http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46888
Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Keywords| |missed-optimization Status|UNCONFIRMED |NEW Last reconfirmed| |2010.12.10 19:42:11 Version|unknown |4.6.0 Ever Confirmed|0 |1 Severity|normal |enhancement --- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2010-12-10 19:42:11 UTC --- Here is a simpler example. Take: struct b { int t; int tt; }; union a { long long t; struct b b; }; long long f(int i, int t) { long long ii = ((long long)i) << 32; union a a; a.t = 0; a.b.t = i; a.b.tt = t; return a.t; } --- CUT --- For MIPS64r2 (both n64 and n32): move $2,$0 dins $2,$4,32,32 j $31 dins $2,$5,0,32 --- CUT --- is produced but the first two instructions can really be done as one shift: dsll $2,$4,32 j $31 dins $2,$5,0,32