From patchwork Thu Oct 30 01:53:08 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alan Modra X-Patchwork-Id: 3497 Received: (qmail 19832 invoked by alias); 30 Oct 2014 01:53:26 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 19458 invoked by uid 89); 30 Oct 2014 01:53:23 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL, BAYES_00, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-pd0-f176.google.com X-Received: by 10.66.244.233 with SMTP id xj9mr12854273pac.67.1414633997288; Wed, 29 Oct 2014 18:53:17 -0700 (PDT) Date: Thu, 30 Oct 2014 12:23:08 +1030 From: Alan Modra To: "Joseph S. Myers" Cc: libc-alpha@sourceware.org, bug-gnulib@gnu.org Subject: Re: [PATCH] 64-bit obstack support Message-ID: <20141030015308.GQ4267@bubble.grove.modra.org> References: <20141029033453.GO4267@bubble.grove.modra.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) On Wed, Oct 29, 2014 at 06:34:02PM +0000, Joseph S. Myers wrote: > On Wed, 29 Oct 2014, Alan Modra wrote: > > > And >2G on 32-bit. > > > > [BZ #14483] > > in the ChangeLog entry. Thanks, added. Since the stdalign.h change won't do for glibc, I've split the glibc patch into two. The first being Import new obstack support from gnulib * malloc/obstack.h: Import from gnulib. * malloc/obstack.c: Likewise. The second 64-bit obstack support And >2G on 32-bit. [BZ #14483] * include/gnu-versions.h (_GNU_OBSTACK_INTERFACE_VERSION): Bump. * include/obstack.h: Include shlib-compat.h and gnu-versions.h. (_OBSTACK_ELIDE_CODE, _OBSTACK_NO_ERROR_HANDLER, _OBSTACK_COMPAT, _OBSTACK_ALIAS): Define. (_obstack_allocated_p, _obstack_newchunk, _obstack_free, _obstack_begin, _obstack_begin_1, _obstack_memory_used): Define. (_obstack_newchunk): Only use libc_hidden_proto on the version we will use inside glibc. * malloc/obstack.c: Revert gnulib commit e8f86ce9, ie. don't use stdalign.h and alignof. * malloc/obstackv1.c: New file. * malloc/obstackv2.c: New file. * malloc/Makefile (routines): Remove obstack. Add obstackv1 and obstackv2. (CFLAGS-obstack.c): Don't define. (CFLAGS-obstackv1.c, CFLAGS-obstackv2.c): Define. (malloc/Versions): Add GLIBC_2.21 _obstack functions. * config.h.in (SIZEOF_INT, SIZEOF_SIZE_T): Add. * configure.in: AC_CHECK_SIZEOF int and size_t. * configure: Regenerate. * manual/memory.texi: Update obstack documentation. Added manual patch follows. It's missing @safety markup for the previously undocumented obstack_begin, obstack_specify_allocation, and obstack_specify_allocation_with_arg macros. I'm hoping someone else can do that as I'd just be guessing. (Are they even appropriate for macros?) diff --git a/manual/memory.texi b/manual/memory.texi index 0729e70..5ab16b7 100644 --- a/manual/memory.texi +++ b/manual/memory.texi @@ -1922,8 +1922,7 @@ the padding needed to start each object on a suitable boundary. use obstacks. * Allocation in an Obstack:: Allocating objects in an obstack. * Freeing Obstack Objects:: Freeing objects in an obstack. -* Obstack Functions:: The obstack functions are both - functions and macros. +* Obstack Functions:: The obstack functions are really macros. * Growing Objects:: Making an object bigger by stages. * Extra Fast Growing:: Extra-high-efficiency (though more complicated) growing objects. @@ -1948,7 +1947,7 @@ An obstack is represented by a data structure of type @code{struct obstack}. This structure has a small fixed size; it records the status of the obstack and how to find the space in which objects are allocated. It does not contain any of the objects themselves. You should not try -to access the contents of the structure directly; use only the functions +to access the contents of the structure directly; use only the macros described in this chapter. @end deftp @@ -1958,7 +1957,7 @@ of object. Dynamic allocation of obstacks allows your program to have a variable number of different stacks. (You can even allocate an obstack structure in another obstack, but this is rarely useful.) -All the functions that work with obstacks require you to specify which +All the macros that work with obstacks require you to specify