C++: Remove CP in getOperandMemoryAccess

The overrides of `Instruction.getOperandMemoryAccess` did not relate
`this` to any of its other parameters, which made it attempt to compute
the Cartesian product of `Instruction` and `TPhiOperand`. This happened
only during computation of aliased SSA. Perhaps the optimizer was able
to eliminate the CP for the non-aliased SSA computation.

With this change, I'm able to compute aliased SSA for medium-sized
snapshots.

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

@@ -602,7 +602,7 @@ class ReturnValueInstruction extends ReturnInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof ReturnValueOperand and
+    exists(this.getOperand(tag.(ReturnValueOperand))) and
     result instanceof IndirectMemoryAccess
   }
 }
@@ -629,7 +629,7 @@ class LoadInstruction extends CopyInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof CopySourceOperand and
+    exists(this.getOperand(tag.(CopySourceOperand))) and
     result instanceof IndirectMemoryAccess
   }
 
@@ -1015,7 +1015,7 @@ class ThrowValueInstruction extends ThrowInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof ExceptionOperand and
+    exists(this.getOperand(tag.(ExceptionOperand))) and
     result instanceof IndirectMemoryAccess
   }
 
@@ -1114,7 +1114,7 @@ class UnmodeledUseInstruction extends Instruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof UnmodeledUseOperand and
+    exists(this.getOperand(tag.(UnmodeledUseOperand))) and
     result instanceof UnmodeledMemoryAccess
   }
 }
@@ -1125,7 +1125,7 @@ class PhiInstruction extends Instruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof PhiOperand and
+    exists(this.getOperand(tag.(PhiOperand))) and
     result instanceof PhiMemoryAccess
   }
 

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

@@ -602,7 +602,7 @@ class ReturnValueInstruction extends ReturnInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof ReturnValueOperand and
+    exists(this.getOperand(tag.(ReturnValueOperand))) and
     result instanceof IndirectMemoryAccess
   }
 }
@@ -629,7 +629,7 @@ class LoadInstruction extends CopyInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof CopySourceOperand and
+    exists(this.getOperand(tag.(CopySourceOperand))) and
     result instanceof IndirectMemoryAccess
   }
 
@@ -1015,7 +1015,7 @@ class ThrowValueInstruction extends ThrowInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof ExceptionOperand and
+    exists(this.getOperand(tag.(ExceptionOperand))) and
     result instanceof IndirectMemoryAccess
   }
 
@@ -1114,7 +1114,7 @@ class UnmodeledUseInstruction extends Instruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof UnmodeledUseOperand and
+    exists(this.getOperand(tag.(UnmodeledUseOperand))) and
     result instanceof UnmodeledMemoryAccess
   }
 }
@@ -1125,7 +1125,7 @@ class PhiInstruction extends Instruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof PhiOperand and
+    exists(this.getOperand(tag.(PhiOperand))) and
     result instanceof PhiMemoryAccess
   }
 

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

@@ -602,7 +602,7 @@ class ReturnValueInstruction extends ReturnInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof ReturnValueOperand and
+    exists(this.getOperand(tag.(ReturnValueOperand))) and
     result instanceof IndirectMemoryAccess
   }
 }
@@ -629,7 +629,7 @@ class LoadInstruction extends CopyInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof CopySourceOperand and
+    exists(this.getOperand(tag.(CopySourceOperand))) and
     result instanceof IndirectMemoryAccess
   }
 
@@ -1015,7 +1015,7 @@ class ThrowValueInstruction extends ThrowInstruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof ExceptionOperand and
+    exists(this.getOperand(tag.(ExceptionOperand))) and
     result instanceof IndirectMemoryAccess
   }
 
@@ -1114,7 +1114,7 @@ class UnmodeledUseInstruction extends Instruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof UnmodeledUseOperand and
+    exists(this.getOperand(tag.(UnmodeledUseOperand))) and
     result instanceof UnmodeledMemoryAccess
   }
 }
@@ -1125,7 +1125,7 @@ class PhiInstruction extends Instruction {
   }
 
   override final MemoryAccessKind getOperandMemoryAccess(OperandTag tag) {
-    tag instanceof PhiOperand and
+    exists(this.getOperand(tag.(PhiOperand))) and
     result instanceof PhiMemoryAccess
   }