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Fix bad interaction between --relax and tls optimisation 

Adding long-branch stubs for __tls_get_addr calls that are optimised
away is silly.  It also causes assertion failures on newer object files
that use R_PPC_TLSGD and R_PPC_TLSLD marker relocs, and half-optimised
(ie. broken) code for older object files.

	PR 16546
	* elf32-ppc.c (ppc_elf_relax_section): Don't build long-branch
	stubs for calls to __tls_get_addr that we know will later be
	optimised away.
This commit is contained in:
Alan Modra 2014-02-12 21:04:32 +10:30
parent 795bc6b3ea
commit 9f7552cff4
2 changed files with 62 additions and 0 deletions
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6
bfd/ChangeLog
View File

@ -1,3 +1,9 @@
2014-02-12 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (ppc_elf_relax_section): Don't build long-branch
stubs for calls to __tls_get_addr that we know will later be
optimised away.
2014-02-12 Alan Modra <amodra@gmail.com>
* elf32-ppc.c (ppc_elf_relax_section): Enable ppc476 workaround

56
bfd/elf32-ppc.c
View File

@ -6831,6 +6831,62 @@ ppc_elf_relax_section (bfd *abfd,
else
continue;
/* If this branch is to __tls_get_addr then we may later
optimise away the call. We won't be needing a long-
branch stub in that case. */
if (link_info->executable
&& !link_info->relocatable
&& h == htab->tls_get_addr
&& irel != internal_relocs)
{
unsigned long t_symndx = ELF32_R_SYM (irel[-1].r_info);
unsigned long t_rtype = ELF32_R_TYPE (irel[-1].r_info);
unsigned int tls_mask = 0;
/* The previous reloc should be one of R_PPC_TLSGD or
R_PPC_TLSLD, or for older object files, a reloc
on the __tls_get_addr arg setup insn. Get tls
mask bits from the symbol on that reloc. */
if (t_symndx < symtab_hdr->sh_info)
{
bfd_vma *local_got_offsets = elf_local_got_offsets (abfd);
if (local_got_offsets != NULL)
{
struct plt_entry **local_plt = (struct plt_entry **)
(local_got_offsets + symtab_hdr->sh_info);
char *lgot_masks = (char *)
(local_plt + symtab_hdr->sh_info);
tls_mask = lgot_masks[t_symndx];
}
}
else
{
struct elf_link_hash_entry *th
= elf_sym_hashes (abfd)[t_symndx - symtab_hdr->sh_info];
while (th->root.type == bfd_link_hash_indirect
|| th->root.type == bfd_link_hash_warning)
th = (struct elf_link_hash_entry *) th->root.u.i.link;
tls_mask
= ((struct ppc_elf_link_hash_entry *) th)->tls_mask;
}
/* The mask bits tell us if the call will be
optimised away. */
if ((tls_mask & TLS_TLS) != 0 && (tls_mask & TLS_GD) == 0
&& (t_rtype == R_PPC_TLSGD
|| t_rtype == R_PPC_GOT_TLSGD16
|| t_rtype == R_PPC_GOT_TLSGD16_LO))
continue;
if ((tls_mask & TLS_TLS) != 0 && (tls_mask & TLS_LD) == 0
&& (t_rtype == R_PPC_TLSLD
|| t_rtype == R_PPC_GOT_TLSLD16
|| t_rtype == R_PPC_GOT_TLSLD16_LO))
continue;
}
sym_type = h->type;
}