LTO and error adding symbols: archive has no index; run ranlib to add one

[70311826-e6d8-4d29-8604-c4ec4bfa7f0d]

Bugzilla Link	42684
Version	trunk
OS	Linux
CC	@DougGregor,@noloader,@zygoloid,@yuanfang-chen

Extended Description

We are trying to document the process of using Link Time Optimizations (LTO) at https://www.cryptopp.com/wiki/Link_Time_Optimization. Attempting to use -flto results in the following during link (we drive link through the compiler):

$ CXX=clang++ CXXFLAGS="-DNDEBUG -O2 -flto -g -fPIC -pthread" make -j 4 ... clang++ -o cryptest.exe -DNDEBUG -O2 -flto -g -fPIC -pthread -DCRYPTOPP_DISABLE_MIXED_ASM -pipe adhoc.o test.o bench1.o bench2.o bench3.o datatest.o dlltest.o fipsalgt.o validat0.o validat1.o validat2.o validat3.o validat4.o validat5.o validat6.o validat7.o validat8.o validat9.o validat10.o regtest1.o regtest2.o regtest3.o regtest4.o ./libcryptopp.a /bin/ld: ./libcryptopp.a: error adding symbols: archive has no index; run ranlib to add one clang-8: error: linker command failed with exit code 1 (use -v to see invocation) make: *** [GNUmakefile:1323: cryptest.exe] Error 1

---

Additionally, adding "AR=clang-ar" and "RANLIB=clang-ranlib" fails due to missing programs. This is a GCC convention, so I suppose it is not unexpected. However, using GCC's tools produces the same errors:

$ AR=gcc-ar RANLIB=gcc-ranlib CXX=clang++ CXXFLAGS="-DNDEBUG -O2 -flto -g -fPIC -pthread" make -j 4 ... /bin/ar: creating libcryptopp.a gcc-ranlib libcryptopp.a clang++ -o cryptest.exe ... ./libcryptopp.a /bin/ld: ./libcryptopp.a: error adding symbols: archive has no index; run ranlib to add one clang-8: error: linker command failed with exit code 1 (use -v to see invocation) make: *** [GNUmakefile:1323: cryptest.exe] Error 1

I don't know why we are getting messages like "/bin/ar: creating libcryptopp.a". Our makefile honors AR, ARFLAGS, RANLIB, CXX, CXXFLAGS, etc. We don't use LD since we drive link through the compiler. Everything is override-able by the user.

---

I'm working on Fedora 30 x86_64 (fully updated).

$ uname -a Linux skylake 5.1.17-300.fc30.x86_64 #​1 SMP Wed Jul 10 15:20:27 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

Here are the installed clang packages:

$ rpm -qa | grep -i -E 'llvm|clang' clang-tools-extra-8.0.0-1.fc30.x86_64 llvm-libs-8.0.0-6.fc30.x86_64 clang-8.0.0-1.fc30.x86_64 clang-libs-8.0.0-1.fc30.x86_64

[yuanfang-chen]

Additionally, adding "AR=clang-ar" and "RANLIB=clang-ranlib" fails due to missing programs.

There are llvm-ar and llvm-ranlib as GCC counterparts.

[llvmbot]

clang-10/unknown,now 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 amd64 [installed] libclang-10-dev/unknown,now 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 amd64 [installed]

also

7z e /usr/lib/llvm-10/lib/libclangCodeGen.a BackendUtil.cpp.o

file BackendUtil.cpp.o BackendUtil.cpp.o: LLVM IR bitcode

[llvmbot]

ld: /usr/lib/llvm-10/lib/libclangCodeGen.a: error adding symbols: archive has no index; run ranlib to add one

Using the packages from apt.llvm.org, the distro is Ubuntu eoan

The versions are:

llvm-10-dev/unknown,now 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 amd64 [installed] llvm-10-doc/unknown,unknown 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 all llvm-10-examples/unknown,unknown 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 all llvm-10-runtime/unknown,now 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 amd64 [installed,automatic] llvm-10-tools/unknown,now 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 amd64 [installed] llvm-10/unknown,now 1:10~+201911052151040800092452d402d-1~exp1~20191106072627.8 amd64 [installed]