Testbench update axpy kernel

test/benchmark/axpy/axpy_int.cpp

@@ -1,16 +1,20 @@
+namespace {
+constexpr int kN = 16;
+constexpr int kA = 3;
+}  // namespace
+
 // Keep the function name matching "kernel" so llvm-extract --rfunc=".*kernel.*" can find it.
-extern "C" void kernel_axpy_int(int n, int a, const int *x, int *y) {
-  for (int i = 0; i < n; ++i) {
-    y[i] = a * x[i] + y[i];
+extern "C" void kernel_axpy_int(const int *x, int *y) {
+  for (int i = 0; i < kN; ++i) {
+    y[i] = kA * x[i] + y[i];
   }
 }
 
 // Provide a tiny main so clang emits a complete TU; tests extract only the kernel anyway.
 int main() {
-  const int N = 16;
-  static int x[N];
-  static int y[N];
-  kernel_axpy_int(N, /*a=*/3, x, y);
+  static int x[kN];
+  static int y[kN];
+  kernel_axpy_int(x, y);
   return 0;
 }