Index: polly/trunk/lib/Analysis/ScopBuilder.cpp
===================================================================
--- polly/trunk/lib/Analysis/ScopBuilder.cpp
+++ polly/trunk/lib/Analysis/ScopBuilder.cpp
@@ -29,6 +29,17 @@
 STATISTIC(ScopFound, "Number of valid Scops");
 STATISTIC(RichScopFound, "Number of Scops containing a loop");
 
+// If the loop is nonaffine/boxed, return the first non-boxed surrounding loop
+// for Polly. If the loop is affine, return the loop itself. Do not call
+// `getSCEVAtScope()` on the result of `getFirstNonBoxedLoopFor()`, as we need
+// to analyze the memory accesses of the nonaffine/boxed loops.
+static Loop *getFirstNonBoxedLoopFor(Loop *L, LoopInfo &LI,
+                                     const BoxedLoopsSetTy &BoxedLoops) {
+  while (BoxedLoops.count(L))
+    L = L->getParentLoop();
+  return L;
+}
+
 static cl::opt<bool> ModelReadOnlyScalars(
     "polly-analyze-read-only-scalars",
     cl::desc("Model read-only scalar values in the scop description"),
@@ -150,9 +161,12 @@
   std::vector<const SCEV *> SizesSCEV;
 
   const InvariantLoadsSetTy &ScopRIL = scop->getRequiredInvariantLoads();
+
+  Loop *SurroundingLoop = getFirstNonBoxedLoopFor(L, LI, scop->getBoxedLoops());
   for (auto *Subscript : Subscripts) {
     InvariantLoadsSetTy AccessILS;
-    if (!isAffineExpr(&scop->getRegion(), L, Subscript, SE, &AccessILS))
+    if (!isAffineExpr(&scop->getRegion(), SurroundingLoop, Subscript, SE,
+                      &AccessILS))
       return false;
 
     for (LoadInst *LInst : AccessILS)
@@ -226,8 +240,10 @@
   // Check if the length val is actually affine or if we overapproximate it
   InvariantLoadsSetTy AccessILS;
   const InvariantLoadsSetTy &ScopRIL = scop->getRequiredInvariantLoads();
-  bool LengthIsAffine =
-      isAffineExpr(&scop->getRegion(), L, LengthVal, SE, &AccessILS);
+
+  Loop *SurroundingLoop = getFirstNonBoxedLoopFor(L, LI, scop->getBoxedLoops());
+  bool LengthIsAffine = isAffineExpr(&scop->getRegion(), SurroundingLoop,
+                                     LengthVal, SE, &AccessILS);
   for (LoadInst *LInst : AccessILS)
     if (!ScopRIL.count(LInst))
       LengthIsAffine = false;
@@ -345,9 +361,11 @@
       isVariantInNonAffineLoop = true;
 
   InvariantLoadsSetTy AccessILS;
-  bool IsAffine =
-      !isVariantInNonAffineLoop &&
-      isAffineExpr(&scop->getRegion(), L, AccessFunction, SE, &AccessILS);
+
+  Loop *SurroundingLoop = getFirstNonBoxedLoopFor(L, LI, BoxedLoops);
+  bool IsAffine = !isVariantInNonAffineLoop &&
+                  isAffineExpr(&scop->getRegion(), SurroundingLoop,
+                               AccessFunction, SE, &AccessILS);
 
   const InvariantLoadsSetTy &ScopRIL = scop->getRequiredInvariantLoads();
   for (LoadInst *LInst : AccessILS)
Index: polly/trunk/lib/Analysis/ScopInfo.cpp
===================================================================
--- polly/trunk/lib/Analysis/ScopInfo.cpp
+++ polly/trunk/lib/Analysis/ScopInfo.cpp
@@ -2246,6 +2246,10 @@
   return true;
 }
 
+// If the loop is nonaffine/boxed, return the first non-boxed surrounding loop
+// for Polly. If the loop is affine, return the loop itself. Do not call
+// `getSCEVAtScope()` on the result of `getFirstNonBoxedLoopFor()`, as we need
+// to analyze the memory accesses of the nonaffine/boxed loops.
 static Loop *getFirstNonBoxedLoopFor(BasicBlock *BB, LoopInfo &LI,
                                      const BoxedLoopsSetTy &BoxedLoops) {
   auto *L = LI.getLoopFor(BB);
Index: polly/trunk/lib/Support/SCEVValidator.cpp
===================================================================
--- polly/trunk/lib/Support/SCEVValidator.cpp
+++ polly/trunk/lib/Support/SCEVValidator.cpp
@@ -214,8 +214,9 @@
 
     auto *L = Expr->getLoop();
     if (R->contains(L) && (!Scope || !L->contains(Scope))) {
-      DEBUG(dbgs() << "INVALID: AddRec out of a loop whose exit value is not "
-                      "synthesizable");
+      DEBUG(dbgs() << "INVALID: Loop of AddRec expression boxed in an a "
+                      "non-affine subregion or has a non-synthesizable exit "
+                      "value.");
       return ValidatorResult(SCEVType::INVALID);
     }
 
