diff --git a/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp b/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
--- a/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
+++ b/mlir/lib/Dialect/MemRef/IR/MemRefOps.cpp
@@ -119,8 +119,9 @@
   if (!memRefType.getAffineMaps().empty())
     numSymbols = memRefType.getAffineMaps().front().getNumSymbols();
   if (op.symbolOperands().size() != numSymbols)
-    return op.emitOpError(
-        "symbol operand count does not equal memref symbol count");
+    return op.emitOpError("symbol operand count does not equal memref symbol "
+                          "count: expected ")
+           << numSymbols << ", got " << op.symbolOperands().size();
 
   return success();
 }
@@ -146,7 +147,7 @@
                                 PatternRewriter &rewriter) const override {
     // Check to see if any dimensions operands are constants.  If so, we can
     // substitute and drop them.
-    if (llvm::none_of(alloc.getOperands(), [](Value operand) {
+    if (llvm::none_of(alloc.dynamicSizes(), [](Value operand) {
           return matchPattern(operand, matchConstantIndex());
         }))
       return failure();
@@ -167,7 +168,7 @@
         newShapeConstants.push_back(dimSize);
         continue;
       }
-      auto *defOp = alloc.getOperand(dynamicDimPos).getDefiningOp();
+      auto *defOp = alloc.dynamicSizes()[dynamicDimPos].getDefiningOp();
       if (auto constantIndexOp = dyn_cast_or_null<ConstantIndexOp>(defOp)) {
         // Dynamic shape dimension will be folded.
         newShapeConstants.push_back(constantIndexOp.getValue());
@@ -187,7 +188,8 @@
 
     // Create and insert the alloc op for the new memref.
     auto newAlloc = rewriter.create<AllocLikeOp>(
-        alloc.getLoc(), newMemRefType, newOperands, alloc.alignmentAttr());
+        alloc.getLoc(), newMemRefType, newOperands, alloc.symbolOperands(),
+        alloc.alignmentAttr());
     // Insert a cast so we have the same type as the old alloc.
     auto resultCast =
         rewriter.create<CastOp>(alloc.getLoc(), newAlloc, alloc.getType());
diff --git a/mlir/test/Dialect/MemRef/canonicalize.mlir b/mlir/test/Dialect/MemRef/canonicalize.mlir
--- a/mlir/test/Dialect/MemRef/canonicalize.mlir
+++ b/mlir/test/Dialect/MemRef/canonicalize.mlir
@@ -217,3 +217,41 @@
   return
 }
 
+// -----
+
+// CHECK-LABEL: func @simplify_alloc(
+//  CHECK: %[[mem1:.+]] = memref.alloc() : memref<1xi32>
+//  CHECK: %[[mem2:.+]] = memref.cast %[[mem1]] : memref<1xi32> to memref<?xi32>
+//  CHECK: return %[[mem2]] : memref<?xi32>
+func @simplify_alloc() -> memref<?xi32> {
+  %c1 = constant 1 : index
+  %0 = memref.alloc(%c1) : memref<?xi32>
+  return %0 : memref<?xi32>
+}
+
+// -----
+
+// CHECK-LABEL: func @simplify_alloc_ignore_symbols1(
+//  CHECK: %[[c1:.+]] = constant 1 : index
+//  CHECK: %[[mem1:.+]] = memref.alloc({{.*}})[%[[c1]], %[[c1]]] : memref<?xi32, #map>
+//  CHECK: return %[[mem1]] : memref<?xi32, #map>
+#map0 = affine_map<(d0)[s0, s1] -> (d0 * s1 + s0)>
+func @simplify_alloc_ignore_symbols1(%arg0 : index) -> memref<?xi32, #map0> {
+  %c1 = constant 1 : index
+  %0 = memref.alloc(%arg0)[%c1, %c1] : memref<?xi32, #map0>
+  return %0 : memref<?xi32, #map0>
+}
+
+// -----
+
+// CHECK-LABEL: func @simplify_alloc_ignore_symbols2(
+//  CHECK: %[[c1:.+]] = constant 1 : index
+//  CHECK: %[[mem1:.+]] = memref.alloc()[%[[c1]], %[[c1]]] : memref<1xi32, #map>
+//  CHECK: %[[mem2:.+]] = memref.cast %[[mem1]] : memref<1xi32, #map> to memref<?xi32, #map>
+//  CHECK: return %[[mem2]] : memref<?xi32, #map>
+#map0 = affine_map<(d0)[s0, s1] -> (d0 * s1 + s0)>
+func @simplify_alloc_ignore_symbols2() -> memref<?xi32, #map0> {
+  %c1 = constant 1 : index
+  %0 = memref.alloc(%c1)[%c1, %c1] : memref<?xi32, #map0>
+  return %0 : memref<?xi32, #map0>
+}