diff --git a/llvm/lib/Target/AMDGPU/SIAnnotateControlFlow.cpp b/llvm/lib/Target/AMDGPU/SIAnnotateControlFlow.cpp
--- a/llvm/lib/Target/AMDGPU/SIAnnotateControlFlow.cpp
+++ b/llvm/lib/Target/AMDGPU/SIAnnotateControlFlow.cpp
@@ -13,6 +13,7 @@
 
 #include "AMDGPU.h"
 #include "GCNSubtarget.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/Analysis/LegacyDivergenceAnalysis.h"
 #include "llvm/Analysis/LoopInfo.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
@@ -157,7 +158,9 @@
 
 /// Pop the last saved value from the control flow stack
 Value *SIAnnotateControlFlow::popSaved() {
-  return Stack.pop_back_val().second;
+  auto [x, y] = Stack.pop_back_val();
+  // dbgs() << "popping off <" << x->getName() << ", " << *y << ">\n";
+  return y;
 }
 
 /// Push a BB and saved value to the control flow stack
@@ -209,6 +212,7 @@
   Value *Ret = CallInst::Create(If, Term->getCondition(), "", Term);
   Term->setCondition(ExtractValueInst::Create(Ret, 0, "", Term));
   push(Term->getSuccessor(1), ExtractValueInst::Create(Ret, 1, "", Term));
+  // dbgs() << "Stack size " << Stack.size() << '\n';
   return true;
 }
 
@@ -287,7 +291,6 @@
   }
 
   Term->setCondition(CallInst::Create(Loop, Arg, "", Term));
-
   push(Term->getSuccessor(0), Arg);
 
   return true;
@@ -296,7 +299,6 @@
 /// Close the last opened control flow
 bool SIAnnotateControlFlow::closeControlFlow(BasicBlock *BB) {
   llvm::Loop *L = LI->getLoopFor(BB);
-
   assert(Stack.back().first == BB);
 
   if (L && L->getHeader() == BB) {
@@ -327,13 +329,13 @@
     }
     CallInst::Create(EndCf, Exec, "", FirstInsertionPt);
   }
-
   return true;
 }
 
 /// Annotate the control flow with intrinsics so the backend can
 /// recognize if/then/else and loops.
 bool SIAnnotateControlFlow::runOnFunction(Function &F) {
+
   DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
   LI = &getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
   DA = &getAnalysis<LegacyDivergenceAnalysis>();
@@ -348,18 +350,23 @@
     BranchInst *Term = dyn_cast<BranchInst>(BB->getTerminator());
 
     if (!Term || Term->isUnconditional()) {
-      if (isTopOfStack(BB))
+      if (isTopOfStack(BB)) {
         Changed |= closeControlFlow(BB);
-
+      }
       continue;
     }
 
     if (I.nodeVisited(Term->getSuccessor(1))) {
-      if (isTopOfStack(BB))
+      if (isTopOfStack(BB)) {
         Changed |= closeControlFlow(BB);
+      }
 
-      if (DT->dominates(Term->getSuccessor(1), BB))
-        Changed |= handleLoop(Term);
+      if (DT->dominates(Term->getSuccessor(1), BB)) {
+        if (handleLoop(Term) && I.nodeVisited(Stack.back().first)) {
+          Changed = true;
+          closeControlFlow(Stack.back().first);
+        }
+      }
       continue;
     }
 
@@ -373,10 +380,15 @@
 
       Changed |= closeControlFlow(BB);
     }
-
     Changed |= openIf(Term);
   }
 
+  // A basic block may be pushed as a result of loop handling
+  // and could never be processed if it was already visited before.
+  // Close control flow at this basic block.
+  // if (Stack.size() == 1)
+  //   closeControlFlow(Stack.back().first);
+
   if (!Stack.empty()) {
     // CFG was probably not structured.
     report_fatal_error("failed to annotate CFG");
diff --git a/llvm/test/CodeGen/AMDGPU/si-annotate-nested-control-flows.ll b/llvm/test/CodeGen/AMDGPU/si-annotate-nested-control-flows.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/AMDGPU/si-annotate-nested-control-flows.ll
@@ -0,0 +1,40 @@
+; RUN: opt -mtriple=amdgcn-- -S -structurizecfg -si-annotate-control-flow %s | FileCheck %s
+
+define void @nested_inf_loop(i1 %0, i1 %1) {
+; CHECK-LABEL: define void @nested_inf_loop(
+; CHECK-NEXT: BB:
+; CHECK-NEXT:  br label %BB1
+; CHECK:      BB1:                                              ; preds = %BB3, %BB
+; CHECK-NEXT:  %2 = call { i1, i64 } @llvm.amdgcn.if.i64(i1 %0)
+; CHECK-NEXT:  %3 = extractvalue { i1, i64 } %2, 0
+; CHECK-NEXT:  %4 = extractvalue { i1, i64 } %2, 1
+; CHECK-NEXT:  br i1 %3, label %BB3, label %BB2
+; CHECK:      BB2:                                              ; preds = %BB1
+; CHECK-NEXT:  call void @llvm.amdgcn.end.cf.i64(i64 %4)
+; CHECK-NEXT:  br label %BB4
+; CHECK:      BB4:                                              ; preds = %BB4, %BB2
+; CHECK-NEXT:  %phi.broken = phi i64 [ %5, %BB4 ], [ 0, %BB2 ]
+; CHECK-NEXT:  %5 = call i64 @llvm.amdgcn.if.break.i64(i1 %1, i64 %phi.broken)
+; CHECK-NEXT:  %6 = call i1 @llvm.amdgcn.loop.i64(i64 %5)
+; CHECK-NEXT:  br i1 %6, label %BB4.BB3_crit_edge, label %BB4
+; CHECK:      BB4.BB3_crit_edge:                                ; preds = %BB4
+; CHECK-NEXT:  call void @llvm.amdgcn.end.cf.i64(i64 %5)
+; CHECK-NEXT:  br label %BB3
+; CHECK:      BB3:                                              ; preds = %BB4.BB3_crit_edge, %BB1
+; CHECK-NEXT:  br label %BB1
+;
+BB:
+  br label %BB1
+
+BB1:
+  br i1 %0, label %BB3, label %BB2
+
+BB2:
+  br label %BB4
+
+BB4:
+  br i1 %1, label %BB3, label %BB4
+
+BB3:
+  br label %BB1
+}