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Bignums avoid both custom GMP allocator and finalizers

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* libguile/deprecated.c (make_bignum): Move here from numbers.c, to
support scm_i_long2big etc.
(scm_i_big2dbl):
(scm_i_long2big):
(scm_i_ulong2big):
(scm_i_clonebig):
(scm_i_normbig): Deprecate.
(scm_install_gmp_memory_functions): Deprecate, happily!  SCM bignums now
have digits allocated inline with the bignum itself, so they are
completely transparent to the GC already.  The price is that if GMP ever
allocates digits via the MPZ API, those digits then have to be copied
back into managed memory.  But we avoid having to install finalizers and
we avoid having to muck with GMP's allocator.
* libguile/numbers.c (scm_from_mpz): Use scm_integer_from_mpz.
(scm_init_numbers): Never muck with GMP's allocators.
* doc/ref/guile-invoke.texi (Environment Variables): Remove note about
GUILE_INSTALL_GMP_MEMORY_FUNCTIONS.
* meta/build-env.in: No need to set GUILE_INSTALL_GMP_MEMORY_FUNCTIONS.
This commit is contained in:
Andy Wingo 2022-01-07 14:01:52 +01:00
parent a0765f564a
commit aa5455ea98
6 changed files with 113 additions and 201 deletions
Download patch file Download diff file Expand all files Collapse all files

15
doc/ref/guile-invoke.texi
View file

@ -1,6 +1,6 @@
@c -*-texinfo-*-
@c This is part of the GNU Guile Reference Manual.
@c Copyright (C) 1996-1997,2000-2005,2010-2011,2013-2014,2016,2019,2021
@c Copyright (C) 1996-1997,2000-2005,2010-2011,2013-2014,2016,2019,2021-2022
@c Free Software Foundation, Inc.
@c See the file guile.texi for copying conditions.
@ -424,19 +424,6 @@ Guile uses the environment variable @env{HOME}, the name of your home
directory, to locate various files, such as @file{.guile} or
@file{.guile_history}.
@item GUILE_INSTALL_GMP_MEMORY_FUNCTIONS
@vindex GUILE_INSTALL_GMP_MEMORY_FUNCTIONS
Guile uses the GNU multi-precision (GMP) library to implement its bigint
support. It can use an included minimal version of GMP, or the system
version, which may be more optimal. If Guile is the sole user of GMP in
the process, Guile can tell GMP to allocate its digits using
garbage-collected memory. This can be significantly faster. However
this approach is unsafe if there are other libraries loaded that use
libgmp, such as the GnuTLS library. The default is for Guile to do the
fastest safe thing: use the garbage collector for GMP when using the
included ``mini-GMP'', but not otherwise. Set this variable to nonzero
to force GMP to use garbage-collected memory, even when using system GC.
@item GUILE_JIT_THRESHOLD
@vindex GUILE_JIT_THRESHOLD
Guile has a just-in-time (JIT) code generator that makes running Guile

