Re: [PATCH v2 2/4] gold: Correctly get and put r_info for Mips64el.

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Jan 12, 2016 at 10:20 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Mon, Jan 11, 2016 at 7:01 PM, Cary Coutant <ccoutant@gmail.com> wrote:
>>> elfcpp/
>>>         * elfcpp.h (class Rel): Add new constructor.
>>>         (class Rel_write): Likewise.
>>>         (class Rela): Likewise.
>>>         (class Rela_write): Likewise.
>>>         (Rela::get_r_info): Correctly get r_info for Mips64 little endian.
>>>         (Rela_write::put_r_info): Correctly put r_info for Mips64 little endian.
>>>
>>> gold/
>>>         * gc.h (gc_process_relocs): Call new constructor for Reltype.
>>>         * target-reloc.h (scan_relocs): Likewise.
>>>         (relocate_section): Likewise.
>>>         (scan_relocatable_relocs): Likewise.
>>>         (relocate_relocs): Call new constructor for Reltype and for Reltype_write.
>>>         * target.h (Target::is_mips64el): New virtual function.
>>
>> I've taken a different approach. Rather than store a flag in the
>> elfcpp accessor class, which will have to be tested every time the
>> r_info field is accessed, I've extended the Classify_reloc interface
>> to provide methods for reading the r_sym and r_type fields. For the
>> templated routines in gc.h and target-reloc.h that use Classify_reloc
>> or Default_scan_relocatable_relocs, this allows us to provide the MIPS
>> accessor functions without a runtime check.
>>
>> The commit description and ChangeLog entry are copied below. The patch
>> is attached.
>>
>> -cary
>>
>>
>> For MIPS-64, the r_info field in the relocation format is
>> replaced by several individual fields, including r_sym and
>> r_type. To enable support for this format, I've refactored
>> target-independent code to remove almost all uses of the r_info
>> field. (I've left alone a couple of routines used only for
>> incremental linking, which I can update if/when the MIPS target
>> adds support for incremental linking.)
>>
>> For routines that are already templated on a Classify_reloc class
>> (namely, gc_process_relocs, relocate_section, and
>> relocate_relocs), I've extended the Classify_reloc interface to
>> include sh_type (which no longer needs to be a separate template
>> parameter) as well as get_r_sym() and get_r_type() methods for
>> extracting the r_sym and r_type fields. For
>> scan_relocatable_relocs, I've extended the
>> Default_scan_relocatable_relocs class by converting it to a class
>> template with Classify_reloc as a template parameter. For the
>> remaining routines that need to access r_sym, I've added a
>> virtual Target::get_r_sym() method with an override for the MIPS
>> target.
>>
>> In elfcpp, I've added Mips64_rel, etc., accessor classes and
>> corresponding internal data structures. The MIPS target uses
>> these new classes within its own Mips_classify_reloc class.
>> The Mips64_ accessor classes also expose the r_ssym, r_type2,
>> and r_type3 fields from the relocation.
>>
>> These changes should be functionally the same for all but the
>> MIPS target.
>>
>>
>> 2016-01-11  Cary Coutant  <ccoutant@gmail.com>
>>
>> elfcpp/
>>         * elfcpp.h (Mips64_rel, Mips64_rel_write): New classes.
>>         (Mips64_rela, Mips64_rela_write): New classes.
>>         * elfcpp_internal.h (Mips64_rel_data, Mips64_rela_data): New structs.
>>
>> gold/
>>         * gc.h (get_embedded_addend_size): Remove sh_type parameter.
>>         (gc_process_relocs): Remove sh_type template parameter.
>>         Use Classify_reloc to access r_sym, r_type, and r_addend fields.
>>         * object.h (Sized_relobj_file::split_stack_adjust): Add target
>>         parameter.
>>         (Sized_relobj_file::split_stack_adjust_reltype): Likewise.
>>         * reloc-types.h (Reloc_types::copy_reloc_addend): (SHT_REL and SHT_RELA
>>         specializations) Remove.
>>         * reloc.cc (Emit_relocs_strategy): Rename and move to target-reloc.h.
>>         (Sized_relobj_file::emit_relocs_scan): Call Target::emit_relocs_scan().
>>         (Sized_relobj_file::emit_relocs_scan_reltype): Remove.
>>         (Sized_relobj_file::split_stack_adjust): Add target parameter.
>>         Adjust all callers.
>>         (Sized_relobj_file::split_stack_adjust_reltype): Likewise. Call
>>         Target::get_r_sym() to get r_sym field from relocations.
>>         (Track_relocs::next_symndx): Call Target::get_r_sym().
>>         * target-reloc.h (scan_relocs): Remove sh_type template parameter;
>>         add Classify_reloc template parameter.  Use for accessing r_sym and
>>         r_type.
>>         (relocate_section): Likewise.
>>         (Default_classify_reloc): New class (renamed and moved from reloc.cc).
>>         (Default_scan_relocatable_relocs): Remove sh_type template parameter.
>>         (Default_scan_relocatable_relocs::Reltype): New typedef.
>>         (Default_scan_relocatable_relocs::reloc_size): New const.
>>         (Default_scan_relocatable_relocs::sh_type): New const.
>>         (Default_scan_relocatable_relocs::get_r_sym): New method.
>>         (Default_scan_relocatable_relocs::get_r_type): New method.
>>         (Default_emit_relocs_strategy): New class.
>>         (scan_relocatable_relocs): Replace sh_type template parameter with
>>         Scan_relocatable_relocs class.  Use it to access r_sym and r_type
>>         fields.
>>         (relocate_relocs): Replace sh_type template parameter with
>>         Classify_reloc class.  Use it to access r_sym and r_type fields.
>>         * target.h (Target::is_call_to_non_split): Replace r_type parameter
>>         with pointer to relocation. Adjust all callers.
>>         (Target::do_is_call_to_non_split): Likewise.
>>         (Target::emit_relocs_scan): New virtual method.
>>         (Sized_target::get_r_sym): New virtual method.
>>         * target.cc (Target::do_is_call_to_non_split): Replace r_type parameter
>>         with pointer to relocation.
>>
>>
>
> It breaks i686 gold:
>
> gcctestdir/ld: internal error in get_reloc_addend, at
> /export/gnu/import/git/sources/binutils-gdb/gold/reloc-types.h:49
> collect2: error: ld returned 1 exit status
> Makefile:5149: recipe for target 'icf_virtual_function_folding_test' failed
> make[7]: *** [icf_virtual_function_folding_test] Error 1
>

It breaks all REL targets.

-- 
H.J.