[VM DBC compiler and simulator] Support reified generic functions.

runtime/vm/flow_graph_compiler_dbc.cc

 // Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_DBC.
 #if defined(TARGET_ARCH_DBC)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
@@ skipping 365 matching lines @@
       __ Frame(num_locals);    // Reserve space for locals.
     } else if (flow_graph_.graph_entry()->spill_slot_count() >
                flow_graph_.num_copied_params()) {
       __ Frame(flow_graph_.graph_entry()->spill_slot_count() -
                flow_graph_.num_copied_params());
     }
   }
 
   if (function.IsClosureFunction()) {
     // In optimized mode the register allocator expects CurrentContext in the
-    // flow_graph_.num_copied_params() register at function entry.
+    // flow_graph_.num_copied_params() register at function entry, unless that
+    // register is used for function type arguments, either as their
+    // permanent location or as their temporary location when captured.
+    // In that case, the next register holds CurrentContext.
     // (see FlowGraphAllocator::ProcessInitialDefinition)
     Register context_reg =
-        is_optimizing() ? flow_graph_.num_copied_params() : context_index;
+        is_optimizing() ? ((parsed_function().function_type_arguments() != NULL)

[Vyacheslav Egorov (Google), 2017/08/16 05:27:36]

The code below uses FLAG_reify_generic_functions && function.IsGeneric() and
here we use (parsed_function().function_type_arguments() != NULL).

Is it possible to unify these conditions?

Maybe even make

const bool has_type_arguments = ...

[regis, 2017/08/16 17:47:48]

Done.
I also unified with the code in FlowGraphAllocator::ProcessInitialDefinition.

+                               ? flow_graph_.num_copied_params() + 1
+                               : flow_graph_.num_copied_params())
+                        : context_index;
     LocalScope* scope = parsed_function().node_sequence()->scope();
-    LocalVariable* local = scope->VariableAt(0);
+    LocalVariable* local = scope->VariableAt(0);  // Closure instance receiver.
 
     Register closure_reg;
     if (local->index() > 0) {
       __ Move(context_reg, -local->index());
       closure_reg = context_reg;
     } else {
       closure_reg = -local->index() - 1;
     }
     __ LoadField(context_reg, closure_reg,
                  Closure::context_offset() / kWordSize);
   } else if (has_optional_params && !is_optimizing()) {
     __ LoadConstant(context_index, Object::empty_context());
   }
 
   // Check for a passed type argument vector if the function is generic.
   if (FLAG_reify_generic_functions && function.IsGeneric() &&
       !flow_graph().IsCompiledForOsr()) {
-    __ Comment("Check passed-in type args");
-    UNIMPLEMENTED();  // TODO(regis): Not yet supported.
+    ASSERT(-parsed_function().first_stack_local_index() - 1 ==
+           flow_graph_.num_copied_params());
+    __ CheckFunctionTypeArgs(function.NumTypeParameters(),
+                             flow_graph_.num_copied_params());
   }
+
+  // TODO(regis): Verify that no vector is passed if not generic, unless already
+  // checked during resolution.
 }
 
 void FlowGraphCompiler::CompileGraph() {
   InitCompiler();
 
   if (TryIntrinsify()) {
     // Skip regular code generation.
     return;
   }
 
@@ skipping 124 matching lines @@
 
 void ParallelMoveResolver::RestoreFpuScratch(FpuRegister reg) {
   UNIMPLEMENTED();
 }
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC