Support for precise stepping in functions compiled before debugging was started (step 1)

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index 3b0e96f1ef93793398b98eb7a5daa50ca1c156a6..6ef90c045f7fa7952ef563471bc24bf547b0c0e4 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -2945,13 +2945,35 @@ void Code::set_optimizable(bool value) {
 
 bool Code::has_deoptimization_support() {
   ASSERT(kind() == FUNCTION);
-  return READ_BYTE_FIELD(this, kHasDeoptimizationSupportOffset) == 1;
+  return ((READ_BYTE_FIELD(this, kFullCodeFlags) &
+           kFullCodeFlagsHasDeoptimizationSupportMask) >>
+          kFullCodeFlagsHasDeoptimizationSupportShift) == 1;

[Sven Panne, 2011/09/08 08:07:59]

Why do we need both a mask and a shift? A single bit mask/flag (whatever you
call it) seems to be sufficient. Same for other places like this below.

[Søren Thygesen Gjesse, 2011/09/13 07:31:19]

This pattern is used for all the other flags (at lease for class Code), as some
flags are more than one bit. However I changed the initialization of the Mask
values in objects.h to

  static const int kFullCodeFlagsHasDeoptimizationSupportMask =
      1 << kFullCodeFlagsHasDeoptimizationSupportShift;
  static const int kFullCodeFlagsHasDebugBreakSlotsMask =
      1 << kFullCodeFlagsHasDebugBreakSlotsShift;

[Sven Panne, 2011/09/13 07:51:51]

I think Kevin changed Code to use BitField for flags
(http://codereview.chromium.org/7787028/), so we should probably follow that
style.

[Søren Thygesen Gjesse, 2011/09/13 08:06:29]

I also noticed that after the rebase. This has now been changed.

 }
 
 
 void Code::set_has_deoptimization_support(bool value) {
   ASSERT(kind() == FUNCTION);
-  WRITE_BYTE_FIELD(this, kHasDeoptimizationSupportOffset, value ? 1 : 0);
+  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
+  flags = (flags & ~kFullCodeFlagsHasDeoptimizationSupportMask) |
+      ((value ? 1 : 0) << kFullCodeFlagsHasDeoptimizationSupportShift);
+  WRITE_BYTE_FIELD(this, kFullCodeFlags, flags);
+}
+
+
+bool Code::has_debug_break_slots() {
+  ASSERT(kind() == FUNCTION);
+  return ((READ_BYTE_FIELD(this, kFullCodeFlags) &
+          kFullCodeFlagsHasDebugBreakSlotsMask) >>
+          kFullCodeFlagsHasDebugBreakSlotsShift) == 1;
+}
+
+
+void Code::set_has_debug_break_slots(bool value) {
+  ASSERT(kind() == FUNCTION);
+  byte flags = READ_BYTE_FIELD(this, kFullCodeFlags);
+  flags = (flags & ~kFullCodeFlagsHasDebugBreakSlotsMask) |
+      ((value ? 1 : 0) << kFullCodeFlagsHasDebugBreakSlotsShift);
+  WRITE_BYTE_FIELD(this, kFullCodeFlags, flags);
 }