v8: forward compatibility to current V8 master

[addaleax]

As discussed in nodejs/CTC#99, we are aiming for a upgrade to V8 6.0 in the Node 8.x lifecycle. Therefore, it makes sense to apply changes that are semver-major because they break the API or ABI before that upgrade actually happens.

Changes that are marked deps: are cherry-picks, the rest is manual work and needs review.

This is a bit WIP because I’m still compiling to see if everything works out. ;)

CI: https://ci.nodejs.org/job/node-test-commit/9702/
CI: https://ci.nodejs.org/job/node-test-commit/9705/
CI: https://ci.nodejs.org/job/node-test-commit/9720/
V8 CI: https://ci.nodejs.org/job/node-test-commit-v8-linux/683/
V8 CI: https://ci.nodejs.org/job/node-test-commit-v8-linux/685/
V8 CI: https://ci.nodejs.org/job/node-test-commit-v8-linux/686/
V8 CI: https://ci.nodejs.org/job/node-test-commit-v8-linux/687/
V8 CI: https://ci.nodejs.org/job/node-test-commit-v8-linux/691/
CITGM: https://ci.nodejs.org/view/Node.js-citgm/job/citgm-smoker/763/
CITGM on master for comparison: https://ci.nodejs.org/view/Node.js-citgm/job/citgm-smoker/764/

@nodejs/v8 @targos @jasnell

Checklist

• make -j4 test (UNIX), or vcbuild test (Windows) passes
• commit message follows commit guidelines
• figure out whether to do anything about removed command line flags

Affected core subsystem(s)

deps/v8

[addaleax]

This works locally, so I kicked off CI.

Flags that would still be removed:

-  --datetime_format_to_parts (enable "Intl.DateTimeFormat.formatToParts")
-  --future (Implies all staged features that we want to ship in the not-too-far future)
-  --ignition_staging (use ignition with all staged features)
-  --ignition_deadcode (use ignition dead code elimination optimizer)
-        type: bool  default: true
-  --ignition_peephole (use ignition peephole optimizer)
-  --collect_megamorphic_maps_from_stub_cache (crankshaft harvests type feedback from stub cache)
-        type: bool  default: false
-  --trace_wasm_text_start (start function for WASM text generation (inclusive))
-        type: int  default: 0
-  --trace_wasm_text_end (end function for WASM text generation (exclusive))
-        type: int  default: 0
-  --wasm_loop_assignment_analysis (perform loop assignment analysis for WASM)
-        type: bool  default: true
-  --wasm_trap_if (enable the use of the trap_if operator for traps)
-        type: bool  default: true
-  --zap_code_space (Zap free memory in code space with 0xCC while sweeping.)
-        type: bool  default: false
-  --enable_fast_array_builtins (use optimized builtins)
-  --max_opt_count (maximum number of optimization attempts before giving up.)
-  --trace_debug_json (trace debugging JSON request/response)
-        type: bool  default: false
-  --trace_object_groups (print object groups detected during each garbage collection)
-        type: bool  default: false
-  --preparser_scope_analysis (perform scope analysis for preparsed inner functions)

Remaining diff to current V8 master include/v8.h: https://gist.github.com/addaleax/4cb6d8dc35e4c4adfe89b8d55680f0f6

[targos]

I suppose we can have this only on v8.x? That way we will be able to simply update master to 5.9 when it's stable.
Also is it compatible with this fix from the V8 team?: v8@eb87979

[addaleax]

I suppose we can have this only on v8.x? That way we will be able to simply update master to 5.9 when it's stable.

If you prefer that, yes, I guess so. Edit: I’ll just switch the base branch to v8.x-staging once V8 5.8 is on it.

Also is it compatible with this fix from the V8 team?: v8/node@eb87979

Heh, well, from it quick glance it looks that way – it’s a bit hard to tell since everything is squashed into one big change. Edit: See #12878 (comment) for a better answer :)

[addaleax]

Updated with one extra change from #12878 that seems to make sense (though it probably doesn’t actually affect addons anyway). The diff between the two PRs looks pretty nice to me, which seems like a good sign this will work out. :)

[jasnell]

Rubber stamp LGTM from me. I haven't gone through the code in detail, but I applied the patch and gave it some tests and everything appears to work as expected.