[cfg] Add back in bool return value, returning a value to it this time.

Author: gottesmm

include/swift/SILOptimizer/Utils/CFG.h

@@ -131,7 +131,7 @@ bool splitAllCriticalEdges(SILFunction &F, bool OnlyNonCondBr,
 ///
 /// A current invariant of Ownership SIL is that cond_br can only have critical
 /// edges with non-trivial arguments. This simplifies computation.
-void splitAllCondBrCriticalEdgesWithNonTrivialArgs(SILFunction &F,
+bool splitAllCondBrCriticalEdgesWithNonTrivialArgs(SILFunction &Fn,
                                                    DominanceInfo *DT,
                                                    SILLoopInfo *LI);
 

lib/SILOptimizer/Utils/CFG.cpp

@@ -931,7 +931,7 @@ void swift::completeJointPostDominanceSet(
   copy(MustVisitSuccessorBlocks, std::back_inserter(Result));
 }
 
-void swift::splitAllCondBrCriticalEdgesWithNonTrivialArgs(SILFunction &Fn,
+bool swift::splitAllCondBrCriticalEdgesWithNonTrivialArgs(SILFunction &Fn,
                                                           DominanceInfo *DT,
                                                           SILLoopInfo *LI) {
   // Find our targets.
@@ -955,11 +955,16 @@ void swift::splitAllCondBrCriticalEdgesWithNonTrivialArgs(SILFunction &Fn,
     Targets.emplace_back(&Block, CondBranchInst::FalseIdx);
   }
 
+  if (Targets.empty())
+    return false;
+
   for (auto P : Targets) {
     SILBasicBlock *Block = P.first;
     unsigned Index = P.second;
     auto *Result = splitCriticalEdge(Block->getTerminator(), Index, DT, LI);
     (void)Result;
     assert(Result);
   }
+
+  return true;
 }