Fix powr and re-enable test.

We already treat 1 as a special case in pow(). If we treat it as a
special case in powr() too, that looks to be sufficient to avoid
errors caused by internal overflow.

modules/compiler/builtins/abacus/source/abacus_math/powr.cpp

@@ -45,12 +45,14 @@ inline T powr(const T x, const T y) {
   result =
       __abacus_select(result, bit, SignedType(xIsInf | yIsInf | (x == 0.0f)));
 
-  // Return for any input where y is zero
-  result = __abacus_select(result, T(1.0), SignedType(y == 0.0f));
+  // Return 1 for any input where x is 1 or y is zero and we do not subsequently
+  // change it to NaN.
+  result =
+      __abacus_select(result, T(1.0f), SignedType((x == 1.0f) | (y == 0.0f)));
 
-  // Return NAN in the following conditions:
-  // * x is NAN
-  // * y is NAN
+  // Return NaN in the following conditions:
+  // * x is NaN
+  // * y is NaN
   // * x is less than zero
   // * x is +/- zero and y is +/- zero
   // * x is INFINITY and y is +/- zero

source/cl/test/UnitCL/source/ktst_precision.cpp

@@ -1807,8 +1807,7 @@ TEST_P(HalfMathBuiltinsPow, Precision_80_Half_pow) {
   TestAgainstRef<4_ULP>(pow_ref);
 }
 
-// TODO: OCK-523
-TEST_P(HalfMathBuiltinsPow, DISABLED_Precision_81_Half_powr) {
+TEST_P(HalfMathBuiltinsPow, Precision_81_Half_powr) {
   if (!UCL::hasHalfSupport(device)) {
     GTEST_SKIP();
   }