Disconnects code objects from infrequently used unoptimized functions.

runtime/vm/stub_code_mips.cc

Index: runtime/vm/stub_code_mips.cc
===================================================================
--- runtime/vm/stub_code_mips.cc	(revision 28803)
+++ runtime/vm/stub_code_mips.cc	(working copy)
@@ -1812,8 +1812,26 @@
 
   __ Bind(&call_target_function);
   // T3: Target function.
-  __ lw(T3, FieldAddress(T3, Function::code_offset()));
-  __ lw(T3, FieldAddress(T3, Code::instructions_offset()));
+  Label is_compiled;
+  __ lw(T4, FieldAddress(T3, Function::code_offset()));
+  if (FLAG_collect_code) {
+    __ BranchNotEqual(T4, reinterpret_cast<int32_t>(Object::null()),
+                      &is_compiled);
+    __ EnterStubFrame();
+    __ addiu(SP, SP, Immediate(-3 * kWordSize));
+    __ sw(S5, Address(SP, 2 * kWordSize));  // Preserve IC data.
+    __ sw(S4, Address(SP, 1 * kWordSize));  // Preserve arg desc.
+    __ sw(T3, Address(SP, 0 * kWordSize));  // Function argument.
+    __ CallRuntime(kCompileFunctionRuntimeEntry, 1);
+    __ lw(T3, Address(SP, 0 * kWordSize));  // Restore Function.
+    __ lw(S4, Address(SP, 1 * kWordSize));  // Restore arg desc.
+    __ lw(S5, Address(SP, 2 * kWordSize));  // Restore IC data.
+    __ addiu(SP, SP, Immediate(3 * kWordSize));
+    __ LeaveStubFrame();
+    __ lw(T4, FieldAddress(T3, Function::code_offset()));
+    __ Bind(&is_compiled);
+  }
+  __ lw(T3, FieldAddress(T4, Code::instructions_offset()));
   __ AddImmediate(T3, Instructions::HeaderSize() - kHeapObjectTag);
   __ jr(T3);