C++: Add ReadSideEffectInstruction to IR

There was already a `WriteSideEffectInstruction` class that served as a
superclass for all the specific write side effects. This new class
serves the same purpose for read side effects.

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

@@ -1198,52 +1198,63 @@ class CallSideEffectInstruction extends SideEffectInstruction {
 }
 
 /**
- * An instruction representing the side effect of a function call on any memory that might be read
- * by that call.
+ * An instruction representing the side effect of a function call on any memory
+ * that might be read by that call. This instruction is emitted instead of
+ * `CallSideEffectInstruction` when it's certain that the call target cannot
+ * write to escaped memory.
  */
 class CallReadSideEffectInstruction extends SideEffectInstruction {
   CallReadSideEffectInstruction() { getOpcode() instanceof Opcode::CallReadSideEffect }
 }
 
+/**
+ * An instruction representing a read side effect of a function call on a
+ * specific parameter.
+ */
+class ReadSideEffectInstruction extends SideEffectInstruction, IndexedInstruction {
+  ReadSideEffectInstruction() { getOpcode() instanceof ReadSideEffectOpcode }
+
+  /** Gets the operand for the value that will be read from this instruction, if known. */
+  final SideEffectOperand getSideEffectOperand() { result = getAnOperand() }
+
+  /** Gets the value that will be read from this instruction, if known. */
+  final Instruction getSideEffect() { result = getSideEffectOperand().getDef() }
+
+  /** Gets the operand for the address from which this instruction may read. */
+  final AddressOperand getArgumentOperand() { result = getAnOperand() }
+
+  /** Gets the address from which this instruction may read. */
+  final Instruction getArgumentDef() { result = getArgumentOperand().getDef() }
+}
+
 /**
  * An instruction representing the read of an indirect parameter within a function call.
  */
-class IndirectReadSideEffectInstruction extends SideEffectInstruction {
+class IndirectReadSideEffectInstruction extends ReadSideEffectInstruction {
   IndirectReadSideEffectInstruction() { getOpcode() instanceof Opcode::IndirectReadSideEffect }
-
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
  * An instruction representing the read of an indirect buffer parameter within a function call.
  */
-class BufferReadSideEffectInstruction extends SideEffectInstruction {
+class BufferReadSideEffectInstruction extends ReadSideEffectInstruction {
   BufferReadSideEffectInstruction() { getOpcode() instanceof Opcode::BufferReadSideEffect }
-
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
  * An instruction representing the read of an indirect buffer parameter within a function call.
  */
-class SizedBufferReadSideEffectInstruction extends SideEffectInstruction {
+class SizedBufferReadSideEffectInstruction extends ReadSideEffectInstruction {
   SizedBufferReadSideEffectInstruction() {
     getOpcode() instanceof Opcode::SizedBufferReadSideEffect
   }
 
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
   Instruction getSizeDef() { result = getAnOperand().(BufferSizeOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
- * An instruction representing a side effect of a function call.
+ * An instruction representing a write side effect of a function call on a
+ * specific parameter.
  */
 class WriteSideEffectInstruction extends SideEffectInstruction, IndexedInstruction {
   WriteSideEffectInstruction() { getOpcode() instanceof WriteSideEffectOpcode }

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

@@ -1198,52 +1198,63 @@ class CallSideEffectInstruction extends SideEffectInstruction {
 }
 
 /**
- * An instruction representing the side effect of a function call on any memory that might be read
- * by that call.
+ * An instruction representing the side effect of a function call on any memory
+ * that might be read by that call. This instruction is emitted instead of
+ * `CallSideEffectInstruction` when it's certain that the call target cannot
+ * write to escaped memory.
  */
 class CallReadSideEffectInstruction extends SideEffectInstruction {
   CallReadSideEffectInstruction() { getOpcode() instanceof Opcode::CallReadSideEffect }
 }
 
