JS: Avoid more bad joins due to locality

Author: asgerf

javascript/ql/lib/semmle/javascript/AST.qll

@@ -474,6 +474,8 @@ module AST {
     DataFlow::AnalyzedNode analyze() { result = DataFlow::valueNode(this).analyze() }
 
     /** Gets the data flow node associated with this program element. */
+    overlay[caller]
+    pragma[inline]
     DataFlow::ValueNode flow() { result = DataFlow::valueNode(this) }
 
     /**

javascript/ql/lib/semmle/javascript/Regexp.qll

@@ -1009,7 +1009,7 @@ private predicate isUsedAsNonMatchObject(DataFlow::MethodCallNode call) {
 pragma[inline]
 private predicate isUsedAsNumber(DataFlow::LocalSourceNode value) {
   any(Comparison compare)
-      .hasOperands(value.getALocalUse().asExpr(), any(Expr e | e.analyze().getAType() = TTNumber()))
+      .hasOperands(value.getALocalUse().asExpr(), any(Expr e | canBeNumber(e.analyze())))
   or
   value.flowsToExpr(any(ArithmeticExpr e).getAnOperand())
   or
@@ -1024,20 +1024,30 @@ private predicate isUsedAsNumber(DataFlow::LocalSourceNode value) {
   )
 }
 
+bindingset[node]
+overlay[global]
+pragma[inline_late]
+private predicate canBeString(DataFlow::AnalyzedNode node) { node.getAType() = TTString() }
+
+bindingset[node]
+overlay[global]
+pragma[inline_late]
+private predicate canBeNumber(DataFlow::AnalyzedNode node) { node.getAType() = TTNumber() }
+
 /**
  * Holds if `source` may be interpreted as a regular expression.
  */
 cached
 predicate isInterpretedAsRegExp(DataFlow::Node source) {
   Stages::Taint::ref() and
-  source.analyze().getAType() = TTString() and
+  canBeString(source) and
   (
     // The first argument to an invocation of `RegExp` (with or without `new`).
     source = DataFlow::globalVarRef("RegExp").getAnInvocation().getArgument(0)
     or
     // The argument of a call that coerces the argument to a regular expression.
     exists(DataFlow::MethodCallNode mce, string methodName |
-      mce.getReceiver().analyze().getAType() = TTString() and
+      canBeString(mce.getReceiver()) and
       mce.getMethodName() = methodName and
       not exists(Function func | func = mce.getACallee() |
         not isNativeStringMethod(func, methodName)

javascript/ql/lib/semmle/javascript/dataflow/DataFlow.qll

@@ -1419,6 +1419,7 @@ module DataFlow {
    * This predicate is only defined for expressions, properties, and for statements that declare
    * a function, a class, or a TypeScript namespace or enum.
    */
+  pragma[nomagic]
   ValueNode valueNode(AstNode nd) { result.getAstNode() = nd }
 
   /**

javascript/ql/lib/semmle/javascript/frameworks/LazyCache.qll

@@ -43,7 +43,7 @@ module LazyCache {
     pragma[noopt]
     override DataFlow::Node getImportedModuleNode() {
       this instanceof LazyCacheImport and
-      result = this.flow()
+      result = DataFlow::valueNode(this)
       or
       exists(LazyCacheVariable variable, Expr base, PropAccess access, string localName |
         // To avoid recursion, this should not depend on `SourceNode`.
@@ -52,7 +52,7 @@ module LazyCache {
         access.getBase() = base and
         localName = this.getLocalAlias() and
         access.getPropertyName() = localName and
-        result = access.flow()
+        result = DataFlow::valueNode(access)
       )
     }
   }

javascript/ql/lib/semmle/javascript/internal/flow_summaries/ForOfLoops.qll

@@ -48,12 +48,18 @@ class ForOfLoopStep extends AdditionalFlowInternal {
   ) {
     exists(ForOfStmt stmt |
       pred = getSynthesizedNode(stmt, "for-of-map-key") and
-      contents.asSingleton().asArrayIndex() = 0
+      contents = arrayIndex0()
       or
       pred = getSynthesizedNode(stmt, "for-of-map-value") and
-      contents.asSingleton().asArrayIndex() = 1
+      contents = arrayIndex1()
     |
       succ = DataFlow::lvalueNode(stmt.getLValue())
     )
   }
 }
+
+pragma[nomagic]
+private DataFlow::ContentSet arrayIndex0() { result.asSingleton().asArrayIndex() = 0 }
+
+pragma[nomagic]
+private DataFlow::ContentSet arrayIndex1() { result.asSingleton().asArrayIndex() = 1 }