Add isNonCriticalEdge fast check for a specific edge.

Author: atrick

include/swift/SILOptimizer/Utils/CFGOptUtils.h

@@ -83,6 +83,11 @@ void replaceBranchTarget(TermInst *t, SILBasicBlock *oldDest,
 /// Check if the edge from the terminator is critical.
 bool isCriticalEdge(TermInst *t, unsigned edgeIdx);
 
+inline bool isNonCriticalEdge(SILBasicBlock *predBB, SILBasicBlock *succBB) {
+  return predBB->getSingleSuccessorBlock() == succBB
+    || succBB->getSinglePredecessorBlock() == predBB;
+}
+
 /// Splits the edge from terminator if it is critical.
 ///
 /// Updates dominance information and loop information if not null.

lib/SILOptimizer/Utils/CFGOptUtils.cpp

@@ -601,9 +601,10 @@ bool swift::hasCriticalEdges(SILFunction &f, bool onlyNonCondBr) {
     if (isa<BranchInst>(bb.getTerminator()))
       continue;
 
-    for (unsigned idx = 0, e = bb.getSuccessors().size(); idx != e; ++idx)
-      if (isCriticalEdge(bb.getTerminator(), idx))
+    for (SILBasicBlock *succBB : bb.getSuccessorBlocks()) {
+      if (!isNonCriticalEdge(&bb, succBB))
         return true;
+    }
   }
   return false;
 }