Merge pull request #2289 from jbj/ConvertToNonVirtualBaseInstruction

C++ IR: clearly distinguish between virtual and non-virtual base conversions

cpp/ql/src/semmle/code/cpp/ir/implementation/Opcode.qll

@@ -34,7 +34,7 @@ private newtype TOpcode =
   TPointerSub() or
   TPointerDiff() or
   TConvert() or
-  TConvertToBase() or
+  TConvertToNonVirtualBase() or
   TConvertToVirtualBase() or
   TConvertToDerived() or
   TCheckedConvertOrNull() or
@@ -110,6 +110,8 @@ abstract class RelationalOpcode extends CompareOpcode { }
 
 abstract class CopyOpcode extends Opcode { }
 
+abstract class ConvertToBaseOpcode extends UnaryOpcode { }
+
 abstract class MemoryAccessOpcode extends Opcode { }
 
 abstract class ReturnOpcode extends Opcode { }
@@ -302,11 +304,11 @@ module Opcode {
     final override string toString() { result = "Convert" }
   }
 
-  class ConvertToBase extends UnaryOpcode, TConvertToBase {
-    final override string toString() { result = "ConvertToBase" }
+  class ConvertToNonVirtualBase extends ConvertToBaseOpcode, TConvertToNonVirtualBase {
+    final override string toString() { result = "ConvertToNonVirtualBase" }
   }
 
-  class ConvertToVirtualBase extends UnaryOpcode, TConvertToVirtualBase {
+  class ConvertToVirtualBase extends ConvertToBaseOpcode, TConvertToVirtualBase {
     final override string toString() { result = "ConvertToVirtualBase" }
   }
 

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

@@ -981,14 +981,22 @@ class InheritanceConversionInstruction extends UnaryInstruction {
  * to the address of a direct non-virtual base class.
  */
 class ConvertToBaseInstruction extends InheritanceConversionInstruction {
-  ConvertToBaseInstruction() { getOpcode() instanceof Opcode::ConvertToBase }
+  ConvertToBaseInstruction() { getOpcode() instanceof ConvertToBaseOpcode }
+}
+
+/**
+ * Represents an instruction that converts from the address of a derived class
+ * to the address of a direct non-virtual base class.
+ */
+class ConvertToNonVirtualBaseInstruction extends ConvertToBaseInstruction {
+  ConvertToNonVirtualBaseInstruction() { getOpcode() instanceof Opcode::ConvertToNonVirtualBase }
 }
 
 /**
  * Represents an instruction that converts from the address of a derived class
  * to the address of a virtual base class.
  */
-class ConvertToVirtualBaseInstruction extends InheritanceConversionInstruction {
+class ConvertToVirtualBaseInstruction extends ConvertToBaseInstruction {
   ConvertToVirtualBaseInstruction() { getOpcode() instanceof Opcode::ConvertToVirtualBase }
 }
 

cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/AliasAnalysis.qll

@@ -109,7 +109,7 @@ private predicate operandIsPropagated(Operand operand, IntValue bitOffset) {
     instr = operand.getUse() and
     (
       // Converting to a non-virtual base class adds the offset of the base class.
-      exists(ConvertToBaseInstruction convert |
+      exists(ConvertToNonVirtualBaseInstruction convert |
         convert = instr and
         bitOffset = Ints::mul(convert.getDerivation().getByteOffset(), 8)
       )

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

@@ -981,14 +981,22 @@ class InheritanceConversionInstruction extends UnaryInstruction {
  * to the address of a direct non-virtual base class.
  */
 class ConvertToBaseInstruction extends InheritanceConversionInstruction {
-  ConvertToBaseInstruction() { getOpcode() instanceof Opcode::ConvertToBase }
+  ConvertToBaseInstruction() { getOpcode() instanceof ConvertToBaseOpcode }
+}
+
+/**
+ * Represents an instruction that converts from the address of a derived class
+ * to the address of a direct non-virtual base class.
+ */
+class ConvertToNonVirtualBaseInstruction extends ConvertToBaseInstruction {
+  ConvertToNonVirtualBaseInstruction() { getOpcode() instanceof Opcode::ConvertToNonVirtualBase }
 }
 
 /**
  * Represents an instruction that converts from the address of a derived class
  * to the address of a virtual base class.
  */
-class ConvertToVirtualBaseInstruction extends InheritanceConversionInstruction {
+class ConvertToVirtualBaseInstruction extends ConvertToBaseInstruction {
   ConvertToVirtualBaseInstruction() { getOpcode() instanceof Opcode::ConvertToVirtualBase }
 }
 

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

@@ -1038,7 +1038,7 @@ class TranslatedInheritanceConversion extends TranslatedSingleInstructionConvers
     then
       if expr.(BaseClassConversion).isVirtual()
       then result instanceof Opcode::ConvertToVirtualBase
-      else result instanceof Opcode::ConvertToBase
+      else result instanceof Opcode::ConvertToNonVirtualBase
     else result instanceof Opcode::ConvertToDerived
   }
 }

cpp/ql/src/semmle/code/cpp/ir/implementation/raw/internal/TranslatedInitialization.qll

@@ -752,7 +752,7 @@ abstract class TranslatedBaseStructorCall extends TranslatedStructorCallFromStru
 
   final override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
     tag = OnlyInstructionTag() and
-    opcode instanceof Opcode::ConvertToBase and
+    opcode instanceof Opcode::ConvertToNonVirtualBase and
     resultType = getTypeForGLValue(call.getTarget().getDeclaringType())
   }
 

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

@@ -981,14 +981,22 @@ class InheritanceConversionInstruction extends UnaryInstruction {
  * to the address of a direct non-virtual base class.
  */
 class ConvertToBaseInstruction extends InheritanceConversionInstruction {
-  ConvertToBaseInstruction() { getOpcode() instanceof Opcode::ConvertToBase }
+  ConvertToBaseInstruction() { getOpcode() instanceof ConvertToBaseOpcode }
+}
+
+/**
+ * Represents an instruction that converts from the address of a derived class
+ * to the address of a direct non-virtual base class.
+ */
+class ConvertToNonVirtualBaseInstruction extends ConvertToBaseInstruction {
+  ConvertToNonVirtualBaseInstruction() { getOpcode() instanceof Opcode::ConvertToNonVirtualBase }
 }
 
 /**
  * Represents an instruction that converts from the address of a derived class
  * to the address of a virtual base class.
  */
-class ConvertToVirtualBaseInstruction extends InheritanceConversionInstruction {
+class ConvertToVirtualBaseInstruction extends ConvertToBaseInstruction {
   ConvertToVirtualBaseInstruction() { getOpcode() instanceof Opcode::ConvertToVirtualBase }
 }
 

cpp/ql/src/semmle/code/cpp/ir/implementation/unaliased_ssa/internal/AliasAnalysis.qll

@@ -109,7 +109,7 @@ private predicate operandIsPropagated(Operand operand, IntValue bitOffset) {
     instr = operand.getUse() and
     (
       // Converting to a non-virtual base class adds the offset of the base class.
-      exists(ConvertToBaseInstruction convert |
+      exists(ConvertToNonVirtualBaseInstruction convert |
         convert = instr and
         bitOffset = Ints::mul(convert.getDerivation().getByteOffset(), 8)
       )