https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61984
Segher Boessenkool <segher at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2014-08-10
CC| |segher at gcc dot gnu.org
Component|target |rtl-optimization
Ever confirmed|0 |1
--- Comment #2 from Segher Boessenkool <segher at gcc dot gnu.org> ---
GCC already does this transformation: the pattern
used for the compare is mov<mode>_internal2.
With -m32, the wanted "mr. 3,4" comes out.
With -m64, IRA makes a non-optimal decision: it
gets {r125:CC=(r4<=>0); r124=r4} as a first insn,
and as a secon insn it gets (in a different BB)
r3=r124, and then it decides assigning r4 to the
pseudo r124 is the best idea.