+/**
+ * An instruction representing a read side effect of a function call on a
+ * specific parameter.
+ */
+class ReadSideEffectInstruction extends SideEffectInstruction, IndexedInstruction {
+  ReadSideEffectInstruction() { getOpcode() instanceof ReadSideEffectOpcode }
+
+  /** Gets the operand for the value that will be read from this instruction, if known. */
+  final SideEffectOperand getSideEffectOperand() { result = getAnOperand() }
+
+  /** Gets the value that will be read from this instruction, if known. */
+  final Instruction getSideEffect() { result = getSideEffectOperand().getDef() }
+
+  /** Gets the operand for the address from which this instruction may read. */
+  final AddressOperand getArgumentOperand() { result = getAnOperand() }
+
+  /** Gets the address from which this instruction may read. */
+  final Instruction getArgumentDef() { result = getArgumentOperand().getDef() }
+}
+
 /**
  * An instruction representing the read of an indirect parameter within a function call.
  */
-class IndirectReadSideEffectInstruction extends SideEffectInstruction {
+class IndirectReadSideEffectInstruction extends ReadSideEffectInstruction {
   IndirectReadSideEffectInstruction() { getOpcode() instanceof Opcode::IndirectReadSideEffect }
-
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
  * An instruction representing the read of an indirect buffer parameter within a function call.
  */
-class BufferReadSideEffectInstruction extends SideEffectInstruction {
+class BufferReadSideEffectInstruction extends ReadSideEffectInstruction {
   BufferReadSideEffectInstruction() { getOpcode() instanceof Opcode::BufferReadSideEffect }
-
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
  * An instruction representing the read of an indirect buffer parameter within a function call.
  */
-class SizedBufferReadSideEffectInstruction extends SideEffectInstruction {
+class SizedBufferReadSideEffectInstruction extends ReadSideEffectInstruction {
   SizedBufferReadSideEffectInstruction() {
     getOpcode() instanceof Opcode::SizedBufferReadSideEffect
   }
 
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
   Instruction getSizeDef() { result = getAnOperand().(BufferSizeOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
- * An instruction representing a side effect of a function call.
+ * An instruction representing a write side effect of a function call on a
+ * specific parameter.
  */
 class WriteSideEffectInstruction extends SideEffectInstruction, IndexedInstruction {
   WriteSideEffectInstruction() { getOpcode() instanceof WriteSideEffectOpcode }

cpp/ql/src/semmle/code/cpp/ir/implementation/unaliased_ssa/Instruction.qll

@@ -1198,52 +1198,63 @@ class CallSideEffectInstruction extends SideEffectInstruction {
 }
 
 /**
- * An instruction representing the side effect of a function call on any memory that might be read
- * by that call.
+ * An instruction representing the side effect of a function call on any memory
+ * that might be read by that call. This instruction is emitted instead of
+ * `CallSideEffectInstruction` when it's certain that the call target cannot
+ * write to escaped memory.
  */
 class CallReadSideEffectInstruction extends SideEffectInstruction {
   CallReadSideEffectInstruction() { getOpcode() instanceof Opcode::CallReadSideEffect }
 }
 
+/**
+ * An instruction representing a read side effect of a function call on a
+ * specific parameter.
+ */
+class ReadSideEffectInstruction extends SideEffectInstruction, IndexedInstruction {
+  ReadSideEffectInstruction() { getOpcode() instanceof ReadSideEffectOpcode }
+
+  /** Gets the operand for the value that will be read from this instruction, if known. */
+  final SideEffectOperand getSideEffectOperand() { result = getAnOperand() }
+
+  /** Gets the value that will be read from this instruction, if known. */
+  final Instruction getSideEffect() { result = getSideEffectOperand().getDef() }
+
+  /** Gets the operand for the address from which this instruction may read. */
+  final AddressOperand getArgumentOperand() { result = getAnOperand() }
+
+  /** Gets the address from which this instruction may read. */
+  final Instruction getArgumentDef() { result = getArgumentOperand().getDef() }
+}
+
 /**
  * An instruction representing the read of an indirect parameter within a function call.
  */
-class IndirectReadSideEffectInstruction extends SideEffectInstruction {
+class IndirectReadSideEffectInstruction extends ReadSideEffectInstruction {
   IndirectReadSideEffectInstruction() { getOpcode() instanceof Opcode::IndirectReadSideEffect }
-
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
  * An instruction representing the read of an indirect buffer parameter within a function call.
  */
-class BufferReadSideEffectInstruction extends SideEffectInstruction {
+class BufferReadSideEffectInstruction extends ReadSideEffectInstruction {
   BufferReadSideEffectInstruction() { getOpcode() instanceof Opcode::BufferReadSideEffect }
-
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
  * An instruction representing the read of an indirect buffer parameter within a function call.
  */
-class SizedBufferReadSideEffectInstruction extends SideEffectInstruction {
+class SizedBufferReadSideEffectInstruction extends ReadSideEffectInstruction {
   SizedBufferReadSideEffectInstruction() {
     getOpcode() instanceof Opcode::SizedBufferReadSideEffect
   }
 
-  Instruction getArgumentDef() { result = getAnOperand().(AddressOperand).getDef() }
-
   Instruction getSizeDef() { result = getAnOperand().(BufferSizeOperand).getDef() }
-
-  Instruction getSideEffect() { result = getAnOperand().(SideEffectOperand).getDef() }
 }
 
 /**
- * An instruction representing a side effect of a function call.
+ * An instruction representing a write side effect of a function call on a
+ * specific parameter.
  */
 class WriteSideEffectInstruction extends SideEffectInstruction, IndexedInstruction {
   WriteSideEffectInstruction() { getOpcode() instanceof WriteSideEffectOpcode }