Allow lookup of module exports by export name.

This required fixing the exports_ hash map to use the appropriate
comparison function instead of pointer comparison.

BUG=v8:1569
LOG=n

Review URL: https://codereview.chromium.org/960793003

Cr-Commit-Position: refs/heads/master@{#26920}

src/modules.cc

@@ -20,9 +20,8 @@ void ModuleDescriptor::AddLocalExport(const AstRawString* export_name,
   ZoneAllocationPolicy allocator(zone);
 
   if (exports_ == nullptr) {
-    exports_ = new (zone->New(sizeof(ZoneHashMap)))
-        ZoneHashMap(ZoneHashMap::PointersMatch,
-                    ZoneHashMap::kDefaultHashMapCapacity, allocator);
+    exports_ = new (zone->New(sizeof(ZoneHashMap))) ZoneHashMap(
+        AstRawString::Compare, ZoneHashMap::kDefaultHashMapCapacity, allocator);
   }
 
   ZoneHashMap::Entry* p =
@@ -33,5 +32,18 @@ void ModuleDescriptor::AddLocalExport(const AstRawString* export_name,
 
   p->value = const_cast<AstRawString*>(local_name);
 }
+
+
+const AstRawString* ModuleDescriptor::LookupLocalExport(
+    const AstRawString* export_name, Zone* zone) {
+  if (exports_ == nullptr) return nullptr;
+  ZoneAllocationPolicy allocator(zone);
+  ZoneHashMap::Entry* entry =
+      exports_->Lookup(const_cast<AstRawString*>(export_name),
+                       export_name->hash(), false, allocator);
+  if (entry == nullptr) return nullptr;
+  DCHECK_NOT_NULL(entry->value);
+  return static_cast<const AstRawString*>(entry->value);
+}
 }
 }  // namespace v8::internal

src/modules.h

@@ -58,6 +58,9 @@ class ModuleDescriptor : public ZoneObject {
     return index_;
   }
 
+  const AstRawString* LookupLocalExport(const AstRawString* export_name,
+                                        Zone* zone);
+
   // ---------------------------------------------------------------------------
   // Iterators.
 

test/cctest/test-parsing.cc

@@ -5223,6 +5223,8 @@ TEST(ModuleParsingInternals) {
   i::Handle<i::String> source = factory->NewStringFromAsciiChecked(kSource);
   i::Handle<i::Script> script = factory->NewScript(source);
   i::CompilationInfoWithZone info(script);
+  i::Zone* zone = info.zone();
+  i::AstValueFactory avf(zone, isolate->heap()->HashSeed());
   i::Parser parser(&info, isolate->stack_guard()->real_climit(),
                    isolate->heap()->HashSeed(), isolate->unicode_cache());
   parser.set_allow_harmony_modules(true);
@@ -5233,13 +5235,12 @@ TEST(ModuleParsingInternals) {
   CHECK_EQ(i::MODULE_SCOPE, func->scope()->scope_type());
   i::ModuleDescriptor* descriptor = func->scope()->module();
   CHECK_NOT_NULL(descriptor);
-  int num_exports = 0;
-  for (auto it = descriptor->iterator(); !it.done(); it.Advance()) {
-    ++num_exports;
-    CHECK(it.local_name()->IsOneByteEqualTo("x"));
-    CHECK(it.export_name()->IsOneByteEqualTo("y"));
-  }
-  CHECK_EQ(1, num_exports);
+  CHECK_EQ(1, descriptor->Length());
+  const i::AstRawString* export_name = avf.GetOneByteString("y");
+  const i::AstRawString* local_name =
+      descriptor->LookupLocalExport(export_name, zone);
+  CHECK_NOT_NULL(local_name);
+  CHECK(local_name->IsOneByteEqualTo("x"));
   i::ZoneList<i::Declaration*>* declarations = func->scope()->declarations();
   CHECK_EQ(2, declarations->length());
   CHECK(declarations->at(0)->proxy()->raw_name()->IsOneByteEqualTo("x"));