RFR(M): 8195112: x86 (32 bit): implementation for Thread-local handshakes

[Lindenmaier, Goetz]

Hi Martin, 

I had a look at your change. 

c1_LIRAssembler_x86.cpp:
Address(poll_addr, in_bytes(Thread::polling_page_offset()
Why do you need to use in_bytes to cast away ByteSize?
In the debug build, there is a proper Address constructor, and 
in opt it should be pointless.  In other places, you don't use it 
either.

macroAssembler_x86.hpp
Maybe you could coment above the definition of safepoint_poo()
// If thread_reg is != noreg the code assumes the register passed contains
// the thread.

sharedRuntime_x86_32.cpp:
Please break comment to shorter lines.

Sometimes, you protect code by _LP64, sometimes by AMD64.
Why? (I prefer AMD64 to protect code that depends on the architectural
extension for 64-bit ...).
Instead of ifndef AMD64 you can use ifdef IA32 which you do
at other places :)

I think the submission forest is good to show you didn't break
X86_64. So I think if it passes there you can push it.

Reviewed.

Best regards,
  Goetz.

-----Original Message-----
From: hotspot-runtime-dev [mailto:hotspot-runtime-dev-bounces at openjdk.java.net] On Behalf Of Doerr, Martin
Sent: Monday, February 19, 2018 1:15 PM
To: Robbin Ehn <robbin.ehn at oracle.com>; hotspot-runtime-dev at openjdk.java.net
Subject: [CAUTION] RE: RFR(M): 8195112: x86 (32 bit): implementation for Thread-local handshakes

Hi,

I have disabled ThreadLocalHandshakes by default on linux 32 bit.
After some performance measurements, I have also switched it off on Windows 32 bit if the server compiler is not active (arguments.cpp) which is the default.
C1 performance is affected if enabled. C2 and tiered performance look ok.

So on 32 bit, ThreadLocalHandshakes are only used on Windows when enabling server mode with this updated version.

Please review:
http://cr.openjdk.java.net/~mdoerr/8195112_x86_local_poll/webrev.01/

@Robbin: I guess the submission forest is not helpful for 32 bit?
Will I still need a sponsor for it?

Best regards,
Martin


-----Original Message-----
From: Andrew Haley [mailto:aph at redhat.com] 
Sent: Donnerstag, 8. Februar 2018 17:28
To: Doerr, Martin <martin.doerr at sap.com>; David Holmes <david.holmes at oracle.com>; Robbin Ehn <robbin.ehn at oracle.com>; hotspot-runtime-dev at openjdk.java.net
Subject: Re: RFR(M): 8195112: x86 (32 bit): implementation for Thread-local handshakes

On 08/02/18 13:04, Doerr, Martin wrote:
> Are you planning to fix it soon?
> If so, we can delay my change until it was pushed.

I was, but I keep getting interrupted by urgent things.

> Otherwise, we can keep ThreadLocalHandshakes off by default on linux x86 32 bit.
> That would be ok for us, too. We'd just like the feature to be available.

Sure, do that.  Thanks.

-- 
Andrew Haley
Java Platform Lead Engineer
Red Hat UK Ltd. <https://www.redhat.com>
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