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<p>Thanks for confirming. Then the API works as expected. This is
described in the Linker javadoc - e.g. support for variadic calls
require the method handle to be specialized manually (by creating
a function descriptor featuring the desired arity). The ABI needs
to know specific information re. variadic calls, as in some
platforms variadic arguments are dealt with specially.<br>
</p>
<p>Jextract works around this problem by using a method handle which
accepts an Object... and then specializes a new downcall method
handle on each new call. This can probably be optimized by using
invokedynamic + mutable call site, so that an impl can reuse an
existing specialized variadic downcall method handle.</p>
<p>Another option for you (if specialization is not possible) would
be to just support VaList (which is similar to what Swift does
[1]).<br>
</p>
<p>Maurizio<br>
<br>
[1] - <a class="moz-txt-link-freetext" href="https://developer.apple.com/documentation/swift/cvararg">https://developer.apple.com/documentation/swift/cvararg</a><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 24/10/2022 16:24, Mark Hammons
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CA+Qhaypk0tPoJjKbsvAMPbUp3K5T0p2ZMR=Phs3Bh3tLw09b_Q@mail.gmail.com">
<div dir="ltr">
<div>Hi Jorn, Maurizio, <br>
</div>
<div><br>
</div>
<div>When I make the change suggested by Jorn, the bindings work
as expected. <br>
</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Mark<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Oct 24, 2022 at 5:10
PM Maurizio Cimadamore <<a href="mailto:maurizio.cimadamore@oracle.com" moz-do-not-send="true" class="moz-txt-link-freetext">maurizio.cimadamore@oracle.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>Do you get the error even if you add the asVariadic call,
as noted by Jorn?</p>
<p>Maurizio<br>
</p>
<div>On 24/10/2022 15:38, Mark Hammons wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>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: <br>
```</div>
<div>
<div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:Menlo,Monaco,"Courier New",monospace;font-weight:normal;font-size:12px;line-height:18px;white-space:pre-wrap"><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">val</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">format</span><span style="color:rgb(212,212,212)"> = </span><span style="color:rgb(78,201,176)">Ptr</span><span style="color:rgb(212,212,212)">.copy(</span><span style="color:rgb(206,145,120)">"%i hello: %s %i"</span><span style="color:rgb(212,212,212)">)</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">val</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">buffer</span><span style="color:rgb(212,212,212)"> = </span><span style="color:rgb(78,201,176)">Ptr</span><span style="color:rgb(212,212,212)">.blankArray[</span><span style="color:rgb(78,201,176)">Byte</span><span style="color:rgb(212,212,212)">](</span><span style="color:rgb(181,206,168)">256</span><span style="color:rgb(212,212,212)">)</span></div>
<div><span style="color:rgb(212,212,212)"> </span></div><div><span style="color:rgb(212,212,212)"> assertEquals(format.copyIntoString(</span><span style="color:rgb(181,206,168)">200</span><span style="color:rgb(212,212,212)">), </span><span style="color:rgb(206,145,120)">"%i hello: %s %i"</span><span style="color:rgb(212,212,212)">)</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(78,201,176)">Cstd</span><span style="color:rgb(212,212,212)">.sprintf(buffer, format, </span><span style="color:rgb(181,206,168)">1</span><span style="color:rgb(212,212,212)">, </span><span style="color:rgb(78,201,176)">Ptr</span><span style="color:rgb(212,212,212)">.copy(</span><span style="color:rgb(206,145,120)">"hello"</span><span style="color:rgb(212,212,212)">), </span><span style="color:rgb(181,206,168)">2</span><span style="color:rgb(212,212,212)">)</span></div><div><span style="color:rgb(212,212,212)"> assertEquals(buffer.copyIntoString(</span><span style="color:rgb(181,206,168)">256</span><span style="color:rgb(212,212,212)">), </span><span style="color:rgb(206,145,120)">"1 hello: hello 2"</span><span style="color:rgb(212,212,212)">)</span></div><div><span style="color:rgb(212,212,212)">```
