Disconnects code objects from infrequently used unoptimized functions.

runtime/vm/flow_graph_compiler_ia32.cc

Index: runtime/vm/flow_graph_compiler_ia32.cc
===================================================================
--- runtime/vm/flow_graph_compiler_ia32.cc	(revision 28803)
+++ runtime/vm/flow_graph_compiler_ia32.cc	(working copy)
@@ -8,6 +8,7 @@
 #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"
@@ -1098,6 +1099,31 @@
     ASSERT(StackSize() >= 0);
     __ EnterDartFrame(StackSize() * kWordSize);
   }
+
+  // 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 Immediate& raw_null =
+        Immediate(reinterpret_cast<intptr_t>(Object::null()));
+    const Register function_reg = EDI;
+    __ LoadObject(function_reg, function);
+    __ movl(EAX, FieldAddress(function_reg, Function::code_offset()));
+    __ cmpl(EAX, raw_null);
+    __ j(NOT_EQUAL, &is_connected, Assembler::kNearJump);

[srdjan, 2013/10/18 17:16:07]

Add comment what you are doing: add the code object back to function?

[zra, 2013/10/22 16:13:24]

Code obsolete.

+    __ movl(EAX, Address(EBP, kPcMarkerSlotFromFp * kWordSize));
+    const intptr_t code_pc_dist =
+      Instructions::HeaderSize() - Instructions::code_offset() +
+      Assembler::kEntryPointToPcMarkerOffset;

[srdjan, 2013/10/18 17:16:07]

Indent 4 chars the two lines above

[zra, 2013/10/22 16:13:24]

Code obsolete

+    __ movl(EAX, Address(EAX, -code_pc_dist));
+    __ movl(FieldAddress(function_reg, Function::code_offset()), EAX);
+    __ movl(
+        FieldAddress(function_reg, Function::unoptimized_code_offset()), EAX);
+    __ Bind(&is_connected);
+  }
 }
 
 
@@ -1412,8 +1438,27 @@
   // illegal class id was found, the target is a cache miss handler that can
   // be invoked as a normal Dart function.
   __ movl(EAX, FieldAddress(EDI, ECX, TIMES_4, base + kWordSize));
-  __ movl(EAX, FieldAddress(EAX, Function::code_offset()));
-  __ movl(EAX, FieldAddress(EAX, Code::instructions_offset()));
+  __ movl(EBX, FieldAddress(EAX, 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()));
+    __ cmpl(EBX, raw_null);
+    __ j(NOT_EQUAL, &is_compiled, Assembler::kNearJump);
+    __ EnterStubFrame();
+    __ pushl(EDX);  // Preserve arguments descriptor array.
+    __ pushl(ECX);  // Preserve IC data object.
+    __ pushl(EAX);  // Pass function.
+    __ CallRuntime(kCompileFunctionRuntimeEntry, 1);
+    __ popl(EAX);  // Restore function.

[srdjan, 2013/10/18 17:16:07]

The argument can be modified in the callee, therefore you need to do extra
saving/restoring of function.

[zra, 2013/10/22 16:13:24]

At other call-sites of CompileFunction (e.g. around stub_code_ia32.cc:720) there
are comments indicating the argument is read-only. If this is actually not true,
I'll preserve the function, and edit the comments at all call-sites.

+    __ popl(ECX);  // Restore IC data array.
+    __ popl(EDX);  // Restore arguments descriptor array.
+    __ LeaveFrame();
+    __ movl(EBX, FieldAddress(EAX, Function::code_offset()));
+    __ Bind(&is_compiled);
+  }
+  __ movl(EAX, FieldAddress(EBX, Code::instructions_offset()));
   __ LoadObject(ECX, ic_data);
   __ LoadObject(EDX, arguments_descriptor);
   __ addl(EAX, Immediate(Instructions::HeaderSize() - kHeapObjectTag));