I reckon it's quite OK to write &p->field in C when p might be NULL,
and lots of old C programmers probably agree with me. However, ubsan
disagrees and so do some people I respect. I suspect C++ influence is
to blame for the ubsan behaviour. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92634. So far no one has
educated me as to why I'm wrong to claim that there isn't anything in
the C standard to say that p->field is always (*p).field. Note 79
doesn't quite do that because it doesn't cover null pointers. If
there was such an equivalence then you could claim &p->field has a
null pointer reference when p is NULL, even though no C compiler would
ever dereference p.
Anyway, to silence ubsan I'm going to apply the following though I
prefer to avoid casts when possible. And I'm using (void *)
deliberately because this is C, not C++!
* ldlang.c (lang_output_section_find_by_flags): Don't use &p->field
when p might be NULL.
* ldelf.c (output_rel_find, ldelf_place_orphan): Likewise.
(insert_os_after, lang_insert_orphan, lookup_name): Likewise.
(strip_excluded_output_sections, lang_clear_os_map): Likewise.
(lang_check, lang_for_each_input_file): Likewise.
(lang_reset_memory_regions, find_replacements_insert_point): Likewise.
(find_rescan_insertion, lang_propagate_lma_regions): Likewise.
(lang_record_phdrs): Likewise.
* emultempl/alphaelf.em (alpha_after_open): Likewise.
* emultempl/mmo.em (mmo_place_orphan): Likewise.
* emultempl/pe.em (gld_${EMULATION_NAME}_place_orphan): Likewise.
* emultempl/pep.em (gld_${EMULATION_NAME}_place_orphan): Likewise.
* emultempl/ppc32elf.em (ppc_after_check_relocs): Likewise.
* emultempl/spuelf.em (spu_before_allocation): Likewise.
(embedded_spu_file): Likewise.
The idea is to make it a little easier to find uses of this list,
so searches don't hit occurrences of lang_output_section_statement_type
and lang_output_section_statement_enum.
* ldlang.h (lang_os_list): Rename from lang_output_section_statement.
* ldlang.c: Likewise throughout file.
* emultempl/alphaelf.em: Likewise.
* emultempl/elf32.em: Likewise.
* emultempl/mmo.em: Likewise.
* emultempl/pe.em: Likewise.
* emultempl/pep.em: Likewise.
* emultempl/ppc32elf.em: Likewise.
* emultempl/spuelf.em: Likewise.
ld/
* emultempl/alphaelf.em (alpha_after_parse): Enable 2 relax passes.
bfd/
* elf64-alpha.c (elf64_alpha_size_got_sections): New may_merge
parameter; honor it and disable got merging when false.
(elf64_alpha_relax_got_load): Do not relax to GPREL relocs during
the first pass of relaxation.
(elf64_alpha_relax_with_lituse): Likewise. Move relaxed relocs to
the end of the LITERAL+LITUSE chain.
(elf64_alpha_relax_section): Only process LITERAL relocs during the
second pass of relaxation.
* ld.h (struct args_type): Rename 'relax' field to
'disable_target_specific_optimizations' and turn it into a
tri-state variable.
(RELAXATION_DISABLED_BY_DEFAULT): New macro.
(RELAXATION_DISABLED_BY_USER): New macro.
(RELAXATION_ENABLED): New macro.
(DISABLE_RELAXATION): New macro.
(ENABLE_RELAXATION): New macro.
* lexsup (enum option_values): Add OPTION_NO_RELAX.
(struct ld_options): Add --no-relax.
(parse_args): Handle OPTION_NO_RELAX. Use DISABLE_RELAXATION and
ENABLE_RELAXATION macros.
* ldlang.c (lang_relax_sections): Use RELAXATION_ENABLED macro.
(lang_process): Likewise.
* ldmain.c (main): Initialise
disable_target_specific_optimizations field.
(multiple_definition): Use RELAXATION_ENABLED macro.
* ld.texinfo: Document new command line option.
* emultempl/alphaelf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_DISABLED_BY_USER macro.
Use ENABLE_RELAXATION macro.
* emultempl/avrelf.em: (after_allocation): Test RELAXATION_ENABLED
macro.
* emultempl/cr16elf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_DISABLED_BY_USER macro.
Use ENABLE_RELAXATION macro.
* emultempl/crxelf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_DISABLED_BY_USER macro.
Use ENABLE_RELAXATION macro.
* emultempl/mmix-elfnmmo.em: (before_allocation): Use
ENABLE_RELAXATION macro.
* emultempl/needrelax.em: (before_allocation): Use
ENABLE_RELAXATION macro.
* emultempl/ppc32elf.em: (before_allocation): Test
RELAXATION_DISABLED_BY_DEFAULT macro. Use
ENABLE_RELAXATION macro.
* emultempl/sh64elf.em: (before_allocation): Test
RELAXATION_ENABLED macro. Use DISABLE_RELAXATION macro.
* emultempl/xtensaelf.em: Remove --no-relax option.
(before_allocation): Test RELAXATION_ENABLED macro.
Use ENABLE_RELAXATION macro.