8343068: C2: CastX2P Ideal transformation not always applied

Reviewed-by: kvn, thartmann

src/hotspot/share/opto/phaseX.cpp

@@ -1695,6 +1695,14 @@ void PhaseIterGVN::add_users_of_use_to_worklist(Node* n, Node* use, Unique_Node_
       worklist.push(cmp);
     }
   }
+  if (use->Opcode() == Op_AddX) {
+    for (DUIterator_Fast i2max, i2 = use->fast_outs(i2max); i2 < i2max; i2++) {
+      Node* u = use->fast_out(i2);
+      if (u->Opcode() == Op_CastX2P) {
+        worklist.push(u);
+      }
+    }
+  }
 }
 
 /**

test/hotspot/jtreg/compiler/c2/TestCastX2NotProcessedIGVN.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2024, Red Hat, Inc. 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+package compiler.c2;
+
+import compiler.lib.ir_framework.*;
+import jdk.internal.misc.Unsafe;
+
+/*
+ * @test
+ * @bug 8343068
+ * @summary C2: CastX2P Ideal transformation not always applied
+ * @modules java.base/jdk.internal.misc
+ * @library /test/lib /
+ * @run driver compiler.c2.TestCastX2NotProcessedIGVN
+ */
+
+public class TestCastX2NotProcessedIGVN {
+    private static final Unsafe UNSAFE = Unsafe.getUnsafe();
+    static int size = 1024;
+    static long base = UNSAFE.allocateMemory(4 * size);
+
+
+    public static void main(String[] args) {
+        TestFramework.runWithFlags("--add-modules", "java.base", "--add-exports", "java.base/jdk.internal.misc=ALL-UNNAMED");
+    }
+
+    @Test
+    @IR(failOn = IRNode.ADD_L, counts = {IRNode.ADD_P, "1"})
+    public static byte test1(long base) {
+        int offset = 0;
+        do {
+            offset++;
+        } while (offset < 100);
+        long longOffset = ((long) offset) * 2;
+        return UNSAFE.getByte(null, base + longOffset);
+    }
+
+    @Run(test = "test1")
+    public static void test1Runner() {
+        test1(base);
+    }
+
+    @Test
+    @IR(counts = {IRNode.LOAD_VECTOR_I, "> 1"})
+    public static int test2(int stop, int[] array) {
+        int v = 0;
+        stop = Math.min(stop, Integer.MAX_VALUE / 4);
+        for (int i = 0; i < stop; i++) {
+            long offset = ((long)i) * 4;
+            array[i] = UNSAFE.getInt(null, offset + base);
+        }
+        return v;
+    }
+
+    @Run(test = "test2")
+    public static void test2Runner() {
+        test2(size, new int[size]);
+    }
+}

test/hotspot/jtreg/compiler/lib/ir_framework/IRNode.java

@@ -219,6 +219,11 @@ public class IRNode {
         beforeMatchingNameRegex(ADD_L, "AddL");
     }
 
+    public static final String ADD_P = PREFIX + "ADD_P" + POSTFIX;
+    static {
+        beforeMatchingNameRegex(ADD_P, "AddP");
+    }
+
     public static final String ADD_VD = VECTOR_PREFIX + "ADD_VD" + POSTFIX;
     static {
         vectorNode(ADD_VD, "AddVD", TYPE_DOUBLE);