Customized support for feedback on calls to Array.

src/hydrogen.cc

 // Copyright 2013 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 "hydrogen.h"
 
 #include <algorithm>
 
 #include "v8.h"
 #include "allocation-site-scopes.h"
@@ skipping 2450 matching lines @@
   double nan_double = FixedDoubleArray::hole_nan_as_double();
   HValue* hole = IsFastSmiOrObjectElementsKind(elements_kind)
       ? Add<HConstant>(factory->the_hole_value())
       : Add<HConstant>(nan_double);
 
   if (to == NULL) {
     to = AddLoadFixedArrayLength(elements);
   }
 
   // Special loop unfolding case
-  static const int kLoopUnfoldLimit = 8;
   STATIC_ASSERT(JSArray::kPreallocatedArrayElements <= kLoopUnfoldLimit);
   int initial_capacity = -1;
   if (from->IsInteger32Constant() && to->IsInteger32Constant()) {
     int constant_from = from->GetInteger32Constant();
     int constant_to = to->GetInteger32Constant();
 
     if (constant_from == 0 && constant_to <= kLoopUnfoldLimit) {
       initial_capacity = constant_to;
     }
   }
@@ skipping 5743 matching lines @@
     // as is it dropped on deserialization.
     CHECK(!Serializer::enabled(isolate()));
     Handle<JSObject> global_receiver(
         target->context()->global_object()->global_receiver());
     return Add<HConstant>(global_receiver);
   }
   return graph()->GetConstantUndefined();
 }
 
 
+void HOptimizedGraphBuilder::BuildArrayCall(Expression* expression,
+                                            int arguments_count,
+                                            HValue* function,
+                                            Handle<AllocationSite> site) {
+  Add<HCheckValue>(function, array_function());
+
+  if (IsCallArrayInlineable(arguments_count, site)) {
+    BuildInlinedCallArray(expression, arguments_count, site);
+    return;
+  }
+
+  HInstruction* call = PreProcessCall(New<HCallNewArray>(
+      function, arguments_count + 1, site->GetElementsKind()));
+  if (expression->IsCall()) {
+    Drop(1);
+  }
+  ast_context()->ReturnInstruction(call, expression->id());
+}
+
+
+bool HOptimizedGraphBuilder::TryHandleArrayCall(Call* expr, HValue* function) {
+  if (!array_function().is_identical_to(expr->target())) {
+    return false;
+  }
+
+  AllocationSiteInfo* site_info =
+      reinterpret_cast<AllocationSiteInfo*>(expr->extra_info());
+  if (site_info == NULL) return false;
+  Handle<AllocationSite> site = site_info->allocation_site();
+  if (site.is_null()) return false;
+
+  BuildArrayCall(expr,
+                 expr->arguments()->length(),
+                 function,
+                 site);
+  return true;
+}
+
+
+bool HOptimizedGraphBuilder::TryHandleArrayCallNew(CallNew* expr,
+                                                   HValue* function) {
+  if (!array_function().is_identical_to(expr->target())) {
+    return false;
+  }
+
+  BuildArrayCall(expr,
+                 expr->arguments()->length(),
+                 function,
+                 expr->allocation_site());
+  return true;
+}
+
+
 void HOptimizedGraphBuilder::VisitCall(Call* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   Expression* callee = expr->expression();
   int argument_count = expr->arguments()->length() + 1;  // Plus receiver.
   HInstruction* call = NULL;
 
   Property* prop = callee->AsProperty();
   if (prop != NULL) {
@@ skipping 74 matching lines @@
   } else {
     VariableProxy* proxy = expr->expression()->AsVariableProxy();
     if (proxy != NULL && proxy->var()->is_possibly_eval(isolate())) {
       return Bailout(kPossibleDirectCallToEval);
     }
 
     // The function is on the stack in the unoptimized code during
     // evaluation of the arguments.
     CHECK_ALIVE(VisitForValue(expr->expression()));
     HValue* function = Top();
-    bool global_call = proxy != NULL && proxy->var()->IsUnallocated();
-    if (global_call) {
+    if (expr->global_call()) {
       Variable* var = proxy->var();
       bool known_global_function = false;
       // If there is a global property cell for the name at compile time and
       // access check is not enabled we assume that the function will not change
       // and generate optimized code for calling the function.
       LookupResult lookup(isolate());
       GlobalPropertyAccess type = LookupGlobalProperty(var, &lookup, LOAD);
       if (type == kUseCell &&
           !current_info()->global_object()->IsAccessCheckNeeded()) {
         Handle<GlobalObject> global(current_info()->global_object());
@@ skipping 13 matching lines @@
 
         if (TryInlineBuiltinFunctionCall(expr)) {
           if (FLAG_trace_inlining) {
             PrintF("Inlining builtin ");
             expr->target()->ShortPrint();
             PrintF("\n");
           }
           return;
         }
         if (TryInlineApiFunctionCall(expr, receiver)) return;
+        if (TryHandleArrayCall(expr, function)) return;
         if (TryInlineCall(expr)) return;
 
