RFR(M): 8207343: Automate vtable/itable stub size calculation

[Boris Ulasevich]

Hi Lutz,

   I have run jtreg with your change and do not see new fails (test that 
fails on aarch64 is excluded for 32 bit platforms).

   I am OK with your change (I'm not a reviewer). But description and 
variable name in VtableStub::pd_code_alignment function looks strange 
for me. Raspberry Pi2 ARM1176JZF-S processor has a cache line length of 
32 bytes, and, as I know, icache line size is not a constant for ARM32 
architecture.

regards,
Boris

On 02.08.2018 15:02, Schmidt, Lutz wrote:
> Hi Zhongwei,
> 
> thank you for testing aarch64. Given my lack of expertise, I am surprised there are only those two issues.
> Ad 1.: fixed. The declaration just a few lines above was forgotten to adapt.
> Ad 2.: adapted. I pushed the estimate to 152 bytes. I expected this value would require some adjustment.
> 
> Please find a new webrev with the changes at http://cr.openjdk.java.net/~lucy/webrevs/8207343.01
> 
> Best Regards,
> Lutz
> 
> On 02.08.18, 04:45, "Zhongwei Yao" <Zhongwei.Yao at arm.com> wrote:
> 
>      Hi, Lutz,
>      
>      I have tested it on aarch64 by running jtreg tests. And find two tiny issues in vtableStubs_aarch64.cpp's VtableStubs::create_itable_stub function:
>      1. typecheckSize on line 212 is not defined.
>      2. estimate on line 211 is not large enough, I get 148 in gc/g1/TestFromCardCacheIndex.java case. Here is the assertion failure from that case:
>          assert(slop_delta >= 0) failed: itable #3: Code size estimate (140) for lookup_interface_method too small, required: 148
>      
>      However, I don't have tested the modification in vtableStubs_arm.cpp due to I don't have an arm32 environment at hand.
>      
>      --
>      Best regards,
>      Zhongwei
>      
>      ________________________________________
>      From: hotspot-compiler-dev <hotspot-compiler-dev-bounces at openjdk.java.net> on behalf of Schmidt, Lutz <lutz.schmidt at sap.com>
>      Sent: Monday, July 30, 2018 3:57:05 PM
>      To: hotspot-compiler-dev at openjdk.java.net
>      Subject: RFR(M): 8207343: Automate vtable/itable stub size calculation
>      
>      Dear all,
>      
>      may I please request reviews for this change:
>      
>      Bug:    https://bugs.openjdk.java.net/browse/JDK-8207343
>      Webrev: http://cr.openjdk.java.net/~lucy/webrevs/8207343.00/
>      
>      With this change, I try to get rid of the a-priory size guessing for vtable and itable stubs. Please refer to the bug description for all the details. I didn't want to duplicate that text.
>      
>      ARM and AARCH64 help requested!
>      The edits in vtableStubs_aarch64.cpp and vtableStubs_arm.cpp are made blindfolded. I am neither an ARM expert nor do I have build or test hardware available. I would be very grateful if one of the ARM gurus could please fill in for me.
>      
>      Thank you!
>      Lutz
>      
>      
>      
>