[RFA] Fix gold's understanding of ARM v4T/v5T interworking

[Matthew Gretton-Dann]

Hi,

Whilst preparing a patch for gold to work around an issue on ARM1176 
CPUs (forthcoming) I noticed that gold doesn't correctly identify 
between v4T and v5T.  In particular:

   * It assumes BLX is available on v4T - it is not, BLX is only 
available from v5T.
   * It therefore assumes that using the availability of BLX is a good 
test for whether --fix-v4bx-interworking is also available.

The attached patch fixes these two issues by splitting the
Target_arm::may_use_blx() function into two:
   * Target_arm::may_use_v4t_interworking()
   * Target_arm::may_use_v5t_interworking()

The tests which previous checked may_use_blx() are then directed to use
one of the appropriate may_use_v#t_interworking queries.

I also ported some of the ld-arm/farcall* tests to gold in order to test 
these fixes.

Tested on arm-none-eabi.

Can someone please review?

Thanks,

Matt

gold/ChangeLog:

2011-09-20  Matthew Gretton-Dann<matthew.gretton-dann@arm.com>

   	* arm.cc (Target_arm::Target_arm): Remove initialisation of
	may_use_blx_
	(Target_arm::may_use_blx): Remove method.
	(Target_arm::set_may_use_blx): Likewise.
	(Target_arm::may_use_v4t_interworking): New method.
	(Target_arm::may_use_v5t_interworking): Likewise.
	(Target_arm::may_use_blx_): Remove member variable.
	(Arm_relocate_functions::arm_branch_common): Check for v5T
	interworking.
	(Arm_relocate_functions::thumb_branch_common): Likewise.
	(Reloc_stub::stub_type_for_reloc): Likewise.
	(Target_arm::do_finalize_sections): Correct interworking checks.
	* testsuite/Makefile.am: Add new tests.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/arm_farcall_arm_arm.s: New test.
	* testsuite/arm_farcall_arm_arm.sh: Likewise.
	* testsuite/arm_farcall_arm_thumb.s: Likewise.
	* testsuite/arm_farcall_arm_thumb.sh: Likewise.
	* testsuite/arm_farcall_thumb_arm.s: Likewise.
	* testsuite/arm_farcall_thumb_arm.sh: Likewise.
	* testsuite/arm_farcall_thumb_thumb.s: Likewise.
	* testsuite/arm_farcall_thumb_thumb.sh: Likewise.

-- 
Matthew Gretton-Dann
Principal Engineer, PD Software - Tools, ARM Ltd
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