From 687fab1763eacf53518428621296c1b885e8b393 Mon Sep 17 00:00:00 2001
From: Christian Thalinger <twisti@openjdk.org>
Date: Fri, 25 May 2012 11:39:13 -0700
Subject: [PATCH] 7170145: C1 doesn't respect the JMM with volatile field loads
Reviewed-by: kvn, roland
---
hotspot/src/share/vm/c1/c1_ValueMap.hpp | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/hotspot/src/share/vm/c1/c1_ValueMap.hpp b/hotspot/src/share/vm/c1/c1_ValueMap.hpp
index 4278b11d39a..5b38819da82 100644
--- a/hotspot/src/share/vm/c1/c1_ValueMap.hpp
+++ b/hotspot/src/share/vm/c1/c1_ValueMap.hpp
@@ -141,8 +141,11 @@ class ValueNumberingVisitor: public InstructionVisitor {
// visitor functions
void do_StoreField (StoreField* x) {
- if (x->is_init_point()) {
- // putstatic is an initialization point so treat it as a wide kill
+ if (x->is_init_point() || // putstatic is an initialization point so treat it as a wide kill
+ // This is actually too strict and the JMM doesn't require
+ // this in all cases (e.g. load a; volatile store b; load a)
+ // but possible future optimizations might require this.
+ x->field()->is_volatile()) {
kill_memory();
} else {
kill_field(x->field());
@@ -160,8 +163,8 @@ class ValueNumberingVisitor: public InstructionVisitor {
void do_Local (Local* x) { /* nothing to do */ }
void do_Constant (Constant* x) { /* nothing to do */ }
void do_LoadField (LoadField* x) {
- if (x->is_init_point()) {
- // getstatic is an initialization point so treat it as a wide kill
+ if (x->is_init_point() || // getstatic is an initialization point so treat it as a wide kill
+ x->field()->is_volatile()) { // the JMM requires this
kill_memory();
}
}