<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
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<div class="moz-cite-prefix">"--llvm.C++Interop" is an option for
the GraalVM LLVM Runtime, not for compiler.<br>
<br>
You need to pass it to the GraalVM launcher (e.g. lli):<br>
lli --llvm.C++Interop <bitcode file><br>
<br>
Or if you're embedding it in a Java application, you can pass the
option to the ContextBuilder:<br>
<pre><code class="language-java hljs"> Context polyglot = Context.newBuilder()
.allowExperimentalOptions(true)
.option("llvm.C++Interop", "true")
.allowAllAccess(<span class="hljs-keyword">true</span>).build();
</code></pre>
</div>
<div class="moz-cite-prefix">- Roland<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">On 1/29/21 7:29 PM, Darrell Schiebel
wrote:<br>
</div>
<blockquote type="cite" cite="mid:CAPgAq0mywwgohy7+p6=QfvHE4Lanm6DvR9ca5rM15XUL_uiGSg@mail.gmail.com">
<div dir="ltr">
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">Thanks
very much for your reply. It was very useful information, but
I haven't been able to get the "<span style="font-family:Arial,Helvetica,sans-serif">--llvm.C++Interop"
flag to be accepted:</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif"><br>
</span></div>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">bash$
type clang++</span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">clang++
is hashed
(/Library/Java/JavaVirtualMachines/graalvm-ee-java8-21.0.0/Contents/Home/jre/languages/llvm/native/bin/clang++)</span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">bash$
clang++ -g --llvm.C++Interop -std=c++11 -shared -o
methodsTest.so methodsTest.cpp -lgraalvm-llvm</span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">clang-10:
</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(202,51,35)"><b>error:
</b></span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">unsupported
option '--llvm.C++Interop'</span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">clang-10:
</span><span class="gmail-s2" style="font-variant-ligatures:no-common-ligatures;color:rgb(202,51,35)"><b>error:
</b></span><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">unsupported
option '--llvm.C++Interop'</span></p>
</div>
</blockquote>
<blockquote style="margin:0 0 0 40px;border:none;padding:0px">
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span class="gmail-s1" style="font-variant-ligatures:no-common-ligatures">bash$<span class="gmail-Apple-converted-space"> </span></span></p>
</div>
</blockquote>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif"><br>
</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif">So I'm not
sure if this is a new flag that has not made it into
production or if it is an old flag that has been retired.</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif"><br>
</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif">I appreciate
the work that's gone into GraalVM. It will be great if it
provides a way to integrate legacy systems into a modern
ecosystem.</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif"><br>
</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif">Darrell</span></div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><span style="font-family:Arial,Helvetica,sans-serif"><br>
</span></div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Tue, Jan 26, 2021 at 12:50
PM Roland Schatz <<a href="mailto:roland.schatz@oracle.com" moz-do-not-send="true">roland.schatz@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>
<div>Hi,<br>
<br>
The interop support for C++ is currently work in progress,
some things work already, others not yet.<br>
Some of the C++ interop features are behind a flag, try
passing "--llvm.C++Interop".<br>
</div>
<div><br>
</div>
<div>Calling constructors and non-virtual methods should
work already.<br>
</div>
<div>There is a WIP PR for virtual method calls: <a href="https://urldefense.com/v3/__https://github.com/oracle/graal/pull/2932__;!!GqivPVa7Brio!IwKBSALxE-CiB-oAQ46lEv4ZRCdDpz5VCpAQi9MxhHvSiPMwOx9W02hUi2cQ_AQuCwg$" target="_blank" moz-do-not-send="true">https://github.com/oracle/graal/pull/2932</a></div>
<div><br>
</div>
<div>C++ interop is a very recent feature and doesn't have
many users yet, so there might be bugs.<br>
</div>
<div><br>
</div>
<div>Some more comments inline below...<br>
</div>
<div><br>
</div>
<div>On 1/25/21 10:48 PM, Darrell Schiebel wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">Hello,</div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small"><br>
</div>
<div class="gmail_default" style="font-family:verdana,sans-serif;font-size:small">I'm
trying to understand the capabilities and limitations
of using C++ libraries from Java. One of the more
complete examples I could find was the:</div>
<div class="gmail_default">
<ul>
<li>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">CxxMethodsTest.java/</span><span style="font-variant-ligatures:no-common-ligatures">methodsTest.cpp</span></p>
</li>
</ul>
<div><font face="verdana, sans-serif">test from the
GraalVM distribution. I removed the unit test
framework, but I find that there are some
operations which fail (in Java):</font></div>
<div>
<ol>