90
libguile/deprecated.c
View file

@ -36,6 +36,7 @@
#include "dynl.h"
#include "eval.h"
#include "foreign.h"
#include "finalizers.h"
#include "generalized-vectors.h"
#include "gc.h"
#include "gsubr.h"
@ -690,6 +691,95 @@ SCM_DEFINE (scm_dynamic_unlink, "dynamic-unlink", 1, 0, 0, (SCM obj), "")
#undef FUNC_NAME
static void
finalize_bignum (void *ptr, void *data)
{
SCM bignum;
bignum = SCM_PACK_POINTER (ptr);
mpz_clear (SCM_I_BIG_MPZ (bignum));
}
static SCM
make_bignum (void)
{
scm_t_bits *p;
/* Allocate one word for the type tag and enough room for an `mpz_t'. */
p = scm_gc_malloc_pointerless (sizeof (scm_t_bits) + sizeof (mpz_t),
"bignum");
p[0] = scm_tc16_big;
scm_i_set_finalizer (p, finalize_bignum, NULL);
return SCM_PACK (p);
}
/* scm_i_big2dbl() rounds to the closest representable double,
in accordance with R5RS exact->inexact. */
double
scm_i_big2dbl (SCM b)
{
scm_c_issue_deprecation_warning
("scm_i_big2dbl is deprecated. Use scm_to_double instead.");
return scm_to_double (b);
}
SCM
scm_i_long2big (long x)
{
scm_c_issue_deprecation_warning
("scm_i_long2big is deprecated. Use scm_from_long instead.");
/* Return a newly created bignum initialized to X. */
SCM z = make_bignum ();
mpz_init_set_si (SCM_I_BIG_MPZ (z), x);
return z;
}
SCM
scm_i_ulong2big (unsigned long x)
{
scm_c_issue_deprecation_warning
("scm_i_ulong2big is deprecated. Use scm_from_ulong instead.");
/* Return a newly created bignum initialized to X. */
SCM z = make_bignum ();
mpz_init_set_ui (SCM_I_BIG_MPZ (z), x);
return z;
}
SCM
scm_i_clonebig (SCM src_big, int same_sign_p)
{
scm_c_issue_deprecation_warning
("scm_i_clonebig is deprecated. Use scm_to_mpz/scm_from_mpz instead.");
/* Copy src_big's value, negate it if same_sign_p is false, and return. */
SCM z = make_bignum ();
scm_to_mpz (src_big, SCM_I_BIG_MPZ (z));
if (!same_sign_p)
mpz_neg (SCM_I_BIG_MPZ (z), SCM_I_BIG_MPZ (z));
return z;
}
SCM
scm_i_normbig (SCM b)
{
scm_c_issue_deprecation_warning
("scm_i_normbig is deprecated. Direct bignum bit manipulation is not "
"supported.");
/* convert a big back to a fixnum if it'll fit */
/* presume b is a bignum */
if (mpz_fits_slong_p (SCM_I_BIG_MPZ (b)))
{
scm_t_inum val = mpz_get_si (SCM_I_BIG_MPZ (b));
if (SCM_FIXABLE (val))
b = SCM_I_MAKINUM (val);
}
return b;
}
int scm_install_gmp_memory_functions;
void

15
libguile/deprecated.h
View file

@ -1,7 +1,7 @@
#ifndef SCM_DEPRECATED_H
#define SCM_DEPRECATED_H
/* Copyright 2003-2007,2009-2018,2020,2021
/* Copyright 2003-2007,2009-2018,2020-2022
Free Software Foundation, Inc.
This file is part of Guile.
@ -146,6 +146,19 @@ SCM_DEPRECATED SCM scm_copy_tree (SCM obj);
SCM_DEPRECATED SCM scm_dynamic_unlink (SCM obj);
/* Each bignum is just an mpz_t stored in a double cell starting at word 1. */
#if defined BUILDING_LIBGUILE || SCM_ENABLE_MINI_GMP == 0
#define SCM_I_BIG_MPZ(x) (*((mpz_t *) (SCM_CELL_OBJECT_LOC((x),1))))
#endif
SCM_DEPRECATED int scm_install_gmp_memory_functions;
SCM_DEPRECATED SCM scm_i_normbig (SCM x);
SCM_DEPRECATED double scm_i_big2dbl (SCM b);
SCM_DEPRECATED SCM scm_i_long2big (long n);
SCM_DEPRECATED SCM scm_i_ulong2big (unsigned long n);
SCM_DEPRECATED SCM scm_i_clonebig (SCM src_big, int same_sign_p);
void scm_i_init_deprecated (void);
#endif

