VM: [Kernel] Implement CatchBlockEntryInstr::should_restore_closure_context on all platforms.

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 382 matching lines @@
       ASSERT(num_locals > 0);  // There is always at least context_var.
       __ 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()) {
-    Register reg =
+    // In optimized mode the register allocator expects CurrentContext in the
+    // flow_graph_.num_copied_params() register at function entry.
+    // (see FlowGraphAllocator::ProcessInitialDefinition)
+    Register context_reg =
         is_optimizing() ? flow_graph_.num_copied_params() : context_index;
-    Register closure_reg = reg;
     LocalScope* scope = parsed_function().node_sequence()->scope();
     LocalVariable* local = scope->VariableAt(0);
+
+    Register closure_reg;
     if (local->index() > 0) {
-      __ Move(reg, -local->index());
+      __ Move(context_reg, -local->index());
+      closure_reg = context_reg;
     } else {
       closure_reg = -local->index() - 1;
     }
-    __ LoadField(reg, closure_reg, Closure::context_offset() / kWordSize);
+    __ LoadField(context_reg, closure_reg,
+                 Closure::context_offset() / kWordSize);
   } else if (has_optional_params && !is_optimizing()) {
     __ LoadConstant(context_index, Object::empty_context());
   }
 }
 
 
 void FlowGraphCompiler::CompileGraph() {
   InitCompiler();
 
   if (TryIntrinsify()) {
     // Skip regular code generation.
     return;
   }
 
   EmitFrameEntry();
   VisitBlocks();
 }
 
 
 uint16_t FlowGraphCompiler::ToEmbeddableCid(intptr_t cid,
                                             Instruction* instruction) {
   if (!Utils::IsUint(16, cid)) {
     instruction->Unsupported(this);
     UNREACHABLE();
   }
   return static_cast<uint16_t>(cid);
 }
 
 
+intptr_t FlowGraphCompiler::CatchEntryRegForVariable(const LocalVariable& var) {
+  ASSERT(is_optimizing());
+  ASSERT(var.index() <= 0);
+  return kNumberOfCpuRegisters -
+         (flow_graph().num_non_copied_params() - var.index());
+}
+
+
 #undef __
 #define __ compiler_->assembler()->
 
 
 void ParallelMoveResolver::EmitMove(int index) {
   MoveOperands* move = moves_[index];
   const Location source = move->src();
   const Location destination = move->dest();
   if (source.IsStackSlot() && destination.IsRegister()) {
     // Only allow access to the arguments.
@@ skipping 107 matching lines @@
 void ParallelMoveResolver::RestoreFpuScratch(FpuRegister reg) {
   UNIMPLEMENTED();
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_DBC