diff mbox

[1/5] obstack tidy

Message ID 1406354233-7664-2-git-send-email-amodra@gmail.com
State Superseded
Headers show

Commit Message

Alan Modra July 26, 2014, 5:57 a.m. UTC
a) Delete nonsense about "not polluting the namespace with stddef.h
symbols" since string.h includes stddef.h a little later anyway.
b) Don't roll our own slow memcpy in _obstack_newchunk.
c) Rename obstack_free to _obstack_free.  This makes the naming consistent
   with other obstack functions and obviates the need for __obstack_free.
   Ancient obstack.c defined both obstack_free and _obstack_free.  We
   continue to do that for _LIBC via an alias.
d) Miscellaneous macro fixes.  The expression used to test for gcc-2.8 is
   clever, but will give a warning nowadays if simulating an old gcc with
   -U__GNUC__ -U__GNUC_MINOR__ -D__GNUC__=1.
e) Move error handling code, to avoid a forward declaration and to
   simplify later patches in this series.

	* lib/obstack.h: Include stddef.h unconditionally and stdlib.h earlier.
	(PTR_INT_TYPE): Delete, replace with ptrdiff_t.
	(struct obstack <temp>): Rename fields of union and update all uses.
	(__obstack_free): Delete, update refs.
	(_obstack_free): Rename from obstack_free.
	(__extension__): Avoid undefined macro warning for __GNUC_MINOR__.
	(obstack_object_size, obstack_room): Parenthesise !__GNUC__ versions.
	* lib/obstack.c: Don't include stddef.h.
	(COPYING_UNIT): Delete.
	(_obstack_newchunk): Use memcpy to move existing object to new chunk.
	(_obstack_free): Rename from __obstack_free, update alias.
	(obstack_exit_failure, obstack_alloc_failed_handler, _obstack_compat):
	Move later in file.
---
 lib/obstack.c |   97 ++++++++++++++++++++-------------------------------------
 lib/obstack.h |   91 ++++++++++++++++++++++-------------------------------
 2 files changed, 71 insertions(+), 117 deletions(-)

Comments

Roland McGrath July 28, 2014, 7:31 p.m. UTC | #1
> a) Delete nonsense about "not polluting the namespace with stddef.h
> symbols" since string.h includes stddef.h a little later anyway.

If you are talking specifically about the glibc implementation's string.h,
then you are confused.  glibc's string.h complies with the C and POSIX
standards, and so does not pollute the namespace with all of stddef.h's
names.  It only defines size_t and NULL via stddef.h.  If you also want
ptrdiff_t for use in obstack.h, with GCC's stddef.h you can do:
	#define __need_ptrdiff_t
	#include <stddef.h>

That said, I don't think anybody actually cares about a GNU extension
header like obstack.h implicitly defining common standard C symbols like
that ones that stddef.h defines.
Alan Modra July 28, 2014, 11:31 p.m. UTC | #2
On Mon, Jul 28, 2014 at 12:31:00PM -0700, Roland McGrath wrote:
> > a) Delete nonsense about "not polluting the namespace with stddef.h
> > symbols" since string.h includes stddef.h a little later anyway.
> 
> If you are talking specifically about the glibc implementation's string.h,
> then you are confused.

No, I was talking about gnulib's string.h.

>  glibc's string.h complies with the C and POSIX
> standards, and so does not pollute the namespace with all of stddef.h's
> names.  It only defines size_t and NULL via stddef.h.  If you also want
> ptrdiff_t for use in obstack.h, with GCC's stddef.h you can do:
> 	#define __need_ptrdiff_t
> 	#include <stddef.h>
> 
> That said, I don't think anybody actually cares about a GNU extension
> header like obstack.h implicitly defining common standard C symbols like
> that ones that stddef.h defines.

