Add and document sccache support for Windows
The two `cl.exe` flags that confused sccache on my setup, and resulted
in uncacheable calls are the following:
- `/Brepro`
- `/showIncludes:user`
This CL disables these options if `cc_wrapper` is set and documents that
`chrome_pgo_phase` must be disabled if sccache will be used.
These settings result in a high number of sccache cache hits and
significant speed-up when not using Goma:
```
Compile requests 27222
Compile requests executed 27222
Cache hits 27218
Cache hits (C/C++) 27218
Cache misses 4
Cache misses (C/C++) 4
```
For the record, this change has been tested on Windows 10 Pro 20H2,
sccache v0.2.15, and Visual Studio Community 2019 in an Electron.js
build environment.
R=thakis@chromium.org, tikuta@chromium.org
Bug: 1224369,787983
Change-Id: I8e2921aabca04598119743906ec6989ef43167ad
Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2989169
Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#897180}
diff --git a/AUTHORS b/AUTHORS
index d130774..a748783 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -551,6 +551,7 @@
Josué Ratelle <jorat1346@gmail.com>
Josyula Venkat Narasimham <venkat.nj@samsung.com>
Joyer Huang <collger@gmail.com>
+Juan Cruz Viotti <jv@jviotti.com>
Juan Jose Lopez Jaimez <jj.lopezjaimez@gmail.com>
Juhui Lee <juhui24.lee@samsung.com>
Julian Geppert <spctstr@gmail.com>
diff --git a/build/config/win/BUILD.gn b/build/config/win/BUILD.gn
index ca0c916..1d32642 100644
--- a/build/config/win/BUILD.gn
+++ b/build/config/win/BUILD.gn
@@ -126,7 +126,8 @@
}
}
- if (use_lld && !use_thin_lto && (is_clang || !use_goma)) {
+ # Disabled with cc_wrapper because of https://github.com/mozilla/sccache/issues/264
+ if (use_lld && !use_thin_lto && (is_clang || !use_goma) && cc_wrapper == "") {
# /Brepro lets the compiler not write the mtime field in the .obj output.
# link.exe /incremental relies on this field to work correctly, but lld
# never looks at this timestamp, so it's safe to pass this flag with
diff --git a/build/toolchain/win/BUILD.gn b/build/toolchain/win/BUILD.gn
index 7dd5888..c3def9ec 100644
--- a/build/toolchain/win/BUILD.gn
+++ b/build/toolchain/win/BUILD.gn
@@ -190,7 +190,8 @@
coverage_wrapper = ""
}
- if (toolchain_args.is_clang) {
+ # Disabled with cc_wrapper because of https://github.com/mozilla/sccache/issues/1013
+ if (toolchain_args.is_clang && cc_wrapper == "") {
# This flag omits system includes from /showIncludes output, to reduce the
# amount of data to parse and store in .ninja_deps. We do this on non-Windows too,
# and already make sure rebuilds after win sdk / libc++ / clang header updates happen via
diff --git a/docs/windows_build_instructions.md b/docs/windows_build_instructions.md
index be30a8eb4..370e9be 100644
--- a/docs/windows_build_instructions.md
+++ b/docs/windows_build_instructions.md
@@ -186,6 +186,7 @@
operating system and CPU.
* For more info on GN, run `gn help` on the command line or read the [quick
start guide](https://gn.googlesource.com/gn/+/master/docs/quick_start.md).
+
### Faster builds
* Reduce file system overhead by excluding build directories from
@@ -234,6 +235,14 @@
Still, builds will take many hours on many machines.
+#### Use SCCACHE
+
+You might be able to use [sccache](https://github.com/mozilla/sccache) for the
+build process by enabling the following arguments:
+
+* `cc_wrapper = "sccache"` - assuming the `sccache` binary is in your `%PATH%`
+* `chrome_pgo_phase = 0`
+
### Why is my build slow?
Many things can make builds slow, with Windows Defender slowing process startups
