Migration from Android.mk to cmake - linking problem

[Tsvetan Bogoev]

Hi, I have a problem while linking a release version of a shared library
using cmake (gradle/Android studio)
While using Android.mk everything is working as expected - I am compiling a
couple of static libraries using optimization level -Oz and LTO (-flto) and
the it links fine.
But when I switched to cmake I use the same compilation options the code
compiles but it can't be linked. Currently I can not find exact ld but it
gives the following error:

arm-linux-androideabi/bin/ld: fatal error: Optimization level must be
between 0 and 3
clang++: error: linker command failed with exit code 1 (use -v to see
invocation)
ninja: build stopped: subcommand failed.

I did not managed how to pass this "-v" options
here are some gradle arguments and global flags from gradle

externalNativeBuild {
cmake {
arguments "-DCMAKE_BUILD_TYPE=Release",
"-DANDROID_CPP_FEATURES=rtti exceptions",
"-DANDROID_STL=c++_static",
"-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON"
cppFlags "-v -ffunction-sections -fdata-sections
-fvisibility=hidden -fvisibility-inlines-hidden -flto"
cFlags "-v -ffunction-sections -fdata-sections
-fvisibility=hidden -fvisibility-inlines-hidden -flto"
}
}

Also I am not sure how to pass some options to linker only (like
-Wl,--exclude-libs=ALL -Wl,--gc-sections) - I tried this

list(APPEND ANDROID_LINKER_FLAGS "-Wl,--exclude-libs=ALL -Wl,--gc-sections
--verbose -flto")


I believe that there is something wrong with exact call to ld but since the
build does not print it I can not compare it with the some call while using
ndk-build/Andorid.mk

[Tsvetan Bogoev]

I am using r17b (also tried r17)

Post by Tsvetan Bogoev
Hi, I have a problem while linking a release version of a shared library
using cmake (gradle/Android studio)
While using Android.mk everything is working as expected - I am compiling
a couple of static libraries using optimization level -Oz and LTO (-flto)
and the it links fine.
But when I switched to cmake I use the same compilation options the code
compiles but it can't be linked. Currently I can not find exact ld but it
arm-linux-androideabi/bin/ld: fatal error: Optimization level must be
between 0 and 3
clang++: error: linker command failed with exit code 1 (use -v to see
invocation)
ninja: build stopped: subcommand failed.
I did not managed how to pass this "-v" options
here are some gradle arguments and global flags from gradle
externalNativeBuild {
cmake {
arguments "-DCMAKE_BUILD_TYPE=Release",
"-DANDROID_CPP_FEATURES=rtti exceptions",
"-DANDROID_STL=c++_static",
"-DCMAKE_VERBOSE_MAKEFILE:BOOL=ON"
cppFlags "-v -ffunction-sections -fdata-sections
-fvisibility=hidden -fvisibility-inlines-hidden -flto"
cFlags "-v -ffunction-sections -fdata-sections
-fvisibility=hidden -fvisibility-inlines-hidden -flto"
}
}
Also I am not sure how to pass some options to linker only (like
-Wl,--exclude-libs=ALL -Wl,--gc-sections) - I tried this
list(APPEND ANDROID_LINKER_FLAGS "-Wl,--exclude-libs=ALL
-Wl,--gc-sections --verbose -flto")
I believe that there is something wrong with exact call to ld but since
the build does not print it I can not compare it with the some call while
using ndk-build/Andorid.mk

[Tsvetan Bogoev]

I am using r17b (also tried r17)

[Tsvetan Bogoev]

I found what causes the problem, while using cmake ld is called with the
following options:
-plugin /home/myhome/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-
x86_64/bin/../lib64/LLVMgold.so
-plugin-opt=mcpu=generic
-plugin-opt=Os
-plugin-opt=-function-sections
-plugin-opt=-data-sections

when using ndk-build it looks like:
-plugin /home/tsvetan/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-
x86_64/bin/../lib64/LLVMgold.so
-plugin-opt=mcpu=generic

the "-plugin-opt=Os" is missing. So now I am trying to understand why cmake
passes this to ninja an thus link command fails

[Tsvetan Bogoev]

I found what causes the problem, while using cmake ld is called with the
following options:
-plugin /home/myhome/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-
x86_64/bin/../lib64/LLVMgold.so
-plugin-opt=mcpu=generic
-plugin-opt=Os
-plugin-opt=-function-sections
-plugin-opt=-data-sections

when using ndk-build it looks like:
-plugin /home/myhome/Android/Sdk/ndk-bundle/toolchains/llvm/prebuilt/linux-
x86_64/bin/../lib64/LLVMgold.so
-plugin-opt=mcpu=generic

the "-plugin-opt=Os" is missing. So now I am trying to understand why cmake
passes this to ninja an thus link command fails