1; RUN: opt < %s -passes=reassociate -disable-output 2 3; It has been detected that dead loops like the one in this test case can be 4; created by -passes=jump-threading (it was detected by a csmith generated program). 5; 6; According to -passes=verify this is valid input (even if it could be discussed if 7; the dead loop really satisfies SSA form). 8; 9; The problem found was that the -passes=reassociate pass ends up in an infinite loop 10; when analysing the 'deadloop1' basic block. See "Bugzilla - Bug 30818". 11define void @deadloop1() { 12 br label %endlabel 13 14deadloop1: 15 %1 = xor i32 %2, 7 16 %2 = xor i32 %1, 8 17 br label %deadloop1 18 19endlabel: 20 ret void 21} 22 23 24; Another example showing that dead code could result in infinite loops in 25; reassociate pass. See "Bugzilla - Bug 30818". 26define void @deadloop2() { 27 br label %endlabel 28 29deadloop2: 30 %1 = and i32 %2, 7 31 %2 = and i32 %3, 8 32 %3 = and i32 %1, 6 33 br label %deadloop2 34 35endlabel: 36 ret void 37} 38