Add testcase for extendhfxf2

Author: biabbas

compiler-rt/test/builtins/Unit/extendhfxf2_test.c

@@ -0,0 +1,57 @@
+// RUN: %clang_builtins %s %librt -o %t && %run %t
+// REQUIRES: librt_has_extendhfxf2
+
+#include <stdio.h>
+#include <math.h> // for isnan, isinf
+#include <limits.h>
+
+long double __extendhfxf2(_Float16 f);
+
+int test_extendhfxf2(_Float16 a, long double expected)
+{
+    long double x = __extendhfxf2(a);
+    int ret = !(x == expected || (isnan(x) && isnan(expected)) || (isinf(x) && isinf(expected) && x == expected));
+    if (ret){
+        printf("error in test__extendhfsf2(%f) = %.20Lf, "
+               "expected %.20Lf\n", a, x, expected);
+    }
+    return ret;
+}
+
+char assumption_1[sizeof(_Float16) * CHAR_BIT == 16] = {0};
+
+int main() {
+    // Small positive value
+    if (test_extendhfxf2(0.09997558593750000000f, 0.09997558593750000000f))
+        return 1;
+
+    // Small negative value
+    if (test_extendhfxf2(-0.09997558593750000000f, -0.09997558593750000000f))
+        return 1;
+
+    // Zero
+    if (test_extendhfxf2(0.0f, 0.0L))
+        return 1;
+
+    // Smallest positive non-zero value
+    if (test_extendhfxf2(0x1p-16f, 0x1p-16f))
+        return 1;
+
+    // Smallest negative non-zero value
+    if (test_extendhfxf2(-0x1p-16f, -0x1p-16f))
+        return 1;
+
+    // Positive infinity
+    if (test_extendhfxf2(__builtin_huge_valf16(), __builtin_huge_valf64x()))
+        return 1;
+
+    // Negative infinity
+    if (test_extendhfxf2(-__builtin_huge_valf16(), (long double)-__builtin_huge_valf64x()))
+        return 1;
+
+    // NaN
+    if (test_extendhfxf2(__builtin_nanf16(""), (long double)__builtin_nanf64x("")))
+        return 1;
+
+    return 0;
+}