Right.
diff mbox

Patch

diff --git a/lib/obstack.c b/lib/obstack.c
index 598f6aa..f7cd4e5 100644
--- a/lib/obstack.c
+++ b/lib/obstack.c
@@ -47,12 +47,11 @@ 
 # endif
 #endif
 
-#include <stddef.h>
-
 #ifndef ELIDE_CODE
 
 
 # include <stdint.h>
+# include <stdlib.h>
 
 /* Determine default alignment.  */
 union fooround
@@ -75,42 +74,6 @@  enum
   DEFAULT_ROUNDING = sizeof (union fooround)
 };
 
-/* When we copy a long block of data, this is the unit to do it with.
-   On some machines, copying successive ints does not work;
-   in such a case, redefine COPYING_UNIT to 'long' (if that works)
-   or 'char' as a last resort.  */
-# ifndef COPYING_UNIT
-#  define COPYING_UNIT int
-# endif
-
-
-/* The functions allocating more room by calling 'obstack_chunk_alloc'
-   jump to the handler pointed to by 'obstack_alloc_failed_handler'.
-   This can be set to a user defined function which should either
-   abort gracefully or use longjump - but shouldn't return.  This
-   variable by default points to the internal function
-   'print_and_abort'.  */
-static _Noreturn void print_and_abort (void);
-void (*obstack_alloc_failed_handler) (void) = print_and_abort;
-
-/* Exit value used when 'print_and_abort' is used.  */
-# include <stdlib.h>
-# ifdef _LIBC
-int obstack_exit_failure = EXIT_FAILURE;
-# else
-#  include "exitfail.h"
-#  define obstack_exit_failure exit_failure
-# endif
-
-# ifdef _LIBC
-#  if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_3_4)
-/* A looong time ago (before 1994, anyway; we're not sure) this global variable
-   was used by non-GNU-C macros to avoid multiple evaluation.  The GNU C
-   library still exports it because somebody might use it.  */
-struct obstack *_obstack_compat = 0;
-compat_symbol (libc, _obstack_compat, _obstack, GLIBC_2_0);
-#  endif
-# endif
 
 /* Define a macro that either calls functions with the traditional malloc/free
    calling interface, or calls functions with the mmalloc/mfree interface
@@ -248,8 +211,6 @@  _obstack_newchunk (struct obstack *h, int length)
   struct _obstack_chunk *new_chunk;
   long new_size;
   long obj_size = h->next_free - h->object_base;
-  long i;
-  long already;
   char *object_base;
 
   /* Compute size for new chunk.  */
@@ -269,25 +230,8 @@  _obstack_newchunk (struct obstack *h, int length)
   object_base =
     __PTR_ALIGN ((char *) new_chunk, new_chunk->contents, h->alignment_mask);
 
-  /* Move the existing object to the new chunk.
-     Word at a time is fast and is safe if the object
-     is sufficiently aligned.  */
-  if (h->alignment_mask + 1 >= DEFAULT_ALIGNMENT)
-    {
-      for (i = obj_size / sizeof (COPYING_UNIT) - 1;
-           i >= 0; i--)
-        ((COPYING_UNIT *) object_base)[i]
-          = ((COPYING_UNIT *) h->object_base)[i];
-      /* We used to copy the odd few remaining bytes as one extra COPYING_UNIT,
-         but that can cross a page boundary on a machine
-         which does not do strict alignment for COPYING_UNITS.  */
-      already = obj_size / sizeof (COPYING_UNIT) * sizeof (COPYING_UNIT);
-    }
-  else
-    already = 0;
-  /* Copy remaining bytes one by one.  */
-  for (i = already; i < obj_size; i++)
-    object_base[i] = h->object_base[i];
+  /* Move the existing object to the new chunk.  */
+  memcpy (object_base, h->object_base, obj_size);
 
