Nios II CALL26 linker relaxation

2014-01-30  Sandra Loosemore  <sandra@codesourcery.com>

	bfd/
	* bfd-in2.h: Update from reloc.c.
	* elf32-nios2.c: Include elf32-nios2.h.
	(elf_nios2_howto_table_rel): Add entry for R_NIOS2_CALL26_NOAT.
	(nios2_reloc_map): Likewise.
	(enum elf32_nios2_stub_type): Declare.
	(struct elf32_nios2_stub_hash_entry): Declare.
	(nios2_stub_hash_entry, nios2_stub_hash_lookup): New macros.
	(struct elf32_nios2_link_hash_entry): Add hsh_cache field.
	(struct elf32_nios2_link_hash_table): Add new fields bstab,
	stub_bfd, add_stub_section, layout_sections_again, stub_group,
	bfd_count, top_index, input_list, all_local_syms.
	(nios2_call26_stub_entry): New.
	(nios2_elf32_install_imm16): Move up in file.
	(nios2_elf32_install_data): Move up in file.
	(hiadj): Move up in file.
	(stub_hash_newfunc): New.
	(link_hash_newfunc): Initialize hsh_cache field.
	(STUB_SUFFIX): New.
	(nios2_stub_name): New.
	(nios2_get_stub_entry): New.
	(nios2_add_stub): New.
	(nios2_elf32_setup_section_lists): New.
	(nios2_elf32_next_input_section): New.
	(CALL26_SEGMENT): New.
	(MAX_STUB_SECTION_SIZE): New.
	(group_sections): New.
	(nios2_type_of_stub): New.
	(nios2_build_one_stub): New.
	(nios2_size_one_stub): New.
	(get_local_syms): New.
	(nios2_elf32_size_stubs): New.
	(nios2_elf32_build_stubs): New.
	(nios2_elf32_do_call26_relocate): Correct CALL26 overflow test.
	(nios2_elf32_relocate_section): Handle R_NIOS2_CALL26_NOAT.  Add
	trampolines for R_NIOS2_CALL26 stubs.
	(nios2_elf32_check_relocs): Handle R_NIOS2_CALL26_NOAT.
	(nios2_elf32_gc_sweep_hook): Likewise.
	(nios2_elf32_link_hash_table_create): Initialize the stub hash table.
	(nios2_elf32_link_hash_table_free): New.
	(bfd_elf32_bfd_link_hash_table_free): Define.
	* elf32-nios2.h: New file.
	* libbfd.h: Update from reloc.c.
	* reloc.c (BFD_RELOC_NIOS2_CALL26_NOAT): New.

	gas/
	* config/tc-nios2.c (md_apply_fix): Handle BFD_RELOC_NIOS2_CALL26_NOAT.
	(nios2_assemble_args_m): Likewise.
	(md_assemble): Likewise.

	gas/testsuite/
	* gas/nios2/call26_noat.d: New.
	* gas/nios2/call26_noat.s: New.
	* gas/nios2/call_noat.d: New.
	* gas/nios2/call_noat.s: New.

	include/elf/
	* nios2.h (elf_nios2_reloc_type): Add R_NIOS2_CALL26_NOAT.

	ld/
	* Makefile.am (enios2elf.c, enios2linux.c): Update dependencies.
	* Makefile.in: Regenerated.
	* emulparams/nios2elf.sh (EXTRA_EM_FILE): Set.
	* emulparams/nios2linux.sh (EXTRA_EM_FILE): Set.
	* emultempl/nios2elf.em: New file.
	* gen-doc.texi (NIOSII): Set.
	* ld.texinfo (NIOSII): Set.

	ld/testsuite/
	* ld-nios2/relax_call26.s: New.
	* ld-nios2/relax_call26_boundary.ld: New.
	* ld-nios2/relax_call26_boundary.s: New.
	* ld-nios2/relax_call26_boundary_c8.d: New.
	* ld-nios2/relax_call26_boundary_cc.d: New.
	* ld-nios2/relax_call26_boundary_d0.d: New.
	* ld-nios2/relax_call26_boundary_d4.d: New.
	* ld-nios2/relax_call26_boundary_d8.d: New.
	* ld-nios2/relax_call26_boundary_dc.d: New.
	* ld-nios2/relax_call26_boundary_f0.d: New.
	* ld-nios2/relax_call26_boundary_f4.d: New.
	* ld-nios2/relax_call26_boundary_f8.d: New.
	* ld-nios2/relax_call26_boundary_fc.d: New.
	* ld-nios2/relax_call26_cache.d: New.
	* ld-nios2/relax_call26_cache.ld: New.
	* ld-nios2/relax_call26_cache.s: New.
	* ld-nios2/relax_call26_multi.d: New.
	* ld-nios2/relax_call26_multi.ld: New.
	* ld-nios2/relax_call26_norelax.d: New.
	* ld-nios2/relax_call26_shared.d: New.
	* ld-nios2/relax_call26_shared.ld: New.

1 files changed, 44 insertions, 0 deletions

diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index a8e5ea69a7a..1287a6cc180 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -30,6 +30,7 @@
 @set MMIX
 @set MSP430
 @set NDS32
+@set NIOSII
 @set POWERPC
 @set POWERPC64
 @set Renesas
@@ -1605,6 +1606,9 @@ This option is only supported on a few targets.
 @ifset M68HC11
 @xref{M68HC11/68HC12,,@command{ld} and the 68HC11 and 68HC12}.
 @end ifset
+@ifset NIOSII
+@xref{Nios II,,@command{ld} and the Altera Nios II}.
+@end ifset
 @ifset POWERPC
 @xref{PowerPC ELF32,,@command{ld} and PowerPC 32-bit ELF Support}.
 @end ifset
@@ -6105,6 +6109,9 @@ functionality are not listed.
 @ifset NDS32
 * NDS32::			@command{ld} and NDS32
 @end ifset
+@ifset NIOSII
+* Nios II::			@command{ld} and the Altera Nios II
+@end ifset
 @ifset POWERPC
 * PowerPC ELF32::		@command{ld} and PowerPC 32-bit ELF Support
 @end ifset
@@ -6743,6 +6750,43 @@ Avoid generating the IFC instruction inside the loop.
 @end ifclear
 @end ifset
 
+@ifset NIOSII
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node Nios II
+@section @command{ld} and the Altera Nios II
+@cindex Nios II call relaxation
+@kindex --relax on Nios II
+
+Call and immediate jump instructions on Nios II processors are limited to
+transferring control to addresses in the same 256MB memory segment,
+which may result in @command{ld} giving
+@samp{relocation truncated to fit} errors with very large programs.
+The command-line option @option{--relax} enables the generation of
+trampolines that can access the entire 32-bit address space for calls
+outside the normal @code{call} and @code{jmpi} address range.  These
+trampolines are inserted at section boundaries, so may not themselves
+be reachable if an input section and its associated call trampolines are
+larger than 256MB.
+
+The @option{--relax} option is enabled by default unless @option{-r}
+is also specified.  You can disable trampoline generation by using the
+@option{--no-relax} linker option.  You can also disable this optimization
+locally by using the @samp{set .noat} directive in assembly-language
+source files, as the linker-inserted trampolines use the @code{at}
+register as a temporary.
+
+Note that the linker @option{--relax} option is independent of assembler
+relaxation options, and that using the GNU assembler's @option{-relax-all}
+option interferes with the linker's more selective call instruction relaxation.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
 @ifset POWERPC
 @ifclear GENERIC
 @raisesections