Cleanup the way the debugger stores live registers when entering at a break...

src/x64/macro-assembler-x64.cc

 // Copyright 2009 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 2084 matching lines @@
     movq(kScratchRegister, ExternalReference(counter));
     Operand operand(kScratchRegister, 0);
     if (value == 1) {
       decl(operand);
     } else {
       subl(operand, Immediate(value));
     }
   }
 }
 
-#ifdef ENABLE_DEBUGGER_SUPPORT
-
-void MacroAssembler::PushRegistersFromMemory(RegList regs) {
-  ASSERT((regs & ~kJSCallerSaved) == 0);
-  // Push the content of the memory location to the stack.
-  for (int i = 0; i < kNumJSCallerSaved; i++) {
-    int r = JSCallerSavedCode(i);
-    if ((regs & (1 << r)) != 0) {
-      ExternalReference reg_addr =
-          ExternalReference(Debug_Address::Register(i));
-      movq(kScratchRegister, reg_addr);
-      push(Operand(kScratchRegister, 0));
-    }
-  }
-}
-
 
-void MacroAssembler::SaveRegistersToMemory(RegList regs) {
-  ASSERT((regs & ~kJSCallerSaved) == 0);
-  // Copy the content of registers to memory location.
-  for (int i = 0; i < kNumJSCallerSaved; i++) {
-    int r = JSCallerSavedCode(i);
-    if ((regs & (1 << r)) != 0) {
-      Register reg = { r };
-      ExternalReference reg_addr =
-          ExternalReference(Debug_Address::Register(i));
-      movq(kScratchRegister, reg_addr);
-      movq(Operand(kScratchRegister, 0), reg);
-    }
-  }
-}
-
-
-void MacroAssembler::RestoreRegistersFromMemory(RegList regs) {
-  ASSERT((regs & ~kJSCallerSaved) == 0);
-  // Copy the content of memory location to registers.
-  for (int i = kNumJSCallerSaved - 1; i >= 0; i--) {
-    int r = JSCallerSavedCode(i);
-    if ((regs & (1 << r)) != 0) {
-      Register reg = { r };
-      ExternalReference reg_addr =
-          ExternalReference(Debug_Address::Register(i));
-      movq(kScratchRegister, reg_addr);
-      movq(reg, Operand(kScratchRegister, 0));
-    }
-  }
-}
-
-
-void MacroAssembler::PopRegistersToMemory(RegList regs) {
-  ASSERT((regs & ~kJSCallerSaved) == 0);
-  // Pop the content from the stack to the memory location.
-  for (int i = kNumJSCallerSaved - 1; i >= 0; i--) {
-    int r = JSCallerSavedCode(i);
-    if ((regs & (1 << r)) != 0) {
-      ExternalReference reg_addr =
-          ExternalReference(Debug_Address::Register(i));
-      movq(kScratchRegister, reg_addr);
-      pop(Operand(kScratchRegister, 0));
-    }
-  }
-}
-
-
-void MacroAssembler::CopyRegistersFromStackToMemory(Register base,
-                                                    Register scratch,
-                                                    RegList regs) {
-  ASSERT(!scratch.is(kScratchRegister));
-  ASSERT(!base.is(kScratchRegister));
-  ASSERT(!base.is(scratch));
-  ASSERT((regs & ~kJSCallerSaved) == 0);
-  // Copy the content of the stack to the memory location and adjust base.
-  for (int i = kNumJSCallerSaved - 1; i >= 0; i--) {
-    int r = JSCallerSavedCode(i);
-    if ((regs & (1 << r)) != 0) {
-      movq(scratch, Operand(base, 0));
-      ExternalReference reg_addr =
-          ExternalReference(Debug_Address::Register(i));
-      movq(kScratchRegister, reg_addr);
-      movq(Operand(kScratchRegister, 0), scratch);
-      lea(base, Operand(base, kPointerSize));
-    }
-  }
-}
-
+#ifdef ENABLE_DEBUGGER_SUPPORT
 void MacroAssembler::DebugBreak() {
   ASSERT(allow_stub_calls());
   xor_(rax, rax);  // no arguments
   movq(rbx, ExternalReference(Runtime::kDebugBreak));
   CEntryStub ces(1);
   Call(ces.GetCode(), RelocInfo::DEBUG_BREAK);
 }
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 
@@ skipping 149 matching lines @@
   if (FLAG_debug_code) {
     Move(kScratchRegister, Smi::FromInt(type));
     cmpq(Operand(rbp, StandardFrameConstants::kMarkerOffset), kScratchRegister);
     Check(equal, "stack frame types must match");
   }
   movq(rsp, rbp);
   pop(rbp);
 }
 
 
-void MacroAssembler::EnterExitFramePrologue(ExitFrame::Mode mode,
-                                            bool save_rax) {
+void MacroAssembler::EnterExitFramePrologue(bool save_rax) {
   // Setup the frame structure on the stack.
   // All constants are relative to the frame pointer of the exit frame.
   ASSERT(ExitFrameConstants::kCallerSPDisplacement == +2 * kPointerSize);
   ASSERT(ExitFrameConstants::kCallerPCOffset == +1 * kPointerSize);
   ASSERT(ExitFrameConstants::kCallerFPOffset ==  0 * kPointerSize);
   push(rbp);
   movq(rbp, rsp);
 
-  // Reserve room for entry stack pointer and push the debug marker.
+  // Reserve room for entry stack pointer and push the code object.
   ASSERT(ExitFrameConstants::kSPOffset == -1 * kPointerSize);
   push(Immediate(0));  // Saved entry sp, patched before call.
   movq(kScratchRegister, CodeObject(), RelocInfo::EMBEDDED_OBJECT);
   push(kScratchRegister);  // Accessed from EditFrame::code_slot.
 
