[GR-49508] [GR-49654] Backport to 23.0 : Refactor NI Optimization Levels.

PullRequest: graal/15873

Author: elkorchi

compiler/src/org.graalvm.compiler.phases.common/src/org/graalvm/compiler/phases/common/CanonicalizerPhase.java

@@ -25,6 +25,7 @@
 package org.graalvm.compiler.phases.common;
 
 import static org.graalvm.compiler.phases.common.CanonicalizerPhase.CanonicalizerFeature.CFG_SIMPLIFICATION;
+import static org.graalvm.compiler.phases.common.CanonicalizerPhase.CanonicalizerFeature.DEAD_PHI_CYCLE_DETECTION;
 import static org.graalvm.compiler.phases.common.CanonicalizerPhase.CanonicalizerFeature.GVN;
 import static org.graalvm.compiler.phases.common.CanonicalizerPhase.CanonicalizerFeature.READ_CANONICALIZATION;
 
@@ -108,7 +109,13 @@ public enum CanonicalizerFeature {
          * Determines if the canonicalizer is allowed to perform global value numbering. See
          * {@link StructuredGraph#findDuplicate(Node)} for details.
          */
-        GVN;
+        GVN,
+        /**
+         * Determines if the canonicalizer is allowed to perform a global graph analysis on dead
+         * loop phi cycles and delete them.
+         * {@link CanonicalizerPhase#isDeadLoopPhiCycle(PhiNode, NodeFlood)} for details.
+         */
+        DEAD_PHI_CYCLE_DETECTION;
     }
 
     protected static final int MAX_ITERATION_PER_NODE = 10;
@@ -158,6 +165,12 @@ public CanonicalizerPhase copyWithoutGVN() {
         return new CanonicalizerPhase(customSimplification, newFeatures);
     }
 
+    public CanonicalizerPhase copyWithoutDeadPhiCycleDetection() {
+        EnumSet<CanonicalizerFeature> newFeatures = EnumSet.copyOf(features);
+        newFeatures.remove(DEAD_PHI_CYCLE_DETECTION);
+        return new CanonicalizerPhase(customSimplification, newFeatures);
+    }
+
     public CanonicalizerPhase copyWithoutSimplification() {
         EnumSet<CanonicalizerFeature> newFeatures = EnumSet.copyOf(features);
         newFeatures.remove(CFG_SIMPLIFICATION);
@@ -314,7 +327,7 @@ public void usagesDroppedToZero(Node node) {
             for (Node n : tool.workList) {
                 processNode(n, tool);
                 ++sum;
-                if (tool.allUsagesAvailable() && n.isAlive() && n instanceof PhiNode && ((PhiNode) n).isLoopPhi()) {
+                if (features.contains(DEAD_PHI_CYCLE_DETECTION) && tool.allUsagesAvailable() && n.isAlive() && n instanceof PhiNode && ((PhiNode) n).isLoopPhi()) {
                     if (phiPostProcessingWorkList == null) {
                         phiPostProcessingWorkList = EconomicSet.create();
                     }