From zhuyong.me at gmail.com  Mon Sep 26 10:30:30 2016
From: zhuyong.me at gmail.com (Zhu Yong)
Date: Mon, 26 Sep 2016 18:30:30 +0800
Subject: cross compile openjdk8u102-b14, zeroshark, getFunctionAddress()
	return NULL when compile java.lang.String::equals
Message-ID: <CAMPNdT=QC_mEc2bHp2wNkDN3xEEj2jqC0yOtN3Bp+bV8bYjofQ@mail.gmail.com>

Dear All,

I am new to OpenJDK, I was assigned task to do some evaluation on OpenJDK
on ARM, both zero and zeroshark.
My Host is x86_64, boot JDK use 32bit JDK7 from Oracle, LLVM use 3.4.2,
cross compiled.

I have managed to cross compile oepnjdk jdk8u102-b14, zero variant for ARM,
java runs OK, but it's slow.

Ccross compile zeroshark variant for ARM passed with some patches found
online.
In sharkCompiler.cpp, I enabled MCJIT, forced MArch to ARM. When I run
 "java" command on target, I saw assert:

#  Internal Error
(/data/develop/kinetic/uboot-linux/buildroot-2011.05-2013_Q1.1/output/build/openjdk-jdk8u102-b14/hotspot/src/share/vm/shark/sharkCompiler.cpp:339),
pid=26316, tid=0x4d29f470
#  assert(code != NULL) failed: code must be != NULL

To debug the failure, I added some debug message in both OpenJDK and LLVM,
and discovered
1. method java.lang.String::hashCode was compiled successfully from
module _normal_context->module()
2. When compile java.lang.String::equals method, call
of execution_engine()->getFunctionAddress(name); return NULL, this caused
the assert above.
3. From debug message I added in LLVM MCJIT::FindFunctionNamed(),
 java.lang.String::equals function already in the finalized module
(normal). But it's not in RuntimeDyldImpl.GlobalSymbolTable , and that's
why MCJIT::getExistingSymbolAddress() can't find it.
4. Then I printed all symbols in RuntimeDyldImpl::loadObject(),
 java.lang.String::equals was not in the symbol list.

What's the status for zeroshark in jdk8u?  Any specific version of LLVM is
required?  Is it stable?

Refer to the assert, method java.lang.String::equals is compiled into same
module as java.lang.String::hashCode , but not added into
RuntimeDyldImpl.GlobalSymbolTable, what should I do to make
java.lang.String::equals added into symbol table?

Thank you very much!
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From aph at redhat.com  Mon Sep 26 10:48:56 2016
From: aph at redhat.com (Andrew Haley)
Date: Mon, 26 Sep 2016 11:48:56 +0100
Subject: cross compile openjdk8u102-b14, zeroshark, getFunctionAddress()
	return NULL when compile java.lang.String::equals
In-Reply-To: <CAMPNdT=QC_mEc2bHp2wNkDN3xEEj2jqC0yOtN3Bp+bV8bYjofQ@mail.gmail.com>
References: <CAMPNdT=QC_mEc2bHp2wNkDN3xEEj2jqC0yOtN3Bp+bV8bYjofQ@mail.gmail.com>
Message-ID: <edff31bc-8e56-8804-1d7d-fd9165ad7e6c@redhat.com>

On 26/09/16 11:30, Zhu Yong wrote:

> What's the status for zeroshark in jdk8u?  Any specific version of
> LLVM is required?  Is it stable?

It does need a very specific version of LLVM, but I'd have to search.

I don't know that Shark has been tested in some time.  It may not
work.

Andrew.