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[GOLD] PowerPC64 localentry:0 plt call optimization
- From: Alan Modra <amodra at gmail dot com>
- To: binutils at sourceware dot org
- Date: Wed, 21 Jun 2017 23:11:32 +0930
- Subject: [GOLD] PowerPC64 localentry:0 plt call optimization
- Authentication-results: sourceware.org; auth=none
Another patch to bring some ld.bfd capabilities to gold.
elfcpp/
* elfcpp.h (DT_PPC64_OPT): Define.
* powerpc.h (PPC64_OPT_TLS, PPC64_OPT_MULTI_TOC,
PPC64_OPT_LOCALENTRY): Define.
gold/
* options.h (General_options): Add plt_localentry.
* powerpc.cc (Target_powerpc::st_other): New function.
(Target_powerpc::plt_localentry0_, plt_localentry0_init_,
has_localentry0_): New vars.
(Target_powerpc::plt_localentry0, set_has_localentry0,
is_elfv2_localentry0): New functions.
(Target_powerpc::Branch_info::mark_pltcall): Don't set tocsave or
return true for localentry:0 calls.
(Stub_table::Plt_stub_ent::localentry0_): New var.
(Stub_table::add_plt_call_entry): Set localentry0_ and has_localentry0_.
Don't set r2save_ for localentry:0 calls.
(Output_data_glink::do_write): Save r2 in __glink_PLTresolve for elfv2.
(Target_powerpc::scan_relocs): Default plt_localentry0_.
(Target_powerpc::do_finalize_sections): Set DT_PPC64_OPT.
(Target_powerpc::Relocate::relocate): Don't require nop following
calls for localentry:0 plt calls, and don't change nop.
diff --git a/elfcpp/elfcpp.h b/elfcpp/elfcpp.h
index cce40d4..fa2f158 100644
--- a/elfcpp/elfcpp.h
+++ b/elfcpp/elfcpp.h
@@ -773,6 +773,9 @@ enum DT
DT_PPC64_OPD = 0x70000001,
DT_PPC64_OPDSZ = 0x70000002,
+ // Specify whether various optimisations are possible.
+ DT_PPC64_OPT = 0x70000003,
+
// The index of an STT_SPARC_REGISTER symbol within the DT_SYMTAB
// symbol table. One dynamic entry exists for every STT_SPARC_REGISTER
// symbol in the symbol table.
diff --git a/elfcpp/powerpc.h b/elfcpp/powerpc.h
index 99647bd..3dc0828 100644
--- a/elfcpp/powerpc.h
+++ b/elfcpp/powerpc.h
@@ -228,6 +228,14 @@ enum
EF_PPC64_ABI = 3
};
+// DT_PPC64_OPT bits
+enum
+{
+ PPC64_OPT_TLS = 1,
+ PPC64_OPT_MULTI_TOC = 2,
+ PPC64_OPT_LOCALENTRY = 4
+};
+
enum
{
// The ELFv2 ABI uses three bits in the symbol st_other field of a
diff --git a/gold/options.h b/gold/options.h
index 202d4b0..c7c032b 100644
--- a/gold/options.h
+++ b/gold/options.h
@@ -1104,6 +1104,10 @@ class General_options
N_("(PowerPC64 only) Align PLT call stubs to fit cache lines"),
N_("[=P2ALIGN]"), true, int, int, options::parse_uint, false);
+ DEFINE_bool(plt_localentry, options::TWO_DASHES, '\0', false,
+ N_("(PowerPC64 only) Optimize calls to ELFv2 localentry:0 functions"),
+ N_("(PowerPC64 only) Don't optimize ELFv2 calls"));
+
DEFINE_bool(plt_static_chain, options::TWO_DASHES, '\0', false,
N_("(PowerPC64 only) PLT call stubs should load r11"),
N_("(PowerPC64 only) PLT call stubs should not load r11"));
diff --git a/gold/powerpc.cc b/gold/powerpc.cc
index e102538..0c6dece 100644
--- a/gold/powerpc.cc
+++ b/gold/powerpc.cc
@@ -373,6 +373,12 @@ public:
set_abiversion(int ver);
unsigned int
+ st_other (unsigned int symndx) const
+ {
+ return this->st_other_[symndx];
+ }
+
+ unsigned int
ppc64_local_entry_offset(const Symbol* sym) const
{ return elfcpp::ppc64_decode_local_entry(sym->nonvis() >> 3); }
@@ -605,7 +611,9 @@ class Target_powerpc : public Sized_target<size, big_endian>
