mirrored from git://git.sv.gnu.org/emacs.git
/
lisp.h
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lisp.h
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/* Fundamental definitions for GNU Emacs Lisp interpreter. -*- coding: utf-8 -*-
Copyright (C) 1985-2024 Free Software Foundation, Inc.
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or (at
your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
#ifndef EMACS_LISP_H
#define EMACS_LISP_H
#include <alloca.h>
#include <setjmp.h>
#include <stdarg.h>
#include <stdckdint.h>
#include <stddef.h>
#include <string.h>
#include <float.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#include <attribute.h>
#include <byteswap.h>
#include <count-leading-zeros.h>
#include <intprops.h>
#include <verify.h>
INLINE_HEADER_BEGIN
/* Define a TYPE constant ID as an externally visible name. Use like this:
DEFINE_GDB_SYMBOL_BEGIN (TYPE, ID)
# define ID (some integer preprocessor expression of type TYPE)
DEFINE_GDB_SYMBOL_END (ID)
This hack is for the benefit of compilers that do not make macro
definitions or enums visible to the debugger. It's used for symbols
that .gdbinit needs. */
#define DECLARE_GDB_SYM(type, id) type const id EXTERNALLY_VISIBLE
#ifdef MAIN_PROGRAM
# define DEFINE_GDB_SYMBOL_BEGIN(type, id) DECLARE_GDB_SYM (type, id)
# define DEFINE_GDB_SYMBOL_END(id) = id;
#else
# define DEFINE_GDB_SYMBOL_BEGIN(type, id) extern DECLARE_GDB_SYM (type, id)
# define DEFINE_GDB_SYMBOL_END(val) ;
#endif
/* The ubiquitous max and min macros. */
#undef min
#undef max
#define max(a, b) ((a) > (b) ? (a) : (b))
#define min(a, b) ((a) < (b) ? (a) : (b))
/* Number of elements in an array. */
#define ARRAYELTS(arr) (sizeof (arr) / sizeof (arr)[0])
/* Number of bits in a Lisp_Object tag. */
DEFINE_GDB_SYMBOL_BEGIN (int, GCTYPEBITS)
#define GCTYPEBITS 3
DEFINE_GDB_SYMBOL_END (GCTYPEBITS)
/* EMACS_INT - signed integer wide enough to hold an Emacs value
EMACS_INT_WIDTH - width in bits of EMACS_INT
EMACS_INT_MAX - maximum value of EMACS_INT; can be used in #if
pI - printf length modifier for EMACS_INT
EMACS_UINT - unsigned variant of EMACS_INT */
#ifndef EMACS_INT_MAX
# if INTPTR_MAX <= 0
# error "INTPTR_MAX misconfigured"
# elif INTPTR_MAX <= INT_MAX && !defined WIDE_EMACS_INT
typedef int EMACS_INT;
typedef unsigned int EMACS_UINT;
enum { EMACS_INT_WIDTH = INT_WIDTH, EMACS_UINT_WIDTH = UINT_WIDTH };
# define EMACS_INT_MAX INT_MAX
# define pI ""
# elif INTPTR_MAX <= LONG_MAX && !defined WIDE_EMACS_INT
typedef long int EMACS_INT;
typedef unsigned long EMACS_UINT;
enum { EMACS_INT_WIDTH = LONG_WIDTH, EMACS_UINT_WIDTH = ULONG_WIDTH };
# define EMACS_INT_MAX LONG_MAX
# define pI "l"
# elif INTPTR_MAX <= LLONG_MAX
typedef long long int EMACS_INT;
typedef unsigned long long int EMACS_UINT;
enum { EMACS_INT_WIDTH = LLONG_WIDTH, EMACS_UINT_WIDTH = ULLONG_WIDTH };
# define EMACS_INT_MAX LLONG_MAX
/* MinGW supports %lld only if __USE_MINGW_ANSI_STDIO is non-zero,
which is arranged by config.h, and (for mingw.org) if GCC is 6.0 or
later and the runtime version is 5.0.0 or later. Otherwise,
printf-like functions are declared with __ms_printf__ attribute,
which will cause a warning for %lld etc. */
# if defined __MINGW32__ \
&& (!defined __USE_MINGW_ANSI_STDIO \
|| (!defined MINGW_W64 \
&& !(GNUC_PREREQ (6, 0, 0) && __MINGW32_MAJOR_VERSION >= 5)))
# define pI "I64"
# else /* ! MinGW */
# define pI "ll"
# endif
# else
# error "INTPTR_MAX too large"
# endif
#endif
/* Number of bits to put in each character in the internal representation
of bool vectors. This should not vary across implementations. */
enum { BOOL_VECTOR_BITS_PER_CHAR =
#define BOOL_VECTOR_BITS_PER_CHAR 8
BOOL_VECTOR_BITS_PER_CHAR
};
/* An unsigned integer type representing a fixed-length bit sequence,
suitable for bool vector words, GC mark bits, etc. Normally it is size_t
for speed, but on weird platforms it is unsigned char and not all
its bits are used. */
#if BOOL_VECTOR_BITS_PER_CHAR == CHAR_BIT
typedef size_t bits_word;
# define BITS_WORD_MAX SIZE_MAX
enum { BITS_PER_BITS_WORD = SIZE_WIDTH };
#else
typedef unsigned char bits_word;
# define BITS_WORD_MAX ((1u << BOOL_VECTOR_BITS_PER_CHAR) - 1)
enum { BITS_PER_BITS_WORD = BOOL_VECTOR_BITS_PER_CHAR };
#endif
verify (BITS_WORD_MAX >> (BITS_PER_BITS_WORD - 1) == 1);
/* Use pD to format ptrdiff_t values, which suffice for indexes into
buffers and strings. Emacs never allocates objects larger than
PTRDIFF_MAX bytes, as they cause problems with pointer subtraction.