<li><font face="verdana, sans-serif">retrieving a
class: </font>testLibrary.getMember("Point")</li>
</ol>
</div>
</div>
</div>
</blockquote>
<p>That should already work. You should be able to use to
create instances of "Point" (with
`point.newInstance(...)`).<br>
It might be that this needs the "--llvm.C++Interop" flag
though.<br>
<br>
</p>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<ol>
<li><font face="verdana, sans-serif">retrieving a
class method: </font>squaredEuclideanDistance
=
testLibrary.getMember("squaredEuclideanDistance")</li>
</ol>
</div>
</div>
</div>
</blockquote>
That doesn't work since "squaredEuclideanDistance" is not a
global function. If you have an instance of "Point", you
should be able to
`point.getMember("squaredEuclideanDistance")` and execute
the result, or just use
`point.invokeMember("squaredEuclideanDistance", ...)` to
directly invoke methods.<br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<ol>
<li><font face="verdana, sans-serif">invoking a
class member: </font>testLibrary.invokeMember("setY",
point2, 8)</li>
</ol>
</div>
</div>
</div>
</blockquote>
Same thing. This needs to be `point2.invokeMember("setY",
8)`.<br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<div><font face="verdana, sans-serif">I am using
GraalVM 21.0.0, and I compiled the C++ like:</font></div>
<div>
<ul>
<li>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">clang++ -std=c++11
-shared -o methodsTest.so methodsTest.cpp
-lgraalvm-llvm</span></p>
</li>
</ul>
<div><font face="verdana, sans-serif">I suppose
maybe the testing framework may compile the
C++ source code differently. Any idea where
I've gone astray?</font></div>
</div>
</div>
</div>
</div>
</blockquote>
<p><font face="verdana, sans-serif">Is that "clang++" from
the toolchain we ship with GraalVM? If yes, then that's
the correct way to build.<br>
<br>
If no: If you want to use interop (both C++ or C), you
need to compile with debug info enabled. Also note that
we currently only support libc++ (the one from the LLVM
project), not libstdc++ (the one from GCC, which is the
default on most Linux systems).</font></p>
<p><font face="verdana, sans-serif"><font face="verdana,
sans-serif">You can get the path to our toolchain
using "lli --print-toolchain-path" (you might have to
install it using "gu install llvm-toolchain", it's an
optional component since you don't need it at
runtime). </font>The "clang++" from there
automatically sets the correct flags. You can use "-v"
to see what exactly it does.</font><font face="verdana,
sans-serif"><br>
</font></p>
<font face="verdana, sans-serif"><br>
</font><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<div>
<div><font face="verdana, sans-serif">I think they
may compile without name mangling or perhaps
they compile the cpp file on the fly... I
don't know exactly what happens behind the
scenes with:</font></div>
<div>
<ul>
<li>
<p style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:11px;line-height:normal;font-family:Menlo;color:rgb(0,0,0)"><span style="font-variant-ligatures:no-common-ligatures">testLibrary =
loadTestBitcodeValue("methodsTest.cpp")</span></p>
</li>
</ul>
</div>
</div>
</div>
</div>
</div>
</blockquote>
That's just some path manipulation to locate .so file for
that test, which is somewhere under mxbuild in a directory
called "methodsTest.cpp.dir". It doesn't do any compilation,
that is done using mx and make.<br>
<br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<div>
<div>
<div><font face="verdana, sans-serif">My
modified methodsTest.cpp file is down below.</font></div>
<div><font face="verdana, sans-serif"><br>
</font></div>
<div><span style="font-family:verdana,sans-serif">It
seems like these are the key points:</span><br>
</div>
</div>
<div>
<ul>
<li><font face="verdana, sans-serif">pointers
should be used to pass/return objects (no
mapping from List<T> to
std::list<T> for example)</font></li>
</ul>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<font face="verdana, sans-serif">Correct, currently we don't
support by-value arguments in interop (except primitives
of course). Everything must be pointers. Not sure about
C++ references, they should work in principle, since in
bitcode they are also just pointers. But I've never tried
to be honest.<br>
</font><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<div>
<div>
<ul>
<li><font face="verdana, sans-serif">mangled
names do not work (unless the mangled name
is used for lookup, of course)</font></li>
</ul>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<font face="verdana, sans-serif">With the
"--llvm.C++Interop" flag that should work. We read the
unmangled names from the debug info.<br>
This probably only works if there is no name conflict with
the unmangled name, i.e. no overloading.<br>
</font><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<div>
<div>
<ul>
<li><font face="verdana, sans-serif">class
based inherited methods work (using an
object pointer)</font></li>
<li><font face="verdana, sans-serif">looking
up methods and supplying the object and
args does not work (e.g.
squareEuclideanDistance above)</font></li>
<li><font face="verdana, sans-serif">retrieving
object constructor as a function (e.g.
