Open
Description
| Bugzilla Link | 8108 |
| Version | trunk |
| OS | All |
| Attachments | missed.ll |
| Reporter | LLVM Bugzilla Contributor |
Extended Description
See the attached .ll files. In particular, note this snippet:
lor.rhs.i:
%cmp9.i = icmp eq i32 %tmp2, 16
br label %_Z16sparc_floating_pPK4type.exit
_Z16sparc_floating_pPK4type.exit:
%call19 = phi i1 [ true, %sw.bb.i ], [ %cmp9.i, %lor.rhs.i ], [ true, %sw.bb.i ]
%cmp = icmp eq i32 %tmp2, 16
%or.cond = and i1 %call19, %cmp
br i1 %or.cond, label %if.end18, label %sw.bb.i24
Notice that the comparison of %tmp2 with 16 is repeated. If this edge were to be threaded by JumpThreading, GVN would pick up the duplication and get rid of it. However, because we can't actually determine a value for the comparison JumpThreading does not currently choose to thread this edge.