Basic V8 guide

v8.md

Install V8 on Linux

Requirements

• git

Installation

depot_tools

First we have to install depot_tools. You can clone that into your home directory or whatever you want

git clone https://chromium.googlesource.com/chromium/tools/depot_tools.git

then insert absolute depot_tools path to your PATH. To do that you have to add this line at the end of your ~/.bashrc file (or .bash_profile, or any file you're using as source)

export PATH=$PATH:/path/to/depot_tools

if you've cloned that repo into your home directory it's going to be

export PATH=$PATH:/home/<user_name>/depot_tools

At the end just call

source ~/.bashrc

To reload your source.

You should be able to call

gclient

from your terminal now

Getting V8

Now let's create folder when your V8 is going to be

mkdir ~/v8
cd ~/v8

Get V8 code and build dependencies

fetch v8
cd v8

// Install build dependencies (Linux needs it, Mac should have those already)
./build/install-build-deps.sh
// Get a coffee

let's compile our V8

tools/dev/gm.py x64.release.check
// Get another coffee, tidy up your room, do the laundry

You're basically done and your v8 is in ./out/x64.release/d8

Make it easier to use (optional)

If you don't want to use v8 like that

~/v8/v8/out/x64.release/d8 sth.js

every time you can to call it it's useful to add it into your .bashrc file as alias (note that if you're Mac use then linux-tick-processor is mac-tick-processor)

alias d8=/home/<user_name>/v8/v8/out/x64.release/d8
alias tick-processor=/home/<user_name>/v8/v8/tools/linux-tick-processor
alias ic-processor=/home/<user_name>/v8/v8/tools/ic-processor
export D8_PATH="/home/<user_name>/v8/v8/out/x64.release"

Now you can just call

d8 sth.js

Remember to call source ~/.bashrc at the end, otherwise it won't be in your shell.

Using V8

I'm calling V8 with alias setup in my bash profile file. If you didn't do that on your machine replace d8 with /path/to/my/v8/out/x64.release/d8

Every time you want to use V8 only thing you need to do is to call it and pass list of parameters with JS file

d8 --prof index.js

sometimes you may want to output print from V8 into text file (easier to read)

d8 --print-opt-code index.js > optcode.txt

What about tick-processor alias?

After running --prof you should have v8.log file which is really hard to read. That's where tick-processor comes in handy. Run tick-processor (or full path to you linux-tick-processor file) from withing folder with v8.log file. You should see list of human readable statistics now.

The same goes for ic-processor which is responsible for processing trace-ic (inline cache).

List of V8 options

All options are available when calling d8 --help. I've just filtered more useful ones. Always use help to get latest list of features.

  --use-strict (enforce strict mode)
        type: bool  default: false
  --enable-one-shot-optimization (Enable size optimizations for the code that will only be executed once)
        type: bool  default: true
  --use-ic (use inline caching)
        type: bool  default: true
  --print-bytecode (print bytecode generated by ignition interpreter)
        type: bool  default: false
  --print-bytecode-filter (filter for selecting which functions to print bytecode)
        type: string  default: *
  --allow-natives-syntax (allow natives syntax, like %HaveSameMap)
        type: bool  default: false
  --runtime-call-stats (report runtime call counts and times)
        type: bool  default: false
  --serialization-statistics (Collect statistics on serialized objects.)
        type: bool  default: false
  --prof (Log statistical profiling information (implies --log-code).)
        type: bool  default: false
  --print-opt-source (print source code of optimized and inlined functions)
        type: bool  default: false
  --print-code (print generated code)
        type: bool  default: false
  --print-opt-code (print optimized code)
        type: bool  default: false
  --print-code-verbose (print more information for code)
        type: bool  default: false

Logging

  --log (Minimal logging (no API, code, GC, suspect, or handles samples).)
        type: bool  default: false
  --log-all (Log all events to the log file.)
        type: bool  default: false
  --log-api (Log API events to the log file.)
        type: bool  default: false
  --log-code (Log code events to the log file without profiling.)
        type: bool  default: false
  --log-handles (Log global handle events.)
        type: bool  default: false
  --log-suspect (Log suspect operations.)
        type: bool  default: false
  --log-source-code (Log source code.)
        type: bool  default: false
  --log-function-events (Log function events (parse, compile, execute) separately.)
        type: bool  default: false
  --log-internal-timer-events (Time internal events.)
        type: bool  default: false

And there is a hole bunch of tracking options

  --trace-ignition-codegen (trace the codegen of ignition interpreter bytecode handlers)
        type: bool  default: false
  --trace-ignition-dispatches (traces the dispatches to bytecode handlers by the ignition interpreter)
        type: bool  default: false
  --trace-migration (trace object migration)
        type: bool  default: false
  --trace-generalization (trace map generalization)
        type: bool  default: false
  --trace-heap-broker-verbose (trace the heap broker verbosely (all reports))
        type: bool  default: false
  --trace-turbo (trace generated TurboFan IR)
        type: bool  default: false
  --trace-turbo-inlining (trace TurboFan inlining)
        type: bool  default: false
  --trace-gc (print one trace line following each garbage collection)
        type: bool  default: false
  --trace-opt-verbose (extra verbose compilation tracing)
        type: bool  default: false
  --trace-deopt (trace optimize function deoptimization)
        type: bool  default: false
  --trace-ic (trace inline cache state transitions for tools/ic-processor)
        type: bool  default: false

That's not all, just ones i've found really useful at the beginning.

gclinet or gclient ??
only gclient exists in ~/depot_tools