Victor Gomes
9de0d9c878
Remove the experimental --maglev-object-tracking flag (and --trace-maglev-object-tracking) along with virtual object mutation tracking, snapshotting, cloning, and control-flow merging in Maglev graph building. Preserve IsFieldConstant (vobj::FieldConstness:: kConstAfterInit) for folding constant fields on VirtualJSArrayIteratorShape. M4 Pinpoint benchmarks (150 repeats each) show that --maglev-object-tracking provides negligible benefit in Maglev-only mode and is neutral/noisy under Turbolev (which has its own dedicated post-inlining escape analysis pass, TurbolevEscapeAnalysis) while introducing significant complexity and sub-benchmark regressions: - JS3 (--no-turbofan vs --no-turbofan --maglev-object-tracking): https://pinpoint-dot-chromeperf.appspot.com/job/10eab4f9990000 (+0.27% Total/Score, p=0.0002; +0.38% Total/Average) - JS3 (--turbolev vs --turbolev --maglev-object-tracking): https://pinpoint-dot-chromeperf.appspot.com/job/124a247e990000 (+0.10% Total/Score, p=0.2135 [noise]; +0.02% Total/Average, p=0.8673 [noise], with -6.16% Score / -12.12% Worst regression on doxbee-promise and -3.01% Score / -9.06% First regression on js-tokens) - SP3 (--no-turbofan vs --no-turbofan --maglev-object-tracking): https://pinpoint-dot-chromeperf.appspot.com/job/121545ae990000 (+0.09% Score, p=0.0084) - SP3 (--turbolev vs --turbolev --maglev-object-tracking): https://pinpoint-dot-chromeperf.appspot.com/job/12769e16990000 (+0.02% Score, p=0.3416 [noise]) Removing the virtual object snapshotting, merging, and tracking overhead in this CL also improves JS3 code-load and startup benchmarks (M4 Pinpoint, 150 repeats each): - JS3 (--no-turbofan): https://pinpoint-dot-chromeperf.appspot.com/job/13d1e316990000 (+0.14% Total/Score, p=0.0212; first-inspector-code-load +1.89% Score / +2.64% Worst, multi-inspector-code-load +1.35% Score / +1.93% Worst, octane-code-load +0.75% Score, babylonjs-startup-es6 +0.38% Score) - JS3 (--turbolev): https://pinpoint-dot-chromeperf.appspot.com/job/11c76518990000 (-0.03% Total/Score, p=0.9263 [noise]; first-inspector-code-load +1.59% Score / +2.14% Worst, multi-inspector-code-load +1.19% Score / +1.68% Worst, octane-code-load +0.50% Average, babylonjs-startup-es6 +0.35% Score) - SP3 (--no-turbofan): https://pinpoint-dot-chromeperf.appspot.com/job/120d2365990000 (-0.04% Score, p=0.1507 [noise]) - SP3 (--turbolev): https://pinpoint-dot-chromeperf.appspot.com/job/15be49b1990000 (+0.04% Score, p=0.1009 [noise]) Bug: 582696367 Fixed: 577666671 Change-Id: Ia9d483f9c2a188102eea6510b47656be346c183a Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/8727069 Commit-Queue: Leszek Swirski <leszeks@chromium.org> Reviewed-by: Leszek Swirski <leszeks@chromium.org> Auto-Submit: Victor Gomes <victorgomes@chromium.org> Commit-Queue: Victor Gomes <victorgomes@chromium.org> Cr-Commit-Position: refs/heads/main@{#111769}
TOOLS
This directory contains debugging and investigation tools for V8.
The contents are regularly mirrored to http://v8.dev/tools.
Local Development
For local development you have to start a local webserver under http://localhost:8000:
cd tools/;
npm install;
npm run start-webserver;
Local Symbol Server
The system-analyzer can symbolize profiles for local binaries by running a local symbol server
cd tools/;
./system-analyzer/local-server.sh;
Note that the local symbol server will run nm and objdump and has access to
your files.