161
libguile/numbers.c
View file

@ -160,25 +160,6 @@ VARARG_MPZ_ITERATOR (mpz_clear)
*/
/* the macro above will not work as is with fractions */
/* In the context of Guile, it's most efficient for GMP to use libgc to
allocate MPZ values. That way Guile doesn't need to install
finalizers, which have significant overhead. Using libgc to allocate
digits also allows Guile's GC to adequately measure the memory cost
of MPZ values.
However, if the Guile process is linked to some other user of GMP,
then probably the references from the other user of GMP to MPZ values
aren't visible to the garbage collector. So libgc could prematurely
collect values from that other GMP user.
This isn't theoretical -- it happens for Guile-GnuTLS. GnuTLS uses
GMP, and so does Guile. But if Guile installs libgc as the allocator
for MPZ values, we break GnuTLS.
Therefore we only install libgc as the GMP allocator if we are using
mini-gmp, which we know isn't shared with any external library. */
int scm_install_gmp_memory_functions = SCM_ENABLE_MINI_GMP;
static SCM flo0;
static SCM exactly_one_half;
static SCM flo_log10e;
@ -234,132 +215,6 @@ scm_from_complex_double (complex double z)
/* Clear the `mpz_t' embedded in bignum PTR. */
static void
finalize_bignum (void *ptr, void *data)
{
SCM bignum;
bignum = SCM_PACK_POINTER (ptr);
mpz_clear (SCM_I_BIG_MPZ (bignum));
}
/* The next three functions (custom_libgmp_*) are passed to
mp_set_memory_functions (in GMP) so that memory used by the digits
themselves is known to the garbage collector. This is needed so
that GC will be run at appropriate times. Otherwise, a program which
creates many large bignums would malloc a huge amount of memory
before the GC runs. */
static void *
custom_gmp_malloc (size_t alloc_size)
{
return scm_gc_malloc_pointerless (alloc_size, "GMP");
}
static void *
custom_gmp_realloc (void *old_ptr, size_t old_size, size_t new_size)
{
return scm_gc_realloc (old_ptr, old_size, new_size, "GMP");
}
static void
custom_gmp_free (void *ptr, size_t size)
{
/* Do nothing: all memory allocated by GMP is under GC control and
will be freed when needed. */
}
/* Return a new uninitialized bignum. */
static inline SCM
make_bignum (void)
{
scm_t_bits *p;
/* Allocate one word for the type tag and enough room for an `mpz_t'. */
p = scm_gc_malloc (sizeof (scm_t_bits) + sizeof (mpz_t),
"bignum");
p[0] = scm_tc16_big;
/* When the 'custom_gmp_*' functions are in use, no need to set a
finalizer since allocated memory is under GC control. In other
cases, set a finalizer to call 'mpz_clear', which is expensive. */
if (!scm_install_gmp_memory_functions)
scm_i_set_finalizer (p, finalize_bignum, NULL);
return SCM_PACK (p);
}
SCM
scm_i_long2big (long x)
{
/* Return a newly created bignum initialized to X. */
SCM z = make_bignum ();
mpz_init_set_si (SCM_I_BIG_MPZ (z), x);
return z;
}
SCM
scm_i_ulong2big (unsigned long x)
{
/* Return a newly created bignum initialized to X. */
SCM z = make_bignum ();
mpz_init_set_ui (SCM_I_BIG_MPZ (z), x);
return z;
}
SCM
scm_i_clonebig (SCM src_big, int same_sign_p)
{
/* Copy src_big's value, negate it if same_sign_p is false, and return. */
SCM z = make_bignum ();
mpz_init_set (SCM_I_BIG_MPZ (z), SCM_I_BIG_MPZ (src_big));
if (!same_sign_p)
mpz_neg (SCM_I_BIG_MPZ (z), SCM_I_BIG_MPZ (z));
return z;
}
/* scm_i_big2dbl() rounds to the closest representable double,
in accordance with R5RS exact->inexact. */
double
scm_i_big2dbl (SCM b)
{
return scm_integer_to_double_z (scm_bignum (b));
}
SCM
scm_i_normbig (SCM b)
{
/* convert a big back to a fixnum if it'll fit */
/* presume b is a bignum */
if (mpz_fits_slong_p (SCM_I_BIG_MPZ (b)))
{
scm_t_inum val = mpz_get_si (SCM_I_BIG_MPZ (b));
if (SCM_FIXABLE (val))
b = SCM_I_MAKINUM (val);
}
return b;
}
static SCM_C_INLINE_KEYWORD SCM
scm_i_mpz2num (mpz_t b)
{
/* convert a mpz number to a SCM number. */
if (mpz_fits_slong_p (b))
{
scm_t_inum val = mpz_get_si (b);
if (SCM_FIXABLE (val))
return SCM_I_MAKINUM (val);
}
{
SCM z = make_bignum ();
mpz_init_set (SCM_I_BIG_MPZ (z), b);
return z;
}
}
/* Make the ratio NUMERATOR/DENOMINATOR, where:
1. NUMERATOR and DENOMINATOR are exact integers
2. NUMERATOR and DENOMINATOR are reduced to lowest terms: gcd(n,d) == 1 */
@ -6938,7 +6793,7 @@ scm_to_mpz (SCM val, mpz_t rop)
SCM
scm_from_mpz (mpz_t val)
{
return scm_i_mpz2num (val);
return scm_integer_from_mpz (val);
}
int
@ -7324,20 +7179,6 @@ SCM_PRIMITIVE_GENERIC (scm_sqrt, "sqrt", 1, 0, 0,
void
scm_init_numbers ()
{
/* Give the user the chance to force the use of libgc to manage gmp
digits, if we know there are no external GMP users in this process.
Can be an important optimization for those who link external GMP,
before we switch to the MPN API. */
if (!SCM_ENABLE_MINI_GMP)
scm_install_gmp_memory_functions
= scm_getenv_int ("GUILE_INSTALL_GMP_MEMORY_FUNCTIONS",
scm_install_gmp_memory_functions);
if (scm_install_gmp_memory_functions)
mp_set_memory_functions (custom_gmp_malloc,
custom_gmp_realloc,
custom_gmp_free);
/* It may be possible to tune the performance of some algorithms by using
* the following constants to avoid the creation of bignums. Please, before
* using these values, remember the two rules of program optimization:

