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Comment by Klathmon | Hacker News Reader

>It's why official builds will generally be faster than compiling from scratch yourself.

Would it be possible for Google to publish the profile data along with the source code to enable those who compile from scratch to have these same optimizations?

>I'm surprised Chrome wasn't already taking advantage of PGO.

They have been on windows since M53 (released in 2016), but this seems to be a better implementation and it's now for MacOS as well now.

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> Would it be possible for Google to publish the profile data

They do.

https://chromium.googlesource.com/chromium/src.git/+/master/...

Can you explain this because the article says:

  It is rolling out with Chrome M85 on Mac and Windows.

Never mind. This [1] says:

  Starting in Chrome 53, Chrome has started using
  Microsoft’s Profile Guided Optimization (PGO)
  technology to make Chrome up to 15% faster
  on Windows.

This strongly implies Google was using MSVC for the M53 build.

[1] https://blog.chromium.org/2016/10/making-chrome-on-windows-f...

From the article: "PGO was initially introduced in M53 for Chrome on Windows using Microsoft Visual C++ (MSVC) […] In M85, we are rolling out PGO on Mac and Windows using Clang."

So it sounds like they've been using PGO for a while using MSVC, and now they've started using PGO with Clang.

Wouldn't PGO only work with the exact source code, flags, compiler version, etc... used by google ? At which point you'll end up with the exact same binary than Google's too

Is M85 the first Chrome Windows release done with Clang, as opposed to MSVC? I haven't been following the Windows side of it.

Great question! Anyone have this answer?

Chrome M64 was the first shipping version built with Clang on Windows: http://web.archive.org/web/20200125010517/http://blog.llvm.o...

Thanks. So Chrome on Windows had MSVC PGO from 53-63, but lost PGO from 64-84.

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