glink_(NULL), rela_dyn_(NULL), copy_relocs_(),
tlsld_got_offset_(-1U),
stub_tables_(), branch_lookup_table_(), branch_info_(), tocsave_loc_(),
- plt_thread_safe_(false), relax_failed_(false), relax_fail_count_(0),
+ plt_thread_safe_(false), plt_localentry0_(false),
+ plt_localentry0_init_(false), has_localentry0_(false),
+ relax_failed_(false), relax_fail_count_(0),
stub_group_size_(0), savres_section_(0)
{
}
@@ -1000,6 +1008,49 @@ class Target_powerpc : public Sized_target<size, big_endian>
plt_thread_safe() const
{ return this->plt_thread_safe_; }
+ bool
+ plt_localentry0() const
+ { return this->plt_localentry0_; }
+
+ void
+ set_has_localentry0()
+ {
+ this->has_localentry0_ = true;
+ }
+
+ bool
+ is_elfv2_localentry0(const Symbol* gsym) const
+ {
+ return (size == 64
+ && this->abiversion() >= 2
+ && this->plt_localentry0()
+ && gsym->type() == elfcpp::STT_FUNC
+ && gsym->is_defined()
+ && gsym->nonvis() >> 3 == 0);
+ }
+
+ bool
+ is_elfv2_localentry0(const Sized_relobj_file<size, big_endian>* object,
+ unsigned int r_sym) const
+ {
+ const Powerpc_relobj<size, big_endian>* ppc_object
+ = static_cast<const Powerpc_relobj<size, big_endian>*>(object);
+
+ if (size == 64
+ && this->abiversion() >= 2
+ && this->plt_localentry0()
+ && ppc_object->st_other(r_sym) >> 5 == 0)
+ {
+ const Symbol_value<size>* psymval = object->local_symbol(r_sym);
+ bool is_ordinary;
+ if (!psymval->is_ifunc_symbol()
+ && psymval->input_shndx(&is_ordinary) != elfcpp::SHN_UNDEF
+ && is_ordinary)
+ return true;
+ }
+ return false;
+ }
+
int
abiversion () const
{ return this->processor_specific_flags() & elfcpp::EF_PPC64_ABI; }
@@ -1475,6 +1526,9 @@ class Target_powerpc : public Sized_target<size, big_endian>
Tocsave_loc tocsave_loc_;
bool plt_thread_safe_;
+ bool plt_localentry0_;
+ bool plt_localentry0_init_;
+ bool has_localentry0_;
bool relax_failed_;
int relax_fail_count_;
@@ -2954,8 +3008,10 @@ Target_powerpc<size, big_endian>::Branch_info::mark_pltcall(
sym = symtab->resolve_forwards(sym);
const Sized_symbol<size>* gsym = static_cast<const Sized_symbol<size>*>(sym);
if (gsym != NULL
- ? gsym->use_plt_offset(Scan::get_reference_flags(this->r_type_, target))
- : this->object_->local_has_plt_offset(this->r_sym_))
+ ? (gsym->use_plt_offset(Scan::get_reference_flags(this->r_type_, target))
+ && !target->is_elfv2_localentry0(gsym))
+ : (this->object_->local_has_plt_offset(this->r_sym_)
+ && !target->is_elfv2_localentry0(this->object_, this->r_sym_)))
{
this->tocsave_ = 1;
return true;
@@ -3989,12 +4045,13 @@ class Stub_table : public Output_relaxed_input_section
struct Plt_stub_ent
{
Plt_stub_ent(unsigned int off, unsigned int indx)
- : off_(off), indx_(indx), r2save_(0)
+ : off_(off), indx_(indx), r2save_(0), localentry0_(0)
{ }
unsigned int off_;
- unsigned int indx_ : 31;
+ unsigned int indx_ : 30;
unsigned int r2save_ : 1;
+ unsigned int localentry0_ : 1;
};
typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
static const Address invalid_address = static_cast<Address>(0) - 1;
@@ -4439,8 +4496,18 @@ Stub_table<size, big_endian>::add_plt_call_entry(
std::pair<typename Plt_stub_entries::iterator, bool> p
= this->plt_call_stubs_.insert(std::make_pair(key, ent));
if (p.second)
- this->plt_size_ = ent.off_ + this->plt_call_size(p.first);
- if (size == 64 && !tocsave)
+ {
+ this->plt_size_ = ent.off_ + this->plt_call_size(p.first);