which obstack to use. You do this with a pointer of type @code{struct obstack *}. In the following, we often say ``an obstack'' when strictly speaking the object at hand is such a pointer. @@ -1978,7 +1977,7 @@ These matters are described in the following section. @node Preparing for Obstacks @subsubsection Preparing for Using Obstacks -Each source file in which you plan to use the obstack functions +Each source file in which you plan to use obstacks must include the header file @file{obstack.h}, like this: @smallexample @@ -2011,7 +2010,9 @@ larger blocks of memory. @xref{Obstack Chunks}, for full details. At run time, before the program can use a @code{struct obstack} object as an obstack, it must initialize the obstack by calling -@code{obstack_init}. +@code{obstack_init} or one of its variants, @code{obstack_begin}, +@code{obstack_specify_allocation}, or +@code{obstack_specify_allocation_with_arg}. @comment obstack.h @comment GNU @@ -2031,10 +2032,10 @@ as an obstack, it must initialize the obstack by calling @c fxprintf dup @asucorrupt @aculock @acucorrupt @c exit @acucorrupt? Initialize obstack @var{obstack-ptr} for allocation of objects. This -function calls the obstack's @code{obstack_chunk_alloc} function. If +macro calls the obstack's @code{obstack_chunk_alloc} function. If allocation of memory fails, the function pointed to by @code{obstack_alloc_failed_handler} is called. The @code{obstack_init} -function always returns 1 (Compatibility notice: Former versions of +macro always returns 1 (Compatibility notice: Former versions of obstack returned 0 if allocation failed). @end deftypefun @@ -2059,6 +2060,29 @@ obstack_init (myobstack_ptr); @comment obstack.h @comment GNU +@deftypefun int obstack_begin (struct obstack *@var{obstack-ptr}, size_t chunk_size) +Like @code{obstack_init}, but specify an initial chunk of +@var{chunk_size} bytes. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun int obstack_specify_allocation (struct obstack *@var{obstack-ptr}, size_t chunk_size, size_t alignment, void *(*chunkfun) (size_t), void (*freefun) (void *)) +Like @code{obstack_init}, specifying intial chunk size, chunk +alignment, and memory allocation functions. A @var{chunk_size} or +@var{alignment} of zero results in the default size or alignment +respectively being used. +@end deftypefun + +@comment obstack.h +@comment GNU +@deftypefun int obstack_specify_allocation_with_arg (struct obstack *@var{obstack-ptr}, size_t chunk_size, size_t alignment, void *(*chunkfun) (void *, size_t), void (*freefun) (void *, void *), void *arg) +Like @code{obstack_specify_allocation}, but specifying memory +allocation functions that take an extra first argument, @var{arg}. +@end deftypefun + +@comment obstack.h +@comment GNU @defvar obstack_alloc_failed_handler The value of this variable is a pointer to a function that @code{obstack} uses when @code{obstack_chunk_alloc} fails to allocate @@ -2084,7 +2108,7 @@ The most direct way to allocate an object in an obstack is with @comment obstack.h @comment GNU -@deftypefun {void *} obstack_alloc (struct obstack *@var{obstack-ptr}, int @var{size}) +@deftypefun {void *} obstack_alloc (struct obstack *@var{obstack-ptr}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_alloc @mtsrace:obstack-ptr @acucorrupt @acsmem @c obstack_blank dup @mtsrace:obstack-ptr @acucorrupt @acsmem @@ -2092,10 +2116,10 @@ The most direct way to allocate an object in an obstack is with This allocates an uninitialized block of @var{size} bytes in an obstack and returns its address. Here @var{obstack-ptr} specifies which obstack to allocate the block in; it is the address of the @code{struct obstack} -object which represents the obstack. Each obstack function or macro +object which represents the obstack. Each obstack macro requires you to specify an @var{obstack-ptr} as the first argument. -This function calls the obstack's @code{obstack_chunk_alloc} function if +This macro calls the obstack's @code{obstack_chunk_alloc} function if it needs to allocate a new chunk of memory; it calls @code{obstack_alloc_failed_handler} if