</span></div></div>
</div>
<div><br>
</div>
<div>With the fixed code above, I get the following
result from add_var: <br>
</div>
<div><br>
</div>
<div>-1884714972</div>
<div><br>
</div>
<div>~Mark<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Oct 24, 2022
at 3:23 PM Maurizio Cimadamore <<a href="mailto:maurizio.cimadamore@oracle.com" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">maurizio.cimadamore@oracle.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px
0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div>
<p>Hi Mark,<br>
interesting. On M1 we have currently few issues -
see also this:</p>
<p><a href="https://bugs.openjdk.org/browse/JDK-8275584" target="_blank" moz-do-not-send="true" class="moz-txt-link-freetext">https://bugs.openjdk.org/browse/JDK-8275584</a></p>
<p>Stack spilling doesn't always occur correctly,
however I note that your example should not spill
on the stack, so it should be immune.</p>
<p>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?</p>
<p>I'd rewrite it as:</p>
<p>```<br>
for(int i = 0; i < n; i++) { <br>
int i = va_arg(ptr, int);<br>
printf("lala %d", i);<br>
Sum += i;<br>
}<br>
```</p>
<p>And test again.<br>
</p>
<p>Maurizio<br>
</p>
<div>On 24/10/2022 13:40, Mark Hammons wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>Hi all, <br>
</div>
<div><br>
</div>
<div>I was testing panama on java 19 with my
work issued macbook pro, and my varargs method
bindings were returning invalid data.</div>
<div><br>
</div>
<div>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: <br>
</div>
<div><br>
</div>
<div>
<div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:Menlo,Monaco,"Courier New",monospace;font-weight:normal;font-size:12px;line-height:18px;white-space:pre-wrap"><div><span style="color:rgb(212,212,212)"> test(</span><span style="color:rgb(206,145,120)">"manual varargs"</span><span style="color:rgb(212,212,212)">) {</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">val</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">linker</span><span style="color:rgb(212,212,212)"> = </span><span style="color:rgb(78,201,176)">Linker</span><span style="color:rgb(212,212,212)">.nativeLinker().nn</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">val</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">sl</span><span style="color:rgb(212,212,212)"> = </span><span style="color:rgb(78,201,176)">SymbolLookup</span><span style="color:rgb(212,212,212)">.loaderLookup().nn</span></div>
<div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">val</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">mh</span><span style="color:rgb(212,212,212)"> = linker</span></div><div><span style="color:rgb(212,212,212)"> .downcallHandle(</span></div><div><span style="color:rgb(212,212,212)"> sl.lookup(</span><span style="color:rgb(206,145,120)">"add_var"</span><span style="color:rgb(212,212,212)">).nn.orElseThrow(),</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(78,201,176)">FunctionDescriptor</span><span style="color:rgb(212,212,212)">.of(</span><span style="color:rgb(78,201,176)">JAVA_INT</span><span style="color:rgb(212,212,212)">, </span><span style="color:rgb(78,201,176)">JAVA_INT</span><span style="color:rgb(212,212,212)">, </span><span style="color:rgb(78,201,176)">JAVA_INT</span><span style="color:rgb(212,212,212)">, </span><span style="color:rgb(78,201,176)">JAVA_INT</span><span style="color:rgb(212,212,212)">)</span></div><div><span style="color:rgb(212,212,212)"> )</span></div><div><span style="color:rgb(212,212,212)"> .nn;</span></div>
<div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">val</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">res</span><span style="color:rgb(212,212,212)"> = </span><span style="color:rgb(78,201,176)">MethodHandleFacade</span><span style="color:rgb(212,212,212)">.callVariadic(mh, </span><span style="color:rgb(181,206,168)">2</span><span style="color:rgb(212,212,212)">, </span><span style="color:rgb(181,206,168)">1</span><span style="color:rgb(212,212,212)">, </span><span style="color:rgb(181,206,168)">2</span><span style="color:rgb(212,212,212)">).</span><span style="color:rgb(220,220,170)">asInstanceOf</span><span style="color:rgb(212,212,212)">[</span><span style="color:rgb(78,201,176)">Int</span><span style="color:rgb(212,212,212)">]</span></div><div><span style="color:rgb(212,212,212)"> assertEquals(res, </span><span style="color:rgb(181,206,168)">3</span><span style="color:rgb(212,212,212)">)</span></div><div><span style="color:rgb(212,212,212)"> }</span></div>