In C99, pD can always be "t", as we no longer need to worry about
pre-C99 libraries such as glibc 2.0 (1997) and Solaris 8 (2000). */
#define pD "t"
/* Convenience macro for rarely-used functions that do not return. */
#define AVOID _Noreturn ATTRIBUTE_COLD void
/* Extra internal type checking? */
/* Define Emacs versions of <assert.h>'s 'assert (COND)' and <verify.h>'s
'assume (COND)'. COND should be free of side effects, as it may or
may not be evaluated.
'eassert (COND)' checks COND at runtime if ENABLE_CHECKING is
defined and suppress_checking is false, and does nothing otherwise.
Emacs dies if COND is checked and is false. The suppress_checking
variable is initialized to 0 in alloc.c. Set it to 1 using a
debugger to temporarily disable aborting on detected internal
inconsistencies or error conditions.
In some cases, a good compiler may be able to optimize away the
eassert macro even if ENABLE_CHECKING is true, e.g., if XSTRING (x)
uses eassert to test STRINGP (x), but a particular use of XSTRING
is invoked only after testing that STRINGP (x) is true, making the
test redundant.
eassume is like eassert except that it also causes the compiler to
assume that COND is true afterwards, regardless of whether runtime
checking is enabled. This can improve performance in some cases,
though it can degrade performance in others. It's often suboptimal
for COND to call external functions or access volatile storage. */
#ifndef ENABLE_CHECKING
# define eassert(cond) ((void) (false && (cond))) /* Check COND compiles. */
# define eassume(cond) assume (cond)
#else /* ENABLE_CHECKING */
extern AVOID die (const char *, const char *, int);
extern bool suppress_checking EXTERNALLY_VISIBLE;
# define eassert(cond) \
(suppress_checking || (cond) \
? (void) 0 \
: die (# cond, __FILE__, __LINE__))
# define eassume(cond) \
(suppress_checking \
? assume (cond) \
: (cond) \
? (void) 0 \
: die (# cond, __FILE__, __LINE__))
#endif /* ENABLE_CHECKING */
/* Use the configure flag --enable-check-lisp-object-type to make
Lisp_Object use a struct type instead of the default int. The flag
causes CHECK_LISP_OBJECT_TYPE to be defined. */
/***** Select the tagging scheme. *****/
/* The following option controls the tagging scheme:
- USE_LSB_TAG means that we can assume the least 3 bits of pointers are
always 0, and we can thus use them to hold tag bits, without
restricting our addressing space.
If ! USE_LSB_TAG, then use the top 3 bits for tagging, thus
restricting our possible address range.
USE_LSB_TAG not only requires the least 3 bits of pointers returned by
malloc to be 0 but also needs to be able to impose a mult-of-8 alignment
on some non-GC Lisp_Objects, all of which are aligned via
GCALIGNED_UNION_MEMBER. */
enum Lisp_Bits
{
/* Number of bits in a Lisp_Object value, not counting the tag. */
VALBITS = EMACS_INT_WIDTH - GCTYPEBITS,
/* Number of bits in a fixnum value, not counting the tag. */
FIXNUM_BITS = VALBITS + 1
};
/* Number of bits in a fixnum tag; can be used in #if. */
DEFINE_GDB_SYMBOL_BEGIN (int, INTTYPEBITS)
#define INTTYPEBITS (GCTYPEBITS - 1)
DEFINE_GDB_SYMBOL_END (INTTYPEBITS)
/* The maximum value that can be stored in a EMACS_INT, assuming all
bits other than the type bits contribute to a nonnegative signed value.
This can be used in #if, e.g., '#if USE_LSB_TAG' below expands to an
expression involving VAL_MAX. */
#define VAL_MAX (EMACS_INT_MAX >> (GCTYPEBITS - 1))
/* Whether the least-significant bits of an EMACS_INT contain the tag.
On hosts where pointers-as-ints do not exceed VAL_MAX / 2, USE_LSB_TAG is:
a. unnecessary, because the top bits of an EMACS_INT are unused, and
b. slower, because it typically requires extra masking.
