pic patch for arm-elf

[Richard Earnshaw]

> This patch implements GC for GOT and PLT relocs in the elf32-arm
> backend.  One effect of this is to avoid a spurious R_ARM_NONE reloc
> which was blighting glibc by causing libc.so to be marked as
> DT_TEXTREL.  
> 
> It also replaces the code sequence used for PLT thunks with a more
> efficient version, which can make a significant difference on some
> processors.
> 
> May I check this in?
> 
> Thanks
> 
> p.
> 
> 
> 2003-10-26  Philip Blundell  <philb@gnu.org>
> 
> 	* elf32-arm.h (elf32_arm_plt0_entry, elf32_arm_plt_entry): New
> 	code sequence.
> 	(PLT_HEADER_SIZE): New.
> 	(struct elf32_arm_pcrel_relocs_copied): Rename to ...
> 	(struct elf32_arm_relocs_copied): ... this.  Count both
> 	pcrel and non-pcrel relocs.  All uses updated.
> 	(struct elf32_arm_link_hash_table): Add pointers to dynamic linker
> 	sections and symbol/section mapping cache.
> 	(create_got_section): New.
> 	(elf32_arm_create_dynamic_sections): New.
> 	(elf_backend_create_dynamic_sections): Use it.
> 	(elf32_arm_final_link_relocate): Support garbage collection of relocs.
> 	(elf32_arm_check_relocs): Likewise.
> 	(elf32_arm_adjust_dynamic_symbol): Likewise.
> 	(elf32_arm_copy_indirect_symbol): New.
> 	(elf32_arm_link_hash_table_create): Initialise new fields. 
> 	(elf32_arm_gc_sweep_hook): Implement.
> 	(elf32_arm_discard_copies): Delete.
> 	(elf32_arm_finish_dynamic_symbol): Use new PLT code.
> 	(elf32_arm_finish_dynamic_sections): Likewise.
> 	(elf_backend_can_refcount): Define.
> 	(elf_backend_copy_indirect_symbol): Likewise.
> 	(elf_backend_plt_header_size): Set to PLT_HEADER_SIZE.


OK.

I guess at some point we will want to GC the FOUR_WORD_PLT code, but I 
guess that for now it's wise to keep it in case there are deviant dynamic 
loaders around.

R.