Basic interface inference for modules.

src/interface.cc

Index: src/interface.cc
diff --git a/src/interface.cc b/src/interface.cc
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+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "v8.h"
+
+#include "interface.h"
+
+namespace v8 {
+namespace internal {
+
+static bool Match(void* key1, void* key2) {
+  String* name1 = *static_cast<String**>(key1);
+  String* name2 = *static_cast<String**>(key2);
+  ASSERT(name1->IsSymbol());
+  ASSERT(name2->IsSymbol());
+  return name1 == name2;
+}
+
+
+Interface* Interface::Lookup(Handle<String> name) {
+  ASSERT(IsModule());
+  ZoneHashMap* map = Chase()->exports_;
+  if (map == NULL) return NULL;
+  ZoneHashMap::Entry* p = map->Lookup(name.location(), name->Hash(), false);
+  if (p == NULL) return NULL;
+  ASSERT(*static_cast<String**>(p->key) == *name);
+  ASSERT(p->value != NULL);
+  return static_cast<Interface*>(p->value);
+}
+
+
+#ifdef DEBUG
+// Current nesting depth for debug output.
+class Nesting {
+ public:
+  Nesting()  { current_ += 2; }
+  ~Nesting() { current_ -= 2; }
+  static int current() { return current_; }
+ private:
+  static int current_;
+};
+
+int Nesting::current_ = 0;
+#endif
+
+
+void Interface::DoAdd(
+    void* name, uint32_t hash, Interface* interface, bool* ok) {
+  MakeModule(ok);
+  if (!*ok) return;
+
+#ifdef DEBUG
+  if (FLAG_print_interface_details) {
+    PrintF("%*s# Adding...\n", Nesting::current(), "");
+    PrintF("%*sthis = ", Nesting::current(), "");
+    this->Print(Nesting::current());
+    PrintF("%*s%s : ", Nesting::current(), "",
+           (*reinterpret_cast<String**>(name))->ToAsciiArray());
+    interface->Print(Nesting::current());
+  }
+#endif
+
+  ZoneHashMap** map = &Chase()->exports_;
+  if (*map == NULL) *map = new ZoneHashMap(Match, 8);
+
+  ZoneHashMap::Entry* p = (*map)->Lookup(name, hash, !IsFrozen());
+  if (p == NULL) {
+    // This didn't have name but was frozen already, that's an error.
+    *ok = false;
+  } else if (p->value == NULL) {
+    p->value = interface;
+  } else {
+#ifdef DEBUG
+    Nesting nested;
+#endif
+    reinterpret_cast<Interface*>(p->value)->Unify(interface, ok);
+  }
+
+#ifdef DEBUG
+  if (FLAG_print_interface_details) {
+    PrintF("%*sthis' = ", Nesting::current(), "");
+    this->Print(Nesting::current());
+    PrintF("%*s# Added.\n", Nesting::current(), "");
+  }
+#endif
+}
+
+
+void Interface::Unify(Interface* that, bool* ok) {
+  if (this->forward_) return this->Chase()->Unify(that, ok);
+  if (that->forward_) return this->Unify(that->Chase(), ok);
+  ASSERT(this->forward_ == NULL);
+  ASSERT(that->forward_ == NULL);
+
+  *ok = true;
+  if (this == that) return;
+  if (this->IsValue()) return that->MakeValue(ok);
+  if (that->IsValue()) return this->MakeValue(ok);
+
+#ifdef DEBUG
+  if (FLAG_print_interface_details) {
+    PrintF("%*s# Unifying...\n", Nesting::current(), "");
+    PrintF("%*sthis = ", Nesting::current(), "");
+    this->Print(Nesting::current());
+    PrintF("%*sthat = ", Nesting::current(), "");
+    that->Print(Nesting::current());
+  }
+#endif
+
+  // Merge the smaller interface into the larger, for performance.
+  if (this->exports_ != NULL && (that->exports_ == NULL ||
+      this->exports_->occupancy() >= that->exports_->occupancy())) {
+    this->DoUnify(that, ok);
+  } else {
+    that->DoUnify(this, ok);
+  }
+
+#ifdef DEBUG
+  if (FLAG_print_interface_details) {
+    PrintF("%*sthis' = ", Nesting::current(), "");
+    this->Print(Nesting::current());
+    PrintF("%*sthat' = ", Nesting::current(), "");
+    that->Print(Nesting::current());
+    PrintF("%*s# Unified.\n", Nesting::current(), "");
+  }
+#endif
+}
+
+
+void Interface::DoUnify(Interface* that, bool* ok) {
+  ASSERT(this->forward_ == NULL);
+  ASSERT(that->forward_ == NULL);
+  ASSERT(!this->IsValue());
+  ASSERT(!that->IsValue());
+  ASSERT(*ok);
+
+#ifdef DEBUG
+    Nesting nested;
+#endif
+
+  // Try to merge all members from that into this.
+  ZoneHashMap* map = that->exports_;
+  if (map != NULL) {
+    for (ZoneHashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p)) {
+      this->DoAdd(p->key, p->hash, static_cast<Interface*>(p->value), ok);
+      if (!*ok) return;
+    }
+  }
+
+  // If the new interface is larger than that's, then there were members in
+  // 'this' which 'that' didn't have. If 'that' was frozen that is an error.
+  int this_size = this->exports_ == NULL ? 0 : this->exports_->occupancy();
+  int that_size = map == NULL ? 0 : map->occupancy();
+  if (that->IsFrozen() && this_size > that_size) {
+    *ok = false;
+    return;
+  }
+
+  // Merge interfaces.
+  this->flags_ |= that->flags_;
+  that->forward_ = this;
+}
+
+
+#ifdef DEBUG
+void Interface::Print(int n) {
+  int n0 = n > 0 ? n : 0;
+
+  if (FLAG_print_interface_details) {
+    PrintF("%p", static_cast<void*>(this));
+    for (Interface* link = this->forward_; link != NULL; link = link->forward_)
+      PrintF("->%p", static_cast<void*>(link));
+    PrintF(" ");
+  }
+
+  if (IsUnknown()) {
+    PrintF("unknown\n");
+  } else if (IsValue()) {
+    PrintF("value\n");
+  } else if (IsModule()) {
+    PrintF("module %s{", IsFrozen() ? "" : "(unresolved) ");
+    ZoneHashMap* map = Chase()->exports_;
+    if (map == NULL || map->occupancy() == 0) {
+      PrintF("}\n");
+    } else if (n < 0 || n0 >= 2 * FLAG_print_interface_depth) {
+      // Avoid infinite recursion on cyclic types.
+      PrintF("...}\n");
+    } else {
+      PrintF("\n");
+      for (ZoneHashMap::Entry* p = map->Start(); p != NULL; p = map->Next(p)) {
+        String* name = *static_cast<String**>(p->key);
+        Interface* interface = static_cast<Interface*>(p->value);
+        PrintF("%*s%s : ", n0 + 2, "", name->ToAsciiArray());
+        interface->Print(n0 + 2);
+      }
+      PrintF("%*s}\n", n0, "");
+    }
+  }
+}
+#endif
+
+} }  // namespace v8::internal