So, USE_LSB_TAG is true only on hosts where it might be useful. */
DEFINE_GDB_SYMBOL_BEGIN (bool, USE_LSB_TAG)
#define USE_LSB_TAG (VAL_MAX / 2 < INTPTR_MAX)
DEFINE_GDB_SYMBOL_END (USE_LSB_TAG)
/* Mask for the value (as opposed to the type bits) of a Lisp object. */
DEFINE_GDB_SYMBOL_BEGIN (EMACS_INT, VALMASK)
# define VALMASK (USE_LSB_TAG ? - (1 << GCTYPEBITS) : VAL_MAX)
DEFINE_GDB_SYMBOL_END (VALMASK)
/* Ignore 'alignas' on compilers lacking it. */
#if (!defined alignas && !defined __alignas_is_defined \
&& __STDC_VERSION__ < 202311 && __cplusplus < 201103)
# define alignas(a)
#endif
/* Minimum alignment requirement for Lisp objects, imposed by the
internal representation of tagged pointers. It is 2**GCTYPEBITS if
USE_LSB_TAG, 1 otherwise. It must be a literal integer constant,
for older versions of GCC (through at least 4.9). */
#if USE_LSB_TAG
# define GCALIGNMENT 8
# if GCALIGNMENT != 1 << GCTYPEBITS
# error "GCALIGNMENT and GCTYPEBITS are inconsistent"
# endif
#else
# define GCALIGNMENT 1
#endif
/* To cause a union to have alignment of at least GCALIGNMENT, put
GCALIGNED_UNION_MEMBER in its member list.
If a struct is always GC-aligned (either by the GC, or via
allocation in a containing union that has GCALIGNED_UNION_MEMBER)
and does not contain a GC-aligned struct or union, putting
GCALIGNED_STRUCT after its closing '}' can help the compiler
generate better code. Also, such structs should be added to the
emacs_align_type union in alloc.c.
Although these macros are reasonably portable, they are not
guaranteed on non-GCC platforms, as the C standard does not require support
for alignment to GCALIGNMENT and older compilers may ignore
alignment requests. For any type T where garbage collection
requires alignment, use verify (GCALIGNED (T)) to verify the
requirement on the current platform. Types need this check if
their objects can be allocated outside the garbage collector. For
example, struct Lisp_Symbol needs the check because of lispsym and
struct Lisp_Cons needs it because of STACK_CONS. */
#define GCALIGNED_UNION_MEMBER char alignas (GCALIGNMENT) gcaligned;
#if HAVE_STRUCT_ATTRIBUTE_ALIGNED
# define GCALIGNED_STRUCT __attribute__ ((aligned (GCALIGNMENT)))
#else
# define GCALIGNED_STRUCT
#endif
#define GCALIGNED(type) (alignof (type) % GCALIGNMENT == 0)
/* Lisp_Word is a scalar word suitable for holding a tagged pointer or
integer. Usually it is a pointer to a deliberately-incomplete type
'struct Lisp_X'. However, it is EMACS_INT when Lisp_Objects and
pointers differ in width. */
#define LISP_WORDS_ARE_POINTERS (EMACS_INT_MAX == INTPTR_MAX)
#if LISP_WORDS_ARE_POINTERS
/* TAG_PTR_INITIALLY casts to Lisp_Word and can be used in static initializers
so this typedef assumes static initializers can contain casts to pointers.
All Emacs targets support this extension to the C standard. */
typedef struct Lisp_X *Lisp_Word;
#else
typedef EMACS_INT Lisp_Word;
#endif
/* Some operations are so commonly executed that they are implemented
as macros, not functions, because otherwise runtime performance would
suffer too much when compiling with GCC without optimization.
There's no need to inline everything, just the operations that
would otherwise cause a serious performance problem.
For each such operation OP, define a macro lisp_h_OP that contains
the operation's implementation. That way, OP can be implemented
via a macro definition like this:
#define OP(x) lisp_h_OP (x)
and/or via a function definition like this:
Lisp_Object (OP) (Lisp_Object x) { return lisp_h_OP (x); }
without worrying about the implementations diverging, since
lisp_h_OP defines the actual implementation. The lisp_h_OP macros
are intended to be private to this include file, and should not be
used elsewhere. They should evaluate each argument exactly once,
so that they behave like their functional counterparts.
FIXME: Remove the lisp_h_OP macros, and define just the inline OP
functions, once "gcc -Og" (new to GCC 4.8) or equivalent works well
enough for Emacs developers. Maybe in the year 2025. See Bug#11935.
For the macros that have corresponding functions (defined later),
see these functions for commentary. */
/* Convert among the various Lisp-related types: I for EMACS_INT, L
for Lisp_Object, P for void *.
