Ruby: Cache ConstantReadAccess::getValue

Author: hvitved

ruby/ql/lib/codeql/ruby/ast/Constant.qll

@@ -224,21 +224,7 @@ class ConstantReadAccess extends ConstantAccess {
    *
    * the value being read at `M::CONST` is `"const"`.
    */
-  Expr getValue() {
-    not exists(this.getScopeExpr()) and
-    result = lookupConst(this.getEnclosingModule+().getModule(), this.getName()) and
-    // For now, we restrict the scope of top-level declarations to their file.
-    // This may remove some plausible targets, but also removes a lot of
-    // implausible targets
-    if result.getEnclosingModule() instanceof Toplevel
-    then result.getFile() = this.getFile()
-    else any()
-    or
-    this.hasGlobalScope() and
-    result = lookupConst(TResolved("Object"), this.getName())
-    or
-    result = lookupConst(resolveConstantReadAccess(this.getScopeExpr()), this.getName())
-  }
+  Expr getValue() { result = getConstantReadAccessValue(this) }
 
   final override string getAPrimaryQlClass() { result = "ConstantReadAccess" }
 }

ruby/ql/lib/codeql/ruby/ast/internal/Constant.qll

@@ -1,5 +1,6 @@
 private import codeql.ruby.AST
 private import codeql.ruby.ast.internal.Literal
+private import codeql.ruby.ast.internal.Module
 private import codeql.ruby.controlflow.CfgNodes
 private import codeql.ruby.dataflow.SSA
 private import ExprNodes
@@ -441,6 +442,23 @@ private module Cached {
     result.isNil() and
     isNilExpr(e)
   }
+
+  cached
+  Expr getConstantReadAccessValue(ConstantReadAccess read) {
+    not exists(read.getScopeExpr()) and
+    result = lookupConst(read.getEnclosingModule+().getModule(), read.getName()) and
+    // For now, we restrict the scope of top-level declarations to their file.
+    // This may remove some plausible targets, but also removes a lot of
+    // implausible targets
+    if result.getEnclosingModule() instanceof Toplevel
+    then result.getFile() = read.getFile()
+    else any()
+    or
+    read.hasGlobalScope() and
+    result = lookupConst(TResolved("Object"), read.getName())
+    or
+    result = lookupConst(resolveConstantReadAccess(read.getScopeExpr()), read.getName())
+  }
 }
 
 import Cached