RFR: 8204331: AArch64: fix CAS not embedded in normal graph error.

[Erik Osterlund]

Hi Andrew,

I agree; it would be preferable to fix this in the ad file.

Thanks,
/Erik

> On 6 Jun 2018, at 11:41, Andrew Haley <aph at redhat.com> wrote:
> 
>> On 06/05/2018 04:41 PM, Zhongwei Yao wrote:
>> Hi,
>> 
>> Bug:
>> https://bugs.openjdk.java.net/browse/JDK-8204331
>> 
>> Webrev:
>> http://cr.openjdk.java.net/~zyao/8204331/webrev.00/
>> 
>> This patch fixes an assertion error on aarch64 in several jtreg tests. 
>> 
>> The failure assertion is in needs_acquiring_load_exclusive() in aarch64.ad when checking whether the graph is in "leading_to_normal"  shape. The abnormal shape is generated in  LibraryCallKit::inline_unsafe_load_store(). This patch fixes it by swap the order of "Pin SCMProj node" and "Insert post barrier" in LibraryCallKit::inline_unsafe_load_store().
>> 
> 
> I don't think this is the right way to fix it.  It'd be better to
> fix the code in aarhc64.ad.
> 
> -- 
> Andrew Haley
> Java Platform Lead Engineer
> Red Hat UK Ltd. <https://www.redhat.com>
> EAC8 43EB D3EF DB98 CC77 2FAD A5CD 6035 332F A671