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Optimize MSVC build throughput for debug and release compile/link configurations #503

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f85e542
Initial plan
Copilot Mar 7, 2026
01ab2ef
build(msvc): enable faster debug info and linking defaults
Copilot Mar 7, 2026
d3085d0
build: speed release by removing CUDA debug flags from Release
Copilot Mar 7, 2026
8deedf3
build: add fast MSVC release-link defaults for local iteration
Copilot Mar 7, 2026
63583ec
build: avoid MSVC release warning and cut VS module scan overhead
Copilot Mar 7, 2026
3a13342
build: scope msvc fast-link flags to real linker targets
Copilot Mar 9, 2026
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31 changes: 30 additions & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,9 @@ set(CMAKE_CUDA_STANDARD 20)
set(CMAKE_CUDA_STANDARD_REQUIRED ON)
set(CMAKE_CUDA_SEPARABLE_COMPILATION ON)

set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} -g -lineinfo --use-local-env -use_fast_math")
set(CMAKE_CUDA_FLAGS "${CMAKE_CUDA_FLAGS} --use-local-env -use_fast_math")
set(CMAKE_CUDA_FLAGS_DEBUG "${CMAKE_CUDA_FLAGS_DEBUG} -g -lineinfo")
set(CMAKE_CUDA_FLAGS_RELWITHDEBINFO "${CMAKE_CUDA_FLAGS_RELWITHDEBINFO} -lineinfo")

project(alien-project LANGUAGES C CXX CUDA)

Expand All @@ -29,6 +31,33 @@ include_directories(
external)

if (MSVC)
option(ALIEN_MSVC_FAST_BUILD "Enable faster MSVC debug info generation and linking for local development builds" ON)
if (ALIEN_MSVC_FAST_BUILD)
# Prefer /Z7 over /Zi in Debug/RelWithDebInfo to reduce PDB writer contention with /MP.
set(CMAKE_MSVC_DEBUG_INFORMATION_FORMAT "$<$<CONFIG:Debug,RelWithDebInfo>:Embedded>")
# Reduce debug link time in Visual Studio builds for real linker invocations.
string(APPEND CMAKE_EXE_LINKER_FLAGS_DEBUG " /DEBUG:FASTLINK")
string(APPEND CMAKE_SHARED_LINKER_FLAGS_DEBUG " /DEBUG:FASTLINK")
string(APPEND CMAKE_MODULE_LINKER_FLAGS_DEBUG " /DEBUG:FASTLINK")
string(APPEND CMAKE_EXE_LINKER_FLAGS_RELWITHDEBINFO " /DEBUG:FASTLINK")
string(APPEND CMAKE_SHARED_LINKER_FLAGS_RELWITHDEBINFO " /DEBUG:FASTLINK")
string(APPEND CMAKE_MODULE_LINKER_FLAGS_RELWITHDEBINFO " /DEBUG:FASTLINK")
endif()

option(ALIEN_MSVC_DISABLE_MODULE_SCAN "Disable MSVC C++ module scanning for faster non-module builds" ON)
if (ALIEN_MSVC_DISABLE_MODULE_SCAN)
# This project does not use C++ modules; dependency scanning adds avoidable overhead in Visual Studio builds.
set(CMAKE_CXX_SCAN_FOR_MODULES OFF)
endif()

option(ALIEN_MSVC_FAST_RELEASE_BUILD "Enable faster MSVC release linking for local development builds" ON)
if (ALIEN_MSVC_FAST_RELEASE_BUILD)
# Improve /GL + /LTCG release link throughput for real linker invocations.
string(APPEND CMAKE_EXE_LINKER_FLAGS_RELEASE " /LTCG:INCREMENTAL")
string(APPEND CMAKE_SHARED_LINKER_FLAGS_RELEASE " /LTCG:INCREMENTAL")
string(APPEND CMAKE_MODULE_LINKER_FLAGS_RELEASE " /LTCG:INCREMENTAL")
endif()

# Suppress `warning C4005: 'FOO': macro redefinition`
add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-wd4005>)

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5 changes: 5 additions & 0 deletions README.md
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Expand Up @@ -94,6 +94,11 @@ mkdir build && cd build
cmake .. -DCMAKE_BUILD_TYPE=Release
cmake --build . --config Release -j8
```
On MSVC, CMake enables `ALIEN_MSVC_FAST_BUILD=ON` by default, which uses `/Z7` for Debug/RelWithDebInfo and applies `/DEBUG:FASTLINK` on executable/shared/module link steps to shorten local incremental build times.
Release builds no longer include CUDA debug info flags by default (`-g`, `-lineinfo`), which shortens release compile times (including MSVC toolchains).
For MSVC, `ALIEN_MSVC_DISABLE_MODULE_SCAN=ON` is enabled by default to skip C++ module dependency scanning in non-module builds and reduce compile overhead in Visual Studio.
`ALIEN_MSVC_FAST_RELEASE_BUILD=ON` is also enabled by default and applies `/LTCG:INCREMENTAL` on executable/shared/module link steps for faster local Release links without forcing `/INCREMENTAL`.

If everything goes well, the ALIEN executable can be found under the build directory in `./alien` or `.\Release\alien.exe` depending on the used toolchain and platform.
It is important to start ALIEN directly from the build folder, otherwise it will not find the resource folder.

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