diff --git a/frontend/Interfaces/buddy/DAP/DSP/WhisperPreprocess.h b/frontend/Interfaces/buddy/DAP/DSP/WhisperPreprocess.h
index a642243e7..cf997f518 100644
--- a/frontend/Interfaces/buddy/DAP/DSP/WhisperPreprocess.h
+++ b/frontend/Interfaces/buddy/DAP/DSP/WhisperPreprocess.h
@@ -29,15 +29,24 @@ namespace dap {
 namespace detail {
 // Declare the whisper preprocess C interface.
 extern "C" {
-void _mlir_ciface_buddy_whisperPreprocess(MemRef<double, 1> *inputRawSpeech,
-                                          MemRef<float, 3> *outputFeatures);
+// The original MLIR function:
+//    ```mlir
+//    func.func @buddy_whisperPreprocess(%in : memref<?xf64>) ->
+//        memref<1x80x3000xf32>
+//    ```
+//
+// After applying the '-llvm-request-c-wrappers' pass:
+//    The result of the function (memref<1x80x3000xf32>) is modified to be the
+//    first operand of the function.
+void _mlir_ciface_buddy_whisperPreprocess(MemRef<float, 3> *outputFeatures,
+                                          MemRef<double, 1> *inputRawSpeech);
 }
 } // namespace detail
 
 // Function for Whisper preprocess
 void whisperPreprocess(MemRef<double, 1> *inputRawSpeech,
                        MemRef<float, 3> *outputFeatures) {
-  detail::_mlir_ciface_buddy_whisperPreprocess(inputRawSpeech, outputFeatures);
+  detail::_mlir_ciface_buddy_whisperPreprocess(outputFeatures, inputRawSpeech);
 }
 
 } // namespace dap
diff --git a/frontend/Interfaces/lib/DAP-extend.mlir b/frontend/Interfaces/lib/DAP-extend.mlir
index 8a8455f50..c77fe3873 100644
--- a/frontend/Interfaces/lib/DAP-extend.mlir
+++ b/frontend/Interfaces/lib/DAP-extend.mlir
@@ -1,4 +1,4 @@
-func.func @buddy_whisperPreprocess(%in : memref<?xf64>, %out : memref<1x80x3000xf32>) -> () {
-  dap.whisper_preprocess %in, %out : memref<?xf64>, memref<1x80x3000xf32>
-  return
+func.func @buddy_whisperPreprocess(%in : memref<?xf64>) -> memref<1x80x3000xf32> {
+  %out = dap.whisper_preprocess %in : memref<?xf64> to memref<1x80x3000xf32>
+  return %out : memref<1x80x3000xf32>
 }
diff --git a/midend/include/Dialect/DAP/DAPOps.td b/midend/include/Dialect/DAP/DAPOps.td
index 98bac167d..0855fdaad 100644
--- a/midend/include/Dialect/DAP/DAPOps.td
+++ b/midend/include/Dialect/DAP/DAPOps.td
@@ -50,8 +50,7 @@ def DAP_FirOp : DAP_Op<"fir"> {
   }];
 }
 
-def DAP_BiquadOp : DAP_Op<"biquad">
-{
+def DAP_BiquadOp : DAP_Op<"biquad"> {
   let summary = [{Biquad filter, a infinite impulse response (IIR) filter.
 
   ```mlir
@@ -95,22 +94,25 @@ def DAP_IirOp : DAP_Op<"iir"> {
 }
 
 def DAP_WhisperPreprocessOp : DAP_Op<"whisper_preprocess"> {
-  let summary = [{Preprocessor for Whisper model, do features extraction for input audio.
-  Input MemRef stores the raw speech data, Output MemRef contains computed features with 
-  shape memref<1x80x3000xf32>.
+  let summary = "preprocessor for Whisper model";
+  let description = [{
+    Preprocessor for Whisper model, do features extraction for input audio. 
+    Input MemRef stores the raw speech data, Output MemRef contains computed 
+    features with shape memref<1x80x3000xf32>.
 