These use the following mnemonics:
XLI: Lisp_Object to Integer;
XIL: Integer to Lisp_Object;
XLP: Lisp_Object to Pointer. */
#if !CHECK_LISP_OBJECT_TYPE
# if LISP_WORDS_ARE_POINTERS
# define lisp_h_XLI(o) ((EMACS_INT) (o))
# define lisp_h_XIL(i) ((Lisp_Object) (i))
# define lisp_h_XLP(o) ((void *) (o))
# else
# define lisp_h_XLI(o) (o)
# define lisp_h_XIL(i) (i)
# define lisp_h_XLP(o) ((void *) (uintptr_t) (o))
# endif
# define lisp_h_Qnil 0
#else
# if LISP_WORDS_ARE_POINTERS
# define lisp_h_XLI(o) ((EMACS_INT) (o).i)
# define lisp_h_XIL(i) ((Lisp_Object) {(Lisp_Word) (i)})
# define lisp_h_XLP(o) ((void *) (o).i)
# else
# define lisp_h_XLI(o) ((o).i)
# define lisp_h_XIL(i) ((Lisp_Object) {i})
# define lisp_h_XLP(o) ((void *) (uintptr_t) (o).i)
# endif
# define lisp_h_Qnil {0}
#endif
#define lisp_h_CHECK_FIXNUM(x) CHECK_TYPE (FIXNUMP (x), Qfixnump, x)
#define lisp_h_CHECK_SYMBOL(x) CHECK_TYPE (SYMBOLP (x), Qsymbolp, x)
#define lisp_h_CHECK_TYPE(ok, predicate, x) \
((ok) ? (void) 0 : wrong_type_argument (predicate, x))
#define lisp_h_CONSP(x) TAGGEDP (x, Lisp_Cons)
#define lisp_h_BASE_EQ(x, y) (XLI (x) == XLI (y))
#define lisp_h_FIXNUMP(x) \
(! (((unsigned) (XLI (x) >> (USE_LSB_TAG ? 0 : FIXNUM_BITS)) \
- (unsigned) (Lisp_Int0 >> !USE_LSB_TAG)) \
& ((1 << INTTYPEBITS) - 1)))
#define lisp_h_FLOATP(x) TAGGEDP (x, Lisp_Float)
#define lisp_h_NILP(x) BASE_EQ (x, Qnil)
#define lisp_h_SYMBOL_CONSTANT_P(sym) \
(XSYMBOL (sym)->u.s.trapped_write == SYMBOL_NOWRITE)
#define lisp_h_SYMBOL_TRAPPED_WRITE_P(sym) (XSYMBOL (sym)->u.s.trapped_write)
#define lisp_h_SYMBOL_WITH_POS_P(x) PSEUDOVECTORP (x, PVEC_SYMBOL_WITH_POS)
#define lisp_h_BARE_SYMBOL_P(x) TAGGEDP (x, Lisp_Symbol)
#define lisp_h_TAGGEDP(a, tag) \
(! (((unsigned) (XLI (a) >> (USE_LSB_TAG ? 0 : VALBITS)) \
- (unsigned) (tag)) \
& ((1 << GCTYPEBITS) - 1)))
#define lisp_h_VECTORLIKEP(x) TAGGEDP (x, Lisp_Vectorlike)
#define lisp_h_XCAR(c) XCONS (c)->u.s.car
#define lisp_h_XCDR(c) XCONS (c)->u.s.u.cdr
#define lisp_h_XHASH(a) XUFIXNUM_RAW (a)
#if USE_LSB_TAG
# define lisp_h_make_fixnum_wrap(n) \
XIL ((EMACS_INT) (((EMACS_UINT) (n) << INTTYPEBITS) + Lisp_Int0))
# if defined HAVE_STATEMENT_EXPRESSIONS && defined HAVE_TYPEOF
# define lisp_h_make_fixnum(n) \
({ typeof (+(n)) lisp_h_make_fixnum_n = n; \
eassert (!FIXNUM_OVERFLOW_P (lisp_h_make_fixnum_n)); \
lisp_h_make_fixnum_wrap (lisp_h_make_fixnum_n); })
# else
# define lisp_h_make_fixnum(n) lisp_h_make_fixnum_wrap (n)
# endif
# define lisp_h_XFIXNUM_RAW(a) (XLI (a) >> INTTYPEBITS)
# define lisp_h_XTYPE(a) ((enum Lisp_Type) (XLI (a) & ~VALMASK))
#endif
/* When DEFINE_KEY_OPS_AS_MACROS, define key operations as macros to
cajole the compiler into inlining them; otherwise define them as
inline functions as this is cleaner and can be more efficient.
The default is true if the compiler is GCC-like and if function
inlining is disabled because the compiler is not optimizing or is
optimizing for size. Otherwise the default is false. */
#ifndef DEFINE_KEY_OPS_AS_MACROS
# if (defined __NO_INLINE__ \
&& ! defined __OPTIMIZE__ && ! defined __OPTIMIZE_SIZE__)
# define DEFINE_KEY_OPS_AS_MACROS true
# else
# define DEFINE_KEY_OPS_AS_MACROS false
# endif
#endif
#if DEFINE_KEY_OPS_AS_MACROS
# define XLI(o) lisp_h_XLI (o)
# define XIL(i) lisp_h_XIL (i)
# define XLP(o) lisp_h_XLP (o)
# define BARE_SYMBOL_P(x) lisp_h_BARE_SYMBOL_P (x)
# define CHECK_FIXNUM(x) lisp_h_CHECK_FIXNUM (x)
# define CHECK_SYMBOL(x) lisp_h_CHECK_SYMBOL (x)
# define CHECK_TYPE(ok, predicate, x) lisp_h_CHECK_TYPE (ok, predicate, x)
# define CONSP(x) lisp_h_CONSP (x)
# define BASE_EQ(x, y) lisp_h_BASE_EQ (x, y)
# define FLOATP(x) lisp_h_FLOATP (x)
# define FIXNUMP(x) lisp_h_FIXNUMP (x)
# define NILP(x) lisp_h_NILP (x)
# define SYMBOL_CONSTANT_P(sym) lisp_h_SYMBOL_CONSTANT_P (sym)
# define SYMBOL_TRAPPED_WRITE_P(sym) lisp_h_SYMBOL_TRAPPED_WRITE_P (sym)
# define TAGGEDP(a, tag) lisp_h_TAGGEDP (a, tag)
# define VECTORLIKEP(x) lisp_h_VECTORLIKEP (x)
# define XCAR(c) lisp_h_XCAR (c)
# define XCDR(c) lisp_h_XCDR (c)
# define XHASH(a) lisp_h_XHASH (a)
# if USE_LSB_TAG
# define make_fixnum(n) lisp_h_make_fixnum (n)
# define XFIXNUM_RAW(a) lisp_h_XFIXNUM_RAW (a)
# define XTYPE(a) lisp_h_XTYPE (a)
# endif
#endif
/* Define the fundamental Lisp data structures. */
