RFR: JDK-8160353: narrowing conversion error is occurred with GCC 6

[Kim Barrett]

> On Jun 27, 2016, at 11:36 PM, Yasumasa Suenaga <yasuenag at gmail.com> wrote:
> 
> Hi Kim,
> 
>> I would prefer that compiler configuration issue got fixed and these kinds of issues be deferred to a future modernization project.
> 
> IMHO, src/os/linux/vm/os_linux.cpp should be fixed at least because elf_class
> and endianess is defined as unsigned char.

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src/os/linux/vm/os_linux.cpp
Looks good.

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src/share/vm/classfile/altHashing.cpp
Much as I dislike casts, this change is culturally compatible with the
surrounding code.  Cleaning that up is a task for another time.

Looks good.

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src/share/vm/opto/type.cpp

There seems to be inconsistency about whether these register
categories are signed or unsigned. The Node class defines "uint
ideal_reg()" and NotAMachineReg is a special value that must be > max.
machine register. The Type class has "int ideal_reg()" which deals in
the same values.

So the proposed casts seem to me to be just papering over a deeper
problem. I suggest separating this into a different CR for later
cleanup, since it's not an immediate problem once the build problem is
fixed.

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> 
> In other point, I confirmed that we can avoid -std=gnu++98 as below:

Replied in another thread.