Java: Performance tweaks

Author: igfoo

java/ql/examples/snippets/extend_class.ql

@@ -13,5 +13,5 @@
 import java
 
 from RefType type
-where type.getASupertype+().hasQualifiedName("com.example", "Class")
+where type.getAStrictAncestor().hasQualifiedName("com.example", "Class")
 select type

java/ql/examples/snippets/throw_exception.ql

@@ -9,5 +9,5 @@
 import java
 
 from ThrowStmt throw
-where throw.getThrownExceptionType().getASupertype*().hasQualifiedName("com.example", "AnException")
+where throw.getThrownExceptionType().getAnAncestor().hasQualifiedName("com.example", "AnException")
 select throw, "Don't throw com.example.AnException"

java/ql/lib/semmle/code/java/ControlFlowGraph.qll

@@ -236,7 +236,7 @@ private module ControlFlowGraphImpl {
    */
   private predicate mustCatch(CatchClause c, ThrowableType thrown) {
     thrown = thrownInBody(c.getTry()) and
-    hasSubtype*(c.getACaughtType(), thrown)
+    hasDescendant(c.getACaughtType(), thrown)
   }
 
   /**
@@ -250,7 +250,7 @@ private module ControlFlowGraphImpl {
    */
   private predicate mayNotCatch(CatchClause c, ThrowableType thrown) {
     thrown = thrownInBody(c.getTry()) and
-    not hasSubtype*(c.getACaughtType(), thrown)
+    not hasDescendant(c.getACaughtType(), thrown)
   }
 
   /**

java/ql/lib/semmle/code/java/Expr.qll

@@ -2093,7 +2093,7 @@ class Argument extends Expr {
       p.isVarargs() and
       ptyp = p.getType() and
       (
-        hasSubtype*(ptyp, typ)
+        hasDescendant(ptyp, typ)
         or
         // If the types don't match then we'll guess based on whether there are type variables involved.
         hasInstantiation(ptyp.(Array).getComponentType())

java/ql/lib/semmle/code/java/GeneratedFiles.qll

@@ -18,7 +18,7 @@ class AnnotatedGeneratedClass extends GeneratedClass {
 /** A Java class generated by an ANTLR scanner or parser class. */
 class AntlrGenerated extends GeneratedClass {
   AntlrGenerated() {
-    exists(RefType t | this.getASupertype+() = t |
+    exists(RefType t | this.getAStrictAncestor() = t |
       // ANTLR v3
       t.hasQualifiedName("org.antlr.runtime", "Lexer") or
       t.hasQualifiedName("org.antlr.runtime", "Parser") or

java/ql/lib/semmle/code/java/JDK.qll

@@ -114,7 +114,7 @@ class TypeNumber extends RefType {
 
 /** A (reflexive, transitive) subtype of `java.lang.Number`. */
 class NumberType extends RefType {
-  NumberType() { exists(TypeNumber number | hasSubtype*(number, this)) }
+  NumberType() { exists(TypeNumber number | hasDescendant(number, this)) }
 }
 
 /** A numeric type, including both primitive and boxed types. */
@@ -436,13 +436,13 @@ class ArrayLengthField extends Field {
 
 /** A (reflexive, transitive) subtype of `java.lang.Throwable`. */
 class ThrowableType extends RefType {
-  ThrowableType() { exists(TypeThrowable throwable | hasSubtype*(throwable, this)) }
+  ThrowableType() { exists(TypeThrowable throwable | hasDescendant(throwable, this)) }
 }
 
 /** An unchecked exception. That is, a (reflexive, transitive) subtype of `java.lang.Error` or `java.lang.RuntimeException`. */
 class UncheckedThrowableType extends RefType {
   UncheckedThrowableType() {
-    exists(TypeError e | hasSubtype*(e, this)) or
-    exists(TypeRuntimeException e | hasSubtype*(e, this))
+    exists(TypeError e | hasDescendant(e, this)) or
+    exists(TypeRuntimeException e | hasDescendant(e, this))
   }
 }

java/ql/lib/semmle/code/java/NumberFormatException.qll

@@ -63,7 +63,7 @@ predicate catchesNFE(TryStmt t) {
   exists(CatchClause cc, LocalVariableDeclExpr v |
     t.getACatchClause() = cc and
     cc.getVariable() = v and
-    v.getType().(RefType).getASubtype*() instanceof NumberFormatException
+    v.getType().(RefType).getADescendant() instanceof NumberFormatException
   )
 }
 

java/ql/lib/semmle/code/java/Reflection.qll

@@ -295,7 +295,7 @@ class NewInstance extends MethodAccess {
       // If we cast the result of this method, then this is either the type specified, or a
       // sub-type of that type. Make sure we exclude overly generic types such as `Object`.
       not overlyGenericType(cast.getType()) and
-      hasSubtype*(cast.getType(), result)
+      hasDescendant(cast.getType(), result)
     )
   }
 }

java/ql/lib/semmle/code/java/Serializability.qll

@@ -24,7 +24,7 @@ abstract class DeserializableField extends Field { }
  */
 library class StandardSerializableField extends SerializableField, DeserializableField {
   StandardSerializableField() {
-    this.getDeclaringType().getASupertype*() instanceof TypeSerializable and
+    this.getDeclaringType().getAnAncestor() instanceof TypeSerializable and
     not this.isTransient()
   }
 }

java/ql/lib/semmle/code/java/Type.qll

@@ -37,6 +37,16 @@ predicate hasSubtype(RefType t, Type sub) {
   typeVarSubtypeBound(t, sub) and t != sub
 }
 
+/**
+ * Holds if reference type `anc` is a direct or indirect supertype of `sub`, including itself.
+ */
+cached
+predicate hasDescendant(RefType anc, Type sub) {
+  anc = sub
+  or
+  exists(RefType mid | hasSubtype(anc, mid) and hasDescendant(mid, sub))
+}
+
 private predicate typeVarSubtypeBound(RefType t, TypeVariable tv) {
   if tv.hasTypeBound() then t = tv.getATypeBound().getType() else t instanceof TypeObject
 }
@@ -394,11 +404,17 @@ class RefType extends Type, Annotatable, Modifiable, @reftype {
   /** Gets a direct subtype of this type. */
   RefType getASubtype() { hasSubtype(this, result) }
 
+  /** Gets a direct or indirect descendant of this type, including itself. */
+  RefType getADescendant() { hasDescendant(this, result) }
+
   /** Gets a direct supertype of this type. */
   RefType getASupertype() { hasSubtype(result, this) }
 
   /** Gets a direct or indirect supertype of this type, including itself. */
-  RefType getAnAncestor() { hasSubtype*(result, this) }
+  RefType getAnAncestor() { hasDescendant(result, this) }
+
+  /** Gets a direct or indirect supertype of this type, not including itself. */
+  RefType getAStrictAncestor() { result = this.getAnAncestor() and result != this }
 
   /**
    * Gets the source declaration of a direct supertype of this type, excluding itself.