   // Save the frame pointer and the context in top.
   ExternalReference c_entry_fp_address(Top::k_c_entry_fp_address);
   ExternalReference context_address(Top::k_context_address);
   if (save_rax) {
     movq(r14, rax);  // Backup rax before we use it.
   }
 
   movq(rax, rbp);
   store_rax(c_entry_fp_address);
   movq(rax, rsi);
   store_rax(context_address);
 }
 
-void MacroAssembler::EnterExitFrameEpilogue(ExitFrame::Mode mode,
-                                            int result_size,
+void MacroAssembler::EnterExitFrameEpilogue(int result_size,
                                             int argc) {
-#ifdef ENABLE_DEBUGGER_SUPPORT
-  // Save the state of all registers to the stack from the memory
-  // location. This is needed to allow nested break points.
-  if (mode == ExitFrame::MODE_DEBUG) {
-    // TODO(1243899): This should be symmetric to
-    // CopyRegistersFromStackToMemory() but it isn't! esp is assumed
-    // correct here, but computed for the other call. Very error
-    // prone! FIX THIS.  Actually there are deeper problems with
-    // register saving than this asymmetry (see the bug report
-    // associated with this issue).
-    PushRegistersFromMemory(kJSCallerSaved);
-  }
-#endif
-
 #ifdef _WIN64
   // Reserve space on stack for result and argument structures, if necessary.
   int result_stack_space = (result_size < 2) ? 0 : result_size * kPointerSize;
   // Reserve space for the Arguments object.  The Windows 64-bit ABI
   // requires us to pass this structure as a pointer to its location on
   // the stack.  The structure contains 2 values.
   int argument_stack_space = argc * kPointerSize;
   // We also need backing space for 4 parameters, even though
   // we only pass one or two parameter, and it is in a register.
   int argument_mirror_space = 4 * kPointerSize;
   int total_stack_space =
       argument_mirror_space + argument_stack_space + result_stack_space;
   subq(rsp, Immediate(total_stack_space));
 #endif
 
   // Get the required frame alignment for the OS.
   static const int kFrameAlignment = OS::ActivationFrameAlignment();
   if (kFrameAlignment > 0) {
     ASSERT(IsPowerOf2(kFrameAlignment));
     movq(kScratchRegister, Immediate(-kFrameAlignment));
     and_(rsp, kScratchRegister);
   }
 
   // Patch the saved entry sp.
   movq(Operand(rbp, ExitFrameConstants::kSPOffset), rsp);
 }
 
 
-void MacroAssembler::EnterExitFrame(ExitFrame::Mode mode, int result_size) {
-  EnterExitFramePrologue(mode, true);
+void MacroAssembler::EnterExitFrame(int result_size) {
+  EnterExitFramePrologue(true);
 
   // Setup argv in callee-saved register r12. It is reused in LeaveExitFrame,
   // so it must be retained across the C-call.
   int offset = StandardFrameConstants::kCallerSPOffset - kPointerSize;
   lea(r12, Operand(rbp, r14, times_pointer_size, offset));
 
-  EnterExitFrameEpilogue(mode, result_size, 2);
+  EnterExitFrameEpilogue(result_size, 2);
 }
 
 
-void MacroAssembler::EnterApiExitFrame(ExitFrame::Mode mode,
-                                       int stack_space,
+void MacroAssembler::EnterApiExitFrame(int stack_space,
                                        int argc,
                                        int result_size) {
-  EnterExitFramePrologue(mode, false);
+  EnterExitFramePrologue(false);
 
   // Setup argv in callee-saved register r12. It is reused in LeaveExitFrame,
   // so it must be retained across the C-call.
   int offset = StandardFrameConstants::kCallerSPOffset - kPointerSize;
   lea(r12, Operand(rbp, (stack_space * kPointerSize) + offset));
 
-  EnterExitFrameEpilogue(mode, result_size, argc);
+  EnterExitFrameEpilogue(result_size, argc);
 }
 
 
-void MacroAssembler::LeaveExitFrame(ExitFrame::Mode mode, int result_size) {
+void MacroAssembler::LeaveExitFrame(int result_size) {
   // Registers:
   // r12 : argv
-#ifdef ENABLE_DEBUGGER_SUPPORT
-  // Restore the memory copy of the registers by digging them out from
-  // the stack. This is needed to allow nested break points.
-  if (mode == ExitFrame::MODE_DEBUG) {
-    // It's okay to clobber register rbx below because we don't need
-    // the function pointer after this.
-    const int kCallerSavedSize = kNumJSCallerSaved * kPointerSize;
-    int kOffset = ExitFrameConstants::kCodeOffset - kCallerSavedSize;
-    lea(rbx, Operand(rbp, kOffset));
-    CopyRegistersFromStackToMemory(rbx, rcx, kJSCallerSaved);
-  }
-#endif
 
   // Get the return address from the stack and restore the frame pointer.
   movq(rcx, Operand(rbp, 1 * kPointerSize));
   movq(rbp, Operand(rbp, 0 * kPointerSize));
 
   // Pop everything up to and including the arguments and the receiver
   // from the caller stack.
   lea(rsp, Operand(r12, 1 * kPointerSize));
 
   // Restore current context from top and clear it in debug mode.
@@ skipping 476 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64