Debugger: use debug break slots to break at function exit.

src/ia32/assembler-ia32.h

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // 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.
 //
@@ skipping 515 matching lines @@
                                            ICacheFlushMode icache_flush_mode =
                                                FLUSH_ICACHE_IF_NEEDED) {
     Address constant_pool = code ? code->constant_pool() : NULL;
     set_target_address_at(pc, constant_pool, target);
   }
 
   // Return the code target address at a call site from the return address
   // of that call in the instruction stream.
   inline static Address target_address_from_return_address(Address pc);
 
-  // Return the code target address of the patch debug break slot
-  inline static Address break_address_from_return_address(Address pc);
-
   // This sets the branch destination (which is in the instruction on x86).
   // This is for calls and branches within generated code.
   inline static void deserialization_set_special_target_at(
       Address instruction_payload, Code* code, Address target) {
     set_target_address_at(instruction_payload, code, target);
   }
 
   // This sets the internal reference at the pc.
   inline static void deserialization_set_target_internal_reference_at(
       Address pc, Address target,
       RelocInfo::Mode mode = RelocInfo::INTERNAL_REFERENCE);
 
   static const int kSpecialTargetSize = kPointerSize;
 
   // Distance between the address of the code target in the call instruction
   // and the return address
   static const int kCallTargetAddressOffset = kPointerSize;
-  // Distance between start of patched return sequence and the emitted address
-  // to jump to.
-  static const int kPatchReturnSequenceAddressOffset = 1;  // JMP imm32.
+
+  static const int kCallInstructionLength = 5;
+
+  // The debug break slot must be able to contain a call instruction.
+  static const int kDebugBreakSlotLength = kCallInstructionLength;
 
   // Distance between start of patched debug break slot and the emitted address
   // to jump to.
   static const int kPatchDebugBreakSlotAddressOffset = 1;  // JMP imm32.
 
-  static const int kCallInstructionLength = 5;
-  static const int kPatchDebugBreakSlotReturnOffset = kPointerSize;
-  static const int kJSReturnSequenceLength = 6;
-
-  // The debug break slot must be able to contain a call instruction.
-  static const int kDebugBreakSlotLength = kCallInstructionLength;
-
   // One byte opcode for test al, 0xXX.
   static const byte kTestAlByte = 0xA8;
   // One byte opcode for nop.
   static const byte kNopByte = 0x90;
 
   // One byte opcode for a short unconditional jump.
   static const byte kJmpShortOpcode = 0xEB;
   // One byte prefix for a short conditional jump.
   static const byte kJccShortPrefix = 0x70;
   static const byte kJncShortOpcode = kJccShortPrefix | not_carry;
@@ skipping 845 matching lines @@
   // Level 1, 2 or 3 specifies CPU cache level. Level 0 specifies a
   // non-temporal
   void prefetch(const Operand& src, int level);
   // TODO(lrn): Need SFENCE for movnt?
 
   // Check the code size generated from label to here.
   int SizeOfCodeGeneratedSince(Label* label) {
     return pc_offset() - label->pos();
   }
 
-  // Mark address of the ExitJSFrame code.
-  void RecordJSReturn();
-
   // Mark generator continuation.
   void RecordGeneratorContinuation();
 
   // Mark address of a debug break slot.
-  void RecordDebugBreakSlot();
-  void RecordDebugBreakSlotForCall(int argc);
-  void RecordDebugBreakSlotForConstructCall();
+  void RecordDebugBreakSlot(RelocInfo::Mode mode, int argc = 0);
 
   // Record a comment relocation entry that can be used by a disassembler.
   // Use --code-comments to enable.
   void RecordComment(const char* msg);
 
   // Record a deoptimization reason that can be used by a log or cpu profiler.
   // Use --trace-deopt to enable.
   void RecordDeoptReason(const int reason, const SourcePosition position);
 
   // Writes a single byte or word of data in the code stream.  Used for
@@ skipping 151 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_ASSEMBLER_IA32_H_