Re: [patch][gold][aarch64]Support ifunc, safe icf, TLSLD

[Cary Coutant <ccoutant at google dot com>]

> gold/ChangeLog:
>
> 2014-10-21  Han Shen  <shenhan@google.com>
>             Jing Yu   <jingyu@google.com>
>
>         * aarch64-reloc.def: Add LD_PREL_LO12, ADR_PREL_LO21,
>         TLSLD_ADR_PAGE21, TLSLD_ADD_LO12_NC, TLSLD_MOVW_DTPREL_G1,
>         TLSLD_MOVW_DTPREL_G0_NC. Change property of TLS relocations to
>         Symbol::TLS_REF.
>         * aarch64.cc (Target_aarch64::do_can_check_for_function_pointers): New
>         method.
>         (Target_aarch64::reloc_needs_plt_for_ifunc): New method.
>         (Target_aarch64::tls_ld_to_le): New method.
>         (Target_aarch64::aarch64_info): Enable can_icf_inline_merge_sections
>         for 64bit targets.
>         (Output_data_plt_aarch64::irelative_rel_): New data member.
>         (Output_data_plt_aarch64::add_entry): Add irelative entries to plt.
>         (Output_data_plt_aarch64::add_local_ifunc_entry): New method.
>         (Output_data_plt_aarch64::add_relocation): New method.
>         (Output_data_plt_aarch64::do_write): Add gold_assert on got_irelative
>         offset. Add got_irelative size to got size.
>         (AArch64_relocate_functions): Typedef AArch64_valtype. Replace long
>         type string with the new typename.
>         (AArch64_relocate_functions::update_adr): Replace parameter x with
>         immed.
>         (AArch64_relocate_functions::update_movnz): Correct wrong val mask.
>         (AArch64_relocate_functions::reloc_common): New method.
>         (AArch64_relocate_funcsions::rela_general): Extract common part out
>         into reloc_common method.
>         (AArch64_relocate_functions::rela_general): Likewise.
>         (AArch64_relocate_functions::pcrela_general): Likewise.
>         (AArch64_relocate_functions::adr): New method.
>         (AArch64_relocate_functions::adrp): Calculate immed before calling
>         update_adr.
>         (AArch64_relocate_functions::adrp): Likewise.
>         (AArch64_relocate_functions::movnz): Cast x to SignedW type when
>         comparing x to 0. Calculate immed from ~x when x < 0.
>         (Target_aarch64::optimize_tls_reloc): Add new cases for
>         TLSLD_ADR_PAGE21, TLSLD_ADD_LO12_NC, TLSLD_MOVW_DTPREL_G1,
>         TLSLD_MOVW_DTPREL_G0_NC.
>         (Target_aarch64::possible_function_pointer_reloc): Implement this
>         method.
>         (Target_aarch64::Scan::local_reloc_may_be_function_pointer): Update
>         comment.
>         (Target_aarch64::Scan::local): Add codes to handle STT_GNU_IFUNC
>         symbol. Add cases for TLSLD_ADR_PAGE21, TLSLD_ADD_LO12_NC,
>         TLSLD_MOVW_DTPREL_G1, TLSLD_MOVW_DTPREL_G0_NC.
>         (Target_aarch64::Scan::global): Add codes to handle STT_GNU_IFUNC
>         symbol. Add cases for TLSLD_ADR_PAGE21, TLSLD_ADD_LO12_NC,
>         TLSLD_MOVW_DTPREL_G1, TLSLD_MOVW_DTPREL_G0_NC.
>         (Target_aarch64::make_plt_entry): Call add_entry with two more
>         parameters.
>         (Target_aarch64::make_local_ifunc_plt_entry): New method.
>         (Target_aarch64::Relocate::relocate): Add cases for LD_PREL_LO19,
>         ADR_PREL_LO21, TLSLD_ADR_PAGE21, TLSLD_ADD_LO12_NC,
>         TLSLD_MOVW_DTPREL_G1, TLSLD_MOVW_DTPREL_G0_NC.
>         (Target_aarch64::Relocate::relocate_tls): Add cases for
>         TLSLD_ADR_PAGE21, TLSLD_ADD_LO12_NC, TLSLD_MOVW_DTPREL_G1,
>         TLSLD_MOVW_DTPREL_G0_NC.
>         * testsuite/icf_safe_so_test.cc: Correct test comment.
>         * testsuite/icf_safe_test.sh: Add AArch64 arch.

Just a couple of nits. This patch is OK with the fixes below. Thanks!

-cary


+  // Caculate (S + A) - address, update adr instruction.

"Calculate"

+  if (flags & Symbol::TLS_REF)
+    gold_error(_("%s: unsupported TLS reloc %s for IFUNC symbol"),
+       object->name().c_str(), arp->name().c_str());

Just wondering: should you return false in this case? Returning true
might result in a cascading error.

+    gold_assert(false);

(Several places) Prefer gold_unreachable().