/* This is the set of Lisp data types. If you want to define a new
data type, read the comments after Lisp_Fwd_Type definition
below. */
/* Fixnums use 2 tags, to give them one extra bit, thus
extending their range from, e.g., -2^28..2^28-1 to -2^29..2^29-1. */
#define INTMASK (EMACS_INT_MAX >> (INTTYPEBITS - 1))
#define case_Lisp_Int case Lisp_Int0: case Lisp_Int1
/* Idea stolen from GDB. Pedantic GCC complains about enum bitfields,
and xlc and Oracle Studio c99 complain vociferously about them. */
#if (defined __STRICT_ANSI__ || defined __IBMC__ \
|| (defined __SUNPRO_C && __STDC__))
#define ENUM_BF(TYPE) unsigned int
#else
#define ENUM_BF(TYPE) enum TYPE
#endif
/* Lisp_Object tagging scheme:
Tag location
Upper bits Lower bits Type Payload
000....... .......000 symbol offset from lispsym to struct Lisp_Symbol
001....... .......001 unused
01........ ........10 fixnum signed integer of FIXNUM_BITS
110....... .......011 cons pointer to struct Lisp_Cons
100....... .......100 string pointer to struct Lisp_String
101....... .......101 vectorlike pointer to union vectorlike_header
111....... .......111 float pointer to struct Lisp_Float */
enum Lisp_Type
{
/* Symbol. XSYMBOL (object) points to a struct Lisp_Symbol. */
Lisp_Symbol = 0,
/* Type 1 is currently unused. */
Lisp_Type_Unused0 = 1,
/* Fixnum. XFIXNUM (obj) is the integer value. */
Lisp_Int0 = 2,
Lisp_Int1 = USE_LSB_TAG ? 6 : 3,
/* String. XSTRING (object) points to a struct Lisp_String.
The length of the string, and its contents, are stored therein. */
Lisp_String = 4,
/* Vector of Lisp objects, or something resembling it.
XVECTOR (object) points to a struct Lisp_Vector, which contains
the size and contents. The size field also contains the type
information, if it's not a real vector object. */
Lisp_Vectorlike = 5,
/* Cons. XCONS (object) points to a struct Lisp_Cons. */
Lisp_Cons = USE_LSB_TAG ? 3 : 6,
/* Must be last entry in Lisp_Type enumeration. */
Lisp_Float = 7
};
/* These are the types of forwarding objects used in the value slot
of symbols for special built-in variables whose value is stored in
C variables. */
enum Lisp_Fwd_Type
{
Lisp_Fwd_Int, /* Fwd to a C `int' variable. */
Lisp_Fwd_Bool, /* Fwd to a C boolean var. */
Lisp_Fwd_Obj, /* Fwd to a C Lisp_Object variable. */
Lisp_Fwd_Buffer_Obj, /* Fwd to a Lisp_Object field of buffers. */
Lisp_Fwd_Kboard_Obj /* Fwd to a Lisp_Object field of kboards. */
};
/* If you want to define a new Lisp data type, here are some
instructions.
First, there are already a couple of Lisp types that can be used if
your new type does not need to be exposed to Lisp programs nor
displayed to users. These are Lisp_Misc_Ptr and PVEC_OTHER,
which are both vectorlike objects. The former
is suitable for stashing a pointer in a Lisp object; the pointer
might be to some low-level C object that contains auxiliary
information. The latter is useful for vector-like Lisp objects
that need to be used as part of other objects, but which are never
shown to users or Lisp code (search for PVEC_OTHER in xterm.c for
an example).
These two types don't look pretty when printed, so they are
unsuitable for Lisp objects that can be exposed to users.
To define a new data type, add a pseudovector subtype by extending
the pvec_type enumeration. A pseudovector provides one or more
slots for Lisp objects, followed by struct members that are
accessible only from C.
There is no way to explicitly free a Lisp Object; only the garbage
collector frees them.
For a new pseudovector, it's highly desirable to limit the size
of your data type by VBLOCK_BYTES_MAX bytes (defined in alloc.c).
Otherwise you will need to change sweep_vectors (also in alloc.c).
Then you will need to add switch branches in print.c (in
print_object, to print your object, and possibly also in
print_preprocess) and to alloc.c, to mark your object (in
mark_object) and to free it (in gc_sweep). The latter is also the
right place to call any code specific to your data type that needs
to run when the object is recycled -- e.g., free any additional
resources allocated for it that are not Lisp objects. You can even
make a pointer to the function that frees the resources a slot in
your object -- this way, the same object could be used to represent
several disparate C structures.