   /* If the object just copied was the only data in OLD_CHUNK,
      free that chunk and remove it from the chain.
@@ -342,7 +286,7 @@  _obstack_allocated_p (struct obstack *h, void *obj)
 # undef obstack_free
 
 void
-__obstack_free (struct obstack *h, void *obj)
+_obstack_free (struct obstack *h, void *obj)
 {
   struct _obstack_chunk *lp;    /* below addr of any objects in this chunk */
   struct _obstack_chunk *plp;   /* point to previous chunk if any */
@@ -370,11 +314,9 @@  __obstack_free (struct obstack *h, void *obj)
     /* obj is not in any of the chunks! */
     abort ();
 }
-
 # ifdef _LIBC
-/* Older versions of libc used a function _obstack_free intended to be
-   called by non-GCC compilers.  */
-strong_alias (obstack_free, _obstack_free)
+/* Older versions of libc defined both _obstack_free and obstack_free.  */
+strong_alias (_obstack_free, obstack_free)
 # endif
 
 int
@@ -391,6 +333,15 @@  _obstack_memory_used (struct obstack *h)
 }
 
 /* Define the error handler.  */
+
+/* Exit value used when 'print_and_abort' is used.  */
+# ifdef _LIBC
+int obstack_exit_failure = EXIT_FAILURE;
+# else
+#  include "exitfail.h"
+#  define obstack_exit_failure exit_failure
+# endif
+
 # ifdef _LIBC
 #  include <libintl.h>
 # else
@@ -420,4 +371,22 @@  print_and_abort (void)
   exit (obstack_exit_failure);
 }
 
+/* The functions allocating more room by calling 'obstack_chunk_alloc'
+   jump to the handler pointed to by 'obstack_alloc_failed_handler'.
+   This can be set to a user defined function which should either
+   abort gracefully or use longjump - but shouldn't return.  This
+   variable by default points to the internal function
+   'print_and_abort'.  */
+void (*obstack_alloc_failed_handler) (void) = print_and_abort;
+
+# ifdef _LIBC
+#  if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_3_4)
+/* A looong time ago (before 1994, anyway; we're not sure) this global variable
+   was used by non-GNU-C macros to avoid multiple evaluation.  The GNU C
+   library still exports it because somebody might use it.  */
+struct obstack *_obstack_compat = 0;
+compat_symbol (libc, _obstack_compat, _obstack, GLIBC_2_0);
+#  endif
+# endif
+
 #endif  /* !ELIDE_CODE */
diff --git a/lib/obstack.h b/lib/obstack.h
index f92492f..413c7a3 100644
--- a/lib/obstack.h
+++ b/lib/obstack.h
@@ -104,17 +104,7 @@ 
 #ifndef _OBSTACK_H
 #define _OBSTACK_H 1
 
-/* We need the type of a pointer subtraction.  If __PTRDIFF_TYPE__ is
-   defined, as with GNU C, use that; that way we don't pollute the
-   namespace with <stddef.h>'s symbols.  Otherwise, include <stddef.h>
-   and use ptrdiff_t.  */
-
-#ifdef __PTRDIFF_TYPE__
-# define PTR_INT_TYPE __PTRDIFF_TYPE__
-#else
-# include <stddef.h>
-# define PTR_INT_TYPE ptrdiff_t
-#endif
+#include <stddef.h>
 
 /* If B is the base of an object addressed by P, return the result of
    aligning P to the next multiple of A + 1.  B and P must be of type
@@ -122,15 +112,15 @@ 
 
 #define __BPTR_ALIGN(B, P, A) ((B) + (((P) - (B) + (A)) & ~(A)))
 
-/* Similar to _BPTR_ALIGN (B, P, A), except optimize the common case
+/* Similar to __BPTR_ALIGN (B, P, A), except optimize the common case
    where pointers can be converted to integers, aligned as integers,
-   and converted back again.  If PTR_INT_TYPE is narrower than a
+   and converted back again.  If ptrdiff_t is narrower than a
    pointer (e.g., the AS/400), play it safe and compute the alignment
    relative to B.  Otherwise, use the faster strategy of computing the
    alignment relative to 0.  */
 
 #define __PTR_ALIGN(B, P, A)						      \
-  __BPTR_ALIGN (sizeof (PTR_INT_TYPE) < sizeof (void *) ? (B) : (char *) 0, \
+  __BPTR_ALIGN (sizeof (ptrdiff_t) < sizeof (void *) ? (B) : (char *) 0,      \
                 P, A)
 
