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

src/objects-inl.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 2927 matching lines @@
 
 
 void Code::set_optimizable(bool value) {
   ASSERT(kind() == FUNCTION);
   WRITE_BYTE_FIELD(this, kOptimizableOffset, value ? 1 : 0);
 }
 
 
 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);
+}
+
+
 int Code::allow_osr_at_loop_nesting_level() {
   ASSERT(kind() == FUNCTION);
   return READ_BYTE_FIELD(this, kAllowOSRAtLoopNestingLevelOffset);
 }
 
 
 void Code::set_allow_osr_at_loop_nesting_level(int level) {
   ASSERT(kind() == FUNCTION);
   ASSERT(level >= 0 && level <= kMaxLoopNestingMarker);
   WRITE_BYTE_FIELD(this, kAllowOSRAtLoopNestingLevelOffset, level);
@@ skipping 1711 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_