In addition, you need to add switch branches in data.c for Fcl_type_of
and `cl--define-builtin-type` in lisp/emacs-lisp/cl-preloaded.el. */
/* A Lisp_Object is a tagged pointer or integer. Ordinarily it is a
Lisp_Word. However, if CHECK_LISP_OBJECT_TYPE, it is a wrapper
around Lisp_Word, to help catch thinkos like 'Lisp_Object x = 0;'.
LISP_INITIALLY (W) initializes a Lisp object with a tagged value
that is a Lisp_Word W. It can be used in a static initializer. */
#ifdef CHECK_LISP_OBJECT_TYPE
typedef struct Lisp_Object { Lisp_Word i; } Lisp_Object;
# define LISP_OBJECT_IS_STRUCT
# define LISP_INITIALLY(w) {w}
# undef CHECK_LISP_OBJECT_TYPE
enum CHECK_LISP_OBJECT_TYPE { CHECK_LISP_OBJECT_TYPE = true };
#else
typedef Lisp_Word Lisp_Object;
# define LISP_INITIALLY(w) (w)
enum CHECK_LISP_OBJECT_TYPE { CHECK_LISP_OBJECT_TYPE = false };
#endif
/* Forward declarations. */
/* Defined in this file. */
INLINE void set_sub_char_table_contents (Lisp_Object, ptrdiff_t,
Lisp_Object);
/* Defined in bignum.c. */
extern int check_int_nonnegative (Lisp_Object);
extern intmax_t check_integer_range (Lisp_Object, intmax_t, intmax_t);
extern double bignum_to_double (Lisp_Object) ATTRIBUTE_CONST;
extern Lisp_Object make_bigint (intmax_t);
extern Lisp_Object make_biguint (uintmax_t);
extern uintmax_t check_uinteger_max (Lisp_Object, uintmax_t);
/* Defined in chartab.c. */
extern Lisp_Object char_table_ref (Lisp_Object, int) ATTRIBUTE_PURE;
extern void char_table_set (Lisp_Object, int, Lisp_Object);
/* Defined in data.c. */
extern AVOID args_out_of_range_3 (Lisp_Object, Lisp_Object, Lisp_Object);
extern AVOID wrong_type_argument (Lisp_Object, Lisp_Object);
extern Lisp_Object default_value (Lisp_Object symbol);
extern void defalias (Lisp_Object symbol, Lisp_Object definition);
extern char *fixnum_to_string (EMACS_INT number, char *buffer, char *end);
/* Defined in emacs.c. */
/* Set after Emacs has started up the first time.
Prevents reinitialization of the Lisp world and keymaps on
subsequent starts. */
extern bool initialized;
extern struct gflags
{
/* True means this Emacs instance was born to dump. */
bool will_dump_ : 1;
bool will_bootstrap_ : 1;
#ifdef HAVE_PDUMPER
/* Set in an Emacs process that will likely dump with pdumper; all
Emacs processes may dump with pdumper, however. */
bool will_dump_with_pdumper_ : 1;
/* Set in an Emacs process that has been restored from a portable
dump. */
bool dumped_with_pdumper_ : 1;
#endif
#ifdef HAVE_UNEXEC
bool will_dump_with_unexec_ : 1;
/* Set in an Emacs process that has been restored from an unexec
dump. */
bool dumped_with_unexec_ : 1;
/* We promise not to unexec: useful for hybrid malloc. */
bool will_not_unexec_ : 1;
#endif
} gflags;
INLINE bool
will_dump_p (void)
{
#if HAVE_PDUMPER || defined HAVE_UNEXEC
return gflags.will_dump_;
#else
return false;
#endif
}
INLINE bool
will_bootstrap_p (void)
{
#if HAVE_PDUMPER || defined HAVE_UNEXEC
return gflags.will_bootstrap_;
#else
return false;
#endif
}
INLINE bool
will_dump_with_pdumper_p (void)
{
#if HAVE_PDUMPER
return gflags.will_dump_with_pdumper_;
#else
return false;
#endif
}
INLINE bool
dumped_with_pdumper_p (void)
{
#if HAVE_PDUMPER
return gflags.dumped_with_pdumper_;
#else
return false;
#endif
}
INLINE bool
will_dump_with_unexec_p (void)
{
#ifdef HAVE_UNEXEC
return gflags.will_dump_with_unexec_;
#else
return false;
#endif
}
INLINE bool
dumped_with_unexec_p (void)
{
#ifdef HAVE_UNEXEC
return gflags.dumped_with_unexec_;
#else
return false;
#endif
}
/* This function is the opposite of will_dump_with_unexec_p(), except
that it returns false before main runs. It's important to use
gmalloc for any pre-main allocations if we're going to unexec. */
INLINE bool
definitely_will_not_unexec_p (void)
{
#ifdef HAVE_UNEXEC
return gflags.will_not_unexec_;
#else
return true;
#endif
}
/* Defined in floatfns.c. */
extern double extract_float (Lisp_Object);
/* Low-level conversion and type checking. */
/* Convert among various types use to implement Lisp_Object. At the
machine level, these operations may widen or narrow their arguments
if pointers differ in width from EMACS_INT; otherwise they are
no-ops. */
INLINE EMACS_INT
(XLI) (Lisp_Object o)
{
return lisp_h_XLI (o);
}
INLINE Lisp_Object
(XIL) (EMACS_INT i)
{
return lisp_h_XIL (i);
}
INLINE void *
(XLP) (Lisp_Object o)
{
return lisp_h_XLP (o);
}
/* Extract A's type. */
INLINE enum Lisp_Type
(XTYPE) (Lisp_Object a)
{
#if USE_LSB_TAG
return lisp_h_XTYPE (a);
#else
EMACS_UINT i = XLI (a);
return USE_LSB_TAG ? i & ~VALMASK : i >> VALBITS;
#endif
}
/* True if A has type tag TAG.
