From beebce044db97e50a7aea3f83d70e134b2128d0a Mon Sep 17 00:00:00 2001
From: Martin Doerr <mdoerr@openjdk.org>
Date: Thu, 2 May 2024 10:21:21 +0000
Subject: [PATCH] 8331421: ubsan: vmreg.cpp checking error member call on
 misaligned address

Reviewed-by: mbaesken, lucy
---
 src/hotspot/share/code/vmreg.cpp | 2 +-
 src/hotspot/share/code/vmreg.hpp | 5 +++--
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/src/hotspot/share/code/vmreg.cpp b/src/hotspot/share/code/vmreg.cpp
index 37c3137a102..ba30c114c6c 100644
--- a/src/hotspot/share/code/vmreg.cpp
+++ b/src/hotspot/share/code/vmreg.cpp
@@ -30,7 +30,7 @@
 // used by SA and jvmti, but it's a leaky abstraction: SA and jvmti
 // "know" that stack0 is an integer masquerading as a pointer. For the
 // sake of those clients, we preserve this interface.
-VMReg VMRegImpl::stack0 = (VMReg)(intptr_t)VMRegImpl::stack_0()->value();
+VMReg VMRegImpl::stack0 = (VMReg)(intptr_t)FIRST_STACK;
 
 // VMRegs are 4 bytes wide on all platforms
 const int VMRegImpl::stack_slot_size = 4;
diff --git a/src/hotspot/share/code/vmreg.hpp b/src/hotspot/share/code/vmreg.hpp
index 78f52b8d57a..41e40e9a017 100644
--- a/src/hotspot/share/code/vmreg.hpp
+++ b/src/hotspot/share/code/vmreg.hpp
@@ -54,7 +54,8 @@ friend class OptoReg;
 // friend class Location;
 private:
   enum {
-    BAD_REG = -1
+    BAD_REG = -1,
+    FIRST_STACK = (ConcreteRegisterImpl::number_of_registers + 7) & ~7
   };
 
   // Despite being private, this field is exported to the
@@ -71,7 +72,7 @@ private:
 public:
 
   static constexpr VMReg stack_0() {
-    return first() + ((ConcreteRegisterImpl::number_of_registers + 7) & ~7);
+    return first() + FIRST_STACK;
   }
 
   static VMReg as_VMReg(int val, bool bad_ok = false) {