[CedricGuillemet]

Description

Adds the MSVC /MP (multiprocessor compilation) flag to the root CMakeLists.txt, enabling parallel compilation of source files when building with MSVC.
Remove Unity build as not mandatory for BRN Windows prebuilt binaries.

Changes

• Added add_compile_options(/MP) in the existing MSVC compiler-flags block in the root CMakeLists.txt.

Note: build time decrease is not that significant on the CI. Should be better with local builds.
local test PG debug full rebuild.
no MP :

 Build: 50 succeeded, 0 failed, 0 up-to-date, 0 skipped ==========
========== Build completed at 2:37 PM and took 01:35.764 minutes ==========

with MP:

========== Rebuild All: 50 succeeded, 0 failed, 0 skipped ==========
========== Rebuild completed at 2:42 PM and took 01:01.454 minutes ==========

[bghgary]

@CedricGuillemet I wonder if UNITY_BUILD being on is the reason why the build time is not decreasing in CI. Have you tried turning off UNITY_BUILD and turn on /MP?

[bghgary]

Another option to explore is the /m on MSBuild which will build projects in parallel. See https://learn.microsoft.com/en-us/cpp/build/reference/mp-build-with-multiple-processes?view=msvc-170#the-msbuild-tool. If the goal is to decrease build times, we should explore these options.

[CedricGuillemet]

@bghgary I remember adding UNITY_BUILD for footprint issue with BRN on Windows. Now it's not a problem anymore, do you think we should remove it?

I also want multicore with local builds with MSVC. So, the MSBuild flag is not enough.

EDIT: build time change is not significant with UNITY_BUILD off and /mp on the CI.

[bghgary]

I think so. It's annoying sometimes since it doesn't work, so we have to turn it off for some targets.

[Copilot]

Pull request overview

This PR aims to speed up Windows/MSVC builds by enabling MSVC multiprocessor compilation, but it also removes the existing “unity build” configuration plumbing across CI scripts, Gradle, and per-target CMake settings.

Changes:

• Add MSVC /MP to the root CMakeLists.txt compile options.
• Remove the UNITY_BUILD/CMAKE_UNITY_BUILD CI and Android Gradle wiring.
• Remove multiple per-target UNITY_BUILD false overrides across CMake targets/dependencies.

Reviewed changes

Copilot reviewed 23 out of 23 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
CMakeLists.txt	Adds MSVC /MP flag.
azure-pipelines.yml	Removes UNITY_BUILD pipeline variable.
.github/jobs/win32.yml	Drops -D CMAKE_UNITY_BUILD=$(UNITY_BUILD) from Win32 configure step.
.github/jobs/win32_precompiled_shader_test.yml	Drops unity-build CMake define from configure step.
.github/jobs/uwp.yml	Drops unity-build CMake define from configure step.
.github/jobs/test_install_win32.yml	Drops unity-build CMake define from configure step.
.github/jobs/test_install_macos.yml	Drops unity-build CMake define from configure step.
.github/jobs/test_install_linux.yml	Drops unity-build CMake define from configure step.
.github/jobs/test_install_ios.yml	Drops unity-build CMake define from configure step.
.github/jobs/macos.yml	Drops unity-build CMake define from configure step.
.github/jobs/linux.yml	Drops unity-build CMake define from configure step.
.github/jobs/ios.yml	Drops unity-build CMake define from configure step.
Apps/Playground/Android/app/build.gradle	Removes unity-build property plumbing; minor formatting change.
Apps/Playground/Android/BabylonNative/build.gradle	Removes unity-build property plumbing and -DCMAKE_UNITY_BUILD arg; minor formatting change.
Plugins/TestUtils/CMakeLists.txt	Removes target-level UNITY_BUILD false override on Apple.
Plugins/NativeCamera/CMakeLists.txt	Removes target-level UNITY_BUILD false override on Apple.
Dependencies/xr/CMakeLists.txt	Removes target-level UNITY_BUILD false override on Apple.
Dependencies/CMakeLists.txt	Removes multiple target-level UNITY_BUILD false overrides (bgfx 3rdparty, JsRuntimeHost-related targets, libwebp sharpyuv, etc.).
Core/Graphics/CMakeLists.txt	Removes target-level UNITY_BUILD false override.
Apps/UnitTests/CMakeLists.txt	Removes target-level UNITY_BUILD false override.
Apps/PrecompiledShaderTest/CMakeLists.txt	Removes target-level UNITY_BUILD false overrides.
Apps/Playground/CMakeLists.txt	Removes target-level UNITY_BUILD false override on Apple.
Apps/HeadlessScreenshotApp/CMakeLists.txt	Removes target-level UNITY_BUILD false override.

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