James E Wilson]

Ling-hua Tseng wrote:
> James E Wilson wrote:
> I read the descriptions of (high:m exp) and (lo_sum:m x y) in the gcc 
> internal manuls (Section 10.7 and 10.9).
> The last line of their descriptions confused me because they wrote "m 
> should be Pmode".

A doc bug.  You only need Pmode if you are operating on an address. 
high was originally added for loading addresses on a risc, like a sparc, 
in which case you would have to have Pmode.  However, it has proven 
useful in many other cases.  The sparc.md file for instance has an 
SFmode pattern that uses high/lo_sum, for loading an SFmode constant 
into a general register.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com