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

src/mips/macro-assembler-mips.cc

Index: src/mips/macro-assembler-mips.cc
diff --git a/src/mips/macro-assembler-mips.cc b/src/mips/macro-assembler-mips.cc
index 5cc505d1679177a1054a173708457f018e7f2d10..b2f60c5d2a09749cdedcbb862495d6ac1c01c3db 100644
--- a/src/mips/macro-assembler-mips.cc
+++ b/src/mips/macro-assembler-mips.cc
@@ -4021,6 +4021,22 @@ void MacroAssembler::CheckMap(Register obj,
 }
 
 
+void MacroAssembler::CmpWeakValue(Register match, Register value,
+                                  Handle<WeakCell> cell) {
+  li(match, Operand(cell));
+  lw(match, FieldMemOperand(match, WeakCell::kValueOffset));
+  Subu(match, value, match);
+}
+
+
+void MacroAssembler::LoadWeakValue(Register value, Handle<WeakCell> cell,
+                                   Label* miss) {
+  li(value, Operand(cell));
+  lw(value, FieldMemOperand(value, WeakCell::kValueOffset));
+  JumpIfSmi(value, miss);
+}
+
+
 void MacroAssembler::MovFromFloatResult(DoubleRegister dst) {
   if (IsMipsSoftFloatABI) {
     if (kArchEndian == kLittle) {