Disconnects code objects from infrequently used unoptimized functions.

runtime/vm/flow_graph_compiler_x64.cc

 // Copyright (c) 2013, 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_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/flow_graph_compiler.h"
 
 #include "vm/ast_printer.h"
+#include "vm/compiler.h"
 #include "vm/dart_entry.h"
 #include "vm/deopt_instructions.h"
 #include "vm/il_printer.h"
 #include "vm/locations.h"
 #include "vm/object_store.h"
 #include "vm/parser.h"
 #include "vm/stack_frame.h"
 #include "vm/stub_code.h"
 #include "vm/symbols.h"
 
@@ skipping 1103 matching lines @@
   if (flow_graph().IsCompiledForOsr()) {
     intptr_t extra_slots = StackSize()
         - flow_graph().num_stack_locals()
         - flow_graph().num_copied_params();
     ASSERT(extra_slots >= 0);
     __ EnterOsrFrame(extra_slots * kWordSize, new_pp, new_pc);
   } else {
     ASSERT(StackSize() >= 0);
     __ EnterDartFrameWithInfo(StackSize() * kWordSize, new_pp, new_pc);
   }
+
+  // TODO(zra): maybe do this only before we try to optimize?
+  if (FLAG_collect_code) {
+    // If we are collecting code, make sure this function still has a pointer
+    // to the code object.
+    // TODO(zra): Is it cheaper just to write the Function fields with the
+    // code object without doing the test?
+    Label is_connected;
+    const Register function_reg = RDI;
+    __ LoadObject(function_reg, function, PP);
+    __ movq(RAX, FieldAddress(function_reg, Function::code_offset()));
+    __ CompareObject(RAX, Object::null_object(), PP);
+    __ j(NOT_EQUAL, &is_connected, Assembler::kNearJump);
+    __ movq(RAX, Address(RBP, kPcMarkerSlotFromFp * kWordSize));
+    const intptr_t code_pc_dist =
+      Instructions::HeaderSize() - Instructions::code_offset() +
+      Assembler::kEntryPointToPcMarkerOffset;
+    __ movq(RAX, Address(RAX, -code_pc_dist));
+    __ movq(FieldAddress(function_reg, Function::code_offset()), RAX);
+    __ movl(
+        FieldAddress(function_reg, Function::unoptimized_code_offset()), RAX);
+    __ Bind(&is_connected);
+  }
 }
 
 
 void FlowGraphCompiler::CompileGraph() {
   InitCompiler();
 
   TryIntrinsify();
 
   EmitFrameEntry();
 
@@ skipping 296 matching lines @@
   __ j(ZERO, &call_target_function, Assembler::kNearJump);
   __ cmpq(RDX, RAX);
   __ j(NOT_EQUAL, &update, Assembler::kNearJump);
 
   __ Bind(&call_target_function);
   // Call the target found in the cache.  For a class id match, this is a
   // proper target for the given name and arguments descriptor.  If the
   // illegal class id was found, the target is a cache miss handler that can
   // be invoked as a normal Dart function.
   __ movq(RAX, FieldAddress(RDI, RCX, TIMES_8, base + kWordSize));
-  __ movq(RAX, FieldAddress(RAX, Function::code_offset()));
-  __ movq(RAX, FieldAddress(RAX, Code::instructions_offset()));
+  __ movq(RBX, FieldAddress(RAX, Function::code_offset()));
+  if (FLAG_collect_code) {
+    // If we are collecting code, the code object may be null.
+    Label is_compiled;
+    const Immediate& raw_null =
+        Immediate(reinterpret_cast<intptr_t>(Object::null()));
+    __ cmpq(RBX, raw_null);
+    __ j(NOT_EQUAL, &is_compiled, Assembler::kNearJump);
+    __ EnterStubFrame();
+    __ pushq(RDX);  // Preserve arguments descriptor array.
+    __ pushq(RCX);  // Preserve IC data object.
+    __ pushq(RAX);  // Pass function.
+    __ CallRuntime(kCompileFunctionRuntimeEntry, 1);
+    __ popq(RAX);  // Restore function.
+    __ popq(RCX);  // Restore IC data array.
+    __ popq(RDX);  // Restore arguments descriptor array.
+    __ LeaveFrame();
+    __ movq(RBX, FieldAddress(RAX, Function::code_offset()));
+    __ Bind(&is_compiled);
+  }
+  __ movq(RAX, FieldAddress(RBX, Code::instructions_offset()));
   __ LoadObject(RBX, ic_data, PP);
   __ LoadObject(R10, arguments_descriptor, PP);
   __ AddImmediate(
       RAX, Immediate(Instructions::HeaderSize() - kHeapObjectTag), PP);
   __ call(RAX);
   AddCurrentDescriptor(PcDescriptors::kOther, Isolate::kNoDeoptId, token_pos);
   RecordSafepoint(locs);
   AddDeoptIndexAtCall(Isolate::ToDeoptAfter(deopt_id), token_pos);
   __ Drop(argument_count);
 }
@@ skipping 472 matching lines @@
   __ movups(reg, Address(RSP, 0));
   __ AddImmediate(RSP, Immediate(kFpuRegisterSize), PP);
 }
 
 
 #undef __
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64