RFC: Using mode and code macros in *.md files

[James E Wilson]

Steve Ellcey wrote:
> I hadn't thought about that.  I did experiment with this a little by
> removing the addsf and adddf instructions from my ia64.md file and
> forcing it to use addxf.

You should check the effect on stack loads and stores.  SFmode is a 4 
byte access, DFmode is an 8 byte access, but XFmode is a 16 byte access. 
  If you force stuff to be XFmode, then we may end up with more stack 
accesses and larger stack sizes, which could affect performance.  This 
should only affect intermediate values, and we have plenty of FP 
registers, so this seems unlikely to be a problem, but it would be nice 
to check and make sure.
-- 
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com