Add macros to allocate temporary Lisp objects with alloca.
Respect MAX_ALLOCA and fall back to regular GC for large objects. * character.h (parse_str_as_multibyte): Move prototype to ... * lisp.h (parse_str_as_multibyte): ... here. (struct Lisp_Cons): Add GCALIGNED attribute if supported. (scoped_cons, scoped_list2, build_local_vector, build_local_string): New macros. (scoped_cons_init, pointer_valid_for_lisp_object, local_vector_init) (local_string_init): New functions. * alloc.c (verify_alloca) [ENABLE_CHECKING]: New function. (init_alloc_once): Call it.
This commit is contained in:
Dmitry Antipov
parent
80465f41d7
commit
c7dfea947e
4 changed files with 158 additions and 5 deletions
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@ -5,6 +5,18 @@
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(x_delete_terminal): Do not close X connection fd (Bug#18403).
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Add eassert and mark dpyinfo as dead only if it was alive.
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Add macros to allocate temporary Lisp objects with alloca.
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Respect MAX_ALLOCA and fall back to regular GC for large objects.
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* character.h (parse_str_as_multibyte): Move prototype to ...
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* lisp.h (parse_str_as_multibyte): ... here.
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(struct Lisp_Cons): Add GCALIGNED attribute if supported.
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(scoped_cons, scoped_list2, build_local_vector, build_local_string):
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New macros.
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(scoped_cons_init, pointer_valid_for_lisp_object, local_vector_init)
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(local_string_init): New functions.
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* alloc.c (verify_alloca) [ENABLE_CHECKING]: New function.
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(init_alloc_once): Call it.
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2014-09-08 Eli Zaretskii <eliz@gnu.org>
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* dispnew.c (prepare_desired_row): When MODE_LINE_P is zero,
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27
src/alloc.c
27
src/alloc.c
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@ -7117,8 +7117,29 @@ die (const char *msg, const char *file, int line)
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file, line, msg);
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terminate_due_to_signal (SIGABRT, INT_MAX);
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}
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#endif
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/* Stress alloca with inconveniently sized requests and check
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whether all allocated areas may be used for Lisp_Object. */
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NO_INLINE static void
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verify_alloca (void)
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{
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int i;
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enum { ALLOCA_CHECK_MAX = 256 };
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/* Start from size of the smallest Lisp object. */
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for (i = sizeof (struct Lisp_Cons); i <= ALLOCA_CHECK_MAX; i++)
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{
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char *ptr = alloca (i);
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eassert (pointer_valid_for_lisp_object (ptr));
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}
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}
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#else /* not ENABLE_CHECKING */
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#define verify_alloca() ((void) 0)
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#endif /* ENABLE_CHECKING */
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/* Initialization. */
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void
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@ -7128,6 +7149,8 @@ init_alloc_once (void)
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purebeg = PUREBEG;
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pure_size = PURESIZE;
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verify_alloca ();
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#if GC_MARK_STACK || defined GC_MALLOC_CHECK
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mem_init ();
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Vdead = make_pure_string ("DEAD", 4, 4, 0);
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@ -644,8 +644,6 @@ extern int string_char (const unsigned char *,
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const unsigned char **, int *);
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extern int translate_char (Lisp_Object, int c);
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extern void parse_str_as_multibyte (const unsigned char *,
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ptrdiff_t, ptrdiff_t *, ptrdiff_t *);
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extern ptrdiff_t count_size_as_multibyte (const unsigned char *, ptrdiff_t);
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extern ptrdiff_t str_as_multibyte (unsigned char *, ptrdiff_t, ptrdiff_t,
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ptrdiff_t *);
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122
src/lisp.h
122
src/lisp.h
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@ -298,6 +298,13 @@ error !;
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# endif
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#endif
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/* Stolen from gnulib. */
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#if (__GNUC__ || __HP_cc || __HP_aCC || __IBMC__ \
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|| __IBMCPP__ || __ICC || 0x5110 <= __SUNPRO_C)
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#define GCALIGNED __attribute__ ((aligned (GCALIGNMENT)))
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#else
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#define GCALIGNED /* empty */
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#endif
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/* Some operations are so commonly executed that they are implemented
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as macros, not functions, because otherwise runtime performance would
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@ -1016,7 +1023,7 @@ LISP_MACRO_DEFUN_VOID (CHECK_TYPE,
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typedef struct interval *INTERVAL;
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struct Lisp_Cons
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struct GCALIGNED Lisp_Cons
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{
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/* Car of this cons cell. */
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Lisp_Object car;
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@ -3622,6 +3629,10 @@ extern void syms_of_xsettings (void);
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/* Defined in vm-limit.c. */
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extern void memory_warnings (void *, void (*warnfun) (const char *));
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/* Defined in character.c. */
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extern void parse_str_as_multibyte (const unsigned char *, ptrdiff_t,
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ptrdiff_t *, ptrdiff_t *);
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/* Defined in alloc.c. */
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extern void check_pure_size (void);
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extern void free_misc (Lisp_Object);
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@ -4535,6 +4546,115 @@ extern void *record_xmalloc (size_t) ATTRIBUTE_ALLOC_SIZE ((1));
