Fix issue 825 (LiveEdit vs. function with no locals) for x64.

Review URL: https://chromiumcodereview.appspot.com/10387116

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@11587 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/ia32/debug-ia32.cc

@@ -175,7 +175,7 @@ static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
     // Read current padding counter and skip corresponding number of words.
     __ pop(unused_reg);
     // We divide stored value by 2 (untagging) and multiply it by word's size.
-    STATIC_ASSERT(kSmiTagSize == 1);
+    STATIC_ASSERT(kSmiTagSize == 1 && kSmiShiftSize == 0);
     __ lea(esp, Operand(esp, unused_reg, times_half_pointer_size, 0));
 
     // Get rid of the internal frame.

src/x64/debug-x64.cc

@@ -91,7 +91,7 @@ void BreakLocationIterator::ClearDebugBreakAtSlot() {
   rinfo()->PatchCode(original_rinfo()->pc(), Assembler::kDebugBreakSlotLength);
 }
 
-const bool Debug::FramePaddingLayout::kIsSupported = false;
+const bool Debug::FramePaddingLayout::kIsSupported = true;
 
 
 #define __ ACCESS_MASM(masm)
@@ -105,6 +105,12 @@ static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
   {
     FrameScope scope(masm, StackFrame::INTERNAL);
 
+    // Load padding words on stack.
+    for (int i = 0; i < Debug::FramePaddingLayout::kInitialSize; i++) {
+      __ Push(Smi::FromInt(Debug::FramePaddingLayout::kPaddingValue));
+    }
+    __ Push(Smi::FromInt(Debug::FramePaddingLayout::kInitialSize));
+
     // 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 as two smis causing it to be untouched by GC.
@@ -159,6 +165,11 @@ static void Generate_DebugBreakCallHelper(MacroAssembler* masm,
       }
     }
 
+    // Read current padding counter and skip corresponding number of words.
+    __ pop(kScratchRegister);
+    __ SmiToInteger32(kScratchRegister, kScratchRegister);
+    __ lea(rsp, Operand(rsp, kScratchRegister, times_pointer_size, 0));
+
     // Get rid of the internal frame.
   }