[Bug target/119386] New: [14/15 Regression][x64] Shared libraries can no longer be compiled with profiling

[sirl at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119386

            Bug ID: 119386
           Summary: [14/15 Regression][x64] Shared libraries can no longer
                    be compiled with profiling
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sirl at gcc dot gnu.org
  Target Milestone: ---

Hi,

compiling even the simplest code to a shared library with profiling is broken
since r14-811-bde21de1205c0456f6df68c950fb7ee631fcfa93 .

int f(int var)
{
  return var;
}

Compiled and linked like that:

# gcc-trunk -pg -W -Wall -fPIC -c test-shared-pg.c
# gcc-trunk -pg -shared -o libtest.so test-shared-pg.o 
/usr/x86_64-suse-linux/bin/ld: test-shared-pg.o: warning: relocation against
`mcount@@GLIBC_2.2.5' in read-only section `.text'
/usr/x86_64-suse-linux/bin/ld: test-shared-pg.o: relocation R_X86_64_PC32
against symbol `mcount@@GLIBC_2.2.5' can not be used when making a shared
object; recompile with -fPIC
/usr/x86_64-suse-linux/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

Compiling with -mno-direct-extern-access fixes it, but there is a fat warning
about mixing -mno-direct-extern-access and the default -mdirect-extern-access
in the manual.

In the bad case a naked "call mcount" is emitted, with
-mno-direct-extern-access or gcc-13 it's "call *mcount@GOTPCREL(%rip)".