Index: lib/Transforms/Scalar/LoopInterchange.cpp
===================================================================
--- lib/Transforms/Scalar/LoopInterchange.cpp
+++ lib/Transforms/Scalar/LoopInterchange.cpp
@@ -958,6 +958,18 @@
     return false;
   }
 
+  // Check if outer and inner loop contain legal instructions only.
+  for (auto *BB : OuterLoop->blocks())
+    for (Instruction &I : *BB)
+      if (CallInst *CI = dyn_cast<CallInst>(&I)) {
+        // readnone functions do not prevent interchanging.
+        if (CI->doesNotReadMemory())
+          continue;
+        DEBUG(dbgs() << "Loops with call instructions cannot be interchanged "
+                     << "safely.");
+        return false;
+      }
+
   // Create unique Preheaders if we already do not have one.
   BasicBlock *OuterLoopPreHeader = OuterLoop->getLoopPreheader();
   BasicBlock *InnerLoopPreHeader = InnerLoop->getLoopPreheader();
Index: test/Transforms/LoopInterchange/call-instructions.ll
===================================================================
--- /dev/null
+++ test/Transforms/LoopInterchange/call-instructions.ll
@@ -0,0 +1,158 @@
+; RUN: opt < %s -basicaa -loop-interchange -S | FileCheck %s
+;; We test the complete .ll for adjustment in outer loop header/latch and inner loop header/latch.
+
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@A = common global [100 x [100 x i32]] zeroinitializer
+
+declare void @foo(i64 %a)
+declare void @bar(i64 %a) readnone
+
+;;--------------------------------------Test case 01------------------------------------
+;; Not safe to interchange, because the called function `foo` is not marked as
+;; readnone, so it could introduce dependences.
+;;
+;;  for(int i=0;i<N;i++) {
+;;    for(int j=1;j<N;j++) {
+;;      foo(i);
+;;      A[j][i] = A[j][i]+k;
+;;    }
+;; }
+
+define void @interchange_01(i32 %k, i32 %N) {
+entry:
+  %cmp21 = icmp sgt i32 %N, 0
+  br i1 %cmp21, label %for1.ph, label %exit
+
+for1.ph:
+  %cmp219 = icmp sgt i32 %N, 1
+  %0 = add i32 %N, -1
+  br label %for1.header
+
+for1.header:
+  %indvars.iv23 = phi i64 [ 0, %for1.ph ], [ %indvars.iv.next24, %for1.inc10 ]
+  br i1 %cmp219, label %for2.ph, label %for1.inc10
+
+for2.ph:
+  br label %for2
+
+for2:
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for2 ], [ 1, %for2.ph ]
+  call void @foo(i64 %indvars.iv23)
+  %arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv23
+  %1 = load i32, i32* %arrayidx5
+  %add = add nsw i32 %1, %k
+  store i32 %add, i32* %arrayidx5
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %0
+  br i1 %exitcond, label %for2.loopexit , label %for2
+
+for2.loopexit:
+  br label %for1.inc10
+
+for1.inc10:
+  %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
+  %lftr.wideiv25 = trunc i64 %indvars.iv23 to i32
+  %exitcond26 = icmp eq i32 %lftr.wideiv25, %0
+  br i1 %exitcond26, label %for1.loopexit, label %for1.header
+
+for1.loopexit:
+  br label %exit
+
+exit:
+  ret void
+}
+
+; CHECK-LABEL: @interchange_01
+; CHECK: for1.ph:
+; CHECK: br label %for1.header
+
+; CHECK: for1.header:
+; CHECK-NEXT: %indvars.iv23 = phi i64 [ 0, %for1.ph ], [ %indvars.iv.next24, %for1.inc10 ]
+; CHECK-NEXT: br i1 %cmp219, label %for2.ph, label %for1.inc10
+
+; CHECK: for2:
+; CHECK: br i1 %exitcond, label %for2.loopexit, label %for2
