Bug 1111218 - Fold congruent type barriers. r=bhackett

js/src/jit/MIR.cpp

@@ -1207,6 +1207,19 @@ MTypeBarrier::printOpcode(FILE *fp) const
     getOperand(0)->printName(fp);
 }
 
+bool
+MTypeBarrier::congruentTo(const MDefinition *def) const
+{
+    if (!def->isTypeBarrier())
+        return false;
+    const MTypeBarrier *other = def->toTypeBarrier();
+    if (barrierKind() != other->barrierKind() || isGuard() != other->isGuard())
+        return false;
+    if (!resultTypeSet()->equals(other->resultTypeSet()))
+        return false;
+    return congruentIfOperandsEqual(other);
+}
+
 #ifdef DEBUG
 void
 MPhi::assertLoopPhi() const
@@ -4355,13 +4368,10 @@ TryAddTypeBarrierForWrite(TempAllocator &alloc, types::CompilerConstraintList *c
         if (!aggregateProperty) {
             aggregateProperty.emplace(property);
         } else {
-            if (!aggregateProperty->maybeTypes()->isSubset(property.maybeTypes()) ||
-                !property.maybeTypes()->isSubset(aggregateProperty->maybeTypes()))
-            {
+            if (!aggregateProperty->maybeTypes()->equals(property.maybeTypes()))
                 return false;
         }
     }
-    }
 
     MOZ_ASSERT(aggregateProperty);
 

js/src/jit/MIR.h

@@ -11343,10 +11343,8 @@ class MTypeBarrier
     }
 
     void printOpcode(FILE *fp) const;
+    bool congruentTo(const MDefinition *def) const;
 
-    bool congruentTo(const MDefinition *def) const {
-        return false;
-    }
     AliasSet getAliasSet() const {
         return AliasSet::None();
     }

js/src/jsinfer.cpp

@@ -383,7 +383,7 @@ TypeSet::objectsAreSubset(TypeSet *other)
 }
 
 bool
-TypeSet::isSubset(TypeSet *other)
+TypeSet::isSubset(const TypeSet *other) const
 {
     if ((baseFlags() & other->baseFlags()) != baseFlags())
         return false;

js/src/jsinfer.h

@@ -634,7 +634,7 @@ class TypeSet
      * Get whether this type set is known to be a subset of other.
      * This variant doesn't freeze constraints. That variant is called knownSubset
      */
-    bool isSubset(TypeSet *other);
+    bool isSubset(const TypeSet *other) const;
 
     /*
      * Get whether the objects in this TypeSet are a subset of the objects
@@ -642,6 +642,11 @@ class TypeSet
      */
     bool objectsAreSubset(TypeSet *other);
 
+    /* Whether this TypeSet contains exactly the same types as other. */
+    bool equals(const TypeSet *other) const {
+        return this->isSubset(other) && other->isSubset(this);
+    }
+
     /* Forward all types in this set to the specified constraint. */
     bool addTypesToConstraint(JSContext *cx, TypeConstraint *constraint);