Add a operand type check for Corr2D op and a test

  - Make sure that input, kernel, output and constant have the same
    value and use as inferred type
  - Adding a negative lit test to check params of the op

lib/Conversion/LowerDIP/LowerDIPPass.cpp

@@ -73,8 +73,16 @@ class DIPCorr2DOpLowering : public OpRewritePattern<dip::Corr2DOp> {
     auto boundaryOptionAttr = op.boundary_option();
     Value strideVal = rewriter.create<ConstantIndexOp>(loc, stride);
 
-    auto memRefTy = input.getType().cast<MemRefType>();
-    auto elemTy = memRefTy.getElementType();
+    auto inElemTy = input.getType().cast<MemRefType>().getElementType();
+    auto kElemTy = kernel.getType().cast<MemRefType>().getElementType();
+    auto outElemTy = output.getType().cast<MemRefType>().getElementType();
+    auto constElemTy = constantValue.getType();
+    if (inElemTy != kElemTy || kElemTy != outElemTy || outElemTy != constElemTy) {
+        return op->emitOpError() <<  "input, kernel, output and constant must have the same element type";
+    }
+    // NB: we can infer element type for all operation to be the same as input
+    // since we verified that the operand types are the same
+    auto elemTy = inElemTy;
 
     IntegerType i1 = IntegerType::get(ctx, 1);
 
@@ -99,6 +107,7 @@ class DIPCorr2DOpLowering : public OpRewritePattern<dip::Corr2DOp> {
     FloatType f32 = FloatType::getF32(ctx);
     IntegerType i32 = IntegerType::get(ctx, 32);
     Value zeroPaddingElem = {};
+    // TODO: extend for other types and add a check for supported types
     if (elemTy.isF32()) {
         zeroPaddingElem = rewriter.create<ConstantFloatOp>(loc, (APFloat)(float)0, f32);
     } else if (elemTy.isInteger(32)) {