C++/C#: Make IRVariable and its derived classes non-abstract

Author: Dave Bartolomeo

cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/IRVariable.qll

@@ -17,10 +17,16 @@ IRUserVariable getIRUserVariable(Language::Function func, Language::Variable var
  * be a user-declared variable (`IRUserVariable`) or a temporary variable
  * generated by the AST-to-IR translation (`IRTempVariable`).
  */
-abstract class IRVariable extends TIRVariable {
+class IRVariable extends TIRVariable {
   Language::Function func;
 
-  abstract string toString();
+  IRVariable() {
+    this = TIRUserVariable(_, _, func) or
+    this = TIRTempVariable(func, _, _, _) or
+    this = TIRStringLiteral(func, _, _, _)
+  }
+
+  string toString() { none() }
 
   /**
    * Holds if this variable's value cannot be changed within a function. Currently used for string
@@ -41,19 +47,19 @@ abstract class IRVariable extends TIRVariable {
   /**
    * Gets the type of the variable.
    */
-  abstract Language::LanguageType getLanguageType();
+  Language::LanguageType getLanguageType() { none() }
 
   /**
    * Gets the AST node that declared this variable, or that introduced this
    * variable as part of the AST-to-IR translation.
    */
-  abstract Language::AST getAST();
+  Language::AST getAST() { none() }
 
   /**
    * Gets an identifier string for the variable. This identifier is unique
    * within the function.
    */
-  abstract string getUniqueId();
+  string getUniqueId() { none() }
 
   /**
    * Gets the source location of this variable.
@@ -101,16 +107,31 @@ class IRUserVariable extends IRVariable, TIRUserVariable {
  * stack. This includes all parameters, non-static local variables, and
  * temporary variables.
  */
-abstract class IRAutomaticVariable extends IRVariable { }
+class IRAutomaticVariable extends IRVariable {
+  IRAutomaticVariable() {
+    exists(Language::Variable var |
+      this = TIRUserVariable(var, _, func) and
+      Language::isVariableAutomatic(var)
+    ) or
+    this = TIRTempVariable(func, _, _, _)
+  }
+}
 
+/**
+ * Represents a user-declared variable that is allocated on the stack. This
+ * includes all parameters and non-static local variables.
+ */
 class IRAutomaticUserVariable extends IRUserVariable, IRAutomaticVariable {
   override Language::AutomaticVariable var;
 
-  IRAutomaticUserVariable() { Language::isVariableAutomatic(var) }
-
   final override Language::AutomaticVariable getVariable() { result = var }
 }
 
+/**
+ * Represents a user-declared variable that is not allocated on the stack. This
+ * includes all global variables, namespace-scope variables, static fields, and
+ * static local variables.
+ */
 class IRStaticUserVariable extends IRUserVariable {
   override Language::StaticVariable var;
 
@@ -119,10 +140,19 @@ class IRStaticUserVariable extends IRUserVariable {
   final override Language::StaticVariable getVariable() { result = var }
 }
 
-abstract class IRGeneratedVariable extends IRVariable {
+/**
+ * Represents a variable that is not user-declared. This includes temporary
+ * variables generated as part of IR construction, as well as string literals.
+ */
+class IRGeneratedVariable extends IRVariable {
   Language::AST ast;
   Language::LanguageType type;
 
+  IRGeneratedVariable() {
+    this = TIRTempVariable(func, ast, _, type) or
+    this = TIRStringLiteral(func, ast, type, _)
+  }
+
   final override Language::LanguageType getLanguageType() { result = type }
 
   final override Language::AST getAST() { result = ast }
@@ -144,6 +174,11 @@ IRTempVariable getIRTempVariable(Language::AST ast, TempVariableTag tag) {
   result.getTag() = tag
 }
 
+/**
+ * Represents a temporary variable introduced by IR construction. The most common examples are the
+ * variable generated to hold the return value of afunction, or the variable generated to hold the
+ * result of a condition operator (`a ? b : c`).
+ */
 class IRTempVariable extends IRGeneratedVariable, IRAutomaticVariable, TIRTempVariable {
   TempVariableTag tag;
 
@@ -158,18 +193,28 @@ class IRTempVariable extends IRGeneratedVariable, IRAutomaticVariable, TIRTempVa
   override string getBaseString() { result = "#temp" }
 }
 
+/**
+ * The temporary variable generated to hold the return value of a function.
+ */
 class IRReturnVariable extends IRTempVariable {
   IRReturnVariable() { tag = ReturnValueTempVar() }
 
   final override string toString() { result = "#return" }
 }
 
+/**
+ * The temporary variable generated to hold the exception thrown by a `ThrowValue` instruction.
+ */
 class IRThrowVariable extends IRTempVariable {
   IRThrowVariable() { tag = ThrowTempVar() }
 
   override string getBaseString() { result = "#throw" }
 }
 
+/**
+ * The variable generated to represent the contents of a string literal. This variable acts much
+ * like a read-only global variable.
+ */
 class IRStringLiteral extends IRGeneratedVariable, TIRStringLiteral {
   Language::StringLiteral literal;
 

cpp/ql/src/semmle/code/cpp/ir/implementation/raw/IRVariable.qll

@@ -17,10 +17,16 @@ IRUserVariable getIRUserVariable(Language::Function func, Language::Variable var
  * be a user-declared variable (`IRUserVariable`) or a temporary variable
  * generated by the AST-to-IR translation (`IRTempVariable`).
  */
-abstract class IRVariable extends TIRVariable {
+class IRVariable extends TIRVariable {
   Language::Function func;
 