Equivalent to XTYPE (a) == TAG, but often faster. */
INLINE bool
(TAGGEDP) (Lisp_Object a, enum Lisp_Type tag)
{
return lisp_h_TAGGEDP (a, tag);
}
INLINE void
(CHECK_TYPE) (int ok, Lisp_Object predicate, Lisp_Object x)
{
lisp_h_CHECK_TYPE (ok, predicate, x);
}
/* Extract A's pointer value, assuming A's Lisp type is TYPE and the
extracted pointer's type is CTYPE *. When !USE_LSB_TAG this simply
extracts A's low-order bits, as (uintptr_t) LISP_WORD_TAG (type) is
always zero then. */
#define XUNTAG(a, type, ctype) \
((ctype *) ((uintptr_t) XLP (a) - (uintptr_t) LISP_WORD_TAG (type)))
/* A forwarding pointer to a value. It uses a generic pointer to
avoid alignment bugs that could occur if it used a pointer to a
union of the possible values (struct Lisp_Objfwd, struct
Lisp_Intfwd, etc.). The pointer is packaged inside a struct to
help static checking. */
typedef struct { void const *fwdptr; } lispfwd;
/* Interned state of a symbol. */
enum symbol_interned
{
SYMBOL_UNINTERNED, /* not interned anywhere */
SYMBOL_INTERNED, /* interned but not in initial obarray */
SYMBOL_INTERNED_IN_INITIAL_OBARRAY /* interned in initial obarray */
};
enum symbol_redirect
{
SYMBOL_PLAINVAL, /* plain var, value is in the `value' field */
SYMBOL_VARALIAS, /* var alias, value is really in the `alias' symbol */
SYMBOL_LOCALIZED, /* localized var, value is in the `blv' object */
SYMBOL_FORWARDED /* forwarding var, value is in `forward' */
};
enum symbol_trapped_write
{
SYMBOL_UNTRAPPED_WRITE, /* normal case, just set the value */
SYMBOL_NOWRITE, /* constant, cannot set, e.g. nil, t, :keyword */
SYMBOL_TRAPPED_WRITE /* trap the write, call watcher functions */
};
struct Lisp_Symbol
{
union
{
struct
{
bool_bf gcmarkbit : 1;
/* Indicates where the value can be found. */
ENUM_BF (symbol_redirect) redirect : 2;
ENUM_BF (symbol_trapped_write) trapped_write : 2;
/* Interned state of the symbol. */
ENUM_BF (symbol_interned) interned : 2;
/* True means that this variable has been explicitly declared
special (with `defvar' etc), and shouldn't be lexically bound. */
bool_bf declared_special : 1;
/* True if pointed to from purespace and hence can't be GC'd. */
bool_bf pinned : 1;
/* The symbol's name, as a Lisp string. */
Lisp_Object name;
/* Value of the symbol or Qunbound if unbound. Which alternative of the
union is used depends on the `redirect' field above. */
union {
Lisp_Object value;
struct Lisp_Symbol *alias;
struct Lisp_Buffer_Local_Value *blv;
lispfwd fwd;
} val;
/* Function value of the symbol or Qnil if not fboundp. */
Lisp_Object function;
/* The symbol's property list. */
Lisp_Object plist;
/* Next symbol in obarray bucket, if the symbol is interned. */
struct Lisp_Symbol *next;
} s;
GCALIGNED_UNION_MEMBER
} u;
};
verify (GCALIGNED (struct Lisp_Symbol));
/* Declare a Lisp-callable function. The MAXARGS parameter has the same
meaning as in the DEFUN macro, and is used to construct a prototype. */
/* We can use the same trick as in the DEFUN macro to generate the
appropriate prototype. */
#define EXFUN(fnname, maxargs) \
extern Lisp_Object fnname DEFUN_ARGS_ ## maxargs
/* Note that the weird token-substitution semantics of ANSI C makes
this work for MANY and UNEVALLED. */
#define DEFUN_ARGS_MANY (ptrdiff_t, Lisp_Object *)
#define DEFUN_ARGS_UNEVALLED (Lisp_Object)
#define DEFUN_ARGS_0 (void)
#define DEFUN_ARGS_1 (Lisp_Object)
#define DEFUN_ARGS_2 (Lisp_Object, Lisp_Object)
#define DEFUN_ARGS_3 (Lisp_Object, Lisp_Object, Lisp_Object)
#define DEFUN_ARGS_4 (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object)
#define DEFUN_ARGS_5 (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object, \
Lisp_Object)
#define DEFUN_ARGS_6 (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object, \
Lisp_Object, Lisp_Object)
#define DEFUN_ARGS_7 (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object, \
Lisp_Object, Lisp_Object, Lisp_Object)
#define DEFUN_ARGS_8 (Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object, \
Lisp_Object, Lisp_Object, Lisp_Object, Lisp_Object)
/* Lisp_Word_tag is big enough for a possibly-shifted tag, to be
added to a pointer value for conversion to a Lisp_Word. */
#if LISP_WORDS_ARE_POINTERS
typedef uintptr_t Lisp_Word_tag;
#else
typedef EMACS_UINT Lisp_Word_tag;
#endif
/* A integer value tagged with TAG, and otherwise all zero. */
#define LISP_WORD_TAG(tag) \
((Lisp_Word_tag) (tag) << (USE_LSB_TAG ? 0 : VALBITS))
/* An initializer for a Lisp_Object that contains TAG along with P.
