This is an archive of the discontinued LLVM Phabricator instance.

Make clang-cl able to self host on Windows ✿ヾ╲(｡◕‿◕｡)╱✿
ClosedPublic

Authored by zturner on Feb 22 2015, 11:08 PM.

Download Raw Diff

Details

Reviewers

chandlerc
majnemer
rnk

Commits

rGe13b76591e00: cmake: Don't do the libstdc++ version check when clang simulates MSVC
rL230239: cmake: Don't do the libstdc++ version check when clang simulates MSVC

Summary

CMake 3.x adds the notion of "simulated compilers" [1, 2]. CMAKE_CXX_COMPILER_ID will still report the actual compiler you're using, but it will set additional variables CMAKE_CXX_SIMULATE_ID and CMAKE_CXX_SIMULATE_VERSION. So, for example, if you set CC and CXX to clang-cl and run CMake while MSVC in your path (for example you've run vcvarsall), then CMAKE_CXX_SIMULATE_ID will get set to "MSVC", and CMAKE_CXX_SIMULATE_VERSION will get set to the value of -fms-compatibility-version.

With this patch and one more patch on the clang side to get -fms-compatibility-version to default to 18.00 instead of 17.00, I was able to compile with clang-cl with the following CMake invocation:

set CC=clang-cl.exe
set CXX=clang-cl.exe
cmake -G Ninja ..\..\llvm

I need to test this more exhaustively, and with CMake 2.8. I know CMake 2.8 doesn't support this, but I want to make sure it doesn't completely break the build. I also haven't completed a full build and run the test suite. But I was able to get ninja to [100/3000] with no major blowups before I stopped due to clang being so slow (I had installed a debug build). So this is promising, and I want to throw it up for discussion.

[1] http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=51ab85c3
[2] http://cmake.org/gitweb?p=cmake.git;a=commitdiff;h=3d8356d4

Diff Detail

Event Timeline

zturner updated this revision to Diff 20489.Feb 22 2015, 11:08 PM

zturner retitled this revision from to Make clang-cl able to self host on Windows ✿ヾ╲(｡◕‿◕｡)╱✿.

zturner updated this object.

zturner edited the test plan for this revision. (Show Details)

zturner added reviewers: rnk, chandlerc, majnemer.

zturner added a subscriber: Unknown Object (MLST).

yaron.keren added a subscriber: yaron.keren.Feb 22 2015, 11:48 PM

Thanks for looking into this!

With this patch and one more patch on the clang side to get -fms-compatibility-version to default to 18.00 instead of 17.00,

Yes, I think we should just bump the compatibility version now.

Nice! Looks good. Can we tweak the libstdc++ check instead, though? I think it makes more sense to come into the Clang branch in case we add more stuff there in the future.

-    if(NOT LLVM_ENABLE_LIBCXX)
+    if (CMAKE_CXX_SIMULATE_ID MATCHES "MSVC")
+      ...
+    elseif(NOT LLVM_ENABLE_LIBCXX)

This revision is now accepted and ready to land.Feb 23 2015, 9:53 AM

Closed by commit rL230239: cmake: Don't do the libstdc++ version check when clang simulates MSVC (authored by rnk). · Explain WhyFeb 23 2015, 11:09 AM

This revision was automatically updated to reflect the committed changes.

Revision Contents

Path

Size

cmake/

modules/

HandleLLVMOptions.cmake

6 lines

Diff 20489

cmake/modules/HandleLLVMOptions.cmake

Context not available.
	if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.7)	if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 4.7)
	message(FATAL_ERROR "Host GCC version must be at least 4.7!")	message(FATAL_ERROR "Host GCC version must be at least 4.7!")
	endif()	endif()
	elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")	elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND NOT (CMAKE_CXX_SIMULATE_ID MATCHES "MSVC") )
	if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.1)	if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS 3.1)
	message(FATAL_ERROR "Host Clang version must be at least 3.1!")	message(FATAL_ERROR "Host Clang version must be at least 3.1!")
	endif()	endif()
Context not available.
	message(WARNING "Host Visual Studio should at least be 2013 Update 4 (MSVC 18.0.31101)"	message(WARNING "Host Visual Studio should at least be 2013 Update 4 (MSVC 18.0.31101)"
	" due to miscompiles from earlier versions")	" due to miscompiles from earlier versions")
	endif()	endif()
		elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND CMAKE_CXX_SIMULATE_ID MATCHES "MSVC")
		if (CMAKE_CXX_SIMULATE_VERSION VERSION_LESS 18.0)
		message(FATAL_ERROR "Host Clang must have at least -fms-compatibility-version=18.0")
		endif()
	endif()	endif()
	endif()	endif()

Context not available.