[mlir] Use dyn_cast instead of cast in MathToVCIX conversion (#134047)

Fixes #131093.

Author: CoTinker

mlir/test/Conversion/MathToVCIX/math-to-vcix.mlir

@@ -191,3 +191,14 @@ func.func @log_fixed(%a: vector<8 x f32>, %rvl: i64) -> vector<8 x f32> {
   %res = math.log %a : vector<8 x f32>
   return %res : vector<8 x f32>
 }
+
+// -----
+
+// Ensure this case exit gracefully
+
+// CHECK-LABEL:   func.func @no_vector_type
+// CHECK:           math.cos
+func.func @no_vector_type(%arg0: f32) -> f32 {
+  %0 = math.cos %arg0 : f32
+  return %0 : f32
+}

mlir/test/lib/Conversion/MathToVCIX/TestMathToVCIXConversion.cpp

@@ -25,7 +25,7 @@ namespace {
 /// according to LLVM's encoding:
 /// https://lists.llvm.org/pipermail/llvm-dev/2020-October/145850.html
 static std::pair<unsigned, VectorType> legalizeVectorType(const Type &type) {
-  VectorType vt = cast<VectorType>(type);
+  VectorType vt = dyn_cast<VectorType>(type);
   // To simplify test pass, avoid multi-dimensional vectors.
   if (!vt || vt.getRank() != 1)
     return {0, nullptr};