C++: Remove TInitializeThisValueNumber case from IR value numbering

Author: MathiasVP

cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/gvn/ValueNumbering.qll

@@ -56,8 +56,6 @@ class ValueNumber extends TValueNumber {
     or
     this instanceof TInitializeParameterValueNumber and result = "InitializeParameter"
     or
-    this instanceof TInitializeThisValueNumber and result = "InitializeThis"
-    or
     this instanceof TStringConstantValueNumber and result = "StringConstant"
     or
     this instanceof TFieldAddressValueNumber and result = "FieldAddress"

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

@@ -7,7 +7,6 @@ newtype TValueNumber =
   TInitializeParameterValueNumber(IRFunction irFunc, Language::AST var) {
     initializeParameterValueNumber(_, irFunc, var)
   } or
-  TInitializeThisValueNumber(IRFunction irFunc) { initializeThisValueNumber(_, irFunc) } or
   TConstantValueNumber(IRFunction irFunc, IRType type, string value) {
     constantValueNumber(_, irFunc, type, value)
   } or
@@ -79,8 +78,6 @@ private predicate numberableInstruction(Instruction instr) {
   or
   instr instanceof InitializeParameterInstruction
   or
-  instr instanceof InitializeThisInstruction
-  or
   instr instanceof ConstantInstruction
   or
   instr instanceof StringConstantInstruction
@@ -132,10 +129,6 @@ private predicate initializeParameterValueNumber(
   instr.getIRVariable().getAST() = var
 }
 
-private predicate initializeThisValueNumber(InitializeThisInstruction instr, IRFunction irFunc) {
-  instr.getEnclosingIRFunction() = irFunc
-}
-
 private predicate constantValueNumber(
   ConstantInstruction instr, IRFunction irFunc, IRType type, string value
 ) {
@@ -268,9 +261,6 @@ private TValueNumber nonUniqueValueNumber(Instruction instr) {
         result = TInitializeParameterValueNumber(irFunc, var)
       )
       or
-      initializeThisValueNumber(instr, irFunc) and
-      result = TInitializeThisValueNumber(irFunc)
-      or
       exists(string value, IRType type |
         constantValueNumber(instr, irFunc, type, value) and
         result = TConstantValueNumber(irFunc, type, value)