18
libguile/numbers.h
View file

@ -1,7 +1,7 @@
#ifndef SCM_NUMBERS_H
#define SCM_NUMBERS_H
/* Copyright 1995-1996,1998,2000-2006,2008-2011,2013-2014,2016-2018,2021,2022
/* Copyright 1995-1996,1998,2000-2006,2008-2011,2013-2014,2016-2018,2021-2022
Free Software Foundation, Inc.
This file is part of Guile.
@ -168,11 +168,6 @@ typedef long scm_t_inum;
#define SCM_COMPLEX_REAL(x) (((scm_t_complex *) SCM2PTR (x))->real)
#define SCM_COMPLEX_IMAG(x) (((scm_t_complex *) SCM2PTR (x))->imag)
/* Each bignum is just an mpz_t stored in a double cell starting at word 1. */
#if defined BUILDING_LIBGUILE || SCM_ENABLE_MINI_GMP == 0
#define SCM_I_BIG_MPZ(x) (*((mpz_t *) (SCM_CELL_OBJECT_LOC((x),1))))
#endif
#define SCM_BIGP(x) (SCM_HAS_TYP16 (x, scm_tc16_big))
#define SCM_NUMBERP(x) (SCM_I_INUMP(x) || SCM_NUMP(x))
@ -203,7 +198,6 @@ typedef struct scm_t_complex
double imag;
} scm_t_complex;
SCM_API SCM scm_exact_p (SCM x);
@ -346,13 +340,6 @@ SCM_INTERNAL SCM scm_i_product (SCM x, SCM y, SCM rest);
SCM_INTERNAL SCM scm_i_divide (SCM x, SCM y, SCM rest);
SCM_INTERNAL SCM scm_i_exact_integer_sqrt (SCM k);
/* bignum internal functions */
SCM_API /* FIXME: not internal */ SCM scm_i_normbig (SCM x);
SCM_API /* FIXME: not internal */ double scm_i_big2dbl (SCM b);
SCM_API /* FIXME: not internal */ SCM scm_i_long2big (long n);
SCM_API /* FIXME: not internal */ SCM scm_i_ulong2big (unsigned long n);
SCM_API /* FIXME: not internal */ SCM scm_i_clonebig (SCM src_big, int same_sign_p);
/* ratio functions */
SCM_API SCM scm_rationalize (SCM x, SCM err);
SCM_API SCM scm_numerator (SCM z);
@ -607,9 +594,6 @@ SCM_API double scm_c_angle (SCM z);
SCM_API int scm_is_number (SCM val);
/* If nonzero, tell gmp to use GC_malloc for its allocations. */
SCM_API int scm_install_gmp_memory_functions;
SCM_INTERNAL void scm_init_numbers (void);

5
meta/build-env.in
View file

@ -1,6 +1,6 @@
#!/bin/sh
# Copyright (C) 2003, 2006, 2008-2012, 2016, 2017, 2021 Free Software Foundation
# Copyright (C) 2003, 2006, 2008-2012, 2016, 2017, 2021, 2022 Free Software Foundation
#
# This file is part of GNU Guile.
#
@ -90,9 +90,6 @@ done
export LTDL_LIBRARY_PATH
export DYLD_LIBRARY_PATH
GUILE_INSTALL_GMP_MEMORY_FUNCTIONS=1
export GUILE_INSTALL_GMP_MEMORY_FUNCTIONS
if [ x"$PKG_CONFIG_PATH" = x ]
then
PKG_CONFIG_PATH="${top_builddir}/meta"