getMember("Point") above)</font></li>
</ul>
<div><font face="verdana, sans-serif">Does this
seem right? I've looked at the examples I
could find on the GraalVM.org website but
are there any bigger examples of Java/C++
integration via GraalVM?</font></div>
</div>
</div>
</div>
</div>
</div>
</blockquote>
<font face="verdana, sans-serif">Since this is a work in
progress feature, we don't have any published examples for
C++ yet.<br>
<br>
Most of our users are only using C-based interfaces, even
if the actual implementation behind the interface is in
C++. That is of course a workaround you can use right now,
but not a nice one.<br>
We'll probably publish more examples once we reach a more
complete state of our C++ interop implementation.<br>
<br>
<br>
As I wrote in the beginning, all of this is pretty new, so
not everything might work out of the box. You're welcome
to play around with it, and if you get stuck, feel free to
ask questions or report issues!<br>
<br>
<br>
- Roland<br>
</font><br>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default">
<div>
<div>
<div>
<div><font face="verdana, sans-serif"><br>
</font></div>
<div><font face="verdana, sans-serif">thanks for
any advice,</font></div>
<div><font face="verdana, sans-serif">Darrell</font></div>
<div><font face="verdana, sans-serif"><br>
</font></div>
<div><font face="verdana, sans-serif">/*<br>
* Copyright (c) 2020, Oracle and/or its
affiliates.<br>
*<br>
* All rights reserved.<br>
*<br>
* Redistribution and use in source and
binary forms, with or without modification,
are<br>
* permitted provided that the following
conditions are met:<br>
*<br>
* 1. Redistributions of source code must
retain the above copyright notice, this list
of<br>
* conditions and the following disclaimer.<br>
*<br>
* 2. Redistributions in binary form must
reproduce the above copyright notice, this
list of<br>
* conditions and the following disclaimer
in the documentation and/or other materials
provided<br>
* with the distribution.<br>
*<br>
* 3. Neither the name of the copyright
holder nor the names of its contributors may
be used to<br>
* endorse or promote products derived from
this software without specific prior written<br>
* permission.<br>
*<br>
* THIS SOFTWARE IS PROVIDED BY THE
COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS<br>
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF<br>
* MERCHANTABILITY AND FITNESS FOR A
PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
EVENT SHALL THE<br>
* COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL,<br>
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
OF SUBSTITUTE<br>
* GOODS OR SERVICES; LOSS OF USE, DATA, OR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED<br>
* AND ON ANY THEORY OF LIABILITY, WHETHER
IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING<br>
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY
WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
ADVISED<br>
* OF THE POSSIBILITY OF SUCH DAMAGE.<br>
*/<br>
#include <graalvm/llvm/polyglot.h><br>
#include <stdlib.h><br>
#include <math.h><br>
<br>
#define EXTERN extern "C"<br>
<br>
class Point {<br>
protected:<br>
int x;<br>
int y;<br>
<br>
public:<br>
Point();<br>
int getX();<br>
int getY();<br>
void setX(int val);<br>
void setY(int val);<br>
double squaredEuclideanDistance(Point
*other);<br>
};<br>
<br>
POLYGLOT_DECLARE_TYPE(Point)<br>
<br>
class XtendPoint : public Point {<br>
private:<br>
int z;<br>
<br>
public:<br>
XtendPoint();<br>
int getZ();<br>
void setZ(int val);<br>
int getZ(int constant);<br>
int getX();<br>
};<br>
<br>
POLYGLOT_DECLARE_TYPE(XtendPoint)<br>
<br>
//class methods<br>
<br>
Point::Point() {<br>
x = 0;<br>
y = 0;<br>
}<br>
<br>
int Point::getX() {<br>
return x;<br>
}<br>
<br>
int Point::getY() {<br>
return y;<br>
}<br>
<br>
void Point::setX(int val) {<br>
x = val;<br>
}<br>
<br>
void Point::setY(int val) {<br>
y = val;<br>
}<br>
<br>
double Point::squaredEuclideanDistance(Point
*other) {<br>
double dX = (double) (x - other->x);<br>
double dY = (double) (y - other->y);<br>
return dX * dX + dY * dY;<br>
}<br>
<br>
XtendPoint::XtendPoint() {<br>
z = 0;<br>
}<br>
<br>
int XtendPoint::getZ() {<br>
return z;<br>
}<br>
<br>
void XtendPoint::setZ(int dZ) {<br>
z = dZ;<br>
}<br>
<br>
int XtendPoint::getZ(int constantOffset) {<br>
return z + constantOffset;<br>
}<br>
<br>
int XtendPoint::getX() {<br>
return x * 2;<br>
}<br>
<br>
//functions<br>
EXTERN void *allocNativePoint() {<br>
Point *ret = (Point *)
malloc(sizeof(*ret));<br>
return polyglot_from_Point(ret);<br>
}<br>
<br>
EXTERN void *allocNativeXtendPoint() {<br>
XtendPoint *ret = (XtendPoint *)
malloc(sizeof(*ret));<br>
return polyglot_from_XtendPoint(ret);<br>
}<br>
<br>
EXTERN void swap(Point *p, Point *q) {<br>
Point tmp = *q;<br>
*q = *p;<br>
*p = tmp;<br>
}<br>
<br>
EXTERN void freeNativePoint(Point *p) {<br>
free(p);<br>
}<br>
<br>
EXTERN void freeNativeXtendPoint(XtendPoint
*p) {<br>
free(p);<br>
}<br>
</font></div>
<div><font face="verdana, sans-serif"><br>
</font></div>
</div>
</div>
</div>
</div>
</div>
<br>
<fieldset></fieldset>
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