From what I can tell, the code is checking for PHIs that expect any value from
this block, not just constants.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232697
91177308-0d34-0410-b5e6-
96231b3b80d8
SmallPtrSet<MachineBasicBlock *, 4> SuccsHandled;
- // Check successor nodes' PHI nodes that expect a constant to be available
- // from this block.
+ // Check PHI nodes in successors that expect a value to be available from this
+ // block.
for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
const BasicBlock *SuccBB = TI->getSuccessor(succ);
if (!isa<PHINode>(SuccBB->begin())) continue;