 #include <string.h>
@@ -159,8 +149,8 @@  struct obstack          /* control current object in current chunk */
   char *chunk_limit;            /* address of char after current chunk */
   union
   {
-    PTR_INT_TYPE tempint;
-    void *tempptr;
+    ptrdiff_t i;
+    void *p;
   } temp;                       /* Temporary for some macros.  */
   int alignment_mask;           /* Mask of alignment for each object. */
   /* These prototypes vary based on 'use_extra_arg', and we use
@@ -182,6 +172,7 @@  struct obstack          /* control current object in current chunk */
 /* Declare the external functions we use; they are in obstack.c.  */
 
 extern void _obstack_newchunk (struct obstack *, int);
+extern void _obstack_free (struct obstack *, void *);
 extern int _obstack_begin (struct obstack *, int, int,
                            void *(*)(long), void (*)(void *));
 extern int _obstack_begin_1 (struct obstack *, int, int,
@@ -189,13 +180,6 @@  extern int _obstack_begin_1 (struct obstack *, int, int,
                              void (*)(void *, void *), void *);
 extern int _obstack_memory_used (struct obstack *) __attribute_pure__;
 
-/* The default name of the function for freeing a chunk is 'obstack_free',
-   but gnulib users can override this by defining '__obstack_free'.  */
-#ifndef __obstack_free
-# define __obstack_free obstack_free
-#endif
-extern void __obstack_free (struct obstack *, void *);
-
 
 /* Error handler called when 'obstack_chunk_alloc' failed to allocate
    more memory.  This can be set to a user defined function which
@@ -258,7 +242,7 @@  extern int obstack_exit_failure;
 #define obstack_memory_used(h) _obstack_memory_used (h)
 
 #if defined __GNUC__
-# if ! (2 < __GNUC__ + (8 <= __GNUC_MINOR__))
+# if !defined __GNUC_MINOR__ || __GNUC__ * 1000 + __GNUC_MINOR__ < 2008
 #  define __extension__
 # endif
 
@@ -406,15 +390,16 @@  extern int obstack_exit_failure;
        void *__obj = (OBJ);						      \
        if (__obj > (void *) __o->chunk && __obj < (void *) __o->chunk_limit)  \
          __o->next_free = __o->object_base = (char *) __obj;		      \
-       else (__obstack_free) (__o, __obj); })
+       else								      \
+         _obstack_free (__o, __obj); })
 
 #else /* not __GNUC__ */
 
-# define obstack_object_size(h) \
-  (unsigned) ((h)->next_free - (h)->object_base)
+# define obstack_object_size(h)						      \
+  ((unsigned) ((h)->next_free - (h)->object_base))
 
 # define obstack_room(h)						      \
-  (unsigned) ((h)->chunk_limit - (h)->next_free)
+  ((unsigned) ((h)->chunk_limit - (h)->next_free))
 
 # define obstack_empty_p(h) \
   ((h)->chunk->prev == 0						      \
@@ -429,23 +414,23 @@  extern int obstack_exit_failure;
    but some compilers won't accept it.  */
 
 # define obstack_make_room(h, length)					      \
-  ((h)->temp.tempint = (length),					      \
-   (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit)		      \
-   ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0))
+  ((h)->temp.i = (length),						      \
+   (((h)->next_free + (h)->temp.i > (h)->chunk_limit)			      \
+   ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0))
 
 # define obstack_grow(h, where, length)					      \
-  ((h)->temp.tempint = (length),					      \
-   (((h)->next_free + (h)->temp.tempint > (h)->chunk_limit)		      \
-   ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0),		      \
-   memcpy ((h)->next_free, where, (h)->temp.tempint),			      \
-   (h)->next_free += (h)->temp.tempint)
+  ((h)->temp.i = (length),						      \
+   (((h)->next_free + (h)->temp.i > (h)->chunk_limit)			      \
+   ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0),			      \
+   memcpy ((h)->next_free, where, (h)->temp.i),				      \
+   (h)->next_free += (h)->temp.i)
 
