_testembed.c warning: Programs/_testembed.gcda profile count data file not found

[utkonos]

Bug report

Bug description:

gcc -shared  -flto=auto -fno-semantic-interposition -flto -fuse-linker-plugin -ffat-lto-objects -g   Modules/cjkcodecs/_codecs_hk.o   -o Modules/_codecs_hk.cpython-314-x86_64-linux-gnu.so
    default: ./Programs/_testembed.c: In function ‘main’:
    default: ./Programs/_testembed.c:2472:1: warning: ‘/tmp/Python-3.14.0/Programs/_testembed.gcda’ profile count data file not found [-Wmissing-profile]
    default:  2472 | }
    default:       | ^

CPython versions tested on:

3.14

Operating systems tested on:

Linux

[picnixz]

Usually, a make clean helps with this kind of issue. I think it also happens when one has once used PGO, changed something, then recompile. I also see those kind of build warnings but I don't remember the exact steps I usually do to reproduce them.

[utkonos]

@picnixz This is on an absolutely clean build. I am using Vagrant and downloading the Python tgz, extracting it, and building all in a freshly spun up Ubuntu LTS 24.04 image. The image is an official one from here: https://cloud-images.ubuntu.com/noble/

[picnixz]

What are the configure options you are using? Could you produce the full commands from the moment you unpacked the archive to the end of the make command? Also, what is the gcc version?

[utkonos]

Here are the commands:

./configure --enable-optimizations --with-lto
export CFLAGS="-flto=auto"
export LDFLAGS="-flto=auto"
make -j $(nproc)

GCC:

# gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-linux-gnu/13/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Ubuntu 13.3.0-6ubuntu2~24.04' --with-bugurl=file:///usr/share/doc/gcc-13/README.Bugs --enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr --with-gcc-major-version-only --program-suffix=-13 --program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id --libexecdir=/usr/libexec --without-included-gettext --enable-threads=posix --libdir=/usr/lib --enable-nls --enable-bootstrap --enable-clocale=gnu --enable-libstdcxx-debug --enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new --enable-libstdcxx-backtrace --enable-gnu-unique-object --disable-vtable-verify --enable-plugin --enable-default-pie --with-system-zlib --enable-libphobos-checking=release --with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch --disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64 --with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic --enable-offload-targets=nvptx-none=/build/gcc-13-fG75Ri/gcc-13-13.3.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-13-fG75Ri/gcc-13-13.3.0/debian/tmp-gcn/usr --enable-offload-defaulted --without-cuda-driver --enable-checking=release --build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu --with-build-config=bootstrap-lto-lean --enable-link-serialization=2
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 13.3.0 (Ubuntu 13.3.0-6ubuntu2~24.04)

[picnixz]

I am not entirely sure we support custom CFLAGS/LDFLAGS after running configure especially for the LTO build. cc @corona10

(I need to go now because it is 2 AM)

[corona10]

I will take a look at this weekend

[utkonos]

@picnixz The _testembed.c warning happens regardless of whether those two lines are there or not. I have run the build with and without those two and this is still there.

[vstinner]

I can reproduce the warning with these commands:

./configure --enable-optimizations --with-lto
export CFLAGS="-flto=auto"
export LDFLAGS="-flto=auto"
make -j $(nproc)

In Makefile, PROFILE_TASK= -m test --pgo --timeout=$(TESTTIMEOUT) doesn't run ./Programs/_testembed: test_embed is excluded by --pgo option (see ./python -m test --pgo --list-tests output).

Well, it's just a warning. ./Programs/_testembed is only used by tests (test_embed), it doesn't have to be optimized.

You can safely ignore this warning. I don't think that anything should be done here. I suggest closing the issue.

[vstinner]

I close the issue.