fxregs.c undefined reference to __x86.get_pc_thunk.ax while building on CENTOS7

Reproduce the 32-bit build from 32/x86/fxregs.c on CentOS 7.8 with GCC 4.8.5, first using the reported configuration and then with disable32bit enabled for comparison. Inspect the inline assembly around the __x86.get_pc_thunk.ax call and verify that the 32-bit target links successfully without that undefined reference.

I tried building rr at commit b04220a6e66c2f9f47c9c953b928ce074bf6c075 on CENTOS 7.8 using gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44).

[ben@rr obj]$ cmake3 ../rr
-- The C compiler identification is GNU 4.8.5
-- The CXX compiler identification is GNU 4.8.5
-- The ASM compiler identification is GNU
-- Found assembler: /usr/lib64/ccache/cc
-- Check for working C compiler: /usr/lib64/ccache/cc
-- Check for working C compiler: /usr/lib64/ccache/cc - works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/lib64/ccache/c++
-- Check for working CXX compiler: /usr/lib64/ccache/c++ - works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Performing Test SUPPORTS_CXX14
-- Performing Test SUPPORTS_CXX14 - Failed
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.27.1") 
-- Checking for module 'capnp'
--   Found capnp, version 0.5.3.1
-- Found PythonInterp: /usr/bin/python3 (found suitable version "3.6.8", minimum required is "3") 
-- Configuring done
-- Generating done
-- Build files have been written to: /home/ben/rr/obj
[ben@rr obj]$ make
...
Scanning dependencies of target fxregs_32
[  5%] Building C object CMakeFiles/fxregs_32.dir/32/x86/fxregs.c.o
[  5%] Linking C executable bin/fxregs_32
CMakeFiles/fxregs_32.dir/32/x86/fxregs.c.o: In function `main':
/home/ben/rr/obj/32/x86/fxregs.c:64: undefined reference to `__x86.get_pc_thunk.ax'
collect2: error: ld returned 1 exit status
make[2]: *** [bin/fxregs_32] Error 1
make[1]: *** [CMakeFiles/fxregs_32.dir/all] Error 2
make: *** [all] Error 2
[ben@rr obj]$

It seems that fxregs.c is calling __x86.get_pc_thunk.ax , but it is not available.
Reading around, this seems to be provided by some versions of gcc, but it seems very unwise to depend on it.
Unfortunately I have not come to a good understanding of it.

From fxregs.c:

int main(void) {
  unsigned int eax, ecx, edx;
  unsigned int required_cpuid_flags = AVX_FEATURE_FLAG | OSXSAVE_FEATURE_FLAG;

  cpuid(CPUID_GETFEATURES, 0, &eax, &ecx, &edx);
  AVX_enabled = (ecx & required_cpuid_flags) == required_cpuid_flags;

  if (!AVX_enabled) {
    atomic_puts("AVX YMM registers disabled, not tested");
  }

  __asm__ __volatile__(
/* Push the constants in stack order so they look as
 * we expect in gdb. */
#if __i386__
      "call __x86.get_pc_thunk.ax\n\t"
      "addl $_GLOBAL_OFFSET_TABLE_, %eax\n\t"
      "fldl st7@GOTOFF(%eax)\n\t"
      "fldl st6@GOTOFF(%eax)\n\t"
      "fldl st5@GOTOFF(%eax)\n\t"
      "fldl st4@GOTOFF(%eax)\n\t"
      "fldl st3@GOTOFF(%eax)\n\t"
      "fldl st2@GOTOFF(%eax)\n\t"
      "fldl st1@GOTOFF(%eax)\n\t"
      "fldl st0@GOTOFF(%eax)\n\t"
      "movss xmm0@GOTOFF(%eax), %xmm0\n\t"
      "movss xmm1@GOTOFF(%eax), %xmm1\n\t"
      "movss xmm2@GOTOFF(%eax), %xmm2\n\t"
      "movss xmm3@GOTOFF(%eax), %xmm3\n\t"
      "movss xmm4@GOTOFF(%eax), %xmm4\n\t"
      "movss xmm5@GOTOFF(%eax), %xmm5\n\t"
      "movss xmm6@GOTOFF(%eax), %xmm6\n\t"
      "movss xmm7@GOTOFF(%eax), %xmm7\n\t"
#elif __x86_64__

It seems that the problem can be avoided by disabling 32 bit support:

[ben@rr obj]$ cmake3 ../rr -Ddisable32bit=ON

Unfortunately I still have a use for rr on 32 bit.

Can the dependence on __x86.get_pc_thunk.ax be removed from the 32 bit build?