targhooks.h (default_emutls_var_fields, [...]): Declare.

	* targhooks.h (default_emutls_var_fields,
	default_emutls_var_init): Declare.
	* tree.h (DECL_THREAD_LOCAL): Compare against TLS_MODEL_REAL.
	* target.h (struct gcc_target): Add struct emutls member.
	* target-def.h (TARGET_EMUTLS_GET_ADDRESS,
	TARGET_EMUTLS_REGISTER_COMMON, TARGET_EMUTLS_VAR_SECTION,
	TARGET_EMUTLS_TMPL_SECTION, TARGET_EMUTLS_VAR_PREFIX,
	TARGET_EMUTLS_TMPL_PREFIX, TARGET_EMUTLS_VAR_FIELDS,
	TARGET_EMUTLS_VAR_INIT, TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS,
	TARGET_EMUTLS_VAR_ALIGN_FIXED, TARGET_EMUTLS): New.
	(TARGET_INITIALIZER): Add TARGET_EMUTLS.
	* builtins.def (BUILT_IN_EMUTLS_GET_ADDRESS,
	BUILT_IN_EMUTLS_REGISTER_COMMON): Get name from targetm structure.
	* dwarf2out.c (loc_descriptor_from_tree_1): Check if emutls can
	emit debug information.
	* coretypes.h (tls_model): Add TLS_MODEL_EMULATED, TLS_MODEL_REAL.
	* varasm.c: Include targhooks.h.
	(emutls_object_section, emutls_tmpl_section): New.
	(EMUTLS_VAR_PREFIX, EMUTLS_TMPL_PREFIX): Remove.
	(EMUTLS_SEPARATOR): New.
	(prefix_name): New.
	(get_emutls_object_name): New.
	(default_emutls_var_fields): New, broken out of ...
	(get_emutls_object_type): ... here.  Adjust to use target hooks.
	(get_emutls_init_templ_addr): Adjust to use target hooks.
	(emutls_decl): Adjust to use target hooks.
	(emutls_finish): Likewise.
	(default_emutls_var_init): New, broken out of ...
	(assemble_variable): ... here.  Adjust to use target hooks.
	* output.h (enum section_category): Add SECCAT_EMUTLS_VAR,
	SECCAT_EMUTLS_TMPL.
	* c-common.c (handle_section_attribute): Prevent overriding
	sections for emulated tls with special sections.
	* config/i386/i386.c (x86_64_elf_select_section): Add
	SECCAT_EMUTLS_VAR and SECCAT_EMUTLS_TMPL.
	(x86_64_elf_unique_section): Likewise.
	* config/vxworks.c: Include tree.h.
	(vxworks_emutls_var_fields, vxworks_emutls_var_init): New.
	(vxworks_override_options): Set TLS scheme.
	* gcc/doc/tm.texi (Emulated TLS): New node.

	gcc/testsuite/
	* gcc.dg/tls/section-2.c: New.
	* gcc.dg/tls/emutls-1.c: New.
	* lib/target-supports.exp (check_effective_target_tls_native):
	Exclude vxworks.

From-SVN: r134729

1 files changed, 79 insertions, 0 deletions

diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 869bb1b..6ce3b4a 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -50,6 +50,7 @@ through the macros defined in the @file{.h} file.
 * Floating Point::      Handling floating point for cross-compilers.
 * Mode Switching::      Insertion of mode-switching instructions.
 * Target Attributes::   Defining target-specific uses of @code{__attribute__}.
+* Emulated TLS::        Emulated TLS support.
 * MIPS Coprocessors::   MIPS coprocessor support and how to customize it.
 * PCH Target::          Validity checking for precompiled headers.
 * C++ ABI::             Controlling C++ ABI changes.
@@ -9192,6 +9193,84 @@ attributes, @code{false} otherwise.  By default, if a function has a
 target specific attribute attached to it, it will not be inlined.
 @end deftypefn
 
+@node Emulated TLS
+@section Emulating TLS
+@cindex Emulated TLS
+
+For targets whose psABI does not provide Thread Local Storage via
+specific relocations and instruction sequences, an emulation layer is
+used.  A set of target hooks allows this emulation layer to be
+configured for the requirements of a particular target.  For instance
+the psABI may infact specify TLS support in terms of an emulation
+layer.
+
+The emulation layer works by creating a control object for every TLS
+object.  To access the TLS object, a lookup function is provided
+which, when given the address of the control object, will return the
+address of the current thread's instance of the TLS object.
+
+@deftypevr {Target Hook} {const char *} TARGET_EMUTLS_GET_ADDRESS
+Contains the name of the helper function that uses a TLS control
+object to locate a TLS instance.  The default causes libgcc's
+emulated TLS helper function to be used.
+@end deftypevr
+
+@deftypevr {Target Hook} {const char *} TARGET_EMUTLS_REGISTER_COMMON
+Contains the name of the helper function that should be used at
+program startup to register TLS objects that are implicitly
+initialized to zero.  If this is @code{NULL}, all TLS objects will
+have explicit initializers.  The default causes libgcc's emulated TLS
+registration function to be used.
+@end deftypevr
+
+@deftypevr {Target Hook} {const char *} TARGET_EMUTLS_VAR_SECTION
+Contains the name of the section in which TLS control variables should
+be placed.  The default of @code{NULL} allows these to be placed in
+any section.
+@end deftypevr
+
+@deftypevr {Target Hook} {const char *} TARGET_EMUTLS_TMPL_SECTION
+Contains the name of the section in which TLS initializers should be
+placed.  The default of @code{NULL} allows these to be placed in any
+section.
+@end deftypevr
+
+@deftypevr {Target Hook} {const char *} TARGET_EMUTLS_VAR_PREFIX
+Contains the prefix to be prepended to TLS control variable names.
+The default of @code{NULL} uses a target-specific prefix.
+@end deftypevr
+
+@deftypevr {Target Hook} {const char *} TARGET_EMUTLS_TMPL_PREFIX
+Contains the prefix to be prepended to TLS initializer objects.  The
+default of @code{NULL} uses a target-specific prefix.
+@end deftypevr
+
+@deftypefn {Target Hook} tree TARGET_EMUTLS_VAR_FIELDS (tree @var{type}, tree *@var{name})
+Specifies a function that generates the FIELD_DECLs for a TLS control
+object type.  @var{type} is the RECORD_TYPE the fields are for and
+@var{name} should be filled with the structure tag, if the default of
+@code{__emutls_object} is unsuitable.  The default creates a type suitable
+for libgcc's emulated TLS function.
+@end deftypefn
+
+@deftypefn {Target Hook} tree TARGET_EMUTLS_VAR_INIT (tree @var{var}, tree @var{decl}, tree @var{tmpl_addr})
+Specifies a function that generates the CONSTRUCTOR to initialize a
+TLS control object.  @var{var} is the TLS control object, @var{decl}
+is the TLS object and @var{tmpl_addr} is the address of the
+initializer.  The default initializes libgcc's emulated TLS control object.
+@end deftypefn
+
+@deftypevr {Target Hook} {bool} TARGET_EMUTLS_VAR_ALIGN_FIXED
+Specifies whether the alignment of TLS control variable objects is
+fixed and should not be increased as some backends may do to optimize
+single objects.  The default is false.
+@end deftypevr
+
+@deftypevr {Target Hook} {bool} TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS
+Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor
+may be used to describe emulated TLS control objects.
+@end deftypevr
+
 @node MIPS Coprocessors
 @section Defining coprocessor specifics for MIPS targets.
 @cindex MIPS coprocessor-definition macros