[Bug target/42081] big-endian arm MULTILIB_DEFAULTS hard-coded to little-endian

[tom at giftssoft dot com]

--- Comment #1 from tom at giftssoft dot com  2009-11-20 17:26 ---
It looks like this bug is related to bug 16350, which was created on 2004-07-03
and resulted in patch 800-arm-bigendian.patch being applied on 2007-11-07 to
gcc 4.3.0.  Prior to this patch, gcc defaulted to little-endian mode on both
big-endian and little-endian arm targets, and had to be explicitly told to
compile in big-endian mode.  This patch modified gcc to detault to big-endian
mode on big-endian arm targets and little-endian mode on littlr-endian arm
targets.  However, the hunk of the patch that replaced:

{ marm, mlittle-endian, mhard-float, mno-thumb-interwork }

with:

{ marm, TARGET_ENDIAN_OPTION, mhard-float, mno-thumb-interwork }

was somehow not applied.  Therefore, this bug can be restated as follows:  

The patch to resolve bug 16350 was only partially applied and resulted in an
inconsistent linux-elf.h file in which part of it still assumes little-endian
on all arm targets (the old behavor) and part of it assumes big-endian on
big-endian arm targets (the new behavior).



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42081

[Bug other/42081] New: big-endian arm MULTILIB_DEFAULTS hard-coded to little-endian

[tom at giftssoft dot com]

To whom it may concern:

In general, the logic of the gcc/config/arm/linux-elf.h file dictates that if
the target is big-endian arm, gcc will use big-endian defaults (like
-mbig_endian); otherwise, gcc will use little-endian defaults.  However, there
is apparently one exception to this rule.  MUTLILIB_DEFAULTS is hard-coded to
little-endian for both big-endian and little-endian arm:

#undef  MULTILIB_DEFAULTS
#define MULTILIB_DEFAULTS \
{ marm, mlittle-endian, mhard-float, mno-thumb-interwork }

To be to consistent with the rest of the header file, shouldn't this read:

#undef  MULTILIB_DEFAULTS
#if TARGET_BIG_ENDIAN_DEFAULT
#define MULTILIB_DEFAULTS \
{ marm, mbig-endian, mhard-float, mno-thumb-interwork }
#else
#define MULTILIB_DEFAULTS \
{ marm, mlittle-endian, mhard-float, mno-thumb-interwork }
#endif

or better yet:

#undef  MULTILIB_DEFAULTS
#define MULTILIB_DEFAULTS \
{ marm, TARGET_ENDIAN_OPTION, mhard-float, mno-thumb-interwork }


Otherwise, on a big-endian arm target in which multi-lib is enabled,
potentially some options would be set by default to big-endian, others to
little-endian, and the compiler would get confused.  At least that's how it
appears to me.

If this is by design rather than a minor bug that fell through the cracks (I
know that arm is natively little-endian, and thus there may be a reason to
always default it to little-endian in certain cases) please disregard this
message and close this bug report.  Thanks.

Regards,

Tom


-- 
   Summary: big-endian arm MULTILIB_DEFAULTS hard-coded to little-
endian
   Product: gcc
   Version: 4.5.0
Status: UNCONFIRMED
  Severity: minor
  Priority: P3
 Component: other
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tom at giftssoft dot com
GCC target triplet: arm*b-*-*


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42081