Index: include/polly/ScopInfo.h
===================================================================
--- include/polly/ScopInfo.h
+++ include/polly/ScopInfo.h
@@ -1399,6 +1399,9 @@
     return getRegion()->contains(L);
   }
 
+  /// Check if the statement contains boxed loops.
+  bool hasBoxedLoops() const;
+
   /// Return whether this statement represents @p BB.
   bool represents(BasicBlock *BB) const {
     if (isCopyStmt())
@@ -1601,7 +1604,6 @@
 
   /// Insert an instruction before all other instructions in this statement.
   void prependInstruction(Instruction *Inst) {
-    assert(isBlockStmt() && "Only block statements support instruction lists");
     Instructions.insert(Instructions.begin(), Inst);
   }
 
@@ -1927,9 +1929,6 @@
   Scop(Region &R, ScalarEvolution &SE, LoopInfo &LI,
        ScopDetection::DetectionContext &DC, OptimizationRemarkEmitter &ORE);
 
-  /// Return the LoopInfo used for this Scop.
-  LoopInfo *getLI() const { return Affinator.getLI(); }
-
   //@}
 
   /// Initialize this ScopBuilder.
@@ -2370,6 +2369,9 @@
   Scop &operator=(const Scop &) = delete;
   ~Scop();
 
+  /// Return the LoopInfo used for this Scop.
+  LoopInfo *getLI() const { return Affinator.getLI(); }
+
   /// Get the count of copy statements added to this Scop.
   ///
   /// @return The count of copy statements added to this Scop.
Index: lib/Analysis/ScopInfo.cpp
===================================================================
--- lib/Analysis/ScopInfo.cpp
+++ lib/Analysis/ScopInfo.cpp
@@ -1737,6 +1737,24 @@
   return getRegion()->getEntry();
 }
 
+bool ScopStmt::hasBoxedLoops() const {
+  Loop *L = getSurroundingLoop();
+
+  if (L) {
+    for (Loop *L : L->getSubLoops())
+      if (contains(L))
+        return true;
+  }
+
+  LoopInfo *LI = getParent()->getLI();
+
+  for (Loop *L : make_range(LI->begin(), LI->end()))
+    if (contains(L))
+      return true;
+
+  return false;
+}
+
 unsigned ScopStmt::getNumIterators() const { return NestLoops.size(); }
 
 const char *ScopStmt::getBaseName() const { return BaseName.c_str(); }
Index: lib/Transform/ForwardOpTree.cpp
===================================================================
--- lib/Transform/ForwardOpTree.cpp
+++ lib/Transform/ForwardOpTree.cpp
@@ -767,10 +767,6 @@
   /// to forward them into the statement.
   bool forwardOperandTrees() {
     for (ScopStmt &Stmt : *S) {
-      // Currently we cannot modify the instruction list of region statements.
-      if (!Stmt.isBlockStmt())
-        continue;
-
       bool StmtModified = false;
 
       // Because we are modifying the MemoryAccess list, collect them first to
Index: lib/Transform/ZoneAlgo.cpp
===================================================================
--- lib/Transform/ZoneAlgo.cpp
+++ lib/Transform/ZoneAlgo.cpp
@@ -376,7 +376,7 @@
 
     // In region statements the order is less clear, eg. the load and store
     // might be in a boxed loop.
-    if (Stmt->isRegionStmt() &&
+    if (Stmt->hasBoxedLoops() &&
         !isl_union_map_is_disjoint(Loads.keep(), AccRel.keep())) {
       DEBUG(dbgs() << "WRITE in non-affine subregion not supported\n");
       OptimizationRemarkMissed R(PassName, "StoreInSubregion",
Index: test/DeLICM/reject_storeinsubregion.ll
===================================================================
--- test/DeLICM/reject_storeinsubregion.ll
+++ test/DeLICM/reject_storeinsubregion.ll
@@ -75,5 +75,11 @@
   ret void
 }
 
