More precise break points and stepping when debugging...

src/arm/debug-arm.cc

 // Copyright 2006-2008 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 39 matching lines @@
   // to a call to the debug break return code.
   // #if USE_BLX
   //   ldr ip, [pc, #0]
   //   blx ip
   // #else
   //   mov lr, pc
   //   ldr pc, [pc, #-4]
   // #endif
   //   <debug break return code entry point address>
   //   bktp 0
-  CodePatcher patcher(rinfo()->pc(), 4);
+  CodePatcher patcher(rinfo()->pc(), Assembler::kJSReturnSequenceInstructions);
 #ifdef USE_BLX
   patcher.masm()->ldr(v8::internal::ip, MemOperand(v8::internal::pc, 0));
   patcher.masm()->blx(v8::internal::ip);
 #else
   patcher.masm()->mov(v8::internal::lr, v8::internal::pc);
   patcher.masm()->ldr(v8::internal::pc, MemOperand(v8::internal::pc, -4));
 #endif
   patcher.Emit(Debug::debug_break_return()->entry());
   patcher.masm()->bkpt(0);
 }
 
 
 // Restore the JS frame exit code.
 void BreakLocationIterator::ClearDebugBreakAtReturn() {
   rinfo()->PatchCode(original_rinfo()->pc(),
-                     Assembler::kJSReturnSequenceLength);
+                     Assembler::kJSReturnSequenceInstructions);
 }
 
 
-// A debug break in the exit code is identified by a call.
+// A debug break in the frame exit code is identified by the JS frame exit code
+// having been patched with a call instruction.
 bool Debug::IsDebugBreakAtReturn(RelocInfo* rinfo) {
   ASSERT(RelocInfo::IsJSReturn(rinfo->rmode()));
   return rinfo->IsPatchedReturnSequence();
 }
 
 
+bool BreakLocationIterator::IsDebugBreakAtSlot() {
+  ASSERT(IsDebugBreakSlot());
+  // Check whether the debug break slot instructions have been patched.
+  return rinfo()->IsPatchedDebugBreakSlotSequence();
+}
+
+
+void BreakLocationIterator::SetDebugBreakAtSlot() {
+  ASSERT(IsDebugBreakSlot());
+  // Patch the code changing the debug break slot code from
+  //   mov r2, r2
+  //   mov r2, r2
+  //   mov r2, r2
+  // to a call to the debug break slot code.
+  // #if USE_BLX
+  //   ldr ip, [pc, #0]
+  //   blx ip
+  // #else
+  //   mov lr, pc
+  //   ldr pc, [pc, #-4]
+  // #endif
+  //   <debug break slot code entry point address>
+  CodePatcher patcher(rinfo()->pc(), Assembler::kDebugBreakSlotInstructions);
+#ifdef USE_BLX
+  patcher.masm()->ldr(v8::internal::ip, MemOperand(v8::internal::pc, 0));
+  patcher.masm()->blx(v8::internal::ip);
+#else
+  patcher.masm()->mov(v8::internal::lr, v8::internal::pc);
+  patcher.masm()->ldr(v8::internal::pc, MemOperand(v8::internal::pc, -4));
+#endif
+  patcher.Emit(Debug::debug_break_return()->entry());
+}
+
+
+void BreakLocationIterator::ClearDebugBreakAtSlot() {
+  ASSERT(IsDebugBreakSlot());
+  rinfo()->PatchCode(original_rinfo()->pc(),
+                     Assembler::kDebugBreakSlotInstructions);
+}
+
+
 #define __ ACCESS_MASM(masm)
 
 
 static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
                                           RegList pointer_regs) {
   // Save the content of all general purpose registers in memory. This copy in
   // memory is later pushed onto the JS expression stack for the fake JS frame
   // generated and also to the C frame generated on top of that. In the JS
   // frame ONLY the registers containing pointers will be pushed on the
   // expression stack. This causes the GC to update these  pointers so that
@@ skipping 116 matching lines @@
 
 
 void Debug::GenerateStubNoRegistersDebugBreak(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  No registers used on entry.
   // -----------------------------------
   Generate_DebugBreakCallHelper(masm, 0);
 }
 
 
+void Debug::GenerateSlot(MacroAssembler* masm) {
+  // Generate enough nop's to make space for a call instruction.
+  Label check_codesize;
+  __ bind(&check_codesize);
+  __ RecordDebugBreakSlot();
+  for (int i = 0; i < Assembler::kDebugBreakSlotInstructions; i++) {
+    __ nop(2);
+  }
+  ASSERT_EQ(Assembler::kDebugBreakSlotInstructions,
+            masm->InstructionsGeneratedSince(&check_codesize));
+}
+
+
+void Debug::GenerateSlotDebugBreak(MacroAssembler* masm) {
+  // In the places where a debug break slot is inserted no registers can contain
+  // object pointers.
+  Generate_DebugBreakCallHelper(masm, 0);
+}
+
+
 void Debug::GeneratePlainReturnLiveEdit(MacroAssembler* masm) {
   masm->Abort("LiveEdit frame dropping is not supported on arm");
 }
 
+
 void Debug::GenerateFrameDropperLiveEdit(MacroAssembler* masm) {
   masm->Abort("LiveEdit frame dropping is not supported on arm");
 }
 
 #undef __
 
 
 void Debug::SetUpFrameDropperFrame(StackFrame* bottom_js_frame,
                                    Handle<Code> code) {
   UNREACHABLE();
 }
 const int Debug::kFrameDropperFrameSize = -1;
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM