[cleanup] Remove unused EstimateNumberOfElements runtime function

R=jgruber@chromium.org

Bug: v8:9183
Change-Id: I773af2e44bbfb780a3cf375e6412274fe917d397
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1617250
Commit-Queue: Simon Zünd <szuend@chromium.org>
Auto-Submit: Simon Zünd <szuend@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61616}

src/debug/debug-evaluate.cc

@@ -262,7 +262,6 @@ bool IntrinsicHasNoSideEffect(Runtime::FunctionId id) {
   V(GetProperty)                              \
   /* Arrays */                                \
   V(ArraySpeciesConstructor)                  \
-  V(EstimateNumberOfElements)                 \
   V(HasComplexElements)                       \
   V(HasFastPackedElements)                    \
   V(NewArray)                                 \

src/runtime/runtime-array.cc

@@ -422,44 +422,6 @@ RUNTIME_FUNCTION(Runtime_PrepareElementsForSort) {
   return RemoveArrayHoles(isolate, object, length);
 }
 
-// How many elements does this object/array have?
-RUNTIME_FUNCTION(Runtime_EstimateNumberOfElements) {
-  DisallowHeapAllocation no_gc;
-  HandleScope scope(isolate);
-  DCHECK_EQ(1, args.length());
-  CONVERT_ARG_CHECKED(JSArray, array, 0);
-  FixedArrayBase elements = array->elements();
-  SealHandleScope shs(isolate);
-  if (elements->IsNumberDictionary()) {
-    int result = NumberDictionary::cast(elements)->NumberOfElements();
-    return Smi::FromInt(result);
-  } else {
-    DCHECK(array->length()->IsSmi());
-    // For packed elements, we know the exact number of elements
-    int length = elements->length();
-    ElementsKind kind = array->GetElementsKind();
-    if (IsFastPackedElementsKind(kind)) {
-      return Smi::FromInt(length);
-    }
-    // For holey elements, take samples from the buffer checking for holes
-    // to generate the estimate.
-    const int kNumberOfHoleCheckSamples = 97;
-    int increment = (length < kNumberOfHoleCheckSamples)
-                        ? 1
-                        : static_cast<int>(length / kNumberOfHoleCheckSamples);
-    ElementsAccessor* accessor = array->GetElementsAccessor();
-    int holes = 0;
-    for (int i = 0; i < length; i += increment) {
-      if (!accessor->HasElement(array, i, elements)) {
-        ++holes;
-      }
-    }
-    int estimate = static_cast<int>((kNumberOfHoleCheckSamples - holes) /
-                                    kNumberOfHoleCheckSamples * length);
-    return Smi::FromInt(estimate);
-  }
-}
-
 RUNTIME_FUNCTION(Runtime_TrySliceSimpleNonFastElements) {
   HandleScope scope(isolate);
   DCHECK_EQ(3, args.length());

src/runtime/runtime.h

@@ -42,7 +42,6 @@ namespace internal {
   F(ArrayIndexOf, 3, 1)                   \
   F(ArrayIsArray, 1, 1)                   \
   F(ArraySpeciesConstructor, 1, 1)        \
-  F(EstimateNumberOfElements, 1, 1)       \
   F(GrowArrayElements, 2, 1)              \
   F(HasComplexElements, 1, 1)             \
   I(IsArray, 1, 1)                        \