P can be a pointer or an integer. The result is usable in a static
initializer if TAG and P are both integer constant expressions. */
#define TAG_PTR_INITIALLY(tag, p) \
LISP_INITIALLY ((Lisp_Word) ((uintptr_t) (p) + LISP_WORD_TAG (tag)))
/* LISPSYM_INITIALLY (Qfoo) is equivalent to Qfoo except it is
designed for use as a (possibly static) initializer. */
#define LISPSYM_INITIALLY(name) \
TAG_PTR_INITIALLY (Lisp_Symbol, (intptr_t) ((i##name) * sizeof *lispsym))
/* Declare extern constants for Lisp symbols. These can be helpful
when using a debugger like GDB, on older platforms where the debug
format does not represent C macros. However, they are unbounded
and would just be asking for trouble if checking pointer bounds. */
#define DEFINE_LISP_SYMBOL(name) \
DEFINE_GDB_SYMBOL_BEGIN (Lisp_Object, name) \
DEFINE_GDB_SYMBOL_END (LISPSYM_INITIALLY (name))
/* The index of the C-defined Lisp symbol SYM.
This can be used in a static initializer. */
#define SYMBOL_INDEX(sym) i##sym
/* By default, define macros for Qt, etc., as this leads to a bit
better performance in the core Emacs interpreter. A plugin can
define DEFINE_NON_NIL_Q_SYMBOL_MACROS to be false, to be portable to
other Emacs instances that assign different values to Qt, etc. */
#ifndef DEFINE_NON_NIL_Q_SYMBOL_MACROS
# define DEFINE_NON_NIL_Q_SYMBOL_MACROS true
#endif
/* True if N is a power of 2. N should be positive. */
#define POWER_OF_2(n) (((n) & ((n) - 1)) == 0)
/* Return X rounded to the next multiple of Y. Y should be positive,
and Y - 1 + X should not overflow. Arguments should not have side
effects, as they are evaluated more than once. Tune for Y being a
power of 2. */
#define ROUNDUP(x, y) (POWER_OF_2 (y) \
? ((y) - 1 + (x)) & ~ ((y) - 1) \
: ((y) - 1 + (x)) - ((y) - 1 + (x)) % (y))
#include <globals.h>
/* Header of vector-like objects. This documents the layout constraints on
vectors and pseudovectors (objects of PVEC_xxx subtype). It also prevents
compilers from being fooled by Emacs's type punning: XSETPSEUDOVECTOR
and PSEUDOVECTORP cast their pointers to union vectorlike_header *,
because when two such pointers potentially alias, a compiler won't
incorrectly reorder loads and stores to their size fields. See
Bug#8546. This union formerly contained more members, and there's
no compelling reason to change it to a struct merely because the
number of members has been reduced to one. */
union vectorlike_header
{
/* The `size' header word, W bits wide, has one of two forms
discriminated by the second-highest bit (PSEUDOVECTOR_FLAG):
1 1 W-2
+---+---+-------------------------------------+
| M | 0 | SIZE | vector
+---+---+-------------------------------------+
1 1 W-32 6 12 12
+---+---+--------+------+----------+----------+
| M | 1 | unused | TYPE | RESTSIZE | LISPSIZE | pseudovector
+---+---+--------+------+----------+----------+
M (ARRAY_MARK_FLAG) holds the GC mark bit.
SIZE is the length (number of slots) of a regular Lisp vector,
and the object layout is struct Lisp_Vector.
TYPE is the pseudovector subtype (enum pvec_type).
LISPSIZE is the number of Lisp_Object fields at the beginning of the
object (after the header). These are always traced by the GC.
RESTSIZE is the number of fields (in word_size units) following.
These are not automatically traced by the GC.
For PVEC_BOOL and statically allocated PVEC_SUBR, RESTSIZE is 0.
(The block size for PVEC_BOOL is computed from its own size
field, to avoid being restricted by the 12-bit RESTSIZE field.)
*/
ptrdiff_t size;
};
struct Lisp_Symbol_With_Pos
{
union vectorlike_header header;
Lisp_Object sym; /* A symbol */
Lisp_Object pos; /* A fixnum */
} GCALIGNED_STRUCT;