From 604a9a98a972ae11590e0de4e3e9faac385302fd Mon Sep 17 00:00:00 2001
From: Eduardo Roman <eromanc@fb.com>
Date: Wed, 16 Jan 2019 11:53:04 -0800
Subject: [PATCH] guard against INF values in CompactValue

Summary:
After this diff D13403925 that got rid of `-ffast-math` we started to have a very odd behavior on Yoga when using release builds.

After digging a while we found that certain set of conditions on O2 and O3 optimization levels was causing Origami to set some `INFINITE` values on Yoga.

We found the root of the problem and fix it on Origami side. But I'm wondering if guarding agains `INFINITE` on Yoga side would be good too. Since now Yoga it's not using `-ffast-math` anymore, and I think infinite is not a a valid value anywhere on Yoga side, it seems to support the reason to guard against it.

I'm happy to abandon this diff if you guys think this is not a good solution.

Reviewed By: davidaurelio

Differential Revision: D13679319

fbshipit-source-id: 061448fea9d1a8496362ff07dc46b546e7f1ffa3
---
 tests/CompactValueTest.cpp | 12 ++++++++++++
 yoga/CompactValue.h        |  3 ++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/tests/CompactValueTest.cpp b/tests/CompactValueTest.cpp
index 7d2afc13..d0a2c669 100644
--- a/tests/CompactValueTest.cpp
+++ b/tests/CompactValueTest.cpp
@@ -29,6 +29,18 @@ TEST(YogaTest, compact_value_can_represent_undefined) {
   ASSERT_FALSE(c.isAuto());
 }
 
+TEST(YogaTest, compact_value_manages_infinity_as_undefined) {
+  auto c = CompactValue{
+      YGValue{std::numeric_limits<float>::infinity(), YGUnitUndefined}};
+  YGValue v = c;
+  ASSERT_EQ(v, YGValueUndefined);
+  ASSERT_NE(v, YGValueAuto);
+  ASSERT_NE(v, (YGValue{-1.25, YGUnitPoint}));
+  ASSERT_NE(v, (YGValue{25, YGUnitPercent}));
+  ASSERT_TRUE(c.isUndefined());
+  ASSERT_FALSE(c.isAuto());
+}
+
 TEST(YogaTest, compact_value_can_represent_auto) {
   auto c = CompactValue{YGValue{0, YGUnitAuto}};
   YGValue v = c;
diff --git a/yoga/CompactValue.h b/yoga/CompactValue.h
index 9c9a92e0..3cc36a48 100644
--- a/yoga/CompactValue.h
+++ b/yoga/CompactValue.h
@@ -70,7 +70,8 @@ public:
 
   template <YGUnit Unit>
   static CompactValue ofMaybe(float value) noexcept {
-    return std::isnan(value) ? ofUndefined() : of<Unit>(value);
+    return std::isnan(value) || std::isinf(value) ? ofUndefined()
+                                                  : of<Unit>(value);
   }
 
   static constexpr CompactValue ofZero() noexcept {