 # define obstack_grow0(h, where, length)				      \
-  ((h)->temp.tempint = (length),					      \
-   (((h)->next_free + (h)->temp.tempint + 1 > (h)->chunk_limit)		      \
-   ? (_obstack_newchunk ((h), (h)->temp.tempint + 1), 0) : 0),		      \
-   memcpy ((h)->next_free, where, (h)->temp.tempint),			      \
-   (h)->next_free += (h)->temp.tempint,					      \
+  ((h)->temp.i = (length),						      \
+   (((h)->next_free + (h)->temp.i + 1 > (h)->chunk_limit)		      \
+   ? (_obstack_newchunk ((h), (h)->temp.i + 1), 0) : 0),		      \
+   memcpy ((h)->next_free, where, (h)->temp.i),				      \
+   (h)->next_free += (h)->temp.i,					      \
    *((h)->next_free)++ = 0)
 
 # define obstack_1grow(h, datum)					      \
@@ -470,10 +455,10 @@  extern int obstack_exit_failure;
   (((int *) ((h)->next_free += sizeof (int)))[-1] = (aint))
 
 # define obstack_blank(h, length)					      \
-  ((h)->temp.tempint = (length),					      \
-   (((h)->chunk_limit - (h)->next_free < (h)->temp.tempint)		      \
-   ? (_obstack_newchunk ((h), (h)->temp.tempint), 0) : 0),		      \
-   obstack_blank_fast (h, (h)->temp.tempint))
+  ((h)->temp.i = (length),						      \
+   (((h)->chunk_limit - (h)->next_free < (h)->temp.i)			      \
+   ? (_obstack_newchunk ((h), (h)->temp.i), 0) : 0),			      \
+   obstack_blank_fast (h, (h)->temp.i))
 
 # define obstack_alloc(h, length)					      \
   (obstack_blank ((h), (length)), obstack_finish ((h)))
@@ -488,7 +473,7 @@  extern int obstack_exit_failure;
   (((h)->next_free == (h)->object_base					      \
     ? (((h)->maybe_empty_object = 1), 0)				      \
     : 0),								      \
-   (h)->temp.tempptr = (h)->object_base,				      \
+   (h)->temp.p = (h)->object_base,					      \
    (h)->next_free							      \
      = __PTR_ALIGN ((h)->object_base, (h)->next_free,			      \
                     (h)->alignment_mask),				      \
@@ -496,15 +481,15 @@  extern int obstack_exit_failure;
      > (h)->chunk_limit - (char *) (h)->chunk)				      \
    ? ((h)->next_free = (h)->chunk_limit) : 0),				      \
    (h)->object_base = (h)->next_free,					      \
-   (h)->temp.tempptr)
+   (h)->temp.p)
 
 # define obstack_free(h, obj)						      \
-  ((h)->temp.tempint = (char *) (obj) - (char *) (h)->chunk,		      \
-   ((((h)->temp.tempint > 0						      \
-      && (h)->temp.tempint < (h)->chunk_limit - (char *) (h)->chunk))	      \
+  ((h)->temp.i = (char *) (obj) - (char *) (h)->chunk,			      \
+   ((((h)->temp.i > 0							      \
+      && (h)->temp.i < (h)->chunk_limit - (char *) (h)->chunk))		      \
     ? (void) ((h)->next_free = (h)->object_base				      \
-                          = (h)->temp.tempint + (char *) (h)->chunk)	      \
-    : (__obstack_free) (h, (h)->temp.tempint + (char *) (h)->chunk)))
+                          = (h)->temp.i + (char *) (h)->chunk)		      \
+    : _obstack_free (h, (h)->temp.i + (char *) (h)->chunk)))
 
 #endif /* not __GNUC__ */
 
@@ -512,4 +497,4 @@  extern int obstack_exit_failure;
 }       /* C++ */
 #endif
 
-#endif /* obstack.h */
+#endif /* _OBSTACK_H */