diff --git a/mlir/include/mlir/IR/BuiltinAttributes.h b/mlir/include/mlir/IR/BuiltinAttributes.h
--- a/mlir/include/mlir/IR/BuiltinAttributes.h
+++ b/mlir/include/mlir/IR/BuiltinAttributes.h
@@ -560,6 +560,11 @@
   /// same total number of elements as well as element type.
   DenseElementsAttr reshape(ShapedType newType);
 
+  /// Return a new DenseElementsAttr that has the same data as the current
+  /// attribute, but has bitcast elements to 'newElType'. The new type must have
+  /// the same bitwidth as the current element type.
+  DenseElementsAttr bitcast(Type newElType);
+
   /// Generates a new DenseElementsAttr by mapping each int value to a new
   /// underlying APInt. The new values can represent either an integer or float.
   /// This underlying type must be an DenseIntElementsAttr.
diff --git a/mlir/lib/Dialect/StandardOps/IR/Ops.cpp b/mlir/lib/Dialect/StandardOps/IR/Ops.cpp
--- a/mlir/lib/Dialect/StandardOps/IR/Ops.cpp
+++ b/mlir/lib/Dialect/StandardOps/IR/Ops.cpp
@@ -512,16 +512,8 @@
 
   Type resType = getResult().getType();
 
-  if (auto denseAttr = operand.dyn_cast<DenseFPElementsAttr>()) {
-    Type elType = getElementTypeOrSelf(resType);
-    return denseAttr.mapValues(
-        elType, [](const APFloat &f) { return f.bitcastToAPInt(); });
-  }
-  if (auto denseAttr = operand.dyn_cast<DenseIntElementsAttr>()) {
-    Type elType = getElementTypeOrSelf(resType);
-    // mapValues does its own bitcast to the target type.
-    return denseAttr.mapValues(elType, [](const APInt &i) { return i; });
-  }
+  if (auto denseAttr = operand.dyn_cast<DenseElementsAttr>())
+    return denseAttr.bitcast(resType.cast<ShapedType>().getElementType());
 
   APInt bits;
   if (auto floatAttr = operand.dyn_cast<FloatAttr>())
diff --git a/mlir/lib/IR/BuiltinAttributes.cpp b/mlir/lib/IR/BuiltinAttributes.cpp
--- a/mlir/lib/IR/BuiltinAttributes.cpp
+++ b/mlir/lib/IR/BuiltinAttributes.cpp
@@ -1025,6 +1025,7 @@
     return *this;
 
   (void)curType;
+  assert(newType.getElementType() && "excepted integer or float element type");
   assert(newType.getElementType() == curType.getElementType() &&
          "expected the same element type");
   assert(newType.getNumElements() == curType.getNumElements() &&
@@ -1032,6 +1033,25 @@
   return DenseIntOrFPElementsAttr::getRaw(newType, getRawData(), isSplat());
 }
 
+/// Return a new DenseElementsAttr that has the same data as the current
+/// attribute, but has bitcast elements such that it is now 'newType'. The new
+/// type must have the same shape and element types of the same bitwidth as the
+/// current type.
+DenseElementsAttr DenseElementsAttr::bitcast(Type newElType) {
+  ShapedType curType = getType();
+  Type curElType = curType.getElementType();
+  if (curElType == newElType)
+    return *this;
+
+  (void)curElType;
+  assert(newElType.isIntOrFloat() && "excepted integer or float element type");
+  assert(newElType.getIntOrFloatBitWidth() ==
+             curElType.getIntOrFloatBitWidth() &&
+         "expected element types with the same bitwidth");
+  return DenseIntOrFPElementsAttr::getRaw(curType.clone(newElType),
+                                          getRawData(), isSplat());
+}
+
 DenseElementsAttr
 DenseElementsAttr::mapValues(Type newElementType,
                              function_ref<APInt(const APInt &)> mapping) const {
diff --git a/mlir/lib/IR/BuiltinTypes.cpp b/mlir/lib/IR/BuiltinTypes.cpp
--- a/mlir/lib/IR/BuiltinTypes.cpp
+++ b/mlir/lib/IR/BuiltinTypes.cpp
@@ -445,10 +445,14 @@
     return emitError() << "vector types must have at least one dimension";
 
   if (!isValidElementType(elementType))
-    return emitError() << "vector elements must be int/index/float type";
+    return emitError()
+           << "vector elements must be int/index/float type but got "
+           << elementType;
 
   if (any_of(shape, [](int64_t i) { return i <= 0; }))
-    return emitError() << "vector types must have positive constant sizes";
+    return emitError()
+           << "vector types must have positive constant sizes but got "
+           << llvm::to_vector<4>(shape);
 
   return success();
 }