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

[Aleksey Shipilev]

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`

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

Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/9567/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=9567&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8290704
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/9567.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/9567/head:pull/9567

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