Build broken for ARM32 after 8231610: Relocate the CDS archive if it cannot be mapped to the requested address

[christoph.goettschkes at microdoc.com]

Hi,

I am no longer able to build for ARM32 after the commit for 8231610:
Relocate the CDS archive if it cannot be mapped to the requested address
[1]. I am using a linaro toolchain with a GCC version 4.9.4.

arm-linux-gnueabi-g++ (Linaro GCC 4.9-2017.01) 4.9.4
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR 
PURPOSE.

src/hotspot/share/memory/filemap.cpp:1569:21:
error: right shift count >= width of type [-Werror]
   assert((offset >> 32) == 0, "must be 32-bit only");

I guess the same check could be achieved without a right shift operation,
by casting the offset twice and comparing it?
   assert(offset == (size_t)(uint32_t)offset, "must be 32-bit only");

Here is a webrev [2] for that particular fix (there are two instances
where size_t is right shifted by 32). Should I open a new bug for this,
or should this be discussed using the already existing bug 8231610?

-- Christoph

[1] https://bugs.openjdk.java.net/browse/JDK-8231610
[2] https://cr.openjdk.java.net/~cgo/8231610/webrev.00/