RFR: 8258838: Remove JVM option UseStackBanging

[David Holmes]

On Thu, 7 Jan 2021 20:03:19 GMT, Harold Seigel <hseigel at openjdk.org> wrote:

> Please review this change to remove the JVM develop flag UseStackBanging and always use stack banging.
> 
> The change was tested with tiers 1-2 on Linux, Mac OS, and Windows, tiers 3-5 on Linux x64, and cross-builds on PPC64, Linux32, and S390x.
> 
> Thanks, Harold

Hi Harold,

Changes seem fine. I'm enjoying your "war" on legacy flags :) 

A couple of minor comments below.

Thanks,
David

src/hotspot/cpu/aarch64/aarch64.ad line 3:

> 1: //
> 2: // Copyright (c) 2003, 2021, Oracle and/or its affiliates. All rights reserved.
> 3: // Copyright (c) 2014, 2021, Red Hat, Inc. All rights reserved.

Not clear if non-Oracle copyrights need updating when we update Oracle ones.

src/hotspot/cpu/arm/sharedRuntime_arm.cpp line 1507:

> 1505:   // interpreter would need. So this stack banging should never
> 1506:   // trigger a fault. Verify that it does not on non product builds.
> 1507:   // See if it is enough stack to push deoptimized frames

Now the two comment blocks flow together, please add a period to line 1507. Thanks.

src/hotspot/share/jvmci/jvmciCompilerToVMInit.cpp line 252:

> 250:   X86_ONLY(do_intx_flag(UseSSE))                                           \
> 251:   COMPILER2_PRESENT(do_bool_flag(UseSquareToLenIntrinsic))                 \
> 252:   do_bool_flag(UseStackBanging)                                            \

Compiler folk will need to verify if this change is okay wrt. upstream Graal code.

-------------

Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1988