RFR(S): 8219650: [Testbug] Fix potential crashes in new test hotspot gtest "test_print_hex_dump"

[Aleksey Shipilev]

On 2/28/19 4:21 PM, Thomas Stüfe wrote:
> Took this over from Christoph since he is busy with other stuff.
> 
> http://cr.openjdk.java.net/~stuefe/webrevs/8219650-shade-print-hex/webrev.00/webrev/

Looks okay.

Do we really need to change stack alloc to malloc now, though? For any char*, either the char*
itself, or (char*) + 1 would be misaligned for any unit size greater than 1.

> Note that the reason is_readable_pointer() did not catch the SIGBUS was that is_readable_pointer()
> does a SafeFetch32 on the address; so, it just requires 32bit alignment. In the crash case, we had
> 32bit aligned pointer and tried to load a 64bit valute (unitsize=8).

Dang. That's a problem for is_readable_pointer, is it not? It should be doing native-width access?

-Aleksey