Bug 1894424 - Optimize gfxFont::AlwaysNeedsMaskForShadow check by caching the answer in the font entry. r=gfx-reviewers,lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D209104

gfx/thebes/gfxFont.h

@@ -1527,9 +1527,7 @@ class gfxFont {
   // and therefore needs us to use a mask for text-shadow even when
   // we're not actually blurring.
   bool AlwaysNeedsMaskForShadow() const {
-    return mFontEntry->TryGetColorGlyphs() || mFontEntry->TryGetSVGData(this) ||
-           mFontEntry->HasFontTable(TRUETYPE_TAG('C', 'B', 'D', 'T')) ||
-           mFontEntry->HasFontTable(TRUETYPE_TAG('s', 'b', 'i', 'x'));
+    return mFontEntry->AlwaysNeedsMaskForShadow();
   }
 
   // whether a feature is supported by the font (limited to a small set

gfx/thebes/gfxFontEntry.cpp

@@ -355,7 +355,7 @@ bool gfxFontEntry::TryGetSVGData(const gfxFont* aFont) {
     mSVGInitialized = true;
   }
 
-  if (GetSVGGlyphs()) {
+  if (GetSVGGlyphs() && aFont) {
     AutoWriteLock lock(mLock);
     if (!mFontsUsingSVGGlyphs.Contains(aFont)) {
       mFontsUsingSVGGlyphs.AppendElement(aFont);

gfx/thebes/gfxFontEntry.h

@@ -273,6 +273,18 @@ class gfxFontEntry {
     return flag == LazyFlag::Yes;
   }
 
+  inline bool AlwaysNeedsMaskForShadow() {
+    LazyFlag flag = mNeedsMaskForShadow;
+    if (flag == LazyFlag::Uninitialized) {
+      flag =
+          TryGetColorGlyphs() || TryGetSVGData(nullptr) || HasColorBitmapTable()
+              ? LazyFlag::Yes
+              : LazyFlag::No;
+      mNeedsMaskForShadow = flag;
+    }
+    return flag == LazyFlag::Yes;
+  }
+
   inline bool HasCmapTable() {
     if (!mCharacterMap && !mShmemCharacterMap) {
       ReadCMAP();
@@ -670,6 +682,7 @@ class gfxFontEntry {
   std::atomic<LazyFlag> mHasGraphiteTables;
   std::atomic<LazyFlag> mHasGraphiteSpaceContextuals;
   std::atomic<LazyFlag> mHasColorBitmapTable;
+  std::atomic<LazyFlag> mNeedsMaskForShadow;
 
   enum class SpaceFeatures : uint8_t {
     Uninitialized = 0xff,