Bug 1771503 - Disable the 'two layers that scroll together' assertion for matrices with Inf or NaN elements. r=tnikkel

Differential Revision: https://phabricator.services.mozilla.com/D149466
2022-06-17 23:50:49 +00:00 · 2022-06-17 23:50:49 +00:00 · 5d687c962b
--- a/gfx/2d/Matrix.h
+++ b/gfx/2d/Matrix.h
@ -1510,6 +1510,18 @@ class Matrix4x4Typed {
    _44 = UnspecifiedNaN<T>();
  }

+  // Verifies that the matrix contains no Infs or NaNs
+  bool IsFinite() const {
+    return mozilla::IsFinite(_11) && mozilla::IsFinite(_12) &&
+           mozilla::IsFinite(_13) && mozilla::IsFinite(_14) &&
+           mozilla::IsFinite(_21) && mozilla::IsFinite(_22) &&
+           mozilla::IsFinite(_23) && mozilla::IsFinite(_24) &&
+           mozilla::IsFinite(_31) && mozilla::IsFinite(_32) &&
+           mozilla::IsFinite(_33) && mozilla::IsFinite(_34) &&
+           mozilla::IsFinite(_41) && mozilla::IsFinite(_42) &&
+           mozilla::IsFinite(_43) && mozilla::IsFinite(_44);
+  }
+
  void SkewXY(double aXSkew, double aYSkew) {
    // XXX Is double precision really necessary here
    T tanX = SafeTangent(aXSkew);
--- a/gfx/layers/apz/src/APZCTreeManager.cpp
+++ b/gfx/layers/apz/src/APZCTreeManager.cpp
@ -1322,8 +1322,10 @@ HitTestingTreeNode* APZCTreeManager::PrepareNodeForLayer(
    // In such cases, go with the one that does not include the perspective
    // component; the perspective transform is remembered and applied to the
    // children instead.
-    if (!aAncestorTransform.CombinedTransform().FuzzyEqualsMultiplicative(
-            apzc->GetAncestorTransform())) {
+    auto ancestorTransform = aAncestorTransform.CombinedTransform();
+    auto existingAncestorTransform = apzc->GetAncestorTransform();
+    if (!ancestorTransform.FuzzyEqualsMultiplicative(
+            existingAncestorTransform)) {
      typedef TreeBuildingState::DeferredTransformMap::value_type PairType;
      if (!aAncestorTransform.ContainsPerspectiveTransform() &&
          !apzc->AncestorTransformContainsPerspective()) {
@ -1333,9 +1335,16 @@ HitTestingTreeNode* APZCTreeManager::PrepareNodeForLayer(
        // cases, it's expected that different instances can have different
        // transforms, since each page renders a different part of the item.
        if (!aLayer.Metadata().IsPaginatedPresentation()) {
-          MOZ_ASSERT(false,
-                     "Two layers that scroll together have different ancestor "
-                     "transforms");
+          if (ancestorTransform.IsFinite() &&
+              existingAncestorTransform.IsFinite()) {
+            MOZ_ASSERT(
+                false,
+                "Two layers that scroll together have different ancestor "
+                "transforms");
+          } else {
+            MOZ_ASSERT(ancestorTransform.IsFinite() ==
+                       existingAncestorTransform.IsFinite());
+          }
        }
      } else if (!aAncestorTransform.ContainsPerspectiveTransform()) {
        aState.mPerspectiveTransformsDeferredToChildren.insert(
--- a/layout/base/crashtests/1771503.html
+++ b/layout/base/crashtests/1771503.html
@ -0,0 +1,22 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <style>
+        * {
+            transform: matrix3d(130, -7052, 1000, 35803, 122, 7197, 197, 126, 201, 64, 38, -69, 5.727476671737168, 124, 22882, 168.04863081346616);
+            overflow: auto clip ! important;
+            padding-right: 39%;
+            min-inline-size: min-content;
+        }
+    </style>
+</head>
+<body>
+<table>
+    <th>
+        <fieldset>
+            <textarea cols='4096' autofocus></textarea>
+        </fieldset>
+    </th>
+</table>
+</body>
+</html>
--- a/layout/base/crashtests/crashtests.list
+++ b/layout/base/crashtests/crashtests.list
@ -568,3 +568,4 @@ pref(layout.accessiblecaret.enabled,true) load 1746989.html
 load 1752649.html
 load 1753779.html
 pref(layout.css.backdrop-filter.enabled,true) load 1755790.html
+load 1771503.html