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Alan Modra 34e0882b83 [GOLD] PowerPC tls_get_addr_optimize 
This implements the special __tls_get_addr_opt call stub for powerpc
gold that returns __thread variable addresses without actually making
a call to __tls_get_addr in most cases.  Shared libraries that are
loaded at program load time (ie. dlopen is not used) have a known
layout for their __thread variables, and thus DTPMOD64/DPTREL64 pairs
describing those variables can be set up by ld.so for the
__tls_get_addr_opt call stub fast exit.
Ref https://sourceware.org/ml/libc-alpha/2015-03/msg00626.html

I really, really wish I'd used a differently versioned __tls_get_addr
symbol than the base symbol to indicate glibc support for the
optimized call, rather than having glibc export __tls_get_addr_opt.  A
lot of the messing around here, flipping symbols from __tls_get_addr
to __tls_get_addr_opt, is caused by that decision.  About the only
benefit is that a user can see at a glance that their disassembled
code is calling __tls_get_addr via the fancy call stub..  Anyway, we
need references to __tls_get_addr to seem like they were to
__tls_get_addr_opt, and in cases like the tsan interceptor, a
definition of __tls_get_addr to seem like one of __tls_get_addr_opt
as well.  That's the reason for Symbol::clear_in_reg and
Symbol_table::clone, and why symbols are substituted in Scan::global
and other places dealing with dynamic linking.

elfcpp/
	* elfcpp.h (DT_PPC_OPT): Define.
	* powerpc.h (PPC_OPT_TLS): Define.
gold/
	* options.h (tls_get_addr_optimize): New option.
	* symtab.h (Symbol::clear_in_reg, clone): New functions.
	(Sized_symbol::clone): New function.
	(Symbol_table::clone): New function.
	* resolve.cc (Symbol::clone, Sized_symbol::clone): New functions.
	* powerpc.cc (Target_powerpc::has_tls_get_addr_opt_,
	tls_get_addr_, tls_get_addr_opt_): New vars.
	(Target_powerpc::tls_get_addr_opt, tls_get_addr,
	is_tls_get_addr_opt, replace_tls_get_addr,
	set_has_tls_get_addr_opt, stk_linker): New functions.
	(Target_powerpc::Track_tls::maybe_skip_tls_get_addr_call): Add
	target param.  Update callers.  Compare symbols rather than names.
	(Target_powerpc::do_define_standard_symbols): Init tls_get_addr_
	and tls_get_addr_opt_.
	(Target_powerpc::Branch_info::mark_pltcall): Translate tls_get_addr
	sym to tls_get_addr_opt.
	(Target_powerpc::Branch_info::make_stub): Likewise.
	(Stub_table::define_stub_syms): Likewise.
	(Target_powerpc::Scan::global): Likewise.
	(Target_powerpc::Relocate::relocate): Likewise.
	(add_3_12_2, add_3_12_13, bctrl, beqlr, cmpdi_11_0, cmpwi_11_0,
	ld_11_1, ld_11_3, ld_12_3, lwz_11_3, lwz_12_3, mr_0_3, mr_3_0,
	mtlr_11, std_11_1): New constants.
	(Stub_table::eh_frame_added_): Delete.
	(Stub_table::tls_get_addr_opt_bctrl_, plt_fde_len_, plt_fde_): New vars.
	(Stub_table::init_plt_fde): New functions.
	(Stub_table::add_eh_frame, replace_eh_frame): Move definition out
	of line.  Init and use plt_fde_.
	(Stub_table::plt_call_size): Return size for tls_get_addr stub.
	Extract alignment code to..
	(Stub_table::plt_call_align): ..this new function.  Adjust all callers.
	(Stub_table::add_plt_call_entry): Set has_tls_get_addr_opt and
	tls_get_addr_opt_bctrl, and align after that.
	(Stub_table::do_write): Write out tls_get_addr stub.
	(Target_powerpc::do_finalize_sections): Emit DT_PPC_OPT
	PPC_OPT_TLS/PPC64_OPT_TLS bit.
	(Target_powerpc::Relocate::relocate): Don't check for or modify
	nop following bl for tls_get_addr stub.
2017-08-29 21:29:37 +09:30
..
aarch64.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
arm.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
ChangeLog [GOLD] PowerPC tls_get_addr_optimize 2017-08-29 21:29:37 +09:30
ChangeLog-0815
ChangeLog-2016
dwarf.h [GOLD] undef after using DW_IDX and friends 2017-07-03 21:49:34 +09:30
elfcpp_file.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
elfcpp_internal.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
elfcpp_swap.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
elfcpp.h [GOLD] PowerPC tls_get_addr_optimize 2017-08-29 21:29:37 +09:30
i386.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
mips.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
powerpc.h [GOLD] PowerPC tls_get_addr_optimize 2017-08-29 21:29:37 +09:30
README Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
s390.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
sparc.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
tilegx.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30
x86_64.h Update year range in copyright notice of all files. 2017-01-02 14:08:56 +10:30

README

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

elfcpp is a C++ library for reading and writing ELF information.  This
was written to support gold, the ELF linker, and may not be generally
useful.

elfcpp does not do file I/O.  It deals only with offsets and memory
data.

For efficiency, most accessors are templates with two arguments: the
ELF file class (32 or 64 bits) and the endianness.


Copyright (C) 2012-2017 Free Software Foundation, Inc.

Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright
notice and this notice are preserved.