<div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:Menlo,Monaco,"Courier New",monospace;font-weight:normal;font-size:12px;line-height:18px;white-space:pre-wrap"><div><span style="color:rgb(197,134,192)">#include</span><span style="color:rgb(86,156,214)"> </span><span style="color:rgb(206,145,120)"><stdarg.h></span></div><div><span style="color:rgb(197,134,192)">#include</span><span style="color:rgb(86,156,214)"> </span><span style="color:rgb(206,145,120)"><stdio.h></span></div>
<div><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(220,220,170)">add_var</span><span style="color:rgb(212,212,212)">(</span><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(156,220,254)">n</span><span style="color:rgb(212,212,212)">, ...) {</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)"> Sum = </span><span style="color:rgb(181,206,168)">0</span><span style="color:rgb(212,212,212)">;</span></div>
<div><span style="color:rgb(212,212,212)"> va_list ptr;</span></div>
<div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(220,220,170)">va_start</span><span style="color:rgb(212,212,212)">(ptr, n);</span></div>
<div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(197,134,192)">for</span><span style="color:rgb(212,212,212)">(</span><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)"> i = </span><span style="color:rgb(181,206,168)">0</span><span style="color:rgb(212,212,212)">; i < n; i++) { </span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)"> i = </span><span style="color:rgb(220,220,170)">va_arg</span><span style="color:rgb(212,212,212)">(ptr, </span><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)">);</span></div><div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(220,220,170)">printf</span><span style="color:rgb(212,212,212)">(</span><span style="color:rgb(206,145,120)">"lala </span><span style="color:rgb(156,220,254)">%d</span><span style="color:rgb(206,145,120)">"</span><span style="color:rgb(212,212,212)">, i);</span></div><div><span style="color:rgb(212,212,212)"> Sum += </span><span style="color:rgb(220,220,170)">va_arg</span><span style="color:rgb(212,212,212)">(ptr, </span><span style="color:rgb(86,156,214)">int</span><span style="color:rgb(212,212,212)">);</span></div><div><span style="color:rgb(212,212,212)"> }</span></div></div><div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:Menlo,Monaco,"Courier New",monospace;font-weight:normal;font-size:12px;line-height:18px;white-space:pre-wrap">
<div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(220,220,170)">va_end</span><span style="color:rgb(212,212,212)">(ptr);</span></div>
<div><span style="color:rgb(212,212,212)"> </span><span style="color:rgb(197,134,192)">return</span><span style="color:rgb(212,212,212)"> Sum;</span></div>}
<span style="color:rgb(0,0,0)"><span style="background-color:rgb(255,255,255)">The output of the test code is consistent with my autogenerated code, </span></span></div><div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:Menlo,Monaco,"Courier New",monospace;font-weight:normal;font-size:12px;line-height:18px;white-space:pre-wrap"><span style="color:rgb(0,0,0)"><span style="background-color:rgb(255,255,255)">the Ints are not reaching the add_var function in a proper state, and therefore </span></span></div><div style="color:rgb(212,212,212);background-color:rgb(30,30,30);font-family:Menlo,Monaco,"Courier New",monospace;font-weight:normal;font-size:12px;line-height:18px;white-space:pre-wrap"><span style="color:rgb(0,0,0)"><span style="background-color:rgb(255,255,255)">add_var is returning something like 840370212 instead of 3.
</span></span></div></div>
</div>
</div>
</blockquote>
</div>
</blockquote>
</div>
</blockquote>
</div>
</blockquote>
</div>
</blockquote>
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