Corrupted profile header, while building coverage for PostgreSQL with `%p` in `LLVM_PROFILE_FILE`

[nataraj-hates-MS-for-stealing-github]

I am PostgreSQL developer, I am trying to build coverage for PosrtgreSQL tests with clang, and meet "corrupted profile header" error when I am using %p in LLVM_PROFILE_FILE.

How to reproduce:

git clone git://git.postgresql.org/git/postgresql.git -b REL_17_STABLE
cd postgres
CC=clang LD=clang CXX=clang++ CFLAGS="-fprofile-instr-generate -fcoverage-mapping" ./configure --enable-debug --enable-cassert --enable-tap-tests
make world-bin -j8
rm -rf `pwd`/../profile
mkdir `pwd`/../profile
LLVM_PROFILE_FILE=`pwd`/../profile/%p_%m.profraw make check-world
llvm-profdata merge -output=../merged.profdata ../profile/*

You will get error message like

warning: ../profile/559020_695054008901113306_0.profraw: invalid instrumentation profile data (file header is corrupt)
warning: ../profile/578083_695054008901113306_0.profraw: invalid instrumentation profile data (file header is corrupt)
warning: ../profile/558952_695054008901113306_0.profraw: invalid instrumentation profile data (file header is corrupt)
error: no profile can be merged

And your profile dir will be as large as 9Gb

After #123963 fix have been merged into main branch, you can replace %p with %b in LLVM_PROFILE_FILE variable, configure postgres with -Wl,--build-id added to CFLAGS, and will get profile dir as large as 7Mb, and you can build proper html coverage from it.

But still if you add %p to LLVM_PROFILE_FILE everything will stop working the same way, it did not work before. %p_%m_%b leads to same corrupted headers.

%p is not compatible with PostgreSQL tests somehow, and I guess this indicates to some problem that should be fixed.