[RFR] Instrumentation for Unsafe volatile put/get

[Man Cao]

In unsafe.cpp:
Calls to __tsan_java_acquire and __tsan_java_release should be swapped.
I.e., Get*Volatile should use __tsan_java_acquire, and Put*Volatile should
use __tsan_java_release.

I think the tests should check that proper use of volatile establishes
happens-before, instead of "no race on volatile access". E.g.:

volatile byte b = 0;
int data = 0;
T1:
data = 42;
b = 1;

T2:
while (b == 0);
int t = data;

In NonRacyUnsafeVolatileLoopTest.java:

private byte b = 0x42;

Should this field be "volatile"?

-Man



On Fri, Sep 20, 2019 at 8:40 AM Arthur Eubanks <aeubanks at google.com> wrote:

> webrev:
>
> http://cr.openjdk.java.net/~aeubanks/tsanvolatileunsafe/webrev.00/index.html
>
> I also added a test that normal volatile accesses (not through unsafe) are
> not considered racy, since we didn't have a test for that before.
>