Which args.gn are you using for the build?

My usual build settings are:

use_lld = true
is_debug = true
is_component_build = true
enable_nacl = false
target_cpu = "x86"
remove_webcore_debug_symbols=true
use_jumbo_build = true
goma_dir = "C:\src\goma\goma-win64"
use_goma = true
symbol_level = 2

With link.exe this gives us incremental linking because this is a debug/component build.

Any updates?
Incremental debug build is so important for windows developers.

How much incremental build time is different in your typical workflow between lld and link.exe?

Currently I'm building with:
target_cpu = "x86"
enable_nacl = false
is_component_build = true
is_debug = true
use_lld = false
win_console_app = true
use_goma = true

That takes 30 seconds to incremental build.
If I turn "use_lld" on, it takes 90 seconds.

What is your main build target and the files you often modify?

and +Bob who owns the upstream bug

Also consider to use use_ghash option in args.gn.
https://cs.chromium.org/chromium/src/build/config/compiler/BUILD.gn?type=cs&q=use_ghash&sq=package:chromium&g=0&l=130

I'm working on third_party/blink/renderer/core/*.
I'm building content_shell and webkit_unit_tests daily.

Or is it possible to emit .lib/.dll separately?
I think debug infos are in dll and took time to generate it, but lib can be generated much faster.

Then some dependency chain can be (partially) deserialized for blink core modified case like below.
* blink_core.dll and blink_core.lib (40~50 seconds) -> chrome.dll and chrome.lib (30 ~ 40 seconds), 70~90 seconds in total

* blink_core.lib (10 seconds?) -> chrome.dll and chrome.lib (30 ~ 40 seconds), 40~50 seconds in total
   blink_core.dll (40~50 seconds)

Sorry, I meant pdb, not dll in #12, so considered to generate dll/lib and pdb separately.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e3cc83dcfbd6679c8b67b958287668e524960deb

commit e3cc83dcfbd6679c8b67b958287668e524960deb
Author: Takuto Ikuta <tikuta@chromium.org>
Date: Sat Jun 09 01:02:42 2018

Make lld only update export lib timestamp when they change

With this patch, incremental component debug build time of chrome just
after touching .\third_party\blink\renderer\core\url\dom_url.cc
becomes 50 seconds, reduced from 186 seconds without this patch.

This patch improves build by not invoking linker for some components
(blink_modules, content, chrome and etc) when building chrome after
changing only .cc files for blink_core.

Bug: 801351
Change-Id: I2731449b1f89470201c35c63eeb2d31dd5a82371
Reviewed-on: https://chromium-review.googlesource.com/1092611
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565807}
[modify] https://crrev.com/e3cc83dcfbd6679c8b67b958287668e524960deb/build/config/win/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/54f7be95955c9b35e64569c1d40e0c3dd097359c

commit 54f7be95955c9b35e64569c1d40e0c3dd097359c
Author: Mirko Bonadei <mbonadei@chromium.org>
Date: Tue Jun 12 15:49:58 2018

Defining incremental_linking_off_switch when !use_lld.

This should fix the following error on WebRTC's MSVC bots:

ERROR at //build/config/win/BUILD.gn:481:15: Undefined identifier
    ldflags = incremental_linking_off_switch

Bug: 801351
Change-Id: I3e1068360fb96bfda1e8a4acec39ec43236ec415
Reviewed-on: https://chromium-review.googlesource.com/1097224
Commit-Queue: Mirko Bonadei <mbonadei@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566438}
[modify] https://crrev.com/54f7be95955c9b35e64569c1d40e0c3dd097359c/build/config/win/BUILD.gn

I heard that splitting blink_core into 2 or more dlls made build faster.
Anyone know how to change Build.gn?

Having offline chat with yoichio, I suggested followings for faster debug blink_core link in component build.

* Use symbol_level = 1 or 0 and blink_symbol_level = 2, this may need to specify blink_symbols_config for some blink unittests.
* Investigate the possibility of specifying jumbo_component in https://cs.chromium.org/chromium/src/third_party/blink/renderer/core/core.gni?l=76&rcl=d6870941e6becaaa00888c02c5ff7697ce2c2c6f
* Or maybe, specifying jumbo_static_library there improves link time of incremental build even when we do component build.

Actually, using separated symbol level looks not improve link time in blink_core.