[GR-68341] Fix handling of StageFlag.VECTOR_API_EXPANSION

PullRequest: graal/21726

Author: gergo-

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/nodes/GraphState.java

@@ -262,7 +262,9 @@ public String updateFromPreviousToString(GraphState previous) {
         builder.append(valueStringAsDiff(previous.frameStateVerification, this.frameStateVerification, "Frame state verification: ", ", "));
         builder.append(newFlagsToString(previous.futureRequiredStages, this.futureRequiredStages, "+", "Future required stages: "));
         builder.append(newFlagsToString(this.futureRequiredStages, previous.futureRequiredStages, "-", ""));
-        builder.setLength(builder.length() - 2);
+        if (builder.length() > 1) {
+            builder.setLength(builder.length() - 2);
+        }
         builder.append('}');
         return builder.toString();
     }

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/vector/replacements/vectorapi/VectorAPIExpansionPhase.java

@@ -144,6 +144,12 @@ public Optional<NotApplicable> notApplicableTo(GraphState graphState) {
         return NotApplicable.unlessRunBefore(this, GraphState.StageFlag.HIGH_TIER_LOWERING, graphState);
     }
 
+    @Override
+    public void updateGraphState(GraphState graphState) {
+        super.updateGraphState(graphState);
+        graphState.setAfterStage(GraphState.StageFlag.VECTOR_API_EXPANSION);
+    }
+
     /**
      * A "connected component" of macro nodes connected by input/usage relationships or through phi
      * or proxy nodes.