-  ```mlir
-    dap.whisper_preprocess %input, %output : memref<?xf64>, memref<1x80x3000xf32>
-  ```
+    Example:
+
+    ```mlir
+    %output = dap.whisper_preprocess %input : memref<?xf64> to memref<1x80x3000xf32>
+    ```
   }];
 
   let arguments = (ins Arg<AnyRankedOrUnrankedMemRef, "inputMemref",
-                           [MemRead]>:$memrefI,
-                       Arg<AnyRankedOrUnrankedMemRef, "outputMemref",
-                           [MemRead]>:$memrefO);
-
+                           [MemRead]>:$memrefI);
+  let results = (outs Res<AnyRankedOrUnrankedMemRef, "outputMemref",
+                           [MemAlloc]>:$memrefO);
   let assemblyFormat = [{
-    $memrefI `,` $memrefO attr-dict `:` type($memrefI) `,` type($memrefO) 
+    $memrefI attr-dict `:` type($memrefI) `to` type($memrefO) 
   }];
 }
 
diff --git a/midend/lib/Conversion/ExtendDAP/ExtendDAPPass.cpp b/midend/lib/Conversion/ExtendDAP/ExtendDAPPass.cpp
index 85aad217b..8981ea769 100644
--- a/midend/lib/Conversion/ExtendDAP/ExtendDAPPass.cpp
+++ b/midend/lib/Conversion/ExtendDAP/ExtendDAPPass.cpp
@@ -1283,7 +1283,7 @@ Value spectrogram(PatternRewriter &rewriter, Location loc, Value f0, Value c0,
   RankedTensorType tensorTy0 = RankedTensorType::get({400}, f64Ty);
   MemRefType mTp = MemRefType::get({400}, f64Ty);
 
-  // mulf_trait for linalg generic operation
+  // #mulf_trait for 'linalg.generic' operation
   AffineMap mulFIdMap =
       AffineMap::getMultiDimIdentityMap(1, rewriter.getContext());
   SmallVector<AffineMap> mulFIndexingMaps = {mulFIdMap, mulFIdMap, mulFIdMap};
@@ -1299,7 +1299,7 @@ Value spectrogram(PatternRewriter &rewriter, Location loc, Value f0, Value c0,
         Value buffer =
             rewriter.create<tensor::CastOp>(loc, tensorTy0, buffer400);
 
-        // linalg.generic operation use mulf_trait
+        // 'linalg.generic' operation use #mulf_trait
         auto mulfOp = rewriter.create<linalg::GenericOp>(
             loc, /*resultTensorTypes=*/tensorTy0,
             /*inputs=*/ValueRange{buffer, window},
@@ -1368,14 +1368,14 @@ Value spectrogram(PatternRewriter &rewriter, Location loc, Value f0, Value c0,
       /*outputs=*/ValueRange{melFloor});
   Value spectrogramMax = linalgMaxOp.getResultTensors()[0];
 
-  // log10_trait for linalg generic operation
+  // #log10_trait for 'linalg.generic' operation
   AffineMap log10IdMap =
       AffineMap::getMultiDimIdentityMap(2, rewriter.getContext());
   SmallVector<AffineMap> log10IndexingMaps = {log10IdMap, log10IdMap};
   SmallVector<utils::IteratorType> log10IteratorTypes = {
       utils::IteratorType::parallel, utils::IteratorType::parallel};
 
-  // linalg.generic operation use log10_trait
+  // 'linalg.generic' operation use #log10_trait
   auto log10Op = rewriter.create<linalg::GenericOp>(
       loc, /*resultTensorTypes=*/tensorTy1,
       /*inputs=*/ValueRange{spectrogramMax},
@@ -1402,9 +1402,7 @@ class DAPWhisperPreprocessLowering
                                 PatternRewriter &rewriter) const override {
     auto loc = op->getLoc();
     auto ctx = op->getContext();
-
     Value input = op->getOperand(0);
-    Value output = op->getOperand(1);
 
     Value c0 = rewriter.create<ConstantIndexOp>(loc, 0);
     Value c1 = rewriter.create<ConstantIndexOp>(loc, 1);
@@ -1498,14 +1496,14 @@ class DAPWhisperPreprocessLowering
     Value InputFeaturesF32 =
         rewriter.create<tensor::SplatOp>(loc, resultTy, f0F32);
 
-    // tail_processing_trait for linalg generic operation
+    // #tail_processing_trait for 'linalg.generic' operation
     AffineMap IdMap =
         AffineMap::getMultiDimIdentityMap(2, rewriter.getContext());
     SmallVector<AffineMap> IndexingMaps = {IdMap, IdMap};
     SmallVector<utils::IteratorType> IteratorTypes = {
         utils::IteratorType::parallel, utils::IteratorType::parallel};
 
-    // linalg.generic operation use tail_processing_trait
+    // 'linalg.generic' operation use #tail_processing_trait
     auto tailProcessOp = rewriter.create<linalg::GenericOp>(
         loc, /*resultTensorTypes=*/resultTy,
         /*inputs=*/ValueRange{logSpecMax},
@@ -1538,9 +1536,9 @@ class DAPWhisperPreprocessLowering
     Value resultMemRef = rewriter.create<bufferization::ToMemrefOp>(
         loc, resultMemTp, resultExpand);
 
-    rewriter.create<memref::CopyOp>(loc, resultMemRef, output);
-
-    rewriter.eraseOp(op);
+    // Replace this operation with the generated result. The replaced op is
+    // erased.
+    rewriter.replaceOp(op, resultMemRef);
     return success();
   }
 };
@@ -1570,8 +1568,8 @@ class ExtendDAPPass
   void runOnOperation() override;
 
   void getDependentDialects(DialectRegistry &registry) const override {
-    registry.insert<arith::ArithDialect>();
     registry.insert<affine::AffineDialect>();
+    registry.insert<arith::ArithDialect>();
     registry.insert<bufferization::BufferizationDialect>();
     registry.insert<func::FuncDialect>();
     registry.insert<linalg::LinalgDialect>();
@@ -1590,11 +1588,17 @@ void ExtendDAPPass::runOnOperation() {
   ModuleOp module = getOperation();
 
   ConversionTarget target(*context);
-  target.addLegalDialect<affine::AffineDialect, scf::SCFDialect,
-                         func::FuncDialect, math::MathDialect,
-                         memref::MemRefDialect, arith::ArithDialect,
-                         linalg::LinalgDialect, tensor::TensorDialect,
-                         bufferization::BufferizationDialect>();
+  // Add legal dialects.
+  target.addLegalDialect<affine::AffineDialect>();
+  target.addLegalDialect<arith::ArithDialect>();
+  target.addLegalDialect<bufferization::BufferizationDialect>();
+  target.addLegalDialect<func::FuncDialect>();
+  target.addLegalDialect<linalg::LinalgDialect>();
+  target.addLegalDialect<math::MathDialect>();
+  target.addLegalDialect<memref::MemRefDialect>();
+  target.addLegalDialect<scf::SCFDialect>();
+  target.addLegalDialect<tensor::TensorDialect>();
+  // Add legal operations.
   target.addLegalOp<ModuleOp, func::FuncOp, func::ReturnOp>();
 
   RewritePatternSet patterns(context);