XeGPU Flash Attention implementation. (#703)

Author: charithaintc

lib/ExecutionEngine/ImexRunnerUtils.cpp

@@ -211,15 +211,18 @@ void _mlir_ciface_printMaxError(UnrankedMemRefType<T> *M,
   DynamicMemRefType<T> DN = DynamicMemRefType<T>(*N);
   DynamicMemRefIterator<T> i = DM.begin();
   DynamicMemRefIterator<T> j = DN.begin();
-  std::pair<float, DynamicMemRefIterator<T>> max_rel_err_idx{0.0, DM.begin()};
-  std::pair<float, DynamicMemRefIterator<T>> max_abs_err_idx{0.0, DM.begin()};
-  for (; i != DM.end() && j != DN.end(); ++i, ++j) {
-    const float delta = getFloat(*i) - getFloat(*j);
-    const float delta_abs = fabs(delta);
-    if (delta > max_abs_err_idx.first) {
-      max_abs_err_idx = {delta_abs, i};
-      max_rel_err_idx = {delta, i};
-    }
+  std::pair<double, DynamicMemRefIterator<T>> max_rel_err_idx{0.0, DM.begin()};
+  std::pair<double, DynamicMemRefIterator<T>> max_abs_err_idx{0.0, DM.begin()};
+  uint64_t idx = 0;
+  for (; i != DM.end() && j != DN.end(); ++i, ++j, ++idx) {
+    const double i_val = getFloat(*i);
+    const double j_val = getFloat(*j);
+    const double delta = fabs(i_val - j_val);
+    const double rel_error = delta / fmax(fabs(i_val), fabs(j_val));
+    if (delta > max_abs_err_idx.first)
+      max_abs_err_idx = {delta, i};
+    if (rel_error > max_rel_err_idx.first)
+      max_rel_err_idx = {rel_error, i};
   }
   std::cout << "Max absolute error " << max_abs_err_idx.first
             << " at idx=" << std::distance(DM.begin(), max_abs_err_idx.second)