Reland parts of 'Use weak cells in map checks in polymorphic ICs'

src/x87/macro-assembler-x87.cc

Index: src/x87/macro-assembler-x87.cc
diff --git a/src/x87/macro-assembler-x87.cc b/src/x87/macro-assembler-x87.cc
index d6d24530715e9fb998560c45d250eed7482144fa..0d23cffafb75f961fa168caadb5410dc9876308a 100644
--- a/src/x87/macro-assembler-x87.cc
+++ b/src/x87/macro-assembler-x87.cc
@@ -2544,6 +2544,21 @@ void MacroAssembler::PushHeapObject(Handle<HeapObject> object) {
 }
 
 
+void MacroAssembler::CmpWeakValue(Register value, Handle<WeakCell> cell,
+                                  Register scratch) {
+  mov(scratch, cell);
+  cmp(value, FieldOperand(scratch, WeakCell::kValueOffset));
+}
+
+
+void MacroAssembler::LoadWeakValue(Register value, Handle<WeakCell> cell,
+                                   Label* miss) {
+  mov(value, cell);
+  mov(value, FieldOperand(value, WeakCell::kValueOffset));
+  JumpIfSmi(value, miss);
+}
+
+
 void MacroAssembler::Ret() {
   ret(0);
 }