8367244: [lworld] C2 compilation fails with assert "no node with a side effect"

src/hotspot/share/opto/parse.hpp

@@ -572,7 +572,7 @@ class Parse : public GraphKit {
   bool    path_is_suitable_for_uncommon_trap(float prob) const;
 
   void    do_ifnull(BoolTest::mask btest, Node* c);
-  void    do_if(BoolTest::mask btest, Node* c, bool can_trap = true, bool new_path = false, Node** ctrl_taken = nullptr);
+  void    do_if(BoolTest::mask btest, Node* c, bool can_trap = true, bool new_path = false, Node** ctrl_taken = nullptr, Node** stress_count_mem = nullptr);
   void    do_acmp(BoolTest::mask btest, Node* left, Node* right);
   void    acmp_always_null_input(Node* input, const TypeOopPtr* tinput, BoolTest::mask btest, Node* eq_region);
   void    acmp_known_non_inline_type_input(Node* input, const TypeOopPtr* tinput, ProfilePtrKind input_ptr, ciKlass* input_type, BoolTest::mask btest, Node* eq_region);

src/hotspot/share/opto/parse2.cpp

@@ -1819,7 +1819,7 @@ void Parse::do_ifnull(BoolTest::mask btest, Node *c) {
 }
 
 //------------------------------------do_if------------------------------------
-void Parse::do_if(BoolTest::mask btest, Node* c, bool can_trap, bool new_path, Node** ctrl_taken) {
+void Parse::do_if(BoolTest::mask btest, Node* c, bool can_trap, bool new_path, Node** ctrl_taken, Node** stress_count_mem) {
   int target_bci = iter().get_dest();
 
   Block* branch_block = successor_for_bci(target_bci);
@@ -1850,6 +1850,9 @@ void Parse::do_if(BoolTest::mask btest, Node* c, bool can_trap, bool new_path, N
   bool do_stress_trap = StressUnstableIfTraps && ((C->random() % 2) == 0);
   if (do_stress_trap) {
     increment_trap_stress_counter(counter, incr_store);
+    if (stress_count_mem != nullptr) {
+      *stress_count_mem = incr_store;
+    }
   }
 
   // Sanity check the probability value
@@ -2313,22 +2316,26 @@ void Parse::do_acmp(BoolTest::mask btest, Node* left, Node* right) {
   // This is the last check, do_if can emit traps now.
   Node* subst_cmp = _gvn.transform(new CmpINode(ret, intcon(1)));
   Node* ctl = C->top();
+  Node* stress_count_mem = nullptr;
   if (btest == BoolTest::eq) {
     PreserveJVMState pjvms(this);
-    do_if(btest, subst_cmp, can_trap);
+    do_if(btest, subst_cmp, can_trap, false, nullptr, &stress_count_mem);
     if (!stopped()) {
       ctl = control();
     }
   } else {
     assert(btest == BoolTest::ne, "only eq or ne");
     PreserveJVMState pjvms(this);
-    do_if(btest, subst_cmp, can_trap, false, &ctl);
+    do_if(btest, subst_cmp, can_trap, false, &ctl, &stress_count_mem);
     if (!stopped()) {
       eq_region->init_req(2, control());
       eq_io_phi->init_req(2, i_o());
       eq_mem_phi->init_req(2, reset_memory());
     }
   }
+  if (stress_count_mem != nullptr) {
+    set_memory(stress_count_mem, stress_count_mem->adr_type());
+  }
   ne_region->init_req(5, ctl);
   ne_io_phi->init_req(5, i_o());
   ne_mem_phi->init_req(5, reset_memory());

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

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 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
+ * 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
+ * @key randomness
+ * @bug 8367244
+ * @summary Ensure the stress counter is wired correctly with StressUnstableIf for acmp.
+ * @enablePreview
+ * @run main/othervm -Xbatch -XX:-TieredCompilation
+ *                   -XX:CompileCommand=compileonly,compiler/valhalla/inlinetypes/TestAcmpStressUnstableIf.test
+ *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressUnstableIfTraps -XX:StressSeed=3862475856
+ *                   compiler.valhalla.inlinetypes.TestAcmpStressUnstableIf
+ * @run main/othervm -Xbatch -XX:-TieredCompilation
+ *                   -XX:CompileCommand=compileonly,compiler/valhalla/inlinetypes/TestAcmpStressUnstableIf.test
+ *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressUnstableIfTraps
+ *                   compiler.valhalla.inlinetypes.TestAcmpStressUnstableIf
+ * @run main compiler.valhalla.inlinetypes.TestAcmpStressUnstableIf
+ */
+
+package compiler.valhalla.inlinetypes;
+
+public class TestAcmpStressUnstableIf {
+    static value class MyValue {
+        int x;
+
+        public MyValue(int x) {
+            this.x = x;
+        }
+    }
+
+    public static void main(String[] args) {
+        MyValue val = new MyValue(123456);
+        MyValue val_copy = new MyValue(123456);
+        MyValue val_diff = new MyValue(123456 + 1);
+
+        test(val, val_copy, val_diff);
+    }
+
+    public static void test(MyValue val, MyValue val_copy, MyValue val_diff) {
+        for (int i = 0; i < 30_000; ++i) {
+            if (val != val_copy) {
+                return;
+            }
+            if (val == val_diff) {
+                return;
+            }
+        }
+    }
+}

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

@@ -27,13 +27,11 @@
  * @summary Test that deoptimization at unstable ifs in acmp works as expected.
  * @library /test/lib
  * @enablePreview
- * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:-StressUnstableIfTraps compiler.valhalla.inlinetypes.TestAcmpWithUnstableIf
+ * @run main/othervm -XX:+UnlockDiagnosticVMOptions -XX:+StressUnstableIfTraps compiler.valhalla.inlinetypes.TestAcmpWithUnstableIf
  * @run main/othervm -XX:CompileCommand=compileonly,compiler.valhalla.inlinetypes.TestAcmpWithUnstableIf::test* -Xbatch
- *                   -XX:+UnlockDiagnosticVMOptions -XX:-StressUnstableIfTraps compiler.valhalla.inlinetypes.TestAcmpWithUnstableIf
+ *                   -XX:+UnlockDiagnosticVMOptions -XX:+StressUnstableIfTraps compiler.valhalla.inlinetypes.TestAcmpWithUnstableIf
  */
 
-// TODO 8367244: Remove -XX:-StressUnstableIfTraps again.
-
 package compiler.valhalla.inlinetypes;
 
 import jdk.test.lib.Asserts;