C++: Expose PresentIRFunction and override in cpp/count-ir-inconsistencies

The `toString` implementtion that `PresentIRFunction` uses may result in very
long strings that may crash the evaluator. Overriding allows is to limit the
string size and still suffices when just counting the number of inconsistencies.

Author: jketema

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/IRConsistency.qll

@@ -22,7 +22,7 @@ module InstructionConsistency {
     abstract Language::Location getLocation();
   }
 
-  private class PresentIRFunction extends OptionalIRFunction, TPresentIRFunction {
+  class PresentIRFunction extends OptionalIRFunction, TPresentIRFunction {
     private IRFunction irFunc;
 
     PresentIRFunction() { this = TPresentIRFunction(irFunc) }
@@ -37,6 +37,8 @@ module InstructionConsistency {
       result =
         min(Language::Location loc | loc = irFunc.getLocation() | loc order by loc.toString())
     }
+
+    IRFunction getIRFunction() { result = irFunc }
   }
 
   private class MissingIRFunction extends OptionalIRFunction, TMissingIRFunction {

cpp/ql/src/Metrics/Internal/IRConsistency.ql

@@ -10,6 +10,12 @@ import cpp
 import semmle.code.cpp.ir.implementation.aliased_ssa.IR
 import semmle.code.cpp.ir.implementation.aliased_ssa.IRConsistency as IRConsistency
 
+class PresentIRFunction extends IRConsistency::PresentIRFunction {
+  override string toString() {
+    result = min(string name | name = this.getIRFunction().getFunction().getQualifiedName() | name)
+  }
+}
+
 select count(Instruction i | IRConsistency::missingOperand(i, _, _, _) | i) as missingOperand,
   count(Instruction i | IRConsistency::unexpectedOperand(i, _, _, _) | i) as unexpectedOperand,
   count(Instruction i | IRConsistency::duplicateOperand(i, _, _, _) | i) as duplicateOperand,