Vector-ICs: Implement slot sharing for global loads.

test/cctest/test-feedback-vector.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 #include "test/cctest/cctest.h"
 
 #include "src/api.h"
 #include "src/debug.h"
 #include "src/execution.h"
@@ skipping 289 matching lines @@
   CompileRun("f({ blarg: 3, gran: 3, torino: 10, foo: 2 })");
   CHECK_EQ(MEGAMORPHIC, nexus.StateFromFeedback());
   CHECK(!nexus.FindFirstMap());
 
   // After a collection, state should not be reset to PREMONOMORPHIC.
   heap->CollectAllGarbage(i::Heap::kNoGCFlags);
   CHECK_EQ(MEGAMORPHIC, nexus.StateFromFeedback());
 }
 
 
+TEST(VectorLoadICSlotSharing) {
+  if (i::FLAG_always_opt || !i::FLAG_vector_ics) return;
+  CcTest::InitializeVM();
+  LocalContext context;
+  v8::HandleScope scope(context->GetIsolate());
+  Isolate* isolate = CcTest::i_isolate();
+
+  // Function f has 3 LoadICs, one for each o, but the ICs share the same
+  // feedback vector IC slot.
+  CompileRun(
+      "var o = 10;"
+      "function f() {"
+      "  var x = o + 10;"
+      "  return o + x + o;"
+      "}"
+      "f();");
+  Handle<JSFunction> f = v8::Utils::OpenHandle(
+      *v8::Handle<v8::Function>::Cast(CcTest::global()->Get(v8_str("f"))));
+  // There should be one IC slot.
+  Handle<TypeFeedbackVector> feedback_vector =
+      Handle<TypeFeedbackVector>(f->shared()->feedback_vector(), isolate);
+  CHECK_EQ(1, feedback_vector->ICSlots());
+  FeedbackVectorICSlot slot(0);
+  LoadICNexus nexus(feedback_vector, slot);
+  CHECK_EQ(MONOMORPHIC, nexus.StateFromFeedback());
+}
+
+
 TEST(VectorLoadICOnSmi) {
   if (i::FLAG_always_opt || !i::FLAG_vector_ics) return;
   CcTest::InitializeVM();
   LocalContext context;
   v8::HandleScope scope(context->GetIsolate());
   Isolate* isolate = CcTest::i_isolate();
   Heap* heap = isolate->heap();
 
   // Make sure function f has a call that uses a type feedback slot.
   CompileRun(
@@ skipping 37 matching lines @@
   CHECK(number_map_found && o_map_found);
 
   // The degree of polymorphism doesn't change.
   CompileRun("f(100)");
   CHECK_EQ(POLYMORPHIC, nexus.StateFromFeedback());
   MapHandleList maps2;
   nexus.FindAllMaps(&maps2);
   CHECK_EQ(2, maps2.length());
 }
 }