Ensure a unique fallback is created for a given method.

Author: teshull

substratevm/src/com.oracle.graal.pointsto/src/com/oracle/graal/pointsto/meta/AnalysisType.java

@@ -1128,7 +1128,12 @@ public AnalysisMethod resolveConcreteMethod(ResolvedJavaMethod method, ResolvedJ
                     var concreteMethod = originalMethod instanceof BaseLayerMethod ? originalMethod : wrapped.resolveConcreteMethod(originalMethod, originalCallerType);
                     newResolvedMethod = universe.lookup(concreteMethod);
                     if (newResolvedMethod == null) {
-                        newResolvedMethod = getUniverse().getBigbang().fallbackResolveConcreteMethod(this, (AnalysisMethod) method);
+                        /* Ensure we only calculate the fallback method once. */
+                        resolvedMethod = resolvedMethods.computeIfAbsent(method, (k) -> {
+                            var fallbackMethod = getUniverse().getBigbang().fallbackResolveConcreteMethod(this, (AnalysisMethod) method);
+                            return fallbackMethod == null ? NULL_METHOD : fallbackMethod;
+                        });
+                        return resolvedMethod == NULL_METHOD ? null : (AnalysisMethod) resolvedMethod;
                     }
 
                 } catch (UnsupportedFeatureException e) {