First step toward an optimizing compiler:

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
===================================================================
--- runtime/vm/flow_graph_compiler_x64.cc	(revision 7907)
+++ runtime/vm/flow_graph_compiler_x64.cc	(working copy)
@@ -32,7 +32,52 @@
 DECLARE_FLAG(bool, report_usage_count);
 DECLARE_FLAG(bool, code_comments);
 
+class DeoptimizationStub : public ZoneAllocated {
+ public:
+  DeoptimizationStub(intptr_t deopt_id,
+                     intptr_t deopt_token_index,
+                     intptr_t try_index,
+                     DeoptReasonId reason)
+      : deopt_id_(deopt_id),
+        deopt_token_index_(deopt_token_index),
+        try_index_(try_index),
+        reason_(reason),
+        registers_(2),
+        entry_label_() {}
 
+  void Push(Register reg) { registers_.Add(reg); }
+  Label* entry_label() { return &entry_label_; }
+
+  void GenerateCode(FlowGraphCompiler* compiler);
+
+ private:
+  const intptr_t deopt_id_;
+  const intptr_t deopt_token_index_;
+  const intptr_t try_index_;
+  const DeoptReasonId reason_;
+  GrowableArray<Register> registers_;
+  Label entry_label_;
+
+  DISALLOW_COPY_AND_ASSIGN(DeoptimizationStub);
+};
+
+
+void DeoptimizationStub::GenerateCode(FlowGraphCompiler* compiler) {
+  Assembler* assem = compiler->assembler();
+  assem->Comment("Deopt stub for id %d", deopt_id_);
+  assem->Bind(entry_label());

[Florian Schneider, 2012/05/24 00:20:39]

Maybe make a temporary definition of the __ macro for better readability?

[srdjan, 2012/05/24 01:36:26]

Done

+  for (intptr_t i = 0; i < registers_.length(); i++) {
+    assem->pushq(registers_[i]);
+  }
+  assem->movq(RAX, Immediate(Smi::RawValue(reason_)));
+  assem->call(&StubCode::DeoptimizeLabel());
+  compiler->AddCurrentDescriptor(PcDescriptors::kOther,
+                                 deopt_id_,
+                                 deopt_token_index_,
+                                 try_index_);
+}
+
+
 FlowGraphCompiler::FlowGraphCompiler(
     Assembler* assembler,
     const ParsedFunction& parsed_function,
@@ -45,6 +90,7 @@
       current_block_(NULL),
       pc_descriptors_list_(NULL),
       exception_handlers_list_(NULL),
+      deopt_stubs_(),
       is_optimizing_(is_optimizing) {
 }
 
@@ -1317,6 +1363,11 @@
 }
 
 
+void FlowGraphCompiler::VisitBinaryOp(BinaryOpComp* comp) {
+  UNIMPLEMENTED();
+}
+
+
 void FlowGraphCompiler::EmitInstructionPrologue(Instruction* instr) {
   LocationSummary* locs = instr->locs();
   ASSERT(locs != NULL);
@@ -1857,6 +1908,7 @@
   VisitBlocks();
 
   __ int3();
+  GenerateDeferredCode();
   // Emit function patching code. This will be swapped with the first 13 bytes
   // at entry point.
   pc_descriptors_list_->AddDescriptor(PcDescriptors::kPatchCode,
@@ -1868,6 +1920,13 @@
 }
 
 
+void FlowGraphCompiler::GenerateDeferredCode() {
+  for (intptr_t i = 0; i < deopt_stubs_.length(); i++) {
+    deopt_stubs_[i]->GenerateCode(this);
+  }
+}
+
+
 // Infrastructure copied from class CodeGenerator.
 void FlowGraphCompiler::GenerateCall(intptr_t token_index,
                                      intptr_t try_index,
@@ -1900,6 +1959,21 @@
 }
 
 
+Label* FlowGraphCompiler::AddDeoptStub(intptr_t deopt_id,
+                                       intptr_t deopt_token_index,
+                                       intptr_t try_index,
+                                       DeoptReasonId reason,
+                                       Register reg1,
+                                       Register reg2) {
+  DeoptimizationStub* stub =
+      new DeoptimizationStub(deopt_id, deopt_token_index, try_index, reason);
+  stub->Push(reg1);
+  stub->Push(reg2);
+  deopt_stubs_.Add(stub);
+  return stub->entry_label();
+}
+
+
 void FlowGraphCompiler::FinalizePcDescriptors(const Code& code) {
   ASSERT(pc_descriptors_list_ != NULL);
   const PcDescriptors& descriptors = PcDescriptors::Handle(