8388441

src/hotspot/share/opto/callnode.cpp

@@ -1403,7 +1403,7 @@ bool CallStaticJavaNode::remove_unknown_flat_array_load(PhaseIterGVN* igvn, Node
 Node* CallStaticJavaNode::replace_is_substitutable(PhaseIterGVN* igvn) {
   Node* left = in(TypeFunc::Parms);
   Node* right = in(TypeFunc::Parms + 1);
-  if (!InlineTypeNode::can_emit_substitutability_check(left, right)) {
+  if (!InlineTypeNode::can_emit_substitutability_check(igvn, left, right)) {
     return nullptr;
   }
 

src/hotspot/share/opto/inlinetypenode.cpp

@@ -598,14 +598,32 @@ static bool check_cycle(ciInlineKlass* vk) {
   return false;
 }
 
+// Check if 'lhs' and 'rhs' are the same oop, possibly wrapped in an InlineTypeNode.
+static bool same_oop(PhaseGVN* phase, Node* lhs, Node* rhs) {
+  InlineTypeNode* lhs_inline = lhs->isa_InlineType();
+  if (lhs_inline != nullptr && lhs_inline->is_allocated(phase)) {
+    lhs = lhs_inline->get_oop();
+  }
+  InlineTypeNode* rhs_inline = rhs->isa_InlineType();
+  if (rhs_inline != nullptr && rhs_inline->is_allocated(phase)) {
+    rhs = rhs_inline->get_oop();
+  }
+  return lhs->eqv_uncast(rhs);
+}
+
 // Check if a substitutability check between 'lhs' and 'rhs' can be implemented in IR
-bool InlineTypeNode::can_emit_substitutability_check(Node* lhs, Node* rhs) {
+bool InlineTypeNode::can_emit_substitutability_check(PhaseGVN* phase, Node* lhs, Node* rhs) {
+  // We can't create new InlineTypeNodes after macro expansion
+  if (!phase->C->allow_macro_nodes()) {
+    return false;
+  }
+
   if (!lhs->bottom_type()->isa_ptr() ||
       (rhs != nullptr && !rhs->bottom_type()->isa_ptr())) {
     return false;
   }
 
-  if (rhs != nullptr && lhs->eqv_uncast(rhs)) {
+  if (rhs != nullptr && same_oop(phase, lhs, rhs)) {
     return true;
   }
 
@@ -641,7 +659,7 @@ bool InlineTypeNode::can_emit_substitutability_check(Node* lhs, Node* rhs) {
 
     Node* lhs_fv = lhs_inline->field_value(i);
     Node* rhs_fv = rhs_inline != nullptr ? rhs_inline->field_value(i) : nullptr;
-    if (!can_emit_substitutability_check(lhs_fv, rhs_fv)) {
+    if (!can_emit_substitutability_check(phase, lhs_fv, rhs_fv)) {
       return false;
     }
   }
@@ -696,7 +714,7 @@ static Node* emit_substitutability_check_pointer(GraphKit* kit, PhiNode* result,
   }
 
   Node* cmp = nullptr;
-  if (lhs->eqv_uncast(rhs)) {
+  if (same_oop(&gvn, lhs, rhs)) {
     cmp = kit->intcon(0);
   } else if (!lhs_type->is_ptr()->can_be_inline_type() || !rhs_type->is_ptr()->can_be_inline_type()) {
     // If one of the sides is not a value object, can only be substitutable if they are the same

src/hotspot/share/opto/inlinetypenode.hpp

@@ -132,7 +132,7 @@ public:
   void store_flat_array(GraphKit* kit, Node* base, Node* idx);
 
   // Implementation of the substitutability check for acmp
-  static bool can_emit_substitutability_check(Node* lhs, Node* rhs);
+  static bool can_emit_substitutability_check(PhaseGVN* phase, Node* lhs, Node* rhs);
   static Node* emit_substitutability_check(GraphKit* kit, Node* lhs, Node* rhs);
 
   // Allocates the inline type (if not yet allocated)

test/hotspot/jtreg/compiler/valhalla/inlinetypes/TestSubstitutabilityExpansionAfterMacro.java

@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2026, 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
+ * 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.
+ */
+
+/*
+ * @test
+ * @bug 8388441
+ * @summary Test acmp optimization when operands become known after macro expansion
+ * @requires vm.compiler2.enabled
+ * @library /test/lib
+ * @enablePreview
+ * @run main/othervm -XX:-TieredCompilation -Xbatch ${test.main.class}
+ */
+
+import jdk.test.lib.Asserts;
+
+public class TestSubstitutabilityExpansionAfterMacro {
+    record Box(Object value) { }
+    value record MyValue(Object value) { }
+
+    static boolean equals(Object a, Object b) {
+        return a == b;
+    }
+
+    // Below tests trigger InlineTypeNode::can_emit_substitutability_check only
+    // after macro expansion.
+
+    // EA leaves the right operand as Phi(InlineType<MyValue>, LoadN<Object>).
+    // The cast creates a buffered InlineTypeNode whose oop is a cast of that phi.
+    // After InlineTypeNode removal after macro expansion, both operands are equivalent.
+    static boolean test1(boolean b) {
+        Box box = b ? new Box(new MyValue(null)) : new Box(null);
+        if (box.value == null) {
+            box = new Box(new MyValue(null));
+        }
+        return equals((MyValue) box.value, box.value);
+    }
+
+    // InlineTypeNode removal changes Phi(InlineType<Integer>(oop=null), exact Object)
+    // to Phi(null, exact Object) as the right operand. The phi then becomes an exact
+    // nullable Object and can_be_inline_type() changes to false after macro expansion.
+    static boolean test2(Object obj, boolean b) {
+        return equals(obj, b ? (Integer) null : new Object());
+    }
+
+    // Both operands are phis of an InlineTypeNode and its oop. After InlineTypeNode
+    // removal, both phis collapse to the same oop and the operands become equivalent
+    // after macro expansion.
+    static boolean test3(Object obj, boolean b) {
+        Object left = b ? (MyValue) obj : obj;
+        Object right = b ? obj : (MyValue) obj;
+        // Use local acmp for fresh profiling
+        return left == right;
+    }
+
+    public static void main(String[] args) {
+        // Warmup and profile acmp with identity operands
+        for (int i = 0; i < 10_000; i++) {
+            equals(args, args);
+        }
+        Object obj = new Object();
+        MyValue val = new MyValue(obj);
+        for (int i = 0; i < 50_000; i++) {
+            boolean b = (i & 1) == 0;
+            Asserts.assertEQ(test1(b), true);
+            Asserts.assertEQ(test2(b ? null : obj, b), b);
+            Asserts.assertEQ(test3(val, b), true);
+        }
+    }
+}
+