The following enables a hpux specific workaround for the WEAK UNDEF
symbols used by LTO debuginfo extraction. It makes sure to use
a special name (gnu_lto_v1) for those.
It also adjusts removed local symbols to not use UNDEFs (similar
to solaris ld for globals hpux doesn't like undefs it cannot resolve even
if they are unused). Instead it uses DEFS with NULL name.
I also fixed some readelf complaints about stale sh_info/link in
removed sections. (maybe that fixes the solaris complaints? ... just
having some christmas wishes ;))
LTO Bootstrapped and tested on x86_64-unknown-linux-gnu.
I've tested GNU ld and gold for a simple testcase exercising multiple
WEAK UNDEFs with the same name and local defs, they seem happy
(but they also retain all those local defs now in the partial link ... :/)
I'll probably see to implement "real" section removal in stage3 to
fix the Solaris complaints but I hope to not need reloc section
rewriting (aka really pruning stuff from the symtab).
If I hear back from John / Rainer about this patch (or Alan) I see
to commit this during the holidays when it is convenient.
Richard.
2017-12-19 Richard Biener <rguent...@suse.de>
PR lto/83452
* simple-object-elf.c (simple_object_elf_copy_lto_debug_section):
Do not use UNDEF locals for removed symbols but instead just
define them in the first prevailing section and with no name.
Use the same gnu_lto_v1 name for all removed globals we promote to
WEAK UNDEFs so hpux can use a stub to provide this symbol. Clear
sh_info and sh_link in removed sections.
Index: libiberty/simple-object-elf.c
===================================================================
--- libiberty/simple-object-elf.c (revision 255777)
+++ libiberty/simple-object-elf.c (working copy)
@@ -1091,6 +1091,7 @@ simple_object_elf_copy_lto_debug_section
int changed;
int *pfnret;
const char **pfnname;
+ unsigned first_shndx = 0;
shdr_size = (ei_class == ELFCLASS32
? sizeof (Elf32_External_Shdr)
@@ -1158,6 +1159,9 @@ simple_object_elf_copy_lto_debug_section
ret = (*pfn) (&name);
pfnret[i - 1] = ret == 1 ? 0 : -1;
pfnname[i - 1] = name;
+ if (first_shndx == 0
+ && pfnret[i - 1] == 0)
+ first_shndx = i;
}
/* Mark sections as preserved that are required by to be preserved
@@ -1327,6 +1331,15 @@ simple_object_elf_copy_lto_debug_section
sobj->offset + stroff,
(unsigned char *)strings,
strsz, &errmsg, err);
+ /* Find gnu_lto_ in strings. */
+ char *gnu_lto = strings;
+ while ((gnu_lto = memchr (gnu_lto, 'g',
+ strings + strsz - gnu_lto)))
+ if (strncmp (gnu_lto, "gnu_lto_v1",
+ strings + strsz - gnu_lto) == 0)
+ break;
+ else
+ gnu_lto++;
for (ent = buf; ent < buf + length; ent += entsize)
{
unsigned st_shndx = ELF_FETCH_FIELD (type_functions, ei_class,
@@ -1366,31 +1379,27 @@ simple_object_elf_copy_lto_debug_section
in case it is local. */
int bind = ELF_ST_BIND (*st_info);
int other = STV_DEFAULT;
- size_t st_name;
-
if (bind == STB_LOCAL)
- ELF_SET_FIELD (type_functions, ei_class, Sym,
- ent, st_name, Elf_Word, 0);
+ {
+ /* Make discarded local symbols unnamed and
+ defined in the first prevailing section. */
+ ELF_SET_FIELD (type_functions, ei_class, Sym,
+ ent, st_name, Elf_Word, 0);
+ ELF_SET_FIELD (type_functions, ei_class, Sym,
+ ent, st_shndx, Elf_Half, first_shndx);
+ }
else
{
+ /* Make discarded global symbols hidden weak
+ undefined and sharing the gnu_lto_ name. */
bind = STB_WEAK;
- st_name = ELF_FETCH_FIELD (type_functions, ei_class,
- Sym, ent, st_name,
- Elf_Word);
- if (st_name < strsz)
- {
- char *p = strings + st_name;
- if (p[0] == '_'
- && p[1] == '_'
- && strncmp (p + (p[2] == '_'),
- "__gnu_lto_", 10) == 0)
- {
- other = STV_HIDDEN;
- ELF_SET_FIELD (type_functions, ei_class, Sym,
- ent, st_name, Elf_Word,
- st_name + 2);
- }
- }
+ other = STV_HIDDEN;
+ if (gnu_lto)
+ ELF_SET_FIELD (type_functions, ei_class, Sym,
+ ent, st_name, Elf_Word,
+ gnu_lto - strings);
+ ELF_SET_FIELD (type_functions, ei_class, Sym,
+ ent, st_shndx, Elf_Half, SHN_UNDEF);
}
*st_other = other;
*st_info = ELF_ST_INFO (bind, STT_NOTYPE);
@@ -1398,8 +1407,6 @@ simple_object_elf_copy_lto_debug_section
ent, st_value, Elf_Addr, 0);
ELF_SET_FIELD (type_functions, ei_class, Sym,
ent, st_size, Elf_Word, 0);
- ELF_SET_FIELD (type_functions, ei_class, Sym,
- ent, st_shndx, Elf_Half, SHN_UNDEF);
}
}
XDELETEVEC (strings);
@@ -1422,6 +1429,10 @@ simple_object_elf_copy_lto_debug_section
link. */
ELF_SET_FIELD (type_functions, ei_class, Shdr,
shdr, sh_type, Elf_Word, SHT_NULL);
+ ELF_SET_FIELD (type_functions, ei_class, Shdr,
+ shdr, sh_info, Elf_Word, 0);
+ ELF_SET_FIELD (type_functions, ei_class, Shdr,
+ shdr, sh_link, Elf_Word, 0);
}
flags = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
