On Mon, Jun 4, 2012 at 11:08 PM, Eric Botcazou <ebotca...@adacore.com> wrote:
>> Hmm, Mach-O does have BSS.
>
> OK, bad memory, this was for Tru64.
Could it be that there is a bug in the way .bss section selection
works? Looking through the documentation, it seems actually rather
hard to miss the .bss section:
@defmac BSS_SECTION_ASM_OP
If defined, a C expression whose value is a string, including spacing,
containing the assembler operation to identify the following data as
uninitialized global data. If not defined, and
@code{ASM_OUTPUT_ALIGNED_BSS} not defined,
uninitialized global data will be output in the data section if
@option{-fno-common} is passed, otherwise @code{ASM_OUTPUT_COMMON} will be
used.
@end defmac
The definition of have_global_bss_p() is this:
The following targets have no re-definition of BSS_SECTION_ASM_OP and
no definition of ASM_OUTPUT_ALIGNED_BSS
-bfin
-cris
-iq2000
-mcore
-mips
-mmix
-moxie
-pdp11
-vax
The following of those targets seem to inherit
TARGET_HAVE_SWITCHABLE_BSS_SECTIONS from config/elfos.h:
-bfin (elf only)
-cris (for cris-*-elf only)
-iq2000 (elf only)
-mcore (elf only)
-mips (seems to be elf only, too?!)
-moxie (elf only)
That leaves pdp11, vax, and non-ELF cris as the only targets without
.bss support. AFAICT, that is :-)
Eric, do you remember a test case that was the reason for the patch
that added this to utils.c? I would like to play with it, and see if I
can understand why apparently the data didn't end up in a .bss
section.
Ciao1
Steven
