Extended Description

Nick Lewycky reported that dominators we're getting updated for this .ll file correctly:

declare void %use1(int)

void %f(int %i, bool %c) {
entry:
%A = seteq int %i, 0
br bool %A, label %brtrue, label %brfalse

brtrue:
%B = phi bool [ true, %brtrue ], [ false, %entry ]
call void %use1(int %i)
br bool %B, label %brtrue, label %brfalse

brfalse:
call void %use1(int %i)
ret void
}

Correct is:

Inorder Dominator Tree:
[1] %entry
[2] %entry.brfalse_crit_edge
[2] %entry.brtrue_crit_edge
[3] %brtrue
[4] %brtrue.brfalse_crit_edge
[4] %brtrue.brtrue_crit_edge
[2] %brfalse

Computed is:

Inorder Dominator Tree:
[1] %entry
[2] %brtrue
[3] %brtrue.brtrue_crit_edge
[3] %brtrue.brfalse_crit_edge
[2] %brfalse
[2] %entry.brtrue_crit_edge
[2] %entry.brfalse_crit_edge

BCE assumes that the broken edge block can never dominate anything, which is incorrect in this case.

-Chris