Change NaN with large number

Summary:
Changed NaN with large number to support `-ffast-math` compiler flag.For  `-ffast-math` to work, all floating point numbers should be finite. Reason for not going with `FLT_MAX`, is that, it may cause number overflow during math operations. So thats why I opted for big number smaller than `FLT_MAX`.  Earlier we used NaN, while NaN is involved in comparision the comparision operator behaves differently, it always returns false. Also operators like, fmaxf,fminf etc. have wierd beahviours. This diff takes care of those things as far as possible, and all tests are passing.

Running ./instrumentation_tests/run instrumentation_tests/com/facebook/feed/ctacoalescing:ctacoalescing --class AttachmentCallToActionSelectorBenchmarkTest --benchmark --extra-arg iterations=100 shows the perf gain of 13-15%

Reviewed By: emilsjolander

Differential Revision: D6969537

fbshipit-source-id: bdc09eaf703e0d313ca65c25a4fb44c99203d9bf

yoga/Utils.h

@@ -54,6 +54,38 @@ struct YGCollectFlexItemsRowValues {
 
 bool YGValueEqual(const YGValue a, const YGValue b);
 
+// This custom float equality function returns true if either absolute
+// difference between two floats is less than 0.0001f or both are undefined.
+bool YGFloatsEqual(const float a, const float b);
+
+// We need custom max function, since we want that, if one argument is
+// YGUndefined then the max funtion should return the other argument as the max
+// value. We wouldn't have needed a custom max function if YGUndefined was NAN
+// as fmax has the same behaviour, but with NAN we cannot use `-ffast-math`
+// compiler flag.
+float YGFloatMax(const float a, const float b);
+
+// We need custom min function, since we want that, if one argument is
+// YGUndefined then the min funtion should return the other argument as the min
+// value. We wouldn't have needed a custom min function if YGUndefined was NAN
+// as fmin has the same behaviour, but with NAN we cannot use `-ffast-math`
+// compiler flag.
+float YGFloatMin(const float a, const float b);
+
+// This custom float comparision function compares the array of float with
+// YGFloatsEqual, as the default float comparision operator will not work(Look
+// at the comments of YGFloatsEqual function).
+template <std::size_t size>
+bool YGFloatArrayEqual(
+    const std::array<float, size>& val1,
+    const std::array<float, size>& val2) {
+  bool areEqual = true;
+  for (std::size_t i = 0; i < size && areEqual; ++i) {
+    areEqual = YGFloatsEqual(val1[i], val2[i]);
+  }
+  return areEqual;
+}
+
 YGFlexDirection YGFlexDirectionCross(
     const YGFlexDirection flexDirection,
     const YGDirection direction);
@@ -71,7 +103,7 @@ inline float YGResolveValue(const YGValue value, const float parentSize) {
     case YGUnitPoint:
       return value.value;
     case YGUnitPercent:
-      return value.value * parentSize / 100.0f;
+      return value.value * parentSize * 0.01;
   }
   return YGUndefined;
 }