         PushArgumentsFromEnvironment(argument_count);
         call = BuildCallConstantFunction(expr->target(), argument_count);
       } else {
         Push(graph()->GetConstantUndefined());
         CHECK_ALIVE(VisitExpressions(expr->arguments()));
         PushArgumentsFromEnvironment(argument_count);
         call = New<HCallFunction>(function, argument_count);
       }
@@ skipping 29 matching lines @@
       PushArgumentsFromEnvironment(argument_count);
       call = New<HCallFunction>(function, argument_count);
     }
   }
 
   Drop(1);  // Drop the function.
   return ast_context()->ReturnInstruction(call, expr->id());
 }
 
 
-void HOptimizedGraphBuilder::BuildInlinedCallNewArray(CallNew* expr) {
+void HOptimizedGraphBuilder::BuildInlinedCallArray(
+    Expression* expression,
+    int argument_count,
+    Handle<AllocationSite> site) {
+  ASSERT(!site.is_null());
   NoObservableSideEffectsScope no_effects(this);
 
-  int argument_count = expr->arguments()->length();
   // We should at least have the constructor on the expression stack.
   HValue* constructor = environment()->ExpressionStackAt(argument_count);
 
-  ElementsKind kind = expr->elements_kind();
-  Handle<AllocationSite> site = expr->allocation_site();
-  ASSERT(!site.is_null());
-
   // Register on the site for deoptimization if the transition feedback changes.
   AllocationSite::AddDependentCompilationInfo(
       site, AllocationSite::TRANSITIONS, top_info());
+  ElementsKind kind = site->GetElementsKind();
   HInstruction* site_instruction = Add<HConstant>(site);
 
   // In the single constant argument case, we may have to adjust elements kind
   // to avoid creating a packed non-empty array.
   if (argument_count == 1 && !IsHoleyElementsKind(kind)) {
     HValue* argument = environment()->Top();
     if (argument->IsConstant()) {
       HConstant* constant_argument = HConstant::cast(argument);
       ASSERT(constant_argument->HasSmiValue());
       int constant_array_size = constant_argument->Integer32Value();
       if (constant_array_size != 0) {
         kind = GetHoleyElementsKind(kind);
       }
     }
   }
 
   // Build the array.
   JSArrayBuilder array_builder(this,
                                kind,
                                site_instruction,
                                constructor,
                                DISABLE_ALLOCATION_SITES);
-  HValue* new_object;
+  HValue* new_object = NULL;
   if (argument_count == 0) {

[danno, 2014/05/16 16:34:11]

ASSERT(argument_count == 0); and remove the if.

[mvstanton, 2014/05/19 13:45:24]

I do need to support the 1 argument case too though. It's been vetted beforehand
to be a single argument within a range that prevents building a loop construct.
But I added the assert (>=0 && <=1) and compactified the expression that
initializes new_object.

     new_object = array_builder.AllocateEmptyArray();
   } else if (argument_count == 1) {
     HValue* argument = environment()->Top();
     new_object = BuildAllocateArrayFromLength(&array_builder, argument);
   } else {
-    HValue* length = Add<HConstant>(argument_count);
-    // Smi arrays need to initialize array elements with the hole because
-    // bailout could occur if the arguments don't fit in a smi.
-    //
-    // TODO(mvstanton): If all the arguments are constants in smi range, then
-    // we could set fill_with_hole to false and save a few instructions.
-    JSArrayBuilder::FillMode fill_mode = IsFastSmiElementsKind(kind)
-        ? JSArrayBuilder::FILL_WITH_HOLE
-        : JSArrayBuilder::DONT_FILL_WITH_HOLE;
-    new_object = array_builder.AllocateArray(length, length, fill_mode);
-    HValue* elements = array_builder.GetElementsLocation();
-    for (int i = 0; i < argument_count; i++) {
-      HValue* value = environment()->ExpressionStackAt(argument_count - i - 1);
-      HValue* constant_i = Add<HConstant>(i);
-      Add<HStoreKeyed>(elements, constant_i, value, kind);
-    }
+    UNREACHABLE();
   }
 
