[Bug other/37463] [4.4 regression] All Solaris/x86 eh tests fail

[ebotcazou at gcc dot gnu dot org]

------- Comment #13 from ebotcazou at gcc dot gnu dot org  2008-11-19 18:51 -------
> I'm a bit unsure how to test this right now: what I find is that C objects
> have read-only .eh_frame sections and use .cfi* directives, while C++, Java
> and Ada objects have read-write .eh_frame sections and still use .eh_frame
> sections directly emitted by the compiler.

The decision is made in dwarf2out_do_cfi_asm:

/* Decide whether to emit frame unwind via assembler directives.  */

int
dwarf2out_do_cfi_asm (void)
{
  int enc;

#ifdef MIPS_DEBUGGING_INFO
  return false;
#endif
  if (!flag_dwarf2_cfi_asm || !dwarf2out_do_frame ())
    return false;
  if (!eh_personality_libfunc)
    return true;
  if (!HAVE_GAS_CFI_PERSONALITY_DIRECTIVE)
    return false;

  /* Make sure the personality encoding is one the assembler can support.
     In particular, aligned addresses can't be handled.  */
  enc = ASM_PREFERRED_EH_DATA_FORMAT (/*code=*/2,/*global=*/1);
  if ((enc & 0x70) != 0 && (enc & 0x70) != DW_EH_PE_pcrel)
    return false;
  enc = ASM_PREFERRED_EH_DATA_FORMAT (/*code=*/0,/*global=*/0);
  if ((enc & 0x70) != 0 && (enc & 0x70) != DW_EH_PE_pcrel)
    return false;

  return true;
}

On Solaris with Sun ld, ASM_PREFERRED_EH_DATA_FORMAT is defined so that at
least one of the 2 tests will always return false.  Therefore the only way
to have dwarf2out_do_cfi_asm return true is

  if (!eh_personality_libfunc)
    return true;

The C++, Java and Ada compilers unconditionally register their personality
routine, whereas the C compiler doesn't, even with -fexceptions: if there
is no EH action in the code, it doesn't register it.  Hence the discrepancy.


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37463