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<p>Hi Mark,<br>
interesting. On M1 we have currently few issues - see also this:</p>
<p><a class="moz-txt-link-freetext" href="https://bugs.openjdk.org/browse/JDK-8275584">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 class="moz-cite-prefix">On 24/10/2022 13:40, Mark Hammons
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CA+QhayqHiyBT4Tru8huE4xgeeuv9kBVmGhkSFph-9d4EP7ye0A@mail.gmail.com">
<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>
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