Index: lib/CodeGen/IslExprBuilder.cpp
===================================================================
--- lib/CodeGen/IslExprBuilder.cpp
+++ lib/CodeGen/IslExprBuilder.cpp
@@ -130,7 +130,8 @@
   }
 
   Indices.push_back(IndexOp);
-  assert((PtrElTy->isIntOrIntVectorTy() || PtrElTy->isFPOrFPVectorTy()) &&
+  assert((PtrElTy->isIntOrIntVectorTy() || PtrElTy->isFPOrFPVectorTy() ||
+          PtrElTy->isPtrOrPtrVectorTy()) &&
          "We do not yet change the type of the access base during code "
          "generation.");
 
@@ -274,15 +275,23 @@
   assert((!IsPtrType || RHS->getType()->isPointerTy()) &&
          "Both ICmp operators should be pointer types or none of them");
 
-  if (!IsPtrType) {
-    Type *MaxType = LHS->getType();
-    MaxType = getWidestType(MaxType, RHS->getType());
-
-    if (MaxType != RHS->getType())
-      RHS = Builder.CreateSExt(RHS, MaxType);
-
-    if (MaxType != LHS->getType())
-      LHS = Builder.CreateSExt(LHS, MaxType);
+  if (LHS->getType() != RHS->getType()) {
+    if (IsPtrType) {
+      Type *I8PtrTy = Builder.getInt8PtrTy();
+      if (LHS->getType() != I8PtrTy)
+        LHS = Builder.CreateBitCast(LHS, I8PtrTy);
+      if (RHS->getType() != I8PtrTy)
+        RHS = Builder.CreateBitCast(RHS, I8PtrTy);
+    } else {
+      Type *MaxType = LHS->getType();
+      MaxType = getWidestType(MaxType, RHS->getType());
+
+      if (MaxType != RHS->getType())
+        RHS = Builder.CreateSExt(RHS, MaxType);
+
+      if (MaxType != LHS->getType())
+        LHS = Builder.CreateSExt(LHS, MaxType);
+    }
   }
 
   isl_ast_op_type OpType = isl_ast_expr_get_op_type(Expr);
Index: test/Isl/CodeGen/aliasing_different_pointer_types.ll
===================================================================
--- /dev/null
+++ test/Isl/CodeGen/aliasing_different_pointer_types.ll
@@ -0,0 +1,51 @@
+; RUN: opt %loadPolly -polly-code-generator=isl -polly-codegen-isl -S < %s | FileCheck %s
+;
+; Check that we cast the different pointer types correctly before we compare
+; them in the RTC's.
+;
+; CHECK: entry:
+; CHECK:   %polly.access.B = getelementptr float** %B, i64 1024
+; CHECK:   %polly.access.A = getelementptr double** %A, i64 0
+; CHECK:   %[[paBb:[._a-zA-Z0-9]]] = bitcast float** %polly.access.B to i8*
+; CHECK:   %[[paAb:[._a-zA-Z0-9]]] = bitcast double** %polly.access.A to i8*
+; CHECK:   %[[ALeB:[._a-zA-Z0-9]]] = icmp ule i8* %[[paBb]], %[[paAb]]
+; CHECK:   %polly.access.A1 = getelementptr double** %A, i64 1024
+; CHECK:   %polly.access.B2 = getelementptr float** %B, i64 0
+; CHECK:   %[[paA1b:[._a-zA-Z0-9]]] = bitcast double** %polly.access.A1 to i8*
+; CHECK:   %[[paB2b:[._a-zA-Z0-9]]] = bitcast float** %polly.access.B2 to i8*
+; CHECK:   %[[A1LeB2:[._a-zA-Z0-9]]] = icmp ule i8* %[[paA1b]], %[[paB2b]]
+; CHECK:   %[[le1OrLe2:[._a-zA-Z0-9]]] = or i1 %[[ALeB]], %[[A1LeB2]]
+; CHECK:   %[[orAndTrue:[._a-zA-Z0-9]]] = and i1 true, %[[le1OrLe2]]
+; CHECK:   br label %polly.split_new_and_old
+;
+;    void jd(double **A, float **B) {
+;      for (int i = 0; i < 1024; i++)
+;        A[i] = (double *)B[i];
+;    }
+;
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+define void @jd(double** %A, float** %B) {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %indvars.iv = phi i64 [ %indvars.iv.next, %for.inc ], [ 0, %entry ]
+  %exitcond = icmp ne i64 %indvars.iv, 1024
+  br i1 %exitcond, label %for.body, label %for.end
+
+for.body:                                         ; preds = %for.cond
+  %arrayidx = getelementptr inbounds float** %B, i64 %indvars.iv
+  %tmp = load float** %arrayidx, align 8
+  %tmp1 = bitcast float* %tmp to double*
+  %arrayidx2 = getelementptr inbounds double** %A, i64 %indvars.iv
+  store double* %tmp1, double** %arrayidx2, align 8
+  br label %for.inc
+
+for.inc:                                          ; preds = %for.body
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  br label %for.cond
+
+for.end:                                          ; preds = %for.cond
+  ret void
+}