Merge pull request #2017 from AndreiDiaconu1/ircsharp-various

C# IR: Some minor additions

Author: calumgrant

csharp/ql/src/semmle/code/csharp/ir/implementation/raw/internal/TranslatedElement.qll

@@ -99,6 +99,12 @@ private predicate ignoreExprOnly(Expr expr) {
   // Ignore the expression (that is not a declaration)
   // that appears in a using block
   expr.getParent().(UsingBlockStmt).getExpr() = expr
+  or
+  // Ignore the `ThisAccess` when it is used as the qualifier for
+  // a callable access (e.g. when a member callable is passed as a
+  // parameter for a delegate creation expression)
+  expr instanceof ThisAccess and
+  expr.getParent() instanceof CallableAccess
 }
 
 /**
@@ -199,6 +205,10 @@ private predicate ignoreLoad(Expr expr) {
   // to get the address of the first element in an array
   expr = any(ArrayAccess aa).getQualifier()
   or
+  // Indexer calls returns a reference or a value,
+  // no need to load it
+  expr instanceof IndexerCall
+  or
   // No load is needed for the lvalue in an assignment such as:
   // Eg. `Object obj = oldObj`;
   expr = any(Assignment a).getLValue() and

csharp/ql/src/semmle/code/csharp/ir/implementation/raw/internal/TranslatedExpr.qll

@@ -1382,6 +1382,11 @@ class TranslatedAssignExpr extends TranslatedAssignment {
 class TranslatedAssignOperation extends TranslatedAssignment {
   override AssignOperation expr;
 
+  TranslatedAssignOperation() {
+    // Assignments to events is handled differently
+    not expr.getLValue() instanceof EventAccess
+  }
+
   override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) {
     kind instanceof GotoEdge and
     (
@@ -1893,104 +1898,6 @@ class TranslatedIsExpr extends TranslatedNonConstantExpr {
   }
 }
 
-/**
- * The IR translation of a lambda expression. This initializes a temporary variable whose type is that of the lambda,
- * using the initializer list that represents the captures of the lambda.
- */
-class TranslatedLambdaExpr extends TranslatedNonConstantExpr, InitializationContext {
-  override LambdaExpr expr;
-
-  final override Instruction getFirstInstruction() {
-    result = this.getInstruction(InitializerVariableAddressTag())
-  }
-
-  final override TranslatedElement getChild(int id) { id = 0 and result = this.getInitialization() }
-
-  override Instruction getResult() { result = this.getInstruction(LoadTag()) }
-
-  override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) {
-    tag = InitializerVariableAddressTag() and
-    kind instanceof GotoEdge and
-    result = this.getInstruction(InitializerStoreTag())
-    or
-    tag = InitializerStoreTag() and
-    kind instanceof GotoEdge and
-    (
-      result = this.getInitialization().getFirstInstruction()
-      or
-      not this.hasInitializer() and result = this.getInstruction(LoadTag())
-    )
-    or
-    tag = LoadTag() and
-    kind instanceof GotoEdge and
-    result = this.getParent().getChildSuccessor(this)
-  }
-
-  override Instruction getChildSuccessor(TranslatedElement child) {
-    child = getInitialization() and
-    result = this.getInstruction(LoadTag())
-  }
-
-  override predicate hasInstruction(
-    Opcode opcode, InstructionTag tag, Type resultType, boolean isLValue
-  ) {
-    tag = InitializerVariableAddressTag() and
-    opcode instanceof Opcode::VariableAddress and
-    resultType = this.getResultType() and
-    isLValue = true
-    or
-    tag = InitializerStoreTag() and
-    opcode instanceof Opcode::Uninitialized and
-    resultType = this.getResultType() and
-    isLValue = false
-    or
-    tag = LoadTag() and
-    opcode instanceof Opcode::Load and
-    resultType = this.getResultType() and
-    isLValue = false
-  }
-
-  override Instruction getInstructionOperand(InstructionTag tag, OperandTag operandTag) {
-    tag = InitializerStoreTag() and
-    operandTag instanceof AddressOperandTag and
-    result = this.getInstruction(InitializerVariableAddressTag())
-    or
-    tag = LoadTag() and
-    (
-      operandTag instanceof AddressOperandTag and
-      result = this.getInstruction(InitializerVariableAddressTag())
-      or
-      operandTag instanceof LoadOperandTag and
-      result = this.getEnclosingFunction().getUnmodeledDefinitionInstruction()
-    )
-  }
-
-  override IRVariable getInstructionVariable(InstructionTag tag) {
-    (
-      tag = InitializerVariableAddressTag() or
-      tag = InitializerStoreTag()
-    ) and
-    result = this.getTempVariable(LambdaTempVar())
-  }
-
-  override predicate hasTempVariable(TempVariableTag tag, Type type) {
-    tag = LambdaTempVar() and
-    type = this.getResultType()
-  }
-
-  final override Instruction getTargetAddress() {
-    result = this.getInstruction(InitializerVariableAddressTag())
-  }
-
-  final override Type getTargetType() { result = this.getResultType() }
-
-  private predicate hasInitializer() { exists(this.getInitialization()) }
-
-  private TranslatedInitialization getInitialization() {
-    result = getTranslatedInitialization(expr.getChild(0))
-  }
-}
-
 /**
  * The translation of a `DelegateCall`. Since this type of call needs
  * desugaring, we treat it as a special case. The AST node of the
@@ -2155,3 +2062,37 @@ class TranslatedDelegateCreation extends TranslatedCreation {
 
