Adapt arguments when inlining C++ builtins

src/compiler/js-typed-lowering.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/compiler/js-typed-lowering.h"
 
 #include "src/builtins/builtins-utils.h"
 #include "src/code-factory.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
@@ skipping 1487 matching lines @@
   node->ReplaceInput(2, rglobal);
   node->ReplaceInput(3, control);
   node->TrimInputCount(4);
   NodeProperties::ChangeOp(node,
                            common()->Phi(MachineRepresentation::kTagged, 3));
   return Changed(node);
 }
 
 namespace {
 
+static const int kStubAndReceiver = 2;
+
+// Adapts arguments if required and returns the number of JS arguments. This
+// is always the number of formal arguments if we're adapting, and the current
+// arity otherwise.
+int MaybeAdaptArguments(Isolate* isolate, JSGraph* jsgraph, Node* node,
+                        int arity, SharedFunctionInfo* shared) {
+  const int formal_parameter_count = shared->internal_formal_parameter_count();
+  const bool should_adapt_arguments =
+      formal_parameter_count != SharedFunctionInfo::kDontAdaptArgumentsSentinel;
+
+  if (!should_adapt_arguments) return arity;
+
+  if (arity < formal_parameter_count) {
+    // Fewer actual than formal parameters, push the rest as undefined.
+    Node* undefined = jsgraph->UndefinedConstant();
+    for (int i = arity; i < formal_parameter_count; i++) {
+      node->InsertInput(jsgraph->zone(), arity + kStubAndReceiver, undefined);
+    }
+  } else if (arity > formal_parameter_count) {
+    // More actual than formal parameters, remove trailing parameters.
+    for (int i = formal_parameter_count; i < arity; i++) {
+      node->RemoveInput(formal_parameter_count + kStubAndReceiver);
+    }
+  }
+
+  return formal_parameter_count;
+}
+
 void ReduceBuiltin(Isolate* isolate, JSGraph* jsgraph, Node* node,
                    int builtin_index, int arity, CallDescriptor::Flags flags) {
   // Patch {node} to a direct CEntryStub call.
   //
   // ----------- A r g u m e n t s -----------
   // -- 0: CEntryStub
   // --- Stack args ---
   // -- 1: receiver
   // -- [2, 2 + n[: the n actual arguments passed to the builtin
   // -- 2 + n: argc, including the receiver and implicit args (Smi)
   // -- 2 + n + 1: target
   // -- 2 + n + 2: new_target
   // --- Register args ---
   // -- 2 + n + 3: the C entry point
   // -- 2 + n + 4: argc (Int32)
   // -----------------------------------
 
   // The logic contained here is mirrored in Builtins::Generate_Adaptor.
   // Keep these in sync.
 
   const bool is_construct = (node->opcode() == IrOpcode::kJSCallConstruct);
 
   DCHECK(Builtins::HasCppImplementation(builtin_index));
 
+  Zone* zone = jsgraph->zone();
   Node* target = NodeProperties::GetValueInput(node, 0);
   Node* new_target = is_construct
                          ? NodeProperties::GetValueInput(node, arity + 1)
                          : jsgraph->UndefinedConstant();
 
+  Type* target_type = NodeProperties::GetType(target);
+  DCHECK(target_type->IsConstant());
+
   // API and CPP builtins are implemented in C++, and we can inline both.
   // CPP builtins create a builtin exit frame, API builtins don't.
   const bool has_builtin_exit_frame = Builtins::IsCpp(builtin_index);
-
   Node* stub = jsgraph->CEntryStubConstant(1, kDontSaveFPRegs, kArgvOnStack,
                                            has_builtin_exit_frame);
   node->ReplaceInput(0, stub);
 
-  Zone* zone = jsgraph->zone();
   if (is_construct) {
     // Unify representations between construct and call nodes.
     // Remove new target and add receiver as a stack parameter.
     Node* receiver = jsgraph->UndefinedConstant();
     node->RemoveInput(arity + 1);
     node->InsertInput(zone, 1, receiver);
   }
 
-  const int argc = arity + BuiltinArguments::kNumExtraArgsWithReceiver;
+  Handle<JSFunction> function =
+      Handle<JSFunction>::cast(target_type->AsConstant()->Value());
+  const int adapted_arity =
+      MaybeAdaptArguments(isolate, jsgraph, node, arity, function->shared());
+
+  const int argc = adapted_arity + BuiltinArguments::kNumExtraArgsWithReceiver;
   Node* argc_node = jsgraph->Int32Constant(argc);
 
