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/**
* @test
* @bug 6880034
* @summary SIGBUS during deoptimisation at a safepoint on 64bit-SPARC
*
* @run main/othervm -Xcomp -Xbatch
* -XX:+PrintCompilation
* -XX:CompileCommand=compileonly,compiler.c2.Test6880034::deopt_compiledframe_at_safepoint
* compiler.c2.Test6880034
*/
package compiler.c2;
// This test provokes a deoptimisation at a safepoint.
//
// It achieves this by compiling the method 'deopt_compiledframe_at_safepoint'
// before its first usage at a point in time when a call to the virtual method
// A::doSomething() from within 'deopt_compiledframe_at_safepoint' can be
// optimised to a static call because class A has no descendants.
//
// Later, when deopt_compiledframe_at_safepoint() is running, class B which
// extends A and overrides the virtual method "doSomething()", is loaded
// asynchronously in another thread. This makes the compiled code of
// 'deopt_compiledframe_at_safepoint' invalid and triggers a deoptimisation of
// the frame where 'deopt_compiledframe_at_safepoint' is running in a
// loop.
//
// The deoptimisation leads to a SIGBUS on 64-bit server VMs on SPARC and to
// an incorrect result on 32-bit server VMs on SPARC due to a regression
// introduced by the change: "6420645: Create a vm that uses compressed oops
// for up to 32gb heapsizes"
// (http://hg.openjdk.java.net/jdk7/jdk7/hotspot/rev/ba764ed4b6f2). Further
// investigation showed that change 6420645 is not really the root cause of
// this error but only reveals a problem with the float register encodings in
// sparc.ad which was hidden until now.
//
// Notice that for this test to fail in jtreg it is crucial that
// deopt_compiledframe_at_safepoint() runs in the main thread. Otherwise a
// crash in deopt_compiledframe_at_safepoint() will not be detected as a test
// failure by jtreg.
//
// Author: Volker H. Simonis
public class Test6880034 {
static class A {
public int doSomething() {
return 0;
}
}
static class B extends A {
public B() {}
// override 'A::doSomething()'
public int doSomething() {
return 1;
}
}
static class G {
public static volatile A a = new A();
// Change 'a' to point to a 'B' object
public static void setAtoB() {
try {
a = (A) ClassLoader.
getSystemClassLoader().
loadClass("B").
getConstructor(new Class[] {}).
newInstance(new Object[] {});
}
catch (Exception e) {
System.out.println(e);
}
}
}
public static volatile boolean is_in_loop = false;
public static volatile boolean stop_while_loop = false;
public static double deopt_compiledframe_at_safepoint() {
// This will be an optimised static call to A::doSomething() until we load "B"
int i = G.a.doSomething();
// Need more than 16 'double' locals in this frame
double local1 = 1;
double local2 = 2;
double local3 = 3;
double local4 = 4;
double local5 = 5;
double local6 = 6;
double local7 = 7;
double local8 = 8;
long k = 0;
// Once we load "B", this method will be made 'not entrant' and deoptimised
// at the safepoint which is at the end of this loop.
while (!stop_while_loop) {
if (k == 1) local1 += i;
if (k == 2) local2 += i;
if (k == 3) local3 += i;
if (k == 4) local4 += i;
if (k == 5) local5 += i;
if (k == 6) local6 += i;
if (k == 7) local7 += i;
if (k == 8) local8 += i;
// Tell the world that we're now running wild in the loop
if (k++ == 20000) is_in_loop = true;
}
return
local1 + local2 + local3 + local4 +
local5 + local6 + local7 + local8 + i;
}
public static void main(String[] args) {
// Just to resolve G before we compile deopt_compiledframe_at_safepoint()
G g = new G();
// Asynchronous thread which will eventually invalidate the code for
// deopt_compiledframe_at_safepoint() and therefore triggering a
// deoptimisation of that method.
new Thread() {
public void run() {
while (!is_in_loop) {
// Wait until the loop is running
}
// Load class 'B' asynchronously..
G.setAtoB();
// ..and stop the loop
stop_while_loop = true;
}
}.start();
// Run the loop in deopt_compiledframe_at_safepoint()
double retVal = deopt_compiledframe_at_safepoint();
System.out.println(retVal == 36 ? "OK" : "ERROR : " + retVal);
if (retVal != 36) throw new RuntimeException();
}
}