[heap] Simplify zapping of old optimized code maps.

This unconditionally enables zapping of old optimized code maps and
unifies the various zapping paths. The unconditional zapping, even if
heap verification is off, is needed because slots in the code map have
not been recorded and evacuation invariants break.

R=ulan@chromium.org

Review URL: https://codereview.chromium.org/1410833009

Cr-Commit-Position: refs/heads/master@{#31895}

src/objects.cc

@@ -11104,12 +11104,7 @@ void SharedFunctionInfo::AddToOptimizedCodeMap(
     // flushed the optimized code map and the copy we created is full of holes.
     // For now we just give up on adding the entry and pretend it got flushed.
     if (shared->optimized_code_map()->IsSmi()) return;
-    int old_length = old_code_map->length();
-    // Zap the old map to avoid any stale entries. Note that this is required
-    // for correctness because entries are being treated weakly by the GC.
-    MemsetPointer(old_code_map->data_start(), isolate->heap()->the_hole_value(),
-                  old_length);
-    entry = old_length;
+    entry = old_code_map->length();
   }
   new_code_map->set(entry + kContextOffset, *native_context);
   new_code_map->set(entry + kCachedCodeOffset, *code);
@@ -11129,12 +11124,10 @@ void SharedFunctionInfo::AddToOptimizedCodeMap(
   }
 #endif
 
-  if (Heap::ShouldZapGarbage()) {
-    // Zap any old optimized code map for heap-verifier.
-    if (!shared->optimized_code_map()->IsSmi()) {
-      FixedArray* old_code_map = FixedArray::cast(shared->optimized_code_map());
-      old_code_map->FillWithHoles(0, old_code_map->length());
-    }
+  // Zap any old optimized code map.
+  if (!shared->optimized_code_map()->IsSmi()) {
+    FixedArray* old_code_map = FixedArray::cast(shared->optimized_code_map());
+    old_code_map->FillWithHoles(0, old_code_map->length());
   }
 
   shared->set_optimized_code_map(*new_code_map);
@@ -11142,12 +11135,10 @@ void SharedFunctionInfo::AddToOptimizedCodeMap(
 
 
 void SharedFunctionInfo::ClearOptimizedCodeMap() {
-  if (Heap::ShouldZapGarbage()) {
-    // Zap any old optimized code map for heap-verifier.
-    if (!optimized_code_map()->IsSmi()) {
-      FixedArray* old_code_map = FixedArray::cast(optimized_code_map());
-      old_code_map->FillWithHoles(0, old_code_map->length());
-    }
+  // Zap any old optimized code map.
+  if (!optimized_code_map()->IsSmi()) {
+    FixedArray* old_code_map = FixedArray::cast(optimized_code_map());
+    old_code_map->FillWithHoles(0, old_code_map->length());
   }
 
   set_optimized_code_map(Smi::FromInt(0));