RFR: 8290704: x86: TemplateTable::_new should not call eden_allocate() without contiguous allocs enabled

[Coleen Phillimore]

On Wed, 20 Jul 2022 09:46:08 GMT, Aleksey Shipilev <shade at openjdk.org> wrote:

> I have been doing the thread register verification patches for better Loom debugging, and one of the failures it caught is calling `eden_allocate` with garbage thread register. That method actually shortcuts:
> 
> 
> void BarrierSetAssembler::eden_allocate(MacroAssembler* masm,
>                                         Register thread, Register obj,
>                                         Register var_size_in_bytes,
>                                         int con_size_in_bytes,
>                                         Register t1,
>                                         Label& slow_case) {
>   ...
>   if (!Universe::heap()->supports_inline_contig_alloc()) {
>     __ jmp(slow_case);
> 
> 
> ...and does not use the thread. But it is still confusing. Other ports gate the calls to `eden_allocate` with `allow_shared_alloc`, x86 should do the same.
> 
> (This thing would be cleaner when/if we remove the support for contiguous inline allocs altogether, see [JDK-8290706](https://bugs.openjdk.org/browse/JDK-8290706)).
> 
> Additional testing:
>  - [x] Linux x86_32 fastdebug `tier1`

Seems good to me.

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

Marked as reviewed by coleenp (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9567