More precise break points and stepping when debugging...

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 450 matching lines @@
   static const int kCallTargetSize = kPointerSize;
   static const int kExternalTargetSize = 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.
 
+  // 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 kJSReturnSequenceLength = 6;
 
+  // The debug break slot must be able to contain a call instruction.
+  static const int kDebugBreakSlotLength = kCallInstructionLength;
+
   // ---------------------------------------------------------------------------
   // Code generation
   //
   // - function names correspond one-to-one to ia32 instruction mnemonics
   // - unless specified otherwise, instructions operate on 32bit operands
   // - instructions on 8bit (byte) operands/registers have a trailing '_b'
   // - instructions on 16bit (word) operands/registers have a trailing '_w'
   // - naming conflicts with C++ keywords are resolved via a trailing '_'
 
   // NOTE ON INTERFACE: Currently, the interface is not very consistent
@@ skipping 318 matching lines @@
 
   // Debugging
   void Print();
 
   // Check the code size generated from label to here.
   int SizeOfCodeGeneratedSince(Label* l) { return pc_offset() - l->pos(); }
 
   // Mark address of the ExitJSFrame code.
   void RecordJSReturn();
 
+  // Mark address of a debug break slot.
+  void RecordDebugBreakSlot();
+
   // Record a comment relocation entry that can be used by a disassembler.
   // Use --debug_code to enable.
   void RecordComment(const char* msg);
 
   void RecordPosition(int pos);
   void RecordStatementPosition(int pos);
-  void WriteRecordedPositions();
+  bool WriteRecordedPositions();
 
   // Writes a single word of data in the code stream.
   // Used for inline tables, e.g., jump-tables.
   void dd(uint32_t data, RelocInfo::Mode reloc_info);
 
   int pc_offset() const  { return pc_ - buffer_; }
   int current_statement_position() const { return current_statement_position_; }
   int current_position() const  { return current_position_; }
 
   // Check if there is less than kGap bytes available in the buffer.
   // If this is the case, we need to grow the buffer before emitting
   // an instruction or relocation information.
   inline bool overflow() const { return pc_ >= reloc_info_writer.pos() - kGap; }
 
   // Get the number of bytes available in the buffer.
   inline int available_space() const { return reloc_info_writer.pos() - pc_; }
 
+  static bool IsNop(Address addr) { return *addr == 0x90; }
+
   // Avoid overflows for displacements etc.
   static const int kMaximalBufferSize = 512*MB;
   static const int kMinimalBufferSize = 4*KB;
 
  protected:
   void movsd(XMMRegister dst, const Operand& src);
   void movsd(const Operand& dst, XMMRegister src);
 
   void emit_sse_operand(XMMRegister reg, const Operand& adr);
   void emit_sse_operand(XMMRegister dst, XMMRegister src);
@@ skipping 96 matching lines @@
  private:
   Assembler* assembler_;
 #ifdef DEBUG
   int space_before_;
 #endif
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_ASSEMBLER_IA32_H_