allocation of memory by @code{obstack_chunk_alloc} failed. @@ -2117,12 +2141,11 @@ copystring (char *string) @} @end smallexample -To allocate a block with specified contents, use the function -@code{obstack_copy}, declared like this: +To allocate a block with specified contents, use the macro @code{obstack_copy}. @comment obstack.h @comment GNU -@deftypefun {void *} obstack_copy (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +@deftypefun {void *} obstack_copy (struct obstack *@var{obstack-ptr}, void *@var{address}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_copy @mtsrace:obstack-ptr @acucorrupt @acsmem @c obstack_grow dup @mtsrace:obstack-ptr @acucorrupt @acsmem @@ -2135,7 +2158,7 @@ bytes of data starting at @var{address}. It calls @comment obstack.h @comment GNU -@deftypefun {void *} obstack_copy0 (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +@deftypefun {void *} obstack_copy0 (struct obstack *@var{obstack-ptr}, void *@var{address}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_copy0 @mtsrace:obstack-ptr @acucorrupt @acsmem @c obstack_grow0 dup @mtsrace:obstack-ptr @acucorrupt @acsmem @@ -2144,13 +2167,13 @@ Like @code{obstack_copy}, but appends an extra byte containing a null character. This extra byte is not counted in the argument @var{size}. @end deftypefun -The @code{obstack_copy0} function is convenient for copying a sequence +The @code{obstack_copy0} macro is convenient for copying a sequence of characters into an obstack as a null-terminated string. Here is an example of its use: @smallexample char * -obstack_savestring (char *addr, int size) +obstack_savestring (char *addr, size_t size) @{ return obstack_copy0 (&myobstack, addr, size); @} @@ -2164,7 +2187,7 @@ Contrast this with the previous example of @code{savestring} using @subsubsection Freeing Objects in an Obstack @cindex freeing (obstacks) -To free an object allocated in an obstack, use the function +To free an object allocated in an obstack, use the macro @code{obstack_free}. Since the obstack is a stack of objects, freeing one object automatically frees all other objects allocated more recently in the same obstack. @@ -2200,13 +2223,9 @@ obstacks, or non-obstack allocation, can reuse the space of the chunk. @subsubsection Obstack Functions and Macros @cindex macros -The interfaces for using obstacks may be defined either as functions or -as macros, depending on the compiler. The obstack facility works with -all C compilers, including both @w{ISO C} and traditional C, but there are -precautions you must take if you plan to use compilers other than GNU C. - -If you are using an old-fashioned @w{non-ISO C} compiler, all the obstack -``functions'' are actually defined only as macros. You can call these +The interfaces for using obstacks are shown here as functions to +specify the return types and give a hint as to expected argument +types, but they are really defined as macros. You can call these macros like functions, but you cannot use them in any other way (for example, you cannot take their address). @@ -2224,34 +2243,15 @@ If you use @code{*obstack_list_ptr++} as the obstack pointer argument, you will get very strange results since the incrementation may occur several times. -In @w{ISO C}, each function has both a macro definition and a function -definition. The function definition is used if you take the address of the -function without calling it. An ordinary call uses the macro definition by -default, but you can request the function definition instead by writing the -function name in parentheses, as shown here: - -@smallexample -char *x; -void *(*funcp) (); -/* @r{Use the macro}. */ -x = (char *) obstack_alloc (obptr, size); -/* @r{Call the function}. */ -x = (char *) (obstack_alloc) (obptr, size); -/* @r{Take the address of the function}. */ -funcp = obstack_alloc; -@end smallexample - -@noindent -This is the same situation that exists in @w{ISO C} for the standard library -functions. @xref{Macro Definitions}. - -@strong{Warning:} When you do use the macros, you must observe the -precaution of avoiding side effects in the first operand, even in @w{ISO C}. - If you use the GNU C compiler, this precaution is not necessary, because various language extensions in GNU C permit defining the macros so as to compute each argument only once. +@code{obstack.h} does declare a number of functions, +@code{_obstack_begin}, @code{_obstack_begin_1}, +@code{_obstack_newchunk}, @code{_obstack_free}, and +@code{_obstack_memory_used}. You should not call these directly. + @node Growing Objects @subsubsection Growing Objects @cindex growing objects (in obstacks) @@ -2261,13 +2261,13 @@ Because memory in obstack chunks is used sequentially, it is possible to build up an object step by step, adding one or more bytes at a time to the end of the object. With this technique, you do not need to know how much data you will put in the object until you come to the end of it. We call -this the technique of @dfn{growing objects}. The special functions +this the technique of @dfn{growing objects}. The special macros for adding data to the growing object are described in this section. You don't need to do anything special when you start to grow an object. -Using one of the functions to add data to the object automatically +Using one of the macros to add data to the object automatically starts it. However, it is necessary to say explicitly when the object is -finished. This is done with the function @code{obstack_finish}. +finished. This is done with @code{obstack_finish}. The actual address of the object thus built up is not known until the object is finished. Until then, it always remains possible that you will @@ -2279,7 +2279,7 @@ already added to the growing object will become part of the other object. @comment obstack.h @comment GNU -@deftypefun void obstack_blank (struct obstack *@var{obstack-ptr}, int @var{size}) +@deftypefun void obstack_blank (struct obstack *@var{obstack-ptr}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_blank @mtsrace:obstack-ptr @acucorrupt @acsmem @c _obstack_newchunk @mtsrace:obstack-ptr @acucorrupt @acsmem @@ -2287,13 +2287,13 @@ already added to the growing object will become part of the other object. @c *obstack_alloc_failed_handler dup user-supplied @c *freefun @c obstack_blank_fast dup @mtsrace:obstack-ptr -The most basic function for adding to a growing object is +The most basic macro for adding to a growing object is @code{obstack_blank}, which adds space without initializing it. @end deftypefun @comment obstack.h @comment GNU -@deftypefun void obstack_grow (struct obstack *@var{obstack-ptr}, void *@var{data}, int @var{size}) +@deftypefun void obstack_grow (struct obstack *@var{obstack-ptr}, void *@var{data}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_grow @mtsrace:obstack-ptr @acucorrupt @acsmem @c _obstack_newchunk dup @mtsrace:obstack-ptr @acucorrupt @acsmem @@ -2306,7 +2306,7 @@ bytes of data to the growing object, copying the contents from @comment obstack.h @comment GNU -@deftypefun void obstack_grow0 (struct obstack *@var{obstack-ptr}, void *@var{data}, int @var{size}) +@deftypefun void obstack_grow0 (struct obstack *@var{obstack-ptr}, void *@var{data}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_grow0 @mtsrace:obstack-ptr @acucorrupt @acsmem @c (no sequence point between storing NUL and incrementing next_free) @@ -2325,7 +2325,7 @@ character. @c obstack_1grow @mtsrace:obstack-ptr @acucorrupt @acsmem @c _obstack_newchunk dup @mtsrace:obstack-ptr @acucorrupt @acsmem @c obstack_1grow_fast dup @mtsrace:obstack-ptr @acucorrupt @acsmem -To add one character at a time, use the function @code{obstack_1grow}. +To add one character at a time, use @code{obstack_1grow}. It adds a single byte containing @var{c} to the growing object. @end deftypefun @@ -2336,7 +2336,7 @@ It adds a single byte containing @var{c} to the growing object. @c obstack_ptr_grow @mtsrace:obstack-ptr @acucorrupt @acsmem @c _obstack_newchunk dup @mtsrace:obstack-ptr @acucorrupt @acsmem @c obstack_ptr_grow_fast dup @mtsrace:obstack-ptr -Adding the value of a pointer one can use the