1 files changed, 27 insertions, 32 deletions

diff --git a/layout/generic/nsGridContainerFrame.h b/layout/generic/nsGridContainerFrame.h
index cb3eef68c3..1fa7bbe487 100644
--- a/layout/generic/nsGridContainerFrame.h
+++ b/layout/generic/nsGridContainerFrame.h
@@ -566,12 +566,8 @@ class nsGridContainerFrame final : public nsContainerFrame,
       if (aFrame->IsSubtreeDirty()) {
         return false;
       }
-
-      if (!CanCacheMeasurement(aFrame, aCBSize)) {
-        return false;
-      }
-
-      return mKey == Key(aFrame, aCBSize);
+      const mozilla::Maybe<Key> maybeKey = Key::TryHash(aFrame, aCBSize);
+      return maybeKey.isSome() && mKey == *maybeKey;
     }
 
     static bool CanCacheMeasurement(const nsIFrame* aFrame,
@@ -583,55 +579,54 @@ class nsGridContainerFrame final : public nsContainerFrame,
 
     void Update(const nsIFrame* aFrame, const LogicalSize& aCBSize,
                 const nscoord aBSize) {
-      MOZ_ASSERT(CanCacheMeasurement(aFrame, aCBSize));
-      mKey.mHashKey = Key::GenerateHash(aFrame, aCBSize);
+      mKey.UpdateHash(aFrame, aCBSize);
       mBSize = aBSize;
     }
 
    private:
-    struct Key {
+    class Key {
       // mHashKey is generated by combining these 2 variables together
       //   1. The containing block size in the item's inline axis used
       //   for measuring reflow
       //   2. The item's baseline padding property
       uint32_t mHashKey;
 
+      explicit Key(uint32_t aHashKey) : mHashKey(aHashKey) {}
+
+     public:
       Key() = default;
 
       Key(const nsIFrame* aFrame, const LogicalSize& aCBSize) {
-        MOZ_ASSERT(CanHash(aFrame, aCBSize));
-        mHashKey = GenerateHash(aFrame, aCBSize);
+        UpdateHash(aFrame, aCBSize);
       }
 
       void UpdateHash(const nsIFrame* aFrame, const LogicalSize& aCBSize) {
-        MOZ_ASSERT(CanHash(aFrame, aCBSize));
-        mHashKey = GenerateHash(aFrame, aCBSize);
+        const mozilla::Maybe<Key> maybeKey = TryHash(aFrame, aCBSize);
+        MOZ_ASSERT(maybeKey.isSome());
+        mHashKey = maybeKey->mHashKey;
       }
 
-      static uint32_t GenerateHash(const nsIFrame* aFrame,
-                                   const LogicalSize& aCBSize) {
-        MOZ_ASSERT(CanHash(aFrame, aCBSize));
-
-        nscoord gridAreaISize = aCBSize.ISize(aFrame->GetWritingMode());
-        nscoord bBaselinePaddingProperty =
+      static mozilla::Maybe<Key> TryHash(const nsIFrame* aFrame,
+                                         const LogicalSize& aCBSize) {
+        const nscoord gridAreaISize = aCBSize.ISize(aFrame->GetWritingMode());
+        const nscoord bBaselinePaddingProperty =
             abs(aFrame->GetProperty(nsIFrame::BBaselinePadProperty()));
 
-        uint_fast8_t bitsNeededForISize = mozilla::FloorLog2(gridAreaISize) + 1;
-
-        return (gridAreaISize << (32 - bitsNeededForISize)) |
-               bBaselinePaddingProperty;
+        const uint_fast8_t bitsNeededForISize =
+            mozilla::FloorLog2(gridAreaISize) + 1;
+
+        const uint_fast8_t bitsNeededForBBaselinePadding =
+            mozilla::FloorLog2(bBaselinePaddingProperty) + 1;
+        if (bitsNeededForISize + bitsNeededForBBaselinePadding > 32) {
+          return mozilla::Nothing();
+        }
+        const uint32_t hashKey = (gridAreaISize << (32 - bitsNeededForISize)) |
+                                 bBaselinePaddingProperty;
+        return mozilla::Some(Key(hashKey));
       }
 
       static bool CanHash(const nsIFrame* aFrame, const LogicalSize& aCBSize) {
-        uint_fast8_t bitsNeededForISize =
-            mozilla::FloorLog2(aCBSize.ISize(aFrame->GetWritingMode())) + 1;
-
-        uint_fast8_t bitsNeededForBBaselinePadding =
-            mozilla::FloorLog2(
-                abs(aFrame->GetProperty(nsIFrame::BBaselinePadProperty()))) +
-            1;
-
-        return bitsNeededForISize + bitsNeededForBBaselinePadding <= 32;
+        return TryHash(aFrame, aCBSize).isSome();
       }
 
       bool operator==(const Key& aOther) const {