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

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 112 matching lines @@
   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
-  // they will have the correct value when returning from the debugger.
-  __ SaveRegistersToMemory(kJSCallerSaved);
-
+                                          RegList object_regs,
+                                          RegList non_object_regs) {
   __ EnterInternalFrame();
 
-  // Store the registers containing object pointers on the expression stack to
-  // make sure that these are correctly updated during GC.
-  // Use sp as base to push.
-  __ CopyRegistersFromMemoryToStack(sp, pointer_regs);
+  // Store the registers containing live values on the expression stack to
+  // make sure that these are correctly updated during GC. Non object values
+  // are stored as a smi causing it to be untouched by GC.
+  ASSERT((object_regs & ~kJSCallerSaved) == 0);
+  ASSERT((non_object_regs & ~kJSCallerSaved) == 0);
+  ASSERT((object_regs & non_object_regs) == 0);
+  if ((object_regs | non_object_regs) != 0) {
+    for (int i = 0; i < kNumJSCallerSaved; i++) {
+      int r = JSCallerSavedCode(i);
+      Register reg = { r };
+      if ((non_object_regs & (1 << r)) != 0) {
+        if (FLAG_debug_code) {
+          __ tst(reg, Operand(0xc0000000));
+          __ Assert(eq, "Unable to encode value as smi");
+        }
+        __ mov(reg, Operand(reg, LSL, kSmiTagSize));
+      }
+    }
+    __ stm(db_w, sp, object_regs | non_object_regs);
+  }
 
 #ifdef DEBUG
   __ RecordComment("// Calling from debug break to runtime - come in - over");
 #endif
   __ mov(r0, Operand(0));  // no arguments
   __ mov(r1, Operand(ExternalReference::debug_break()));
 
-  CEntryStub ceb(1, ExitFrame::MODE_DEBUG);
+  CEntryStub ceb(1);
   __ CallStub(&ceb);
 
-  // Restore the register values containing object pointers from the expression
-  // stack in the reverse order as they where pushed.
-  // Use sp as base to pop.
-  __ CopyRegistersFromStackToMemory(sp, r3, pointer_regs);
+  // Restore the register values from the expression stack.
+  if ((object_regs | non_object_regs) != 0) {
+    __ ldm(ia_w, sp, object_regs | non_object_regs);
+    for (int i = 0; i < kNumJSCallerSaved; i++) {
+      int r = JSCallerSavedCode(i);
+      Register reg = { r };
+      if ((non_object_regs & (1 << r)) != 0) {
+        __ mov(reg, Operand(reg, LSR, kSmiTagSize));
+      }
+      if (FLAG_debug_code &&
+          (((object_regs |non_object_regs) & (1 << r)) == 0)) {
+        __ mov(reg, Operand(kDebugZapValue));
+      }
+    }
+  }
 
   __ LeaveInternalFrame();
 
-  // Finally restore all registers.
-  __ RestoreRegistersFromMemory(kJSCallerSaved);
-
   // Now that the break point has been handled, resume normal execution by
   // jumping to the target address intended by the caller and that was
   // overwritten by the address of DebugBreakXXX.
   __ mov(ip, Operand(ExternalReference(Debug_Address::AfterBreakTarget())));
   __ ldr(ip, MemOperand(ip));
   __ Jump(ip);
 }
 
 
 void Debug::GenerateLoadICDebugBreak(MacroAssembler* masm) {
   // Calling convention for IC load (from ic-arm.cc).
   // ----------- S t a t e -------------
   //  -- r2    : name
   //  -- lr    : return address
   //  -- r0    : receiver
   //  -- [sp]  : receiver
   // -----------------------------------
   // Registers r0 and r2 contain objects that need to be pushed on the
   // expression stack of the fake JS frame.
-  Generate_DebugBreakCallHelper(masm, r0.bit() | r2.bit());
+  Generate_DebugBreakCallHelper(masm, r0.bit() | r2.bit(), 0);
 }
 
 
 void Debug::GenerateStoreICDebugBreak(MacroAssembler* masm) {
   // Calling convention for IC store (from ic-arm.cc).
   // ----------- S t a t e -------------
   //  -- r0    : value
   //  -- r1    : receiver
   //  -- r2    : name
   //  -- lr    : return address
   // -----------------------------------
   // Registers r0, r1, and r2 contain objects that need to be pushed on the
   // expression stack of the fake JS frame.
-  Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit() | r2.bit());
+  Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit() | r2.bit(), 0);
 }
 
 
 void Debug::GenerateKeyedLoadICDebugBreak(MacroAssembler* masm) {
   // ---------- S t a t e --------------
   //  -- lr     : return address
   //  -- r0     : key
-  //  -- sp[0]  : key
-  //  -- sp[4]  : receiver
-  Generate_DebugBreakCallHelper(masm, r0.bit());
+  //  -- r1     : receiver
+  Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit(), 0);
 }
 
 
 void Debug::GenerateKeyedStoreICDebugBreak(MacroAssembler* masm) {
   // ---------- S t a t e --------------
   //  -- r0     : value
   //  -- r1     : key
   //  -- r2     : receiver
   //  -- lr     : return address
-  Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit() | r2.bit());
+  Generate_DebugBreakCallHelper(masm, r0.bit() | r1.bit() | r2.bit(), 0);
 }
 
 
 void Debug::GenerateCallICDebugBreak(MacroAssembler* masm) {
   // Calling convention for IC call (from ic-arm.cc)
   // ----------- S t a t e -------------
-  //  -- r2: name
+  //  -- r2     : name
   // -----------------------------------
-  Generate_DebugBreakCallHelper(masm, r2.bit());
+  Generate_DebugBreakCallHelper(masm, r2.bit(), 0);
 }
 
 
 void Debug::GenerateConstructCallDebugBreak(MacroAssembler* masm) {
-  // In places other than IC call sites it is expected that r0 is TOS which
-  // is an object - this is not generally the case so this should be used with
-  // care.
-  Generate_DebugBreakCallHelper(masm, r0.bit());
+  // Calling convention for construct call (from builtins-arm.cc)
+  //  -- r0     : number of arguments (not smi)
+  //  -- r1     : constructor function
+  Generate_DebugBreakCallHelper(masm, r1.bit(), r0.bit());
 }
 
 
 void Debug::GenerateReturnDebugBreak(MacroAssembler* masm) {
   // In places other than IC call sites it is expected that r0 is TOS which
   // is an object - this is not generally the case so this should be used with
   // care.
-  Generate_DebugBreakCallHelper(masm, r0.bit());
+  Generate_DebugBreakCallHelper(masm, r0.bit(), 0);
 }
 
 
 void Debug::GenerateStubNoRegistersDebugBreak(MacroAssembler* masm) {
   // ----------- S t a t e -------------
   //  No registers used on entry.
   // -----------------------------------
-  Generate_DebugBreakCallHelper(masm, 0);
+  Generate_DebugBreakCallHelper(masm, 0, 0);
 }
 
 
 void Debug::GenerateSlot(MacroAssembler* masm) {
   // Generate enough nop's to make space for a call instruction. Avoid emitting
   // the constant pool in the debug break slot code.
   Assembler::BlockConstPoolScope block_const_pool(masm);
   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);
+  Generate_DebugBreakCallHelper(masm, 0, 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");
 }
 
 const bool Debug::kFrameDropperSupported = false;
 
 #undef __
 
 
 
 #endif  // ENABLE_DEBUGGER_SUPPORT
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_ARM