function +Adding the value of a pointer one can use @code{obstack_ptr_grow}. It adds @code{sizeof (void *)} bytes containing the value of @var{data}. @end deftypefun @@ -2348,8 +2348,8 @@ containing the value of @var{data}. @c obstack_int_grow @mtsrace:obstack-ptr @acucorrupt @acsmem @c _obstack_newchunk dup @mtsrace:obstack-ptr @acucorrupt @acsmem @c obstack_int_grow_fast dup @mtsrace:obstack-ptr -A single value of type @code{int} can be added by using the -@code{obstack_int_grow} function. It adds @code{sizeof (int)} bytes to +A single value of type @code{int} can be added by using +@code{obstack_int_grow}. It adds @code{sizeof (int)} bytes to the growing object and initializes them with the value of @var{data}. @end deftypefun @@ -2358,28 +2358,24 @@ the growing object and initializes them with the value of @var{data}. @deftypefun {void *} obstack_finish (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{}}} @c obstack_finish @mtsrace:obstack-ptr @acucorrupt -When you are finished growing the object, use the function +When you are finished growing the object, use @code{obstack_finish} to close it off and return its final address. Once you have finished the object, the obstack is available for ordinary allocation or for growing another object. - -This function can return a null pointer under the same conditions as -@code{obstack_alloc} (@pxref{Allocation in an Obstack}). @end deftypefun When you build an object by growing it, you will probably need to know afterward how long it became. You need not keep track of this as you grow -the object, because you can find out the length from the obstack just -before finishing the object with the function @code{obstack_object_size}, -declared as follows: +the object, because you can find out the length from the obstack +with @code{obstack_object_size}, before finishing the object. @comment obstack.h @comment GNU -@deftypefun int obstack_object_size (struct obstack *@var{obstack-ptr}) +@deftypefun size_t obstack_object_size (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acsafe{}} -This function returns the current size of the growing object, in bytes. -Remember to call this function @emph{before} finishing the object. +This macro returns the current size of the growing object, in bytes. +Remember to call @code{obstack_object_size} @emph{before} finishing the object. After it is finished, @code{obstack_object_size} will return zero. @end deftypefun @@ -2393,41 +2389,36 @@ obstack_free (obstack_ptr, obstack_finish (obstack_ptr)); @noindent This has no effect if no object was growing. -@cindex shrinking objects -You can use @code{obstack_blank} with a negative size argument to make -the current object smaller. Just don't try to shrink it beyond zero -length---there's no telling what will happen if you do that. - @node Extra Fast Growing @subsubsection Extra Fast Growing Objects @cindex efficiency and obstacks -The usual functions for growing objects incur overhead for checking +The usual macros for growing objects incur overhead for checking whether there is room for the new growth in the current chunk. If you are frequently constructing objects in small steps of growth, this overhead can be significant. You can reduce the overhead by using special ``fast growth'' -functions that grow the object without checking. In order to have a +macros that grow the object without checking. In order to have a robust program, you must do the checking yourself. If you do this checking in the simplest way each time you are about to add data to the object, you have not saved anything, because that is what the ordinary growth -functions do. But if you can arrange to check less often, or check +macros do. But if you can arrange to check less often, or check more efficiently, then you make the program faster. -The function @code{obstack_room} returns the amount of room available -in the current chunk. It is declared as follows: +@code{obstack_room} returns the amount of room available +in the current chunk. @comment obstack.h @comment GNU -@deftypefun int obstack_room (struct