[GR-62435] Expand fixed guards during GuardLowering

PullRequest: graal/20118

Author: gergo-

compiler/src/jdk.graal.compiler/src/jdk/graal/compiler/phases/common/GuardLoweringPhase.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2013, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2013, 2025, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -33,6 +33,7 @@
 import jdk.graal.compiler.nodes.AbstractBeginNode;
 import jdk.graal.compiler.nodes.BeginNode;
 import jdk.graal.compiler.nodes.DeoptimizeNode;
+import jdk.graal.compiler.nodes.FixedGuardNode;
 import jdk.graal.compiler.nodes.FixedWithNextNode;
 import jdk.graal.compiler.nodes.GraphState;
 import jdk.graal.compiler.nodes.GraphState.GuardsStage;
@@ -50,12 +51,14 @@
 import jdk.graal.compiler.phases.schedule.SchedulePhase;
 
 /**
- * This phase lowers {@link GuardNode GuardNodes} into corresponding control-flow structure and
- * {@link DeoptimizeNode DeoptimizeNodes}.
+ * This phase lowers {@link GuardNode floating GuardNodes} and {@link FixedGuardNode}s into
+ * corresponding control-flow structure and {@link DeoptimizeNode DeoptimizeNodes}.
+ * <p/>
+ *
+ * This allows compilation to enter the {@link GuardsStage#FIXED_DEOPTS FIXED_DEOPTS} stage of the
+ * graph where all nodes that may cause deoptimization are fixed.
+ * <p/>
  *
- * This allow to enter the {@link GuardsStage#FIXED_DEOPTS FIXED_DEOPTS} stage of the graph where
- * all node that may cause deoptimization are fixed.
- * <p>
  * It first makes a schedule in order to know where the control flow should be placed. Then, for
  * each block, it applies two passes. The first one tries to replace null-check guards with implicit
  * null checks performed by access to the objects that need to be null checked. The second phase
@@ -113,23 +116,44 @@ private void lowerToIf(GuardNode guard) {
         }
     }
 
+    @Override
+    public boolean shouldApply(StructuredGraph graph) {
+        return graph.hasNode(GuardNode.TYPE) || graph.hasNode(FixedGuardNode.TYPE);
+    }
+
     @Override
     public Optional<NotApplicable> notApplicableTo(GraphState graphState) {
         return NotApplicable.ifAny(
                         NotApplicable.ifApplied(this, StageFlag.GUARD_LOWERING, graphState),
                         NotApplicable.when(!graphState.getGuardsStage().allowsFloatingGuards(), "Floating guards must be allowed"));
     }
 
-    @Override
-    protected void run(StructuredGraph graph, CoreProviders context) {
+    private static void lowerFloatingGuards(StructuredGraph graph) {
         SchedulePhase.runWithoutContextOptimizations(graph, SchedulePhase.SchedulingStrategy.EARLIEST_WITH_GUARD_ORDER);
         ScheduleResult schedule = graph.getLastSchedule();
 
         for (HIRBlock block : schedule.getCFG().getBlocks()) {
             processBlock(block, schedule);
         }
+    }
 
-        assert assertNoGuardsLeft(graph);
+    private static void lowerFixedGuards(StructuredGraph graph) {
+        for (FixedGuardNode fixedGuard : graph.getNodes(FixedGuardNode.TYPE)) {
+            fixedGuard.lowerToIf();
+        }
+    }
+
+    @Override
+    protected void run(StructuredGraph graph, CoreProviders context) {
+        if (graph.hasNode(GuardNode.TYPE)) {
+            lowerFloatingGuards(graph);
+        }
+        if (graph.hasNode(FixedGuardNode.TYPE)) {
+            lowerFixedGuards(graph);
+        }
+
+        assert graph.getNodes(GuardNode.TYPE).isEmpty() : "no floating guards must be left after guard lowering";
+        assert graph.getNodes(FixedGuardNode.TYPE).isEmpty() : "no fixed guards must be left after guard lowering";
     }
 
     @Override
@@ -139,11 +163,6 @@ public void updateGraphState(GraphState graphState) {
         graphState.setGuardsStage(GuardsStage.FIXED_DEOPTS);
     }
 
-    private static boolean assertNoGuardsLeft(StructuredGraph graph) {
-        assert graph.getNodes(GuardNode.TYPE).isEmpty();
-        return true;
-    }
-
     private static void processBlock(HIRBlock block, ScheduleResult schedule) {
         DebugContext debug = block.getBeginNode().getDebug();
         new LowerGuards(debug.isDumpEnabledForMethod() || debug.isLogEnabledForMethod(), schedule).processNodes(block);