Add PowerPC64 ld --tls-get-addr-optimize.

Sometimes it may be of benefit to force use of the __tls_get_addr_opt
call stub even when the glibc being used during linking does not
advertise __tls_get_addr_opt.

bfd/
	* elf64-ppc.h (struct ppc64_elf_params <tls_get_addr_opt>): Rename
	from no_tls_get_addr_opt.
	* elf64-ppc.c: Update for rename and inversion of tls_get_addr_opt.
	(ppc64_elf_tls_setup): Set tls_get_addr_opt to 0 only when at
	default of -1.
ld/
	* emultempl/ppc64elf.em (params): Init tls_get_addr_opt field to -1.
	(OPTION_TLS_GET_ADDR_OPT): Define.
	(PARSE_AND_LIST_LONGOPTS): Handle --tls-get-addr-opt.
	(PARSE_AND_LIST_OPTIONS, PARSE_AND_LIST_ARGS_CASES): Likewise.
	* ld.texinfo: Document --tls-get-addr-optimize and
	--no-tls-get-addr-optimize.

3 files changed, 37 insertions, 4 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 96359f5..f495ed2 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,5 +1,14 @@
 2015-09-18  Alan Modra  <amodra@gmail.com>
 
+	* emultempl/ppc64elf.em (params): Init tls_get_addr_opt field to -1.
+	(OPTION_TLS_GET_ADDR_OPT): Define.
+	(PARSE_AND_LIST_LONGOPTS): Handle --tls-get-addr-opt.
+	(PARSE_AND_LIST_OPTIONS, PARSE_AND_LIST_ARGS_CASES): Likewise.
+	* ld.texinfo: Document --tls-get-addr-optimize and
+	--no-tls-get-addr-optimize.
+
+2015-09-18  Alan Modra  <amodra@gmail.com>
+
 	PR ld/18963
 	* ldexp.h (struct ldexp_control): Add rel_from_abs.
 	(ldexp_finalize_syms): Declare.
diff --git a/ld/emultempl/ppc64elf.em b/ld/emultempl/ppc64elf.em
index 41942f9..08bd5d4 100644
--- a/ld/emultempl/ppc64elf.em
+++ b/ld/emultempl/ppc64elf.em
@@ -37,7 +37,7 @@ static void ppc_layout_sections_again (void);
 static struct ppc64_elf_params params = { NULL,
 					  &ppc_add_stub_section,
 					  &ppc_layout_sections_again,
-					  1, 0, 0,
+					  1, -1, 0,
 					  ${DEFAULT_PLT_STATIC_CHAIN-0}, -1, 0,
 					  0, -1, -1, 0};
 
@@ -699,7 +699,8 @@ PARSE_AND_LIST_PROLOGUE=${PARSE_AND_LIST_PROLOGUE}'
 #define OPTION_DOTSYMS			(OPTION_NO_SAVRES + 1)
 #define OPTION_NO_DOTSYMS		(OPTION_DOTSYMS + 1)
 #define OPTION_NO_TLS_OPT		(OPTION_NO_DOTSYMS + 1)
-#define OPTION_NO_TLS_GET_ADDR_OPT	(OPTION_NO_TLS_OPT + 1)
+#define OPTION_TLS_GET_ADDR_OPT		(OPTION_NO_TLS_OPT + 1)
+#define OPTION_NO_TLS_GET_ADDR_OPT	(OPTION_TLS_GET_ADDR_OPT + 1)
 #define OPTION_NO_OPD_OPT		(OPTION_NO_TLS_GET_ADDR_OPT + 1)
 #define OPTION_NO_TOC_OPT		(OPTION_NO_OPD_OPT + 1)
 #define OPTION_NO_MULTI_TOC		(OPTION_NO_TOC_OPT + 1)
@@ -722,6 +723,7 @@ PARSE_AND_LIST_LONGOPTS=${PARSE_AND_LIST_LONGOPTS}'
   { "save-restore-funcs", no_argument, NULL, OPTION_SAVRES },
   { "no-save-restore-funcs", no_argument, NULL, OPTION_NO_SAVRES },
   { "no-tls-optimize", no_argument, NULL, OPTION_NO_TLS_OPT },
+  { "tls-get-addr-optimize", no_argument, NULL, OPTION_TLS_GET_ADDR_OPT },
   { "no-tls-get-addr-optimize", no_argument, NULL, OPTION_NO_TLS_GET_ADDR_OPT },
   { "no-opd-optimize", no_argument, NULL, OPTION_NO_OPD_OPT },
   { "no-toc-optimize", no_argument, NULL, OPTION_NO_TOC_OPT },
@@ -786,6 +788,9 @@ PARSE_AND_LIST_OPTIONS=${PARSE_AND_LIST_OPTIONS}'
   --no-tls-optimize           Don'\''t try to optimize TLS accesses.\n"
 		   ));
   fprintf (file, _("\
+  --tls-get-addr-optimize     Force use of special __tls_get_addr call.\n"
+		   ));
+  fprintf (file, _("\
   --no-tls-get-addr-optimize  Don'\''t use a special __tls_get_addr call.\n"
 		   ));
   fprintf (file, _("\
@@ -877,8 +882,12 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
       no_tls_opt = 1;
       break;
 
+    case OPTION_TLS_GET_ADDR_OPT:
+      params.tls_get_addr_opt = 1;
+      break;
+
     case OPTION_NO_TLS_GET_ADDR_OPT:
-      params.no_tls_get_addr_opt = 1;
+      params.tls_get_addr_opt = 0;
       break;
 
     case OPTION_NO_OPD_OPT:
@@ -903,7 +912,7 @@ PARSE_AND_LIST_ARGS_CASES=${PARSE_AND_LIST_ARGS_CASES}'
 
     case OPTION_TRADITIONAL_FORMAT:
       no_tls_opt = 1;
-      params.no_tls_get_addr_opt = 1;
+      params.tls_get_addr_opt = 0;
       no_opd_opt = 1;
       no_toc_opt = 1;
       params.no_multi_toc = 1;
diff --git a/ld/ld.texinfo b/ld/ld.texinfo
index be1d490..57f1730 100644
--- a/ld/ld.texinfo
+++ b/ld/ld.texinfo
@@ -7133,6 +7133,21 @@ PowerPC64 @command{ld} normally performs some optimization of code
 sequences used to access Thread-Local Storage.  Use this option to
 disable the optimization.
 
+@cindex PowerPC64 __tls_get_addr optimization
+@kindex --tls-get-addr-optimize
+@kindex --no-tls-get-addr-optimize
+@item --tls-get-addr-optimize, --no-tls-get-addr-optimize
+These options control whether PowerPC64 @command{ld} uses a special
+stub to call __tls_get_addr.  PowerPC64 glibc 2.22 and later support
+an optimization that allows the second and subsequent calls to
+@code{__tls_get_addr} for a given symbol to be resolved by the special
+stub without calling in to glibc.  By default the linker enables this
+option when glibc advertises the availability of __tls_get_addr_opt.
+Forcing this option on when using an older glibc won't do much besides
+slow down your applications, but may be useful if linking an
+application against an older glibc with the expectation that it will
+normally be used on systems having a newer glibc.
+
 @cindex PowerPC64 OPD optimization
 @kindex --no-opd-optimize
 @item --no-opd-optimize