obstack *@var{obstack-ptr}) +@deftypefun size_t obstack_room (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acsafe{}} This returns the number of bytes that can be added safely to the current growing object (or to an object about to be started) in obstack -@var{obstack} using the fast growth functions. +@var{obstack} using the fast growth macros. @end deftypefun -While you know there is room, you can use these fast growth functions +While you know there is room, you can use these fast growth macros for adding data to a growing object: @comment obstack.h @@ -2436,7 +2427,7 @@ for adding data to a growing object: @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acunsafe{@acucorrupt{} @acsmem{}}} @c obstack_1grow_fast @mtsrace:obstack-ptr @acucorrupt @acsmem @c (no sequence point between copying c and incrementing next_free) -The function @code{obstack_1grow_fast} adds one byte containing the +@code{obstack_1grow_fast} adds one byte containing the character @var{c} to the growing object in obstack @var{obstack-ptr}. @end deftypefun @@ -2445,7 +2436,7 @@ character @var{c} to the growing object in obstack @var{obstack-ptr}. @deftypefun void obstack_ptr_grow_fast (struct obstack *@var{obstack-ptr}, void *@var{data}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acsafe{}} @c obstack_ptr_grow_fast @mtsrace:obstack-ptr -The function @code{obstack_ptr_grow_fast} adds @code{sizeof (void *)} +@code{obstack_ptr_grow_fast} adds @code{sizeof (void *)} bytes containing the value of @var{data} to the growing object in obstack @var{obstack-ptr}. @end deftypefun @@ -2455,41 +2446,41 @@ obstack @var{obstack-ptr}. @deftypefun void obstack_int_grow_fast (struct obstack *@var{obstack-ptr}, int @var{data}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acsafe{}} @c obstack_int_grow_fast @mtsrace:obstack-ptr -The function @code{obstack_int_grow_fast} adds @code{sizeof (int)} bytes +@code{obstack_int_grow_fast} adds @code{sizeof (int)} bytes containing the value of @var{data} to the growing object in obstack @var{obstack-ptr}. @end deftypefun @comment obstack.h @comment GNU -@deftypefun void obstack_blank_fast (struct obstack *@var{obstack-ptr}, int @var{size}) +@deftypefun void obstack_blank_fast (struct obstack *@var{obstack-ptr}, size_t @var{size}) @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acsafe{}} @c obstack_blank_fast @mtsrace:obstack-ptr -The function @code{obstack_blank_fast} adds @var{size} bytes to the +@code{obstack_blank_fast} adds @var{size} bytes to the growing object in obstack @var{obstack-ptr} without initializing them. @end deftypefun When you check for space using @code{obstack_room} and there is not -enough room for what you want to add, the fast growth functions +enough room for what you want to add, the fast growth macros are not safe. In this case, simply use the corresponding ordinary -growth function instead. Very soon this will copy the object to a +growth macro instead. Very soon this will copy the object to a new chunk; then there will be lots of room available again. -So, each time you use an ordinary growth function, check afterward for +So, each time you use an ordinary growth macro, check afterward for sufficient space using @code{obstack_room}. Once the object is copied to a new chunk, there will be plenty of space again, so the program will -start using the fast growth functions again. +start using the fast growth macros again. Here is an example: @smallexample @group void -add_string (struct obstack *obstack, const char *ptr, int len) +add_string (struct obstack *obstack, const char *ptr, size_t len) @{ while (len > 0) @{ - int room = obstack_room (obstack); + size_t room = obstack_room (obstack); if (room == 0) @{ /* @r{Not enough room. Add one character slowly,} @@ -2511,12 +2502,17 @@ add_string (struct obstack *obstack, const char *ptr, int len) @end group @end smallexample +@cindex shrinking objects +You can use @code{obstack_blank_fast} with a negative size argument to make +the current object smaller. Just don't try to shrink it beyond zero +length---there's