Flag conflict detection 1) bails out on incompatible flag values (e.g.
--jitless and --turbofan) and 2) handles such bailouts transparently in
the test runner by marking affected tests as OUTCOMES_FAIL.
This CL adds full support for readonly flags to this system, together
with required additional annotations in variants.py.
Drive-by: assert proper use of v8_enable_slow_dchecks, and add
support when dcheck_always_on is set.
Drive-by: introduce has_maglev build variable detection based on
v8_enable_maglev and use that for .status file annotations.
Drive-by: protect against unintended overwrites of build variables
in statusfile.py.
Cq-Include-Trybots: luci.v8.try:v8_linux64_fyi_rel
Bug: v8:13629,v8:10577
Change-Id: I04de399139a0490806df8bfee7e75e2ec767b4b5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4135879
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Reviewed-by: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Jakob Linke <jgruber@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85130}
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