Disconnects code objects from infrequently used unoptimized functions.

runtime/vm/stub_code_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"
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/assembler.h"
 #include "vm/compiler.h"
 #include "vm/dart_entry.h"
@@ skipping 1582 matching lines @@
   const intptr_t target_offset = ICData::TargetIndexFor(num_args) * kWordSize;
   const intptr_t count_offset = ICData::CountIndexFor(num_args) * kWordSize;
   __ movq(RAX, Address(R12, target_offset));
   __ addq(Address(R12, count_offset), Immediate(Smi::RawValue(1)));
   __ j(NO_OVERFLOW, &call_target_function, Assembler::kNearJump);
   __ movq(Address(R12, count_offset),
           Immediate(Smi::RawValue(Smi::kMaxValue)));
 
   __ Bind(&call_target_function);
   // RAX: Target function.
-  __ movq(RAX, FieldAddress(RAX, Function::code_offset()));
-  __ movq(RAX, FieldAddress(RAX, Code::instructions_offset()));
+  Label is_compiled;
+  __ movq(RCX, FieldAddress(RAX, Function::code_offset()));
+  if (FLAG_collect_code) {
+    // If code might be GC'd, then EBX might be null. If it is, recompile.
+    __ CompareObject(RCX, Object::null_object(), PP);
+    __ j(NOT_EQUAL, &is_compiled, Assembler::kNearJump);
+    __ EnterStubFrame();
+    __ pushq(R10);  // Preserve arguments descriptor array.
+    __ pushq(RBX);  // Preserve IC data object.
+    __ pushq(RAX);  // Pass function.
+    __ CallRuntime(kCompileFunctionRuntimeEntry, 1);
+    __ popq(RAX);  // Restore function.
+    __ popq(RBX);  // Restore IC data array.
+    __ popq(R10);  // Restore arguments descriptor array.
+    __ LeaveFrame();
+    __ movq(RCX, FieldAddress(RAX, Function::code_offset()));
+    __ Bind(&is_compiled);
+  }
+  __ movq(RAX, FieldAddress(RCX, Code::instructions_offset()));
   __ addq(RAX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));
   __ jmp(RAX);
 
   __ Bind(&get_class_id_as_smi);
   Label not_smi;
   // Test if Smi -> load Smi class for comparison.
   __ testq(RAX, Immediate(kSmiTagMask));
   __ j(NOT_ZERO, &not_smi, Assembler::kNearJump);
   __ movq(RAX, Immediate(Smi::RawValue(kSmiCid)));
   __ ret();
@@ skipping 160 matching lines @@
 }
 
 
 void StubCode::GenerateTwoArgsUnoptimizedStaticCallStub(Assembler* assembler) {
   GenerateUsageCounterIncrement(assembler, RCX);
   GenerateNArgsCheckInlineCacheStub(
       assembler, 2, kStaticCallMissHandlerTwoArgsRuntimeEntry);
 }
 
 
+// Stub for calling the CompileFunction runtime call.
+// RCX: IC-Data.
+// RDX: Arguments descriptor.
+// RAX: Function.
+void StubCode::GenerateCompileFunctionRuntimeCallStub(Assembler* assembler) {
+  __ 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();
+  __ ret();
+}
+
+
 //  RBX, R10: May contain arguments to runtime stub.
 //  TOS(0): return address (Dart code).
 void StubCode::GenerateBreakpointRuntimeStub(Assembler* assembler) {
   __ EnterStubFrame();
   // Preserve runtime args.
   __ pushq(RBX);
   __ pushq(R10);
   // Room for result. Debugger stub returns address of the
   // unpatched runtime stub.
   __ LoadObject(R12, Object::null_object(), PP);
@@ skipping 339 matching lines @@
   __ movq(right, Address(RSP, 3 * kWordSize));
   GenerateIdenticalWithNumberCheckStub(assembler, left, right);
   __ popq(right);
   __ popq(left);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_X64