diff options
Diffstat (limited to 'gcc/doc/tm.texi')
| -rw-r--r-- | gcc/doc/tm.texi | 89 |
1 files changed, 85 insertions, 4 deletions
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index 869bb1b6a0a..91448a71a42 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. @@ -3170,7 +3171,7 @@ frame, or the frame pointer of the @var{count} @minus{} 1 frame if @code{RETURN_ADDR_IN_PREVIOUS_FRAME} is defined. The value of the expression must always be the correct address when -@var{count} is zero, but may be @code{NULL_RTX} if there is not way to +@var{count} is zero, but may be @code{NULL_RTX} if there is no way to determine the return address of other frames. @end defmac @@ -3818,9 +3819,11 @@ which. @c above is overfull. not sure what to do. --mew 5feb93 did @c something, not sure if it looks good. --mew 10feb93 -@defmac OUTGOING_REG_PARM_STACK_SPACE -Define this to a nonzero value if it is the responsibility of the caller -to allocate the area reserved for arguments passed in registers. +@defmac OUTGOING_REG_PARM_STACK_SPACE (@var{fntype}) +Define this to a nonzero value if it is the responsibility of the +caller to allocate the area reserved for arguments passed in registers +when calling a function of @var{fntype}. @var{fntype} may be NULL +if the function called is a library function. If @code{ACCUMULATE_OUTGOING_ARGS} is defined, this macro controls whether the space for these arguments counts in the value of @@ -9192,6 +9195,84 @@ 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 |