From 3492bf51e76e5226fd44e52aff053f2ccdea4ecb Mon Sep 17 00:00:00 2001
From: Marc Chevalier <marc.chevalier@oracle.com>
Date: Thu, 30 Jul 2026 11:29:19 +0200
Subject: [PATCH] Add tests, fix comment

---
 .../cpu/aarch64/frame_aarch64.inline.hpp      |  6 +-
 src/hotspot/cpu/x86/frame_x86.inline.hpp      |  7 ++-
 src/hotspot/share/code/nmethod.hpp            |  2 +-
 .../exceptions/TestStackWalkPerf.java         | 57 +++++++++++++++++++
 4 files changed, 66 insertions(+), 6 deletions(-)
 create mode 100644 test/hotspot/jtreg/compiler/exceptions/TestStackWalkPerf.java

diff --git a/src/hotspot/cpu/aarch64/frame_aarch64.inline.hpp b/src/hotspot/cpu/aarch64/frame_aarch64.inline.hpp
index 3785c543951..e062fabfb7b 100644
--- a/src/hotspot/cpu/aarch64/frame_aarch64.inline.hpp
+++ b/src/hotspot/cpu/aarch64/frame_aarch64.inline.hpp
@@ -406,8 +406,10 @@ inline int frame::sender_sp_ret_address_offset() {
   return frame::sender_sp_offset - frame::return_addr_offset;
 }
 
-//------------------------------------------------------------------------------
-// frame::sender
+// This method can be on a hot path. Since Valhalla made it a bit bigger, compilers are
+// not as eager to inline it, but in some cases, it makes a significant difference.
+// Let's encourage the compiler to inline sender all the way to frame::repair_sender_sp.
+// through frame::sender_for_compiled_frame.
 ALWAYSINLINE frame frame::sender(RegisterMap* map) const {
   frame result = sender_raw(map);
 
diff --git a/src/hotspot/cpu/x86/frame_x86.inline.hpp b/src/hotspot/cpu/x86/frame_x86.inline.hpp
index 2dbcb647ea9..f6596236532 100644
--- a/src/hotspot/cpu/x86/frame_x86.inline.hpp
+++ b/src/hotspot/cpu/x86/frame_x86.inline.hpp
@@ -390,9 +390,10 @@ inline int frame::sender_sp_ret_address_offset() {
   return frame::sender_sp_offset - frame::return_addr_offset;
 }
 
-//------------------------------------------------------------------------------
-// frame::sender
-
+// This method can be on a hot path. Since Valhalla made it a bit bigger, compilers are
+// not as eager to inline it, but in some cases, it makes a significant difference.
+// Let's encourage the compiler to inline sender all the way to frame::repair_sender_sp.
+// through frame::sender_for_compiled_frame.
 ALWAYSINLINE frame frame::sender(RegisterMap* map) const {
   frame result = sender_raw(map);
 
diff --git a/src/hotspot/share/code/nmethod.hpp b/src/hotspot/share/code/nmethod.hpp
index 959e6baac3a..ce8fc4a2747 100644
--- a/src/hotspot/share/code/nmethod.hpp
+++ b/src/hotspot/share/code/nmethod.hpp
@@ -286,7 +286,7 @@ public:
     // Used by shared scope closure (scopedMemoryAccess.cpp)
     bool has_scoped_access() const { return (_bits & SCOPED_ACCESS) != 0; }
 
-    // Used by shared scope closure (scopedMemoryAccess.cpp)
+    // Stack has been extended and needs reair. See comment in MacroAssembler::remove_frame
     bool needs_stack_repair() const { return (_bits & NEEDS_STACK_REPAIR) != 0; }
   };
 
diff --git a/test/hotspot/jtreg/compiler/exceptions/TestStackWalkPerf.java b/test/hotspot/jtreg/compiler/exceptions/TestStackWalkPerf.java
new file mode 100644
index 00000000000..24332faf0b9
--- /dev/null
+++ b/test/hotspot/jtreg/compiler/exceptions/TestStackWalkPerf.java
@@ -0,0 +1,57 @@
+/*
+ * 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 8389130
+ * @summary With Valhalla, frame::sender became a bit too big and is not as spontaneously inlined as before.
+ *          This causes some measurable performance regressions in cases where walking the stack is frequent.
+ * @run main/othervm -Xbatch
+ *                   -XX:-TieredCompilation
+ *                   -XX:CompileCommand=dontinline,${test.main.class}::fillInStackTrace
+ *                   ${test.main.class}
+ * @run main ${test.main.class}
+ */
+
+package compiler.exceptions;
+
+public class TestStackWalkPerf extends Throwable {
+    private static final TestStackWalkPerf PROBE = new TestStackWalkPerf();
+
+    private static void fillInStackTrace(int depth, int fills) {
+        if (depth == 0) {
+            for (int i = 0; i < fills; i++) {
+                PROBE.fillInStackTrace();
+            }
+            return;
+        }
+        fillInStackTrace(depth - 1, fills);
+    }
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 10_000; i++) {
+            fillInStackTrace(512, 1);
+        }
+        fillInStackTrace(512, 1_000_000);
+    }
+}