+
+; CHECK: for1.inc10:
+; CHECK: br i1 %exitcond26, label %for1.loopexit, label %for1.header
+
+; CHECK: for1.loopexit:
+; CHECK-NEXT: br label %exit
+
+
+;;--------------------------------------Test case 02------------------------------------
+;; Safe to interchange, because the called function `bar` is marked as readnone,
+;; so it cannot introduce dependences.
+;;
+;;  for(int i=0;i<N;i++) {
+;;    for(int j=1;j<N;j++) {
+;;      bar(i);
+;;      A[j][i] = A[j][i]+k;
+;;    }
+;; }
+
+define void @interchange_02(i32 %k, i32 %N) {
+entry:
+  %cmp21 = icmp sgt i32 %N, 0
+  br i1 %cmp21, label %for1.ph, label %exit
+
+for1.ph:
+  %cmp219 = icmp sgt i32 %N, 1
+  %0 = add i32 %N, -1
+  br label %for1.header
+
+for1.header:
+  %indvars.iv23 = phi i64 [ 0, %for1.ph ], [ %indvars.iv.next24, %for1.inc10 ]
+  br i1 %cmp219, label %for2.ph, label %for1.inc10
+
+for2.ph:
+  br label %for2
+
+for2:
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for2 ], [ 1, %for2.ph ]
+  call void @bar(i64 %indvars.iv23)
+  %arrayidx5 = getelementptr inbounds [100 x [100 x i32]], [100 x [100 x i32]]* @A, i64 0, i64 %indvars.iv, i64 %indvars.iv23
+  %1 = load i32, i32* %arrayidx5
+  %add = add nsw i32 %1, %k
+  store i32 %add, i32* %arrayidx5
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, %0
+  br i1 %exitcond, label %for2.loopexit , label %for2
+
+for2.loopexit:
+  br label %for1.inc10
+
+for1.inc10:
+  %indvars.iv.next24 = add nuw nsw i64 %indvars.iv23, 1
+  %lftr.wideiv25 = trunc i64 %indvars.iv23 to i32
+  %exitcond26 = icmp eq i32 %lftr.wideiv25, %0
+  br i1 %exitcond26, label %for1.loopexit, label %for1.header
+
+for1.loopexit:
+  br label %exit
+
+exit:
+  ret void
+}
+
+; CHECK-LABEL: @interchange_02
+; CHECK: for1.header:
+; CHECK-NEXT: %indvars.iv23 = phi i64 [ 0, %for1.ph ], [ %indvars.iv.next24, %for1.inc10 ]
+; CHECK-NEXT: br i1 %cmp219, label %for2.split1, label %for1.loopexit
+
+; CHECK: for2.split1:
+; CHECK: br label %for2.loopexit
+
+; CHECK: for2.split:
+; CHECK-NEXT: %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+; CHECK: br i1 %exitcond, label %for1.loopexit, label %for2
+
+; CHECK: for2.loopexit:
+; CHECK-NEXT:  br label %for1.inc10
+
+; CHECK: for1.inc10:
+; CHECK: br i1 %exitcond26, label %for2.split, label %for1.header
Index: test/Transforms/LoopInterchange/interchange-flow-dep-outer.ll
===================================================================
--- test/Transforms/LoopInterchange/interchange-flow-dep-outer.ll
+++ test/Transforms/LoopInterchange/interchange-flow-dep-outer.ll
@@ -65,8 +65,8 @@
   br i1 %exitcond, label %for.body9, label %for.cond.cleanup8
 }
 
-declare double @fn1()
-declare void @fn2(double)
+declare double @fn1() readnone
+declare void @fn2(double) readnone
 
 
 ;; After interchange %indvars.iv (j) should increment as the middle loop.
Index: test/Transforms/LoopInterchange/not-interchanged-tightly-nested.ll
===================================================================
--- test/Transforms/LoopInterchange/not-interchanged-tightly-nested.ll
+++ test/Transforms/LoopInterchange/not-interchanged-tightly-nested.ll
@@ -93,7 +93,7 @@
 ; CHECK: ret void
 
 
-declare void @foo(...)
+declare void @foo(...) readnone
 
 ;; Loops not tightly nested are not interchanged
 ;;  for(int j=0;j<N;j++) {