graal/com.oracle.graal.replacements/src/com/oracle/graal/replacements/ReplacementsImpl.java

*** 301,317 ****
  
      public Assumptions getAssumptions() {
          return assumptions;
      }
  
!     private static SubstitutionGuard getGuard(Class<? extends SubstitutionGuard> guardClass) {
          if (guardClass != SubstitutionGuard.class) {
              try {
!                 return guardClass.newInstance();
              } catch (Exception e) {
                  throw new GraalInternalError(e);
              }
          }
          return null;
      }
  
      private static String getOriginalInternalName(Class<?> substitutions) {
--- 301,331 ----
  
      public Assumptions getAssumptions() {
          return assumptions;
      }
  
!     private SubstitutionGuard getGuard(Class<? extends SubstitutionGuard> guardClass) {
          if (guardClass != SubstitutionGuard.class) {
+             Constructor<?>[] constructors = guardClass.getConstructors();
+             if (constructors.length != 1) {
+                 throw new GraalInternalError("Substitution guard " + guardClass.getSimpleName() + " must have a single public constructor");
+             }
+             Constructor<?> constructor = constructors[0];
+             Class<?>[] paramTypes = constructor.getParameterTypes();
+             // Check for supported constructor signatures
              try {
!                 if (constructor.getParameterCount() == 1 && paramTypes[0] == Architecture.class) {
!                     // Guard(Architecture)
!                     return (SubstitutionGuard) constructor.newInstance(target.arch);
!                 } else if (constructor.getParameterCount() == 0) {
!                     // Guard()
!                     return (SubstitutionGuard) constructor.newInstance();
!                 }
              } catch (Exception e) {
                  throw new GraalInternalError(e);
              }
+             throw new GraalInternalError("Unsupported constructor signature in substitution guard: " + constructor);
          }
          return null;
      }
  
      private static String getOriginalInternalName(Class<?> substitutions) {