-
-; CHECK: store is in a non-affine subregion
+; CHECK:      DeLICM result:
+; CHECK-NEXT: Statistics {
+; CHECK-NEXT:     Compatible overwrites: 1
+; CHECK-NEXT:     Overwrites mapped to:  0
+; CHECK-NEXT:     Value scalars mapped:  0
+; CHECK-NEXT:     PHI scalars mapped:    0
+; CHECK-NEXT: }
+; CHECK-NEXT: No modification has been made
Index: test/ForwardOpTree/forward_region.ll
===================================================================
--- /dev/null
+++ test/ForwardOpTree/forward_region.ll
@@ -0,0 +1,71 @@
+; RUN: opt %loadPolly -polly-optree -analyze < %s | FileCheck %s -match-full-lines
+;
+; Move instructions to region statements.
+;
+; for (int j = 0; j < n; j += 1) {
+; bodyA:
+;   double val = 21.0 + 21.0;
+;
+; bodyB_entry:
+;   if (undef)
+; body_true:
+;     A[0] = val;
+; }
+;
+define void @func(i32 %n, double* noalias nonnull %A) {
+entry:
+  br label %for
+
+for:
+  %j = phi i32 [0, %entry], [%j.inc, %inc]
+  %j.cmp = icmp slt i32 %j, %n
+  br i1 %j.cmp, label %bodyA, label %exit
+
+    bodyA:
+      %val = fadd double 21.0, 21.0
+      br label %bodyB
+
+    bodyB:
+      %cond = fcmp oeq double 21.0, 21.0
+      br i1 %cond, label %bodyB_true, label %bodyB_exit
+
+    bodyB_true:
+      store double %val, double* %A
+      br label %bodyB_exit
+
+    bodyB_exit:
+      br label %inc
+
+inc:
+  %j.inc = add nuw nsw i32 %j, 1
+  br label %for
+
+exit:
+  br label %return
+
+return:
+  ret void
+}
+
+; CHECK: Statistics {
+; CHECK-NEXT:     Instructions copied: 1
+; CHECK-NEXT:     Known loads forwarded: 0
+; CHECK-NEXT:     Read-only accesses copied: 0
+; CHECK-NEXT:     Operand trees forwarded: 1
+; CHECK-NEXT:     Statements with forwarded operand trees: 1
+; CHECK-NEXT: }
+; CHECK-NEXT: After statements {
+; CHECK-NEXT:     Stmt_bodyA
+; CHECK-NEXT:             MustWriteAccess :=	[Reduction Type: NONE] [Scalar: 1]
+; CHECK-NEXT:                 [n] -> { Stmt_bodyA[i0] -> MemRef_val[] };
+; CHECK-NEXT:             Instructions {
+; CHECK-NEXT:                   %val = fadd double 2.100000e+01, 2.100000e+01
+; CHECK-NEXT:             }
+; CHECK-NEXT:     Stmt_bodyB__TO__bodyB_exit
+; CHECK-NEXT:             MayWriteAccess :=	[Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:                 [n] -> { Stmt_bodyB__TO__bodyB_exit[i0] -> MemRef_A[0] };
+; CHECK-NEXT:             Instructions {
+; CHECK-NEXT:                   %val = fadd double 2.100000e+01, 2.100000e+01
+; CHECK-NEXT:                   %cond = fcmp oeq double 2.100000e+01, 2.100000e+01
+; CHECK-NEXT:             }
+; CHECK-NEXT: }
Index: test/ForwardOpTree/noforward_region.ll
===================================================================
--- test/ForwardOpTree/noforward_region.ll
+++ /dev/null
@@ -1,51 +0,0 @@
-; RUN: opt %loadPolly -polly-optree -analyze < %s | FileCheck %s -match-full-lines
-;
-; Do not move instructions to region statements.
-;
-; for (int j = 0; j < n; j += 1) {
-; bodyA:
-;   double val = 21.0 + 21.0;
-;
-; bodyB_entry:
-;   if (undef)
-; body_true:
-;     A[0] = val;
-; }
-;
-define void @func(i32 %n, double* noalias nonnull %A) {
-entry:
-  br label %for
-
-for:
-  %j = phi i32 [0, %entry], [%j.inc, %inc]
-  %j.cmp = icmp slt i32 %j, %n
-  br i1 %j.cmp, label %bodyA, label %exit
-
-    bodyA:
-      %val = fadd double 21.0, 21.0
-      br label %bodyB
-
-    bodyB:
-      %cond = fcmp oeq double 21.0, 21.0
-      br i1 %cond, label %bodyB_true, label %bodyB_exit
-
-    bodyB_true:
-      store double %val, double* %A
-      br label %bodyB_exit
-
-    bodyB_exit:
-      br label %inc
-
-inc:
-  %j.inc = add nuw nsw i32 %j, 1
-  br label %for
-
-exit:
-  br label %return
-
-return:
-  ret void
-}
-
-
-; CHECK: ForwardOpTree executed, but did not modify anything