Introducing upgrated BLIS GTestSuite.

Key features:
- able to test both static and dynamic libraries
- able to test BLAS, CBLAS and BLIS-typed interface
- can use any CBLAS library for reference results
- can build and/or run tests depending on the BLAS level or a specific API

AMD-Internal: [CPUPL-2732]
Change-Id: Ibe0d7938e06081526bbc54d3182ac7d17affdaf6

gtestsuite/testinghelpers/inc/common/error_helpers.h

@@ -0,0 +1,67 @@
+#pragma once
+
+#include <limits>
+#include "common/type_info.h"
+
+namespace testinghelpers {
+
+/**
+ * @brief Returns the value of machine epsilon depending on the type.
+ *        For scomplex and dcomplex, returns the value of machine epsilon
+ *        for float and double, respectively.
+ *        Epsilon is used as the basis for setting the threshold used for
+ *        SUCCESS or FAILURE of tests.
+ */
+template<typename T>
+double getEpsilon()
+{
+    using RT = typename testinghelpers::type_info<T>::real_type;
+    double eps = std::numeric_limits<RT>::epsilon();
+    return eps;
+}
+
+/**
+ * @brief Returns the relative error. Relative error is used in most cases since
+ *        it takes into account the magnitude of the exact and approx.
+ *        For the cases where we are comparing very small values, that is values
+ *        which are approximately zero, division with zero will cause inf/NaN.
+ *        For example, if exact=0 and approx=0, getRelativeError() would return -NaN.
+ */
+template<typename T>
+double getRelativeError(T exact, T approx)
+{
+    double rel_err;
+    rel_err = std::abs(exact - approx)/std::abs(exact);
+    return rel_err;
+}
+
+/**
+ * @brief Returns the absolute error. Absolute error is used for the cases where
+ *        we are comparing very small values, where relative error cannot be used.
+ *        For example, on the example above where exact=0 and approx=0,
+ *        getAbsoluteError() would return 0.
+ *
+ *        Absolute error doesn't take into account magnitude which means that for
+ *        large values this could give false negatives.
+ *        For example, if T is float, exact=598320.943 and approx=598320.9431,
+ *        getAbsoluteError() would return 0.0001, compared to the relative error of ~2e-10.
+ */
+template<typename T>
+double getAbsoluteError(T exact, T approx)
+{
+    double abs_err;
+    abs_err = std::abs(exact - approx);
+    return abs_err;
+}
+
+template<typename T>
+double getError(T exact, T approx)
+{
+    if ( std::abs(exact) > 1 )
+        return getRelativeError(exact, approx);
+    else
+        return getAbsoluteError(exact, approx);
+}
+
+
+} // end of testinghelpers namespace