-  node->InsertInput(zone, arity + 2, argc_node);
-  node->InsertInput(zone, arity + 3, target);
-  node->InsertInput(zone, arity + 4, new_target);
+  int cursor = adapted_arity + kStubAndReceiver;
+  node->InsertInput(zone, cursor++, argc_node);
+  node->InsertInput(zone, cursor++, target);
+  node->InsertInput(zone, cursor++, new_target);
 
   Address entry = Builtins::CppEntryOf(builtin_index);
   ExternalReference entry_ref(ExternalReference(entry, isolate));
   Node* entry_node = jsgraph->ExternalConstant(entry_ref);
 
-  node->InsertInput(zone, arity + 5, entry_node);
-  node->InsertInput(zone, arity + 6, argc_node);
+  node->InsertInput(zone, cursor++, entry_node);
+  node->InsertInput(zone, cursor++, argc_node);
 
   static const int kReturnCount = 1;
   const char* debug_name = Builtins::name(builtin_index);
   Operator::Properties properties = node->op()->properties();
   CallDescriptor* desc = Linkage::GetCEntryStubCallDescriptor(
       zone, kReturnCount, argc, debug_name, properties, flags);
 
   NodeProperties::ChangeOp(node, jsgraph->common()->Call(desc));
 }
 
@@ skipping 14 matching lines @@
   if (target_type->IsConstant() &&
       target_type->AsConstant()->Value()->IsJSFunction()) {
     Handle<JSFunction> function =
         Handle<JSFunction>::cast(target_type->AsConstant()->Value());
     Handle<SharedFunctionInfo> shared(function->shared(), isolate());
     const int builtin_index = shared->construct_stub()->builtin_index();
     const bool is_builtin = (builtin_index != -1);
 
     CallDescriptor::Flags flags = CallDescriptor::kNeedsFrameState;
 
-    if (is_builtin && Builtins::HasCppImplementation(builtin_index) &&
-        (shared->internal_formal_parameter_count() == arity ||
-         shared->internal_formal_parameter_count() ==
-             SharedFunctionInfo::kDontAdaptArgumentsSentinel)) {
+    if (is_builtin && Builtins::HasCppImplementation(builtin_index)) {
       // Patch {node} to a direct CEntryStub call.
 
       // Load the context from the {target}.
       Node* context = effect = graph()->NewNode(
           simplified()->LoadField(AccessBuilder::ForJSFunctionContext()),
           target, effect, control);
       NodeProperties::ReplaceContextInput(node, context);
 
       // Update the effect dependency for the {node}.
       NodeProperties::ReplaceEffectInput(node, effect);
@@ skipping 91 matching lines @@
     NodeProperties::ReplaceEffectInput(node, effect);
 
     // Compute flags for the call.
     CallDescriptor::Flags flags = CallDescriptor::kNeedsFrameState;
     if (p.tail_call_mode() == TailCallMode::kAllow) {
       flags |= CallDescriptor::kSupportsTailCalls;
     }
 
     Node* new_target = jsgraph()->UndefinedConstant();
     Node* argument_count = jsgraph()->Int32Constant(arity);
-    if (is_builtin && Builtins::HasCppImplementation(builtin_index) &&
-        (shared->internal_formal_parameter_count() == arity ||
-         shared->internal_formal_parameter_count() ==
-             SharedFunctionInfo::kDontAdaptArgumentsSentinel)) {
+    if (is_builtin && Builtins::HasCppImplementation(builtin_index)) {
       // Patch {node} to a direct CEntryStub call.
       ReduceBuiltin(isolate(), jsgraph(), node, builtin_index, arity, flags);
     } else if (shared->internal_formal_parameter_count() == arity ||
                shared->internal_formal_parameter_count() ==
                    SharedFunctionInfo::kDontAdaptArgumentsSentinel) {
       // Patch {node} to a direct call.
       node->InsertInput(graph()->zone(), arity + 2, new_target);
       node->InsertInput(graph()->zone(), arity + 3, argument_count);
       NodeProperties::ChangeOp(node,
                                common()->Call(Linkage::GetJSCallDescriptor(
@@ skipping 495 matching lines @@
 }
 
 
 CompilationDependencies* JSTypedLowering::dependencies() const {
   return dependencies_;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8