Check for a passed-in type argument vector in the prolog of generic functions.

runtime/vm/stub_code_x64.cc

Index: runtime/vm/stub_code_x64.cc
diff --git a/runtime/vm/stub_code_x64.cc b/runtime/vm/stub_code_x64.cc
index d60227d207974dda81aad9bf566edd88aeef2b17..f679a748d4b9bae0f9ba9808bd84b11b6bcb1810 100644
--- a/runtime/vm/stub_code_x64.cc
+++ b/runtime/vm/stub_code_x64.cc
@@ -833,6 +833,15 @@ void StubCode::GenerateInvokeDartCodeStub(Assembler* assembler) {
   // Push arguments. At this point we only need to preserve kTargetCodeReg.
   ASSERT(kTargetCodeReg != RDX);
 
+  // TODO(regis): Do we need to support type arguments when calling from C++?

[rmacnak, 2017/06/14 00:14:20]

Or mirrors? *cringe*

Let's not add this until there's a specific request for it.

[regis, 2017/06/14 21:02:05]

Agreed.

+  // TODO(regis): Add this check or proper implementation to other platforms.
+  __ cmpq(FieldAddress(R10, ArgumentsDescriptor::type_args_len_offset()),
+          Immediate(0));
+  Label no_type_args;
+  __ j(EQUAL, &no_type_args, Assembler::kNearJump);
+  __ int3();
+  __ Bind(&no_type_args);
+
   // Load number of arguments into RBX.
   __ movq(RBX, FieldAddress(R10, ArgumentsDescriptor::count_offset()));
   __ SmiUntag(RBX);