no telling what will happen if you do that. + @node Status of an Obstack @subsubsection Status of an Obstack @cindex obstack status @cindex status of obstack -Here are functions that provide information on the current status of +Here are macros that provide information on the current status of allocation in an obstack. You can use them to learn about an object while still growing it. @@ -2524,7 +2520,7 @@ still growing it. @comment GNU @deftypefun {void *} obstack_base (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acsafe{}} -This function returns the tentative address of the beginning of the +This macro returns the tentative address of the beginning of the currently growing object in @var{obstack-ptr}. If you finish the object immediately, it will have that address. If you make it larger first, it may outgrow the current chunk---then its address will change! @@ -2538,7 +2534,7 @@ chunk). @comment GNU @deftypefun {void *} obstack_next_free (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{}@asunsafe{@asucorrupt{}}@acsafe{}} -This function returns the address of the first free byte in the current +This macro returns the address of the first free byte in the current chunk of obstack @var{obstack-ptr}. This is the end of the currently growing object. If no object is growing, @code{obstack_next_free} returns the same value as @code{obstack_base}. @@ -2546,14 +2542,14 @@ returns the same value as @code{obstack_base}. @comment obstack.h @comment GNU -@deftypefun int obstack_object_size (struct obstack *@var{obstack-ptr}) +@deftypefun size_t obstack_object_size (struct obstack *@var{obstack-ptr}) @c dup @safety{@prelim{}@mtsafe{@mtsrace{:obstack-ptr}}@assafe{}@acsafe{}} -This function returns the size in bytes of the currently growing object. +This macro returns the size in bytes of the currently growing object. This is equivalent to @smallexample -obstack_next_free (@var{obstack-ptr}) - obstack_base (@var{obstack-ptr}) +((size_t) obstack_next_free (@var{obstack-ptr}) - obstack_base (@var{obstack-ptr})) @end smallexample @end deftypefun @@ -2567,12 +2563,11 @@ specified boundary. By default, this boundary is aligned so that the object can hold any type of data. To access an obstack's alignment boundary, use the macro -@code{obstack_alignment_mask}, whose function prototype looks like -this: +@code{obstack_alignment_mask}. @comment obstack.h @comment GNU -@deftypefn Macro int obstack_alignment_mask (struct obstack *@var{obstack-ptr}) +@deftypefn Macro size_t obstack_alignment_mask (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} The value is a bit mask; a bit that is 1 indicates that the corresponding bit in the address of an object should be 0. The mask value should be one @@ -2640,7 +2635,7 @@ not to waste too much memory in the portion of the last chunk not yet used. @comment obstack.h @comment GNU -@deftypefn Macro int obstack_chunk_size (struct obstack *@var{obstack-ptr}) +@deftypefn Macro size_t obstack_chunk_size (struct obstack *@var{obstack-ptr}) @safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}} This returns the chunk size of the given obstack. @end deftypefn @@ -2659,25 +2654,37 @@ if (obstack_chunk_size (obstack_ptr) < @var{new-chunk-size}) @end smallexample @node Summary of Obstacks -@subsubsection Summary of Obstack Functions +@subsubsection Summary of Obstack Macros -Here is a summary of all the functions associated with obstacks. Each +Here is a summary of all the macros associated with obstacks. Each takes the address of an obstack (@code{struct obstack *}) as its first argument. @table @code -@item void obstack_init (struct obstack *@var{obstack-ptr}) +@item int obstack_init (struct obstack *@var{obstack-ptr}) Initialize use of an obstack. @xref{Creating Obstacks}. -@item void *obstack_alloc (struct obstack *@var{obstack-ptr}, int @var{size}) +@item int obstack_begin (struct obstack *@var{obstack-ptr}, size_t chunk_size) +Initialize use of an obstack, with an initial chunk of +@var{chunk_size} bytes. + +@item int obstack_specify_allocation (struct obstack *@var{obstack-ptr}, size_t chunk_size, size_t alignment, void *(*chunkfun) (size_t), void (*freefun) (void *)) +Initialize use of an obstack, specifying intial chunk size, chunk +alignment, and memory allocation functions. + +@item int obstack_specify_allocation_with_arg (struct obstack *@var{obstack-ptr}, size_t chunk_size, size_t alignment, void *(*chunkfun) (void *, size_t), void (*freefun) (void *, void *), void *arg) +Like @code{obstack_specify_allocation}, but specifying memory +allocation functions that take an extra first argument, @var{arg}. + +@item void *obstack_alloc (struct obstack *@var{obstack-ptr}, size_t @var{size}) Allocate an object of @var{size} uninitialized bytes. @xref{Allocation in an Obstack}. -@item void *obstack_copy (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +@item void *obstack_copy (struct obstack *@var{obstack-ptr}, void *@var{address}, size_t @var{size}) Allocate an object of @var{size} bytes, with contents copied from @var{address}. @xref{Allocation in an Obstack}. -@item void *obstack_copy0 (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +@item void *obstack_copy0 (struct obstack *@var{obstack-ptr}, void *@var{address}, size_t @var{size}) Allocate an object of @var{size}+1 bytes, with @var{size} of them copied from @var{address}, followed by a null character at the end. @xref{Allocation in an Obstack}. @@ -2686,15 +2693,15 @@ from @var{address}, followed by a null character at the end. Free @var{object} (and everything allocated in the specified obstack more recently than @var{object}). @xref{Freeing Obstack Objects}. -@item void obstack_blank (struct obstack *@var{obstack-ptr}, int @var{size}) +@item void obstack_blank (struct obstack *@var{obstack-ptr}, size_t @var{size}) Add @var{size} uninitialized bytes to a growing object. @xref{Growing Objects}. -@item void obstack_grow (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +@item void obstack_grow (struct obstack *@var{obstack-ptr}, void *@var{address}, size_t @var{size}) Add @var{size} bytes, copied from @var{address}, to a growing object. @xref{Growing Objects}. -@item void obstack_grow0 (struct obstack *@var{obstack-ptr}, void *@var{address}, int @var{size}) +@item void obstack_grow0 (struct obstack *@var{obstack-ptr}, void *@var{address}, size_t @var{size}) Add @var{size} bytes, copied from @var{address}, to a growing object, and then add another byte containing a null character. @xref{Growing Objects}. @@ -2707,11 +2714,11 @@ Add one byte containing @var{data-char} to a growing object. Finalize the object that is growing and return its permanent address. @xref{Growing Objects}. -@item int obstack_object_size (struct obstack *@var{obstack-ptr}) +@item size_t obstack_object_size (struct obstack *@var{obstack-ptr}) Get the current size of the currently growing object. @xref{Growing Objects}. -@item void obstack_blank_fast (struct obstack *@var{obstack-ptr}, int @var{size}) +@item void obstack_blank_fast (struct obstack *@var{obstack-ptr}, size_t @var{size}) Add @var{size} uninitialized bytes to a growing object without checking that there is enough room. @xref{Extra Fast Growing}. @@ -2719,15 +2726,15 @@ that there is enough room. @xref{Extra Fast Growing}. Add one byte containing @var{data-char} to a growing object without checking that there is enough room. @xref{Extra Fast Growing}. -@item int obstack_room (struct obstack *@var{obstack-ptr}) +@item size_t obstack_room (struct obstack *@var{obstack-ptr}) Get the amount of room now available for growing the current object. @xref{Extra Fast Growing}. -@item int obstack_alignment_mask (struct obstack *@var{obstack-ptr}) +@item size_t obstack_alignment_mask (struct obstack *@var{obstack-ptr}) The mask used for aligning the beginning of an object. This is an lvalue. @xref{Obstacks Data Alignment}. -@item int obstack_chunk_size (struct obstack *@var{obstack-ptr}) +@item size_t obstack_chunk_size (struct obstack *@var{obstack-ptr}) The size for allocating chunks. This is an lvalue. @xref{Obstack Chunks}. @item void *obstack_base (struct obstack *@var{obstack-ptr})