Merge commit '50d3e596bbe89c95615f96eb71f6bc5be737a1db' into Basilisk-releasev2018.07.18

# Conflicts:
#	browser/app/profile/firefox.js
#	browser/components/preferences/jar.mn

1 files changed, 42 insertions, 0 deletions

diff --git a/js/src/jit/MIR.h b/js/src/jit/MIR.h
index 2de91e2df..6ec05af76 100644
--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -13192,6 +13192,48 @@ class MHasClass
     }
 };
 
+class MGuardToClass
+    : public MUnaryInstruction,
+      public SingleObjectPolicy::Data
+{
+    const Class* class_;
+
+    MGuardToClass(MDefinition* object, const Class* clasp, MIRType resultType)
+      : MUnaryInstruction(object)
+      , class_(clasp)
+    {
+        MOZ_ASSERT(object->type() == MIRType::Object ||
+                   (object->type() == MIRType::Value && object->mightBeType(MIRType::Object)));
+        MOZ_ASSERT(resultType == MIRType::Object || resultType == MIRType::ObjectOrNull);
+        setResultType(resultType);
+        setMovable();
+        if (resultType == MIRType::Object) {
+            // We will bail out if the class type is incorrect,
+            // so we need to ensure we don't eliminate this instruction
+            setGuard();
+        }
+    }
+
+  public:
+    INSTRUCTION_HEADER(GuardToClass)
+    TRIVIAL_NEW_WRAPPERS
+    NAMED_OPERANDS((0, object))
+
+    const Class* getClass() const {
+        return class_;
+    }
+    AliasSet getAliasSet() const override {
+        return AliasSet::None();
+    }
+    bool congruentTo(const MDefinition* ins) const override {
+        if (!ins->isGuardToClass())
+            return false;
+        if (getClass() != ins->toGuardToClass()->getClass())
+            return false;
+        return congruentIfOperandsEqual(ins);
+    }
+};
+
 class MCheckReturn
   : public MBinaryInstruction,
     public BoxInputsPolicy::Data