Update V8 to r6768 as required by WebKit r78450

Change-Id: Ib8868ff7147a76547a8d1d85f257ebe8546a3d3f
diff --git a/src/x64/assembler-x64-inl.h b/src/x64/assembler-x64-inl.h
index 1fe9eed..285c078 100644
--- a/src/x64/assembler-x64-inl.h
+++ b/src/x64/assembler-x64-inl.h
@@ -199,8 +199,10 @@
   if (IsInternalReference(rmode_)) {
     // absolute code pointer inside code object moves with the code object.
     Memory::Address_at(pc_) += static_cast<int32_t>(delta);
+    CPU::FlushICache(pc_, sizeof(Address));
   } else if (IsCodeTarget(rmode_)) {
     Memory::int32_at(pc_) -= static_cast<int32_t>(delta);
+    CPU::FlushICache(pc_, sizeof(int32_t));
   }
 }
 
@@ -236,6 +238,7 @@
     Assembler::set_target_address_at(pc_, target);
   } else {
     Memory::Address_at(pc_) = target;
+    CPU::FlushICache(pc_, sizeof(Address));
   }
 }
 
@@ -271,6 +274,7 @@
 void RelocInfo::set_target_object(Object* target) {
   ASSERT(IsCodeTarget(rmode_) || rmode_ == EMBEDDED_OBJECT);
   *reinterpret_cast<Object**>(pc_) = target;
+  CPU::FlushICache(pc_, sizeof(Address));
 }
 
 
@@ -295,6 +299,7 @@
   ASSERT(rmode_ == RelocInfo::GLOBAL_PROPERTY_CELL);
   Address address = cell->address() + JSGlobalPropertyCell::kValueOffset;
   Memory::Address_at(pc_) = address;
+  CPU::FlushICache(pc_, sizeof(Address));
 }
 
 
@@ -331,6 +336,8 @@
          (IsDebugBreakSlot(rmode()) && IsPatchedDebugBreakSlotSequence()));
   Memory::Address_at(pc_ + Assembler::kRealPatchReturnSequenceAddressOffset) =
       target;
+  CPU::FlushICache(pc_ + Assembler::kRealPatchReturnSequenceAddressOffset,
+                   sizeof(Address));
 }
 
 
@@ -356,10 +363,14 @@
   RelocInfo::Mode mode = rmode();
   if (mode == RelocInfo::EMBEDDED_OBJECT) {
     visitor->VisitPointer(target_object_address());
+    CPU::FlushICache(pc_, sizeof(Address));
   } else if (RelocInfo::IsCodeTarget(mode)) {
     visitor->VisitCodeTarget(this);
+  } else if (mode == RelocInfo::GLOBAL_PROPERTY_CELL) {
+    visitor->VisitGlobalPropertyCell(this);
   } else if (mode == RelocInfo::EXTERNAL_REFERENCE) {
     visitor->VisitExternalReference(target_reference_address());
+    CPU::FlushICache(pc_, sizeof(Address));
 #ifdef ENABLE_DEBUGGER_SUPPORT
   } else if (Debug::has_break_points() &&
              ((RelocInfo::IsJSReturn(mode) &&
@@ -379,10 +390,14 @@
   RelocInfo::Mode mode = rmode();
   if (mode == RelocInfo::EMBEDDED_OBJECT) {
     StaticVisitor::VisitPointer(target_object_address());
+    CPU::FlushICache(pc_, sizeof(Address));
   } else if (RelocInfo::IsCodeTarget(mode)) {
     StaticVisitor::VisitCodeTarget(this);
+  } else if (mode == RelocInfo::GLOBAL_PROPERTY_CELL) {
+    StaticVisitor::VisitGlobalPropertyCell(this);
   } else if (mode == RelocInfo::EXTERNAL_REFERENCE) {
     StaticVisitor::VisitExternalReference(target_reference_address());
+    CPU::FlushICache(pc_, sizeof(Address));
 #ifdef ENABLE_DEBUGGER_SUPPORT
   } else if (Debug::has_break_points() &&
              ((RelocInfo::IsJSReturn(mode) &&
@@ -414,7 +429,7 @@
   // Use SIB with no index register only for base rsp or r12. Otherwise we
   // would skip the SIB byte entirely.
   ASSERT(!index.is(rsp) || base.is(rsp) || base.is(r12));
-  buf_[1] = scale << 6 | index.low_bits() << 3 | base.low_bits();
+  buf_[1] = (scale << 6) | (index.low_bits() << 3) | base.low_bits();
   rex_ |= index.high_bit() << 1 | base.high_bit();
   len_ = 2;
 }