diff --git a/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td b/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
--- a/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
+++ b/mlir/include/mlir/Dialect/Shape/IR/ShapeOps.td
@@ -155,7 +155,9 @@
   let hasFolder = 1;
 }
 
-def Shape_FromExtentTensorOp : Shape_Op<"from_extent_tensor", []> {
+def Shape_FromExtentTensorOp : Shape_Op<"from_extent_tensor", [
+    NoSideEffect,
+    DeclareOpInterfaceMethods<InferTypeOpInterface>]> {
   let summary = "Creates a shape from a tensor of extents";
   let description = [{
     Creates a shape from a 1D integral tensor of extents. The rank of the
@@ -165,26 +167,25 @@
 
   let arguments = (ins IndexTensor:$input);
   let results = (outs Shape_ShapeType:$result);
+
+  let assemblyFormat = "attr-dict $input `:` type($input)";
 }
 
-def Shape_ToExtentTensorOp : Shape_Op<"to_extent_tensor", []> {
+def Shape_ToExtentTensorOp : Shape_Op<"to_extent_tensor", [NoSideEffect]> {
   let summary = "Creates a dimension tensor from a shape";
-  // TODO: Think more about the error situation. Perhaps factor out the
-  // error detection into a separate op so downstream consumers can control
-  // their error behavior. Then this op would assume that the input has
-  // been properly checked to not be an error (and could thus be a
-  // NoSideEffect op).
   let description = [{
     Converts a shape to a 1D integral tensor of extents. The number of elements
     in the tensor equals the rank of the shape, and the elements equal the
     extents of the shape.
 
-    If the shape represents an error, then this op currently aborts the program.
+    If the shape represents an error, this op's behavior is undefined.
   }];
 
   let arguments = (ins Shape_ShapeType:$input);
   let results = (outs IndexTensor:$result);
 
+  let assemblyFormat = "attr-dict $input `:` type($result)";
+
   let hasFolder = 1;
 }
 
diff --git a/mlir/lib/Dialect/Shape/IR/Shape.cpp b/mlir/lib/Dialect/Shape/IR/Shape.cpp
--- a/mlir/lib/Dialect/Shape/IR/Shape.cpp
+++ b/mlir/lib/Dialect/Shape/IR/Shape.cpp
@@ -290,14 +290,6 @@
 // FromExtentsOp
 //===----------------------------------------------------------------------===//
 
-LogicalResult FromExtentsOp::inferReturnTypes(
-    MLIRContext *context, Optional<Location> location, ValueRange operands,
-    DictionaryAttr attributes, RegionRange regions,
-    SmallVectorImpl<Type> &inferredReturnTypes) {
-  inferredReturnTypes.push_back(ShapeType::get(context));
-  return success();
-}
-
 OpFoldResult FromExtentsOp::fold(ArrayRef<Attribute> operands) {
   if (llvm::any_of(operands, [](Attribute a) { return !a; }))
     return nullptr;
@@ -308,6 +300,14 @@
   return builder.getIndexTensorAttr(extents);
 }
 
+LogicalResult FromExtentsOp::inferReturnTypes(
+    MLIRContext *context, Optional<Location> location, ValueRange operands,
+    DictionaryAttr attributes, RegionRange regions,
+    SmallVectorImpl<Type> &inferredReturnTypes) {
+  inferredReturnTypes.push_back(ShapeType::get(context));
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // GetExtentOp
 //===----------------------------------------------------------------------===//
@@ -332,6 +332,18 @@
   return elements.getValue({dimToGet});
 }
 
+//===----------------------------------------------------------------------===//
+// FromExtentTensorOp
+//===----------------------------------------------------------------------===//
+
+LogicalResult FromExtentTensorOp::inferReturnTypes(
+    MLIRContext *context, Optional<Location> location, ValueRange operands,
+    DictionaryAttr attributes, RegionRange regions,
+    SmallVectorImpl<Type> &inferredReturnTypes) {
+  inferredReturnTypes.push_back(ShapeType::get(context));
+  return success();
+}
+
 //===----------------------------------------------------------------------===//
 // NumElementsOp
 //===----------------------------------------------------------------------===//
diff --git a/mlir/test/Dialect/Shape/canonicalize.mlir b/mlir/test/Dialect/Shape/canonicalize.mlir
--- a/mlir/test/Dialect/Shape/canonicalize.mlir
+++ b/mlir/test/Dialect/Shape/canonicalize.mlir
@@ -83,7 +83,7 @@
 func @f() -> tensor<2xindex> {
   // CHECK: constant dense<[0, 1]> : tensor<2xindex>
   %cs = shape.const_shape [0, 1]
-  %0 = "shape.to_extent_tensor"(%cs) : (!shape.shape) -> tensor<2xindex>
+  %0 = shape.to_extent_tensor %cs : tensor<2xindex>
   return %0 : tensor<2xindex>
 }
 
diff --git a/mlir/test/Dialect/Shape/ops.mlir b/mlir/test/Dialect/Shape/ops.mlir
--- a/mlir/test/Dialect/Shape/ops.mlir
+++ b/mlir/test/Dialect/Shape/ops.mlir
@@ -80,3 +80,14 @@
   }
   return
 }
+
+func @test_to_extent_tensor(%arg: !shape.shape) -> tensor<3xindex> {
+  %0 = shape.to_extent_tensor %arg : tensor<3xindex>
+  return %0 : tensor<3xindex>
+}
+
+func @test_from_extent_tensor(%arg: tensor<?xindex>) -> !shape.shape {
+  %0 = shape.from_extent_tensor %arg : tensor<?xindex>
+  return %0 : !shape.shape
+}
+