I have upgraded my whole arch linux system today (12th May, 2022). gcc
was also upgraded from v11.2
to v12.1
. I tried compiling some of my programs with g++
(part of gcc
compiler collection) by the following command:
g++ -O3 -DNDEBUG -Os -Ofast -Og -s -march=native -flto -funroll-all-loops -std=c++20 main.cc -o ./main
The program compiled perfectly and ran as excepted without any errors, but I got a warning:
lto-wrapper: warning: using serial compilation of 2 LTRANS jobs
But, when the same program was compiled using v11.2
it produces zero number of errors and warnings.
My Questions:
- What is the meaning of this warning?
- How can I fix this?
- Is this warning occurred due to upgrading
gcc
version tov12.1
Here's the g++
configuration on my machine:
$ g++ -v
Using built-in specs.
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-pc-linux-gnu/12.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /build/gcc/src/gcc/configure --enable-languages=c,c++,ada,fortran,go,lto,objc,obj-c++ --enable-bootstrap --prefix=/usr --libdir=/usr/lib --libexecdir=/usr/lib --mandir=/usr/share/man --infodir=/usr/share/info --with-bugurl=https://bugs.archlinux.org/ --with-linker-hash-style=gnu --with-system-zlib --enable-__cxa_atexit --enable-cet=auto --enable-checking=release --enable-clocale=gnu --enable-default-pie --enable-default-ssp --enable-gnu-indirect-function --enable-gnu-unique-object --enable-linker-build-id --enable-lto --enable-multilib --enable-plugin --enable-shared --enable-threads=posix --disable-libssp --disable-libstdcxx-pch --disable-werror --with-build-config=bootstrap-lto --enable-link-serialization=1
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.1.0 (GCC)