From 97c611d029b614bb462a8f5398ea75b2715c3f07 Mon Sep 17 00:00:00 2001
From: Tobias Holenstein <tholenstein@openjdk.org>
Date: Fri, 20 Jan 2023 14:20:32 +0000
Subject: [PATCH] 8289748: C2 compiled code crashes with SIGFPE with
 -XX:+StressLCM and -XX:+StressGCM

Reviewed-by: thartmann, chagedorn, kvn
---
 src/hotspot/share/opto/loopTransform.cpp      |  7 +-
 .../loopopts/TestRemoveEmptyCountedLoop.java  | 70 +++++++++++++++++++
 2 files changed, 76 insertions(+), 1 deletion(-)
 create mode 100644 test/hotspot/jtreg/compiler/loopopts/TestRemoveEmptyCountedLoop.java

diff --git a/src/hotspot/share/opto/loopTransform.cpp b/src/hotspot/share/opto/loopTransform.cpp
index 5912a4b4408f0..c296db00d0bec 100644
--- a/src/hotspot/share/opto/loopTransform.cpp
+++ b/src/hotspot/share/opto/loopTransform.cpp
@@ -3694,7 +3694,12 @@ bool IdealLoopTree::do_remove_empty_loop(PhaseIdealLoop *phase) {
   // counted loop has limit check predicate.
   Node* phi = cl->phi();
   Node* exact_limit = phase->exact_limit(this);
-  Node* final_iv = new SubINode(exact_limit, cl->stride());
+
+  // We need to pin the exact limit to prevent it from floating above the zero trip guard.
+  Node* cast_ii = ConstraintCastNode::make(cl->in(LoopNode::EntryControl), exact_limit, phase->_igvn.type(exact_limit), ConstraintCastNode::UnconditionalDependency, T_INT);
+  phase->register_new_node(cast_ii, cl->in(LoopNode::EntryControl));
+
+  Node* final_iv = new SubINode(cast_ii, cl->stride());
   phase->register_new_node(final_iv, cl->in(LoopNode::EntryControl));
   phase->_igvn.replace_node(phi, final_iv);
 
diff --git a/test/hotspot/jtreg/compiler/loopopts/TestRemoveEmptyCountedLoop.java b/test/hotspot/jtreg/compiler/loopopts/TestRemoveEmptyCountedLoop.java
new file mode 100644
index 0000000000000..59f1d42b9b977
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/loopopts/TestRemoveEmptyCountedLoop.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2023, 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 8289748
+ * @summary SIGFPE caused by C2 IdealLoopTree::do_remove_empty_loop
+ * @key stress randomness
+ *
+ * @run main/othervm -XX:-TieredCompilation -Xcomp -XX:+UnlockDiagnosticVMOptions -XX:+StressGCM
+ *                   -XX:CompileOnly=compiler.loopopts.TestRemoveEmptyCountedLoop::test*
+ *                   compiler.loopopts.TestRemoveEmptyCountedLoop
+ * @run main/othervm -XX:-TieredCompilation -Xcomp -XX:+UnlockDiagnosticVMOptions -XX:+StressGCM -XX:StressSeed=2160808391
+ *                   -XX:CompileOnly=compiler.loopopts.TestRemoveEmptyCountedLoop::test*
+ *                   compiler.loopopts.TestRemoveEmptyCountedLoop
+ */
+
+package compiler.loopopts;
+
+public class TestRemoveEmptyCountedLoop {
+
+    public static void test1() {
+        int k = 3;
+        for (int i=9; i>0; i--) {
+            for (int j=2; j<i; j++) {
+                k = k;
+                k = (1 % j);
+            }
+        }
+    }
+
+    public static void test2() {
+        int k = 3;
+        for (int i=9; i>0; i--) {
+            int j = 2;
+            do {
+                try {
+                    k = k;
+                    k = (1 % j);
+                } catch (Exception e) {}
+            } while (++j < i);
+        }
+    }
+
+    public static void main(String[] args) {
+        test1();
+        test2();
+        System.out.println("Test passed.");
+    }
+}