------- Comment #7 from rask at sygehus dot dk 2007-06-13 13:36 -------
Looking at this again, I don't think the transformation I'm making with the
splitter is valid, because I'm making up a zero extension which wasn't there to
begin with. The upper part could have been non-zero before the instruction.
As to the original example, it should be possible to optimize
addl %eax, %edx
cmpl %edx, %eax
ja .L7
into
addl %eax, %edx
jc .L7
with a CCmode expressing that the carry flag is set if %edx is smaller than
%eax.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30315
