Disable /Zi when using ccache on Windows/MSVC.
#11841
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
ScottTodd
added
infrastructure
ScottTodd
commented
Jan 14, 2023
Comment on lines
+436
to
+441
| message(STATUS "Replacing /Zi with /Z7 since ccache is in use and does not support /Zi") | ||
| # https://learn.microsoft.com/en-us/cpp/build/reference/z7-zi-zi-debug-information-format | ||
| string(REPLACE "/Zi" "/Z7" CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG}") | ||
| string(REPLACE "/Zi" "/Z7" CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG}") | ||
| string(REPLACE "/Zi" "/Z7" CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO}") | ||
| string(REPLACE "/Zi" "/Z7" CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO}") |
There was a problem hiding this comment.
Note: this will affect downstream users too. Not really a fan of when projects modify global flags, but I think this is niche enough...
There was a problem hiding this comment.
since it's conditional on ccache usage and anyone using ccache would need the same thing it seems ok - may still conflict with a user's similar hacks but probably worth waiting for that to be an issue :)
jpienaar
pushed a commit
that referenced
this pull request
May 1, 2023
One step towards enabling [ccache](https://ccache.dev/) on our Windows CI, but there are a few details to still work through: #11009 (comment). On my machine, I see these results (sample size 1): > clean build (no cache): 528 seconds > ``` > λ ccache --show-stats > Cacheable calls: 3942 / 3943 (99.97%) > Hits: 2 / 3942 ( 0.05%) > Direct: 0 / 2 ( 0.00%) > Preprocessed: 2 / 2 (100.0%) > Misses: 3940 / 3942 (99.95%) > Uncacheable calls: 1 / 3943 ( 0.03%) > Local storage: > Cache size (GB): 2.21 / 5.00 (44.21%) > Cleanups: 16 > ``` > clean build (with cache): 96 seconds > ``` > λ ccache --show-stats > Cacheable calls: 3942 / 3943 (99.97%) > Hits: 3939 / 3942 (99.92%) > Direct: 3939 / 3939 (100.0%) > Preprocessed: 0 / 3939 ( 0.00%) > Misses: 3 / 3942 ( 0.08%) > Uncacheable calls: 1 / 3943 ( 0.03%) > Local storage: > Cache size (GB): 2.21 / 5.00 (44.23%) > ``` My only changes to enable ccache were: * Download ccache.exe and put it on my `PATH` * Configure CMake with `-DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache` (added to `"cmake.configureArgs": [ ... ]` in VSCode settings)
This was referenced Feb 19, 2025
ScottTodd
added a commit
to nod-ai/TheRock
that referenced
this pull request
Feb 20, 2025
Progress on #36. This fixes ccache when compiling with `-DCMAKE_BUILD_TYPE=RelWithDebInfo` and MSVC on Windows. Before: ``` λ ccache --show-stats Cacheable calls: 0 / 4309 ( 0.00%) Hits: 0 Direct: 0 Preprocessed: 0 Misses: 0 Uncacheable calls: 4309 / 4309 (100.0%) Local storage: Cache size (GB): 0.0 / 50.0 ( 0.00%) ``` After: ``` λ ccache --show-stats Cacheable calls: 4099 / 4309 (95.13%) Hits: 4054 / 4099 (98.90%) Direct: 3482 / 4054 (85.89%) Preprocessed: 572 / 4054 (14.11%) Misses: 45 / 4099 ( 1.10%) Uncacheable calls: 210 / 4309 ( 4.87%) Local storage: Cache size (GB): 4.2 / 50.0 ( 8.34%) Hits: 4054 / 4099 (98.90%) Misses: 45 / 4099 ( 1.10%) ``` We had a different workaround in IREE: iree-org/iree#11841. I tried a solution like that one in this project but the meta-project nature of TheRock discourages setting implicit top level options. Instead, I followed how other options like `CMAKE_CXX_COMPILER_LAUNCHER` are forwarded to subprojects explicitly. ### Debugging notes I followed https://ccache.dev/manual/4.10.2.html#_cache_debugging: ```bash ccache --set-config debug=true ccache --set-config debug_dir=D:\cache\ccache_debug ccache --show-config # confirm that the options are set ``` Then I looked in files like `D:\cache\ccache_debug\projects\TheRock\build\compiler\amd-llvm\build\lib\Support\CMakeFiles\LLVMSupport.dir\Allocator.cpp.obj.20250219_112722_308872.ccache-log` and found logs like these: ``` [2025-02-19T11:27:22.309172 28480] Command line: ccache C:\\PROGRA~2\\MICROS~2\\2022\\BUILDT~1\\VC\\Tools\\MSVC\\1442~1.344\\bin\\Hostx64\\x64\\cl.exe /nologo /TP -DGTEST_HAS_RTTI=0 -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_HAS_EXCEPTIONS=0 -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -ID:\\projects\\TheRock\\build\\compiler\\amd-llvm\\build\\lib\\Support -ID:\\projects\\TheRock\\compiler\\amd-llvm\\llvm\\lib\\Support -ID:\\projects\\TheRock\\build\\compiler\\amd-llvm\\build\\include -ID:\\projects\\TheRock\\compiler\\amd-llvm\\llvm\\include /DWIN32;/D_WINDOWS;/EHsc /DWIN32 /D_WINDOWS /Zc:inline /Zc:preprocessor /Zc:__cplusplus /Oi /bigobj /permissive- /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd5105 -wd4324 -w14062 -we4238 /Gw /O2 /Ob1 /DNDEBUG -std:c++17 -MD -Zi /EHs-c- /GR- /showIncludes /Folib\\Support\\CMakeFiles\\LLVMSupport.dir\\Allocator.cpp.obj /Fdlib\\Support\\CMakeFiles\\LLVMSupport.dir\\LLVMSupport.pdb /FS -c D:\\projects\\TheRock\\compiler\\amd-llvm\\llvm\\lib\\Support\\Allocator.cpp [2025-02-19T11:27:22.312459 28480] Hostname: DESKTOP-HTCE3IS [2025-02-19T11:27:22.312465 28480] Working directory: D:\projects\TheRock\build\compiler\amd-llvm\build [2025-02-19T11:27:22.312475 28480] Compiler: C:\PROGRA~2\MICROS~2\2022\BUILDT~1\VC\Tools\MSVC\1442~1.344\bin\Hostx64\x64\cl.exe [2025-02-19T11:27:22.312476 28480] Compiler type: msvc [2025-02-19T11:27:22.312846 28480] Detected input file: D:\projects\TheRock\compiler\amd-llvm\llvm\lib\Support\Allocator.cpp [2025-02-19T11:27:22.312852 28480] Compiler option -Zi is unsupported [2025-02-19T11:27:22.312857 28480] Failed; falling back to running the real compiler ``` From there it was whack-a-mole trying to find where the `-Zi` flag came from, checking source code and eventually finding https://github.com/llvm/llvm-project/blob/c0c42c8b3213520700f15587ab8aa4477a286ff9/cmake/Modules/CMakePolicy.cmake#L9-L20. Reading the docs informed me that my prior workaround of manipulating `CMAKE_C_FLAGS_RELWITHDEBINFO` is outdated and actually won't work when the new policy is enabled. With the right fix, I deleted my build directory, re-ran a full build, and checked the ccache stats and log files to ensure that ccache was operating as expected again.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
One step towards enabling ccache on our Windows CI, but there are a few details to still work through: #11009 (comment).
On my machine, I see these results (sample size 1):
My only changes to enable ccache were:
PATH-DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache(added to"cmake.configureArgs": [ ... ]in VSCode settings)