Hi.
The patch is about better symbol table manipulation
for debug info objects. The patch fixes reported issue
on hppa64-hp-hpux11.11.
Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
Ready to be installed?
Thanks,
Martin
libiberty/ChangeLog:
2019-08-27 Martin Liska <mli...@suse.cz>
PR lto/91478
* simple-object-elf.c (simple_object_elf_copy_lto_debug_sections):
First find a WEAK HIDDEN symbol in symbol table that will be
preserved. Later, use the symbol name for all removed symbols.
---
libiberty/simple-object-elf.c | 71 +++++++++++++++++++++++------------
1 file changed, 48 insertions(+), 23 deletions(-)
diff --git a/libiberty/simple-object-elf.c b/libiberty/simple-object-elf.c
index 75159266596..b637e4b0c92 100644
--- a/libiberty/simple-object-elf.c
+++ b/libiberty/simple-object-elf.c
@@ -1366,30 +1366,17 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
return errmsg;
}
- /* If we are processing .symtab purge __gnu_lto_slim symbol
- from it and any symbols in discarded sections. */
+ /* If we are processing .symtab purge any symbols
+ in discarded sections. */
if (sh_type == SHT_SYMTAB)
{
unsigned entsize = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
shdr, sh_entsize, Elf_Addr);
unsigned strtab = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
shdr, sh_link, Elf_Word);
- unsigned char *strshdr = shdrs + (strtab - 1) * shdr_size;
- off_t stroff = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
- strshdr, sh_offset, Elf_Addr);
- size_t strsz = ELF_FETCH_FIELD (type_functions, ei_class, Shdr,
- strshdr, sh_size, Elf_Addr);
- char *strings = XNEWVEC (char, strsz);
- char *gnu_lto = strings;
+ size_t prevailing_name_idx = 0;
unsigned char *ent;
unsigned *shndx_table = NULL;
- simple_object_internal_read (sobj->descriptor,
- sobj->offset + stroff,
- (unsigned char *)strings,
- strsz, &errmsg, err);
- /* Find first '\0' in strings. */
- gnu_lto = (char *) memchr (gnu_lto + 1, '\0',
- strings + strsz - gnu_lto);
/* Read the section index table if present. */
if (symtab_indices_shndx[i - 1] != 0)
{
@@ -1404,6 +1391,41 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
(unsigned char *)shndx_table,
sidxsz, &errmsg, err);
}
+
+ /* Find a WEAK HIDDEN symbol which name we will use for removed
+ symbols. */
+ for (ent = buf; ent < buf + length; ent += entsize)
+ {
+ unsigned st_shndx = ELF_FETCH_FIELD (type_functions, ei_class,
+ Sym, ent,
+ st_shndx, Elf_Half);
+ unsigned char *st_info;
+ unsigned char *st_other;
+ if (ei_class == ELFCLASS32)
+ {
+ st_info = &((Elf32_External_Sym *)ent)->st_info;
+ st_other = &((Elf32_External_Sym *)ent)->st_other;
+ }
+ else
+ {
+ st_info = &((Elf64_External_Sym *)ent)->st_info;
+ st_other = &((Elf64_External_Sym *)ent)->st_other;
+ }
+ if (st_shndx == SHN_XINDEX)
+ st_shndx = type_functions->fetch_Elf_Word
+ ((unsigned char *)(shndx_table + (ent - buf) / entsize));
+
+ if (st_shndx != SHN_COMMON
+ && !(st_shndx != SHN_UNDEF
+ && st_shndx < shnum
+ && pfnret[st_shndx - 1] == -1)
+ && ELF_ST_BIND (*st_info) == STB_WEAK
+ && *st_other == STV_HIDDEN)
+ prevailing_name_idx = ELF_FETCH_FIELD (type_functions, ei_class,
+ Sym, ent,
+ st_name, Elf_Addr);
+ }
+
for (ent = buf; ent < buf + length; ent += entsize)
{
unsigned st_shndx = ELF_FETCH_FIELD (type_functions, ei_class,
@@ -1426,9 +1448,10 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
if (st_shndx == SHN_XINDEX)
st_shndx = type_functions->fetch_Elf_Word
((unsigned char *)(shndx_table + (ent - buf) / entsize));
- /* Eliminate all COMMONs - this includes __gnu_lto_v1
- and __gnu_lto_slim which otherwise cause endless
- LTO plugin invocation. */
+ /* Eliminate all COMMONs - this includes __gnu_lto_slim
+ which otherwise cause endless LTO plugin invocation.
+ FIXME: remove the condition once we remove emission
+ of __gnu_lto_slim symbol. */
if (st_shndx == SHN_COMMON)
discard = 1;
/* We also need to remove symbols refering to sections
@@ -1460,12 +1483,15 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
else
{
/* Make discarded global symbols hidden weak
- undefined and sharing the gnu_lto_ name. */
+ undefined and sharing a name of a prevailing
+ symbol. */
bind = STB_WEAK;
other = STV_HIDDEN;
+
ELF_SET_FIELD (type_functions, ei_class, Sym,
- ent, st_name, Elf_Word,
- gnu_lto - strings);
+ ent, st_name, Elf_Addr,
+ prevailing_name_idx);
+
ELF_SET_FIELD (type_functions, ei_class, Sym,
ent, st_shndx, Elf_Half, SHN_UNDEF);
}
@@ -1482,7 +1508,6 @@ simple_object_elf_copy_lto_debug_sections (simple_object_read *sobj,
ELF_SET_FIELD (type_functions, ei_class, Sym,
ent, st_shndx, Elf_Half, sh_map[st_shndx]);
}
- XDELETEVEC (strings);
XDELETEVEC (shndx_table);
}
else if (sh_type == SHT_GROUP)