   override predicate needsLoad() { none() }
 }
+
+/**
+ * Represents the IR translation of an assign operation where the lhs is an event access.
+ */
+class TranslatedEventAccess extends TranslatedNonConstantExpr {
+  override AssignOperation expr;
+
+  TranslatedEventAccess() { expr.getLValue() instanceof EventAccess }
+
+  // We only translate the lhs, since the rhs is translated as part of the
+  // accessor call.
+  override TranslatedElement getChild(int id) { id = 0 and result = this.getLValue() }
+
+  override predicate hasInstruction(
+    Opcode opcode, InstructionTag tag, Type resultType, boolean isLValue
+  ) {
+    none()
+  }
+
+  final override Instruction getFirstInstruction() {
+    result = this.getLValue().getFirstInstruction()
+  }
+
+  override Instruction getResult() { none() }
+
+  override Instruction getInstructionSuccessor(InstructionTag tag, EdgeKind kind) { none() }
+
+  override Instruction getChildSuccessor(TranslatedElement child) {
+    child = this.getLValue() and
+    result = this.getParent().getChildSuccessor(this)
+  }
+
+  private TranslatedExpr getLValue() { result = getTranslatedExpr(expr.getLValue()) }
+}

csharp/ql/test/library-tests/ir/ir/events.cs

@@ -0,0 +1,35 @@
+class Events
+{
+    public delegate string MyDel(string str);
+    public MyDel Inst;
+
+    event MyDel MyEvent;
+
+    public Events()
+    {
+        this.Inst = new MyDel(this.Fun);
+    }
+
+    public void AddEvent() 
+    {
+        this.MyEvent += this.Inst;
+    }
+
+    public void RemoveEvent()
+    {
+        this.MyEvent -= this.Inst;
+    }
+
+    public string Fun(string str) 
+    {
+        return str;
+    }
+    
+    static void Main(string[] args) 
+    {
+        Events obj = new Events();
+        obj.AddEvent();
+        string result = obj.MyEvent("string");
+        obj.RemoveEvent();
+    }
+}

csharp/ql/test/library-tests/ir/ir/indexers.cs

@@ -0,0 +1,30 @@
+class Indexers
+{
+    public class MyClass
+    {
+        public MyClass()
+        {
+        }
+
+        private string[] address = new string[2];
+        public string this[int index]
+        {
+            get
+            {
+                return address[index];
+            }
+            set
+            {
+                address[index] = value;
+            }
+        }
+    }
+
+    public static void Main()
+    {
+        MyClass inst = new MyClass();
+        inst[0] = "str1";
+        inst[1] = "str1";
+        inst[1] = inst[0];
+    }
+}