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

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
===================================================================
--- src/x64/macro-assembler-x64.cc	(revision 5352)
+++ src/x64/macro-assembler-x64.cc	(working copy)
@@ -2102,91 +2102,8 @@
   }
 }
 
-#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
@@ -2356,8 +2273,7 @@
 }
 
 
-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);
@@ -2366,7 +2282,7 @@
   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);
@@ -2385,23 +2301,8 @@
   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;
@@ -2430,48 +2331,35 @@
 }
 
 
-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));