[ptr-compr][ubsan] Use UnalignedSlot only for types which require bigger alignments

Bug: v8:7703
Change-Id: I497fe7e4ba81acbda8564142959f823c5195c5eb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1529008Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60338}

src/elements.cc

@@ -2973,13 +2973,13 @@ class TypedElementsAccessor
     DisallowHeapAllocation no_gc;
     BackingStore elements = BackingStore::cast(receiver->elements());
     ctype* data = static_cast<ctype*>(elements->DataPtr());
-#ifdef V8_COMPRESS_POINTERS
-    // TODO(ishell, v8:8875): See UnalignedSlot<T> for details.
-    std::fill(UnalignedSlot<ctype>(data + start),
-              UnalignedSlot<ctype>(data + end), value);
-#else
-    std::fill(data + start, data + end, value);
-#endif
+    if (COMPRESS_POINTERS_BOOL && alignof(ctype) > kTaggedSize) {
+      // TODO(ishell, v8:8875): See UnalignedSlot<T> for details.
+      std::fill(UnalignedSlot<ctype>(data + start),
+                UnalignedSlot<ctype>(data + end), value);
+    } else {
+      std::fill(data + start, data + end, value);
+    }
     return *array;
   }
 
@@ -3152,12 +3152,13 @@ class TypedElementsAccessor
     if (len == 0) return;
 
     ctype* data = static_cast<ctype*>(elements->DataPtr());
-#ifdef V8_COMPRESS_POINTERS
-    // TODO(ishell, v8:8875): See UnalignedSlot<T> for details.
-    std::reverse(UnalignedSlot<ctype>(data), UnalignedSlot<ctype>(data + len));
-#else
-    std::reverse(data, data + len);
-#endif
+    if (COMPRESS_POINTERS_BOOL && alignof(ctype) > kTaggedSize) {
+      // TODO(ishell, v8:8875): See UnalignedSlot<T> for details.
+      std::reverse(UnalignedSlot<ctype>(data),
+                   UnalignedSlot<ctype>(data + len));
+    } else {
+      std::reverse(data, data + len);
+    }
   }
 
   static Handle<FixedArray> CreateListFromArrayLikeImpl(Isolate* isolate,

src/runtime/runtime-typedarray.cc

@@ -125,21 +125,28 @@ RUNTIME_FUNCTION(Runtime_TypedArraySortFast) {
   Handle<FixedTypedArrayBase> elements(
       FixedTypedArrayBase::cast(array->elements()), isolate);
   switch (array->type()) {
-#define TYPED_ARRAY_SORT(Type, type, TYPE, ctype)                        \
-  case kExternal##Type##Array: {                                         \
-    ctype* data = static_cast<ctype*>(elements->DataPtr());              \
-    if (COMPRESS_POINTERS_BOOL &&                                        \
-        kExternal##Type##Array == kExternalFloat64Array) {               \
-      /* TODO(ishell, v8:8875): See UnalignedSlot<T> for details. */     \
-      std::sort(UnalignedSlot<ctype>(data),                              \
-                UnalignedSlot<ctype>(data + length), CompareNum<ctype>); \
-    } else if (kExternal##Type##Array == kExternalFloat64Array ||        \
-               kExternal##Type##Array == kExternalFloat32Array) {        \
-      std::sort(data, data + length, CompareNum<ctype>);                 \
-    } else {                                                             \
-      std::sort(data, data + length);                                    \
-    }                                                                    \
-    break;                                                               \
+#define TYPED_ARRAY_SORT(Type, type, TYPE, ctype)                          \
+  case kExternal##Type##Array: {                                           \
+    ctype* data = static_cast<ctype*>(elements->DataPtr());                \
+    if (kExternal##Type##Array == kExternalFloat64Array ||                 \
+        kExternal##Type##Array == kExternalFloat32Array) {                 \
+      if (COMPRESS_POINTERS_BOOL && alignof(ctype) > kTaggedSize) {        \
+        /* TODO(ishell, v8:8875): See UnalignedSlot<T> for details. */     \
+        std::sort(UnalignedSlot<ctype>(data),                              \
+                  UnalignedSlot<ctype>(data + length), CompareNum<ctype>); \
+      } else {                                                             \
+        std::sort(data, data + length, CompareNum<ctype>);                 \
+      }                                                                    \
+    } else {                                                               \
+      if (COMPRESS_POINTERS_BOOL && alignof(ctype) > kTaggedSize) {        \
+        /* TODO(ishell, v8:8875): See UnalignedSlot<T> for details. */     \
+        std::sort(UnalignedSlot<ctype>(data),                              \
+                  UnalignedSlot<ctype>(data + length));                    \
+      } else {                                                             \
+        std::sort(data, data + length);                                    \
+      }                                                                    \
+    }                                                                      \
+    break;                                                                 \
   }
 
     TYPED_ARRAYS(TYPED_ARRAY_SORT)