Varargs bindings do not work in java 19 on the macbook pro M1 MAX

[Mark Hammons]

Sorry, yes there's an error there. However, this was not the first place I
noticed the error. Rather, I noticed that my binding to sprintf was
returning halfway malformed strings like   `1810529328 hello:
�_�����{���\���^��@xA�!$@�!@����@Q@ 922798592` when the following test code
was run:
```
val format = Ptr.copy("%i hello: %s %i")
val buffer = Ptr.blankArray[Byte](256)

assertEquals(format.copyIntoString(200), "%i hello: %s %i")
Cstd.sprintf(buffer, format, 1, Ptr.copy("hello"), 2)
assertEquals(buffer.copyIntoString(256), "1 hello: hello 2")
```

With the fixed code above, I get the following result from add_var:

-1884714972

~Mark

On Mon, Oct 24, 2022 at 3:23 PM Maurizio Cimadamore <
maurizio.cimadamore at oracle.com> wrote:

> Hi Mark,
> interesting. On M1 we have currently few issues - see also this:
>
> https://bugs.openjdk.org/browse/JDK-8275584
>
> Stack spilling doesn't always occur correctly, however I note that your
> example should not spill on the stack, so it should be immune.
>
> Is your C code correct? I see you do _two_ va_arg per loop iteration,
> which surely would leave you accessing invalid data. E.g. in this case n =
> 2, so the loop would do two iterations, and va_arg will be called _four_
> times? Am I missing something?
>
> I'd rewrite it as:
>
> ```
>     for(int i = 0; i < n; i++) {
>         int i = va_arg(ptr, int);
>         printf("lala %d", i);
>         Sum += i;
>     }
> ```
>
> And test again.
>
> Maurizio
> On 24/10/2022 13:40, Mark Hammons wrote:
>
> Hi all,
>
> I was testing panama on java 19 with my work issued macbook pro, and my
> varargs method bindings were returning invalid data.
>
> I thought that maybe it was a failure in my own code, but I couldn't work
> around it so I created a test instance using manually written code:
>
> test("manual varargs") {
> val linker = Linker.nativeLinker().nn
> val sl = SymbolLookup.loaderLookup().nn
> val mh = linker
> .downcallHandle(
> sl.lookup("add_var").nn.orElseThrow(),
> FunctionDescriptor.of(JAVA_INT, JAVA_INT, JAVA_INT, JAVA_INT)
> )
> .nn;
> val res = MethodHandleFacade.callVariadic(mh, 2, 1, 2).asInstanceOf[Int]
> assertEquals(res, 3)
> }
> #include <stdarg.h>
> #include <stdio.h>
> int add_var(int n, ...) {
> int Sum = 0;
> va_list ptr;
> va_start(ptr, n);
> for(int i = 0; i < n; i++) {
> int i = va_arg(ptr, int);
> printf("lala %d", i);
> Sum += va_arg(ptr, int);
> }
> va_end(ptr);
> return Sum;
> } The output of the test code is consistent with my autogenerated code,
> the Ints are not reaching the add_var function in a proper state, and
> therefore
> add_var is returning something like 840370212 instead of 3.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://mail.openjdk.org/pipermail/panama-dev/attachments/20221024/5fffa6ac/attachment-0001.htm>