C++: Forward to a cached predicate in a cached module instead of caching the predicate in 'Instruction.qll' to include it in the cached stage of the other predicates.

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

@@ -247,8 +247,7 @@ class Instruction extends Construction::TStageInstruction {
    * Gets the type of the result produced by this instruction. If the instruction does not produce
    * a result, its result type will be `IRVoidType`.
    */
-  cached
-  final IRType getResultIRType() { result = this.getResultLanguageType().getIRType() }
+  final IRType getResultIRType() { result = Construction::getInstructionResultIRType(this) }
 
   /**
    * Gets the type of the result produced by this instruction. If the

cpp/ql/lib/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll

@@ -429,6 +429,11 @@ private module Cached {
     instr = unreachedInstruction(_) and result = Language::getVoidType()
   }
 
+  cached
+  IRType getInstructionResultIRType(Instruction instr) {
+    result = instr.getResultLanguageType().getIRType()
+  }
+
   /**
    * Holds if `opcode` is the opcode that specifies the operation performed by `instr`.
    *