-  abstract string toString();
+  IRVariable() {
+    this = TIRUserVariable(_, _, func) or
+    this = TIRTempVariable(func, _, _, _) or
+    this = TIRStringLiteral(func, _, _, _)
+  }
+
+  string toString() { none() }
 
   /**
    * Holds if this variable's value cannot be changed within a function. Currently used for string
@@ -41,19 +47,19 @@ abstract class IRVariable extends TIRVariable {
   /**
    * Gets the type of the variable.
    */
-  abstract Language::LanguageType getLanguageType();
+  Language::LanguageType getLanguageType() { none() }
 
   /**
    * Gets the AST node that declared this variable, or that introduced this
    * variable as part of the AST-to-IR translation.
    */
-  abstract Language::AST getAST();
+  Language::AST getAST() { none() }
 
   /**
    * Gets an identifier string for the variable. This identifier is unique
    * within the function.
    */
-  abstract string getUniqueId();
+  string getUniqueId() { none() }
 
   /**
    * Gets the source location of this variable.
@@ -101,16 +107,31 @@ class IRUserVariable extends IRVariable, TIRUserVariable {
  * stack. This includes all parameters, non-static local variables, and
  * temporary variables.
  */
-abstract class IRAutomaticVariable extends IRVariable { }
+class IRAutomaticVariable extends IRVariable {
+  IRAutomaticVariable() {
+    exists(Language::Variable var |
+      this = TIRUserVariable(var, _, func) and
+      Language::isVariableAutomatic(var)
+    ) or
+    this = TIRTempVariable(func, _, _, _)
+  }
+}
 
+/**
+ * Represents a user-declared variable that is allocated on the stack. This
+ * includes all parameters and non-static local variables.
+ */
 class IRAutomaticUserVariable extends IRUserVariable, IRAutomaticVariable {
   override Language::AutomaticVariable var;
 
-  IRAutomaticUserVariable() { Language::isVariableAutomatic(var) }
-
   final override Language::AutomaticVariable getVariable() { result = var }
 }
 
+/**
+ * Represents a user-declared variable that is not allocated on the stack. This
+ * includes all global variables, namespace-scope variables, static fields, and
+ * static local variables.
+ */
 class IRStaticUserVariable extends IRUserVariable {
   override Language::StaticVariable var;
 
@@ -119,10 +140,19 @@ class IRStaticUserVariable extends IRUserVariable {
   final override Language::StaticVariable getVariable() { result = var }
 }
 
-abstract class IRGeneratedVariable extends IRVariable {
+/**
+ * Represents a variable that is not user-declared. This includes temporary
+ * variables generated as part of IR construction, as well as string literals.
+ */
+class IRGeneratedVariable extends IRVariable {
   Language::AST ast;
   Language::LanguageType type;
 
+  IRGeneratedVariable() {
+    this = TIRTempVariable(func, ast, _, type) or
+    this = TIRStringLiteral(func, ast, type, _)
+  }
+
   final override Language::LanguageType getLanguageType() { result = type }
 
   final override Language::AST getAST() { result = ast }
@@ -144,6 +174,11 @@ IRTempVariable getIRTempVariable(Language::AST ast, TempVariableTag tag) {
   result.getTag() = tag
 }
 
+/**
+ * Represents a temporary variable introduced by IR construction. The most common examples are the
+ * variable generated to hold the return value of afunction, or the variable generated to hold the
+ * result of a condition operator (`a ? b : c`).
+ */
 class IRTempVariable extends IRGeneratedVariable, IRAutomaticVariable, TIRTempVariable {
   TempVariableTag tag;
 
@@ -158,18 +193,28 @@ class IRTempVariable extends IRGeneratedVariable, IRAutomaticVariable, TIRTempVa
   override string getBaseString() { result = "#temp" }
 }
 
+/**
+ * The temporary variable generated to hold the return value of a function.
+ */
 class IRReturnVariable extends IRTempVariable {
   IRReturnVariable() { tag = ReturnValueTempVar() }
 
   final override string toString() { result = "#return" }
 }
 
+/**
+ * The temporary variable generated to hold the exception thrown by a `ThrowValue` instruction.
+ */
 class IRThrowVariable extends IRTempVariable {
   IRThrowVariable() { tag = ThrowTempVar() }
 
   override string getBaseString() { result = "#throw" }
 }
 
+/**
+ * The variable generated to represent the contents of a string literal. This variable acts much
+ * like a read-only global variable.
+ */
 class IRStringLiteral extends IRGeneratedVariable, TIRStringLiteral {
   Language::StringLiteral literal;