------- Comment #7 from ubizjak at gmail dot com 2007-07-01 15:46 ------- Well, the problem is, that we "forgot" to take into account false branch from bb4 to bb6. In notation form the Comment #6, this branch has the condition !C4, so the total condition for branch from bb4 leading to bb6 would be: !C3 && !C4.
The conditions for both branches leading to phi node are then: left: (C3 || C4) && 1 -----> C3 || C4 right: !C3 && !C4 ---------> !(C3 || C4) With above correction, phi # quotient_3 = PHI <quotient_20(4), quotient_22(5)> would be substituted with: quotient_3 = !(C3 || C4) ? quotient_20 : quotient_22; or: quotient_3 = (C3 || C4) ? quotient_22 : quotient_20; which just happens to be the correct condition. QED. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31966