Index: polly/trunk/test/DependenceInfo/nonaffine-condition-buildMemoryAccess.ll
===================================================================
--- polly/trunk/test/DependenceInfo/nonaffine-condition-buildMemoryAccess.ll
+++ polly/trunk/test/DependenceInfo/nonaffine-condition-buildMemoryAccess.ll
@@ -0,0 +1,74 @@
+; RUN: opt %loadPolly -polly-codegen -polly-allow-nonaffine-loops -polly-allow-nonaffine -debug-only=polly-dependence < %s 2>&1 | FileCheck %s 
+; REQUIRES: asserts
+
+; CHECK:        MayWriteAccess :=   [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:       { Stmt_for_body__TO__for_inc11[i0] -> MemRef_A[o0] : 0 <= o0 <= 699 };
+; CHECK-NEXT:   MayWriteAccess :=   [Reduction Type: NONE] [Scalar: 0]
+; CHECK-NEXT:       { Stmt_for_body__TO__for_inc11[i0] -> MemRef_B[700] };
+
+; The if condition C[i] is a non-affine condition, which make the nested loop boxed. The memory access for A should be a range A[0...699]. The memory access for B should be simplified to B[700].
+;
+; int A[1000], B[1000], C[1000];
+;
+; void foo(int n, int m, int N) {
+;   for (int i = 0; i < 500; i+=1) { /* affine loop */
+;      C[i] += i;
+;      if (C[i]) { /* non-affine subregion */
+;          int j;
+;          for (j = 0; j < 700; j+=1) { /* boxed loop */
+;            A[j] = 1;
+;          }
+;          B[j] = 2;
+;      }
+;    }
+; }
+
+
+target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
+
+@C = common global [1000 x i32] zeroinitializer, align 4
+@A = common global [1000 x i32] zeroinitializer, align 4
+@B = common global [1000 x i32] zeroinitializer, align 4
+
+; Function Attrs: norecurse nounwind
+define void @foo(i32 %n, i32 %m, i32 %N) #0 {
+entry:
+  br label %entry.split
+
+entry.split:                                      ; preds = %entry
+  br label %for.body
+
+for.cond.cleanup:                                 ; preds = %for.inc11
+  ret void
+
+for.body:                                         ; preds = %for.inc11, %entry.split
+  %indvars.iv25 = phi i64 [ 0, %entry.split ], [ %indvars.iv.next26, %for.inc11 ]
+  %arrayidx = getelementptr inbounds [1000 x i32], [1000 x i32]* @C, i64 0, i64 %indvars.iv25
+  %0 = load i32, i32* %arrayidx, align 4
+  %1 = trunc i64 %indvars.iv25 to i32
+  %add = add nsw i32 %0, %1
+  store i32 %add, i32* %arrayidx, align 4
+  %tobool = icmp eq i32 %add, 0
+  br i1 %tobool, label %for.inc11, label %for.body5.preheader
+
+for.body5.preheader:                              ; preds = %for.body
+  br label %for.body5
+
+for.body5:                                        ; preds = %for.body5.preheader, %for.body5
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.body5 ], [ 0, %for.body5.preheader ]
+  %arrayidx7 = getelementptr inbounds [1000 x i32], [1000 x i32]* @A, i64 0, i64 %indvars.iv
+  store i32 1, i32* %arrayidx7, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv, 699
+  br i1 %exitcond, label %for.end, label %for.body5
+
+for.end:                                          ; preds = %for.body5
+  store i32 2, i32* getelementptr inbounds ([1000 x i32], [1000 x i32]* @B, i64 0, i64 700), align 4
+  br label %for.inc11
+
+for.inc11:                                        ; preds = %for.body, %for.end
+  %indvars.iv.next26 = add nuw nsw i64 %indvars.iv25, 1
+  %exitcond27 = icmp eq i64 %indvars.iv25, 499
+  br i1 %exitcond27, label %for.cond.cleanup, label %for.body
+}
+
Index: polly/trunk/test/ScopInfo/nonaffine-buildMemoryAccess.ll
===================================================================
--- polly/trunk/test/ScopInfo/nonaffine-buildMemoryAccess.ll
+++ polly/trunk/test/ScopInfo/nonaffine-buildMemoryAccess.ll
@@ -0,0 +1,45 @@
+; RUN: opt %loadPolly -polly-allow-nonaffine-loops -polly-scops -analyze < %s | FileCheck %s
+;
+; CHECK:      Domain :=
+; CHECK-NEXT:   { Stmt_while_cond_i__TO__while_end_i[] };
+;
+define i32 @func(i32 %param0, i32 %param1, i64* %param2) #3 {
+
+entry:
+  %var0 = alloca i32
+  %var1 = alloca i32
+  br label %while.cond.i
+
+while.cond.i:                                     ; preds = %while.cond.i.backedge, %entry
+  %var2 = phi i32 [ %param0, %entry ], [ %var3, %while.cond.i.backedge ]
+  %var3 = add nsw i32 %var2, 1
+  %var4 = icmp slt i32 %var2, -1
+  br i1 %var4, label %while.cond.i.backedge, label %if.end.i1.i
+
+if.end.i1.i:                                    ; preds = %while.cond.i
+  %var5 = sdiv i32 %var3, 64
+  %var6 = icmp sgt i32 %param1, %var5
+  br i1 %var6, label %exit1.i, label %while.cond.i.backedge
+
+exit1.i:                          ; preds = %if.end.i1.i
+  %var7 = srem i32 %var3, 64
+  %var8 = sext i32 %var5 to i64
+  %var9 = getelementptr inbounds i64, i64* %param2, i64 %var8
+  %var10 = load i64, i64* %var9, align 8
+  %var11 = zext i32 %var7 to i64
+  %var12 = shl i64 1, %var11
+  %var13 = and i64 %var10, %var12
+  %var14 = icmp eq i64 %var13, 0
+  store i32 %var2, i32* %var1
+  store i32 %var3, i32* %var0
+  br i1 %var14, label %while.cond.i.backedge, label %while.end.i
+
+while.cond.i.backedge:                            ; preds = %exit1.i, %while.cond.i, %if.end.i1.i
+  br label %while.cond.i
+
+while.end.i:
+  %var15 = load i32, i32* %var0
+  %var16 = load i32, i32* %var1
+  %var17 = add i32 %var15, %var16
+  ret i32 %var17
+}