RFR: 8290706: Remove the support for inline contiguous allocations [v2]

[Tobias Hartmann]

On Thu, 21 Jul 2022 16:17:38 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

>> See the bug for rationale and link to RFC.
>> 
>> This removes the 3rd allocation path (first two being TLAB and native GC interface), that is used by Serial/Parallel when TLABs are not available. There is little sense in keeping this code, especially since it requires supporting a bunch of platform-specific assembly.
>> 
>> Additional testing:
>>  - [x] Linux x86_64 fastdebug `tier1`
>>  - [x] Linux x86_32 fastdebug `tier1`
>>  - [x] Linux AArch64 fastdebug `tier1`
>>  - [x] Linux x86_64 Zero build
>>  - [x] Linux AArch64 cross-build (attn @theRealAph, @adinn)
>>  - [x] Linux ARM cross-build (attn @bulasevich, @snazarkin)
>>  - [x] Linux S390X cross-build (attn @backwaterred, @RealLucy)
>>  - [x] Linux PPC64 cross-build (attn @TheRealMDoerr, @reinrich)
>>  - [x] Linux RISC-V cross-build (attn @RealFYang)
>> 
>> Apart from x86 and AArch64, I only verified the cross-compilation builds pass, no other testing is done.
>> 
>> I did not touch the JVMCI interfaces, since I am not sure what is the proper protocol for JVMCI changes.
>
> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:
> 
>  - Merge branch 'master' into JDK-8290706-remove-inline-contig
>  - Work

JIT changes look good to me.

src/hotspot/share/gc/shared/c2/barrierSetC2.cpp line 718:

> 716:   //       prevent a degradation of the optimization.
> 717:   //       See comment in memnode.hpp, around line 227 in class LoadPNode.
> 718:   Node *tlab_end = macro->make_load(toobig_false, mem, tlab_end_adr, 0, TypeRawPtr::BOTTOM, T_ADDRESS);

Suggestion:

  Node* tlab_end = macro->make_load(toobig_false, mem, tlab_end_adr, 0, TypeRawPtr::BOTTOM, T_ADDRESS);


Some more occurences in below changes/code.

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Marked as reviewed by thartmann (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9576