On 07/12/2014 08:08 PM, Charles Oliver Nutter wrote:
I played with this some years ago. Doesn't it just become recursive,
because it won't inline through the dynamicInvoker?
- Charlie (mobile)
It's clearly recursive.
I don't think it's a good idea to try to fully inline it anyway, it will
generate too much assembly code.
The actual problem is that the JIT generate assembly code and then try
again, and again, and again ...
Rémi
On Jul 12, 2014 9:36 AM, "Remi Forax" <fo...@univ-mlv.fr
<mailto:fo...@univ-mlv.fr>> wrote:
It seems that the JIT is lost with whe there is a loopy callsite
and never stabilize (or the steady state is after the program ends).
import java.lang.invoke.MethodHandle;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.MethodType;
import java.lang.invoke.MutableCallSite;
public class Loop {
static class LoopyCS extends MutableCallSite {
public LoopyCS() {
super(MethodType.methodType(void.class, int.class));
MethodHandle target = dynamicInvoker();
target = MethodHandles.filterArguments(target, 0, FOO);
target = MethodHandles.guardWithTest(ZERO,
target,
MethodHandles.dropArguments(MethodHandles.constant(int.class,
0).asType(MethodType.methodType(void.class)), 0, int.class));
setTarget(target);
}
}
static final MethodHandle FOO, ZERO;
static {
try {
FOO = MethodHandles.lookup().findStatic(Loop.class, "foo",
MethodType.methodType(int.class, int.class));
ZERO = MethodHandles.lookup().findStatic(Loop.class, "zero",
MethodType.methodType(boolean.class, int.class));
} catch (NoSuchMethodException | IllegalAccessException e) {
throw new AssertionError(e);
}
}
private static boolean zero(int i) {
return i != 0;
}
private static int foo(int i) {
COUNTER++;
return i - 1;
}
private static int COUNTER = 0;
public static void main(String[] args) throws Throwable {
for(int i=0; i<100_000; i++) {
new LoopyCS().getTarget().invokeExact(1_000);
}
System.out.println(COUNTER);
}
}
cheers,
Rémi
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