-  Drop(argument_count + 1);  // drop constructor and args.
+  int args_to_drop = argument_count + (expression->IsCall() ? 2 : 1);
+  Drop(args_to_drop);
   ast_context()->ReturnValue(new_object);
 }
 
 
 // Checks whether allocation using the given constructor can be inlined.
 static bool IsAllocationInlineable(Handle<JSFunction> constructor) {
   return constructor->has_initial_map() &&
       constructor->initial_map()->instance_type() == JS_OBJECT_TYPE &&
       constructor->initial_map()->instance_size() < HAllocate::kMaxInlineSize &&
       constructor->initial_map()->InitialPropertiesLength() == 0;
 }
 
 
-bool HOptimizedGraphBuilder::IsCallNewArrayInlineable(CallNew* expr) {
+bool HOptimizedGraphBuilder::IsCallArrayInlineable(
+    int argument_count,
+    Handle<AllocationSite> site) {
   Handle<JSFunction> caller = current_info()->closure();
-  Handle<JSFunction> target(isolate()->native_context()->array_function(),
-                            isolate());
-  int argument_count = expr->arguments()->length();
+  Handle<JSFunction> target = array_function();
   // We should have the function plus array arguments on the environment stack.
   ASSERT(environment()->length() >= (argument_count + 1));
-  Handle<AllocationSite> site = expr->allocation_site();
   ASSERT(!site.is_null());
 
   bool inline_ok = false;
   if (site->CanInlineCall()) {
     // We also want to avoid inlining in certain 1 argument scenarios.
     if (argument_count == 1) {
       HValue* argument = Top();
       if (argument->IsConstant()) {
         // Do not inline if the constant length argument is not a smi or
-        // outside the valid range for a fast array.
+        // outside the valid range for unrolled loop initialization.
         HConstant* constant_argument = HConstant::cast(argument);
         if (constant_argument->HasSmiValue()) {
           int value = constant_argument->Integer32Value();
-          inline_ok = value >= 0 &&
-              value < JSObject::kInitialMaxFastElementArray;
+          inline_ok = value >= 0 && value <= kLoopUnfoldLimit;
           if (!inline_ok) {
             TraceInline(target, caller,
-                        "Length outside of valid array range");
+                        "Constant length outside of valid inlining range.");
           }
         }
       } else {
-        inline_ok = true;
+        TraceInline(target, caller,
+                    "Dont inline [new] Array(n) where n isn't constant.");
       }
+    } else if (argument_count == 0) {
+      inline_ok = true;
     } else {
-      inline_ok = true;
+      TraceInline(target, caller, "Too many arguments to inline.");
     }
   } else {
     TraceInline(target, caller, "AllocationSite requested no inlining.");
   }
 
   if (inline_ok) {
     TraceInline(target, caller, NULL);
   }
   return inline_ok;
 }
@@ skipping 109 matching lines @@
     initial_map_value->DeleteAndReplaceWith(NULL);
     receiver->DeleteAndReplaceWith(NULL);
     check->DeleteAndReplaceWith(NULL);
     environment()->SetExpressionStackAt(receiver_index, function);
     HInstruction* call =
       PreProcessCall(New<HCallNew>(function, argument_count));
     return ast_context()->ReturnInstruction(call, expr->id());
   } else {
     // The constructor function is both an operand to the instruction and an
     // argument to the construct call.
-    Handle<JSFunction> array_function(
-        isolate()->native_context()->array_function(), isolate());
-    bool use_call_new_array = expr->target().is_identical_to(array_function);
-    if (use_call_new_array && IsCallNewArrayInlineable(expr)) {
-      // Verify we are still calling the array function for our native context.
-      Add<HCheckValue>(function, array_function);
-      BuildInlinedCallNewArray(expr);
-      return;
-    }
+    if (TryHandleArrayCallNew(expr, function)) return;
 
-    HBinaryCall* call;
-    if (use_call_new_array) {
-      Add<HCheckValue>(function, array_function);
-      call = New<HCallNewArray>(function, argument_count,
-                                expr->elements_kind());
-    } else {
-      call = New<HCallNew>(function, argument_count);
-    }
-    PreProcessCall(call);
+    HInstruction* call =
+        PreProcessCall(New<HCallNew>(function, argument_count));
     return ast_context()->ReturnInstruction(call, expr->id());
   }
 }
 
 
 // Support for generating inlined runtime functions.
 
 // Lookup table for generators for runtime calls that are generated inline.
 // Elements of the table are member pointers to functions of
 // HOptimizedGraphBuilder.
@@ skipping 3118 matching lines @@
   if (ShouldProduceTraceOutput()) {
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 } }  // namespace v8::internal