http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56223
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2013-02-06
Ever Confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> 2013-02-06
12:14:54 UTC ---
Related support is in tree-ssa-phiopt.c which simply doesn't consider this
more complex pattern. A changed pattern detection could detect
if (v >= 0)
use +v
...
else
use -v
...
v unused outside the if
and replace it with
v' = abs (v);
if (v >= 0)
use v'
...
else
use v'
...
and hope for further optimizations to detect the equivalences.
Or special-case a single addition / subtraction statement here.