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memory_full (SIZE_MAX); \
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} while (false)
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/* Use the following functions to allocate temporary (function-
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or block-scoped) conses, vectors, and strings. These objects
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are not managed by GC, and passing them out of their scope
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most likely causes an immediate crash at next GC. */
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#if (__GNUC__ || __HP_cc || __HP_aCC || __IBMC__ \
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|| __IBMCPP__ || __ICC || 0x5110 <= __SUNPRO_C)
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/* Allocate temporary block-scoped cons. This version assumes
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that stack-allocated Lisp_Cons is always aligned properly. */
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#define scoped_cons(car, cdr) \
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make_lisp_ptr (&((struct Lisp_Cons) { car, { cdr } }), Lisp_Cons)
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#else /* not __GNUC__ etc... */
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/* Helper function for an alternate scoped cons, see below. */
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INLINE Lisp_Object
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scoped_cons_init (void *ptr, Lisp_Object x, Lisp_Object y)
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{
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struct Lisp_Cons *c = (struct Lisp_Cons *)
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(((uintptr_t) ptr + (GCALIGNMENT - 1)) & ~(GCALIGNMENT - 1));
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c->car = x;
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c->u.cdr = y;
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return make_lisp_ptr (c, Lisp_Cons);
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}
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/* This version uses explicit alignment. */
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#define scoped_cons(car, cdr) \
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scoped_cons_init ((char[sizeof (struct Lisp_Cons) \
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+ (GCALIGNMENT - 1)]) {}, (car), (cdr))
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#endif /* __GNUC__ etc... */
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/* Convenient utility macro similar to list2. */
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#define scoped_list2(x, y) scoped_cons (x, scoped_cons (y, Qnil))
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/* True if Lisp_Object may be placed at P. Used only
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under ENABLE_CHECKING and optimized away otherwise. */
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INLINE bool
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pointer_valid_for_lisp_object (void *p)
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{
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uintptr_t v = (uintptr_t) p;
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return !(USE_LSB_TAG ? (v & ~VALMASK) : v >> VALBITS);
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}
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/* Helper function for build_local_vector, see below. */
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INLINE Lisp_Object
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local_vector_init (uintptr_t addr, ptrdiff_t length, Lisp_Object init)
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{
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ptrdiff_t i;
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struct Lisp_Vector *v = (struct Lisp_Vector *) addr;
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eassert (pointer_valid_for_lisp_object (v));
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v->header.size = length;
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for (i = 0; i < length; i++)
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v->contents[i] = init;
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return make_lisp_ptr (v, Lisp_Vectorlike);
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}
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/* If size permits, create temporary function-scoped vector OBJ of
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length SIZE, with each element being INIT. Otherwise create
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regular GC-managed vector. */
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#define build_local_vector(obj, size, init) \
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(MAX_ALLOCA < (size) * word_size + header_size \
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? obj = Fmake_vector (make_number (size), (init)) \
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: (obj = XIL ((uintptr_t) alloca \
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((size) * word_size + header_size)), \
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obj = local_vector_init ((uintptr_t) XLI (obj), (size), (init))))
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/* Helper function for build_local_string, see below. */
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INLINE Lisp_Object
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local_string_init (uintptr_t addr, const char *data, ptrdiff_t size)
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{
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ptrdiff_t nchars, nbytes;
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struct Lisp_String *s = (struct Lisp_String *) addr;
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eassert (pointer_valid_for_lisp_object (s));
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parse_str_as_multibyte ((const unsigned char *) data,
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size, &nchars, &nbytes);
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s->data = (unsigned char *) (addr + sizeof *s);
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s->intervals = NULL;
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memcpy (s->data, data, size);
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s->data[size] = '\0';
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if (size == nchars || size != nbytes)
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s->size = size, s->size_byte = -1;
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else
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s->size = nchars, s->size_byte = nbytes;
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return make_lisp_ptr (s, Lisp_String);
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}
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/* If size permits, create temporary function-scoped string OBJ
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with contents DATA of length NBYTES. Otherwise create regular
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GC-managed string. */
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#define build_local_string(obj, data, nbytes) \
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(MAX_ALLOCA < (nbytes) + sizeof (struct Lisp_String) \
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? obj = make_string ((data), (nbytes)) \
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: (obj = XIL ((uintptr_t) alloca \
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((nbytes) + sizeof (struct Lisp_String))), \
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obj = local_string_init ((uintptr_t) XLI (obj), data, nbytes)))
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/* Loop over all tails of a list, checking for cycles.
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FIXME: Make tortoise and n internal declarations.
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FIXME: Unroll the loop body so we don't need `n'. */
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