+ if (size == 64
+ && this->targ_->is_elfv2_localentry0(gsym))
+ {
+ p.first->second.localentry0_ = 1;
+ this->targ_->set_has_localentry0();
+ }
+ }
+ if (size == 64
+ && !tocsave
+ && !p.first->second.localentry0_)
p.first->second.r2save_ = 1;
return this->can_reach_stub(from, ent.off_, r_type);
}
@@ -4460,8 +4527,18 @@ Stub_table<size, big_endian>::add_plt_call_entry(
std::pair<typename Plt_stub_entries::iterator, bool> p
= this->plt_call_stubs_.insert(std::make_pair(key, ent));
if (p.second)
- this->plt_size_ = ent.off_ + this->plt_call_size(p.first);
- if (size == 64 && !tocsave)
+ {
+ this->plt_size_ = ent.off_ + this->plt_call_size(p.first);
+ if (size == 64
+ && this->targ_->is_elfv2_localentry0(object, locsym_index))
+ {
+ p.first->second.localentry0_ = 1;
+ this->targ_->set_has_localentry0();
+ }
+ }
+ if (size == 64
+ && !tocsave
+ && !p.first->second.localentry0_)
p.first->second.r2save_ = 1;
return this->can_reach_stub(from, ent.off_, r_type);
}
@@ -5184,6 +5261,7 @@ Output_data_glink<size, big_endian>::do_write(Output_file* of)
write_insn<big_endian>(p, mflr_0), p += 4;
write_insn<big_endian>(p, bcl_20_31), p += 4;
write_insn<big_endian>(p, mflr_11), p += 4;
+ write_insn<big_endian>(p, std_2_1 + 24), p += 4;
write_insn<big_endian>(p, ld_2_11 + l(-16)), p += 4;
write_insn<big_endian>(p, mtlr_0), p += 4;
write_insn<big_endian>(p, sub_12_12_11), p += 4;
@@ -7575,6 +7653,21 @@ Target_powerpc<size, big_endian>::scan_relocs(
typedef gold::Default_classify_reloc<elfcpp::SHT_RELA, size, big_endian>
Classify_reloc;
+ if (!this->plt_localentry0_init_)
+ {
+ bool plt_localentry0 = false;
+ if (size == 64
+ && this->abiversion() >= 2)
+ {
+ if (parameters->options().user_set_plt_localentry())
+ plt_localentry0 = parameters->options().plt_localentry();
+ else
+ plt_localentry0 = symtab->lookup("GLIBC_2.26", NULL) != NULL;
+ }
+ this->plt_localentry0_ = plt_localentry0;
+ this->plt_localentry0_init_ = true;
+ }
+
if (sh_type == elfcpp::SHT_REL)
{
gold_error(_("%s: unsupported REL reloc section"),
@@ -7771,6 +7864,9 @@ Target_powerpc<size, big_endian>::do_finalize_sections(
(this->glink_->pltresolve_size
- 32));
}
+ if (this->has_localentry0_)
+ odyn->add_constant(elfcpp::DT_PPC64_OPT,
+ elfcpp::PPC64_OPT_LOCALENTRY);
}
}
@@ -7916,6 +8012,7 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
= static_cast<Powerpc_relobj<size, big_endian>*>(relinfo->object);
Address value = 0;
bool has_stub_value = false;
+ bool localentry0 = false;
unsigned int r_sym = elfcpp::elf_r_sym<size>(rela.get_r_info());
if ((gsym != NULL
? gsym->use_plt_offset(Scan::get_reference_flags(r_type, target))
@@ -7969,6 +8066,7 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
&& next_rela.get_r_offset() == rela.get_r_offset() + 4)
value += 4;
}
+ localentry0 = ent->localentry0_;
has_stub_value = true;
}
}
@@ -8012,8 +8110,8 @@ Target_powerpc<size, big_endian>::Relocate::relocate(
{
typedef typename elfcpp::Swap<32, big_endian>::Valtype Valtype;
Valtype* wv = reinterpret_cast<Valtype*>(view);
- bool can_plt_call = false;
- if (rela.get_r_offset() + 8 <= view_size)
+ bool can_plt_call = localentry0;
+ if (!localentry0 && rela.get_r_offset() + 8 <= view_size)
{
Valtype insn = elfcpp::Swap<32, big_endian>::readval(wv);
Valtype insn2 = elfcpp::Swap<32, big_endian>::readval(wv + 1);
--
Alan Modra
Australia Development Lab, IBM