LLVMgold.dll is not found on android-ndk-r13b-windows

[Klayflash]

I'm attempting to add -flto for link-time optimization. Link fails with error:

LLVMgold.so: could not load plugin library: unable to load dll

*LLVMgold*.* file is absent in android-ndk-r13b-windows.

How can I use link time optimization on Windows?

NDK API level: 23
Compiler and linker: clang.exe

See also
#108

[DanAlbert]

Dup of #108

[Klayflash]

Please clarify. Is this issue has been fixed in android-ndk-r13b-windows ?

[DanAlbert]

No. Not fixed.

[Klayflash]

Will fix be available in next after android-ndk-r13b-windows?

[DanAlbert]

I'm going to reopen this so we can track Darwin and Windows separately, since they're probably not going to get fixed at the same time.

The short answer here is that this probably isn't going to be supported any time soon. Clang's LTO support currently only works on Linux. Darwin support seems to be nearly there, but I don't know if anyone has ever looked at Windows. We'll get it up and running on Darwin first since there's more demand for that (and it's likely the easier task as well since it's at least unix-like), but after that we can look at what it will take to support Windows.

[Klayflash]

This (https://www.crystax.net/en/android/ndk) lib contains LLVMgold.dll.
May be LLVMgold.dll is built because cross-build is used:

WARNING!!! Building the Windows version of CrystaX NDK is only supported on a Linux host (cross-build used). Building on a Windows host is not tested and not supported.

I hope this info will help to you. Thank you for a job.

[Klayflash]

I have built LLVMgold.dll on windows platform! It was not easy...

The batch file that I used to build LLVMgold.dll:

@echo off
rem download cmake tool and unpack into next line folder
set PATH=%PATH%;C:\temp\Buildgold\cmake-3.7.1-win64-x64\bin
rem download "LLVM source code" from http://llvm.org/releases/download.html#3.9.0 and unpack into next line folder
cd C:\temp\Buildgold\llvm-3.8.1.src
rem modify llvm-3.8.1.src\cmake\modules\HandleLLVMOptions.cmake: set LLVM_ENABLE_PLUGINS to ON
mkdir mybuilddir
cd mybuilddir
rem cmake 3.7.1 was used
cmake --version
IF ERRORLEVEL 1 goto error
cmake .. -G "Visual Studio 14 2015 Win64" -DPYTHON_EXECUTABLE=C:\lib\android\1\android-ndk-r13b-windows-x86_64\android-ndk-r13b\prebuilt\windows-x86_64\bin\python.exe -DLLVM_BINUTILS_INCDIR=C:\temp\Buildgold\binutils\include -DCMAKE_BUILD_TYPE=Release
IF ERRORLEVEL 1 goto error
cmake --build . --config Release --target LLVMgold
IF ERRORLEVEL 1 goto error
:success
echo "SUCCESS"
goto exit
:error
echo "ERROR!"
goto exit
:exit
pause

Steps:

1. I added "-flto" to clang compiler and same for clang linker.
2. run build. After build, expected error "could not load plugin library" is shown:

C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\llvm\prebuilt\windows-x86_64\bin/../lib64/LLVMgold.so: could not load plugin library: unable to load dll
C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\temp\myBuildDir\results\80_default.o:1:3: invalid character
C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\temp\myBuildDir\results\80_default.o:1:3: syntax error, unexpected $end

3. I added to folder this dll and rename, so full path is C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\llvm\prebuilt\windows-x86_64\lib64\LLVMgold.so
4. run build. After build, unexpected error "1:3: invalid character" is shown:

C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\temp\myBuildDir\results\80_default.o:1:3: invalid character
C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\temp\myBuildDir\results\80_default.o:1:3: syntax error, unexpected $end
C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\temp\myBuildDir\results\80_default.o: not an object or archive
C:\lib\android\2\android-ndk-r14-beta1-windows-x86_64\android-ndk-r14-beta1\toolchains\x86-4.9\prebuilt\windows-x86_64/lib/gcc/i686-linux-android/4.9.x/../../../../i686-linux-android/bin\ld: error: C:\temp\myBuildDir\results\28_default.o:1:3: invalid character

Why unexpected error is shown?

[stephenhines]

I don't think it is safe to build LLVMgold.dll from the 3.9 sources, since the Clang/LLVM it is linking against is most definitely not 3.9. It is likely that there are missing symbols or other incompatibilities here, so you will have to wait until we can rebuild the compiler with further patches to get the appropriate .dll file.

[DanAlbert]

LLVMgold.dll landed a few releases ago.