c-common.h (enum rid): Add RID_THREAD.

        * c-common.h (enum rid): Add RID_THREAD.
        * c-decl.c (start_decl): Do not set DECL_COMMON for tls variables.
        (grokdeclarator): Grok __thread.
        * c-parse.in (reswords): Add __thread.
        (rid_to_yy): Add RID_THREAD.
        * cp/lex.c (rid_to_yy): Add RID_THREAD.

        * tree.h (DECL_THREAD_LOCAL): New.
        (struct tree_decl): Add thread_local_flag.
        * print-tree.c (print_node): Dump DECL_THREAD_LOCAL.
        * tree.c (staticp): TLS variables are not static.

        * target-def.h (TARGET_HAVE_TLS): New.
        * target.h (have_tls): New.
        * output.h (SECTION_TLS): New.
        * varasm.c (assemble_variable): TLS variables can't be common for now.
        (default_section_type_flags): Handle .tdata and .tbss.
        (default_elf_asm_named_section): Handle SECTION_TLS.
        (categorize_decl_for_section): Handle DECL_THREAD_LOCAL.

        * flags.h (flag_tls_default): Declare.
        * toplev.c (flag_tls_default): Define.
        (display_help): Display help for it.
        (decode_f_option): Set it.

        * doc/extend.texi (Thread-Local): New node describing language-level
        thread-local storage.
        * doc/invoke.texi (-ftls-model): Document.

        * fixinc/inclhack.def (thread_keyword): New.
        * fixinc/fixincl.x: Rebuild.

From-SVN: r53715

2 files changed, 59 insertions, 1 deletions

diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index b27bec4..e37a66b 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -432,6 +432,7 @@ extensions, accepted by GCC in C89 mode and in C++.
 * Target Builtins::     Built-in functions specific to particular targets.
 * Pragmas::             Pragmas accepted by GCC.
 * Unnamed Fields::      Unnamed struct/union fields within structs/unions.
+* Thread-Local::        Per-thread variables.
 @end menu
 
 @node Statement Exprs
@@ -6165,6 +6166,55 @@ It is ambiguous which @code{a} is being referred to with @samp{foo.a}.
 Such constructs are not supported and must be avoided.  In the future,
 such constructs may be detected and treated as compilation errors.
 
+@node Thread-Local
+@section Thread-Local Storage
+@cindex Thread-Local Storage
+@cindex TLS
+@cindex __thread
+
+Thread-local storage (TLS) is a mechanism by which variables are
+allocated such that there is one instance of the variable per extant
+thread.  The run-time model GCC uses to implement this originates
+in the IA-64 processor-specific ABI, but has since been migrated
+to other processors as well.  It requires significant support from
+the linker (@command{ld}), dynamic linker (@command{ld.so}), and
+system libraries (@file{libc.so} and @file{libpthread.so}), so it
+is not supported everywhere.
+
+At the user level, the extension is visible with a new storage
+class keyword: @code{__thread}.  For example:
+
+@example
+__thread int i;
+extern __thread struct state s;
+static __thread char *p;
+@end example
+
+The @code{__thread} specifier may be used alone, with the @code{extern}
+or @code{static} specifiers, but with no other storage class specifier.
+When used with @code{extern} or @code{static}, @code{__thread} must appear
+immediately after the other storage class specifier.
+
+The @code{__thread} specifier may be applied to any global, file-scoped
+static, function-scoped static, or class-scoped static variable.  It may
+not be applied to function-scoped automatic or class-scoped member variables.
+
+When the address-of operator is applied to a thread-local variable, it is
+evaluated at run-time and returns the address of the current thread's
+instance of that variable.  An address so obtained may be used by any
+thread.  When a thread terminates, any pointers to thread-local variables
+in that thread become invalid.
+
+No static initialization may refer to the address of a thread-local variable.
+
+In C++, a thread-local variable may not be initialized by a static
+constructor.
+
+See @uref{http://people.redhat.com/drepper/tls.pdf,
+ELF Handling For Thread-Local Storage} for a detailed explanation of
+the four thread-local storage addressing models, and how the run-time
+is expected to function.
+
 @node C++ Extensions
 @chapter Extensions to the C++ Language
 @cindex extensions, C++ language
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 855fcd9..cedabdf 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -677,7 +677,7 @@ in the following sections.
 -fverbose-asm  -fpack-struct  -fstack-check @gol
 -fstack-limit-register=@var{reg}  -fstack-limit-symbol=@var{sym} @gol
 -fargument-alias  -fargument-noalias @gol
--fargument-noalias-global  -fleading-underscore}
+-fargument-noalias-global  -fleading-underscore -ftls-model=@var{model}}
 @end table
 
 @menu
@@ -9915,6 +9915,14 @@ is to help link with legacy assembly code.
 
 Be warned that you should know what you are doing when invoking this
 option, and that not all targets provide complete support for it.
+
+@item -ftls-model=@var{model}
+Alter the thread-local storage model to be used (@pxref{Thread-Local}).
+The @var{model} argument should be one of @code{global-dynamic},
+@code{local-dynamic}, @code{initial-exec} or @code{local-exec}.
+
+The default without @option{-fpic} is @code{initial-exec}; with
+@option{-fpic} the default is @code{global-dynamic}.
 @end table
 
 @c man end